JP6780716B2 - Imaging device, image forming device and color measurement method - Google Patents

Description

The present invention relates to an image pickup apparatus, an image forming apparatus, and a color measurement method.

Image forming devices such as color ink injection type image forming devices and color electrophotographic image forming devices have a relatively small number of prints, but offsets of advertising media, brochures, etc. that require high images as the image quality improves. It is also being used for printing.

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

Normally, the customer confirms the color of the printed matter on the display and orders printing, but each image forming device has color reproduction characteristics unique to each model and is different from the color confirmed on the display. It 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, for example, an L * a * b * color space or an xyz color space has been used. ..

Then, the image forming apparatus controls the amount of the coloring material and the like in order to output the designated color. For example, in an ink injection type image forming apparatus, the output color is controlled by calculating and controlling the ink ejection amount, the printing pattern, etc., and controlling the ink ejection amount from the ink head. In the image forming apparatus, the output color is controlled by controlling the amount of toner adhering to the photoconductor, the amount of light of the laser beam, and the like.

However, the amount of the coloring material, for example, the amount of ink ejected from the ink ejection type image forming apparatus varies depending on the state of the nozzle of the head, the variation in ink viscosity, the variation in the ejection driving element (piezo element, etc.), and the like. There are variations in color reproducibility. Further, the amount of ink ejected from the ink injection type image forming apparatus may change over time in one image forming apparatus or may be different for each image forming apparatus, and may change over time or for each image forming apparatus. In addition, the color reproduction of the image varies.

Therefore, conventionally, in an image forming apparatus, a color adjustment process is performed in order to suppress variations in output due to characteristics unique to the device and improve output reproducibility with respect to input. In this color adjustment process, for example, first, an image of a color patch of a reference color (reference color patch image) is actually output by an image forming apparatus, and the reference color patch image is measured by the color measuring apparatus. Then, a color conversion parameter is generated based on the difference between the color measurement value of the standard color patch image measured by the color measuring device and the coloration value in the standard color space of the corresponding standard color, and this color conversion parameter is used. Set in the image forming device. After that, when the image forming apparatus outputs an image corresponding to the input image data, the image forming apparatus performs color conversion on the input image data based on the set color conversion parameters, and after the color conversion is performed. By recording and outputting an image based on the image data, it is possible to suppress the variation in the output due to the characteristics peculiar to the device and to output the image with high color reproducibility.

In this conventional color adjustment process, a spectrophotometer is widely used as a colorimeter for measuring a reference color patch image, and the spectrophotometer can obtain the spectral reflectance for each wavelength. Therefore, high-precision color measurement can be performed. However, since a spectrophotometer is an expensive device equipped with a large number of sensors, it is required to enable highly accurate color measurement using a cheaper device.

Then, conventionally, the housing, the reference pattern used for color measurement arranged in the housing, the reference pattern is imaged in a part of the imaging region, and the color measurement target is imaged in the other region. A dimensional sensor, the two-dimensional sensor, an imaging element arranged on the reference pattern and the optical path of the color measurement target and forming an image of the reference pattern on the sensor surface of the two-dimensional sensor, and the two-dimensional An imaging device including a transmission member arranged in the optical path between the sensor and the color measurement target and having a refractive index for setting the imaging position of the color measurement target by the image forming element on the two-dimensional sensor surface. Has been proposed (see Patent Document 1). Then, in this conventional technique, the housing is moved on the color measurement target recorded on paper or the like, and the reference pattern in the housing and the color measurement target are imaged.

However, the prior art described in the above publication has a problem that the imaging quality is deteriorated.

Therefore, an object of the present invention is to improve the imaging quality of a subject.

To solve the above problems and achieve the object, an imaging apparatus according to the present invention is an imaging device having a two-dimensional image sensor and the opening, one before Symbol 2-dimensional image sensor of an image captured the shading correction data in the first region including the object of color measurement position through the opening, the shading correction be created based on the underlying color image data of the shading correction data of said first region comprising a data creation unit, and the front Symbol corrector to correct by the shading correction data to the first region of the first of the color measurement target data area smaller than the area, the.

According to the present invention, the imaging quality of a subject can be improved.

The schematic perspective view of the image forming apparatus to which one Example of this invention was applied. Top view of the carriage part. Arrangement diagram of the recording head. Top view of the imaging unit. FIG. 4 is a cross-sectional view taken along the line AA of the imaging unit of FIG. FIG. 5 is a cross-sectional view taken along the line BB of the imaging unit of FIG. Top view of the reference chart board. The main block block diagram of the image forming apparatus. Block configuration diagram of the image pickup unit and the color measurement control unit. The figure which shows an example of 3D image data when the white reference plate was imaged as a subject. The figure which shows an example of shading correction data. It is explanatory drawing of the acquisition process of the reference color measurement value and the imaging reference RGB value from the reference sheet, and the reference value linear conversion matrix acquisition process. The figure which shows an example of the initial reference RGB value. The figure which shows an example of image data which image | image | image | image | image | image | image | image | Explanatory drawing of colorimetric processing. Explanatory drawing of reference RGB linear transformation matrix generation processing. The figure which shows the relationship between the initial reference RGB value and the reference RGB value at the time of color measurement. Explanatory drawing of basic color measurement processing. The figure which shows the basic color measurement processing which continued with FIG. Front sectional view of an imaging unit not provided with an optical path length changing member. A cross-sectional view taken along the line AA of the imaging unit of FIG. 20. A system configuration diagram of an image forming system to which a color measurement system is applied.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Since the examples described below are preferable examples of the present invention, various technically preferable limitations are given, but the scope of the present invention is unreasonably limited by the following description. Not all of the configurations described in this embodiment are essential constituents of the present invention.

1 to 22 are views showing an embodiment of an image pickup unit, a color measurement device, an image forming device, a color measurement system, and a color measurement method of the present invention, and FIG. 1 is a diagram showing an image pickup unit, a color measurement device, and a color measurement method of the present invention. FIG. 5 is a schematic perspective view of an image forming apparatus 1 to which an embodiment of an apparatus, an image forming apparatus, a color measuring system, and a color measuring method is applied.

In FIG. 1, the image forming apparatus 1 has a main body housing 2 arranged on a main body frame 3, and a main guide rod in the main body housing 2 in the main scanning direction indicated by the double-headed arrow A in FIG. 4 and the sub guide rod 5 are stretched. The main guide rod 4 movably supports the carriage 6, and the carriage 6 is provided with a connecting piece 6a 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-shaped timing belt 7 is arranged along the main guide rod 4, and the timing belt 7 is stretched between the drive pulley 8 and the driven pulley 9. The drive pulley 8 is rotationally driven by the main scanning motor 10, and the driven pulley 9 is arranged in a state of giving a predetermined tension to the timing belt 7. The drive 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 rotational direction thereof.

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

In the image forming apparatus 1, the cartridge portion 11 and the maintenance mechanism portion 12 are housed at both ends in the main scanning direction in the main body housing 2, and the cartridge portions 11 are yellow (Y), magenta (M), and cyan. Cartridges for storing the inks (C) and black (K) are exchangeably stored. Each cartridge of the cartridge unit 11 is connected to the recording heads 20y, 20m, 20c, and 20k (see FIG. 2) of the corresponding colors of the recording head 20 mounted on the carriage 6 by a pipe (not shown). The cartridge supplies ink to the recording heads 20y, 20m, 20c, 20k through a pipe. In the following description, when 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 the carriage 6 in the main scanning direction and moves the carriage 6 in the sub-scanning direction (arrow B direction in FIG. 1) orthogonal to the main scanning direction on the platen 14 (see FIG. 2). By ejecting ink to the recording medium P that is intermittently conveyed, an image is recorded and output to 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 while the conveying of the recording medium P in the sub-scanning direction is stopped, moves the carriage 6 in the main scanning direction. While moving, ink is ejected from the nozzle row of the recording head 20 mounted on the carriage 6 onto the recording medium P on the platen 14, and an image is formed on the recording medium P.

The maintenance mechanism unit 12 cleans the ejection surface of the recording head 20, caps, ejects unnecessary ink, and discharges unnecessary ink from the recording head 20 and maintains the reliability of the recording head 20. There is.

The image forming apparatus 1 is provided with a cover 13 so that the transport portion of the recording medium P can be opened and closed. By opening the cover 13 during maintenance of the image forming apparatus 1 or when a jam occurs, the inside of the main body housing 2 is opened. It is possible to perform maintenance work, removal of the jam recording medium P, and the like.

As shown in FIG. 2, the carriage 6 is equipped with recording heads 20y, 20m, 20c, and 20k. The recording heads 20y, 20m, 20c, and 20k are connected to the cartridges of the corresponding colors of the cartridge unit 11 by pipes, and inks of the corresponding colors are discharged to the opposite 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 ejection surface (nozzle surface) faces downward in FIG. 1 (recording medium P side), and ejects ink to the recording medium P.

In the image forming apparatus 1, the encoder sheet 15 is arranged in parallel with the timing belt 7, that is, the main guide rod 4, at least over the moving range of the carriage 6. On the other hand, an encoder sensor 21 that reads the encoder sheet 15 is attached to the carriage 6. The image forming apparatus 1 controls the movement of the carriage 6 in the main scanning direction by controlling the drive 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 heads 20 mounted on the carriage 6 have the recording heads 20y, 20m, 20c, and 20k each composed of a plurality of nozzle rows. The recording head 20 forms an image on the recording medium P by ejecting ink from the nozzle row onto the recording medium P conveyed on the platen 14. In the image forming apparatus 1, the carriage 6 is provided with an upstream recording head 20 and a downstream recording head 20 in order to secure a wide width of an image that can be formed on the recording medium P by one scanning of the carriage 6. ing. Further, in order to improve the printing speed of black, the number of recording heads 20k that eject black ink is twice as many as the number of recording heads 20y, 6m, and 6c that eject color ink is mounted on the carriage 6. Further, the recording heads 20y and 6m are divided in the main scanning direction and arranged in an adjacent state so that the colors are overlapped in the reciprocating operation of the carriage 6 so that the colors do not change between the outward path and the return path. Has been done. 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 image pickup unit 30 is attached to the carriage 6, and the image pickup unit 30 captures a subject in order to measure a subject (color measurement object) during a color adjustment process described later. To do.

The image pickup unit 30 is mounted on the substrate 31 as shown in FIGS. 4 which are plan views, FIG. 5 which is a sectional view taken along the line AA of FIG. 4, and FIG. 6 which is a sectional view taken along the line BB of FIG. A square box-shaped housing 32 having an open surface on the substrate 31 side is fixed by a fastening member 33.

The substrate 31 is fixed to the carriage 6 shown in FIG. The housing 32 is not limited to a square box shape, and may be, for example, a cylindrical shape or an elliptical cylinder shape having a bottom surface portion 32a formed with openings 32b and 32c.

The image pickup unit 30 is a surface of the substrate 31 on the housing 32 side, and an image sensor unit 34 is arranged in the center thereof, and the image sensor unit (sensor means) 34 is a CCD (Charge Coupled Device) sensor. It is equipped with a two-dimensional image sensor 35 such as a CMOS (Complementary Metal Oxide Semiconductor) sensor and a lens 36.

In the imaging unit 30, the lower surface of the surface portion (hereinafter, referred to as the bottom surface portion) 32a of the housing 32 on the side opposite to the substrate 31 faces the recording medium P on the platen 14 with a predetermined interval d. In this state, it is attached to the carriage 6. On the bottom surface portion (opposing surface) 32a, a substantially rectangular opening 32b and an opening 32c are formed side by side with the center line Lo as the center, respectively, with the bottom surface portion 32a having a predetermined width interposed therebetween. .. As will be described later, the gap d is preferably small in consideration of the focal length with respect to the two-dimensional image sensor 35, but the lower surface of the housing 32 and the recording medium P are separated from each other in relation to the flatness of the recording medium P. The size is set so that it does not come into contact, for example, about 1 mm to 2 mm. The bottom surface portion 32a between the opening 32b and the opening 32c may be subjected to a predetermined surface treatment or the like to absorb the specularly reflected light from the illumination light source 37 described later.

The housing 32 is formed with a recess 32d on the outer surface of the bottom surface 32a side, including both the opening 32b and the opening 32c, and is further closer to the outer surface side of the housing 32 than the recess 32d. A recess 32e larger than the recess 32d is formed.

A reference chart plate (plate-shaped member) 38 is detachably fitted in the recess 32b so as to cover both the opening 32b and the opening 32c, and the holding plate is held while covering the reference chart plate 38. 39 is detachably fitted in the recess 32e.

The opening 32b and the opening 32c are closed by the reference chart plate 38 and the holding plate 39. As shown in FIGS. 5 and 6, the position of the reference chart plate 38 facing the opening 32c has a predetermined width in the moving direction of the imaging unit 30, and has a predetermined length in the direction orthogonal to the moving direction. A slit (opening) 38a is formed. Further, the holding plate 39 is formed with an opening 39a larger than the slit 38a at a position corresponding to the slit 38a.

As will be described later, the slit 38a is a reference color patch KP (see FIG. 12) and a color measurement adjustment sheet CS (see FIG. 12) of the reference sheet KS (see FIG. 12) which is an imaging target (subject) formed on the recording medium P. It is used to image the color measurement adjustment color patch CP (see FIGS. 5 and 15) of (5, see FIG. 15). The slit 38a may have at least a size capable of capturing all the patch images to be imaged, but since there is a gap d between the housing 32 and the imaging target, the shadow generated around the slit 38a is taken into consideration. Therefore, it is formed to be slightly larger than the size of the imaging region to be imaged.

As shown in FIG. 6, a reflection suppressing portion (reflection suppressing means) 40 is provided around the slit 38a on the surface of the reference chart plate 38 on the housing 32 side, and the reflection suppressing portion 40 is provided. In the image forming apparatus 1 of this embodiment, reflection is suppressed by applying black color having a predetermined width. The reference chart plate 38 is a portion facing the opening 32c, and the portion other than the reflection suppression portion 40 provided in black is changed to a color having low reflectance, for example, gray (gray). It may be applied. Further, the gray color data value may be a color data value exceeding the maximum value of the color data of the color of the reference chart KC.

The reference chart plate 38 has a reference chart KC formed on the inner surface of the housing 32 at a position facing the opening 32b.

The reference chart KC is used by the image pickup unit 30 as a comparison target with the reference color patch KP of the reference sheet KS and the image pickup color measurement value of the color measurement adjustment color patch CP of the color measurement adjustment sheet CS which is the image pickup target in the color adjustment process. It is taken together with the standard color patch KP and the color measurement adjustment color patch CP. That is, the image pickup unit 30 measures the colors of the reference color patch KP of the reference sheet KS and the color measurement adjustment sheet CS located outside the housing 32 through the slit 38a of the opening 32c provided in the bottom surface 32a of the housing 32. The adjustment color patch CP is imaged. Then, the imaging unit 30 captures the reference color patch KP and the colorimetric adjustment color patch CP, and compares the color patch on the reference chart KC located in the opening 32b of the bottom surface 32a of the housing 32 as a comparison target. Take an image.

In the image pickup unit 30, the two-dimensional image sensor 35 sequentially scans the pixels to read the image. Therefore, strictly speaking, 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 and the reference chart KC are not read together, but the reference color patch KP and the color measurement are performed within one frame. Since the images of the adjustment color patch CP and the reference chart KC can be acquired, they are appropriately expressed as "acquire together" or "acquire together".

As shown in FIG. 7, this reference chart KC has a plurality of reference color patch rows Pa to Pd for color measurement, pattern rows Pe for dot diameter measurement, and distance measurement on the inner surface (upper surface) of the housing 32. A line lk and a marker mk for specifying a chart position are formed.

The patch rows Pa to Pd for color measurement are 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 gray. There is a patch sequence (achromatic gradation pattern) Pc in which scale patches are arranged in the order of gradation, and a patch sequence Pd in which patches of tertiary colors are arranged. The dot diameter measurement pattern sequence Pe is a pattern sequence for geometric shape measurement in which circular patterns having different sizes are arranged in order of size.

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

The colorimetric control unit 106 (see FIGS. 8 and 9), which will be described later, identifies the distance measurement line lk and the chart position identification markers mk at its four corners from the image data of the reference chart KC acquired from the imaging unit 30. , The position of the reference chart KC and the position of each pattern are specified.

Each patch constituting the reference color patch sequences Pa to Pd for color measurement is a standard color space L * using a spectroscope BS (see FIG. 10) in the same manner as the reference patch KP of the reference chart KC described later. The color color value (L * a * b * value) in the a * b * color space is measured in advance. Each of these patches serves as a reference value when measuring the color measurement adjustment color patch CP of the color measurement adjustment sheet CS described later.

The configuration of the patch rows Pa to Pd for color measurement arranged on the reference chart KC is not limited to the arrangement example shown in FIG. 7, and any patch row can be used. For example, the patch sequences Pa to Pd may use patches that can specify the color range as widely as possible, and the YMCK primary color patch sequence Pa and the grayscale patch sequence Pc form an image. It may consist of a patch of color measurement values of the ink used in the device 1. Further, the RGB secondary color patch sequence Pa of the reference chart KC may be composed of a patch of color measurement values capable of developing colors with the ink used in the image forming apparatus 1, and further, color measurement values such as JapanColor. You may use the standard color chart that has been defined.

The reference chart plate 38 on which the reference chart KC is formed has an opening 32b formed in the bottom surface 32a of the housing 32 and a recess 32d formed on the outer periphery of the surface of the opening 32c on the recording medium P side. It is arranged in. Therefore, the reference chart KC is imaged by the two-dimensional image sensor 35 of the image sensor unit 34 at the same focal length as the image pickup target such as the recording medium P.

Further, the reference chart KC is detachably set in the opening 32b formed in the bottom surface 32a of the housing 32 and the recess 32d formed in the outer periphery of the surface of the opening 32c on the recording medium P side. There is. Further, the reference chart KC is detachably held by a holding plate 39 which is detachably fitted in the recess 32e outside the recess 32d. Therefore, even if dust or the like that has entered the housing 32 adheres to the surface of the reference chart KC, the holding plate 32e and the reference chart plate 38 are removed, and the surface of the reference chart plate 38 on the reference chart KC side is cleaned cleanly. be able to. Then, the reference chart plate 38 can be reattached after cleaning, and the measurement accuracy of the reference chart KC can be improved.

It will be described again from FIG. 4 to FIG. As shown in FIG. 4, the image pickup unit 30 is on the center line Lo in the sub-scanning direction passing through the center of the image sensor unit 34, and is equidistantly spaced by a predetermined amount from the center of the image sensor unit 34 in the sub-scanning direction. A pair of illumination light sources 37 are arranged on the substrate 31 at a distant position. As the illumination light source 37, an LED (Light Emitting Diode) or the like is used.

Further, in the imaging unit 30, the arrangement conditions of the opening 32c of the imaging region and the reference chart KC are arranged substantially symmetrically with respect to the center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 line-symmetrically the same, and improve the accuracy of the color adjustment processing and the color measurement processing of the two-dimensional image sensor 35 using the reference chart KC. be able to.

The lens 36 is arranged in the optical path of the reflected light from the subject and the reference chart KC to the two-dimensional image sensor 35, and the reflected light is focused on the two-dimensional image sensor 35. As the lens 36, one imaging lens may be used, or a plurality of lenses may be used in combination.

Further, in the housing 32, the optical path length changing member 50 is arranged on the bottom surface portion 32a in a state of closing the opening 32c in the housing 32, and the optical path length changing member 50 is around the opening 32c. Is fixed or held on the housing 32 of.

The optical path length changing member 50 uses a light transmitting member having a refractive index n and a length (hereinafter, referred to as the length of the optical path length changing member) Lp in the light transmission direction, and has a refractive index n. It has an optical path length change amount (amount of floating image) C determined by the following equation (1) according to the length Lp in the light transmission direction.

C = Lp (1-1 / n) ... (1)
The optical path length (focal length) L from the imaging surface of the recording medium P to the two-dimensional image sensor 35 of the image sensor unit 34 is given by the following equation (2).

L = Lt + Lp (1-1 / n) ... (2)
Here, Lt is the distance between the top of the lens 36 on the image pickup target side and the image pickup surface of the recording medium P.

Then, in the imaging unit 30, the optical path length (focal length) L from the imaging surface of the recording medium P to the two-dimensional image sensor 35 and the optical path length (focal length) from the reference chart KC to the two-dimensional image sensor 35 match. The refractive index n and the length Lp of the optical path length changing member 50 are set. By setting in this way, the focal position of the reference chart KC with respect to the two-dimensional image sensor 35 of the image sensor unit 34 can be made to match the focal position of the subject (imaging surface).

Further, the imaging unit 30 uses the same illumination light source 37 for illuminating the imaging surface of the recording medium P through the optical path length changing member 50 and the slit 38a of the opening 32c and illuminating the reference chart KC. It is the illumination light of. Therefore, the image pickup unit 30 can take an image of the reference chart KC and the image pickup surface of the recording medium P together under the same illumination conditions. Further, two illumination light sources 37 are arranged on the center line Lo, which is a substantially intermediate position between the reference chart KC and the recording medium P, and two illumination light sources 37 are arranged on the center line Lo with respect to the lens 36. Therefore, the imaging unit 30 can uniformly illuminate the imaging region of the reference chart KC and the recording medium P under substantially the same illumination conditions.

Further, in the imaging unit 30, the arrangement conditions of the slit 38a of the opening 32c of the imaging region and the reference chart KC are arranged substantially symmetrically with respect to the center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 line-symmetrically the same, and improve the accuracy of the color adjustment processing and the color measurement processing of the two-dimensional image sensor 35 using the reference chart KC. be able to.

The image forming apparatus 1 of this embodiment has a block configuration as shown in FIG. 8, and includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and a main scan. A driver 104, a recording head driver 105, a color measurement control unit 106, a paper transport unit 107, a sub-scanning driver 108, and the like are provided, and the recording head 20, the encoder sensor 21, and the image pickup mounted on the carriage 6 as described above It is equipped with a unit 30 and the like.

The ROM 102 stores programs such as a basic program as the image forming apparatus 1 and a color adjustment processing program, and necessary system data and the like.

Based on the program in the ROM 102, the CPU 101 controls each part of the image forming apparatus 1 while using the RAM 103 as a work memory to execute the basic processing as the image forming apparatus 1. Further, the CPU 101 executes a color adjustment process at the time of image formation based on the RGB value captured by the image pickup unit 30 and based on the color measurement value obtained by the color measurement process by the color measurement control unit 106.

In controlling the carriage 6 and the paper transport unit 107, the CPU 101 controls the drive of the main scanning driver 104 based on the encoder value from the encoder sensor 21 to control the movement of the carriage 6 in the main scanning direction. Further, the CPU 101 controls the drive of the paper transport unit 107 such as the sub-scanning motor and the transport roller (not shown) via the 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.

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

The image pickup unit 30 and the color measurement control unit 106 are configured in blocks as shown in FIG. The image pickup unit 30 includes the illumination light source 37, the image sensor unit 34, an image processing unit 110, an interface unit 120, and the like. The image processing unit 110 includes a black level correction circuit 111, an A / D conversion unit 112, a shading correction unit 113, a white balance correction unit 114, a γ correction unit 115, and an image format conversion unit 116. The image pickup unit 30 and the color measurement control unit 106 function as a color measurement device as a whole.

The image sensor unit 30 outputs analog RGB image data in which the image sensor unit 34 images the subject and the reference chart KC together to the image processing unit 110. The image processing unit 110 performs necessary image processing on the analog RGB image data sent from the image sensor unit 34 and outputs it to the color measurement control unit 106.

In the black level correction circuit 111, the analog image signal output by the image sensor unit 34 is input via an AC coupling capacitor (not shown). The black level correction circuit 111 clamps the image signal when the image sensor unit 34 reads the black color of the reflection suppression unit 40 formed around the slit 38a to a predetermined potential as the black offset level, and provides an appropriate offset. A voltage is applied to hold the sample. The black level correction circuit 111 converts the image signal into a continuous analog signal by sampling and holding the image signal by a sample pulse, and then outputs a pixel of each color signal to a constant level, particularly, the A / D converter 112. It is amplified to the level of the reference voltage and output to the A / D conversion unit 112.

That is, the black level correction circuit 111 clamps the black offset level to a predetermined potential by line-clamping the black color of the reflection suppression unit 40, and the reflection suppression unit 40 after digital conversion by the A / D conversion unit 112. The output of is almost the target black offset level.

The A / D conversion unit 112 compares the analog image signal input from the black level correction circuit 111 with the reference voltage, converts it into, for example, 8-bit digital data, and outputs it to the shading correction unit 113.

The shading correction unit 113 corrects an error in the image data due to uneven illuminance 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 from the A / D conversion unit 112. Then, it is output to the white balance correction unit 114.

The white balance correction unit 114 corrects the white balance with respect to the RGB image data after shading correction, and outputs the white balance 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 the linearity of the sensitivity of the image sensor unit 34, and outputs the image 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 color measurement control unit 106 via the interface unit 120.

The interface unit 120 is for the image pickup unit 30 to acquire various setting signals, timing signals and light source drive signals sent from the color measurement control unit 106, and to send image data from the image pickup unit 30 to the color measurement control unit 106. It is an interface.

Then, the shading correction unit 113 may arrange a white reference plate in the imaging region of the slit 38a, and the imaging unit 30 may read the white reference plate together with the reference sheet KS to perform shading correction. In this case, the image data of the white reference plate imaged by the image pickup unit 30 can be represented three-dimensionally as shown in FIG. The image data output by the image pickup unit 30 is RGB image data, but FIG. 10 shows only one color. Further, in FIG. 10, for the sake of simplicity, image data in the case where only four patches are formed on the reference chart KC is illustrated.

The shading correction unit 113 extracts the image data of the peripheral region of a predetermined color, which is the base of the correction data, from the image data output from the image sensor unit 34. Specifically, the shading correction unit 113 first removes image data in a pre-stored area (a predetermined area of the imaging range of the image sensor unit 34) from the image data output from the shading correction unit 113. .. In FIG. 10, the bottom surface region is the bottom surface portion 32a of the housing 32 located between the opening 32b and the opening 32c. FIG. 10 shows a case where the bottom surface portion 32a is subjected to a diffusion treatment for diffusing the illumination light from the illumination light source 37, but the diffusion treatment may not be applied.

Then, the shading correction unit 113 uses each patch provided on the reference chart KC (including the dot diameter measurement pattern sequence Pe and the distance measurement line lk) by using the chart position identification marker mk of the reference chart KC. Identify the location of. The shading correction unit 113 removes the image data of each of these patch areas from the image data output from the image sensor unit 34. The shading correction unit 113 detects a black reflection suppression unit 40 provided around the slit 38a of the reference chart plate 38. From the image data output from the image sensor unit 34, the image data of the black reflection suppression unit 40 and the region outside the black reflection suppression unit 40 is removed, and the image data of the white reference plate is acquired. Further, the shading correction unit 113 extracts the image data of the peripheral region consisting of only the region of the predetermined color of the reference chart KC as shown in FIG. The shading correction unit 113 compares the image data of the entire imaging range output from the image sensor unit 34 with a predetermined threshold value, and removes the region where the image data is equal to or less than the threshold value to obtain the image data of the peripheral region. May be extracted.

The shading correction unit 113 generates shading correction data by interpolating the image data of each patch area of the reference chart KC, the reflection suppression unit 40, and the white reference plate inside the patch based on the image data of the extracted peripheral area. .. Specifically, the shading correction unit 113 obtains an approximate expression that approximates the extracted image data of the peripheral region with a low-order (about 2 to 3rd-order) polynomial, and uses this approximate expression for each patch of the reference chart KC. The image data of these regions is interpolated by applying the region, the black reflection suppression portion 40 and the region inside the region (white reference plate). Further, the shading correction unit 113 interpolates the image data of each patch region of the reference chart KC, the reflection suppression unit 40, and the white reference plate region inside the patch using, for example, two-dimensional spline interpolation. May be good.

Then, the shading correction unit 113 generates shading correction data as shown in FIG. 11 by interpolating the image data and stores it in the internal storage unit. The shading correction unit 113 uses the shading correction data of the internal storage unit to correct the shading of the image data output by the image sensor unit 34 when the reference color patch KP is imaged, when the color measurement sheet CS is imaged, and when the subject is imaged. I do.

In the above description, the image data of the area of each patch provided on the reference chart KC is removed from the image data output from the image sensor unit 34, and the image data of the peripheral area is extracted. However, if the interval between the patches provided in the reference chart KC is narrow and the image data in the area between the patches cannot be properly extracted, the distance measurement line is used from the image data output from the image sensor unit 34. The image data of the entire region of the reference chart KC surrounded by lk may be removed to extract the image data of the peripheral region.

By imaging the white reference plate as the subject in this way, shading correction can be performed accurately and easily.

Further, by providing the black reflection suppression section 40 around the slit 38a and reading the black reflection suppression section 40, the black reference correction by the black level correction circuit 111 can be easily and appropriately performed.

Further, the shading correction unit 113 generates correction data to be used for shading correction by using only the image data of the white reference plate excluding the image data around the white reference plate from the image data output from the image sensor unit 34. ing. Therefore, it is possible to acquire highly accurate correction data, and it is possible to improve the correction accuracy of shading correction.

The color measurement control unit (calculation means) 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 non-volatile memory 125, and the calculation unit 124 is a color measurement value calculation unit. It is equipped with 126.

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

As shown in FIG. 12, the non-volatile memory 125 is a color measurement value of a color measurement result of a plurality of reference color patches KP arranged in a reference sheet KS by a spectrophotometer (colorimeter) BS. At least one of the a * b * value and the XYZ value (both the L * a * b * value and the XYZ value in FIG. 12) is patched to the memory table Tb1 of the non-volatile memory 125 as a reference color measurement value. It is stored corresponding to the number.

Further, the image forming apparatus 1 uses the reference sheet KS of the image forming apparatus 1 in a state where the reference color measurement value is stored in the memory table Tb1 in the non-volatile memory 125 and in the initial state of the image forming apparatus 1. Set on platen 14. The image forming apparatus 1 controls the movement of the carriage 6 and reads the same reference patch KP as that read by the spectroscope BS in the reference sheet KS by the imaging unit 30 to obtain the imaging reference RGB value of the non-volatile memory 125. It is stored in the memory table Tb1 in correspondence with the patch number, that is, in correspondence with the reference colorimetric value. Further, the image forming apparatus 1 images each patch of the reference chart KC of the image pickup unit 30 together with the reference sheet KS to acquire RGB values. The image forming apparatus 1 stores the RGB values of each patch of the reference chart KC as the initial reference RGB values RdGdBd in the memory table Tb1 of the non-volatile memory 125 under the control of the calculation unit 124.

When the image forming apparatus 1 stores the reference color measurement value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the non-volatile memory 125, the color measurement value calculation unit 126 stores the reference color measurement value in the non-volatile memory 125. A reference value linear conversion matrix for mutual conversion is calculated for a pair of a value XYZ value and an imaging reference RGB value, that is, a pair of an XYZ value and an imaging reference RGB value having the same patch number, and the calculated reference value linear is calculated. The conversion matrix is stored in the non-volatile 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 color measurement value, the imaging reference RGB value, and the initial reference RGB value RdGdBd, which are the execution results, are set to the memory table Tb1 of the non-volatile memory 125. After registering in, the reference value linear conversion matrix is calculated and stored in the non-volatile memory 125.

Further, as will be described later, the image forming apparatus 1 of the present embodiment includes a color measurement adjusting color patch CP and a housing as a subject formed on the recording medium P by the recording head 20 which is changing with time during the color adjusting process. The image sensor unit 34 images the reference chart KC arranged inside the body 32 together, and outputs the image data including the color measurement adjustment color patch CP and the reference chart KC to the color measurement control unit 106. The color measurement control unit 106 uses the color measurement adjustment color patch CP imaged by the image sensor unit 34 during the color adjustment process acquired from the image pickup unit 30 as the reference color patch of the reference sheet KS (hereinafter referred to as the initial reference color patch). After being converted to the initial reference RGB values RdGdBd of the reference charts KC patches Pa to Pe that were read and stored together when read by the imaging unit 30, the color measurement adjustment color patch CP was applied to the initial reference RGB values RdGdBd. Of these, the part having linearity is taken out and linearly converted to obtain the color measurement value, and the color measurement process is performed.

That is, the calculation unit 124 controls the operation of the color measurement control unit 106, and the color measurement value calculation unit 126 executes the color measurement process and outputs the color measurement value which is the processing result of the color measurement process to the CPU 101. To do. The CPU 101 color-adjusts the image data using the color measurement value, and controls the recording head 20 based on the color-adjusted image data to form an image in a state where the color reproducibility is improved.

The timing signal generation unit 122 generates a timing signal for controlling the timing of imaging by the image sensor unit 34 of the imaging unit 30 and supplies the timing signal to the imaging unit 30.

The light source drive control unit 123 generates a light source drive signal for driving the illumination light source 37 of the image pickup unit 30 and supplies the light source drive signal to the image pickup unit 30.

The image pickup unit 30 and the color measurement control unit 106 function as a color measurement device as a whole.

The image forming apparatus 1 of this embodiment includes ROM, EEPROM (Electrically Erasable and Programmable Read Only Memory) (registered trademark), EPROM, flash memory, flexible disk, CD-ROM (Compact Disc Read Only Memory), and CD-RW ( The color measurement method of this embodiment recorded on a computer-readable recording medium such as a compact disc rewritable), a DVD (Digital Versatile Disk), an SD (Secure Digital) card, or an MO (Magneto-Optical Disc) is executed. By reading the color measurement program and introducing it into the ROM 102 or the non-volatile memory 125, etc., the subject and the reference chart are always accurately positioned in a stable positional relationship while preventing the influence of the reflection of the illumination light on the subject of the illumination light source 37. It is constructed as an image forming apparatus 1 equipped with a color measuring device including a color measuring unit that executes a color measuring method for imaging. This color measurement program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark), an object-oriented blogging language, etc., and is stored in the above recording medium. Can be distributed.

Next, the operation of this embodiment will be described. The image forming apparatus 1 of this embodiment improves the image quality of the subject without being affected by the diffused reflection around the subject.

As shown in FIG. 12, the image forming apparatus 1 of this embodiment uses the color measurement results of the plurality of reference color patches arranged in the reference sheet KS by the spectroscope BS as the L * a * b * values. At least one of the XYZ values is stored as a reference color measurement value in the memory table Tb1 of the non-volatile memory 125 corresponding to the patch number.

Further, the image forming apparatus 1 is in a state where the reference colorimetric value is stored in the memory table Tb1 in the non-volatile memory 125, and the reference sheet is in the initial state when the image forming apparatus 1 is manufactured or overfalled. The KS is set on the platen 14 of the image forming apparatus 1. The image forming apparatus 1 controls the movement of the carriage 6 and images the same reference patch as read by the spectroscope BS of the reference sheet KS by the image pickup unit 30. Further, the image forming apparatus 1 captures each patch (initial reference color patch) of the reference chart KC arranged inside the housing 32 together with the reference patch of the reference sheet KS as shown in FIG.

The image forming apparatus 1 obtains an imaging reference RGB value, that is, a device-dependent signal depending on the device, which is an RGB value obtained by processing the image data obtained by imaging the reference patch of the reference sheet KS by the image processing unit 110. As shown in FIG. 12, the arithmetic unit 124 of the 106 stores the non-volatile memory 125 in the memory table Tb1 in accordance with the patch number, that is, in correspondence with the reference color measurement value. Further, the calculation unit 124 reads the initial reference color patch of the reference chart KC and converts the initial reference RGB value RdGdBd, which is the RGB value processed by the image processing unit 110, into the non-volatile memory 125 as shown in FIG. 13A. Store in.

In the image data of the initial reference color batch of the reference chart KC read by the imaging unit 30, the calculation unit 124 is a predetermined region of the imaging region imaged through the slit 38a, for example, a region shown by a broken line in FIG. 14 (measurement). The average value is calculated for each color target area) and used as the initial reference RGB value RdGdBd. When the initial reference RGB value RdGdBd is calculated by averaging a large number of pixels in the color measurement target region in this way, the influence of noise can be reduced and the bit resolution can be improved. Further, FIG. 13B is a scatter plot in which the initial reference RGB values RdGdBd are plotted. In FIG. 13A, the reference L * a * b * value Ldadbd obtained by converting the initial reference RGB value RdGdBd into the L * a * b * value and the reference XYZ value xdydzd converted into the XYZ value are also registered in the non-volatile memory 125. Indicates the state of.

When the image forming apparatus 1 stores the reference color measurement value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the non-volatile memory 125, the color measurement value calculation unit 126 of the calculation unit 124 calculates the reference value linear conversion matrix. And store it in the non-volatile memory 125. That is, the color measurement value calculation unit 126 sets a pair of the reference color measurement value XYZ value and the imaging reference RGB value stored in the non-volatile memory 125, that is, a pair of the XYZ value and the imaging reference RGB value of the same patch number. On the other hand, a reference value linear conversion matrix for mutual conversion is calculated and stored in the non-volatile memory 125.

In this state, in the image forming apparatus 1, the CPU 101 controls the main scanning movement of the carriage 6, the transport control of the recording medium P by the paper transport unit 107, and the recording head, based on the image data and print settings input from the outside. The drive of 20 is controlled to intermittently convey the recording medium P, and the ink ejection from the recording heads 20y, 20m, 20c, and 20k of the recording head 20 is controlled to record and output the image to the recording medium P. To do.

At this time, the amount of ink ejected from the recording heads 20y, 20m, 20c, and 20k may change due to characteristics unique to the device, changes over time, and the like. When the ejection amount of the ink changes, the image forming apparatus 1 forms an image with a color different from the color of the image intended by the user, and the color reproducibility deteriorates.

Therefore, the image forming apparatus 1 executes a color adjustment process of obtaining a color measurement value and performing color adjustment based on the color measurement value at a predetermined color adjustment process timing.

That is, when the color adjustment processing timing is reached, the image forming apparatus 1 forms a plurality of color patches (color measurement adjustment color patches) CP on the recording medium P by the recording head 20 as shown in FIG. 15 for color measurement adjustment. Record and output as sheet CS. In this color measurement adjustment sheet CS, a color measurement adjustment color patch CP, which is a plurality of color patches for color measurement adjustment, is formed and output by the recording head 20. The color measurement adjustment sheet CS is formed with a color measurement adjustment color patch CP that reflects the output characteristics at the color adjustment processing timing of the image forming apparatus 1, particularly the output characteristics of the recording head 20. The color patch data of the color measurement adjustment color patch CP is stored in advance in the non-volatile 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 patch CPs of the color measurement adjustment sheet CS as the RGB values to be measured (RGB values for color measurement). The color target RGB value is converted into the initial reference RGB value RdGdBd. The image forming apparatus 1 has a reference color measurement value (a reference color measurement value that is close in distance to the color measurement value obtained by converting the initial reference RGB value RdGdBd among the reference color measurement values registered in the memory table Tb1 of the non-volatile memory 125. Neighborhood reference colorimetric value) is selected. The image forming apparatus 1 obtains a colorimetric value for converting an RGB value to be colorimetrically measured into a selected neighborhood reference colorimetric value, and records the image data based on the image data after performing color conversion based on the colorimetric value. The image is output by the head 20. By doing so, the image forming apparatus 1 improves the color reproducibility of the formed image.

Therefore, the image forming apparatus 1 performs a color measurement process as shown in FIG. That is, the image processing device 1 is in a state where the color measurement adjustment sheet CS is set on the platen 14 or is held on the platen 14 without being ejected when the color measurement adjustment sheet CS is recorded. The image forming apparatus 1 captures a plurality of color measurement adjustment color patch CPs on the color measurement adjustment sheet CS on the platen 14 by the image pickup unit 30 by controlling the movement of the carriage 6, and the reference chart by the image pickup unit 30. Image the KC patch. When the image forming apparatus 1 captures the color measuring adjustment color patch CP of the color measuring adjustment sheet CS and the patch of the reference chart KC together by the image pickup unit 30, the image processing unit 110 of the image pickup unit 30 displays the color measurement adjusting sheet CS. Color measurement Performs necessary image processing on the image data of the color patch CP and the image data of the patch of the reference chart KC. The image processing unit 110 sends the image data (RGB value) of the color measurement adjustment color patch CP of the color measurement adjustment sheet CS to the color measurement control unit 106 as a color measurement target RGB value, that is, a device-dependent signal depending on the device. Further, the image processing unit 110 sends the image data (RGB value) of the patch of the reference chart KC to the color measurement control unit 106 as the reference RGB value RdsGdsBds at the time of color measurement. As shown in FIG. 15, the color measurement control unit 106 temporarily stores these color measurement target RGB values and color measurement reference RGB values RdsGdsBds in the frame memory 121 (step S11).

In the color measurement control unit 106, the color measurement value calculation unit 126 of the calculation unit 124 initializes the color measurement target RGB values stored in the frame memory 121 by using the reference RGB linear conversion matrix described later. Convert to RGB values RsGsBs (steps S12, S13).

The calculation unit 124 of the color measurement control unit 106 uses the converted initialization color measurement target RGB value RsGsBs as the color measurement target RGB value (step S14), executes the basic color measurement process described later, and executes L * a * b. * Acquire the colorimetric value (step S15).

Then, the image forming apparatus 1 of this embodiment is obtained by the colorimetric value calculation unit 126 of the calculation unit 124 processing the reference RGB linear conversion matrix as shown in FIGS. 16 and 17.

That is, as shown in FIG. 16, the color measurement value calculation unit 126 of the calculation unit 124 images the patch of the reference chart KC together with the image of the reference color patch KP of the reference sheet KS by the image pickup unit 30 at the initial stage. When the initial reference RGB value RdGdBd stored in the non-volatile memory 125 and the color measurement adjustment color patch CP of the color measurement adjustment sheet CS are imaged by the image pickup unit 30 at the time of color measurement, the patch of the reference chart KC is displayed together. Is imaged and the reference RGB value RdsGdsBds at the time of color measurement stored in the non-volatile memory 125 is read from the non-volatile memory 125. The color measurement value calculation unit 126 obtains a reference RGB linear conversion matrix for converting the color measurement reference RGB value RdsGdsBds into the initial reference RGB value RdGdBd, and stores the obtained reference RGB linear conversion matrix in the non-volatile memory 125.

That is, in FIG. 17, the points shown by the white dots in FIG. 17A are the points where the initial reference RGB value RdGdBd is plotted in the rgb space, and the filled points are the color measurement reference RGB values RdsGdsBds rgb. These are the points plotted in space. As can be seen from FIG. 17A, the value of the reference RGB value RdsGdsBds at the time of color measurement fluctuates from the value of the initial reference RGB value RdGdBd. The directions of fluctuation in these rgb spaces are substantially the same as shown by the arrows in FIG. 17 (b), but the directions of deviation differ depending on the hue. The reason why the RGB values fluctuate even if the patch of the same reference chart KC is imaged in this way is the time-dependent change of the illumination light source 37 and the time-dependent change of the two-dimensional image sensor 35.

In this way, the color measurement value is changed using the RGB value to be measured when the color measurement adjustment color patch CP of the color measurement adjustment sheet CS is imaged in a state where the patch of the same reference chart KC is fluctuating. If is obtained, there is a possibility that an error will occur in the color measurement value by the amount of fluctuation.

Therefore, the image forming apparatus 1 of the present embodiment initially sets the color measurement reference RGB value RdsGdsBds between the initial reference RGB value RdGdBd and the color measurement reference RGB value RdsGdsBds by using an estimation method such as the least squares method. The reference RGB linear conversion matrix to be converted to the reference RGB value RdGdBd is obtained. The image forming apparatus 1 uses this reference RGB linear conversion matrix to image the color measurement adjustment color patch CP of the color measurement adjustment sheet CS with the image pickup unit 30, and the color measurement target RGB stored in the non-volatile memory 125. The value is converted into the RGB value RsGsBs for initialization color measurement. The image forming apparatus 1 acquires the L * a * b * color measurement value by executing the basic color measurement process described later with the converted initialization color measurement target RGB value RsGsBs as the color measurement target RGB value.

This reference RGB linear conversion matrix may be a non-linear matrix of higher order as well as the first order, and when the non-linearity is high between the rgb space and the XYZ space, it may be a higher order matrix. , The conversion accuracy can be improved.

Then, the image pickup unit 30 takes an image of 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 32c formed in the bottom surface portion 32a. At this time, the imaging unit 30 also images the patch of the reference sheet KS arranged in the opening 32b of the bottom surface portion 32a of the housing 32. Therefore, the imaging unit 30 can always image 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 with the patch of the reference sheet KS as the subject in the same positional relationship. , It is possible to take an image in a stable state.

Further, the image pickup unit 30 has an optical path length 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 32c and the two-dimensional image sensor 35. The changing member 50 is arranged. The optical path length changing member 50 includes an optical path length (focal length) L from the color measurement adjustment color patch CP of the color measurement adjustment sheet CS, which is the subject, to the image sensor unit 34, and an optical path length from the reference chart KC to the image sensor unit 34. The refractive index n and the length Lp are set so that the (focal length) Lc matches. Therefore, the focal position of the reference chart KC with respect to the image sensor unit 34 can be matched with 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). As a result, the reference color patch KP of the reference sheet KS, the color measurement adjustment color patch CP of the color measurement adjustment sheet CS, and the reference chart KC to be compared with these are always and stably imaged with high accuracy and the same accuracy. be able to.

Further, the imaging unit 30 uses the same illumination light from the illumination light source 37 as the illumination light irradiating the imaging surface of the recording medium P through the optical path length changing member 50 and the slit 38a and the illumination light irradiating the reference chart KC. is there. Therefore, the image pickup unit 30 can take an image of the reference chart KC and the image pickup surface of the recording medium P together under the same illumination conditions. Further, two illumination light sources 37 are arranged on the center line Lo, which is a substantially intermediate position between the reference chart KC and the recording medium P, and two illumination light sources 37 are arranged on the center line Lo with respect to the lens 36. Therefore, the imaging unit 30 can uniformly illuminate the imaging region of the reference chart KC and the recording medium P under substantially the same illumination conditions.

Further, in the imaging unit 30, the arrangement conditions of the slit 38a in the imaging region and the reference chart KC are arranged substantially symmetrically with respect to the center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 line-symmetrically the same, and improve the accuracy of the color adjustment processing and the color measurement processing of the two-dimensional image sensor 35 using the reference chart KC. be able to.

Further, in the imaging unit 30, a reflection suppressing portion 40 is formed around the slit 38a. Therefore, the image pickup unit 30 can take an image while suppressing the influence of diffused reflection of the illumination light emitted from the illumination light source 37 on the color measurement target, and improve the image quality to improve the accuracy of the color adjustment process and the color measurement process. It can be further improved.

Further, as described above, in the imaging unit 30, the reflection suppressing portion 40 is provided in black. Therefore, the image pickup unit 30 can further suppress the influence of diffused reflection of the illumination light, and can easily and inexpensively perform black reference correction by utilizing the black color of the reflection suppression unit 40.

Then, the image forming apparatus 1 obtains the initial color measurement target RGB values RsGsBs as described above, and if the initial color measurement target RGB values are used as the color measurement target RGB values, the image forming apparatus 1 executes the basic color measurement processing as shown in FIGS. 18 and 19. That is, the image forming apparatus 1 is a reference in the vicinity of the reference color measurement values registered in the memory table Tb1 of the non-volatile memory 125, which are close in distance to the color measurement values converted into the color measurement target RGB values. A basic color measurement process is performed in which a color measurement value (neighborhood reference color measurement value) is selected and the color measurement value for converting the RGB value to be measured is converted into the selected neighborhood reference color measurement value. The image forming apparatus 1 improves the color reproducibility of the formed image by the image forming apparatus 1 by outputting an image by the recording head 20 based on the image data after performing the color conversion based on the colorimetric value. Let me.

That is, as shown in FIG. 18, 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 obtains the color measurement target RGB. As a value, it is stored in the non-volatile memory 125 (step S21). The image forming apparatus 1 then converts it into a first XYZ value (step S23) using the reference value linear conversion matrix (step S22), and stores it in the non-volatile memory 125 (step S24). For example, in FIG. 18, the color measurement value calculation unit 126 sets the color measurement target RGB values (3, 200, 5) of the image pickup unit 30 to the first XYZ values (first color measurement values) of (20, 80, 10). Is converted to and stored in the non-volatile memory 125.

The color measurement value calculation unit 126 uses the memory table Tb1 of the non-volatile memory 125 as a reference for the first XYZ value, or uses a known conversion formula to obtain the first L * a * b * value (first color measurement value). ) (Step S25) and stored in the non-volatile memory 125 (step S26). For example, in FIG. 16, the colorimetric value calculation unit 126 converts the first XYZ value (20, 80, 10) into the first L * a * b * value (75, -60, 8) which is an imaging colorimetric value. doing.

Next, the color measurement value calculation unit 126 refers to the color patches of a plurality of colors registered in the memory table Tb1 stored in the non-volatile memory 125, as shown in the L * a * b * space in FIG. Search for color measurement values (L * a * b * values). The color measurement value calculation unit 126 is a color patch of the reference color measurement values (L * a * b * values) that is closer to the first L * a * b * value in the L * a * b * space. A set of (neighborhood color patches) is selected (step S27). For example, in the figure of the L * a * b * space of FIG. 18, a figure in which 60 color patches are selected and plotted on the L * a * b * space is shown. The colorimetric value calculation unit 126 uses, for example, a first L * a * b * value and a reference colorimetric value (L * a * b * value) of a plurality of color patches as a method of selecting patches having a short distance. Calculate the distance to all points. When the color measurement value calculation unit 126 calculates the distance, the reference L * a * b * value of the color patch whose distance is close to the first L * a * b * value which is the first color measurement value (in FIG. 18). Select the hatched reference L * a * b * value).

Next, as shown in FIG. 19, the color measurement value calculation unit 126 refers to the memory table Tb1 and refers to the imaging reference RGB value that is paired with the first L * a * b * value of the selection set, that is, A combination of the imaging reference RGB value (selected RGB value) and the reference XYZ value having the same patch number as the first L * a * b * of the selection set is selected (step S28). The color measurement value calculation unit 126 obtains a selected RGB value linear conversion matrix for conversion between the imaging reference RGB and the reference XYZ pairs of the selected combination (selected set) by using the least squares method. The colorimetric value calculation unit 126 stores the obtained selected RGB value linear conversion matrix in the non-volatile memory 125 (step S29).

The color measurement value calculation unit 126 captures each color measurement adjustment color patch CP of the color measurement adjustment sheet CS, which is the color measurement target, with the imaging unit 30, and digitally converts the color measurement target RGB values into the selected RGB value linear. The second XYZ value, which is the second color measurement value, is obtained using the conversion matrix (step S30). The colorimetric value calculation unit 126 converts the obtained second XYZ value into a second L * a * b * value using a known conversion formula (step S31), and acquires it as the final colorimetric value (step S32). ).

The colorimetric value calculation unit 126 adjusts the image based on the image data obtained by color conversion using the obtained colorimetric value, and drives the recording head 20 based on the image-adjusted image data to form an image.

That is, when the image forming apparatus 1 of this embodiment captures and acquires a plurality of color measurement adjustment color patch CPs of the color measurement adjustment sheet CS that reflects the output characteristics of the recording head 20 at the color adjustment processing timing. The first L * a * b * value of the RGB value to be measured is obtained when the reference sheet KS is imaged in the initial state using the reference value linear conversion matrix. The image forming apparatus 1 has a distance to the first L * a * b * value in the L * a * b * space of the reference L * a * b * of the patches of a plurality of colors registered in the memory table Tb1. Select a patch set with a reference L * a * b * value that is close to. The image forming apparatus 1 converts the color measurement target RGB value corresponding to the selected reference L * a * b * value into an L * a * b * value using the selected RGB value linear conversion matrix, thereby converting the L * The a * b * color measurement value is calculated. Then, the colorimetric value calculation unit 126 adjusts the image based on the image data obtained by color conversion using the obtained colorimetric value, and drives the recording head 20 based on the image-adjusted image data to form an image. To do.

As described above, the image pickup unit 30 of the image forming apparatus 1 of the present embodiment has a housing 32 having a slit (opening) 38a and an image sensor unit (sensor means) for imaging a subject outside the housing 32 through the slit 38a. ) 34, a reference chart KC composed of a plurality of colors arranged in the housing 32 and imaged by the image sensor unit 34 together with the subject, and a surface around the slit 38a of the housing 32 on the image sensor unit 34 side. The reflection suppressing unit (reflection suppressing means) 40 provided in the above is provided.

Therefore, it is possible to suppress the influence of diffused reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject, and it is possible to image the subject with high accuracy and improve the imaging quality of the subject.

Further, the image forming apparatus 1 of the present embodiment is based on an imaging means that captures an arbitrary subject together with a reference chart KC composed of a plurality of colors, and imaging data of the subject and the reference chart KC imaged by the imaging means. It is a color measurement device including a color measurement control unit (calculation means) 106 for calculating a color measurement value of a subject, and the image pickup unit 30 is provided as the image pickup means.

Therefore, the influence of the diffused reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed, and the subject can be imaged with high accuracy, and the image quality of the subject can be improved with high accuracy. The color can be measured.

Further, the image forming apparatus 1 of the present embodiment is an image forming apparatus that forms an image using image data whose color is adjusted based on the colorimetric value measured by the colorimetric apparatus, and the colorimetric apparatus includes the image forming apparatus 1. It is equipped with the above color measuring device.

Therefore, it is possible to suppress the influence of diffused reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject, to image the subject with high accuracy, measure the color with high accuracy, and obtain a high quality image. Can be formed.

Further, the color measuring device of the image forming apparatus 1 of this embodiment is formed on a reference chart plate (predetermined plate member) 38 together with a reference chart KC composed of a plurality of colors, and is subjected to reflection suppression processing by a reflection suppression unit 40 around it. An imaging process step of imaging an arbitrary subject through the slit (opening) 38a provided to acquire the RGB value of the reference chart KC and the RGB value of the subject, and each color of the reference color patch composed of a plurality of colors. With the reference color measurement value which is the color measurement value in a predetermined color space independent of the device and the RGB value of each color of the reference color patch acquired by being imaged in the imaging process step with the reference color patch as the subject. A certain imaging reference RGB value is stored in a non-volatile memory (reference value storage means) 125 in association with an initial reference RGB value which is an RGB value of the reference chart KC acquired by being imaged in the imaging processing step together with the reference color patch. The reference value storage processing step, the RGB value for color measurement acquired by imaging a predetermined subject for color measurement in the imaging processing step, and the RGB of the reference chart KC imaged together with the imaging of the subject for color measurement. A color measurement RGB value storage processing step for storing a color measurement reference RGB value in a non-volatile memory (color measurement RGB value storage means) 125, and the color measurement reference RGB value as the initial reference RGB value. The RGB value for color measurement is converted into the RGB value for initialization color measurement by using the reference RGB linear conversion matrix generation processing step for generating the reference RGB linear conversion matrix to be converted and the reference RGB linear conversion matrix. The RGB value conversion processing step, the reference value linear conversion matrix calculation processing step for calculating the reference value linear conversion matrix for converting the imaging reference RGB value into the reference color measurement value, and the reference value linear conversion matrix are used to describe the above. The imaging color measurement value calculation processing step of converting the RGB value for initialization color measurement converted in the RGB value conversion processing step into an imaging color measurement value to obtain an imaging color measurement value, and the imaging color measurement value from the reference color patch. And the patch selection processing step of selecting a predetermined number of reference color patches having a close distance in the predetermined color space, and the RGB value for color measurement corresponding to the selected predetermined number of reference color patches as the selected RGB value. Using the selected RGB selection processing step, the selected RGB value linear conversion matrix calculation processing step for calculating the selected RGB value linear conversion matrix for converting the selected RGB value into the reference color measurement value, and the selected RGB value linear conversion matrix. Therefore, a color measurement method including a color measurement value conversion processing step for converting the RGB value of the color measurement subject acquired in the image pickup processing step into a color measurement value is executed.

Therefore, the influence of the diffused reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed, and the subject can be imaged with high accuracy, and the image quality of the subject can be improved with high accuracy. The color can be measured.

Further, the image pickup unit 30 of the image forming apparatus 1 of the present embodiment is a black surface on which the reflection suppression portion 40 is provided on the surface of the image sensor portion 34 side around the slit 38a.

Therefore, the influence of diffused reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed easily and inexpensively, the subject can be imaged inexpensively and with high accuracy, and the black surface is blackened. By using it for reference correction, black reference correction can be easily and appropriately performed.

Further, in the image pickup unit 30 of the image forming apparatus 1 of this embodiment, the housing 32 is grayed out over a predetermined range on the outer circumference of the reflection suppression unit 40.

Therefore, the reflected light from the periphery of the slit 38a can be further reduced, and the subject can be imaged with higher accuracy.

Further, in the image pickup unit 30 of the image forming apparatus 1 of this embodiment, the gray color on the outer periphery of the reflection suppression unit 40 is a color data value that exceeds the maximum value of the color data of the color of the reference chart KC.

Therefore, the gray area, the reference chart KC, and the black area around the slit 38a can be divided by the threshold value of the color data, and shading correction can be performed in the gray area. As a result, the color measurement accuracy can be further improved when color measurement is performed using the image pickup unit 30.

Further, in the image pickup unit 30 of the image forming apparatus 1 of the present embodiment, the slit 38a and the reference chart KC are provided side by side at a predetermined interval on the reference chart plate (plate-shaped member) 38 to which the slit 38a and the reference chart KC are detachably attached to the housing 32. Has been done.

Therefore, the reference chart KC and the periphery of the slit 38a can always be kept in a normal state, and the subject can be imaged with even higher accuracy.

In this case, when the focal length of the reference chart KC and the subject such as the recording medium P to the image sensor unit 34 can be ignored in terms of accuracy, the imaging unit 30 changes the optical path length as shown in FIGS. 20 and 21. The member 50 may not be provided. Also in this case, as shown in FIG. 21, a reflection suppressing portion 40 such as black is provided around the slit 38a formed in the reference chart plate 38. In FIGS. 20 and 21, the same reference numerals are given to the same components as those in FIGS. 4 to 6, and the description thereof will be omitted.

By doing so, it is possible to more inexpensively and surely prevent the influence of the reflected light around the slit 38a on the captured image.

Further, the optical path changing member is not limited to the one provided only on the opening 32c (slit 38a) side, and may be provided on the opening 32b side as well.

Further, in the above embodiment, the slit 38a which is an opening is formed in the reference chart plate 38 provided with the reference chart KC, but the slit 38a needs to be formed in the reference chart plate 38. Absent. For example, the slit 38a may be formed directly on the bottom surface portion 32a of the housing 32 independently of the reference chart plate 38, or may be formed on a plate member provided in the opening 32c.

Further, in the above description, the color measurement process is performed by the color measurement control unit 106 of the image forming apparatus 1, but the color measuring process does not need to be executed inside the image forming apparatus 1. For example, FIG. 22 shows. As shown, as an image forming system (color measuring system) 200, an image forming device 210 is connected to an external device 220, and image data captured by the image forming device 210 is output to the external device 220, and the image data is output to the external device 220. The external device 220 performs color adjustment processing accompanied by color measurement processing, outputs the image data after color adjustment to the image forming device 210, and the image forming device 210 forms an image based on the image data from the external device 220. You may.

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. Further, the external device 220 can use, for example, a computer having a normal hardware configuration and a software configuration, and is a color adjustment program including a color measurement program that executes a color adjustment process accompanied by the color measurement process of the present invention as software. By introducing, color adjustment processing accompanied by color measurement processing is executed. 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 device 220 by the line 230 by the I / F unit 213, and the line 230 is a dedicated line, a network such as a LAN (Local Area Network), the Internet, or the like, and is wired. It may be wireless.

Under the control of the external device 220, the image forming device 210 forms and outputs an image on a recording medium by the engine 211 based on the image data sent from the external device 220. The engine 211 forms an image on a recording medium by an ink injection 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 is necessary for the operation of the image forming apparatus 210. Various operations are performed by the operation keys, and various information notified to the user from the image forming apparatus 210 is displayed and output on the display. Other I / F unit 214 is used for connecting expansion units and the like.

The engine 211 includes a carriage that moves in the same main scanning direction as described in the above embodiment, and the image pickup unit 30 is attached to the carriage. The image forming apparatus 210 forms the color measuring adjustment color patch CP on the recording medium based on the color patch data of the color measuring adjusting color patch CP sent from the external device 220 under the control of the CPU 221 of the external device 220. To generate the colorimetric adjustment sheet CS. The image forming apparatus 210 reads the colorimetric adjustment color patch CP of the generated colorimetric adjustment sheet CS by the image pickup unit 30 and transmits the colorimetric adjustment color patch CP to the external device 220 via the I / F unit 213.

The external device (calculation means) 220 stores an image formation control program that controls the operation of the image forming device 210, a color adjustment program that performs color adjustment processing accompanied by the color measurement processing of the present invention, and necessary data in the hard disk 229 or ROM 227. Has been done. In the external device 220, the CPU 221 controls the image forming apparatus 210 based on the program in the ROM 227 or the hard disk 229 to execute the basic processing as the image forming apparatus 210, and the color adjustment accompanied by the color measurement processing of the present invention. Execute the process.

The hard disk 229 stores the above program and also stores various data necessary for executing the color adjustment process. In particular, the hard disk 229 has at least one of the L * a * b * values and the XYZ values of the color measurement results of the plurality of reference color patches KP arranged in the reference sheet KS described in the above embodiment. Imaging reference RGB value when the reference patch KP of the reference sheet KS is read by the imaging unit 30 of the image forming apparatus 210, reference value linear conversion matrix, table of neighboring points and selected RGB value linear conversion matrix, together with reference sheet KS. Read reference chart Initial reference RGB value RdGdBd of each color patch of KC, color measurement adjustment color patch of color measurement adjustment sheet CS Reference chart read together with KC reference patch Color measurement reference RGB value RdsGdsBds And the reference RGB linear conversion matrix for converting the reference RGB value RdsGdsBds at the time of color measurement into the initial reference RGB value RdGdBd is stored.

The communication I / F unit 224 is connected to an image processing device such as a scanner device, a composite device, or another external device via a line such as a network, and receives image data to be output by the image forming device 210. The I / F unit 213, the I / F unit 224, and the line 230 function as a communication means as a whole.

The image processing unit 223 performs various image processing necessary for forming and outputting the image data by 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 the color measurement process executed by the calculation unit 124 of the color measurement control unit 106, particularly the color measurement value calculation unit 126, to perform the color measurement value. Ask for. The CPU 221 performs color adjustment on the image data based on the obtained colorimetric value, and outputs the image data to the image forming apparatus 210.

In the image forming system 200 of FIG. 22, the operation of the image forming device 210 is controlled by the external device 220, but the form of the image forming system 200 is not limited to this form. For example, in the image forming system 200, the image forming apparatus 210 itself includes a controller such as a CPU, and the controller controls the image forming operation itself, and only the color measuring process for obtaining the color measurement value, or the color measurement. The external device 220 may execute only the color adjustment process including the process.

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

Although the invention made by the present inventor has been specifically described above based on suitable examples, the present invention is not limited to the ones described in the above examples, and various modifications are made without departing from the gist thereof. It goes without saying that it is possible.

1 Image forming device 2 Main body housing 3 Main body frame 4 Main guide rod 5 Secondary guide rod 6 Carriage 6a Connecting piece 7 Timing belt 8 Drive pulley 9 Driven pulley 10 Main scanning motor 11 Cartridge part 12 Maintenance mechanism part 13 Cover 14 Platen 15 Encoder Sheet 20, 20y, 20m, 20c, 20k Recording head 21 Encoder sensor 30 Imaging unit 31 Top cover 32 Housing 32a Bottom 32b Opening 32c Opening 32d Recess 32e Recess 32f Communication port 33 Fastening member 34 Image sensor 35 2D Image sensor 36 Lens 37 Illumination light source 38 Reference chart plate 38a Slit 39 Holding plate 39a Opening 40 Reflection suppression unit 50 Optical path length changing member 101 CPU
102 ROM
103 RAM
104 Main scanning driver 105 Recording head driver 106 Color measurement control unit 107 Paper transport unit 108 Secondary scanning 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 Color measurement value calculation unit 200 Image formation system 210 Image formation device 211 Engine 212 Operation display unit 213 I / F unit 214 Others I / F section 215 Bus 220 External device 221 CPU
222 Memory section 223 Image processing section 224 Communication I / F section 225 I / F section 226 Bus 227 ROM
228 RAM
229 Hard disk 230 Line P Recording medium Lo Center line KS Standard sheet KP Standard color patch CS Color measurement adjustment sheet CP Color measurement adjustment patch KC Standard chart Pa to Pd Standard color patch line Pe Dot diameter measurement pattern line lk Distance measurement line mk Chart position identification marker Tb1 memory table

Japanese Unexamined Patent Publication No. 2012-063270

Claims (15)

An image pickup device having a two-dimensional image sensor and an opening .
Among the images before Symbol 2-dimensional image sensor is captured, the shading correction data in the first region including the object of color measurement position through the opening, and the base of the shading correction data of said first region Shading correction data creation unit created based on the image data of the color
A correcting unit that corrects at the shading correction data for the previous SL the object of color measurement data area smaller than the first region in the first region,
To prepare
An imaging device characterized by this. The imaging device includes an illumination light source that illuminates the imaging region of the two-dimensional image sensor.
The imaging device according to claim 1 . The shading correction data is correction data for correcting illuminance unevenness in the imaging region of the two-dimensional image sensor.
The imaging device according to claim 1 or 2 . The narrow area is the area inside the opening.
The imaging device according to any one of claims 1 to 3 , wherein the imaging device is characterized by the above. The perimeter of the opening is black.
The imaging device according to claim 4 , wherein the image pickup apparatus is characterized by the above. A region outside the black region with respect to the opening is included in the first region.
The image pickup apparatus according to claim 5 . The outer region adjacent to the black region with respect to the opening is gray.
The imaging device according to claim 5 or 6 , characterized in that. The correction unit corrects the data obtained from the black region as a black level.
The imaging device according to any one of claims 5 to 7 . The imaging device includes a reference chart imaged by the two-dimensional image sensor.
The area around the reference chart is included in the first area.
The imaging device according to any one of claims 1 to 8 , wherein the imaging device is characterized by the above. The correction unit corrects at least the data of the reference chart in the image captured by the two-dimensional image sensor.
9. The imaging device according to claim 9 . The two-dimensional image sensor captures an image of a white plate through the opening.
The shading correction data creation unit creates the shading correction data based on the data of the first area including the data obtained by imaging the white plate,
The imaging device according to any one of claims 4 to 8 . The imaging device according to any one of claims 1 to 11 .
An image forming unit that forms the colorimetric object with respect to the object,
A moving unit that relatively moves the image pickup device and the color measurement target,
An image forming apparatus characterized by being provided. The imaging device according to any one of claims 1 to 11 .
An image forming unit that forms the colorimetric object with respect to the object,
An image forming apparatus comprising. The imaging device according to any one of claims 1 to 11 .
A recording head that forms the colorimetric object with respect to the object,
A carriage equipped with the recording head and
With
The imaging device is attached to the carriage.
An image forming apparatus characterized in that. Of the images captured by the two- dimensional image sensor, the shading correction data of the first region including the color measurement target located through the opening is the base color of the shading correction data in the first region. Steps to create based on image data and
Among the images the two-dimensional image sensor is captured, and correcting by the shading correction data to said first of said colorimetric target data area smaller than the area of said first region,
including,
A color measurement method characterized by that.