JP2004341235A - Image forming apparatus and image forming method - Google Patents

Abstract

Provided is an image forming apparatus and an image forming method capable of reliably preventing blade turning even when a new image carrier is used.
When a new photoconductor attached to the apparatus main body is detected by a photoconductor new / old detection sensor, an initialization operation (step S3) is performed prior to an image density control operation (step S4) and an actual printing operation. ) To deposit toner in the deposition space. That is, a charging toner image is formed on the photoconductor by controlling a charging bias (a charging potential for toner accumulation) and a developing bias (a developing potential for toner accumulation). Then, the toner image for deposition formed as described above is moved to the cleaning section as it is, and the toner constituting the toner image for deposition is scraped off by the blade and deposited on the deposition space.
[Selection] Fig. 6

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus and an image forming method for scraping toner remaining on an image carrier such as a photoreceptor by a cleaning blade, and in particular, a contact portion formed by the cleaning blade and the image carrier being in contact with each other; The present invention relates to a technique for scraping toner remaining on an image carrier by a cleaning blade in a state where toner is deposited near the contact portion.
[0002]
[Prior art]
2. Description of the Related Art In an electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile machine, a toner image is formed on an image carrier such as a photoreceptor, and then the toner image is copied into a copy sheet, a transfer sheet, a sheet, and a transparent sheet for an OHP. Etc. are transferred to a sheet. An apparatus in which a cleaning blade is brought into contact with the surface of an image carrier to clean and remove toner remaining on the image carrier when the transfer process is performed is known (see Patent Document 1).
[0003]
In the apparatus described in Patent Document 1, a photoconductor blade (cleaning blade) is provided, and the toner (residual toner) remaining on and adhered to the outer peripheral surface of the photoconductor is scraped off. Further, in this apparatus, a sheet for scooping the toner that is scraped off by the blade and dropping, and a depositing unit that deposits the dropping toner are provided. For this reason, the toner scraped off by the blade is always deposited on the contact portion between the photoreceptor and the blade for the photoreceptor and immediately below the contact portion. The action of the thus deposited toner as a lubricant prevents the blade from being turned.
[0004]
[Patent Document 1]
JP 2001-42721 A ([0016] [0026], FIG. 2)
[0005]
[Problems to be solved by the invention]
By the way, when a new photoconductor is used, when the photoconductor is mounted on the apparatus main body, the toner is not deposited on the contact portion and directly below the contact portion, and the lubricant action of the deposited toner cannot be obtained. Therefore, in the conventional apparatus, a lubricant such as polyvinylidene fluoride is previously applied to the surface of the blade in order to prevent the blade from being turned up at the beginning of use. That is, in a printing operation for a while after the new photoconductor is mounted on the apparatus main body, the blade is prevented from being turned up by a lubricant previously applied to the surface of the blade, and the toner is brought into contact with the contact portion by the printing operation. When the toner is deposited immediately below, the blade is prevented from being turned up by the lubricant action of the deposited toner.
[0006]
However, there is a limit to the amount of lubricant applied to the blade surface, and the blade may be turned during the initial stage of use after replacement with a new photoreceptor, that is, immediately after the replacement and until toner is deposited on a contact portion. There is. In addition, it is conceivable that toner is deposited on a contact portion of the new photoconductor, but when the new photoconductor is transported or transported to a user or the like, the accumulated toner may scatter and contaminate the surroundings. There is. Therefore, it is practically impossible to supply the accumulated toner to the new photoconductor in advance.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an image forming apparatus and an image forming method that can reliably prevent the blade from being turned when a new image carrier is used.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to the present invention has an image carrier that rotates in a predetermined rotation direction while carrying a toner image, and remains on the image carrier in contact with the surface of the image carrier. A cleaning blade for scraping the toner, a contact portion between the image carrier and the cleaning blade, and a depositing means for depositing the toner scraped off by the cleaning blade in the vicinity of the contact portion, and whether the image carrier is new. Detecting means for detecting whether the image carrier is new, and performing an initializing operation for accumulating toner near the contact portion and the contact portion when the detection device detects that the image carrier is new. .
[0009]
In the invention configured as described above, the detection unit detects whether the image carrier is new. Then, when a new image carrier is detected, an initialization operation is performed, and toner is deposited near the contact portion and the contact portion. Therefore, regardless of whether the image carrier is brand-new or not, the deposited toner is present in the vicinity of the contact portion between the image carrier and the cleaning blade and in the vicinity of the contact portion. The turning of the blade is reliably prevented. That is, the toner is always supplied to the contact portion between the rotating image carrier and the cleaning blade without being affected by the image pattern formed on the image carrier. Since the toner has a function as a lubricant, the presence of the toner reduces a frictional force between the blade and the surface of the image carrier, and makes it difficult for the blade to be turned.
[0010]
Here, a developing unit that forms a toner image on an image carrier such as a photoconductor may be used in order to perform an initialization operation and deposit toner near the contact portion and the contact portion. In this type of image forming apparatus, a developing unit is provided to form an image. Therefore, a toner image for deposition may be formed on the image carrier by the developing means, and the toner constituting the toner image for deposition may be deposited as the deposited toner in the contact portion and in the vicinity of the contact portion. That is, in the initialization operation, toner is supplied to the image carrier over the entire width of the toner carrier in a direction substantially orthogonal to the rotation direction of the toner carrier, and a toner image for deposition having the same width as the toner carrier is deposited on the image carrier. At the same time, the toner constituting the toner image for deposition may be scraped off by a cleaning blade and deposited on the contact portion and the vicinity of the contact portion. By doing so, the toner can be uniformly deposited over at least the width region (the entire width region of the toner carrier) related to image formation in the contact portion. As a result, it is possible to more reliably prevent the blade from being turned up by the toner existing in the contact portion.
[0011]
The length of the toner image for deposition formed as described above, that is, the length in the rotation direction of the image carrier is arbitrary, but it is desirable to consider the following points. That is, the amount of toner carried on the toner carrier may be uneven in the rotation direction of the toner carrier, but the length of the toner image for deposition is shorter than the circumferential length of the toner carrier in the rotation direction. In some cases, the amount of deposited toner may fluctuate greatly due to uneven toner on the toner carrier. On the other hand, when the length of the toner image for deposition is set to be equal to or greater than the circumference of the toner carrier, there is a sufficient amount of toner for suppressing the influence of uneven toner on the toner carrier and preventing the blade from turning. Can be deposited. As a result, even when toner unevenness occurs on the toner carrier, sufficient toner can be accumulated and blade turning can be more reliably prevented.
[0012]
Further, even when toner image unevenness occurs in the rotation direction of the image carrier with respect to the toner image carried on the image carrier, there is the same effect as the effect of the toner unevenness on the toner carrier. Therefore, if the length of the toner image for deposition in the rotation direction of the image carrier is set to be equal to or greater than the circumference of the image carrier, the influence of unevenness of the toner image on the image carrier is suppressed, and the blade is prevented from turning. Sufficient toner can be deposited. As a result, even when toner image unevenness occurs on the image carrier, sufficient toner can be deposited and blade turning can be more reliably prevented.
[0013]
Further, in order to form a toner image for deposition, it is necessary to form a latent image corresponding to the toner image for deposition on the image carrier, and this latent image is formed without using (i) an exposure unit. Or (ii) it may be formed by using exposure means.
[0014]
As the former (i), charging means is provided between the cleaning blade and the developing means in the rotation direction of the image carrier, and is provided so as to be able to charge the surface of the image carrier from which residual toner has been scraped off by the cleaning blade. Charging control means for controlling the surface potential of the image carrier by adjusting the charging bias applied to the charging means; and supplying toner from the toner carrier to the image carrier by adjusting the developing bias applied to the toner carrier. And a developing control unit for controlling the developing bias.In the initialization operation, the latent image corresponding to the toner image for deposition is formed by controlling the charging bias, and the toner is attached to the latent image by controlling the developing bias. Thus, a toner image for deposition may be formed. When forming a toner image for deposition in this manner, the toner image for deposition can be formed by simple control without operating the exposure unit.
[0015]
On the other hand, the latter (ii) further includes an exposing means for exposing the surface of the image carrier with a light beam to form a latent image. At the same time, the toner may be attached to the latent image by the developing means to form a toner image for deposition. When the toner image for deposition is formed in this manner, an arbitrary image pattern can be formed as the toner image for deposition.
[0016]
In this type of image forming apparatus, a density control factor that affects image density is set to a predetermined value to form a patch image, and the density control factor is adjusted based on the image density of the patch image. It is known that density control is performed as needed. In such an image forming apparatus, when the detection unit detects that the image carrier is new, an initialization operation may be performed prior to performing image density control. Thus, even when a new image carrier is used, image density control can be performed while reliably preventing blade turning, and image density control can be performed satisfactorily.
[0017]
Furthermore, in order to achieve the above object, the image forming method according to the present invention provides a method in which a cleaning blade and an image carrier are brought into contact with each other and a toner is deposited near the contact portion. In an image forming apparatus for scraping toner remaining on an image carrier by a cleaning blade, when the image carrier is new, an initializing operation of accumulating toner near the contact portion and the contact portion is performed. I have.
[0018]
According to the invention configured as described above, when the image carrier is new, the initialization operation is performed, and the toner is deposited near the contact portion and the contact portion. Therefore, regardless of whether the image carrier is brand-new or not, the deposited toner is present in the vicinity of the contact portion between the image carrier and the cleaning blade and in the vicinity of the contact portion. The turning of the blade can be reliably prevented.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus 1 forms a full-color image by superimposing four color toners of yellow (Y), magenta (M), cyan (C), and black (K), or using only black (K) toner. The image forming apparatus forms a monochrome image. In the image forming apparatus 1, when an image signal is given to the main controller 11 from an external device such as a host computer in response to an image forming request from a user, the engine controller 10 By controlling each part of the EG, an image corresponding to the image signal is formed on the sheet S.
[0020]
In the engine unit EG, a photoconductor 22 corresponding to the “image carrier” of the present invention is provided rotatably in the arrow direction D1 in FIG. A charging unit 23, a rotary developing unit 4, and a cleaning unit 25 are arranged around the photoconductor 22 along the rotation direction D1. The charging unit 23 receives the application of the charging bias from the charging control unit 103 and uniformly charges the outer peripheral surface of the photoconductor 22 to a predetermined surface potential. The photoconductor 22, the charging unit 23, and the cleaning unit 25 integrally form the photoconductor cartridge 2. As will be described later, the photoconductor cartridge 2 is integrally detachable from the apparatus 1 main body. Has become.
[0021]
The light beam L is emitted from the exposure unit 6 toward the outer peripheral surface of the photoconductor 22 charged by the charging unit 23. The exposure unit 6 forms an electrostatic latent image corresponding to an image signal by exposing the light beam L on the photoconductor 22 in accordance with a control command given from the exposure control unit 102. For example, when an image signal is supplied from an external device such as a host computer to the CPU 111 of the main controller 11 via the interface (I / F) 112, the CPU 101 of the engine controller 10 sends the image signal to the exposure control unit 102 at a predetermined timing. Is output from the exposure unit 6 on the photosensitive member 22 in response to the control signal, and an electrostatic latent image corresponding to the image signal is formed on the photosensitive member 22.
[0022]
The electrostatic latent image thus formed is developed by the developing unit 4 with toner. That is, in this embodiment, the developing unit 4 is configured so as to be rotatable about an axis, a rotation driving unit (not shown), and detachably attached to the support frame 40 so that the toner of each color can be detached. Is provided with a developing unit 4Y for yellow, a developing unit 4M for magenta, a developing unit 4C for cyan, and a developing unit 4K for black. The developing unit 4 is controlled by a developing device control unit 104 as shown in FIG. Then, based on a control command from the developing device control section 104, the developing unit 4 is driven to rotate, and the developing devices 4Y, 4C, 4M, and 4K are selectively brought into contact with the photoconductor 22 or a predetermined gap. Is positioned at a predetermined developing position opposed to the developing position. Further, by applying a developing bias from the developing device controller 104 to the developing roller 41 of the developing device positioned at the developing position, the toner carried on the surface of the developing roller 41 from the developing roller 41 to the photosensitive member 22 is applied. Supply. As a result, the electrostatic latent image on the photoconductor 22 is visualized with the selected toner color.
[0023]
The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer area TR1. The transfer unit 7 includes an intermediate transfer belt 71 stretched over a plurality of rollers 72 to 75, and a driving unit (not shown) that rotates the roller 73 to rotate the intermediate transfer belt 71 in a predetermined rotation direction D2. It has. When the color image is to be transferred to the sheet S, the color images are formed by superimposing the toner images of the respective colors formed on the photoreceptor 22 on the intermediate transfer belt 71, and are taken out of the cassette 8 and transported. The color image is secondarily transferred onto the sheet S conveyed along F to the secondary transfer area TR2. Further, the sheet S on which the color image is formed is conveyed via the fixing unit 9 to a discharge tray provided on the upper surface of the apparatus main body.
[0024]
In the vicinity of the roller 75, an intermediate transfer belt cleaning unit 76, a vertical synchronization sensor 77, and a density sensor 60 are disposed. Of these, the cleaning unit 76 can be moved toward and away from the roller 75 by an electromagnetic clutch (not shown). The blade of the cleaning unit 76 contacts the surface of the intermediate transfer belt 71 wrapped around the roller 75 while moving to the roller 75 side, and remains on the outer peripheral surface of the intermediate transfer belt 71 after the secondary transfer. Remove the toner. The vertical synchronization sensor 77 is a sensor for detecting a reference position of the intermediate transfer belt 71, and is for obtaining a synchronization signal output in association with the rotation driving of the intermediate transfer belt 71, that is, a vertical synchronization signal Vsync. Functions as a vertical synchronization sensor. In this apparatus, the operation of each section of the apparatus is controlled based on the vertical synchronization signal Vsync so that the operation timing of each section is aligned and the toner images formed in each color are accurately overlapped. Further, the density sensor 60 is provided to face the surface of the intermediate transfer belt 71, and measures the optical density of a toner image as a patch image formed on the outer peripheral surface of the intermediate transfer belt 71 as necessary.
[0025]
In FIG. 2, reference numeral 78 denotes a photoconductor new / old detection sensor for detecting whether the photoconductor cartridge 2 is new or not, and corresponds to a “detection unit” of the present invention. In this embodiment, the state of the photoreceptor new / old fuse (not shown) provided in the photoreceptor cartridge 2 configured as described below is detected to detect the new and old of the photoreceptor 22. Reference numeral 113 denotes an image memory provided in the main controller 11 for storing an image provided from an external device such as a host computer via the interface 112, and reference numeral 106 denotes an arithmetic program executed by the CPU 101 and an engine unit. A ROM for storing control data for controlling the EG and the like, and a reference numeral 107 denotes a RAM for temporarily storing a calculation result in the CPU 101 and other data.
[0026]
FIG. 3 is an external perspective view of the image forming apparatus of FIG. FIG. 4 is a diagram showing a configuration of a photoreceptor cartridge of the image forming apparatus of FIG. FIG. 5 is a partially enlarged view of the photoreceptor cartridge of FIG. The configuration of the photoreceptor cartridge 2 will be described with reference to these drawings. In the photoreceptor cartridge 2, the photoreceptor 22, the charging unit 23 and the cleaning unit 25 are integrally attached to the cartridge main body 20, and are detachable from the main body of the apparatus 1.
[0027]
In this image forming apparatus 1, as shown in FIG. 3, an openable / closable external cover 121 is provided on a side surface of the apparatus main body 120. When a user or a service engineer opens the external cover 121, the apparatus main body 120 is opened. The side surface of the photoreceptor cartridge 2 is exposed through the photoreceptor opening 122 provided in the cartridge. Then, the lock is released by rotating the lock lever 123 for fixing the photoreceptor cartridge 2 in the arrow direction D3, and the photoreceptor cartridge 2 can be pulled out along the (+ X) direction in FIG. Further, by inserting the photosensitive member cartridge 2 in the (-X) direction in FIG. 3 through the photosensitive member opening 122, a new photosensitive member cartridge 2 can be mounted on the apparatus main body 120. Then, the photoreceptor cartridge 2 is fixed by the lock lever 123. When the photoreceptor cartridge 2 is mounted in this way, the photoreceptor opening 122 is substantially closed by the side surface of the photoreceptor cartridge 2. Although not shown in the drawings, the cartridge main body 20 is provided with a fuse for discriminating between a new photoconductor and an old photoconductor. When the photosensitive member 22 is new, the fuse for determining whether the photosensitive member is new or old is in an initial state. When the new photoreceptor cartridge 2 is mounted in the apparatus main body 120 as described above, the photoreceptor new / old discriminating fuse is pressed against an engaging portion (not shown) provided in the apparatus main body 120 to be mechanically cut. Is done. Such a state of the photoconductor new / old discrimination fuse is detected by the photoconductor new / old detection sensor 78, so that it is possible to detect whether the photoconductor cartridge 2 (photoconductor 22) mounted on the apparatus main body 120 is new. I have.
[0028]
Further, as shown in FIG. 4, the cleaning unit 25 includes a photoconductor blade (cleaning blade) 251 that scrapes off toner (residual toner) remaining on the outer peripheral surface of the photoconductor 22, and the blade 251. The storage unit 252 includes a deposition unit 252 for depositing the scraped toner, a receiving unit 253 that receives the toner overflowing from the upper end of the deposition unit 252, and a case 254.
[0029]
The blade 251 has its base end fixed to the blade holder 255, while its tip (edge) 251 a is in contact with the surface of the photoconductor 22. Therefore, the toner remaining on the photoreceptor 22 can be scraped off at the contact portion CP. In addition, a sheet-like deposition portion 252 is attached to the blade side surface opposite to the contact portion CP. The deposition unit 252 is attached to the blade 251 such that the upper end 252a of the deposition unit 252 projects above the tip 251a of the blade 251. For this reason, a space SP surrounded by the photoconductor 22, the tip 251a of the blade 251 and the upper end 252a of the deposition unit 252 is formed as a deposition space for depositing toner. For this reason, the toner T scraped off by the blade 251 is constantly deposited in the deposition space SP as shown in FIG. 5B. As described above, in this embodiment, the contact portion CP and the toner T can be deposited in the vicinity of the contact portion CP, and the deposition portion 252 functions as the “deposition means” of the present invention. .
[0030]
Reference numeral 256 in FIG. 5 is a regulation sheet that regulates the accumulation of the toner T on the accumulation space SP more than necessary. By providing the regulation sheet 256, the amount of accumulated toner can be kept constant.
[0031]
FIG. 6 is a flowchart showing the operation in the image forming apparatus of FIG. In the image forming apparatus 1, the photoconductor cartridge 2 is detachable from the apparatus main body 120, and a user or a service engineer replaces the photoconductor cartridge 2 as necessary. Therefore, the engine controller 10 controls each unit of the apparatus in accordance with a control program stored in the ROM 106 in advance, so that replacement of the photosensitive cartridge 2 can be appropriately dealt with. That is, when the engine controller 10 detects the mounting of the photoreceptor cartridge 2 on the apparatus main body 120 by a detection sensor (not shown) provided on the apparatus main body 120 (step S1), the photoreceptor 22 is initialized as necessary. The operation (step S3) and the image density control operation (step S4) are executed. Hereinafter, the operation of the image forming apparatus 1 will be described with reference to FIGS.
[0032]
When the photoreceptor cartridge 2 is mounted on the apparatus main body 120, it is detected whether or not the photoreceptor cartridge 2 (photoreceptor 22) mounted on the apparatus main body 120 is new based on an output signal from the new and old photoreceptor detection sensor 78. (Step S2). If the mounted photoreceptor cartridge 2 is not new, that is, if the photoreceptor cartridge 2 removed from the apparatus main body 120 is remounted, the toner T is deposited in the deposition space SP as shown in FIG. Therefore, the image density control operation (step S4) is executed without executing the initialization operation (step S3) described below. In this embodiment, the image density control operation (step S4) is always performed after the photoreceptor cartridge 2 is mounted. However, if the photoreceptor cartridge 2 is not a new one, the image density control operation is performed as necessary. May be performed.
[0033]
On the other hand, if the mounted photoreceptor cartridge 2 is new, an initialization operation (step S3) is performed. That is, in the new photoconductor cartridge 2, as shown in FIG. 5A, the toner T is not accumulated in the accumulation space SP. Therefore, prior to the image density control operation (step S4) and the normal printing operation, an initialization operation (step S3) described below is executed to deposit toner in the accumulation space SP.
[0034]
In this initialization operation, as shown in FIG. 7A, the charging control unit 103 applies a charging bias (charging potential for toner accumulation) different from that during normal printing during the timing t1 to t2, so that the photosensitive member 22 is charged. Is uniformly charged to a potential Vat different from the surface potential Va0 during normal printing (step S31). As a result, an electrostatic latent image LI (FIG. 7B) corresponding to a later-described accumulation toner image is formed on the photoconductor 22.
[0035]
On the other hand, by applying a developing bias (developing potential for toner accumulation) from the developing device controller 104 to the developing roller 41 of the developing device positioned at the developing position, the surface potential of the developing roller 41 is set to the potential Vbt ( Step S32). As a result, an amount of toner corresponding to the contrast potential Vcon (= | Vbt−Vat |) is supplied from the developing roller 41 to the photoconductor 22, and the electrostatic latent image LI on the photoconductor 22 is visualized with the selected toner color. As a result, a toner image TI for deposition is formed. The shape, size, and the like of the deposition toner image TI formed in this embodiment will be described later in detail.
[0036]
In addition, in the image forming apparatus 1, the deposition toner image TI thus formed is moved to the cleaning unit 25 without being primarily transferred to the intermediate transfer belt 71. Then, the toner constituting the toner image TI for accumulation is scraped off by the blade 251 and accumulated in the accumulation space SP (FIG. 5B).
[0037]
In the next step S4, a conventionally well-known image density control operation is performed. In other words, a small test image (patch image) having a predetermined image pattern is formed with each developing bias while changing and setting a density control factor that affects image density, for example, a developing bias in multiple stages. Further, the image density of each patch image is detected by the density sensor 60, and the optimum value of the developing bias is obtained based on the detection result. Then, when a print command is given, the developing bias is set to an optimum value to form an image.
[0038]
As described above, according to this embodiment, when the photoconductor 22 is detected as new by the photoconductor new / old detection sensor 78, initialization is performed prior to the image density control operation (step S4) and the actual printing operation. The operation (step S3) is executed to deposit the toner T in the deposition space SP. Also, the initialization operation is not executed while the photoconductor 22 is not new by the photoconductor new / old detection sensor 78. This is because the toner T is always deposited in the space SP. That is, after the initialization operation, the image density control operation (step S4), the printing operation, and the like are performed continuously or intermittently. At this time, the residual toner on the photoconductor 22 is scraped off by the blade 252, It is supplied to the deposition space SP. Therefore, regardless of whether the photosensitive member cartridge 2 is new or not by performing the initialization operation, the contact portion CP between the photosensitive member 22 and the cleaning blade 252 and the vicinity of the contact portion CP, that is, in the deposition space SP, The presence of the deposited toner T makes it possible to reliably prevent the blade 252 from being turned up by the action of the toner T as a lubricant. That is, the toner T is always supplied to the contact portion CP between the rotating photoconductor 22 and the cleaning blade 252 without being affected by the image pattern formed on the photoconductor 22. As a result, the frictional force between the blade 252 and the surface of the photoreceptor 22 is reduced by the lubricant action of the toner T, so that the occurrence of the blade turning 252 can be effectively prevented.
[0039]
Further, since the toner T is present in the accumulation space SP before the image density control operation (step S4) as described above, the contact state between the blade 252 and the photoconductor 22 becomes exactly the same as that of normal printing. A density control factor that affects image density can be satisfactorily adjusted. As a result, the quality of an image formed by normal printing can be improved.
[0040]
Further, in this embodiment, as shown in FIG. 7B, the width W of the toner image for deposition TI coincides with the entire width of the developing roller 41, so that the toner constituting the toner image for deposition TI is cleaned by the cleaning blade 251. And the toner T is accumulated in the accumulation space SP (in the vicinity of the contact portion CP and the contact portion CP), so that the toner T is spread over at least the width region (the entire width region of the developing roller 41) related to image formation in the contact portion CP. It can be deposited uniformly. As a result, the blade T can be more reliably prevented from being turned by the toner T existing in the contact portion CP.
[0041]
Further, in forming the deposition toner image TI, only the charging bias and the developing bias are controlled without operating the exposure unit 6. Here, the exposure unit 6 may be operated to form a latent image LI on the photoconductor 22 corresponding to the toner image TI for deposition. On the other hand, in the above embodiment, since it is not necessary to operate the exposure unit 6, the device control can be simplified accordingly.
[0042]
In the above-described embodiment, the width W of the toner image TI for deposition in a direction (direction X in FIG. 7B) substantially orthogonal to the rotation direction of the photoconductor 22 and the developing roller 41 has been examined in detail. It is desirable to set the length TL in the direction (the direction Y in FIG. 7B) as follows. That is, the amount of toner carried by the developing roller 41 may be non-uniform in the rotation direction of the developing roller 41 as described above. Here, if the length TL of the accumulation toner image TI is shorter than the circumferential length of the developing roller 41, the amount of accumulated toner may fluctuate largely due to uneven toner on the developing roller 41. On the other hand, when the length TL of the toner image TI for deposition is set to be equal to or longer than the circumferential length of the developing roller 41, it is sufficient to suppress the influence of uneven toner on the developing roller 41 and prevent the blade from turning. The proper toner T can be deposited in the deposition space SP. As a result, even when toner unevenness occurs on the developing roller 41, sufficient toner T is accumulated in the accumulation space SP, so that blade turning can be more reliably prevented. Therefore, it is desirable to adjust the timings t1 and t2 to set the length TL of the accumulation toner image TI to be equal to or longer than the circumference of the developing roller 41.
[0043]
Further, even when the toner image TI carried on the photoconductor 22 has uneven toner images in the rotation direction D1 of the photoconductor 22, the same effect as the toner unevenness on the developing roller 41 has exists. . Therefore, if the length TL of the toner image TI for deposition in the rotation direction D1 of the photoconductor 22 (the direction Y in FIG. 7B) is equal to or longer than the circumference of the photoconductor 22, Sufficient toner T can be deposited in the deposition space SP in order to suppress the effect of uneven toner image and prevent the blade from turning. As a result, even when the toner image unevenness on the photoconductor 22 occurs, a sufficient amount of the toner T is accumulated in the accumulation space SP, and the turning of the blade can be more reliably prevented. Therefore, it is desirable to adjust the timings t1 and t2 to set the length TL of the deposition toner image TI to be equal to or longer than the circumference of the photoconductor 22.
[0044]
Note that the present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above embodiment, the present invention is applied to the cleaning unit 25 that scrapes the residual toner on the photoconductor 22. However, the cleaning unit 25 that scrapes the residual toner on the intermediate transfer body such as the intermediate transfer belt 71 is used. The present invention may be applied to this. In the above embodiment, the case where the image carrier (photoconductor) is cylindrical has been described. However, the present invention can be applied to a case where the image carrier is belt-shaped.
[0045]
In the above embodiment, the deposition space SP is formed by attaching the sheet-shaped deposition portion 252 to the photoconductor blade (cleaning blade) 251. However, the configuration (deposition means) for forming the deposition space SP is not limited thereto. The present invention is not limited to this. For example, a configuration may be used in which a plurality of members are combined and the scraped toner is deposited as in an apparatus described in Patent Literature 1.
[0046]
Further, in the above-described embodiment, the photoconductor new / old discrimination fuse is detected to detect that the photoconductor 22 is new. However, the detection of a new photoconductor is not limited to this. A memory storing information on the old and new photoconductors may be mounted to detect that the photoconductor is new based on the information stored in the memory.
[0047]
Further, in the above embodiment, the present invention is applied to the image forming apparatus 1 that can form a color and monochrome image, but the present invention can be applied to an image forming apparatus dedicated to monochrome. Although the image forming apparatus 1 is a printer, the image forming apparatus includes all image forming apparatuses such as a copying machine and a facsimile machine.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus of FIG. 1;
FIG. 3 is an external perspective view of the image forming apparatus of FIG.
FIG. 4 is a diagram illustrating a configuration of a photoreceptor cartridge of the image forming apparatus of FIG. 1;
FIG. 5 is a partially enlarged view of the photoreceptor cartridge of FIG.
FIG. 6 is a flowchart illustrating an operation in the image forming apparatus of FIG. 1;
FIG. 7 is a diagram showing an initialization operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photoconductor cartridge, 4 ... Developing unit (developing means), 4Y, 4M, 4C, 4K ... Developing device (developing means), 6 ... Exposure unit (exposure means), 22 ... Photoconductor ( 23: charging unit (charging unit), 25: cleaning unit, 41: developing roller (toner carrier), 78: photoconductor new / old detection sensor (detection unit), 103: charging control unit, 104: development 251: cleaning blade, 252: stacking unit, CP: contact unit, LI: latent image, SP: stacking space, T: toner, TI: toner image for stacking

Claims (8)

An image carrier that rotates in a predetermined rotation direction while carrying the toner image,
A cleaning blade that scrapes off toner remaining on the image carrier in contact with the surface of the image carrier,
A contact portion between the image bearing member and the cleaning blade and in the vicinity of the contact portion, a depositing unit that deposits the toner scraped off by the cleaning blade;
Detecting means for detecting whether the image carrier is new or not,
When the detecting means detects that the image carrier is new, the image forming apparatus performs an initialization operation for depositing toner in the contact portion and in the vicinity of the contact portion. A toner carrier that rotates while carrying toner, and a developing unit that supplies toner from the toner carrier to the image carrier to form a toner image on the image carrier;
In the initialization operation, toner is supplied to the image carrier over the entire width of the toner carrier in a direction substantially orthogonal to the rotation direction of the toner carrier, and a toner image for deposition having the same width as the toner carrier is formed. 2. The image forming apparatus according to claim 1, wherein the toner is formed on the image carrier, and the toner constituting the toner image for stacking is scraped off by the cleaning blade and is deposited on the contact portion and the vicinity of the contact portion. 3. The image forming apparatus according to claim 2, wherein in the initialization operation, the length of the toner image for deposition in the rotation direction of the image carrier is equal to or longer than the circumference of the toner carrier. 3. The image forming apparatus according to claim 2, wherein in the initialization operation, the length of the deposition toner image in the rotation direction of the image carrier is equal to or longer than the circumference of the image carrier. 4. Charging means disposed between the cleaning blade and the developing means in the direction of rotation of the image carrier and provided so as to be able to charge the surface of the image carrier on which residual toner has been scraped off by the cleaning blade;
Charge control means for controlling the surface potential of the image carrier by adjusting the charging bias applied to the charging means,
A development control unit that controls a toner supply from the toner carrier to the image carrier by adjusting a development bias applied to the toner carrier;
In the initialization operation, a latent image corresponding to the toner image for deposition is formed by controlling the charging bias, and toner is adhered to the latent image by controlling the developing bias so that the toner for deposition is controlled. The image forming apparatus according to claim 2, which forms an image. Further comprising an exposure unit for exposing the surface of the image carrier with a light beam to form a latent image,
In the initialization operation, a latent image corresponding to the toner image for deposition is formed by the exposure unit, and toner is attached to the latent image by the developing unit to form the toner image for deposition. 5. The image forming apparatus according to any one of 2 to 4. A density control factor affecting image density is set to a predetermined value to form a patch image, and the density control factor is adjusted based on the image density of the patch image to perform image density control as needed. Item 7. The image forming apparatus according to any one of Items 1 to 6,
An image forming apparatus that executes the initialization operation before performing the image density control when the detection unit detects that the image carrier is new. A contact portion formed by the cleaning blade and the image carrier being in contact with each other, and image formation in which toner remaining on the image carrier is scraped by the cleaning blade in a state where toner is deposited near the contact portion In the device,
When the image carrier is brand new, an initialization operation for depositing toner in the contact portion and in the vicinity of the contact portion is performed.

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