JP2021165813A - Image forming device - Google Patents

Abstract

[Problem] To provide an image forming device capable of appropriately correcting the density of an image formed on an embossed recording medium. [Solution] The image forming device includes an image forming unit that forms an image for density correction on the recording medium, a reading unit that reads the image for density correction formed on the recording medium, and a correction unit that corrects the density of the image formed by the image forming unit based on the density of the image for density correction read by the reading unit. When the recording medium is an embossed recording medium, the reading unit reads both sides of the recording medium. The correction unit corrects the variation in density of the image for density correction read by the reading unit using a correction table and the shape of the recording medium obtained by reading the recording medium with the reading unit, and corrects the density of the image formed by the image forming unit based on the corrected density of the image for density correction read by the reading unit. [Selected Figure] Figure 4

Description

The present disclosure relates to an image forming apparatus.

An image forming apparatus for forming an image on embossed paper (hereinafter, also referred to as "embossed paper") is known. Embossing is to make the surface of the paper uneven by pressing the paper between the letterpress and the intaglio. Some embossed papers are embossed on only one side of the paper, while others are embossed on both sides of the paper.

When an image is formed on an embossed surface (hereinafter, also referred to as an "embossed surface"), white spots are likely to occur in the image. This is because when the toner image is transferred from the intermediate transfer belt to the paper, transfer defects occur in the recesses. The reason why the transfer failure occurs is that the concave portion is closer to the toner on the intermediate transfer belt than the convex portion. The deeper the groove of the recess, the more likely it is that transfer defects will occur, so the amount of whiteout tends to increase. Further, when an image is formed on a surface that has not been embossed (hereinafter, also referred to as “non-embossed surface”), toner scattering is likely to occur. This is because the transfer current becomes too large in the recessed portion. The paper is thinner in the recesses than in the other parts. Since the transfer current is set based on the original thickness of the paper (the thickness of the paper before embossing), the transfer current becomes too large in the recessed portion. Therefore, toner scatter occurs. Due to these characteristics of the embossed paper, even if a patch is formed on the embossed paper at a predetermined density, white spots occur on the embossed surface and toner is scattered on the non-embossed surface, so that the density of the patch varies. , And the density cannot be corrected properly.

Japanese Patent Application Laid-Open No. 2019-152722 (Patent Document 1) states that a plurality of patches are formed on embossed paper using a plurality of screen patterns, and the amount of residual toner on the intermediate transfer belt is less than a predetermined standard. A technique for determining a screen having the largest number of screen lines among the screen patterns used for generation as a screen pattern used when forming an image on the embossed paper is disclosed.

Japanese Unexamined Patent Publication No. 2007-30340 (Patent Document 2) discloses a technique of forming a patch image while avoiding a region (uneven region) in which the color reproduction characteristics fluctuate greatly, and reading the formed patch image to adjust the density. ing.

JP-A-2019-152722 JP-A-2007-30340

The technique disclosed in Japanese Patent Application Laid-Open No. 2019-152722 is a technique for suppressing deterioration of the image quality (occurrence of whiteout) of an image formed on embossed paper, and an object thereof is to appropriately perform density correction. It's not something to do. Further, the technique disclosed in Japanese Patent Application Laid-Open No. 2007-30340 is a technique for forming a patch image by avoiding streaks and unevenness that partially occur, and it is assumed that unevenness occurs on the entire surface such as embossed paper. It has not been.

The present disclosure has been made in view of such circumstances, and one object of the present disclosure is to provide an image forming apparatus capable of appropriately correcting the density of an image formed on an embossed recording medium. ..

An image forming apparatus according to a certain embodiment includes an image forming unit that forms a density correction image on a recording medium, a reading unit that reads a density correction image formed on the recording medium, and a density correction image read by the reading unit. A correction unit for correcting the density of the image formed by the image forming unit based on the density of the image is provided. When the recording medium is an embossed recording medium, the reading unit reads both sides of the recording medium. The correction unit corrects the variation in the density of the density correction image read by the reading unit using the correction table and the shape of the recording medium obtained by reading the recording medium by the reading unit, and reads the density correction image by the reading unit. Based on the corrected density of the density correction image, the density of the image formed by the image forming unit is corrected.

An image forming apparatus according to another embodiment includes an image forming unit that forms an image for density correction on a recording medium, a feeding unit that supplies the recording medium to the image forming unit, and an image forming unit that is located after the feeding unit. A recording medium reading unit arranged in the front stage to read the recording medium, an image reading unit arranged in the rear stage of the image forming unit to read the density correction image formed on the recording medium, and a density correction unit read by the image reading unit. A correction unit for correcting the density of the image formed by the image forming unit based on the density of the image is provided. When the recording medium is an embossed recording medium, the recording medium reading unit reads both sides of the recording medium. The correction unit corrects the variation in the density of the density correction image read by the image reading unit by using the correction table and the shape of the recording medium obtained by reading the recording medium by the recording medium reading unit, and reads the image. The density of the image formed by the image forming unit is corrected based on the corrected density of the density correction image read by the unit.

According to the present disclosure, the density of an image formed on an embossed recording medium can be appropriately corrected.

It is a figure which shows the schematic structure of the image forming apparatus. It is a block diagram which shows the main functional composition of an image forming apparatus. It is a figure which shows the cross section of the embossed paper. It is a flowchart which shows the process of correcting the print density of embossed paper. It is a figure which shows the relationship between the image luminance and the depth of the groove of embossed paper. It is a figure which shows the relationship between the image luminance and the thickness of embossed paper. It is a figure which shows the setting screen of the embossed paper. It is a figure which shows the density correction chart. It is a figure which shows the filtering process. It is a figure which shows the 1st correction table. It is a figure which shows the 2nd correction table. It is a figure which shows the schematic structure of the image forming apparatus in Embodiment 2. FIG. It is a flowchart which shows the process of correcting the print density of the embossed paper in Embodiment 2.

Hereinafter, each embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[Embodiment 1]
The configuration of the image forming apparatus 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1. FIG. 2 is a block diagram showing a main functional configuration of the image forming apparatus 1.

The image forming apparatus 1 includes a control unit 10, a storage unit 11, an operation unit 12, a display unit 13, a communication unit 14, a paper feeding unit 15, an image forming unit 17, a fixing unit 18, a conveying unit 19, and a reading unit 21. .. The control unit 10 includes a control unit 10, a storage unit 11, an operation unit 12, a display unit 13, a communication unit 14, a paper feed unit 15, an image forming unit 17, a fixing unit 18, a transport unit 19, and a reading unit via a bus 22. It is connected to the unit 21.

The control unit 10 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, and a ROM (Read Only Memory) 103. The CPU 101 comprehensively controls the entire image forming apparatus 1. The CPU 101 reads and executes a control program stored in the ROM 103 or the storage unit 11 to perform various arithmetic processes. The RAM 102 is a work area when the CPU 101 executes a program, and temporarily stores the program, data when the program is executed, and the like. The ROM 103 stores various control programs, setting data, and the like executed by the CPU 101.

The storage unit 11 is composed of a DRAM (Dynamic Random Access Memory) or the like, and stores paper setting information used for printing, image data input from an external PC (Personal Computer) or the like via the communication unit 14, and the like. Will be done. The paper setting information includes the type of paper (for example, plain paper, embossed paper, etc.), the size of the paper, the basis weight of the paper, and the characteristics of the paper (for example, if the paper is embossed paper, embossing is the paper. Information such as information indicating whether the paper is applied to only one side or both sides of the paper, the depth of the groove of the embossed paper, etc.) is included.

The operation unit 12 includes input devices such as a touch panel arranged so as to be superimposed on the operation keys and the screen of the display unit 13, and converts input operations for these input devices into operation signals and outputs them to the control unit 10.

The display unit 13 includes a display device such as an LCD (Liquid crystal display), and displays an operation screen or the like showing the state of the image forming device 1 or the content of an input operation on the touch panel.

The communication unit 14 is composed of a communication control card such as a LAN (Local Area Network) card, and is connected to an external device (for example, a PC) connected to a communication network such as a LAN or WAN (Wide Area Network). Send and receive various data.

The paper feed unit 15 supplies the paper stored in the paper feed tray one by one to the image forming unit 17, which will be described later. The paper stored in the paper feed tray is not limited to plain paper, but may be embossed paper, thin paper, thick paper, envelopes, or the like. Further, the paper is only an example of a recording medium, and another recording medium (for example, an OHP (Overhead Projector) film or the like) may be stored in the paper feed tray.

The image forming unit 17 includes four sets of exposed units 171, a photoconductor 172, and a developing unit 173 corresponding to each color component of C (cyan), M (magenta), Y (yellow), and K (black). , An intermediate transfer belt 174 and a secondary transfer roller 175 are provided, and an image is formed on paper by an electrophotographic method based on image data. The image data includes, for example, image data input from an external PC or the like via the communication unit 14, image data of a copy document read by the reading unit 21 described later, and a density correction image (hereinafter, also referred to as “patch”). Data etc.

The fixing unit 18 heats and pressurizes the paper on which the toner is transferred to fix the toner on the paper.

The transport unit 19 includes a plurality of rollers that can rotate while holding the paper. The transport unit 19 transports the paper fed from the paper feed tray along a predetermined transport path. The transport unit 19 transports the image-formed and fixed paper to the post-processing device 24, and discharges the paper that has been post-processed by the post-processing device 24 to the output tray 25. The post-processing device 24 performs staple processing, drilling processing, and the like on the paper on which the image is formed and fixed.

The reading unit 21 includes a line sensor (for example, a CCD (Charge-Coupled Device) image sensor, a CIS (Contact Image Sensor), etc.), an optical system, a light source, and the like. The reading unit 21 reads one side or both sides of the paper set by the user and outputs the obtained image data to the control unit 10. The reading unit 21 reads a copy document, reads a blank sheet of paper, and reads a patch. The image data of the copy document read by the scanning unit 21 is used in the image forming by the image forming unit 17. The image data of the blank paper read by the reading unit 21 and the image data of the patch read by the reading unit 21 are used in the process of correcting the print density, which will be described later.

The process of correcting the print density is a process of correcting the density of the image formed by the image forming unit 17 (hereinafter, also referred to as “print density”), and is performed by the control unit 10. When correcting the print density, the control unit 10 forms a patch on the paper at a predetermined density, and corrects the print density based on the image data obtained by reading the patch.

FIG. 3 is a diagram showing a cross section of the embossed paper. Embossed paper is paper that has been embossed. Embossing is to make the surface of the paper uneven by pressing the paper between the letterpress and the intaglio. Some embossed papers are embossed on only one side of the paper, while others are embossed on both sides of the paper. In FIG. 3, an embossed paper in which embossing is applied to only one side of the paper is drawn.

When an image is formed on an embossed surface (a surface that has been embossed), white spots are likely to occur in the image. This is because when the toner image is transferred from the intermediate transfer belt to the paper, transfer defects occur in the recesses R1, R2, and R3. The reason why the transfer failure occurs is that the concave portions R1, R2, and R3 are farther from the toner on the intermediate transfer belt than the convex portion. The deeper the grooves of the recesses R1, R2, and R3, the more likely it is that transfer defects will occur, so the amount of whiteout tends to increase. Further, when an image is formed on a non-embossed surface (a surface not embossed), toner scattering is likely to occur. This is because the transfer current becomes too large in the recesses R1, R2, and R3. The recesses R1, R2, and R3 are thinner than the other portions F1, F2, F3, and F4. Since the transfer current is set based on the original thickness T of the paper (the thickness of the paper before embossing), the transfer current becomes too large for the recesses R1, R2, and R3. .. As a result, toner scatter occurs.

Due to these characteristics of the embossed paper, even if a patch is formed on the embossed paper at a predetermined density, white spots occur on the embossed surface and toner scatters on the non-embossed surface, so that the density of the patch varies. , And the print density cannot be corrected properly. On the other hand, white spots and toner scattering are uniquely determined by the level of embossing, that is, the depth of the embossed paper groove and the thickness of the embossed paper (thinness of the embossed paper). If the thickness of the paper is known, it is possible to predict how much whiteout and toner scattering will occur. Therefore, the image forming apparatus 1 in the first embodiment identifies a region where white spots and toner scatter occur and a generation level based on the depth of the groove of the embossed paper and the thickness of the embossed paper, and white in the patch region. Correct the density in the area where omission or toner scattering occurs. As a result, the variation in the density of the patch is corrected, so that the density of the image can be appropriately corrected in the image formation on the embossed paper.

The process of correcting the print density of the embossed paper will be described with reference to FIGS. 4 to 11. FIG. 4 is a flowchart showing a process of correcting the print density of the embossed paper. The process shown in FIG. 4 is a process performed by the control unit 10 (see FIG. 1), and is realized by the CPU 101 (see FIG. 2) executing a predetermined program stored in the ROM 103 (see FIG. 2).

First, the control unit 10 determines whether or not it has been instructed to correct the print density of the embossed paper (step S405). When instructed to correct the print density of the embossed paper (YES in step S405), the control unit 10 shifts the process to step S415. On the other hand, if it is not instructed to correct the print density of the embossed paper (NO in step S405), the control unit 10 ends a series of processes shown in FIG.

In step S415, the control unit 10 determines whether or not a blank embossed paper is set in the reading unit 21. When the user wants to correct the print density of the embossed paper, the user needs to set a blank embossed paper in the reading unit 21. When a blank embossed paper is set in the reading unit 21 (YES in step S415), the control unit 10 shifts the process to step S420.

In step S420, the control unit 10 reads the blank embossed paper set by the user and identifies the shape of the embossed paper. Specifically, the control unit 10 causes the reading unit 21 to read both sides of the blank embossed paper set by the user, and calculates the image brightness by performing image processing on the read image data. The control unit 10 specifies the depth of the groove of the embossed paper based on the image brightness of the embossed surface in the calculated image brightness, and the control unit 10 determines the depth of the groove of the embossed paper based on the image brightness of the non-embossed surface in the calculated image brightness. Identify the thickness.

Here, a method for the control unit 10 (see FIG. 1) to specify the shape of the embossed paper will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing the relationship between the image luminance and the depth of the groove of the embossed paper. FIG. 6 is a diagram showing the relationship between the image brightness and the thickness of the embossed paper. As shown in FIG. 5, the image brightness tends to decrease as the groove of the embossed paper becomes deeper. This is because the irradiation light of the reading unit 21 (see FIG. 1) is diffusely reflected in the recess. Further, as shown in FIG. 6, the image brightness tends to decrease as the embossed paper becomes thinner. This is because the irradiation light of the reading unit 21 is transmitted when the paper is thin. The control unit 10 identifies the shape of the embossed paper based on the tendency shown in FIGS. 5 and 6 and the image brightness obtained by reading the blank embossed paper.

Further, the control unit 10 (see FIG. 1) identifies the embossed surface of the embossed paper based on the setting information regarding the embossed paper input on the setting screen shown in FIG. 7. FIG. 7 is a diagram showing a setting screen 130 of the embossed paper. The setting screen 130 is a screen for the user to input the information of the embossed paper, and is displayed on the display unit 13 (see FIG. 1). The setting screen 130 includes a field for inputting the size of the paper, a field for inputting the basis weight of the paper, a field for inputting the embossed surface, and a field for inputting the depth of the groove of the embossed paper. including. When "single side" is selected in the "embossing" field on the setting screen 130, the control unit 10 identifies the front surface of the embossed paper as the embossed surface and the back surface of the embossed paper as the non-embossed surface. .. When "double-sided" is selected in the "embossed" field on the setting screen 130, the control unit 10 specifies both sides of the embossed paper as the embossed surface. Further, the control unit 10 changes the fixing temperature, the development setting, and the transfer setting based on the setting information regarding the embossed paper input on the setting screen 130. As a result, the image forming apparatus 1 optimally prints on the embossed paper.

Again, referring to FIG. 4, the control unit 10 feeds the embossed paper from the paper feed unit 15 to the image forming unit 17 (step S425). Specifically, the control unit 10 feeds the image forming unit 17 with the blank embossed paper stored in the paper feed tray in the paper feed unit 15.

Next, the control unit 10 determines whether or not the embossed paper has reached the image forming unit 17 (step S430). When the embossed paper reaches the image forming unit 17 (YES in step S430), the control unit 10 shifts the process to step S435.

In step S435, the control unit 10 forms the density correction chart on the embossed paper fed from the paper feed unit 15, and discharges the embossed paper on which the density correction chart is formed to the output tray 25. Specifically, the control unit 10 causes the image forming unit 17 to form a plurality of patches on the embossed paper fed from the feeding unit 15 at different concentrations, and the transfer unit 19 forms the embossed paper on which the patches are formed. It is conveyed to the output tray 25. Here, the density correction chart will be described with reference to FIG. FIG. 8 is a diagram showing a density correction chart C. The density correction chart C is composed of a plurality of patches P having different densities. Each patch P is formed at a different density by the image forming unit 17 (see FIG. 1).

Again, referring to FIG. 4, the control unit 10 determines whether or not the embossed paper on which the density correction chart is formed is set in the reading unit 21 (step S440). When the embossed paper on which the density correction chart is formed is ejected to the output tray 25, the user needs to set the ejected embossed paper in the reading unit 21. When the embossed paper on which the density correction chart is formed is set in the reading unit 21 (YES in step S440), the control unit 10 shifts the process to step S445.

In step S445, the control unit 10 reads the density correction chart formed on the embossed paper set by the user and calculates the density of each patch. Specifically, the control unit 10 causes the reading unit 21 to read the density correction chart formed on the embossed paper set by the user, and calculates the density of each patch by performing image processing on the read image data.

Next, the control unit 10 performs a filter process (step S450). The filter process is a process for correcting the variation in the density of each patch calculated in step S445. Here, the filtering process will be described with reference to FIG. FIG. 9 is a diagram showing the filtering process.

There are variations in the concentration (measured value) of each patch calculated in step S445 (see FIG. 4). This is because white spots and toner scatter occur in each patch. As described with reference to FIG. 3, white spots and toner scatter occur in the embossed paper. Therefore, when the density correction chart is formed on the embossed paper, white spots and toner scatter occur in each patch, so that the density of each patch varies.

Therefore, the control unit 10 (see FIG. 1) performs a filter process. The filtering process uses the shape of the embossed paper specified in step S420 (see FIG. 4) and the correction table previously stored in the storage unit 11 (see FIG. 2) to create white spots in the area of each patch. It is to correct the density of the area where the toner is scattered and the density to an appropriate density. Specifically, the control unit 10 uses the shape of the embossed paper specified in step S420 (see FIG. 4) to determine the region where white spots and toner scatter occur and the level at which white spots and toner scatter occur. Identify and correct the density of the area where white spots and toner are scattered in the area of each patch using the correction table.

Here, the correction table will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing a first correction table. FIG. 11 is a diagram showing a second correction table. The correction table includes a first correction table and a second correction table. The correction table is a table for correcting variations in the density of each patch caused by embossing.

Each cell of the correction table stores a correction value for correcting the density of the area where white spots or toner scattering occur in the area of each patch. The correction value in the first correction table is uniquely determined based on the depth of the groove of the embossed paper and the density of the patch. The correction value in the second correction table is uniquely determined based on the thickness of the embossed paper and the density of the patch. The control unit 10 (see FIG. 1) refers to the correction table, and refers to the shape of the embossed paper specified in step S420 (see FIG. 4) and the density (measured value) of each patch calculated in step S445 (see FIG. 4). ) And the correction value corresponding to), and the correction value is used to correct the variation in the density of each patch.

The correction table is stored in the storage unit 11 (see FIG. 2) for each detailed setting of the embossed paper at the time of factory shipment of the image forming apparatus 1 (see FIG. 1). The correction table may be stored in the ROM 103 (see FIG. 2).

Again, referring to FIG. 9, the filtering process corrects the variation in density due to white spots and toner scattering, so that the density of each patch after the filtering process becomes uniform.

Again, referring to FIG. 4, the control unit 10 corrects the print density of the embossed paper based on the density of each patch after correction (step S455). The method of correcting the print density in step S455 is the same as the method of correcting the print density of plain paper. That is, the control unit 10 calculates the average value or the median value of the entire patch from the density of each patch after correction, and based on the calculated value, the print density of the embossed paper, that is, the image forming unit 17 (see FIG. 1). ) Corrects the density of the image formed by.

After the process of step S455, the control unit 10 ends the process shown in FIG.

As described above, when the image forming apparatus 1 in the first embodiment reads the patch formed on the embossed paper and corrects the print density, the region where the white embossed paper is read and white spots or toner scatter occur. And the level at which white spots and toner scatter occur are specified, and the density of the area where white spots and toner scatter occur in the area of each patch formed on the embossed paper is corrected using a correction table. As a result, the print density can be corrected based on a uniform density in which variations due to white spots and toner scattering are corrected. Therefore, in the image forming apparatus 1 according to the first embodiment, the embossed recording medium is used. The density of the formed image can be appropriately corrected.

[Embodiment 2]
The image forming apparatus according to the second embodiment will be described with reference to FIG. In the image forming apparatus 1 (see FIG. 1) in the first embodiment, the apparatus for reading the embossed paper is only the reading unit 21 in which the user needs to set the reading target. Therefore, in the image forming apparatus 1 of the first embodiment, the user needs to manually set the embossed paper in the reading unit 21 in order to correct the print density of the embossed paper. On the other hand, the image forming apparatus 1A according to the second embodiment includes a reading device for automatically setting the embossed paper to be read as a device for reading the embossed paper. In the following, only the configuration different from that of the first embodiment will be described, and the same reference numerals will be given to the same configurations as those of the first embodiment, and the description will not be repeated.

FIG. 12 is a diagram showing a schematic configuration of the image forming apparatus 1A according to the second embodiment. As shown in FIG. 12, the image forming apparatus 1A includes two reading units (recording medium reading unit 30 and image reading unit 40) in addition to the reading unit 21 as a device for reading the embossed paper. The reading unit 21 is a reading device in which the user needs to set the reading target, whereas the recording medium reading unit 30 and the image reading unit 40 are reading devices in which the embossed paper to be read is automatically set. The recording medium reading unit 30 and the image reading unit 40 include a line sensor (for example, a CCD (Charge-Coupled Device) image sensor, a CIS (Contact Image Sensor), etc.), an optical system, a light source, and the like.

The recording medium reading unit 30 is arranged in the rear stage of the paper feeding unit 15 and in the front stage of the image forming unit 17 on the paper transport path, and reads the paper fed from the paper feeding unit 15. The recording medium reading unit 30 includes a front surface reading unit 30a for reading the front surface of the paper and a back surface reading unit 30b for reading the back surface of the paper. The image reading unit 40 is arranged after the image forming unit 17, and reads a density correction chart (patch) formed on the paper conveyed from the image forming unit 17. The image reading unit 40 includes a front surface reading unit 40a for reading the front surface of the paper and a back surface reading unit 40b for reading the back surface of the paper. The recording medium reading unit 30 reads both sides of the paper and outputs the obtained image data to the control unit 10. The image reading unit 40 reads one side or both sides of the paper and outputs the obtained image data to the control unit 10.

FIG. 13 is a flowchart showing a process of correcting the print density of the embossed paper in the second embodiment. The process shown in FIG. 13 is a process performed by the control unit 10 (see FIG. 12), and is realized by the CPU 101 (see FIG. 2) executing a predetermined program stored in the ROM 103 (see FIG. 2).

First, the control unit 10 determines whether or not it has been instructed to correct the print density of the embossed paper (step S1305). When instructed to correct the print density of the embossed paper (YES in step S1305), the control unit 10 shifts the process to step S1310. On the other hand, if it is not instructed to correct the print density of the embossed paper (NO in step S1305), the control unit 10 ends the series of processes shown in FIG.

In step S1310, the control unit 10 feeds the blank embossed paper to the recording medium reading unit 30. Specifically, the control unit 10 causes the paper feed unit 15 to feed the blank embossed paper stored in the paper feed tray to the recording medium reading unit 30.

Next, the control unit 10 determines whether or not the embossed paper has reached the recording medium reading unit 30 (step S1315). When the embossed paper reaches the recording medium reading unit 30 (YES in step S1315), the control unit 10 shifts the process to step S1320.

In step S1320, the control unit 10 reads the blank embossed paper fed from the paper feed unit 15 to specify the shape of the embossed paper (step S1320). Specifically, the control unit 10 causes the recording medium reading unit 30 to read both sides of the blank embossed paper fed from the paper feeding unit 15, and calculates the image brightness by performing image processing on the read image data. do. The control unit 10 specifies the depth of the groove of the embossed paper based on the image brightness of the embossed surface in the calculated image brightness, and the control unit 10 determines the depth of the groove of the embossed paper based on the image brightness of the non-embossed surface in the calculated image brightness. Identify the thickness. The method by which the control unit 10 specifies the shape of the embossed paper is the same as the method described with reference to FIGS. 5 to 7.

Next, the control unit 10 conveys the blank embossed paper read by the recording medium reading unit 30 to the image forming unit 17 (step S1325). Specifically, the control unit 10 causes the transport unit 19 to transport the blank embossed paper read by the recording medium reading unit 30 to the image forming unit 17.

Next, the control unit 10 determines whether or not the embossed paper has reached the image forming unit 17 (step S1330). When the embossed paper reaches the image forming unit 17 (YES in step S1330), the control unit 10 shifts the process to step S1335.

In step S1335, the control unit 10 forms the density correction chart on the embossed paper, and conveys the embossed paper on which the density correction chart is formed to the image reading unit 40. Specifically, the control unit 10 causes the image forming unit 17 to form a plurality of patches on the embossed paper conveyed from the recording medium reading unit 30 at different concentrations, and the embossed paper on which the patches are formed is formed on the conveying unit 19. It is conveyed to the image reading unit 40. The density correction chart is the same as the chart described with reference to FIG.

Next, the control unit 10 determines whether or not the embossed paper has reached the image reading unit 40 (step S1340). When the embossed paper reaches the image reading unit 40 (YES in step S1340), the control unit 10 shifts the process to step S1345.

In step S1345, the control unit 10 reads the density correction chart formed on the embossed paper conveyed from the image forming unit 17, calculates the density of each patch, and discharges the embossed paper to the output tray 25. .. Specifically, the control unit 10 causes the image reading unit 40 to read the density correction chart formed on the embossed paper conveyed from the image forming unit 17, and performs image processing on the read image data to perform each patch. Calculate the concentration of. Further, the control unit 10 causes the transport unit 19 to transport the embossed paper that has been read by the image reading unit 40 to the output tray 25.

Next, the control unit 10 performs a filter process (step S1350). The filter process is a process for correcting the variation in the density of each patch calculated in step S1345, and is the same as the filter process described with reference to FIGS. 9 to 11.

Next, the control unit 10 corrects the print density of the embossed paper based on the density of each patch after correction (step S1355). The method of correcting the print density in step S1355 is the same as the method of correction described in step S455 (see FIG. 4).

After the process of step S1355, the control unit 10 ends the process shown in FIG.

As described above, when the image forming apparatus 1A in the second embodiment reads the patch formed on the embossed paper and corrects the print density, the region where the white embossed paper is read and white spots or toner scatter occur. And the level at which white spots and toner scatter occur are specified, and the density of the area where white spots and toner scatter occur in the area of each patch formed on the embossed paper is corrected using a correction table. As a result, the print density can be corrected based on the uniform density in which variations due to white spots and toner scattering are corrected. Therefore, in the image forming apparatus 1A according to the second embodiment, the embossed recording medium is used. The density of the formed image can be appropriately corrected.

Further, since the image forming apparatus 1A in the second embodiment includes a reading device (recording medium reading unit 30 and image reading unit 40) in which the embossed paper to be read is automatically set as a device for reading the embossed paper. , The user does not have to manually load the embossed paper in the reader to correct the print density of the embossed paper. As a result, the user's trouble can be saved.

[Modification example]
A modification of the first embodiment or the second embodiment will be described. In the first embodiment or the second embodiment, the correction table is stored in the storage unit 11 (see FIG. 2) from the time of shipment from the factory, but in the modified example, the correction table is stored by the control unit 10 (see FIG. 2). Will be generated. Hereinafter, the generation of the correction table by the control unit 10 and the usage scene thereof will be described. Since the configuration of the image forming apparatus in the modified example is the same as the configuration of the image forming apparatus 1 (see FIG. 1) or the image forming apparatus 1A (see FIG. 12), the same reference numerals are given to the same configurations. , The explanation is not repeated.

The control unit 10 has the shape of the embossed paper specified in step S420 or step S1320 (see FIG. 4 or 13) and the density (measured value) of each patch calculated in step S445 or step S1345 (see FIG. 4 or 13). ) And generate a correction table. Specifically, the control unit 10 has a degree of variation in the patch density depending on the depth of the groove of the embossed paper and the thickness of the embossed paper specified in step S420 or step S1320 (see FIG. 4 or 13). Detects the existence and generates a correction table based on the detection result. The control unit 10 saves the generated correction table in the storage unit 11, ROM 103 (see FIG. 2), or RAM 102 (see FIG. 2), and saves the saved correction table in step S450 or step S1350 (see FIG. 4 or 13). It is used to correct the variation in the density of each patch.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1,1A Image forming device, 10 Control unit, 11 Storage unit, 12 Operation unit, 13 Display unit, 14 Communication unit, 15 Paper feeding unit, 17 Image forming unit, 18 Fixing unit, 19 Conveying unit, 21 Reading unit, 22 Bus, 24 post-processing device, 25 output tray, 30 recording medium reader, 40 image reader, 101 CPU, 102 RAM, 103 ROM, 130 setting screen, 171 exposure unit, 172 photoconductor, 173 developing unit, 174 intermediate Transfer belt, 175 secondary transfer roller, C concentration correction chart, F1, F2, F3, F4 other parts, P patch, R1, R2, R3 recesses, T thickness.

Claims (10)

An image forming unit that forms a density correction image on a recording medium,
A reading unit that reads the density correction image formed on the recording medium, and
A correction unit for correcting the density of an image formed by the image forming unit based on the density of the density correction image read by the reading unit is provided.
When the recording medium is an embossed recording medium, the reading unit reads both sides of the recording medium.
The correction unit
The variation in the density of the density correction image read by the reading unit is corrected by using the correction table and the shape of the recording medium obtained by reading the recording medium by the reading unit.
An image forming apparatus that corrects the density of an image formed by the image forming unit based on the corrected density of the density correction image read by the reading unit. The shape of the recording medium obtained by reading the recording medium with the reading unit is the depth of the groove of the recording medium obtained by reading the embossed surface of the recording medium with the reading unit and the reading unit. The image forming apparatus according to claim 1, which is the thickness of the recording medium obtained by reading the embossed non-processed surface of the recording medium. The image forming apparatus according to claim 2, further comprising a specific portion for specifying the embossed surface of the recording medium based on the setting information regarding the recording medium. A storage unit for storing the correction table is further provided.
The image forming apparatus according to any one of claims 1 to 3, wherein the correction table is a table for correcting the density variation of the density correction image generated due to embossing. .. A storage unit for storing the correction table is further provided.
The correction table is a table for correcting the density variation of the density correction image caused by the embossing process.
A claim that further includes a generation unit that generates the correction table based on the shape of the recording medium obtained by reading the recording medium with the reading unit and the density of the density correction image read by the reading unit. The image forming apparatus according to any one of claims 1 to 3. An image forming unit that forms a density correction image on a recording medium,
A paper feeding unit that supplies the recording medium to the image forming unit,
A recording medium reading unit, which is arranged after the paper feeding unit and before the image forming unit and reads the recording medium,
An image reading unit arranged after the image forming unit and reading the density correction image formed on the recording medium, and an image reading unit.
A correction unit for correcting the density of an image formed by the image forming unit based on the density of the density correction image read by the image reading unit is provided.
When the recording medium is an embossed recording medium, the recording medium reading unit reads both sides of the recording medium.
The correction unit
The variation in the density of the density correction image read by the image reading unit is corrected by using the correction table and the shape of the recording medium obtained by reading the recording medium by the recording medium reading unit.
An image forming apparatus that corrects the density of an image formed by the image forming unit based on the corrected density of the density correction image read by the image reading unit. The shape of the recording medium obtained by reading the recording medium with the recording medium reading unit is the depth of the groove of the recording medium obtained by reading the embossed surface of the recording medium with the recording medium reading unit. The image forming apparatus according to claim 6, which is the thickness of the recording medium obtained by reading the embossed non-processed surface of the recording medium with the recording medium reading unit. The image forming apparatus according to claim 7, further comprising a specific portion for specifying the embossed surface of the recording medium based on the setting information regarding the recording medium. A storage unit for storing the correction table is further provided.
The image forming apparatus according to any one of claims 6 to 8, wherein the correction table is a table for correcting the density variation of the density correction image generated due to the embossing process. .. A storage unit for storing the correction table is further provided.
The correction table is a table for correcting the density variation of the density correction image caused by the embossing process.
A generation unit that generates the correction table based on the shape of the recording medium obtained by reading the recording medium with the recording medium reading unit and the density of the density correction image read by the image reading unit is further added. The image forming apparatus according to any one of claims 6 to 8.

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