JP2019164126A - Optical sensor device, color measuring device, and image forming apparatus - Google Patents

Abstract

An optical sensor device that can be used for accurate colorimetry is provided at a lower cost. A first light source having a plurality of peak wavelengths in a wavelength range of 400 nm to 780 nm, a second light source capable of irradiating ultraviolet light, and an object reflected by the first light source or the second light source are reflected. A first light amount adjusting unit that adjusts a light amount of the first light source from an output of the sensor in a state where the first light source is turned on and the second light source is turned off; A second light amount adjusting unit that adjusts the light amount of the second light source based on the output of the sensor in a state where the two light sources are turned on and the first light source is turned off; A correction unit that obtains a correction value of data output from the sensor from an output of the sensor in a state where the two light sources are turned on. [Selection diagram] FIG.

Description

  The present invention relates to an optical sensor device, a color measuring device, and an image forming apparatus.

  Conventionally, there is a technique for capturing a reference pattern and a color object to be measured and correcting the color of the color object to be measured.

  Patent Document 1 includes a light source that has a light emitting diode having a peak value of emission intensity in a wavelength range of 380 nm to 420 nm, and irradiates white light to a color object to be measured, and performs color measurement by performing spectral diffraction. A colorimetric device is disclosed.

  However, according to the conventional color measuring device, there is a problem that the color measuring accuracy is good but expensive.

  The present invention has been made in view of the above, and an object thereof is to provide an optical sensor device that can be used for accurate color measurement at a lower cost.

  In order to solve the above-described problems and achieve the object, the present invention provides a first light source having a plurality of peak wavelengths in a wavelength range of 400 nm to 780 nm, a second light source capable of irradiating ultraviolet light, and the first A sensor that receives light reflected by the object irradiated by the light source or the second light source, and an output of the sensor in a state where the first light source is turned on and the second light source is turned off. A first light amount adjustment unit that adjusts the light amount, and a second light amount adjustment unit that adjusts the light amount of the second light source from the output of the sensor in a state where the second light source is turned on and the first light source is turned off. And a correction unit that acquires a correction value of data output from the sensor from the output of the sensor in a state where the first light source and the second light source are lit with the adjusted light amount. .

  According to the present invention, an optical sensor device that can be used for accurate colorimetry can be provided at a lower cost.

FIG. 1 is a perspective view illustrating the inside of the image forming apparatus according to the first embodiment. FIG. 2 is a top view showing an internal mechanical configuration of the image forming apparatus. FIG. 3 is a diagram for explaining an arrangement example of the recording heads mounted on the carriage. FIG. 4A is a longitudinal sectional view of the imaging unit. FIG. 4B is a top view of the imaging unit with a perspective view. FIG. 4-3 is a plan view of the bottom surface of the housing as viewed from the X2 direction in FIG. 4-1. FIG. 5 is a block diagram illustrating a schematic configuration of a control mechanism of the image forming apparatus. FIG. 6 is a diagram illustrating an example of image data obtained by simultaneously imaging the reference chart and the imaging target. FIG. 7 is a block diagram illustrating a configuration example of the control mechanism of the color measurement device. FIG. 8 is a diagram for explaining processing for obtaining a reference colorimetric value and a reference RGB value and processing for generating a reference value linear transformation matrix. FIG. 9 is a diagram illustrating an example of the initial reference RGB values. FIG. 10 is a diagram for explaining basic colorimetry processing. FIG. 11 is a diagram for explaining basic colorimetry processing. FIG. 12 is a flowchart schematically showing the flow of light amount / sensor adjustment / colorimetry processing before colorimetry. FIG. 13 is a longitudinal sectional view of an imaging unit according to the second embodiment. FIG. 14 is a diagram illustrating a configuration of a reflective colorimetric sensor according to the third embodiment. FIG. 15 is a diagram illustrating a captured image for each paper type according to the fourth embodiment. FIG. 16 is a diagram illustrating an example of a table of RGB values for each paper type. FIG. 17 is a flowchart schematically showing the flow of the paper type discrimination process. FIG. 18 is a flowchart showing the flow of colorimetric preprocessing using the paper type discrimination process.

(First embodiment)
Exemplary embodiments of an optical sensor device, a colorimetric device, and an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In the embodiments described below, an inkjet printer is illustrated as an example of an image forming apparatus to which the present invention is applied. However, the present invention is widely applied to various types of image forming apparatuses that output an image to a recording medium. Applicable.

<Mechanical configuration of image forming apparatus>
First, the mechanical configuration of the image forming apparatus 100 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view illustrating the inside of the image forming apparatus 100 according to the first embodiment. FIG. 2 is a top view illustrating the internal mechanical configuration of the image forming apparatus 100. FIG. 5 is a diagram for explaining an example of the arrangement of the recording heads 6 mounted on the recording medium.

  As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment reciprocates in the main scanning direction (arrow A direction in the figure) and is intermittently conveyed in the sub-scanning direction (arrow B direction in the figure). A carriage 5 for forming an image on the recording medium 16. The carriage 5 is supported by a main guide rod 3 extending along the main scanning direction. The carriage 5 is provided with a connecting piece 5a. The connecting piece 5 a engages with the sub guide member 4 provided in parallel with the main guide rod 3 to stabilize the posture of the carriage 5.

  As shown in FIG. 2, the carriage 5 includes a recording head 6y that discharges yellow (Y) ink, a recording head 6m that discharges magenta (M) ink, a recording head 6c that discharges cyan (C) ink, and black. (Bk) A plurality of recording heads 6k that discharge ink (hereinafter, the recording heads 6y, 6m, 6c, and 6k are collectively referred to as recording heads 6) are mounted. The recording head 6 is mounted on the carriage 5 so that its ejection surface (nozzle surface) faces downward (on the recording medium 16 side). The recording head 6 is a main body of image output means.

  A cartridge 7, which is an ink supply body for supplying ink to the recording head 6, is not mounted on the carriage 5 and is disposed at a predetermined position in the image forming apparatus 100. The cartridge 7 and the recording head 6 are connected by a pipe (not shown), and ink is supplied from the cartridge 7 to the recording head 6 through this pipe.

  The carriage 5 is connected to a timing belt 11 stretched between a driving pulley 9 and a driven pulley 10. The drive pulley 9 is rotated by driving the main scanning motor 8. The driven pulley 10 has a mechanism for adjusting the distance to the driving pulley 9 and has a role of applying a predetermined tension to the timing belt 11. The carriage 5 reciprocates in the main scanning direction when the timing belt 11 is fed by driving the main scanning motor 8. The movement of the carriage 5 in the main scanning direction is controlled based on an encoder value obtained by detecting a mark on the encoder sheet 40 by an encoder sensor 41 provided on the carriage 5, for example, as shown in FIG.

  Further, the image forming apparatus 100 according to the present embodiment includes a maintenance mechanism 21 for maintaining the reliability of the recording head 6. The maintenance mechanism 21 performs cleaning and capping of the ejection surface of the recording head 6 and discharging unnecessary ink from the recording head 6.

  A platen plate 22 is provided at a position facing the ejection surface of the recording head 6 as shown in FIG. The platen plate 22 is for supporting the recording medium 16 when ink is ejected from the recording head 6 onto the recording medium 16. The image forming apparatus 100 according to the present embodiment is a wide-width machine in which the moving distance of the carriage 5 in the main scanning direction is long. For this reason, the platen plate 22 is constituted by connecting a plurality of plate-like members in the main scanning direction (movement direction of the carriage 5). The recording medium 16 is nipped by a conveyance roller driven by a sub scanning motor (not shown), and is intermittently conveyed on the platen plate 22 in the sub scanning direction.

  The recording head 6 includes a plurality of nozzle arrays, and forms an image on the recording medium 16 by ejecting ink from the nozzle arrays onto the recording medium 16 conveyed on the platen plate 22. In this embodiment, in order to secure a large width of an image that can be formed on the recording medium 16 by one scan of the carriage 5, as shown in FIG. 3, the upstream recording head 6 and the downstream recording head are provided on the carriage 5. The head 6 is mounted. Further, the recording head 6k that discharges black ink is mounted on the carriage 5 as many times as the recording heads 6y, 6m, and 6c that discharge color ink. The recording heads 6y and 6m are arranged separately on the left and right. This is because the color stacking order is adjusted by the reciprocating operation of the carriage 5 so that the color does not change between the forward path and the return path. The arrangement of the recording heads 6 shown in FIG. 3 is an example, and the arrangement is not limited to the arrangement shown in FIG.

  Each of the above-described constituent elements constituting the image forming apparatus 100 according to the present embodiment is disposed inside the exterior body 1. The exterior body 1 is provided with a cover member 2 that can be opened and closed. At the time of maintenance of the image forming apparatus 100 or when a jam occurs, the cover member 2 can be opened to perform work on each component provided inside the exterior body 1.

  The image forming apparatus 100 according to the present embodiment intermittently conveys the recording medium 16 in the sub scanning direction, and moves the carriage 5 in the main scanning direction while the conveyance of the recording medium 16 in the sub scanning direction is stopped. Then, ink is ejected from the nozzle array of the recording head 6 mounted on the carriage 5 onto the recording medium 16 on the platen plate 22 to form an image on the recording medium 16.

  In particular, when calibration for adjusting the output characteristics of the image forming apparatus 100 is performed, ink is ejected from the nozzle row of the recording head 6 mounted on the carriage 5 onto the recording medium 16 on the platen plate 22. Thus, the patch image 200 to be colorimetric is formed on the recording medium 16. The patch image 200 is an image obtained when the image forming apparatus 100 outputs a reference color patch, and reflects the output characteristics of the image forming apparatus 100. Therefore, a color conversion parameter is generated based on the difference between the colorimetric value of the patch image 200 and the corresponding color value of the reference color in the standard color space, and color conversion is performed using this color conversion parameter. By outputting an image based on the image data, the image forming apparatus 100 can output an image with high reproducibility.

  The image forming apparatus 100 according to the present embodiment includes a color measurement device for measuring the color of the patch image 200 output to the recording medium 16. The colorimetric device includes an image pickup unit 42 that takes a patch image 200 to be colorimetrically formed on the recording medium 16 by the image forming apparatus 100 as a subject and images the patch image 200 and a reference chart 400 described later. The colorimetric device calculates the colorimetric value of the patch image 200 based on the image data of the reference chart 400 obtained by imaging by the imaging unit 42 and the image data of the patch image 200 obtained by imaging by the imaging unit 42. Note that this color measurement device uses not only the function of calculating the color measurement value of the patch image 200 but also the amount of positional deviation of the image output by the image forming apparatus 100 using the image data obtained by the imaging unit 42. The function of calculating, the function of calculating the amount of positional deviation of the image formed by the image forming apparatus 100 using the image data obtained by the imaging of the imaging unit 42, and the dot diameter of the image output by the image forming apparatus 100 are calculated. It also has a function to do.

  As shown in FIG. 2, the imaging unit 42 is provided fixed to the carriage 5 and reciprocates in the main scanning direction together with the carriage 5. Then, the imaging unit 42 takes the image formed on the recording medium 16 (the patch image 200 to be colorimetric when the patch image 200 is colorimetric) as a subject, and moves to a position facing this subject. And one frame of image data including the reference chart 400 is acquired.

<Specific example of imaging unit>
4A to 4C are diagrams illustrating specific examples of the imaging unit 42. FIG. 4A is a longitudinal sectional view of the imaging unit 42 (cross-sectional view taken along line X1-X1 in FIG. 4-2). 4-2 is a top view showing the inside of the imaging unit 42 as seen through, and FIG. 4-3 is a plan view of the bottom surface of the housing as viewed from the X2 direction in FIG. 4-1.

  The imaging unit 42 includes a housing 421 configured by combining a frame body 422 and a substrate 423. The frame 422 is formed in a bottomed cylindrical shape in which one end side which is the upper surface of the housing 421 is opened. The substrate 423 is fastened to the frame body 422 by the fastening member 424 and integrated with the frame body 422 so as to close the open end of the frame body 422 and configure the upper surface of the housing 421.

  The housing 421 is fixed to the carriage 5 so that the bottom surface portion 421a thereof faces the recording medium 16 on the platen plate 22 with a predetermined gap d. An opening for allowing the subject (patch image 200) formed on the recording medium 16 to be photographed from the inside of the casing 421 is provided on the bottom surface (first surface) 421 a of the casing 421 facing the recording medium 16. 425 is provided.

  A sensor unit 430 that captures an image is provided inside the housing 421. The sensor unit 430 includes a two-dimensional image sensor 431 such as a CCD sensor or a CMOS sensor, and an imaging lens 432 that forms an optical image in the imaging range of the sensor unit 430 on the sensor surface of the two-dimensional image sensor 431. The two-dimensional image sensor 431 is mounted on, for example, the inner surface (component mounting surface) of the substrate 423 so that the sensor surface faces the bottom surface portion 421a side of the housing 421. The imaging lens 432 is fixed in a state of being positioned with respect to the two-dimensional image sensor 431 so as to maintain the positional relationship determined according to the optical characteristics.

  A chart plate 410 on which a reference chart 400 is formed is disposed on the inner surface of the bottom surface 421a of the housing 421 facing the sensor unit 430 so as to be adjacent to the opening 425 provided in the bottom surface 421a. Yes. For example, the chart plate 410 is bonded to the inner surface side of the bottom surface portion 421a of the housing 421 with an adhesive or the like, with the surface opposite to the surface on which the reference chart 400 is formed, being attached to the housing 421. It is held in a fixed state. The reference chart 400 may be directly formed on the inner surface side of the bottom surface portion 421a of the housing 421 instead of on the chart plate 410. In this case, the chart plate 410 is not necessary. The reference chart 400 is taken together with the subject (patch image 200) by the sensor unit 430. Details of the reference chart 400 will be described later.

  In addition, an illumination light source 426 that illuminates the subject (patch image 200) and the reference chart 400 when the sensor unit 430 captures the subject (patch image 200) and the reference chart 400 is provided inside the housing 421. It has been. For example, an LED is used as the illumination light source 426. In the present embodiment, four LEDs are used as the illumination light source 426. These four LEDs used as the illumination light source 426 are mounted on the inner surface of the substrate 423 together with the two-dimensional image sensor 431 of the sensor unit 430, for example. However, the illumination light source 426 only needs to be disposed at a position where the subject (patch image 200) and the reference chart 400 can be illuminated, and is not necessarily mounted directly on the substrate 423. Moreover, in this embodiment, although LED is used as the illumination light source 426, the kind of light source is not limited to LED. For example, an organic EL or the like may be used as the illumination light source 426.

  The four LEDs used as the illumination light source 426 include two white LEDs 426a that are first light sources having a plurality of peak wavelengths in a wavelength range of 400 nm to 780 nm, and two UV LEDs 426b that are second light sources capable of emitting ultraviolet light. It is. The UV LED 426b is provided outside or inside the white LED 426a so as to be a target for the sensor unit 430. In the present embodiment, the UV LED 426b is disposed inside the white LED 426a.

  Further, in the present embodiment, as shown in FIG. 4B, when the four LEDs used as the illumination light source 426 are vertically looked down from the substrate 423 side to the bottom surface portion 421a side of the housing 421, the projection on the bottom surface portion 421a. It arrange | positions so that a position may become in the area | region between the opening part 425 and the reference | standard chart 400. FIG. Further, these four LEDs are arranged so that the two white LEDs 426a are symmetric with respect to the sensor unit 430, and the two UV LEDs 426b are in positions of interest with respect to the sensor unit 430. In other words, the housing 421 is arranged at a position where a line connecting four LEDs used as the illumination light source 426 passes through the center of the imaging lens 432 of the sensor unit 430 and is symmetrical with respect to a line connecting the four LEDs. The opening 425 provided in the bottom surface portion 421a and the reference chart 400 are arranged. By arranging the four LEDs used as the illumination light source 426 in this way, the subject (patch image 200) and the reference chart 400 can be illuminated under substantially the same conditions.

  Further, if the gap d between the bottom surface 421a of the housing 421 and the recording medium 16 is reduced, the optical path length from the sensor unit 430 to the subject (patch image 200) and the optical path from the sensor unit 430 to the reference chart 400 The difference from the length may be within the range of the depth of field of the sensor unit 430. The imaging unit 42 of the present embodiment has a configuration in which a sensor unit 430 captures a subject (patch image 200) outside the housing 421 and a reference chart 400 provided inside the housing 421. Therefore, if the difference between the optical path length from the sensor unit 430 to the subject (patch image 200) and the optical path length from the sensor unit 430 to the reference chart 400 exceeds the range of the depth of field of the sensor unit 430, the subject ( An image focused on both the patch image 200) and the reference chart 400 cannot be captured.

  The difference between the optical path length from the sensor unit 430 to the subject (patch image 200) and the optical path length from the sensor unit 430 to the reference chart 400 is approximately a value obtained by adding the gap d to the thickness of the bottom surface part 421a of the housing 421. Become. Therefore, if the gap d is set to a sufficiently small value, the difference between the optical path length from the sensor unit 430 to the subject (patch image 200) and the optical path length from the sensor unit 430 to the reference chart 400 is calculated. An image focused on both the subject (patch image 200) and the reference chart 400 can be captured within the depth of field. For example, if the gap d is set to about 1 mm to 2 mm, the difference between the optical path length from the sensor unit 430 to the subject (patch image 200) and the optical path length from the sensor unit 430 to the reference chart 400 is determined by the sensor unit 430. It can be within the depth of field.

  Note that the depth of field of the sensor unit 430 is determined according to the aperture value of the sensor unit 430, the focal length of the imaging lens 432, the distance between the sensor unit 430 and the subject, and the like. It is. In the imaging unit 42 of the present embodiment, when the gap d between the bottom surface 421a of the housing 421 and the recording medium 16 is set to a sufficiently small value, for example, about 1 mm to 2 mm, the subject (patch) The sensor unit 430 is designed such that the difference between the optical path length to the image 200) and the optical path length from the sensor unit 430 to the reference chart 400 is within the depth of field.

<Schematic configuration of control mechanism of image forming apparatus>
Next, a schematic configuration of the control mechanism of the image forming apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram illustrating a schematic configuration of a control mechanism of the image forming apparatus 100.

  The control mechanism of the image forming apparatus 100 according to the present embodiment includes a host CPU 107, a ROM 118, a RAM 119, a main scanning driver 109, a recording head driver 111, a color measurement control unit 50, a paper conveyance unit 112, a sub scanning driver 113, and a recording head 6. An encoder sensor 41 and an imaging unit 42. The recording head 6, the encoder sensor 41, and the imaging unit 42 are mounted on the carriage 5 as described above.

  The host CPU 107 supplies image data and drive control signals (pulse signals) to be formed on the recording medium 16 to each driver, and controls the entire image forming apparatus 100. Specifically, the upper CPU 107 controls driving of the carriage 5 in the main scanning direction via the main scanning driver 109. The host CPU 107 controls the ink ejection timing by the recording head 6 via the recording head driver 111. Further, the upper CPU 107 controls driving of the paper conveyance unit 112 including a conveyance roller and a sub scanning motor via the sub scanning driver 113.

  The encoder sensor 41 outputs an encoder value obtained by detecting the mark on the encoder sheet 40 to the upper CPU 107. The upper CPU 107 controls driving of the carriage 5 in the main scanning direction via the main scanning driver 109 based on the encoder value from the encoder sensor 41.

  As described above, the imaging unit 42 detects the patch image 200 and the reference chart 400 on the chart plate 410 disposed inside the housing 421 at the time of color measurement of the patch image 200 formed on the recording medium 16. The image is captured at 430 and image data including the patch image 200 and the reference chart 400 is output to the colorimetric control unit 50.

  FIG. 6 is a diagram illustrating an example of image data obtained by simultaneously imaging the reference chart and the imaging target. As illustrated in FIG. 6, the imaging unit 42 images each patch of the reference chart 400 arranged inside the frame body 32. The image data shown in FIG. 8 is an example in which a reference chart 400 is fixedly arranged on the left half surface with respect to the two-dimensional image sensor 431 and a colorimetric object is imaged on the right half surface. The RGB signal value to be imaged is obtained by averaging a part of the right imaging area. In the example shown in FIG. 6, the RGB signals in the broken line area are obtained by averaging. By averaging a large number of pixels, the influence of noise can be reduced and the bit resolution can be improved.

  The colorimetric control unit 50 calculates a colorimetric value (colorimetric value in the standard color space) of the patch image 200 based on the patch image 200 acquired from the imaging unit 42. The colorimetric values of the patch image 200 calculated by the colorimetry control unit 50 are sent to the host CPU 107. The color measurement control unit 50 constitutes a color measurement device together with the imaging unit 42. In the present embodiment, the colorimetric control unit 50 is configured separately from the imaging unit 42, but the colorimetric control unit 50 may be integrated with the imaging unit 42. For example, a control circuit that functions as the colorimetric control unit 50 may be mounted on the substrate 423 of the imaging unit 42.

  In addition, the colorimetric control unit 50 supplies various setting signals, timing signals, light source driving signals, and the like to the image pickup unit 42 and controls image pickup by the image pickup unit 42. The various setting signals include a signal for setting an operation mode of the sensor unit 430 and a signal for setting an imaging condition such as a shutter speed and an AGC gain. These setting signals are acquired by the colorimetric control unit 50 from the host CPU 107 and supplied to the imaging unit 42. The timing signal is a signal that controls the timing of imaging by the sensor unit 430, and the light source driving signal is a signal that controls the driving of the illumination light source 426 that illuminates the imaging range of the sensor unit 430. These timing signals and light source drive signals are generated by the colorimetric control unit 50 and supplied to the imaging unit 42.

  The ROM 118 stores, for example, programs such as processing procedures executed by the host CPU 107, various control data, and the like. The RAM 119 is used as a working memory for the upper CPU 107.

<Configuration of control mechanism of color measuring device>
Next, the control mechanism of the color measuring device will be specifically described with reference to FIG. FIG. 7 is a block diagram illustrating a configuration example of the control mechanism of the color measurement device.

  The color measurement device includes an imaging unit 42 and a color measurement control unit 50. The imaging unit 42 further includes an image processing unit 45 and an interface unit 46 in addition to the sensor unit 430 and the illumination light source 426 described above. In the present embodiment, the image processing unit 45 is configured separately from the sensor unit 430. However, the two-dimensional image sensor 431 of the sensor unit 430 may have the function of the image processing unit 45.

  The image processing unit 45 processes image data captured by the sensor unit 430, and includes an AD conversion unit 451, a shading correction unit 452, a white balance correction unit 453, a γ correction unit 454, and an image format conversion unit 455. .

  The AD conversion unit 451 converts the analog signal output from the sensor unit 430 from analog to digital.

  The shading correction unit 452 corrects an error in image data caused by uneven illumination of illumination from the illumination light source 426 with respect to the imaging range of the sensor unit 430.

  The white balance correction unit 453 corrects the white balance of the image data.

  The γ correction unit 454 corrects the image data so as to compensate for the sensitivity linearity of the sensor unit 430.

  The image format conversion unit 455 converts the image data into an arbitrary format.

  The interface unit 46 is used for the imaging unit 42 to acquire various setting signals, timing signals, and light source driving signals sent from the colorimetry control unit 50, and to send image data from the imaging unit 42 to the colorimetry control unit 50. Interface.

  The colorimetry control unit 50 includes a frame memory 51, a calculation unit 53, a timing signal generation unit 54, a light source drive control unit 55, and a nonvolatile memory 60.

  The frame memory 51 is a memory that temporarily stores the image data sent from the imaging unit 42.

  As shown in FIG. 8, the non-volatile memory 60 is a colorimetric value L * that is a colorimetric value of a plurality of reference color patches KP arrayed on the reference sheet KS by a spectroscope (colorimetry device) BS. At least one of the a * b * value and the XYZ value (both the L * a * b * value and the XYZ value in FIG. 8) is patched to the memory table Tb1 of the nonvolatile memory 60 as a reference colorimetric value. Stored in correspondence with the number.

  The nonvolatile memory 60 also stores read RGB values (Rd, Gd, Bd) of each patch of the reference chart 400 when the white LED 426a is lit and when the UV LED 426b is lit.

  The nonvolatile memory 60 also stores read RGB values (Rd′Gd′Bd ′) of each patch of the reference chart 400 at the time of color measurement of the white LED 426a and at the time of color measurement of the UV LED 426b.

  The calculation unit 53 includes a colorimetric value calculation unit (calculation unit) 531. The calculation unit 53 includes a processor such as a CPU, for example, and implements the function of the colorimetric value calculation unit 531 by executing a predetermined program by the processor. In this embodiment, the colorimetric value calculation unit 531 of the calculation unit 53 is realized by software. However, a part or all of these are implemented by ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or the like. It can also be realized by using dedicated hardware.

  When the sensor unit 430 of the imaging unit 42 images the patch image 200 to be measured, the colorimetric value calculation unit 531 calculates the colorimetric value of the patch image 200 based on the patch image 200 obtained by the imaging. calculate. The colorimetric values of the patch image 200 calculated by the colorimetric value calculation unit 531 are sent to the upper CPU 107. Details of a specific example of processing by the colorimetric value calculation unit 531 will be described later.

  The timing signal generation unit 54 generates a timing signal for controlling the timing of imaging by the sensor unit 430 of the imaging unit 42 and supplies the timing signal to the imaging unit 42.

  The light source drive control unit 55 generates a light source drive signal for driving the illumination light source 426 (white LED 426a, UV LED 426b) of the imaging unit 42 and supplies the light source drive signal to the imaging unit 42. The light source drive control unit 55 functions as a first light amount adjustment unit and a second light amount adjustment unit.

<Color measurement method for patch images>
Next, a color measurement method of the patch image 200 by the image forming apparatus 100 according to the present embodiment will be described in detail. This color measurement method is performed during pre-processing that is performed when the image forming apparatus 100 is in an initial state (when the image forming apparatus 100 is in an initial state due to manufacturing, overfall, or the like) and during adjustment that performs color adjustment of the image forming apparatus 100. Color measurement processing to be performed.

  FIG. 8 is a diagram for explaining processing for obtaining a reference colorimetric value and a reference RGB value and processing for generating a reference value linear transformation matrix. These processes shown in FIG. 8 are implemented as pre-processing. In the preprocessing, a reference sheet KS on which a plurality of reference patches KP are formed is used. The reference patches KP of the reference sheet KS may be the same as the patches of the reference chart 400 included in the imaging unit 42, but it is preferable that the number is larger than the patches included in the reference chart 400.

  First, at least one of L * a * b * values and XYZ values that are colorimetric values of a plurality of reference patches KP of the reference sheet KS (in the example of FIG. 8, L * a * b * values and XYZ values). Are stored in a memory table Tb1 provided in, for example, the non-volatile memory 60 in the colorimetric control unit 50, corresponding to each patch number. The colorimetric value of the reference patch KP is a value obtained in advance by colorimetry using the spectroscope BS or the like. If the colorimetric value of the reference patch KP is known, that value may be used. Hereinafter, the colorimetric values of the reference patch KP stored in the memory table Tb1 are referred to as “reference colorimetric values”.

  Next, the reference sheet KS is set on the platen plate 22, and the movement of the carriage 5 is controlled, so that the imaging unit 42 performs imaging using the plurality of reference patches KP of the reference sheet KS as subjects.

  Then, the RGB values of each patch (initial reference color patch) of the reference sheet KS obtained by imaging by the imaging unit 42 are stored in the memory table Tb1 of the nonvolatile memory 60 corresponding to the patch number. That is, in the memory table Tb1, the colorimetric values and RGB values of the plurality of reference patches KP arranged on the reference sheet KS are stored in correspondence with the patch numbers of the respective reference patches KP. Hereinafter, the RGB values of the reference patch KP stored in the memory table Tb1 are referred to as “reference RGB values”. The reference RGB value is a value reflecting the characteristics of the imaging unit 42.

  When the reference colorimetric value and the reference RGB value of the reference patch KP are stored in the memory table Tb1 of the non-volatile memory 60, the host CPU 107 of the image forming apparatus 100 uses the XYZ value that is the reference colorimetric value of the same patch number and the reference A reference value linear transformation matrix for mutually converting the RGB value pair is generated and stored in the nonvolatile memory 60. When only the L * a * b * value is stored as the reference colorimetric value in the memory table Tb1, L * a * b is converted using a known conversion formula for converting the L * a * b * value into an XYZ value. * After converting values to XYZ values, a reference value linear conversion matrix may be generated.

  Further, when the imaging unit 42 captures the plurality of reference patches KC of the reference sheet KS, the reference chart 400 provided in the imaging unit 42 is also captured at the same time. The RGB values of each patch of the reference chart 400 obtained by this imaging are also stored in the memory table Tb1 of the nonvolatile memory 60 in association with the patch number. The RGB values of the patches of the reference chart 400 stored in the memory table Tb1 by this preprocessing are referred to as “initial reference RGB values”. FIG. 9 is a diagram illustrating an example of the initial reference RGB values. FIG. 9A shows a state in which the initial reference RGB value (RdGdBd) is stored in the memory table Tb1, and the initial reference Lab obtained by converting the initial reference RGB value (RdGdBd) into the Lab value together with the initial reference RGB value and (RdGdBd). It shows that the initial reference XYZ value (XdYdZd) converted into the value (Ldadbd) and the XYZ value is also stored in association with each other. FIG. 9B is a scatter diagram in which initial reference RGB values of each patch of the reference chart 400 are plotted.

  After the above preprocessing is completed, the image forming apparatus 100 allows the upper CPU 107 to control the main scanning movement of the carriage 5 and the recording medium P by the paper conveyance unit 112 based on image data input from the outside, print settings, and the like. The control of the recording head 6 and the drive control of the recording head 6 are performed to control the ink ejection from the recording head 6 while the recording medium P is intermittently conveyed, and an image is output to the recording medium P. At this time, the amount of ink ejected from the recording head 6 may change depending on the characteristics inherent to the device or changes over time. When this ink ejection amount changes, the color differs from the color of the image intended by the user. As a result, the color reproducibility deteriorates. Therefore, the image forming apparatus 100 performs a color measurement process for obtaining a color measurement value of the patch image 200 at a predetermined timing for color adjustment. And color reproducibility is improved by performing color adjustment based on the colorimetric value obtained by the colorimetric processing.

  10 and 11 are diagrams for explaining basic colorimetric processing. The colorimetric value calculation unit 531 first reads the reference value linear conversion matrix generated in the preprocessing and stored in the nonvolatile memory 60, and uses the reference value linear conversion matrix to calculate the colorimetric target RGB values (RsGsBs) in the first XYZ. It converts into a value and stores it in the non-volatile memory 60 (step S21). FIG. 10 shows an example in which the initialization colorimetric object RGB values (3, 200, 5) are converted to the first XYZ values (20, 80, 10) by the reference value linear conversion matrix.

  Next, the colorimetric value calculation unit 531 converts the first XYZ value converted from the colorimetric target RGB value (RsGsBs) in step S21 into a first L * a * b * value using a known conversion formula. It stores in the non-volatile memory 60 (step S22). FIG. 10 shows an example in which the first XYZ values (20, 80, 10) are converted into the first L * a * b * values (75, −60, 8) by a known conversion formula.

  Next, the colorimetric value calculation unit 531 searches a plurality of reference colorimetric values (L * a * b * values) stored in the memory table Tb1 of the nonvolatile memory 60 in the preprocessing, and the reference colorimetric values. Among (L * a * b * values), it has a reference colorimetric value (L * a * b * value) that is close to the first L * a * b * value in the L * a * b * space. A set of a plurality of patches (neighboring color patches) is selected (step S23). As a method for selecting a patch having a short distance, for example, the distance from the first L * a * b * value to all the reference colorimetric values (L * a * b * values) stored in the memory table Tb1. And a plurality of patches having L * a * b * values (L * a * b * values that are hatched in FIG. 10) that are close to the first L * a * b * values. A method of selecting can be used.

  Next, as shown in FIG. 11, the colorimetric value calculation unit 531 refers to the memory table Tb1 and makes a pair with the L * a * b * value for each of the neighboring color patches selected in step S23. RGB values (reference RGB values) and XYZ values are extracted, and a combination of RGB values and XYZ values is selected from the plurality of RGB values and XYZ values (step S24). Then, the colorimetric value calculation unit 531 obtains a selected RGB value linear conversion matrix for converting the RGB value of the selected combination (selected set) into an XYZ value using a least square method or the like, and obtains the selected RGB value obtained. The linear transformation matrix is stored in the nonvolatile memory 60 (step S25).

  Next, the colorimetric value calculation unit 531 converts the colorimetric target RGB values (RsGsBs) into the second XYZ values using the selected RGB value linear conversion matrix generated in step S25 (step S26). Further, the colorimetric value calculation unit 531 converts the second XYZ value obtained in step S26 into a second L * a * b * value using a known conversion formula (step S27), and obtains the obtained second L * a. The * b * value is the final colorimetric value of the patch image 200 to be measured. The image forming apparatus 100 improves color reproducibility by performing color adjustment based on the colorimetric values obtained by the above colorimetric processing.

  By the way, when the “color measurement reference patch Rd′Gd′Bd ′ value” when the color measurement target is actually measured varies, it may not match the “initial reference patch RdGdBd value”. Possible causes of the fluctuation include a change with time of the illumination light source and a change with time of the sensor sensitivity. If conversion is performed using the selected RGB value linear conversion matrix in such a state where it is fluctuated in this way, the final colorimetric value is also fluctuated, and it is expected that highly accurate colorimetry cannot be performed.

  Therefore, in the present embodiment, the LED light amount and the sensor sensitivity (white) are measured before color measurement so that the “color measurement reference patch Rd′Gd′Bd ′ value” always matches the “initial reference patch RdGdBd value”. Adjust the balance and γ correction.

  Here, FIG. 12 is a flowchart schematically showing the flow of the light amount / sensor adjustment / colorimetry process before colorimetry. As shown in FIG. 12, the colorimetric value calculation unit 531 first turns on only the white LED 426a with PWM Duty A [%] (step S1), images the reference chart 400, and RGB of the reference patch for white LED adjustment A value is acquired (step S2).

  Next, the colorimetric value calculation unit 531 determines whether the value of G is X ± a [digit] (step S3). In addition, you may adjust by the value of R or B instead of G.

  If the colorimetric value calculation unit 531 determines that the value of G is not X ± a [digit] (No in step S3), the PWM duty is set to A = A + 1 [when the value of G is smaller than X ± a [digit]. %] And when the value of G is greater than X ± a [digit], the PWM duty is set to A = A−1 [%] (step S4), and the process returns to step S2.

  If the colorimetric value calculation unit 531 determines that the value of G is X ± a [digit] (Yes in step S3), the process proceeds to step S5.

  As described above, the light amount adjustment of the white LED 426a is completed by the processing in steps S1 to S4.

  Next, the colorimetric value calculation unit 531 turns off the white LED 426a, turns on only the UV LED 426b with PWM Duty B [%] (step S5), images the reference chart 400, and RGB values of the reference patch for UV LED adjustment Is acquired (step S6).

  Next, the colorimetric value calculation unit 531 determines whether the value of G is Y ± b [digit] (step S7). In addition, you may adjust by the value of R or B instead of G.

  If the colorimetric value calculation unit 531 determines that the G value is not Y ± b [digit] (No in step S7), the PWM duty is set to B = B + 1 [ %] And when the value of G is larger than Y ± b [digit], the PWM duty is set to B = B−1 [%] (step S8), and the process returns to step S6.

  If the colorimetric value calculation unit 531 determines that the value of G is Y ± b [digit] (Yes in step S7), the process proceeds to step S9.

  As described above, the light amount adjustment of the UV LED 426b is completed by the processing in steps S5 to S8.

  In addition, the peak of the light amount of the UV LED 426b is set to about half or less of the peak of the white LED 426a near 400 nm to 500 nm. This is because the balance of the ultraviolet light with respect to the white light is set to D65 to prevent the fluorescent material from being fluorescent. Thereby, the accuracy of colorimetry can be improved.

  Next, the colorimetric value calculation unit 531 turns on the white LED 426a with the light amount adjusted in steps S1 to S4 (step S9). Thereby, both the white LED 426a and the UV LED 426b are turned on.

  Subsequently, the colorimetric value calculation unit 531 captures the reference chart and acquires the RGB value of the white balance / γ correction reference patch (step S10).

  Next, the colorimetric value calculation unit 531 determines whether the R value is Rd ± c [digit], the G value is Gd ± c [digit], or the B value is Bd ± c [digit]. Determination is made (step S11).

  When the R value is Rd ± c [digit], the G value is Gd ± c [digit], and the B value is not Bd ± c [digit] (No in step S11), the colorimetric value calculation unit 531 performs white balance / γ The adjustment is executed (step S12), and the process returns to step S10.

  On the other hand, when the R value is Rd ± c [digit], the G value is Gd ± c [digit], and the B value is Bd ± c [digit] (Yes in step S11), the colorimetric value calculation unit 531 performs processing. Exit.

  As described above, the adjustment of the white balance and γ correction of the image sensor is completed by the processes of steps S9 to S12.

  Next, the white LED 426a and the UV LED 426b are turned on with the light amount adjusted in steps S4 and S8, and the color measurement target is imaged. The captured RGB values of the colorimetric object are corrected with the white and γ correction values set by the processes of steps S9 to S12, and are output as the colorimetric object RsGsBs (step S13).

  Then, the colorimetric value is calculated by the colorimetric method described above (step S14).

  Thus, according to the present embodiment, an optical sensor device that can be used for accurate colorimetry can be provided at a lower cost.

  In the present embodiment, the white LED adjustment reference patch for the white LED 426a and the UV LED adjustment reference patch for the UV LED 426b are used when adjusting the LED light amount and sensor sensitivity (white balance, γ correction). However, the present invention is not limited to this, and the threshold may be changed using the same patch.

(Second Embodiment)
Next, a second embodiment will be described.

  In the image forming apparatus 100 of the second embodiment, the imaging unit is different from that of the first embodiment. Hereinafter, in the description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted, and different parts from the first embodiment will be described.

  Here, FIG. 13 is a longitudinal sectional view of the imaging unit 42F according to the second embodiment, and is a sectional view at the same position as the longitudinal sectional view of the imaging unit 42 shown in FIG. 4-1.

  In the imaging unit 42F according to the second embodiment, an optical path length changing member 440 is disposed inside the housing 421. The optical path length changing member 440 is an optical element having a refractive index n (n is an arbitrary number) that transmits light. The optical path length changing member 440 is disposed in the optical path between the subject (patch image 200) outside the housing 421 and the sensor unit 430, and the imaging surface of the optical image of the subject (patch image 200) is the reference chart 400. It has a function to bring the optical image closer to the image plane. In other words, in the imaging unit 42F according to the second embodiment, the optical path length changing member 440 is arranged in the optical path between the subject (patch image 200) and the sensor unit 430, so that the subject outside the casing 421 is located. The imaging surface of the optical image of (patch image 200) and the imaging surface of the reference chart 400 inside the housing 421 are both matched with the sensor surface of the two-dimensional image sensor 431 of the sensor unit 430. Although FIG. 13 illustrates an example in which the optical path length changing member 440 is placed on the bottom surface portion 421a of the housing 421, the optical path length changing member 440 does not necessarily have to be placed on the bottom surface portion 421a. It is only necessary to be disposed in the optical path between the subject (patch image 200) outside the housing 421 and the sensor unit 430.

When light passes through the optical path length changing member 440, the optical path length is extended according to the refractive index n of the optical path length changing member 440, and the image appears to float. The image floating amount C can be obtained by the following equation, where Lp is the length of the optical path length changing member 440 in the optical axis direction.
C = Lp (1-1 / n)

When the distance between the principal point of the imaging lens 432 of the sensor unit 430 and the reference chart 400 is Lc, the front focal plane of the optical image transmitted through the principal point of the imaging lens 432 and the optical path length changing member 440 ( The distance L to the imaging surface can be obtained by the following equation.
L = Lc + Lp (1-1 / n)

  Here, when the refractive index n of the optical path length changing member 440 is 1.5, L = Lc + Lp (1/3), and the optical path length of the optical image transmitted through the optical path length changing member 440 is set to the optical path length changing member 440. The length can be increased by about 1/3 of the length Lp in the optical axis direction. In this case, for example, if Lp = 9 [mm], L = Lc + 3 [mm], so the difference between the distance from the sensor unit 430 to the reference chart 400 and the distance to the subject (patch image 200) is 3 mm. In this state, the sensor unit includes both the rear focal plane (imaging plane) of the optical image of the reference chart 400 and the rear focal plane (imaging plane) of the optical image of the subject (patch image 200). It can be matched with the sensor surface of the two-dimensional image sensor 431 of 430.

  In the imaging unit 42F according to the second embodiment configured as described above, the optical path length changing member 440 is disposed in the optical path between the subject (patch image 200) and the sensor unit 430, so that the subject ( Since the image plane of the optical image of the patch image 200) is brought close to the image plane of the optical image of the reference chart 400, an appropriate image focused on both the subject (patch image 200) and the reference chart 400. Can be imaged.

(Third embodiment)
Next, a third embodiment will be described.

  The image forming apparatus 100 according to the third embodiment is different from the first embodiment in that a reflective colorimetric sensor is provided instead of the two-dimensional image sensor 431. Hereinafter, in the description of the third embodiment, the description of the same parts as those of the first embodiment will be omitted, and different parts from the first embodiment will be described.

  FIG. 14 is a diagram illustrating a configuration of a reflective colorimetric sensor 500 according to the third embodiment. FIG. 14A is a side view, and FIG. 14B is a rear view. As shown in FIG. 14, the reflection type colorimetric sensor 500 has a plurality of light receiving elements 502, 503, and 504 having different spectral sensitivities on a printed board 501. In the example shown in FIG. 14, three light receiving elements 502, 503, and 504 having RGB sensitivities are arranged, but light receiving elements having other spectral sensitivities such as gray, cyan, and orange are also combined. It may be arranged.

  In the reflective colorimetric sensor 500, a light emitting element 505a and a light emitting element 505b are disposed in the vicinity of the light receiving elements 502, 503, and 504. The light emitting element 505a of the present embodiment is the white LED 426a described in the first embodiment. The light emitting element 505b is the white LED 426b described in the first embodiment.

  The reflection type colorimetric sensor 500 includes a light shielding wall 506 for preventing stray light around the light receiving elements 502, 503, and 504 and the light emitting elements 505a and 505b.

  Light emitted from the light emitting elements 505a and 505b hits the patch image 200 and the reference chart 400 to be colorimetrically measured, and irregularly reflected light or regular reflected light is uniformly incident on the light receiving elements 502, 503, and 504.

  The light receiving elements 502, 503, and 504 output RGB signals corresponding to the amount of received light, are amplified by an amplifier, and are converted into digital values by an AD converter. Also in this example, the light emitting element 505a and the light emitting element 505b are sequentially turned on, and PWM duty setting, white balance, and γ correction value adjustment are performed. In this case, the apparatus has a known standard, and the light emitting element 505a and the light emitting element 505b are sequentially turned on to make the above adjustment.

  Thus, according to the present embodiment, an optical sensor device that can be used for accurate color measurement can be provided at a lower cost.

(Fourth embodiment)
Next, a fourth embodiment will be described.

  The image forming apparatus 100 according to the fourth embodiment is capable of discriminating the paper type even when the fluorescent whitening agent is included in the paper to be printed. Different from the embodiment. Hereinafter, in the description of the third embodiment, the description of the same parts as those of the first embodiment will be omitted, and different parts from the first embodiment will be described.

  2. Description of the Related Art Conventionally, a technique for imaging a paper to be printed and determining a paper type is known. However, according to the prior art, if a fluorescent whitening agent is included in the paper to be printed, there is a problem that the paper type cannot be accurately determined because of the influence of fluorescence.

  Here, FIG. 15 is a diagram showing a photographed image for each paper type according to the fourth embodiment. FIG. 15A shows a photographed image for each paper type when the white LED 426a is lit, and FIG. 15B shows a photographed image for each paper type when the UV LED 426b is lit. 15 (a) and 15 (b), (1) is a photographed image of a paper (paper type A) on which nanoporous coating has been applied, and (2) is a paper (paper type) using grid-like glue. A photographed image of B), (3) is a photographed image of a sheet of vinyl chloride film (paper type C), and (4) is a photographed image of a sheet of paper (paper type D).

  As shown in FIG. 15A, regarding the photographed image when the white LED 426a is lit, there is no large difference in RGB level even for paper containing a large amount of fluorescent whitening agent. On the other hand, as shown in FIG. 15B, with respect to the photographed image when the UV LED 426b is turned on, the reflectance of the reflected light received by the two-dimensional image sensor 431 varies depending on the amount of fluorescent whitening agent applied. A difference appears in the level.

  Therefore, the colorimetric value calculation unit 531 in the image forming apparatus 100 according to the present embodiment stores in advance the RGB values of the paper containing the fluorescent whitening agent imaged when the UV LED 426b is turned on, and the UV LED 426b The paper type is determined by comparing the RGB value of the captured image of the determination object (paper) with the RGB value stored in advance.

  Here, FIG. 16 is a diagram illustrating an example of a table T of RGB values for each paper type. FIG. 16 shows a table of RGB values for four different types of paper. The RGB value table T for each paper type is stored in, for example, the non-volatile memory 60, and stores in advance the RGB values for each paper type including the fluorescent whitening agent imaged when the UV LED 426b is turned on.

  The colorimetric value calculation unit 531 of the colorimetry control unit 50 compares the RGB value of the image captured by the UV LED 426b with the RGB value table T for each paper type after imaging the discrimination target (paper). By discriminating the paper type depending on the paper type range, it is possible to discriminate the paper type even if the discriminating object (paper) contains a fluorescent brightener.

  Next, the flow of the paper type discrimination process will be described.

  FIG. 17 is a flowchart schematically showing the flow of the paper type discrimination process. The paper type determination process is executed after the light amount adjustment of the UV LED 426b in the colorimetry control unit 50. Note that the light amount adjustment of the UV LED 426b has been described with reference to FIG.

  As illustrated in FIG. 17, the colorimetric value calculation unit 531 first captures an image of a sheet with the two-dimensional image sensor 431 of the sensor unit 430 using the UV LED 426b (step S31).

  Next, the colorimetric value calculation unit 531 acquires the RGB value of the paper from the captured image (step S32).

  Next, the colorimetric value calculation unit 531 compares the B value of the acquired RGB values with the table T of RGB values based on the paper type (step S33). Note that the G value or the R value may be compared with the table T of RGB values by paper type.

  Next, the colorimetric value calculation unit 531 selects the closest B value from the comparison result in step S33, and determines the paper type (step S34).

  Next, pre-processing for color measurement using the paper type discrimination process will be described.

  Here, FIG. 18 is a flowchart showing the flow of colorimetric preprocessing using the paper type discrimination process. As shown in FIG. 18, the colorimetric value calculation unit 531 first stores the result of color measurement performed by the spectroscope for each paper type in the storage area (step S41).

  Next, the colorimetric value calculation unit 531 measures the color with the white LED 426a and the UV LED 426b for each paper type, and acquires RGB values (step S42).

  Next, the colorimetric value calculation unit 531 stores the acquired RGB values in association with the colorimetric results of the spectroscope in the RGB value table T for each paper type (step S43).

  Next, the colorimetric value calculation unit 531 calculates a reference value linear conversion matrix for a pair of RGB values and XYZ values that are reference colorimetric values stored in the RGB value table T by paper type (step S44). ).

  The colorimetric value calculation unit 531 performs the colorimetry process shown in FIG. 10 and the colorimetry process shown in FIG. 11 using the calculated reference value linear conversion matrix.

  By performing the processing in this manner, the reference value linear conversion matrix is determined for each paper type, so that it is possible to calculate the colorimetric value with higher accuracy than when the paper type is not discriminated.

  As described above, according to the present embodiment, after imaging a discrimination target (paper), the RGB value of the image photographed by the UV LED 426b is compared with the RGB value table T for each paper type to determine which paper type. By discriminating the paper type depending on the range, it is possible to discriminate the paper type even if the discriminating object (paper) contains a fluorescent brightening agent.

6 Image output means 42 Optical sensor device 42, 50 Color measurement device 45 Correction unit 55 First light amount adjustment unit, second light amount adjustment unit 100 Image forming device 400 Reference chart 426a First light source 426b Second light source 431 Sensor 531 Calculation Part

JP2013-007610A

Claims (8)

A first light source having a plurality of peak wavelengths in a wavelength range of 400 nm to 780 nm;
A second light source capable of emitting ultraviolet light;
A sensor that receives light reflected by the object irradiated by the first light source or the second light source;
A first light amount adjusting unit that adjusts a light amount of the first light source from an output of the sensor in a state where the first light source is turned on and the second light source is turned off;
A second light amount adjustment unit that adjusts the light amount of the second light source from the output of the sensor in a state where the second light source is turned on and the first light source is turned off;
A correction unit that acquires a correction value of data output from the sensor from the output of the sensor in a state in which the first light source and the second light source are turned on with the adjusted light amount;
An optical sensor device comprising: The first light amount adjustment unit adjusts the light amount of the first light source using any value of R, G, and B output from the sensor.
The optical sensor device according to claim 1. The second light amount adjustment unit adjusts the light amount of the second light source by using any value of R, G, and B output from the sensor.
The optical sensor device according to claim 1. The correction unit adjusts white balance and γ correction based on the correction value of the data.
The optical sensor device according to claim 1. An optical sensor device according to any one of claims 1 to 4,
A reference chart imaged by the optical sensor device together with a subject;
A calculation unit that calculates a colorimetric value of the subject based on the subject imaged by the optical sensor device and imaging data of the reference chart;
A colorimetric device comprising: The calculation unit includes:
A memory table that stores in advance RGB values for each type of object obtained from the sensor photographed by the second light source;
According to the comparison result between the RGB value obtained from the sensor photographed by the second light source and the value of the memory table, the type of the object is determined.
The colorimetric apparatus according to claim 5. The calculation unit calculates a reference value linear transformation matrix for a pair of the determined RGB value and reference colorimetric value of the object;
The colorimetric apparatus according to claim 6. Image output means for outputting an image to a recording medium;
A colorimetric device according to any one of claims 5 to 7,
With
The colorimetric device calculates a colorimetric value of the image output from the image output unit as the subject,
The image output means outputs an image based on image data color-adjusted using the colorimetric value after the colorimetric device calculates the colorimetric value.
An image forming apparatus.