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WO2019142518A1 - Dispositif de détection de type transmissif, dispositif de détection de milieu flottant et dispositif de formation d'images - Google Patents

Dispositif de détection de type transmissif, dispositif de détection de milieu flottant et dispositif de formation d'images Download PDF

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Publication number
WO2019142518A1
WO2019142518A1 PCT/JP2018/044397 JP2018044397W WO2019142518A1 WO 2019142518 A1 WO2019142518 A1 WO 2019142518A1 JP 2018044397 W JP2018044397 W JP 2018044397W WO 2019142518 A1 WO2019142518 A1 WO 2019142518A1
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WO
WIPO (PCT)
Prior art keywords
light
medium
unit
openings
sheet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2018/044397
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English (en)
Japanese (ja)
Inventor
橋本　昌彦
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujifilm Corp
Original Assignee
Fujifilm Corp
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Filing date
Publication date
Application filed by Fujifilm Corp filed Critical Fujifilm Corp
Priority to JP2019565747A priority Critical patent/JP6886049B2/ja
Publication of WO2019142518A1 publication Critical patent/WO2019142518A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J11/00—Devices or arrangements  of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
    • B41J11/0095—Detecting means for copy material, e.g. for detecting or sensing presence of copy material or its leading or trailing end
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/14—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors by photoelectric feelers or detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
    • B41J13/10—Sheet holders, retainers, movable guides, or stationary guides
    • B41J13/22—Clamps or grippers
    • B41J13/223—Clamps or grippers on rotatable drums

Definitions

  • the present invention relates to a transmission detection apparatus, a medium floating detection apparatus, and an image forming apparatus, and in particular, a detection technology using a transmission type sensor having a light emitting unit and a light receiving unit, and a medium floating detection apparatus to which the detection technology is applied. And an image forming apparatus.
  • Patent Documents 1 and 2 There is known a method of detecting "lifting" caused by wrinkles or bending of a medium to be transported using a transmission type laser sensor having a light emitting unit and a light receiving unit.
  • the detection beam is projected along the medium surface of the medium to be conveyed in the medium width direction orthogonal to the direction of conveyance of the medium to be conveyed.
  • the beam is blocked due to the floating by a certain height or more, and the amount of light received by the light receiving unit is reduced. Therefore, by comparing the amount of light received by the light receiving unit with a preset threshold value, it is possible to determine the presence or absence of floating above a certain height. That is, when the amount of light received by the light receiving unit falls below the threshold, it is possible to detect floating of a certain height or more.
  • Such medium floating detection is performed, for example, in order to prevent the ink jet head from being damaged by the contact between the ink jet head and the floating of the paper which is the transported medium in the ink jet printing apparatus.
  • the ink jet printing apparatus described in Patent Document 3 is configured to stop the drum for conveying the sheet and retract the recording head to the maintenance position outside the drum when the sheet floating sensor detects the sheet floating that exceeds the allowable range. It is disclosed. "Paper” corresponds to a medium to be transported.
  • the ink jet printing apparatus described in Patent Document 4 temporarily retracts the recording head away from the sheet conveyance surface without stopping the sheet conveyance without stopping the sheet conveyance. After passing the generated sheet, the position of the recording head is returned to the original printing position to resume printing.
  • a configuration may be considered in which a plurality of transmission type laser sensors are arrayed according to the type of height to be detected.
  • the configuration in which a plurality of transmission type laser sensors are arrayed is expensive, and the optical axes of the individual laser sensors must be adjusted, which makes the adjustment operation complicated.
  • positioning several laser sensors arises.
  • the beam of one laser sensor is divided into a plurality of beams through an aperture member having a plurality of openings for light passage, and threshold processing for the light quantity received by the light receiving unit is performed. It is conceivable to carry out multi-step float detection by multi-step.
  • Each of the above-described problems is not limited to the application for detecting the floating of the medium to be transported, but is a problem common to transmission-type detection devices using a plurality of beams.
  • the present invention has been made in view of such circumstances, and in order to solve at least one of the plurality of problems described above, to provide a transmission type detection device capable of realizing highly accurate detection with a simple configuration. As one of the goals. Further, the present invention provides a medium floating detection apparatus and an image forming apparatus capable of realizing multistage floating detection with a simple configuration and suppressing false detection to realize high accuracy multistage floating detection. To do one of the other purposes.
  • the present disclosure provides the following inventive aspects.
  • the transmission type detection apparatus includes a light projecting unit that projects a beam onto a passage area through which an object to be detected passes, an aperture member having a plurality of light passing openings disposed in the light projecting unit, and a plurality A light receiving unit for receiving a beam projected onto the passage area through the individual openings, and a light amount received by the light receiving unit are compared with a plurality of predetermined threshold values, and a signal corresponding to the comparison result is output.
  • each of the plurality of apertures has a polygonal aperture shape, and the plurality of apertures are outside the diffracted light generation region where diffracted light of beams passing through the other apertures is generated
  • the transmission type detection device is disposed at a position overlapping the diffracted light non-generation area which is the area of
  • the beam is projected from the light emitting unit toward the passage area of the detection subject, and the beam transmitted through the passage area is received by the light receiving unit.
  • One beam is divided into a plurality of beams as the beams pass through the plurality of apertures of the aperture member disposed in the light emitting unit.
  • the object to be detected is a part of the medium to be conveyed which is conveyed along the medium conveyance path, and lifting of the medium to be conveyed in the thickness direction of the medium to be conveyed occurs.
  • the transmission type detection device is configured to be used as a medium floating detection device that detects the presence or absence of floating higher than the reference height in multiple stages with respect to a plurality of reference heights different in height in the thickness direction. You may
  • the floating of the medium to be conveyed that occurs in the thickness direction of the medium to be conveyed is referred to as "floating".
  • a plurality of threshold values corresponding to a plurality of types of reference heights are determined in advance, and threshold processing is performed using the plurality of threshold values with respect to the light amount received by the light receiving unit.
  • the above floating can be accurately detected in multiple steps.
  • the plurality of openings in the aperture member be arranged in an oblique direction that is not parallel to the thickness direction of the medium to be transported. According to this arrangement form, the interference between the diffracted light and another beam generated due to the floating of the transported medium can be suppressed, and the noise of the light reception signal is reduced.
  • a third aspect of the invention is the transmission type detection device according to the second aspect, wherein the light projection unit may project the beam along the medium surface of the medium to be conveyed in a direction intersecting the conveyance direction of the medium to be conveyed.
  • the direction intersecting the transport direction may be a direction orthogonal to the transport direction, or may be a direction diagonal to the transport direction.
  • the medium width direction orthogonal to the transport direction is an example of a direction intersecting the transport direction.
  • the medium width direction orthogonal to the transport direction is the same as the width direction of the media transport path.
  • a fourth aspect of the invention is the transmission detection apparatus according to any one of the first to third aspects, wherein the polygon may have a configuration in which two pairs of opposite sides are parallel quadrilaterals.
  • the diffracted light generation region may be a band-shaped region extending in a direction orthogonal to each side of the polygon.
  • a sixth aspect is the transmission type detection device according to any one of the first to fifth aspects, wherein the light receiving portion includes a light receiving side aperture member having a plurality of light receiving openings for passing light. You may
  • the light receiving openings are respectively disposed in the light paths of the respective beams passing through the respective openings of the aperture member of the light emitting unit.
  • a seventh aspect is the transmission type detection device according to any one of the first to the sixth aspects, wherein the plurality of openings are arranged at positions not overlapping with the diffracted light generation regions formed by the other openings. You may
  • no interference pattern is generated in each beam, and a spot of a beam of uniform light intensity can be obtained.
  • the plurality of apertures are disposed at positions where a portion of each aperture region overlaps the diffracted light generation region created by the other apertures.
  • the aperture is a position overlapping the uniform light intensity area having a uniform light intensity distribution in the beam area of each beam passing through each of the apertures of the aperture member disposed in the light projection section, and in the beam area It may be arranged at a position not overlapping with the interference fringe generation region which is a region overlapping the diffracted light generation region.
  • the openings in the aperture members of the light emitting section are disposed close to each other, and so on, so that a part of each opening area partially overlaps the diffracted light generation area created by the other opening. Even when the aperture is arranged, highly accurate detection is possible by arranging the light receiving aperture at a position overlapping the uniform light intensity area in the beam area.
  • the plurality of light receiving openings have an opening area smaller than the opening of the aperture member disposed in the light projecting portion and fall within the uniform light intensity region. It may be arranged at a position.
  • a tenth aspect of the invention is the transmission detection apparatus according to any one of the first to ninth aspects, wherein the light projecting unit includes a laser light source and a beam shaping optical system that widens the beam diameter of the laser light output from the laser light source.
  • the beam shaping optical system may be configured to be disposed in a light path between the laser light source and the aperture member.
  • the beam diameter of the beam output from the laser light source is small, the beam diameter can be expanded to the range of the detection target to be detected.
  • the beam shaping optical system may be a beam expander.
  • the light receiving section may be configured to have a lens for condensing a beam transmitted through the passing area.
  • the medium floating detection apparatus includes a light projecting unit that projects a beam along the medium surface of the conveyed medium in a direction intersecting the conveyance direction of the conveyed medium, and a light passing portion disposed in the light projecting unit
  • An aperture member having a plurality of openings, a light receiving unit for receiving a beam projected along the medium surface through the plurality of openings, a quantity of light received by the light receiving unit, and a plurality of predetermined threshold values , And outputs a signal corresponding to the comparison result, each of the plurality of openings has a polygonal opening shape, and the plurality of openings pass through the other openings.
  • the medium floating detection device is disposed at a position overlapping the non-diffraction light generation area which is an area outside the diffracted light generation area where the diffracted light of the light beam is generated.
  • the thirteenth aspect it is possible to suppress the generation of interference fringes due to the diffracted light of the beam passing through each opening of the aperture member, and it is possible to accurately detect floats different in height corresponding to a plurality of threshold values. Further, according to the thirteenth aspect, multistage float detection can be realized with low cost and space saving by a simple configuration.
  • a fourteenth aspect of the invention is the medium floating detection device according to the thirteenth aspect, wherein the light emitting unit and the light receiving unit may be arranged to face each other across the medium transport path of the medium to be transported in the width direction.
  • a fifteenth aspect of the invention is the medium floating detection apparatus according to the thirteenth or fourteenth aspect, further including a parallel flat plate for translating the beam projected along the medium surface in the thickness direction of the medium to be conveyed according to the thickness of the medium to be conveyed. It may be a configuration.
  • the fifteenth aspect it is possible to keep the distance between the medium surface and the beam constant regardless of the thickness of the medium to be transported.
  • the influence of the reflection from the medium surface can be made constant, and the noise of the light reception signal can be reduced.
  • the medium floating detection apparatus may be configured to include a blower mechanism for blowing air to the light path of the beam.
  • the sixteenth aspect it is possible to destroy the thermal boundary layer around the beam by air blowing, and it is possible to suppress the bending of the beam due to the heat blaze phenomenon or the mirage phenomenon, that is, light refraction, and to reduce the noise of the received light signal.
  • a seventeenth aspect is the medium floating detection device according to any one of the thirteenth to sixteenth aspects, wherein the plurality of beams passing through each of the plurality of openings mutually extend from the transport surface of the transported medium to the thickness direction of the transported medium
  • the beam passing through different height positions of the light beam and passing through a relatively low height position among the plurality of beams may pass through the upstream position in the transport direction.
  • the medium floating detection device may be configured to include a transport unit that holds the transported medium and transports the transported medium.
  • An image forming apparatus is an image forming apparatus including the medium floating detection apparatus according to any one of the thirteenth to eighteenth aspects and a recording head for recording an image on a transported medium.
  • Aspect 20 may be configured such that in the image forming apparatus of aspect 19, the recording head is an ink jet head.
  • the present invention it is possible to suppress the generation of interference fringes due to diffracted light of a beam projected through each aperture of the aperture member, and it is possible to realize highly accurate detection. Moreover, according to the present invention, it is possible to realize multi-step detection corresponding to a plurality of threshold values with a simple configuration at low cost and space saving.
  • FIG. 1 is a view schematically showing the configuration of a medium floating detection apparatus according to a first embodiment of the present invention.
  • FIG. 2 is a front view of the aperture member in the comparative example.
  • FIG. 3 is a view showing the distribution of brightness of a beam projected toward the medium transport path in the comparative example.
  • FIG. 4 is a view showing a state in which a part of the beam is blocked by the floating of the sheet.
  • FIG. 5 is a view showing the distribution of the brightness of the beam observed when a part of the lower beam is blocked by the floating of the sheet in the comparative example.
  • FIG. 6 is a front view showing an example of an aperture member used on the light projection side of the medium floating detection device according to the first embodiment of the present invention.
  • FIG. 1 is a view schematically showing the configuration of a medium floating detection apparatus according to a first embodiment of the present invention.
  • FIG. 2 is a front view of the aperture member in the comparative example.
  • FIG. 3 is a view showing the distribution
  • FIG. 7 is an explanatory view schematically showing the relationship between the detection beam that has passed through the aperture member and the sheet P.
  • FIG. 8 is a diagram showing the distribution of brightness of a beam emitted along the medium surface.
  • FIG. 9 is a view showing the distribution of the brightness of the beam when a part of the lower beam is blocked by the floating in the comparative example.
  • FIG. 10 is a view schematically showing a diffracted light generation region and a diffracted light non-generation region of diffracted light generated when a beam passes through one rectangular opening in the aperture member.
  • FIG. 11 is a schematic view showing an arrangement example of the second rectangular opening in the aperture member.
  • FIG. 12 is a schematic view showing an arrangement example of the third rectangular opening in the aperture member.
  • FIG. 13 is a view showing the light intensity distribution of one beam spot and diffracted light generated around it in the case where there is no floating on the sheet.
  • FIG. 14 is a view showing the beam shape and the light intensity distribution of diffracted light when a part of the beam spot shown in FIG. 13 is blocked by the floating of the sheet.
  • FIG. 15 is a front view showing an example of an aperture member used on the light projection side of the medium floating detection device according to the second embodiment.
  • FIG. 16 is a schematic view showing the positional relationship of each beam in the second embodiment.
  • FIG. 17 is a view showing an example of a light receiving side aperture member disposed in the light receiving section of the second embodiment.
  • FIG. 18 is a view showing an example of a light receiving side aperture member disposed in the light receiving section of the third embodiment.
  • FIG. 19 is a diagram schematically showing the configuration of a medium floating detection device according to the fourth embodiment.
  • FIG. 20 is a block diagram showing a configuration of a control system of the medium floating detection apparatus.
  • FIG. 21 is a side view schematically showing the relationship between the two beams projected through the aperture member and the floating of the sheet.
  • FIG. 22 is a side view schematically showing the relationship between two beams projected through the aperture member and lifting of the sheet.
  • FIG. 23 is a side view schematically showing the relationship between two beams projected through the aperture member and floating of the sheet.
  • FIG. 24 is a side view schematically showing the relationship between two beams projected through the aperture member and the floating of the sheet.
  • FIG. 25 is a side view schematically showing the positional relationship between the beam and the sheet.
  • FIG. 26 is an overall configuration diagram of an ink jet printing apparatus according to an embodiment of the present invention.
  • FIG. 27 is a block diagram showing a schematic configuration of a control system of the ink jet printing apparatus.
  • FIG. 28 is a perspective view showing an example of the light emitting unit and the light receiving unit of the medium floating detection apparatus disposed in the drawing unit.
  • FIG. 29 is a schematic configuration diagram of an ink jet printing apparatus according to another embodiment.
  • FIG. 30 is a plan view showing another form of the aperture member.
  • FIG. 31 is a view schematically showing an example of a diffracted light generation region formed by the rhombic openings and a diffracted light non-generation region.
  • FIG. 32 is a view schematically showing an example of a diffracted light generation region formed by triangular openings and a diffracted light non-generation region.
  • FIG. 33 is a view schematically showing an example of a diffracted light generation region formed by hexagonal openings and a diffracted light non-generation region.
  • FIG. 1 is a view schematically showing the configuration of a medium floating detection apparatus according to a first embodiment of the present invention.
  • the medium floating detection device 10 is configured using a transmission type laser sensor including the light emitting unit 12 and the light receiving unit 14.
  • the medium floating detection device 10 is an example of a transmission type detection device.
  • the medium floating detection device 10 is a device that detects floating of the conveyed sheet P in multiple stages.
  • the sheet P is held by a medium conveyance mechanism (not shown) and conveyed along a predetermined medium conveyance path.
  • the sheet P is an example of a medium to be transported.
  • the white arrows shown in FIG. 1 indicate the transport direction of the sheet P.
  • the light emitting unit 12 and the light receiving unit 14 are disposed to face each other with the medium transport path interposed therebetween in the width direction.
  • the light projector 12 projects the beams B1 and B2 along the medium surface in the medium width direction orthogonal to the conveyance direction of the paper P.
  • the light receiving unit 14 receives a part or all of the beams B1 and B2 projected from the light projecting unit 12, and outputs a light receiving signal according to the amount of light received.
  • the object to be detected in the medium floating detection device 10 is floating of the sheet P. That is, the object to be detected is a portion of the sheet P transported along the medium transport path, and is a portion on the sheet P in which the thickness direction of the sheet P is raised. As the sheet P is transported, the beams B1 and B2 are projected to the area (passing area) through which the float passes.
  • the float passing area is an area around the medium surface along the medium surface of the sheet P in the medium transport path.
  • the light projector 12 includes a light projector 22 including a laser light source 22A, and an aperture member 24 for dividing one beam emitted from the light projector 22 into a plurality of beams.
  • a semiconductor light source can be used as the laser light source 22A.
  • a laser diode can be mentioned as an example of a light emitting element that can be used as the laser light source 22A.
  • a red semiconductor laser diode of wavelength 660 nanometer [nm] band can be used.
  • the light projector 22 may correspond to “class 1” of the classification defined in “Safety Standard for Laser Products: JIS C 6802” of Japanese Industrial Standard.
  • the maximum output of the projector 22 may be, for example, 2 milliwatts [mW].
  • the aperture member 24 is a plate-like member having a plurality of openings 24A and 24B for light passage.
  • the aperture member 24 may be understood as a throttling member that functions as a "diaphragm".
  • an aperture member 24 having two openings 24A, 24B is illustrated.
  • the number of openings in the aperture member 24 is the same as the number of levels of the reference height for determining the presence or absence of floating more than a certain height, that is, the same as the number of stages when detecting floating of the paper P in multiple stages. be able to.
  • the first reference height for determining whether or not the floating of the first reference height or more occurs in the thickness direction of the sheet P from the medium surface and the first reference height from the sheet surface
  • a two-step sheet floating detection is performed using a two-level level of the second reference height to determine whether or not a floating higher than the second reference height occurs.
  • the first reference height is, for example, 0.6 mm [mm].
  • the second reference height is, for example, 3.0 millimeters [mm].
  • the light projector 12 is provided with a beam expander 26 that expands the beam diameter of the laser beam emitted from the light projector 22.
  • a beam expander 26 is disposed in the light path between the projector 22 and the aperture member 24.
  • the beam expander 26 is an example of a beam shaping optical system.
  • the beam expander 26 includes, for example, a concave lens 26A and a convex lens 26B.
  • the beam expander 26 is not limited to the Galileo type, and may be a Kepler type.
  • the beam expander 26 it is possible to change the beam diameter in accordance with the type of float height (the number of stages of multi-step float detection) to be detected. For example, in the case of performing three-step paper floating detection, the beam diameter may be made larger than that in the example of FIG.
  • the light receiving unit 14 includes a light receiver 32 and a light receiving side aperture member 34.
  • the light receiving side aperture member 34 has a plurality of light receiving openings 34A and 34B for light passage.
  • the number of light receiving openings in the light receiving side aperture member 34 is the same as the number of the aperture members 24 on the light projection side.
  • the beam B1 having passed through the opening 24A of the light emitting side aperture member 24 passes through the light receiving opening 34A of the light receiving side aperture member 34 and is received by the light receiver 32.
  • the beam B2 that has passed through the opening 24B of the light emitting side aperture member 24 passes through the light receiving opening 34B of the light receiving side aperture member 34 and is received by the light receiver 32.
  • the light receiving unit 14 is provided with a convex lens 36 that condenses the beams B1 and B2 spreading in the detection area.
  • the convex lens 36 is disposed in the light path between the light receiving side aperture member 34 and the light receiver 32.
  • the beams having passed through the light receiving openings 34 A and 34 B of the light receiving side aperture member 34 are condensed by the convex lens 36 and are incident on the light receiver 32.
  • the convex lens 36 is an example of a lens for condensing a beam.
  • the light receiver 32 is configured using a photoelectric conversion element, and outputs an electric signal according to the amount of light received.
  • the light reception signal output from the light receiver 32 is sent to an arithmetic circuit not shown in FIG.
  • the arithmetic circuit compares the amount of light represented by the light reception signal obtained from the light receiver 32 with a plurality of predetermined threshold values, and outputs a signal indicating the comparison result.
  • the medium floating detection device 10 includes a first parallel flat plate 42 and a second parallel flat plate 44 that translates the beams B1 and B2 in the thickness direction of the paper P according to the thickness of the paper P.
  • the first parallel flat plate 42 is disposed between the aperture member 24 of the light emitting unit 12 and the medium transport path and on the light path of the beams B1 and B2.
  • the second parallel flat plate 44 is disposed between the light receiving side aperture member 34 of the light receiving unit 14 and the medium transport path, and on the light path of the beams B1 and B2.
  • Each of the first parallel flat plate 42 and the second parallel flat plate 44 is made of glass or other transparent material, and is rotatably supported by a rotation mechanism (not shown).
  • the conveyance direction of the sheet P may be referred to as “Y direction” or “medium conveyance direction”.
  • the thickness direction of the sheet P is taken as the direction of the Z axis.
  • the height direction of the floating of the paper P is taken as the positive direction of the Z axis.
  • the thickness direction of the sheet P may be referred to as “Z direction”. Further, in the present specification, when expressing the positional relationship in the upper and lower direction and / or the upper and lower direction, the positive direction of the Z axis away from the medium surface of the paper P is taken as the “upper” direction.
  • FIG. 2 is a front view of the aperture member 54 in the comparative example. The case where the aperture member 54 of the comparative example is disposed in the light emitting unit 12 instead of the aperture member 24 shown in FIG. 1 will be described.
  • two circular openings 54A and 54B for light passage are arranged side by side in the Z direction.
  • the circular openings 54A, 54B have the same opening area.
  • the diameter d of the openings 54A, 54B is 1.0 mm [mm]
  • the center-to-center distance L between the openings 54A, 54B is 2.4 mm [mm].
  • FIG. 3 is a view showing the distribution of brightness of a beam projected from the X direction toward the medium transport path.
  • the distribution of brightness may be understood as the light intensity distribution of the beam.
  • the light intensity distribution of a beam may be understood as the shape of the beam.
  • the beams having passed through the circular openings 54A and 54B of the aperture member 54 generate interference fringes as shown in FIG. 3 due to light interference, and a beam of uniform light intensity can not be obtained. For this reason, detection noise increases in the light receiving unit 14 and false detection of floating easily occurs. This point is one of the problems.
  • FIG. 4 is a view showing a state in which a part of the beam is blocked by the floating of the sheet.
  • the lower beam passing a position close to the medium surface of the sheet P is blocked by the float 58 of the sheet P. It is shown schematically.
  • FIG. 5 is a view showing the distribution of the brightness of the beam observed when a part of the lower beam is blocked by the float 58 of the paper P in the comparative example.
  • FIG. 5 compared to FIG. 3, the lower beam is blocked by the float 58, light diffraction occurs at the point of the float 58, and the diffracted light interferes with the upper beam, resulting in a striped pattern. It is changing. As shown in FIG. 5, when the diffracted light generated by the float 58 interferes with the upper beam, the noise of the received light signal increases. This point is one of the other issues.
  • FIG. 6 is a front view showing an example of the aperture member 24 used on the light projection side of the medium floating detection device 10 according to the first embodiment of the present invention.
  • the aperture member 24 has a plurality of square openings 24A and 24B.
  • an opening shape is not limited to a square, and may be a rectangle, a rhombus, or the like.
  • the opening shape may be a polygon other than a quadrangle, but a quadrangle is one of the preferable forms as the opening shape.
  • aperture shape a form in which two pairs of opposite sides are parallel quadrilaterals is preferable, and a form in which all corners are square is more preferable.
  • a rectangle in which all the corners are right angles is denoted as "rectangle”.
  • a rectangular opening may be described as a "rectangular opening”.
  • One set of two parallel sides in the rectangular openings 24A and 24B illustrated in FIG. 6 is parallel to the Y axis, and the other set of two parallel sides is parallel to the Z axis.
  • the two openings 24A and 24B are arranged side by side obliquely in the direction of the optical axis of the beam.
  • the upper opening 24B is disposed obliquely at an angle ⁇ with respect to the lower opening 24A, with the azimuth just above the lower opening 24A being an azimuth of an angle of 0 degrees.
  • the angle ⁇ can be an appropriate angle excluding “0 °” immediately above and “ ⁇ 90 °” in the horizontal direction.
  • the openings 24A and 24B are arranged in an arrangement form in which the openings 24A and 24B are arranged in an oblique direction (parallel to the Z direction and a non-perpendicular direction) that is not parallel to the Z direction.
  • the center-to-center distance Lz between the opening 24A and the opening 24B in the Z direction is, for example, 2.4 mm [mm].
  • the length a of one side of the rectangular opening, the angle ⁇ , and the center-to-center distance Lz can be appropriately designed according to the height of the float to be detected.
  • FIG. 7 is an explanatory view schematically showing the relationship between the detection beam that has passed through the aperture member 24 and the sheet P.
  • the sheet P is held by the medium transport mechanism 60 and transported from right to left in FIG. 7.
  • the medium support surface 60A of the medium transport mechanism 60 corresponds to the medium transport surface.
  • a float 58 is generated on the sheet P, and in FIG. 7, a state immediately before the lower beam B1 is blocked by the float 58 is depicted.
  • the height h of the float 58 is, for example, slightly higher than the first reference height h1 from the medium surface.
  • the first reference height h1 is, for example, 0.6 mm [mm].
  • the lower beam B1 passing a relatively lower height position of the two beams B1 and B2 passes the upstream position in the transport direction than the upper beam B2 It has become.
  • FIG. 8 is a diagram showing the distribution of brightness of a beam emitted along the medium surface.
  • the diffracted light of the beam that has passed through each of the rectangular openings 24A and 24B spreads in four directions of the cross orthogonal to each side of the rectangular centering on each of the openings 24A and 24B.
  • interference fringes do not occur in another beam, and beam spots of uniform light intensity can be obtained for each of the lower and upper beams.
  • a beam with uniform light intensity can be obtained.
  • noise of the light reception signal is reduced, and false detection of floating can be suppressed.
  • FIG. 9 is a diagram showing the distribution of the brightness of the beam when a part of the lower beam is blocked by the float 58.
  • the light diffracted by the float 58 does not reach the upper beam, so that a spot of uniform light intensity can be maintained for the upper beam.
  • FIG. 10 is a view schematically showing a diffracted light generation region and a diffracted light non-generation region of diffracted light generated when a beam passes through one rectangular opening in the aperture member.
  • diffracted light DL is generated in four directions of the cross outside the rectangular aperture 25A as shown in FIG.
  • the four directions in which the diffracted light DL is generated are orthogonal to the sides of the rectangular aperture 25A.
  • first-order diffracted light and second-order diffracted light are shown in FIG. 10, third- or higher-order diffracted light may also be generated.
  • a region where diffracted light is generated outside the aperture of the aperture member is referred to as a diffracted light generation region.
  • the diffracted light DL is generated in a diffracted light generation area DA1 extending in a strip in the Y direction and a diffracted light generation area DA2 extending in a strip in the Z direction.
  • almost no diffracted light is generated in the area outside the diffracted light generation areas DA1 and DA2, that is, the area hatched in FIG.
  • a region where the diffracted light is hardly generated is called a diffracted light non-generating region, and is indicated by a symbol ND.
  • the periphery of one opening can be divided into a diffracted light generation region and a diffracted light non-generation region.
  • the width of the actual diffracted light generation region becomes narrower as the distance from the aperture increases.
  • the intensity distribution of diffracted light may be calculated based on the aperture shape to define a diffracted light generation area that more closely reflects the actual diffraction light generation area, in FIG. 10, the diffracted light generation area DA1 is The case where the width in the Z direction and the width in the Y direction of the diffracted light generation area DA2 are constant is shown as an example. As shown in FIG. 10, there is no problem in practical use even if the diffracted light generation areas DA1 and DA2 having a constant width are defined, and such simple handling is sufficient.
  • each of the plurality of openings be disposed at a position overlapping the diffracted light non-generating area, avoiding the diffracted light generating area of the other aperture.
  • the second rectangular aperture 25B is provided for one rectangular aperture 25A shown in FIG. 10, as shown in FIG. 11, the second rectangular aperture 25B is arranged in the diffracted light non-generating region ND shown as a hatched region.
  • the third rectangular aperture 25C is disposed at a position not overlapping the diffracted light generation region formed by each of the other two rectangular apertures 25A and 25B.
  • each of the plurality of openings is preferably disposed at a position overlapping the non-diffraction light generation region which is a region outside the diffracted light generation region due to the other openings. By adopting this, it is possible to suppress the generation of interference fringes due to diffracted light.
  • the openings 24A and 24B of the aperture member 24 shown in FIG. 1 are arranged in the same positional relationship as the rectangular openings 25A and 25B shown in FIG.
  • the arrangement form of the openings 24A and 24B is not limited to the form illustrated in FIG. 11, and the openings 24A and 24B may be arranged at positions overlapping with the diffracted light non-generation areas of the other openings.
  • FIG. 13 is a view showing the light intensity distribution of one beam spot and diffracted light generated around it in the case where there is no floating on the sheet.
  • the beam pattern 71 shown on the left side of FIG. 13 schematically shows the spot of the beam and the shape of the diffracted light generated around it.
  • a graph 72 shown on the right side of FIG. 13 is a graph showing the light intensity distribution of the cross section along line A of the pattern 71.
  • Line A is a line passing through the center of the beam spot and parallel to the Z direction.
  • the vertical axis of the graph 72 represents the position, and the horizontal axis represents the light intensity.
  • Light intensity may be understood as "light quantity” or "illuminance”.
  • FIG. 14 is a view showing the beam shape and the light intensity distribution of diffracted light when a part of the beam spot shown in FIG. 13 is blocked by the floating of the sheet.
  • the beam pattern 75 shown on the left side of FIG. 14 schematically shows the beam shape when a part under the beam spot shown in FIG. 13 is blocked by the floating of the sheet.
  • a graph 76 shown on the right side of FIG. 14 is a graph showing the light intensity distribution of the cross section along the line B of the pattern 75.
  • Line B is a line passing through the center of the beam spot and parallel to the Z direction.
  • the vertical axis of the graph 76 represents the position, and the horizontal axis represents the light intensity.
  • the light wraparound generally called "knife edge diffraction" occurs, and new interference fringes occur. That is, in the diffracted light generation region, interference fringes are generated in which the diffracted light generated at the opening of the aperture member 24 and the diffracted light generated by light blocking due to floating interfere with each other.
  • the reflected light from the sheet P may be incident on the light receiving unit 14 when the distance from the floating place to the light receiving unit 14 is long.
  • the interference fringes generated by light shielding due to floating become a more complicated pattern as compared with the distribution of light quantity when there is no floating shown in FIG. 13, but such interference fringes It occurs in the diffracted light generation region described in 10. Therefore, as illustrated in FIG. 11 and FIG. 12, diffracted light generated by floating is provided by arranging a plurality of rectangular openings in a region (diffraction light non-generation region ND) avoiding each other's diffracted light generation region. Can suppress the generation of complicated interference fringes.
  • FIG. 15 shows an example in which the opening area of the second opening 24B is partially overlapped with a part of the diffracted light generation area formed by the first opening 24A shown at the center. . That is, the openings 24A, 24B are disposed at positions where a portion of each opening region overlaps the diffracted light generation region created by the other openings.
  • the beams having passed through the respective openings 24A and 24B include two regions of a uniform light intensity region having a uniform light intensity distribution and an interference fringe generation region where interference fringes may occur.
  • the interference fringe generation area may be understood as a nonuniform light intensity area where the light intensity distribution may be nonuniform.
  • a uniform light intensity area 80A and an interference fringe generation area 81A exist in the beam area of the beam B1 which has passed through the first opening 24A shown at the center.
  • the beam area of the rectangular beam B2 that has passed through the second opening 24B includes a uniform light intensity area 80B and an interference fringe generation area 81B.
  • the light receiving side aperture member 34 of the light receiving unit 14 blocks the light from the interference fringe generation areas 81A and 81B and allows only the light of the uniform light intensity areas 80A and 80B to pass, It is preferred to have 34B.
  • FIG. 17 is a view showing an example of the light receiving side aperture member 34 disposed in the light receiving unit 14.
  • Each of the rectangular regions shown by broken lines in FIG. 17 indicates the uniform light intensity regions 80A and 80B of the beams B1 and B2 described in FIG.
  • Each of the light receiving openings 34A and 34B formed in the light receiving side aperture member 34 shown in FIG. 17 has an opening area smaller than the uniform light intensity areas 80A and 80B, and the range of the uniform light intensity areas 80A and 80B. It is provided at a position that fits inside. As a result, since the beam in the portion where the interference fringes are generated does not enter the light receiver 32, noise can be reduced.
  • the shape of the light receiving openings 34A and 34B may be circular or polygonal.
  • the light receiving side aperture member 34 having the light receiving openings 34A and 34B having an opening area of 0.25 square millimeters [mm 2 ] or less in the light receiving unit 14 be disposed.
  • the light receiving aperture may be a circular aperture of 0.5 mm in diameter.
  • FIG. 18 is a view showing another example of the light receiving side aperture member 34 disposed in the light receiving portion 14.
  • Each of the rectangular regions shown by broken lines in FIG. 18 indicates the uniform light intensity regions 80A and 80B of the beams B1 and B2 described in FIG.
  • the light receiving openings 34A and 34B formed in the light receiving side aperture member 34 shown in FIG. 18 are disposed at positions partially overlapping the uniform light intensity areas 80A and 80B and do not overlap the interference fringe generating areas 81A and 81B. It is placed in position. Even if the arrangement of the light receiving openings 34A and 34B as shown in FIG. 18 is adopted, the beam in the portion where the interference fringes are generated does not enter the light receiver 32, so noise can be reduced.
  • FIG. 19 is a diagram schematically showing the configuration of a medium floating detection device according to the fourth embodiment.
  • elements that are the same as or similar to the configuration shown in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted. The differences from FIG. 1 will be described.
  • the medium floating detection apparatus 10 shown in FIG. 19 includes a blower mechanism 90 for blowing air to the beams B1 and B2.
  • the blower mechanism 90 includes a plurality of fans 92 and a blower nozzle 94.
  • the plurality of fans 92 are arranged side by side in the width direction of the sheet P.
  • the blower mechanism 90 blows air to the light paths of the beams B1 and B2.
  • the temperature boundary layer in the vicinity of the sheet P can be destroyed by the air blowing from the air blowing mechanism 90, and the signal fluctuation can be reduced. That is, if there is a temperature boundary layer in the vicinity of the sheet P, the distribution of the refractive index depending on the air temperature is generated, the optical axis of the beam is bent due to the positive flame phenomenon or the mirage phenomenon, and the light reception signal from the light receiver 32 may fluctuate . In this respect, by blowing the air to the beams B1 and B2 using the blowing mechanism 90, the temperature boundary layer can be broken, and a stable signal can be obtained from the light receiver 32.
  • FIG. 20 is a block diagram showing a configuration of a control system of the medium floating detection device 10.
  • the medium floating detection device 10 includes a control device 110 connected to the light emitter 22 and the light receiver 32.
  • the control device 110 can be realized using one or more computers and a program.
  • the control device 110 includes an arithmetic unit 112, performs light emission control of the light projector 22, and processes a signal obtained from the light receiver 32.
  • the calculation unit 112 compares the amount of light received by the light receiver 32 with a plurality of predetermined threshold values, and outputs a signal according to the comparison result.
  • a first threshold and a second threshold are illustrated as an example of the plurality of thresholds referred to by the calculation unit 112.
  • the first threshold corresponds to a determination criterion for determining the presence or absence of floating above the first reference height
  • the second threshold corresponds to a determination criterion for determining the presence or absence of floating above the second reference height Do.
  • each of the first threshold and the second threshold may be a value indicating a voltage value.
  • the operation unit 112 may be configured using a digital circuit or may be configured using an analog circuit such as an operational amplifier.
  • the calculation unit 112 determines that no floating above the first reference height has occurred, and the first determination result indicating the determination result Generate a floating undetected signal.
  • the calculation unit 112 When the amount of light received by the light receiver 32 is equal to or less than the first threshold and greater than the second threshold, the calculation unit 112 generates a float greater than or equal to the first reference height and less than the second reference height. And generates a first floating detection signal indicating the determination result. If the amount of light received by the light receiver 32 is less than or equal to the second threshold value, the calculation unit 112 determines that a float greater than or equal to the second reference height is generated, and indicates the second determination result. Generate a float detection signal.
  • the first floating detection signal generated by the calculation unit 112 is sent to the conveyance control unit 120 and the head elevation control unit 122.
  • the transport control unit 120 is a control circuit that controls the operation of the medium transport unit 124.
  • the medium conveyance unit 124 includes a medium conveyance mechanism that holds the sheet P and conveys the sheet P along a predetermined medium conveyance path, and a motor serving as a motive power source.
  • the medium transport mechanism may be, for example, a transport mechanism based on a suction belt transport method or a transport mechanism based on a drum transport method.
  • the medium transport unit 124 is an example of the “transport unit”.
  • the conveyance control unit 120 acquires the first floating detection signal from the calculation unit 112, the conveyance control unit 120 continues conveyance of the sheet P by the medium conveyance unit 124.
  • the head elevation control unit 122 is a control circuit that controls the operation of the head elevation unit 126 that raises and lowers the recording head (not shown) in the Z direction.
  • a head lifting unit 126 lifts and lowers the printing head between a printing position at which an image can be recorded on the sheet P and a retracted position where the printing head is raised by a predetermined distance in the Z direction from the printing position. It is comprised including a source motor.
  • the head elevation control unit 122 When the head elevation control unit 122 acquires the first floating detection signal from the calculation unit 112, the head elevation control unit 122 drives the head elevation unit 126 to move the recording head to the retracted position, and the sheet P on which the floating occurs is the recording head After passing under the recording head, the recording head is returned to the printing position.
  • the second floating detection signal generated by the calculation unit 112 is sent to the conveyance control unit 120.
  • the conveyance control unit 120 acquires the second floating detection signal from the calculation unit 112, the conveyance control unit 120 urgently stops conveyance of the sheet P by the medium conveyance unit 124.
  • the transport control unit 120 and the head elevation control unit 122 may be included in the control device 110 or may be included in a control device of an image forming apparatus connected to the control device 110 or the like.
  • the display device 130 and the input device 132 are connected to the control device 110.
  • the display device 130 may be, for example, a liquid crystal display, an organic electro-luminescence (OEL) display, a projector, or a suitable combination thereof.
  • OEL organic electro-luminescence
  • As the input device 132 a keyboard, a mouse, a touch panel, a trackball, a voice input device, an appropriate combination of these input devices, or the like can be adopted.
  • the display device 130 can display various information in response to an instruction from the control device 110.
  • the input device 132 and the display device 130 constitute a user interface.
  • the user can operate the input device 132 to input information specifying the type and / or thickness of the sheet P.
  • the control device 110 executes various processes in accordance with the information input through the input device 132.
  • the control device 110 may include a parallel plate drive control unit 114, an air flow control unit 116 and a display control unit 118 in addition to the calculation unit 112.
  • the medium floating detection device 10 further includes a first parallel flat plate drive unit 142 and a second parallel flat plate drive unit 144.
  • the first parallel plate drive unit 142 includes a motor as a power source for driving the first parallel plate 42 to rotate.
  • the second parallel plate drive unit 144 is configured to include a motor as a power source for driving the second parallel plate 44 to rotate.
  • the parallel flat plate drive control unit 114 controls the first parallel flat plate drive unit 142 and the second parallel flat plate drive unit 144 according to the thickness of the sheet P to increase the heights of the beams B1 and B2 with respect to the surface of the sheet P. Adjust the
  • the blower control unit 116 controls the operation of the blower mechanism 90.
  • the blower control unit 116 drives the fan 92 of the blower mechanism 90 while the sheet P is being conveyed, to blow air to the beams B1 and B2.
  • the display control unit 118 generates a signal indicating the display content by the display device 130.
  • the signal output from the calculation unit 112 can be displayed on the display device 130 via the display control unit 118.
  • the display control unit 118 can display a warning message or the like on the display device 130 based on the first floating detection signal and / or the second floating detection signal.
  • FIG. 21 is a side view schematically showing the relationship between the two beams B1 and B2 projected through the aperture member 24 and the float 58 of the sheet P.
  • the state of reference numeral 151 shown at the top of FIG. 21 indicates that a float 58 having a height h is generated from the surface of the medium on the sheet P, and this float 58 approaches the front of the beams B1 and B2. .
  • the state indicated by reference numeral 151 is an example in the case where the Y direction length Ly of the float 58 is larger than the Y direction detection range L0 of the beams B1 and B2 and the height h of the float 58 is larger than the second reference height h2. is there.
  • the state of reference numeral 152 shown in the second row from the top of FIG. 21 shows that the sheet P moves in the Y direction from the state of reference numeral 151 and the beams B1 and B2 are shielded by the float 58. If Ly ⁇ L0, the floats 58 can simultaneously block the beams B1 and B2.
  • a state 153 in the third row from the top of FIG. An example is shown.
  • the Y-direction length Ly of the float 58 in the state of reference numeral 153 is larger than the Y-direction detection range L0 of the beams B1 and B2.
  • the state of reference numeral 154 shown at the bottom of FIG. 21 indicates that the sheet P moves in the Y direction from the state of reference numeral 153 and only the lower beam B1 is blocked by the float 58. If Ly ⁇ L0, the float 58 can block only the lower beam B1.
  • the state of reference numeral 152 and the state of reference numeral 154 can be determined based on the signal obtained from the light receiver 32.
  • FIG. 22 is a side view schematically showing the relationship between the two beams B1 and B2 projected through the aperture member and the float 58 of the sheet P.
  • the state of reference numeral 155 shown at the top of FIG. 22 indicates that a float 58 having a height h is generated from the surface of the medium on the sheet P, and this float 58 approaches the front of the beams B1 and B2. .
  • the Y direction length Ly of the float 58 is smaller than the Y direction detection range L0 of the beams B1 and B2, and the height h of the float 58 from the medium surface is larger than the second reference height h2. An example of the case is shown.
  • the state of reference numeral 156 shown in the second row from the top of FIG. 22 shows that the sheet P moves in the Y direction from the state of reference 155 and the beam B1 is blocked by the float 58.
  • the state of reference numeral 157 shown in the third row from the top of FIG. 22 shows that the sheet P is moved in the Y direction from the state of reference numeral 156 and the beam B2 is blocked by the float 58.
  • Ly ⁇ L0 the float 58 can not block the beams B1 and B2 simultaneously.
  • the state of reference numeral 158 shown in the fourth row from the top of FIG. An example is shown.
  • the Y-direction length Ly of the float 58 in the state of reference numeral 158 is smaller than the Y-direction detection range L0 of the beams B1 and B2.
  • the state of reference numeral 159 shown at the bottom of FIG. 22 shows that the sheet P moves in the Y direction from the state of reference 158 and only the lower beam B1 is blocked by the float 58. If Ly ⁇ L0, only the lower beam B1 may be blocked by the float 58.
  • FIGS. 23 and 24 show an example in which the upper beam B2 passes through the upstream position in the medium transport direction and the lower beam B1 passes through the downstream position in the medium transport direction. It is done.
  • FIG. 23 is a side view schematically showing the relationship between the two beams B1 and B2 projected through the aperture member and the float 58 of the sheet P. As shown in FIG. FIG. 23 shows an example in which the upper beam B2 passes the upstream position in the medium transport direction, and the lower beam B1 passes the downstream position in the medium transport direction. .
  • the state of reference numeral 161 shown at the top of FIG. 23 indicates that a float 58 having a height h is generated from the surface of the medium on the sheet P, and this float 58 approaches the front of the beams B1 and B2. .
  • the state indicated by reference numeral 151 is an example in the case where the Y direction length Ly of the float 58 is larger than the Y direction detection range L0 of the beams B1 and B2 and the height h of the float 58 is larger than the second reference height h2. is there.
  • the state of reference numeral 162 shown in the second row from the top of FIG. 23 shows that the sheet P is moved in the Y direction from the state of reference numeral 161 and the beams B1 and B2 are blocked by the float 58. If Ly ⁇ L0, the floats 58 can simultaneously block the beams B1 and B2.
  • a state 163 in the third row from the top of FIG. An example is shown.
  • the Y-direction length Ly of the float 58 in the state of reference numeral 163 is larger than the Y-direction detection range L0 of the beams B1 and B2.
  • the state of reference numeral 164 shown at the bottom of FIG. 23 shows that the sheet P moves in the Y direction from the state of reference 163 and only the lower beam B1 is blocked by the float 58. If Ly ⁇ L0, the float 58 can block only the lower beam B1.
  • the state of reference numeral 162 and the state of reference numeral 164 can be determined.
  • FIG. 24 is a side view schematically showing the relationship between the two beams B1 and B2 projected through the aperture member and the float 58 of the sheet P.
  • the state of reference numeral 165 shown at the top of FIG. 24 represents that the float 58 having a height h from the surface of the medium is generated on the sheet P, and this float 58 approaches the front of the beams B1 and B2. .
  • the Y-direction length Ly of the float 58 is smaller than the Y-direction detection range L0 of the beams B1 and B2, and the height h of the float 58 from the medium surface is larger than the second reference height h2. An example of the case is shown.
  • the state of reference numeral 166 shown in the second row from the top of FIG. 24 shows that the sheet P moves in the Y direction from the state of reference numeral 165 and the beam B2 is blocked by the float 58.
  • the state of reference numeral 167 shown in the third row from the top of FIG. 24 shows that the sheet P moves in the Y direction from the state of reference numeral 166 and the beam B1 is blocked by the float 58.
  • Ly ⁇ L0 the float 58 can not block the beams B1 and B2 simultaneously.
  • the state of the symbol 168 shown in the fourth row from the top of FIG. An example is shown.
  • the Y-direction length Ly of the float 58 in the state of reference numeral 168 is smaller than the Y-direction detection range L0 of the beams B1 and B2.
  • the state of reference numeral 169 shown at the bottom of FIG. 24 shows that the sheet P is moved in the Y direction from the state of reference 168 and only the lower beam B1 is blocked by the float 58. If Ly ⁇ L0, only the lower beam B1 may be blocked by the float 58.
  • the lower beam B1 is shown at a position higher than the medium surface of the paper P, for example, floating of the first reference height of 0.6 mm or more is In the case of detection, the lower beam B1 can be disposed at such a height position that the sheet P passes in the beam area as shown in FIG.
  • FIG. 26 is an overall configuration diagram of an ink jet printing apparatus 201A according to an embodiment of the present invention.
  • the inkjet printing apparatus 201A includes line-type inkjet heads 246K, 246C, 246M, and 246Y as recording heads of the drawing unit 240, and applies black (K), cyan (C), and magenta (M) to the sheet P which is a sheet. And yellow (Y) four-color ink to print a desired image in a single pass method.
  • the inkjet printing apparatus 201A is an example of an image forming apparatus.
  • an aqueous ink is used as the drawing ink.
  • An aqueous ink refers to an ink in which a coloring material such as a pigment or a dye is dissolved or dispersed in water and / or a solvent soluble in water.
  • an ultraviolet curable ink may be used.
  • the inkjet printing apparatus 201A includes a sheet feeding unit 210, a treatment liquid deposition unit 220, a treatment liquid drying unit 230, a drawing unit 240, an ink drying unit 250, and a stacking unit 260.
  • the sheet feeding unit 210 includes a sheet feeding device 212, a feeder board 214, and a sheet feeding drum 216.
  • the sheets of paper P are placed on the sheet feeding table 212A in the form of a stack of a large number of stacked sheets.
  • the type of the paper P is not particularly limited, for example, printing paper mainly made of cellulose such as high quality paper, coated paper, art paper, etc. can be used.
  • the sheet feeding device 212 takes out the sheets P in the bundle state set on the sheet feeding table 212A one by one in order from the top and feeds the sheet P to the feeder board 214.
  • the feeder board 214 conveys the sheet P received from the sheet feeding device 212 to the sheet feeding drum 216.
  • the feed drum 216 receives the sheet P fed from the feeder board 214, and conveys the received sheet P to the treatment liquid deposition unit 220.
  • the treatment liquid deposition unit 220 applies the treatment liquid to the sheet P.
  • the treatment liquid is a liquid having a function of aggregating, or insolubilizing or thickening the coloring material component in the ink.
  • the treatment liquid application unit 220 includes a treatment liquid application drum 222 and a treatment liquid application device 224.
  • the treatment liquid application drum 222 receives the sheet P from the feed drum 216 and conveys the received sheet P to the treatment liquid drying unit 230.
  • the treatment liquid application drum 222 has grippers 223 on its peripheral surface, and holds the leading end of the sheet P by the gripper 223 and rotates it, thereby winding and conveying the sheet P around the peripheral surface.
  • the treatment liquid application device 224 applies the treatment liquid to the sheet P conveyed by the treatment liquid application drum 222.
  • the treatment liquid is applied by a roller.
  • the method of applying the treatment liquid is not limited to the roller application method.
  • Other methods may be applied to the treatment liquid application device 224. Examples of other methods of the treatment liquid application device 224 include application using a blade, ejection by an inkjet method, and spraying by a spray method.
  • the treatment liquid drying unit 230 dries the sheet P to which the treatment liquid has been applied.
  • the treatment liquid drying unit 230 includes a treatment liquid drying drum 232 and a hot air blower 234.
  • the treatment liquid drying drum 232 receives the sheet P from the treatment liquid application drum 222, and conveys the received sheet P to the drawing unit 240.
  • the treatment liquid drying drum 232 is provided with grippers 233 on its circumferential surface.
  • the processing liquid drying drum 232 conveys the sheet P by gripping and rotating the leading end of the sheet P by the gripper 233.
  • the hot air blower 234 is installed inside the treatment liquid drying drum 232.
  • the hot air blower 234 blows hot air on the sheet P conveyed by the treatment liquid drying drum 232 to dry the treatment liquid.
  • the drawing unit 240 includes a drawing drum 242, a head unit 244, a sheet floating detection unit 245, a sheet pressing roller 247, and an image reading device 248.
  • the drawing drum 242 receives the sheet P from the treatment liquid drying drum 232, and conveys the received sheet P to the ink drying unit 250.
  • the drawing drum 242 includes grippers 243 on the circumferential surface of the drum, and grips and rotates the leading end of the sheet P using the gripper 243 to wind and transport the sheet P around the circumferential surface.
  • the drawing drum 242 is provided with a suction mechanism (not shown), and sucks the sheet P wound around the circumferential surface to the circumferential surface of the drum and conveys it. Negative pressure is used for adsorption.
  • the drawing drum 242 has a large number of suction holes on the circumferential surface, and sucks the sheet P on the circumferential surface of the drawing drum 242 by suctioning from inside the drawing drum 242 through the suction holes.
  • the circumferential surface of the drawing drum 242 on which the sheet P is suction-supported corresponds to the sheet support surface that supports the sheet P.
  • the circumferential surface of the drawing drum 242 corresponds to the conveyance surface.
  • the drawing drum 242 is an example of the “conveying unit”.
  • the sheet floating detection unit 245 is a unit that detects the floating of the sheet P conveyed by the drawing drum 242.
  • the floating of the sheet P is floating due to the wrinkles of the sheet P and / or the bending of the sheet P or the like.
  • the floating height of the sheet P that is, the floating amount is evaluated on the basis of the height from the reference printing surface which is the medium surface of the sheet P.
  • the floating amount of the sheet P may be evaluated by the height from the sheet supporting surface of the drawing drum 242.
  • the sheet floating detection unit 245 is disposed on the upstream side of the head unit 244 in the medium conveyance path of the drawing drum 242 and on the downstream side of the sheet pressing roller 247, and detects floating of the sheet P at a position before the head unit 244. .
  • the configuration of the medium floating detection device 10 shown in FIGS. 1 and 7 to 19 can be applied to the paper floating detection unit 245.
  • the light emitting unit 12 and the light receiving unit 14 are divided on both sides of the drawing drum 242 in the axial direction of the drawing drum 242 and arranged to face each other.
  • the axial direction of the drawing drum 242 is a direction parallel to the rotation axis of the drawing drum 242.
  • the optical axis of the beam projected from the light projector 12 is parallel to the axial direction of the drawing drum 242, and the beam passes near the surface of the drawing drum 242.
  • the head unit 244 includes ink jet heads 246K, 246C, 246M, and 246Y.
  • the inkjet head 246 K is a recording head that discharges black (K) ink droplets.
  • the inkjet head 246C is a recording head that discharges cyan (C) ink droplets.
  • the inkjet head 246M is a recording head that ejects a droplet of magenta (M) ink.
  • the inkjet head 246Y is a recording head that discharges a droplet of yellow (Y) ink.
  • the term "inkjet head” or “recording head” may be simply referred to as "head”.
  • Ink is supplied to each of the inkjet heads 246K, 246C, 246M, and 246Y from an ink tank (not shown) which is an ink supply source of the corresponding color through a piping path (not shown).
  • Each of the inkjet heads 246 K, 246 C, 246 M, and 246 Y is configured by a line head capable of printing by one scan on the sheet P conveyed by the drawing drum 242, that is, by a single pass method.
  • the nozzle faces of the inkjet heads 246 K, 246 C, 246 M, and 246 Y are disposed so as to face the circumferential surface of the drawing drum 242.
  • the inkjet heads 246 K, 246 C, 246 M, and 246 Y are arranged at regular intervals along the transport path of the sheet P by the drawing drum 242.
  • a plurality of nozzles which are ejection openings, are two-dimensionally arranged on the nozzle surface of each of the inkjet heads 246K, 246C, 246M, and 246Y.
  • the “nozzle surface” refers to a discharge surface on which the nozzles are formed, and is synonymous with the terms “ink discharge surface” or “nozzle formation surface”.
  • the nozzle arrangement of the plurality of nozzles arranged two-dimensionally is referred to as "two-dimensional nozzle arrangement”.
  • a water repellent film is formed on the nozzle surface of each of the inkjet heads 246K, 246C, 246M, and 246Y.
  • Each of the inkjet heads 246K, 246C, 246M, and 246Y can be configured by joining a plurality of head modules in the sheet width direction.
  • Each of the inkjet heads 246K, 246C, 246M and 246Y is a line type recording head having a nozzle array capable of recording an image according to a predetermined recording resolution in a single scan over the entire recording area of the sheet P in the sheet width direction. It is.
  • Such a recording head is also called a "full line type recording head" or a "page wide head”.
  • the predetermined recording resolution may be a recording resolution predetermined by the inkjet printing apparatus 201A, or may be set by user selection or automatic selection by a program according to the print mode.
  • the recording resolution can be, for example, 1200 dpi. “Dpi” means dot per inch and is a unit notation representing the number of dots (dots) per inch. One inch is 25.4 mm [mm].
  • the sheet width direction orthogonal to the conveyance direction of the sheet P may be referred to as the nozzle row direction of the line head, and the conveyance direction of the sheet P may be referred to as the nozzle row vertical direction.
  • a projected nozzle array obtained by projecting (orthogonal projection) the nozzles in the two-dimensional nozzle array to align along the nozzle array direction achieves the maximum recording resolution in the nozzle array direction.
  • the nozzle density is equivalent to a single nozzle row in which the nozzles are arranged substantially at equal intervals.
  • the "generally equal intervals" means substantially equal intervals as droplet deposition points that can be recorded by the ink jet printing apparatus.
  • the term "evenly spaced” is also included in the case where the spacing is slightly different in consideration of manufacturing errors and / or movement of droplets on the medium due to landing interference.
  • the projection nozzle row corresponds to a substantial nozzle row.
  • the nozzle numbers representing the nozzle position can be associated with each nozzle in the order of the projection nozzles arranged in the nozzle array direction.
  • the arrangement form of the nozzles in each of the inkjet heads 246K, 246C, 246M, and 246Y is not limited, and various nozzle arrangement forms can be adopted.
  • a line array linear array, a V-shaped nozzle array, a W-shaped nozzle array having a V-shaped array as a repeating unit, etc. are also possible It is.
  • Ink droplets are ejected from at least one of the inkjet heads 246 K, 246 C, 246 M, and 246 Y toward the sheet P conveyed by the drawing drum 242, and the ejected droplets adhere to the sheet P. , And an image is formed on the sheet P.
  • the drawing drum 242 functions as a means for relatively moving the inkjet heads 246 K, 246 C, 246 M, 246 Y and the paper P.
  • the drawing drum 242 is an example of a medium transport mechanism that transports the sheet P with respect to the inkjet heads 246K, 246C, 246M, and 246Y.
  • the ejection timings of the inkjet heads 246 K, 246 C, 246 M, and 246 Y are synchronized with an encoder signal obtained from an encoder provided on the drawing drum 242.
  • the illustration of the encoder is omitted in FIG.
  • the ejection timing is timing for ejecting ink droplets, and is synonymous with droplet ejection timing.
  • the configuration using the four colors of CMYK is exemplified, but the combination of the ink color and the number of colors is not limited to this embodiment, and light ink, dark ink, special color ink, etc. may be used if necessary. May be added.
  • an inkjet head that ejects light-based inks such as light cyan and light magenta
  • an inkjet head that ejects ink of a special color such as green or orange.
  • the arrangement order of the inkjet heads of each color is not particularly limited.
  • the image reading device 248 is a device that optically reads an image recorded on the sheet P by the inkjet heads 246 K, 246 C, 246 M, and 246 Y, and generates electronic image data indicating the read image.
  • the image reading device 248 includes an imaging device that picks up an image recorded on the sheet P and converts it into an electrical signal indicating image information.
  • the image reading device 248 may include, in addition to the imaging device, an illumination optical system that illuminates an object to be read and a signal processing circuit that processes signals obtained from the imaging device to generate digital image data.
  • the image reader 248 is preferably configured to be able to read a color image.
  • a color CCD (Charge-Coupled Device) linear image sensor is used as an imaging device in the image reading device 248 of this example.
  • the color CCD linear image sensor is an image sensor in which light receiving elements having color filters of red (R), green (G) and blue (B) are linearly arranged.
  • a color CMOS (Complementary Metal Oxide Semiconductor) linear image sensor may be used instead of the color CCD linear image sensor.
  • the image reading device 248 reads an image on the sheet P while the sheet P is being conveyed by the drawing drum 242.
  • the image reading apparatus installed in the medium transport path in this manner may be called an "in-line scanner” or an “in-line sensor”.
  • the image reader 248 may also be a camera.
  • the sheet P on which an image is recorded using at least one of the inkjet heads 246 K, 246 C, 246 M, and 246 Y passes the reading area of the image reading device 248, the image on the sheet P is read.
  • the image recorded on the sheet P in addition to the user image to be printed specified in the job, a defective nozzle detection pattern for inspecting the ejection state for each nozzle, a test pattern for print density correction, and various other tests Patterns may be included.
  • the printed image is inspected based on the data of the read image read by the image reading device 248, and it is determined whether or not the image quality is abnormal. Further, based on the data of the read image read by the image reading device 248, information such as the density of the image and the ejection failure of the inkjet heads 246K, 246C, 246M, and 246Y can be obtained.
  • the ink drying unit 250 dries the sheet P on which the image is formed by the drawing unit 240.
  • the ink drying unit 250 includes a chain gripper 270, a sheet guide 280, and a heating and drying processing unit 290.
  • the chain gripper 270 receives the sheet P from the drawing drum 242 and conveys the received sheet P to the stacking unit 260.
  • the chain gripper 270 includes a pair of endless chains 272 traveling along a prescribed traveling path, and conveys the paper P in a prescribed manner in a state in which the leading end of the paper P is gripped by the grippers 274 provided on the pair of chains 272 Transport along the route.
  • a plurality of grippers 274 are provided on the chain 272 at regular intervals.
  • the chain gripper 270 of this example includes a first sprocket 271A, a second sprocket 271B, a chain 272, and a plurality of grippers 274, and the pair of first sprockets 271A and second sprockets 271B includes a pair The endless chain 272 is wound around. Only one of the pair of first sprockets 271A and the second sprockets 271B and the pair of chains 272 is shown in FIG.
  • the chain gripper 270 has a structure in which a plurality of grippers 274 are disposed at a plurality of positions in the feed direction of the chain 272. Further, the chain gripper 270 has a structure in which a plurality of grippers 274 are disposed between the pair of chains 272 along the sheet width direction. Of the plurality of grippers 274 disposed between the pair of chains 272, only one gripper 274 is illustrated in FIG.
  • the conveyance path of the sheet P by the chain gripper 270 includes a horizontal conveyance area for conveying the sheet P in the horizontal direction, and an inclined conveyance area for conveying the sheet P obliquely upward from the end of the horizontal conveyance area.
  • the horizontal conveyance area is referred to as a first conveyance section, and the inclined conveyance area is referred to as a second conveyance section.
  • the sheet guide 280 is a mechanism for guiding the conveyance of the sheet P by the chain gripper 270.
  • the sheet guide 280 includes a first sheet guide 282 and a second sheet guide 284.
  • the first sheet guide 282 guides the sheet P conveyed on the first conveyance section of the chain gripper 270.
  • the second sheet guide 284 guides the sheet conveyed in the second conveyance section downstream of the first conveyance section.
  • the suction belt conveyance device is a device for conveying the sheet P by feeding the conveyance belt in a state where the sheet P is adsorbed to the endless conveyance belt.
  • the heating and drying processing unit 290 applies heat to the sheet P on which the image is formed by the drawing unit 240 to evaporate the solvent of the ink, thereby drying the sheet P.
  • the heating and drying processing unit 290 is, for example, a hot air blowing unit, is disposed to face the first sheet guide 282, and blows hot air to the sheet P conveyed by the chain gripper 270.
  • the stacking unit 260 includes a stacking device 262 that receives and stacks the sheets P conveyed from the ink drying unit 250 by the chain gripper 270.
  • the chain gripper 270 releases the sheet P at a predetermined stacking position.
  • the stacking device 262 includes a stacking tray 262A, receives the sheets P released from the chain gripper 270, and stacks them on the stacking tray 262A.
  • the stacking unit 260 corresponds to a paper discharge unit.
  • the inkjet printing apparatus 201A can move each of the inkjet heads 246K, 246C, 246M, and 246Y individually in the normal direction of each nozzle surface. It has an elevator.
  • the head elevating unit is described as reference numeral 126 in FIGS. 20 and 27.
  • the head elevating unit 126 can be used to change the distance (gap) between the nozzle surface of each head and the outer peripheral surface of the drawing drum 242.
  • Each of the inkjet heads 246 K, 246 C, 246 M, and 246 Y can be moved from the printing position to the upper retraction position by the head elevating unit 126, and can be returned to the printing position from the retraction position.
  • “upper” refers to a direction in which the outer side of the drawing drum 242 is separated from the circumferential surface of the drawing drum 242 as the medium support surface.
  • the printing position is a head position when each of the inkjet heads 246 K, 246 C, 246 M, and 246 Y records an image on the sheet P.
  • the retracted position is a position where the distance from the medium support surface of the drawing drum 242 above the printing position is long, and when the floating of the first reference height or more is detected, contact between the paper P and the head is detected. In order to avoid this, the heads are retracted.
  • the inkjet heads 246 K, 246 C, 246 M, and 246 Y of the respective colors in the drawing unit 240 are supported by a common head support frame.
  • the ink jet printing apparatus 201A moves the entire head unit 244 including the ink jet heads 246K, 246C, 246M, and 246Y attached to the head support frame up and down with the head support frame above the drawing drum 242. Equipped with
  • the ink jet printing apparatus 201A includes a head horizontal moving unit capable of horizontally moving the entire head unit 244 together with the head support frame in the axial direction of the drawing drum 242.
  • the head horizontal movement unit not shown in FIG. 26 is described as reference numeral 402 in FIG.
  • the inkjet printing apparatus 201A includes a maintenance unit that performs maintenance processing on the inkjet heads 246K, 246C, 246M, and 246Y.
  • the maintenance unit is installed in line with the drawing drum 242 in the axial direction of the drawing drum 242.
  • the maintenance unit is described as reference numeral 240 in FIG.
  • FIG. 27 is a block diagram showing a schematic configuration of a control system of the ink jet printing apparatus 201A.
  • the inkjet printing apparatus 201A includes a system controller 300.
  • the system controller 300 is configured to include a central processing unit (CPU) 300A, a read only memory (ROM) 300B, and a random access memory (RAM) 300C.
  • Storage units such as the ROM 300 ⁇ / b> B and the RAM 300 ⁇ / b> C may be provided outside the system controller 300.
  • the system controller 300 functions as an overall control unit that controls each part of the inkjet printing apparatus 201A in an integrated manner.
  • the system controller 300 also functions as an arithmetic unit that performs various arithmetic processes.
  • the system controller 300 functions as a memory controller that controls reading and writing of data in memories such as the ROM 300B and the RAM 300C.
  • the inkjet printing apparatus 201A includes a communication unit 302, an image memory 304, an image processing unit 306, a transport control unit 120, a paper feed control unit 312, a treatment liquid application control unit 314, a treatment liquid drying control unit 316, a drawing control unit 318, and a head.
  • An elevation control unit 122, a head horizontal movement control unit 322, an ink drying control unit 324, a paper discharge control unit 326, and a maintenance control unit 328 are provided. Elements of these units can be realized by one or more computers. That is, the elements of each control unit including the system controller 300 can be configured by a combination of computer hardware and software. In addition, part or all of the processing functions necessary for control may be realized using an integrated circuit represented by a digital signal processor (DSP) or a field programmable gate array (FPGA).
  • DSP digital signal processor
  • FPGA field programmable gate array
  • the system controller 300 may include some or all of the functions of the control device 110 described in FIG.
  • the communication unit 302 includes a communication interface (not shown), and can transmit and receive data to and from the host computer 400 connected to the communication interface.
  • the image memory 304 functions as a temporary storage unit of various data including image data. Image data captured from the host computer 400 via the communication unit 302 is temporarily stored in the image memory 304.
  • the image processing unit 306 generates dot data from input image data.
  • the image processing unit 306 includes a color separation processing unit, a color conversion processing unit, a correction processing unit, and a halftone processing unit.
  • the image processing unit 306 performs color separation processing for separating input image data into each color of RGB, color conversion processing for converting RGB data to CMYK data, various correction processing such as gamma correction, unevenness correction, and pixels of each color Halftone processing is performed to convert each tone value into a tone value less than the original tone value.
  • the correction process performed by the image processing unit 306 includes a process of defect correction that suppresses an image defect caused by a defective nozzle.
  • the input image data is continuous tone image data.
  • An example of input image data is raster data represented by digital values of 0 to 255.
  • the dot data obtained as a result of the halftone process may be binary or may be a multivalue of three or more and less than the gradation value before the halftone process.
  • Some or all of the processing functions of the image processing unit 306 may be included in the system controller 300 or the drawing control unit 318.
  • the conveyance control unit 120 controls the operation of the conveyance system 211 of the sheet P in the inkjet printing apparatus 201A.
  • the conveyance system 211 includes a medium conveyance mechanism such as the feed drum 216, the treatment liquid application drum 222, the treatment liquid drying drum 232, and the drawing drum 242 shown in FIG. Further, the transport system 211 includes a motor as a power source (not shown) and a drive unit such as a motor drive circuit.
  • the paper feed control unit 312 shown in FIG. 27 operates the paper feed unit 210 in response to an instruction from the system controller 300.
  • the paper feed control unit 312 controls the supply start operation of the sheet P, the supply stop operation of the sheet P, and the like.
  • the treatment liquid deposition control unit 314 operates the treatment liquid deposition unit 220 in accordance with the command from the system controller 300.
  • the treatment liquid application control unit 314 controls the application amount of the treatment liquid, the application timing, and the like.
  • the drawing control unit 318 controls the drawing operation of the head unit 244 in accordance with an instruction from the system controller 300.
  • the drawing control unit 318 includes a waveform generation unit, a waveform storage unit, and a drive circuit. Illustration of a waveform generation part, a waveform storage part, and a drive circuit is omitted.
  • the waveform generation unit generates a waveform of a drive voltage for causing each ink jet head of the head unit 244 to perform a discharge operation.
  • the waveform storage unit stores the waveform of the drive voltage.
  • the drive circuit generates a drive voltage having a drive waveform according to the dot data.
  • the drive circuit supplies a drive voltage to the inkjet head of the head unit 244.
  • the inkjet printing apparatus 201 ⁇ / b> A includes an encoder 406 as means for detecting the rotation angle of the drawing drum 242 in the transport system 211.
  • the encoder 406 is provided on the drawing drum 242, and outputs a signal corresponding to the transport amount of the sheet P by the drawing drum 242.
  • a rotary encoder that outputs a pulse signal for each unit rotation angle of the rotation axis of the drawing drum 242 is used.
  • the ejection timing of each of the inkjet heads 246 K, 246 C, 246 M, and 246 Y is controlled in accordance with the ejection timing signal generated from the encoder signal output from the encoder 406.
  • the discharge timing and the ink discharge amount of each pixel position are determined based on the dot data generated through the processing by the image processing unit 306, the discharge timing of each pixel position, the driving voltage according to the ink discharge amount, and each pixel
  • the control signal which determines the discharge timing of is generated.
  • the drive voltage generated by the drawing control unit 318 is supplied to the inkjet head, and dots are formed by the ink ejected from the inkjet head.
  • the head elevation control unit 122 operates the head elevation unit 126 in accordance with a command from the system controller 300.
  • the head elevating unit 126 includes a mechanism for moving the ink jet heads 246 K, 246 C, 246 M, and 246 Y up and down in the direction normal to the nozzle surface, and a motor serving as a motive power source.
  • the sheet floating detection unit 245 may include a circuit that determines the presence or absence of the sheet P floating based on the signal output from the light receiver 32. The information detected by the sheet floating detection unit 245 is sent to the system controller 300.
  • the system controller 300 sends a command to move each ink jet head 246 K, 246 C, 246 M, 246 Y to the retraction position to the head elevation control unit 122 based on the detection information obtained from the sheet floating detection unit 245 Can. For example, when floating of the first reference height and the second reference height is detected by the sheet floating detection unit 245, the head elevating unit 126 is driven to print the inkjet heads 246K, 246C, 246M, and 246Y. It is moved from the position to the upper retraction position.
  • the inkjet heads 246K, 246C, 246M, and 246Y are returned from the retracted position to the printing position.
  • the system controller 300 can send an instruction to stop the driving of the conveyance system 211 to the conveyance control unit 120 based on the detection information obtained from the sheet floating detection unit 245. For example, when the paper floating detection unit 245 detects floating of the second reference height or more, the conveyance system 211 is stopped.
  • the head horizontal movement control unit 322 operates the head horizontal movement unit 402 in accordance with an instruction from the system controller 300.
  • the head horizontal moving unit 402 includes a mechanism for horizontally moving the head unit 244 in the axial direction of the drawing drum 242 and a motor as a power source of the mechanism.
  • the head horizontal moving unit 402 moves the inkjet heads 246 K, 246 C, 246 M, and 246 Y between the drawing unit 240 and the maintenance unit 440.
  • the ink drying control unit 324 operates the ink drying unit 250 in response to a command from the system controller 300.
  • the ink drying control unit 324 controls the drying gas temperature, the flow rate of the drying gas, and / or the injection timing of the drying gas.
  • the paper discharge control unit 326 operates the stacking unit 260 in response to an instruction from the system controller 300.
  • the paper discharge control unit 326 controls the operation of the elevating mechanism in accordance with the increase and decrease of the sheets P.
  • the discharge control unit 326 may control the sorting of the printed matter.
  • Maintenance control unit 328 controls the operation of maintenance unit 440 in accordance with a command from system controller 300.
  • the maintenance unit 440 is a processing unit that performs maintenance processing such as capping for cleaning and / or moisturizing the nozzle surfaces of the inkjet heads 246 K, 246 C, 246 M, and 246 Y. Examples of the maintenance process include pressurized purge, dummy jets, nozzle suction, or wiping of the nozzle surface, or an appropriate combination thereof. "Dummy jet” is synonymous with preliminary discharge.
  • a cap that covers the nozzle surface of each of the inkjet heads 246K, 246C, 246M, and 246Y, and a wiping member such as a web that wipes the nozzle surface are disposed.
  • the inkjet printing apparatus 201A includes an operation unit 330, a display unit 332, a parameter storage unit 334, and a program storage unit 336.
  • the operation unit 330 includes an input device including operation buttons, a keyboard, a mouse, an operation member such as a touch panel, a voice input device, or an appropriate combination thereof. Information input via the operation unit 330 is sent to the system controller 300.
  • the operation unit 330 may be the input device 132 described in FIG.
  • the system controller 300 executes various processes in accordance with the information input from the operation unit 330.
  • the display unit 332 includes a display device such as a liquid crystal panel.
  • the display unit 332 can display various information such as various setting information of the apparatus or abnormality information in accordance with an instruction from the system controller 300.
  • the user can set various parameters and input and edit various information using the operation unit 330 while viewing the content displayed on the screen of the display unit 332.
  • the display unit 332 may be the display device 130 described in FIG.
  • the parameter storage unit 334 stores various parameters used in the inkjet printing apparatus 201A.
  • the various parameters stored in the parameter storage unit 334 are read via the system controller 300 and set in the respective units of the apparatus.
  • the program storage unit 336 stores a program used in each unit of the inkjet printing apparatus 201A.
  • the various programs stored in the program storage unit 336 are read via the system controller 300 and executed in the respective units of the apparatus.
  • the parameter storage unit 334 and the program storage unit 336 are configured using storage devices such as a hard disk drive and / or a semiconductor memory.
  • Example of arrangement of paper floating detection unit in drawing unit >> As described above, the medium floating detection device 10 is incorporated in the ink jet printing apparatus 201A, and the floating of the paper P is detected before ink droplet ejection.
  • FIG. 28 is a perspective view showing an example of the light emitting unit 12 and the light receiving unit 14 of the medium floating detection device 10 disposed in the drawing unit 240.
  • the light emitting unit 12 and the light receiving unit 14 are disposed to face each other with the conveying surface 242A of the drawing drum 242 in the axial direction.
  • illustration of the first parallel flat plate 42 and the second parallel flat plate 44 described in FIG. 1 is omitted.
  • the air blowing mechanism 90 described with reference to FIG. 20 is not shown.
  • the light projecting unit 12 is attached to the main body frame of the inkjet printing apparatus 201A via a bracket (not shown).
  • the light receiving unit 14 is attached to the main body frame of the inkjet printing apparatus 201A via a bracket (not shown).
  • the ejectors of the inkjet heads 246K, 246C, 246M, and 246Y are configured to include a nozzle that discharges liquid, a pressure chamber that communicates with the nozzle, and a discharge energy generating element that supplies discharge energy to the liquid in the pressure chamber.
  • a piezoelectric element can be used as the ejection energy generating element.
  • the means for generating discharge energy is not limited to the piezoelectric element, and various discharge energy generating elements such as a heating element and an electrostatic actuator can be applied to the discharge method for discharging droplets from the nozzles of the ejector.
  • Corresponding discharge energy generating elements are provided in the flow path structure according to the discharge method of the ink jet head.
  • FIG. 29 is a schematic configuration diagram of an ink jet printing apparatus according to another embodiment.
  • the inkjet printing apparatus 500 shown in FIG. 29 includes a belt conveyance unit 540 as a medium conveyance mechanism for conveying the sheet P.
  • the belt conveyance unit 540 includes a roller 541A and an endless belt 542 wound around the roller 541B. By rotating either the roller 541A or the roller 541B counterclockwise in FIG. 29, the belt 542 is caused to travel in the direction indicated by the arrow line.
  • the sheet P supported by the medium support surface 542 A of the belt 542 is conveyed in the traveling direction of the belt 542.
  • the medium support surface 542A is an aspect of the medium conveyance surface.
  • the inkjet head 544 includes the same configuration as the inkjet heads 246K, 246C, 246M, and 246Y shown in FIG.
  • the sheet floating detection unit 245 detects the floating of the sheet P in multiple stages before the inkjet head 544.
  • the configurations shown in FIGS. 1 to 18 can be appropriately applied to the ink jet printing apparatus 500 shown in FIG.
  • the hardware-like structure of a processing unit (processing unit) that executes various processes such as 328 is, for example, various processors as shown below.
  • processors are processors that can change the circuit configuration after manufacturing a central processing unit (CPU) or a field programmable gate array (FPGA) that is a general-purpose processor that executes programs and functions as various processing units.
  • the circuit includes a dedicated electric circuit which is a processor having a circuit configuration specially designed to execute a specific process such as a programmable logic device (PLD) or an application specific integrated circuit (ASIC).
  • PLD programmable logic device
  • ASIC application specific integrated circuit
  • One processing unit may be configured of one of these various processors, or may be configured of two or more processors of the same or different types.
  • one processing unit may be configured by a plurality of FPGAs or a combination of a CPU and an FPGA.
  • a plurality of processing units may be configured by one processor.
  • a plurality of processing units are configured by one processor, first, one processor or more is configured by a combination of one or more CPUs and software, as represented by computers such as clients and servers.
  • a processor functions as a plurality of processing units.
  • SoC system on chip
  • IC Integrated Circuit
  • circuitry circuitry
  • 26 illustrates the drawing drum 242 as the medium conveyance mechanism
  • FIG. 29 illustrates the belt conveyance unit 540 as the medium conveyance mechanism.
  • a media transport mechanism such as a roll transport system may be employed.
  • the detection beam is projected in parallel with the X axis. It may project not only in a form but in the diagonal direction which intersects the X-axis, ie, a direction which is not parallel to the X-axis.
  • the directions (posture) of the openings 24A and 24B in the aperture member 24 described with reference to FIG. 6 may be appropriately rotated in the YZ plane of FIG.
  • the rectangular openings 24A and 24B may be arranged in a posture in which each side is inclined at an angle of 45 ° with respect to the Y direction.
  • each of the openings 24A and 24B is disposed in the non-diffracted light generation region, avoiding the generation region of the diffracted light created by the other openings.
  • the opening shape of the opening formed in the aperture member 24 is not limited to a rectangular shape, and may be a rhombus or parallelogram as shown in FIG.
  • FIG. 31 schematically shows one opening, a diffracted light generation area DA created by the opening, and a diffracted light non-generation area ND.
  • the diffracted light generation area DA is formed in a direction orthogonal to each side of the opening.
  • a second opening (not shown) is disposed in the diffracted light non-generation region ND.
  • the shape of the opening formed in the aperture member 24 is not limited to a square, but may be various polygons, and may be, for example, a triangle.
  • FIG. 32 schematically shows an example of a diffracted light generation region formed by triangular openings and a diffracted light non-generation region. A second opening (not shown) is disposed in the diffracted light non-generation region ND.
  • the shape of the opening formed in the aperture member 24 may be hexagonal.
  • FIG. 33 schematically shows an example of a diffracted light generation region formed by hexagonal openings and a diffracted light non-generation region.
  • a second opening (not shown) is disposed in the diffracted light non-generation region ND.
  • a single beam is divided into a plurality of beams through an aperture member 24 having a plurality of apertures using a pair of light emitters 22 and light receivers 32, and a plurality of light receiving amounts by the light receivers 32 are obtained.
  • the adjustment of the optical axis can be simplified as compared with the embodiment in which a plurality of transmission type laser sensors are arranged, since the adjustment of the optical axis may be performed for one set of the light emitter 22 and the light receiver 32.
  • the medium floating detection apparatus can realize multistage floating detection with a small space, as compared with the configuration in which a plurality of transmission type laser sensors are arranged.
  • a light projector having a configuration in which the beam expander 26 as a beam shaping optical system for changing the beam diameter is disposed in the light projecting unit 12 and a convex lens 36 as a lens for condensing the beam is disposed in the light receiving unit 14 Even when the diameter of the beam emitted from 22 is relatively small, the range of the beam can be expanded and used to the range of the float to be detected.
  • the configuration including the blowing mechanism 90 By employing the configuration including the blowing mechanism 90, the temperature boundary layer in the vicinity of the medium surface of the sheet P can be destroyed. As a result, it is possible to suppress the bending of the beam due to the heat buildup phenomenon or the mirage phenomenon and to reduce the signal noise.
  • the single-pass type inkjet printing apparatus has been described in the above embodiment, the scope of application of the present invention is not limited to this, and a plurality of short print heads such as serial (shuttle scan) heads may be moved.
  • the present invention is also applicable to an image forming apparatus that performs image recording by head scanning of the above.
  • the heads may be arranged separately for the colors of the plurality of colors of ink, or even one ink may be ejected from a single recording head. Good.
  • composition which conveys paper to a head stopped to a printing position was illustrated, composition which moves a head to paper P is also possible in the case of implementation of the present invention.
  • a single-pass line head is usually disposed along the medium width direction orthogonal to the medium conveyance direction, a predetermined angle is given to the medium width direction orthogonal to the medium conveyance direction.
  • the line head is disposed along the oblique direction.
  • the medium floating detection device of the present invention can be applied to image forming devices in various printing methods other than the inkjet printing device.
  • a wiring drawing apparatus for drawing a wiring pattern of an electronic circuit a manufacturing apparatus for various devices, a resist printing apparatus using a resin liquid as a functional liquid for discharge, a color filter manufacturing apparatus, and a minute using a material for material deposition.
  • the present invention is also applicable to an image forming apparatus that obtains various shapes and patterns using a liquid functional material, such as a microstructure forming apparatus that forms a structure.
  • the transmission type detection apparatus of the present invention is not limited to the mode used as a medium floating detection apparatus for detecting floating of a medium to be transported in multiple stages, and can be applied to various applications. That is, the objects to be detected by the plurality of beams are not limited to floating on the medium to be transported, and can be various objects.
  • the object to be detected may be, for example, a mechanical component, an electronic component, various products, foreign matter, or a structure.
  • transmission detection devices for various applications using a plurality of beams are provided. The present invention can be applied.
  • Paper is a medium used to record an image.
  • the term paper includes the concept of what is called various terms such as recording medium, recording paper, printing paper, printing medium, printing medium, printing medium, imaging medium, imaging medium, image receiving medium, ejection medium, and the like.
  • the material, shape, and the like of the sheet are not particularly limited, and various sheet materials can be used regardless of the type and shape of the seal sheet, resin sheet, film, cloth, non-woven fabric, and the like.
  • the paper is not limited to a sheet-like medium, but may be a continuous medium such as continuous paper. Further, the sheet is not limited to a cut sheet prepared in advance to a prescribed size, and may be obtained by cutting from a continuous medium to a prescribed size at any time.
  • printing device includes the concept of terms such as printing machines, printers, printing devices, image forming devices, image output devices, or drawing devices. Also, the term “printing device” includes the concept of a printing system combining multiple devices. “Printing” is used as a term covering the meaning of recording, printing, printing, drawing, or image formation. The “recording" of an image includes the concept of terms such as image formation, printing, printing, drawing, and printing.
  • image is to be interpreted in a broad sense, and includes color images, black and white images, single color images, gradation images, uniform density (solid) images, and the like.
  • image is not limited to a photographic image, and includes a pattern, characters, symbols, line drawings, mosaic patterns, color division patterns, line patterns, dot patterns, various other patterns, test charts, or a suitable combination thereof. Used as a comprehensive term.
  • the “image” is not limited to one formed by the ink containing the coloring material, and other functions such as a treatment liquid applied to the paper before applying the ink, and / or a varnish applied to the paper after applying the ink, etc. It may be an image formed by a sex material.
  • recording head is synonymous with the terms “printing head,” “printing head,” “printing head,” “drawing head,” and the like, and an inkjet head, an ink ejection head, a liquid ejection head, a droplet ejection head, or a droplet ejection head. Including the concept.
  • homogeneous in the present specification includes aspects which are not strictly homogeneous and which can be regarded as substantially “homogeneous” in which substantially the same effects as in the case of being homogeneous can be obtained.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Controlling Sheets Or Webs (AREA)
  • Handling Of Sheets (AREA)

Abstract

L'invention concerne un dispositif de détection de type transmissif qui peut effectuer une détection très précisément en utilisant une configuration simple, un dispositif de détection de milieu flottant, et un dispositif de formation d'images. Un mode de réalisation de ce dispositif de détection de type transmissif comprend : une unité de projection de lumière (12); un élément d'ouverture (24) qui est disposé dans l'unité de projection de lumière (12) et qui comporte une pluralité d'ouvertures (24A, 24B) dans lesquelles passe la lumière; une unité de réception de lumière (14) qui reçoit des faisceaux projetés sur une zone de passage par l'intermédiaire de la pluralité d'ouvertures; et une unité de logique arithmétique qui compare la quantité de lumière reçue par l'unité de réception de lumière (14) à une pluralité de valeurs seuils prédéfinies et qui délivre un signal correspondant au résultat de la comparaison. Chaque ouverture de la pluralité d'ouvertures (24A, 24B) a une forme polygonale. La pluralité d'ouvertures (24A, 24B) est disposée dans des positions chevauchant une zone de non-génération de lumière diffractée, qui est une zone à l'extérieur d'une zone de génération de lumière diffractée dans laquelle la lumière diffractée d'un faisceau traversant l'autre ouverture est générée.
PCT/JP2018/044397 2018-01-19 2018-12-03 Dispositif de détection de type transmissif, dispositif de détection de milieu flottant et dispositif de formation d'images Ceased WO2019142518A1 (fr)

Priority Applications (1)

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JP2019565747A JP6886049B2 (ja) 2018-01-19 2018-12-03 透過型検出装置、媒体浮き検出装置並びに画像形成装置

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JP2018007268 2018-01-19
JP2018-007268 2018-01-19

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WO2019142518A1 true WO2019142518A1 (fr) 2019-07-25

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011195221A (ja) * 2010-03-17 2011-10-06 Fujifilm Corp 用紙浮き検出装置及びインクジェット記録装置
JP2014166901A (ja) * 2013-02-28 2014-09-11 Fujifilm Corp 記録媒体浮き検出装置及びインクジェット記録装置
JP2015202601A (ja) * 2014-04-11 2015-11-16 株式会社リコー 液滴吐出状態検出装置及びこの液滴吐出状態検出装置を備えた画像形成装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011195221A (ja) * 2010-03-17 2011-10-06 Fujifilm Corp 用紙浮き検出装置及びインクジェット記録装置
JP2014166901A (ja) * 2013-02-28 2014-09-11 Fujifilm Corp 記録媒体浮き検出装置及びインクジェット記録装置
JP2015202601A (ja) * 2014-04-11 2015-11-16 株式会社リコー 液滴吐出状態検出装置及びこの液滴吐出状態検出装置を備えた画像形成装置

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