Image forming system

Abstract

The image forming system includes: an image holding body that rotates; a charging unit that rotates while being in contact with the image holding body and charges the surface of the image holding body by applying a charging bias voltage; a pressing member that presses the charging portion against the image holding body so as to create a bite width; a developing unit that develops a latent image formed on the surface of the image holding body with a toner; and at least one processor that performs a process in which an absolute value of a surface potential of the image holding body charged by the charging portion is lower than an absolute value of a developing potential of the developing portion; the absolute value of the potential of the charging part is raised in a rectangular wave manner only during a set time during which the charging part instantly discharges before and after the nip width of the image holding body and does not discharge at the center of the nip width, and the absolute value of the potential of the charging part is raised in a rectangular wave manner only during a set time during which the charging part does not discharge at the center of the nip width. The absolute value of the surface potential of the image holding body is higher than the absolute value of the developing potential.

Description

Technical Field

[0001] This invention relates to an image forming system. Background Technology

[0002] Patent Document 1 discloses an image forming apparatus comprising a charged component, a latent image forming mechanism, a developing mechanism, and a light sensor. The charged component is disposed in contact with or close to a photoreceptor. The latent image forming mechanism forms an electrostatic latent image on the photoreceptor charged by the charged component. The developing mechanism develops the image by attaching toner to the electrostatic latent image. A voltage applying mechanism applies a voltage to the charged component. The light sensor detects the reflectance concentration of the surface of the photoreceptor. In this image forming apparatus, the voltage applied to the charged component can be changed, and the applied voltage output from the voltage applying mechanism can be changed according to the output ratio of the light sensor before and after the change. Furthermore, in this image forming apparatus, the light sensor is characterized by a structure in which the light sensor also functions as a toner concentration sensor, and the light sensor is positioned between the developing width end and the corresponding position of the toner concentration sensor in the longitudinal direction of the photoreceptor.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2002-268296 Summary of the Invention

[0004] The present invention provides an image forming system capable of inferring the engagement width of the charged part with the image holder.

[0005] The image forming system according to the first embodiment includes: an image holder that rotates; a charged part that rotates while in contact with the image holder and charges the surface of the image holder by applying a charged bias voltage; a pressing member that presses the charged part onto the image holder in a manner that creates an engagement width; a developing unit that develops a latent image formed on the surface of the image holder using a toner; and at least one processor that processes the image holder such that, while the absolute value of the surface potential of the image holder charged by the charged part is lower than the absolute value of the developing potential of the developing unit, the charged part discharges only at the moment before and after the engagement width of the image holder and does not discharge at the center of the engagement width for a set time, causing the absolute value of the potential of the charged part to rise in a rectangular wave, so that the absolute value of the surface potential of the image holder is higher than the absolute value of the developing potential.

[0006] In the image forming system described in the first embodiment, the charged part is a circular rotating body. When the diameter of the charged part is set to d [mm] and the rotational speed of the image holder is set to v [mm / sec], the setting time t [ms] is t = d / v × 2.92 ± 5%.

[0007] In the image forming system described in the first or second embodiment, the minimum value of the set time is the time until the desired potential of the charged part is reached, and the maximum value of the set time is less than or equal to the time during which no undischarged area remains on the engagement width.

[0008] In the image forming system described in any of the first to third embodiments, the processor performs the following processing: predicting the engagement width of the charged part with the image holder based on a measured value obtained by directly or indirectly measuring the width of the position of the blur toner during a state where the blur toner is less in the rotational direction of the image holder.

[0009] The image forming system of the fifth embodiment is the same as that of the fourth embodiment, and includes: an intermediate transfer body for transferring toner onto the surface of the image holder; and a concentration detection unit for detecting the concentration of toner transferred to the intermediate transfer body.

[0010] The image forming system of the sixth embodiment is in the same system as the image forming system of the fourth embodiment, and has a detection unit that detects the concentration of toner on the surface of the image holder.

[0011] In the image forming system described in the 7th embodiment, as described in the 5th or 6th embodiment, the concentration of the toner is measured only at a position corresponding to the end of the image holder along its axial direction.

[0012] In the image forming system described in the fourth embodiment, the processor performs the following processing: when the engagement width of the charged part corresponding to the measured value is above a threshold, a cleaning mode for cleaning the charged part is implemented.

[0013] In the image forming system described in the 8th embodiment, the processor performs the following processing: based on the engagement width of the charged part corresponding to the measured value, the frequency of the cleaning mode for cleaning the charged part is increased.

[0014] The image forming system of the 10th embodiment, in the image forming system of the 8th embodiment, includes a cleaning member on the downstream side of the transfer position where the toner image of the surface of the image holder is transferred to the medium and upstream of the charged part, for cleaning the surface of the image holder. In the cleaning mode, dirt from the charged part is transferred to the image holder, and the dirt from the image holder is removed by the cleaning member.

[0015] The image forming system involved in the 11th embodiment, in the image forming system described in the 4th embodiment, wherein the processor performs the following processing: when the engagement width of the charged part corresponding to the measured value is above a threshold, the absolute value of the potential of the charged part that keeps the image body charged during image forming is increased compared to the absolute value of the potential of the normally charged part.

[0016] The image forming system involved in the 12th embodiment is obtained by reducing the absolute value of the potential of the charged part without changing the development potential of the developing part in the image forming system described in any one of the 1st to 11th embodiments.

[0017] In the image forming system described in any of the 1st to 12th embodiments, the charged part makes the image holding body charged by adding an AC voltage to a DC voltage.

[0018] Invention Effects

[0019] Based on the image forming system involved in the first scheme, the engagement width of the charged part with the image holder can be inferred.

[0020] According to the image forming system involved in the second scheme, compared with the case where time t is longer than d / v×2.92+5% or shorter than d / v×2.92-5%, it is possible to form the position of the blurring toner corresponding to the engagement width of the charged part during a state where there is less blurring toner in the rotation direction of the image holder.

[0021] According to the image forming system of the third scheme, by increasing the absolute value of the potential of the charged part only for a set time, it is possible to form the position of the blurring toner opposite to the engagement width of the charged part during a period when the blurring toner is less in the rotation direction of the image holder.

[0022] According to the image forming system involved in the fourth scheme, the engagement width of the charged part with the image holder can be inferred from the measured value of the width of the position of the blurring toner.

[0023] According to the image forming system involved in the fifth scheme, by detecting the concentration of the toner transferred to the intermediate transfer body by the concentration detection unit, the width of the blur toner during the period when the blur toner is low can be determined.

[0024] According to the image forming system of the sixth scheme, by directly detecting the concentration of the toner on the surface of the image holder by the detection unit, the width of the blur toner during the period of low blur toner concentration can be determined.

[0025] According to the image forming system involved in the seventh scheme, compared with the case where the concentration of the toner is measured along the entire axis of the image holder, it is easier to measure the width of the blur toner in the rotational direction of the image holder.

[0026] According to the image forming system involved in the eighth scheme, compared with the case where the engagement width of the charged part with the image holder is unknown, it is possible to suppress the occurrence of poor charging of the image holder caused by the charged part.

[0027] According to the image forming system involved in the 9th scheme, compared with the case where a cleaning mode is performed every time the width of the blur toner is measured, the occurrence of poor charging of the image holder caused by the charged part can be suppressed.

[0028] According to the image forming system of the 10th embodiment, dirt on the charged parts can be removed using the cleaning component of the image holder.

[0029] According to the image forming system of the 11th scheme, compared with the case where the potential of the charged part is constant during image forming, the occurrence of poor charging of the image holder caused by the charged part can be suppressed.

[0030] According to the image forming system involved in the 12th scheme, the cost of the output substrate of the developing section can be suppressed compared with the case of changing the developing potential of the developing section.

[0031] According to the image forming system involved in Scheme 13, the surface potential of the image holder is stable compared to the case where only a DC voltage is used to charge the surface of the image holder. Attached Figure Description

[0032] The embodiments of the present invention will be described in detail with reference to the following figures.

[0033] Figure 1 This is a schematic structural diagram illustrating the image forming system according to the first embodiment;

[0034] Figure 2 This is a side view showing the area near the charged roller and photoreceptor of the image forming system according to the first embodiment;

[0035] Figure 3 This is a cross-sectional view showing the engagement width of the charged roller with the photoreceptor in the image forming system according to the first embodiment;

[0036] Figure 4 It is a graph showing the relationship between the axial position of the charged roller and the engagement width;

[0037] Figure 5It is a graph showing the relationship between the engagement width of the charged roller with the photoreceptor and the amount of additives attached to the charged roller;

[0038] Figure 6 This is a block diagram illustrating the hardware structure of the image forming system according to the first embodiment;

[0039] Figure 7 This is an explanatory diagram showing the outputs of the potential, developer, and concentration sensors at various points relative to the time when the contact width between the charged roller and the photoreceptor is detected.

[0040] Figure 8 This is an explanatory diagram showing the discharge state when the photoreceptor is charged by the charged roller;

[0041] Figure 9 In the diagram, (A) is an explanatory diagram showing the state of the charged roller, exposure device and primary transfer roller during normal image formation, and (B) is an explanatory diagram showing the state of the charged roller and photoreceptor during normal image formation.

[0042] Figure 10 In the diagram, (A) is an explanatory diagram showing the state of the charged roller, exposure device and primary transfer roller when cleaning the charged roller, and (B) is an explanatory diagram showing the state of the charged roller and photosensitive material when cleaning the charged roller.

[0043] Figure 11 This is a flowchart illustrating the information processing flow of the image forming system according to the first embodiment;

[0044] Figure 12 This is a schematic structural diagram showing the toning agent image forming unit of the image forming system according to the second embodiment. Detailed Implementation

[0045] The following describes a method for implementing the present invention. In this description, the direction indicated by arrow H in each figure is defined as the vertical direction and the height direction of the device, and the direction indicated by arrow W is defined as the horizontal direction and the width direction of the device. The direction orthogonal to the height direction and the width direction of the device in each figure (the direction of arrow D) is defined as the depth direction of the device.

[0046] [First Embodiment]

[0047] Figure 1 This is a front view showing the overall structure of the image forming system 10 according to the first embodiment. In the first embodiment, the overall structure of the image forming system 10 has been described first, and then the content related to the engagement width of the charged roller with the photoreceptor will be described.

[0048] <Overall Structure of Image Forming System>

[0049] like Figure 1 As shown, the image forming system 10 of the first embodiment is an electrophotographic apparatus comprising a toner image forming unit 20, a transfer device 30, a transport device 40, a fixing device 50, and a control unit 100. Hereinafter, in the description of the overall structure of the image forming system 10, unless otherwise specified, reference will be made to... Figure 1 Please provide an explanation.

[0050] [Toning agent image formation section]

[0051] The toning image forming unit 20 has the function of performing charging, exposure, and development processes to form toning images on photoreceptors 22Y, 22M, 22C, and 22K. The toning image forming unit 20 is composed of monochrome units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black. Furthermore, each monochrome unit 20Y, 20M, 20C, and 20K incorporates a photoreceptor 22Y, 22M, 22C, and 22K. The photoreceptors 22Y, 22M, 22C, and 22K are examples of image holding media. Additionally, from... Figure 1 When viewing the image forming system 10 from the front side, the monochrome units 20Y, 20M, 20C, and 20K are arranged in their described order, spanning from the right side across the left side (below the transfer belt 31) in the width direction of the device. Furthermore, as an example, the polarity of the average charge of the toner used in the first embodiment is set to negative.

[0052] In monochrome units 20Y, 20M, 20C, and 20K, all structural components are identical except for the color of the toner. Therefore, when it is not necessary to distinguish the color of the toner, the symbols Y, M, C, and K after each component are sometimes omitted in the description. Monochrome units 20Y, 20M, 20C, and 20K each have a charged roller 62, an exposure device 64, a developing machine 66, and a cleaning blade 68 around a photoreceptor 22 that rotates in the direction indicated by the arrow. The charged roller 62 is an example of a charged part. The charged roller 62 rotates while in contact with the photoreceptor 22, and charges the photoreceptor 22 by applying a charged bias voltage. The exposure device 64 exposes the photoreceptor 22 charged by the charged roller 62, forming a latent image on the photoreceptor 22. The developing machine 66 includes a developing roller 66A, which uses the toner to develop the latent image formed on the photoreceptor 22 by the exposure device 64. The cleaning blade 68 removes residual toner from the surface of the photoreceptor 22 after the toner image has been transferred to the transfer device 30. The developing machine 66 is an example of a developing section. The cleaning blade 68 is an example of a cleaning component.

[0053] The charged roller 62, for example, imparts a negative polarity to the surface (photosensitive layer) of the photoreceptor 22. On the negatively polarized surface of the photoreceptor 22, the portion exposed to exposure light by the exposure device 64 becomes positively polarized, thereby forming a latent image on the surface of the photoreceptor 22. Then, in the developing machine 66, a negatively polarized rubbed, charged toner adheres to the positively polarized latent image, thereby developing the latent image. Thus, a toner image is formed on the surface of the photoreceptor 22.

[0054] As an example, the charged roller 62 is a circular rotating body. The charged roller 62 rotates in tandem with the rotation of the photoreceptor 22. As an example, a bias voltage, which adds an AC voltage to a DC voltage, is applied to the charged roller 62. The charged roller 62 charges the photoreceptor 22 by adding an AC voltage to the DC voltage.

[0055] The cleaning scraper 68 is positioned downstream of the primary transfer position of the transfer belt 31 and upstream of the charged roller 62, where the toner image on the surface of the photoreceptor 22 is transferred to the transfer belt 31.

[0056] [Transfer Device]

[0057] The transfer apparatus 30 has the function of transferring the tonal images formed on each of the photoreceptors 22Y, 22M, 22C, and 22K onto the transfer belt 31 in a single step. Furthermore, the transfer apparatus 30 has the function of transferring the tonal images held on the transfer belt 31 a second time onto the medium P. The medium P is an example of a recording medium, such as paper.

[0058] like Figure 1 As shown, the transfer apparatus 30 includes a transfer belt 31, a drive roller 32, a plurality of primary transfer rollers 34, a driven roller 36, and a tension roller 37. Furthermore, the transfer apparatus 30 includes a secondary transfer roller 38, a concentration sensor 72, a support roller 74, and a cleaning scraper 76. Here, the transfer belt 31 is an example of an intermediate transfer body, and the concentration sensor 72 is an example of a concentration detection unit.

[0059] The transfer belt 31 is wound in a loop around a drive roller 32 that rotates around an axis, and is driven by the drive roller 32 to rotate in the circumferential direction (arrow A direction). That is, the transfer belt 31 has the function of holding the toner image and conveying it in the circumferential direction (arrow A direction). The transfer belt 31 holds the toner images that have been transferred once from the photoreceptors 22Y, 22M, 22C, and 22K, which have toner images of each color formed, through the primary transfer rollers 34.

[0060] And, as Figure 1As shown, if the image forming system 10 is viewed from the front side, a driven roller 36 is arranged below the drive roller 32, and a tension roller 37 is arranged above the drive roller 32 and on the right side in the width direction of the device. Furthermore, a support roller 74 is arranged below the tension roller 37. Then, the transfer belt 31 is wound around the drive roller 32, driven roller 36, tension roller 37, and support roller 74, and its posture is determined.

[0061] (Primary transfer roller)

[0062] The primary transfer roller 34 has the function of transferring the tonal images held on the photoreceptors 22Y, 22M, 22C, 22K to the transfer belt 31 by applying a transfer voltage. The primary transfer roller 34 contacts the inner surface of the transfer belt 31 and rotates about an axis.

[0063] (Secondary transfer roller)

[0064] The secondary transfer roller 38 has the function of transferring the toner image onto the medium P by clamping a portion of the transfer belt 31 wound on the drive roller 32. The secondary transfer roller 38 is disposed on the opposite side of the drive roller 32 across the transfer belt 31, and has an engagement portion N1 formed between the secondary transfer roller 38 and the drive roller 32 on the transfer belt 31.

[0065] The secondary transfer roller 38 rotates around its axis from the power supply PS (reference). Figure 1 A transfer voltage is applied to the drive roller 32. As a result, the secondary transfer roller 38 and the drive roller 32 transfer the toner image held by the transfer belt 31 to the medium P passing through the engagement portion N1. Additionally, the secondary transfer roller 38 is in contact with the ground wire.

[0066] (Tension roller)

[0067] The tension roller 37 functions to apply tension (i.e., tension) to the transfer belt 31. The tension roller 37 rotates automatically as it moves in the circumferential direction (arrow A) of the transfer belt 31. Tension is applied to the transfer belt 31 by pressing its outer peripheral surface against the inner surface of the transfer belt 31. As a result, the transfer belt 31 moves in the circumferential direction (arrow A) under tension, conveying the toner image held on the surface.

[0068] (Support roller)

[0069] The support roller 74 has the function of supporting the transfer belt 31 by contacting the inner surface of the transfer belt 31. The support roller 74 is driven by the movement of the transfer belt 31 around it.

[0070] (Concentration sensor)

[0071] The concentration sensor 72 has the function of measuring the concentration of the toner image transferred to the surface of the transfer belt 31 by irradiating the transfer belt 31 with light and detecting the light reflected by the transfer belt 31. The concentration sensor 72 is disposed opposite to the outer periphery of the transfer belt 31 at a position that is downstream of the toner image forming section 20 in the circumferential direction of the transfer belt 31 and upstream of the driven roller 36.

[0072] As an example, concentration sensors 72 are respectively disposed at both ends in the width direction intersecting the moving direction (arrow A direction) of the transfer belt 31. When measuring the toner concentration on the surface of the transfer belt 31 by the concentration sensors 72, the concentration sensors 72 irradiate light onto the transfer belt 31 and detect the light reflected by the transfer belt 31. The output of the concentration sensors 72 is input to the control unit 100 (reference). Figure 1 ).

[0073] (Cleaning scraper)

[0074] The cleaning scraper 76 has the function of contacting and cleaning the surface of the transfer belt 31. The cleaning scraper 76 is disposed downstream of the transfer position of the secondary transfer roller 38 in the circumferential direction (arrow A direction) of the transfer belt 31. By contacting the surface of the transfer belt 31 with the front end of the cleaning scraper 76, the cleaning scraper 76 removes the toner and other adhering substances remaining on the surface of the transfer belt 31 after the toner image has been transferred twice.

[0075] [Transmission Device]

[0076] The conveying device 40 has the function of conveying the media P contained in the media receiving section 42 along the conveying path 46C including the engagement section N1 and the engagement section N2 and discharging it outside the frame of the image forming system 10. The conveying device 40 includes a delivery roller 46A and a plurality of conveying roller pairs 46B.

[0077] [Fixing device]

[0078] The fixing device 50 has the function of fixing the toner image transferred to the media P by the transfer device 30 onto the media P. The fixing device 50 includes a heating roller 54 and a pressure roller 52. Then, the fixing device 50 heats the media P passing through the engagement portion N2 formed by the heating roller 54 and the pressure roller 52 by the heating roller 54, and applies pressure by the heating roller 54 and the pressure roller 52. As a result, the toner image is fixed onto the media P.

[0079] [Control Department]

[0080] The control unit 100 has the function of controlling each component of the image forming system 10. The control unit 100 will be described later.

[0081] <The Actions of the Image Forming System>

[0082] Next, the operation of the image forming system 10 will be explained.

[0083] When the image forming system 10 begins operation, toner images of each color are formed on the surfaces of photoreceptors 22Y, 22M, 22C, and 22K in the monochrome units 20Y, 20M, 20C, and 20K of the toner image forming section 20 through a process of charging, exposure, and development. Specifically, the photoreceptor 22 is charged by the charging roller 62 and exposed by the exposure device 64, thereby forming a latent image on the surface of the photoreceptor 22. Furthermore, the latent image of the photoreceptor 22 is developed using a toner by the developing machine 66. Thus, toner images of each color are formed on the surfaces of photoreceptors 22Y, 22M, 22C, and 22K in the monochrome units 20Y, 20M, 20C, and 20K.

[0084] In the image forming system 10, a transfer voltage is applied to the primary transfer rollers 34 for each color. Furthermore, the drive roller 32 causes the transfer belt 31 to rotate in the direction of arrow A. Thus, the tonal images of each color formed on the photoreceptors 22Y, 22M, 22C, and 22K are transferred to the transfer belt 31 in a superimposed manner in a single transfer.

[0085] On the other hand, the media P contained in the media receiving section 42 is conveyed to the engagement section N1 by the conveying device 40 in a manner that coincides with the arrival time of the portions of the transfer belt 31 where the toner images of each color have been transferred in the first stage. Then, by applying a transfer voltage to the drive roller 32, an electric field is formed between the drive roller 32 and the secondary transfer roller 38, and the toner images of each color held in the transfer belt 31 are transferred to the media P.

[0086] Furthermore, the medium P, on which toner images of each color are transferred, is conveyed toward the engagement portion N2 of the fixing device 50 via the conveying device 40. Then, the fixing device 50 fixes the toner images of each color onto the medium P passing through the engagement portion N2, and an image is formed on the medium P.

[0087] The medium P containing the image is discharged outside the device via the transmission device 40. Thus, the image forming operation ends.

[0088] <Clack width of the electrified roller>

[0089] Next, the engagement width of the charged roller 62 with the photoreceptor 22 will be explained.

[0090] exist Figure 2 The structure near the charged roller 62 is shown in the side view. Figure 3 The structure near the charged roller 62 is shown in cross-sectional view.

[0091] like Figure 2 and Figure 3 As shown, the charged roller 62 is arranged along the axial direction of the photoreceptor 22 and is in contact with the photoreceptor 22. A cleaning roller 80 for removing deposits from the surface of the charged roller 62 is arranged on the side of the charged roller 62 opposite to the photoreceptor 22. The cleaning roller 80 is arranged along the axial direction of the charged roller 62 and is in contact with the charged roller 62. Holding portions 82 (see reference) are provided at both ends of the cleaning roller 80 along its axial direction to rotatably hold the shaft portion of the cleaning roller 80. Figure 2 Additionally, in Figure 2 The holding portion that rotatably holds the shaft portion 62A of the charged roller 62 and the holding portion that rotatably holds the shaft portion of the photosensitive element 22 are omitted from the illustration.

[0092] like Figure 2 As shown, as an example, the retaining part 82 is supported by a symmetrical L-shaped support frame 84. The support frame 84 is pressed against the photosensitive element 22 by a helical spring 86. The helical spring 86 is an example of a pressing component. The helical spring 86 presses the charged roller 62 against the photosensitive element 22 to create an engagement width NW (see reference). Figure 3 Here, the engagement width NW refers to the width of the contact between the charged roller 62 and the photoreceptor 22 in the direction of rotation (arrow direction). As an example, the charged roller 62 includes a shaft portion 62A and an elastic layer 62B formed around the shaft portion 62A and having electrical conductivity. The engagement width NW of the charged roller 62 is generated by pressing the charged roller 62 against the photoreceptor 22. A helical spring 86 is provided at both ends of the cleaning roller 80 in the axial direction. As an example, the charged roller 62 is pressed against the photoreceptor 22 via the cleaning roller 80 using the helical spring 86.

[0093] Figure 4 This is a graph showing the profile of the engagement width (Nip width) NW between the charged roller 62 and the photoreceptor 22. Figure 4 The diagram shows the relationship between the axial position of the charged roller 62 and the engagement width NW. The two ends of the charged roller 62 are pressed against the photosensitive element 22 by helical springs 86 (see reference). Figure 2 Therefore, as Figure 4 As shown, the engagement width NW at both ends of the electric roller 62 in the axial direction is greater than the engagement width NW at the center in the axial direction.

[0094] Figure 5 This is a graph showing the relationship between the bite width NW and the amount of additive adhering to the charged roller 62. The developer contains additives. For example... Figure 5As shown, if the engagement width NW between the charged roller 62 and the photoreceptor 22 increases, the additive tends to adhere to the charged roller 62. When the engagement width NW between the charged roller 62 and the photoreceptor 22 is, for example, 0.39 mm or less, poor following is likely to occur when the charged roller 62 is driven to rotate by the rotation of the photoreceptor 22. Furthermore, when the amount of additive adhering to the charged roller 62 is, for example, 0.7 mg or more, blurry toning agents are easily generated on the photoreceptor 22 due to poor charging caused by the charged roller 62. In this example, when the engagement width NW between the charged roller 62 and the photoreceptor 22 is, for example, 0.55 mm or more, the amount of additive adhering to the charged roller 62 increases. At this time, due to poor charging caused by the charged roller 62, blurry toning agents are easily generated on the photoreceptor 22. Therefore, when the engagement width NW between the electrified roller 62 and the photoreceptor 22 is, for example, 0.55 mm or more, it is preferable to remove any adhering substances such as additives attached to the electrified roller 62.

[0095] <Hardware Structure of Image Forming System>

[0096] Figure 6 This is a block diagram representing the hardware structure of the image forming system 10. Figure 6 In this document, hardware structures that are not related to the main part of the invention are omitted.

[0097] like Figure 6 As shown, the image forming system 10 includes a control unit 100, a power supply 120 for the electrified rollers, an exposure unit 64, a developing unit 66, a power supply 124 for the primary transfer rollers, a motor 126, and a density sensor 72. The developing unit 66 includes the power supply 122 for the developing rollers. Furthermore, the motor 126 drives the rollers of each part of the image forming system 10.

[0098] The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a storage device 104, and an input / output interface 105. These components are communicatively connected to each other via a bus 109.

[0099] CPU 101 is a central processing unit that executes various programs or controls various parts. CPU 101 is an example of a processor. That is, CPU 101 reads programs from ROM 102 or storage device 104 and executes the programs using RAM 103 as its working area. CPU 101 performs control of the aforementioned structures and various arithmetic operations according to the programs recorded in ROM 102 or storage device 104. In the first embodiment, an information processing program is stored in ROM 102 or storage device 104.

[0100] ROM 102 stores various programs and data. RAM 103 serves as a working area for temporary storage of programs or data. Storage device 104, consisting of an HDD (Hard Disk Drive) or SSD (Solid State Drive), stores various programs, including the operating system, and various data. The printer driver program is stored in storage device 104. CPU 101 reads the printer driver program from storage device 104 and executes it, thereby functioning as the printer driver.

[0101] The input / output interface 105 is an interface for communicating with the various devices mounted on the image forming system 10. The control unit 100 is connected to the power supply 120 for the charged roller, the exposure device 64, the developing machine 66, the power supply 124 for the primary transfer roller, the motor 126, and the density sensor 72 via the input / output interface 105.

[0102] The output value, which is the measured value determined by the concentration sensor 72, is input to the control unit 100.

[0103] The power supply 120 applies a bias voltage (i.e., a voltage for charging) to the charged roller 62. This charges the photoreceptor 22.

[0104] The developing roller is powered by a power supply 122 that applies a developing voltage to the developing roller 66A. During normal image formation, the developing roller 66A is powered by a developing voltage, thereby developing the latent image of the photoreceptor 22 using a toner to form a toner image.

[0105] The primary transfer roller 34 is supplied with a primary transfer voltage by a power supply 124. During normal image formation, the primary transfer roller 34 is supplied with a primary transfer voltage, thereby transferring the tonal image of the photoreceptor 22 onto the transfer belt 31 in one pass.

[0106] The CPU 101 of the control unit 100 controls the power supply 120 for the charged roller, the exposure device 64, the developing machine 66, the power supply 124 for the primary transfer roller, and the motor 126 in the monochrome units 20Y, 20M, 20C, and 20K of the toning image forming unit 20.

[0107] CPU 101 implements a bite width detection mode for detecting the bite width NW of the electrified roller 62 on the photoreceptor 22. For example, when performing density adjustment after the image forming system 10 has printed a predetermined number of prints, between 50 and 100, CPU 101 switches from the normal image forming mode to the bite width detection mode.

[0108] CPU101 performs cleaning of the electrified roller 62 based on the detection result of the bite width NW of the electrified roller 62 obtained through the bite width detection mode.

[0109] <Detection of the bite width of the electrified roller>

[0110] Next, the processing of the engagement width NW of the electric roller 62 with the photoreceptor 22 will be explained.

[0111] exist Figure 7 The diagram shows the potential at various points relative to the time taken when the contact width NW between the charged roller 62 and the photoreceptor 22 is detected, as well as the output of the developing toner and concentration sensor 72 of the photoreceptor 22. (See diagram for details.) Figure 7 As shown, in the bite width detection mode, the CPU 101 sets the absolute value of the surface potential 136A of the photoreceptor 22 charged by the charged roller 62 to be lower than the absolute value of the developing potential 132 of the developing machine 66. For example, by making the absolute value of the potential (i.e., the potential of the charged bias voltage) 134A of the charged roller 62 lower than the absolute value of the developing potential 132, the absolute value of the surface potential 136A of the photoreceptor 22 is set to be lower than the absolute value of the developing potential 132 of the developing machine 66.

[0112] As an example, the developing potential 132 of the developing machine 66 is set to -500V, and the surface potential 136A of the photoreceptor 22 is set to -400V. As an example, the potential (i.e., the potential of the bias voltage) 134A of the charged roller 62 is set to -450V. Thus, the absolute value (e.g., 400V) of the surface potential 136A of the photoreceptor 22 charged by the charged roller 62 is set to be lower than the absolute value (e.g., 500V) of the developing potential 132 of the developing machine 66.

[0113] As an example, in the bite width detection mode, the developing potential 132 of the developing machine 66 in the normal image forming mode is not changed, but the absolute value of the potential 134A of the charged roller 62 is reduced. Thus, it is set that the absolute value of the surface potential 136A of the photoreceptor 22 charged by the charged roller 62 is lower than the absolute value of the developing potential 132 of the developing machine 66.

[0114] like Figure 7As shown, the CPU 101 causes the absolute value of the potential 134B of the charged roller 62 to rise in a rectangular wave only at a predetermined time, so that the absolute value of the surface potential 136B of the photoreceptor 22 is higher than the absolute value of the developing potential 132 of the developing machine 66. The predetermined time is the time during which the charged roller 62 discharges instantaneously before and after the engagement width NW of the photoreceptor 22, and does not discharge in the center of the engagement width NW.

[0115] As an example, the potential 134B of the charged roller 62 is set between -700V and -800V using a rectangular wave, and the surface potential 136B of the photoreceptor 22 is set to -600V. Thus, the absolute value of the surface potential 136B of the photoreceptor 22 (e.g., 600V) is higher than the absolute value of the developing potential 132 of the developing machine 66 (e.g., 500V).

[0116] like Figure 8 As shown, the charged roller 62 discharges before and after the engagement width NW with the photoreceptor 22 (reference). Figure 8 The discharge state ED is shown. That is, discharge occurs in the space between the charged roller 62 and the photosensitive element 22 before and after the engagement width NW. Therefore, as Figure 7 As shown, if the absolute value of the potential 134B of the charged roller 62 is instantaneously increased, no discharge will occur within the engagement width NW, and the absolute value of the surface potential 136A of the photoreceptor 22 will not increase. As an example, the surface potential 136A of the photoreceptor 22 in the non-discharged portion becomes -400V.

[0117] The set time for the absolute value of the potential 134B of the electrified roller 62 to rise in a rectangular wave is set, for example, as follows.

[0118] When the diameter of the charged roller 62 is set to d [mm] and the rotational speed of the photosensitive element 22 is set to v [mm / sec], the set time t [ms] is t = d / v × 2.92 ± 5%.

[0119] As an example, when the diameter d of the charged roller 62 is φ12 [mm] and the rotational speed v of the photosensitive element 22 is 175 [mm / sec], the set time t [ms] becomes 0.2 ± 5% [ms].

[0120] The minimum set time is the time until the required voltage 134B of the charged roller 62 is reached, and the maximum set time is less than the time during which no undischarged area remains on the bite width NW.

[0121] As an example, the minimum set time is 0.15 ms of the time it takes for the potential of the charged roller 62 to reach -600V to -900V at a rotational speed of 175 mm / sec. Furthermore, as an example, with a hypothetical minimum engagement width of 0.3 mm, the maximum set time is 0.3 mm / 175 mm / sec = 1.7 ms. For example, in the diameter and hardness of the charged roller 62 in the first embodiment, the hypothetical minimum engagement width is 0.3 mm. Additionally, in the rotational direction of the photoreceptor 22, if the pre-discharge start position before and after the engagement width NW reaches the post-discharge start position, the undischarged area disappears.

[0122] Within the aforementioned set time period, the absolute value of the potential 134B of the charged roller 62 is increased in a rectangular wave, thereby forming a portion of the absolute value of the surface potential 136A of the photoreceptor 22 with a low absolute value between the portions of the high absolute value of the surface potential 136B of the photoreceptor 22. The portions of the high absolute value of the surface potential 136B and the portions of the low absolute value of the surface potential 136A of the photoreceptor 22 correspond to a "latent image" in the bite width detection mode. Thus, as... Figure 7 As shown, the developing toner of the photoreceptor 22 developed by the developing machine 66 is formed in the portion where the absolute value of the surface potential 136A of the photoreceptor 22 is lower than the absolute value of the developing potential 132. That is, the toner is negatively polar, so the developing toner is formed in the portion where the surface potential 136A of the photoreceptor 22 is -400V. The position P2 where the blurring toner (i.e., the developing toner) is located during the state S1 where there is less blurring toner in the rotation direction of the photoreceptor 22 corresponds to the engagement width NW.

[0123] The blurring toner (i.e., developing toner) on the surface of the photoreceptor 22 is transferred to the transfer belt 31 in one step, and the blurring toner (i.e., developing toner) on the transfer belt 31 is measured using the concentration sensor 72. Figure 7 As shown, the output of the density sensor 72 corresponds to the engagement width NW. That is, the density sensor 72 measures the width of position P2 where the blurring toner (i.e., the developing toner) is located during the state S1 when the blurring toner is less. The CPU 101 predicts the engagement width NW of the charged roller 62 on the photoreceptor 22 based on the measured value obtained by the density sensor 72 of the width of position P2 where the toner (i.e., the developing toner) is located. In this example, in order to transfer the blurring toner (i.e., the developing toner) on the surface of the photoreceptor 22 to the transfer belt 31 in one pass, the density sensor 72 indirectly measures the blurring toner (i.e., the developing toner) on the surface of the photoreceptor 22.

[0124] As an example, the measurement of the blurring toner (i.e., developing toner) of the transfer belt 31 by the concentration sensor 72 is carried out continuously for about 10 times to predict the bite width NW by the average value.

[0125] As described above, the concentration sensor 72 is positioned opposite both ends of the transfer belt 31 along its axial direction. The concentration of the toner measured by the concentration sensor 72 is performed only at the position corresponding to the end of the photoreceptor 22 along its axial direction. Therefore, the CPU 101 predicts the engagement width NW of the charged roller 62 at the axial end of the photoreceptor 22 based on the measurement value from the concentration sensor 72.

[0126] Cleaning of live rollers

[0127] Next, the cleaning of the electrified roller 62 will be explained.

[0128] When the engagement width NW of the charged roller 62 corresponding to the measurement value of the concentration sensor 72 is above a threshold, the CPU 101 implements a cleaning mode to clean the charged roller 62. The cleaning mode is an example of a sweeping mode.

[0129] The threshold is set to, for example, 0.55. As mentioned above, if the engagement width NW is 0.55 [mm] or more, the amount of additive adhering to the charged roller 62 increases, and the amount of gray haze pigment in the photoreceptor 22 increases due to poor charging (see reference). Figure 5 Therefore, for example, by setting the threshold to 0.55 and cleaning the charged roller 62, it is possible to reduce the blurring of the photoreceptor 22.

[0130] Before explaining the cleaning mode, we will illustrate this with an example from typical image formation. For example... Figure 9 As shown in (A), during normal image formation, after electrostatic removal by the primary transfer roller 34, the photoreceptor 22 is charged by the charging roller 62, and then exposed or electrostatically removed by the exposure device 64. The latent image formed on the surface of the photoreceptor 22 is thus developed by the toner on the developing roller 66A. The toner image of the photoreceptor 22 is transferred to the transfer belt 31 by the primary transfer roller 34.

[0131] like Figure 9 As shown in (B), during normal image formation, the absolute value of the potential of the photoreceptor 22 decreases, while the absolute value of the potential of the charged roller 62 increases. Therefore, additives and other deposits attached to the surface of the charged roller 62 are less likely to migrate to the photoreceptor 22.

[0132] like Figure 10As shown in (A), in cleaning mode, the relationship between the potential of the photoreceptor 22 and the potential of the charged roller 62 is reversed. For example, the output of the primary transfer roller 34 is set to off, the output of the charged roller 62 is set to off, and the output of the exposure device 64 is set to off. Thus, as Figure 10 As shown in (B), the absolute value of the potential of the photoreceptor 22 increases, while the absolute value of the potential of the charged roller 62 decreases. For example, the potential of the photoreceptor 22 is -600V to -700V. Therefore, dirt (i.e., additives, etc.) on the surface of the charged roller 62 is transferred to the photoreceptor 22. The dirt (i.e., additives, etc.) on the surface of the photoreceptor 22 is removed by the cleaning scraper 68. Alternatively, the dirt (i.e., additives, etc.) on the surface of the photoreceptor 22 can be transferred to the transfer belt 31 and removed by the cleaning scraper 76.

[0133] Furthermore, when the engagement width NW of the charged roller 62 corresponding to the measurement value of the concentration sensor 72 is above a threshold, the CPU 101 increases the absolute value of the potential of the charged roller 62 that charges the photoreceptor 22 during image formation, compared to the absolute value of the potential of a normal charged roller 62. By increasing the absolute value of the potential of the charged roller 62 compared to the absolute value of the potential of a normal charged roller 62, the engagement width NW of the charged roller 62 is widened, which can suppress charging defects (i.e., blurring of the photoreceptor 22) caused by the progression of contamination. For example, the absolute value of the potential of the charged roller 62 is set to be increased by +10V relative to the absolute value of the potential of a normal charged roller 62. As a result, charging defects (i.e., blurring of the photoreceptor 22) caused by the engagement width NW of the charged roller 62 becoming uneven in the axial direction are less likely to occur.

[0134] <The function of image forming system 10>

[0135] Figure 11 This is a flowchart illustrating the information processing flow of the image forming system 10. In the image forming system 10, the CPU 101 reads the information processing program from the ROM 102 or the storage device 104, expands it in the RAM 103, and executes it, thereby performing information processing.

[0136] like Figure 11 As shown, the CPU101 implements a detection sequence of the engagement width NW of the electrified roller 62 on the photoreceptor 22 (step S301).

[0137] Specifically, after printing the specified number of sheets, the CPU101 switches from the normal image forming mode to the bite width detection mode. For example... Figure 7As shown, the CPU 101 is configured such that the absolute value of the surface potential 136A of the photoreceptor 22 charged by the charged roller 62 is lower than the absolute value of the developing potential 132 of the developing machine 66. In this state, the CPU 101 causes the absolute value of the potential 134B of the charged roller 62 to rise in a rectangular wave only for a predetermined time, so that the absolute value of the surface potential 136B of the photoreceptor 22 is higher than the absolute value of the developing potential 132 of the developing machine 66. The predetermined time is the time during which discharge occurs instantaneously before and after the engagement width NW of the charged roller 62 on the photoreceptor 22, and during the time during which no discharge occurs in the center of the engagement width NW. Thus, a portion of the surface potential 136A of the photoreceptor 22 with a low absolute value is formed between portions where the absolute value of the surface potential 136B of the photoreceptor 22 is high.

[0138] Therefore, the developing toner of the photoreceptor 22 developed by the developing machine 66 is formed in the portion where the absolute value of the surface potential 136A of the photoreceptor 22 is lower than the absolute value of the developing potential 132 (reference). Figure 7 During the state S1, when there is less blurring toner in the rotational direction of the photoreceptor 22, the position P2 where the blurring toner (i.e., the developing toner) is located corresponds to the bite width NW.

[0139] Next, the blurring toner (i.e., developing toner) on the surface of the photoreceptor 22 is transferred to the transfer belt 31 in one pass, and the blurring toner (i.e., developing toner) on the transfer belt 31 is measured using the density sensor 72. The CPU 101 predicts the engagement width NW of the charged roller 62 on the photoreceptor 22 based on the measured value obtained by the density sensor 72 of the width of the toner (i.e., developing toner) at the location P2.

[0140] like Figure 11 As shown, CPU101 determines whether the bite width NW is above a threshold (step S302). As mentioned above, the threshold is, for example, 0.55.

[0141] If the bite width NW is above the threshold (step S302: "Yes"), CPU101 performs the cleaning sequence of the electrified roller 62 (step S303).

[0142] Specifically, CPU101 switches to the cleaning mode of the electrified roller 62. For example... Figure 10 As shown in (A), for example, the output of the primary transfer roller 34 is set to off, the output of the charged roller 62 is set to off, and the output of the exposure device 64 is set to off. Thus, as Figure 10 As shown in (B), the absolute value of the potential of the photoreceptor 22 increases, while the absolute value of the potential of the charged roller 62 decreases. As a result, dirt (i.e., additives and other deposits) on the surface of the charged roller 62 is transferred to the photoreceptor 22, and the dirt (i.e., additives and other deposits) on the surface of the photoreceptor 22 is removed by the cleaning scraper 68.

[0143] like Figure 11 As shown, if the bite width NW is not above the threshold (step S302: "No"), the CPU 101 terminates the processing of the information processing program based on the image forming system 10.

[0144] Thus, the information processing based on the image forming system 10 is terminated.

[0145] In the image forming system 10 described above, the engagement width NW of the charged roller 62 on the photoreceptor 22 can be inferred.

[0146] Furthermore, in the image forming system 10, when the diameter of the charged roller 62 is set to d [mm] and the rotational speed of the photoreceptor 22 is set to v [mm / sec], the set time t [ms] is t = d / v × 2.92 ± 5%.

[0147] Therefore, in the image forming system 10, compared to the case where time t is longer than d / v×2.92+5%, it is possible to form the position P2 (reference) of the blurring toner corresponding to the engagement width NW of the charged roller during a period when there is less blurring toner in the rotational direction of the photoreceptor 22. Figure 7 Furthermore, in the image forming system 10, compared to the case where the time t is shorter than d / v × 2.92-5%, it is possible to form the position P2 (reference) of the blurring toner corresponding to the engagement width NW of the charged roller during a period when there is less blurring toner in the rotational direction of the photoreceptor 22. Figure 7 ).

[0148] Furthermore, in the image forming system 10, the minimum set time is the time until the desired potential of the charged roller 62 is reached, and the maximum set time is less than the time during which no undischarged area remains on the engagement width NW. Therefore, in the image forming system 10, by increasing the absolute value of the potential of the charged roller 62 only during the set time, it is possible to form a position P2 (reference point) opposite to the engagement width NW of the charged roller 62 during a period when there is little blurring agent in the rotation direction of the photoreceptor 22. Figure 7 ).

[0149] Furthermore, in the image forming system 10, the CPU 101 predicts the engagement width NW of the electrified roller 62 on the photoreceptor 22 based on a measurement obtained by indirectly measuring the width of the position P2 where the blurr toner is located during a period of low blurr toner concentration in the rotational direction of the photoreceptor 22. Therefore, in the image forming system 10, the engagement width NW of the electrified roller 62 on the photoreceptor 22 can be inferred based on the measured value of the width of the position P2 where the blurr toner is located.

[0150] Furthermore, the image forming system 10 includes: a transfer belt 31, a toner on the surface of the transfer photoreceptor 22; and a density sensor 72, which detects the concentration of the toner transferred to the transfer belt 31. Therefore, in the image forming system 10, by detecting the concentration of the toner transferred to the transfer belt 31 by the density sensor 72, the width of the blurred toner during a state with low toner concentration can be determined.

[0151] Furthermore, in the image forming system 10, the concentration of the toner is measured only at the end corresponding to the axial direction of the photoreceptor 22. Therefore, in the image forming system 10, compared to measuring the concentration of the toner along the entire axial direction of the photoreceptor, it is easier to measure the width of the blurred toner in the rotational direction of the photoreceptor 22.

[0152] Furthermore, when the engagement width NW of the charged roller 62 corresponding to the measurement value of the concentration sensor 72 is above a threshold, the CPU 101 implements a cleaning mode to clean the charged roller 62. Therefore, in the image forming system 10, compared to the case where the engagement width of the charged roller on the photoreceptor is unknown, the occurrence of poor charging of the photoreceptor 22 caused by the charged roller 62 can be suppressed.

[0153] Furthermore, in the image forming system 10, a cleaning blade 68 is provided downstream of the transfer position where the toner image on the surface of the photoreceptor 22 is transferred to the transfer belt 31 and upstream of the charged roller 62 to clean the surface of the photoreceptor 22. In cleaning mode, dirt on the charged roller 62 is transferred to the photoreceptor 22, and the dirt on the photoreceptor 22 is removed using the cleaning blade 68. Therefore, in the image forming system 10, dirt on the charged roller 62 can be removed using the cleaning blade 68 on the photoreceptor 22.

[0154] Furthermore, when the engagement width NW of the charged roller 62 corresponding to the measurement value of the concentration sensor 72 is above a threshold, the CPU 101 increases the absolute value of the potential of the charged roller 62 that charges the photoreceptor 22 during image formation, compared to the absolute value of the potential of the normally charged roller 62. Therefore, in the image forming system 10, compared to the case where the potential of the charged roller is constant during image formation, the occurrence of poor charging of the photoreceptor 22 caused by the charged roller 62 can be suppressed.

[0155] Furthermore, in the image forming system 10, the state in which the absolute value of the surface potential of the photoreceptor 22 charged by the charged roller is lower than the absolute value of the developing potential of the developing machine 66 is achieved by reducing the absolute value of the potential of the charged roller 62 without changing the developing potential of the developing machine 66. Therefore, in the image forming system 10, compared to the case where the developing potential of the developing machine is changed, the cost of the output substrate of the developing machine 66 can be suppressed.

[0156] Furthermore, in the image forming system 10, the charged roller 62 charges the photoreceptor 22 by adding an AC voltage to the DC voltage. Therefore, in the image forming system 10, the surface potential of the photoreceptor 22 is stabilized compared to the case where only a DC voltage is used to charge the surface of the photoreceptor.

[0157] Furthermore, in the first embodiment, the concentration of the toner is measured once by the concentration sensor 72, and a cleaning mode for cleaning the charged roller 62 is performed once based on the engagement width NW of the charged roller 62 corresponding to the measured value. However, the present invention is not limited to this structure. The CPU 101 can increase the frequency of the cleaning mode for cleaning the charged roller 62 based on the engagement width of the charged roller 62 corresponding to the measured value by the concentration sensor 72. For example, the cleaning mode can be performed more than twice every time the width of the blur toner is measured. As a result, in the image forming system 10, compared to the case where a cleaning mode is performed once every time the width of the blur toner is measured, the occurrence of poor charging of the photoreceptor 22 caused by the charged roller 62 can be suppressed.

[0158] [Second Implementation]

[0159] Next, the image forming system according to the second embodiment will be described. Furthermore, components identical to those in the first embodiment described above will be labeled with the same numbers, and their descriptions will be omitted.

[0160] exist Figure 12 The image forming unit 401 of the image forming system 400 according to the second embodiment is shown. Figure 12 As shown, the toning agent image forming unit 401 of the image forming system 400 includes a photoreceptor 402 that rotates in the direction of the arrow. The photoreceptor 402 is an example of an image holder. Furthermore, the image forming system 400 includes a charged roller 62, an exposure device 64, a developing unit 404, a transfer roller 406, and a cleaning blade 68 around the photoreceptor 402. The image forming system 400 also includes a density sensor 420. The developing unit 404 is an example of a developing section.

[0161] In the image forming system 400, a transfer roller 406 is disposed on the lower side of the photoreceptor 402 in the vertical direction. The transfer roller 406 directly transfers the toner image formed on the surface of the photoreceptor 402 to a medium P conveyed between the photoreceptor 402 and the transfer roller 406. The medium P is, for example, paper. A density sensor 420 is an example of a detection unit. The density sensor 420 is disposed between the developing unit 404 and the transfer roller 406 in the rotational direction of the photoreceptor 402. The density sensor 420 detects the concentration of the toner on the surface of the photoreceptor 402. As an example, the density sensor 420 is disposed at positions opposite to both ends of the photoreceptor 402 in the axial direction.

[0162] Furthermore, the other structures of the image forming system 400 are the same as those of the monochrome unit of the toning agent image forming section 20 of the image forming system 10 in the first embodiment. The image forming system 400 includes a bite width detection mode for detecting the bite width NW of the charged roller 62 on the photoreceptor 402. Moreover, the image forming system 400 includes a cleaning mode for cleaning the charged roller 62 based on the bite width NW.

[0163] In the image forming system 400 of the second embodiment, in addition to the effects based on the same structure as the image forming system 10 of the first embodiment, the following effects are also present.

[0164] In the image forming system 400, the concentration of toner on the surface of the photoreceptor 402 is directly detected by the concentration sensor 420. The concentration sensor 420 can also measure the width of the blurring toner during periods when the surface of the photoreceptor 402 has low levels of blurring toner. In the image forming system 400, the engagement width NW between the charged roller 62 and the photoreceptor 402 can be predicted based on the width of the blurring toner and the directly measured value.

[0165] [Supplementary Explanation]

[0166] The image forming system of the present invention is not limited to the image forming systems 10 and 400 described in the first and second embodiments, and various modifications can be made. In the first embodiment, a density sensor 72 is provided at a position opposite to the transfer belt 31 corresponding to both ends of the photoreceptor 22 along its axial direction, but the present invention is not limited to this structure. For example, if the contour of the charged roller 62 relative to the photoreceptor 22 is obtained, the engagement width NW of the axial end of the charged roller 62 can be predicted, and therefore the position of the density sensor 72 can be changed.

[0167] Similarly, in the second embodiment, a concentration sensor 420 is provided at positions opposite to both ends of the photoreceptor 402 along its axial direction, but the present invention is not limited to this structure. For example, if the contour of the charged roller 62 relative to the photoreceptor 402 is obtained, the engagement width NW at the axial ends of the charged roller 62 can be predicted, and thus the position of the concentration sensor 420 can be changed.

[0168] Furthermore, in the first embodiment, the structure of the helical spring 86 used to press the charged roller 62 against the photosensitive element 22 can also be changed.

[0169] Furthermore, the processing of the aforementioned image forming systems 10 and 400 can also be implemented using dedicated hardware circuitry. In this case, it can be performed by a single piece of hardware or by multiple pieces of hardware.

[0170] Furthermore, the program that enables the image forming systems 10 and 400 to operate can be provided by computer-readable recording media such as USB (Universal Serial Bus) memory, floppy disk, or CD-ROM (Compact Disc Read Only Memory), or it can be provided online via a network such as the Internet. In this case, the program recorded on the computer-readable recording medium is usually transferred and stored in memory or storage device. Moreover, this program can be provided, for example, as standalone application software, or it can be programmed into the software of each device as a function of the image forming systems 10 and 400.

[0171] Furthermore, while specific embodiments of the present invention have been described in detail, the present invention is not limited to these embodiments, and those skilled in the art will obviously be able to employ various other embodiments within the scope of the present invention.

[0172] [Postscript]

[0173] The following are descriptions of the methods of the present invention. (((1)))

[0175] An image forming system comprising:

[0176] The image is held in place and rotated.

[0177] The charged part rotates while in contact with the image holder, and the surface of the image holder is charged by applying a charged bias voltage;

[0178] The pressing component presses the charged part onto the image holder in a manner that creates an engagement width;

[0179] The developing section develops the latent image formed on the surface of the image holder using a toning agent; and

[0180] At least one processor,

[0181] The processor performs the following processing:

[0182] When the absolute value of the surface potential of the image holder charged by the charged part is lower than the absolute value of the developing potential of the developing part, the absolute value of the potential of the charged part is increased in a rectangular wave for a set time during which the charged part discharges only at the moment before and after the engagement width of the image holder and does not discharge in the middle of the engagement width, so that the absolute value of the surface potential of the image holder is higher than the absolute value of the developing potential. (((2)))

[0184] According to the image forming system described in ((1)), wherein,

[0185] The charged part is a circular rotating body.

[0186] When the diameter of the charged part is set to d [mm] and the rotational speed of the image holder is set to v [mm / sec],

[0187] The set time t [ms] is t = d / v × 2.92 ± 5%. (((3)))

[0189] According to the image forming system described in (((1))) or (((2))), wherein,

[0190] The minimum value of the set time is the time until the desired potential of the charged part is reached, and the maximum value of the set time is less than or equal to the time during which no undischarged area remains in the engagement width. (((4)))

[0192] The image forming system according to any one of ((1))) to ((3))) wherein,

[0193] The processor performs the following processing:

[0194] The engagement width of the charged part with the image holder is predicted based on the measured value obtained by directly or indirectly measuring the width of the position of the blurr during a state where the blurr is less in the rotational direction of the image holder. (((5)))

[0196] According to the image forming system described in ((4)), it has:

[0197] An intermediate transfer body transfers the toner onto the surface of the image holder; and

[0198] The concentration detection unit detects the concentration of the toner transferred to the intermediate transfer body. (((6)))

[0200] The image forming system according to ((4)) has a detection unit that detects the concentration of toner on the surface of the image holder. (((7)))

[0202] According to the image forming system described in ((5)) or ((6)), wherein,

[0203] The concentration of the toning agent is measured only at a position corresponding to the end of the image holder along its axial direction. (((8)))

[0205] According to the image forming system described in (4), wherein,

[0206] The processor performs the following processing:

[0207] When the engagement width of the charged part corresponding to the measured value is above a threshold, a cleaning mode for cleaning the charged part is implemented. ((9)))

[0209] According to the image forming system described in (8), wherein,

[0210] The processor performs the following processing:

[0211] Based on the engagement width of the charged part corresponding to the measured value, the frequency of the cleaning mode for cleaning the charged part is increased. (((10)))

[0213] According to the image forming system described in (8), wherein,

[0214] Downstream of the transfer position where the toner image on the surface of the image holder is transferred to the media and upstream of the charged portion, a cleaning member is provided for cleaning the surface of the image holder.

[0215] In the cleaning mode, the dirt on the charged part is transferred to the image holder, and the dirt on the image holder is removed by the cleaning component. (((11)))

[0217] According to the image forming system described in (4), wherein,

[0218] The processor performs the following processing:

[0219] When the engagement width of the charged part corresponding to the measured value is above a threshold, the absolute value of the potential of the charged part that keeps the image body charged during image formation is increased compared to the absolute value of the potential of the normally charged part. (((12)))

[0221] The image forming system according to any one of ((1))) to ((11))) wherein,

[0222] The state in which the absolute value of the surface potential of the image holder charged by the charged part is lower than the absolute value of the developing potential of the developing part is obtained by reducing the absolute value of the potential of the charged part without changing the developing potential of the developing part. (((13)))

[0224] The image forming system according to any one of ((1))) to ((12))) wherein,

[0225] The charged part makes the image holding body charged by adding an AC voltage to the DC voltage.

[0226] Based on the image forming system involved in (((1))), the engagement width of the charged part with the image holder can be inferred.

[0227] According to the image forming system involved in ((2)), compared with the case where time t is longer than d / v×2.92+5% or shorter than d / v×2.92-5%, it is possible to form the position of the blurring toner corresponding to the engagement width of the charged part during the state where there is less blurring toner in the rotation direction of the image holder.

[0228] According to the image forming system involved in ((3)), by increasing the absolute value of the potential of the charged part only at a set time, it is possible to form the position of the blurring toner opposite to the engagement width of the charged part during a state where the blurring toner is less in the rotation direction of the image holder.

[0229] Based on the image forming system involved in ((4)), the engagement width of the charged part with the image holder can be inferred from the measured value of the width of the position of the blurring toner.

[0230] According to the image forming system involved in ((5)), by detecting the concentration of the toner transferred to the intermediate transfer body by the concentration detection unit, the width of the blur toner during the state of low blur toner can be determined.

[0231] According to the image forming system involved in ((6)), by directly detecting the concentration of the toner on the surface of the image holder by the detection unit, the width of the blur toner during the state of low blur toner can be determined.

[0232] According to the image forming system involved in ((7)), it is easier to determine the width of the blurring toner in the rotational direction of the image holder compared to the case where the concentration of the toner is measured along the entire axis of the image holder.

[0233] According to the image forming system involved in ((8)), compared with the case where the engagement width of the charged part to the image holder is unknown, it is possible to suppress the occurrence of poor charging of the image holder caused by the charged part.

[0234] According to the image forming system involved in (9), compared with the case where a cleaning mode is performed every time the width of the blur toner is measured, the occurrence of poor charging of the image holder caused by the charged part can be suppressed.

[0235] According to the image forming system involved in ((10)), it is possible to remove dirt from the charged parts using the cleaning component of the image holder.

[0236] According to the image forming system involved in ((11)), compared with the case where the potential of the charged part is constant during image forming, the occurrence of poor charging of the image holder caused by the charged part can be suppressed.

[0237] According to the image forming system involved in ((12)), the cost of the output substrate of the developing section can be suppressed compared with the case of changing the developing potential of the developing section.

[0238] According to the image forming system involved in ((13)), the surface potential of the image holder is stable compared to the case where only a DC voltage is used to charge the surface of the image holder.

[0239] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

[0240] Symbol Explanation

[0241] 10 - Image forming system; 22 - Photoreceptor (an example of an image holder); 31 - Transfer belt (an example of an intermediate transfer body); 62 - Charged roller (an example of a charged section); 66 - Developer (an example of a developing section); 68 - Cleaning scraper (an example of a cleaning component); 72 - Concentration sensor (an example of a concentration detection unit); 86 - Helical spring (an example of a pressing component); 101 - CPU (an example of a processor); 132 - Developing potential; 134A - Potential of charged roller; 134B - Potential of charged roller; 136A - Surface potential of photoreceptor (an example of the surface potential of an image holder); 136B - Surface potential of photoreceptor (an example of the surface potential of an image holder); 400 - Image forming system; 402 - Photoreceptor (an example of an image holder); 404 - Developer (an example of a developing section); 420 - Concentration sensor (an example of a detection unit); NW - Engagement width.

Claims

1. An image forming system comprising: an image holding body that rotates; a charging section that rotates while being in contact with the image holding body, and charges a surface of the image holding body by applying a charging bias; a pressing member that presses the charging section on the image holding body in a manner that generates a nip width; a developing section that develops a latent image formed on the surface of the image holding body using toner; and at least one processor, the processor performs processing in which: in a state in which an absolute value of a surface potential of the image holding body charged by the charging section is lower than an absolute value of a developing potential of the developing section, an absolute value of a potential of the charging section is raised in a rectangular wave only for a set time in which a discharge occurs at an instant before and after the nip width of the image holding body by the charging section and no discharge occurs in a center of the nip width, so that the absolute value of the surface potential of the image holding body is higher than the absolute value of the developing potential.

2. The image forming system according to claim 1, wherein: the charging section is a circular rotating body, when a diameter of the charging section is set as d [mm] and a rotational speed of the image holding body is set as v [mm / sec], the set time t [ms] is t = d / v x 2.92 ± 5%.

3. The image forming system according to claim 1 or 2, wherein: a minimum value of the set time is a time until a required potential of the charging section is reached, and a maximum value of the set time is a time that is lower than a time in which no discharge interval is left on the nip width.

4. The image forming system according to any one of claims 1 to 3, wherein: the processor performs processing in which: a nip width of the charging section on the image holding body is predicted from a measurement value that is obtained by directly or indirectly measuring a width of a position at which toner that is blurred is present during a state in which toner that is blurred is little in a rotational direction of the image holding body.

5. The image forming system according to claim 4, comprising: an intermediate transfer body that transfers toner on the surface of the image holding body; and a density detection section that detects a density of toner transferred to the intermediate transfer body.

6. The image forming system according to claim 4, comprising a detection section that detects a density of toner on the surface of the image holding body.

7. The image forming system according to claim 5 or 6, wherein: measurement of the density of the toner is performed only at a position that corresponds to an end portion in an axial direction of the image holding body.

8. The image forming system according to claim 4, wherein: the processor performs processing in which: when the nip width of the charging section corresponding to the measurement value is equal to or higher than a threshold value, a cleaning mode in which the charging section is cleaned is implemented.

9. The image forming system according to claim 8, wherein: the processor performs processing in which: a frequency of the cleaning mode in which the charging section is cleaned is increased in accordance with the nip width of the charging section corresponding to the measurement value.

10. The image forming system according to claim 8, wherein: A cleaning member that cleans the surface of the image holding body is provided on the downstream side of a transfer position at which a toner image of the surface of the image holding body is transferred to a medium, and on the upstream side of the charging section, In the cleaning mode, dirt of the charging section is transferred to the image holding body, and the dirt of the image holding body is removed by the cleaning member.

11. The image forming system according to claim 4, wherein The processor performs the following processing: When the nip width of the charging section corresponding to the measured value is equal to or greater than a threshold value, the absolute value of the potential of the charging section that charges the image holding body at the time of image formation is increased compared to the absolute value of the potential of the charging section in general.

12. The image forming system according to any one of claims 1 to 11, wherein An absolute value of a surface potential of the image holding body charged by the charging section is lower than an absolute value of a developing potential of the developing section, and is obtained by reducing the absolute value of the potential of the charging section without changing the developing potential of the developing section.

13. The image forming system according to any one of claims 1 to 12, wherein The charging section charges the image holding body by adding an alternating voltage to a direct voltage.

Images