JP2007079004A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a user's convenience by shortening time required for return by carrying out a reverse bias control only when there is a possibility of toner sticking to a secondary transfer roller in a return process of an image forming apparatus after releasing of jamming. <P>SOLUTION: Developer removal control removing developer attached to a transfer means is not performed in the image forming apparatus after detection of a jamming release by a jamming release detection means in response to the jamming occurring when the transfer means is separated from an intermediate transfer body. However the developer removal control is performed after detection of jamming release by a jamming release detection means in response to the jamming occurring when the transfer means comes into contact with the intermediate transfer body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to processing when JAM occurs in an image forming apparatus such as a copying machine, and more particularly to reverse bias control for removing toner adhering to a transfer unit during JAM return processing.

  2. Description of the Related Art Conventionally, some image forming apparatuses such as copying machines and printers using an electrophotographic system perform image formation using a belt-like intermediate transfer member (hereinafter referred to as “intermediate transfer belt”). In this type of image forming apparatus, an electrostatic latent image formed on a photosensitive member is developed with toner, and a toner image visualized thereby is transferred to an intermediate transfer belt, and then the toner image on the intermediate transfer belt is transferred to a recording material ( A method of batch transfer to paper) is adopted. This method is generally called an “intermediate transfer method”.

  In a full-color copying machine, printer, or the like that employs such an intermediate transfer method, toner images of a plurality of colors, for example, four color toner images of Y (yellow), M (magenta), C (cyan), and K (black) are used. One color image is formed by sequentially superimposing and transferring on the intermediate transfer belt. On the running path of the intermediate transfer belt, a “primary transfer position” that is a transfer position of the toner image from the photosensitive member to the intermediate transfer belt and a “secondary” that is a transfer position of the toner image from the intermediate transfer belt to the recording material. "Transfer position" is provided, and a transfer roller is disposed in each of them. Among these, the transfer roller disposed at the primary transfer position is supported in pressure contact with the surface of the photoconductor via the intermediate transfer belt, and the transfer roller disposed at the secondary transfer position moves the intermediate transfer belt from the inner peripheral side. It is supported so that it can contact and separate with respect to the backup roller to support. At the secondary transfer position, the transfer roller is pressed against the surface side of the intermediate transfer belt supported by the backup roller (the surface on which the toner image is transferred) through the paper. In this state, the backup roller and By applying a transfer bias to one or both of the transfer rollers, the toner image on the image carrier belt is transferred to the surface of the recording material.

  However, when the image forming operation is interrupted due to the recording material clogging on the conveyance path during the formation of the toner image on the photosensitive member or the intermediate transfer member, that is, the occurrence of a jam, the toner image is not printed. It may adhere directly to the transfer roller at the next transfer position, which may cause the backside of the recording material to be conveyed next.

  As a countermeasure against this, as described in Japanese Patent Laid-Open No. 9-6146, when a jam is released, a bias having a polarity opposite to that during normal transfer is applied to either the backup roller or the transfer roller at the secondary transfer position. A reverse bias control is known in which toner applied to the secondary transfer roller is applied to one or both of the toner and applied to an intermediate transfer belt, and the toner is cleaned using a cleaning device for the intermediate transfer belt.

  However, in the case of the conventional configuration, since the reverse bias control is always performed in the restoration process of the image forming apparatus performed after the jam is released, there is a problem that the restoration process takes extra time.

  In order to solve the above problem, in the present invention, reverse bias control is necessary in the restoration processing of the image forming apparatus after the jam is released-only when toner may be attached to the secondary transfer roller-. The purpose is to shorten the time required for the return and to improve the convenience for the user.

  In order to achieve this object, the present invention has a photosensitive member, an intermediate transfer member, and transfer means for transferring a developed image formed on the intermediate transfer member to a recording material, and the transfer means is the intermediate transfer member. The transfer means is separated from the intermediate transfer body when a developed image is formed on the intermediate transfer body, and the transfer means is moved to the intermediate transfer body when transferring the developed image to a recording material. In an image forming apparatus which can be controlled to contact a transfer body, a storage means for storing whether the transfer means is located at a position where it is in contact with the intermediate transfer body or a place where the transfer means is located, a jam detection means, a jam Release detection means, developer removal control means for removing the developer attached to the transfer means, jam release detection means according to a jam that occurs when the transfer means is separated from the intermediate transfer body After detecting that the jam has been released, the operation of the developer removal control unit is prohibited, and the jam release detection unit is in response to a jam that occurs when the transfer unit is in contact with the intermediate transfer member. And a control unit that permits the operation of the developer removal control unit after detecting that the jam is released.

  According to the present invention, it is possible to reduce the time required for the return by performing the reverse bias control only when necessary in the return processing of the image forming apparatus after the jam release, and the convenience for the user is improved.

  First, the overall configuration of the image forming apparatus according to the present embodiment will be described.

  FIG. 1 is a configuration diagram showing a schematic internal structure of the image forming apparatus 100. The image forming apparatus 100 includes a digital color image reader unit (hereinafter abbreviated as “reader unit”) 150 that forms the upper part of the casing, and a digital color image printer unit (hereinafter abbreviated as “printer unit”) that forms the lower part of the casing. ) 170 and a document feeder 180 attached to the upper part of the reader unit 150, and is configured as a copier having an image reading function and an image forming function, for example, for forming a color image.

  In addition, the image forming apparatus 100 performs arbitrary post-processing such as a post-processing device (for example, punch processing for punching a recording material, stapling processing for binding recording materials, and bookbinding processing for binding a plurality of recording materials and attaching a cover sheet). The image forming apparatus main body is attached to the image forming apparatus main body so that the post-processing as described above can be performed on the recording material on which image formation has been completed. The image forming apparatus 100 is also configured to transmit and receive data to and from an external device such as a host computer via a network communication interface unit (not shown).

  The reader unit 150 includes a document table glass 101, a scanner unit 102 including a document illumination lamp 103 and a scanning mirror 104, a scanning mirror 105, a scanning mirror 106, a lens 107, a full color image sensor unit 108, and the like.

  The document table glass 101 is used as a table for placing a document fed by the document feeding device 180 or a document set manually. The scanner unit 102 is driven by a motor (not shown) and reciprocates in a predetermined direction. The document illumination lamp 103 is a light source that emits light that irradiates the document. When the scanner unit 102 scans the document placed on the document table glass 101, the document illumination lamp 103 passes the reflected light image of the light irradiated on the document through the scanning mirrors 104 to 106, and passes through the lens 107. An image is formed on the CCD sensor in the full-color image sensor unit 108 formed integrally with the RGB three-color separation filter to obtain a color color separation image analog signal. The color separation image analog signal is digitized through amplification processing by an amplification circuit (not shown).

  The printer unit 170 includes an exposure control unit 109, a photosensitive drum 111, a cleaning device 112, a pre-exposure lamp 113, a primary charger 114, a black developing device 115, a rotating color developing device 116, an intermediate transfer belt 117, and a primary transfer charger 118. The image forming unit 110 includes a cleaning device 121.

  The exposure control unit 109 includes a semiconductor laser that is a laser light generation unit, a polygon scanner, and the like. The exposure control unit 109 converts the image signal that has been converted into an electrical signal by the color image sensor unit 108 of the reader unit 150 and subjected to predetermined image processing. Based on this, modulated laser light is generated, and the photosensitive drum 111 which is an image carrier is irradiated with the laser light.

  The photosensitive drum 111 is driven to rotate counterclockwise in the figure by a motor (not shown), is neutralized by a pre-exposure lamp 113, and is uniformly charged to a predetermined potential by a primary charger 114, and then exposed. An electrostatic latent image is formed on the surface of the photosensitive drum upon irradiation with laser light emitted from the control unit 109. A toner image is formed on the photosensitive drum 111 by developing the electrostatic latent image formed on the photosensitive drum 111 by operating a predetermined developing device. The photosensitive drum 111 has a property that, during development, toner does not adhere to a portion that has been irradiated with laser light, and toner adheres to a portion that has not been irradiated with laser light. That is, the stronger the laser beam irradiated on the photosensitive drum 111, the thinner the toner, and vice versa.

  The rotating color developing device 116 includes developing devices 122, 123, and 124 corresponding to yellow, magenta, and cyan colors, respectively. When developing a color or black-and-white toner image on the photosensitive drum 111, in the case of a color image, the rotating color developing device 116 is rotated by a motor (not shown), and a developing device corresponding to each separation color to be developed. In the case where development is performed by selectively bringing a predetermined developing device among 122 to 124 close to the photosensitive drum 111 and black development is performed, a black developing device 115 disposed close to the photosensitive drum 111 is used. Develop using. For black and white images, only the black developing device 115 is used.

  The toner image developed on the photosensitive drum 111 is primarily transferred to the intermediate transfer belt 117 by a bias (primary transfer bias) applied by the primary transfer charger 118. In the case of color image formation, four color toner images are primarily transferred onto the intermediate transfer belt 117, and in the case of monochrome image formation, only the black toner image is primarily transferred to the intermediate transfer belt 117. In this embodiment, when the longitudinal dimension of the recording material to be image-formed is equal to or less than ½ of the entire circumference of the intermediate transfer belt 117, two recording materials on the intermediate transfer belt 117 are used. It is possible to simultaneously form an image on a region corresponding to the above. After the completion of the primary transfer, the photosensitive drum 111 is subjected to an image forming process again after the residual toner on the surface is cleaned by a blade (not shown) provided in the cleaning device 112.

  In addition to the above components, the printer unit 170 further includes a registration roller 137, a secondary transfer roller 138, a conveyance belt 139, a heat roller fixing device (hereinafter abbreviated as a fixing device) 140, a paper discharge flapper 141, and a right cassette deck 125. , Left cassette deck 126, upper cassette deck 127, lower cassette deck 128, transport path 147, transport path 142, reverse path 143, lower transport path 144, refeed path 145, refeed roller 146, discharge roller 148, manual feed A tray 160 and the like are provided.

  Each of the cassette decks 125 to 128 stores a recording material for secondary transfer of the toner image formed on the intermediate transfer belt 117 in the image forming unit 110. The recording material stored in the right cassette deck 125 is fed by a pickup roller 129 and a paper feed roller 133, and is moved to a secondary transfer position where a toner image on the intermediate transfer belt 117 is transferred to the recording material by a registration roller 137. Be transported. Similarly, the recording material in the left cassette deck 126 is fed by the pickup roller 130 and the paper feed roller 134, and the recording material in the upper cassette deck 127 is fed by the pickup roller 131 and the paper feed roller 135. The recording material 128 in the lower cassette deck 128 is fed by a pickup roller 132 and a paper feed roller 136 and is conveyed to a secondary transfer position by a registration roller 137, respectively. In the case of manual paper feed, a manual paper feed roller 161 is used.

  In the image forming unit 110, after the primary transfer of the toner image on the photosensitive drum 111 to the intermediate transfer belt 117, the toner image is conveyed from one of the cassette decks 125 to 128 to the position of the registration roller 137. The recording material is further conveyed to the position of the secondary transfer roller 138 which is the secondary transfer position, and the toner image on the intermediate transfer belt 117 is applied to the bias (2 which is applied via the secondary transfer roller 138 in accordance with this. Secondary transfer to the recording material is performed by the secondary transfer bias). After the secondary transfer, the intermediate transfer belt 117 is subjected to the image forming process again after the residual toner on the surface is cleaned by a blade (not shown) provided in the cleaning device 121.

  In the present embodiment, the gap between the intermediate transfer belt 117 and the secondary transfer roller 138 can be arbitrarily set by operating an eccentric cam (not shown) at a desired timing. When forming a color image, a gap is provided when a toner image of a plurality of colors is formed on the intermediate transfer belt 117, and the gap is eliminated when the toner image is secondarily transferred to a recording material. When forming a black and white image, no gap is provided. In addition, a gap is provided during standby or when the power is turned off. Details of the attachment / detachment control of the secondary transfer roller 138 during the image forming operation will be described later with reference to FIG.

  After the secondary transfer is completed, the recording material passes through the secondary transfer roller 138 and is then conveyed by the conveyor belt 139. The toner transferred onto the recording material pressurizes and heats the recording material in the fixing device 140. Then, the sheet is conveyed by a conveyance path 147 and discharged by a discharge roller 148 to a recording material discharge unit (not shown) provided outside the image forming apparatus 100.

  The paper discharge flapper 141 switches the discharge destination of the recording material on which the toner is fixed to the conveyance path 142 side or the discharge roller 148 side. When an image is formed on only one side of the recording material, the discharge flapper 141 is set on the discharge roller 148 side. When forming images on both sides of the recording material, the discharge flapper 141 is set on the conveyance path 142 side, the recording material conveyed by the conveyance path 142 is conveyed to the lower conveyance path 144 via the reverse path 143, Guide to the paper feed path 145. At this time, the recording material is turned over by passing through the reverse path 143 and the lower transport path 144. When the recording material is turned over and discharged from the image forming apparatus 100, the discharge flapper 141 is set on the conveyance path 142 side, the recording material is drawn into the reversing path 143, the reversing roller is reversed, and the recording material is discharged to the discharging roller. To 148.

  The document feeder 180 includes a document stacking unit on which a document bundle to be copied is stacked, a feeding mechanism that feeds documents one by one from the document bundle loaded in the document stacking unit, and the like. This is used when the originals are automatically exchanged (a series of processes of feeding the originals one by one from the original bundle onto the original platen glass 101 and discharging the originals when the reading of the originals is completed is repeated for the number of originals).

  Next, the control means will be described.

  FIG. 2 is a block diagram showing the control means of this embodiment. In the figure, a reader unit 800 is a processing unit that controls a document feeder 180 and an image reader 150, and is a processing unit that mainly supplies a document and reads an image. A CPU 801 is a central processing unit (hereinafter referred to as a CPU) that controls the entire reader unit. A ROM 802 is a read-only memory that stores a control procedure (control program) for the document feeder 180 and the image reader 150. The CPU 801 controls each component device of the document feeder 180 and the image reader 150 according to the control procedure stored in the ROM 802. A RAM 803 is a random access memory which is a main storage device used as a storage area for input data, a working storage area, and the like. An I / O 805 is an input / output IC that inputs a control signal output from the CPU 801 to a load such as a motor and a signal from a sensor or the like and sends the signal to the CPU 801. The image processing unit 806 performs shading correction on the image data read by the CCD, and performs control for transmission to the controller unit 820 described later.

  The controller unit 820 performs overall control of the copying apparatus main body 100 while giving instructions to the reader unit 150 and the printer unit 170. A CPU 821 is a central processing unit (hereinafter referred to as a CPU) that controls the entire copying apparatus main body 100. A ROM 822 is a read-only memory that stores a control procedure (control program) for the copying apparatus main body 100. The CPU 821 Each component device of the copying apparatus main body 100 is controlled according to the control procedure stored in the ROM 822. A RAM 823 is a random access memory which is a main storage device used as a storage area for input data, a working storage area, or the like. The CPU 821 accepts input from various keys of the operation unit 860 via the bus and appropriate I / O, and sends it out to display necessary information on the display on the panel. The SRAM 825 is a RAM for holding data such as adjustment values and the total number of prints that must be held even after the main power is turned off, and a battery (not shown) is connected to back up the contents. An image processing unit 825 is a processing unit that processes image data transmitted from the reader unit 800 or an external device (not shown), and performs processing such as scaling, image data compression, and decompression. Also, image data to be printed is transmitted to a printer unit 170 described later.

  The printer unit 840 is a processing unit that controls the printer unit 170, and performs a series of processes related to image formation on a recording material, that is, conveyance control of the recording material, formation and development of a latent image, transfer to the recording material, Fix it. The CPU 841 is a central processing unit (hereinafter referred to as CPU) that controls the entire printer unit 840, and the ROM 843 is a read-only memory that stores a control procedure (control program) of the printer unit 170. Each component device of the printer 170 is controlled in accordance with the stored control procedure. A RAM 844 is a random access memory that is a main storage device used as a storage area for input data, a working storage area, or the like. An I / O 845 is an input / output IC that inputs a control signal output from the CPU 841 to a load such as a motor and a signal from a sensor or the like and sends the signal to the CPU 841.

  Hereinafter, toner removal control of the transfer roller 138 characterizing the present invention will be described with reference to FIGS. The control here is executed as a program stored in the ROM 843 in the printer control unit 840.

  FIG. 3 is a diagram illustrating attachment / detachment control of the secondary transfer roller 138 during the image forming operation. (A) in FIG. 3 shows a case where the length in the conveyance direction of the recording material to be image formed is ½ or less of the entire length of the intermediate transfer belt 117. As described above, in such a case, images corresponding to two recording materials are formed on the intermediate transfer belt 117. The vertical lines in the figure indicate the time required for the intermediate transfer belt 117 to make a half turn. First, the yellow (Y1) image corresponding to the first recording material is formed, and the intermediate transfer belt 117 makes a half turn. When it reaches the stage, the yellow (Y2) image corresponding to the second recording material is formed. Then, when the intermediate transfer belt 117 reaches one stage, the magenta (M1) image corresponding to the first recording material is formed so as to overlap the previous Y1, and from the M1 image formation to the intermediate transfer belt. Is further half a circle, a magenta (M2) image corresponding to the second recording material is formed so as to overlap Y2. The cyan (C1, C2) and black (K1, K2) images are overlapped in the same manner. While the four color images are superimposed on the intermediate transfer belt in this way, the secondary transfer roller 138 is in a position separated from the intermediate transfer belt 117, but the image corresponding to the first recording material is secondary. The secondary transfer roller is brought into contact with the intermediate transfer belt immediately before reaching the transfer position (position of the secondary transfer roller 138), and a transfer bias is applied. As a result, transfer to the recording material conveyed to this position is performed at the same timing as when the image reaches the secondary transfer position. The secondary transfer roller 138 may be separated from the intermediate transfer belt 117 from the end of the transfer to the first recording material to before the start of the transfer to the second recording material. Then, after the transfer to the second recording material is finished, it is separated to prepare for the secondary transfer of the next image. (B) shows the case where the length in the conveyance direction of the recording material to be image formed exceeds 1/2 of the entire circumference of the intermediate transfer belt 117, and (c) shows the secondary transfer roller 138 in the case of forming a black monochrome image. The attachment / detachment control is shown. In (b), the same control as in (a) is performed except that the number of images formed at one time corresponds to one recording material. In (c), the secondary transfer roller is always in contact with the intermediate transfer member 117.

  FIG. 4 is a schematic diagram illustrating a jam detection method. On the recording material conveyance path in the printer unit 170 of the image forming apparatus 100, the minimum length of the recording material that can be handled by the image forming apparatus 100 with respect to the recording material conveyance direction so that the position of the recording material in the apparatus can be seen. Sensors are arranged at intervals not exceeding (not shown). As shown in S1 and S2 in FIG. 4, the sensor mainly uses a flag type sensor, but another type of sensor such as an optical type may be used. The jam to be detected can be broadly classified into two types: a delayed jam (FIG. 4-a) and a staying jam (FIG. 4-b). The delay jam has passed a predetermined time from when the recording material 401 is fed from one of the cassette decks (125, 126, 127, 128) or detected by the sensor S1 having the leading end of the recording material. Is also detected by the fact that it is not detected by the next sensor S2 on the transport path. The stagnant jam is not detected when the trailing edge of the recording material 401 is detected from the sensor S1 with the leading edge of the recording material 401 even after a predetermined time has elapsed (the input of the sensor S1 does not turn OFF). Detect with. When a jam is detected, the contact / separation state of the secondary transfer roller 138 at that time is stored in the RAM 844 in the printer unit, and the operation unit 860 indicates that a jam has occurred and is jammed in the machine. The user is prompted to remove the recording material. Further, it is considered that the jam is released because any sensor on the conveyance path stops detecting the recording material. The restoration process of the image forming apparatus 100 after the jam is released will be described later with reference to FIG.

  FIG. 5 is a diagram illustrating a configuration of the secondary transfer roller. The secondary transfer roller 501 in the figure is the same as the secondary transfer roller 138 shown in FIG. The secondary transfer roller 501 has a positive bias (a in the figure) as a secondary transfer bias for transferring toner to the recording material and a reverse bias (as a cleaning bias for removing toner adhering to the secondary transfer roller). In the figure, b) can be switched and applied. During normal image formation, a secondary transfer bias is applied during secondary transfer to transfer the toner image formed on the intermediate transfer body 117 to the recording material. However, a jam occurs and the toner is transferred to the secondary transfer roller. When there is a possibility that the toner adheres, the toner attached to the secondary transfer roller 501 is applied to the intermediate transfer belt 117 by applying a reverse bias, and the toner is further provided to the blade provided in the cleaning device 121. Clean (not shown).

  FIG. 6 is a flowchart showing the timing for carrying out the reverse bias control. When the print job is started (S601), counting by the timer is started at the timing when the recording material is fed or the leading edge of the recording material is detected by the sensor on the conveyance path, and the delay or the stay jam is detected. (S602). If printing ends without jamming (S609), the print job ends (S610). If a jam is detected in S602, whether the secondary transfer roller 138 is in the contact position or the separation position at that time is stored in the RAM 844 in the printer unit (S603), and then whether the jam is released by the user Detection of whether or not is started (S604). When the jam is released, that is, when any sensor on the conveyance path no longer detects the recording material, the image forming apparatus 100 is returned (S605). Specifically, the return processing includes control of temperature adjustment of the fixing device 140, initial alignment of the rotary color developing device 116, toner remaining amount check, cleaning of the primary charger 114, cleaning of the intermediate transfer belt 117, and the like. The Next, the position of the secondary transfer roller 138 at the time of jam occurrence is determined with reference to the RAM 844 in the printer unit (S606), and if it is in the abutting position, reverse bias control is performed to adhere to the secondary transfer roller 138. The toner that is being used is supplied to the intermediate transfer belt 117 and cleaned by the cleaning device 121 (S607), and the subsequent return processing is continued (S608). If the secondary transfer roller 138 is at a separated position in S606, the reverse bias control is not performed and the subsequent return processing (S608) is continued. The return processing at this stage is specifically configured by control such as image density adjustment, alignment of the intermediate transfer belt 117, and the like. When the series of return processing from S606 to S608 is completed, the printing operation interrupted by the jam is resumed, and the processing returns to the previous processing of S602.

1 is a diagram showing a schematic internal structure of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing control means of an image forming apparatus according to an embodiment of the present invention. The figure which shows secondary transfer roller control during image formation operation Diagram showing the jam detection method The figure which shows the structure of the secondary transfer roller which applies a forward bias and a reverse bias. Flow chart showing the timing for performing reverse bias control

Claims (1)

A photosensitive member, an intermediate transfer member, and a transfer unit that transfers a developed image formed on the intermediate transfer member to a recording material, the transfer unit being capable of contacting and separating from the intermediate transfer member; In the image forming apparatus in which the transfer unit is separated from the intermediate transfer member when forming a developed image thereon, and the transfer unit is in contact with the intermediate transfer member when transferring the developed image to a recording material. ,
Storage means for storing whether the transfer means is located at a position where it is in contact with the intermediate transfer member or located away from the intermediate transfer body;
Jam detection means,
Jam release detection means,
Developer removal control means for removing the developer attached to the transfer means;
In response to a jam that occurs when the transfer unit is separated from the intermediate transfer member, the jam removal detection unit detects that the jam has been removed and prohibits the operation of the developer removal control unit, Control means for allowing the operation of the developer removal control means after detecting that the jam is released by the jam release detecting means in response to a jam that occurs when the transfer means is in contact with the intermediate transfer member. An image forming apparatus comprising:

Images