JP5717052B2 - Spectroscopic measurement apparatus, image evaluation apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to a spectroscopic measurement apparatus, an image evaluation apparatus, and an image forming apparatus, and more specifically, a spectroscopic measurement apparatus that measures a wavelength spectrum of reflected light, an image evaluation apparatus including the spectroscopic measurement apparatus, and the image evaluation apparatus. The present invention relates to an image forming apparatus.

  In recent years, in the field of production printing, digitization has progressed, and electrophotographic image forming apparatuses, inkjet image forming apparatuses, and the like have been put on the market.

  There is an increasing demand for high image quality for these image forming apparatuses, and color tone management such as color stability and color reproducibility in the image forming apparatus has become important.

  Therefore, it has been considered to measure the color of an image formed by the image forming apparatus using a spectrometer and perform color correction based on the measurement result.

  For example, Patent Document 1 discloses a spectral characteristic measuring apparatus that takes wavelength shift into consideration. Patent Document 2 discloses a spectral characteristic acquisition device that constitutes a spectral sensor array in which a plurality of spectral sensors are arranged in one direction.

  By the way, in the case of a measurement object whose spectral reflectance distribution changes relatively comparatively like an image formed by an image forming apparatus, a spectrometer that outputs a relatively small number of light intensity signals of about 3 to 16 is used. A so-called multiband spectroscopic method for estimating the spectral reflectance from the light intensity signal can be used (see, for example, Non-Patent Document 1). This method has the advantage that the measurement time is relatively short because the number of light intensity signals to be detected is smaller than that of a conventional spectroscope, and high-speed measurement is possible, such as in-line measurement of a printed image on an image forming apparatus. Suitable for required fields.

  However, in the spectral characteristic measuring apparatus disclosed in Patent Document 1, it is difficult to obtain high measurement accuracy when the multiband spectroscopy method is used.

  Further, in the spectral characteristic acquisition device disclosed in Patent Document 2, if the wavelength distribution of light acquired by each pixel of the light receiving element is shifted due to a change with time, a change in environmental temperature, a heat generation of the light source, etc., the measurement accuracy There was a risk of lowering.

From a first viewpoint, the present invention is a spectroscopic measurement device that measures a wavelength spectrum of reflected light from a relatively moving object, and includes a light source that irradiates the object with light, and an opening. An aperture member disposed on an optical path of reflected light from the object, an imaging optical system that collects the reflected light that has passed through the aperture of the aperture member, and the imaging optical system A diffractive member disposed on the optical path of the reflected light, diffracting the reflected light, a light receiving element having a plurality of light receiving regions for receiving first-order diffracted light from the diffractive member, and a relative relationship of the light receiving element with respect to the opening member A position shift detection device for detecting a position shift amount from a reference position of the position, and a plurality of conversion matrices used when estimating the wavelength spectrum from the output signal of the light receiving element, the plurality of conversion matrices Refer to the above And a processing apparatus for obtaining an appropriate transformation matrix based on the detection result of the device, the plurality of conversion matrices, correspond to a plurality of different positional deviation amount from each other,
The processing device selects two conversion matrices from the plurality of conversion matrices according to the amount of positional deviation detected by the positional deviation detection device, and interpolates the two conversion matrices to perform the appropriate conversion. is a spectroscopic measuring device you and acquires the matrix.

  According to a second aspect of the present invention, there is provided an image evaluation apparatus that evaluates the color of an image, wherein the spectral measurement apparatus of the present invention and an evaluation that evaluates the color of the image based on a measurement result of the spectral measurement apparatus And an image evaluation apparatus.

  According to a third aspect of the present invention, in an image forming apparatus for forming an image under an image forming condition corresponding to image information, the image evaluation apparatus according to the present invention and the image evaluation apparatus based on the evaluation result of the image evaluation apparatus. An image forming apparatus comprising: an adjusting device that adjusts a forming condition.

  According to the spectroscopic measurement apparatus of the present invention, a highly accurate measurement result can be stably obtained using a multiband spectroscopic method.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. It is a figure for demonstrating an image evaluation apparatus. It is FIG. (1) for demonstrating a spectroscopic measurement apparatus. It is FIG. (2) for demonstrating a spectroscopic measurement apparatus. It is a figure for demonstrating a microlens array. It is a figure for demonstrating an opening member. It is a figure for demonstrating the positional relationship of a microlens array and an opening member. It is FIG. (1) for demonstrating an imaging optical system. FIG. 6 is a second diagram for explaining the imaging optical system; It is a figure for demonstrating a diffraction element. It is a figure for demonstrating a light receiver. It is a figure for demonstrating a 1st line sensor and a 2nd line sensor. It is a figure for demonstrating the diffraction direction in a diffraction element. It is a figure for demonstrating the relationship between a 1st line sensor and a + 1st order diffraction image. It is a figure for demonstrating the arrangement direction of the unevenness | corrugation in a diffraction element. It is FIG. (1) for demonstrating a spectral sensor. It is FIG. (2) for demonstrating a spectroscopic sensor. It is a figure for demonstrating a conversion matrix table. It is a block diagram for demonstrating the structure of a processing apparatus. It is a figure for demonstrating a part of data stored in the data area in ROM. It is a flowchart (the 1) for demonstrating the process performed by CPU in the case of image evaluation. It is a flowchart (the 2) for demonstrating the process performed by CPU in the case of image evaluation. It is a flowchart (the 3) for demonstrating the process performed by CPU in the case of image evaluation. It is a figure for demonstrating the amount of position shift. It is a figure for demonstrating the relationship between a positional offset amount and the position regarding an X-axis direction. It is a figure for demonstrating the modification 1 of a light receiver. FIGS. 27A and 27B are diagrams for explaining the relationship between the zero-order light and the semiconductor position sensor in the light receiver of the first modification. FIG. 27B is a diagram for describing a method for acquiring a positional deviation amount at a position where a semiconductor position sensor is not provided in the case of FIG. It is a figure for demonstrating the modification of a spectroscopic measurement apparatus. It is a flowchart for demonstrating the calibration process of the conversion matrix performed by CPU in the spectroscopic measurement apparatus of FIG. It is a figure for demonstrating the light receiver in the spectroscopic measurement apparatus of FIG. It is a figure for demonstrating the modification 1 of an image evaluation apparatus. It is a figure for demonstrating the light receiving element in the image evaluation apparatus of FIG. It is a flowchart for demonstrating the image evaluation process performed by CPU in the image evaluation apparatus of FIG. It is a figure for demonstrating the modification of the light receiving element in the image evaluation apparatus of FIG. It is a figure for demonstrating the modification 2 of an image evaluation apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 as an image forming apparatus according to an embodiment.

  The color printer 2000 is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010, four photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), 4 Toner cartridges (2034a, 2034b, 2034c, 2034d), transfer belt 2040, transfer roller 2042, fixing device 2050, paper feed roller 2054, registration roller pair 2056, paper discharge roller 2058, paper feed tray 2 60, the discharge tray 2070, a communication control device 2080, an image evaluation apparatus 2245 includes the paper detection sensor 2246, temperature and humidity sensor (not shown), and a printer control unit 2090 for centrally controlling the above units.

  In the following description, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction of each photosensitive drum is defined as the X-axis direction, and the direction along the arrangement direction of the four photosensitive drums is defined as the Z-axis direction.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog data An AD conversion circuit for converting the signal into digital data. Then, the printer control device 2090 notifies the optical scanning device 2010 of multi-color image information (black image information, cyan image information, magenta image information, yellow image information) received from the host device via the communication control device 2080. To do.

  The temperature / humidity sensor detects the temperature and humidity in the color printer 2000 and notifies the printer controller 2090 of it.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a are used as a set and form an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image. Configure.

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, the toner cartridge 2034b, and the cleaning unit 2031b are used as a set and form an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image. Configure.

  The photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, the toner cartridge 2034c, and the cleaning unit 2031c are used as a set, and form an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image. Configure.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, the toner cartridge 2034d, and the cleaning unit 2031d are used as a set, and form an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image. Configure.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010 includes four light sources, a pre-deflector optical system, an optical deflector, a scanning optical system, and a scanning control device. The optical scanning device 2010 scans the surface of the corresponding charged photosensitive drum with a plurality of light beams modulated for each color based on multicolor image information from the printer control device 2090. As a result, on the surface of each photoconductive drum, the charge disappears only in the portion irradiated with light, and a latent image corresponding to the image information is formed on the surface of each photoconductive drum. The latent image formed here moves in the direction of the corresponding developing roller as the photosensitive drum rotates.

  As each developing roller rotates, the toner from the corresponding toner cartridge is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing, and are superimposed to form a color image.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060, and the paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060 and conveys it to the registration roller pair 2056. The registration roller pair 2056 feeds the recording paper toward the gap between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the color image on the transfer belt 2040 is transferred to the recording paper. The recording sheet transferred here is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. The recording paper fixed here is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  The paper detection sensor 2246 is disposed in the vicinity of the recording paper conveyance path between the fixing device 2050 and the image evaluation device 2245, and detects the leading edge and the trailing edge of the recording paper.

  The image evaluation device 2245 is disposed in the vicinity of the conveyance path of the recording paper that has passed through the fixing device 2050, and evaluates the quality of the image on the recording paper. The evaluation result of the image evaluation device 2245 is notified to the printer control device 2090.

  As shown in FIG. 2 as an example, the image evaluation device 2245 is arranged on the + Z side of the recording paper P, and includes three spectroscopic measurement devices (10_1, 10_2, 10_3), the processing device 20, and the like. Here, the toner image is fixed on the surface of the recording paper P on the + Z side, and the surface of the recording paper P on which the toner image is fixed is also referred to as “front surface”.

  The three spectroscopic measurement devices (10_1, 10_2, 10_3) are arranged along the X-axis direction.

  The three spectroscopic measurement devices (10_1, 10_2, 10_3) have the same configuration, and when it is not necessary to distinguish them, they are collectively referred to as the spectroscopic measurement device 10.

  As shown in FIG. 3 and FIG. 4 as an example, the spectroscopic measurement apparatus 10 includes a light source unit 11 (not shown in FIG. 3), a microlens array 12, an aperture member 13, an imaging optical system 14, a diffraction element 15, and It has a light receiver 16 and the like.

  The light source unit 11 is disposed on the −Y side of the microlens array 12 and the opening member 13 with respect to the Y-axis direction.

  The light source unit 11 includes an LED array 11a and a collimating lens array 11b.

  The LED array 11a has a plurality of LEDs (Light Emitting Diodes) arranged along the X-axis direction. Each LED emits white light having light intensity in almost all visible light. Each LED is turned on and off by the processing device 20.

  Instead of the LED array, a fluorescent lamp such as a cold cathode tube or a lamp light source can be used. In short, it is preferable that the light source emits light in a wavelength region necessary for spectroscopic measurement and can be illuminated uniformly over the entire measurement region.

  The collimating lens array 11b has a plurality of collimating lenses corresponding to a plurality of LEDs. The plurality of collimating lenses are arranged on the optical path of white light emitted from the corresponding LED, and the white light is converted into parallel light. Light passing through the collimating lens array 11b illuminates the front surface of the recording paper P. That is, the light source unit 11 emits linear illumination light whose longitudinal direction is the X-axis direction.

  Here, the white light from the light source unit 11 is set so as to be obliquely incident on the front surface of the recording paper P in the YZ plane (see FIG. 4). Specifically, illumination light is incident from a direction at an angle of about 45 degrees with respect to the front surface of the recording paper P, and light diffusely reflected in a direction orthogonal to the front surface of the recording paper P is received. This is a so-called 45/0 optical system. Note that the present invention is not limited to this 45/0 optical system. For example, illumination light is incident from a direction orthogonal to the front surface of the recording paper P, and light diffusely reflected in a direction of about 45 degrees is reflected. A so-called 0/45 optical system that receives light may be used.

  The microlens array 12 is disposed on the optical path of light diffusely reflected by the front surface of the recording paper P. Hereinafter, light diffusely reflected by the front surface of the recording paper P is simply referred to as “reflected light”.

  As shown in FIG. 5 as an example, this microlens array has a plurality of microlenses arranged along the X-axis direction. The distance between the centers of two microlenses adjacent to each other in the X-axis direction is referred to as “lens pitch LP”. Each microlens collects the incident reflected light.

  The opening member 13 is disposed on the optical path of the reflected light that passes through the microlens array 12.

  As shown in FIG. 6 as an example, the opening member 13 has a plurality of openings arranged along the X-axis direction. The distance between the centers of two openings adjacent to each other in the X-axis direction is referred to as “opening pitch AP”.

  Each opening may be either a pinhole or a slit. Further, the shape of the opening is not limited to a circle and a rectangle, but may be an ellipse or other shapes.

  Further, as the opening member 13, a blackened metal plate having a plurality of holes or a glass plate in which a black member (for example, chromium or carbon-containing resin) is applied in a predetermined shape is used. be able to.

  Each opening of the opening member 13 is located in the vicinity of the light collection position of the reflected light through the microlens array 12 (see FIG. 7).

  The imaging optical system 14 includes a plurality of condenser lenses (here, two condenser lenses), and is disposed on the + Z side of the aperture member 13.

  The imaging optical system 14 condenses the reflected lights that have passed through the plurality of apertures of the aperture member 13 at different positions in the X-axis direction (see FIGS. 8 and 9).

  As the imaging optical system 14, it is possible to use a lens used in a general scanner optical system or a line sensor lens used industrially. Here, as an example, a commercially available lens for a line sensor (ML-L02035, manufactured by Moritex Corporation) was used. This line sensor lens has a magnification of 0.2, and can form an image of about 300 mm in a range of 60 mm.

  The diffraction element 15 is disposed on the + Z side of the imaging optical system 14. As an example, the diffraction element 15 is a grating in which sawtooth-shaped irregularities are formed on the surface on the + Z side of a transparent substrate, as shown in FIG. The distance between the centers of two concavities and convexities adjacent to each other is referred to as “lattice pitch GP”.

When the incident angle of the reflected light to the diffraction element 15 is α and the diffraction order is m, the light of wavelength λ included in the reflected light is diffracted at an angle θ _m expressed by the following equation (1).

sin θ _m = mλ / GP + sin α (1)

  When the unevenness of the grating has a sawtooth shape, the light intensity of the + 1st order diffracted light can be increased. The irregularities of the grating may be stepped.

  Thus, the light diffracted by the diffraction element 15 travels in different directions depending on the wavelength. That is, the reflected light is subjected to wavelength spectroscopy by the diffraction element 15. In the following, an assembly of + 1st order diffracted light of reflected light that has passed through one aperture is referred to as “+ 1st order diffracted image”, and when there is no need to distinguish diffraction orders, it is also simply referred to as “diffracted image”.

  As illustrated in FIG. 11 as an example, the light receiver 16 includes a first line sensor 16_1 and a second line sensor 16_2. Each line sensor has a plurality of light receiving regions arranged along the X-axis direction.

  As an example, as shown in FIG. 12, the first line sensor 16_1 is disposed at a position for receiving the + 1st order diffraction image from the diffraction element 15, and the second line sensor 16_2 receives the 0th order light from the diffraction element 15. It is arranged at the position to receive light. Each light receiving region outputs a signal corresponding to the amount of received light to the processing device 20.

  Hereinafter, each light receiving region of the first line sensor 16_1 is also referred to as a “pixel”. Further, the distance between the centers of two adjacent pixels in the X-axis direction is referred to as “pixel pitch d”. Here, in the second line sensor 16_2, the distance between the centers of two adjacent light receiving regions in the X-axis direction is the same as the pixel pitch d.

  By the way, if the arrangement direction of the unevenness in the diffraction element 15 is parallel to the arrangement direction of the plurality of light receiving regions in the first line sensor 16_1 (here, the same as the X-axis direction), the zero-order light, ± second-order diffracted light, In addition, the diffracted light of the reflected light that has passed through the adjacent openings in the opening member 13 may overlap on the light receiver 16, making accurate spectral measurement difficult.

  Therefore, in this embodiment, the arrangement direction of the unevenness in the diffraction element 15 is inclined with respect to the arrangement direction of the plurality of light receiving regions in the first line sensor 16_1.

  The imaging position on the light receiver 16 of the light of each wavelength separated by the diffraction element 15 can be derived from L × tan θm using the distance L between the diffraction element 15 and the light receiver 16 in the Z-axis direction. In addition, since the size of the diffraction image on the light receiver 16 is determined by the magnification of the imaging optical system 14, when a white light diffraction image is received, the width j of the diffraction image (see FIG. 13) can be obtained. it can.

In general, the length c (see FIG. 14) in the X-axis direction and the length (height) h (see FIG. 14) in the Y-axis direction of one light receiving region are determined by the line sensor. Therefore, the number n of light receiving regions necessary to receive one diffraction image (here, the + 1st order diffraction image) without excess or deficiency is determined from the aperture pitch AP in the aperture member 13 and the magnification of the imaging optical system 14. it can. At this time, the value of tan ⁻¹ (h / (n × c)) is the inclination angle θ (see FIG. 15) with respect to the X-axis direction in the XY plane of the unevenness in the diffraction element 15.

  That is, the diffraction image is received by the first line sensor 16_1 in a state where the diffraction direction is inclined at an angle θ with respect to the X-axis direction in the XY plane.

  For example, when the pixel pitch d is 10 μm, the grating pitch GP is 10 μm, and the distance L is 2 mm, the reflected light that has passed through one opening of the opening member 13 corresponds to the wavelength as shown in FIG. 16 as an example. Are received by six pixels. In this case, one spectroscopic sensor is composed of six pixels.

  Therefore, as shown in FIG. 17 as an example, the light receiver 16 is an assembly of a plurality of spectral sensors, and diffracted light of reflected light that has passed through different openings is incident on each spectral sensor. The plurality of spectral sensors correspond to a plurality of measurement positions on the recording paper P in the X-axis direction.

  In the following, the wavelength band of light received by one pixel is referred to as “band”, and the splitting of light into a plurality of bands is also referred to as “multiband spectroscopy”. Therefore, the number of bands in one spectroscopic sensor is the same as the number of pixels constituting one spectroscopic sensor. Further, the relationship between the wavelength and the light intensity (or reflectance) of the reflected light that has passed through one opening is also referred to as “reflected light wavelength spectrum”.

  In multiband spectroscopy, the reflected light wavelength spectrum can be obtained with higher accuracy as the number of bands increases. However, since the number of pixels in the first line sensor 16_1 is constant, when the number of bands increases, the number of pixels used in one spectroscopic sensor increases, the number of spectroscopic sensors decreases, and the number of measurement points decreases. .

  Therefore, in this embodiment, the number of bands is minimized, and the reflected light wavelength spectrum is estimated by an estimation means such as Wiener estimation. There are many methods that can be used for estimation of the reflected light wavelength spectrum (for example, see “Analysis and Evaluation of Digital Color Images”, University of Tokyo Press, p.154-p.157).

  Here, an example of a method for estimating the reflected light wavelength spectrum from the output signal of one spectroscopic sensor will be described. One spectroscopic sensor is assumed to have N pixels. Here, as a reflected light wavelength spectrum, a predetermined wavelength band (for example, 400 to 700 [nm]) is divided by a predetermined wavelength pitch (for example, 10 [nm]), and the reflectance is calculated. And

  A row vector r in which each reflectance is stored is represented by the following equation (2), where v is a row vector in which output signals vi (i = 1 to N) of N pixels are stored and G is a transformation matrix. Can be expressed as

r = Gv (2)

  The transformation matrix G is a matrix R (= [r1, r2] in which n row vectors (r1, r2,..., Rn) of n samples with known reflected light wavelength spectra are stored. ,..., Rn]) and n row vectors (v1, v2,..., Vn) obtained when the same n samples are measured by the same spectroscopic measurement apparatus as in this embodiment. G when the square norm of the error of R-GV is minimized using the matrix V (= [v1, v2,..., Vn]).

  At this time, in general, the regression coefficient matrix G of the regression equation from V to R, where V is an explanatory variable and R is an objective variable, is a Moore-Penrose generalized inverse matrix that gives the above-mentioned least square norm solution of the matrix V Can be calculated from the following equation (3) (see Non-Patent Document 1, for example).

G = RV ^T (VV ^T ) ⁻¹ (3)

  In the above equation (3), the superscript T represents the transpose of the matrix, and the superscript -1 represents the inverse matrix. The regression coefficient matrix G calculated from the above equation (3) is defined as a conversion matrix G.

Here, for each spectroscopic measurement device, the position of the opening of the opening member 13 is moved a plurality of times in the X-axis direction for each spectroscopic sensor, and a plurality of conversion matrices are created in advance. For example, the aperture member 13 is moved a plurality of times in the X-axis direction so that the image of the aperture received by the first line sensor 16_1 moves by d / M using the pixel pitch d and the integer M. A transformation matrix (G _{1 to} G _M ) is created.

  As the value of M is larger, measurement with a smaller error with respect to the positional deviation amount is possible, but the storage capacity of the processing device 20 needs to be increased. Therefore, the number M of transformation matrices may be set according to the application.

  The M conversion matrices are expressed in a table format for each spectroscopic measurement device and for each spectroscopic sensor, corresponding to the relative positional deviation amount (the positional deviation amount with respect to the reference position) of the first line sensor 16_1 with respect to the opening position. The conversion matrix table (see FIG. 18) is stored in the ROM 23 (see FIG. 19) of the processing device 20.

  The processing device 20 performs an image evaluation process in response to an instruction from the printer control device 2090. As shown in FIG. 19 as an example, the processing device 20 includes an input / output control circuit 21, a CPU 22, a ROM 23, a RAM 24, a light source driving circuit 26, and the like.

  The input / output control circuit 21 controls data exchange with the printer control device 2090. For example, when there is a request for image evaluation from the printer control device 2090, the input / output control circuit 21 notifies the CPU 22 of the request. In addition, when the CPU 22 receives an evaluation completion notification from the CPU 22, the input / output control circuit 21 outputs the evaluation result stored in the RAM 24 to the printer control device 2090.

  The ROM 23 is a rewritable ROM and has a program area and a data area. In the program area, a program described in a code readable by the CPU 22 is stored. The data area stores various data used when executing the program (see FIG. 20).

  The RAM 24 is a working memory.

  The light source driving circuit 26 turns on / off the LED array 11a in accordance with an instruction from the CPU 22.

  The printer control device 2090 is (1) when the power is turned on, (2) when the temperature in the device changes by 10 ° C. or more, (3) when the relative humidity in the device changes by 50% or more, (4) When the number of printed sheets reaches a predetermined number, (5) When the number of rotations of the developing roller reaches a predetermined number, (6) When the travel distance of the transfer belt reaches a predetermined distance, (7) Not shown Image process control is performed when requested from the operation panel.

  In this image process control, the printer control device 2090 requests the image evaluation device 2245 to perform image evaluation.

The printer control unit 2090, the (1) when the power is turned on, and (7) when requested by the not shown operation panel is set to 1 in the calibration request flag f _A.

  Here, the image evaluation process performed by the processing device 20 will be described. The flowcharts of FIGS. 21 to 23 correspond to a series of processing algorithms executed by the CPU 22 during the image evaluation process.

  The output signal of the paper detection sensor 2246 is periodically monitored by timer interrupt processing. When the leading edge and the trailing edge of the recording paper are detected, each detection flag (leading edge detection flag, trailing edge detection flag) is set to 1. Is set.

  In the first step S401, it is determined whether or not an image evaluation request has been received from the printer control apparatus 2090. If there is no image evaluation request notification from the input / output control circuit 21, the process waits. On the other hand, if there is an image evaluation request notification from the input / output control circuit 21, the determination here is affirmed and the process proceeds to step S403.

In the next step S403, it sets 0 to the calibration flag f _B indicating whether or not it is necessary to calibrate the conversion matrix is initialized.

In the next step S405, the calibration request flag f _A determines whether it is 1. Calibration request flag f _A is not 1, this determination is negative, the process proceeds to step S409.

  In the next step S409, it is determined whether or not the elapsed time t after the previous calibration of the conversion matrix is equal to or greater than a preset calibration interval tc. The calibration interval tc is stored in the data area of the ROM 23. The elapsed time t is counted up in a timer interrupt process executed every predetermined time. If the elapsed time t is less than the calibration interval tc, the determination here is denied and the process proceeds to step S411.

  In this step S411, the current temperature is acquired from the output signal of the temperature / humidity sensor, and the difference ΔT from the temperature when the previous conversion matrix was calibrated is greater than or equal to a preset calibration temperature difference Tc. Determine whether. The calibration temperature difference Tc is stored in the data area of the ROM 23. If the temperature difference ΔT is less than the calibration temperature difference Tc, the determination here is denied and the process proceeds to step S413.

  In this step S413, it is determined whether or not the number n of prints since the previous calibration of the conversion matrix is equal to or greater than a preset number Nc of calibrations. The calibration number Nc is stored in the data area of the ROM 23. If the number n of prints is equal to or greater than the number Nc of calibrations, the determination here is affirmed, and the process proceeds to step S415.

In step S415, the calibration flag f _B, is set to 1 which means that calibration of the transformation matrix is needed.

In the next step S417, the value of the calibration flag f _B determines whether it is 1. If the value of the calibration flag f is 1, the determination here is affirmed and the process proceeds to step S419.

  In step S419, the value of the elapsed time t is reset to zero.

  In the next step S421, the value of the number of printed sheets n is reset to zero.

  In the next step S423, the current temperature is stored in the RAM 24.

  The calibration interval tc, the calibration temperature difference Tc, and the calibration number Nc can be set from an operation panel (not shown).

  In the next step S501, the printer controller 2090 is requested to stop the conveyance system.

  In the next step S503, the light source drive circuit 26 is instructed to turn on the LED array 11a of each spectroscopic measurement device.

  In the next step S505, the output signal of the second line sensor 16_2 is acquired for each spectroscopic sensor for each spectroscopic measurement device.

  In the next step S507, the positional deviation amount is obtained for each spectroscopic measurement device based on the output signal of the second line sensor 16_2 for each spectroscopic sensor. Here, as an example, as shown in FIG. 24, the barycentric position of the light intensity is calculated in the X-axis direction, and the difference from the reference position is obtained as the amount of positional deviation.

  In the next step S509, as shown in FIG. 25 as an example, the positional deviation amount and the position in the X axis direction are calculated from the plurality of positional deviation amounts obtained in step S507 and the positions in the X axis direction. Find the polynomial that represents the relationship.

  In the next step S511, each positional shift amount obtained in step S507 is corrected using the polynomial.

In the next step S513, for each spectroscopic measurement device, the conversion matrix table stored in the ROM 23 is referred to for each spectroscopic sensor, and a conversion matrix corresponding to the corrected amount of displacement is selected. For example, positional deviation amount is when the D _2, the conversion matrix G ₂ is selected. The position deviation amount when between D ₂ and D _3, and the conversion matrix G ₂ and the conversion matrix G ₃ is selected.

  In the next step S515, for the spectroscopic sensor having two conversion matrices selected in step S513, the two conversion matrices are interpolated according to the positional deviation amount. Note that nothing is done for the spectroscopic sensor having one conversion matrix selected in step S513.

  In the next step S517, the interpolated conversion matrix or the selected conversion matrix is stored in the RAM 24 for each spectroscopic sensor and for each spectroscopic sensor.

  In the next step S519, the light source driving circuit 26 is instructed to turn off the LED array 11a of each spectroscopic measurement device.

  In the next step S521, the printer controller 2090 is requested to restart the transport system.

  The processes in steps S501 to S521 are “conversion matrix calibration process”.

  In the next step S601, the printer controller 2090 is requested to create a master image for image evaluation.

  In the next step S603, the leading edge detection flag is referred to and it is determined whether or not the leading edge of the recording paper is detected. If 1 is not set in the tip detection flag, the process waits until 1 is set in the tip detection flag. On the other hand, if 1 is set in the tip detection flag, the determination here is affirmed, the tip detection flag is reset to 0, and then the process proceeds to step S605.

  In step S605, the light source drive circuit 26 is instructed to turn on the LED array 11a of each spectroscopic measurement device.

  In the next step S607, the output signal of the first line sensor 16_1 is acquired for each spectroscopic sensor for each spectroscopic measurement device. The output signal of the first line sensor 16_1 is subjected to preprocessing such as dark current correction and linearity correction.

  In the next step S609, the reflected light wavelength spectrum is estimated for each spectroscopic sensor and for each spectroscopic sensor.

  Here, the row vector v is created, the transformation matrix stored in the RAM 24 is read, the row vector v and the transformation matrix are integrated, and the row vector r is calculated. If the conversion matrix calibration process is not performed this time, the RAM 24 stores a conversion matrix obtained by the most recent conversion matrix calibration process.

  In the next step S611, the result of the estimation calculation is stored in the RAM 24 together with information on the measurement position on the recording paper for each spectroscopic sensor. The measurement position on the recording paper can be known from the recording paper conveyance speed and the elapsed time since the leading edge of the recording paper was detected with respect to the recording paper conveyance direction. Further, the width direction of the recording paper can be known from the opening position in the X-axis direction.

  In the next step S613, the trailing edge detection flag is referred to and it is determined whether or not the trailing edge of the recording sheet is detected. If 1 is not set in the rear end detection flag, the determination here is negative and the processing returns to step S607.

  Thereafter, the processes in steps S607 and S611 are repeated until the determination in step S613 is positive.

  When 1 is set in the rear end detection flag, the determination in step S613 is affirmed, and after the rear end detection flag is reset to 0, the process proceeds to step S615.

  In step S615, the light source drive circuit 26 is instructed to turn off the LED array 11a.

In the next step S617, color information of the image is obtained based on the reflected light wavelength spectrum at each measurement position stored in the RAM 24. As the color information of the image, an XYZ color system recommended by the CIE (International Lighting Commission) or an L ^* a ^* b ^* color system can be used.

  In the next step S619, the color reproducibility in the image is evaluated based on the color information of the image.

  In the next step S621, the evaluation result of the image is stored in the RAM 24.

  In the next step S623, the input / output control circuit 21 is notified of the end of the image evaluation. Then, the process returns to step S403 to wait for the next image evaluation request.

  When the input / output control circuit 21 receives an image evaluation end notification, the input / output control circuit 21 outputs the evaluation result stored in the RAM 24 to the printer control device 2090.

  Based on the evaluation result from the image evaluation device 2245, the printer control device 2090 is emitted from the light source of the optical scanning device 2010 when color variation (color unevenness) is detected within one sheet of recording paper (within a page). Control the amount of luminous flux. When a color variation is detected between recording sheets (between pages), at least one of a developing bias, a fixing temperature, and a light emission amount of a light source for each scan is controlled.

In the above step S405, if the calibration request flag _{f A} is 1, the result of the determination in step S405 is affirmative, the process proceeds to step S407.

In step S407, the calibration request flag _{f A} reset to 0, the process proceeds to step S415.

  If the elapsed time t is equal to or longer than the calibration interval tc in step S409, the determination in step S409 is affirmed and the process proceeds to step S415.

  If the temperature difference ΔT is greater than or equal to the calibration temperature difference Tc in step S411, the determination in step S411 is affirmed and the process proceeds to step S415.

  If the number of printed sheets n is less than the calibrated sheet number Nc in step S413, the determination in step S413 is denied and the process proceeds to step S417.

Further, in step S417, the value of the calibration flag _{f B} unless one, the determination in step S417 is negative, the process proceeds to step S601. That is, the conversion matrix is not calibrated.

  As described above, the image evaluation apparatus 2245 according to the present embodiment includes the plurality of spectroscopic measurement apparatuses 10, the processing apparatus 20, and the like.

  Each spectroscopic measurement device 10 includes a light source unit 11, a microlens array 12, an aperture member 13, an imaging optical system 14, a diffraction element 15, a light receiver 16, and the like.

  The light receiver 16 includes a first line sensor 16_1 disposed at a position for receiving + 1st order diffracted light from the diffraction element 15 and a second line sensor 16_2 disposed at a position for receiving 0th order light from the diffraction element 15. Have.

  For each spectroscopic measurement device, the processing device 20 obtains the amount of displacement from the reference position of the first line sensor 16_1 in the X-axis direction based on the output signal of the second line sensor 16_2 for each optical sensor. Further, the processing device 20 estimates and calculates a reflected light wavelength spectrum for each spectroscopic measurement device, using a conversion matrix selected and interpolated according to the amount of positional deviation for each optical sensor.

  Then, the processing device 20 obtains the color information of the image based on each reflected light wavelength spectrum, and evaluates the color reproducibility in the image based on the color information of the image.

  In this case, each spectroscopic measurement device 10 can stably obtain a highly accurate measurement result with a simple configuration using a multiband spectroscopic method.

  Since the image evaluation device 2245 includes the plurality of spectroscopic measurement devices 10, the image evaluation can be performed with high accuracy.

  Since the color printer 2000 includes the image evaluation device 2245 and adjusts the image forming process based on the evaluation result of the image evaluation device 2245, a high quality image can be stably formed.

  In the above-described embodiment, a control device may be provided in each spectroscopic measurement device 10, and a part of the processing performed by the processing device 20 described above may be performed by the control device.

  Moreover, although the said embodiment demonstrated the case where the image evaluation apparatus 2245 has three spectroscopy measuring apparatuses, it is not limited to this. In short, the image evaluation device 2245 only needs to be provided with one or more spectroscopic measurement devices so that the color can be evaluated over the entire width of the image formed on the recording paper that the color printer 2000 can support.

  In the above-described embodiment, the case where the second line sensor 16_2 is disposed at the position where the 0th-order light from the diffraction element 15 is received has been described. However, the present invention is not limited to this. It may be arranged at a position for receiving diffracted light other than + 1st order diffracted light. For example, the second line sensor 16_2 may be arranged at a position for receiving −1st order diffracted light from the diffraction element 15.

  Moreover, although the said embodiment demonstrated the case where the center distance regarding the X-axis direction of two adjacent light-receiving area | regions in the 2nd line sensor 16_2 was the same as the pixel pitch d, it is not limited to this.

  In the above embodiment, instead of the microlens array 12, a refractive index distribution type lens array such as a SELFOC lens array (registered trademark) or an imaging optical system including a plurality of lenses or mirrors may be used. good.

  In the above embodiment, when the opening member 13 is close to the recording paper, the microlens array 12 may not be provided.

Further, in the above embodiment, in the calibration process of the transformation matrix, when the amount of displacement is between D ₂ and D ₃ , the transformation matrix G ₂ and the transformation matrix G ₃ are selected, and the two transformation matrices are positioned. Although the case where the interpolation is performed according to the shift amount has been described, the present invention is not limited to this. In accordance with the result of the estimated calculation using the result as conversion matrix G ₃ which is estimated and calculated by using a conversion matrix G ₂ to the displacement amount may be interpolated.

For example, a transformation matrix G _A at position displacement amount D _A, the transformation matrix G _B at position deviation amount D _B is selected, the actually measured positional deviation amount D _X is larger than the positional deviation amount D _A, positional deviation amount and D _B smaller. Then, the calculation results in the case of using the conversion matrix G _A and W _A, if the calculation results in the case of using the transformation matrix G _B and W _B, the operation result W _X at position deviation amount D _X, the following (4) It can obtain | require from Formula.

  As interpolation methods for interpolating a conversion matrix or a calculation result corresponding to an actually measured displacement amount from two conversion matrices or two calculation results, linear interpolation and quadratic interpolation are generally used. Well known interpolation methods can be used.

  Moreover, in the said embodiment, as FIG. 26 shows as an example, it may replace with the said 2nd line sensor 16_2, and may use semiconductor position sensor 16_3 which can output the spot position of incident light with an analog signal. . In this case, as shown in FIG. 27A, a semiconductor position sensor 16_3 may be provided for each 0th-order light, or for a plurality of 0th-order lights as shown in FIG. One semiconductor position sensor 16_3 may be provided.

  For example, as shown in FIG. 28, the position x1 is the reference position of the optical sensor 1, the position x2 is the reference position of the optical sensor 2,..., The position x5 is the reference position of the optical sensor 5. Consider a case where a semiconductor position sensor 16_3 is provided in 1 and the optical sensor 5. In this case, the positional deviation amount measured by the optical sensor 1 and the positional deviation amount measured by the optical sensor 5 are connected by a straight line, and the value at the position x2 of the straight line is defined as the positional deviation amount by the optical sensor 2. The value at x3 is the amount of positional deviation at the optical sensor 3, and the value at position x4 is the amount of positional deviation at the optical sensor 4.

  Moreover, in the said embodiment, as FIG. 29 shows as an example, you may provide the light source device 31 for position shift amount measurement. In this case, the second line sensor 16_2 is not necessary.

  The light source device 31 includes a semiconductor laser 31a, a collimating lens 31b, and a diffraction element 31c. The collimating lens 31b converts a light beam having a substantially single wavelength emitted from the semiconductor laser 31a into a substantially parallel light beam. The diffractive element 31c expands the light beam that has passed through the collimating lens 31b in the X-axis direction. Thereby, the line-shaped light which makes the X-axis direction a longitudinal direction is irradiated on the front surface of the recording paper P. FIG. The semiconductor laser 31 a is turned on and off by the light source driving circuit 26.

  In this case, in the conversion matrix calibration process, as shown in FIG. 30, instead of step S503, the light source driving circuit 26 is instructed to turn on the semiconductor laser 31a (step S503 '). At this time, the light beam incident on the diffractive element 15 travels toward the first line sensor 16_1 with almost no splitting (see FIG. 31). Then, the processing device 20 acquires the output signal of the first line sensor 16_1 (step S505 '), and obtains the positional deviation amount based on the output signal.

  Note that it is preferable to use an object such as a white scatterer prepared in advance as an object when the semiconductor laser 31a is turned on.

  In place of step S519, the light source driving circuit 26 is instructed to turn off the semiconductor laser 31a (step S519 ').

  Instead of the semiconductor laser 31a, a vertical cavity surface emitting laser (VCSEL), an LED array that emits a light beam having a substantially single wavelength, a lamp light source having a bright line, or the like may be used.

  In the above embodiment, the case where the image forming apparatus is an electrophotographic system has been described. However, the present invention is not limited to this, and may be an ink jet system, for example. In this case, it is possible to correct the color variation within one recording sheet and the color variation between recording sheets by adjusting the ink discharge amount according to the head position or adjusting the dot pattern. .

  In the above embodiment, the case of an image forming apparatus using four color toners has been described. However, the present invention is not limited to this. For example, an image forming apparatus using five or six color toners may be used.

  In the above embodiment, the image forming apparatus in which the toner image is transferred from the photosensitive drum to the recording paper via the transfer belt has been described. However, the present invention is not limited to this, and the toner image is directly transferred to the recording paper. The image forming apparatus may be used.

  Further, an image forming apparatus using a color developing medium (positive printing paper) that develops color by the heat energy of the beam spot as the recording paper may be used.

  Further, the image evaluation device 2245 in the above embodiment may be used other than the image forming device.

  As an example, FIG. 32 shows an image evaluation device 2245A for evaluating the color at one point of an image. The image evaluation device 2245A includes an illumination device 111, a first lens 112, an aperture member 113, a second lens 114, a diffraction element 115, a third lens 116, a light receiving element 117, a processing device 120, an input device 121, and a display device 122. Etc.

  The input device 121 includes at least one input medium (not shown) of, for example, a keyboard, a mouse, a tablet, a light pen, and a touch panel, and notifies the processing device 120 of various types of information input by an operator. Note that information from the input medium may be input in a wireless manner.

  The display device 122 includes a display unit (not shown) using, for example, a CRT, a liquid crystal display (LCD), a plasma display panel (PDP), and the like, and displays various information instructed from the processing device 120. Further, as an example in which the display device 122 and the input device 121 are integrated, there is an LCD with a touch panel, for example.

  The opening member 113 has one opening.

  The illuminating device 111 illuminates the object from a direction of 45 ° with respect to the normal direction, for example. The light beam diffusely reflected by the object in the normal direction is condensed by the first lens 112 in the vicinity of the opening of the opening member 113. The light beam that has passed through the aperture of the aperture member 113 is converted into substantially parallel light by the second lens 114 and diffracted by the diffraction element 115 in different directions for each wavelength. The light flux of each wavelength from the diffraction element 115 is collected by the third lens 116 and received by the light receiving element 117.

  As shown in FIG. 33 as an example, the light receiving element 117 includes a first light receiving unit 117_1 for receiving + 1st order diffracted light and a second light receiving unit 117_2 for receiving 0th order light (non-diffracted light). doing.

  Here, as an example, a photodiode array (PDA) is used as the first light receiving unit 117_1, and a semiconductor position sensor (PSD) capable of analogly outputting the spot position of incident light is used as the second light receiving unit 117_2. Yes.

  The first light receiving unit 117_1 has ten light receiving regions (pixels), and is arranged so that, for example, light having a wavelength of 400 nm to 700 nm can be received in ten pixels.

  The second light receiving unit 117_2 outputs the barycentric position of the 0th-order light as an analog signal.

  For example, when the light intensity of the + 1st order diffracted light is significantly higher than the light intensity of the 0th order light, a light reducing member such as a neutral density filter (ND filter) is attached to a part of the first light receiving unit 117_1. May be.

  The processing device 120 has the same configuration as the processing device 20 and receives an evaluation request from the input device 121, and performs image evaluation processing.

  Here, the image evaluation process performed by the processing device 120 will be described. The flowchart in FIG. 34 corresponds to a series of processing algorithms executed by the CPU of the processing device 120 during the image evaluation process.

  In the first step S701, the light source of the illumination device 111 is turned on to illuminate the object.

  In the next step S703, the output signal of the second light receiving unit 117_2 is acquired.

  In the next step S705, the amount of positional deviation between the opening of the opening member 113 and the first light receiving portion 117_1 is obtained from the output signal of the second light receiving portion 117_2.

  In the next step S707, a transformation matrix is selected according to the amount of positional deviation.

  In the next step S709, when there are two selected transformation matrices, the two transformation matrices are interpolated to obtain a transformation matrix appropriate for the positional deviation amount.

  In the next step S711, the selected conversion matrix or interpolated conversion matrix is stored.

  In the next step S713, the output signal of the first light receiving unit 117_1 is acquired.

  In the next step S715, the light source of the illumination device 111 is turned off.

  In the next step S717, the reflected light wavelength spectrum is estimated. Here, the row vector v is created from the output signal of the first light receiving unit 117_1, the stored transformation matrix is read, the row vector v and the transformation matrix are integrated, and the row vector r is calculated.

  In the next step S719, color information of the image is obtained based on the reflected light wavelength spectrum obtained by the estimation calculation.

  In the next step S721, the color reproducibility in the image is evaluated based on the color information of the image.

  In the next step S723, the evaluation result of the image is displayed on the display device 122. Then, the image evaluation process ends.

  Note that a photodiode array similar to that of the first light receiving unit 117_1 may be used as the second light receiving unit 117_2. In this case, as shown in FIG. 35 as an example, the first light receiving unit 117_1 and the second light receiving unit 117_2 may be integrated.

  Further, as the first light receiving portion 117_1, a metal oxide semiconductor device (MOS), a complementary metal oxide semiconductor device (CMOS), a charge cup device (CCD), or the like may be used.

  In this case, the image evaluation device 2245A may include a transport device (not shown) for transporting the evaluation object.

  Further, as a modification of the image evaluation device 2245A, instead of the opening member 113, an opening member 113 ′ in which a plurality of openings are arranged in a line in one direction is used, and instead of the first light receiving unit 117_1, Using the first light receiving portion 117_1 ′ in which a plurality of photodiode arrays are arranged along the one direction, a plurality of semiconductor position sensors are arranged along the one direction instead of the second light receiving portion 117_2. The second light receiving portion 117_2 ′ may be used.

  In this case, the evaluation at a plurality of positions in the one direction can be performed almost simultaneously. At this time, as shown in FIG. 36 as an example, in the second light receiving unit 117_2 ', the number of semiconductor position sensors may be smaller than the number of photodiode arrays. The amount of misalignment at a position where the semiconductor position sensor is not provided can be estimated from the actually measured misalignment amounts before and after.

DESCRIPTION OF SYMBOLS 10 ... Spectrometer, 11 ... Light source unit, 11a ... LED array, 11b ... Collimating lens array, 12 ... Micro lens array (1st imaging system), 13 ... Aperture member, 14 ... Imaging optical system (2nd connection) Image system), 15 ... Diffraction element (diffractive member), 16 ... Light receiver, 16_1 ... First line sensor (light receiving element, first light receiving element), 16_2 ... Second line sensor (second light receiving element), 16_3 ... Semiconductor position sensor (light receiving position sensor), 20 ... Processing device (processing device, arithmetic device, evaluation means), 21 ... Input / output control circuit, 22 ... CPU, 23 ... ROM, 24 ... RAM, 26 ... Light source drive circuit, DESCRIPTION OF SYMBOLS 31 ... Light source device, 31a ... Semiconductor laser, 31b ... Collimating lens, 31c ... Diffraction element, 111 ... Illumination device, 112 ... 1st lens, 113 ... Opening member, 114 ... 2nd lens, 1 5 ... Diffraction element 116 ... Third lens 117 ... Light receiving element 120 ... Processing device 2000 ... Color printer (image forming device) 2010 ... Optical scanning device 2030a, 2030b, 2030c, 2030d ... Photoconductor drum 2050 ... fixing device, 2090 ... printer control device (adjustment device), 2245 ... image evaluation device, 2245A ... image evaluation device, P ... recording paper (object).

Japanese Patent No. 3925301 JP 2010-256324 A

Tokudo Tsumura, Hideaki Haneishi, Yoichi Miyake “Estimation of Spectral Reflectance from Multiband Images by Multiple Regression Analysis”, Optics, Vol. 27, no. 7, p. 384-391 (1998)

Claims (9)

A spectroscopic measurement device that measures the wavelength spectrum of reflected light from a relatively moving object,
A light source for irradiating the object with light;
An opening member having an opening and disposed on an optical path of reflected light from the object;
An imaging optical system that collects the reflected light that has passed through the aperture of the aperture member;
A diffractive member disposed on an optical path of the reflected light via the imaging optical system and diffracting the reflected light;
A light receiving element having a plurality of light receiving regions for receiving first-order diffracted light from the diffraction member;
A displacement detection device for detecting a displacement amount from a reference position of a relative position of the light receiving element with respect to the opening member;
A plurality of conversion matrices used for estimating and calculating the wavelength spectrum from the output signal of the light receiving element, and an appropriate conversion based on the detection result of the misalignment detection device with reference to the plurality of conversion matrices; A processing device for obtaining a matrix,
The plurality of transformation matrices correspond to a plurality of different positional deviation amounts,
The processing device selects two conversion matrices from the plurality of conversion matrices according to the amount of positional deviation detected by the positional deviation detection device, and interpolates the two conversion matrices to perform the appropriate conversion. min optical measuring apparatus you and acquires the matrix.   The misregistration detection device includes a light receiver that receives non-diffracted light from the diffractive member or diffracted light other than first-order diffracted light, and an arithmetic device that calculates the misregistration amount based on an output signal of the light receiver. The spectroscopic measurement apparatus according to claim 1.   The spectroscopic measurement apparatus according to claim 2, wherein the light receiver of the misregistration detection apparatus includes a light receiving position sensor that detects a light receiving position. The light receiving element is a first light receiving element,
The spectroscopic measurement device according to claim 2, wherein the light receiver of the misregistration detection device includes a second light receiving element having a plurality of light receiving regions. The light source is a first light source,
The misregistration detection device is based on a second light source that emits light of a single wavelength, and an output signal of the light receiving element when the first light source is turned off and the second light source is turned on. The spectroscopic measurement apparatus according to claim 1, further comprising an arithmetic unit that obtains the positional deviation amount.   The spectroscopic measurement apparatus according to claim 5, wherein the second light source is a light source that emits laser light. The opening member has a plurality of openings arranged along one direction,
The light receiving element, spectroscopic measurement apparatus according to any one of claims 1 to 6, characterized in that it has a plurality of light receiving regions for each opening of the opening member. An image evaluation device for evaluating the color of an image,
The spectroscopic measurement device according to any one of claims 1 to 7 ,
An image evaluation apparatus comprising: an evaluation unit that evaluates the color of the image based on a measurement result of the spectroscopic measurement apparatus. In an image forming apparatus that forms an image under image forming conditions according to image information,
An image evaluation apparatus according to claim 8 ,
An image forming apparatus comprising: an adjustment device that adjusts the image forming condition based on an evaluation result of the image evaluation device.

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