JP5784289B2 - Image density measuring apparatus, image forming apparatus, and image density measuring method - Google Patents

Description

  The present invention relates to an image density measuring apparatus, an image forming apparatus, and an image density measuring method.

  Conventionally, an electrophotographic image forming apparatus forms an image by mixing four primary colors of CMYK, which are primary colors in subtractive color mixing. In such an image forming apparatus, the density of the image on the paper is not always the same even if the image forming conditions are the same due to the difference in the characteristics of the output paper such as whiteness and gloss. An image forming apparatus that reads an image formed on a sheet with a monochrome density sensor and performs image stabilization processing such as γ correction is known.

  In the single-color density sensor used in such image stabilization processing, all the RGB colors as the secondary colors obtained by mixing two of the primary colors of CMY and all of the primary colors of CMY are obtained. The process black as a tertiary color obtained by mixing the colors cannot be read as a color image signal. Therefore, in practice, it is estimated that the above-described mixed color image of the secondary color or higher will approach an ideal state by performing the above-described CMYK primary color image stabilization process. In general, there is no care for image stabilization of a mixed color image of secondary or higher colors.

  However, in reality, the primary color is corrected to the ideal state even if the primary color is corrected to the ideal state by changing the image forming process state such as transfer or fixing of the toner material to the paper. It is not always done.

  On the other hand, for example, a color chart composed of color patch images of about 1000 colors is output, and each of these is measured offline to regenerate a color profile, thereby stabilizing an image of primary colors or mixed colors. This is a time-consuming and labor-intensive operation such as output of a color chart, colorimetry operation, and profile generation.

  In view of such problems, in conventional image forming apparatuses, color patches from primary colors to tertiary colors are formed on paper, and LEDs of three colors RGB are turned on for the color patches passing through predetermined positions. In other words, the light is received by a light receiving unit with a filter that is spectrally separated into RGB and the hue of a color patch is detected (for example, Patent Document 1).

JP 2004-212893 A

  However, in the technique described in Patent Document 1, color correction from the primary color to the tertiary color can be performed by a simple method. However, the light sources of the RGB three-color LEDs irradiate the same position. Since the reflected light is received by the light receiving unit, it is necessary to control the lighting of the light source to be irradiated according to the color patch to be read, and the control becomes complicated. Also, the amount of light output differs greatly between reading a color patch with a single color LED and reading a color patch with all the LEDs emitting light. That is, compared to reading the primary color patch, when reading the secondary and tertiary color patches, the number of LEDs to be lit increases and the amount of light increases. Therefore, it is necessary to adjust the output of the LED, and during that time, image formation cannot be performed, so that there is a problem that productivity is lowered.

  An object of the present invention is to provide an image density measuring apparatus, an image forming apparatus, and an image density measuring method capable of reading a color image by a simple method and suppressing a decrease in productivity.

In order to solve the above-described problems, the invention described in claim 1 includes a cyan color patch composed of cyan, a magenta color patch composed of magenta, a yellow color patch composed of yellow, a cyan color, In an image density measuring device for reading density information of each color patch by reading red, green, and blue mixed color patches in which two or more of magenta and yellow are mixed,
The cyan color patch, the red color, and the green color are emitted by emitting red light toward the color patch, receiving the light reflected by the color patch, and outputting a signal corresponding to the amount of the received light. A first reading unit that reads a mixed color patch of color and blue ,
Green light is emitted toward the color patch, light reflected by the color patch is received, and a signal corresponding to the amount of the received light is output, whereby the magenta color patch, the red color, and the green color are output. A second reading unit that reads a mixed color patch of color and blue ,
By emitting blue light toward the color patch, receiving the light reflected by the color patch, and outputting a signal according to the amount of the received light, the yellow color patch, the red color, and the green color A third reading unit for reading a mixed color patch of color and blue ,
A density information acquisition unit that obtains density information of each color patch from signals respectively output from the first reading unit, the second reading unit, and the third reading unit;
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. A control unit that performs composition processing for specifying the color of the mixed color patch of the red color, the green color, and the blue color that has been read and combined at a ratio;
With
The color patch is read by the first reading unit, the second reading unit, and the third reading unit at different positions, respectively.

According to a second aspect of the present invention, in the image forming apparatus,
And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming unit that forms a mixed color patch of green and blue on a recording medium,
A first reading unit that emits red light toward a color patch passing through the first reading position, receives light reflected by the color patch, and outputs a signal corresponding to the amount of the received light When,
Green light is emitted toward a color patch passing through a second reading position different from the first reading position in the main scanning direction in the recording medium, and the light reflected by the color patch is received; A second reading unit that outputs a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position different from the first reading position and the second reading position in the main scanning direction on the recording medium. A third reading unit that receives the reflected light and outputs a signal according to the amount of the received light;
A density information acquisition unit for obtaining color patch density information from signals output from the first reading unit, the second reading unit, and the third reading unit;
With
The image forming unit passes the cyan color patch at the first reading position, the magenta color patch at the second reading position, and the yellow color patch at the third reading position. As described above, the cyan color patch, the magenta color patch, and the yellow color patch are formed on the recording medium, and the mixed color patch of red, green, and blue is the first reading position, Forming a mixed color patch of red, green and blue on the recording medium so as to pass through the second reading position and the third reading position,
The density information acquisition unit obtains density information of the cyan color patch from the signal output from the first reading unit, and obtains density information of the magenta color patch from the signal output from the second reading unit. The density information of the yellow color patch is obtained from the signal output from the third reading unit, and from the signals output from the first reading unit, the second reading unit, and the third reading unit, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. The image processing apparatus includes a control unit that performs a combining process of specifying the colors of the mixed color patches of the red color, the green color, and the blue color that are combined at a ratio and read .

According to a third aspect of the present invention, in the image forming apparatus,
And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming unit that forms a mixed color patch of green and blue on a recording medium,
A first reading unit that emits red light toward a color patch passing through the first reading position, receives light reflected by the color patch, and outputs a signal corresponding to the amount of the received light When,
Green light is emitted toward a color patch that passes through a second reading position that is the same as the first reading position in the main scanning direction and different in the sub-scanning direction on the recording medium, and is reflected by the color patch. A second reading unit that receives the received light and outputs a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position that is the same as the first scanning position and the second reading position in the main scanning direction and different in the sub-scanning direction in the recording medium. A third reading unit that receives the light reflected by the color patch and outputs a signal corresponding to the amount of the received light;
A density information acquisition unit for obtaining color patch density information from signals output from the first reading unit, the second reading unit, and the third reading unit;
With
The image forming unit passes the first reading position, the second reading position, and the third reading position so that the cyan color patch, the magenta color patch, and the yellow color color are passed. Forming patches and mixed color patches of red, green and blue on the recording medium,
The density information acquisition unit obtains density information of the cyan color patch from the signal output from the first reading unit, and obtains density information of the magenta color patch from the signal output from the second reading unit. The density information of the yellow color patch is obtained from the signal output from the third reading unit, and from the signals output from the first reading unit, the second reading unit, and the third reading unit, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. The image processing apparatus includes a control unit that performs a combining process of specifying the colors of the mixed color patches of the red color, the green color, and the blue color that are combined at a ratio and read .

According to a fourth aspect of the present invention, there is provided a cyan color patch composed of a cyan color, a magenta color patch composed of a magenta color, a yellow color patch composed of a yellow color, and a cyan color, a magenta color and a yellow color. In an image density measurement method for obtaining density information of each color patch by reading a red, green, and blue mixed color patch in which two or more colors are mixed,
By emitting red light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal according to the amount of the received light, the cyan color patch, the red color, and the green color A first reading step for reading a blue mixed color patch;
The magenta color patch, the red color, and the green color are emitted by emitting green light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light. A second reading step for reading a blue mixed color patch;
By emitting blue light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal according to the amount of the received light, the yellow color patch, the red color, and the green color A third reading step for reading a blue mixed color patch;
A density information acquisition step of obtaining density information of each color patch from the signals respectively obtained in the first reading step, the second reading step, and the third reading step;
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. A synthesis processing step for specifying the color of the mixed color patch of the red color, the green color, and the blue color that has been read,
Including
The color patch reading in the first reading step, the color patch reading in the second reading step, and the color patch reading in the third reading step are performed at different positions, respectively. Features.

The invention according to claim 5 is an image density measurement method,
And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming process for forming green, blue mixed color patches on a recording medium,
A first reading step of emitting red light toward the color patch passing through the first reading position, receiving light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light; ,
Green light is emitted toward a color patch passing through a second reading position different from the first reading position in the main scanning direction in the recording medium, and the light reflected by the color patch is received; A second reading step for obtaining a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position different from the first reading position and the second reading position in the main scanning direction on the recording medium. A third reading step of receiving the reflected light and obtaining a signal according to the amount of the received light;
A density information acquisition step of obtaining color patch density information from the signals obtained in the first reading step, the second reading step and the third reading step, respectively;
Including
In the image forming step, the cyan color patch passes through the first reading position, the magenta color patch passes through the second reading position, and the yellow color patch passes through the third reading position. As described above, the cyan color patch, the magenta color patch, and the yellow color patch are formed on the recording medium, and the mixed color patch of red, green, and blue is the first reading position, Forming a mixed color patch of red, green and blue on the recording medium so as to pass through the second reading position and the third reading position,
In the density information acquisition step, density information of the cyan color patch is obtained from the signal obtained in the first reading step, and density information of the magenta color patch is obtained from the signal obtained in the second reading step. The density information of the yellow color patch is obtained from the signal obtained in the third reading step, and from the signals obtained in the first reading step, the second reading step, and the third reading step, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. And a synthesis processing step of specifying the color of the mixed color patch of the red color, green color, and blue color that has been read and synthesized .

The invention according to claim 6 is an image density measuring method,
And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming process for forming green, blue mixed color patches on a recording medium,
A first reading step of emitting red light toward the color patch passing through the first reading position, receiving light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light; ,
Green light is emitted toward a color patch that passes through a second reading position that is the same as the first reading position in the main scanning direction and different in the sub-scanning direction on the recording medium, and is reflected by the color patch. A second reading step of receiving the received light and obtaining a signal according to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position that is the same as the first scanning position and the second reading position in the main scanning direction and different in the sub-scanning direction in the recording medium. A third reading step of receiving light reflected by the color patch and obtaining a signal corresponding to the amount of the received light;
A density information acquisition step of obtaining color patch density information from the signals obtained in the first reading step, the second reading step and the third reading step, respectively;
Including
In the image forming step, the cyan color patch, the magenta color patch, and the yellow color color so as to pass through the first reading position, the second reading position, and the third reading position. Forming patches and mixed color patches of red, green and blue on the recording medium,
In the density information acquisition step, density information of the cyan color patch is obtained from the signal obtained in the first reading step, and density information of the magenta color patch is obtained from the signal obtained in the second reading step. The density information of the yellow color patch is obtained from the signal obtained in the third reading step, and from the signals obtained in the first reading step, the second reading step, and the third reading step, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. And a synthesis processing step of specifying the color of the mixed color patch of the red color, green color, and blue color that has been read and synthesized .

  According to the present invention, it is possible to read a color image by a simple method and to suppress a decrease in productivity.

1 is a block diagram illustrating a functional configuration of an image forming apparatus according to a first embodiment. It is a schematic sectional drawing of an image formation part and a relay unit. It is a schematic block diagram of a density | concentration detection part. It is a figure explaining the center wavelength of a light emitting element. It is a figure which shows the example of a gradation pattern image. It is a figure which shows the example of a gradation pattern image. It is a figure explaining the procedure of the reading of the gradation pattern image in 1st Embodiment. It is a schematic block diagram of the density | concentration detection part in 2nd Embodiment. It is a figure which shows the example of a gradation pattern image. It is a figure which shows the example of a gradation pattern image. It is a figure explaining the procedure of the reading of the gradation pattern image in 2nd Embodiment. It is a figure explaining the relationship of the output value of a monochrome density sensor with respect to the neutral gray input gradation. It is a graph explaining the relationship of the output value of a monochrome density sensor with respect to the neutral gray input gradation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The scope of the invention is not limited to the illustrated example.

(First embodiment)
FIG. 1 shows a functional configuration of an image forming apparatus 100 according to the first embodiment of the present invention. The image forming apparatus 100 is a multifunction machine having a copy function, an image reading function, and a printer function, and is an electrophotographic color image forming apparatus.

  For example, as illustrated in FIG. 1, the image forming apparatus 100 includes a control unit 10, an operation display unit 20, an image reading unit 30, an image forming unit 40, a relay unit 50, a density detection unit 60, a storage unit 70, and a communication unit 80. Etc., and each part is connected by a bus.

  The control unit 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In response to an operation signal input from the operation display unit 20 or an instruction signal received by the communication unit 80, the CPU reads the system program and various processing programs stored in the ROM, expands them in the RAM, and expands them. The operation of each part of the image forming apparatus 100 is centrally controlled according to the program.

  The operation display unit 20 is configured by an LCD (Liquid Crystal Display), and displays various operation buttons, device status display, operation status of each function, and the like on the display screen according to instructions of a display signal input from the control unit 10. Do. The LCD display screen is covered with a pressure-sensitive (resistive film pressure) touch panel that consists of transparent electrodes arranged in a grid, and detects the position coordinates pressed by a finger or touch pen as a voltage value. The detected position signal is output to the control unit 10 as an operation signal. The operation display unit 20 includes various operation buttons such as a numeric button and a start button, and outputs an operation signal generated by the button operation to the control unit 10.

The image reading unit 30 includes a scanner below the contact glass on which the document is placed, and reads an image of the document. The scanner includes a light source, a CCD (Charge Coupled Device) image sensor, an A / D converter, and the like, and forms an image of reflected light of light scanned from the light source onto the document and photoelectrically converts the image of the document to RGB The data is read as a signal, and the read image is A / D converted to generate image data.

The image forming unit 40 forms and outputs an image on a sheet based on image data of yellow (Y), magenta (M), cyan (C), and black (K) by electrophotography.
As shown in FIG. 2, the image forming unit 40 includes Y, M, C, and K photoconductive drums 41Y, 41M, 41C, and 41K, primary transfer rollers 42Y, 42M, 42C, and 42K, an intermediate transfer belt 43, The apparatus includes a roller 44, a registration roller 45, a secondary transfer roller 46, a fixing unit 47, a paper feed unit 48, and the like.

Here, image formation in the image forming unit 40 will be described.
The photosensitive drum 41Y rotates, the surface thereof is charged by a charger (not shown), and a latent image of an image of Y data is formed on the charged portion by exposure of a laser light source (not shown). Then, a yellow toner image is formed on the latent image portion by a developing device (not shown). The toner image is transferred to the intermediate transfer belt 43 by the pressure contact of the primary transfer roller 42Y. The toner image is a yellow image corresponding to the image data to be output. The toner that has not been transferred is removed by a cleaner (not shown).
Magenta, cyan, and black toner images are formed and transferred in the same manner.

  The intermediate transfer belt 43 is rotated by the rotation of the roller 44 and the primary transfer rollers 42Y, 42M, 42C, and 42K, and the YMCK toner images are sequentially superimposed and transferred onto the intermediate transfer belt 43. The paper feeding unit 48 includes a plurality of paper feeding trays, and supplies the paper stored in the paper feeding trays to the image forming unit 40. The paper supplied from each paper supply tray of the paper supply unit 48 is conveyed to the secondary transfer roller 46 by the rotation of the registration roller 45.

  As the registration roller 45 and the secondary transfer roller 46 rotate, the sheet passes through the pressure contact portion of the secondary transfer roller 46, whereby the YMCK toner image on the intermediate transfer belt 43 is transferred to the sheet. The sheet on which the YMCK toner image is transferred passes through the fixing unit 47. By the pressurization and heating of the fixing unit 47, the YMCK toner image is fixed on the paper to form a color image. The sheet on which the image is formed is discharged to the relay unit 50.

  In addition, when performing duplex printing, a secondary transfer roller is formed by a registration roller 45 so that a sheet on which an image is formed on one side is reversed by a duplex conveyance unit (not shown) and an image is formed again on a surface on which no image is formed. It is conveyed to 46.

  The relay unit 50 has a function of receiving paper discharged from the image forming unit 40 and sending it out for subsequent processing. The relay unit 50 is provided with a concentration detector 60 in the path. Further, the relay unit 50 may include a finisher function for performing each process such as a punching process, a folding process, and a cutting process.

The density detection unit 60 outputs a voltage value corresponding to the density of each patch of the gradation pattern image on the fixed paper on which the image is formed by the image forming unit 40 to the control unit 10 as an image density signal.
The control unit 10 detects the density of each patch based on the voltage value output from the density detection unit 60.

  FIG. 3 shows a schematic configuration of the concentration detection unit 60. FIG. 3A is an enlarged plan view of the concentration detection unit 60 provided on the conveyance path C. FIG.

Density detecting unit 60, as shown in FIG. 3 (a), the monochrome density sensor (R) 61R, monochrome density sensor (G1) 61G _1, the monochrome density sensor (B) 61B and the monochrome density sensor (G2) 61G ₂ They are arranged at predetermined intervals in parallel with the main scanning direction of the paper P. Note that the arrangement of the monochrome density sensors is not limited to that described above, and can be arranged in any arrangement. In the first embodiment, the monochrome density sensor (R) 61R, the monochrome density sensor (G1) 61G ₁ , the monochrome density sensor (B) 61B, and the monochrome density sensor (G2) 61G ₂ are each at least in the main scanning direction. As long as they are arranged at different positions, they may be arranged shifted in the sub-scanning direction.
FIG. 3B shows a schematic side view of the monochrome density sensor (R) 61R. The monochromatic density sensor (R) 61R, the monochromatic density sensor (G1) 61G ₁ , the monochromatic density sensor (B) 61B, and the monochromatic density sensor (G2) 61G ₂ all have the same configuration. Only the schematic configuration of the density sensor (R) 61R will be described, and the description of the other monochrome density sensors will be omitted.

The monochrome density sensor (R) 61R includes an LED (Light Emitting Diode) 62R, a lens 63R, a light receiving element 64R, a white reference plate 65R, a reference plate cover 66R, and the like.
The LED 62R is a light emitter that emits red light. Note that the monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (G2) 61G _2, respectively, LED62G _1, 62G ₂ is a light-emitting body emitting green light is provided, the monochrome density sensor (B) 61B is An LED 62B, which is a light emitting body that emits blue light, is provided. The center wavelengths of the light emitted from the LEDs 62R, 62G ₁ , 62B, and 62G ₂ are different for each color as shown in FIG. 4, and the red light output by the LED 62R is easily absorbed by cyan, The green light output from the LEDs 62G ₁ and 62G ₂ is easily absorbed in magenta, and the blue light output from the LED 62B is easily absorbed in yellow. In other words, a color complementary to the emission color has a characteristic of easily absorbing light. Note that the black color has a characteristic of absorbing light of any color. In the present embodiment, as described later, in consideration of the above-described characteristics, the monochrome density sensor (R) 61R, the monochrome density sensor (G1) 61G ₁ , the monochrome density sensor (B) 61B, and the monochrome density sensor ( as color patches corresponding to the emission color of the LED provided respectively G2) 61G ₂ is read by the monochrome density sensor is configured to gradation pattern image is generated. In this embodiment, an LED is applied as a light emitter to be used, but other light emitting elements such as EL (Electronic Luminescence) may be applied.

  The lens 63R collects light from the LED 62R. The light receiving element 64R is constituted by a photodiode, for example, and converts the amount of received light into a voltage value and outputs the voltage value. The white reference plate 65R is a reflecting plate for reflecting the light from the LED 62R without absorbing it, and is used to calibrate the LED described later. The reference plate cover 66R prevents the white reference plate 65R from being soiled by paper dust or the like from the paper when the white reference plate 65R is not used. The reference plate cover 66R is displaced from the covering position of the white reference plate 65R to the open position when the white reference plate 65R is used.

The monochrome density sensor (R) 61R configured as described above emits light from the LED 62R to each patch passing through the measurement position DR on the paper P on which the gradation pattern image conveyed on the conveyance path C is formed. The reflected light is received by the light receiving element 64R through the lens 63R. The light receiving element 64 </ b> R outputs a voltage value as an image density signal corresponding to the amount of reflected light to the control unit 10. Based on this image density signal, the output value from the monochrome density sensor (R) 61R, that is, the density of the measured image is specified. In the present embodiment, the gradation pattern image is read by the monochrome density sensor (R) 61R as described above. The gradation pattern image is read by the monochrome density sensor (G1) 61G ₁ , the monochrome density sensor (B) 61B, and the monochrome density sensor (G2) 61G _{2 in the same} manner as the monochrome density sensor (R) 61R. . In addition, measurement positions DR, DG ₁ , DB, and DG ₂ are respectively determined for the measurement positions corresponding to the single color density sensors.
For example, the control unit 10 generates a gamma curve based on the result of reading the gradation pattern image as described above.

  The storage unit 70 is configured by a hard disk, a flash memory, or the like, and stores various data. The storage unit 70 includes a gradation pattern image storage unit 71 and the like.

  The gradation pattern image storage unit 71 stores Y, M, C, K, R, G, B, and Pb data for forming a gradation pattern image including a plurality of patches having different densities. R (red) is red as a secondary color generated by mixing two color materials of magenta and yellow. G (green) is green as a secondary color generated by mixing two color materials of cyan and yellow. B (blue) is blue as a secondary color generated by mixing two color materials of cyan and magenta. Pb (process black) is black as a tertiary color generated by mixing three color materials of cyan, magenta, and yellow.

As shown in FIGS. 5 and 6, three gradation pattern images C1, C2, and C3 are used for one density adjustment. As shown in FIG. 5, the gradation pattern image C1 formed on the paper P has a plurality of densities ranging from the lowest density (gradation value 32) to the highest density (gradation value 255) for each color of CMYK. Contains patches. For example, the gradation values of the patches of the respective colors included in the gradation pattern image C1 are 32, 64, 96, 128, 160, 192, 224, and 255, respectively. Each color patch of CMYK is formed so as to be read by a single-color density sensor including an LED that emits light of a corresponding color. That is, a cyan (C) patch is formed at a position passing through the measurement position DR, a magenta (M) patch is formed at a position passing through the measurement position DG ₁ , and a yellow (Y patches) are formed, patch black (K) in a position passing through the measurement position DG ₂ is formed. As a result, a patch of a color that is complementary to the emission color of the LED is read.

Further, as shown in FIG. 6A, the gradation pattern C2 formed on the paper P is from the lowest density (gradation value 32) to the highest density (gradation value 255) for each of R and G colors. A plurality of density patches in the range of. For example, the tone values of the patches of each color included in the tone pattern image C2 are 32, 64, 96, 128, 160, 192, 224, and 255, respectively. Each density patch R · G are monochrome density sensor (R) 61R, to be read, respectively in the monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) 61B, the measurement position _DR, DG 1, DB Are arranged side by side in the main scanning direction.

Further, as shown in FIG. 6B, the gradation pattern C3 formed on the paper P is from the lowest density (gradation value 32) to the highest density (gradation value 255) for each color of B and Pb. A plurality of density patches in the range of. For example, the gradation values of the patches of each color included in the gradation pattern image are 32, 64, 96, 128, 160, 192, 224, and 255, respectively. Each density patch B · Pb is monochrome density sensor (R) 61R, to be read, respectively in the monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) 61B, the measurement position _DR, DG 1, DB Are arranged side by side in the main scanning direction.

As shown in FIG. 6, in the gradation pattern C2, a green (G) density patch is formed below the red (R) density patch, and in the gradation pattern C3, a blue (B) density patch is formed. The process black (Pb) density patch is formed below, but the order of colors to be formed is not limited to the above, and can be set as appropriate.
In the present embodiment, patches are formed in descending order of density in order to facilitate detection of the start positions of the gradation pattern images C1, C2, and C3. However, the order of patch formation is not limited to this. Further, in order to detect the start position of the gradation pattern image, a reference bar image extending in the main scanning direction may be formed.
In this embodiment, two color patches are formed for each sheet, and the secondary color and tertiary color patches are read using two sheets. However, one sheet is used. Alternatively, density patches of all colors may be formed, or density patches may be formed separately on three or more sheets.
As shown in FIGS. 5 and 6, the gradation pattern image according to the first embodiment forms a plurality of density patches in parallel, so that the density patches can be read with less waste paper.

  The communication unit 80 includes a modem, a LAN (Local Area Network) adapter, a router, a TA (Terminal Adapter), and the like, and performs communication control with each device connected to the network N.

Next, a procedure for reading a gradation pattern image for each of the monochrome density sensor (R) 61R, the monochrome density sensor (G1) 61G ₁ , the monochrome density sensor (B) 61B, and the monochrome green density sensor (G2) 61G ₂ is described. This will be described with reference to FIG.

First, the control unit 10 moves the reference plate covers 66R, 66G ₁ , 66B, 66G ₂ to the open positions, and opens the upper surfaces of the white reference plates 65R, 65G ₁ , 65B, 65G ₂ respectively (Step S10R, S10G ₁ , S10B, S10G ₂ ).

Next, the control unit _10, LED62R, 62G 1, 62B, carrying out the calibration of 62G ₂ (step S20). That is, the control unit 10, first _LED62R, 62G _{1, 62B,} respectively to emit 62G _2, the light receiving elements _64R, 64G 1, 64B, the white reference plate _65R of light received respectively by the _{64G 2, 65G 1, 65B,} 65G 2 A voltage value indicating the amount of reflected light from is input. Then, the control unit 10 adjusts the output of the LEDs 62R, 62G ₁ , 62B, 62G ₂ and adjusts the light receiving elements 64R, 64G ₁ , 64B so that the voltage values from the light receiving elements 64R, 64G ₁ , 64B, 64G ₂ become the same. It adjusts the gain of 64G _2.

Next, the control unit 10 moves the reference plate covers 66R, 66G ₁ , 66B, 66G ₂ to the covering positions, respectively, and covers the upper surfaces of the white reference plates 65R, 65G ₁ , 65B, 65G ₂ respectively (step S30R). , S30G ₁ , S30B, S30G ₂ ).

Next, the control unit 10 forms the gradation pattern image C1 as shown in FIG. 5 on the paper P by the image forming unit 40, and the cyan color density patch by the single color density sensor (R) 61R as described above. read (step S40R), reads the magenta color density patch by the monochrome density sensor (G1) 61G ₁ (step S40G _1), it reads the yellow color density patch by the monochrome density sensor (B) 61B (step S40B), the monochrome density sensor (G2) read the black density patch with 61G ₂ (step S40G _2).

Next, the control unit 10 forms the gradation pattern image C2 as shown in FIG. 6A on the paper P by the image forming unit 40, and the single color density sensor (R) 61R, the single color as described above. respectively, by the concentration sensor (G1) 61G ₁ and the monochrome density sensor (B) 61B reads the red color density patch (step S50). The control unit 10, the monochrome density sensor (R) 61R, read the green density patch, respectively, by single-color density sensor (G1) 61G ₁ and the monochrome density sensor (B) 61B (Step S60).

Next, the control unit 10 forms the gradation pattern image C3 as shown in FIG. 6B on the paper P by the image forming unit 40, and as described above, the single-color density sensor (R) 61R, the single-color sensor respectively, by the concentration sensor (G1) 61G ₁ and the monochrome density sensor (B) 61B reads the blue color density patch (step S60). The control unit 10, the monochrome density sensor (R) 61R, monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) reads the process black color density patches respectively by 61B (step S80).

Based on the image density signal of each color obtained by reading the density patch of each color as described above, the control unit 10 performs an averaging process for obtaining an average value of the image density signal for each patch, or a monochrome density sensor (R) 61R. , monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) by combining the respective color image density signal of RGBPb respectively obtained at a predetermined combination ratio by 61B, the read combined processing for specifying the color of the patch I do.

  In the present embodiment, as described above, it is possible to read not only the primary color but also the color image of the secondary color or more even when using the single color density sensor whose light source is one color. Based on the image data, for example, color profile calibration and image stabilization processing such as γ correction can be appropriately performed.

In the present embodiment has been implemented using four monochrome density sensor, for example, monochrome density sensor black color density patch (R) 61R, monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) If a gradation pattern image is formed so as to be read by any one of 61B, it can be realized by three monochrome density sensors.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment of the present invention, the configuration of the concentration detection unit 60 in the first embodiment is changed. In the second embodiment, the same reference numerals are used for the same components as those in the first embodiment, and the description thereof is omitted.

  As shown in FIG. 8, the density detection unit 60 in the second embodiment uses a monochrome density sensor (R) 61R, a monochrome density sensor (G) 61G, and a monochrome density sensor (B) 61B in the sub-scanning direction of the paper P. In parallel with each other at predetermined intervals. In the second embodiment, three monochrome density sensors are used. The configuration of each part of the monochrome density sensor (R) 61R, the monochrome density sensor (G) 61G, and the monochrome density sensor (B) 61B is the same as that of the first embodiment. In addition, the arrangement order of the monochrome density sensor (R) 61R, the monochrome density sensor (G) 61G, and the monochrome density sensor (B) 61B is not limited to the above, and can be arranged in any arrangement.

  Further, the gradation pattern image storage unit 71 stores data for forming gradation pattern images C4, C5, C6, and C7 as shown in FIGS. 9 and 10, and based on these data. The gradation pattern images C4, C5, C6, and C7 are formed on the paper P, and density adjustment is performed once using these four gradation pattern images.

As shown in FIG. 9A, the gradation pattern image C4 includes a plurality of density patches in the range from the lowest density (gradation value 32) to the highest density (gradation value 255) for each of C and M colors. These density patches are arranged in the sub-scanning direction. Further, as shown in FIG. 9B, the gradation pattern image C5 has a plurality of densities in a range from the lowest density (gradation value 32) to the highest density (gradation value 255) for each of Y and K colors. Patches are included, and these density patches are arranged in the sub-scanning direction. As shown in FIG. 10A, the gradation pattern image C6 has a plurality of densities in a range from the lowest density (gradation value 32) to the highest density (gradation value 255) for each of R and G colors. Patches are included, and these density patches are arranged in the sub-scanning direction. Further, as shown in FIG. 10B, the gradation pattern image C7 has a plurality of densities in a range from the lowest density (gradation value 32) to the highest density (gradation value 255) for each color of B and Pb. Patches are included, and these density patches are arranged in the sub-scanning direction. The configuration of each color density patch is the same as that of the first embodiment.
Since the gradation pattern image in the second embodiment forms density patches serially as shown in FIGS. 9 and 10, the image forming unit is compared with the gradation pattern image in the first embodiment. 40 is less susceptible to the influence of density uniformity in the main scanning direction in the image forming process.

In the second embodiment, the monochromatic density sensor (R) 61R, the monochromatic density sensor (G) 61G, and the monochromatic density sensor (B) 61B are arranged horizontally in the sub-scanning direction of the paper P. Similarly, the positions DR, DG, and DB are arranged parallel to the sub-scanning direction of the paper P. Since it is configured as described above, the density patches in the gradation pattern images C4, C5, C6, and C7 are the monochrome density sensor (B) 61B, the monochrome density sensor (G) 61G, and the monochrome density sensor (R) 61R. Will be read in the order of.
When the CMYK density patches are read under the control of the control unit 10, the monochrome density sensor (R) 61R is used for cyan density patches, and the monochrome density sensor (G) 61G is used for magenta density patches. The monochrome density sensor (B) selectively reads the yellow color density patch, and the monochrome color density sensor (G) 61G selectively reads the black color density patch.
Further, the monochrome density sensor (B) 61B, the monochrome density sensor (G) 61G, and the monochrome density sensor (R) 61R respectively read the density patches of RGBPb under the control of the control unit 10.

  Next, the procedure of reading the gradation pattern image for each of the monochrome density sensor (R) 61R, the monochrome density sensor (G) 61G, and the monochrome density sensor (B) 61B in the second embodiment will be described with reference to FIG. Will be described with reference to FIG.

  First, the control unit 10 moves the reference plate covers 66R, 66G, and 66B to the open positions, and opens the upper surfaces of the white reference plates 65R, 65G, and 65B, respectively (Steps S110R, S110G, and S110B).

  Next, the controller 10 calibrates the LEDs 62R, 62G, and 62B (step S120). The control content of the calibration is the same as in the first embodiment.

  Next, the control unit 10 moves the reference plate covers 66R, 66G, and 66B to the covering positions, and covers the upper surfaces of the white reference plates 65R, 65G, and 65B, respectively (Steps S130R, S130G, and S130B).

Next, the control unit 10 forms gradation pattern images C4 and C5 as shown in FIG. 9 on the paper P by the image forming unit 40, and the cyan density patch of the gradation pattern image C4 is at the measurement position DR. At the timing of arrival, reading of the cyan density patch by the single color density sensor (R) 61R is started as described above (step S140).
Then, at the timing when the magenta color density patch of the gradation pattern image C4 reaches the measurement position DG, the control unit 10 starts reading the magenta color density patch by the single color density sensor (G) 61G as described above. (Step S150).
Then, at the timing when the yellow color density patch of the gradation pattern image C5 reaches the measurement position DB, the control unit 10 starts reading the yellow color density patch by the single color density sensor (B) 61B as described above. (Step S160).
Then, at the timing when the black color density patch of the gradation pattern image C5 reaches the measurement position DG, the control unit 10 starts reading the black color density patch by the single color density sensor (G) 61G as described above. (Step S170).

  Next, the control unit 10 forms gradation pattern images C6 and C7 as shown in FIG. 10 on the paper P by the image forming unit 40, and the red color density patch of the gradation pattern image C6 is set at the measurement position DB. At the timing of arrival, reading of the red color density patch by the single color density sensor (B) 61B is started as described above (step S180B), and the red color density patch reaches the measurement position DG slightly later than this. At the timing, reading of the red color density patch by the single color density sensor (G) 61G is started as described above (step S180G), and at a timing slightly later than this, the red color density patch reaches the measurement position DR. As described above, reading of the red color density patch by the single color density sensor (R) 61R is started (step S18). R).

  Then, at the timing when the green color density patch of the gradation pattern image C6 reaches the measurement position DB, the control unit 10 starts reading the green color density patch by the single color density sensor (B) 61B as described above. (Step S190B) At a timing slightly later than this, when the green color density patch reaches the measurement position DG, reading of the green color density patch by the monochrome density sensor (G) 61G is started as described above (Step S190B). S190G) At a timing slightly later than this, when the green color density patch reaches the measurement position DR, reading of the green color density patch by the monochrome density sensor (R) 61R is started as described above (step S190R). .

  Then, at the timing when the blue color density patch of the gradation pattern image C7 reaches the measurement position DB, the control unit 10 starts reading the blue color density patch by the single color density sensor (B) 61B as described above. (Step S200B) At a timing slightly later than this, when the blue color patch reaches the measurement position DG, reading of the blue color patch by the single-color density sensor (G) 61G is started as described above (Step S200B). S200G), at a timing slightly later than this, when the blue color density patch reaches the measurement position DR, reading of the blue color density patch by the monochrome density sensor (R) 61R is started as described above (step S200R). .

  Then, the control unit 10 reads the process black color density patch by the monochrome density sensor (B) 61B as described above at the timing when the process black color density patch of the gradation pattern image C7 reaches the measurement position DB. The process black color patch is read by the single color density sensor (G) 61G as described above at the timing when the process black color patch reaches the measurement position DG with a slight delay (step S210B). The process black color patch is read by the single-color density sensor (R) 61R as described above at a timing when the process black color patch arrives at the measurement position DR with a slight delay (step S210G). Start (step S210R).

  Based on the image density signal of each color obtained by reading the density patch of each color as described above, the control unit 10 performs the above-described averaging process, composition process, and the like.

As described above, according to the first and second embodiments of the present invention, the monochromatic density sensor (R) 61R emits red light toward the density patch and is reflected by the density patch. And a signal corresponding to the amount of the received light is output, thereby reading the cyan density patch, red color density patch, green color density patch, blue color density patch, and process black color density patch. The monochromatic density sensor (G1) 61G ₁ (monochromatic density sensor (G) 61G) emits green light toward the density patch, receives the light reflected by the density patch, and receives the light quantity of the received light. By outputting a signal corresponding to the above, the magenta color density patch, red color density patch, green color density patch, blue color density patch and process black color density patch are read. The monochrome density sensor (B) 61B emits blue light toward the density patch, receives the light reflected by the density patch, and outputs a signal corresponding to the amount of the received light. The yellow color density patch, red color density patch, green color density patch, blue color density patch, and process black color density patch are read. Then, the control unit 10 determines each density patch from signals output from the monochrome density sensor (R) 61R, the monochrome density sensor (G1) 61G ₁ (monochrome density sensor (G) 61G), and the monochrome density sensor (B) 61B. Obtain concentration information. The density patches are read at different positions by the monochrome density sensor (R) 61R, the monochrome density sensor (G1) 61G ₁ (monochrome density sensor (G) 61G), and the monochrome density sensor (B) 61B. As a result, it is not necessary to perform light amount control or light amount correction according to the density patch to be read, and it is possible to read the density patch of the primary color and the secondary color or more with a simple method, and production accompanying the light amount correction. Deterioration can be suppressed.

Further, according to the first embodiment of the present invention, the image forming unit 40 includes a cyan density patch made of cyan, a magenta color density patch made of magenta, and a yellow color density patch made of yellow. Then, a red color density patch, a green color density patch, a blue color density patch, and a process black color density patch in which two or more of cyan, magenta, and yellow are mixed are formed on the paper P, respectively. The monochromatic density sensor (R) 61R emits red light toward the density patch passing through the measurement position DR, receives the light reflected by the density patch, and responds to the amount of the received light. Output a signal. The single-color density sensor (G1) 61G ₁ emits green light toward the density patch passing through the measurement position DG ₁ different from the measurement position DR in the main scanning direction at least on the paper P. The reflected light is received, and a signal corresponding to the amount of the received light is output. Then, the monochrome density sensor (B) 61B is blue light, emitted toward the density patch passing through different measurement positions DB in the main scanning direction in at least the paper P to the measurement position DR and measurement position DG _1, wherein Light reflected by the density patch is received, and a signal corresponding to the amount of the received light is output. Then, the control unit 10 obtains the density information of the density patch from the monochrome density sensor (R) 61R, monochrome density sensor (G1) 61G ₁ and signals output from the single-color density sensor (B) 61B. Then, the image forming unit 40, the cyan color density patch on the measurement position DR is, the magenta color density patch on the measurement position DG ₁ is cyan density patches on the paper P as a yellow color density patch passes each measurement position DB , to form a magenta color density patches and yellow color density patch, red color density patch, green density patch, blue color density patch and process black color density patch measurement position DR, the measurement position DG ₁ and the measurement position DB A red color density patch, a green color density patch, a blue color density patch, and a process black color density patch are formed on the paper P so as to pass therethrough. Then, the control unit 10, to give the concentration information of cyan density patch from the signal output from the monochrome density sensor (R) 61R, the concentration of the magenta color density patch from the signal output from the monochrome density sensor (G1) 61G ₁ obtain information, obtain density information of the yellow color density patch from the signal output from the monochrome density sensor (B) 61B, a single color density sensor (R) 61R, monochrome density sensor (G1) 61G ₁ and the monochrome density sensor (B) The density information of the red color density patch, the green color density patch, the blue color density patch, and the process black color density patch is obtained from the signals output from 61B. As a result, it is not necessary to perform light amount control or light amount correction according to the density patch to be read, and it is possible to read the density patch of the primary color and the secondary color or more with a simple method, and production accompanying the light amount correction. Deterioration can be suppressed.

  Further, according to the second embodiment of the present invention, the image forming unit 40 includes a cyan density patch composed of cyan, a magenta color density patch composed of magenta, and a yellow color density patch composed of yellow. Then, a red color density patch, a green color density patch, a blue color density patch, and a process black color density patch in which two or more of cyan, magenta, and yellow are mixed are formed on the paper P, respectively. The monochromatic density sensor (R) 61R emits red light toward the density patch passing through the measurement position DR, receives the light reflected by the density patch, and responds to the amount of the received light. Output a signal. The single-color density sensor (G) 61G emits green light toward a density patch that passes the measurement position DG that is the same in the main scanning direction and the different scanning position DG in the sub-scanning direction. Light reflected by the density patch is received, and a signal corresponding to the amount of the received light is output. Then, the monochrome density sensor (B) 61B directs the blue light to the density patch that passes through the measurement position DB that is the same as the measurement position DR and the measurement position DG in the main scanning direction of the paper P and is different in the sub scanning direction. The light that is emitted and reflected by the density patch is received, and a signal corresponding to the amount of the received light is output. Then, the control unit 10 obtains density information of the density patch from signals output from the monochrome density sensor (R) 61R, the monochrome density sensor (G) 61G, and the monochrome density sensor (B) 61B. Then, the image forming unit 40 passes the measurement position DR, the measurement position DG, and the measurement position DB so that the cyan density patch, the magenta color density patch, the yellow color density patch, the red color density patch, and the green color A color density patch, a blue color density patch, and a process black color density patch are formed on the paper P, respectively. Then, the control unit 10 obtains the density information of the cyan density patch from the signal output from the single color density sensor (R) 61R, and the density information of the magenta color density patch from the signal output from the single color density sensor (G) 61G. The density information of the yellow color density patch is obtained from the signal output from the monochrome density sensor (B) 61B, and is obtained from the monochrome density sensor (R) 61R, the monochrome density sensor (G) 61G, and the monochrome density sensor (B) 61B. The density information of the red color density patch, the green color density patch, the blue color density patch, and the process black color density patch is obtained from the output signals. As a result, it is not necessary to perform light amount control or light amount correction according to the density patch to be read, and it is possible to read the density patch of the primary color and the secondary color or more with a simple method, and production accompanying the light amount correction. Deterioration can be suppressed.

  The description in the embodiment of the present invention is an example of the image forming apparatus according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of each functional unit constituting the image forming apparatus can be appropriately changed.

In the first and second embodiments of the present invention, a neutral gray gradation image is displayed when each color LED is arranged in the single-color density sensor or every time a gradation pattern image is read. Each monochromatic density sensor is read, and the output characteristics of each monochromatic density sensor are obtained from the output voltage value, and based on this, the output voltage value is the same for reading a neutral gray gradation image. Adjustments may be made. Such adjustment may be performed together with the calibration described above or instead of the calibration described above.
For example, FIG. 12 shows a neutral gray gradation image read and output by a monochrome density sensor with a red light source, a monochrome density sensor with a green light source, and a monochrome density sensor with a blue light source. The output value specified from the measured voltage value is shown. Here, neutral gray is, for example, a gray color represented on or near the L * axis in the L * a * b * color system. In FIG. 12, the output value shown for each light source of each color is a value specified based on the output voltage value, and a ROI (Region Of Interest) is set for each patch, and a plurality of values are read in the set ROI. The average of the obtained values is shown. FIG. 13 is a graph showing the output value of each monochrome density sensor shown in FIG. In FIG. 13, the x-axis indicates the neutral gray input gradation, and the y-axis indicates the output value of each monochrome density sensor.
As described above, when the neutral gray gradation image is read, the gain adjustment of each monochrome density sensor is performed so that the output value specified from the voltage value of each monochrome density sensor substantially matches at any input gradation. It is preferred that this is done.

  In the present embodiment, an example in which a hard disk, a semiconductor nonvolatile memory, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also used as a medium for providing program data according to the present invention via a communication line.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 10 Control part 40 Image forming part 60 Density detection part 61R Monochromatic density sensor (R)
61G single color density sensor (G)
61G ₁ single color density sensor (G1)
61G ₂ single density sensor (G2)
61B Monochromatic density sensor (B)
_{62R, 62G, 62G 1, 62G} 2, 62B LED
_{64R, 64G, 64G 1, 64G} 2, 64B light-receiving element

Claims (6)

And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed In the image density measuring device that reads the green color and the mixed color patch of blue color to obtain density information of each color patch,
The cyan color patch, the red color, and the green color are emitted by emitting red light toward the color patch, receiving the light reflected by the color patch, and outputting a signal corresponding to the amount of the received light. A first reading unit that reads a mixed color patch of color and blue ,
Green light is emitted toward the color patch, light reflected by the color patch is received, and a signal corresponding to the amount of the received light is output, whereby the magenta color patch, the red color, and the green color are output. A second reading unit that reads a mixed color patch of color and blue ,
By emitting blue light toward the color patch, receiving the light reflected by the color patch, and outputting a signal according to the amount of the received light, the yellow color patch, the red color, and the green color A third reading unit for reading a mixed color patch of color and blue ,
A density information acquisition unit that obtains density information of each color patch from signals respectively output from the first reading unit, the second reading unit, and the third reading unit;
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. A control unit that performs composition processing for specifying the color of the mixed color patch of the red color, the green color, and the blue color that has been read and combined at a ratio;
With
An image density measuring apparatus, wherein color patches are read by the first reading unit, the second reading unit, and the third reading unit at different positions. And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming unit that forms a mixed color patch of green and blue on a recording medium,
A first reading unit that emits red light toward a color patch passing through the first reading position, receives light reflected by the color patch, and outputs a signal corresponding to the amount of the received light When,
Green light is emitted toward a color patch passing through a second reading position different from the first reading position in the main scanning direction in the recording medium, and the light reflected by the color patch is received; A second reading unit that outputs a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position different from the first reading position and the second reading position in the main scanning direction on the recording medium. A third reading unit that receives the reflected light and outputs a signal according to the amount of the received light;
A density information acquisition unit for obtaining color patch density information from signals output from the first reading unit, the second reading unit, and the third reading unit;
With
The image forming unit passes the cyan color patch at the first reading position, the magenta color patch at the second reading position, and the yellow color patch at the third reading position. As described above, the cyan color patch, the magenta color patch, and the yellow color patch are formed on the recording medium, and the mixed color patch of red, green, and blue is the first reading position, Forming a mixed color patch of red, green and blue on the recording medium so as to pass through the second reading position and the third reading position,
The density information acquisition unit obtains density information of the cyan color patch from the signal output from the first reading unit, and obtains density information of the magenta color patch from the signal output from the second reading unit. The density information of the yellow color patch is obtained from the signal output from the third reading unit, and from the signals output from the first reading unit, the second reading unit, and the third reading unit, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. An image forming apparatus comprising: a control unit configured to perform synthesis processing for specifying a color of a mixed color patch of the red color, green color, and blue color that are combined and read at a ratio . And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming unit that forms a mixed color patch of green and blue on a recording medium,
A first reading unit that emits red light toward a color patch passing through the first reading position, receives light reflected by the color patch, and outputs a signal corresponding to the amount of the received light When,
Green light is emitted toward a color patch that passes through a second reading position that is the same as the first reading position in the main scanning direction and different in the sub-scanning direction on the recording medium, and is reflected by the color patch. A second reading unit that receives the received light and outputs a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position that is the same as the first scanning position and the second reading position in the main scanning direction and different in the sub-scanning direction in the recording medium. A third reading unit that receives the light reflected by the color patch and outputs a signal corresponding to the amount of the received light;
A density information acquisition unit for obtaining color patch density information from signals output from the first reading unit, the second reading unit, and the third reading unit;
With
The image forming unit passes the first reading position, the second reading position, and the third reading position so that the cyan color patch, the magenta color patch, and the yellow color color are passed. Forming patches and mixed color patches of red, green and blue on the recording medium,
The density information acquisition unit obtains density information of the cyan color patch from the signal output from the first reading unit, and obtains density information of the magenta color patch from the signal output from the second reading unit. The density information of the yellow color patch is obtained from the signal output from the third reading unit, and from the signals output from the first reading unit, the second reading unit, and the third reading unit, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color of the first reading unit, the second reading unit, and the third reading unit obtained from the density information acquisition unit is set to a predetermined value. An image forming apparatus comprising: a control unit configured to perform synthesis processing for specifying a color of a mixed color patch of the red color, green color, and blue color that are combined and read at a ratio . And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed In the image density measurement method for obtaining the density information of each color patch by reading each of the mixed color patches of green color and blue color ,
By emitting red light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal according to the amount of the received light, the cyan color patch, the red color, and the green color A first reading step for reading a blue mixed color patch;
The magenta color patch, the red color, and the green color are emitted by emitting green light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light. A second reading step for reading a blue mixed color patch;
By emitting blue light toward the color patch, receiving the light reflected by the color patch, and obtaining a signal according to the amount of the received light, the yellow color patch, the red color, and the green color A third reading step for reading a blue mixed color patch;
A density information acquisition step of obtaining density information of each color patch from the signals respectively obtained in the first reading step, the second reading step, and the third reading step;
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. A synthesis processing step for specifying the color of the mixed color patch of the red color, the green color, and the blue color that has been read,
Including
The color patch reading in the first reading step, the color patch reading in the second reading step, and the color patch reading in the third reading step are performed at different positions, respectively. A characteristic image density measuring method. And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming process for forming green, blue mixed color patches on a recording medium,
A first reading step of emitting red light toward the color patch passing through the first reading position, receiving light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light; ,
Green light is emitted toward a color patch passing through a second reading position different from the first reading position in the main scanning direction in the recording medium, and the light reflected by the color patch is received; A second reading step for obtaining a signal corresponding to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position different from the first reading position and the second reading position in the main scanning direction on the recording medium. A third reading step of receiving the reflected light and obtaining a signal according to the amount of the received light;
A density information acquisition step of obtaining color patch density information from the signals obtained in the first reading step, the second reading step and the third reading step, respectively;
Including
In the image forming step, the cyan color patch passes through the first reading position, the magenta color patch passes through the second reading position, and the yellow color patch passes through the third reading position. As described above, the cyan color patch, the magenta color patch, and the yellow color patch are formed on the recording medium, and the mixed color patch of red, green, and blue is the first reading position, Forming a mixed color patch of red, green and blue on the recording medium so as to pass through the second reading position and the third reading position,
In the density information acquisition step, density information of the cyan color patch is obtained from the signal obtained in the first reading step, and density information of the magenta color patch is obtained from the signal obtained in the second reading step. The density information of the yellow color patch is obtained from the signal obtained in the third reading step, and from the signals obtained in the first reading step, the second reading step, and the third reading step, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. The image density measuring method further comprising a combining processing step of specifying the color of the mixed color patch of the red color, the green color, and the blue color that are combined at a ratio of 1 and read . And cyan color patches consisting of cyan, and magenta color patches consisting of magenta, and yellow color patches consisting of yellow, red color more colors of cyan, magenta and yellow color is mixed An image forming process for forming green, blue mixed color patches on a recording medium,
A first reading step of emitting red light toward the color patch passing through the first reading position, receiving light reflected by the color patch, and obtaining a signal corresponding to the amount of the received light; ,
Green light is emitted toward a color patch that passes through a second reading position that is the same as the first reading position in the main scanning direction and different in the sub-scanning direction on the recording medium, and is reflected by the color patch. A second reading step of receiving the received light and obtaining a signal according to the amount of the received light;
Blue light is emitted toward a color patch that passes through a third reading position that is the same as the first scanning position and the second reading position in the main scanning direction and different in the sub-scanning direction in the recording medium. A third reading step of receiving light reflected by the color patch and obtaining a signal corresponding to the amount of the received light;
A density information acquisition step of obtaining color patch density information from the signals obtained in the first reading step, the second reading step and the third reading step, respectively;
Including
In the image forming step, the cyan color patch, the magenta color patch, and the yellow color color so as to pass through the first reading position, the second reading position, and the third reading position. Forming patches and mixed color patches of red, green and blue on the recording medium,
In the density information acquisition step, density information of the cyan color patch is obtained from the signal obtained in the first reading step, and density information of the magenta color patch is obtained from the signal obtained in the second reading step. The density information of the yellow color patch is obtained from the signal obtained in the third reading step, and from the signals obtained in the first reading step, the second reading step, and the third reading step, respectively. Obtain density information of the mixed color patch of red, green and blue ,
Each density information of the mixed color patch of red color, green color, and blue color in the first reading process, the second reading process, and the third reading process obtained in the density information acquisition process is predetermined. The image density measuring method further comprising a combining processing step of specifying the color of the mixed color patch of the red color, the green color, and the blue color that are combined at a ratio of 1 and read .

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