JP2006091728A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing image defects, reducing the down-time of the apparatus to improve productivity at a user, and reducing the consumption of consumables such as toner. <P>SOLUTION: The image forming apparatus comprising an intermediate transfer body, an intermediate transfer body cleaning means and a decision means for deciding toner quantity on the intermediate transfer body is provided with a plurality of cleaning modes, i.e. an intermediate transfer body cleaning mode to be periodically operated at different timing or periods and an intermediate transfer body cleaning mode to be irregularly operated. At the time of executing at least one intermediate transfer body cleaning mode, the execution timing of the other intermediate transfer body cleaning mode is changed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image on a recording material using an electrophotographic system.

  In a conventional image forming apparatus, a cleaning blade may be employed as a cleaning unit for the intermediate transfer member, and processing for causing a slight amount of toner to adhere to the cleaning blade is periodically performed to maintain the performance (preventing turning-up). (For example, refer to Patent Document 1).

  In some cases, the intermediate transfer member is exposed due to JAM processing (see, for example, Patent Document 2).

JP 2002-244386 A Japanese Patent Laid-Open No. 9-292812

  However, if the intermediate transfer member is exposed during JAM processing, the operator may accidentally touch the intermediate transfer member during JAM processing, and oil and dirt will adhere to the hand when touched. As a result, image defects may occur.

  In addition, although the processing contents described above are duplicated, they are performed separately because the purpose and processing timing are different.

  Accordingly, the object of the present invention is to form an image that can suppress image defects, reduce apparatus downtime, improve user productivity, and reduce consumption of consumables such as toner. To provide an apparatus.

  In order to achieve the above object, the present invention operates periodically at different timings and cycles in an image forming apparatus having an intermediate transfer member, an intermediate transfer member cleaning unit, and a determination unit that determines the amount of toner on the intermediate transfer member. A plurality of intermediate transfer member cleaning modes and irregular intermediate transfer member cleaning modes are provided, and when executing at least one intermediate transfer member cleaning mode, the execution timing of other intermediate transfer member cleaning modes is set. It is characterized by changing.

  That is, according to the present invention, when a mode performed at an unspecified timing is executed, a periodic timer for a mode that is periodically performed is initialized, or the periodic timer is initialized according to the remaining toner amount at the time of JAM or the like. Therefore, it was decided to extend the time until the next processing performed periodically.

  According to the present invention, the intermediate transfer member is always cleaned, image defects can be suppressed, user downtime can be reduced, user productivity can be improved, and consumption of consumables such as toner can be reduced. can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
FIG. 1 is a cross-sectional view of a full-color printer as an image forming apparatus. The image forming unit 1Y forms a yellow image, the image forming unit 1M forms a magenta image, and the image forms a cyan image. The image forming unit 1C includes four image forming units (image forming units) that form a black color image. The four image forming units 1Y, 1M, 1C, and 1Bk are arranged at regular intervals. Arranged in a row.

  In each of the image forming units 1Y, 1M, 1C, and 1Bk, drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 2a, 2b, 2c, and 2d are installed as image carriers. Around each photosensitive drum 2a, 2b, 2c, 2d, there are primary chargers 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d as transfer means, Drum cleaner devices 6a, 6b, 6c, and 6d are disposed, respectively, and a laser exposure device 7 is disposed below the primary chargers 3a, 3b, 3c, and 3d and the developing devices 4a, 4b, 4c, and 4d. is set up.

  Yellow toner, cyan toner, magenta toner, and black toner are respectively stored below the developing devices 4a, 4b, 4c, and 4d.

  Each of the photosensitive drums 2a, 2b, 2c, and 2d is a negatively charged OPC photosensitive member having a photoconductive layer on an aluminum drum base, and is driven in a direction indicated by an arrow (clockwise in FIG. 1) by a driving device (not shown). Direction) at a predetermined process speed.

  Primary chargers 3a, 3b, 3c, and 3d as primary charging means bring the surface of each photosensitive drum 2a, 2b, 2c, and 2d to a predetermined negative potential by a charging bias applied from a charging bias power source (not shown). Charge uniformly.

  The developing devices 4a, 4b, 4c, and 4d contain toner, and are developed as toner images by attaching toners of respective colors to the electrostatic latent images formed on the photosensitive drums 2a, 2b, 2c, and 2d, respectively. Visualization).

  Transfer rollers 5a, 5b, 5c and 5d as primary transfer means are arranged so as to be in contact with the respective photosensitive drums 2a, 2b, 2c and 2d via the intermediate transfer belt 8 in the respective primary transfer portions 32a to 32d. Yes.

  The drum cleaners 6 a, 6 b, 6 c, and 6 d have a cleaning blade or the like for removing, from the photosensitive drum 2, transfer residual toner remaining on the photosensitive drum 2 during the primary transfer.

  The intermediate transfer belt 8 is disposed on the upper surface side of each of the photosensitive drums 2a, 2b, 2c, and 2d, and is stretched between the secondary transfer counter roller 10 and the tension roller 11, and the secondary transfer counter roller 10 is The secondary transfer unit 34 is disposed so as to be in contact with the secondary transfer roller 12 via the intermediate transfer belt 8. The intermediate transfer belt 8 is made of a dielectric resin such as polycarbonate, polyethylene terephthalate resin film, polyvinylidene fluoride resin film, or the like.

  Further, the intermediate transfer belt 8 has a primary transfer surface (8b) formed on the surface facing the photosensitive drums 2a, 2b, 2c, and 2d inclined with the secondary transfer roller 12 side facing downward. .

That is, the intermediate transfer belt 8 is disposed on the upper surface of the photosensitive drums 2a, 2b, 2c, and 2d so as to be movable, and the primary transfer surface formed on the surface facing the photosensitive drum 2, that is, the lower flat surface 8b. The secondary transfer unit 34 is inclined so that the side is the lower side. Specifically, this inclination angle is set to about 15 °. The intermediate transfer belt 8 is disposed on the opposite side with the primary transfer portions 32a to 32d sandwiched between the secondary transfer counter roller 10 disposed on the secondary transfer portion 34 side and applying a driving force to the intermediate transfer belt 8. In addition, the intermediate transfer belt 8 is stretched with two tension rollers 11 that apply tension.

  The secondary transfer counter roller 10 is disposed so as to be in contact with the secondary transfer roller 12 via the intermediate transfer belt 8 at the secondary transfer unit 34. In addition, a belt cleaning device 13 for removing and collecting the transfer residual toner remaining on the surface of the intermediate transfer belt 8 is installed outside the endless intermediate transfer belt 8 and in the vicinity of the tension roller 11. A fixing device 16 having a fixing roller 16a and a pressure roller 16b is installed in a vertical path configuration on the downstream side of the transfer direction of the transfer material P from the secondary transfer unit 34.

  The exposure device 7 includes laser light emitting means for emitting light corresponding to time-series electric digital pixel signals of given image information, a polygon lens, a reflection mirror, and the like, and exposes each photosensitive drum 2a, 2b, 2c, 2d. As a result, an electrostatic latent image of each color corresponding to the image information is formed on the surface of each photosensitive drum 2a, 2b, 2c, 2d charged by each primary charger 3a, 3b, 3c, 3d.

  Next, an image forming operation by the above-described image forming apparatus will be described.

  When an image formation start signal is issued, the photosensitive drums 2a, 2b, 2c, and 2d of the image forming units 1Y, 1M, 1C, and 1Bk that are rotationally driven at a predetermined process speed are respectively connected to the primary chargers 3a, 3b, 3c and 3d are uniformly charged to negative polarity. Then, the exposure device 7 irradiates an image signal, which is color-separated from the outside, from the laser light emitting element, and passes each color on each photosensitive drum 2a, 2b, 2c, 2d via a polygon lens, a reflection mirror, or the like. An electrostatic latent image is formed.

  First, yellow toner is adhered to the electrostatic latent image formed on the photosensitive drum 2a by the developing device 4a to which a developing bias having the same polarity as the charging polarity (negative polarity) of the photosensitive drum 2a is applied. Visualize as an image. This yellow toner image is driven by a transfer roller 5a to which a primary transfer bias (a reverse polarity (positive polarity) to toner) is applied in a primary transfer portion 32a between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 8.

  The intermediate transfer belt 8 onto which the yellow toner image has been transferred is moved to the image forming unit 1M side. Also in the image forming unit 1M, the magenta toner image formed on the photosensitive drum 2b is superimposed on the yellow toner image on the intermediate transfer belt 8 in the same manner as described above, and the primary transfer unit 32b. Transcribed.

  At this time, the transfer residual toner remaining on each photosensitive drum 2 is scraped off and collected by a cleaner blade or the like provided in the drum cleaner devices 6a, 6b, 6c, and 6d.

  Similarly, cyan and black toner images formed by the photosensitive drums 2c and 2d of the image forming units 1C and 1Bk on the yellow and magenta toner images superimposed and transferred on the intermediate transfer belt 8 are respectively transferred in the same manner. A full-color toner image is formed on the intermediate transfer belt 8 by sequentially superposing the portions 32a to 32d.

  Then, in accordance with the timing when the leading edge of the full color toner image on the intermediate transfer belt 8 is moved to the secondary transfer portion 34 between the secondary transfer counter roller 10 and the secondary transfer roller 12, the paper feed cassette 17 or the manual feed tray. The transfer material (paper) P selected from 20 and fed through the transport path 18 is transported to the secondary transfer section 34 by the registration roller 19. A full-color toner image is collectively transferred to the transfer material P conveyed to the secondary transfer unit 34 by the secondary transfer roller 12 to which a secondary transfer bias (polarity opposite to the toner (positive polarity)) is applied. Is done.

  The transfer material P on which the full-color toner image is formed is conveyed to the fixing device 16, and the full-color toner image is heated and pressed at the fixing nip portion between the fixing roller 16a and the pressure roller 16b, thereby transferring the transfer material. After being thermally fixed on the surface of P, the paper is discharged onto a paper discharge tray 22 on the top surface of the main body by a paper discharge roller 21, and a series of image forming operations is completed. The secondary transfer residual toner and the like remaining on the intermediate transfer belt 8 are removed and collected by the belt cleaning device 13.

  The above is the image forming operation at the time of single-sided image formation.

  Next, a double-sided image forming operation in the image forming apparatus according to the present invention will be described.

  The operation up to the conveyance to the fixing device 16 is the same as the one-sided image forming operation, and the full-color toner image is heated and pressurized at the fixing nip portion between the fixing roller 16a and the pressure roller 16b to transfer the transfer material P. After heat fixing on the surface, the paper discharge roller 21 stops rotating with the paper discharge roller 21 discharging most of the transfer material P onto the paper discharge tray 22 on the upper surface of the main body. At that time, the transfer material P is stopped so that the rear end position of the transfer material P reaches the reversible position 42.

  Subsequently, in order to feed the transfer material P, whose conveyance has been stopped by stopping the rotation of the paper discharge roller 21, to the double-sided path including the double-sided rollers 40, 41, the paper discharge roller 21 rotates in the reverse direction to the normal rotation. Let By rotating the paper discharge roller 21 in the reverse direction, the rear end side of the transfer material P located at the reversal position 42 is set as the front end side and reaches the double-sided roller 40.

  After that, the transfer material P is conveyed to the double-sided roller 41 by the double-sided roller 40, and the transfer material P is sequentially conveyed toward the registration roller 19 by the double-sided rollers 40 and 41, during which an image formation start signal is generated. As in the case of single-sided image formation, the registration roller is aligned with the timing at which the front end of the full-color toner image on the intermediate transfer belt 8 is moved to the secondary transfer portion 34 between the secondary transfer counter roller 10 and the secondary transfer roller 12. 19, the transfer material P is moved to the secondary transfer portion 34.

  After the toner image is transferred by aligning the leading edge of the toner image with the leading edge of the transfer material P in the secondary transfer unit 34, the image on the transfer material P is fixed by the fixing device 16 in the same manner as in the single-sided image forming operation. Then, the sheet is conveyed again by the sheet discharge roller 21 and finally discharged onto the sheet discharge tray 22, and a series of image forming operations is completed.

  FIG. 2 is a control block diagram in the image forming apparatus.

  A CPU 171 performs basic control of the image forming apparatus. A ROM 174 in which a control program is written, a work RAM 175 for processing, and an input / output port 173 are connected by an address bus and a data bus. The input / output port 173 is connected to various loads (not shown) such as a motor and a clutch for controlling the image forming apparatus, and an input (not shown) such as a sensor for detecting the position of the paper.

  The CPU 171 sequentially performs input / output control via the input / output port 173 in accordance with the contents of the ROM 174 to execute an image forming operation. An operation unit 172 is connected to the CPU 171 and controls display means and key input means of the operation unit 172. The operator instructs the image forming operation mode and display switching to the CPU 171 through the key input means, and the CPU 171 displays the state of the image forming apparatus 100 and the operation mode setting by key input. The CPU 171 includes an external I / F processing unit 400 that transmits and receives image data and processing data from an external device such as a PC, an image memory unit 300 that performs image expansion processing and temporary storage processing, and an image memory unit 300. The image forming unit 200 is connected to perform processing to expose the line image data transferred from the exposure apparatus 7 to the exposure apparatus 7.

  Next, details of the image memory unit 300 will be described with reference to FIG.

  In the image memory unit 300, image data received from the external I / F processing unit 400 via the memory controller unit 302 is written into a page memory 301 configured by a memory such as a DRAM, and image reading to the image forming unit 2 is performed. I / O access for images.

  The memory controller unit 302 determines whether the image data from the external device received from the external I / F processing unit 400 is compressed data. If it is determined that the image data is compressed data, the compressed data expansion processing unit After performing the decompression process using 303, a write process is performed on the page memory 301 via the memory controller unit 302.

  The memory controller unit 302 generates a DRAM refresh signal of the page memory 301 and arbitrates access to the page memory 301 for writing from the image I / F processing unit 400 and reading to the image forming unit 200. Further, in accordance with an instruction from the CPU 171, the write address to the page memory 301, the read address from the page memory 301, the read direction, and the like are controlled.

  The configuration of the external I / F processing unit 400 will be described with reference to FIG.

  The external I / F processing unit 400 receives image data and print command data transmitted from the external device 500 via any of the USB I / F unit 401, the Centro I / F unit 402, and the network I / F unit 403. In addition, the status information of the image forming apparatus determined by the CPU 171 is transmitted to the external apparatus 500. Here, the external device 500 is a computer, a workstation, or the like.

  Print command data received from the external device 500 via any of the USB I / F unit 401, the Centro I / F unit 402, and the network I / F unit 403 is processed by the CPU 171 and the print operation is performed by the image forming unit 200 or Settings and timings for executing a print operation using the I / O 173 and the like in FIG. 2 are generated.

  Image data received from the external device 500 via any of the USB I / F unit 401, the Centro I / F unit 402, and the network I / F unit 403 is transferred to the image memory unit 300 according to the timing based on the print command data. Then, the image forming unit 200 processes the image to form an image.

  First, two types of intermediate transfer member cleaning modes will be described.

  FIG. 5 is a flowchart showing a procedure of the turning-up prevention processing procedure of the cleaning blade in the intermediate transfer body cleaning device 13, and in this example, it is automatically executed every n = 1,000 sheets (equivalent to A4). The processing timing is at the end of the job.

  First, it is determined whether or not the number of sheets exceeds 1,000 (step s1). If not, the process ends without doing anything. If the number exceeds 1,000, a belt-like pattern is formed (step s2), and the intermediate transfer member is formed. (Step s3).

  Next, when the transferred belt-like pattern on the rotating intermediate transfer member passes through the nip of the secondary transfer roller, a secondary transfer roller cleaning process is performed (step s4).

  The bias applied to the secondary transfer roller is applied so that the image is not transferred to the secondary transfer roller, and cleaning is performed by alternately applying positive and negative biases during cleaning.

  Wait until the belt-like pattern on the intermediate transfer member passes through the intermediate transfer member cleaning blade (step s5), and initialize the turn-up prevention processing counter.

  FIG. 6 is a flowchart showing a sequence for cleaning the intermediate transfer member when the operator accidentally touches the intermediate transfer member when the JAM process or the like is performed.

  First, a belt-like pattern is formed (step s11), transferred to an intermediate transfer member (step s12), and the intermediate transfer member is rotated for Z seconds (120 seconds in this example) (step s13).

  This is repeated N times (in this example, twice) (step s14), the secondary transfer roller cleaning process is performed (step s15), and the process ends when the cleaning blade is passed (step s16).

  Next, the operation when the present invention is implemented will be described.

  FIG. 7 is a flowchart showing the operation when the present invention is implemented in the sequence for cleaning the intermediate transfer member when the operator accidentally touches the intermediate transfer member when JAM processing or the like is performed. It is.

  First, a belt-like pattern is formed (step s21), transferred to an intermediate transfer member (step s22), and the intermediate transfer member is rotated for Z seconds (120 seconds in this example) (step s23).

  This is repeated N times (twice in this example) (step s24), the secondary transfer roller cleaning process is performed (step s25), and after passing the cleaning blade (step s26), the turn-up prevention counter is initialized ( Step s27) ends.

  In the image forming apparatus configured as described above, when JAM occurs, an image that has not been transferred to the recording medium remains on the intermediate transfer member.

  In the present invention, the number of dots of an image formed by a video count means (not shown) is counted, and the amount of toner transferred to the intermediate transfer member is determined from the number of dots of the image.

  The amount of toner transferred to the recording medium is determined from the positional relationship between the recording medium and the secondary transfer roller nip.

  Therefore, the remaining toner amount not transferred to the recording medium but remaining on the intermediate transfer member can be calculated from the toner amount transferred to the intermediate transfer member and the toner amount transferred to the recording medium.

  If the remaining toner amount is larger than a certain value, it is considered that the cleaning blade is prevented from turning over instead of the belt-like pattern.

  Therefore, the cleaning blade can be prevented from being turned over and repaired by the rotational cleaning of the intermediate transfer member and the secondary transfer roller cleaning process performed during the preparatory operation after the JAM process (process for removing the recording medium subjected to the JAM) is completed. It is.

  Therefore, when the amount of residual toner remaining on the intermediate transfer member at the end of the preparation operation after JAM return is compared with the amount of toner necessary for the anti-turning process, and it is determined that a sufficient amount remains, the anti-turning is prevented. The counter was initialized.

  Even if there is not a sufficient amount, the density of the belt-like pattern formed may be reduced according to the amount of remaining toner.

  Note that it is considered that the accuracy can be further improved by determining whether the toner spreads uniformly over the cleaning blade by measuring not only the amount of residual toner but also the distribution.

  Next, in consideration of a case where the intermediate transfer member is accidentally touched when the JAM occurs and the operator performs the JAM processing, and the intermediate transfer member becomes dirty, for example, when the JAM is returned from the operation unit 172 If the intermediate transfer member cleaning sequence is set to be performed during the preparatory operation, the remaining toner on the intermediate transfer member is determined by the same determination means as described above for the first of the N repeating sequences (steps s11 to s14). Substituted according to the amount.

  That is, when the remaining toner amount remaining on the intermediate transfer member at the end of the preparatory operation after the JAM return is compared with the toner amount required for one intermediate transfer member cleaning process, it is determined that a sufficient amount has remained. In the above, the repeating sequence in the cleaning sequence is substituted once.

  Even if there is not a sufficient amount, the density of the belt-like pattern formed may be reduced according to the amount of remaining toner.

  In this case as well, it is considered that the accuracy can be further improved by determining whether or not the toner spreads uniformly over the cleaning blade by measuring not only the amount of residual toner but also the distribution.

  The present invention can be used in an image forming apparatus such as a copying machine, a FAX, or a printer.

1 is a side sectional view of an image forming apparatus to which the present invention is applied. 2 is a control block diagram of the image forming apparatus. FIG. It is a detailed block diagram of an image memory part. It is a detailed block diagram of an external I / F processing unit. 6 is a flowchart illustrating an intermediate transfer member cleaning mode. 6 is a flowchart showing a sequence for cleaning an intermediate transfer member when an operator accidentally touches the intermediate transfer member when a JAM process or the like is performed. 6 is a flowchart showing an operation when the present invention is implemented in a sequence for cleaning an intermediate transfer member when an operator accidentally touches the intermediate transfer member when AM processing or the like is performed.

Explanation of symbols

1Y, 1M, 1C, 1Bk Image forming portions 2a, 2b, 2c, 2d Photosensitive drum (image carrier)
3a, 3b, 3c, 3d Primary charger (charging means)
4a, 4b, 4c, 4d Developing device (developing means)
5a, 5b, 5c, 5d Transfer roller (primary transfer means)
6a, 6b, 6c, 6d Drum cleaner device (cleaner means)
7 Exposure equipment (exposure means)
7a Lower surface 7b Lower end 8 Intermediate transfer belt 8a Top surface 8b Lower plane (primary transfer surface)
10 Secondary transfer counter roller 11 Tension roller 12 Secondary transfer roller (secondary transfer means)
13 Belt cleaning device 16 Fixing device (fixing means)
16a Fixing roller 16b Heating roller 17 Paper feed cassette 18 Transport path 21 Paper discharge roller (discharge means)
22 Paper discharge tray 30 Toner container 31 Nipping part (heating and pressing position)
32a, 32b, 32c, 32d Primary transfer part 34 Secondary transfer part 301, 602, 603 Sensor 701 Encoder

Claims (4)

In an image forming apparatus having an intermediate transfer member, an intermediate transfer member cleaning unit, and a determination unit for determining a toner amount on the intermediate transfer member,
There are multiple intermediate transfer member cleaning modes that operate periodically at different timings and cycles, and irregular intermediate transfer member cleaning modes that are performed at irregular intervals. And changing the execution timing of the intermediate transfer member cleaning mode.   The cleaning device for cleaning the intermediate transfer member is provided, and at least one of the plurality of intermediate transfer member cleaning modes is performed for adjustment of the cleaning member. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the execution timing of the intermediate transfer member cleaning mode is changed based on a determination result of the toner amount determination unit.   The image forming apparatus according to claim 1, wherein the operation content of the intermediate transfer member cleaning mode is changed based on a determination result of the toner amount determination unit.

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