JP2014126637A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of toner when forming a plurality of patches while suppressing a reduction in productivity in an image forming apparatus.SOLUTION: When a timing of forming first patches and a timing of forming second patches are in a predetermined relationship, a control unit forms third patches having applications of the first patches and second patches in place of forming the first patches and second patches.

Description

  The present invention relates to an image forming apparatus that forms a predetermined patch on an image carrier.

Conventionally, in an image forming apparatus, it is known to form various patches having a predetermined use such as density correction on an image carrier such as a photosensitive drum or an intermediate transfer belt.
Further, by forming these patches between the printing images on the image carrier during the image forming operation, the patches can be formed without stopping the image forming operation, and the reduction in productivity can be suppressed. .
For example, Patent Document 1 describes an image forming apparatus that forms a toner pattern such as each color gradation pattern, chevron patch, and toner consumption pattern in a non-image forming area (between sheets) on an intermediate transfer belt (for example, FIG. 7 of Patent Document 1).

JP 2012-198303 A

In the image forming apparatus described in Patent Document 1, for example, the toner consumption pattern and each color gradation pattern are formed separately even when the formation timings are close in time.
Here, instead of separately forming a plurality of patches, a patch having a plurality of patch applications can be formed. For example, if the amount of toner consumed when forming the toner consumption pattern is less than the amount of toner consumed when forming each color gradation pattern, the required amount of toner will be consumed if only each color gradation pattern is formed. Therefore, it is not necessary to form a toner consumption pattern separately from each color gradation pattern. In this case, each color gradation pattern itself is a “patch having a plurality of patch applications”.
However, in the image forming apparatus described in the above-mentioned Patent Document 1, patches are formed separately without forming patches having a plurality of patch applications. Therefore, it can be said that toner is wasted in terms of toner consumption compared to the case of forming a patch having a plurality of types of patch applications.

  SUMMARY An advantage of some aspects of the invention is that it reduces toner consumption when forming a plurality of patches while suppressing a decrease in productivity in an image forming apparatus.

The present invention provides the following means. That is,
In an image forming apparatus having an image forming unit that forms an image for printing on an image carrier, and a control unit that controls the image forming unit,
The image forming unit forms a first patch and a second patch having a predetermined use between printing images on the image carrier at a predetermined timing,
When the timing for forming the first patch and the timing for forming the second patch are in a predetermined relationship, the first patch and the second patch are used instead of the first patch and the second patch. An image forming apparatus, wherein the image forming unit is controlled so as to form a third patch having a use of the patch.

  According to the image forming apparatus of the present invention, it is possible to reduce toner consumption when forming a plurality of patches while suppressing a decrease in productivity in the image forming apparatus.

1 is an overall configuration diagram illustrating a configuration example of an image forming apparatus according to the present invention. 1 is a block diagram illustrating a configuration of an image forming apparatus 1. FIG. It is a figure which shows an example of the shape of a toner consumption patch. It is a figure which shows an example of the shape of an intermediate transfer belt cleaning patch. It is a figure which shows an example of the shape of a secondary transfer belt cleaning patch. It is a figure which shows an example of the shape of the division patch between images. It is a figure which shows an example of the shape of the dot diameter patch between images. It is a flowchart which shows an example of the control method in control which forms a 3rd patch. It is a figure which shows the outline of the time series in the control which forms a 3rd patch. It is a flowchart which shows an example of the detailed control method of 3rd patch formation availability determination control. It is a flowchart which shows an example of the detailed control method of 3rd patch formation condition determination control. It is a figure which shows the shape of the 3rd patch determined in Example 1. FIG. It is a time series figure explaining the 3rd patch formation timing decision control. 10 is a flowchart illustrating an example of a detailed control method of third patch formation availability determination control in the image forming apparatus according to Embodiment 4; 14 is a flowchart illustrating a third patch formation control method in the image forming apparatus according to the fifth embodiment. FIG. 10 is a diagram illustrating an example of a plurality of patches divided in an image forming apparatus according to a sixth embodiment. 14 is a flowchart illustrating a third patch formation control method in the image forming apparatus according to the sixth embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

Example 1
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Configuration of image forming apparatus]
FIG. 1 is an overall configuration diagram showing a configuration example of an image forming apparatus according to the present invention. As shown in FIG. 1, the image forming apparatus 1 forms an image on a sheet by an electrophotographic method, and has four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). This is a tandem color image forming apparatus that superimposes toner. The image forming apparatus 1 includes a document conveying unit 10, a paper storage unit 20, an image reading unit 30, an image forming unit 40, an intermediate transfer unit 50, a secondary transfer unit 60, a fixing unit 80, and a control. A substrate 100.

  The document transport unit 10 includes a document feeder 11 on which a document is set, a plurality of rollers 12, a transport drum 13, a transport guide 14, a document discharge roller 15, and a document discharge tray 16. The documents G set on the document feeder 11 are conveyed one by one to the reading position of the image reading unit 30 by the plurality of rollers 12 and the conveying drum 13. The conveyance guide 14 and the document discharge roller 15 discharge the document G conveyed by the plurality of rollers 12 and the conveyance drum 13 to the document discharge tray 16.

The image reading unit 30 reads an image of the document G transported by the document transport unit 10 or the document placed on the document table 31 and generates image data. Specifically, the image of the original G is irradiated by the lamp L. The reflected light from the document G is guided in the order of the first mirror unit 32, the second mirror unit 33, and the lens unit 34 and forms an image on the light receiving surface of the image sensor 35. The image sensor 35 photoelectrically converts incident light and outputs a predetermined image signal. The output image signal is created as image data by A / D conversion.
The image reading unit 30 has an image reading control unit 36. The image reading control unit 36 performs processing such as shading correction, dither processing, and compression on the image data created by the A / D conversion, and stores the processed data in the RAM of the control board 100. The image data is not limited to data output from the image reading unit 30 and may be data received from an external device such as a personal computer connected to the image forming apparatus 1 or another image forming apparatus.

  The paper storage unit 20 is disposed in the lower part of the apparatus main body, and a plurality of paper storage units 20 are provided according to the size and type of the paper S. The sheet S is fed by the sheet feeding unit 21 and sent to the transport unit 23, and is transported by the transport unit 23 to the secondary transfer unit 60 that is a transfer position. Further, a manual feed portion 22 is provided in the vicinity of the paper storage portion 20. From the manual feed section 22, paper of a size not stored in the paper storage section 20, tag paper having a tag, special paper such as an OHP sheet is sent to the transfer position.

  An image forming unit 40 and an intermediate transfer unit 50 are disposed between the image reading unit 30 and the paper storage unit 20.

  The image forming unit 40 includes four image forming units 40Y, 40M, 40C, and 40K in order to form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (Bk). . The image forming unit 40 forms an image for printing at a position corresponding to the sheet S on the intermediate transfer belt 51, and forms various patches described later at a position corresponding to between the sheets S and S.

  The first image forming unit 40Y forms a yellow toner image, and the second image forming unit 40M forms a magenta toner image. The third image forming unit 40C forms a cyan toner image, and the fourth image forming unit 40K forms a black toner image. Since these four image forming units 40Y, 40M, 40C, and 40K have the same configuration, only the first image forming unit 40Y will be described here.

The first image forming unit 40Y includes a drum-shaped photoconductor 41, a charging unit 42 disposed around the photoconductor 41, an exposure unit 43, a developing unit 44, and a photoconductor cleaning unit 45. Yes.
The photoreceptor 41 is rotated by a drive motor (not shown). The charging unit 42 applies a charge to the photoconductor 41 and uniformly charges the surface of the photoconductor 41. The exposure unit 43 performs an exposure operation on the surface of the photoconductor 41 based on image data read from the original G or image data transmitted from an external device, thereby forming an electrostatic latent image on the photoconductor 41. Form.
The developing unit 44 attaches yellow toner to the electrostatic latent image formed on the photoconductor 41. As a result, a yellow printing image is formed on the surface of the photoreceptor 41. The developing unit 44 of the second image forming unit 40M attaches magenta toner to the photoconductor 41, and the developing unit 44 of the third image forming unit 40C attaches cyan toner to the photoconductor 41. Then, the developing unit 44 of the fourth image forming unit 40K adheres black toner to the photoconductor 41.
The photoconductor cleaning unit 45 removes toner remaining on the surface of the photoconductor 41.
The printing image formed on the photoconductor 41 is transferred to an intermediate transfer belt 51 showing an example of an intermediate transfer member. The intermediate transfer belt 51 is formed in an endless shape and is stretched around a plurality of rollers. The intermediate transfer belt 51 is rotationally driven in a direction opposite to the rotation (movement) direction of the photoconductor 41 by a drive motor (not shown).

A primary transfer portion 52 is provided at a position on the intermediate transfer belt 51 that faces the photoreceptor 41 of each of the image forming units 40Y, 40M, 40C, and 40K. The primary transfer unit 52 transfers the printing image formed on the photoreceptor 41 to the intermediate transfer belt 51 by applying a polarity opposite to the toner to the intermediate transfer belt 51.
Then, when the intermediate transfer belt 51 is rotationally driven, printing images formed by the four image forming units 40Y, 40M, 40C, and 40K are sequentially transferred onto the surface of the intermediate transfer belt 51. As a result, yellow, magenta, cyan, and black toner images are overlapped on the intermediate transfer belt 51 to form a color printing image.
Further, an intermediate transfer belt cleaning unit 54 (image carrier cleaning member) is opposed to the intermediate transfer belt 51. The intermediate transfer belt cleaning unit 54 cleans the surface of the intermediate transfer belt 51 that has finished transferring the printing image onto the paper S. The intermediate transfer belt cleaning unit 54 may have a roller shape as shown in FIG. 1 or a blade shape.

  A secondary transfer unit 60 is disposed in the vicinity of the intermediate transfer belt 51 and downstream of the transport unit 23 in the sheet transport direction. The secondary transfer unit 60 brings the paper S sent by the transport unit 23 into contact with the intermediate transfer belt 51, and transfers the printing image formed on the outer peripheral surface of the intermediate transfer belt 51 onto the paper S. A secondary transfer belt cleaning unit 61 (secondary transfer unit cleaning member) faces the secondary transfer unit 60. Similar to the intermediate transfer belt cleaning unit 54, the secondary transfer belt cleaning unit 61 may have a roller shape as shown in FIG. 1 or a blade shape.

A fixing unit 80 is provided on the discharge side of the sheet S in the secondary transfer unit 60. The fixing unit 80 pressurizes and heats the paper S to fix the transferred printing image on the paper S. The fixing unit 80 includes, for example, a pair of fixing upper rollers 81 and a fixing lower roller 82 which are a pair of fixing members. The upper fixing roller 81 and the lower fixing roller 82 are arranged in pressure contact with each other, and a fixing nip portion is formed as a pressing portion between the upper fixing roller 81 and the lower fixing roller 82.
A heating unit is provided inside the fixing upper roller 81. The roller portion of the fixing upper roller 81 is warmed by the radiant heat from the heating portion. Then, the heat of the roller portion of the fixing upper roller 81 is transmitted to the paper S, whereby the printing image on the paper S is heat-fixed.
The sheet S is conveyed so that the surface (fixed target surface) onto which the printing image is transferred by the secondary transfer unit 60 faces the fixing upper roller 81, and passes through the fixing nip portion. Accordingly, the sheet S that passes through the fixing nip portion is pressed by the upper fixing roller 81 and the lower fixing roller 82 and heated by the heat of the roller portion of the upper fixing roller 81.

A switching gate 24 is disposed downstream of the fixing unit 80 in the sheet conveyance direction. The switching gate 24 switches the transport path of the paper S that has passed through the fixing unit 80. That is, the switching gate 24 moves the paper S straight when performing face-up paper discharge in single-sided image formation. As a result, the paper S is discharged by the pair of paper discharge rollers 25. The switching gate 24 guides the paper S downward when face-down paper discharge and double-sided image formation in single-sided image formation.
When face-down paper discharge is performed, the paper S is guided downward by the switching gate 24, and then the front and back sides are reversed by the paper reverse conveyance unit 26 and conveyed upward. As a result, the paper S whose front and back are reversed is discharged by the pair of paper discharge rollers 25.
When double-sided image formation is performed, the sheet S is guided downward by the switching gate 24, the front and back sides are reversed by the sheet reversing conveyance unit 26, and sent again to the transfer position by the refeed path 27.
A post-processing device that folds the paper S or performs a stapling process or the like on the paper S may be disposed on the downstream side of the pair of paper discharge rollers 25.

  FIG. 2 is a diagram illustrating a block configuration of the image forming apparatus 1. The image forming apparatus 1 includes a document transport unit 10, a paper storage unit 20, an image reading unit 30, an image forming unit 40, an intermediate transfer unit 50, a secondary transfer unit 60, a fixing unit 80, and a control unit. 110, an operation display unit 120, a communication control unit 130, and a storage unit 140.

  The control unit 110 includes a CPU (Central Processing Unit) 112, a ROM (Read Only Memory) 114, and a RAM (Random Access Memory) 116. The ROM 114 holds a program for operating the image forming apparatus 1. The RAM 116 is used as a temporary storage area for programs read from the ROM 114, input information from the display unit 154, and the like. The CPU 112 reads a program held in the ROM 114 and executes processing according to the program. For example, a program for executing the patch forming operation is read and the patch forming operation corresponding to the program is executed.

  The operation display unit 120 includes an operation unit 122 and a display unit 124. In this example, a touch panel in which the operation unit 122 and the display unit 124 are combined together is used. As the input detection device as the operation unit 122, for example, a capacitance method, a resistance film method, a surface acoustic wave (SAW) method, or the like is adopted. The operation unit 122 detects input information (input position) input by the user on the operation screen displayed on the display unit 124, generates a detection signal based on the detected input information, and supplies the detection signal to the control unit 110. The display unit 124 includes, for example, a liquid crystal display or an organic EL (ElectroLuminescence) display. The display unit 124 performs a predetermined display process according to an image signal based on the detection signal of the operation unit 122 supplied from the control unit 110.

  The communication control unit 130 includes a modem (MODEM: Modulator / DEModulator), a terminal adapter (Terminal Adapter), a LAN adapter, and the like, and performs communication control for communicating with an external device. The communication control unit 130 is used when receiving information related to job reservation contents from an external device, specifically, information regarding image data, the number of output jobs, and the like, and outputting the information to the control unit 110.

  The storage unit 140 includes, for example, an HDD (Harddisk drive) or a semiconductor memory. An execution condition for a patch forming operation to be described later is stored. For example, an HDD (Harddisk drive) or a semiconductor memory is used. The storage unit 140 includes, for example, image data read from the image reading unit 20, document / image data from a computer (not shown) connected to the image forming apparatus 10, operation screen data displayed on the operation display unit 120, patches Formation operation information, correction operation information, and the like are stored.

[Patch formation operation]
As described above, the image forming unit 40 forms a patch having a predetermined use at a position corresponding to the space between the sheets of the intermediate transfer belt 51. Here, the operation of forming a patch will be described by taking a toner consumption patch, an intermediate transfer belt cleaning patch, a secondary transfer belt cleaning patch, an inter-image division patch, and an inter-image dot diameter patch as examples. However, the patches used in the present invention are not limited to these, and may be, for example, a color resist correction patch for correcting the positional deviation of each color toner image.

(1) Toner Consumption Patch The toner consumption patch has a use to prevent the toner characteristics from fluctuating due to toner staying in the developing device for a long time and image stability being impaired. In other words, image stability can be maintained by consuming toner that has passed for a certain period in the developing unit as a toner consumption patch. For example, in this embodiment, when printing on A4 paper, if the printing rate of the printing image for 200 pages is 6% or less, the shortage is consumed as a toner consumption patch.

FIG. 3 shows an example of the shape of the toner consumption patch. A toner consumption patch is formed for each color over the entire width of the intermediate transfer belt 51. Here, I1 and I2 represent printing images, Y, M, C, and Bk represent yellow, magenta, cyan, and black portions of the patch, respectively, and arrows represent the conveyance direction of the intermediate transfer belt 51. The shape of the toner consumption patch is not particularly limited as long as the above-described toner consumption is consumed. For example, in addition to the shape shown in FIG. 3, a belt-like shape parallel to the conveyance direction of the intermediate transfer belt 51 may be used for each color. The amount of toner consumed as a toner consumption patch is determined by the printing rate of the printing image.
The toner consumption patch may be conveyed to the secondary transfer belt cleaning unit 61 or may be conveyed to the intermediate transfer belt cleaning unit 54.

(2) Intermediate Transfer Belt Cleaning Patch The intermediate transfer belt cleaning patch has a purpose of maintaining the lubricity of the intermediate transfer belt cleaning unit 54. In particular, when a blade-shaped member is used as the intermediate transfer belt cleaning unit 54, an intermediate transfer belt cleaning patch is formed for the purpose of preventing blade curl and edge damage. For example, in this embodiment, when printing A4 paper, an intermediate transfer belt cleaning patch is formed every time 100 pages are printed.

FIG. 4 shows an example of the shape of the intermediate transfer belt cleaning patch. As the intermediate transfer belt cleaning patch, a belt-like patch parallel to the entire width of the intermediate transfer belt 51 is formed for each color. By forming the intermediate transfer belt cleaning patch in this manner, the lubricity of the intermediate transfer belt cleaning unit 54 can be maintained.
The shape of the intermediate transfer belt cleaning patch is not limited to this embodiment as long as a certain amount or more of toner is disposed over the entire width of the intermediate transfer belt 51. For example, in addition to the shape shown in FIG. 4, the intermediate transfer belt 51 may have a shape in which the width direction of the intermediate transfer belt 51 is divided into a plurality of sections and toners of a plurality of colors are arranged. Further, in this embodiment, a belt-like patch is formed for each color, but the intermediate transfer belt cleaning patch may be composed of only one color toner.
Since the intermediate transfer belt cleaning patch is intended to maintain the lubricity of the intermediate transfer belt cleaning unit 54, the control unit 110 does not transfer the intermediate transfer belt cleaning patch to the secondary transfer unit 60 and performs intermediate transfer belt cleaning. The secondary transfer unit 60 is controlled so as to be conveyed to the unit 54.

(3) Secondary Transfer Belt Cleaning Patch The secondary transfer belt cleaning patch has a purpose of maintaining the lubricity of the secondary transfer belt cleaning unit 61. Further, when a blade-shaped member is used as the secondary transfer belt cleaning unit 61, a secondary transfer belt cleaning patch is formed for the purpose of preventing blade curl and edge damage. For example, in this embodiment, a secondary transfer belt cleaning patch is formed every time one page is printed when A4 paper is printed.

FIG. 5 shows an example of the shape of the secondary transfer belt cleaning patch. As the secondary transfer belt cleaning patch, as in the intermediate transfer belt cleaning patch, a belt-like patch parallel to the entire width of the secondary transfer portion 60 is formed for each color. By forming the secondary transfer belt cleaning patch in this way, the lubricity of the secondary transfer belt cleaning unit 61 can be maintained.
The shape of the secondary transfer belt cleaning patch is not limited to this embodiment as long as a certain amount or more of toner is disposed over the entire width of the secondary transfer portion 60 as in the case of the intermediate transfer belt cleaning patch. It will never be done. For example, in addition to the shape shown in FIG. 5, the intermediate transfer belt 51 may have a shape in which the width direction of the intermediate transfer belt 51 is divided into a plurality of sections and toners of a plurality of colors are arranged. In this embodiment, a belt-like patch is formed for each color. However, the secondary transfer belt cleaning patch may be configured by only one color toner.
Further, since the secondary transfer belt cleaning patch is intended to maintain the lubricity of the secondary transfer belt cleaning unit 61, the control unit 110 does not leave the secondary transfer belt cleaning patch on the intermediate transfer belt 51. The secondary transfer unit 60 is controlled so as to be conveyed to the next transfer unit 60.

(4) Inter-image division patch The inter-image division patch has an application for preventing deterioration in image quality due to wear characteristics in the axial direction of the photoreceptor and the width direction of the intermediate transfer belt 51. That is, when there is a large difference in the printing rate in the axial direction on the photoconductor, the wear between the photoconductor and the intermediate transfer belt 51 and the wear between the photoconductor and the photoconductor cleaning unit 45 in the axial direction. Since a difference may occur and the quality of image formation may be deteriorated, an image division patch is formed so as to fill in the difference in the printing rate in the axial direction of the photoreceptor (the width direction of the intermediate transfer belt 51). Quality degradation can be prevented. For example, the axial direction of the photosensitive member is divided into eight sections, the printing rate for each section is calculated for each page, and the inter-image division patch in the conveyance direction of the intermediate transfer belt 51 is calculated according to the difference in the printing rate. Determine the length of the.

FIG. 6 is an example of the shape of the inter-image division patch. For black, the printing rate of the printing image is high at the central portion in the width direction of the intermediate transfer belt 51 and low at both ends, so the length in the conveyance direction of the inter-image divided patch is short at the central portion, and at both ends. It has a long shape. On the other hand, for yellow, the printing rate of the printing image is high at the bottom of the paper (lower side in FIG. 6) and low at the upper part of the paper (upper side in FIG. 6). It is short at the bottom and long at the top of the page. The inter-image division patch is a length in the conveyance direction of the intermediate transfer belt 51 formed in each section in the width direction on the intermediate transfer belt 51 in order to fill the difference in the printing rate in the axial direction on the photosensitive member. It is only necessary to be arranged so that there is a difference between them, and the present invention is not limited to this embodiment. For example, in addition to the shape shown in FIG. 6, a belt-like patch added in parallel to the entire width of the intermediate transfer belt 51 may be formed as an inter-image division patch.
Further, the inter-image division patch may be conveyed to the secondary transfer unit 60 or may be conveyed to the intermediate transfer belt cleaning unit 54.

(5) Inter-image dot diameter patch The inter-image dot diameter patch has a purpose of maintaining the density and line width of an image. Specifically, the image density and the line width of the image instructed from the image forming unit 40 do not follow the instructions of the control unit 110 because the characteristics of the materials such as the photoreceptor and toner carrier fluctuate during the printing operation. There is a case. Therefore, the image forming unit 40 is controlled by forming an inter-image dot diameter patch, detecting the density and shape of the inter-image dot diameter patch by a detection sensor (not shown) on the intermediate transfer belt 51, and performing feedback correction. An image having an image density and a line width as instructed by the unit 110 can be formed. For example, in this embodiment, an inter-image dot diameter patch is formed every 30 pages when A4 paper is printed.

FIG. 7 is an example of the shape of the dot diameter patch between images. In this embodiment, a dot matrix of 5 rows × 5 columns is formed for each color. The position, shape, number, etc. of the dot diameter patches between images are determined by the correction control method.
Further, the inter-image dot diameter patch may be conveyed to the secondary transfer unit 60 or may be conveyed to the intermediate transfer belt cleaning unit 54.

  As described above, the image forming unit 40 forms various patches having a predetermined application at positions corresponding to the space between the sheets of the intermediate transfer belt 51. Here, by forming a patch having a plurality of patch applications (third patch), it is possible to reduce the amount of toner consumption compared to the case where a plurality of patches are formed separately. Details of the control for forming a patch having a plurality of patch applications (third patch) will be described below.

[Control to form third patch]
Hereinafter, the control for forming the third patch will be described with reference to FIGS.

  First, the outline of the control for forming the third patch will be described with reference to FIGS. 8 and 9. FIG. 8 is a flowchart illustrating an example of a control method in the control for forming the third patch. FIG. 9 is a diagram showing a time-series outline in the control for forming the third patch. Note that timing P in FIG. 9 represents the timing at which the image forming unit 40 performs a printing operation on a sheet.

  When the printing operation starts, the control unit 110 starts control for forming the third patch (step S801). Thereafter, the control unit 110 controls the image forming unit 40 so as to continue the printing operation until the timing for forming the first patch (timing T1 in FIG. 9) is reached (step S802; No). If it is time to form the first patch, the process proceeds to step S803 (step S802; No). Here, the first patch may be any type of patch.

  When it is time to form the first patch, the control unit 110 refers to the timing (timing T2 in FIG. 9) to form the second patch (step S803). Here, like the first patch, the second patch may be any type of patch. That is, the control unit 110 refers to the information on the timing at which the various patches are scheduled to be formed.

  The control unit 110 determines whether or not to form the third patch based on the information about the timing of forming the first patch and the timing of forming the second patch (step S804). Details of this step will be described later with reference to FIGS.

  If it is determined in step S804 that a third patch is to be formed, the control unit 110 determines a third patch formation condition (step S805). Details of this step will be described later with reference to FIGS.

  After determining the formation condition of the third patch, the control unit 110 determines the timing for forming the third patch (step S806). Details of this step will be described later with reference to FIG.

  Thereafter, the control unit 110 controls the image forming unit 40 to execute an operation of forming the third patch having the formation condition determined in step S805 at the timing determined in step S806 (step S807). The control for forming the third patch is terminated.

  In this embodiment, control is performed so that the timing of forming the first patch in step S802 is changed to refer to the timing of transition to step S803 to form the second patch. The timing for referring to the timing for forming the second patch is not limited to this. For example, the timing for forming the second patch from the timing before the timing for forming the first patch may be controlled.

<Third patch formation availability control>
The third patch formation availability determination control (step S804 in FIG. 8), which is the third patch formation control subroutine, will be described below with reference to FIGS. FIG. 10 is a flowchart illustrating an example of a detailed control method of the third patch formation availability determination control.

  When the third patch formation availability determination control is started, the control unit 110 forms the first patch detected in step S802 in FIG. 8 (T1) and the second patch referenced in step S803. An interval (interval D in FIG. 9) from the timing (T2) is calculated (step S1001).

  The controller 110 determines whether the interval D calculated in step S1001 is shorter than the reference interval (step S1002). Here, the reference interval refers to the timing of forming the first patch and the second patch that can form the third patch without causing a problem in place of the first patch and the second patch. It is the maximum value of the interval from the formation timing. In this embodiment, the reference interval is set to a certain value. That is, when the interval D is shorter than the reference interval (step S1002; Yes), the control unit 110 determines that the third patch can be formed (step S1003), and performs the third patch formation availability determination control. finish. On the other hand, when the interval D is longer than the reference interval (step S1002; No), the control unit 110 determines that the third patch cannot be formed (step S1004) and forms only the first patch. In this way, the image forming unit 40 is controlled (step S1005), and the third patch formation control is terminated.

<Third patch formation condition determination control>
The third patch formation condition determination control (step S805 in FIG. 8), which is a subroutine for the third patch formation control, will be described below with reference to FIG. In the third patch formation condition determination control, the control unit 110 determines the third patch formation condition so that the third patch has both uses of the first patch and the second patch. In this embodiment, a case where the first patch is a toner consumption patch and the second patch is an inter-image division patch will be described as an example. In this case, the third patch uses a toner consumption patch for maintaining image stability and prevents image quality degradation caused by wear characteristics in the axial direction of the photoreceptor and the width direction of the intermediate transfer belt 51. It is necessary to combine the use of split patches.

  FIG. 11 is a flowchart illustrating an example of a detailed control method of the third patch formation condition determination control (step S905 in FIG. 9).

  When the third patch formation condition determination control is started, the control unit 110 refers to the first patch formation condition (step S1101). The patch formation conditions are conditions when the image forming unit 40 forms a patch, such as the patch shape and toner consumption. In this embodiment, since the first patch is a toner consumption patch, the toner consumption for each color may be referred to as the formation condition. Specifically, the toner consumption amount for each color of the toner consumption patch shown in FIG. 3 is referred to. For example, it is assumed that the toner consumption for each color is yellow: 20, magenta: 120, cyan: 70, and black: 40, respectively.

  Thereafter, the control unit 110 refers to the formation conditions of the second patch (step S1102). In this embodiment, since the second patch is an inter-image division patch, as the formation conditions, the shape of the patch for each color, the toner consumption amount for each color, and the like are referred to. Specifically, the patch shape for each color of the inter-image division patch shown in FIG. 4, the toner consumption amount for each color, and the like are referred to. For example, it is assumed that the toner consumption for each color is yellow: 70, magenta: 60, cyan: 70, and black: 80, respectively.

  The control unit 110 determines the third patch formation condition for each color based on the first patch formation condition and the second patch formation condition (steps S1103 to S1106). Details of this control method will be described below.

  The control unit 110 determines the formation condition of the yellow portion of the third patch (step S1103). As for the yellow toner, it is necessary to consume 20 as the toner consumption patch, whereas 70 as the inter-image division patch. That is, the amount of toner consumed when forming the toner consumption patch is smaller than the amount of toner consumed when forming the inter-image division patch. Therefore, if the shape of the yellow portion of the inter-image division patch shown in FIG. 4 is directly used as the shape of the yellow portion of the third patch, a necessary amount of toner can be consumed as a toner consumption patch. And the second patch (inter-image division patch). Therefore, it is determined that the shape of the yellow portion of the inter-image division patch is directly used as the shape of the yellow portion of the third patch.

  Next, the control unit 110 determines the formation condition of the magenta part of the third patch (step S1104). As for the magenta toner, it is necessary to consume 120 as the toner consumption patch, whereas 60 as the inter-image division patch. For this reason, if only the shape of the magenta portion of the inter-image division patch shown in FIG. 4 is the shape of the magenta portion of the third patch, the amount of consumed toner is insufficient, so the first patch (toner consumption Patch) and second patch (inter-image division patch) cannot be used together. Therefore, it is determined that the shape of the magenta portion of the third patch is obtained by adding 60 which is the difference amount from the amount of toner to be consumed to the shape of the magenta portion of the inter-image division patch. By determining the shape of the magenta portion of the inter-image division patch in this way, the first patch (toner consumption patch) and the second patch (inter-image division patch) can be used together. The shape of the portion to be added is not particularly limited, but it is preferably a strip shape parallel to the width direction of the intermediate transfer belt 51.

  Next, the control unit 110 determines the formation condition of the cyan portion of the third patch (step S1105). The cyan toner needs to be consumed as 70 as a toner consumption patch, whereas it is consumed as 70 between image division patches. Therefore, as in the case of yellow, if the shape of the cyan portion of the inter-image division patch shown in FIG. 4 is changed to the shape of the cyan portion of the third patch, a necessary amount of toner is consumed as a toner consumption patch. be able to. That is, the first patch (toner consumption patch) and the second patch (inter-image division patch) can be used together. Therefore, it is determined that the shape of the cyan portion of the inter-image division patch is directly used as the shape of the cyan portion of the third patch.

  Next, the control unit 110 determines the formation condition of the black portion of the third patch (step S1106). For black toner, it is necessary to consume 40 as a toner consumption patch, whereas 80 consumption as a patch between images. For this reason, as in the case of yellow, if the shape of the black portion of the inter-image division patch shown in FIG. 4 is the shape of the black portion of the third patch, a necessary amount of toner is consumed as a toner consumption patch. be able to. That is, the first patch (toner consumption patch) and the second patch (inter-image division patch) can be used together. Therefore, it is determined that the shape of the black portion of the inter-image division patch is directly used as the shape of the black portion of the third patch.

  By determining the formation conditions of the third patch for each color as described above, the formation of the third patch having both uses of the toner consumption patch (first patch) and the inter-image division patch (second patch) is formed. Conditions can be determined. FIG. 12 shows the shape of the third patch determined in this embodiment. In FIG. 12, I1 and I2 are images for printing, Y, M, C, and Bk are the yellow, magenta, cyan, and black portions of the third patch, respectively, and the arrows indicate the conveyance direction of the intermediate transfer belt 51. It represents.

<Third patch formation timing determination control>
The third patch formation timing determination control (step S806 in FIG. 8), which is a third patch formation control subroutine, will be described below.

  FIG. 13 is a time-series diagram illustrating the third patch formation timing determination control. Similarly to FIG. 10, the timing P represents the timing at which the image forming unit 40 is performing the printing operation on the paper, and the control unit 110 determines the timing (T1) for forming the first patch and the second patch. When the interval D with the formation timing (T2) is shorter than the reference interval, the image forming unit 40 is controlled to form the third patch.

  At this time, the control unit 110 forms the first patch formation timing (T3), the second patch formation timing (T8), the first patch formation timing, and the second patch formation. It is determined that the third patch is formed at any timing (T4 to T7) between the timings.

  According to the image forming apparatus of the present invention, by performing the control to form the third patch between the printing images on the intermediate transfer belt 51 during the image forming operation by the control method as described above, It is possible to reduce the amount of toner consumed when a plurality of patches are formed while suppressing a decrease in productivity in the image forming apparatus.

  In this embodiment, the timing of forming the first patch, the timing of forming the second patch, the timing between forming the first patch and the timing of forming the second patch, Although the third patch is formed at any one of the timings, the timing for forming the third patch is not limited to this. For example, the third patch may be formed at a timing (T9) before the timing of forming the first patch or at a timing (T10) after the timing of forming the second patch.

  In this embodiment, as an example, the case where the first patch is a toner consumption patch and the second patch is an inter-image division patch has been described as an example, but the combination of the first patch and the second patch is described. Is not limited to this. As long as it is possible to combine the use of the first patch and the second patch, a combination of other types of patches may be used, and the first patch and the second patch may be the same type of patch. It doesn't matter.

  Note that if there are multiple patches whose interval from the first patch is shorter than the reference interval, executing the third patch formation control multiple times in succession will result in a patch that has three or more patch applications. Can be formed. As an example, let us consider a case where a patch having the uses of three patches of a toner consumption patch, an inter-image division patch, and an inter-image dot diameter patch is formed.

First, the first patch (A) is used as the toner consumption patch and the second patch (B) is used as the inter-image division patch, and the formation control of the third patch (A) having these uses is executed. Thereafter, without actually forming the third patch (A) on the intermediate transfer belt 51, the third patch (A) is used as the first patch (B), and the inter-image dot diameter patch is used as the second patch (B). ), The formation control of the third patch (B) having these uses is executed, and the third patch (B) determined here is formed on the intermediate transfer belt 51, whereby the toner consumption patch, A patch having both uses of the three patches of the inter-image division patch and the inter-image dot diameter patch can be formed.
In this way, by forming a patch having both uses of three or more patches, toner consumption can be more reliably reduced.

(Example 2)
In the first embodiment, the reference interval (step S902 in FIG. 9), which is a criterion for determining whether or not to form the third patch, is set to a certain value. In the example, the reference interval is set to a value calculated according to the frequency of forming the first patch and the second patch.

For example, it is necessary to perform high-accuracy correction such as an inter-image dot diameter patch, and for a patch that is frequently formed, it is desirable to form the third patch at a timing as close as possible to the initial formation timing. There is. Therefore, when either the first patch or the second patch is an inter-image dot diameter patch (a patch that is frequently formed), the toner interval can be reduced by setting the reference interval short. It can suppress that correction accuracy falls. On the other hand, for patches with low formation frequency, such as toner consumption patches, the third patch is formed at a timing away from the initial formation timing, compared to patches with high formation frequency such as inter-image dot diameter patches. However, image stability may be maintained to some extent. Therefore, if either the first patch or the second patch is a toner consumption patch (a patch that is formed less frequently), the image can be stabilized while reducing the toner consumption by setting a long reference interval. It can suppress that property falls. In calculating the reference interval, both the frequency of forming the first patch and the frequency of forming the second patch are considered.
As described above, by setting the reference interval according to the frequency of forming the first patch and the second patch, it is possible to prevent problems with the use of the first patch and the second patch. However, the toner consumption can be reduced.

(Example 3)
In this embodiment, the reference interval is set based on information input from the operation unit by the user.
For example, users who prioritize the reduction of toner consumption over patch applications such as correction accuracy and image stability can often form the third patch by setting a longer reference interval. Compared to the case, the toner consumption can be reduced more. On the other hand, for users who prioritize patch usage over toner consumption reduction, the reference interval is set shorter, so that it is closer to the initial formation timing than the standard setting. Since the third patch is formed, the third patch can more reliably serve the purpose of the first patch and the second patch.
By setting in this way, it is possible to perform the third patch formation control reflecting the usage status of the user, and more appropriately reduce the toner consumption.

Example 4
In the above embodiment, when determining whether or not to form the third patch, there is no mention about the case where the destinations of the first patch and the second patch are different, for example, When the first patch is an intermediate transfer belt cleaning patch that is conveyed to the intermediate transfer belt 51 and the second patch is a secondary transfer belt patch that is conveyed to the secondary transfer unit 60, the conveyance destination Therefore, it is not possible to form a third patch having both uses of the first patch and the second patch. In this embodiment, control is performed in consideration of this point. Details of the control in this embodiment will be described below.

  The third patch formation availability determination control (step S804 in FIG. 8) in the image forming apparatus according to the present embodiment will be described below. FIG. 14 is a flowchart illustrating an example of a detailed control method of the third patch formation availability determination control.

  Similar to the control in the flowchart of FIG. 9, when the third patch formation possibility determination control is started, the control unit 110 sets the interval D between the timing of forming the first patch and the timing of forming the second patch. When it is calculated (step S1401) and the calculated interval D is longer than the reference interval (step S1402; No), it is determined that the third patch cannot be formed (step S1408), and only the first patch is formed. In this way, the image forming unit 40 is controlled (step 1409), and the third patch formation control is terminated. On the other hand, when the interval D is shorter than the reference interval (step S1402; Yes), the process proceeds to step S1403.

  The control unit 110 determines whether one of the first patch and the second patch is a patch for which the transport destination is designated (step S1403). For example, the intermediate transfer belt cleaning patch is a patch designated to be conveyed to the intermediate transfer belt 51, and the secondary transfer belt patch is a patch designated to be conveyed to the secondary transfer unit 60. .

  Here, when either one of the patches is a patch for which the transport destination is designated (step S1403; Yes), the control unit 110 transports the other patch to the designated transport destination. It is determined whether the patch can be applied (S1404). If the other patch is not a patch that can be transported to the designated transport destination (step S1404; No), it is determined that the third patch cannot be formed (step S1406). For example, the case where the first patch is an intermediate transfer belt cleaning patch and the second patch is a secondary transfer belt patch corresponds to this case. On the other hand, if the other patch is a patch that can be transported to the designated transport destination (step S1404; Yes), it is determined that the third patch can be formed (step S1405). ), The third patch formation feasibility determination control is terminated.

  If both patches are not patches for which the transport destination is specified in step S1403 (step S1403; No), the control unit 110 determines that a third patch can be formed. (Step S1405), the third patch formation availability determination control is terminated.

  As described above, in this embodiment, it is determined that it is impossible to form the third patch when the destinations of the first patch and the second patch are different. By controlling in this way, even if one of the first patch and the second patch is a patch for which the transport destination is specified, if both are specified the same transport destination, When one of the patches is designated as the transport destination and the other patch is not designated as the transport destination, the third patch can be formed. Therefore, the number of combinations that can form the third patch can be increased, and the toner consumption can be more reliably reduced.

For example, in the case of forming a third patch having the uses of a toner consumption patch, an intermediate transfer belt cleaning patch, and a secondary transfer belt cleaning patch, a part conveyed to the intermediate transfer belt cleaning unit 54, Since the transport destination is different from the portion transported to the next transfer belt cleaning unit 61, it is necessary to switch the voltage of the secondary transfer unit 60 when passing through the secondary transfer unit 60. Therefore, a patch cannot be formed on the portion of the intermediate transfer belt 51 that passes through the secondary transfer portion 60 while switching the voltage. Therefore, an interval corresponding to the voltage switching time of the secondary transfer unit 60 is provided between the portion transported to the intermediate transfer belt cleaning unit 54 and the portion transported to the secondary transfer belt cleaning unit 61 to provide a third time. Form a patch.
By controlling in this way, the third patch can be formed even if it includes a patch conveyed to a different conveyance destination, and the toner consumption can be more reliably reduced.

(Example 5)
In the above embodiment, in the control for forming the third patch, the intermediate transfer belt 51 is transported by the third patch whose formation condition is determined by the third patch formation condition determination control (step S805 in FIG. 8). Although the case where the length in the direction is longer than the length between images for printing in a normal printing operation is not considered, for example, when printing with a low printing rate continues, it is consumed as a toner consumption patch. The amount of toner that is required increases, and the length of the third patch in the conveyance direction may be longer than the length between normal printing images. Further, as described in the fourth embodiment, when the third patch has a portion conveyed to the intermediate transfer belt cleaning unit 54 and a portion conveyed to the secondary transfer belt cleaning unit 61, the secondary patch Since it is necessary to switch the voltage of the transfer unit 60, a third patch is formed with a gap between the portion conveyed to the intermediate transfer belt cleaning unit 54 and the portion conveyed to the secondary transfer belt cleaning unit 61. To do. In this case as well, the length of the third patch in the conveyance direction may be longer than the length between normal printing images. In such a case, when the third patch is formed between the printing images, the length between the printing image immediately before the third patch is formed and the printing image immediately after the third patch is formed. Will be longer than usual. For this reason, there is a problem that the formation of the next printing image is delayed and the productivity of the printing operation is lowered.

  In this embodiment, when the length of the third patch in the conveyance direction is longer than the length between the normal printing images, the third patch is not formed, and the third patch is not formed between the plurality of printing images. One patch and a second patch are formed, respectively.

FIG. 15 is a flowchart illustrating a third patch formation control method in the image forming apparatus according to the present embodiment. In this embodiment, when the length of the third patch in the conveyance direction is longer than the length between the normal printing images (S1501; No), the control unit 110 forms the third patch. First (S1504), the image forming unit 40 is controlled so as to form the first patch and the second patch between the plurality of printing images (S1505). On the other hand, when the third patch can be formed between the print images on the intermediate transfer belt 51 (S1501; Yes), the timing for forming the third patch is determined (S1502), and the third patch is formed. This is the same as steps S806 and S807 in FIG. 8 of the first embodiment in that the third patch formation control is terminated (S1503).
By controlling in this way, it is possible to further suppress a decrease in productivity of the printing operation while reducing the toner consumption.

(Example 6)
In this embodiment, when the length of the third patch in the transport direction is longer than the length between the normal print images, the third patch is used for the normal print in the transport direction. The image forming unit 40 is controlled so as to be divided into a plurality of patches shorter than the length between images and to form a plurality of patches between the plurality of printing images.

  FIG. 16 is a diagram illustrating an example of a plurality of divided patches. Here, I1, I2, and I3 are images for printing, Y, M, C, and Bk are the yellow, magenta, cyan, and black portions of the third patch, respectively, and the arrows are the conveyance directions of the intermediate transfer belt 51. Represents. Of the third patch, the black, cyan, and magenta portions can be formed between the normal printing images, and thus are formed between the first printing images. On the other hand, the remaining yellow portion of the third patch is formed between the second printing images.

  FIG. 17 is a flowchart illustrating a third patch formation control method in the image forming apparatus according to the present embodiment.

If the third patch can be formed between the print images on the intermediate transfer belt 51 (S1701; Yes), the timing for forming the third patch is determined (S1702), and the third patch forming operation is executed. In step S1703, the third patch formation control is terminated, as in FIG. 15 in the fifth embodiment. On the other hand, in this embodiment, when the length of the third patch in the conveyance direction is longer than the length between the normal printing images (S1701; No), the control unit 110 removes the third patch. The image forming unit 40 is controlled so as to be divided into a plurality of patches whose length in the transport direction is shorter than the length between normal printing images (S1704), and to form a plurality of patches between the plurality of printing images. (S1705).
By forming the third patch in this way, it is possible to more reliably reduce the toner consumption while preventing a decrease in productivity.

The control in the fifth and sixth embodiments may be selectively executed when the length of the third patch in the conveyance direction is longer than the length between the normal printing images. That is, when the length of the third patch in the conveyance direction is longer than the length between the normal printing images, the control unit 110 does not form the third patch, and does not form the third patch. In the first control for controlling the image forming unit 40 to form the first patch and the second patch respectively, and the length in the conveyance direction of the third patch is the length between the normal printing images. The second control for controlling the image forming unit 40 so as to divide the patch into a plurality of shorter patches and form the plurality of patches between the plurality of printing images may be selectively executed. Here, the determination criterion for selective execution may be set based on information input by the user from the operation unit, or set according to the types of the first patch and the second patch. It may be done. Further, it may be set according to the interval between the timing of forming the first patch and the timing of forming the second patch.
By setting in this way, it is possible to perform the third patch formation control reflecting the usage status of the user, and more appropriately reduce the toner consumption.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 40 Image forming part 50 Intermediate transfer part 54 Intermediate transfer belt cleaning part 60 Secondary transfer part 61 Secondary transfer belt cleaning part 110 Control part 130 Communication control part 140 Storage part P Image forming part 40 performs printing operation on paper T1 timing for forming the first patch T2 timing for forming the second patch D interval between timing for forming the first patch and timing for forming the second patch

Claims (11)

In an image forming apparatus comprising: an image forming unit that forms an image for printing on an image carrier; and a control unit that controls the image forming unit.
The image forming unit forms a first patch and a second patch having a predetermined use between printing images on the image carrier at a predetermined timing,
When the timing for forming the first patch and the timing for forming the second patch are in a predetermined relationship, the first patch and the second patch are replaced with the first patch. An image forming apparatus, wherein the image forming unit is controlled so as to form a third patch having both uses of the patch and the second patch. The controller is configured to form the third patch when the interval between the timing of forming the first patch and the timing of forming the second patch is shorter than a predetermined reference interval. The image forming apparatus according to claim 1, wherein the forming unit is controlled. The controller, when forming the third patch, the timing of forming the first patch, the timing of forming the second patch, the timing of forming the first patch, and the second 3. The image formation according to claim 1, wherein the image forming unit is controlled to form the third patch at any one of timings between the timings of forming the patches. apparatus. The image forming apparatus according to claim 2, wherein the reference interval is calculated according to a frequency of forming the first patch and the second patch. It further has an operation unit for the user to input information,
The image forming apparatus according to claim 2, wherein the reference interval is set based on information input by a user from the operation unit. An image carrier cleaning member that is pressed against the image carrier and removes toner adhering to the image carrier;
The control unit is a patch in which either the first patch or the second patch is transported to the image carrier cleaning member on the image carrier, and the other patch is The image forming unit is controlled to form the third patch when the patch can be conveyed to the image carrier cleaning member. The image forming apparatus according to one. A secondary transfer unit for transferring the image for printing on the image carrier to paper;
A secondary transfer portion cleaning member that is in pressure contact with the secondary transfer portion and removes toner adhering to the secondary transfer portion;
The control unit is a patch in which one of the first patch and the second patch is conveyed to the secondary transfer unit cleaning member of the secondary transfer unit, and the other patch The image forming unit is controlled to form the third patch when the patch is a patch that can be conveyed to the secondary transfer unit cleaning member. The image forming apparatus according to any one of the above. When the length of the third patch in the conveyance direction of the image carrier is longer than the length between the normal printing images, the control unit does not form the third patch and prints a plurality of prints. The image forming apparatus according to claim 1, wherein the image forming unit is controlled so as to form the first patch and the second patch between images for use. When the length of the third patch in the conveying direction of the image carrier is longer than the length between the normal printing images, the control unit moves the third patch to the length in the conveying direction. The image forming unit is controlled so that the plurality of patches are divided into a plurality of patches shorter than the length between normal printing images, and the plurality of patches are formed between the plurality of printing images. The image forming apparatus according to any one of 7 to 7. The controller is
When the length of the third patch in the conveyance direction of the image carrier is longer than the length between the normal printing images, the third patch is not formed, and the plurality of printing images A first control for controlling the image forming unit to form the first patch and the second patch, respectively;
The third patch is divided into a plurality of patches whose length in the transport direction is shorter than a length between normal printing images, and the plurality of patches are formed between the plurality of printing images. The image forming apparatus according to claim 1, wherein second control for controlling the forming unit is selectively executed. The controller is
Either one of the first patch or the second patch is a patch intended to consume toner, and the amount of toner consumed when forming the one patch is different from the other patch. The image forming unit is controlled so that the formation condition of the other patch is formed as the formation condition of the third patch when the amount of toner consumed in forming is smaller than the amount of toner consumed. 10. The image forming apparatus according to any one of 10.

Images