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WO2014129305A1 - Appareil de mesure et appareil formant image - Google Patents

Appareil de mesure et appareil formant image Download PDF

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Publication number
WO2014129305A1
WO2014129305A1 PCT/JP2014/052592 JP2014052592W WO2014129305A1 WO 2014129305 A1 WO2014129305 A1 WO 2014129305A1 JP 2014052592 W JP2014052592 W JP 2014052592W WO 2014129305 A1 WO2014129305 A1 WO 2014129305A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
receiving
receiving element
output
measurement
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/JP2014/052592
Other languages
English (en)
Inventor
Yasuo Kamei
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.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Priority to JP2015525686A priority Critical patent/JP5991775B2/ja
Publication of WO2014129305A1 publication Critical patent/WO2014129305A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/043—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for controlling illumination or exposure
    • 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
    • B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
    • B41J29/38—Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2803—Investigating the spectrum using photoelectric array detector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/46—Measurement of colour; Colour measuring devices, e.g. colorimeters
    • G01J3/50—Measurement of colour; Colour measuring devices, e.g. colorimeters using electric radiation detectors
    • G01J3/502—Measurement of colour; Colour measuring devices, e.g. colorimeters using electric radiation detectors using a dispersive element, e.g. grating, prism
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4076—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on references outside the picture
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/56—Processing of colour picture signals
    • H04N1/60—Colour correction or control
    • H04N1/603—Colour correction or control controlled by characteristics of the picture signal generator or the picture reproducer
    • H04N1/6033—Colour correction or control controlled by characteristics of the picture signal generator or the picture reproducer using test pattern analysis
    • H04N1/6044—Colour correction or control controlled by characteristics of the picture signal generator or the picture reproducer using test pattern analysis involving a sensor integrated in the machine or otherwise specifically adapted to read the test pattern
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/46—Measurement of colour; Colour measuring devices, e.g. colorimeters
    • G01J3/462—Computing operations in or between colour spaces; Colour management systems

Definitions

  • the present invention relates to a
  • measurement apparatus having a function of measuring a color, and an image forming apparatus.
  • the quality of an image (to be referred to as an image quality hereinafter) by a recently popular image forming apparatus (to be referred to as a printer hereinafter) is determined by various factors such as graininess, in-plane uniformity, character quality, and color reproducibility (including color stability) . A most important factor of them is color reproducibility.
  • the color difference matters not only between devices of the same model, but also between devices of different models, between image forming apparatuses of different methods, and between an image forming apparatus and an image display apparatus.
  • software and a measurement device for generating a multidimensional LUT (Look Up Table) called an ICC (International Color Consortium) profile are commercially available.
  • each ICC profile is calibrated in association with a device-independent color space based on color
  • CIE Commission internationale deficiency
  • a CMM Color Management Module installed in an image forming apparatus or the like can generate print data by performing color conversion using these profiles.
  • Japanese Patent Laid-Open No. 2004-86013 proposes an inline measurement device arrangement in which a patch image formed on a sheet is detected by a color sensor constructed by a light source, diffraction grating, and position detection sensor, thereby
  • a detection value from the color sensor is converted into a spectral reflectance, and the spectral reflectance can be converted into a CIE Lab value in consideration of the tristimulus values and the like.
  • the color detection accuracy of the color sensor in Japanese Patent Laid- Open No. 2004-86013 degrades owing to fluctuation factors such as output fluctuations of the light source upon a change of the environmental temperature.
  • ⁇ ( ⁇ ) be the quantity of light reflected by the white reference plate
  • ⁇ ( ⁇ ) be the quantity of light reflected by the patch
  • a spectral reflectance calculation method in calculation using the white reference plate is given by:
  • the white reference plate reflects light of a measurement wavelength region at almost the same reflectance regardless of the wavelength.
  • the quantity W ( ⁇ ) of light reflected by the white reference plate can be considered to be equal to the quantity of light incident on the patch image.
  • the output signal value from the position detection sensor which reads reflected light contains even a dark current value in addition to reflected light. There is a fear that fluctuations of the dark current value in accordance with the
  • a measurement apparatus characterized by comprising: a light emitting means for emitting a light; a light receiving means for receiving a reflected light from a measurement target, and outputting spectral reflectance information, the light receiving means comprises a plurality of light- receiving elements; a determination means for determining correction information based on a first signal which is output by a predetermined light- receiving element of the plurality of light-receiving elements in a first state in which the light emitting means does not emit a light and a second signal which is output by the predetermined light-receiving element of the plurality of light-receiving elements in a second state in which the light emitting means emits a light; and a correction means for correcting the spectral reflectance information output by the light receiving means based on the correction information determined by the determination means.
  • a measurement apparatus characterized by comprising: a light emitting means for emitting a light; a light receiving means for receiving a reflected light from a measurement target, and outputting spectral reflectance information, the light receiving means comprises a plurality of light- receiving elements; a detection means for detecting a temperature of the light emitting means; a
  • determination means for determining a target light- receiving element of the plurality of light-receiving elements based on the temperature detected by the detection means, and determining correction information based on a first signal which is output by the target light-receiving element of the plurality of light- receiving elements in a first state in which the light emitting means does not emit a light and a second signal which is output by the target light-receiving element of the plurality of light-receiving elements in a second state in which the light emitting means emits a light; and a correction means for correcting the spectral reflectance information output by the light receiving means based on the correction information determined by the determination means.
  • an image forming apparatus including a measurement apparatus, characterized in that the measurement apparatus comprises: a light emitting means for emitting a light; a light receiving means for receiving a reflected light from a
  • the light receiving means comprises a plurality of light-receiving elements; a determination means for determining correction information based on a first signal which is output by a predetermined light- receiving element of the plurality of light-receiving elements in a first state in which the light emitting means does not emit a light and a second signal which is output by the predetermined light-receiving element of the plurality of light-receiving elements in a second state in which the light emitting means emits a light; and a correction means for correcting the spectral reflectance information output by the light receiving means based on the correction information determined by the determination means.
  • an image forming apparatus including a measurement apparatus, characterized in that the measurement apparatus comprises: a light emitting means for emitting a light; a light receiving means for receiving a reflected light from a
  • the light receiving means comprises a plurality of light-receiving elements; a detection means for detecting a temperature of the light emitting means; a determination means for determining a target light-receiving element of the plurality of light- receiving elements based on the temperature detected by the detection means, and determining correction
  • FIG. 1 is a sectional view showing an example of the arrangement of an image forming
  • Fig. 2 is a view showing the arrangement of a color sensor
  • Fig. 3 is a control block diagram
  • Fig. 4 is a view for explaining an ICC profile
  • FIG. 5 is a schematic view showing a color management environment
  • FIGs. 6A and 6B are block diagrams each including a sensor and control unit according to an embodiment
  • Fig. 7A is a flowchart in measurement of a white reference plate
  • Fig. 7B is a flowchart in patch image measurement (calculation) ;
  • Fig. 7C is a flowchart in patch image measurement (temperature detection) ;
  • Fig. 8 is a view of color measurement in the present invention.
  • Figs. 9A and 9B are graphs for explaining line sensor output fluctuation states before and after light irradiation
  • Figs. 10A and 10B are graphs for explaining line sensor output fluctuation states before and after light irradiation.
  • Figs. 11A and 11B are views for explaining a positional shift of a line sensor caused by
  • the first embodiment will be explained using an electrophotographic laser beam printer. Although the following description is based on the
  • the present invention is also applicable to an image forming apparatus which fixes an image by a thermal drying method, such as an inkjet printer or sublimation printer.
  • a thermal drying method such as an inkjet printer or sublimation printer.
  • Fig. 1 is a sectional view showing the structure of an image forming apparatus (to be referred to as a printer hereinafter) 100 in the embodiment.
  • the printer 100 includes a housing 101.
  • the housing 101 incorporates respective mechanisms for constructing an engine unit, and a control board storage unit (not shown) which stores an engine control unit 312 for performing control concerning respective print
  • an optical processing mechanism As the mechanisms for constructing the engine unit, an optical processing mechanism, fixing processing mechanism, sheet feed processing mechanism, conveyance processing mechanism, and the like are arranged.
  • the optical processing mechanism performs formation of electrostatic latent images on
  • photosensitive drums 105 by scanning of laser beams, visualization of the electrostatic latent images, multiple transfer of the visual images to an
  • the fixing processing mechanism fixes a toner image transferred to the sheet 110.
  • the sheet feed processing mechanism performs sheet feed
  • the conveyance processing mechanism performs conveyance processing of the sheet 110.
  • the optical processing mechanism includes a laser driver in each laser scanner unit 107 to perform ON/OFF driving of a laser beam emitted by a
  • the semiconductor laser (not shown) in accordance with image data supplied from the printer controller 103.
  • the laser beam emitted by the semiconductor laser is oscillated in the scanning direction by a rotating polygon mirror.
  • the laser beam oscillated in the main scanning direction is guided to the photosensitive drum 105 via a reflecting mirror 109 to expose the surface of the photosensitive drum 105 in the main scanning direction.
  • An electrostatic latent image which is charged by a primary charger 111 and formed on the photosensitive drum 105 by scan exposure with a laser beam is visualized into a toner image with toner supplied from a developing unit 112.
  • the toner image visualized on the photosensitive drum 105 is
  • the sheet 110 fed from a storage 113 is conveyed. Simultaneously when transfer rollers 114 press the sheet 110 against the intermediate transfer member 106, a bias opposite in characteristic to the toner is applied to the transfer rollers 114.
  • the visual image formed on the intermediate transfer member 106 is then transferred onto the sheet 110 which is synchronously fed in the sub-scanning direction by the sheet feed processing mechanism (secondary transfer) .
  • the photosensitive drum 105 and developing unit 112 are detachable.
  • An image formation start position detection sensor 115, sheet feed timing sensor 116, and density sensor 117 are arranged around the intermediate
  • the position detection sensor 115 determines a printing start position when performing image formation.
  • the sheet feed timing sensor 116 adjusts the sheet feed timing of the sheet 110.
  • the density sensor 117 measures the density of a measurement image (patch) in density control. When density control is performed, the density sensor 117 measures the density of each patch .
  • the fixing processing mechanism includes a first fixing unit 150 and second fixing unit 160 for fixing a toner image transferred to the sheet 110 by heat and pressure.
  • the first fixing unit 150 includes a fixing roller 151 for applying heat to the sheet 110, a pressure belt 152 for pressing the sheet 110 against the fixing roller 151, and a post-fixing sensor 153 for detecting the completion of fixing.
  • the fixing roller 151 is hollow, incorporates a heater (not shown) , and is configured to convey the sheet 110 simultaneously when the fixing roller 151 is driven to rotate.
  • the second fixing unit 160 is positioned downstream of the first fixing unit 150 in the conveyance path of the sheet 110.
  • the second fixing unit 160 is arranged to add gloss to a toner image on the sheet 110 that has been fixed by the first fixing unit 150, and ensure fixation. Similar to the first fixing unit 150, the second fixing unit 160 also includes a fixing roller 161, pressure roller 162, and post-fixing sensor 163.
  • a conveyance path 130 is arranged to discharge the sheet 110 without passing through the second fixing unit 160.
  • a conveyance path switching flapper 131 can guide the sheet 110 to the conveyance path 130.
  • a conveyance path switching flapper 132 guides the sheet 110 to a conveyance path 135. After a reversing sensor 137 detects the position of the sheet 110, a reversing unit 136 performs a switchback
  • a color sensor 200 configured to detect a patch image on the sheet 110 is further arranged
  • An instruction about a color detection operation is issued in accordance with an instruction from an operation unit 180. Based on the detection result, the engine control unit 312 executes density adjustment, tone adjustment, and multicolor ad ustment .
  • Fig. 2 is a view showing the structure of the color sensor 200 in the embodiment.
  • the color sensor 200 incorporates an LED light source 201, a diffraction grating 202, line sensors 203, that is, 203-1 to 203-s, a calculation unit 204, and a memory 205.
  • the LED light source 201 irradiates, with white light, each toner patch (to be referred to as a patch hereinafter) 207 on a sheet 208.
  • the diffraction grating 202 separates, for respective wavelengths, light which has been reflected by the patch 207 and passed through a window 206.
  • the line sensors 203 that is, 203-1 to 203-s are constructed by s pixels each serving as a light-receiving element configured to detect light decomposed for respective wavelengths by the diffraction grating 202.
  • the calculation unit 204 performs spectral calculation from the light intensity values of the respective pixels that are detected by the line sensors 203.
  • the memory 205 saves various data.
  • the arrangement of the color sensor 200 may incorporate a lens which converges light emitted by the LED light source 201 to the patch 207 on the sheet 208 and converges light reflected by the patch 207 to the diffraction grating 202.
  • the color sensor 200 measures light reflected by a white reference plate 210.
  • the white reference plate 210 may include an
  • the white reference plate 210 may be moved to the vicinity of the position of the sheet 208 or moved to a position where the white reference plate 210 comes into contact with the reverse surface of the sheet 208 even in patch image
  • Fig. 6A is a block diagram showing a sensor and control unit according to the embodiment.
  • a CPU 3001 serving as a control unit performs light quantity setting of the LED light source 201 and data readout from the memory 205.
  • the CPU 3001 issues an
  • the CPU 3001 controls an attaching/detaching motor 3003 to perform the attaching operation of the white reference plate 210 to a
  • the white reference plate 210 is used to adjust the light quantity of the LED light source 201 and calculate the correction coefficient h ⁇ X) .
  • the white reference plate 210 is desired to highly resist light, in order to suppress aged deterioration, and be strong for the attaching/detaching operation. To achieve this, for example, a white reference plate obtained by
  • a white reference plate serving as a criterion measured a white reference plate, and a spectral reflectance obtained when the color sensor 200 measured the same white reference plate.
  • the spectral reflectance hs(500) corresponding to the wavelength 500 [nm] obtained when the white reference plate is measured by the standard measurement device.
  • reference plate is prepared for one color sensor.
  • four white reference plates are also arranged to be paired with the
  • PostScript proposed by Adobe a color separation table in Photoshop®, a CMYK simulation in ColorWise available from EFI to maintain black print information, or the like is also usable.
  • the printer 100 includes the color sensor 200 serving as a reading means on the upstream side of a post-fixing discharge tray (not shown) in the conveyance direction.
  • the printer 100 can measure a spectral reflectance by using the color sensor 200.
  • the printer 100 converts the measurement result into a color value, and
  • the printer 100 performs color conversion processing by using the generated color conversion profile.
  • a calculation method of color value will be explained.
  • a signal input by measuring a color by the color sensor 200 is detected on a CMOS sensor (line sensor 203) arranged in each wavelength region of 380 nm to 720 nm after light emitted by the LED light source 201 is reflected by a measurement target object and the reflected light is separated by the diffraction grating 202.
  • the spectral reflectance is measured for the input signal.
  • the spectral reflectance is converted into L*a*b* values via color matching functions or the like, as defined by CIE, in order to improve the detection calculation accuracy .
  • the color values (L*a*b*) of the patch image are determined based on the measurement result of the patch image. And then, CPU3001 sets the ICC profile based on the color values of the patch image and the signal values used by the engine unit to form the patch image.
  • the following is a method (step) of calculating color values (L*a*b*) from the spectral reflectance. This method is defined by IS013655.
  • the spectral reflectance R( ) of a sample is obtained (380 nm to 780 nm) .
  • Color matching functions ⁇ ( ⁇ ), y ⁇ ) , and ⁇ ( ⁇ ) and a standard light spectral distribution SD50 ( ⁇ ) are prepared. Note that the color matching functions are defined by JIS Z8701. 3 ⁇ 50( ⁇ ) is defined by JIS Z8720 and is also called a supplementary standard illuminant D50.
  • SD50 ( ⁇ ) is integrated with respect to the respective wavelengths :
  • X n , Y n , and Z n are the tristimulus values of standard light:
  • ⁇ ( ⁇ ), ⁇ ( ⁇ ), and z ( ⁇ ) are also described as ⁇ ( ⁇ ) , ⁇ ( ⁇ ) , and ⁇ ( ⁇ ) , respectively.
  • the user In part replacement by a customer engineer, before a job (a print processing) requiring color matching accuracy, or when the user wants to know the tint of a final output material at the design planning stage or the like, the user operates the operation unit 180 to perform color profile generation processing.
  • the profile generation processing is performed in the printer controller 103 shown in the control block diagram of Fig. 3.
  • a profile generation instruction is input to a profile generation unit 301 via the operation unit 180.
  • the profile generation unit 301 sends a signal to a engine unit (engine control unit 312) to output a CMYK color chart of the IS012642 test form (the patch images) without the mediacy of a profile.
  • the profile generation unit 301 sends a measurement
  • the IS012642 test form (the patch images) is transferred and fixed to the sheet 110 by processes such as charging, exposure, development, transfer, and fixing, and the color sensor 200 measures the color.
  • Spectral reflectance data of the measured patch is input to the printer controller 103, and converted into L*a*b* data by a Lab calculation unit 303.
  • the L*a*b* data are converted in accordance with a profile stored in an input ICC profile storage unit 304 for the color sensor, and are input to the profile generation unit 301.
  • the conversion format is not limited to L*a*b*, and spectral reflectance data may be converted into a device-independent color space signal in the CIE1931XYZ colorimetric system.
  • the profile generation unit 301 generates an output ICC profile based on the relationship between the output CMYK patch signals and the input L*a*b* data (converted data) , and replaces, with it, an output ICC profile stored in an output ICC profile storage unit 305.
  • the IS012642 test form includes CMYK color signal patches which cover a color reproduction gamut outputtable by a general copying machine.
  • a color conversion table is generated from the relationship between the respective color signal values and the measured L*a*b* values. That is, a CMYK ⁇ Lab
  • A2B x tag is generated. Based on the conversion table, an inverse conversion table (B2A x tag) is generated.
  • the ICC profile has a structure as shown in
  • Fig. 4 is made up of a header, tags, and their data.
  • the tags describe even a tag (gamt) representing whether a given color expressed by a white point (Wtpt) or a Lab value defined in the profile falls inside or outside the reproducible range of the hard copy.
  • a generated output ICC profile may be uploaded to the external device so that the user can perform color conversion by an application corresponding to the ICC profile.
  • an image signal input on the premise of R, G, and B signal values input via the external I/F 308 such as a scanner unit, or standard printing CMYK signal values such as Japan Color values are sent to an input ICC profile storage unit 307.
  • the input ICC profile storage unit 307 performs RGB ⁇ L*a*b* conversion or CMYK — ⁇ L*a*b* conversion in accordance with the image signal input from the external I/F 308.
  • the input ICC profile is constructed by a one-dimensional LUT which controls an input signal, a multicolor LUT called direct mapping, 4 052592
  • the input image signal is converted from a device-dependent color space into device- independent L*a*b* data by using these tables.
  • the image signals converted into values in the L*a*b* color space coordinate system are input to a CMM (Color Management Module) 306.
  • the image signals undergo gamut conversion, color conversion, black
  • the CMM 306 is a module which performs color management, as shown in Fig. 5, and is assumed to perform color conversion by using an input profile and output profile.
  • Fig. 7A shows a sequence by the CPU 3001 in the measurement operation of the white reference plate 210.
  • the measurement operation of the white reference plate 210 starts.
  • the CPU 3001 instructs the attaching/detaching mechanism of the white reference plate 210 to start the attaching operation.
  • the CPU 3001 determines whether the attaching operation of the white reference plate 210 has ended.
  • the attaching operation end determination method for example, there are a method of waiting for the time taken for the attaching
  • step S302 the process advances to step S303.
  • step S303 the CPU 3001 designates the ON operation of the LED light source 201.
  • step S304 the CPU 3001 instructs the color sensor 200 to start
  • step S305 the CPU 3001 designates the start of the detaching operation of the white reference plate 210 upon completion of measuring the reflected light quantity ⁇ ( ⁇ ). After that, the measurement operation ends .
  • Fig. 6A is a block diagram showing the sensor and control unit according to the first embodiment.
  • the CPU 3001 performs light quantity setting of the LED light source 201, designation of the start of
  • the CPU 3001 instructs the sheet conveying unit 3002 about the sheet conveyance timing in patch image measurement.
  • the CPU 3001 controls the attaching/detaching motor 3003 to perform the attaching operation of the white reference plate 210 to a predetermined position in calibration and the attaching operation to the reverse surface of a sheet in patch image measurement. In the above-described attaching operation, the white
  • reference plate 210 is assumed to be moved to a
  • Fig. 8 is a view showing an image of a color measurement chart according to the embodiment.
  • a plurality of (M) color patch images are arranged in the sheet conveyance direction at positions facing the color sensor 200.
  • ⁇ ( ⁇ ) is measured at the timing when each color patch image passes through a position facing the color sensor 200.
  • a patch 207-1 to be measured first a high- density patch is printed. The timing when the ⁇ ( ⁇ ) value when a patch passes on the measurement region of the color sensor 200 has changed from the value of the blank portion of a sheet is detected as a trigger to determine the timing of subsequent patch image
  • Fig. 7B shows a sequence by the CPU 3001 in the ⁇ ( ⁇ ) measurement operation.
  • the ⁇ ( ⁇ ) measurement operation starts after measurement of the white reference plate 210 which has described with reference to Fig. 7A.
  • the CPU 3001 instructs the sheet conveying unit to supply the color measurement chart.
  • the CPU 3001 measures the dark current value ⁇ ( ⁇ ) of the line sensor 203.
  • the CPU 3001 saves the dark current measurement result in the memory 205.
  • the ⁇ ) is corresponded to each of the plurality of light-receiving elements and stored.
  • the CPU 3001 designates the ON operation of the LED light source 201.
  • the CPU 3001 performs a wait operation for a
  • the CPU 3001 detects the non-light-receiving region of the first to nth (n is an arbitrary natural number) pixels in the line sensor 203.
  • the detection method will be described later.
  • the light-receiving region means pixels which receive light reflected by a measurement target (in this case, a patch or the like) among a plurality of pixels (detection region) included in the line sensor 203.
  • light-receiving region means pixels which do not
  • step S406 If the CPU 3001 determines that the region of the first to nth pixels is the non-light-receiving region (YES in step S406) , it calculates a dark current fluctuation in step S407. If the CPU 3001 determines that the region of the first to nth pixels is not the non-light-receiving region (NO in step S406) , it
  • step S409 the CPU 3001 saves the dark current fluctuation calculation result in the memory 205.
  • step S410 the CPU 3001 detects the timing when the first patch 207-1 passes through the measurement region of the color sensor 200.
  • step S411 the CPU 3001 sets an initial value of 1 in a variable m representing the number of measured patches.
  • step S413, the CPU 3001 designates
  • step S413 the CPU 3001 determines
  • the predetermined patch count M corresponds to the number of patches printed on a sheet. If the
  • step S415 the CPU 3001 waits the measurement operation for the time based on a predetermined patch interval.
  • the time based on the predetermined patch interval is determined by the interval between patches shown in Fig. 8 and the sheet conveyance speed. Then, the process shifts to step S412 to sequentially measure ⁇ ( ⁇ ) of an unmeasured patch.
  • step S416 the CPU 3001 outputs the measurement result of the patch obtained by a calculation method (to be described later) . After that, the patch image color measurement operation ends.
  • a dark current value before irradiation by the LED light source 201 is measured in step S402, and a dark current value after irradiation by the LED light source 201 (that is, a dark current value in the thermal
  • the measurement value is corrected based on the values before and after irradiation by the LED light source 201.
  • Figs. 9A and 9B are graphs each showing the output fluctuation of the line sensor 203 in patch image measurement.
  • the ordinate represents the output value of the line sensor 203
  • the abscissa represents each pixel forming the line sensor 203.
  • a dark current value indicated by a broken line is the dark current value of the line sensor 203 that is measured in step S402 of Fig. 7B.
  • An output in measurement indicated by a solid line is an output from the line sensor 203 after emission of the LED light source 201.
  • Fig. 9B is an enlarged view showing a portion of the 0th to 15th line sensor outputs among line sensor outputs shown in Fig.
  • D(i) is a line sensor output value in the ith pixel
  • D(i) is a dark current value in the ith pixel.
  • the D(i) means D ( ⁇ ) corresponding to the ith light-receiving element.
  • the calculated a is compared with a preset threshold ⁇ to specify a non-light-receiving region. At this time, if ⁇ ⁇ ⁇ (that is, a is smaller than the threshold) , a is regarded as a dark current output fluctuation and is saved as a dark current correction value in the memory 205.
  • Fig. 11A shows a state in which a plurality of pixels positioned at the left end of the line sensor 203 form a non-light- receiving region.
  • Fig. 11B shows a state in which a plurality of pixels positioned at the right end of the line sensor 203 form a non-light-receiving region.
  • the state in Fig. 11A corresponds to the output state shown in Figs. 9A and 9B.
  • the state in Fig. 11B corresponds to the output state shown in Figs. 10A and 10B.
  • Fig. 10B is an enlarged view of part of Fig. 10A.
  • s is the number of pixels included in the line sensor 203
  • s-n is the nth pixel from the right end of the line sensor 203.
  • a' is compared with the threshold ⁇ , similar to step S407. If ⁇ ' ⁇ ⁇ , ⁇ ' is regarded as an output fluctuation and is saved as a dark current correction value in the memory 205.
  • the calculation unit 204 in the color sensor 200 calculates the spectral
  • CPU 3001 may calculate the output fluctuation a (or a') based on a output value (a dark current value) of a non-light-receiving pixel
  • the apparatus can detect the dark current value on a real-time basis and measure a color with higher accuracy. Also, the embodiment has explained an arrangement in which one color sensor measures the colors of patch images
  • Fig. 6B is a block diagram showing a sensor and control unit according to the second embodiment.
  • a color sensor 200 further includes a thermistor 211 serving as a temperature detection unit.
  • a CPU 3001 further instructs the color sensor 200 to detect a temperature by the thermistor 211.
  • a color measurement chart has the same layout as that in Fig. 8 described in the first embodiment.
  • Fig. 7C shows a sequence by the CPU 3001 in the ⁇ ( ⁇ ) measurement operation.
  • the ⁇ ( ⁇ ) measurement operation starts after measurement of a white reference plate 210 which has described with reference to Fig. 7A.
  • the CPU 3001 instructs a sheet conveying unit to supply the color measurement chart.
  • the CPU 3001 measures the dark current value of the line sensor 203.
  • the CPU 3001 saves the dark current measurement result in a memory 205.
  • step S504 the CPU 3001 designates the ON operation of an LED light source 201.
  • step S505 the CPU 3001 performs a wait operation for a predetermined time.
  • the wait operation is performed to wait until the line sensor 203 changes to the thermal equilibrium state by reflected light.
  • step S506 the CPU 3001 instructs the thermistor 211 to detect a temperature. Based on the result of the temperature detected in step S507, the CPU 3001 compares the temperature detection value with a threshold T (threshold for estimating a preset non- light-receiving region) by a method (to be described later) . If the temperature detection value is smaller than the threshold T, the CPU 3001 estimates that the first to nth pixels among pixels included in the line sensor 203 form a non-light-receiving region. Note that pixels forming a non-light-receiving region or the fluctuation amount of a non-light-receiving region may be defined in advance in a table or the like in
  • the determination is made using the table representing the relationship between a detected temperature and the pixels of a non-light-receiving region.
  • step S507 If the detected temperature is lower than the threshold T (YES in step S507), the CPU 3001 calculates a dark current fluctuation from the first to nth pixels of the line sensor 203 (step S508). If the detected temperature is equal to or higher than the threshold T (NO in step S507), the CPU 3001 calculates a dark current fluctuation from the sth to (s-n)th pixels of the line sensor 203 (step S509) . In step S510, the CPU 3001 saves the dark current fluctuation calculation result in the memory 205. In step S511, the CPU 3001 detects the timing when a first patch 207- 1 passes through the measurement region of the color sensor 200. In step S512, the CPU 3001 sets an initial value of 1 in a variable m representing the number of measured patches. In step S513, the CPU 3001
  • step S514 the CPU 3001 determines whether the measurement count has reached a
  • step S516 the CPU 3001 waits the measurement operation for the time based on a predetermined patch interval.
  • the time based on the predetermined patch interval is determined by the interval between patches shown in Fig. 8 and the sheet conveyance speed. Then, the process shifts to step S513 to sequentially measure P ( ⁇ ) of an unmeasured patch. If the measurement count has reached the predetermined patch count M (YES in step S514), the CPU 3001 performs dark current correction for the measurement value obtained by the line sensor 203 in step S517.
  • step S518 the CPU 3001 outputs the measurement result of the patch obtained by a
  • Figs. 9A and 9B each show the output fluctuation of the line sensor 203 in patch image measurement when the temperature
  • a dark current value indicated by a broken line is the dark current value of the line sensor 203 that is measured in step S502 of Fig. 7C.
  • step S509 The calculation method is the same as that in the first embodiment, and a description thereof will not be repeated.
  • the dark current correction method in step S517 is also the same as that in the first embodiment, and a description thereof will not be repeated.
  • the second embodiment can obtain the same effects as those of the first
  • Embodiments of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable
  • the computer may comprise one or more of a central processing unit (CPU) , micro processing unit (MPU) , or other circuitry, and may include a network, of separate computers or separate computer processors.
  • the storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM) , a read only memory (ROM) , a storage of distributed computing
  • an optical disk such as a compact disc (CD) , digital versatile disc (DVD), or Blu-ray Disc (BD)TM
  • CD compact disc
  • DVD digital versatile disc
  • BD Blu-ray Disc

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Color Image Communication Systems (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Color Electrophotography (AREA)

Abstract

La présente invention porte sur un appareil de mesure qui comprend : un moyen électroluminescent destiné à émettre une lumière ; un moyen de réception de lumière destiné à recevoir une lumière réfléchie provenant d'une cible de mesure, et délivrer en sortie des informations de réflectance spectrale, le moyen de réception de lumière comprend une pluralité d'éléments de réception de lumière ; un moyen de détermination destiné à déterminer des informations de correction sur la base d'un premier signal qui est délivré en sortie par un élément de réception de lumière prédéterminé de la pluralité d'éléments de réception de lumière dans un premier état dans lequel le moyen électroluminescent n'émet pas une lumière et d'un second signal qui est délivré en sortie par l'élément de réception de lumière prédéterminé dans un second état dans lequel le moyen électroluminescent émet une lumière ; et un moyen de correction destiné à corriger les informations de réflectance spectrale délivrées en sortie par le moyen de réception de lumière sur la base des informations de correction déterminées par le moyen de détermination.
PCT/JP2014/052592 2013-02-20 2014-01-29 Appareil de mesure et appareil formant image Ceased WO2014129305A1 (fr)

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US11237050B2 (en) 2011-11-03 2022-02-01 Verifood, Ltd. Low-cost spectrometry system for end-user food analysis
US9952098B2 (en) 2013-08-02 2018-04-24 Verifood, Ltd. Spectrometry system with decreased light path
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US11320307B2 (en) 2015-02-05 2022-05-03 Verifood, Ltd. Spectrometry system applications
US10502679B2 (en) 2015-04-07 2019-12-10 Verifood, Ltd. Detector for spectrometry system
CN107820563A (zh) * 2015-06-02 2018-03-20 凯塞光学系统股份有限公司 来自阵列检测器光谱仪的光谱的收集、暗校正和报告的方法
CN107820563B (zh) * 2015-06-02 2021-07-20 凯塞光学系统股份有限公司 来自阵列检测器光谱仪的光谱的收集、暗校正和报告的方法
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US10203246B2 (en) 2015-11-20 2019-02-12 Verifood, Ltd. Systems and methods for calibration of a handheld spectrometer
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US12044617B2 (en) 2018-10-08 2024-07-23 Verifood, Ltd. Accessories for optical spectrometers

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