JP3753684B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an image reading apparatus that reads an image on a document and generates image data, and more particularly to an image reading apparatus having a show-through removal function and an image forming apparatus using the image reading apparatus. This image processing apparatus can be used in, for example, an image pickup apparatus such as a document scanner or a digital camera, a personal computer, a printer, a copier, a facsimile, or the like that processes the image data.
[0002]
[Prior art]
  When an image on a document is shot, a back image of the document or a pattern or dirt on the surface of the document press may appear on the shooting screen. In order to eliminate such show-through, many show-through removal functions or background removal functions have already been proposed.
[0003]
[Patent Document 1]
  In the image processing disclosed in Japanese Patent Laid-Open No. 2001-169080, the user sets a threshold value for removing the show-through according to the degree of show-through and the paper quality.The FragmentA method of extracting a show-through image on one side based on only the image information on the surface and generating an image from which the show-through image is removed is disclosed.
[0004]
[Patent Document 2]
  The image formation control disclosed in Japanese Patent Laid-Open No. 2001-313832 selects a show-through removal threshold depending on the type of image.
[0005]
[Problems to be solved by the invention]
  According to the prior art, the change of the removal level of the show-through removal is only arbitrarily designated by the user, and the user can arbitrarily set the level change and output the image formation once. It relied on trial and error level setting, setting the level again. This leads to waste of time for image output or waste of paper and developer.
[0006]
  An object of the present invention is to solve this problem and to efficiently perform show-through removal.
[0007]
[Means for Solving the Problems]
  (1) Document reading means (30, 10) for reading an image of a document and generating image information (O); and setting conditions (edge strength ≦ Ths) on the image represented by the image information (O) An image reading apparatus comprising: low density image removal means (45Ap) for converting the image data of the low density image (Rr) to be filled into corrected image information (P) obtained by correcting the image data representing an image obtained by erasing the low density image In
  Detect the thickness of the originalThickness detectionMeans (253,254);Conversion characteristics for converting the thickness detected by the thickness detection means into an index value ( Figure Five) Input means for the user to specify (329) The thickness detecting means has a conversion characteristic designated by the input means;Detected thicknessOnlyIndex value setting means (IPP: 9, 10 in FIG. 13) for converting (inversely proportional to Spt) into an index value (Ths) for determining whether or not the setting condition is satisfied, and using the index value An image reading apparatus comprising: means (IPP: 14 to 16b in FIG. 14) for extracting image data of the low-density image.
[0008]
  In order to facilitate understanding, the corresponding elements of the embodiments shown in the drawings and the symbols or the corresponding matters of the corresponding examples shown in the drawings are added for reference as examples. The same applies to the following.
[0009]
  In general, if the original is thin, a show-through image may appear and the density may be high. Therefore, for example, the detected thickness of the document (inversely proportional to Spt) is converted to a higher index value (Ths: Tpmax in FIG. 5) by the index value setting means (IPP: 9, 10 in FIG. 13), By the extraction means (IPP: 14, 16b in FIG. 14) and the low-density image removal means (45Ap: 15, 16a in FIG. 14), the edge whose image edge strength is weaker than the index value (Ths) is regarded as the edge of the show-through image. The show-through image is automatically removed by replacing it with background color image data. Appropriate show-through removal is performed efficiently. Compared with the user's threshold setting work, such as checking the suitability of the index value (Ths) by outputting the corrected image information (P) once, it reduces the waste of time or the waste of supply and removes the show-through. It becomes possible to carry out efficiently.
[0010]
  For documents with high transmissivity, for example, an index value for the detected thickness (Ths) The user can select the degree of the show-through image removal in correspondence with the paper quality, such as selecting a conversion characteristic (FIG. 5B) that increases the degree of the show-off image and increases the degree of the show-through image removal. It is possible to expect a favorable show-through removal by the user's judgment and operation.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
  (2)The thickness detecting means includes a reflecting member having a front surface in close contact with the original and a back surface having a reflecting surface. (255) , And displacement detection means for detecting the amount of displacement of the reflecting member due to the document (253,254) (1) aboveThe image reading apparatus described in 1.
[0012]
  (3) Furthermore,Low density image removal (45Ap) Deleted low density image information (Rr) The image represented by (328) Image output means (20)The image reading apparatus according to the above (1) or (2).
[0013]
  According to this, the image output means (20) By low density image removal (45Ap) Deleted low density image information (Rr) Is displayed. The user can check this image and confirm whether there is an erroneous image removal.
[0014]
  (4) and an input means (311 of 79) for a user to instruct conversion to corrected image information by the low-density image removing means, and the low-density image removing means only when there is such an instruction. in frontRecordThe image reading device according to any one of (1) to (3), wherein conversion processing is performed.
[0015]
  For example, in the case of a document that is viewed as having no possibility of show-through, if the user cancels the instruction to convert to corrected image information by the input means (311 of 79), there is no possibility of erroneous show-through removal. There is no document reading. A favorable document image reading can be expected by the user's judgment and operation.
[0016]
  (5) The original reading means (30, 10) is a double-sided reading means capable of reading the image on the front side of the original and reading the image on the back side to generate image information on each side; The means (45Ap) includes a front surface image information (O) of the original, a low density image (R) on the front surface that is a difference between the image information and the corrected image information (P) on the front surface, and image information on the back surface. Based on the above, (1) to (1) to (c) have a function (3a to 6 in FIG. 13) for generating a low-density image on the back surface and generating a difference between the low-density image on the back surface and the back-side image information (4) The image reading apparatus according to any one of (4).
[0017]
  When reading the image on the front side and the image on the back side of the document, in the image reading on the back side after the reading, based on the original image information (0) and the low density image (R) of the front surface known in advance, Since the low-density image removal of the original image information on the back surface is performed, the low-density image detection based only on the original image information on the back surface is omitted, and the time required for the color conversion process on the back surface can be shortened.
[0018]
  (6) The image reading device (30, 10, IPP) according to any one of (1) to (5); an image data processing means (IPP) for converting the image information into image data for image formation; An image forming apparatus comprising: an image forming means (100) for forming a visible image on a sheet based on the image forming image data.
[0019]
  According to this, the effect described in any one of (1) to (5) is obtained in color conversion and printout of an image.
[0020]
  (7) Further, the image information (O) generated by the document reading means (30, 10), the corrected image information (P) converted by the low density image removal (45Ap), and the erased low density image information (Rr) are represented. The image reading apparatus or the image forming apparatus according to any one of (1) to (6), further including an image output unit (20) that displays an image on a surface (328).
[0021]
  According to this, each image is displayed by the image output means (20). The user can check each image and confirm whether there is an erroneous image removal.
[0022]
  (8) The image output means (20) includes a display (79) for displaying an image on the surface and a display image selection means (318, 319) for the user to select and specify which image is displayed on the display; ).
[0023]
  (9) When an original image is read and the image is formed with an image forming medium (for example, toner), the image on the back side of the original or the next page of the original is prevented from being formed simultaneously with the original surface image. The function (hereinafter referred to as “the show-through removal function”) can be expected to have a high effect, is equipped with an automatic document feeder (ADF), and is equipped with a document thickness detection sensor in the ADF. In the image forming apparatus,
  An image forming apparatus that detects the thickness of a document when the document is scanned by the ADF, and changes the “removal of show-through” level according to the thickness of the document.
[0024]
  According to this, it is possible to suppress the waste of time or the waste and efficiently remove the show-through compared to the work of outputting the image formation once and checking the setting level. Become.
[0025]
  (10) The image forming apparatus according to (9), wherein the user can change the degree of the “removal of show-through” level according to the thickness of the document according to whether the user desires to use or not. According to this, it is possible to form a show-through removed image that is more in response to a user request.
[0026]
  (11) The image forming apparatus according to (9), wherein the user can change ON / OFF of the “document thickness detection type show-through removal function” according to whether the user desires to use or not. According to this, when it is not necessary to change the show-through removal level depending on the thickness, it can be turned off.
[0027]
  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.
[0028]
【Example】
  FIG. 1 shows the appearance of a multi-function full-color digital copying machine according to one embodiment of the present invention. This full-color copying machine is roughly constituted by units of an automatic document feeder (ADF) 30, an operation board 20, a color scanner 10, and a color printer 100. A finisher 34 with a tray capable of stacking a stapler and imaged paper, a double-sided drive unit 33, an additional paper feed bank 35, and a large capacity paper feed tray 36 are mounted on the printer 100. Peripheral unit separable from 100, each having a control board having a power device driver, sensor input, and controller, and directly with a control board (process controller 131 of FIG. 6) of the printer 100 as the image forming apparatus main body. Alternatively, communication is performed indirectly, and timing is controlled to perform sheet feeding and transport operations. The operation board 20 and the color scanner 10 with the ADF 30 are also units that can be separated from the printer 100. The color scanner 10 also has a control board having a power device driver, a sensor input, and a controller. The document image is read by controlling the timing by directly or indirectly communicating with the document.
[0029]
  A LAN (Local Area Network) to which a personal computer PC is connected is connected to the image data processing apparatus ACP (FIG. 6), and a telephone line PN (facsimile communication line) is connected to the facsimile control unit FCU (FIG. 6). Is connected to the exchange PBX. The printed paper of the color printer 100 is discharged onto the paper discharge tray 108 or the finisher 34.
[0030]
  FIG. 2 shows the mechanism of the color printer 100. The color printer 100 of this embodiment is a laser printer. In this laser printer 100, four sets of toner image forming units for forming images of each color of magenta (M), cyan (C), yellow (Y), and black (black: K) are in the transfer paper moving direction. They are arranged in this order along (from the lower right to the upper left direction y in the figure). That is, it is a four-drum type full-color image forming apparatus.
[0031]
  These magenta (M), cyan (C), yellow (Y) and black (K) toner image forming units are respectively photoconductor units 110M, 110C, 110Y having photoconductor drums 111M, 111C, 111Y and 111K. 110K and developing units 120M, 120C, 120Y and 120K. Also, the arrangement of each toner image forming unit is such that the rotation axes of the photosensitive drums 111M, 111C, 111Y and 111K in each photosensitive unit are parallel to the horizontal x-axis (main scanning direction), and transfer paper. It is set so as to be arranged at a predetermined pitch in the movement direction y (sub-scanning direction).
[0032]
  In addition to the toner image forming unit, the laser printer 100 carries an optical writing unit 102 by laser scanning, paper feed cassettes 103 and 104, a pair of registration rollers 105, and transfer paper to support each toner image forming unit. The image forming apparatus includes a transfer belt unit 106 having a transfer conveyance belt 160 that conveys the transfer position so as to pass through, a belt fixing type fixing unit 107, a paper discharge tray 108, a duplex drive (surface reversal) unit 33, and the like. The laser printer 100 also includes a manual feed tray, a toner supply container, a waste toner bottle, and the like (not shown).
[0033]
  The optical writing unit 102 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and oscillates laser light in the x direction on the surfaces of the photosensitive drums 111M, 111C, 111Y, and 111K based on image data. Irradiate while scanning. Also, the alternate long and short dash line in FIG. 2 indicates the transfer path of the transfer paper. The transfer paper fed from the paper feed cassettes 103 and 104 is transported by a transport roller while being guided by a transport guide (not shown), and is sent to the registration roller pair 105. The transfer paper sent to the transfer conveyance belt 160 at a predetermined timing by the registration roller pair 105 is carried by the transfer conveyance belt 160 and is conveyed so as to pass through the transfer position of each toner image forming unit.
[0034]
  The toner images formed on the photosensitive drums 111M, 111C, 111Y, and 111K of each toner image forming unit are transferred to a transfer sheet carried and conveyed by the transfer conveyance belt 160, and the color toner images are superimposed, that is, a color image is formed. The formed transfer paper is sent to the fixing unit 107. That is, the transfer is a direct transfer method in which a toner image is directly transferred onto a transfer sheet. When passing through the fixing unit 107, the toner image is fixed on the transfer paper. The transfer sheet on which the toner image is fixed is discharged or fed to the discharge tray 108, the finisher 36, or the double-sided drive unit 33.
[0035]
  The outline of the yellow Y toner image forming unit will be described below. Other toner image forming units have the same configuration as that of yellow Y. The yellow Y toner image forming unit includes the photoconductor unit 110Y and the developing unit 120Y as described above. In addition to the photosensitive drum 111Y, the photosensitive unit 110Y includes a brush roller that applies a lubricant to the surface of the photosensitive drum, a swingable blade that cleans the surface of the photosensitive drum, and a static elimination lamp that irradiates light on the surface of the photosensitive drum. , A non-contact type charging roller for uniformly charging the surface of the photosensitive drum, and the like.
[0036]
  Laser light modulated by the optical writing unit 102 and deflected by a polygon mirror on the surface of the photosensitive drum 111Y uniformly charged by a charging roller to which an AC voltage is applied in the photosensitive unit 110Y. When L is irradiated while scanning, an electrostatic latent image is formed on the surface of the photosensitive drum 111Y. The electrostatic latent image on the photosensitive drum 11IY is developed by the developing unit 20Y to become a yellow Y toner image. At the transfer position where the transfer paper on the transfer conveyance belt 160 passes, the toner image on the photosensitive drum 11IY is transferred to the transfer paper. The surface of the photosensitive drum 111Y after the toner image has been transferred is coated with a predetermined amount of lubricant by a brush roller, then cleaned by a blade, discharged by the light emitted from the discharging lamp, and subjected to the next static charge. Prepared for formation of an electrostatic latent image.
[0037]
  The developing unit 120Y contains a two-component developer including a magnetic carrier and a negatively charged toner. A developing roller, a conveying screw, a doctor blade, a toner concentration sensor, a powder pump, and the like are provided so as to be partially exposed from the opening on the photosensitive drum side of the developing case 120Y. The developer accommodated in the developing case is triboelectrically charged by being stirred and conveyed by the conveying screw. A part of the developer is carried on the surface of the developing roller. The doctor blade uniformly regulates the layer thickness of the developer on the surface of the developing roller, and the toner in the developer on the surface of the developing roller moves to the photosensitive drum, whereby the toner image corresponding to the electrostatic latent image becomes a photosensitive member. Appears on drum 111Y. The toner density of the developer in the developing case is detected by a toner density sensor. When the density is insufficient, the powder pump is driven to replenish the toner.
[0038]
  The transfer belt 160 of the transfer belt unit 106 is provided with four grounded stretching rollers so as to pass through the transfer positions in contact with and opposed to the photosensitive drums 111M, 111C, 111Y, and 111K of the toner image forming units. It is laid around. One of the stretching rollers is 109. Among these stretching rollers, an electrostatic attracting roller to which a predetermined voltage is applied from a power source is arranged so as to face an entrance roller on the upstream side in the transfer sheet moving direction indicated by a two-dot chain line arrow. The transfer paper that has passed between these two rollers is electrostatically attracted onto the transfer conveyance belt 160. An exit roller on the downstream side in the transfer sheet moving direction is a drive roller that frictionally drives the transfer conveyance belt, and is connected to a drive source (not shown). In addition, a bias roller to which a predetermined cleaning voltage is applied from a power source is disposed on the outer peripheral surface of the transfer conveyance belt 160. The bias roller removes foreign matters such as toner adhered on the transfer conveyance belt 160.
[0039]
  Further, a transfer bias applying member is provided so as to come into contact with the back surface of the transfer conveyance belt 160 forming a contact facing portion that contacts and faces the photosensitive drums 111M, 111C, 111Y, and 111K. These transfer bias applying members are Mylar fixed brushes, and a transfer bias is applied from each transfer bias power source. The transfer bias applied by the transfer bias applying member applies transfer charge to the transfer conveyance belt 160, and a transfer electric field having a predetermined strength is formed between the transfer conveyance belt 160 and the surface of the photosensitive drum at each transfer position. .
[0040]
  The paper that is conveyed by the transfer conveyance belt 160 and onto which the toner images of the respective colors formed on the photosensitive drums 111M, 111C, 111Y, and 111K are transferred is sent to the fixing device 107, where the toner image is heated and pressed. Heat-fixed. After the heat fixing, the sheet is fed to the finisher 34 from the paper discharge port 34 ot to the finisher 34 on the upper side of the left side plate. Alternatively, the paper is discharged to a paper discharge tray 108 on the upper surface of the printer body.
[0041]
  Among the four photosensitive drums, the photosensitive drums 111M, 111C, and 111Y for forming a magenta image, a cyan image, and a yellow image are each an electric motor (color drum motor; color drum) for driving a color drum (not shown). M: Driven by a one-stage reduction through a power transmission system and a speed reducer (not shown). The photosensitive drum 111K for black image formation is driven at a one-stage speed reduction by a single electric motor (K drum motor: not shown) for driving the black drum via a power transmission system and a speed reducer (not shown). The Further, the transfer conveyance belt 160 is rotated by driving of a transfer driving roller via a power transmission system by the K drum motor. Accordingly, the K drum motor drives the K photoconductor drum 11K and the transfer conveyance belt 60, and the color drum motor drives the M, C, Y photoconductor drums 11M, 11C, and 11Y.
[0042]
  The K developing device 120K is driven by an electric motor (not shown) that drives the fixing unit 107 via a power transmission system and a clutch (not shown). The M, C, and Y developing devices 120M, 120C, and 120Y are electric motors (not shown) that drive the registration rollers 105, and are driven via a power transmission system and a clutch (not shown). The developing devices 120M, 120C, 120Y, and 120K are not constantly driven, but receive drive transmission from the clutch so that they can be driven with a predetermined timing.
[0043]
  Refer to FIG. 1 again. The finisher 34 has a stacker tray, that is, a stacking / lowering tray 34hs and a sort tray group 34st. It has a sorter paper discharge mode.
[0044]
  The sheet fed from the printer 100 to the finisher 34 is transported in the upper left direction, passes through the upside down U-shaped transport path, switches the transport direction downward, and then ejects the stacker according to the set mode. In the mode, the sheet is discharged from the discharge port to the loading / lowering tray 34hs. In the sorter paper discharge mode, the paper being discharged at that time of the sorter tray group 34st is discharged to the assigned sorter tray.
[0045]
  When the sorter paper discharge mode is designated, the finisher internal paper discharge controller drives the sort tray group 34st placed at the lowermost overlapping retract position to the use position indicated by a two-dot chain line in FIG. Increase the spacing. In the sorter paper discharge mode, for a set number of copies or prints (one person), when the sorter paper discharge mode is set for copy sorting, each transfer paper on which the same document (image) is printed is sorted into the sort tray group 34st. Assorted and stored in each tray. When the sorter discharge mode is set for page sorting, each tray is assigned to each page (image), and each transfer sheet on which the same page is printed is stacked on one sort tray.
[0046]
  FIG. 3 shows a document image reading mechanism of the scanner 10 and the ADF 30 attached thereto. The original placed on the contact glass 231 of the scanner 10 is illuminated by the illumination lamp 232, and the reflected light (image light) of the original is reflected by the first mirror 233 in parallel with the sub-scanning direction y. The illumination lamp 232 and the first mirror 233 are mounted on a first carriage (not shown) that is driven at a constant speed in the sub-scanning direction y. Second and third mirrors 234 and 235 are mounted on a second carriage (not shown) driven in the same direction as the first carriage, and the image light reflected by the first mirror 233 is The light is reflected downward (z) by the second mirror 234, reflected in the sub-scanning direction y by the third mirror 235, converged by the lens 236, irradiated to the CCD 207, and converted into an electrical signal. The first and second carriages are driven forward (original scanning) and backward (return) in the y direction using the traveling body motor 238 as a drive source.
[0047]
  A white reference plate 239 and a base point sensor 249 for detecting the first carriage are provided between the reading glass 240 and the scale 251 for positioning the document start end. Although the white reference plate 239 has read a document having a uniform density due to variations in individual light emission intensities of the illumination lamp 232, variations in the main scanning direction, sensitivity variations for each pixel of the CCD 207, and the like. It is prepared to correct the phenomenon that the read data varies (shading correction). In this shading correction, first, the white reference plate 239 is read for one line in the main scanning direction before scanning the document, the read white reference data is stored in the memory, and when reading the document image, for each pixel scanned in the document, The image data is divided by the corresponding white reference data on the memory.
[0048]
  The scanner 10 is equipped with an automatic document feeder ADF 30. The documents stacked on the document tray 241 of the ADF 30 are fed between the conveyance drum 244 and the pressing roller 245 by the pickup roller 242 and the registration roller pair 243, and are in close contact with the conveyance drum 244 and pass over the reading glass 240. The paper is discharged onto a paper discharge tray 248 that also serves as a pressure plate below the document tray 241 by the paper discharge rollers 246, 247A, and 247B. When the original passes through the reading glass 240, the original is irradiated by the illumination lamp 232 moving immediately below the original, and the reflected light of the original is irradiated to the CCD 207 through the optical system below the first mirror 233 to be photoelectrically converted. The
[0049]
  When double-sided copying or double-sided reading is designated, reading of the front surface (upper surface in a state of being stacked on the document tray 241) is finished, and the paper is discharged onto the paper discharge tray 248 by the paper discharge rollers 246, 247A, and 247B. When the document tail passes through the reverse feed switching claw 252 and the paper discharge roller 247A does not pass, the conveyance of the original is stopped, and the switching claw 252 is switched to the dotted line position, and the paper discharge roller 247A, 247B is driven in reverse rotation. As a result, the surface of the tail end of the document comes into close contact with the transport drum 244 rotating counterclockwise, and this time the document passes over the reading glass 240 with the back side as the top surface, and the discharge rollers 246, 246 At 247A and 247B, the sheet is discharged onto a discharge tray 248 that also serves as a pressure plate below the document tray 241.
[0050]
  When a document that is brought into close contact with the transport drum 244 of the ADF 30 and is sent to the reading glass 240 passes through the reflection plate 255, the thickness of the document is detected by the displacement detection head 253.
[0051]
  4A shows an outline of the paper thickness detection mechanism, and FIG. 4B shows a head cross section when the horizontal cross section of the displacement detection head 253 shown in FIG. 4 is viewed in the B direction. The reflection plate 255 is in the form of a guide plate that receives the document sent to the reading glass 240 in close contact with the transport drum 244, and the back surface of the surface in contact with the document is a mirror surface. Two support shafts 256 that are parallel to each other are erected and fixed to the back surface of the reflection plate 255. There is a fixed sleeve 257 that slidably receives these spindles 256, and a compression coil spring 258 that is locked to the fixed sleeve 257 presses the reflection plate 255 so as to press it against the transport drum 244. Therefore, when there is no document at the position of the reflection plate 255, the reflection plate 255 is in close contact with the transport drum 244, but when the document arrives, the reflection plate 255 is pushed up by the document. That is, the document enters between the transport drum 244 and the reflection plate 255, and the reflection plate 255 moves away from the transport drum 244 by the thickness of the document.
[0052]
  The displacement detection head 253 is fixed to a fixed sleeve 257. That is, since it is fixed and faces the reflection plate 255, the reflection plate 255 is separated from the front end surface of the displacement detection head 253 when there is no document. However, when the document arrives, the reflection plate 255 is pushed up by the displacement detection head 253. Approach the tip. This displacement amount of the reflection plate 255 is the paper thickness of the document.
[0053]
  The displacement detection head 253 includes a laser light emitting diode 253e and a phototransistor 253r, which have their optical axes such that the laser emitted from the laser light emitting diode 253e is reflected by the reflection plate 255 and enters the phototransistor 253r. In the state where there is no document and the reflection plate 255 is in close contact with the transport drum 244, they are arranged so as to be orthogonal to the back surface of the reflection plate 255. Therefore, the amount of light received by the phototransistor 253r is maximum when there is no document and the reflection plate 255 is in close contact with the transport drum 244 (paper thickness = 0). When the document enters under the reflection plate 255, the reflection plate 255 approaches the displacement detection head 253, so that the amount of light received by the phototransistor 253r decreases. The greater the paper thickness of the document, the greater the reduction in the amount of light received by the phototransistor 253r.
[0054]
  A displacement detection circuit 254 connected to the laser light emitting diode 253e and the phototransistor 253r energizes the ADF 30 when reading a document, and generates a paper thickness signal Spt proportional to the amount of light received by the phototransistor 253r (inversely proportional to the paper thickness). To do. A controller (not shown) of the scanner 10 provides an enable signal of high level H to the displacement detection circuit 254 while the document passes through the reflection plate 255. The displacement detection circuit 254 resets (initializes; clears the hold value) the sample hold circuit in the circuit 254 in response to the rise of the enable signal (H) from L to H, and the enable signal (H) is present. The lower peak value of the paper thickness signal Spt in the meantime is held. The lower peak value indicates the minimum value of the paper thickness of the document that has passed through the reflection plate 255, that is, the thickness of the thinnest portion. When the document is a rough copy having a relatively thick toner and a relatively thick toner, the lower peak value is a background portion where there is no image toner, and is the value closest to the paper thickness. A controller (not shown) of the scanner 10 digitally converts and reads the lower peak value signal Spt held by the displacement detection circuit 254 when processing of the image reading signal of one original is finished, and reads digital data, that is, paper thickness data. Spt is sent to the original image data read this time. This paper thickness data is added to the document image data and written in a memory MEM described later.
[0055]
  For detecting the paper thickness, in addition to the above-described detection of light reflection, a method of detecting the displacement amount of the plate 255 by detecting the capacitance between the plate 255 and the transport drum 244 or a differential transformer is used. For example, a method of detecting a small amount of displacement of the plate 255 may be used.
[0056]
  FIG. 6 shows the system configuration of the image processing system of the copying machine shown in FIG. In this system, a color document scanner 10 including a reading unit 11 and an image data output I / F (Interface) 12 is connected to an image data interface control CDIC (hereinafter simply referred to as CDIC) of an image data processing apparatus ACP. Yes. A color printer 100 is also connected to the image data processing apparatus ACP. The color printer 100 receives the recorded image data from the image data processor IPP (Image Processing Processor; hereinafter simply referred to as IPP) of the image data processing apparatus ACP to the writing I / F 134 and prints it out by the image forming unit 135. . The image forming unit 135 is shown in FIG.
[0057]
  The image data processing device ACP (hereinafter simply referred to as ACP) includes a parallel bus Pb, an image memory access control IMAC (hereinafter simply described as IMAC), an image memory MEM (memory module & hard disk; hereinafter simply described as MEM), A system controller 1, RAM 4, nonvolatile memory 5, font ROM 6, CDIC, IPP, and the like are provided. A facsimile control unit FCU (hereinafter simply referred to as FCU) is connected to the parallel bus Pb. The operation board 20 is connected to the system controller 1.
[0058]
  A reading unit 11 for optically reading a document of the color document scanner 10 generates R, G, B image data by photoelectrically converting the reflected light of the lamp irradiation on the document by the CCD on the sensor board unit SBU. The data is converted into data, shading corrected, and sent to the CDIC via the output I / F 12.
[0059]
  The CDIC performs communication between the output I / F 12, the parallel bus Pb, and the IPP, and communication between the process controller 131 and the system controller 1 that controls the entire ACP with respect to image data. The RAM 132 is used as a work area for the process controller 131, and the nonvolatile memory 133 stores an operation program for the process controller 131.
[0060]
  In addition to the semiconductor memory, the MEM also has a hard disk for storing a lot of image data. By using a hard disk, there is also a feature that an external power source is unnecessary and an image can be retained permanently. Many original images can be read by a scanner and held on a hard disk, and many document images provided by a PC can be held.
[0061]
  Image memory access control IMAC (hereinafter simply referred to as IMAC) controls writing / reading of image data to / from MEM. The system controller 1 controls the operation of each component connected to the parallel bus Pb. The RAM 4 is used as a work area for the system controller 1, and the nonvolatile memory 5 stores an operation program for the system controller 1.
[0062]
  The operation board 20 inputs processing to be performed by the ACP. For example, the type of processing (copying, facsimile transmission, image reading, printing, etc.), the number of processings, etc. are input. Thereby, the image data control information can be input.
[0063]
  The image data read from the reading unit 11 of the scanner 10 is subjected to shading correction by the SBU (sensor board unit) of the scanner 10 and then subjected to image processing for correcting reading distortion such as scanner gamma correction and filter processing by IPP. Apply to MEM. When printing out MEM image data, IPP performs color conversion of RGB signals to YMCK signals, and performs image quality processing such as printer gamma conversion, gradation conversion, and gradation processing such as dither processing or error diffusion processing. The image data after the image quality processing is transferred from the IPP to the writing I / F 134. The writing I / F 134 performs laser control on the gradation processed signal by pulse width and power modulation. Thereafter, the image data is sent to the image forming unit 135, and the image forming unit 135 forms a reproduced image on the transfer paper.
[0064]
  Based on the control of the system controller 1, the IMAC is used to control access to image data and MEM, to develop print data for a personal computer PC (not shown) connected to the LAN (hereinafter simply referred to as PC), and to effectively use MEM. Compress / decompress the image data.
[0065]
  The image data sent to the IMAC is stored in the MEM after data compression, and the stored image data is read out as necessary. The read image data is decompressed, returned to the original image data, and returned from the IMAC to the CDIC via the parallel bus Pb. After the transfer from the CDIC to the IPP, image quality processing is performed and the image is output to the writing I / F 134, and a reproduced image is formed on the transfer paper in the image forming unit 135.
[0066]
  In the flow of image data, the functions of the digital multi-function peripheral are realized by the bus control by the parallel bus Pb and the CDIC. Facsimile transmission is performed by performing image processing on the image data read by the scanner 10 using the IPP and transferring it to the FCU via the CDIC and the parallel bus Pb. The FCU performs data conversion to the communication network and transmits it as facsimile data to the public line PN. Facsimile reception is performed by converting line data from the public line PN into image data by the FCU and transferring it to the IPP via the parallel bus Pb and CDIC. In this case, no special image quality processing is performed, and the image is output from the writing I / F 134 and a reproduced image is formed on the transfer paper in the image forming unit 135.
[0067]
  In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function, and a printer output function operate in parallel, the usage rights of the reading unit 11, the image forming unit 135, and the parallel bus Pb are allocated to the system controller 1 and the process. Control is performed by the controller 131. The process controller 131 controls the flow of image data, and the system controller 1 controls the entire system and manages the activation of each resource. The function selection of the digital multi-function peripheral is performed on the operation board 20, and processing contents such as a copy function and a facsimile function are set by a selection input of the operation board 20.
[0068]
  The system controller 1 and the process controller 131 communicate with each other via the parallel bus Pb, CDIC, and serial bus Sb. Specifically, communication between the system controller 1 and the process controller 131 is performed by performing data format conversion for data and interface between the parallel bus Pb and the serial bus Sb in the CDIC.
[0069]
  Various bus interfaces, such as a parallel bus I / F 7, a serial bus I / F 9, a local bus I / F 3, and a network I / F 8, are connected to the IMAC. The controller unit 1 is connected to related units via a plurality of types of buses in order to maintain independence in the entire ACP.
[0070]
  The system controller 1 controls other functional units via the parallel bus Pb. The parallel bus Pb is used for transferring image data. The system controller 1 issues an operation control command for storing image data in the MEM to the IMAC. This operation control command is sent via IMAC, parallel bus I / F 7, and parallel bus Pb.
[0071]
  In response to this operation control command, the image data is sent from the CDIC to the IMAC via the parallel bus Pb and the parallel bus I / F 7. Then, the image data is stored in the MEM under the control of the IMAC.
[0072]
  On the other hand, the ACP system controller 1 functions as a printer controller, network control, and serial bus control in the case of a call from the PC as a printer function. In the case of via the network, the IMAC receives print output request data via the network I / F 8.
[0073]
  In the case of a general-purpose serial bus connection, the IMAC receives print output request data via the serial bus I / F 9. The general-purpose serial bus I / F 9 corresponds to a plurality of types of standards, for example, a standard interface such as USB (Universal Serial Bus), 1284 or 1394.
[0074]
  Print output request data from the PC is developed into image data by the system controller 1. The development destination is an area in MEM. Font data necessary for expansion is obtained by referring to the font ROM 6 via the local bus I / F 3 and the local bus Rb. The local bus Rb connects the controller 1 to the nonvolatile memory 5 and the RAM 4.
[0075]
  Regarding the serial bus Sb, in addition to the external serial port 2 for connection with the PC, there is also an interface for transfer with the operation board 20 which is an operation unit of the ACP. This is not print development data, but communicates with the system controller 1 via the IMAC, accepts processing procedures, displays the system status, and the like.
[0076]
  Data transmission / reception between the system controller 1 and the MEM and various buses is performed via the IMAC. Jobs that use MEM are centrally managed in the entire ACP.
[0077]
  As shown in FIG. 7, the operation board 20 has a liquid crystal touch panel (hereinafter also referred to as a liquid crystal display or a display) 79 having a surface display function and an input reading function, a numeric keypad 80a, a clear / stop key 60b, Start key 60c, mode clear key 60e, test print key 80f, “copy” function, “scanner” function, “print” function, “facsimile” function, “store” function, “edit” function, “register” function There is a function selection key 80g for selecting and executing other functions.
[0078]
  The main body of the electric control system of the operation board 20 communicates with the system controller 1, reads the input of the operation board 20, controls the display on the board, the ROM storing the control program of the CPU, and the data at the time of control RAM for temporary storage, VRAM for storing drawing data of the liquid crystal display 79, a liquid crystal display controller (LCDC) connected to the VRAM for controlling drawing timing of the liquid crystal display 79, and a clock IC for generating time data Etc. Connected to the CPU of the operation board 20 are a key matrix of operation key groups, an LED matrix of display LEDs, an LED drive device for driving these LEDs, and the like. Further, a nonvolatile RAM (NVRAM) is connected to the data bus to which the CPU of the operation board 20 is connected.
[0079]
  The liquid crystal display 79 displays an input / output screen determined for the function designated by the function selection key 80g. For example, when the “copy” function is designated, the function keys 79a and 79b and the “screen-through removal” input window are displayed. 311 and the like, and a message indicating the number of copies and the state of the image forming apparatus are displayed. The test print key 80f is a key for printing only one copy regardless of the set number of print copies and confirming the print result.
[0080]
  The “character” designation key 80h is selected and operated when the image is recognized as a binary image such as a text or a line drawing. The “halftone dot” designation key 80i is a halftone or gray expression such as a halftone dot or a photograph or a picture. Is selected when it is recognized that When “character” is specified, data (1 bit signal) indicating these specifications is at a high level “1”, and when “halftone” is specified, the data is at a low level “0”. When “character” is designated, the IPP performs a process of clearly expressing characters and lines on the image data, and when “halftone” is designated, the IPP performs a process of smoothly representing a gradation image such as a photograph.
[0081]
  When the initial setting key 80d is operated, an "initial value setting" function for setting various initial values, an "ID setting" function, a "copyright registration / setting" function, and an "usage record output" function A selection menu is displayed.
[0082]
  8, when the copy instruction input standby screen (FIG. 7) is displayed on the liquid crystal display 79, the user inserts a finger or an input pen into the show-through removal button of the “show-through removal” input window 311 on the screen. 7 shows an input screen for “show-through removal setting” displayed on the liquid crystal display 79 when the operation board 20 is touched.
[0083]
  On the upper side of the liquid crystal display 79, there is a task bar image having keys 312 to 316 for instructing the progress of the show-through removal input and the original page display 317. A “Previous” key 312 is a display return instruction key. When the user touches the key, the operation board 20 returns the display on the liquid crystal display 79 to the screen immediately before the current display is switched. An “OK” key 313 is a key (corrected image print start key) for instructing to print out a corrected image (or original image) from which a show-through is removed, of a document displayed on the liquid crystal display 79 (317). . The “cancel show-through removal” key 314 is used to cancel the show-through removal designation, that is, the copy instruction input standby screen in which the display of the “show-through removal” input window 311 is returned to the default (standard setting) show-through removal non-designated state. (FIG. 7) is instructed to return the display of the liquid crystal display 79. When the “show-through removal cancellation” key 314 is touched, the operation board 20 displays a copy instruction input standby screen in which the show-through removal button is switched from the designated display state (dotted shading) to the non-designated display (no shading). (FIG. 7) is displayed on the liquid crystal display 79. A “next page” key 315 is used to display a document page with a show-through removal setting when the scanner 10 continuously reads a plurality of pages of documents on the ADF 30, and is next to the page displayed on the current page display 317. A key for instructing switching to the page, “Previous Page” key 316 is a key for switching to the previous page.
[0084]
  On the right side of the liquid crystal display 79, there is a display condition input screen, in which a “confirm image” input window 330, display image selection, and threshold setting are designated in accordance with the original paper thickness. There are display windows 319, 419 and 324 for performing threshold selection and adjustment of the show-through threshold, selection / update keys or buttons 318, 418, 329, up / down keys 322 and 323, and a confirmation instruction key 327.
[0085]
  The “confirm image” button in the “confirm image” input window 330 switches to a designated display state (dotted shading) when the user touches it, and this changes the original image into a corrected image with the show-through removed. After the conversion, the setting conditions described below are displayed, and after waiting for the user's print instruction (OK key 313 on = user touch), the display mode for printing the corrected image is designated. Is. When the user touches the confirmation button, the display is switched to a non-designated display state (no shading). This is done without changing the original image to a corrected image, and without displaying as described below. The non-display mode for printing the corrected image immediately without waiting for the second instruction (ON of the OK key 313) is designated. The default of the “confirm image” button in the “confirm image” input window 330 is a display mode designation of shaded display.
[0086]
  The mode for displaying an image in the image display area 328 (display image selection 319) includes “original image” and “show-through image” in addition to the default (standard image) “post-removal image”. When the user touches the selection update key 318 once, “original image” is displayed in the display window 319. When the touch is further repeated, the display on the display window 319 is switched to the “show-through image”, and after the “show-through image”, the display returns to the default “image after removal”. A key 318 is a scroll key.
[0087]
  The choices of threshold selection are “automatic” and “manual”, and touching the scroll key 418 switches the display of the input window 419. “Automatic” or “manual” displayed in the input window 419 is currently selected. When “automatic” is selected, the show-through cutout threshold Ths used in “Single-sided image processing show-through removal” P45Ap described later is set to a value corresponding to the paper thickness data Spt when the paper thickness data Spt is present. (7 to 10 in FIG. 13). When “manual” is selected, the threshold value displayed on the display window 324 described below is set.
[0088]
  In the initial display, the display window 324 displays a default value of the show-through cut-out threshold Ths, but the user touches the selection button 329 to set a default value for strong removal, a value for weak removal, and a standard value. Can be easily switched to a value (default value). Further, by touching the up / down keys 322 and 323, the threshold value can be increased or decreased by a minimum unit. This is the “manual” setting of the threshold.
[0089]
  When the user touches the “OK” key 327, the operation board 20 sets the information displayed in the windows 319, 419, and 324 at that time as the document show-through removal condition, and the system controller 1 makes the scanner 10 Start image reading by. The read image (O) is written in the MEM, and when the reading is finished, the show-through removal of all the read original pages is removed, and a corrected image (P) from which the show-through is removed and the removed show-through image (Rr) are obtained. Write to MEM. When proceeding to this image reading and removal process, that is, when the user touches the “OK” key 327, the “confirm image” button of the “confirm image” input window 330 is in the designated state display. That is, when the display mode is designated, the show-through processing result of the first page is displayed in the image display area 328 of the liquid crystal display 79. At this time, the display on the liquid crystal display 79 is switched to the processing result display screen shown in FIG. When the user touches the “OK” key 327 and the “confirm image” button of the “confirm image” input window 330 is a non-designated display (designation of the non-display mode), the system controller 1 does not proceed to the image display (FIG. 9) on the liquid crystal display 79, but proceeds to the printout of the corrected image written in the MEM.
[0090]
  In the processing result display screen displayed on the liquid crystal display 79 in the display mode shown in FIG. 9, the title is changed to “the show-through removal result”, and the “confirm image” input window 330 shown in FIG. The input window 331 is switched to “Return to”. In the display image shown in FIG. 9, Fim is a front image (corrected image), and Rim is a back image (image from which show-through is removed).
[0091]
  In the image display area 328, vertical and horizontal scroll bars are displayed. By touching and sliding these, the image portion displayed in the area 328 can be scrolled. Thereby, an image having a size larger than the display size of the liquid crystal display 79 can be displayed in the region 328.
[0092]
  The default of the “return to original image” input window 331 is a non-designated state in which the “return to original image” button is not shaded, that is, “specify corrected image”. When the user touches the OK key 313 in this state, Is an instruction to print out the corrected image on the display page. When the user hits the “return to original image” button in the “return to original image” input window 331, it enters a state of specifying “return to the original image” in the shaded display, and the operation board 20 displays the image display area 328. The original image is switched and displayed. When the user touches the OK key 313 in a state where the original image is displayed, this is an instruction to print out the original image on the display page.
[0093]
  FIG. 10 shows an outline of the image processing function of IPP. The read image data provided by the scanner 10 through the CDIC is transmitted from the input I / F (interface) 41 of the IPP to the scanner image processing 42 through the CDIC from the SBU. The scanner image processing 42 performs scanner gamma correction, MTF correction, and the like mainly for the purpose of correcting deterioration of image information due to reading. Although not correction processing, enlargement / reduction scaling processing is also performed. After the read image data correction processing is completed, the image data is transferred to the CDIC via the output I / F 43. For output (image formation) to transfer paper, image data from the CDIC is received from the input I / F 44, and area gradation processing is performed in the image quality processing 46. The data after the image quality processing is output to the writing I / F 134 via the output I / F 47. Area gradation processing includes density conversion, dither processing, error diffusion processing, and the like, and mainly performs area approximation of gradation information.
[0094]
  Once the image data subjected to the scanner image processing 42 is stored in the memory MEM, various reproduced images can be confirmed by changing the processing performed in the image quality processing 46. For example, the atmosphere of the reproduced image can be changed by changing the density of the reproduced image or changing the number of lines in the dither matrix. At this time, it is not necessary to read the image again with the scanner 10 every time the process is changed, and if the stored image is read from the MEM, different processes can be performed on the same data any number of times.
[0095]
  11 and 12 show an outline of image processing control in the copy mode by the cooperation of the operation board 20 and the system controller 1. FIG. In the copy mode, which is the default (standard) mode of the copying machine of FIG. 1, the operation board 20 displays the copy mode input screen (FIG. 7) (step 101).
[0096]
  In the following, the word “step” is omitted in parentheses, and step No. Enter only numbers.
[0097]
  If there is an input for changing the copying conditions such as the number of copies, density, magnification, etc., the operation board 20 reads it (102). Further, when the “show-through removal” button in the “show-through removal” window 311 is touched, the operation board 20 switches and displays the show-through removal setting screen (FIG. 8) (103-106).
[0098]
  When the start key 80c is turned on when there is no input of these switching instructions, the system controller 1 sets each part to “copy” and causes the process controller 131 to perform copy control (102 to 105). This copy is common and no show-through removal is performed here.
[0099]
  When the “show-through removal” button in the “show-through removal” window 311 is touched, the operation board 20 switches and displays the show-through removal setting screen (FIG. 8) (103-106). Then, the input to the operation board 20 is read (107). Here, if there is a user input (touch) on the display condition input screen on the right side of the liquid crystal display 79, the display condition input screen is changed in response thereto. When the “OK” key 327 on the display condition input screen is touched, the data in the show-through removal condition register (one area of the internal memory of the operation board) is updated to the information currently displayed on the display condition input screen. .
[0100]
  When the OK key 313 is touched or the copy start key (80c) is operated, the operation board 20 adds the information of the show-through removal condition register and gives a command for reading the scanner image to the system controller 1. .
[0101]
  At this time, if the “confirm image” button in the “confirm image” window 330 is in the display state in which the “confirm” instruction has been issued, the system controller 1 writes the scanned image data to the MEM in the CDIC and IMAC. And an image reading command is given to the scanner 10 via the process controller 131.
[0102]
  In response to this, the scanner 10 starts reading when there is a document in the ADF 30, converts the image of the document into image data, performs shading correction, and outputs it to the IPP via CDIC. The scanner 10 sequentially reads all the originals in the ADF 30 and notifies the system controller 1 via the process controller 131 when all the originals have been read (109-110). At this time, if the document is fed by the ADF 30, the controller (not shown) of the document scanner 10 enters the reflection plate 255 after the leading edge of the document enters the reflection plate 255 based on the timing of document conveyance. Immediately before, Enable (H) is given to the displacement detection circuit 254, and in response to this, the displacement detection circuit 254 holds the lower peak value of the paper thickness signal Spt in the peak hold circuit. When the reading of the image signal of the original is finished, the lower peak value held by the displacement detection circuit 254 is digitally converted, digital data, that is, paper thickness data Spt is added to the image data, and sent to the CDIC (110ad1). ~ 110ad3).
[0103]
  Further, when “both sides” (FIG. 7) is designated, the front side image and the back side image of each document are read. That is, duplex reading is performed. In this case, the front image is paginated on odd pages, and the back image is paginated on even pages.
[0104]
  When there is no original in the ADF 30, the scanner 10 scans the carriage to start reading the original image on the contact glass, and notifies the end when the reading is completed.
[0105]
  The CDIC sends the image data generated by the scanner 10 and the paper thickness data Spt to the IPP, sets the data transfer to send the image data processed by the IPP to the parallel bus Pb, and the image data sent to the parallel bus Pb by the IMAC. Is transferred to MEM. The IPP processes the image data generated by the scanner 10 by the scanner image processing 42 and outputs it to the CDIC. The CDIC performs the primary compression to increase the data transfer efficiency and adds the paper thickness data Spt to the parallel. The primary compressed data sent to the bus Pb and the IMAC sent to the parallel bus Pb are subjected to secondary compression for increasing the memory storage efficiency and written to the MEM.
[0106]
  When the scanner 10 finishes reading the image and the read image data is written in the MEM, the system controller 1 performs a show-through removal process on the image data written in the MEM to the IMAC, CDIC, and IPP, and the resulting image. Data processing for writing data (O, Q, R) to MEM is set. Correspondingly, the IMAC reads out the written image data (first page if there are multiple pages) from the MEM, gives it to the IPP, and processes it with the IPP “removal of show-through” 45A to remove the show-through. After removal (corrected image P) data and show-through image (Rr) data representing the removed image are generated, and these two types of image data (two sets of images P and Rr) are output to the CDIC. Is first compressed, and IMAC is secondarily compressed and written to MEM. When a document image of a plurality of pages is being written on the MEM, the above-described two sets of image data (P, Rr) are generated and written to the MEM for each page of the document. Thereby, the image data of the original image (O) read by the scanner, the corrected image (P) from which the show-through is removed, and the show-through image (Rr) are recorded in the MEM for each page of the document.
[0107]
  FIG. 13 shows an overview of the processing function “show-through removal” 45Ap of IPP “show-through removal processing” 45A. In the “removal of show-through” 45 Ap, if “both sides” is specified, if the image to be “removed by show-through” is an odd page (front image), the process proceeds to “removal of show-through in single-sided image processing” P 45 Ap. (1-2-P45Ap). This content will be described later.
[0108]
  If “double-sided” is specified and the image to be “removed by show-through” is an even page (back-view image), the “reverse-through removal” of the front image on the back is completed, and the original image O, There are the corrected image P and the show-through image Rr from which the show-through has been removed, and the reduced image Or of the original image O generated at the time of the “show-through removal” process is in the work area of the MEM, and the show-through image Rr is Since it is also a reduced image, the peak value B of the original image Or of the front image and the peak value A of the show-through image Rr and the peak value C of the reduced image Or of the current back image (original image O) are used, If the peak value C is equal to or greater than the threshold value d (a set value greater than 0), first, the original transmittance A / C is calculated, and the value A · B / C obtained by multiplying C is calculated (3a, 3b). The higher the document transmittance and the higher the back (front) image density, the greater the value of A / B / C, and the back (front) image appears as a “back image” in the back side image to be processed this time. There is a high possibility. Therefore, if A · B / C is equal to or higher than the threshold value D, which is a set value, it is determined that the reliability of A · B / C is high, the original image Or of the front image is reversed left and right, and the transmittance A show-through image Rr on the back image is calculated (estimated) from A / C (3a, 3b, 4), and is subtracted from the original image Or of the back image to generate a show-through removed image, that is, a corrected image Pr. (5). Then, the corrected image P enlarged to the original size is written in the MEM (6).
[0109]
  If the peak value C is less than the threshold value d, the reliability of the transmittance A / C is low, and therefore, the process proceeds to “removal of show-through in single-sided image processing” P45Ap through steps 7 to 10 (3a-P45Ap). When A · B / C is less than the threshold value D, the possibility of show-through may be low, but it is assumed that the reliability of A · B / C is also low, and the “single-sided image processing” The process proceeds to P45Ap (3b-P45Ap).
[0110]
  In steps 7 to 10, a threshold Ths for cutting out the show-through image is set according to the setting of the “threshold selection” input window 419.
[0111]
  That is, if the setting of the “threshold selection” input window 419 is “automatic” and the paper thickness data Spt exists, the paper thickness data Spt is converted into a threshold value, and the threshold value Ths (used in step 14 described later). (7-9-10). In the nonvolatile memory NVRAM of the operation board 20, conversion coefficients (for “strong”: 2Tpmax / 5, for “medium”: defining each conversion characteristic function shown in FIGS. 5A, 5B and 5C: Tpmax / 5, “Weak”: Tpmax / 10), and the IPP is designated via the system controller 1 in the strong, medium and weak buttons 329 under the “Blurred-through threshold” input window (network A product obtained by reading the conversion coefficient (Tpmax / 5) addressed to the product (for example, medium) multiplied and displayed by multiplying it by the paper thickness data Spt is set as the threshold Ths (9, 10).
[0112]
  Even when the “threshold selection” input window 419 is set to “automatic”, the paper thickness data Spt does not exist (document reading on the contact glass 231), and the setting of the “threshold selection” input window 419 is “manual”. Is set to the threshold Ths, the value displayed in the “show-through threshold” input window 324 is set (7-P45Ap).
[0113]
  FIG. 14 shows an outline of “single side image processing show-through removal” P45Ap. “Removal of show-through in single-sided image processing” P45Ap in this embodiment is disclosed in the aforementioned Japanese Patent Application Laid-Open No. 2001-169080. First, the resolution is reduced by thinning out the image data of the original image O written in the MEM (11). An image appearing thereby is expressed as a reduced original image Or. The color coordinate system of the reduced original image Or is converted into one in which each axis component data is highly independent (12).
[0114]
  Next, the image edge strength is calculated (13). Edges with weak edge strength are detected by binarization processing of edge strength using the threshold Ths (14), a background color image around the edge with weak edge strength is estimated (15), and edges with weak edge strength are expanded. The width is slightly expanded and replaced with a background color image (16a). An edge having a weak edge strength newly generated by replacement with the background color image is detected, and this is similarly replaced with the background color image (16b-15-16a). The image obtained in this way is a pseudo corrected image nPr from which show-through has been removed.
[0115]
  Next, an edge difference image is generated by calculating a difference in edge strength between the original image Or subjected to color coordinate conversion and the pseudo correction image nPr (17, 18). This detects a portion where the image has deteriorated due to inappropriate processing. If there is, the background color image around it is estimated (20), and the corresponding part is replaced with the background color image (21). Further, an edge difference image is generated by calculating a difference in edge strength between the original image Or and the pseudo correction image nPr (17, 18). If there is an edge difference image, steps 20, 21, 17, 18, and 19 are repeated. When no edge difference image is generated, the color coordinate system of the pseudo-corrected image nPr at that time is inversely converted to an original RGB image (22). As a result, an image after the show-through image is removed, that is, a corrected image Pr is obtained.
[0116]
  Next, a show-through image Rr is generated by calculating the difference between the corrected image Pr from which the show-through is removed and the reduced original image Or (23), and is enlarged to the size of the original original image O. A corrected image P in which the reflected image portion is replaced with the background color image at the corresponding position of the corrected image Pr is generated and written into the MEM together with the show-through image Rr (24).
[0117]
  FIG. 11 will be referred to again. When the “confirm image” button of the “confirm image” window 330 is in a display state where there is no confirmation instruction, the above-described two sets of image data (P, Rr) are obtained by the “removal of show-through” 45 Ap. When the generation and the writing to the MEM are completed, the MEM has the data of three sets of images including the original image O and two sets of images (P, Rr) for each image of one page. Here, the system controller 1 reads out the corrected image data P from the MEM, sets the print processing mode in which the image quality processing 46 is performed in the IPP and prints out to the printer 100, and this is set in the IMAC, CDIC, process controller 131 (printer 100) is executed (112).
[0118]
  Please refer to FIG. When the show-through removal setting screen (FIG. 8) is displayed, when the OK key 313 is touched or the copy start key (80c) is operated, the “confirm image” window 330 displays “confirm image”. When the “” button is in a display state in which a confirmation instruction has been given, the system controller 1 executes the above-described “image reading” and “removal of show-through”. When the generation of the set of image data (P, Rr) and the writing to the MEM is completed, the system controller 1 displays a screen of the show-through removal result shown in FIG. With respect to the above, the “show-through removal display” (114) is executed in accordance with the above-described show-through removal condition held in the show-through removal condition register by the operation board 20.
[0119]
  When the display image selection in the show-through removal condition is the display of “image after removal”, the system controller 1 reads the image after the show-through removal, that is, the corrected image P from the MEM via the IMAC and the CDIC. Thus, the image display size is reduced to the liquid crystal display 79, transferred to the operation board 20 through the CDIC and IMAC, and displayed.
[0120]
  When the display image selection in the show-through removal condition is “original image” display, the system controller 1 reads the original image O from the MEM via the IMAC and CDIC, and displays the image on the liquid crystal display 79 by IPP. The size is reduced, transferred to the operation board 20 via the CDIC and IMAC, and displayed.
[0121]
  When the display image selection in the show-through removal condition is the display of “show-through image”, the system controller 1 reads out the show-through image Rr from the MEM via the IMAC and CDIC, and displays it on the liquid crystal display 79 by IPP. The image display size is reduced and transferred to the operation board 20 through the CDIC and IMAC for display.
[0122]
  When the original image O, the corrected image P, or the show-through image Rr is displayed by the “show-through removal display” (114), the user can determine whether the corrected image is appropriate (appropriate for show-through removal).
[0123]
  Here, when the user changes the show-through removal condition and touches the “OK” key 327, the operation board 20 reads this by “input reading” (115), and the show-through being displayed on the liquid crystal display 79 at that time. The removal condition is updated and written in the register, and the show-through removal process re-execution command and the show-through removal condition are transmitted to the system controller 1. The system controller 1 reapplys the show-through removal processing by IPP to the original image data, newly obtains the corrected image P and the show-through image Rr, updates and writes them to the MEM, and then displays them on the liquid crystal display 79 again. “Show-through removal display” (114) is executed under the show-through removal condition (115-116-45Ap-114).
[0124]
  When the user touches the “OK” key 313 or operates the copy start key 80c while the corrected image P is being displayed on the liquid crystal display 79 in the “display-through removal display” (114), the operation board 20 is displayed. When this is read and notified to the system controller 1, the system controller 1 reads the corrected image P from the MEM via the IMAC and CDIC, and for recording suitable for printing on the printer 100 by the “image quality processing” 46 of the IPP. And is printed out by the printer 100 (117-118). This printout is performed for the number of copies set in the copy input mode.
[0125]
  When the corrected image P is displayed on the liquid crystal display 79 in the “display-through removal display” (114), when the next page key 315 is touched and the original image data of the next page is in the MEM, the system controller No. 1 switches the page display 317 of the liquid crystal display 79 of the operation board 20 to that of the next page, and applies the show-through removal processing by IPP to the original image data of the next page, thereby correcting the corrected image P and the show-through image Rr. Then, after updating and writing to the MEM, “show-through removal display” (114) is executed under the show-through removal condition being displayed on the liquid crystal display 79 (119-45Ap-114).
[0126]
  When the corrected image P is displayed on the liquid crystal display 79 in the “display-through removal display” (114), if the “return to original image” button on the “return to original image” window 331 is touched, the operation board 20 reads this and notifies the system controller 1, and in response to this, the system controller 1 displays the original image O in the image display area 328, instructs the IMAC and the operation board 20 to switch the display, and The image O is switched and displayed (121, 122). When the user touches the “OK” key 313 or operates the copy start key 80 c while displaying the original image in this way, the operation board 20 reads this and notifies the system controller 1. In response to this, the system controller 1 reads the original image data from the MEM via the IMAC and CDIC, and converts it into image data for recording suitable for printing by the printer 100 by the “image quality processing” 46 of the IPP. Then, it is printed out by the printer 100 (123, 124). Then, the process returns to “input reading” (115).
[0127]
  When the operation board 20 recognizes that the touch of the “show-through removal cancellation” key 314 is recognized in the “input reading” (115), the operation board 20 notifies the system controller 1 of this, and the copy mode input screen (FIG. 7). ) To return the display of the operation board (120-101).
[0128]
  Note that an input screen (not shown) for modes other than the copy mode (scanner mode, print mode, facsimile mode, storage mode, edit mode, and registration mode) also has a show-through removal window 311, as described above. Show-through removal can be performed.
[0129]
【The invention's effect】
  Compared with the user's threshold setting work, such as checking the suitability of the index value (Ths) by outputting the corrected image information (P) once, it reduces the waste of time or the waste of supply and removes the show-through. It becomes possible to carry out efficiently.For documents with high transmissivity, for example, an index value for the detected thickness (Ths) The user can select the degree of the show-through image removal in correspondence with the paper quality, such as selecting a conversion characteristic (FIG. 5B) that increases the degree of the show-off image and increases the degree of the show-through image removal. It is possible to expect a favorable show-through removal by the user's judgment and operation.
[Brief description of the drawings]
FIG. 1 is a front view showing an appearance of a copier having a composite function according to a first embodiment of the present invention.
FIG. 2 is an enlarged longitudinal sectional view showing an outline of an image forming mechanism of the printer 100 shown in FIG.
3 is an enlarged longitudinal sectional view showing an outline of a reading mechanism of the document scanner 10 shown in FIG. 1. FIG.
4A is an enlarged perspective view of the reflection plate 255 and the displacement detection head 253 shown in FIG. 3, and FIG. 4B is a horizontal cross section of the displacement detection head 253 shown in FIG. FIG.
FIG. 5 is a graph showing characteristics of converting a paper thickness signal Spt into a threshold value, where (a) shows a case where the degree of show-through removal is designated as “medium”, and (b) and (c) show This indicates the case where “strong” and “weak” are designated.
6 is a block diagram showing an outline of an image processing system of the copying machine shown in FIG. 1;
7 is an enlarged plan view of a part of the operation board 20 shown in FIGS. 1 and 6. FIG.
8 is an enlarged plan view of the liquid crystal display 79 shown in FIG. 7, showing a state in which an input screen for show-through removal setting is displayed.
9 is an enlarged plan view of the liquid crystal display 79 shown in FIG. 7, showing a state in which an output screen of a show-through removal result is displayed.
10 is a block diagram showing an outline of some processing functions of the IPP shown in FIG. 6. FIG.
11 is a flowchart showing a part of an outline of image processing control in a copy mode by cooperation of the operation board 20 and the system controller 1 shown in FIG. 6;
12 is a flowchart showing the remainder of the outline of image processing control in the copy mode by the cooperation of the operation board 20 and the system controller 1 shown in FIG.
13 is a flowchart showing an overview of processing functions of “show-through removal” 45A shown in FIG. 10;
FIG. 14 is a flowchart showing the contents of “removal of show-through in single-sided image processing” P45Ap shown in FIG. 13;
[Explanation of symbols]
10: Color document scanner 20: Operation board
30: Automatic document feeder 34: Finisher
34hs: Loading and lowering tray 34ud: Lift platform
34st: Sort tray group 79: LCD touch panel
100: Color printer PC: Personal computer
PBX: Switch PN: Communication line
102: Optical writing unit 103, 104: Paper feed cassette
105: Registration roller pair 106: Transfer belt unit
107: fixing unit 108: discharge tray
110M, 110C, 110Y, 110K: photoconductor unit
111M, 111C, 111Y, 111K: photosensitive drum
120M, 120C, 120Y, 120K: Developer
160: Transfer conveyance belt ACP: Image data processing device
CDIC: Image data interface control
IMAC: Image memory access control
IPP: Image data processor
231: Platen glass 232: Illumination lamp
233: First mirror 234: Second mirror
235: Third mirror 236: Lens
207: CCD 238: traveling body motor
239: Reference white plate 240: Glass
241: Document tray 242: Pickup roller
243: Registration roller pair 244: Conveying drum
245: Pressing roller 246, 247A, B: Paper discharge roller
248: Pressure plate also serving as a discharge tray
249: Base point sensor 250: Axis
251: Scale 252: Reverse feed switching claw
253: Displacement detection head 255: Reflection plate
256: Spindle 257: Guide sleeve
258: Compression coil spring
260: Motor control unit

Claims (6)

Document reading means for reading an image of a document and generating image information; and image data representing an image obtained by erasing the low-density image from image data of a low-density image that satisfies the setting condition on the image represented by the image information In the image reading apparatus comprising: corrected image information corrected to low density image removing means for converting to
Thickness detection means for detecting the thickness of the original ; input means for a user to specify conversion characteristics for converting the thickness detected by the thickness detection means into an index value ; the thickness with the conversion characteristics specified by the input means the thickness detected by the detecting means, the index value setting means for converting the index value for determining whether the set condition is satisfied; and, means for extracting the image data of the low-density image using the index value An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the thickness detection unit includes a reflection member having a front surface in close contact with the document and a back surface having a reflection surface, and a displacement detection unit that detects a displacement amount of the reflection member due to the document. . The image reading apparatus according to claim 1, further comprising: an image output unit that displays an image represented by low density image information erased by low density image removal on a surface . Further, the low concentration input means for the user to instruct the conversion to by the correction image information image removing unit; wherein the low-density image removing means only when there is the instruction, performs the pre-Symbol conversion processing; claims Item 4. The image reading apparatus according to any one of Items 1 to 3.   The original reading means is a double-sided reading means capable of reading an image on the front side of the original and reading an image on the back side to generate image information on each side; , A low-density image on the front surface that is a difference between the image information and the corrected image information on the front surface and the image information on the back surface, and a low-density image on the back surface is generated. The image reading apparatus according to claim 1, having a function of generating a difference between density images as corrected image information on the back surface.   6. An image reading apparatus according to claim 1; image data processing means for converting the image information into image data for image formation; and a visible image on paper based on the image data for image formation. An image forming device.

Images