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WO2019017127A1 - Dispositif de lecture d'image, dispositif de formation d'image, et procédé de lecture d'image - Google Patents

Dispositif de lecture d'image, dispositif de formation d'image, et procédé de lecture d'image Download PDF

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Publication number
WO2019017127A1
WO2019017127A1 PCT/JP2018/022987 JP2018022987W WO2019017127A1 WO 2019017127 A1 WO2019017127 A1 WO 2019017127A1 JP 2018022987 W JP2018022987 W JP 2018022987W WO 2019017127 A1 WO2019017127 A1 WO 2019017127A1
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WIPO (PCT)
Prior art keywords
light
spectrum
correction value
calibration
image reading
Prior art date
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Ceased
Application number
PCT/JP2018/022987
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English (en)
Japanese (ja)
Inventor
謙一郎 河▲崎▼
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.)
Kyocera Document Solutions Inc
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Kyocera Document Solutions Inc
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Filing date
Publication date
Application filed by Kyocera Document Solutions Inc filed Critical Kyocera Document Solutions Inc
Priority to JP2019530937A priority Critical patent/JP6760505B2/ja
Publication of WO2019017127A1 publication Critical patent/WO2019017127A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • 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
    • B41J29/393—Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T1/00—General purpose image data processing
    • 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
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • 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
    • H04N1/48—Picture signal generators

Definitions

  • the present invention relates to an image reading apparatus, an image forming apparatus, and an image reading method, and more particularly, to a technology for achieving accurate color reproduction using a white LED as a light source for image reading.
  • Patent Document 1 facilitates calibration of a color sensor for suppressing the influence of deterioration of sensor output due to change in output due to time-dependent change or ambient temperature change of light emitting unit and light receiving unit constituting a color sensor, and contamination of the sensor surface. It proposes technology. On the other hand, it has also been proposed to adopt a plurality of LEDs as a light source of the image reading unit to increase the light quantity in response to the demand for higher resolution and higher speed in image reading.
  • Patent Document 1 has not sufficiently considered the error of color reproduction due to the variation of a plurality of light sources for image reading.
  • the present invention has been made in view of such circumstances, and it is an object of the present invention to provide a technique for easily suppressing an error in color reproduction caused by variations in a plurality of light sources for image reading.
  • the present invention provides an image reading apparatus for reading an image on a document.
  • the image reading apparatus includes a first source light source emitting light having a first spectrum and a second source light source emitting light having a second spectrum, the light having the first spectrum and Image data according to a plurality of light sources for emitting white light including light having the second spectrum, light having the first spectrum from the document, and reflected light of the light having the second spectrum
  • An image reading unit for generating the second spectrum, a reflected light quantity of the light having the first spectrum from the calibration original prepared in advance for calibration of the light having the second spectrum, and the first spectrum
  • a correction value determination unit for determining an overall correction value for calibrating the light quantity having the first spectrum as a ratio to a calibration reference value set as a standard of the reflected light quantity of light having;
  • the value determination unit is configured to determine the amount of reflected light of the first spectrum from the calibration document when one of the plurality of light sources is turned on, and the first spectrum for the one light source.
  • a partial correction value for calibrating the light quantity having the first spectrum is determined as a ratio to a calibration reference value set as a standard of the reflected light quantity of light having the first correction value, the partial correction value and the total correction value
  • the total correction value is determined using the correction value relation information representing the relation with the above and the partial correction value.
  • An image forming apparatus includes the image reading apparatus and an image forming unit that forms an image based on the image data, and the image forming unit uses the entire correction value to generate the image data. And a calibration unit configured to calibrate image data generated according to the reflected light of the light having the first spectrum.
  • the present invention provides an image reading method for reading an image on a document.
  • the image reading method uses a plurality of light sources respectively including a first source light source emitting light having a first spectrum and a second source light source emitting light having a second spectrum, Irradiating white light including light having a spectrum of: and light having the second spectrum; reflected light of light having the first spectrum from the original and light having the second spectrum
  • the step of determining the correction value includes the step of reflecting the amount of reflected light of the first spectrum from the calibration document when one of the plurality of light sources is turned on;
  • a partial correction value for calibrating the light amount having the first spectrum
  • FIG. 1 is a schematic configuration view showing an entire configuration of an image forming apparatus 1 according to an embodiment of the present invention.
  • FIG. 1 is a cross-sectional view showing an entire configuration of an image forming apparatus 1 according to an embodiment.
  • 5 is a flowchart showing the contents of a light source calibration process procedure of the image forming apparatus 1 according to an embodiment.
  • 5 is a flowchart showing the contents of a light source calibration process procedure of the image forming apparatus 1 according to an embodiment.
  • 5 is a flowchart showing the contents of an LED calibration processing procedure of the image forming apparatus 1 according to an embodiment. It is a graph which shows the relationship between the frequency characteristic of the patch for calibration of cyan and the frequency band of red light concerning one embodiment.
  • FIG. 1 is a block diagram showing a functional configuration of an image forming apparatus 1 according to an embodiment of the present invention.
  • the image forming apparatus 1 includes a control unit 10, an image forming unit 20, a storage unit 40, and an image reading unit 50.
  • the control unit 10 includes a main storage unit such as a RAM and a ROM, and a processor such as an MPU (Micro Processing Unit) and a CPU (Central Processing Unit).
  • the control unit 10 also has a controller function related to interfaces such as various I / O, USB (Universal Serial Bus), bus, and other hardware, and controls the entire image forming apparatus 1.
  • the storage unit 40 is a storage device including a hard disk drive or a flash memory, which is a non-temporary recording medium, and stores control programs and data of processing executed by the control unit 10.
  • the storage unit 40 further stores calibration image data CI and B reference value data Bref as calibration data CD for printing an adjustment document for CMYK calibration.
  • the calibration image data CI is stored in the storage unit 40 as RGB data.
  • the image reading unit 50 reads an image from a document and generates an image data ID which is digital data.
  • the image reading unit 50 includes a light source driver 51 and a plurality of white light sources 52 for irradiating the document P with light.
  • the image reading unit 50 includes two white light sources 52.
  • the plurality of white light sources 52 are arranged in the main scanning direction.
  • the light source driver 51 is an LED driver that drives each LED of the white light source 52.
  • the light source driver 51 performs on / off drive control of the white light source 52. Since the plurality of white light sources 52 are provided, it is possible to realize an increase in scanning speed and an increase in resolution while suppressing a decrease in S / N ratio leading to a granular feeling by increasing the light amount.
  • the white light source 52 is a white light source including a blue LED 52a and a yellow phosphor 52b.
  • the blue LED 52a functions as a source of blue light of the three primary colors.
  • the yellow phosphor 52b is a phosphor that functions as a source light source that emits blue light from the blue LED 52a and emits red light and green light.
  • the white light source 52 can emit red light, green light and blue light, and thus functions as a white LED.
  • the inventor of the present invention has found that the brightness and the spectrum of the blue light vary depending on the chromaticity rank in the white LED.
  • the chromaticity rank indicates the color variation.
  • the spectrum of red light and green light emitted as photoluminescence by phosphors is small in fluctuation of the spectrum, while the spectrum of blue light is relatively fluctuated relatively to red light and green light with small fluctuation in spectrum. I found a thing. This is presumed to be due to the structure of the white LED described above.
  • the storage unit 40 stores B reference value data Bref that is a calibration reference value of blue light.
  • B reference value data Bref reference value data used when both of the two white light sources 52 are turned on, and reference value data used when one of the two white light sources 52 is turned on And are included.
  • the image sensor 53 has a plurality of light receiving elements 53a.
  • the image sensor 53 is a line sensor having a plurality of light receiving elements 53a.
  • the plurality of light receiving elements 53a are arranged in the main scanning direction.
  • the plurality of light receiving elements 53a generate charges photoelectrically converted according to the intensity of each incident light.
  • the generated charge is transferred by an analog shift register (not shown).
  • Each transferred charge is converted by the charge-to-voltage conversion amplifier into an analog electrical signal which is a voltage signal.
  • the image sensor 53 can output an analog electric signal for each pixel in the main scanning direction.
  • the image reading unit 50 further includes a signal processing unit 54, an AGC processing unit 55, and a white reference plate (not shown).
  • the signal processing unit 54 amplifies the analog electrical signal with the gain set by the AGC processing unit 55 and stored in the storage unit 40, and A / D converts the amplified analog electrical signal to generate digital data.
  • the generated digital data is an image data ID.
  • the image forming unit 20 forms and discharges an image on a print medium based on the image data ID.
  • the image data ID is data having a range width of the minimum value “0” and the maximum value “255”.
  • the AGC processing unit 55 is a gain adjustment unit that sets the optimum gain and offset value for each of the plurality of light receiving elements 53a using the black reference signal and the white reference signal.
  • the black reference signal is an analog electrical signal of the light receiving element 53a when the white light source 52 is off.
  • the white reference signal is an analog electric signal of the light receiving element 53a when the white reference plate (not shown) is illuminated instead of the document P.
  • the AGC processing unit 55 sets an offset value such that the value of the image data ID when the black reference signal is A / D converted becomes the minimum value “0”.
  • the AGC processing unit 55 sets the gain such that the value of the image data ID when the white reference signal is A / D converted using this offset value is the maximum value “255”.
  • the fluctuation of the analog electrical signal due to increase or decrease of the reflected light between the black reference signal and the white reference signal can be effectively used from the minimum value "0" to the maximum value "255" of the image data ID. It becomes.
  • the detected RGB gradation is the same even if the RGB gradation of the document is the same.
  • the amount of light of B of the white light source 52 is larger than the amount of light of R or G, the amount of reflected light of B increases even if the gradation of RGB of the document is the same.
  • the image forming unit 20 includes a color conversion processing unit 21, a density sensor 22 for calibration, an exposure unit 23, developing units 24c to 24k, and charging units 25c to 25k.
  • the color conversion processing unit 21 performs color conversion of image data ID, which is RGB data, into CMYK, and executes halftone processing to generate CMYK halftone data.
  • FIG. 2 is a cross-sectional view showing the overall configuration of the image forming apparatus 1 according to an embodiment of the present invention.
  • the image forming apparatus 1 of the present embodiment is a tandem type color printer.
  • photosensitive drums 26 m, 26 c, 26 y and 26 k are arranged in a line in the casing 70 corresponding to each color of magenta, cyan, yellow and black.
  • the photosensitive drums 26m, 26c, 26y and 26k are image carriers.
  • Developing portions 24m, 24c, 24y and 24k are disposed adjacent to the photosensitive drums 26m, 26c, 26y and 26k, respectively.
  • the laser beams Lm, Lc, Ly and Lk for respective colors are irradiated from the exposure unit 23 to the photosensitive drums 26m, 26c, 26y and 26k.
  • electrostatic latent images are formed on the photosensitive drums 26m, 26c, 26y and 26k.
  • the developing units 24m, 24c, 24y and 24k adhere the toner to the electrostatic latent images formed on the surfaces of the photosensitive drums 26m, 26c, 26y and 26k while stirring the toner.
  • the developing process is completed, and toner images of the respective colors are formed on the surfaces of the photosensitive drums 26m, 26c, 26y and 26k.
  • the image forming apparatus 1 has an endless intermediate transfer belt 27a.
  • the intermediate transfer belt 27a is stretched around a tension roller 27c, a drive roller 27b and a driven roller 27d.
  • the intermediate transfer belt 27a is driven to circulate by the rotation of the drive roller 27b.
  • the black toner image on the photosensitive drum 26k is primarily transferred to the intermediate transfer belt 27a by holding the intermediate transfer belt 27a between the photosensitive drum 26k and the primary transfer roller 29k and driving the intermediate transfer belt 27a to circulate. Ru.
  • a full-color toner image is formed on the surface of the intermediate transfer belt 27a by performing primary transfer so as to be superimposed on each other at a predetermined timing. Thereafter, the full-color toner image is secondarily transferred onto the printing paper P supplied from the paper feed cassette 60, and is fixed on the printing paper P in a known fixing process.
  • FIG. 3A is a flowchart showing the contents of the first light source calibration process of the image forming apparatus 1 according to one embodiment.
  • FIG. 3B is a flowchart showing the contents of the second light source calibration process of the image forming apparatus 1 according to one embodiment.
  • the first light source calibration process is a light source calibration process using both of the two white light sources 52.
  • the second light source calibration process is a simplified light source calibration process using only one of the two white light sources 52.
  • the first light source calibration process is performed at the time of adjustment before shipping of the image forming apparatus 1, and is also performed by the user as needed after shipping.
  • the second light source calibration process is performed periodically or according to the situation on the user side after shipment of the image forming apparatus 1.
  • step S100 the control unit 10 executes a first LED calibration process.
  • the first LED calibration process is an LED calibration process performed by lighting only one of the two white light sources 52.
  • FIG. 4 is a flowchart showing the contents of the LED calibration processing procedure of the image forming apparatus 1 according to an embodiment.
  • the user uses the image forming apparatus 1 to print the adjustment document for CMYK calibration.
  • the adjustment document for CMYK calibration is a document to be printed using the calibration image data CI read from the storage unit 40.
  • the calibration image data CI is RGB data for calibration.
  • the calibration RGB data includes C calibration R gradation data, M calibration G gradation data, Y calibration B gradation data, and K calibration RGB (gray) gradation data. Printing of the adjustment document for CMYK calibration is performed using a user interface for execution provided in a preset calibration menu (not shown).
  • the C calibration R gradation data is data for printing a plurality of patches representing each gradation of R.
  • the M calibration G gradation data, the Y calibration B gradation data, and the K calibration RGB (gray) gradation data are data for printing a plurality of patches representing the respective gradations of MYK.
  • the calibration RGB data is configured to print all the patches on one print medium which is preset using these data. As described above, the image forming apparatus 1 outputs the adjustment document for CMYK calibration based on the calibration image data CI.
  • step S112 the user scans the adjustment document for CMYK calibration using the image reading unit 50 of the image forming apparatus 1.
  • the image reading unit 50 reads an image from the adjustment document for CMYK calibration and generates print image data for calibration which is digital data.
  • the proofreading print image data is generated as RGB image data based on the absorption characteristics of RGB light in the CMYK proofreading adjustment document.
  • the calibration print image data may be generated by forming a patch on the intermediate transfer belt 27 a and using the calibration density sensor 22.
  • the image forming apparatus 1 detects the RGB reflected light amount based on the printing image data for calibration.
  • the RGB reflected light amount corresponds to the gradation value of the calibration print image data RGB.
  • the RGB reflected light amount is the light absorption amount Ar of red light in the patch of each gradation of the known cyan adjustment original, the absorption amount Ag of green light in the patch of each gradation of the known magenta adjustment original, and the known yellow adjustment This corresponds to the absorption amount Ab of blue light in the patch of each gradation of the original, and the absorption amount of RGB in the patch of each gradation of the known gray adjustment original.
  • the light absorption amount Ar of red light corresponds to the gradation value of R.
  • the green light absorption amount Ag corresponds to the gradation value of G.
  • the blue light absorption amount Ab corresponds to the gradation value of B.
  • the light absorption amount of RGB corresponds to the gradation value of RGB.
  • FIG. 5A is a graph showing the relationship between the frequency characteristics of the cyan calibration patch and the frequency band of red light according to one embodiment.
  • FIG. 5B is a graph showing the relationship between the frequency characteristics of the calibration patch for magenta and the frequency band of green light according to one embodiment.
  • the horizontal axes shown in FIGS. 5A and 5B indicate the wavelength of light, and the vertical axes indicate the amount of reflected light.
  • FIG. 5A shows an example of the reflection spectrum Rc of the cyan calibration patch of the cyan adjustment original and the absorption spectrum Sr of the cyan calibration patch.
  • the cyan calibration patch of the cyan adjustment original is also referred to as a C calibration patch.
  • the light absorption amount Ar indicates the amount of light absorbed by the cyan calibration patch of the cyan adjustment original, that is, the peak value of the amount of light not reflected.
  • the light absorption amount Ar peaks in the red light wavelength band.
  • FIG. 5B shows an example of the reflection spectrum Rm of the magenta calibration patch of the magenta adjustment document and the absorption spectrum Sg of the magenta calibration patch.
  • the magenta calibration patch of the magenta adjustment original is also referred to as an M calibration patch.
  • the light absorption amount Ag indicates the amount of light absorbed by the magenta calibration patch of the magenta adjustment document, that is, the peak value of the amount of light not reflected.
  • the light absorption amount Ag peaks in the green light wavelength band.
  • the absorption amount Ar of red light shown in FIG. 5A is detected by the image sensor 53, and is used for calibration of the image forming unit 20 by comparing the relationship between the gradation of the cyan calibration patch and the absorption amount Ar of red light.
  • the absorption amount Ag of green light shown in FIG. 5B is detected by the image sensor 53, and is used for calibration of the image forming unit 20 by comparing the relationship between the gradation of the magenta calibration patch and the absorption amount Ag of green light.
  • the gradation of cyan corresponds to the area ratio of cyan dots, and the area ratio of cyan dots increases as the gradation of cyan increases. In other words, as the gradation of cyan is higher, the red light is absorbed by the cyan dot, and the absorption amount Ar of the red light becomes larger. The same applies to the gradation of magenta.
  • step S114 the image forming apparatus 1 performs CM calibration based on the RG reflected light amount.
  • CM calibration is performed as calibration of dot area rates of cyan toner and magenta toner in halftone processing.
  • the light absorption amount Ar is It is calibrated to reduce the area ratio so as to approach the set absorbance. That is, when the area ratio of cyan dots is high, calibration is performed so that the area ratio is decreased so that the light absorption amount Ar approaches the set light absorption amount.
  • the scan result of the print image actually formed is calibrated so as to approach the calibration RGB data.
  • step S115 the image forming apparatus 1 executes K calibration based on the RGB reflected light amount.
  • the K calibration is performed in the present embodiment as a calibration of the dot area rate of the gray patch by the black toner in the halftone process. Specifically, for example, when the detection result of the light absorption amount (not shown) of the patch formed by the K gradation data for K calibration is larger than the set absorption amount which is a known light absorption amount set in advance, It is calibrated to reduce the area ratio so that the absorbance approaches the set absorbance. That is, when the area ratio of the black dots is high, calibration is performed so as to reduce the area ratio so that the light absorption amount approaches the set light absorption amount.
  • step S116 the image forming apparatus 1 executes Y calibration based on the B reflected light amount.
  • Y calibration is performed as calibration of the dot area ratio of yellow toner in halftone processing.
  • the basic method is the same as the CM calibration performed based on the RG reflected light amount shown in step S114. However, this is different from the CM calibration based on the RG reflected light amount shown in step S114 in that Y calibration B gradation data is corrected using a B correction value ⁇ acquired by a method described later.
  • the B calibration data for Y calibration corresponds to the detection result of the light absorption amount Ab of the patch.
  • the B correction value ⁇ is an overall correction value ⁇ 3 described later.
  • FIG. 6A is a graph showing the relationship between the frequency characteristic of the yellow calibration patch and the frequency band of blue light according to one embodiment.
  • FIG. 6B is a graph showing the relationship between the frequency characteristics of the cyan calibration patch and the frequency band of blue light according to one embodiment.
  • FIG. 6A shows an example of the reflection spectrum Ry of the yellow calibration patch of the yellow adjustment original and the absorption spectrum Sb of the yellow calibration patch.
  • the yellow calibration patch is also referred to as a Y calibration patch.
  • the light absorption amount Ab indicates the amount of light absorbed by the yellow calibration patch of the yellow adjustment original, that is, the peak value of the amount of light not reflected.
  • the light absorption amount Ab peaks in the wavelength band of blue light.
  • FIG. 6B shows an example of the reflection spectrum Rc of the cyan calibration patch of the cyan adjustment original and the absorption spectrum Sb of the yellow calibration patch.
  • the cyan calibration patch is also referred to as a C calibration patch. That is, it is a graph showing the relationship between the reflection spectrum Rc of the cyan calibration patch shown in FIG. 5A and the absorption spectrum Sb of the yellow calibration patch shown in FIG. 6A.
  • the reflection spectrum Rc of the cyan calibration patch blue light having a wavelength in the range of 400 nm to 500 nm is reflected with almost no absorption.
  • step S122 the image reading unit 50 detects the B reflected light amount from the C calibration patch of the adjustment document for scanner C calibration.
  • B The scanner C calibration adjustment original used for red light calibration is used to detect the amount of reflected light because the wavelengths of the red light and blue light are largely different, so the scanner C calibration adjustment original is blue light Because it reflects almost without absorbing it.
  • the control unit 10 stores the B correction value ⁇ in the storage unit 40.
  • the B correction value ⁇ is a ratio of the gradation value to be detected when the blue light quantity of the white light source 52 is a reference value to the gradation value actually detected.
  • the RGB_Bc value which is the actual detection amount
  • step S200 the control unit 10 executes a second LED calibration process.
  • the second LED calibration process is an LED calibration process performed by lighting only the other of the two white light sources 52.
  • the contents of the second LED calibration process are the same as the first LED calibration process except for the white light source 52 to be lit.
  • the B partial correction value ⁇ 2 of the other white light source 52 of the two white light sources 52 is acquired.
  • step S300 the control unit 10 executes both LED calibration processing.
  • Both LED calibration processes are LED calibration processes performed by lighting both of two white light sources 52.
  • the contents of both LED calibration processes are the same as the first LED calibration process and the second LED calibration process except for the white light source 52 to be lit and the B reference value data Bref.
  • reference value data used when both of the white light sources 52 of the B reference value data Bref are turned on is used.
  • the B overall correction value ⁇ 3 which is the correction value ⁇ at the time of lighting of both white light sources 52 is calculated.
  • step S400 the control unit 10 executes measurement target LED selection processing.
  • the measurement target LED selection process is a process of selecting a white light source 52 having a B-portion maximum correction value ⁇ L which is the largest correction value ⁇ among the B-portion correction values ⁇ 1 or ⁇ 2 out of the two white light sources 52.
  • the measurement target LED is a white light source 52 to be measured in the second light source calibration process.
  • step S500 the control unit 10 executes a table generation process.
  • the control unit 10 generates a table indicating the correspondence between the B overall correction value ⁇ 3 when both white light sources 52 are lit and the B portion maximum correction value ⁇ L of the selected white light source 52.
  • the wavelength of the LED generally changes to the longer wavelength side as the temperature becomes higher.
  • the change in the wavelength of the white light source 52 having the B partial maximum correction value ⁇ L is used
  • the B whole correction value ⁇ 3 can be estimated.
  • the LEDs have very close characteristics when they have chips diced from the same wafer, and can improve estimation accuracy.
  • the present invention executes the first light source calibration process at the time of adjustment before shipment and prepares the above-described table, thereby enabling execution of the second light source calibration process that is simple and consumes less power after shipment. . However, in consideration of aging and the like, it may be performed after shipment if necessary.
  • the table stores correction value relationship information representing the relationship between the B-portion maximum correction value ⁇ L and the overall correction value ⁇ 3.
  • step S610 shown in FIG. 3B the control unit 10 executes measurement target LED measurement processing.
  • the control unit 10 turns on the measurement target LED, executes the LED calibration process, and acquires the B-portion maximum correction value ⁇ L.
  • step S620 the control unit 10 executes a calibration process using this B-portion maximum correction value ⁇ L.
  • the control unit 10 estimates the B overall correction value ⁇ 3 when both LEDs are lit, using the B portion maximum correction value ⁇ L to be measured and the LED table. The estimation can be performed by interpolation or extrapolation based on a table.
  • the image forming apparatus 1 uses the B entire correction value ⁇ 3 to calculate the light amount when the blue light amount of the white light source 52 is the reference value even if the blue light amount of the white light source 52 fluctuates from the reference value. It can be estimated.
  • the control unit 10 can function as a calibration unit that calibrates image data using the B entire correction value ⁇ 3.
  • the image forming apparatus 1 can easily suppress an error in color reproduction due to the variation of a plurality of light sources for image reading without installing new hardware. .
  • Modified Example 1 Although the above embodiment is calibrated by adjusting the dot area ratio, it may be calibrated by adjusting, for example, the exposure energy, the charging bias, and the developing bias. Although it is possible to calibrate the variation of the light amount of RGB of the light source by adjusting the AGC, the calibration in the image forming process as described above has an advantage of not narrowing the dynamic range of RGB at the time of image reading.
  • Modified Example 2 in the above embodiment, it has a blue LED that emits light having a first spectrum, and a yellow phosphor that is excited by the light having a first spectrum to emit light having a second spectrum.
  • a white light source 52 is used, the white light source 52 is not limited to this example. Blue LEDs are also referred to as source light sources.
  • the image reading unit of the CCD system is adopted, but the invention is not limited to the CCD system, and another system such as the CIS system may be adopted.
  • the CIS method since RGB source light sources are generally used, the present invention can also be applied to suppress variations in RGB source light sources.
  • the white light source 52 comprises a source light source emitting light having a first spectrum, a source light source emitting light having a second spectrum, and a source light source emitting light having a third spectrum. It will have.
  • the white light source 52 generally comprises a first source light source emitting light having a first spectrum and a second source light source emitting light having a second spectrum, the light having a first spectrum Any light source may be used as long as it emits white light including light having a second spectrum.
  • the second source light source may be a phosphor that is excited by light having a first spectrum to emit light having a second spectrum.
  • the adjustment document for scanner C calibration is used as an example of a patch prepared in advance for the calibration of light having the second spectrum, but it is an adjustment document for scanner M calibration May be However, it is generally preferable to use a scanner C calibration adjustment document, which has a lower absorptivity in the blue light band than the scanner M calibration adjustment document.
  • Modification 5 Although the present invention is applied to the image forming apparatus in the above embodiment, the present invention is also applicable to a dedicated scanner or other image reading apparatus.

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  • Facsimile Image Signal Circuits (AREA)

Abstract

L'invention concerne un dispositif de lecture d'image (1) comprenant : une pluralité de sources de lumière (52) qui comprennent respectivement une première source de lumière source qui émet de la lumière comportant un premier spectre et une seconde source de lumière source qui émet de la lumière comportant un second spectre, et émettent une lumière blanche ; une unité de lecture d'image (50) qui génère des données d'image (ID) selon la lumière de réflexion provenant d'un manuscrit (P) ; et une unité de détermination de valeur de correction qui calcule une valeur de correction totale (α3) pour étalonner la quantité de lumière comportant le premier spectre à l'aide du rapport d'une quantité de lumière de réflexion de la lumière comportant le premier spectre provenant d'un manuscrit d'étalonnage préparé à l'avance de façon à étalonner la lumière comportant le second spectre et une valeur de référence d'étalonnage définie en tant que référence de la quantité de lumière de réflexion de la lumière comportant le premier spectre. L'unité de détermination de valeur de correction détermine une valeur de correction partielle par rapport à une source de lumière (52) parmi la pluralité de sources de lumière (52), et calcule la valeur de correction totale à l'aide de la valeur de correction partielle et des informations de relation de valeur de correction qui indiquent une relation entre la valeur de correction partielle et la valeur de correction totale.
PCT/JP2018/022987 2017-07-18 2018-06-15 Dispositif de lecture d'image, dispositif de formation d'image, et procédé de lecture d'image Ceased WO2019017127A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009118142A (ja) * 2007-11-06 2009-05-28 Pfu Ltd 画像読取装置
JP2010178213A (ja) * 2009-01-30 2010-08-12 Sharp Corp 画像読取装置及び画像形成装置
JP2014053882A (ja) * 2012-08-08 2014-03-20 Ricoh Co Ltd スキャナ装置
JP2016146375A (ja) * 2015-02-06 2016-08-12 東レ株式会社 蛍光体含有樹脂シート、それを用いた発光装置およびその製造方法
JP2017046249A (ja) * 2015-08-27 2017-03-02 京セラドキュメントソリューションズ株式会社 画像読取装置、画像読取方法及び制御プログラム

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009118142A (ja) * 2007-11-06 2009-05-28 Pfu Ltd 画像読取装置
JP2010178213A (ja) * 2009-01-30 2010-08-12 Sharp Corp 画像読取装置及び画像形成装置
JP2014053882A (ja) * 2012-08-08 2014-03-20 Ricoh Co Ltd スキャナ装置
JP2016146375A (ja) * 2015-02-06 2016-08-12 東レ株式会社 蛍光体含有樹脂シート、それを用いた発光装置およびその製造方法
JP2017046249A (ja) * 2015-08-27 2017-03-02 京セラドキュメントソリューションズ株式会社 画像読取装置、画像読取方法及び制御プログラム

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