Adjustment Unit and Image Forming Apparatus

Abstract

To provide a technique to protect a reference member used for calibration at an inexpensive price.SOLUTION: An image forming apparatus comprises: color measuring means that has a light source; moving means that moves the color measuring means in a movement direction intersecting with a sheet conveyance direction; a reference member that is used for calibration of the color measuring means; and control means that, before execution of the calibration, controls the moving means to cause the light source to emit light at a first position where the reference member is not irradiated with light emitted from the light source.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an image forming apparatus having a color measurement function. Adjustment unit and

Background Art

[0002] The quality of an image formed by an image forming apparatus (hereinafter referred to as image quality) is evaluated by granularity, in-plane uniformity, character quality, color reproducibility (including color stability), and the like. In today's world where multi-color image forming apparatuses have become widespread, color reproducibility has become important.

[0003] Patent Document 1 discloses an image forming apparatus that forms a test image on a sheet and creates an ICC profile by measuring the color of the test image with a color sensor. By forming an image using the ICC profile, color reproducibility can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The color sensor performs calibration by measuring the color of a white reference plate. Also, when measuring color, the light source such as an LED is made to emit light for about 30 to 45 seconds in order to stabilize the emission luminance of the light source. In the following description, making the light source emit light in order to stabilize the emission luminance of the light source is referred to as "forced emission". In order to suppress the deterioration of the white reference plate due to this forced emission, a protection shutter is provided on the white reference plate. The protection shutter is configured to be movable between a protection position and a retracted position. In the protection position, the protection shutter is between the light source of the color sensor and the white reference plate, and prevents the white reference plate from being irradiated with the light emitted by the light source. When the protection shutter is in the retracted position, the light emitted by the light source irradiates the white reference plate. During calibration, the protection shutter is moved to the retracted position, and in other cases, the white reference plate is in the protection position to protect the white reference plate. However, in such a configuration, the product cost increases by providing the protection shutter and its moving mechanism. Also, it is necessary to secure in the image forming apparatus a space for moving the protection shutter between the protection position and the retracted position and an arrangement space for providing the moving mechanism, and the image forming apparatus becomes larger.

[0006] The present invention provides a technique for inexpensively protecting a reference member used in calibration.

Means for Solving the Problem

[0007] According to one aspect of the present invention, a light source a spectroscopic component that spectroscopically separates light by wavelength, a plurality of light receiving elements that receive the light spectroscopically separated by the spectroscopic component, is provided, color measurement means for measuring the color of a test image formed on a sheet, a reference member used for calibration of the color measurement means, and by moving the color measurement means in a direction intersecting the sheet conveyance direction, a first position where the light source irradiates light toward a region other than the reference member and a second position where the light source irradiates light toward the reference member, moving means for moving the color measurement means to the positions, and in a state where the color measurement means is located at the second position based on spectroscopic data obtained by the light source irradiating the reference member with light, the spectroscopic component spectroscopically separating the light reflected by the reference member, and the plurality of light receiving elements receiving the light, the color measurement means correcting the relationship between the wavelength of the light and the outputs of the plurality of light receiving elementsControl means for performing the calibration, characterized in that the control means, before performing the calibration, causes the light source to emit light for a predetermined period in a state where the color measuring means is located at the first position, and then moves the color measuring means to the second position.

Advantages of the Invention

[0008] According to the present invention, a reference member used in calibration can be protected at low cost.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and duplicate explanations are omitted.

[0011] <First Embodiment> FIG. 1 is a configuration diagram of the image forming apparatus 100. The image forming apparatus 100 includes a main body unit 101 and an adjustment unit 400. A printer controller 103 and an engine control unit 102 are provided in a control board storage unit 104 of the main body unit 101. The printer controller 103 controls the entire image forming apparatus 100. The engine control unit 102 controls each member of the main body unit 101 under the control of the printer controller 103 to perform image formation control on the sheet 110 and the like. The sheet 110 is an object on which an image is formed by the image forming apparatus 100, and is also called recording paper, paper, a recording medium, or the like. The operation unit 180 provides a user interface for the user to operate the image forming apparatus 100 and display the state of the image forming apparatus 100 to the user.

[0012] The image forming apparatus 100 has four stations 120, 121, 122, and 123 corresponding to yellow (Y), magenta (M), cyan (C), and black (K), respectively. The configurations of the stations 120, 121, 122, and 123 are the same except for the color of the toner used, and each forms a toner image of the corresponding color on the photoreceptor 105. The photoreceptor 105 is a kind of image carrier, and is charged to a uniform surface potential by the charger 111 during image formation. The optical scanning unit 107 emits laser light based on image data to the laser 108, and scans the photoreceptor 105 with the laser light to form a latent image on the photoreceptor 105. The developing device 112 develops the latent image with toner (color material) to form a toner image on the photoreceptor 105. The toner image is primarily transferred onto the intermediate transfer body 106. The toner image formed on the intermediate transfer body 106 is secondarily transferred onto the sheet 110 conveyed from the storage 113 by the transfer roller 114.

[0013] The image forming apparatus 100 according to this embodiment includes a first fixing device 150 and a second fixing device 160 that heat and press the toner image transferred onto the sheet 110 to fix it onto the sheet 110. The first fixing device 150 includes a fixing roller 151 for applying heat to the sheet 110, a pressure belt 152 for pressing the sheet 110 against the fixing roller 151, and a first post-fixing sensor 153 for detecting the completion of fixing. The second fixing device 160 is disposed downstream of the first fixing device 150 in the conveyance direction of the sheet 110. The second fixing device 160 adds gloss to the toner image on the sheet 110 fixed by the first fixing device 150 or ensures the fixability. The second fixing device 160 also includes a fixing roller 161, a pressure roller 162, and a second post-fixing sensor 163, similar to the first fixing device 150. Depending on the type of the sheet 110, it may not be necessary to pass through the second fixing device 160. In this case, the image forming apparatus 100 conveys the sheet 110 in the conveyance path 130. The flapper 131 switches whether to guide the sheet 110 to the conveyance path 130 or to the second fixing device 160.

[0014] The flapper 132 is a guiding member that guides the sheet 110 to the conveyance path 135 or the conveyance path 139. For example, when forming images on both sides of the sheet 110, the sheet 110 is conveyed toward the conveyance path 135. Note that since processes such as forming images on both sides of the sheet 110 are not necessary for the description of this embodiment, the description of these processes is omitted. In any case, the sheet 110 is finally conveyed to the adjustment unit 400 via the conveyance path 139.

[0015] FIG. 2 is a configuration diagram of the adjustment unit 400. The feeding roller 401 feeds the sheet 110 from the main body unit 101 to the adjustment unit 400. The sheet is conveyed along the conveyance path 431 by a plurality of conveyance rollers provided along the conveyance path 431 and discharged to the outside of the image forming apparatus 100 by the discharge roller 408. The color measurement unit 500 includes a color sensor 501, and the color sensor 501 measures the color of the sheet 110 being conveyed along the conveyance path 431.

[0016] FIG. 3 is a configuration diagram of the color sensor 501. The light source 507 is a light emitting element that irradiates each patch 520 of the test image on the sheet 110 with light. The diffraction grating 502 is a spectroscopic component that spectroscopically separates the light reflected from the patch 520 for each wavelength. The line sensor 503 is a light detection element including N light receiving elements 503-1 to 503-N that detect the light decomposed for each wavelength by the diffraction grating 502. The arithmetic unit 504 performs various calculations from the amount of light received by each light receiving element (pixel) detected by the line sensor 503. The memory 505 stores various data used by the arithmetic unit 504. The color sensor 501 may have a lens 506 that condenses the light emitted by the light source 507 onto the patch 520 of the test image on the sheet 110, or condenses the reflected light from the patch 520 onto the diffraction grating 502.

[0017] FIG. 4 is an explanatory diagram of the color measurement process by the color sensor 501. In FIG. 4, the output currents of the respective light receiving elements 503-1 to 503-N of the line sensor 503 are converted into voltages and displayed. Before starting the measurement, the arithmetic unit 504 forcibly emits light from the light source 507 for a predetermined period to stabilize the emission luminance of the light source 507. Subsequently, the arithmetic unit 504 turns off the light source 507 and measures the dark voltage obtained by converting the dark current of each of the light receiving elements 503-1 to 503-N of the line sensor 503 into a voltage. FIG. 4(A) shows an example of the measurement result of the dark voltage (Vdark). Next, the arithmetic unit 504 emits light from the light source 507 to irradiate the white reference plate 800 (see FIGS. 8 to 10), and causes the line sensor 503 to receive the reflected light from the white reference plate 800. The white reference plate 800 is a reference member used by the color sensor 501 as a white reference. At this time, the arithmetic unit 504 adjusts and corrects the emission luminance of the light source 507 so that the peak value (Vpeak) of the output of the line sensor 503 matches the target value. The target value is stored in the memory 505. FIG. 4 (B) shows the output voltages of the respective light receiving elements 503-1 to 503-N when the white reference plate 800 is irradiated with the light emitted by the light source 507 after the emission luminance of the light source 507 is adjusted. The arithmetic unit 504 obtains spectroscopic data indicating the spectroscopic reflectance, shown by the solid line in FIG. 4(C), by subtracting the dark voltage from the output voltages of the respective light receiving elements 503-1 to 503-N.

[0018] The memory 505 holds reference data which is the spectral data of the white reference plate 800 measured at the time of factory shipment. The dotted line in Fig. 4(C) indicates the reference data. The arithmetic unit 504 determines the amount of positional deviation of the light-receiving element, that is, the amount of wavelength deviation, by comparing the acquired spectral data with the reference data. Then, the arithmetic unit 504 calculates the output voltage for each wavelength as shown in Fig. 4(D) in consideration of the amount of wavelength deviation. The arithmetic unit 504 stores the result of Fig. 4(D) in the memory 505 as the spectral data W(λ) of the white reference plate 800. Here, λ indicates the wavelength. When actually measuring each patch of the test image, the arithmetic unit 504 obtains, for example, a measurement result M(λ) as shown in Fig. 4(E). The arithmetic unit 504 calculates the spectral data Rp(λ) of the patch of the test image by, for example, the following formula.

[0019] Rp(λ)=M(λ) / W(λ)×R(λ)(1) R(λ) is the reflectance of the white reference plate 800, and its value is stored in the memory 505. The color sensor 501 outputs the spectral data Rp(λ) of each patch of the test image to the printer controller 103 as the color measurement result.

[0020] FIG. 5 is a flowchart of the calibration process of the color sensor 501. In S10, the arithmetic unit 504 forcibly emits light from the light source 507 in order to stabilize the emission luminance of the light source 507. Note that the time until the emission luminance becomes stable is correlated with the time until the temperature of the light source 507 becomes stable. Subsequently, the arithmetic unit 504 stops the emission of the light source 507, and in S11, measures the dark current of each light receiving element of the line sensor 503. Thereafter, the arithmetic unit 504 emits light from the light source 507 to irradiate the white reference plate 800, and causes each light receiving element to receive the reflected light from the white reference plate 800. In S12, the arithmetic unit 504 adjusts the emission luminance of the light source 507 so that the maximum value Vpeak among the output voltages of each light receiving element becomes the target value. After adjusting the emission luminance of the light source 507, in S13, the white reference plate 800 is measured, and the data shown in FIG. 4(B) is acquired. In S14, the arithmetic unit 504 acquires the spectral data of the white reference plate 800 as shown in FIG. 4(D) based on the measurement result in S13, the dark current measured in S11, and the reference data stored in the memory 505.

[0021] The image forming apparatus 100 creates a profile from the colorimetric result of a test image, and forms an output image by converting an input image using the profile. As a profile for realizing excellent color reproducibility, in the present embodiment, an ICC profile that has been accepted in the market in recent years is used. However, the present invention is not limited to the use of an ICC profile. For example, the present invention can also be applied to the use of a CRD (Color Rendering Dictionary) adopted from level 2 of PostScript proposed by Adobe, a color separation table in Photoshop, CMYK simulation in ColorWise of EFI that maintains ink plate information, and the like.

[0022] When a component is replaced by a customer engineer, before a job that requires color matching accuracy, and further when the user wants to know the color tone of the final output product at the design concept stage or the like, the user operates the operation unit 180 to instruct the creation process of the color profile.

[0023] The profile creation process is performed in the printer controller 103 shown in the block diagram of FIG. 6. When the operation unit 180 receives a profile creation instruction, the profile creation unit 301 outputs data indicating a CMYK color chart (test image), which is an ISO 12642 test form, to the engine control unit 102 without passing through the output ICC profile storage unit 305. The engine control unit 102 forms a test image on the sheet 110 as described with reference to FIG. 1. Further, the printer controller 103 instructs the color sensor 501 to measure the color of the test image. The color sensor 501 measures the color of the test image according to the instruction and outputs spectral data, which is the color measurement result, to the Lab calculation unit 303 of the printer controller 103. The Lab calculation unit 303 converts the spectral data into L*a*b* data and outputs it to the profile creation unit 301. Note that the Lab calculation unit 303 may convert it into the CIE1931 XYZ color system, which is a device-independent color space signal.

[0024] The profile creation unit 301 creates an output ICC profile based on the relationship between the CMYK color signal output to the engine control unit 102 and the L*a*b* data input from the Lab calculation unit 303. The profile creation unit 301 updates the output ICC profile by storing the created output ICC profile instead of the output ICC profile stored in the output ICC profile storage unit 305.

[0025] The ISO 12642 test form (test image) includes a plurality of patches of CMYK color signals that cover the color reproduction range that a general copier can output. The profile creation unit 301 creates a color conversion table based on the relationship between each color signal value and the measured L*a*b* value. That is, a conversion table from CMYK to L*a*b* is created. Based on this conversion table, an inverse conversion table, that is, a conversion table from L*a*b* to CMYK, is created and used as the output ICC profile.

[0026] When the profile creation unit 301 receives a profile creation command from the host computer through the I / F 308, it outputs the created output ICC profile to the host computer through the I / F 308. The host computer can execute color conversion corresponding to the output ICC profile with an application program.

[0027] RGB signal values input from a scanner or the like via the I / F 308 and standard printing CMYK signal values such as JapanColor are sent to the input ICC profile storage unit 307. The input ICC profile storage unit 307 performs RGB→L*a*b* or CMYK→L*a*b* conversion according to the image signal input from the I / F 308. The input ICC profile stored in the input ICC profile storage unit 307 is composed of a plurality of LUTs (look-up tables). These LUTs are, for example, a one-dimensional LUT that controls the gamma of the input signal, a multi-color LUT called direct mapping, and a one-dimensional LUT that controls the gamma of the generated conversion data. The input image signal is converted from a device-dependent color space to device-independent L*a*b* data using these LUTs. The input ICC profile storage unit 307 outputs the L*a*b* image signal to the CMM 306. CMM is an abbreviation for Color Management Module. Note that, for example, when an L*a*b* image signal is input via the I / F 308, the L*a*b* image signal is directly input to the CMM 306.

[0028] The CMM306 performs various color conversions. For example, the CMM306 performs a GUMAT conversion that maps the mismatch between the reading color space such as a scanner unit as an input device and the output color reproduction range of the image forming apparatus 100 as an output device. Also, the CMM306 performs a color conversion that adjusts the mismatch between the light source type at the time of input and the light source type when observing the output (also referred to as the mismatch in color temperature setting). In this way, the CMM306 converts the L*a*b* data into L'*a'*b'* data and outputs it to the output ICC profile storage unit 305. The profile created by colorimetry is stored in the output ICC profile storage unit 305. Therefore, the output ICC profile storage unit 305 color-converts the L'*a'*b'* data with the newly created ICC profile, converts it into a CMYK signal dependent on the output device, and outputs it to the engine control unit 102. Note that when the color conversion of the CMYK signal input via the I / F308 is not performed, the CMYK signal is output to the engine control unit 102.

[0029] Next, the details of the colorimetry unit 500 of the present embodiment will be described. The colorimetry unit has a moving mechanism that moves the color sensor 501 in a predetermined moving direction. In the present embodiment, the moving direction of the color sensor 501 is a direction orthogonal to the conveyance direction of the sheet 110. FIG. 7 is a perspective view of the moving mechanism of the colorimetry unit 500. The moving unit 530 holds the color sensor 501. Note that in FIG. 7, the color sensor 501 is omitted for simplification of the drawing. The moving bearing 532 of the moving unit 530 is engaged with the moving belt 533 and the moving shaft 534. The moving belt 533 is engaged with the moving motor 571 via the moving pulley 572. Therefore, by driving the moving motor 571, the moving unit 530 moves in the moving direction. Note that the position of the moving unit 530 is determined based on the position where the slide position detection sensor 545 detects the flag portion 531f of the moving unit 530.

[0030] FIG. 8 shows the configuration near the color sensor 501. In FIG. 8, for the sake of simplicity of the drawing, the moving mechanism of the colorimetric unit 500 is omitted, and only the color sensor 501 is shown. A pair of rollers composed of a conveyance roller 581 and a conveyance roller 582, and a pair of rollers composed of a conveyance roller 583 and a conveyance roller 584 convey the sheet 110 in the conveyance direction. The conveyance roller 581 and the conveyance roller 583 are rotationally driven by a drive unit 590, and the conveyance roller 582 and the conveyance roller 584 rotate following the rotation of the conveyance roller 581 and the conveyance roller 583, respectively. A backing member 810 is disposed between these two pairs of rollers. The color sensor 501 is configured to be movable in the moving direction (a direction orthogonal to the conveyance direction) between these two pairs of rollers. In the direction orthogonal to both the conveyance direction and the moving direction, the color sensor 501 and the backing member 810 are arranged on opposite sides with respect to the position where the sheet 110 is conveyed. Near the end portion of the backing member 810 in the moving direction, a white reference plate 800 is provided on the surface of the backing member 810 on the side where the sheet 110 is conveyed. In FIG. 8, the color sensor 501 has moved to a position where its colorimetric position 501S is within the white reference plate 800.

[0031] Further, the conveyance guide shutters 601 and 602 are each configured to be rotatable about axes 603 and 604 as rotation axes. The conveyance guide shutters 601 and 602 are driven by a drive unit 610. By rotating the conveyance guide shutters 601 and 602 in the R2 direction, the conveyance guide shutters 601 and 602 are in a closed state. Also, by rotating the conveyance guide shutters 601 and 602 in the R3 direction, the conveyance guide shutters 601 and 602 are in an open state.

[0032] Hereinafter, the operation of the color sensor 501 regarding colorimetry will be described. In the following description, as shown in FIGS. 9 and 10, in the moving direction, Backing member 810It is divided into three regions 810a, 810b, and 810c. Region 810b is the region through which the sheet 110 passes. On the other hand, regions 810a and 810c are regions through which the sheet 110 does not pass. Note that regions 810a and 810c are located on opposite sides of region 810b. In the present embodiment, the white reference plate 800 is provided in region 810a.

[0033] FIG. 9(A) shows a state where the color measurement position 501S of the color sensor 501 is on the white reference plate 800. Further, FIG. 9(B) shows a state where the color measurement position 501S of the color sensor 501 is in region 810a but not on the white reference plate 800. In the present embodiment, the color sensor 501 waits in the state of FIG. 9(A). Then, when performing forced light emission (S10 in FIG. 5) before color measurement, the printer controller 103 moves the color sensor 501 to the position shown in FIG. 9(B), that is, the position where the light from the light source 507 no longer irradiates the white reference plate 800. After the forced light emission, the printer controller 103 moves the color sensor 501 to the position shown in FIG. 9(A) to measure the white reference plate 800 and perform calibration. After calibration, the printer controller 103 waits with the color sensor 501 at the position shown in FIG. 9(A) until the sheet 110 is conveyed.

[0034] As shown in FIGS. 10(A) and 10(B), the test image formed on the sheet 110 has m×n patches. Specifically, m patches are formed in each of the n rows of P1 to Pn. As shown in FIG. 10(A), when the patches in the first row come to the color measurement position 501S of the color sensor 501 in the conveyance direction, the printer controller 103 moves the color sensor 501 waiting on the area 810a toward the area 810b while measuring the colors of the m patches in the first row. After measuring the colors of the m patches in the first row, as shown in FIG. 10(B), the printer controller 103 moves the color sensor 501 above the area 810c. Thereafter, when the patches in the second row come to the color measurement position 501S of the color sensor 501 in the conveyance direction, the printer controller 103 measures the colors of the m patches in the second row while moving the color sensor 501 toward the area 810a. After measuring the colors of the m patches in the second row, the printer controller 103 moves the color sensor 501 above the area 810a. Hereinafter, the same process is repeated until the colors of the patches in each of the n rows are measured.

[0035] As described above, the color sensor 501 is configured to be movable in the moving direction orthogonal to the conveyance direction of the sheet 110. Regarding the forced light emission of the color sensor 501, it is performed at a position where the light emitted by the color sensor 501 does not irradiate the white reference plate 800. With this configuration, it is possible to prevent the deterioration of the white reference plate 800 without providing a protection shutter and a moving mechanism for the protection shutter to the white reference plate 800. Further, by providing the white reference plate 800 outside the area 810b through which the sheet 110 passes, that is, in the area 810a where the sheet 110 does not pass, it is possible to reduce the contamination of the white reference plate 800 by paper dust.

[0036] In the above-described embodiment, before executing the calibration performed by measuring the white reference plate 800, the color sensor 501 was moved to the position shown in FIG. 9(B) to perform forced light emission. However, the present invention is not limited to the forced light emission before executing the calibration. For example, the spectral data shown in FIG. 4(D) obtained in the previous calibration can be used. Therefore, the present invention can also be applied to the forced light emission before color measurement when measuring the test image of the sheet 110 without performing calibration.

[0037] In the present embodiment, the white reference plate 800 is provided in the region 810a, but it may be provided in the region 810c. Further, in the present embodiment, the color sensor 501 was moved to a position different from the white reference plate 800 on the region 810a, that is, the position shown in FIG. 9(B) to perform forced light emission. More specifically, forced light emission was performed between the white reference plate 800 and the region 810b through which the sheet 110 passes. However, any position where the white reference plate 800 is not irradiated with light is acceptable, and the position where forced light emission is performed is not limited to the region 810a. For example, a configuration can be adopted in which forced light emission is performed at a position between the center of the region 810b and the white reference plate 800 in the moving direction. In order to shorten the calibration time, it is advantageous to shorten the distance between the position where the white reference plate 800 can be measured and the forced light emission position.

[0038] In the present embodiment, the moving direction of the color sensor 501 is set to the direction orthogonal to the conveyance direction of the sheet 110 within the range where the plane including the conveyance direction and the moving direction is parallel to the sheet 110. However, the moving direction is not limited to such a direction. Specifically, if the white reference plate 800 can be measured by moving and the sheet 110 is crossed, the moving direction may be a direction not orthogonal to the conveyance direction. That is, for example, within the range where the plane including the conveyance direction and the moving direction is parallel to the sheet 110, the moving direction can be set to a direction intersecting the conveyance direction of the sheet 110.

[0039] Furthermore, although the above-described embodiment has been described by taking an electrophotographic image forming apparatus as an example, the present invention can also be applied to an inkjet system or a sublimation type image forming apparatus. Furthermore, the present invention can be applied to any apparatus that calibrates a colorimetric unit (color sensor) using a reference member.

[0040] [Other Embodiments] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and causing one or more processors in a computer of the system or apparatus to read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0041] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the claims are attached to disclose the scope of the invention.

Description of Reference Numerals

[0042] 501: Color sensor, 530: Moving unit, 571: Moving motor, 533: Moving belt, 534: Moving shaft, 800: White reference plate, 103: Printer controller

Claims

1. A light source, a spectroscopic component that spectrally disperses light by wavelength, a plurality of light receiving elements that receive the light dispersed by the spectroscopic component, color measurement means for measuring the color of a test image formed on a sheet, A reference member used for calibration of the color measurement means, Moving means for moving the color measurement means in a direction intersecting the conveyance direction of the sheet, so that the color measurement means is moved to a first position where the light source irradiates light toward a region other than the reference member and a second position where the light source irradiates light toward the reference member, Control means for performing the calibration to correct the relationship between the wavelength of light and the output of the plurality of light receiving elements in the color measurement means based on spectral data obtained by irradiating the reference member with light from the light source in a state where the color measurement means is located at the second position and the spectroscopic component disperses the light reflected by the reference member and the plurality of light receiving elements receive the light, comprising, Before performing the calibration, the control means causes the light source to emit light for a predetermined period in a state where the color measurement means is located at the first position, and then moves the color measurement means to the second position. The adjustment unit is characterized by this.

2. It has conveyance means for conveying the sheet on which the test image measured by the color measurement means is formed, The adjustment unit according to claim 1, wherein the reference member is disposed outside a region through which the sheet conveyed by the conveyance means passes.

3. The adjustment unit according to claim 2, wherein the first position is a position between a region through which the sheet passes and a position where the reference member is disposed in a direction orthogonal to the conveyance direction of the sheet by the conveyance means.

4. The control means causes the color measurement means to measure the test image formed on the sheet while moving the color measurement means by the moving means, and the adjustment unit according to any one of claims 1 to 3.

5. The moving direction of the color measurement means by the moving means is a direction orthogonal to the conveyance direction of the sheet, and the adjustment unit according to any one of claims 1 to 4.

6. An adjustment unit according to any one of claims 1 to 5, and image forming means for forming on the sheet a test image including a plurality of patches of different colors, and after the calibration is executed, the control means causes the color measurement means to measure each of the plurality of patches of the test image formed on the sheet, An image forming apparatus characterized by the above.

Images