JP6222336B2 - Imaging apparatus and image forming apparatus - Google Patents

Description

The present invention relates to an imaging apparatus and an image forming apparatus .

  Image forming apparatuses such as color ink jet type image forming apparatuses and color electrophotographic image forming apparatuses are offset by advertising media and pamphlets that require a high image but a relatively small number of copies as the image quality improves. It is also used for printing.

  In offset printing that requires high image quality, the color of the printed matter requested by the customer may differ from the color of the print output result that is actually printed out by the image forming apparatus.

  Usually, the customer confirms the color of the printed matter on the display and places an order for printing. However, each image forming apparatus has a color reproduction characteristic specific to each model, which is different from the color confirmed on the display. May result in printing.

  Therefore, conventionally, a technique for performing color reproduction using a color space that does not depend on a device such as a display or an image forming apparatus, such as a Lab color space or an xyz color space, has been used.

  The image forming apparatus controls the amount of color material and the like in order to output a specified color. For example, in an ink jet image forming apparatus, the output color is controlled by controlling the amount of ink discharged from the ink head by calculating and controlling the amount of ink discharged and the print pattern. In the image forming apparatus, the output color is controlled by controlling the amount of toner adhering to the photosensitive member, the amount of laser beam, and the like.

  However, the amount of the color material, for example, the ink discharge amount of the ink jet image forming apparatus varies depending on the state of the nozzle of the head, the viscosity of the ink, the variation of the discharge drive elements (piezo elements, etc.), Variation in color reproducibility occurs. Further, the ink ejection amount of the ink jet type image forming apparatus changes with time in one image forming apparatus or varies for each image forming apparatus. In other words, variations in the color reproduction of the image occur.

  Therefore, conventionally, in an image forming apparatus, color adjustment processing is performed in order to suppress output variations due to characteristics unique to the device and to improve output reproducibility with respect to input. In this color adjustment processing, for example, first, an image of a reference color patch (reference color patch image) is actually output by the image forming apparatus, and the reference color patch image is measured by the color measurement device. Then, a color conversion parameter is generated based on the difference between the colorimetric value of the reference color patch image measured by the colorimetry device and the colorimetric value of the corresponding reference color in the standard color space, and the color conversion parameter is Set in the image forming apparatus. After that, when outputting an image according to the input image data, the image forming apparatus performs color conversion on the input image data based on the set color conversion parameter, and after color conversion is performed. By recording and outputting an image based on the image data, an output of an image with high color reproducibility can be achieved by suppressing output variations due to characteristics unique to the device.

  In this conventional color adjustment processing, a spectral colorimeter is widely used as a color measuring device for measuring a reference color patch image, and the spectral colorimeter can obtain a spectral reflectance for each wavelength. Therefore, highly accurate colorimetry can be performed. However, since the spectrocolorimeter is an expensive device equipped with a large number of sensors, it is desired to perform highly accurate color measurement using a cheaper device.

  Conventionally, reference colorimetric means for measuring a reference color chart in advance in order to obtain color reference values as RGB data, and an object including the reference color chart and a color-measurement object are imaged simultaneously or separately. Color image input means for obtaining data, image extraction means for extracting RGB data of the reference color chart and RGB data of the color to be measured from RGB data obtained by the color image input means, and the image extraction means The difference between the RGB data of the reference color chart obtained in step 1 and the RGB data of the reference color chart obtained by the reference color measurement means is obtained, and at least the RGB data of the color to be measured is corrected using this difference There has been proposed a colorimetric device characterized by comprising a calculation means (see Patent Document 1). In this conventional technique, a reference color chart to be compared with the subject is placed near the subject to be colorimetric, and the subject and the reference color chart are simultaneously imaged by a color video camera as a color image input means. In addition, it is disclosed that the RGB data of the subject is corrected using the RGB data of the reference color chart obtained by imaging, and the RGB data of the subject is converted into color values in the standard color space.

  However, in the prior art described in the above publication, it is difficult to keep the positional relationship between the reference color chart to be imaged as a subject to be compared and the color image input means constant for each imaging, and the imaging conditions for each imaging Fluctuates and there is a problem that it is difficult to perform stable imaging.

  Accordingly, an object of the present invention is to always capture an image of a subject and a reference chart with a stable positional relationship.

To solve the above problems and achieve the object, the present invention includes a housing, and a concave lens, an image sensor unit for capturing an object through the concave lens from inside the housing, the image sensor unit A provided lens, a reference chart disposed around the concave lens when viewed in the optical axis direction of the lens , and imaged by the image sensor unit , and each illuminates both the reference chart and the subject A plurality of light sources.

  According to the present invention, the subject and the reference chart can always be imaged with a stable positional relationship.

1 is a schematic perspective view of an image forming apparatus to which an embodiment of the present invention is applied. The top view of a carriage part. FIG. Front sectional drawing of an imaging part. AA arrow sectional drawing of the imaging device of FIG. Explanatory drawing of the optical path length at the time of reference | standard chart imaging when the concave lens is not provided. Explanatory drawing of the optical path length at the time of imaging object imaging when the concave lens is not provided. Explanatory drawing of the focal distance adjustment process by a concave lens. The principal part front view of the imaging part by which the concave lens is arrange | positioned on the bottom face in which the opening part is formed. FIG. 3 is a block diagram of a main part of the image forming apparatus. The block block diagram of an imaging part and a colorimetry control part. Explanatory drawing of the acquisition process of the reference | standard colorimetry value and imaging reference RGB value from a reference | standard sheet, and a reference value linear transformation matrix acquisition process. The figure which shows an example of an initial reference RGB value. Explanatory drawing of a colorimetry process. Explanatory drawing of the linear conversion matrix production | generation process between reference values RGB. The figure which shows the relationship between an initial reference | standard RGB value and the reference | standard RGB value at the time of colorimetry. Explanatory drawing of a basic colorimetry process. FIG. 18 is a diagram illustrating basic color measurement processing continued from FIG. 17. The front sectional view of the image pick-up part which used the transmission member as an optical path length change member. Explanatory drawing of the optical path length in the sand image part which used the permeation | transmission member as an optical path length change member. The principal part front sectional drawing of the imaging part by which the transmissive member is arrange | positioned on the bottom face in which the opening part is formed. The front sectional view of the image pick-up part by which the concave lens is inserted in the opening part currently formed in the bottom face itself of a frame. The front sectional view of the image pick-up part by which a concave lens is arranged on the opening formed in the bottom face itself of a frame. The front sectional view of the image pick-up part by which the transparent member is inserted in the opening part currently formed in the bottom face itself of a frame. The front sectional view of the image pick-up part by which the transmission member is arranged in the opening part currently formed in the bottom face itself of a frame. The front sectional view of the image pick-up part by which the opening and the crevice are formed in the frame bottom, and the concave lens is inserted in the opening. The front sectional view of the image pick-up part by which an opening and a crevice are formed in the frame bottom, and a concave lens is arranged in an opening. The front sectional view of the image pick-up part in which the transparent member is inserted in the opening of the bottom. The front sectional view of the image pick-up part by which the transparent member is arranged on the bottom in which the opening is formed. The top view of the imaging part provided with the reference | standard chart and the opening part for imaging side by side. AA arrow sectional drawing of the imaging part of FIG. FIG. 32 is a cross-sectional view of the imaging unit in FIG. The top view of a reference | standard chart. 1 is a system configuration diagram of an image forming system.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 34 are diagrams showing an embodiment of an imaging apparatus of the present invention, and FIG. 1 is a schematic perspective view of an image forming apparatus 1 to which an embodiment of the imaging apparatus of the present invention is applied.

  In FIG. 1, an image forming apparatus 1 has a main body housing 2 disposed on a main body frame 3, and a main guide rod in the main scanning direction indicated by a double arrow A in FIG. 4 and the auxiliary guide rod 5 are stretched over. The main guide rod 4 movably supports the carriage 6, and the carriage 6 is provided with a connecting piece 6 a that engages with the sub guide rod 5 to stabilize the posture of the carriage 6.

  In the image forming apparatus 1, an endless belt-like timing belt 7 is disposed along a main guide rod 4, and the timing belt 7 is stretched between a driving pulley 8 and a driven pulley 9. The driving pulley 8 is rotationally driven by the main scanning motor 10, and the driven pulley 8 is disposed in a state in which a predetermined tension is applied to the timing belt 7. The driving pulley 8 is rotationally driven by the main scanning motor 10 to rotate and move the timing belt 7 in the main scanning direction according to the rotation direction.

  The carriage 6 is connected to a timing belt 7, and is reciprocated in the main scanning direction along the main guide rod 4 when the timing belt 7 is rotationally moved in the main scanning direction by the drive pulley 8.

  The image forming apparatus 1 houses a cartridge unit 11 and a maintenance mechanism unit 12 at both end positions in the main scanning direction in the main body housing 2, and the cartridge unit 11 includes yellow (Y), magenta (M), and cyan. (C) and the cartridge which each accommodates each ink of black (K) is accommodated so that replacement | exchange is possible. Each cartridge of the cartridge unit 11 is connected to recording heads 20y, 20m, 20c, and 20k (see FIG. 2) of the corresponding color of the recording head 20 mounted on the carriage 6 by pipes (not shown), and from the cartridges through the pipes. Ink is supplied to the recording heads 20y, 20m, 20c, and 20k. In the following description, the recording heads 20y, 20m, 20c, and 20k are collectively referred to as the recording head 20.

  As will be described later, the image forming apparatus 1 moves on the platen 14 (see FIG. 2) in the sub-scanning direction (arrow B direction in FIG. 1) perpendicular to the main scanning direction while moving the carriage 6 in the main scanning direction. By ejecting ink onto the recording medium P that is intermittently conveyed, an image is recorded on the recording medium P.

  That is, the image forming apparatus 1 of the present embodiment intermittently conveys the recording medium P in the sub-scanning direction, and moves the carriage 6 in the main scanning direction while the conveyance of the recording medium P in the sub-scanning direction is stopped. While moving, ink is ejected from the nozzle array of the recording head 20 mounted on the carriage 6 onto the recording medium P on the platen 14 to form an image on the recording medium P.

  The maintenance mechanism unit 11 performs cleaning of the ejection surface of the recording head 20, capping, ejection of unnecessary ink, and the like to discharge unnecessary ink from the recording head 20 and maintain the reliability of the recording head 20. Yes.

  The image forming apparatus 1 is provided with a cover 13 that can open and close the conveyance part of the recording medium P. When the image forming apparatus 1 is maintained or when a jam occurs, the cover 13 is opened so that the inside of the main body housing 2 can be opened. Maintenance work, removal of the jam recording medium P, and the like can be performed.

  As shown in FIG. 2, the carriage 6 is mounted with recording heads 20y, 20m, 20c, and 20k. The recording heads 20y, 20m, 20c, and 20k are piped to the cartridges of the corresponding colors of the cartridge unit 11, respectively. Are connected to each other, and inks of corresponding colors are ejected onto the opposing recording medium P. That is, the recording head 20y is yellow (Y) ink, the recording head 20m is magenta (M) ink, the recording head 20c is cyan (C) ink, and the recording head 20k is black (K) ink. Discharge each.

  The recording head 20 is mounted on the carriage 6 so that its discharge surface (nozzle surface) faces downward (recording medium P side) in FIG. 1, and discharges ink onto the recording medium P.

  In the image forming apparatus 1, an encoder sheet 15 is disposed in parallel with the timing belt 7, that is, the main guide rod 5, over at least the movement range of the carriage 6. The encoder 6 reads the encoder sheet 15 on the carriage 6. A sensor 21 is attached. The image forming apparatus 1 controls the movement of the carriage 6 in the main scanning direction by controlling the driving of the main scanning motor 10 based on the reading result of the encoder sheet 15 by the encoder sensor 21.

  As shown in FIG. 3, the recording head 20 mounted on the carriage 6 includes recording nozzles 20 y, 20 m, 20 c, and 20 k configured by a plurality of nozzle rows, and is recorded on the platen 14. An image is formed on the recording medium P by ejecting ink from the nozzle rows onto the medium P. In the image forming apparatus 1, the upstream recording head 20 and the downstream recording head 20 are mounted on the carriage 6 in order to ensure a wide width of an image that can be formed on the recording medium P by one scan of the carriage 6. ing. In addition, the recording head 20k that discharges black ink has twice the number of recording heads 20y, 6m, and 6c that discharge color ink mounted on the carriage 6 in order to improve the black printing speed. Further, the recording heads 20y and 6m are arranged adjacent to each other in the main scanning direction so that the colors overlap in the reciprocating operation of the carriage 6 and the color does not change between the forward path and the backward path. Therefore, the arrangement of the recording heads 20y, 20m, 20c, and 20k of the recording head 20 is not limited to the arrangement shown in FIG.

  As shown in FIG. 2, an imaging unit (imaging device) 30 is attached to the carriage 6, and the imaging unit 30 performs colorimetry on a subject (colorimetric object) during color adjustment processing described later. Shoot the subject.

  As shown in FIG. 4 which is a front cross-sectional view of the imaging unit 30 and FIG. 5 which is a cross-sectional view taken along the line AA of FIG. 4, a rectangular box in which a surface on the substrate 31 side is opened on the substrate 31. A frame 32 having a shape is fixed by a fastening member (not shown), and the substrate 31 is fixed to the carriage 6 shown in FIG.

  In the imaging unit 30, the frame 32 has a lower surface of a surface portion (hereinafter referred to as a bottom surface portion) 32 a opposite to the substrate 31 facing the recording medium P on the platen 14 with a predetermined distance d. In the state, it is attached to the carriage 6, and the bottom surface (opposing surface) 32 a has a circular opening 32 b of a predetermined size at the center and a peripheral portion of the opening 32 b as a center. On the medium P side, a donut-shaped recess 32c having a larger width than the opening 32 is formed over a predetermined width.

  As will be described later, the gap d is preferably smaller in consideration of the focal length with respect to the two-dimensional image sensor 35. However, due to the flatness of the recording medium P, the lower surface of the frame 32 and the recording medium P are separated from each other. The size which does not contact, for example, is set to about 1 mm to 2 mm.

  A disc-shaped holding member 33 is detachably attached to the recess 32c of the bottom surface 32a by a method such as adhesion, screw fixing, or fitting, and a circular opening of a predetermined size is provided at the center of the holding member 33. A portion 33a is formed.

  The frame body 32 is not limited to a square box shape, and may be, for example, a cylindrical box shape having a bottom surface 32a in which an opening 32b is formed in the center, an elliptic cylinder box shape, or the like. .

  The imaging unit 30 is a surface of the substrate 31 on the frame 32 side, and an image sensor unit 34 is disposed at the center thereof. The image sensor unit (sensor means) 34 is a CCD (Charge Coupled Device) sensor. And a two-dimensional image sensor 35 such as a CMOS (Complementary Metal Oxide Semiconductor) sensor and a lens 36.

  As will be described later, the opening 33a includes a reference color patch KP (see FIG. 12) and a colorimetric adjustment sheet CS (see FIG. 12) of the reference sheet KS (see FIG. 12) that is an imaging target (subject) formed on the recording medium P. This is used to image the colorimetric adjustment color patch CP (see FIG. 14) of FIG. The opening 33a may be at least large enough to capture all images (patch images) to be imaged. However, since there is a gap d between the frame 32 and the imaging object, the opening 33a is around the opening 33a. In consideration of the generated shadow, it is formed in an opening state slightly larger than the size of the imaging region to be imaged. Therefore, the center of the opening 33 a is located at a position opposite to the image sensor unit 34, that is, on the optical axis of the image sensor unit 34.

  A reference chart KC is detachably mounted in a donut shape over a predetermined width on a portion of the holding member 33 located in the opening 32b as shown in FIG.

  The reference chart KC is used as a reference by the imaging unit 30 as a comparison target with the reference color patch KP of the reference sheet KS and the imaged colorimetric value of the colorimetric adjustment color patch CP of the colorimetric adjustment sheet CS that is the image pickup target in the color adjustment process. Photographed simultaneously with the color patch KP and the colorimetric adjustment color patch CP. That is, the imaging unit 30 includes the reference color patch KP of the reference sheet KS located outside the frame body 32 through the opening 33a formed in the holding member 33 fitted in the recess 32c of the bottom surface 32a of the frame body 32. A color patch on the reference chart KC attached to the upper surface of the outer periphery of the opening 33a of the holding member 33 attached to the bottom surface 32a of the frame 32, together with the image of the color measurement adjustment color patch CP of the colorimetry adjustment sheet CS. The image is taken as a comparison target.

  Note that the imaging unit 30 scans pixels sequentially and reads an image, so strictly speaking, the reference color patch KP of the reference sheet KS and the colorimetric adjustment patch CP of the colorimetric adjustment sheet CS and the reference are strictly speaking. Although the chart KC is not read at the same time, the image of the reference color patch KP, the colorimetric adjustment patch CP, and the reference chart KC can be acquired within one frame.

  As shown in FIG. 5, the reference chart KC has a plurality of reference color patches Pa for colorimetry in a donut shape on the inner surface (upper surface) of the frame 32 as shown in FIG. It is formed in the state arrange | positioned circularly along the recessed part 32b.

  The reference color patch Pa for colorimetry includes a YMC primary color patch, an RGB secondary color patch, a gray scale patch, and a tertiary color patch.

  Each patch constituting the reference color patch Pa for colorimetry is a table in the Lab color space, which is a standard color space, using the spectroscope BS (see FIG. 12), similarly to the reference patch KP of the reference chart KC described later. A color value (Lab value) is measured in advance, and becomes a reference value for colorimetry of a colorimetry adjustment color patch CP of a colorimetry adjustment sheet CS described later.

  Note that the configuration of the colorimetric patches Pa arranged in the reference chart KC is not limited to the arrangement example shown in FIG. 5, and any arrangement of patches can be used. A patch that can specify a wide color range may be used, and a YMCK primary color patch or a gray scale patch is a patch of colorimetric values of ink used in the image forming apparatus 1. It may be configured. Further, the RGB secondary color patches of the reference chart KC may be configured with patches of colorimetric values that can be developed with the ink used in the image forming apparatus 1, and colorimetric values such as JapanColor are determined. The obtained reference color chart may be used.

  The reference chart KC is detachably attached to the upper surface of the holding member 33 that is detachably attached to the donut-shaped recess 32c formed on the outer periphery of the opening 32b formed on the bottom surface 32a of the frame 32. Therefore, the two-dimensional image sensor 35 of the image sensor unit 34 can capture an image with the same focal length as that of the imaging target such as the recording medium P.

  Further, as described above, the reference chart KC includes the holding member 33 detachably attached to the donut-shaped recess 32c formed on the outer periphery of the opening 32b formed on the bottom surface 32a of the frame 32. Since it is detachably attached to the upper surface, even if dust or the like entering the frame 32 adheres to the surface of the reference chart KC, the reference chart KC is removed together with the holding member 33 to clean the reference chart KC cleanly. Later, it can be attached again, and the measurement accuracy of the reference chart KC can be improved.

  In the imaging unit 30, an illumination light source 37 is disposed on a substrate 31 at each of the four corners of a rectangular frame 32. The illumination light source 37 includes an LED (Light Emitting Diode) or the like as the illumination light source 37. It is used. The illumination light source 37 uniformly illuminates the imaging target on the recording medium P through the reference chart KC and the opening 33a. The arrangement position of the illumination light source 37 is not limited to the substrate 31 at the four corners in the frame 32, and the illumination light is uniformly irradiated to the imaging target on the recording medium P through the reference chart KC and the opening 33a. If so, it may be at an appropriate position.

  The imaging unit 30 has a concave lens (subject optical path length changing member) 41 fitted in an opening 33a formed at the center of a holding member 33 attached to the bottom surface 32a of the frame 32. The concave lens 41 is disposed in the optical path between the recording medium P and the two-dimensional image sensor 35 through the opening 33a.

  Since the concave lens 41 is fitted in the opening 33a formed on the optical axis of the image sensor unit 34, the center of the concave lens 41 is positioned on the optical axis of the image sensor unit 34. A concave lens having a curvature that matches the optical path length from the imaging surface of the recording medium P to the image sensor unit 34 with the optical path length from the reference chart KC to the image sensor unit 34 is used.

  That is, when viewed from the image sensor unit 34, the imaging unit 30, as shown in FIGS. 6 and 7, captures an imaging target (for example, on the recording medium P) through the reference chart KC on the holding member 33 and the opening 33 a. Since the distance to the colorimetric adjustment patch CP) formed on the image is different, as shown in FIG. 6, when the imaging target is imaged by matching the focal length with the reference chart KC, the focal length is shown in FIG. Is the distance of the reference chart KC, it is out of focus and is out of focus.

  However, in the imaging unit 30 of the present embodiment, as shown in FIG. 8A, the concave lens 41 is fitted in the opening 33a for imaging the imaging target, and FIG. As shown in b), according to the curvature of the concave lens 41, the focal length of the imaging target is the position of the imaging target indicated by the broken line from the position indicated by the solid line in FIG. 8B (the focal length when there is no concave lens 41). The image is taken in a state where the optical path length is extended (a state in which the optical path length is changed).

  In the above description, the case where the concave lens 41 is embedded in the opening 33a has been described. However, the concave lens 41 is not limited to the configuration embedded in the opening 33a, and imaging through the opening 33a is performed. As long as it is on the optical path between the object and the image sensor unit 34, it may be arranged at an appropriate position, for example, on the holding member 33 around the opening 33a as shown in FIG. However, in the case of disposing at an appropriate position between the opening 33a and the image sensor unit 34, it is necessary to be a position that does not interfere with the optical path for imaging the reference chart KC, and the curvature of the concave lens 41 is It is necessary to match with the arrangement position.

  Further, in the imaging unit 30, the illumination light that irradiates the imaging surface of the recording medium P through the concave lens 41 and the opening 33a and the illumination light that irradiates the reference chart KC are illumination light from the same illumination light source 37. The reference chart KC and the imaging surface of the recording medium P can be imaged simultaneously under the same illumination conditions. That is, since the illumination light source 37 that illuminates the subject always illuminates the reference chart KC, the subject on the reference chart KC and the recording medium P can be illuminated under substantially the same illumination conditions. The reference chart KC and the subject can be imaged.

  The image forming apparatus 1 according to the present embodiment is configured as a block as shown in FIG. 10, and includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and main scanning. A driver 104, a recording head driver 105, a colorimetric control unit 106, a paper conveying unit 107, a sub-scanning driver 108, and the like are provided, and the recording head 20, the encoder sensor 21, and the imaging device mounted on the carriage 6 as described above. Part 30 and the like.

  The ROM 102 stores programs such as a basic program and a color adjustment processing program as the image forming apparatus 1 and necessary system data. The CPU 101 uses the RAM 103 as a work memory based on the program in the ROM 102, and performs image processing. The respective units of the forming apparatus 1 are controlled to execute basic processing as the image forming apparatus 1 and, at the same time, the colorimetric processing obtained by the colorimetric processing by the colorimetric control unit 106 based on the RGB values captured by the imaging unit 30. Based on the color value, color adjustment processing at the time of image formation is executed.

  In the control of the carriage 6 and the paper transport unit 107, the CPU 101 controls the driving of the main scanning driver 104 based on the encoder value from the encoder sensor 21, and controls the movement of the carriage 6 in the main scanning direction. The CPU 101 controls driving of a paper transport unit 107 such as a sub-scan motor and a transport roller (not shown) via a sub-scan driver 108. Further, the CPU 101 controls the ink ejection timing and the ink ejection amount by the recording head 20 via the recording head driver 105. In addition, the CPU 101 controls the lighting drive of the illumination light source 37 of the imaging unit 30 via the color measurement control unit 106.

  As described above, the imaging unit 30 generates a colorimetric value for color adjustment that accurately reproduces the color of image data when recording and outputting an image to a color intended by the user, as will be described later. The color measurement adjustment patch CP formed by the recording head 20 on the recording medium P is imaged at the time of color measurement, and the captured RGB values are output to the CPU 101.

  The imaging unit 30 and the colorimetric control unit 106 are configured as a block as shown in FIG. The imaging unit 30 includes the illumination light source 37 and the image sensor unit 34, and also includes an image processing unit 110, an interface unit 111, and the like. The image processing unit 110 includes an A / D conversion unit 112, a shading correction unit, and the like. 113, a white balance correction unit 114, a γ correction unit 115, and an image format conversion unit 116.

  The imaging unit 30 outputs analog RGB image data obtained by the image sensor unit 34 simultaneously capturing the subject and the reference chart KC to the image processing unit 110, and the image processing unit 110 receives the analog RGB image data sent from the image sensor unit 34. Necessary image processing is performed on the RGB image data and output to the colorimetric control unit 106.

  The A / D conversion unit 112 of the image processing unit 110 digitally converts analog RGB image data input from the image sensor unit 34 and outputs the converted data to the shading correction unit 113.

  The shading correction unit 113 corrects the error of the image data caused by the illuminance unevenness of the illumination light from the illumination light source 37 with respect to the imaging range of the image sensor unit 34 with respect to the RGB image data input from the A / D conversion unit 112. And output to the white balance correction unit 114.

  The white balance correction unit 114 corrects the white balance of the RGB image data after the shading correction, and outputs the corrected data to the γ correction unit 115.

  The γ correction unit 115 corrects the image data input from the white balance correction unit 114 so as to compensate for the linearity of the sensitivity of the image sensor unit 34 and outputs the corrected data to the image format conversion unit 116.

  The image format conversion unit 116 converts the image data after γ correction into an arbitrary format, and outputs it to the colorimetry control unit 106 via the interface unit 111.

  The interface unit 111 is used for the imaging unit 30 to acquire various setting signals, timing signals, and light source drive signals sent from the colorimetry control unit 106, and to send image data from the imaging unit 30 to the colorimetry control unit 106. Interface.

  The color measurement control unit 106 includes a frame memory 121, a timing signal generation unit 122, a light source drive control unit 123, a calculation unit 124, and a nonvolatile memory 125. The calculation unit 124 includes a color measurement value calculation unit 126. Yes.

  The frame memory 121 is a memory that temporarily stores the image data sent from the imaging unit 30, and outputs the stored image data to the calculation unit 124.

  As shown in FIG. 12, the non-volatile memory 125 has Lab values that are colorimetric values of the colorimetric results of a plurality of reference color patches KP arrayed on the reference sheet KS by the spectroscope (colorimetry device) BS. And at least one of the XYZ values (both the Lab value and the XYZ value in FIG. 12) is stored as a reference colorimetric value in the memory table Tb1 of the nonvolatile memory 125 corresponding to the patch number.

  Further, the image forming apparatus 1 stores the reference sheet KS of the image forming apparatus 1 in a state where the reference colorimetric values are stored in the nonvolatile memory 125 in the memory table Tb1 and in the initial state of the image forming apparatus 1. An imaging reference RGB value obtained by reading the same reference patch KP as that read by the spectroscope BS of the reference sheet KS by the imaging unit 30 by controlling the movement of the carriage 6 by being set on the platen 14 is stored in the nonvolatile memory 125. Is stored in the memory table Tb1 in correspondence with the patch number, that is, in correspondence with the reference colorimetric value, and each patch of the reference chart KC of the imaging unit 30 is imaged to obtain the RGB value. The RGB value of each patch in the chart KC is set as the initial reference RGB value RdGdBd, and the memory table of the nonvolatile memory 125 is controlled under the control of the calculation unit 124. It is stored in Le Tb1.

  When the image forming apparatus 1 stores the reference colorimetric value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the nonvolatile memory 125, the colorimetric value calculation unit 126 stores the reference colorimetry stored in the nonvolatile memory 125. A reference value linear conversion matrix for mutual conversion is calculated for a pair of XYZ values and imaging reference RGB values, that is, a pair of XYZ values and imaging reference RGB values of the same patch number, and the calculated reference value linear The conversion matrix is stored in the nonvolatile memory 125.

  In the image forming apparatus 1, the above processing is executed in the initial state of the image forming apparatus 1, and the reference colorimetric values, imaging reference RGB values, and initial reference RGB values RdGdBd as execution results are stored in the memory table Tb 1 of the nonvolatile memory 125. Then, a reference value linear transformation matrix is calculated and stored in the nonvolatile memory 125.

  Further, as will be described later, the image forming apparatus 1 according to the present exemplary embodiment includes a color measurement adjustment color patch CP and a frame as a subject formed on the recording medium P by the recording head 20 that changes with time during color adjustment processing. The reference chart KC disposed inside the body 32 is simultaneously imaged by the image sensor unit 34, and image data including the colorimetric adjustment color patch CP and the reference chart KC is output to the colorimetry control unit 106. The color measurement control unit 106 uses the color measurement adjustment color patch CP captured by the image sensor unit 34 during the color adjustment processing acquired from the imaging unit 30 as a reference color patch (hereinafter referred to as an initial reference color patch) of the reference sheet KS. After conversion to the initial reference RGB value RdGdBd of the patch Pa of the reference chart KC read and stored at the same time when read by the imaging unit 30, the linearity of the colorimetric adjustment patch CP with respect to the initial reference RGB value RdGdBd A colorimetric process for obtaining a colorimetric value by taking out a portion having a color and performing linear conversion is performed.

  That is, the arithmetic unit 124 controls the operation of the colorimetric control unit 106, and the colorimetric value calculation unit 126 executes the colorimetric processing and outputs the colorimetric values that are the results of the colorimetric processing to the CPU 101. Then, the CPU 101 performs color adjustment processing on the image data using the colorimetric value, and controls the recording head 20 based on the color adjustment processed image data, thereby forming an image with improved color reproducibility. To do.

  The image forming apparatus 1 of this embodiment includes a ROM, an EEPROM (Electrically Erasable and Programmable Read Only Memory), an EPROM, a flash memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), and a CD-RW (Compact Disc Rewritable). A color measurement program for executing the color measurement method of this embodiment recorded on a computer-readable recording medium such as a DVD (Digital Versatile Disk), an SD (Secure Digital) card, or an MO (Magneto-Optical Disc). It is constructed as an image forming apparatus 1 equipped with a color measuring device that executes a color measuring method that realizes color reproducibility described later at low cost and stably by reading and introducing it into the ROM 102 or the nonvolatile memory 125 or the like. . This color measurement program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented programming language, and is stored in the recording medium. Can be distributed.

  Next, the operation of this embodiment will be described. The image forming apparatus 1 according to the present exemplary embodiment executes an imaging apparatus and a color measurement method that can stably and inexpensively realize color reproducibility.

  As shown in FIG. 12, the image forming apparatus 1 according to the present embodiment uses the spectroscope BS to calculate the color measurement results of a plurality of reference color patches arranged and formed on the reference sheet KS, among Lab values and XYZ values. , At least one of them is stored as a reference colorimetric value corresponding to the patch number in the memory table Tb1 of the nonvolatile memory 125 under the control of the CPU 101.

  Further, when the image forming apparatus 1 is in a state where the reference colorimetric values are stored in the nonvolatile memory 125 in the memory table Tb1 and the image forming apparatus 1 is in an initial state due to manufacture, overfall, or the like, The reference sheet KS is set on the platen 14 of the image forming apparatus 1, the movement of the carriage 6 is controlled, and the same reference patch as read by the spectroscope BS of the reference sheet KS is read by the imaging unit 30, and at the same time Each patch (initial reference color patch) of the reference chart KC disposed inside the frame 32 is imaged.

  When the image forming apparatus 1 captures the reference patch of the reference sheet KS and each patch of the reference chart KC by the imaging unit 30, the image forming apparatus 1 has RGB values obtained by processing the image data obtained by capturing the reference patch of the reference sheet KS by the image processing unit 110. As shown in FIG. 12, the calculation unit 124 of the color measurement control unit 106 associates the imaging reference RGB values, that is, device-dependent signals, with the patch numbers in the memory table Tb1 of the nonvolatile memory 125. That is, the initial reference RGB value RdGdBd, which is the RGB value obtained by reading the initial reference color patch of the reference chart KC and processing it by the image processing unit 110 while storing it in correspondence with the reference colorimetric value, is shown in FIG. As shown in FIG.

  Note that the calculation unit 124 calculates an average value for each predetermined region (color measurement target region) in the image data of the initial reference color batch of the reference chart KC read by the imaging unit 30, and sets the average value as the initial reference RGB value RdGdBd. Yes. When the initial reference RGB value RdGdBd is calculated by averaging a large number of pixels in the colorimetric object region in this way, the influence of noise can be reduced and the bit resolution can be improved. FIG. 13B is a scatter diagram in which the initial reference RGB value RdGdBd is plotted, and FIG. 13A is a reference Lab value Ldaddbd and XYZ value obtained by converting the initial reference RGB value RdGdBd into Lab values. The reference XYZ value xdydzd also indicates a state registered in the nonvolatile memory 125.

  When the image forming apparatus 1 stores the reference colorimetric value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the nonvolatile memory 125, the colorimetric value calculation unit 126 of the calculation unit 124 is stored in the nonvolatile memory 125. Calculate a reference value linear conversion matrix for mutual conversion with respect to a pair of XYZ value and imaging reference RGB value of the reference colorimetric value, that is, a pair of XYZ value and imaging reference RGB value of the same patch number The reference value linear transformation matrix is stored in the nonvolatile memory 125.

  In this state, in the image forming apparatus 1, the CPU 101 controls the main scanning movement of the carriage 6, the conveyance control of the recording medium P by the paper conveyance unit 48, and the recording head based on image data input from the outside, print settings, and the like. 20, by controlling the ink ejection from the recording heads 20 y, 20 m, 20 c, and 20 k of the recording head 20 while intermittently transporting the recording medium P by controlling the drive of the recording medium 20, the image is recorded on the recording medium P To do.

  At this time, the amount of ink discharged from the recording heads 20y, 20m, 20c, and 20k may change depending on the characteristics unique to the device, changes with time, and the like. An image is formed with a color different from the color, and the color reproducibility deteriorates.

  Therefore, the image forming apparatus 1 executes color adjustment processing for obtaining a colorimetric value and performing color adjustment based on the colorimetric value at a predetermined color adjustment processing timing.

  That is, at the color adjustment processing timing, the image forming apparatus 1 forms a plurality of color patches (colorimetric adjustment color patches) CP on the recording medium P by the recording head 20 as shown in FIG. Recorded and output as a sheet CS. In this color measurement adjustment sheet CS, a plurality of color measurement adjustment color patches CP, which are color patches for color measurement adjustment, are formed and output by the recording head 20, and output at the color adjustment processing timing of the image forming apparatus 1. A colorimetric adjustment color patch CP reflecting the characteristics, particularly the output characteristics of the recording head 20 is formed. Note that the color patch data of the color measurement adjustment color patch CP is stored in advance in the nonvolatile memory 125 or the like.

  Then, as will be described later, the image forming apparatus 1 uses the RGB values obtained by imaging the plurality of color measurement adjustment color patches CP of the color measurement adjustment sheet CS as color measurement target RGB values (color measurement RGB values). A color object RGB value is converted into an initial reference RGB value RdGdBd, and among the reference colorimetric values registered in the memory table Tb1 of the nonvolatile memory 125, the initial reference RGB value RdGdBd is converted. A reference colorimetric value close to the distance (neighboring reference colorimetry value) is selected, and a colorimetric value for converting the colorimetric target RGB value into the selected neighborhood reference colorimetric value is obtained. Based on the colorimetric value Based on the image data after the color conversion, the recording head 20 outputs an image, thereby improving the color reproducibility of the image formed by the image forming apparatus 1.

  Therefore, as shown in FIG. 14, the image forming apparatus 1 sets the colorimetric adjustment sheet CS on the platen 14 or does not eject the colorimetric adjustment sheet CS when it is recorded. As the held state, the plurality of color measurement adjustment color patches CP of the color measurement adjustment sheet CS on the platen 14 are imaged by the imaging unit 30 while controlling the movement of the carriage 6 and at the same time, the imaging unit 30 captures the reference chart KC. Capture the patch. When the image forming apparatus 1 simultaneously captures the color measurement adjustment color patch CP of the color measurement adjustment sheet CS and the patch Pa of the reference chart KC by the imaging unit 30, the image processing unit 110 of the imaging unit 30 causes the image processing unit 110 of the color measurement adjustment sheet CS to After performing necessary image processing on the image data of the color measurement adjustment color patch CP and the image data of the patch Pa of the reference chart KC, the image data (RGB value) of the color measurement adjustment color patch CP of the color measurement adjustment sheet CS. ) As a colorimetric target RGB value, that is, a device-dependent signal depending on the device, and the image data (RGB value) of the patch Pa of the reference chart KC as the colorimetric reference RGB value RdsGdsBds, the colorimetry control unit 106 The colorimetric control unit 106 temporarily stores it in the frame memory 121 as shown in FIG. 14 (step S11).

  The colorimetric control unit 106 uses the colorimetric value RGB value stored in the frame memory 121 by the colorimetric value calculation unit 126 of the calculation unit 124 to initialize the colorimetric object to be initialized using a reference RGB linear conversion matrix to be described later. Conversion into RGB values RsGsBs (steps S12 and S13).

  The calculation unit 124 of the color measurement control unit 106 executes the basic color measurement process described later by using the converted initialization color measurement target RGB value RsGsBs as the color measurement target RGB value (step S14), and converts the Lab color measurement value. Obtain (step S15).

  In the image forming apparatus 1 according to the present exemplary embodiment, the colorimetric value calculation unit 126 of the calculation unit 124 obtains the reference RGB linear conversion matrix as illustrated in FIGS. 15 and 16.

  That is, as shown in FIG. 15, the calorimetric value calculation unit 126 of the calculation unit 124 captures the patch of the reference chart KC at the same time when the imaging unit 30 images the reference color patch KP of the reference sheet KS at the initial stage. When the initial reference RGB value RdGdBd stored in the nonvolatile memory 125 and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS are imaged by the imaging unit 30 during color measurement, the patch of the reference chart KC is simultaneously captured. Then, the colorimetric reference RGB value RdsGdsBds stored in the nonvolatile memory 125 is read from the nonvolatile memory 125, and the colorimetric reference RGB value RdsGdsBds is converted into the initial reference RGB value RdGdBd. , And the obtained reference RGB linear conversion matrix is stored in the nonvolatile memory 125.

  That is, in FIG. 16, the points indicated by white dots in FIG. 16A are points where the initial reference RGB values RdGdBd are plotted in the rgb space, and the filled points are the colorimetric reference RGB values RdsGdsBds as rgb. This is a point plotted in space. As can be seen from FIG. 16A, the value of the colorimetric reference RGB value RdsGdsBds varies from the value of the initial reference RGB value RdGdBd, and the direction of variation in the rgb space is shown in FIG. 16B. As indicated by the arrows, the directions are generally the same, but the direction of deviation differs depending on the hue. As described above, the reason why the RGB values fluctuate even when the patches of the same reference chart KC are imaged includes a change with time of the illumination light source 37 and a change with time of the two-dimensional image sensor 35.

  As described above, the colorimetric values are obtained using the colorimetric RGB values obtained when the colorimetric adjustment patch CP of the colorimetry adjustment sheet CS is imaged in a state where the patches of the same reference chart KC are fluctuated. If it is obtained, there is a possibility that an error occurs in the colorimetric value by the amount of variation.

  In view of this, the image forming apparatus 1 according to the present exemplary embodiment uses the estimation method such as the least square method between the initial reference RGB value RdGdBd and the colorimetric reference RGB value RdsGdsBds to initially set the colorimetric reference RGB value RdsGdsBds. A reference RGB linear conversion matrix to be converted into the reference RGB value RdGdBd is obtained, and the colorimetric adjustment color patch CP of the colorimetric adjustment sheet CS is imaged by the imaging unit 30 using the reference RGB linear conversion matrix, and the nonvolatile memory is obtained. The colorimetric object RGB values stored in 125 are converted into initialization colorimetry object RGB values RsGsBs, and the converted initial colorimetry object RGB values RsGsBs are used as colorimetry object RGB values to be described later. To obtain Lab colorimetric values.

  This linear conversion matrix between RGB may be not only a first-order but also a higher-order nonlinear matrix. If the nonlinearity is high between the rgb space and the XYZ space, a higher-order matrix can be obtained. , Conversion accuracy can be improved.

  The imaging unit 30 captures the reference color patch KP of the reference sheet KS as a subject and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS through the opening 33a formed on the bottom surface 32a. At the same time, by imaging the patch Pa of the reference sheet KS disposed in the recess 32b of the bottom surface 32a of the frame 32, the reference sheet KS is always the reference with the patch Pa of the reference sheet KS in the same positional relationship. The color patch KP and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS can be imaged, and the image can be captured in a stable state.

  Further, the imaging unit 30 has an aperture in the optical path between the reference color patch KP of the reference sheet KS and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS as the subject through the opening 33a and the two-dimensional image sensor 35. A concave lens 41 is fitted in the portion 33a.

  The imaging unit 30 then determines the optical path length (focal length) from the reference color patch KP of the reference sheet KS that is the imaging surface and the colorimetric adjustment color patch CP of the color measurement adjustment sheet CS that is the subject to the image sensor unit 34 and the reference. The curvature of the concave lens 41 is set so that the optical path length (focal length) from the chart KC to the image sensor unit 3 matches, and the focal position of the reference chart KC with respect to the image sensor unit 34 and the subject (reference of the reference sheet KS) The focus positions of the color patch KP and the color measurement adjustment color patch CP) of the color measurement adjustment sheet CS can be matched.

  Therefore, the reference color patch KP of the reference sheet KS, the colorimetric adjustment color patch CP of the colorimetry adjustment sheet CS, and the reference chart KC to be compared between them are always stably imaged with high accuracy and the same accuracy. Can do.

  Further, in the imaging unit 30, the illumination light that irradiates the imaging surface of the recording medium P through the concave lens 41 and the opening 33a and the illumination light that irradiates the reference chart KC are illumination light from the same illumination light source 37. The reference chart KC and the imaging surface of the recording medium P can be imaged simultaneously under the same illumination conditions.

  Then, the image forming apparatus 1 obtains the initial colorimetric target RGB value RsGsBs as described above and sets it as the colorimetric target RGB value, as shown in FIGS. 17 and 18, the memory table Tb1 of the nonvolatile memory 125 as shown in FIGS. Of the colorimetric values registered in the colorimetric object RGB values, the reference colorimetric values (neighboring reference colorimetric values) that are close in distance to the colorimetric values converted into the colorimetric object RGB values are selected and measured. A basic colorimetry process for obtaining a colorimetric value for converting a color target RGB value to a selected neighborhood reference colorimetric value is executed, and recording is performed based on image data after color conversion is performed based on the colorimetric value. By outputting an image by the head 20, the color reproducibility of the image formed by the image forming apparatus 1 is improved.

  That is, as shown in FIG. 17, the image forming apparatus 1 captures the color measurement adjustment color patch CP of the color measurement adjustment sheet CS, obtains the initial color measurement target RGB value RsGsBs as described above, and determines the color measurement target RGB. When stored in the nonvolatile memory 125 as a value (step S21), the reference value linear conversion matrix is used (step S22), converted into a first XYZ value (step S23), and stored in the nonvolatile memory 125 (step S22). S24). For example, in FIG. 17, the colorimetric value calculation unit 126 converts the colorimetric target RGB values (3, 200, 5) of the imaging unit 30 into the first XYZ values (first colorimetric values) of (20, 80, 10). And stored in the nonvolatile memory 125.

  The colorimetric value calculation unit 126 converts the first XYZ value into a first Lab value (first colorimetric value) by referring to the memory table Tb1 of the nonvolatile memory 125 or using a known conversion formula. (Step S25), stored in the nonvolatile memory 125 (Step S26). For example, in FIG. 17, the colorimetric value calculation unit 126 converts the first XYZ value (20, 80, 10) into the first Lab value (75, −60, 8) that is the imaged colorimetric value.

  Next, the colorimetric value calculation unit 126 searches for the reference colorimetric values (Lab values) of the color patches of the plurality of colors in the memory table Tb1 stored in the nonvolatile memory 125, as indicated by the Lab space in FIG. Then, a set of color patches (neighboring color patches) that are close in distance to the first Lab value in the Lab space is selected from the reference colorimetric values (Lab values) (step S27). For example, the Lab space diagram of FIG. 17 shows a diagram in which 60 color patches are selected and plotted on the Lab space. For example, the first Lab can be selected as a method for selecting a patch having a short distance. The distance between the value and all points in the reference colorimetric values (Lab values) of the plurality of color patches is calculated, and the reference Lab value of the color patch that is close to the first Lab value that is the first colorimetric value (see FIG. 17, a reference Lab value (hatched) is selected.

  Next, as shown in FIG. 18, the colorimetric value calculation unit 126 refers to the memory table Tb1, and sets the imaging reference RGB values paired with the first Lab value of the selected set, that is, the first Lab of the selected set. A combination of an imaging reference RGB value (selected RGB value) and a reference XYZ value having the same patch number as is selected (step S28), and a combination of the imaging reference RGB and reference XYZ of the selected combination (selected set) is converted. The selected RGB value linear transformation matrix is obtained using the least square method, and the obtained selected RGB value linear transformation matrix is stored in the nonvolatile memory 125 (step S29).

  The colorimetric value calculation unit 126 captures the colorimetry target RGB values obtained by imaging each colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS, which is a colorimetry target, by the image capturing unit 30 and digitally converting it by the A / D converter 36. A second XYZ value, which is a second colorimetric value, is obtained using the selected RGB value linear conversion matrix (step S30), and the second XYZ value is converted into a second Lab value using a known conversion formula (step S31). Obtained as a final colorimetric value (step S32).

  The colorimetric value calculation unit 126 performs image adjustment based on the image data that has been color-converted using the obtained colorimetric value, and drives the recording head 20 based on the image data that has undergone image adjustment to form an image.

  In other words, the image forming apparatus 1 according to the present embodiment captures and acquires a plurality of color measurement adjustment color patches CP of the color measurement adjustment sheet CS reflecting the output characteristics of the recording head 20 at the color adjustment processing timing. The first Lab value when the reference sheet KS is imaged in the initial state using the reference value linear conversion matrix is obtained as the colorimetric target RGB values, and the reference Lab values of the multiple color patches registered in the memory table Tb1 are obtained. Among them, a pair of patches with a reference Lab value that is close in distance to the first Lab value in the Lab space is selected, and a colorimetric RGB value corresponding to the selected reference Lab value is selected as a selected RGB value linear conversion matrix. The Lab colorimetric values are obtained by converting them into Lab values. Then, the colorimetric value calculation unit 126 performs image adjustment based on the image data subjected to color conversion using the obtained colorimetric value, and drives the recording head 20 based on the image data subjected to image adjustment to form an image. To do.

  In the above description, the case where the concave lens 41 is disposed as the optical path length changing member that changes the optical path length on the optical path between the imaging target passing through the opening 33a and the image sensor unit 34 has been described. The optical path length changing member for changing the lens is not limited to the concave lens 41. For example, as shown in FIGS. 19 and 20, a transmissive member 42 having a predetermined refractive index may be disposed.

  In this case, as shown in FIGS. 19 and 20, in the imaging unit 30, the transmissive member 42 is fitted in the opening 33 a of the holding member 33, and the transmissive member 42 replaces the transmissive member 42 of FIG. As shown in FIG. 20B in which the portion of the transmissive member 42 in the passed imaging is enlarged, the focal length of the imaging target by the transmissive member 42 is the position indicated by the solid line in FIG. 20B (when there is no transmissive member 42). The image is taken in a state (a state in which the optical path length is changed) extended from the focal length) to the position of the imaging target indicated by a broken line. Although not shown in the figure, for example, the transmissive member 42 fits a convex portion formed in the circumferential direction of the opening portion 33a of the transmissive member 42 and the holding member 33 into a concave portion formed in the other member 42, 33. By doing so, it is fitted into the opening 33a of the holding member 33 while performing accurate positioning.

  That is, the optical path length (focal length) from the reference color patch KP of the reference sheet KS that is the imaging surface and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS that is the subject to the image sensor unit 34 and the reference chart KC to the image sensor. The refractive index of the transmissive member 42 is set so that the optical path length (focal length) to the portion 3 matches.

  Accordingly, the focal position of the reference chart KC with respect to the image sensor unit 34 and the focal position of the subject (the reference color patch KP of the reference sheet KS and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS) can be matched.

  Even when the transmissive member 42 is used, as a method of disposing the transmissive member 42 on the optical path between the imaging object passing through the opening 33 a and the image sensor unit 34, the transmissive member 42 is fitted into the opening 33 a of the holding member 33. For example, as shown in FIG. 21, the transmissive member 42 may be disposed on the holding member 33 around the opening 33a. If it does in this way, positioning of transparent member 42 can be performed simply and easily. However, when it is arranged at an appropriate position between the opening 33a and the image sensor unit 34, the position and shape (conical shape, etc.) that do not interfere with the optical path for imaging the reference chart KC are required. The refractive index of the transmission member 42 needs to be matched with the arrangement position.

  As described above, in the image forming apparatus 1 according to the present exemplary embodiment, the imaging unit (imaging device) 30 is imaged through the opening 33a and the opening 33a for imaging the subject on the opposing surface facing the subject. A predetermined box-shaped frame 32 provided with a reference chart KC that is imaged together with a subject and provides a predetermined color reference; an illumination light source 37 that illuminates the subject and the reference chart KC under substantially the same illumination conditions; An image sensor unit (sensor means) 34 that receives the reflected light from the subject facing the opening 33a and the reflected light from the reference chart KC and images the subject and the reference chart KC, and the image sensor unit 34 from the subject. A concave lens (subject optical path length changing member) 41 or a transmissive member (subject optical path length changing member) 42 having a predetermined optical path length changing amount. To have.

  Therefore, both the subject and the reference chart KC can be stably imaged, and the optical path lengths of the subject and the reference chart KC with respect to the image sensor unit 34 can be appropriately adjusted. Highly accurate imaging can be performed with a stable positional relationship.

  Further, in the imaging unit 30 of the present embodiment, the opening 33a is formed in the holding member 33 as an opposing surface attached to the bottom surface 32 of the frame 32 at a position facing the image sensor unit 34, The object optical path length changing member is a concave lens 41 disposed on the optical path between the image sensor unit 34 and the opening 33a.

  Accordingly, the optical path length between the subject to be imaged through the opening 33a and the reference chart KC can be adjusted appropriately and inexpensively, and the subject and the reference chart KC can be imaged with high accuracy with a stable and stable positional relationship at low cost. be able to.

  Further, in the imaging unit 30 of the present embodiment, the opening 33a is formed in the holding member 33 as an opposing surface attached to the bottom surface 32a of the frame 32 at a position facing the image sensor unit 34, The object optical path length changing member is a transmission member 42 having a predetermined refractive index disposed on the optical path between the image sensor unit 34 and the opening 33a.

  Therefore, the optical path length between the subject to be imaged through the opening 33a and the reference chart KC can be adjusted appropriately and inexpensively by the transmissive member 42, and the subject and the reference chart KC can be cheaply and more always in a stable positional relationship. High-accuracy imaging can be performed.

  Further, in the imaging unit 30 of the present embodiment, the concave lens 41 or the transmissive member 42 that is a subject optical path length changing member is embedded in the opening 33a or disposed on the opening 33a. It is arranged.

  Accordingly, the optical path length between the subject to be imaged through the opening 33a and the reference chart KC can be adjusted appropriately and inexpensively, and the subject and the reference chart KC can be imaged with high accuracy with a stable and stable positional relationship at low cost. be able to.

  Further, the image forming apparatus 1 according to the present embodiment includes a reference chart KC composed of a plurality of colors and an imaging unit (imaging unit) 30 that simultaneously images an arbitrary subject, the subject imaged by the imaging unit 30, and the reference chart KC. A colorimetric device is installed in which the colorimetric control unit 106 calculates the colorimetric value of the subject based on the image data.

  Therefore, even if the RGB values for colorimetry when the colorimetric adjustment patch CP is imaged due to a change with time of the imaging unit 30 or the like, the change can be corrected, and the linearity of the colorimetric adjustment patch CP can be corrected. A colorimetric value can be obtained by taking out a portion having a color and linearly converting it, and color reproduction with suppressed distortion can be realized at low cost and more stably.

  In the above embodiment, the large opening 32b is formed in the bottom surface 32a of the frame 32, the opening 33a is formed at the center thereof, and the holding member 33 on which the reference chart KC is mounted is detachably attached. Although the concave lens 41 and the transmissive member 42 as the optical path length changing member are disposed in the opening 33a, the arrangement of the opening 33a and the reference chart KC is not limited to the above configuration.

  For example, as shown in FIGS. 22 to 25, an opening 33d for imaging may be formed on the bottom surface 32a itself of the frame 32, and an optical path length changing member may be disposed in the opening 33d. That is, as shown in FIG. 22, the concave lens 41, which is an optical path length changing member, is fitted into the opening 32d formed on the bottom surface 32a of the frame body 32, or the opening 32d of the bottom surface 32a is formed as shown in FIG. The concave lens 41 may be disposed on the formed lens. Further, as shown in FIG. 24, the transmission member 42, which is an optical path length changing member, is fitted into the opening 32d formed in the bottom surface 32a of the frame 32, or the opening 32d is formed as shown in FIG. You may arrange | position on the bottom face 32a of a part.

  In this case, as shown in FIGS. 26 to 29, an opening 32d is formed on the bottom surface 32a of the frame 32, and a recess 32e having a predetermined width is formed on the outer surface of the recess 32d on the top surface of the bottom surface 32a. And the reference chart KC may be detachably disposed in the recess 32e. Also in this case, as shown in FIG. 26, the concave lens 41 which is an optical path length changing member is fitted into the opening 32d formed in the bottom surface 32a of the frame 32, or as shown in FIG. You may arrange | position on forming the part 32d. Further, as shown in FIG. 28, the transmission member 42, which is an optical path length changing member, is fitted into the opening 32d formed in the bottom surface 32a of the frame 32, or the opening 32d is formed as shown in FIG. You may arrange | position on the bottom face 32a of a part.

  Further, as described above, the imaging unit 30 is not limited to the configuration in which the subject imaging opening 33a is formed at the center of the bottom surface 32 of the frame 32. For example, FIGS. As shown in FIG. 5, the reference chart KC and the subject imaging opening may be arranged side by side in the main scanning direction.

  That is, in FIG. 30 to FIG. 32, the imaging unit 50 includes a rectangular box-shaped frame body 52 whose surface on the substrate 51 side is open and fixed to the substrate 51 by the fastening member 53. These are fixed to the carriage 6 of the image forming apparatus 1 shown in FIG.

  The imaging unit 50 is a surface of the substrate 51 on the frame body 52 side, and an image sensor unit 54 is disposed at the center thereof. The image sensor unit 54 is a CCD (Charge Coupled Device) sensor or a CMOS (Complementary). A two-dimensional image sensor 55 such as a metal oxide semiconductor) sensor and a lens 56 are provided. The imaging unit 50 is located on a center line Lo in the sub-scanning direction passing through the center of the image sensor unit 54 and is spaced from the center of the image sensor unit 54 by a predetermined amount in the sub-scanning direction at equal intervals. In addition, a pair of illumination light sources 57 are mounted, and as the illumination light sources 57, LEDs or the like are used.

  In the imaging unit 50, the frame 52 has a lower surface of a surface portion (hereinafter referred to as a bottom surface portion) 52 a opposite to the substrate 51 facing the recording medium P on the platen 14 with a predetermined distance d. The bottom surface 52a is formed with a substantially rectangular opening 52b and an opening 52c in the main scanning direction around the center line Lo. The gap d is preferably smaller in consideration of the focal length with respect to the two-dimensional image sensor 55 as described above, but the lower surface of the frame 52 and the recording medium P are in contact with each other because of the flatness of the recording medium P. The size is not set, for example, about 1 mm to 2 mm.

  In the opening 52b, a concave portion 52d having a predetermined width is formed on the surface of the recording medium P along the periphery of the opening 52b, and the reference chart KC2 is detachably set in the concave portion 52d. A holding plate 52e that covers the surface of the reference chart KC2 on the recording medium P side and holds the reference chart KC2 in the recess 52d is detachably attached to the recess 52d of the opening 52b of the frame 52. The part 52b is closed by the reference chart KC2 and the holding plate 52e. The holding plate 52e has a smooth flat surface on the recording medium P side.

  The opening 52c is used to image the reference color patch KP of the reference sheet KS and the colorimetric adjustment color patch CP of the colorimetry adjustment sheet CS, which are objects to be imaged formed on the recording medium P. The opening 52c may be at least large enough to capture all images to be imaged. However, since there is a gap d between the frame 52 and the imaging object, a shadow generated around the opening 52c is generated. Considering this, it is formed in an opening state that is slightly larger than the size of the imaging region to be imaged.

  The reference chart KC2 is compared with the reference color patch KP of the reference sheet KS and the imaged colorimetric value of the colorimetric adjustment color patch CP of the colorimetric adjustment sheet CS that is the image pickup object in the color adjustment process. The image is taken together with the reference color patch KP and the colorimetric adjustment color patch CP. That is, the imaging unit 50 has the reference color patch KP of the reference sheet KS and the colorimetric adjustment color patch CP of the colorimetry adjustment sheet CS outside the frame 52 through the opening 52c provided in the bottom surface part 52a of the frame 52. In addition, the color patch on the reference chart KC2 mounted in the recess 52d formed around the opening 52b of the bottom surface 52a of the frame 52 is imaged as a comparison target. Note that since the two-dimensional image sensor 55 sequentially scans the pixels and reads the image, the imaging unit 50 sequentially reads the reference color patch KP of the reference sheet KS, the color measurement adjustment patch CP of the color measurement adjustment sheet CS, and the reference chart KC2. In this case, images of the reference color patch KP, the colorimetric adjustment patch CP, and the reference chart KC2 are acquired within one frame.

  As shown in FIG. 33, the reference chart KC2 has a plurality of reference color patch rows Pa to Pd and dot diameters for colorimetry on the inner surface (upper surface) of the frame 52 as shown in FIG. A measurement pattern row Pe, a distance measurement line lk, and a chart position specifying marker mk are formed.

  The color measurement patch rows Pa to Pd include a patch row Pa in which YMC primary color patches are arranged in gradation order, a patch row Pa in which RGB secondary color patches are arranged in gradation order, and a gray color. There are a patch array (achromatic gradation pattern) Pc in which patches of a scale are arranged in order of gradation, and a patch array Pd in which patches of a tertiary color are arranged, and the dot diameter measurement pattern array Pe has a size. It is a pattern sequence for measuring a geometric shape in which different circular patterns are arranged in order of size.

  The distance measurement line lk is formed as a rectangular frame surrounding the color measurement patch rows Pa to Pd and the dot diameter measurement pattern row Pe. The chart position specifying markers mk are provided at the positions of the four corners of the distance measuring line lk, and are markers for specifying each patch position.

  The colorimetric control unit 106 specifies the distance measurement line lk and the chart position specifying markers mk at the four corners from the image data of the reference chart KC2 acquired from the imaging unit 50, whereby the position of the reference chart KC2 and each Specify the position of the pattern.

  For each of the patches constituting the reference color patch rows Pa to Pd for colorimetry, the color values (Lab values) in the Lab color space, which is the standard color space, are measured in advance using the spectrometer BS. This is a reference value for colorimetry of the colorimetric adjustment color patch CP of the color adjustment sheet CS. The configuration of the colorimetric patch rows Pa to Pd arranged in the reference chart KC2 is not limited to the arrangement example shown in FIG. 33, and any patch row can be used. As long as possible, a patch capable of specifying a wide color range may be used, and the YMCK primary color patch row Pa and the gray scale patch row Pc may be used for the ink used in the image forming apparatus 1. It may be composed of patches of colorimetric values. Further, the RGB secondary color patch row Pa of the reference chart KC2 may be composed of patches of colorimetric values that can be developed with ink used in the image forming apparatus 1, and further, colorimetric values such as JapanColor. May be used.

  The reference chart KC2 is disposed in the recess 52d formed on the outer periphery of the surface on the recording medium P side of the opening 52b formed in the bottom surface 52a of the frame 52. Images can be taken by the two-dimensional image sensor 55 of the image sensor unit 54 at the same focal length as that of the imaging target.

  The reference chart KC2 is detachably set in a recess 52d formed on the outer periphery of the surface of the opening 52b formed on the bottom surface 52a of the frame 52 on the recording medium P side. Since the side surface is detachably held by the holding plate 52e that is detachably attached to the recess 52d, it is retained even if dust or the like that has entered the frame 52 adheres to the surface of the reference chart KC2. After the plate 52e and the reference chart KC2 are removed and the reference chart KC2 is cleaned cleanly, it can be attached again, and the measurement accuracy of the reference chart KC2 can be improved.

  In the imaging unit 50, the optical path length changing member 58 is disposed in the optical path between the recording medium P and the two-dimensional image sensor 55 that passes through the opening 52c in a state in which the opening 52c is closed. As the member 58, a transmissive member having a refractive index n (n is an arbitrary value) is used. As shown in FIGS. 30 to 32, the optical path length changing member 58 has an outer shape larger than the opening 52 c and is disposed in the frame body 52. The fixing position of the optical path length changing member 58 is not limited to the position on the opening 52c inside the frame 52 as shown in FIG. 31, but may be in the optical path between the opening 52c and the two-dimensional image sensor 55. For example, the position on the imaging surface side of the frame 52, the position inside the frame 52 and away from the opening 102 may be used. When the light passes through the optical path length changing member 58 having the refractive index n, the light is extended in accordance with the refractive index n of the optical path length changing member 58, and the two-dimensional image sensor 55 is in a state where the image is lifted. The image floating amount C can be obtained by the following equation (1), where Lp is the length of the optical path length changing member 58.

C = Lp (1-1 / n) (1)
Further, the focal length L of the focal plane of the imaging unit 50 other than the reference chart KC2, that is, the focal length L to the surface of the recording medium P imaged through the optical path length changing member 58 and the opening 52c is expressed by the following equation (2). It can ask for.

L = Lc + Lp (1-1 / n) (2)
Here, Lc is the distance between the top of the lens 56 on the imaging target side and the reference chart KC2, and n is the refractive index of the optical path length changing member 58.

  Therefore, for example, when the refractive index n of the optical path length changing member 58 is 1.5, L = Lc + Lp (1-1 / 1.5) = Lc + Lp (1/3), and the length of the optical path length changing member 58 The optical path length can be increased by about 1/3 of Lp. If Lp = 9 [mm], L = Lc + 3 [mm], and the imaging position of the reference chart KC2 and the focal position of the imaging surface of the recording medium P can be matched, and the reference chart KC2 The imaging surface of the recording medium P can be set in a conjugate relationship. In FIG. 31, in order to make the optical path length changing process by the optical path length changing member 58 easy to understand, the optical path is shown to be greatly changed, but the actual optical path change state is as shown in the figure. It does not mean to be.

  The imaging unit 50 uses illumination light from the same illumination light source 57 as illumination light that irradiates the reference chart KC2 and illumination light that irradiates the imaging surface of the recording medium P through the optical path length changing member 58 and the opening 52c. Both the reference chart KC2 and the imaging surface of the recording medium P can be imaged under the same illumination conditions. In addition, the two illumination light sources 57 are arranged on the center line Lo which is a substantially intermediate position between the reference chart KC2 and the recording medium P, and two illumination light sources 57 are arranged on the object on the center line Lo with respect to the lens 56. The imaging area of the reference chart KC2 and the recording medium P can be illuminated uniformly under substantially the same conditions.

  Furthermore, since the imaging unit 50 is arranged substantially symmetrically with respect to the center line Lo connecting the center of the lens 56 and the illumination light source 57, the arrangement condition of the opening 52c of the imaging region and the reference chart KC2 is two-dimensional. The imaging conditions of the image sensor 55 can be made the same in line symmetry, and the accuracy of color adjustment processing and color measurement processing of the two-dimensional image sensor 55 using the reference chart KC2 can be improved.

  Further, in the above description, the color measurement process is performed by the color measurement control unit 106 of the image forming apparatus 1. However, the color measurement process does not need to be executed inside the image forming apparatus 1. For example, FIG. As shown, an image forming apparatus 210 is connected to an external apparatus 220 as an image forming system (colorimetry system) 200, and image data captured by the image forming apparatus 210 is output to the external apparatus 220. The external device 220 performs color adjustment processing that includes colorimetric processing, and outputs the color-adjusted image data to the image forming device 210. The image forming device 210 forms an image based on the image data from the external device 220. May be.

  That is, the image forming apparatus 210 includes an engine 211, an operation display unit 212, an I / F unit 213, other I / F units 214, and the like, and each unit is connected by a bus 215. In addition, the external device 220 can use, for example, a computer having a normal hardware configuration and software configuration, and includes a color adjustment program including a color measurement program that executes a color adjustment process accompanying the color measurement process of the present invention as software. The color adjustment process accompanied by the colorimetric process is executed by introducing. The external device 220 includes a CPU 221, a memory unit 222, an image processing unit 223, a communication I / F unit 224, an I / F unit 225, and the like, and each unit is connected by a bus 226. The memory unit 222 includes a ROM 227, a RAM 228, a hard disk (HDD) 229, and the like.

  The image forming apparatus 210 is connected to the external apparatus 220 via a line 230 by an I / F unit 213. The line 230 is a dedicated line, a network such as a LAN (Local Area Network), the Internet, and the like, and is wired. Or wireless.

  The image forming apparatus 210 forms and outputs an image on a recording medium with the engine 211 based on the image data sent from the external apparatus 220 under the control of the external apparatus 220. The engine 211 forms an image on a recording medium by an ink ejection method or the like, and the operation display unit 212 includes various operation keys and a display such as an LCD (Liquid Crystal Display), which are necessary for the operation of the image forming apparatus 210. Various operations are performed by the operation keys, and various information notified from the image forming apparatus 210 to the user is displayed on the display. The other I / F unit 214 is used for connecting an expansion unit.

  The engine 211 includes a carriage that moves in the main scanning direction similar to that described in the above-described embodiment, and the imaging unit 30 is attached to the carriage. The image forming apparatus 210 forms the color measurement adjustment patch CP on the recording medium based on the color patch data of the color measurement adjustment color patch CP sent from the external apparatus 220 under the control of the CPU 221 of the external apparatus 220. The color measurement adjustment sheet CS is generated, the color measurement adjustment patch CP of the generated color measurement adjustment sheet CS is read by the imaging unit, and transmitted to the external device 220 via the I / F unit 213.

  The external device 220 stores in the hard disk 229 or the ROM 227 an image formation control program for controlling the operation of the image forming apparatus 210, a color adjustment program for performing color adjustment processing accompanying colorimetric processing of the present invention, and necessary data. The CPU 221 controls the image forming apparatus 210 based on a program in the ROM 227 or the hard disk 229, thereby executing basic processing as the image forming apparatus 210 and executing color adjustment processing accompanying colorimetric processing of the present invention.

  The hard disk 229 stores the above program and various data necessary for executing the color adjustment processing, in particular, the colorimetry of the plurality of reference color patches KP arranged on the reference sheet KS described in the above embodiment. At least one of the resulting Lab value and XYZ value, imaging reference RGB value, reference value linear transformation matrix, and neighborhood point table when the reference patch KP of the reference sheet KS is read by the imaging unit of the image forming apparatus 210 And the selected RGB value linear conversion matrix, the initial reference RGB value RdGdBd of each color patch of the reference chart KC2 read simultaneously with the reference sheet KS, and the reference chart read simultaneously when reading the colorimetric adjustment color patch CP of the colorimetry adjustment sheet CS KC2 standard patch colorimetric reference RGB value RdsGdsBds and colorimetric reference Reference RGB between linear transformation matrix to convert the GB value RdsGdsBds the initial reference RGB value RdGdBd is stored.

  The communication I / F unit 224 is connected to an image processing apparatus such as a scanner apparatus, a composite apparatus, or another external apparatus via a line such as a network, and receives image data that causes the image forming apparatus 210 to output an image.

  The image processing unit 223 performs various image processes necessary for forming and outputting the image data with the engine 211 of the image forming apparatus 210.

  As described above, the CPU 221 controls the operation of the image forming apparatus 210 and also executes a colorimetric process executed by the calculation unit 124 of the colorimetry control unit 106, in particular, the colorimetric value calculation unit 126. , Color adjustment is performed on the image data based on the colorimetric value, and the image data is output to the image forming apparatus 210.

  In the image forming system 200 of FIG. 34, the external device 220 controls the operation of the image forming apparatus 210. However, the image forming apparatus 210 itself includes a controller such as a CPU. The external device 220 may execute only the color measurement process for which the controller controls and obtains the color measurement value, or only the color adjustment process including the color measurement process.

  As described above, when color adjustment processing including color measurement processing or color measurement processing is executed at least by an external device of the image forming apparatus 210, the color reproducibility can be appropriately improved at low cost even in the inexpensive image forming apparatus 210. it can.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body housing | casing 3 Main body frame 4 Main guide rod 5 Sub guide rod 6 Carriage 6a Connection piece 7 Timing belt 8 Drive pulley 9 Driven pulley 10 Main scanning motor 11 Cartridge part 12 Maintenance mechanism part 13 Cover 20y, 20m, 20c, 20k Recording head 21 Encoder sensor 30 Imaging unit 31 Substrate 32 Frame body 32a Bottom surface 32b Opening portion 32c Recessed portion 32d Opening portion 32e Recessed portion 33 Holding member 33a Opening portion 34 Image sensor portion 35 Two-dimensional image sensor 36 Lens 37 Illumination light source 41 Concave lens 42 Transmission member 50 Imaging unit 51 Substrate 52 Frame 52a Bottom surface 52b Opening 52c Opening 52d Concave 52e Holding plate 53 Fastening member 54 Image sensor unit 55 Two-dimensional image sensor 56 Lens 57 Illumination light 58 the optical path length changing member 101 CPU
102 ROM
103 RAM
104 Main Scan Driver 105 Recording Head Driver 106 Colorimetry Control Unit 107 Paper Transport Unit 108 Sub Scan Driver 110 Image Processing Unit 111 Interface Unit 112 A / D Conversion Unit 113 Shading Correction Unit 114 White Balance Correction Unit 115 γ Correction Unit 116 Image Format Conversion unit 121 Frame memory 122 Timing signal generation unit 123 Light source drive control unit 124 Calculation unit 125 Non-volatile memory 126 Colorimetric value calculation unit 200 Image forming system 210 Image forming apparatus 211 Engine 212 Operation display unit 213 I / F unit 214 Others I / F unit 215 Bus 220 External device 221 CPU
222 Memory unit 223 Image processing unit 224 Communication I / F unit 225 I / F unit 226 Bus 227 ROM
228 RAM
229 Hard disk 230 Line Lo Center line Tb1 Memory table KS Reference sheet KP Reference color patch CS Color measurement adjustment sheet CP Color measurement adjustment patch KC, KC2 Reference chart Pa Reference color patch array Pa to Pd Reference color patch array Pe Dot diameter measurement pattern Line lk Distance measuring line mk Chart position marker

JP-A-5-223642

Claims (11)

A housing,
And a concave lens,
An image sensor unit that captures an image of a subject from the inside of the housing via the concave lens ;
A lens provided in the image sensor unit;
When viewed in the optical axis direction of the lens , a reference chart disposed around the concave lens and imaged by the image sensor unit ;
A plurality of light sources, each illuminating both the subject and the reference chart,
An imaging apparatus comprising: The imaging device according to claim 1, wherein the concave lens is disposed in an opening provided in the housing. The reference chart is disposed on a predetermined surface of the housing,
The imaging device according to claim 1, wherein the concave lens is disposed in an opening provided in the reference chart. The imaging device according to claim 2, wherein the concave lens is disposed so as to cover the opening. The imaging device according to claim 2, wherein the concave lens is fitted into the opening. The imaging device according to any one of claims 1 to 5, wherein the plurality of light sources are arranged at substantially the same distance from the image sensor unit . The imaging device according to claim 3, wherein the reference chart is detachably arranged. An image forming unit that forms an image on the object;
A control unit that causes the image forming unit to form an image;
The imaging device according to any one of claims 1 to 7, which captures an image formed by the image forming unit as a subject.
An image forming apparatus. The image forming apparatus according to claim 8, wherein the reference chart includes a pattern for measuring a distance of an image formed by the image forming unit. The image forming apparatus according to claim 8, further comprising a color measuring unit that measures an image formed by the image forming unit based on output data of the image sensor unit. A carriage that moves relative to the object;
The image forming apparatus according to claim 8, wherein the imaging device is held by the carriage.