Imaging forming device and program

Abstract

To suppress generation of image quality failure.SOLUTION: An image forming device includes, as an image forming unit 30 that attaches a developer onto a surface of an image carrier to form an image and transcribes the image to a recording medium, one image forming unit that forms an image of a developer of one color on the surface of one image carrier, and another image forming unit that is located downstream of the one image forming unit, forms an image of a developer of another color on a surface 31a of another image carrier 31 and includes a contact member 65 of which the tip part 65a is in contact with the surface 31a after transcription of another image carrier 31. The image forming device performs, at a predetermined frequency, an operation of attaching the developer of another color to the surface 31a of another image carrier 31 to form a predetermined image 66 and passing the image between the surface 31a after transcription and the tip part 65a of the contact member 65.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and a program. [Background technology]

[0002] For example, Patent Document 1 discloses a configuration including a maintenance means for forming a maintenance image on an image carrier using image-forming charged particles by using an image-forming means, and rotating the image carrier without performing a transfer operation by a transfer means to pass the maintenance image against a blocking member periodically or irregularly, wherein the maintenance image used by the maintenance means has a plurality of belt-shaped images extending continuously or discontinuously along a cross direction intersecting the rotational direction of the image carrier, and the belt-shaped images have an uneven pattern in which a plurality of convex portions are arranged at intervals with respect to the rotational direction of the image carrier at any point in the cross direction of the image carrier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-78787 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, consider a case where a plurality of image forming units that deposit developer on the surface of an image carrier to form an image and transfer the image to a recording medium are provided in one direction. In the case where such image forming units include one image forming unit that forms an image of developer of one color, and another image forming unit that is located downstream of the first image forming unit and forms an image of developer of another color on the surface of another image carrier and includes a contact member whose tip portion comes into contact with the surface of the other image carrier after transfer, if the developer of one color accumulates on the tip portion of the contact member to form a lump, the lump may fall onto the recording medium, causing poor image quality. The object of the present invention is to suppress the occurrence of poor image quality compared to a case in which, in another image forming unit located downstream of one image forming unit which forms an image of developer of one color and which has another image carrier which forms an image of developer of another color, the accumulation of developer of one color on the tip of a contact member which contacts the surface of the other image carrier after transfer and the generation of lumps is not prevented. [Means for solving the problem]

[0005] The invention described in claim 1 is an image forming apparatus having a plurality of image forming units in one direction that form an image by adhering a developer to the surface of an image carrier and transfer the image to a recording medium, the image forming units including one image forming unit that forms an image of a developer of one color on the surface of one image carrier, and another image forming unit that is located downstream of the first image forming unit and forms an image of a developer of another color on the surface of another image carrier and includes a contact member whose tip end contacts the surface of the other image carrier after transfer, the image forming apparatus performing an operation of adhering the developer of the other color to the surface of the other image carrier to form a predetermined image, and passing the image of the surface between the surface after transfer and the tip end of the contact member at a predetermined frequency. The invention described in claim 2 is the image forming apparatus described in claim 1, characterized in that the other image forming units are a plurality of other image forming units that form images of each of the developers of YMCK colors as images of the developers of the other colors. The invention described in claim 3 is the image forming apparatus described in claim 2, characterized in that the predetermined frequency is set for each of the other image forming units. The invention described in claim 4 is the image forming apparatus described in claim 3, characterized in that the predetermined frequency becomes lower toward the downstream side in the plurality of other image forming units. The invention described in claim 5 is the image forming apparatus described in claim 3, characterized in that the predetermined frequency is set based on information indicating the amount of developer used of one color. The invention described in claim 6 is the image forming apparatus described in claim 1, characterized in that the predetermined image includes developer portions extending in the axial direction of the other image carrier and non-developer portions provided between the developer portions that are separated in a direction intersecting the axial direction. The invention described in claim 7 is the image forming apparatus described in claim 6, characterized in that the number of developer portions decreases toward the downstream side when the other image forming units are multiple image forming units. An eighth aspect of the present invention is the image forming apparatus according to the first aspect, wherein the one image forming unit does not form the predetermined image. The invention described in claim 9 is an image forming apparatus having a plurality of image forming units in one direction that form an image by adhering a developer to the surface of an image carrier and transfer the image to a recording medium, wherein the image forming units include one image forming unit that forms an image of a developer of one color on the surface of one image carrier, and another image forming unit that is located downstream of the first image forming unit and forms an image of a developer of another color on the surface of the other image carrier and includes a contact member whose tip end contacts the surface of the other image carrier after transfer. The program enables a processor that controls the image forming apparatus to realize the following functions: acquiring the number of times that an image of a developer of one color has been formed by the first image forming unit; and, if the acquired number of times satisfies a predetermined condition, performing an operation of adhering the developer of the other color to the surface of the other image carrier to form a predetermined image, and passing the image on the surface between the tip end of the contact member. Effect of the Invention

[0006] According to the invention of claim 1, in another image forming unit located downstream of one image forming unit that forms an image of developer of one color and that has another image carrier that forms an image of developer of another color, the occurrence of poor image quality can be suppressed compared to a case in which the developer of one color is not prevented from accumulating and generating lumps on the tip of the contact member that contacts the surface of the other image carrier after transfer. According to the invention of claim 2, the occurrence of poor image quality can be suppressed compared to a case in which the other image forming units are not provided with the configuration that the other image forming units are multiple other image forming units that form images of each of the YMCK colors of developers as images of the other colors of developers. According to the invention of claim 3, the occurrence of poor image quality can be suppressed, compared to a case where a configuration is not provided in which a predetermined frequency is set for each of the plurality of other image forming units. According to the invention of claim 4, the consumption of developers of other colors can be reduced compared to a case in which the predetermined frequency is not configured to be lower toward the downstream side among the multiple other image forming units. According to the invention of claim 5, the occurrence of poor image quality can be suppressed compared to a case where the predetermined frequency is not set based on information indicating the amount of developer used of one color. According to the invention of claim 6, the occurrence of poor image quality can be suppressed compared to a case in which the predetermined image does not have a configuration including a developer portion extending in the axial direction of another image carrier and a non-developer portion provided between the developer portions spaced apart in a direction intersecting the axial direction. According to the invention of claim 7, the consumption of developers of other colors can be reduced compared to a case where the number of developer portions is not provided so as to decrease toward the downstream side when the other image forming unit is a plurality of image forming units. According to the invention of claim 8, the consumption amount of the developer of one color can be reduced in one image forming unit compared to a case where the one image forming unit does not have a configuration in which the one image forming unit does not form a predetermined image. According to the invention of claim 9, in another image forming unit located downstream of one image forming unit that forms an image of developer of one color and that has another image carrier that forms an image of developer of another color, the occurrence of poor image quality can be suppressed compared to a case in which the developer of one color is not prevented from accumulating and generating lumps on the tip of the contact member that contacts the surface of the other image carrier after transfer. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an image forming apparatus. [Diagram 2] FIG. 2 is a diagram illustrating a developing device of the image forming apparatus. [Diagram 3] FIG. 2 is a diagram illustrating the periphery of a photosensitive drum of the image forming apparatus. [Figure 4] FIG. 2 illustrates an example of the hardware configuration of a control unit of the image forming apparatus. [Diagram 5] FIG. 2 is a block diagram illustrating a functional configuration of a control unit. [Figure 6] FIG. 13 is a diagram showing an example of an image used in a collapsing operation. [Figure 7] FIG. 13 is a diagram illustrating a collapsing operation performed using an image. [Figure 8] 13 is a flowchart showing an example of a processing procedure for a collapsing operation. [Figure 9] 11 is a table showing examples of application of the breaking-up operation in each image forming unit, where (a) shows the frequency at which the breaking-up operation is performed, and (b) shows the number of bands in an image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an image forming apparatus 1. As shown in FIG. The image forming apparatus 1 according to this embodiment includes a paper feed unit 1A, a printing unit 1B, and a paper discharge unit 1C. The paper feed unit 1A includes a first paper storage section 11 to a fourth paper storage section 14 for storing paper P as an example of a recording medium. The paper feed unit 1A also has feed rolls 15-18 that correspond to the first paper storage section 11 to the fourth paper storage section 14, respectively, and feed the paper P stored in each paper storage section to a transport path connected to the printing unit 1B.

[0009] The printing unit 1B includes an image forming section 20 that forms an image on a sheet P. The printing unit 1B also includes a control section 21 that controls each section of the image forming apparatus 1. The printing unit 1B also includes an image processing section 22. The image processing section 22 performs image processing on image data transmitted from the image reading device 4 and the personal computer (PC) 5. The printing unit 1B is also provided with a UI (User Interface) 23, which is configured with a touch panel or the like and notifies the user of information and receives information input from the user.

[0010] Image forming section 20, as an example of an image forming means, is provided with six image forming units 30T, 30P, 30Y, 30M, 30C, and 30K (hereinafter, sometimes simply referred to as "image forming units 30") arranged in parallel at regular intervals. Each image forming unit 30 includes a photosensitive drum 31 on which an electrostatic latent image is formed while rotating in the direction of arrow A, a charging roll 32 which charges the surface of the photosensitive drum 31, a developing device 33 which develops the electrostatic latent image formed on the photosensitive drum 31, and a drum cleaner 34 which removes toner and the like from the surface of the photosensitive drum 31.

[0011] The image forming section 20 is also provided with a laser exposure device 26 that exposes the photoconductor drum 31 of each image forming unit 30 to laser light. The exposure of the photoconductor drum 31 by the laser exposure device 26 is not limited to using laser light. For example, a light source such as an LED (Light Emitting Diode) may be provided for each image forming unit 30, and the photoconductor drum 31 may be exposed using light emitted from the light source.

[0012] Each image forming unit 30 is configured similarly, except for the toner contained in the developer 33. The image forming units 30Y, 30M, 30C, and 30K form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Further, the image forming units 30T and 30P form toner images using toner corresponding to a corporate color, foaming toner for Braille, fluorescent color toner, toner for improving gloss, etc. In other words, the image forming units 30T and 30P form toner images using toner of a special color.

[0013] Here, the image forming units 30T and 30P are an example of one image forming unit that forms an image of one color developer on the surface of one image carrier, and the image forming units 30Y, 30M, 30C, and 30K are an example of another image forming unit that is located downstream of the one image forming unit and forms an image of another color developer on the surface of another image carrier. That is, the photoconductor drum 31 of the image forming units 30T and 30P is an example of one image carrier, and the developer of one color is the developer of the image forming units 30T and 30P. Also, the photoconductor drum 31 of the image forming units 30Y, 30M, 30C, and 30K is an example of another image carrier, and the developer of the other color is the developer of the image forming units 30Y, 30M, 30C, and 30K.

[0014] The image forming section 20 is also provided with an intermediate transfer belt 41 onto which the toner images of each color formed on the photosensitive drums 31 of the image forming units 30 are transferred. The image forming section 20 is also provided with a primary transfer roll 42 that transfers the respective color toner images of the respective image forming units 30 onto the intermediate transfer belt 41 at a primary transfer portion T1. The image forming unit 20 is also provided with a secondary transfer roll 40 that transfers the toner image transferred onto the intermediate transfer belt 41 onto the paper P at a secondary transfer portion T2. Furthermore, the image forming section 20 is provided with a belt cleaner 45 that removes toner and the like from the surface of the intermediate transfer belt 41, and a fixing device 80 that fixes the secondarily transferred image onto the paper P.

[0015] The image forming unit 20 performs an image forming operation based on a control signal from the control unit 21 . Specifically, in the image forming unit 20, first, image processing is performed on the image data input from the image reading device 4 or the PC 5 by the image processing unit 22, and the image data after image processing is supplied to the laser exposure device 26. Then, for example, in a magenta (M) image forming unit 30M, the surface of the photosensitive drum 31 is charged by the charging roll 32, and then the laser exposure device 26 irradiates the photosensitive drum 31 with laser light modulated by image data obtained from the image processing unit 22.

[0016] As a result, an electrostatic latent image is formed on the photoconductor drum 31 . The formed electrostatic latent image is developed by the developing unit 33, and a magenta toner image is formed on the photosensitive drum 31. Similarly, yellow, cyan and black toner images are formed in the image forming units 30Y, 30C and 30K, and special color toner images are formed in the image forming units 30T and 30P.

[0017] The respective color toner images formed in each image forming unit 30 are electrostatically transferred sequentially by a primary transfer roll 42 onto an intermediate transfer belt 41 rotating in the direction of arrow C in Figure 1, and superimposed toner images are formed on the intermediate transfer belt 41. The superimposed toner image formed on the intermediate transfer belt 41 is transported to a secondary transfer portion T2 constituted by a secondary transfer roll 40 and a backup roll 49 as the intermediate transfer belt 41 moves.

[0018] On the other hand, the paper P is taken out from the first paper storage unit 11 by, for example, the delivery roll 15, and then transported to the position of the registration roll 74 via the transport path. When the superimposed toner image is transported to the secondary transfer portion T2, a sheet of paper P is supplied from the registration roll 74 to the secondary transfer portion T2 in accordance with the transport timing. Then, in the secondary transfer portion T2, the superimposed toner images are electrostatically transferred onto the paper P all at once by the action of a transfer electric field formed between the secondary transfer roll 40 and the backup roll 49.

[0019] Thereafter, the paper P onto which the superimposed toner images have been electrostatically transferred is transported to a fixing device 80. In the fixing device 80, pressure and heat are applied to the paper P on which the unfixed toner image has been formed, and the toner image is fixed to the paper P. Then, the sheet P on which the fixing process has been performed passes through a curl correction section 81 provided in the sheet discharge unit 1C, and is then conveyed to a sheet stacking section (not shown).

[0020] FIG. 2 is a diagram for explaining the developing unit 33 of the image forming apparatus 1, and is a schematic front view of the developing unit 33 as viewed from the same direction as that shown in FIG. 2, the developing unit 33 includes a storage unit 331 that stores a developer (not shown) therein. The storage unit 331 is made of a resin storage case 332. The developer is made of a magnetic carrier and a colored toner, and is a so-called two-component developer. The housing 332 of the developing device 33 is arranged to extend along a direction perpendicular to the paper surface of FIG. 2, which is the direction from the front side to the rear side of the image forming apparatus 1 (see FIG. 1), and has a front side member (not shown) on the front side and a rear side member (not shown) on the rear side.

[0021] An opening 333 is provided in the housing 332 at a location facing the photoconductor drum 31 (see FIG. 1). A developing roll 334 that adheres a developer to the surface of the photoconductor drum 31 is provided in this opening 333. The developing roll 334 holds the developer to be supplied to the photoconductor drum 31. The position where the developer from the developing roll 334 is supplied to the photoconductor drum 31 is sometimes referred to as the developing position. The developing roll 334 is formed in a cylindrical shape and is arranged so as to extend along a direction from the front side to the rear side of the image forming apparatus 1. In addition, the developing roll 334 is arranged so as to extend along the longitudinal direction of the developing unit 33.

[0022] The developing roll 334 is provided with a developing sleeve 334G formed of a cylindrical body and rotated, and a magnet roll 334H disposed inside the developing sleeve 334G. The developing sleeve 334G is made of, for example, a metal such as SUS, etc. The developing sleeve 334G rotates in the direction of the arrow D in the figure.

[0023] Furthermore, in this embodiment, at the primary transfer portion T1 (see FIG. 1) between the developing roll 334 and the photosensitive drum 31, the developing sleeve 334G and the photosensitive drum 31 rotate so that they move in the same direction. The developing unit 33 is provided with a layer regulating member 335 that regulates the layer thickness of the developer held on the developing roll 334 .

[0024] 2, the developing device 33 is provided with a first conveying section 336, a second conveying section 337, and a third conveying section 338 that convey the developer. Hereinafter, the first conveying section 336, the second conveying section 337, and the third conveying section 338 may be referred to as conveying sections 336-338.

[0025] The transport sections 336 to 338 are provided on the opposite side of the developing roll 334 to the side on which the photosensitive drum 31 (see FIG. 1) is installed. Each of the transport sections 336 to 338 includes a rotating member 51, 52, 53 extending along the rotation axis of the developing sleeve 334G that is driven to rotate, and rotates around the rotating member 51 to 53. That is, the transport sections 336 to 338 are disposed approximately parallel to the photosensitive drum 31 (see FIG. 1).

[0026] Next, the rotation speeds of the developing roll 334 and the rotating members 51-53 of each developing device 33 will be described in the cases where a special color toner image is formed and where it is not formed by the image forming unit 30. The rotation speeds of the rotating members 51-53 are sometimes referred to as the speeds of the transport sections 336-338. A first embodiment and a second embodiment will be described below.

[0027] 3 is a diagram illustrating the photoconductor drum 31 and its surroundings of the image forming apparatus 1. Each of the image forming units 30 has the photoconductor drum 31 shown in FIG.

[0028] Around the photosensitive drum 31, the charging roll 32, the developing roll 334, the primary transfer roll 42, and the drum cleaner 34 are arranged in the direction of the arrow A. The drum cleaner 34 will be described in more detail below.

[0029] The drum cleaner 34 cleans the surface 31a of the photoconductor drum 31 downstream of the primary transfer portion T1 in the direction of the arrow A, and removes toner and other substances remaining on the surface 31a after transfer. The drum cleaner 34 also collects the removed substances.

[0030] The drum cleaner 34 includes a main body 61 , a blade 62 , a partition member 63 , a conveying member 64 , and a contact member 65 . The body 61 holds components such as a blade 62 .

[0031] Blade 62 is attached to body 61 so as to be inclined in the direction opposite to the direction of arrow A with respect to surface 31a of photosensitive drum 31, and cleans surface 31a with the tip in contact with surface 31a. The partition member 63 is positioned between the main body 61 and the surface 31 a of the photosensitive drum 31 , and forms a space S for accommodating the material removed by the blade 62 . The transport member 64 is disposed in the space S and extends along the rotation axis of the photoconductor drum 31. The transport member 64 transports the removed matter by rotating, whereby the removed matter is collected.

[0032] The contact member 65 is positioned so as to cover the gap between the main body 61 and the partition member 63, and forms a space S together with the partition member 63. More specifically, the contact member 65 is disposed from the main body 61 toward the surface 31 a of the photosensitive drum 31 .

[0033] To explain further, one end of contact member 65 is attached to main body 61 so as to be inclined in the direction of arrow A, and the other end, tip portion 65a, contacts surface 31a, and a part of it deforms, for example, to conform to surface 31a.

[0034] More specifically, a distinction is made between toner, etc. that passes between the tip 65a of the contact member 65 and the surface 31a of the photosensitive drum 31 and toner, etc. that does not pass between the tip 65a and the surface 31a of the photosensitive drum 31. That is, for each image forming unit 30, the degree of deformation due to the material, thickness, etc. of the contact member 65, or the gap between the tip 65a and the surface 31a, etc. are set according to conditions such as the size of the toner supplied from the developing roll 334 to the photosensitive drum 31. As a result, the toner and the like of the photosensitive drum 31 remaining on the surface 31a after the transfer passes between the surface 31a and the tip 65a of the contact member 65 and moves to the position of the blade 62. On the other hand, the movement of the removed matter contained in the space S to the outside of the main body 61 is restricted. The contact member 65 of this embodiment may be, for example, a soft resin film.

[0035] In this embodiment, among the image forming units provided in the direction of the arrow C (see FIG. 1) of the intermediate transfer belt 41, i.e., in one direction, the image forming units 30T and 30P using special color toners are arranged on the upstream side (see FIG. 1). Also, image forming units 30Y, 30M, 30C, and 30K using any of the YMCK colors are arranged on the downstream side of the image forming units 30T and 30P (see FIG. 1). This is to meet the need that, for example, when considering the background when a transparent recording medium such as a cel picture is viewed from the back, it is preferable to form an image using a special color toner on the most upstream side.

[0036] Also, the particle size of the special color toner is larger than that of the YMCK color toners. Therefore, in the image forming units 30T and 30P, the toner having a larger particle size passes between the surface 31a of the photoconductor drum 31 and the tip 65a of the contact member 65 and can be accommodated in the space S. On the other hand, in the image forming units 30Y, 30M, 30C, and 30K, the toner having a smaller particle size passes between the surface 31a and the tip 65a and can be accommodated in the space S, but the toner having a larger particle size does not pass between the surface 31a and the tip 65a.

[0037] Therefore, in image forming units 30Y, 30M, 30C, and 30K, when the special color toner of image forming units 30T and 30P from the upstream side adheres to surface 31a of photosensitive drum 31 via intermediate transfer belt 41, there is a risk that the toner will not pass between surface 31a and tip end 65a and will instead accumulate on tip end 65a.

[0038] While the YMCK color toners are nearly spherical, the special color toners are irregular in shape compared to the YMCK color toners, and therefore tend to grow large and form lumps after accumulating at the tip 65a. If the lumps become large, they are more likely to fall from the tip 65a under their own weight, and if they fall onto the intermediate transfer belt 41, for example, this can cause poor image quality.

[0039] Therefore, in this embodiment, in order to prevent the special color toner accumulated on the contact member 65 from forming a lump, a control is adopted in which a breaking-up operation is performed to break up the special color toner accumulated on the contact member 65. Note that this breaking-up operation is performed to remove the special color toner from the tip portion 65a, and may be performed in a state where the special color toner is attached to the contact member 65, i.e., before the special color toner accumulates. The collapsing operation will be specifically described below. The collapsing operation is an example of an operation in which the image on the front side is passed between the front side after transfer and the tip of the contact member.

[0040] 4 is a diagram showing an example of the hardware configuration of the control unit 21 of the image forming apparatus 1. The control unit 21 provided in the image forming apparatus 1 is realized by a computer. The control unit 21 includes an arithmetic processing unit 21a that executes digital arithmetic processing according to a program, and a secondary storage unit 21g that stores information. The secondary storage unit 21g is realized by an existing information storage device such as an HDD (Hard Disk Drive), a semiconductor memory, or a magnetic tape.

[0041] The arithmetic processing unit 21a is provided with a CPU 21b as an example of a processor. The arithmetic processing unit 21a is also provided with a RAM 21c used as a working memory for the CPU 21b, and a ROM 21d in which programs executed by the CPU 21b are stored. The arithmetic processing unit 21a is also provided with a non-volatile memory 21e that is rewritable and can retain data even if the power supply is interrupted, and an interface unit 21f that controls each unit, such as a communication unit, connected to the arithmetic processing unit 21a.

[0042] The non-volatile memory 21e is composed of, for example, a battery-backed SRAM, a flash memory, etc. The secondary storage unit 21g stores files and the like, as well as programs executed by the arithmetic processing unit 21a. In this embodiment, the arithmetic processing unit 21a reads programs stored in the ROM 21d or the secondary storage unit 21g, thereby executing each process.

[0043] The program executed by the CPU 21b may be provided to the image forming apparatus 1 in a state where it is stored in a computer-readable recording medium such as a magnetic recording medium (such as a magnetic tape or a magnetic disk), an optical recording medium (such as an optical disk), a magneto-optical recording medium, or a semiconductor memory. The program executed by the CPU 21b may also be provided to the image forming apparatus 1 using a communication means such as the Internet.

[0044] In this specification, the term "processor" refers to a processor in a broad sense, including general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.). In addition, the operations of the processor may not only be performed by one processor, but may be performed by multiple processors in physically separate locations working together. The order of the operations of the processor is not limited to the order described in this embodiment, and may be changed.

[0045] FIG. 5 is a block diagram illustrating the functional configuration of the control unit 21. As shown in FIG. 5, the control unit 21 includes a count information acquisition unit 91, a breaking motion execution determination unit 92, an execution content determination unit 93, and a breaking motion control unit 94. The count information acquisition unit 91 and the like are realized by the CPU 21b (see FIG. 4).

[0046] The count information acquiring unit 91 acquires count information which is information indicating the number of times printing has been performed by the image forming units 30T, 30P using the special color toner. Such count information is the number of times printing has been performed after the collapsing operation has been performed. The count information acquiring unit 91 is an example of a function for acquiring the number of times an image of a developer of one color has been formed by one image forming unit.

[0047] The breaking-down operation execution determination unit 92 determines, based on the number information acquired by the number information acquisition unit 91, whether or not to execute the breaking-down operation in the image forming units 30Y, 30M, 30C, and 30K.

[0048] Such a breaking down operation is performed at a predetermined frequency, and therefore, whether or not the time to perform the breaking down operation has arrived is determined based on whether or not the acquired number information has reached a value corresponding to the predetermined frequency.

[0049] To explain further, the collapsing operation may be performed simultaneously in the image forming units 30Y, 30M, 30C, and 30K, or may be performed individually in the image forming units 30Y, 30M, 30C, and 30K. Therefore, in the former case, it is sufficient to judge one of the image forming units 30Y, 30M, 30C, and 30K, for example, the image forming unit 30Y. In the latter case, the judgment is made for each of the image forming units 30Y, 30M, 30C, and 30K.

[0050] When the breaking down operation execution determination unit 92 determines that the breaking down operation is to be executed, the execution content determination unit 93 determines the content to be executed as the breaking down operation. Such content may be the same for the image forming units 30Y, 30M, 30C, and 30K, or may be different for each of the image forming units 30Y, 30M, 30C, and 30K.

[0051] The breaking operation control unit 94 controls the breaking operation so that the content is as determined by the execution content determination unit 93. This control is to form a toner image according to the determined content on the surface 31a (see FIG. 3) of the photosensitive drum 31, and pass between the toner image and the tip end 65a (see FIG. 3) of the contact member 65 without being transferred to the intermediate transfer belt 41 (see FIG. 3) at the primary transfer unit T1 (see FIG. 3). The breaking operation control unit 94 is an example of a function that performs an operation.

[0052] 6 is a diagram showing an example of an image 66 used in the breaking down operation. The image 66 is a toner image according to the contents determined by the execution contents determination unit 93 (see FIG. 5) described above. 6, in an image 66, band-shaped portions 67a of a toner image extending in the width direction W of the photoconductor drum 31 are arranged along the direction of the arrow A. More specifically, the image 66 shown in FIG 6 includes a plurality of unit areas 67 each including the band-shaped portions 67a.

[0053] The unit area 67 includes strip portions 67a and blank areas 67b located between adjacent strip portions 67a. The strip portions 67a of the unit area 67 have a length of, for example, 2 mm in the direction of the arrow A, and the interval between the strip portions 67a is, for example, 2 mm. That is, in this case, the length of the margin portion 67b in the direction of the arrow A is 2 mm.

[0054] Here, image 66 is an example of a predetermined image. The width direction W of photoconductor drum 31 is an example of the axial direction of another image carrier, and the direction of arrow A is an example of a direction intersecting the axial direction. Moreover, strip-shaped portion 67a is an example of a developer portion, and marginal portion 67b is an example of a non-developer portion.

[0055] An example of the band-shaped portion 67a is, for example, 80% density, has a total length of 300 mm in the width direction W, and a length in the direction of the arrow A of 2 mm. Moreover, the image 66 may have a configuration in which, for example, 30 unit areas 67 are arranged in the direction of the arrow A. These densities, lengths in the width direction W, lengths in the direction of arrow A, and the number of unit areas 67 are merely examples, and other values ​​may be used. It is also possible to use different values ​​for each of the image forming units 30Y, 30M, 30C, and 30K.

[0056] FIG. 7 is a diagram for explaining the collapsing operation performed using the image 66. In FIG. 7, when an image 66 is formed on the surface 31a of the photoconductor drum 31, the transfer potential is controlled so that the image 66 is not transferred at the primary transfer portion T1. As a result, the image 66 on the surface 31a remains on the surface 31a even after passing through the primary transfer portion T1, and passes between the surface 31a and the tip portion 65a of the contact member 65.

[0057] More specifically, when the image 66 on the surface 31a passes between the tip 65a, the contact member 65 in contact with the repeated uneven shape of the image 66 vibrates. More specifically, when the strip 67a of the image 66 passes between the tip 65a, the distance between the surface 31a and the tip 65a widens, and when the strip 67a passes, the tip 65a tries to return to its original shape. This behavior of the tip 65a can occur in the same way when the next strip 67a passes, so the tip 65a behaves as many times as the number of strips 67a. This behavior can also extend to other parts of the tip 65a in the contact member 65. Therefore, by the above-mentioned action, the contact member 65 is vibrated and the special color toner on the contact member 65 is removed. In order to vibrate the entire width of the contact member 65, the image 66 is formed across the entire width.

[0058] Due to the vibration of the contact member 65, the special color toner present on the contact member 65 is separated from the contact member 65. In addition, the special color toner that has separated from the contact member 65 and landed on the surface 31a is more likely to be drawn into the space S because the vibration widens the gap between the surface 31a and the contact member 65. The image 66 on the surface 31a is removed by the blade 62, is stored in the space S, and is collected by the conveying member 64 together with the special color toner.

[0059] FIG. 8 is a flowchart illustrating an example of a processing procedure for the collapsing operation. In the example shown in FIG. 8, when the count information acquisition unit 91 (see FIG. 5) acquires count information (step 101), the breaking down operation execution judgment unit 92 (see the same figure) judges whether the acquired count information satisfies a predetermined execution condition (step 102).

[0060] The execution condition here is a condition for determining whether or not the time to perform the breaking action has arrived based on the number of times according to the acquired number of times information, and for example, it is possible to use information on a predetermined frequency, which will be described later. For example, if the predetermined frequency is "once in 200 times," the condition is whether or not the number of times according to the number of times information has reached 200 times.

[0061] To explain further, the execution conditions referred to here may be changed depending on the type of characteristic color toner possessed by image forming units 30T, 30P, for example, white, gold, silver, etc., or may be left the same regardless of the type of characteristic color toner possessed by image forming units 30T, 30P.

[0062] In addition, the execution conditions referred to here may be the same regardless of the amount of spot color toner used in the image forming units 30T and 30P, or may be changed according to the amount of spot color toner used. For example, the frequency may be changed using information indicating the image density, which is the amount of toner per unit area calculated for each print job. In other words, the frequency is increased when the image density is high, and decreased when the image density is low.

[0063] The information indicating the image density of the spot color can be acquired by the number information acquisition unit 91 (see FIG. 5) of the control unit 21, and is reflected in the judgment of the execution condition (see step 102 in FIG. 8). The information indicating the image density of the spot color is an example of information indicating the usage amount of developer of one color. In this embodiment, when there are multiple image forming units having special color toner, such as image forming units 30T and 30P, a sum of the usage amounts of the special color toners is calculated, and the execution conditions may be changed depending on this sum.

[0064] When the acquired number information satisfies the predetermined execution condition (Yes in step 102), the execution content determination unit 93 (see FIG. 5) determines the execution content of the breaking motion (step 103). If the predetermined execution condition is not satisfied (No in step 102), the process returns to step 101.

[0065] The execution content of the collapsing operation referred to here may be, for example, the number of band-like portions 67a (see FIG. 6) in the image 66. In addition, the execution contents may be different for each of the image forming units 30Y, 30M, 30C, and 30K, or the same for each of the image forming units 30Y, 30M, 30C, and 30K.

[0066] Thereafter, the breaking down operation control unit 94 (see FIG. 5) controls the breaking down operation according to the determined execution content. In this manner, the breaking down operation is performed periodically. Such control may involve inserting an image 66 (see FIG. 6) when the photoconductor drum 31 is rotating in response to a print job. That is, the timing of the collapsing operation may include, for example, forming an image 66 between a print image and the next print image, and forming an image 66 after forming the final image.

[0067] 9 is a table showing examples of application of the breaking down operation in each image forming unit 30, where (a) shows the frequency of performing the breaking down operation and (b) shows the number of band-like portions 67a in the image 66. The number of band-like portions 67a here can also be referred to as the number of unit areas 67 (see FIG. 6). The frequency shown in FIG. 9(a) is an example of a predetermined frequency, and the number of band-shaped portions 67a shown in (b) is an example of the number of developer portions.

[0068] 9(a) indicates how many sheets each of the image forming units 30Y, 30M, 30C, and 30K performs the breaking-up operation for, when printing is performed on paper P using spot color toner in the image forming units 30T and 30P. In this case, the size of the paper P to be printed on (see FIG. 1) is, for example, A4 size, and in the case of other sizes, it is considered to convert to A4 size.

[0069] In the first example of the frequency shown in Fig. 9(a), the image forming units 30Y, 30M, 30C, and 30K all perform the breaking operation at a frequency of "once in 200 sheets." That is, the image forming units 30Y, 30M, 30C, and 30K perform the breaking operation at the same frequency. In this case, "200 sheets" corresponds to a value corresponding to a predetermined frequency.

[0070] In the second example of frequency, focusing on the fact that the amount of special color toner decreases toward the downstream, the breaking up operation is performed at different frequencies, unlike the first example. That is, the frequency of image forming unit 30Y is "once in 200 sheets," the frequency of image forming unit 30M is "once in 300 sheets," the frequency of image forming unit 30C is "once in 400 sheets," and the frequency of image forming unit 30K is "once in 500 sheets." In this way, in the second example of frequency, the frequency is set to decrease toward the downstream for each of image forming units 30Y, 30M, 30C, and 30K.

[0071] More specifically, the image forming unit 30Y, which is closest to the image forming units 30T and 30P, is the most frequent, and the image forming unit 30K, which is farthest from the image forming units 30T and 30P, is the least frequent. The frequency is set according to the distance to the image forming units 30T and 30P. In other words, the frequency is set high for the image forming unit 30Y, which is closest to the image forming units 30T and 30P and receives the largest amount of special color toner. Also, the frequency is set low for the image forming unit 30K, which is farthest from the image forming units 30T and 30P and receives the smallest amount of special color toner.

[0072] In this way, the frequency decreases toward the downstream side in the direction of arrow C of intermediate transfer belt 41 (see FIG. 1). A high frequency results in a large amount of toner consumption, while a low frequency reduces the amount of toner consumption. Thus, in the second example, the consumption of MCK color toner is reduced compared to the first example, while preventing the special color toner accumulated on tip portion 65a (see FIG. 6) of contact member 65 from forming large clumps.

[0073] In the second example, for example, the control of the other image forming units 30M, 30C, and 30K in the case where only the image forming unit 30Y executes the collapsing operation will be described. In such a case, the image forming unit 30Y forms the above-mentioned image 66, while the other image forming units 30M, 30C, and 30K do not form the same image as the image 66 formed by the image forming unit 30Y. However, in order to prevent wear of the blade 62 (see FIG. 3) in the image forming units 30M, 30C, and 30K, it is possible to consider a control to form a number of images (for example, one) less than the number of strip-shaped portions 67a of the image 66 of the image forming unit 30Y.

[0074] The number of band-like portions 67a shown in Fig. 9(b) is the number of band-like portions 67a (see Fig. 6) included in the image 66. The more the number, the longer the time that the tip portion 65a (see Fig. 6) of the contact member 65 vibrates, and the more reliably the spot color toner is removed from the tip portion 65a.

[0075] In the first example shown in FIG. 9(b), the image forming units 30Y, 30M, 30C, and 30K all perform the collapsing operation on the image 66 having "30" strip-shaped portions 67a. On the other hand, in the second example, there are "30" band-shaped portions 67a in image forming unit 30Y, "25" in image forming unit 30M, "20" in image forming unit 30C, and "15" in image forming unit 30K.

[0076] In this way, the number of band-shaped portions 67a is set to decrease toward the downstream side in the direction of the arrow C of the intermediate transfer belt 41. Therefore, in the second example, the consumption amount of MCK color toner is suppressed compared to the first example, while the special color toner accumulated on the tip portion 65a (see FIG. 6) of the contact member 65 is prevented from forming a large lump.

[0077] In the example shown in FIG. 9, the collapsing operation is not performed in the image forming units 30T and 30P, but it is possible to perform the collapsing operation in the image forming units 30T and 30P as well.

[0078] In this embodiment, the image forming units 30Y, 30M, 30C, and 30K that form YMCK color images and the image forming units 30T and 30P that form special color images are provided, but this is not limited to this. For example, it is also possible to adopt a configuration that includes only some of the image forming units 30Y, 30M, 30C, and 30K that form YMCK color images, such as the image forming unit 30K. It is also possible to adopt a configuration that includes only one of the image forming units 30T and 30P.

[0079] <Additional Notes> (((1))) An image forming apparatus having a plurality of image forming units arranged in one direction, each of which forms an image by depositing a developer on a surface of an image carrier and transfers the image to a recording medium, the image forming apparatus comprising: one image forming unit which forms an image of a developer of one color on the surface of one image carrier; and another image forming unit which is located downstream of the one image forming unit, forms an image of a developer of another color on the surface of another image carrier, and includes a contact member whose tip portion comes into contact with the surface of the other image carrier after transfer; a developer of the other color is applied to the surface of the other image carrier to form a predetermined image, and the image on the surface is passed between the surface after transfer and the tip of the contact member at a predetermined frequency; Image forming device. (((2))) the other image forming units are a plurality of other image forming units which form images of each of the developers of Y, M, C and K colors as the images of the developers of the other colors; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (((3))) the predetermined frequency is set for each of the other image forming units; The image forming apparatus according to (((2))) is characterized in that (((4))) the predetermined frequency is lower toward the downstream side in the plurality of other image forming units; The image forming apparatus according to (((3))) is characterized in that (((5))) The predetermined frequency is set based on information indicating a usage amount of a developer of one color. The image forming apparatus according to (((3))) is characterized in that (((6))) the predetermined image includes developer portions extending in an axial direction of the other image carrier, and non-developer portions provided between the developer portions spaced apart in a direction intersecting the axial direction, 4. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: (((7))) the number of developer portions decreases toward the downstream side when the other image forming unit is a plurality of image forming units; The image forming apparatus according to (((6))) is characterized in that (((8))) the one image forming unit does not form the predetermined image; 4. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: (((9))) an image forming apparatus including a plurality of image forming units arranged in one direction, each of which forms an image of a developer of one color on the surface of an image carrier by depositing a developer on the surface of the image carrier and transfers the image to a recording medium, the image forming units including one image forming unit forming an image of a developer of one color on the surface of the image carrier, and another image forming unit located downstream of the one image forming unit forming an image of a developer of another color on the surface of another image carrier and including a contact member whose tip portion comes into contact with the surface of the other image carrier after transfer; a function of acquiring the number of times an image of one color is formed by the one image forming unit; and a function of performing an operation of forming a predetermined image by depositing the developer of the other color on the surface of the other image carrier and passing the image on the surface between the tip portion of the contact member when the acquired number of times satisfies a predetermined condition; A program to achieve this.

[0080] According to the invention (((1))), in another image forming unit which is located downstream of one image forming unit which forms an image of developer of one color and which has another image carrier which forms an image of developer of another color, the occurrence of poor image quality can be suppressed compared to a case in which the developer of one color is not prevented from accumulating on the tip of the contact member which comes into contact with the surface of the other image carrier after transfer and generating a lump. According to the invention (((2))), the occurrence of poor image quality can be suppressed compared to a case in which the other image forming unit is not provided with a configuration in which the other image forming unit is a plurality of other image forming units that form images of each of the YMCK colors of developer as images of the other colors of developer. According to the invention (((3))), the occurrence of poor image quality can be suppressed compared to a case where a configuration is not provided in which a predetermined frequency is set for each of the multiple other image forming units. According to the invention (((4))), the consumption of developers of other colors can be reduced compared to a case in which the predetermined frequency is not configured to be lower toward the downstream side in the multiple other image forming units. According to the invention (((5))), the occurrence of poor image quality can be suppressed compared to a case in which the predetermined frequency is set based on information indicating the amount of developer used of one color. According to the invention (((6))), the occurrence of poor image quality can be suppressed compared to a case in which the predetermined image does not include a configuration including developer portions extending in the axial direction of other image carriers and non-developer portions provided between the developer portions spaced apart in a direction intersecting the axial direction. According to the invention (((7))), the consumption of developers of other colors can be reduced compared to a case where the number of developer portions is not reduced downstream when the other image forming unit is a plurality of image forming units. According to the invention (((8))), the consumption amount of developer of one color can be reduced compared to a case where one image forming unit does not have a configuration in which it does not form a predetermined image. According to the invention (((9))), in another image forming unit which is located downstream of one image forming unit which forms an image of developer of one color and which has another image carrier which forms an image of developer of another color, the occurrence of poor image quality can be suppressed compared to a case in which the developer of one color does not accumulate on the tip of the contact member which comes into contact with the surface of the other image carrier after transfer and a mass is generated. [Explanation of symbols]

[0081] 1... image forming apparatus, 21b... CPU, 30T, 30P, 30Y, 30M, 30C, 30K... image forming units, 31... photosensitive drum, 31a... surface, 65... contact member, 65a... leading end portion, 66... ​​image, 67a... belt-shaped portion, 67b... margin portion, 91... number of times information acquisition portion, 94... breaking operation control portion

Claims

1. An image forming apparatus having a plurality of image forming units arranged in one direction, each of which forms an image by depositing a developer on a surface of an image carrier and transfers the image to a recording medium, the image forming apparatus comprising: one image forming unit which forms an image of a developer of one color on the surface of one image carrier; and another image forming unit which is located downstream of the one image forming unit and forms an image of a developer of another color on the surface of another image carrier, the another image forming unit including a contact member whose tip portion comes into contact with the surface of the other image carrier after transfer, a developer of the other color is applied to the surface of the other image carrier to form a predetermined image, and the image on the surface is passed between the surface after transfer and the tip of the contact member at a predetermined frequency; Image forming device.

2. the other image forming units are a plurality of other image forming units which form images of each of the developers of Y, M, C, and K colors as the images of the developers of the other colors; 2. The image forming apparatus according to claim 1,

3. the predetermined frequency is set for each of the other image forming units; 3. The image forming apparatus according to claim 2,

4. the predetermined frequency is lower toward the downstream side in the plurality of other image forming units; 4. The image forming apparatus according to claim 3.

5. The predetermined frequency is set based on information indicating a usage amount of a developer of one color.

4. The image forming apparatus according to claim 3.

6. the predetermined image includes developer portions extending in an axial direction of the other image carrier, and non-developer portions provided between the developer portions spaced apart in a direction intersecting the axial direction, 2. The image forming apparatus according to claim 1,

7. the number of developer portions decreases toward the downstream side when the other image forming unit is a plurality of image forming units; 7. The image forming apparatus according to claim 6,

8. the one image forming unit does not form the predetermined image; 2. The image forming apparatus according to claim 1,

9. an image forming apparatus including a plurality of image forming units arranged in one direction, each of which forms an image of a developer of one color on the surface of an image carrier by depositing a developer on the surface of the image carrier and transfers the image to a recording medium, the image forming units including one image forming unit forming an image of a developer of one color on the surface of the image carrier, and another image forming unit located downstream of the one image forming unit forming an image of a developer of another color on the surface of another image carrier and including a contact member whose tip portion comes into contact with the surface of the other image carrier after transfer; a function of acquiring the number of times an image of one color is formed by the one image forming unit; and a function of performing an operation of forming a predetermined image by depositing the developer of the other color on the surface of the other image carrier and passing the image on the surface between the tip portion of the contact member when the acquired number of times satisfies a predetermined condition; A program to achieve this.

Images