JP5418174B2 - Image forming apparatus, information processing apparatus, and program - Google Patents

Description

  The present invention relates to an image forming apparatus, an information processing apparatus, and a program.

  Some calibrations performed by the image forming apparatus print color patches of various densities, measure the colors, and set image forming conditions so that each color patch is formed at the original density. . Patent Document 1 discloses that in inkjet printing, a dummy image not used for measurement is arranged on at least a part of a test image used for calibration. In Patent Document 2, streaks and unevenness occur in the surface, dummy patches are formed in places where the density uniformity is inferior, and such areas are excluded from measurement, thereby improving the calibration accuracy. It is disclosed to enhance.

JP 2003-1810 A JP 2007-30302 A

  It is an object of the present invention to form a setting image used when setting image forming conditions through a fixing process in which heat and pressure are applied to a recording medium, and is caused by the fixing process. This is to suppress the variation in the density of the setting image.

In order to solve the above-described problem, an image forming apparatus according to claim 1 of the present invention includes a conveying unit that conveys a recording medium, an image forming unit that forms an image on a recording medium conveyed by the conveying unit, and A fixing unit for fixing the image by applying heat and pressure to the recording medium transported by the transport unit so that the recording medium is an image formed by the image forming unit at a predetermined speed; Control means for controlling the image forming means to form a setting image used when setting the image forming condition, which is a condition for forming the image, to bring the density of the image close to the target density. Then, a non-setting image that is not used for setting the image forming conditions is formed, and then the setting image is formed at a position upstream of the non-setting image in the conveyance direction of the recording medium. And a that control means, when the concentration of the setting image is equal to or greater than the first threshold value, said to form a non-setting image, the concentration is less than the first threshold value In this case, the non-setting image is not formed .

According to a second aspect of the present invention, there is provided an image forming apparatus , wherein a conveying unit that conveys a recording medium, an image forming unit that forms an image on a recording medium that is conveyed by the conveying unit, and the image forming unit form an image. And a fixing unit for fixing the image by applying heat and pressure to the recording medium conveyed by the conveying unit so as to have a predetermined speed, and conditions for forming the image. Control means for controlling the image forming means to form a setting image used when setting the image forming condition so that the density of the image is close to a target density, and setting the image forming condition to form a non-setting image not used for, and control means for forming the image for setting the position of the upstream side of the recording medium than the non-image for setting followed it, the system If the density of the area on the surface of the recording medium on which the setting image is to be formed is less than a second threshold, the means forms the non-setting image having a density higher than the density of the area, The non-setting image is not formed when the density of the region is equal to or higher than the second threshold value.
According to a third aspect of the present invention, in the configuration according to the first or second aspect , when the control unit forms another image in a region where the non-setting image is formed, the control unit The non-setting image is formed after the control to widen the interval with another image is performed.

According to a fourth aspect of the present invention, there is provided an image forming apparatus, wherein a conveying unit that conveys a recording medium, an image forming unit that forms an image on a recording medium conveyed by the conveying unit, and the image forming unit form an image. And a fixing unit for fixing the image by applying heat and pressure to the recording medium conveyed by the conveying unit so as to have a predetermined speed, and conditions for forming the image. Control means for controlling the image forming means to form a setting image used when setting the image forming conditions so that the density of the image is close to a target density, and the density of the setting image Control means for forming a setting image that is longer in the conveyance direction of the recording medium than when the density is less than the first threshold. When That.

According to a fifth aspect of the present invention, in the configuration according to the fourth aspect , the control means is configured such that the density of the region on the surface of the recording medium on which the setting image is formed is less than a second threshold value. Only in this case, a setting image that is long in the transport direction is formed.
According to a sixth aspect of the present invention, in the configuration according to the fourth or fifth aspect , when the control unit forms another image in a region in which a long setting image is formed in the transport direction. Is characterized in that the setting image is formed after the control to widen the interval with the other image.

An information processing apparatus according to a seventh aspect of the present invention acquires image data representing an image obtained by reading a recording medium on which the setting image is formed by the image forming apparatus according to any one of the first to third aspects. Based on the result of reading the image area specified by the specifying means, the specifying means for specifying the image area from which the setting image is read, among the images represented by the image data acquired by the acquiring means, Setting means for setting the image forming condition so that the density of the setting image is close to the target density.

An information processing apparatus according to an eighth aspect of the present invention acquires image data representing an image obtained by reading a recording medium on which the setting image is formed by the image forming apparatus according to any one of the fourth to sixth aspects. And a specifying means for specifying an image area obtained by reading a partial area on the upstream side in the transport direction of the setting image long in the transport direction, among the images represented by the image data acquired by the acquisition means, And setting means for setting the image forming condition so that the density of the setting image is brought close to the target density based on the reading result of the image area specified by the specifying means. .

According to a ninth aspect of the present invention, there is provided a program for conveying a recording medium, an image forming unit for forming an image on a recording medium conveyed by the conveying unit, and a recording in which an image is formed by the image forming unit. A computer of an image forming apparatus having a fixing unit that fixes the image by applying heat and pressure to a recording medium conveyed by the conveying unit so as to have a predetermined speed, and forms an image Control means for controlling the image forming means to form a setting image used when setting the image forming condition, which is a condition when the image forming condition is set so as to bring the density of the image close to a target density, A non-setting image that is not used for setting the image forming conditions is formed, and then the setting image is positioned at a position upstream of the non-setting image in the conveyance direction of the recording medium. To function as a control means for causing made, said control means, when the concentration of the setting image is equal to or greater than the first threshold value, said to form a non-image for setting, in the concentration is less than the first threshold value in some cases, it characterized in that does not form the non-setting image.
According to a tenth aspect of the present invention, there is provided a program for conveying a recording medium, an image forming unit for forming an image on a recording medium conveyed by the conveying unit, and a recording in which an image is formed by the image forming unit. A computer of an image forming apparatus having a fixing unit that fixes the image by applying heat and pressure to a recording medium conveyed by the conveying unit so as to have a predetermined speed, and forms an image Control means for controlling the image forming means to form a setting image used when setting the image forming condition, which is a condition when the image forming condition is set so as to bring the density of the image close to a target density, A non-setting image that is not used for setting the image forming conditions is formed, and then the setting image is positioned at a position upstream of the non-setting image in the conveyance direction of the recording medium. When the density of the area where the setting image is formed on the surface of the recording medium is less than a second threshold, the control means functions as a control means for forming the density of the area higher than the density of the area. The non-setting image is formed, and when the density of the region is equal to or higher than the second threshold, the non-setting image is not formed .

  According to an eleventh aspect of the present invention, there is provided a program for conveying a recording medium, an image forming unit for forming an image on a recording medium conveyed by the conveying unit, and a recording in which an image is formed by the image forming unit. A computer of an image forming apparatus having a fixing unit that fixes the image by applying heat and pressure to a recording medium conveyed by the conveying unit so as to have a predetermined speed, and forms an image Control means for controlling the image forming means to form a setting image used when setting the image forming condition, which is a condition when the image forming condition is set so as to bring the density of the image close to a target density, When the density of the setting image is equal to or higher than the first threshold, a setting image that is longer in the conveyance direction of the recording medium is formed compared to the case where the density is lower than the first threshold. To function as a control means for causing.

According to the first and ninth aspects of the present invention, it is used when setting image forming conditions through a fixing process in which heat and pressure are applied to a recording medium as compared with a case where a non-setting image is not formed. When forming a setting image, it is possible to suppress changes in the density of the setting image caused by the fixing process, and it is difficult to cause a change in the density of the setting image due to the fixing process. , Ru can be omitted in the formation of non-setting image.
According to the second and tenth aspects of the present invention, it is used when setting image forming conditions through a fixing process in which heat and pressure are applied to a recording medium, compared to a case where a non-setting image is not formed. In the case of forming a setting image, it is possible to suppress fluctuations in the density of the setting image caused by the fixing process, and the density of the surface of the recording medium is reduced in the setting image caused by the fixing process. If those capable of reducing the effects of changes in concentration, Ru can be omitted in the formation of non-setting image.
According to the third aspect of the present invention, even when another image is formed at a place where the non-setting image is to be formed, the formation of these images can be prevented.
According to the inventions according to claims 4 and 11, when the image forming conditions are set through the fixing process in which heat and pressure are applied to the recording medium as compared with the case where the setting image long in the transport direction is not formed. In the case of forming the setting image used in the above, it is possible to suppress the density fluctuation caused by the fixing process in the region used for setting the image forming condition of the setting image.
According to the fifth aspect of the present invention, when the density of the surface of the recording medium can reduce the influence of the density variation of the setting image due to the fixing process, the setting image is formed. It is possible to reduce the amount of the color material used for.
According to the sixth aspect of the present invention, even when another image is formed at a place where a setting image that is long in the conveyance direction of the recording medium is to be formed, the formation of these images is not hindered. be able to.
According to the inventions according to claims 7 and 8 , when setting the image forming conditions of the image forming apparatus based on the setting image formed through the fixing process of applying heat and pressure to the recording medium, The decrease in accuracy caused by the fixing process can be suppressed.

1 is a diagram illustrating a configuration of an image forming apparatus. It is a figure which shows the structure of an image formation part and a reading part. It is a figure showing a test chart. 6 is a graph illustrating an example of a recording sheet conveyance speed. It is a figure showing a test chart. It is a figure explaining the area | region of the image for a setting used for a calibration. It is a figure explaining the control which a control part performs.

[First Embodiment]
First, a first embodiment of the present invention will be described.
FIG. 1 is a block diagram showing a configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention. The image forming apparatus 10 of the present embodiment includes a control unit 100, an image forming unit 200, an operation unit 300, a communication unit 400, a storage unit 500, and a reading unit 600.

  The control unit 100 is an example of a control unit of the present invention, and includes an arithmetic device including a CPU (Central Processing Unit) and a memory. The arithmetic unit of the control unit 100 controls each unit of the image forming apparatus 10 by executing a control program stored in the memory. For example, the control unit 100 performs control related to calibration of the image forming apparatus 10. The image forming unit 200 forms an image on a recording medium using toner as a color material. The recording medium is, for example, a recording sheet, but may be a plastic such as an OHP sheet or a sheet of other materials, and may be any medium that can record an image on the surface. The image forming unit 200 is an image forming unit that employs an area gradation method, and uses an electrophotographic process using toner of four colors of yellow (Y), magenta (M), cyan (C), and black (K). To form an image.

  The operation unit 300 includes operation elements such as buttons, and supplies operation information representing the operation content to the control unit 100 in accordance with a user operation. The communication unit 400 includes an interface for transmitting / receiving data to / from an external device. The storage unit 500 includes a storage device such as an HDD (Hard Disk Drive), and stores, for example, image data for forming an image. The reading unit 600 optically reads the surface of the recording paper and generates image data representing the read image.

FIG. 2 is a diagram illustrating the configuration of the image forming unit 200 and the reading unit 600.
Among the reference numerals of the image forming unit 200 shown in FIG. 2, the alphabet attached to the end corresponds to the color of toner handled by the image forming apparatus. The configuration in which only the alphabet at the end of the code differs differs in the color of the toner to be handled, but the configuration is the same. In the following description, when it is not necessary to distinguish each of these components, the description will be made with the alphabet at the end of the reference numerals omitted.
The recording sheet conveyed through the image forming apparatus 10 is conveyed in the direction of the broken arrow C shown in FIG. 2, and an image is formed on the recording sheet.
The photosensitive drum 210 is a cylindrical member having a photoconductive film laminated on the surface. The photosensitive drum 210 holds an electrostatic latent image formed on the surface. When the photosensitive drum 210 is in contact with the intermediate transfer belt 250, the center of the cylinder is the axis (in the direction perpendicular to the paper in FIG. 1) as the intermediate transfer belt 250 moves. Rotate to. The charging device 220 charges the photoconductive film of the photosensitive drum 210 to a predetermined potential. The exposure device 230 exposes the photosensitive drum 210 charged by the charging device 220 to form a latent image corresponding to the exposure light. The developing device 240 has a developer containing toner of any color of Y, M, C, and K and a magnetic material such as ferrite powder. The developing device 240 attaches toner to the latent image formed on the photosensitive drum 210 and develops it to form a toner image.

The intermediate transfer belt 250 is an endless belt-like member, and rotates in the direction of arrow B in the figure while being in contact with the rotary roll 251, the primary transfer roll 260 and the backup roll 271. The rotary roll 251 is a cylindrical member that supports the movement of the intermediate transfer belt 250 and rotates around the center of the cylinder. The primary transfer roll 260 is a cylindrical member that faces the photosensitive drum 210 with the intermediate transfer belt 250 interposed therebetween. The primary transfer roll 260 generates a potential difference with the photosensitive drum 210 to transfer the toner on the surface of the photosensitive drum 210 to the surface of the intermediate transfer belt 250. The secondary transfer roll 270 transfers an image obtained by the development of the developing device 240 onto a recording sheet. The secondary transfer roll 270 is a cylindrical member that faces the backup roll 271 with the intermediate transfer belt 250 interposed therebetween, and generates a potential difference between the secondary transfer roll 271 and the toner on the surface of the intermediate transfer belt 250 as recording paper. Transfer to the surface. The transport roll 280 is a cylindrical member that is driven by a driving device (not shown) and transports the recording paper in the direction of the broken arrow C shown in FIG. The transport roll 280 is rotated so that, for example, the rotation speed is constant so that the recording paper is transported at a predetermined transport speed.
Each configuration described above of the image forming unit 200 functions as an example of an image forming unit of the present invention that forms an image (toner image) on a recording medium.

The fixing device 290 is an example of a fixing unit of the present invention, and includes a fixing roll 291 and a pressure roll 292. The fixing device 290 performs a fixing process for applying heat and pressure to a recording sheet on which an image is transferred and conveyed in a nip region N that is a region sandwiched between a fixing roll 291 and a pressure roll 292. The image is fixed on the recording paper.
In the image forming apparatus 10, at least the control unit 100 and the transport roll 280 perform an operation for transporting the recording paper, that is, function as an example of the transport unit of the present invention.

The reading unit 600 is provided on the downstream side of the position of the fixing device 290 with respect to the conveyance direction of the recording paper (that is, the direction of arrow C shown in FIG. 2). That is, the reading unit 600 reads the surface of the recording paper after the fixing process is performed by the fixing device 290. The reading unit 600 includes a light source, an imaging lens, a line sensor, and a signal processing circuit. The light source is, for example, a fluorescent lamp, and irradiates light onto the conveyed recording paper. The imaging lens images reflected light from the recording paper at the position of the line sensor. The line sensor receives the imaged light and generates an image signal corresponding to the light. The line sensor includes an image sensor that captures images of three colors of R (red), G (green), and B (blue), and generates image signals of these three colors. The signal processing circuit performs processing such as A / D conversion on the image signal to generate image data, and outputs the image data to the control unit 100.
The reading unit 600 performs reading to obtain a color measurement result of an image used for calibration of the image forming apparatus 10.

Next, calibration performed in the image forming apparatus 10 will be described.
The calibration of the image forming apparatus 10 is performed in order to set the image forming conditions so that the density of the image expressed by the area gradation method is brought close to the target density that is the target density. “Density” in this embodiment is an optical density, which is a physical quantity that correlates with the amount of toner arranged per unit area. For example, the concentration D satisfies the relationship D = −log (I / Io). Here, Io is the amount of detection light emitted by the light source of the reading unit 600, and I is the amount of reflected light received by the line sensor of the reading unit 600. In the image expressed by the area gradation method, the toner coverage on the base of the recording medium per unit area (here, the surface of the recording paper) is hereinafter referred to as “image density”.

FIG. 3 shows a test chart TC. The test chart TC is used for calibration of the image forming apparatus 10. The arrows shown in FIG. 3 indicate the conveyance direction of the recording paper when the test chart TC is formed by the image forming unit 200.
The test chart TC includes a setting image and a non-setting image. Each rectangle shown in FIG. 3 corresponds to one setting image or one non-setting image. These setting image and non-setting image are images having the same shape and the same size. Here, the setting image and the non-setting image use one or a plurality of toners of Y, M, C, and K, and the image density in the region is the same. Also, reference numerals of the setting images and the non-setting images, and Y, M, C, and K shown inside each rectangle in FIG. 3 represent the colors of the images. Specifically, Y, M, C, and K represent primary colors using any one of them, and MC, YM, YC, and MK represent two colors corresponding to Y, M, C, and K codes, respectively. Represents a combined secondary color, and YMC is a tertiary color combining three colors Y, M, and C. Also, the number attached to the end of the code of the setting image represents the image density. Images having the same value have the same image density, and the larger the value, the lower the image density. For example, the setting images K1 to K11 are 99.6%, 80%, 60%, 50.2%, 40%, 30.2%, 20%, 10.2%, 7.8%, 5. The image density is 1% and 0.4%, and each is a black (K) image.

The test chart TC is MC, YM, YC, K, C, M, Y, YMC, MK, C, from the left side to the right side in the drawing in the direction orthogonal to the recording sheet conveyance direction indicated by the arrow in FIG. The image for setting M and Y and the image for non-setting are arranged side by side. That is, toner images are transferred by the image forming unit 200 at the same time and the fixing process is performed at the same time between images having the same position in the conveyance direction of the recording paper. Further, the setting image and the non-setting image arranged in a line in the recording sheet conveyance direction are arranged so as to contact each other in the direction, and no gap is provided between the images here.
In the following description, among setting image groups arranged in the conveyance direction of the recording paper, the setting image having the most downstream side in the conveyance direction (that is, the head of the setting image group and the end of the code is “1”). ) May be collectively referred to as “setting image 1”. That is, the image density of “setting image 1” is 99.6%.

The setting image included in the test chart TC is an image in which the color measurement result is used for setting image forming conditions in the calibration performed by the image forming apparatus 10. On the other hand, the non-setting image is an image that is not used for setting image forming conditions in this calibration. As shown in FIG. 3, a non-setting image has “u” added to the end of the reference numeral. Here, each non-setting image has the same color and the same image density as the setting image adjacent to the upstream side in the conveyance direction of the recording paper (for example, the setting image MC1 in the case of the non-setting image MCu). (That is, 99.6%). That is, each setting image is apparently the same image as the setting image adjacent thereto.
In the following description, the non-setting images may be collectively referred to as “non-setting images u” when it is not necessary to distinguish the non-setting images.

Next, a calibration procedure performed in the image forming apparatus 10 will be described.
The control unit 100 performs calibration when the user is instructed to perform calibration by operating the operation unit 300 or when a predetermined time (for example, when the image forming apparatus 10 is activated) has arrived. To implement.
First, the control unit 100 controls the image forming unit 200 so that the test chart TC having the contents shown in FIG. 3 is formed on the recording paper. At this time, the control unit 100 forms the non-setting image u and subsequently forms the setting image sequentially at a position upstream of the non-setting image u in the transport direction. Next, the control unit 100 causes the reading unit 600 to read the surface of the recording sheet after the test chart TC is formed and the fixing device 290 performs the fixing process. The control unit 100 acquires image data representing the read image from the reading unit 600. The control unit 100 specifies an image area in which the setting image is read out of the images represented by the acquired image data. Next, the control unit 100 specifies the density D of each setting image based on the reading result of the specified image area. Then, the control unit 100 compares the density D of each of the setting images with the target density, which is the target density, and the image of the image forming unit 200 so as to reduce the density difference. Set the formation conditions.
Since the position of the non-setting image u in the test chart TC is determined in advance, the control unit 100 specifies the position so that the reading unit 600 does not read the non-setting image u. Good.
The control unit 100 that performs the above control is an example of an acquisition unit, an identification unit, and a setting unit of the present invention.

The image forming condition of the image forming unit 200 is, for example, a toner replenishment amount from a toner box (not shown) to the developing device 240. Specifically, the control unit 100 performs control to increase the density of the setting image by increasing the toner supply amount as the density D is lower than the target density. On the contrary, as the density of the setting image is higher than the target density, the control unit 100 performs control to decrease the density of the setting image by decreasing the toner supply amount. An algorithm indicating the relationship between the density and target density of the setting image and the toner supply amount is described in, for example, a control program. When the image forming conditions are set, the control unit 100 thereafter controls the image forming unit 200 to execute the image forming process according to the image forming conditions.
Note that other image forming conditions may be used. For example, the exposure light amount of the exposure device 230 (exposure amount), the charging potential when the charging device 220 charges the photosensitive drum 210, the developing bias of the developing device 240, the transfer potential of the primary transfer roll 260, and the like. Further, an image forming condition in which a plurality of these are combined may be employed. Whatever image forming conditions are employed, the control unit 100, when performing calibration, sets the image density so as to approach the target density based on the colorimetric result of the setting image. Set the formation conditions.

Next, the operation of the non-setting image u will be described.
FIG. 4 is a graph showing a time-series transition of the conveyance speed of the recording paper P during the calibration period. In the graph of FIG. 4, the horizontal axis represents time, and the vertical axis represents the magnitude of the conveyance speed of the recording paper P.
During the calibration, the control unit 100 controls each part of the image forming unit 200 such as the transport roll 280 so that the recording paper P is transported while maintaining the determined speed. However, when a region on the recording paper P where a toner image is formed (hereinafter referred to as “toner image region”) enters the nip region N, the conveyance force of the recording paper may decrease. This occurs when a region that is not a toner image region on the recording paper is located in the nip region N, and a state in which the toner image region is located in the nip region N is changed.

  That is, even if the control unit 100 performs control for maintaining the conveyance speed of the recording paper P at a predetermined speed, the conveyance speed changes in the illustrated section I as shown in FIG. At the time after section I, the transport speed is returned to the original speed, and the transport speed is maintained constant again. As described above, when the toner image area is subjected to the fixing process in the section I in which the recording paper conveyance speed is changed, the fixability of the toner image area differs at each position. This fixability is determined by time integration of the amount of heat and pressure applied to the toner image. Therefore, if a change occurs in the conveyance speed of the recording paper when the fixing process is performed on the toner image area including the setting image, the density of the setting image differs in the fixing property at each position, and the density is caused by this. It becomes non-uniform. More specifically, a position where the fixing process is excessively performed occurs due to a decrease in the speed of the recording paper, and an area having a density lower than the intended density appears depending on the material and color of the surface of the recording paper. If this density variation occurs in the setting image, it causes a reduction in calibration accuracy.

In order to suppress the density fluctuation of the setting image 1 due to the above reasons, the test chart TC is subjected to fixing processing of the non-setting image u by the fixing device 290 during the period when the recording sheet conveyance speed is changing. It is configured as follows. That is, the density fluctuation caused by the fixing process is caused in the non-setting image u, and the density fluctuation is not caused in the setting image 1. In this way, the image forming apparatus 10 forms the non-setting image u and subsequently forms the setting image 1, so that the setting image is displayed during a period in which the conveyance speed of the recording paper is substantially constant. The density variation is suppressed by forming. Thereby, compared with the case where the non-setting image u is not used, the accuracy of calibration performed by the image forming apparatus 10 is increased.
Note that the setting image on the downstream side in the conveyance direction of the recording paper with respect to the setting image 1 is formed with an image having a higher density immediately before the setting image. Concentration fluctuation is not a problem.

  In the test chart TC, the non-setting image u and the setting image 1 formed so as to be adjacent to each other in the conveyance direction of the recording paper are in contact with each other, but a gap is provided between these images. Also good. The distance between the images in this case is experimentally set beforehand, for example, so that the density variation does not occur in the toner image region of the setting image due to the fixing process or falls within the density variation allowed in the calibration accuracy. What is necessary is just to make it become the threshold value calculated | required by. As an example of this specific mode, the distance is set such that there is a period in which both the non-setting image u and the setting image 1 are located in the nip region N of the fixing device 290.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
Since the apparatus configuration of the image forming apparatus of the second embodiment is the same as that of the image forming apparatus 10 of the first embodiment, the description thereof is omitted. The image forming apparatus 10 of the second embodiment is different from the configuration of the first embodiment in that a test chart TCa is used when performing calibration.
In the following description, each component having the same reference numeral as that in the first embodiment is the same as that described in the first embodiment, and thus the description thereof is omitted.

  FIG. 5 shows a test chart TC. In the following description, among the setting image groups arranged in the conveyance direction of the recording paper, the most downstream side in the conveyance direction (that is, the setting image that is the head of the setting image group and the end of the code is “1a”). Positioned objects may be collectively referred to as “setting image 1a”. The test chart TCa does not include the non-setting image u and is the head of the setting image group, and for the setting image whose code ends with “1a”, each setting formed subsequently to the setting image. The image is longer in the conveyance direction than the image for use. In addition, when the density of the first setting image is equal to or higher than the threshold Th1 (first threshold), the control unit 100 is longer in the recording sheet conveyance direction than when the density is lower than the threshold Th1. The setting image 1a (about twice as long) is formed. That is, if the density of the first setting image with respect to the conveyance direction of the recording paper is equal to or higher than the threshold Th1, the control unit 100 forms the test chart TCa shown in FIG. If the density is less than the threshold Th1, instead of the setting image 1a, a setting image having the same form as the setting image 1 included in the test chart TC shown in FIG. A test chart is formed, which may be referred to as “1”.

FIG. 6 is a diagram for explaining a setting image area used for calibration. Although only the setting image MC1a will be described here, the contents are common to the setting images 1a for the respective colors.
As shown in FIG. 6, the density fluctuation due to the fixing process is likely to occur on the downstream side of the region where the setting image 1a is formed for the same reason as described in the first embodiment. On the other hand, the upstream region of the region in which the setting image MC1a is formed is subjected to the fixing process in a state where the conveyance speed is substantially constant, so that the density fluctuation hardly occurs. Therefore, when the calibration is performed, the control unit 100 obtains the colorimetric results of the downstream area (for example, the downstream half area) of the installation image MC1a as shown in FIG. Instead of using the calibration, the color measurement results of a part of the upstream region (for example, the half region on the upstream side) are used for the calibration. With this configuration, the accuracy of calibration performed by the image forming apparatus 10 is improved as compared with the case where the setting image is shorter in the conveyance direction of the recording paper than the setting image 1a.

  The reason why the setting image 1a is not formed when the density of the first setting image 1a is less than the threshold Th1 is as follows. When the density of the setting image is low, the amount of toner attached to the recording paper P is small. At this time, the amount of toner that dissolves in the recording paper P is not easily affected by the period of the fixing process, and density fluctuations caused by the fixing process are unlikely to occur. Therefore, a threshold value Th1 at which the density fluctuation caused by the fixing process adversely affects the calibration is obtained in advance and described in the program. The control unit 100 forms the setting image 1a that is long in the transport direction only when the density of the setting image is equal to or higher than the threshold Th1. Accordingly, when the density of the setting image is hardly changed due to the fixing process, it is possible to suppress the amount of toner consumed when performing calibration.

Next, the calibration performed in the image forming apparatus 10 will be described mainly with respect to contents different from those in the first embodiment.
The control unit 100 acquires image data representing an image obtained by reading the recording sheet on which the test chart TC is formed from the reading unit 600. The control unit 100 reads an image area obtained by reading a part of the setting image 1a on the upstream side in the conveyance direction of the recording paper from the image represented by the acquired image data, and each setting subsequent to the setting image 1a. The image area from which the image for reading is read is specified. This partial area is, for example, an area in a range determined from the end on the upstream side in the recording paper conveyance direction, and does not cause density fluctuations caused by the fixing process or is allowed in calibration accuracy. This is an area that falls within the concentration fluctuation to be obtained. Further, in this area, when attention is paid to the density transition with respect to the conveyance direction of the recording paper, the density becomes constant, or the density fluctuation allowable in the calibration accuracy (for example, density fluctuation below a threshold value). It is an area that fits in Then, the control unit 100 specifies the density D of each setting image based on the reading result of the specified image area. Then, the control unit 100 compares the density D for each of the setting images with the target density that is the target density, and the image of the image forming unit 200 is reduced so that the density difference between these is small. Set the formation conditions.
Note that the control unit 100 specifies a position on the downstream side in the transport direction in the setting image 1a at which density fluctuation due to the fixing process may occur, and does not cause the reading unit 600 to read the non-setting image u. You may do it.

[Modification]
The present invention can be implemented in a form different from the above-described embodiment. Moreover, you may combine each of the modification shown below.
[Modification 1]
In the first embodiment described above, the image forming apparatus 10 always forms the non-setting image u further downstream than the position of the first setting image 1, but only when a certain condition is satisfied. The non-setting image u may be formed.
For example, similarly to the second embodiment, when the density of the setting image 1 is equal to or higher than the threshold Th1 (first threshold), the control unit 100 forms the non-setting image u and the density is If it is less than the threshold Th1, the non-setting image u may not be formed. As a result, when it is difficult for the density of the setting image 1 to vary due to the fixing process, the formation of the non-setting image u is omitted, so that the amount of toner consumed during calibration can be suppressed. .

In the first embodiment described above, the control unit 100 determines that the surface of the recording sheet has a density less than the threshold Th2 (second threshold) in the area where the setting image 1 on the surface of the recording sheet is to be formed. If the non-setting image u having a higher density than the above-described density is formed and the density is equal to or higher than the threshold Th2, the non-setting image u may not be formed. This density is the density of the same color as the setting image 1 arranged at the head in the transport direction.
As described above, the density fluctuation is likely to occur in the setting image 1 having a relatively high density. However, when the density on the paper surface is high, the density fluctuation has little influence on the colorimetric result of the setting image 1. It can be said. According to this configuration, when the density of the surface of the recording medium can reduce the influence of the density variation of the setting image 1 caused by the fixing process, the non-setting image u is formed. Omitting the toner consumption can be suppressed. On the other hand, the reason for using the non-setting image u whose density is higher than the density of the surface of the recording paper is to reduce the influence of the density of the surface of the paper itself.
In the case of this configuration, the control unit 100 may specify the density of the recording paper based on the density designated in advance by the user, and determine whether or not the non-setting image u is formed based on the density. Further, the image forming apparatus 10 may include a sensor for reading the surface of the recording paper. In this case, the control unit 100 specifies the density of the recording sheet from the reading result of the sensor, and determines whether or not the non-setting image u is formed based on whether or not the specified density is equal to or higher than the threshold Th2.
Further, the reading result of the reading unit 600 may be used. In this case, the control unit 100 reads the area downstream in the transport direction from the area where the setting image 1 is to be formed, identifies the density of the recording paper, and determines whether or not the non-setting image u is formed based on the identification result. Judging. This is because in this case, the control unit 100 specifies (estimates) the density of the region where the setting image 1 is formed on the surface of the recording paper.

The configuration of this modification may be applied to the image forming apparatus 10 of the second embodiment described above. In this case, when the density of the area where the setting image on the surface of the recording paper is to be formed is less than the threshold Th2 (second threshold), the control unit 100 forms the test chart TCa including the setting image 1a. When the density is equal to or higher than the threshold Th2, a test chart using the setting image 1 is formed instead of the setting image 1a. The density here is the density for the same color as the setting image 1a formed at the head in the conveyance direction of the recording paper.
In this modified example, the control unit 100 is combined with the configuration of the modified example 1, and when the density of the setting image is equal to or higher than the threshold Th1 and the density of the recording paper surface is lower than the threshold Th2, The image u may be formed, or the setting image 1a long in the transport direction may be formed.
In the configuration of this modification, attention may be paid to the difference between the density of the recording paper surface and the density of the setting image formed there. In this case, only when the difference is equal to or greater than the threshold value, the control unit 100 forms the non-setting image u or forms a setting image that is long in the transport direction.

[Modification 2]
In the first embodiment described above, when the control unit 100 forms another image in the region where the non-setting image u is to be formed, the control unit 100 performs control to increase the interval with the other image, and then performs non-setting. A working image u may be formed. Hereinafter, the configuration of this modified example will be described using the MC set image group as an example.
For example, the image forming apparatus 10 may form a certain image F and subsequently form a test chart for calibration. At this time, the positional relationship between the setting image MC1 and the setting image F may be determined so as to be continuously arranged in the transport direction as shown on the left side of FIG. In this case, when the control unit 100 tries to form the non-setting image MCu upstream of the setting image MC1, the positions of the non-setting image MCu and the setting image F overlap, and these images are overlapped. May interfere with formation. Therefore, as shown on the right side of FIG. 7A, the control unit 100 performs control to increase the interval between the image F and the setting image MC1, and then forms the non-setting image MCu. More specifically, for example, when another image is formed before the test chart TC, the control unit 100 feeds an extra sheet to ensure at least an area for forming the non-setting image MCu. From this, the setting image MC1 is formed.

This configuration can also be applied to the image forming apparatus 10 of the second embodiment. In this case, in the aspect shown on the left side of FIG. 7B, the setting image F and the setting image MC1a that is an aspect in which the setting image MC1 is extended to the downstream side may overlap each other. Therefore, as shown on the right side of FIG. 7B, the control unit 100 increases the interval between the image F and the setting image MC1 when another image is formed before the setting image MC1a. , The setting image MC1a is formed.
Note that the same effect can be obtained when another image is used instead of the setting image F. For example, the image forming apparatus 10 may simultaneously perform calibration for correcting a deviation of a position where an image is formed from a reference position. In this case, the above control may be performed so as not to prevent the formation of the image used for the calibration and the setting image.

[Modification 3]
In the first embodiment described above, the image forming apparatus 10 forms the setting image group whose density gradually decreases from the downstream side to the upstream side in the conveyance direction of the recording paper. May be. That is, there may be a mode in which the setting image that may cause density fluctuation due to the fixing process is not the head of the setting image group.
Even in this case, when the control unit 100 forms a certain setting image, the density difference from the image formed immediately before the control image is equal to or greater than a threshold value (allowable amount of density fluctuation due to fixing processing). In some cases, the non-setting image is formed so as to suppress the density fluctuation of the setting image, and subsequently, the setting image is formed.
In the configuration of the second embodiment, when forming a certain setting image, the control unit 100 has a density equal to or higher than the threshold Th1 and a density difference from the image formed immediately before the threshold (fixing). If it is equal to or greater than the allowable density fluctuation due to processing), the setting image may be formed by extending the setting image in the recording sheet conveyance direction.

[Modification 4]
In the embodiment described above, the control unit 100 sets the conveyance speed to a predetermined speed during a period in which at least the setting image is located in the nip area N and the fixing process is performed on the toner image area. It is advisable to carry out the recording paper by carrying out various controls.
In each of the embodiments described above, the test charts TC and TCa include 11 setting images for each color. However, the number of these images may be any number, and the number may be any number if one or more. .
Further, the non-setting image u and the setting image that are continuously formed do not necessarily have to be formed so as to have a toner image region having the same density, and the colors of both are different. Also good. That is, any non-setting image having a density that suppresses a change in the conveyance speed of the recording paper when the setting image is formed may be used.

  Each function realized by the control unit 100 of the above-described embodiment may be realized by one or a plurality of hardware, or may be realized by executing one or a plurality of programs. In particular, in the calibration performed by the image forming apparatus 10, an external information processing apparatus may perform each process after reading the test chart to set the image forming conditions of the image forming apparatus 10. In this case, the information processing apparatus communicates with the communication unit 400 of the image forming apparatus 10 via a communication path such as a communication cable. The information processing apparatus transmits an instruction signal for instructing setting of image forming conditions to the image forming apparatus 10. The control unit 100 of the image forming apparatus 10 receives the instruction signal through the communication unit 400 and sets image forming conditions based on the instruction signal. In the configuration of each of the above-described embodiments, the control unit 100 is equivalent to a configuration that functions as the information processing apparatus.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 100 ... Control part, 200 ... Image forming part, 210 ... Photosensitive drum, 220 ... Charging apparatus, 230 ... Exposure apparatus, 240 ... Developing apparatus, 250 ... Intermediate transfer belt, 251 ... Rotating roll, 260 ... primary transfer roll, 270 ... secondary transfer roll, 271 ... backup roll, 280 ... transport roll, 290 ... fixing device, 291 ... fixing roll, 292 ... pressure roll, 30 ... exposure device, 300 ... operation unit, 400 ... Communication unit, 500... Storage unit.

Claims (11)

Conveying means for conveying the recording medium;
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing unit for fixing the image by applying heat and pressure to the recording medium transported by the transport unit so that the recording medium is an image formed by the image forming unit and having a predetermined speed;
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. And a control for forming a non-setting image that is not used for setting the image forming conditions and subsequently forming the setting image at a position upstream of the non-setting image in the conveyance direction of the recording medium. Means and
With
The control unit forms the non-setting image when the density of the setting image is equal to or higher than a first threshold, and when the density is lower than the first threshold, the non-setting is performed. images forming device you characterized by not forming a use images. Conveying means for conveying the recording medium;
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing unit for fixing the image by applying heat and pressure to the recording medium transported by the transport unit so that the recording medium is an image formed by the image forming unit and having a predetermined speed;
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. And a control for forming a non-setting image that is not used for setting the image forming conditions and subsequently forming the setting image at a position upstream of the non-setting image in the conveyance direction of the recording medium. Means and
With
When the density of the area on the surface of the recording medium on which the setting image is to be formed is less than the second threshold, the control unit causes the non-setting image to be formed with a density higher than the density of the area. , when the concentration of the region is not less than the second threshold value, images forming device you characterized in that does not form the non-setting image. Before SL control means when said another image is formed in a region for forming a non-setting image, after performing control to widen the gap between the different images, thereby forming the non-setting image the image forming apparatus according to claim 1 or 2, characterized in that. And transport means for transporting the record medium,
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing unit for fixing the image by applying heat and pressure to the recording medium transported by the transport unit so that the recording medium is an image formed by the image forming unit and having a predetermined speed;
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. When the density of the setting image is equal to or higher than the first threshold, a setting image that is longer in the conveyance direction of the recording medium is formed than when the density is lower than the first threshold. And an image forming apparatus. Before SL control means, the concentration of a region for forming the image for setting the surface of the recording medium only when it is less than the second threshold value, characterized in that to form long image for setting the transport direction The image forming apparatus according to claim 4 . Before Symbol control means,
When another image is formed in a region where a setting image that is long in the transport direction is formed, the setting image is formed after performing a control to widen the interval with the other image. The image forming apparatus according to claim 4 or 5 . An acquisition unit that acquires image data representing an image read a recording medium in which the setting image is formed by the image forming apparatus according to any one of 3 to 請 Motomeko no 1,
A specifying unit that specifies an image region in which the setting image is read out of images represented by the image data acquired by the acquiring unit;
And setting means for setting the image forming condition so that the density of the setting image is brought close to the target density based on the reading result of the image region specified by the specifying means. Information processing apparatus. An acquisition unit that acquires image data representing an image read a recording medium in which the setting image is formed by the image forming apparatus according to any one sixth to 請 Motomeko 4 no,
A specifying unit for specifying an image region obtained by reading a partial region on the upstream side in the transport direction of the image for setting long in the transport direction, among images represented by the image data acquired by the acquisition unit;
And setting means for setting the image forming condition so that the density of the setting image is brought close to the target density based on the reading result of the image region specified by the specifying means. Information processing apparatus. And transport means for transporting the record medium,
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing means for fixing the image by applying heat and pressure to the recording medium transported by the transporting means so that the recording medium is an image formed by the image forming means at a predetermined speed; A computer of an image forming apparatus having
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. And a control for forming a non-setting image that is not used for setting the image forming conditions and subsequently forming the setting image at a position upstream of the non-setting image in the conveyance direction of the recording medium. Function as a means ,
The control means causes the non-setting image to be formed when the density of the setting image is equal to or higher than a first threshold, and the non-setting when the density is lower than the first threshold. A program characterized by not forming an image for use . Conveying means for conveying the recording medium;
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing means for fixing the image by applying heat and pressure to the recording medium transported by the transporting means so that the recording medium is an image formed by the image forming means at a predetermined speed; A computer of an image forming apparatus having
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. And a control for forming a non-setting image that is not used for setting the image forming conditions and subsequently forming the setting image at a position upstream of the non-setting image in the conveyance direction of the recording medium. means
Function as
When the density of the area on the surface of the recording medium on which the setting image is to be formed is less than the second threshold, the control unit causes the non-setting image to be formed with a density higher than the density of the area. The non-setting image is not formed when the density of the area is not less than the second threshold value. Conveying means for conveying the recording medium;
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A fixing means for fixing the image by applying heat and pressure to the recording medium transported by the transporting means so that the recording medium is an image formed by the image forming means at a predetermined speed; A computer of an image forming apparatus having
A control unit that controls the image forming unit to form a setting image used when setting the image forming condition, which is a condition for forming an image, to bring the density of the image close to the target density. When the density of the setting image is equal to or higher than the first threshold, a setting image that is longer in the conveyance direction of the recording medium is formed than when the density is lower than the first threshold. A program for functioning as a control means.

Images