Image forming apparatus

Abstract

To solve the problem in which: in a case where a user frequently uses a specific toner, even when a toner not used is provided to the interface between a cleaning blade and an image carrier for the purpose of lubrication, an external additive for reducing the frictional force therebetween cannot be sufficiently supplied, and an unusual sound may be generated.SOLUTION: An image forming apparatus of the present invention acquires the amount of toner used by a user, and controls to supply the toner frequently used by the user to the interface between a cleaning blade and an image carrier in a process cartridge of each color.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to the field of image forming apparatuses such as copying machines and multifunction machines. [Background technology]

[0002] Conventionally, image forming devices have been equipped with an image forming unit (hereinafter referred to as a process cartridge) and an image forming means including a rotatable belt member that contacts the surface of an image carrier of each color. The process cartridge includes multiple rotatable image carriers provided according to toner color, and a charging means, a developing unit, and a cleaning unit for each image carrier. With this configuration, toner is supplied from the developing unit to form a toner image on the surface of the image carrier, and the toner image is then transferred onto a sheet material carried on the belt member, thereby forming an image on the sheet material. Note that a configuration in which a toner image is primarily transferred from the surface of the image carrier onto a belt member, and then secondarily transferred from the belt member onto a sheet material is also known.

[0003] In addition, a configuration in which a cleaning device is provided for each image carrier to remove residual toner remaining on the image carrier surface after the toner image is transferred from the image carrier surface to a sheet material or a belt member is also widely known. As such a cleaning device, a cleaning means equipped with a cleaning blade that contacts the image carrier surface to scrape off the residual toner is known.

[0004] However, when using a cleaning blade to scrape off residual toner, if the frictional force between the cleaning blade and the surface of the image carrier is large, the following problems may occur: The cleaning blade may chatter (stick-slip) or may turn over.

[0005] Therefore, a technology has been disclosed in which toner is supplied from a development unit to the surface of an image carrier for the purpose of lubrication when no image is being formed. That is, a technology has been disclosed in which the presence of an external additive in the toner at the interface between the cleaning blade and the surface of the image carrier reduces friction, suppresses the generation of abnormal noise, and maintains good cleaning performance (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-161426 Summary of the Invention [Problem to be solved by the invention]

[0007] However, depending on how the user uses the device, it may not be possible to suppress the generation of abnormal noise. Specifically, this applies to a color image forming device using four-color toner (YMCK), where one toner is used frequently and the other three colors are used infrequently. In this case, the toner in the developer container is agitated by the agitating member inside the developer container, and repeatedly collides with the container's inner wall and adjacent toner particles, causing the external additives attached to the toner's surface to peel off from the toner or become embedded in the toner. Thus, even if toner without external additives attached to the toner's surface is used for lubrication purposes, the amount of external additive required at the interface between the cleaning blade and the image carrier surface will be reduced, and the frictional force may not be sufficiently reduced. Therefore, depending on how the user uses the device, abnormal noise and / or peeling of the cleaning blade may occur.

[0008] On the other hand, for toner that is used less frequently, it is possible to stop the stirring operation in the developer container and retain the external additives that adhere to the surface of the toner matrix. However, in this case, it is necessary to provide an independent drive motor for each of the development units 40y to 40k, which increases costs.

[0009] The present invention has been made in view of the above circumstances, and has as its object to suppress the generation of abnormal noise and maintain good cleaning performance regardless of how the user uses it. [Means for solving the problem]

[0010] The image forming apparatus of the present invention selects frequently used toner based on the toner usage status of the user, and controls the toner supply operation so that the selected toner can be supplied to the interface between the cleaning blade and the surface of the image carrier. [Effects of the Invention]

[0011] According to the present invention, regardless of how the user uses the cleaning blade, the frictional force between the cleaning blade and the surface of the image carrier can be reduced more stably, thereby suppressing the generation of abnormal noise and maintaining good cleaning performance. [Brief explanation of the drawings]

[0012] [Figure 1] Overall configuration of image forming apparatus [Figure 2] An explanatory diagram of an image forming operation [Figure 3] Engine controller configuration diagram [Figure 4] Video controller configuration diagram [Figure 5] Toner supply operation control of the embodiment [Figure 6] Modified toner supply operation control [Figure 7] Example of supplied toner image in the embodiment DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, the relative positions and numerical values ​​of the components described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified.

[0014] [Embodiment] An embodiment to which the present invention can be applied will be described with reference to FIG.

[0015] [Overall configuration of image forming device] The schematic configuration of an image forming apparatus according to this embodiment is shown in Figure 1. The image forming apparatus 102 according to this embodiment is a full-color laser beam printer that employs an electrophotographic system.

[0016] The image forming apparatus 102 has a video controller 103 that performs various controls and data processing, and an engine controller 104 that forms a visualized image on a transfer material P. The transfer material P is also called a recording material, recording medium, paper, sheet, or transfer paper. A host computer 101 and the like are connected to the image forming apparatus 102 via a network, a parallel interface, a serial interface, or the like. The host computer 101 issues a print execution request to the image forming apparatus 102 based on the print conditions (e.g., paper size, number of copies, print orientation, print purpose, etc.) set by the user on the printer driver. The video controller 103 rasterizes the print data sent from the host computer 101 along with the print execution instruction into image data, performs data processing described below, and sends the image data to the engine controller 104.

[0017] [Image formation operation] Referring to FIG. 2, a process in which the engine controller 104 controls the image forming apparatus and forms a visualized image on the transfer material P will be described.

[0018] The image forming apparatus is provided with four process cartridges Y, M, C, and Bk, corresponding to the toners of yellow (Y), magenta (M), cyan (C), and black (Bk). The process cartridges for each color are arranged in a horizontal row (from right to left in the figure) along the rotation direction of an intermediate transfer belt 10 (a rotating body and a transport body) that transports toner images formed on photosensitive drums 1y to 1k (described later) to a secondary transfer position. Each process cartridge has a nonvolatile memory device, and the CPU 303 and ASIC 304 of the engine controller 104 read and write various information (such as the total number of images formed and operating time) from and to the memory device.

[0019] The photosensitive drums 1y to 1k are arranged so as to be able to come into contact with the intermediate transfer belt 10, and the toner images carried on the surfaces of the photosensitive drums 1y to 1k can be sequentially transferred onto the intermediate transfer belt 10. The toner images sequentially transferred onto the intermediate transfer belt 10 are then transported to a secondary transfer position (not shown), and then secondarily transferred onto the transfer material P. In this way, in this embodiment, a desired full-color image can be formed on the transfer material P. This type of image forming method is called an "inline method."

[0020] The process cartridge is an image forming unit that is detachably attached to the main body of the image forming apparatus, and includes photosensitive drums 1y to 1k, charging means 2y to 2k, developing units 40y to 40k, and cleaning units 60y to 60k.

[0021] The photosensitive drums 1y to 1k are made of OPC (organic photoconductor) with a diameter of 30 mm and negative charging characteristics, and during image formation, they are rotated in the direction of the arrow by a drive motor (not shown) at a peripheral speed (process speed) of 100 mm / sec.

[0022] The charging means 2y to 2k have an actual resistance of 1×10 6 The rollers are adjusted to Ω, and come into contact with the photosensitive drums 1y to 1k with a total pressure of 9.8 N (Newtons), and are rotated by the photosensitive drums 1y to 1k.

[0023] The developing units 40y-40k are provided with developing rollers 41y-41k that supply toner (developer) to the surfaces of the photosensitive drums 1y-1k. Furthermore, regulating blades (not shown) that regulate the toner layer thickness on the surfaces of the developing rollers 41y-41k are provided, and these are integrally held in a developing container. The developing rollers 41y-41k are driven to rotate by a common drive motor (not shown) that serves as a common drive source, and rotate at a peripheral speed (process speed) of 110 mm / sec in the forward direction relative to the rotational direction of the photosensitive drums 1y-1k.

[0024] The cleaning units 60y-60k have cleaning blades 61y-61k that come into contact with the surfaces of the rotating photosensitive drums 1y-1k to scrape (remove) toner from the surfaces of the photosensitive drums 1y-1k. The cleaning units 60y-60k are also provided with waste toner containers 62y-62k that store the toner scraped from the surfaces of the photosensitive drums 1y-1k. The cleaning blades 61y-61k are preferably made of an elastic material such as urethane rubber. Making the cleaning units 60y-60k detachable from the process cartridges facilitates maintenance work, such as waste toner collection, thereby improving usability.

[0025] Next, the image forming process for forming an image on the transfer material P will be described.

[0026] When a signal to start image formation is input to the control unit of the device main body, first, the photosensitive drums 1y to 1k begin to rotate by a drive motor (common to all colors, not shown), and a charging voltage (-1.2 kV DC voltage) is applied to the charging rollers 2y to 2k from a power supply (not shown). As a result, the surfaces of the photosensitive drums 1y to 1k are uniformly charged to approximately -600 V.

[0027] After the surfaces of the photosensitive drums 1y-1k are uniformly charged, laser light (exposure light) modulated based on an image signal is emitted from the exposure devices 3y-3k, and the surfaces of the photosensitive drums 1y-1k are scanned and exposed, thereby forming electrostatic latent images on the surfaces of the photosensitive drums 1y-1k. In this embodiment, polygon scanners using laser diodes are used as the exposure devices 3y-3k, and the surface potential of the photosensitive drums 1y-1k exposed to the laser becomes approximately -200V.

[0028] In the main scanning direction (the direction perpendicular to the transfer material transport direction), laser exposure starts for each scan line from a position signal in a polygon scanner called BD. Meanwhile, in the sub-scanning direction (the transfer material transport direction), laser exposure starts with a predetermined delay from a TOP signal that originates from a switch (not shown) in the transfer material transport path. This allows laser exposure to always be performed at the same position on the surface of the photosensitive drums 1y to 1k in the four process cartridges Y, M, C, and K.

[0029] Thereafter, toner is supplied from the developing rollers 41y to 41k in contact with the surfaces of the photosensitive drums 1y to 1k to the electrostatic latent images formed on the surfaces of the photosensitive drums 1y to 1k, and the electrostatic latent images are developed into toner images of the respective colors. At this time, a developing voltage (approximately -350V) is applied to the developing rollers 41y to 41k from a power supply (not shown), which makes it possible to electrostatically supply (develop) the toner to the electrostatic latent images.

[0030] The toner images developed on the surfaces of the photosensitive drums 1y to 1k are sequentially transferred (primary transfer) onto an intermediate transfer belt 10 as a belt member in the primary transfer nip portions (width: approximately 1.5 mm) formed by the photosensitive drums 1y to 1k and the transfer rollers 51y to 51k. The intermediate transfer belt 10 is stretched over a roller member 12 and rotates in the direction of the arrow in the figure at a peripheral speed equal to the process speed (100 mm / sec) of the photosensitive drums 1y to 1k. The intermediate transfer belt 10 has a rotational speed of 1×10 10It is an endless single-layer resin belt made of 100 μm thick polyimide film with resistance adjusted to Ωcm, and ribs are provided on both ends of the back side to prevent the belt from meandering or becoming biased.

[0031] The transfer rollers 51y to 51k have a volume resistivity of 1×10 5 Rollers adjusted to a resistance of Ωcm are used to press the intermediate transfer belt 10 from behind, pressing it against the surfaces of the photosensitive drums 1y-1k. By applying a positive transfer voltage (DC voltage) to these transfer rollers 51y-51k, the toner images formed on the surfaces of the photosensitive drums 1y-1k can be sequentially transferred onto the intermediate transfer belt 10. The transfer voltage applied to the transfer rollers 51y-51k is set to +1.0 kV. This allows the toner images to be transferred onto the intermediate transfer belt 10. After the toner images are transferred from the surfaces of the photosensitive drums 1y-1k to the intermediate transfer belt 10, any residual toner remaining on the surfaces of the photosensitive drums 1y-1k is removed by cleaning units 60y-60k. The transfer rollers 51y-51k are movably mounted so that they can be positioned to bring the intermediate transfer belt 10 into contact with the photosensitive drums 1y-1k and to separate the intermediate transfer belt 10 from the photosensitive drums 1y-1k. For example, when forming a monochrome image, the transfer rollers 51y, 51m, and 51c are moved to separate the intermediate transfer belt 10 from the photosensitive drums 1y to 1c.

[0032] In the image forming apparatus described above, a transfer material P is fed from a feed cassette 80, passes through a registration roller 82, and then passes through a secondary transfer nip (not shown) formed by the intermediate transfer belt 10 and a secondary transfer roller 52. At this time, a transfer voltage of +2.0 kV is applied to the secondary transfer roller 52, so that the toner image on the intermediate transfer belt 10 can be transferred onto the transfer material P. After the toner image is transferred from the surface of the intermediate transfer belt 10 onto the transfer material P, any residual toner remaining on the surface of the intermediate transfer belt 10 is positively charged by a charge-imparting brush 90 serving as a charge-imparting member. Then, in the primary transfer nip portion (width: approximately 1.5 mm), the toner is retransferred onto the photosensitive drums 1y to 1k and removed by cleaning blades 61y to 61k as the photosensitive drums 1y to 1k are rotated.

[0033] The transfer material P onto which the toner image has been transferred is then heated and pressurized in the fixing device 70, and the toner image is fixed onto the transfer material P. This completes the formation of a four-color full-color image, and the sheet material P is discharged outside the image forming apparatus main body.

[0034] [Engine Controller Configuration] The engine controller 104 that controls the image forming operation will be described with reference to FIG.

[0035] 3 is a block diagram showing the control unit of the engine controller 104. The engine controller 104 has an engine control unit 301 and an engine mechanism unit 302. The engine mechanism unit 302 operates in accordance with various instructions from the engine control unit 301.

[0036] The exposure system 308 of the engine mechanism section 302 is a part that controls the exposure devices 3y to 3k shown in Fig. 2. The exposure system 308 turns on the lasers of the exposure devices 3y to 3k in accordance with a laser drive signal that indicates the laser exposure time sent from the video controller 103.

[0037] The image forming system 309 is a part that controls the operations described above in [Image Forming Operation]. It executes the image forming operation in response to a print request from the host computer 101. The image forming system 309 also has a high-voltage power supply circuit that generates various biases (high voltages) required for image formation.

[0038] The paper feed / transport system 310 is a part that controls the feeding and transport of the transfer material P, and is composed of various transport system motors, a paper feed cassette 80 or a paper feed tray (not shown), a paper feed roller 81, various transport rollers including a paper discharge roller (not shown), etc. The paper feed / transport system 310 feeds and transports the transfer material P from the paper feed cassette 80 or a paper feed tray (not shown) in accordance with the operation of the image forming system 309.

[0039] The sensor system 311 is a group of sensors that collect information necessary for the CPU 303 and ASIC 304 to control the exposure system 308, the image forming system 309, and the paper feed / transport system 310. This group of sensors includes a temperature sensor for the fixing device 70, a density sensor that detects the density of the toner image formed on the photosensitive drums 1y to 1k, the intermediate transfer belt 10, or the transfer material P, a sensor that detects color misregistration, a paper size sensor, a paper leading edge detection sensor, a paper transport detection sensor, etc. The information detected by the sensor system 311 is acquired by the CPU 303 and reflected in the control of the print sequence.

[0040] The CPU 303 of the engine control unit 301 uses the RAM 305 as a main memory and work area, and controls the engine mechanism unit 302 in accordance with various control programs stored in the nonvolatile storage unit 306. The system bus 312 has an address bus and a data bus. The components of the engine control unit 301 and the engine mechanism unit 302 are connected to the system bus 312 and are accessible to each other.

[0041] When the CPU 303 receives a print execution command from the video controller 103 via the engine interface unit 307, it first drives the image forming system 309 and charges the surfaces of the photosensitive drums 1y-1k with the charging rollers 2y-2k. The CPU 303 generates and outputs a laser drive signal to drive the laser / scanner system 308, and forms an electrostatic latent image on the photosensitive drum 22 with the scanner unit 24.

[0042] Next, CPU 303 drives image forming system 309, causing developing devices 40y-40k to develop the electrostatic latent images and form monochromatic toner images. These monochromatic toner images are sequentially transferred to intermediate transfer belt 10 as a primary transfer, superimposing the images to form a multicolor toner image of Y, M, C, and K on intermediate transfer belt 10. At the same time, CPU 303 controls paper feed / transport system 310, causing paper feed roller 81 to feed transfer material P from paper feed unit 80, and transferring this multicolor toner image onto transfer material P. Thereafter, CPU 303 controls fixing unit 30 to fix the multicolor toner image on transfer material 11.

[0043] The ASIC 304 controls each motor and high-voltage power supplies such as developing bias when executing various print sequences in accordance with instructions from the CPU 303. The ASIC 304 may be responsible for some or all of the functions of the CPU 303, or the CPU 303 may be responsible for some or all of the functions of the ASIC 304. Alternatively, separate dedicated hardware may be provided, and some of the functions of the CPU 303 and ASIC 304 may be performed by that dedicated hardware.

[0044] [Video Controller Configuration] An example configuration of the video controller 103 will be described using FIG. 4. The CPU 401 is a CPU that controls the entire video controller 103. The non-volatile memory unit 402 is a storage means that stores various control codes executed by the CPU 401 and data used for control. The memory unit 402 can be configured, for example, with a ROM, an EEPROM, or a hard disk. The RAM 403 is a temporary storage memory that functions as the main memory or work area of ​​the CPU 401. The host interface unit 404 is a unit that communicates print data and control data from the host computer 101. The print data received by the host interface unit 404 is stored in the RAM 403. The print data may be bitmap data that has undergone halftone processing by the host computer 101 or the like, or may be PDL (page description language) data. PDL data is data written in a page description language to create page image data. The print data typically includes rendering commands for data such as characters, graphics, and photographs. The DMA control unit 407 transfers data from the RAM 403 to the engine interface unit 409 and the data processing unit 406 in response to instructions from the CPU 401. The data processing unit 406 performs various data processing (e.g., estimating toner consumption) on the image data in the RAM 403 in response to instructions from the CPU 401. The detailed operation of the data processing unit 406 will be described later. The operation / display unit 408 is provided in the main body of the image forming apparatus 102, and receives various settings and instructions input from the user and displays various information about the image forming apparatus 102. The engine interface unit 409 is an input / output unit for signals to the printer engine 104. For example, the engine interface unit 409 sends a laser drive signal output from the data processing unit 406 to the printer engine 104.

[0045] The toner amount management unit 405 updates the remaining amount of toner in the process cartridge based on the toner consumption amount for each page notified from the data processing unit 406, and displays the updated amount on the operation / display unit 408. The toner amount management unit 405 may notify the host computer 101 of the remaining amount of toner via the host interface unit 404.

[0046] The density correction processing unit 411 performs density correction processing in response to an instruction from the CPU 401 or an instruction from the printer engine 104 via the engine interface unit 409, and generates a gradation correction table to be used during density correction in a density correction unit 503 (described later). The detailed operation of the density correction processing unit 411 will be described later.

[0047] The system bus 410 has an address bus and a data bus. The above-mentioned components are connected to the system bus 410 and are accessible to each other. The functions of the data processing unit 406 may be realized as an ASIC (application-specific integrated circuit) or dedicated hardware, or some or all of the functions may be performed by the CPU 401. Furthermore, some or all of the functions of the video controller 103 may be performed by an external device such as the host computer 101.

[0048] [Toner supply operation] Here, the operation of supplying toner to the cleaning blades 61y to 61k for the purpose of lubrication will be described.

[0049] In this embodiment, in order to reduce the frictional force between the cleaning blades 61y-61k and the surfaces of the photosensitive drums 1y-1k, the engine controller 104 executes an operation of supplying toner to the surfaces of the photosensitive drums 1y-1k while the image forming operation is not being performed (when no image is being formed). Examples of the period when the image forming operation is not being performed include the pre-rotation and post-rotation of the photosensitive drums 1y-1k. In particular, when unused cleaning units 60y-60k are installed, the toner supply process is performed to allow the unused cleaning blades 61y-61k and the surfaces of the photosensitive drums 1y-1k to slide smoothly against each other.

[0050] The specific operation will be described below.

[0051] When toner is supplied for lubrication purposes, a toner image having a predetermined width in the rotation direction is formed over the entire width (axial direction) of a specific photosensitive drum 1 (in this embodiment, the description will continue using the Bk photosensitive drum 1k as an example) while the photosensitive drums 1y to 1k are rotating. Hereinafter, the toner supplied for lubrication purposes will be referred to as a supply toner image.

[0052] As shown in Figure 7, the supply toner image in this embodiment is four horizontal lines (lines parallel to the axial direction) 1 mm wide in the rotational direction and spaced 70 mm apart, the same as the spacing between the photosensitive drums 1y to 1k. Note that this width in the rotational direction can be changed depending on the amount of toner to be supplied, and if it is desired to change the amount of toner to be supplied, this can be adjusted by increasing or decreasing the exposure time. Note that the supply toner image is not limited to the one shown in Figure 7, and may be one in which toner is placed over the entire image forming area. In other words, the supply toner image is not particularly limited as long as it can supply toner to the surfaces of the photosensitive drums 1y to 1k.

[0053] In this way, the supply toner image formed on the surface of the photosensitive drum 1k is primarily transferred onto the intermediate transfer belt 10 at the primary transfer nip portion (not shown) by applying a transfer voltage of the opposite polarity to that of the supply toner image by the primary transfer roller 51. In the description of this embodiment, the polarity of the supply toner image is negative charge, and the primary transfer voltage is positive charge.

[0054] The supply toner image transferred onto the intermediate transfer belt 10 is carried on the rotating intermediate transfer belt 10 and then rotates once around the intermediate transfer belt 10, transporting it again to the primary transfer nip for each color. During this transport, the supply toner image is given a positive charge by a charging brush 90, which serves as a charging member and is installed downstream in the direction of rotation of the intermediate transfer belt 10, thereby changing the supply toner image from a negative charge to a positive charge. In other words, the charging brush 90 can give the supply toner image on the intermediate transfer belt 10 a charge of a polarity opposite to the charge polarity of the toner.

[0055] When the positively charged supply toner images return to the primary transfer nip, a positive voltage is applied again to the primary transfer rollers 51y to 51k, causing the images to be re-transferred onto the photosensitive drums 1y to 1k of the respective colors.

[0056] The re-transferred supply toner image is transported by the rotating photosensitive drums 1y to 1k to the contact area with the cleaning blades 61y to 61k. In this way, the supply toner image is interposed between the photosensitive drums 1y to 1k and the cleaning blades 61y to 61k and acts as a lubricant, thereby reducing frictional force.

[0057] Furthermore, the charge brush 90 is configured to impart a charge of a polarity opposite to the charge polarity of the toner to the secondary transfer residual toner remaining on the intermediate transfer belt even during normal image formation. The secondary transfer residual toner charged by the charge brush 90 is retransferred to the drum when passing through the primary transfer section during normal image formation (during primary transfer), and is configured to be collectable by a blade provided in the process cartridge.

[0058] [Control flow of toner supply operation] Next, the control flow of the toner supply operation in this embodiment will be explained using Figure 5. As mentioned above, if toner used for lubrication purposes is used infrequently and no external additives adhere to the toner matrix surface, the amount of external additives supplied to the interface between the cleaning blade and the image carrier surface will be small. As a result, it is not possible to sufficiently reduce the friction force between the cleaning blade and the image carrier surface. In other words, it is desirable to use frequently used toner as a lubricant. Therefore, the control flow of the toner supply operation in this embodiment is configured as follows. That is, based on information on the amount of toner used by the user (information on toner usage), one of the photosensitive drums 1y to 1k is selected to form a supply toner image, and the toner supply operation is executed. Information on toner usage includes the number of times the process cartridge has been replaced and a pixel count value (for example, the total number of pixels in image data or the total amount of laser light emitted).

[0059] The control flow described below is controlled by the engine controller 104.

[0060] When the engine controller 104 requests the toner supply process, the control flow starts while the image forming operation is not being performed (during non-image formation). In this embodiment, the explanation continues after the image forming operation is completed (during post-rotation).

[0061] S101 is a process for acquiring the number of times the process cartridge for each color has been replaced. Specifically, this process involves reading out the number of times the process cartridge for each color has been replaced, which is stored in the memory unit 306 of the engine controller 104. Once the number of times the process cartridge has been replaced has been read out, the process proceeds to S102. Here, the memory unit 306 functions as an acquisition unit that acquires information regarding the amount of toner used.

[0062] In step S102, the process cartridge that has been replaced the most is selected based on the number of times each color process cartridge has been replaced. If there is one process cartridge that has been replaced the most (YES), the process proceeds to step S103. If there are multiple process cartridges that have been replaced the most (NO), the process proceeds to step S104.

[0063] In S103, one of the process cartridge toners selected in the process of S102 is determined to be the one to form the supplied toner image. Once the process cartridge is determined, the process proceeds to S106.

[0064] Meanwhile, in S104, the pixel count is read in order to narrow down the multiple process cartridges selected in the process of S102 to one. Specifically, the engine controller 104 reads the pixel count value stored in the memory device of the process cartridge. Once the pixel count values ​​have been read from the multiple process cartridges, the process proceeds to S105.

[0065] In S105, the pixel counts of the multiple process cartridges read in S104 are compared, and the process cartridge with the largest pixel count value (the largest amount of toner used) is determined as the process cartridge that will form the supplied toner image. Once the process cartridge is determined, the process proceeds to S106.

[0066] S106 is a process for executing the aforementioned toner supply operation using the specific toner cartridge determined in S103 or S105. As described above, in this embodiment, the controller 104, which serves as a control unit, can execute the following toner supply operation based on the information stored in the storage unit 306. That is, the controller 104 can execute a supply operation in which a supply toner image formed in one process cartridge is supplied as a lubricant to the blades of another process cartridge based on the information stored in the storage unit 306. Specifically, when the timing for supplying the supply toner image arrives, the controller 104 develops the supply toner image from the developing device of the one process cartridge based on the information stored in the storage unit 306. The controller 104 then transfers the supply toner image formed in the one process cartridge to the intermediate transfer belt 10. The supply toner image transferred to the intermediate transfer belt 10 is then positively charged by the charging brush 90, retransferred at the primary transfer unit of the other process cartridge, and supplied as a lubricant to the blades of the other process cartridge.

[0067] As described above, this embodiment makes it possible to suppress the generation of abnormal noise and maintain good cleaning performance by continuing to reduce the frictional force between the cleaning blade and the image carrier surface more stably, regardless of how the user uses it.

[0068] [Variations] Another embodiment (modified example) of the present invention will be described. In this modified example, when K toner is used frequently and color toners (YMC) are used infrequently, two types of toner supply operations are selected and executed depending on how the user uses the device. Specifically, a method for determining the photosensitive drums 1y to 1k for forming the supplied toner image will be described using print information printed by the user (more specifically, the number of times a color image is printed (number of prints) and the number of times a black-and-white image (monochrome image) is printed (number of prints)). Note that the "overall configuration of the image forming apparatus," "image forming operation," "configuration of the engine controller," and "configuration of the video controller" are the same as those in the previously described embodiment, so their explanation will be omitted and only the differences will be described.

[0069] [Modification of Toner Supply Operation] Here, a modified example of the operation of supplying toner to the cleaning blades 61y to 61k for the purpose of lubrication will be described.

[0070] The toner supply operation of this modified example has two types: a toner supply operation (pattern A) that is performed using only the black photosensitive drum 1k, and a toner supply operation (pattern B) that is performed using the photosensitive drums 1y to 1k of all colors. Note that the toner supply operation of pattern A is the same as that described in the embodiment, so a description thereof will be omitted. Furthermore, the execution timing of the toner supply operation of pattern B is the same as that of pattern A, so a description thereof will also be omitted.

[0071] The toner supply operation of pattern B will be explained further below.

[0072] In this operation, the transfer rollers 51y-51k are moved to positions where they separate the intermediate transfer belt 10 from the photosensitive drum 1. That is, the transfer rollers 51y-51k are moved to positions where they are separated from the intermediate transfer belt 10. When supplying toner for lubrication purposes, a toner image having a predetermined width in the rotation direction is formed across the entire width (axial) area of ​​all the photosensitive drums 1y-1k while the photosensitive drums 1y-1k are rotating. Hereinafter, this toner image will be referred to as a supply toner image. The supply toner image in this modification has a width of 1 mm in the rotation direction. Note that this width in the rotation direction can be changed depending on the amount of toner to be supplied, and if the amount of toner to be supplied needs to be changed, it can be adjusted by increasing or decreasing the exposure time.

[0073] In this way, the supply toner images formed on the surfaces of the photosensitive drums 1y-1k that supply toner pass through the primary transfer nip portion (not shown) and are conveyed to the cleaning blades 61y-61k while remaining on the photosensitive drums 1y-1k. In this way, the supply toner images are interposed between the photosensitive drums 1y-1k and the cleaning blades 61y-61k and act as a lubricant, thereby reducing frictional force.

[0074] [Modification of the control flow of the toner supply operation] Next, we will explain the control flow of the toner supply operation in this modified example using Figure 6. As mentioned above, if toner used for lubrication purposes is used infrequently and no external additives adhere to the toner matrix surface, the amount of external additives supplied to the interface between the cleaning blade and the image carrier surface will be small. As a result, it is not possible to sufficiently reduce the friction force between the cleaning blade and the image carrier surface. In other words, it is desirable to use frequently used toner as a lubricant. Therefore, in this modified example, the printing information printed by the user (more specifically, the number of times a color image and a black and white image have been printed) is used to determine whether the supplied toner image will be formed on the four-color photosensitive drums 1y to 1k or on the Bk photosensitive drum 1k, and toner supply control is performed accordingly.

[0075] The control flow described below is controlled by the engine controller 104.

[0076] When the engine controller 104 requests the toner supply process, the control flow starts while the image forming operation is not being performed (during non-image formation). In this modified example, the explanation will continue after the image forming operation is completed (during post-rotation).

[0077] S201 is a process for acquiring the number of prints made by the user. More specifically, the engine controller 104, which serves as an acquisition unit, acquires information on the number of prints made in color (cumulative number of prints) and the number of prints made in black and white (cumulative number of prints) from the storage unit 306. After acquiring each number of prints, the process proceeds to S202.

[0078] S202 is a process for deriving the color / black and white ratio R from the number of color prints and the number of black and white prints acquired in S201 using the following formula (1): After the color / black and white ratio R has been calculated, the process proceeds to S203.

[0079]

number

[0080] S203 is a process for selecting the above-mentioned toner supply operation pattern based on the color / black and white ratio R calculated in S202. The details are determined by the following equation (2). R<1 …(2)

[0081] That is, if the number of color prints is less than the number of black-and-white prints (YES), the process proceeds to S204 and the operation of toner supply pattern A is executed. That is, supply toner is formed by the black process cartridge and this supply toner is supplied to the other process cartridges. On the other hand, if the number of color prints is greater than the number of black-and-white prints (NO), the process proceeds to S205 and the operation of toner supply pattern B is executed.

[0082] As described above, this modified example makes it possible to continue to reduce the frictional force between the cleaning blade and the image carrier surface more stably, regardless of how the user uses it, thereby suppressing the generation of abnormal noise and maintaining good cleaning performance.

[0083] In this manner, in this embodiment, the toner supply pattern is controlled based on the color / black-and-white ratio. While the color / black-and-white ratio is calculated based on the cumulative number of prints (cumulative number of printed sheets) in this embodiment, this is not limiting. For example, it may be calculated based on the number of image forming jobs executed. That is, the color / black-and-white ratio may be calculated based on the number of color print jobs and the number of black-and-white print jobs. The color / black-and-white ratio may also be calculated based on the amount of toner used during color printing (pixel count value) and the amount of toner used during monochrome printing (pixel count value).

[0084] In addition, in this embodiment, the toner supply operation (pattern B) has been described as an operation in which supply toner is formed from the developing devices of the process cartridges of all colors, but this is not limited to this. For example, a supply toner image may be formed by at least one of the process cartridges for colors other than black, and then supplied to the other process cartridges. [Explanation of symbols]

[0085] P Transfer material 1 Photosensitive drum 2 Charging roller 3 Exposure equipment 10 Intermediate transfer belt 51 Primary transfer roller 40 Developing device 60 Cleaning Device 90 Charge application brush 102 Image forming device 103 Video Controller 104 Engine Controller

Claims

1. a plurality of process cartridges each including an image carrier that carries a toner image, a developing device that develops a latent image formed on the image carrier with toner, and a blade that cleans the toner remaining on the image carrier; a common drive source for driving the plurality of process cartridges; an intermediate transfer belt onto which a toner image formed on each image carrier of the plurality of process cartridges is transferred and which transfers the transferred toner image onto a recording material; a charge applying member to which a voltage of a polarity opposite to the charge polarity of the toner is applied, and which is capable of applying a charge of a polarity opposite to the charge polarity of the toner to the transfer residual toner on the intermediate transfer belt; a control unit that is capable of executing a supply operation in which, during non-image formation, supply toner developed by the developing device of one of the process cartridges is transferred to the intermediate transfer belt, the charge applying member applies a charge to the supply toner, and then the supply toner is transferred to the image carrier of another process cartridge, and the supply toner is supplied to the blade of another process cartridge; an acquisition unit that acquires information about the toner usage amounts of the plurality of process cartridges, An image forming apparatus characterized in that, when performing the supply operation, the control unit controls the supply operation based on the information acquired by the acquisition unit so that the supply toner is supplied from the developing device of the process cartridge that uses the largest amount of toner among the multiple process cartridges.

2. 2. The image forming apparatus according to claim 1, wherein the information regarding the amount of toner used is determined by the number of times the process cartridge has been replaced and a pixel count.

3. a plurality of process cartridges each including an image carrier that carries a toner image, a developing device that develops a latent image formed on the image carrier with toner, and a blade that cleans the toner remaining on the image carrier; a common drive source for driving the plurality of process cartridges; an intermediate transfer belt onto which a toner image formed on each image carrier of the plurality of process cartridges is transferred and which transfers the transferred toner image onto a recording material; a charge applying member to which a voltage of a polarity opposite to the charge polarity of the toner is applied, and which is capable of applying a charge of a polarity opposite to the charge polarity of the toner to the transfer residual toner on the intermediate transfer belt; a first supply operation in which, during non-image formation, supply toner developed by the developing device of a black process cartridge among the plurality of process cartridges is transferred to the intermediate transfer belt, the charge applying member applies charge to the supply toner, and then the supply toner is transferred to the image carrier of another process cartridge, and the supply toner is supplied to the blade of the other process cartridge; a control unit capable of executing a plurality of supply operations, including a second supply operation in which, in a non-image forming state, a supply toner image is developed on the image carrier from the developing device in each process cartridge while the plurality of process cartridges are spaced from the intermediate transfer belt, and the supply toner image is supplied to the blade; an acquisition unit that acquires information about the toner usage amounts of the plurality of process cartridges, The image forming apparatus is characterized in that the control unit selects a supply operation to be executed from the plurality of supply operations based on the information acquired by the acquisition unit.

4. 4. The image forming apparatus according to claim 3, wherein the control unit determines which supply operation to execute from among a plurality of supply operations based on the number of color images to be printed and the number of monochrome images to be printed.

5. 5. The image forming apparatus according to claim 4, wherein the control unit executes the first supply operation when the cumulative number of prints of the color image is less than the cumulative number of prints of the monochrome image, and executes the second supply operation when the cumulative number of prints of the color image is greater than the cumulative number of prints of the monochrome image.

Images