JP2020197684A - Image forming apparatus and program - Google Patents

Abstract

To provide an image forming apparatus that can certainly remove an aggregate from a cleaning member, and a technology related to the same.SOLUTION: An image forming apparatus comprises: an image carrier (for example, transfer belt 21); and a cleaning member (for example, cleaning blade 2) that scrapes off a residual toner on the transfer belt 21 in association with the relative movement of the transfer belt 21. The image forming apparatus executes a maintenance operation to remove an aggregate generated between the transfer belt 21 and the cleaning blade 2. The maintenance operation includes a patch forming operation to form toner images (patch images P50) for removing the aggregate on the transfer belt 21, and a moving operation to causing the transfer belt 21 to advance toward the cleaning blade 2 to cause the patch images P50 on the transfer belt 21 to collide with the cleaning blade 2. An edge E1 on the downstream side in the advance direction D1 of the patch image P50 extends in a direction C1 not perpendicular to the advance direction D1.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus and related techniques.

In an image forming apparatus (specifically, an electrophotographic image forming apparatus), a toner image formed on an image carrier (for example, a transfer belt) is transferred to a paper (transfer material) to obtain an image on the paper. Is formed.

After such an image forming operation (transfer operation of the toner image to the paper), a part of the toner remains on the image carrier. Toner remaining on the image carrier (also called residual toner) hinders the formation of a new image, and is therefore scraped off by a cleaning member (cleaning blade, etc.) arranged in contact with the surface of the image carrier. It is collected and collected in a toner collection unit or the like.

By the way, not only residual toner but also various foreign substances are present on the image carrier after the image forming operation on the paper is performed. Examples of the various foreign substances include paper powder containing a filler added to the paper, an external additive externally added to the toner, and / or a lubricant (lubricant) applied to the photoconductor or the like.

When these foreign substances are present on the image carrier, the foreign substances pass through the contact portion between the image carrier and the cleaning member (the linear contact portion where the image carrier and the cleaning member are in mutual contact). At this time, problems such as damage to the surface of the image carrier occur. When the surface of the image carrier is damaged, the rubber layer under the coat layer covering the surface of the image carrier is exposed, and the cleaning member may be deformed due to an increase in the coefficient of friction with the cleaning member. .. As a result, the service life of the cleaning member may be shortened.

There are techniques for preventing the occurrence of such problems.

For example, in Patent Document 1, a square patch image (patch image with toner) is formed on an image carrier, and the patch image is used as a cleaning member in a state where the patch image and paper dust (foreign matter) are mixed. Techniques have been demonstrated for removing paper dust on an image carrier by impacting.

JP-A-11-258919 Japanese Unexamined Patent Publication No. 2017-21138

However, even when the technique described in Patent Document 1 is used, when the image forming operation on the paper is repeated, the cleaning member (for example, the cleaning blade 2) and the image carrier (for example, the intermediate transfer belt 21) are brought into contact with each other. In the gaps between them, various foreign substances may gradually accumulate (deposit) to generate (generate) aggregates M10 (see FIG. 20).

In this case, when the patch image in the technique described in Patent Document 1 is formed on the image carrier (intermediate transfer belt 21), the agglomerate M10 is not removed and cleaning is poor (as described below). There is a risk of streak-like image noise, etc.).

Specifically, in the technique described in Patent Document 1, the edge on the downstream side in the traveling direction of the quadrangular patch image extends in the direction perpendicular to the traveling direction. Therefore, as shown in FIG. 21, when the agglomerates M10 are present in the gap between the cleaning blade 2 and the intermediate transfer belt 21, the edge (edge extending in the direction perpendicular to the traveling direction D1) E90. Collides with the agglomerate M10, the agglomerate M10 is pushed to the downstream side of the traveling direction D1 by the powder pressure of the toner traveling to the downstream side of the traveling direction D1.

As a result, the agglomerate M10 may be caught between the cleaning blade 2 and the intermediate transfer belt 21 (see FIG. 22), and a gap may be formed between the cleaning blade 2 and the intermediate transfer belt 21. Specifically, of the contact portions between the cleaning blade 2 and the intermediate transfer belt 21, gaps may occur in both side portions of the agglomerate M10 (both side portions in the direction D2 perpendicular to the moving direction D1 of the intermediate transfer belt 21) (FIG. 23). FIG. 23 is a view of the state in which the agglomerates M10 are caught between the cleaning blade 2 and the intermediate transfer belt 21 as viewed from the downstream side in the moving direction D1 of the intermediate transfer belt 21.

When a gap is formed between the cleaning blade 2 and the intermediate transfer belt 21, for example, when the residual toner N10 reaches the position where the agglomerate M10 is generated on the cleaning blade 2, as shown in FIG. 24, the agglomerates A part of the residual toner N10 (toner N5) slips through the gaps on both sides of the M10. As a result, the toner N5 that has slipped through may be transferred onto the image in the next image forming operation, and streak-like image noise (cleaning failure) may occur.

Therefore, it is an object of the present invention to provide an image forming apparatus capable of more reliably removing agglomerates from a cleaning member, and a technique related thereto.

In order to solve the above problems, the invention of claim 1 is an image forming apparatus, which is an image carrier that temporarily supports a toner image and transfers it to paper, and on the image carrier after transfer to the paper. A cleaning member that scrapes off the residual toner remaining on the image carrier as it moves relative to the image carrier, and a maintenance operation that removes agglomerates generated between the image carrier and the cleaning member are executed. The maintenance operation includes a control means, and the maintenance operation includes a patch forming operation of forming a patch image which is a toner image for removing the agglomerates on the image carrier, and directing the image carrier toward the cleaning member. The edge of the patch image on the downstream side in the traveling direction of the patch image includes the moving operation of colliding the patch image on the image carrier with the cleaning member. It is characterized in that it extends in a direction non-vertical to the relative.

The invention of claim 2 is based on the paper type information of a plurality of output sheets printed out, whether or not the control means executes the patch forming operation in the image forming apparatus according to the invention of claim 1. It is characterized by having a decision-making means for making a decision.

According to the invention of claim 3, in the image forming apparatus according to the invention of claim 2, the paper type information includes information indicating whether each of the plurality of output papers is coated paper or uncoated paper. Including, the determination means is characterized in that it determines that the patch forming operation is executed on condition that the ratio of the uncoated paper to the entire plurality of output sheets is larger than the reference value.

The invention of claim 4 further includes a photoconductor that transfers a toner image to the image carrier in the image forming apparatus according to the invention of claim 3, and the reference value is the image carrier and the photoconductor. It is characterized in that it is changed according to the supply amount of the lubricant supplied to at least one of the surfaces.

The invention of claim 5 is the image forming apparatus according to any one of claims 2 to 4, wherein the determining means is a linear shape in which the image carrier and the cleaning member are in mutual contact with each other. The estimated existence range, which is the range in which the aggregate is estimated to be present, is specified in the contact portion, and it is determined that the patch image should be formed in the region corresponding to the estimated existence range on the image carrier. It is characterized by that.

The invention of claim 6 is the image forming apparatus according to the invention of claim 5, wherein the determination means is both ends of the uncoated paper included in the plurality of output sheets and both ends in a direction perpendicular to the traveling direction. It is characterized in that a range having a predetermined width in a direction perpendicular to the traveling direction is specified as the estimated existence range centered on each of the assumed passing positions on the image carrier.

The invention of claim 7 is the image forming apparatus according to the invention of claim 5, wherein the determination means divides the image carrier into a plurality of division ranges in a direction perpendicular to the traveling direction, and the plurality of divisions. Among the ranges, a division range in which the image formation rate in the image formation operation executed before the maintenance operation is smaller than a predetermined degree is specified as the estimated existence range.

The invention of claim 8 is characterized in that, in the image forming apparatus according to any one of claims 1 to 7, the patch image is formed of a solid image of toner.

The invention of claim 9 is characterized in that, in the image forming apparatus according to the invention of claim 8, the patch image is formed by superimposing a solid image of two or more colors of toner.

According to a tenth aspect of the present invention, in the image forming apparatus according to any one of claims 1 to 9, in the patch forming operation, the first patch image and the second patch image are in the traveling direction. The edges of the first patch image on the downstream side in the traveling direction are arranged so that one end of one side and the other side in the direction perpendicular to the traveling direction is ahead of the other end. The edge on the downstream side in the traveling direction of the second patch image is inclined so as to collide with the cleaning member, and the other end of the one side and the other side is the one side. It is characterized in that it is inclined in a direction of colliding with the cleaning member before the end of the.

According to the eleventh aspect of the present invention, the image carrier that temporarily supports the toner image and transfers it to the paper and the residual toner remaining on the image carrier after the transfer to the paper are moved relative to the image carrier. A patch image, which is a toner image for removing agglomerates generated between the image carrier and the cleaning member, is displayed on a computer built in an image forming apparatus including a cleaning member which is scraped off in accordance with the above. The step of executing the patch forming operation of forming on the image carrier, and b) the movement of advancing the image carrier toward the cleaning member and causing the patch image on the image carrier to collide with the cleaning member. A program for executing the step of executing the operation, and the edge of the patch image on the downstream side in the traveling direction of the patch image extends in a direction non-vertical to the traveling direction. It is characterized by doing.

The invention of claim 12 is the paper type of a plurality of output papers printed out in the program according to the invention of claim 11, as in step a), a-1) whether or not to execute the patch forming operation. It is characterized by having a step of making an informed decision.

The invention of claim 13 includes information indicating whether each of the plurality of output papers is coated paper or uncoated paper in the program according to the invention of claim 12. The step a-1) is characterized in that it is determined to execute the patch forming operation on condition that the ratio of the uncoated paper to the entire plurality of output papers is larger than the reference value. ..

The invention of claim 14 further includes, in the program according to the invention of claim 13, a photoconductor that transfers a toner image to the image carrier, and the reference value is the same as that of the image carrier. It is characterized in that it is changed according to the supply amount of the lubricant supplied to at least one surface of the photoconductor.

The invention of claim 15 is the program according to any one of claims 12 to 14, in which c) a linear contact portion in which the image carrier and the cleaning member are in mutual contact with each other. A step of specifying an estimated existence range, which is a range in which the agglomerates are estimated to exist, and d) a step of determining that the patch image should be formed in a region corresponding to the estimated existence range on the image carrier. , And are further executed by the computer.

According to the invention of claim 16, in the program according to the invention of claim 15, in the step c), both ends of the uncoated paper included in the plurality of output sheets and both ends in a direction perpendicular to the traveling direction. A range having a predetermined width in a direction perpendicular to the traveling direction with respect to each of the assumed passing positions on the image carrier is specified as the estimated existence range.

The invention of claim 17 is the program according to the invention of claim 15, wherein step c) is c-1) a step of dividing the image carrier into a plurality of division ranges in a direction perpendicular to the traveling direction. c-2) Among the plurality of division ranges, a division range in which the image formation rate in the image formation operation executed before step a) is smaller than a predetermined degree is specified as the estimated existence range. It is characterized by having.

The invention of claim 18 is characterized in that, in the program according to any one of claims 11 to 17, the patch image is formed of a solid image of toner.

The invention of claim 19 is characterized in that, in the program according to the invention of claim 18, the patch image is formed by superimposing a solid image of two or more colors of toner.

According to the invention of claim 20, in the program according to any one of claims 11 to 19, in the patch forming operation, the first patch image and the second patch image are arranged in the traveling direction. The edge on the downstream side in the traveling direction of the first patch image is such that one end of one side and the other side in the direction perpendicular to the traveling direction is earlier than the other end. The edge on the downstream side in the traveling direction of the second patch image is inclined so as to collide with the cleaning member, and the end of the other side of the one side and the other side is the end of the one side. It is characterized in that it is inclined in a direction of colliding with the cleaning member before that.

According to the inventions of claims 1 to 20, since the edge on the downstream side in the traveling direction of the patch image extends in a direction non-perpendicular to the traveling direction, the cleaning member of the edge is used. The toner in the portion that has reached first and has been scraped off by the cleaning member is swept away by the powder pressure of the toner newly reaching the cleaning member in the direction perpendicular to the traveling direction, and is perpendicular to the traveling direction. Flows towards the agglomerates in the direction. Then, when the toner flowing toward the agglomerates in the direction perpendicular to the traveling direction collides with the agglomerates, the agglomerates are peeled off from the image carrier and the cleaning member, and the direction perpendicular to the traveling direction together with the toner. Flows to and is removed. Therefore, it is possible to prevent the agglomerates from getting caught between the image carrier and the cleaning member, and it is possible to more reliably remove the agglomerates from the cleaning member.

In particular, according to the inventions of claims 2 and 12, whether or not to execute the patch forming operation is determined based on the paper type information of the plurality of output papers printed out, and thus patch forming. It is possible to more appropriately determine the pros and cons of performing an action.

In particular, according to the third and thirteenth aspects of the invention, the patch forming operation is executed on condition that the ratio of the uncoated paper to the entire printed output papers is larger than the reference value. Since the fact is determined, it is possible to more appropriately determine whether or not to execute the patch forming operation.

Further, in particular, according to the inventions of claims 4 and 14, a lubricant in which a reference value regarding the pros and cons of performing a patch forming operation is supplied to at least one surface of an image carrier and a photoconductor. Since it is changed according to the supply amount of the patch forming operation, it is possible to execute the patch forming operation more appropriately as compared with the case where the pros and cons of executing the patch forming operation are always determined using the same reference value.

Further, in particular, according to the inventions of claims 5 and 15, in the linear contact portion where the image carrier and the cleaning member are in mutual contact, in the range where agglomerates are presumed to be present. Since a certain estimated existence range is specified and it is determined that a patch image should be formed in the region corresponding to the estimated existence range on the image carrier, the region corresponding to the entire range of the contact portion on the image carrier is set. It is possible to suppress the consumption of toner as compared with the case where the patch image is always formed.

Further, in particular, according to the inventions of claims 9 and 19, a patch image is formed by superimposing solid images of two or more colors of toner, so that a patch image is formed by a solid image of a single color toner. Compared to the case where the amount of toner forming the patch image is large, the toner collides with the agglomerates adhering to the cleaning member with a larger powder pressure. Therefore, it is possible to more reliably remove the agglomerates adhering to the cleaning member from the cleaning member.

In particular, according to the inventions of claims 10 and 20, the toner flow at the edge of the first patch image and the toner flow at the edge of the second patch image are opposite to each other. Therefore, the toner collides with the agglomerates adhering to the cleaning member from both one side and the other side in the direction perpendicular to the traveling direction of the patch image. As a result, even if the toner of the first patch image does not peel off the agglomerates from the cleaning member, the toner of the second patch image can peel off the agglomerates from the cleaning member. Therefore, it is possible to more reliably remove the agglomerates adhering to the cleaning member from the cleaning member.

It is a figure which shows the schematic structure of the image forming apparatus. It is sectional drawing of the cleaning apparatus seen from the + X side. It is a figure which shows the patch image. It is a flowchart about a patch formation operation. It is a figure which shows the subroutine processing which concerns on the identification processing of the arrangement candidate area of a patch image. It is a figure which shows the print history information. It is a figure which shows the range near the edge of a paper. It is a figure which shows a plurality of division ranges. It is a conceptual diagram which shows how a patch image is scraped by a cleaning blade. It is a conceptual diagram which shows how a patch image is scraped by a cleaning blade. It is a conceptual diagram which shows how a patch image is scraped by a cleaning blade. It is a figure (graph) which shows the occurrence transition of the cleaning failure when the patch formation operation is executed, and the occurrence transition of the cleaning failure when the patch formation operation is not executed. It is a figure which shows the part where the paper and the intermediate transfer belt are in direct contact with each other. It is a flowchart about the patch formation operation which concerns on 2nd Embodiment. It is sectional drawing of the photoconductor cleaning apparatus seen from the + X side. It is a figure (graph) which shows the life ratio of a lubricant block. It is a figure which shows the patch image which concerns on the modification. It is a figure which shows the patch image which concerns on the modification. It is a conceptual diagram which shows how the patch image which concerns on a modification is scraped by a cleaning blade. It is a figure which shows the agglomerate generated between a cleaning blade and an intermediate transfer belt. It is a figure which shows how the agglomerates are pushed to the downstream side in the traveling direction. It is a figure which shows the state in which agglomerates are bitten between a cleaning blade and an intermediate transfer belt. It is a figure which looked at the state which the agglomerate was bitten between a cleaning blade and an intermediate transfer belt from the downstream side in the moving direction of a cleaning member. It is a figure which shows the state which toner slips through from both sides of agglomerates.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. First Embodiment>
<1-1. Device overview>
The image forming apparatus 1 is an apparatus for developing an electrostatic latent image on an image carrier to form an image. Here, as the image forming apparatus, an electrophotographic type print output device, and more specifically, a tandem type full-color print output device is exemplified. In FIG. 1 and the like, directions and the like are shown using an XYZ Cartesian coordinate system.

As shown in FIG. 1, the image forming apparatus 1 includes a plurality of (specifically, four) imaging units 10 (specifically, 10Y, 10M, 10C, 10K). Specifically, the image forming apparatus 1 includes a yellow imaging unit 10Y, a magenta imaging unit 10M, a cyan imaging unit 10C, and a black imaging unit 10K. Each imaging unit 10 electrophotographs an image of each color component (specifically, each component of Y (yellow), M (magenta), C (cyan), and K (black)) in the final output image. It is formed by a method and transferred to an intermediate transfer belt (also referred to as an intermediate transfer body) 21. Then, in the second transfer machine (transfer roller (secondary transfer roller)) 22, the image (toner image) of each color component superimposed on the intermediate transfer belt 21 is further transferred to the paper (transfer material). A full-color image is formed on the paper. The intermediate transfer belt 21 is also expressed as an image carrier that temporarily supports a toner image (toner image) transferred from each photoconductor 11.

The four imaging units 10 (10Y, 10M, 10C, 10K) are arranged in series along the right straight line portion of the intermediate transfer belt 21 in the right straight line portion.

Each imaging unit 10 includes a photoconductor 11, a charger 12, an exposure device (optical writing device) 13, a developing device 14, a first transfer device (primary transfer device) 15, and a cleaner (photoreceptor cleaning device) 17, respectively. And have. Specifically, in each imaging unit 10, the developer 14, the exposure device 13, the charger 12, the cleaner 17, and the first transfer device 15 clock in this order so as to surround the outer circumference of the substantially cylindrical photoconductor 11. It is arranged around. Of these, the first transfer device 15 (specifically, the transfer roller) is arranged at a position facing the photoconductor 11 with an intermediate transfer belt 21 in between.

The intermediate transfer belt 21 is wound around a plurality of rollers including a drive roller, and moves (rotates) in the direction of arrow D1 (FIG. 1) according to the rotational drive of the drive rollers.

Further, a belt cleaning device 8 is provided on the downstream side of the moving direction (rotational direction) D1 of the intermediate transfer belt 21 that has passed the position of the transfer roller 22. The detailed configuration of the belt cleaning device 8 will be described later.

A paper feed unit 30, a paper feed tray 31, and the like are provided on the lower side of the imaging unit 10K (upstream side on the transport path of each imaging unit 10).

Further, a fixing device 26 is provided on the downstream side in the transport direction of the paper that has passed the position of the transfer roller 22, and a paper ejection portion 27 is provided on the downstream side in the transport direction.

The image forming apparatus 1 prints out an image based on image data transmitted from another information processing apparatus (personal computer or the like) connected via a network or the like by using the printing mechanism as described above. , Acts as a color page printer.

Further, the image forming apparatus 1 includes a controller (control unit) 9 (see FIG. 1).

The controller 9 is a control device that is built in the image forming apparatus 1 and controls the image forming apparatus 1 in an integrated manner. The controller 9 is configured as a computer system including a CPU and various semiconductor memories (RAM, ROM, etc.). The controller 9 realizes various processing units by executing a predetermined software program (hereinafter, also simply referred to as a program) stored in the ROM (for example, EEPROM) in the CPU. The program (specifically, a program module group) may be installed in the image forming apparatus 1 via a portable recording medium such as a USB memory, a network, or the like.

The controller 9 realizes various processing units including the determination unit 91 by executing the program.

The determination unit 91 is a control unit that executes a maintenance operation (controls the execution of the maintenance operation) to remove the agglomerates M10 generated (generated) between the intermediate transfer belt 21 and the cleaning blade 2.

The maintenance operation (maintenance process) includes a patch forming operation (next description) and a moving operation (next description).

The patch forming operation (patch forming process) is an operation of forming a toner image (patch image P50 (FIGS. 3 and 7)) for removing the agglomerates M10 on the intermediate transfer belt 21. The moving operation (moving process) is an operation in which the intermediate transfer belt 21 advances (moves) toward the cleaning blade 2 and the patch image P50 on the intermediate transfer belt 21 collides with the cleaning blade 2.

When executing the maintenance operation (patch forming operation, moving operation, etc.), the determination unit 91 executes a determination process for determining whether or not to execute the patch forming operation. Specifically, the determination unit 91 determines whether or not to execute the patch forming operation based on the paper type information of the plurality of output papers (output papers) printed out by the print job.

<1-2. Detailed configuration of belt cleaning device>
FIG. 2 is a cross-sectional view of the belt cleaning device 8 (FIG. 1) seen from the + X side.

The belt cleaning device 8 includes a cleaning blade 2, a toner recovery roller 3, and a casing 4.

The cleaning blade 2 moves the toner (also referred to as residual toner or waste toner) remaining on the intermediate transfer belt 21 after transfer to paper (after image formation operation) relative to the intermediate transfer belt 21 (also referred to as residual toner or waste toner). It is a member (cleaning member) that can be scraped off (scraped off) as the intermediate transfer belt 21 rotates.

The cleaning blade 2 is a thin plate-shaped member having an elongated rectangular shape.

Further, the cleaning blade 2 is formed of an elastic member (for example, a rubber member such as nitrile rubber (NBR)).

The cleaning blade 2 is attached to the casing 4, and as shown in FIG. 2, the tip end portion (blade edge) 2A of the cleaning blade 2 is provided in contact with the surface of the intermediate transfer belt 21. Specifically, the tip of the cleaning blade 2 is in a posture facing upstream of D1 in the moving direction of the intermediate transfer belt 21 (in other words, the direction perpendicular to the axial direction of the drive roller of the intermediate transfer belt 21). It is arranged in contact with the surface of the transfer belt 21. Then, while the cleaning blade 2 is in contact with the intermediate transfer belt 21, the intermediate transfer belt 21 moves (progresses) toward the cleaning blade 2.

As the intermediate transfer belt 21 moves, the residual toner on the intermediate transfer belt 21 also moves toward the cleaning blade 2, and when the residual toner collides with the cleaning blade 2, the residual toner is scraped off from the intermediate transfer belt 21. The toner (residual toner) scraped off by the cleaning blade 2 is accumulated in the lower portion in the casing 4, is conveyed to a waste toner collection container (not shown) by the toner collection roller 3 and is collected.

<1-3. About patch formation operation>
Next, the patch forming operation will be described.

As described above, the patch forming operation is an operation of forming the patch image P50 on the intermediate transfer belt 21. The patch forming operation is performed to remove the agglomerates M10 (described below) generated between the cleaning blade 2 and the intermediate transfer belt 21 (see FIG. 20). FIG. 20 is a diagram showing agglomerates M10 generated between the cleaning blade 2 and the intermediate transfer belt 21.

Various foreign substances are present on the intermediate transfer belt 21 after the image forming operation on the paper, and the various foreign substances are accumulated in the gap between the cleaning blade 2 and the intermediate transfer belt 21 in the aggregate M10. It is generated (generated) by (accumulation) (see FIG. 20). Examples of the various foreign substances include paper powder containing a filler added to the paper, an external additive externally added to the toner, and / or a lubricant (also referred to as a lubricant) applied to the photoconductor 11 and the like. Exists.

Here, since a coating layer is provided on the surface of the coated paper (coated paper, etc.), the coated paper produces more paper dust than the non-coated paper (plain paper, recycled paper, etc.). It is hard to occur. On the other hand, the surface of the uncoated paper is not provided with a coating layer, and the non-coated paper is more likely to generate paper dust than the coated paper. Therefore, when the uncoated paper is transported, more paper dust is transferred to the intermediate transfer belt 21 as compared with the case where the coated paper is transported, and the cleaning blade 2 and the intermediate transfer belt 21 Aggregates M10 are likely to be generated (easily formed) in the gaps between them (see FIG. 20).

In consideration of this point, whether or not to execute the patch forming operation is determined based on the paper type information of the plurality of output papers (printed papers) that have been printed out. Specifically, depending on whether the ratio of uncoated paper (also referred to as uncoated paper ratio) to the total of a plurality of output papers is larger than the reference value V10 (here, V11 (for example, 60%)). Whether or not to execute the patch formation operation is decided.

FIG. 4 is a flowchart relating to the patch forming operation. The operation of FIG. 4 is executed at a predetermined timing (for example, when the number of print output sheets reaches a predetermined number (for example, 10,000 sheets)).

Prior to the operation of FIG. 4, the paper type information is recorded in the print history (print history information) (see FIG. 6) every time the print job is executed.

The paper type information is information indicating whether each of the plurality of output papers is coated paper or uncoated paper. The paper type information is recorded in the print history based on the setting contents of the print job to which the execution instruction is given prior to step S11.

Here, in the image forming apparatus 1, the type (paper type) of the paper arranged in each paper feed tray of the image forming apparatus 1 is set in advance. For example, it is preset that plain paper is arranged in the paper feed tray T1 (not shown), and that coated paper is arranged in the paper feed tray T2 (not shown).

The user specifies the paper tray when instructing the execution of the print job. In response to the user's operation of specifying the paper feed tray, the image forming apparatus 1 uses the paper type information (paper type) of the paper (output paper) to be printed out in the print job based on the paper feed tray specified by the user. (Setting information) is recorded in the print history. For example, when the paper feed tray T1 is specified by the user, the print history includes paper type information indicating that the output paper (here, plain paper) arranged in the paper feed tray T1 is uncoated paper. Recorded in. Further, when the paper feed tray T2 is specified by the user, paper type information indicating that the output paper (here, coated paper) arranged in the paper feed tray T2 is coated paper is included in the print history. Recorded.

In this way, the paper type information regarding the plurality of output papers is recorded in advance in the print history (FIG. 6), and then the operation of FIG. 4 is started.

First, in step S11, the determination unit 91 acquires the paper type information (paper type information of the output paper) recorded in the print history, and based on the paper type information, the uncoated paper ratio is used as a reference. It is determined whether or not it is larger than the value V11. Here, it is determined whether or not the uncoated paper ratio is larger than the reference value V11 based on the paper type information of the latest predetermined number of output sheets (for example, 10,000 sheets). Not limited to this, for example, the uncoated paper ratio is larger than the reference value V11 based on the paper type information (paper type setting information) in the latest predetermined number of jobs (for example, the latest 10 jobs). Whether or not it may be determined.

FIG. 6 is a diagram showing a print history (print history information). Here, it is assumed that 10 print jobs have been executed before the latest predetermined number of sheets (10,000 sheets) are output.

As shown in FIG. 6, out of the 10,000 printed papers printed out, the total number of uncoated papers is 6,400, and the uncoated paper ratio (the latest 10,000 printed papers). The ratio of uncoated paper to the whole) is 64%. In this case, the determination unit 91 determines in step S11 that the uncoated paper ratio (64%) is larger than the reference value V11 (here, 60%).

Then, the process proceeds from step S11 to step S12, and the determination unit 91 determines that the patch forming operation is to be executed. When the uncoated paper ratio is smaller than the reference value V11, the process proceeds from step S11 to step S15, and it is determined that the patch forming operation is not executed.

In this way, the determination unit 91 determines that the patch forming operation is executed on the condition that the uncoated paper ratio is larger than the reference value V10 (here, V11). Then, the process proceeds from step S12 to step S13.

In step S13, the determination unit 91 specifies an arrangement candidate region of the patch image P50 in the patch forming operation (a candidate region in which the patch image P50 should be arranged (formed) in the entire surface area of the intermediate transfer belt 21).

FIG. 5 is a diagram showing a subroutine process related to a candidate area specifying process (step S13) for specifying an arrangement candidate area (arrangement target area) of the patch image P50.

In step S13, a linear contact portion (contact portion extending in the direction D2 perpendicular to the traveling direction D1) R10 (see FIGS. 7 and 8) in which the intermediate transfer belt 21 and the cleaning blade 2 are in mutual contact with each other. Of these, the range in which the aggregate M10 is presumed to be present (estimated existence range B1) is specified (steps S21 to S25). Then, the corresponding region F1 (described later) corresponding to the estimated existence range B1 on the intermediate transfer belt 21 is specified as an arrangement candidate region of the patch image P50 (step S26).

Here, the estimated existence range B1 is specified using each of the two criteria (steps S21 to S25). Specifically, the estimated existence range B1 is specified using the first criterion for both ends of the uncoated paper (steps S21 and S22), and then the estimated existence range B1 is specified using the second criterion for the image formation rate. The range B1 is further specified (steps S23-S25).

First, an operation (steps S21, S22) for specifying the estimated existence range B1 using the first reference will be described.

Here, as shown in FIG. 13, the portion of the intermediate transfer belt 21 on which the toner image N1 is formed during the image forming operation on the paper (specifically, uncoated paper) 100 is formed on the paper 100. On the other hand, the portion where the toner image N1 is not formed comes into direct contact with the paper 100, whereas it does not come into direct contact with the paper 100. Therefore, the portion of the intermediate transfer belt 21 that is in direct contact with the paper 100 (without passing through the toner image N1) is compared with the portion that is not in direct contact with the paper 100. As a result, paper dust is easily transferred from the paper (uncoated paper) 100 (the amount of paper dust transferred from the paper 100 is large).

For example, printing margins are often provided at both end portions in the paper direction D2 (paper width direction), and a toner image is formed (printed) as compared with the central portion of the paper. Few. Therefore, there are many opportunities for the paper and the intermediate transfer belt 21 to come into direct contact (without the toner image) at both ends of the paper. That is, in the intermediate transfer belt 21, more paper dust is applied to the contact portion of the paper (uncoated paper) with both end portions of the paper (non-coated paper) than with the contact portion with the central portion of the paper. Transfer from paper). Therefore, agglomerates M10 are generated in the contact portion R10 (FIG. 7) between the intermediate transfer belt 21 and the cleaning blade 2 corresponding to the passing positions Q10 at both ends of the uncoated paper on the intermediate transfer belt 21. It is estimated that it is relatively likely to be done.

Further, although the passing positions of both ends of the paper on the intermediate transfer belt 21 (passing positions in the direction D2 perpendicular to the traveling direction D1) Q10 (FIG. 7) are predetermined for each paper size, during actual paper transport, Paper may be conveyed with a slight deviation in the direction D2 with respect to a predetermined passing position (assumed passing position) Q10.

In consideration of these points, in steps S21 and S22, each of the assumed passing positions Q10 on the intermediate transfer belt 21 at both ends (both ends in the direction D2) of the uncoated paper included in the plurality of output papers is set. A range having a predetermined width (for example, a width of 10 mm) in the direction D2 as the center (also referred to as a paper edge vicinity range (or paper edge predetermined range) A10) (see FIG. 7) is specified as an estimated existence range B1.

More specifically, considering that the assumed passing position Q10 differs for each paper size, the paper edge neighborhood range A10 relating to the paper size of the uncoated paper included in the plurality of output papers is specified as the estimated existence range B1. Will be done. In other words, the paper edge neighborhood range A10 for all uncoated paper sizes (sizes of uncoated paper) included in the print history (FIG. 6) may be specified as the estimated existence range B1.

First, in step S21, the determination unit 91 acquires the paper size of the uncoated paper included in the plurality of (10,000 sheets in this case) output papers based on the setting information (print history) in the print job. Here, three types of paper sizes (A3 size, A4 size, and postcard size) are acquired (see FIG. 6).

Then, in step S22, the determination unit 91 specifies the range A10 (FIG. 7) near the paper edge of the uncoated paper of each paper size as the estimated existence range B1 based on the paper size of the non-coated paper. Here, the paper edge neighborhood range A10 for each of the A4 size, the A3 size, and the postcard size is specified as the estimated existence range B1.

In this way, the estimated existence range B1 is specified using the first criterion for both ends of the uncoated paper (steps S21, S22). Then, the process proceeds from step S22 to steps S23 to S25.

Next, an operation (steps S23 to S25) of specifying the estimated existence range B1 by using the second reference regarding the image formation rate will be described.

In steps S23 to S25, the low formation rate range (described below) is specified as the estimated existence range B1.

The low formation rate range is larger than the maintenance operation among the plurality of (8 in this case) division ranges A50 (A51 to A58) (see FIG. 8) in which the intermediate transfer belt 21 is divided in the direction D2 perpendicular to the traveling direction D1. The image formation rate (printing rate) in the previously executed image formation operation is a division range smaller than a predetermined degree. More specifically, the low formation rate range is a division range in which the image formation rate in the corresponding region (predetermined length region (described later)) is smaller than a predetermined degree among the plurality of division ranges A50. The low formation rate range is also referred to as a low print rate range.

First, in step S23, the determination unit 91 divides the intermediate transfer belt 21 (contact portion R10) into a plurality of (here, eight) division ranges A50 (A51 to A58) in the direction D2 (see FIG. 8). It is determined whether or not each division range A50 (A51 to A58) is in the low formation rate range.

Specifically, for each of the plurality of division ranges A51 to A58, the ratio (image formation rate) of the adhesion area of the toner (toner for transferring to paper) to the area of the corresponding predetermined length region is calculated. The predetermined length region is a region in which the predetermined section K1 (described below) extends along the traveling direction D1 with the division range A50 as the lateral direction. The predetermined section K1 is a section (a section of 500 meters) between a position retroactively from the end position of the latest image forming operation by a predetermined distance (for example, 500 meters) and the end position. That is, the area of the predetermined length region is calculated by the product of the width of the division range A50 and the predetermined distance (width of the division range A50 × predetermined distance). Then, it is determined whether or not the image formation rate in the corresponding predetermined length region is less than the predetermined value W1 (for example, 3%) for each of the plurality of division ranges A51 to A58. For example, when the image formation rate with respect to the division range A58 is smaller than the predetermined value W1, it is determined in step S23 that the division range A58 is a low formation rate range.

Then, in step S24, the determination unit 91 determines the existence or nonexistence of the low formation rate range.

For example, when it is determined in step S23 that any one of the plurality of division ranges A51 to A58 (for example, the division range A58) is in the low formation rate range, it is determined in step S24 that the low formation rate range exists. The process proceeds from step S24 to step S25. When it is determined in step S23 that none of the plurality of division ranges A51 to A58 is in the low formation rate range, it is determined in step S24 that the low formation rate range does not exist, and the process starts from step S24. The process proceeds to step S26 without going through step S25.

In step S25, the determination unit 91 specifies the division range A50 (for example, A58) determined to be the low formation rate range among the plurality of division ranges A51 to A58 as the estimated existence range B1.

In this way, the estimated existence range B1 is specified using the first criterion for both ends of the uncoated paper (steps S21 and S22), and the estimated existence range B1 is determined using the second criterion for the image formation rate. Further specified (steps S23-S25).

Then, the process proceeds from step S25 to step S26.

In step S26, the determination unit 91 corresponds to the estimated existence range B1 on the intermediate transfer belt 21 (paper edge vicinity range A10 and low formation rate range (classification range determined to be low formation rate range) A50). It is determined that the patch image P50 should be formed in the corresponding region (two-dimensional region) F1 (see FIGS. 7 and 8). Specifically, the determination unit 91 specifies the corresponding region F1 as an arrangement candidate region of the patch image P50. Specifically, of the entire surface region of the intermediate transfer belt 21, an elongated shape having an estimated existence range B1 as the total width (the length in the lateral direction is the width of the estimated existence range B1) and extending in the traveling direction D1. The rectangular region F1 of the shape is specified as an arrangement candidate region of the patch image P50.

When the arrangement candidate area of the patch image P50 is specified in this way (step S13), the process proceeds from step S13 (FIG. 4) to step S14, and maintenance operations (patch forming operation and moving operation) are executed. ..

Specifically, the patch image P50 is formed on the intermediate transfer belt 21 in the region specified as the placement candidate region (corresponding region F1 (see FIGS. 7 and 8) corresponding to the estimated existence range B1).

Note that FIG. 7 shows a patch image P50 formed in the corresponding region F1 corresponding to the paper edge neighborhood range A10 (estimated existence range B1). Further, FIG. 8 shows a patch image P50 formed in the corresponding region F1 corresponding to the division range A50 (estimated existence range B1) determined to be in the low formation rate range. When both the paper edge vicinity range A10 and the low formation rate range A50 are specified as the estimated existence range B1, the patch image P50 is formed in both the corresponding area F1 of FIG. 7 and the corresponding area F1 of FIG. To. In this case, when at least a part of the paper edge neighborhood range A10 and at least a part of the low formation rate range A50 overlap, the correspondence corresponding to the union range of the paper edge neighborhood range A10 and the low formation rate range A50. The patch image P50 is formed in the region (arrangement candidate region).

Then, the intermediate transfer belt 21 advances toward the cleaning blade 2, and the patch image P50 on the intermediate transfer belt 21 collides with the cleaning blade 2.

FIG. 3 is a diagram showing a patch image P50.

The patch image P50 is a toner image for removing the agglomerates M10 generated between the intermediate transfer belt 21 and the cleaning blade 2. Here, the patch image P50 is formed of a solid image of a single color (any one of each YMCK color) toner (toner layer). The patch image P50 is not limited to a solid image, and may be, for example, a halftone dot image of a predetermined degree (for example, 90%) or more.

The edge (boundary portion) E1 of the patch image P50 and the edge E1 on the downstream side of the traveling direction (moving direction of the intermediate transfer belt 21) D1 of the patch image P50 is not perpendicular (and) to the traveling direction D1. It extends in the non-parallel) direction C1. In other words, the angle θ (FIG. 3) formed by the extension direction C1 of the edge E1 (edge oblique to the traveling direction D1) on the downstream side of the traveling direction D1 of the patch image P50 and the traveling direction D1 is It is non-right angle. The angle θ is preferably 30 to 60 degrees (more preferably 45 degrees). Further, it is preferable that the edge E1 extends linearly.

As shown in FIG. 3, here, the patch image P50 (P51A) is formed in a triangular shape. The patch image P50 (P52) may be formed in a rectangular shape (rectangular shape or the like), for example, as shown in FIG. In this case, each side of the rectangular patch image P52 is skewed with respect to the traveling direction D1.

Further, here, the length (width) of the direction D2 of one patch image P50 (specifically, the edge E1 of the patch image P50) is the length of the estimated existence range B1 (FIG. 3) (direction D2 of the arrangement candidate region). Is the same as the length (width) of. Not limited to this, the width of the direction D2 of the patch image P50 (edge E1) may be larger than the length of the estimated existence range B1 and conversely smaller than the length of the estimated existence range B1.

Further, here, a plurality of patch images P50 (three in detail) are arranged in a row along the traveling direction D1. Specifically, the edge E1 on the downstream side of each of the plurality of patch images P50 (P51A) arranged along the traveling direction D1 is one side (left side) in the direction D2 as shown in FIG. The left end (left end) of the other side (right side) is inclined in the direction of colliding with the cleaning blade 2 before the right end (right end). More specifically, the widths (lengths in direction D2) of the plurality of patch images P51A are the same as each other. These patch images P51A are arranged in a row along the traveling direction D1 (in a direction parallel to the traveling direction D1) in the arrangement candidate region.

In the patch forming operation, such a patch image P50 is transferred from the photoconductor 11 to the intermediate transfer belt 21 and formed on the intermediate transfer belt 21.

When performing the maintenance operation (movement operation), a separation operation is performed to separate the secondary transfer roller 22 (FIG. 1) from the intermediate transfer belt 21. As a result, the entire amount of the patch image P50 formed on the intermediate transfer belt 21 reaches (collides) with the cleaning blade 2. However, the present invention is not limited to this, and for example, by applying a secondary transfer bias (secondary transfer voltage) having the same polarity as the polarity of the toner image (patch image P50) to the secondary transfer roller 22, the toner image is transferred. The entire amount of the patch image P50 on the intermediate transfer belt 21 may reach the cleaning blade 2 without being electrostatically transferred to the next transfer roller 22.

Then, when the patch image P50 formed on the intermediate transfer belt 21 reaches the cleaning blade 2, the patch image P50 is scraped off by the cleaning blade 2. At this time, as described below, at the portion of the edge E1 of the patch image P50 that has reached the cleaning blade 2, the toner of the patch image P50 scraped off by the cleaning blade 2 moves in the traveling direction D1 of the patch image P50. It flows toward one side (here, the right side) in the vertical direction D2 (left-right direction in FIGS. 9 to 11 and the like).

9 to 11 are views (top view) showing how the patch image P50 of the intermediate transfer belt 21 is scraped off by the cleaning blade 2.

First, when the left end of the edge E1 of the patch image P50 reaches the cleaning blade 2 (see FIG. 9), the toner at the left end of the edge E1 (toner on the intermediate transfer belt 21) is scraped off by the cleaning blade 2 and intermediate. It peels off from the transfer belt 21. The toner (powder) peeled off from the intermediate transfer belt 21 slightly moves (spills) from the reaching position to the cleaning blade 2 to the right side of FIG. 9 (the direction in which the toner can move).

When new toner (subsequent toner) reaches the cleaning blade 2 in this state, the toner that first reaches the cleaning blade 2 and is peeled off from the intermediate transfer belt 21 is the powder pressure of the subsequent toner (intermediate among the edges E1). The pressure received from the right surface of the portion newly reached to the transfer belt 21) is swept to the right side of FIG. The toner that has been washed away to the right side then falls and is collected in the lower portion of the casing 4 (FIG. 2).

After that, even when the patch image P50 further advances from the state of FIG. 9 to the downstream side of the traveling direction D1 (see FIG. 10), similarly, the portion of the edge E1 of the patch image P50 that has reached the cleaning blade 2 The toner is scraped off by the cleaning blade 2 and slightly moved to the right side, and is swept to the right side by the powder pressure of the subsequent toner.

In this way, of the edge E1 extending in the direction non-perpendicular to the traveling direction D1, the toner (powder) of the portion that first reaches the cleaning blade 2 and is scraped off by the cleaning blade 2 follows. It is swept to the right by the powder pressure of the toner. More specifically, such an event occurs continuously with the movement (progress) of the intermediate transfer belt 21.

Then, when the edge E1 collides with the agglomerate M10, the toner of the portion of the edge E1 scraped off by the cleaning blade 2 immediately before reaching the agglomerate M10 is directed toward the agglomerate M10 (aggregate). It is swept away (from the left side of M10). When the toner flowing to the right side collides with the agglomerate M10 (specifically, the left side surface of the agglomerate M10), the agglomerate M10 is peeled off from the cleaning blade 2 by receiving the force (powder pressure) of the toner from the left side. After that, the agglomerate M10 flows to the right side together with the toner (see FIG. 11) and is collected (removed) in the lower portion in the casing 4 (FIG. 2).

As described above, the agglomerate M10 is removed. Therefore, since the agglomerates M10 are prevented from being caught between the intermediate transfer belt 21 and the cleaning blade 2, the technique described in Patent Document 1 (edge E90 extending in the direction D2 perpendicular to the traveling direction D1). Compared with the technique of colliding (FIG. 21) with the agglomerate M10), it is possible to remove the agglomerate M10 from the cleaning blade 2 more reliably. As a result, it is possible to suppress the occurrence of cleaning defects.

FIG. 12 is a diagram showing a transition of occurrence of cleaning defects (here, streak-shaped image noise) when the patch forming operation as described above is executed and a transition of occurrence of cleaning defects when the patch forming operation is not executed (here). Graph).

Here, when the external additive of the toner and the lubricant on the photoconductor 11 are transferred to the intermediate transfer belt 21 in a state where a relatively large amount of paper dust is present on the intermediate transfer belt 21, the cleaning blade 2 and the cleaning blade 2 are used. Aggregates M10 are particularly likely to be formed with the intermediate transfer belt 21. In order to compare the transition of cleaning defects with respect to whether or not the patch forming operation is executed in a situation where agglomerates M10 are likely to be generated, here, 4000 sheets of uncoated paper (recycled paper, etc.) having a low printing rate (for example, 0%) are used. An experiment is conducted in which the operation of transporting 1000 sheets of uncoated paper having a high printing rate (for example, 30%) is repeated. More specifically, by transporting 4000 sheets of uncoated paper having a low printing rate, a relatively large amount of paper dust is present on the intermediate transfer belt 21, and by transporting 1000 sheets of uncoated paper having a high printing rate. The external additive and the lubricant are transferred to the intermediate transfer belt 21. In this way, in a situation where agglomerates M10 are likely to be generated, the transition of occurrence of cleaning defects regarding whether or not the patch forming operation is executed is compared. In order to confirm the transition of the occurrence of cleaning defects when the patch forming operation is executed, the patch forming operation is executed at the timing when a predetermined number of sheets (for example, 10,000 sheets) of paper are conveyed. That is, the patch forming operation is executed every predetermined number of sheets.

As a result of such an experiment, when the patch forming operation is not executed, a cleaning defect (streak-like image noise) starts to occur when the number of print outputs reaches 80,000. On the other hand, when the patch forming operation for forming the patch image P50 (FIG. 3) as described above is executed every predetermined number of sheets (10,000 sheets in this case), the number of printouts exceeds 200,000. However, it was confirmed that no cleaning failure occurred (see FIG. 12). As can be seen from such experimental results, it is possible to suppress the occurrence of cleaning defects by executing the patch forming operation.

Further, in the first embodiment, whether or not to execute the patch forming operation is determined based on the paper type information of the plurality of output papers that have been printed out (step S11). More specifically, it is determined that the patch forming operation is executed on condition that the ratio of the uncoated paper to the entire plurality of output papers (non-coated paper ratio) is larger than the reference value V10. Therefore, it is possible to more appropriately determine whether or not to execute the patch forming operation.

Specifically, in the first embodiment, the uncoated paper ratio and the reference value V10 are obtained in response to the arrival of a predetermined timing (for example, the timing when the number of print output sheets reaches a predetermined number (for example, 10,000 sheets)). The magnitude relationship with is compared with, and whether or not to execute the patch forming operation is determined (step S11). More specifically, even when a predetermined timing is reached, when the uncoated paper ratio is smaller than the reference value V10, it is determined not to execute the patch forming operation (step S15), and the patch image with toner is used. P50 is not formed on the intermediate transfer belt 21. Therefore, as compared with the case where the patch forming operation is always executed in response to the arrival of a predetermined timing, the execution frequency of the patch forming operation is reduced, so that it is possible to suppress the consumption of toner.

Further, in the first embodiment, of the contact portion R10 between the intermediate transfer belt 21 and the cleaning blade 2, the range where the agglomerates M10 are presumed to exist (estimated existence range B1) is specified, and the intermediate transfer belt 21 is covered. It is determined that the patch image P50 should be formed in the region F1 (see FIGS. 7 and 8) corresponding to the estimated existence range B1 of the above (step S13). Therefore, it is possible to further suppress toner consumption as compared with the case where the patch image P50 is always formed in the region corresponding to the entire range of the contact portion R10.

By the way, in the image forming apparatus, an image stabilizing process (image stabilizing operation) may be performed in order to correct the formation position of the toner image of each color of YMCK and the density of the reproduced image. In the image stabilization process, a resist correction process or the like is executed.

For example, Patent Document 2 discloses a technique for performing such an image stabilization operation (resist correction processing, etc.).

In the resist correction process in Patent Document 2, a resist pattern made of toner for each color of YMCK is formed on the intermediate transfer belt in a line shape and inclined at an angle of, for example, 45 degrees with respect to the traveling direction of the intermediate transfer belt. At the same time, the resist patterns of each color are arranged in the traveling direction of the intermediate transfer belt in a predetermined region on the intermediate transfer belt. Then, the formation position of the resist pattern of each YMCK color is detected by the optical sensor, and the amount of misalignment of each color is obtained based on the detection result. The image formation position of each color is corrected based on the amount of misalignment obtained in this way.

In such an image stabilization operation (an operation of forming a toner image for correcting the toner formation position of each YMCK color on the intermediate transfer belt), the amount of change (change amount) in temperature and humidity in the image forming apparatus is predetermined. It is carried out when the value is exceeded.

On the other hand, the patch forming operation in the present application is performed for a purpose different from the image stabilizing operation, and is performed based on conditions different from the image stabilizing operation.

Specifically, in the image stabilization operation in the technique described in Patent Document 2, a pattern image for correcting the image formation position of each color of YMCK is formed on the intermediate transfer belt, whereas the patch formation in the present application. In operation, as described above, a patch image P50 for removing the agglomerates M10 generated between the intermediate transfer belt 21 and the cleaning blade 2 is formed on the intermediate transfer belt 21. Further, the image forming operation in the technique described in Patent Document 2 is executed when the amount of change in temperature and humidity in the image processing apparatus exceeds a predetermined value, whereas the patch forming operation in the present application is described above. As described above, the execution is performed based on the paper type information of the plurality of output papers that have been printed out (whether each of the plurality of output papers is coated paper or uncoated paper).

As described above, the patch forming operation in the present application is significantly different from the technique described in Patent Document 2.

<2. Second Embodiment>
The second embodiment is a modification of the first embodiment. Hereinafter, the differences from the first embodiment will be mainly described.

In the first embodiment, the reference value V10 (V11) relating to the pros and cons of executing the patch forming operation is fixed.

On the other hand, in the second embodiment, the reference value V10 is changed according to the supply amount of the lubricant supplied to the surface of the photoconductor 11.

Here, a lubricant (lubricant) that reduces the friction coefficient of the photoconductor 11 is applied (supplied) to the surface of the photoconductor 11 (FIG. 1). The lubricant applied to the surface of the photoconductor 11 is transferred from the photoconductor 11 to the intermediate transfer belt 21 during the image forming operation. When the lubricant transferred from the photoconductor 11 to the intermediate transfer belt 21 and the paper dust transferred from the paper (uncoated paper) to the intermediate transfer belt 21 are mixed, the paper dust tends to solidify. Therefore, when the supply amount of the lubricant supplied (coated) to the photoconductor 11 is larger than a certain level, the agglomerates in the cleaning blade 2 are compared with the case where the supply amount of the lubricant is less than a certain level. The growth rate of M10 (the rate at which the aggregate M10 grows) is high. On the contrary, when the supply amount of the lubricant is less than a certain level, the growth rate of the aggregate M10 is slower than when the supply amount of the lubricant is more than a certain level.

In consideration of this point, in the second embodiment, the reference value V10 is changed according to the supply amount of the lubricant supplied to the surface of the photoconductor 11.

The lubricant is applied (supplied) to the surface of the photoconductor 11 by the lubricant application mechanism 70 (described below) provided in the photoconductor cleaning device 17 (FIG. 1).

FIG. 15 is a cross-sectional view of the photoconductor cleaning device 17 as viewed from the + X side.

The lubricant coating mechanism 70 has a brush (lubricant coating brush) 71, a lubricant block (solid lubricant) 72, and an elastic member 73.

The brush 71 is a member that scrapes the lubricant from the lubricant block 72 and applies (supplies) the scraped lubricant to the photoconductor 11. The brush 71 is provided in contact with the surface of the photoconductor 11, and is configured to be rotatable.

The elastic member 73 is a member that presses the lubricant block 72 toward the brush 71. As the elastic member 73, a compression coil spring (a compression coil spring in a state of being contracted from the natural length) is exemplified.

In the lubricant application mechanism 70, the lubricant is scraped from the lubricant block 72 by the brush 71 according to the rotation of the brush 71, and the scraped lubricant is applied (supplied) to the photoconductor 11.

As described below, the amount of lubricant supplied from the lubricant block 72 to the photoconductor 11 decreases over time.

FIG. 16 is a diagram showing changes in the supply amount of the lubricant. The vertical axis in FIG. 16 shows the supply amount of the lubricant supplied to the photoconductor 11, and the horizontal axis in FIG. 16 shows the life ratio. The life ratio is the supply of the lubricant supplied from the lubricant block 72 to the photoconductor 11 at the end of its life (the state in which the lubricant block 72 should be replaced with the new lubricant block 72 (the state at which the life has reached)). The ratio of the current lubricant supply to the quantity. The smaller the life ratio, the closer the lubricant block 72 is to a new state, and the larger the life ratio, the closer the lubricant block 72 is to the end of life state.

The amount (supply amount) of the lubricant applied to the photoconductor 11 is the largest when the lubricant block 72 is in a new state (when the life ratio of the lubricant block 72 is 0%). After that, each time the lubricant of the lubricant block 72 is scraped off by the brush 71, the lubricant block 72 gradually becomes smaller (the life ratio of the lubricant block 72 becomes larger), and the lubricant is supplied to the photoconductor 11. The amount decreases over time. For example, when the life ratio of the lubricant block 72 reaches 50%, the supply amount of the lubricant supplied from the lubricant block 72 to the photoconductor 11 is the supply of the lubricant supplied from the lubricant block 72 in a new state. The amount is reduced to about 2/3 (≈0.42 / 0.65) with respect to the amount (initial supply amount).

In this second embodiment, the reference value V10 regarding the pros and cons of executing the patch forming operation according to the supply amount (the supply amount of the lubricant from the lubricant block 72 to the photoconductor 11) that decreases with time in this way. Is changed. Specifically, the reference value V10 is switched depending on whether or not the life ratio of the lubricant block 72 is smaller than the predetermined value G (for example, 50%).

FIG. 14 is a flowchart relating to the patch forming operation according to the second embodiment. As shown in FIG. 14, in the second embodiment, the processes of steps S31 and S32 are executed in addition to steps S11 to S15.

In step S31, the determination unit 91 determines whether or not the life ratio is smaller than the predetermined value G (for example, 50%). In other words, the supply amount of the lubricant supplied from the lubricant block 72 to the photoconductor 11 is 2/3 of the initial supply amount (the supply amount of the lubricant supplied from the lubricant block 72 in a new state). It is determined whether or not the amount has been reduced to.

When the life ratio of the lubricant block 72 is smaller than the predetermined value G (50%) (in other words, when the supply amount of the lubricant is larger than 2/3 of the initial supply amount), the treatment starts from step S31. Proceeding to step S11, the determination unit 91 determines whether or not to execute the patch forming operation using the reference value V11 (V10) (for example, 60%).

On the other hand, when the life ratio of the lubricant block 72 is equal to or more than a predetermined value G (50%) (in other words, when the supply amount of the lubricant is less than 2/3 of the initial supply amount), the treatment is a step. Proceeding from S31 to step S32, the determination unit 91 determines whether or not to execute the patch forming operation using the reference value V12 (V10). The reference value V12 (for example, 80%) is a value (V12> V11) larger than the reference value V11 (60%). Specifically, whether or not to execute the patch forming operation is determined depending on whether or not the uncoated paper ratio is larger than the reference value V12 (80%).

The processing contents of steps S12 to S15 are the same as those in the first embodiment.

As described above, in the second embodiment, the reference value V10 regarding the pros and cons of executing the patch forming operation is changed according to the supply amount of the lubricant supplied to the photoconductor 11, so that the same reference value V10 (for example, for example) is always used. Compared with the case where the pros and cons of executing the patch forming operation are determined in V11), it is possible to execute the patch forming operation more appropriately.

Specifically, when the supply amount of the lubricant is less than a certain level (here, 2/3 of the initial supply amount), the reference value V12 (80%) is larger than the reference value V11 (60%). Is used to determine whether or not to execute the patch forming operation (step S32). In other words, if the growth rate of the agglomerates M10 is relatively slow (compared to the case where the amount of lubricant supplied is higher than a certain amount) due to the amount of lubricant supplied being less than a certain level, the patch The frequency of execution of the forming operation is reduced. Therefore, it is possible to suppress toner consumption.

Here, when the lubricant is supplied to the photoconductor 11, the reference value V10 is changed according to the supply amount of the lubricant, but the present invention is not limited to this. For example, when the lubricant is not supplied to the photoconductor 11 and the lubricant is supplied to the intermediate transfer belt 21, the reference value V10 is changed according to the supply amount of the lubricant supplied to the intermediate transfer belt 21. May be done. When the lubricant is supplied to both the photoconductor 11 and the intermediate transfer belt 21, the reference value is based on the amount of the lubricant supplied to both the photoconductor 11 and the intermediate transfer belt 21. V10 may be changed.

<3. Modification example>
Although the embodiments of the present invention have been described above, the present invention is not limited to the contents described above.

For example, in each of the above embodiments, the patch image P50 is formed by a solid image of a single color toner (toner layer), but the patch image P50 is not limited to this, but is not limited to this, and is about twice as large as that of a two color toner (a single color toner layer). The patch image P50 may be formed by superimposing the solid images of toner) (with two color toner layers). Alternatively, the patch image P50 may be formed by superimposing solid images of three or more colors of toner.

According to this, the amount of toner forming the patch image P50 is larger than that in the case where the patch image P50 is formed by the solid image with the monochromatic toner, and the amount of the toner adhering to the cleaning blade 2 is higher than that of the aggregate M10. Toner collides with a large powder pressure. Therefore, the agglomerates M10 adhering to the cleaning blade 2 can be more reliably peeled off from the cleaning blade 2.

The belt cleaning device 8 has a limit (cleaning limit) on the amount of toner that the cleaning blade 2 can clean. When the amount of toner (adhesion amount) of the toner that has reached the cleaning blade 2 exceeds the cleaning limit, some toner slips between the cleaning blade 2 and the intermediate transfer belt 21, resulting in poor cleaning such as streak-like image noise. It may occur.

In order to prevent the occurrence of such a problem, when the patch image P50 is formed by superimposing solid images of two or more colors of toner, for example, even if the intermediate transfer belt 21 is rotated two or more turns in the patch forming operation. Good. Specifically, as a result of the rotation operation of the first round of the intermediate transfer belt 21, some toner in the patch image P50 with two or more colors of toner temporarily slips between the cleaning blade 2 and the intermediate transfer belt 21. However, the cleaning blade 2 may scrape off some of the toner during the rotation operation on the second lap.

Further, in each of the above embodiments, the edge E1 on the downstream side of each of the plurality of patch images P51A (see FIG. 3) arranged in the traveling direction D1 is the left end (left end) of both sides in the direction D2. ) Is inclined in the direction of colliding with the cleaning blade 2 before the right end (right end) (in short, the direction of the right shoulder downward) (“right shoulder downward edge”). In other words, in each of the above embodiments, the plurality of patch images P50 from one side (left side) of both sides in the direction D2 perpendicular to the traveling direction D1 with respect to the aggregate M10 adhering to the cleaning blade 2. (See also FIG. 11).

Here, the shape of the agglomerate M10 is indeterminate. Therefore, depending on the shape of the agglomerate M10, the toner (toner of the patch image P50) is applied from only one side (for example, the left side) in the direction D2 perpendicular to the traveling direction D1 with respect to the agglomerate M10 adhering to the cleaning blade 2. There is a possibility that the agglomerate M10 will not be peeled off from the cleaning blade 2 just by colliding.

In consideration of this point, as described below, not only one side (left side) of both sides of the direction D2 perpendicular to the traveling direction D1 but also the other side with respect to the aggregate M10 adhering to the cleaning blade 2. The toner may also collide from (right side). According to this, the agglomerates M10 adhering to the cleaning blade 2 can be more reliably peeled off from the cleaning blade 2.

FIG. 18 is a diagram showing a patch image P50 according to this modified example.

Here, three patch images P50 are formed in a row along the traveling direction D1. Specifically, in the arrangement candidate region, the patch images P51A, P51B, and P51A are arranged in a row along the traveling direction D1 (in a direction parallel to the traveling direction D1) in this order. In other words, the patch images P51A and P51B are alternately arranged in a row along the traveling direction D1.

As shown in FIG. 18, the edge E1 on the downstream side of the traveling direction D1 of the patch image P51A is in the direction in which the left end of both sides in the direction D2 collides with the cleaning blade 2 before the right end (in short, the right shoulder). It is inclined in the downward direction (the "downward edge"). On the other hand, the edge E1 on the downstream side of the traveling direction D1 of the patch image P51B is in the direction in which the right end of both sides in the direction D2 collides with the cleaning blade 2 before the left end (in short, the direction in which the left shoulder is lowered). ("Left shoulder down edge"). Specifically, the width of the edge E1 (right shoulder down edge) of the patch image P51A (length in the direction D2) and the width of the edge E1 (left shoulder down edge) of the patch image P51B are the same length. More specifically, the patch image P51A and the patch image P51B are formed line-symmetrically with respect to the center line (center line parallel to the traveling direction D1) U1 of the patch image P51A (patch image P51B).

Such patch images P51A and P51B may be arranged in the traveling direction D1.

According to this, when the patch images P51A and P51B are scraped off by the cleaning blade 2, the toner flow at the edge E1 of the patch image P51A and the toner flow at the edge E1 of the patch image P51B are opposite to each other. Become. Specifically, as shown by the right-pointing arrow in FIGS. 9 to 11, when the edge E1 of the patch image P51A is scraped off by the cleaning blade 2, the cleaning blade 2 of the edge E1 of the patch image P51A The portion of the toner scraped off by the toner is swept to the right in the direction D2 perpendicular to the traveling direction D1. On the other hand, as shown by the left-pointing arrow in FIG. 19, when the edge E1 of the patch image P51B was scraped by the cleaning blade 2, it was scraped by the cleaning blade 2 of the edge E1 of the patch image P51B. The portion of the toner is swept to the left in the direction D2 perpendicular to the traveling direction D1.

Therefore, by using both the patch images P51A and P51B, one side (right side) and the other side (left side) in the direction D2 perpendicular to the traveling direction D1 with respect to the aggregate M10 adhering to the cleaning blade 2 Toner collides from both sides. In other words, the direction of the toner colliding with the agglomerates M10 adhering to the cleaning blade 2 (the direction of the force acting on the agglomerates M10) is switched between the patch image P51A and the patch image P51B. As a result, even if the toner of the patch image P51A does not peel off the agglomerates M10 from the cleaning blade 2, the toner of the patch image P51B can peel off the agglomerates M10 from the cleaning blade 2. Therefore, the agglomerates M10 adhering to the cleaning blade 2 can be more reliably peeled off from the cleaning blade 2.

Further, in each of the above embodiments, the paper edge vicinity range A10 (for example, A3 size, A4 size, and postcard size) relating to all the paper sizes (for example, A3 size, A4 size, and postcard size) of the uncoated paper included in the plurality of printed papers (FIG. 7) is specified as the estimated existence range B1, but is not limited to this.

Here, as described above, the more often the paper and the intermediate transfer belt 21 come into direct contact (without the toner image) during the image forming operation on the paper (specifically, uncoated paper). , Paper dust is often transferred from the paper (uncoated paper) to the intermediate transfer belt 21, and agglomerates M10 are likely to be generated.

In consideration of this point, out of all the paper sizes of the uncoated paper included in the plurality of output papers, the uncoated paper is conveyed (output) more than a certain number (for example, 100 sheets) in total. The paper edge neighborhood range A10 with respect to the paper size of the above may be specified as the estimated existence range B1. In other words, of all the uncoated paper sizes (sizes of uncoated paper) included in the print history (Fig. 6), the total number of uncoated papers of the same size (cumulative output number) is a fixed number. The paper edge vicinity range A10 with respect to a larger number of uncoated paper sizes (in short, a non-coated paper size in which the cumulative number of passed sheets is larger than a certain number of sheets) may be specified as the estimated existence range B1.

In the example of FIG. 6, among all the paper sizes of the uncoated paper included in the plurality of output papers (here, A3 size, A4 size and postcard size), the total number of passed sheets of the A4 size uncoated paper. The total number of sheets (350 sheets) and the cumulative number of postcard-sized uncoated papers (6000 sheets) are larger than the fixed number (100 sheets). Further, among all the paper sizes of the uncoated paper included in the plurality of output papers, the cumulative number of passed sheets (50 sheets) of the A3 size uncoated paper is smaller than the fixed number (100 sheets). In this case, the paper edge neighborhood range A10 for the A3 size is not specified as the estimated existence range B1, and the paper edge neighborhood range A10 for the A4 size and the postcard size may be specified as the estimated existence range B1, respectively.

As described above, among all the paper sizes of the uncoated paper included in the plurality of output papers, the paper edge vicinity range A10 relating to the paper size of the uncoated paper in which the total number of passed sheets is larger than a certain number is estimated. It may be specified as the existence range B1.

According to this, a range in which the possibility that the agglomerates M10 are present is higher than a certain degree is specified from the range A10 near the edge of the paper for all the paper sizes of the uncoated paper contained in the plurality of output papers. To. In other words, the estimated existence range B1 is integrated from the paper edge vicinity range A10 for all the paper sizes (here, A3 size, A4 size and postcard size) of the uncoated paper included in the plurality of output papers. It is narrowed down to the range A10 near the edge of the paper regarding the paper size (here, A4 size and postcard size) of the uncoated paper that has been conveyed (output) more than a certain number of sheets. Therefore, as compared with the case where the paper edge neighborhood range A10 for all the paper sizes of the uncoated paper included in the plurality of output papers is specified as the estimated existence range B1, the agglomerates M10 are appropriately removed while being appropriately removed. It is possible to suppress the consumption of toner.

Further, among all the paper sizes of the uncoated paper included in the plurality of output papers, the paper edge vicinity range A10 relating to the paper size of the uncoated paper which is continuously conveyed (output) more than a certain number of sheets is , May be specified as the estimated existence range B1. In other words, of all the uncoated paper sizes included in the print history (Fig. 6), the number of continuously passed sheets (continuous output sheets) of uncoated paper of the same size is larger than a certain number of uncoated paper sizes. The paper edge vicinity range A10 with respect to (in short, the size of uncoated paper in which the number of continuously passed sheets is larger than a certain number of sheets) may be specified as the estimated existence range B1.

Here, when a certain number or more of "same size" uncoated paper is conveyed "continuously", the vicinity of both ends of the uncoated paper in the contact portion R10 between the cleaning blade 2 and the intermediate transfer belt 21. Aggregates M10 are likely to be formed in the range corresponding to. Conversely, even if the cumulative number of uncoated papers of the same size is a certain number or more, if the "continuous passing number" of the non-coated paper is not a certain number or more, the contact Aggregates M10 are unlikely to be formed in a range of the portion R10 corresponding to both ends of the uncoated paper.

In consideration of this point, among all the paper sizes of the uncoated paper included in the plurality of output papers, the range near the paper edge regarding the paper size of the uncoated paper in which the number of continuously passed sheets is larger than a certain number A10 However, it may be specified as the estimated existence range B1.

In the example of FIG. 6, among all the paper sizes of the uncoated paper included in the plurality of output papers (here, A3 size, A4 size and postcard size), the number of continuously passed sheets of the postcard size uncoated paper is , More than a certain number (for example, 100). In addition, among all the paper sizes of the uncoated paper included in the plurality of output papers, the number of continuously passed sheets of A3 size uncoated paper and the number of continuously passed sheets of A4 size uncoated paper are, respectively. Less than a certain number (100 sheets). In this case, the paper edge neighborhood range A10 for A3 size and the paper edge neighborhood range A10 for A4 size are not specified as the estimated existence range B1, respectively, and the paper edge neighborhood range A10 for the postcard size is specified as the estimated existence range B1. May be good.

According to this, from the range A10 near the edge of the paper for all the paper sizes of the uncoated paper contained in the plurality of output papers, a range in which the possibility that the agglomerates M10 are present is higher than a certain level is specified. Will be done. In other words, from the paper edge vicinity range A10 with respect to the paper size (here, A4 size and postcard size) of uncoated paper in which the estimated existence range B1 is "accumulated" and conveyed (output) more than a certain number of sheets. The range A10 near the edge of the paper with respect to the paper size (here, the postcard size) of the uncoated paper that has been conveyed (output) more than a certain number of sheets "continuously" is further narrowed down. Therefore, among all the paper sizes of the uncoated paper included in the plurality of output papers, the range A10 near the edge of the paper with respect to the paper size of the uncoated paper whose cumulative number of passed sheets is larger than a certain number is the estimated existence range B1. It is possible to further suppress toner consumption while more appropriately removing the agglomerates M10 as compared to the case specified as.

Further, in each of the above embodiments, the first specific operation (steps S21, S22 (FIG. 5)) for specifying the estimated existence range B1 using the first reference for both ends of the uncoated paper and the image formation rate. Both, but not limited to, the second specific operation (steps S23 to S25) for specifying the estimated existence range B1 by using the second reference with respect to. For example, the first specific operation may be performed without performing the second specific operation, and conversely, the second specific operation may be performed without performing the first specific operation.

1 Image forming device 2 Cleaning blade 8 Belt cleaning device 11 Photoreceptor 17 Photoreceptor cleaning device 21 Intermediate transfer belt 70 Lubricant application mechanism 71 Lubricant application brush 72 Lubricant block 73 Elastic member M10 Aggregate P50 Patch image

Claims (20)

It is an image forming device
An image carrier that temporarily supports a toner image and transfers it to paper,
A cleaning member that scrapes off residual toner remaining on the image carrier after transfer to the paper as it moves relative to the image carrier.
A control means for executing a maintenance operation for removing agglomerates generated between the image carrier and the cleaning member, and
With
The maintenance operation includes a patch forming operation of forming a patch image, which is a toner image for removing the agglomerates, on the image carrier, and the image supporting by advancing the image carrier toward the cleaning member. Including a moving motion of colliding the patch image on the body with the cleaning member.
An image forming apparatus characterized in that an edge of the patch image on the downstream side in the traveling direction of the patch image extends in a direction non-vertical to the traveling direction. In the image forming apparatus according to claim 1,
The control means
A determining means for determining whether or not to execute the patch forming operation based on the paper type information of a plurality of output sheets printed out.
An image forming apparatus comprising. In the image forming apparatus according to claim 2,
The paper type information includes information indicating whether each of the plurality of output papers is coated paper or uncoated paper.
The image forming apparatus is characterized in that the determination means determines that the patch forming operation is to be executed on the condition that the ratio of the uncoated paper to the entire plurality of output sheets is larger than the reference value. In the image forming apparatus according to claim 3,
A photoconductor that transfers a toner image onto the image carrier,
With more
The image forming apparatus, characterized in that the reference value is changed according to the supply amount of the lubricant supplied to at least one surface of the image carrier and the photoconductor. In the image forming apparatus according to any one of claims 2 to 4.
The determination means is
Among the linear contact portions where the image carrier and the cleaning member are in mutual contact, an estimated existence range, which is a range in which the agglomerates are presumed to be present, is specified.
An image forming apparatus for determining that a patch image should be formed in a region corresponding to the estimated existence range on the image carrier. In the image forming apparatus according to claim 5,
The determining means is the traveling direction centered on each of the assumed passing positions on the image carrier at both ends of the uncoated paper included in the plurality of output papers in a direction perpendicular to the traveling direction. An image forming apparatus, characterized in that a range having a predetermined width in a direction perpendicular to is specified as the estimated existence range. In the image forming apparatus according to claim 5,
The determination means is
The image carrier is divided into a plurality of division ranges in a direction perpendicular to the traveling direction, and the image carrier is divided into a plurality of division ranges.
Among the plurality of division ranges, an image formation characterized in that a division range in which the image formation rate in the image formation operation executed before the maintenance operation is smaller than a predetermined degree is specified as the estimated existence range. apparatus. In the image forming apparatus according to any one of claims 1 to 7.
An image forming apparatus, wherein the patch image is formed of a solid image made of toner. In the image forming apparatus according to claim 8,
The patch image is an image forming apparatus characterized in that a solid image made of two or more colors of toner is superimposed. In the image forming apparatus according to any one of claims 1 to 9.
In the patch forming operation, the first patch image and the second patch image are arranged in the traveling direction.
The edge on the downstream side in the traveling direction of the first patch image is cleaned so that one end of one side and the other side in the direction perpendicular to the traveling direction is earlier than the other end. It is tilted in the direction of collision with the member,
The edge on the downstream side in the traveling direction of the second patch image is such that the other end of the one side and the other side collides with the cleaning member before the one end. An image forming apparatus characterized by being tilted. An image carrier that temporarily supports a toner image and transfers it to paper, and a cleaning member that scrapes off residual toner remaining on the image carrier after transfer to the paper as it moves relative to the image carrier. In a computer built into an image forming apparatus equipped with
a) A step of executing a patch forming operation of forming a patch image, which is a toner image for removing agglomerates generated between the image carrier and the cleaning member, on the image carrier.
b) A step of advancing the image carrier toward the cleaning member and performing a moving operation of causing the patch image on the image carrier to collide with the cleaning member.
It is a program to execute
A program characterized in that an edge of the patch image on the downstream side in the traveling direction of the patch image extends in a direction non-perpendicular to the traveling direction. In the program according to claim 11.
In step a),
a-1) A step of determining whether or not to execute the patch forming operation based on the paper type information of a plurality of output sheets printed out.
A program characterized by having. In the program according to claim 12,
The paper type information includes information indicating whether each of the plurality of output papers is coated paper or uncoated paper.
The step a-1) is characterized in that it is determined to execute the patch forming operation on condition that the ratio of the uncoated paper to the entire plurality of output papers is larger than the reference value. program. In the program of claim 13,
The image forming apparatus
A photoconductor that transfers a toner image onto the image carrier,
With more
The program is characterized in that the reference value is changed according to the supply amount of a lubricant supplied to at least one surface of the image carrier and the photoconductor. In the program according to any one of claims 12 to 14.
c) A step of specifying an estimated existence range, which is a range in which the agglomerates are estimated to be present, in a linear contact portion where the image carrier and the cleaning member are in mutual contact.
d) A step of determining that the patch image should be formed in a region corresponding to the estimated existence range on the image carrier, and
A program characterized by causing the computer to further execute. In the program of claim 15.
In the step c), the both ends of the uncoated paper included in the plurality of output papers and both ends in the direction perpendicular to the traveling direction are centered on the assumed passing positions on the image carrier. A program characterized in that a range having a predetermined width in a direction perpendicular to the traveling direction is specified as the estimated existence range. In the program of claim 15.
In step c),
c-1) A step of dividing the image carrier into a plurality of division ranges in a direction perpendicular to the traveling direction, and
c-2) Among the plurality of division ranges, a division range in which the image formation rate in the image formation operation executed before step a) is smaller than a predetermined degree is specified as the estimated existence range. ,
A program characterized by having. In the program according to any one of claims 11 to 17.
The patch image is a program characterized in that it is formed as a solid image with toner. In the program of claim 18.
The patch image is a program characterized in that a solid image of two or more colors of toner is superimposed and formed. In the program according to any one of claims 11 to 19.
In the patch forming operation, the first patch image and the second patch image are arranged in the traveling direction.
The edge on the downstream side in the traveling direction of the first patch image is cleaned so that the end of the one side of the one side and the other side in the direction perpendicular to the traveling direction is prior to the other end. It is tilted in the direction of collision with the member,
The edge on the downstream side in the traveling direction of the second patch image is such that the other end of the one side and the other side collides with the cleaning member before the one end. A program characterized by being tilted.

Images