JP2005215281A - Residual toner collecting method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely collect residual toner in a short time in case of an abnormal stop during an image forming stage. <P>SOLUTION: If the abnormal stop occurs in the image forming stage of forming an image by a plurality of image carriers and an intermediate transfer belt (YES at S103), one of the plurality of image carriers is selected (S104) according to the density of the residual toner on the intermediate transfer belt, the residual toner is reversely transferred to the selected image carrier and collected by a cleaning unit above the image carrier (S105), and the residual toner is collected by an intermediate transfer belt cleaning unit (S106). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a collecting method for collecting residual toner in an image forming process in an electrophotographic image forming apparatus.

  Conventionally, an electrophotographic method is known for a color image forming apparatus. In the image forming process, first, a photosensitive drum is uniformly charged by a charging device, an electrostatic latent image is formed by a laser or an LED, and this electrostatic image is formed. The latent image is developed with toner. This is performed for each of the magenta, cyan, yellow, and black color photosensitive drums, and the formed color toner images are superimposed on the intermediate transfer belt and transferred to a recording material such as paper. A color image is formed by a method in which the toner image superimposed on the recording material is fixed to the recording material by heat. In this process, the toner remaining on the photosensitive drum is collected by a photosensitive drum cleaning device provided around the photosensitive drum. Further, the toner remaining on the intermediate transfer belt is removed by an intermediate transfer belt cleaning device provided around the intermediate transfer belt.

  In recent years, in order to improve the image quality of color image forming apparatuses, a conductive elastic layer made of urethane rubber, silicon rubber or the like is formed on a base layer as a material for an intermediate transfer belt, and the surface layer is made of a fluororesin or the like, so-called An apparatus having an elastic intermediate transfer belt is presented.

  As an advantage of using the above-described elastic intermediate transfer belt, firstly, there is no omission of the toner image that occurs due to toner aggregation during the primary transfer in which the toner image on the photosensitive drum is transferred to the intermediate transfer belt. It can be mentioned. Second, in recent years, color image forming apparatuses are required to support various recording materials, and secondary transfer that transfers a toner image from an intermediate transfer belt to a recording material on a recording material with a rough surface. In the nip portion at this time, the surface of the intermediate transfer belt and the recording material sandwiching the toner image are adapted to each other by this elastic characteristic, and good transfer is performed.

On the other hand, as a means for cleaning the intermediate transfer member, for example, a blade cleaning method in which the blade is brought into contact with the intermediate transfer member and the toner is scraped off by the blade (see, for example, Patent Document 1), and a bias is applied to the conductive fur brush. A conductive brush cleaning system (for example, see Patent Document 2) that rotates and collects toner by a potential difference generated between the intermediate transfer member and the fur brush is disclosed.
JP-A-4-60569 Japanese Patent Laid-Open No. 4-115777

  However, the blade cleaning method has a problem that residual toner slips through due to the surface roughness of the elastic intermediate transfer belt, and sufficient cleaning cannot be performed.

  In addition, the conductive brush cleaning method has a restriction on the amount of toner image on the intermediate transfer belt, and is not a small amount of cleaning such as residual toner after transfer to a recording material. In the case of cleaning after the job is stopped while the toner image that has not been transferred onto the recording material remains on the intermediate transfer belt, it is necessary to perform cleaning by rotating the intermediate transfer belt many times during the previous multiple rotations. Therefore, there is a problem that it takes time for the recovery process.

  The present invention has been made in view of the above-described problems of the prior art, and its object is to reliably collect residual toner in a short time when an abnormal stop occurs in the image forming process. It can be done.

  The present invention relates to a residual toner collecting method for collecting residual toner in an image forming process in an electrophotographic image forming apparatus, and an abnormal stop is caused in an image forming process in which an image is formed by a plurality of image carriers and an intermediate transfer belt. And a step of selecting at least one image carrier from the plurality of image carriers in accordance with a density of residual toner on the intermediate transfer belt, and the residual toner as the selected image. The method includes a step of reversely transferring to a carrier and collecting the residual toner by a cleaning device on the image carrier, and a step of collecting the residual toner by the intermediate transfer belt cleaning device.

  The present invention also provides an image forming apparatus for forming an image by an electrophotographic method, in the case where an abnormal stop occurs in an image forming process in which an image is formed by a plurality of image carriers and an intermediate transfer belt. Selection means for selecting at least one image carrier from among the plurality of image carriers in accordance with the density of the residual toner, and reverse transfer of the residual toner to the selected image carrier and the image carrier. It has a 1st collection means collect | recovered with the cleaning apparatus on a holding body, and a 2nd collection means which collects the said residual toner with the said intermediate transfer belt cleaning apparatus, It is characterized by the above-mentioned.

  According to the present invention, when an abnormal stop occurs in the image forming process, the residual toner can be reliably collected in a short time, and the residual toner can be collected from the plurality of image carriers without being biased. The cleaning performance can be maintained.

  The best mode for carrying out the invention will be described below in detail with reference to the drawings. In this embodiment, when cleaning a large amount of toner images on the intermediate transfer belt, in addition to the intermediate transfer belt cleaning device in order to complete the cleaning in a short time, a cleaning device for each color photosensitive drum is also used. The residual toner is collected.

  Furthermore, the cleaning performance of the photosensitive drum cleaning device is maintained by preventing the collection amounts of the four photosensitive drums from being biased.

  FIG. 2 is a cross-sectional view showing a schematic configuration of a full-color copying machine which is an example of an image forming apparatus according to the present embodiment. As shown in FIG. 2, the full-color copying machine includes a digital color image reader unit 200 (hereinafter referred to as a reader unit) and a digital color image printer unit 201 (hereinafter referred to as a printer unit). Yes.

  In the reader unit 200, an original is placed on the original table glass 211, and the original scanning unit 215 including the exposure lamps 213 and 214 is exposed and scanned at a predetermined constant speed by the optical system reading drive motor 212. Then, the reflected light image from the original is condensed on a full color sensor (CCD) 217 by a lens 216 to obtain an image signal subjected to color separation. As the full-color sensor 217, a three-line CCD with R (red), G (green), and B (blue) filters disposed adjacent to each other is used. Further, the color-separated image signal is subjected to image processing by the image processing unit 218 and then sent to the printer unit 201.

  An operation unit is provided around the platen glass 211, and a switch for setting various modes related to the copy sequence, a display for display, and a display are arranged.

  Next, the printer unit 201 will be described. In the printer unit 201, the control unit 59 is a controller unit, and is configured by a controller board including a CPU, a RAM, a ROM, and the like. Based on a control program stored in the ROM, a paper feeding unit, an intermediate transfer unit, and a conveyance unit The operation of the fixing unit and the operation unit is comprehensively controlled.

  The image forming unit that forms an image under the control of the control unit 59 is configured as follows. Photosensitive drums 11a, 11b, 11c, and 11d as image carriers are pivotally supported at their centers and are rotationally driven by a drive motor (not shown) in the direction of the arrow. Roller chargers 12a, 12b, 12c, 12d, scanners 13a, 13b, 13c, 13d, developing devices 14a, 14b, 14c, 14d, and photosensitive drum cleaning devices facing the outer peripheral surfaces of the photosensitive drums 11a to 11d in the rotational direction. 15a, 15b, 15c, 15d are arranged.

  In such a configuration, the roller chargers 12a to 12d give a uniform charge amount to the surfaces of the photosensitive drums 11a to 11d. Next, the photosensitive drums 11a to 11d are exposed to light beams such as laser beams, which are modulated by the scanners 13a to 13d according to the recording image signal, thereby forming electrostatic latent images thereon. Further, the electrostatic latent images are visualized by developing devices 14a to 14d that respectively store four color developers (toners) such as black, cyan, magenta, and yellow. The visualized visible image is transferred to the intermediate transfer member 30. Thereafter, the residual toner remaining on the photosensitive drums 11a to 11d is collected by the photosensitive drum cleaning devices 15a to 15d. By the process described above, image formation with each toner is sequentially performed.

  Next, the paper feeding unit includes a portion for storing the recording material P, a roller for conveying the recording material P, a sensor for detecting the passage of the recording material P, and a sensor for detecting the presence or absence of the recording material P. And a guide (not shown) for transporting the recording material P along the transport path.

  21a, 21b, 21c, and 21d are cassettes, 27 is a manual feed tray, and 28 is a deck. 22a, 22b, 22c and 22d are pickup rollers for feeding the recording material P from the cassettes 21a to 21d one by one from the top. In the pickup rollers 22a to 22d, a plurality of recording materials P may be sent out, but only one sheet is reliably separated by the BC rollers 23a, 23b, 23c, and 23d. The recording material P separated by only one sheet by the BC rollers 23 a to 23 d is further transported by the drawing rollers 24 a to 24 d and the pre-registration roller 26, and is transported to the registration roller 25.

  The recording material P stored in the manual feed tray 27 is separated by a BC roller 29 and conveyed to a registration roller 25 by a pre-registration roller 26. Further, a plurality of recording materials P stored in the deck 28 are conveyed to the paper feeding roller 61 by the pickup roller 60, and only one sheet is reliably separated by the paper feeding roller 61 and conveyed to the drawing roller 62. Further, the recording material P is conveyed to the registration roller 25 by the pre-registration roller 26.

  Next, the intermediate transfer unit will be described in detail. 30 is an intermediate transfer belt. As a material thereof, a conductive elastic layer made of urethane rubber, silicon rubber, CR rubber or the like is formed on a base layer made of PI, PVdF, or the like, and its surface is made of fluororesin, FKM, or the like. A surface layer is formed. The intermediate transfer belt 30 includes a driving roller 32 that transmits driving to the intermediate transfer belt 30, a tension roller 33 that applies appropriate tension to the intermediate transfer belt 30 by urging a spring (not shown), and the intermediate transfer belt 30. It is supported by a driven roller 34 that forms a secondary transfer region with being sandwiched therebetween.

  The drive roller 32 is rotationally driven by a stepping motor (not shown). Primary transfer rollers 35a to 35d for applying a high pressure for transferring a toner image to the intermediate transfer belt 30 on the back of the intermediate transfer belt 30 at positions facing the respective photosensitive drums 11a to 11d with the intermediate transfer belt 30 interposed therebetween. Is arranged. A secondary transfer roller 36 is disposed opposite the driven roller 34 to form a secondary transfer region by a nip with the intermediate transfer belt 30. The secondary transfer roller 36 is pressed against the intermediate transfer belt 30 with an appropriate pressure.

  A cleaning device 50 for cleaning the image forming surface of the intermediate transfer belt 30 is disposed on the intermediate transfer belt 30 and downstream of the secondary transfer region. The cleaning device 50 includes a conductive fur brush 51, a fur It comprises a bias roller (not shown) for applying a bias to the brush 51 and a waste toner box 52 for storing waste toner.

  The fixing unit 40 has been discharged from a fixing roller 41a provided with a heat source such as a halogen heater inside, a roller 41b (which may also be provided with a heat source), and a pair of these rollers. It consists of an internal paper discharge roller 44 that conveys the recording material P.

  On the other hand, the recording material P conveyed to the registration roller 25 stops and temporarily stops the rotation of the upstream roller from the registration roller 25, and the upstream roller including the registration roller 25 is synchronized with the image formation timing of the image forming unit. The rotational drive is resumed. The recording material P is sent out to a secondary transfer area described later.

  The recording material P to which the image has been transferred in the secondary transfer area and the image has been fixed in the fixing unit 40 passes through the inner paper discharge roller 44 and is then switched by the switching flapper 73. When the switching flapper 73 is on the face-up discharge side, the recording material P is discharged to the face-up discharge tray 2 by the outer discharge roller 45.

  On the other hand, when the switching flapper 73 is on the face-down paper discharge side, the recording material P is conveyed in the direction of the reverse rollers 72 a, 72 b, 72 c and discharged to the face-down paper discharge tray 3.

  Note that a plurality of sensors are arranged in the conveyance path of the recording material P to detect the passage of the recording material P, and the paper feeding retry sensors 64a, 64b, 64c, 64d, the deck paper feeding sensor 65, the deck pulling out. There are a sensor 66, a registration sensor 67, an internal paper discharge sensor 68, a face-down paper discharge sensor 69, a double-sided pre-registration sensor 70, a double-sided paper re-feed sensor 71, and the like.

  The cassettes 21a to 21d that store the recording material P are provided with cassette paper presence / absence sensors 63a, 63b, 63c, and 63d that detect the presence or absence of the recording material P, and the manual feed tray 27 records on the manual feed tray 27. A manual tray paper presence / absence sensor 74 for detecting the presence or absence of the material P is disposed, and a deck paper presence / absence sensor 75 for detecting the presence or absence of the recording material P in the deck 28 is disposed on the deck 28.

  Next, a description will be added in accordance with the operation of the apparatus. As an example, a case where the recording material P is transported from the cassette 21a will be described.

  After a predetermined time has elapsed from the start of the job, first, the recording material P is sent out one by one from the cassette 21a by the pickup roller 22a. Then, the recording material P is conveyed by the paper feed roller 23 to the registration roller 25 via the drawing roller 24 a and the pre-registration roller 26. At that time, the registration roller 25 is stopped, and the leading edge of the paper hits the nip portion.

  Thereafter, the registration roller 25 starts rotating in accordance with the timing at which the image forming unit starts image formation. The rotation timing is set so that the recording material P and the toner image primary-transferred onto the intermediate transfer belt from the image forming unit exactly coincide with each other in the secondary transfer region.

  On the other hand, in the image forming unit, when an image forming operation start signal is issued, a high voltage is applied to the toner image formed on the photosensitive drum 11d that is the most upstream in the rotation direction of the intermediate transfer belt 30 by the process described above. By the transferred transfer roller 35d, primary transfer is performed on the intermediate transfer belt 30 in the primary transfer region. The primarily transferred toner image is conveyed to the next primary transfer area.

  Here, image formation is performed with a delay of the time during which the toner image is conveyed between the image forming units, and the next toner image is transferred with the leading edge of the image aligned on the previous image. Thereafter, the same process is repeated, and finally the four color toner images are primarily transferred onto the intermediate transfer belt 30.

  Thereafter, when the recording material P enters the secondary transfer area and contacts the intermediate transfer belt 30, a high voltage is applied to the secondary transfer roller 36 in accordance with the passing timing of the recording material P. Then, the four color toner images formed on the intermediate transfer belt are transferred onto the surface of the recording material P by the process described above. Thereafter, the recording material P is guided to the fixing roller nip portion. The toner image is fixed on the paper surface by the heat of the roller pairs 41a and 41b and the pressure of the nip. Thereafter, the recording material P is discharged to the face-up discharge tray 2 or the face-down tray 3 according to the switching direction of the switching flapper 73.

  FIG. 8 is a block diagram illustrating an example of the configuration of the control unit 59. A CPU 801 shown in FIG. 8 performs basic control of the full-color copying machine. The CPU 801 is connected to a ROM 802 in which a control program and control data shown in FIG. 1 described later in detail are written, and a work RAM 803 used when the CPU 801 executes processing via an address bus and a data bus. . Also connected to the CPU 801 are a reader control unit 806 and a printer control unit 807 which are electric circuits including an input / output port for controlling each component of the reader unit 200 and the printer unit 201. According to the contents of the control program, the reader control unit 806 and the printer control unit 807 are controlled to execute an image forming operation.

  Further, the CPU 801 is also connected with an image processing unit 805 that performs various image processing on the digital data of the document image converted by the reader control unit 806. Here, the configuration and processing of the image processing unit 805 will be described.

  FIG. 3 is a block diagram illustrating an example of the configuration of the image processing unit 805. First, the reflected light from the original image formed on the CCD sensor 217 is converted into an analog electric signal by the CCD sensor 217. The converted document image is input to the analog signal processing unit 300 and subjected to sample & hold, dark level correction, and the like, and then the analog / digital conversion (A / D conversion) is performed by the A / D / SH processing unit 301. Further, shading correction is performed on the digitized signal. In this shading correction, correction for variation in each pixel of the CCD sensor 217 and correction for variation in light quantity depending on the position based on the light distribution characteristics of the document illumination lamp are performed.

  Next, the RGB line correction unit 302 performs RGB line correction. This correction is a process of synchronizing the RGB signals here because the light input to the RGB light receiving portions of the CCD sensor 217 at a certain time is shifted on the document according to the positional relationship of the RGB light receiving portions. .

  Next, the input masking unit 303 performs input masking processing to convert each luminance data of RGB into each density data of YMCK. In this input masking process, since the RGB value output from the CCD sensor 217 is directly influenced by the color filter attached to the CCD sensor 217, the influence is corrected and converted into a pure RGB value. It is.

  Next, the scaling unit 304 performs scaling processing at a desired scaling factor, and the scaled image data is sent to the image memory unit 305 and stored. Thereafter, the accumulated image data is first sent from the image memory unit 305 to the γ correction unit 306. The γ correction unit 306 outputs a desired output from the original density data based on a look-up table (LUT) that takes printer characteristics into account, in order to output details according to density values set by an operation unit, which will be described later. Convert to density data corresponding to density.

  Next, the density data is sent to the binarization unit 307. The binarization unit 307 converts an 8-bit multilevel signal into a binary signal. As this conversion method, for example, a dither method, an error diffusion method, an improved error diffusion method, or the like is used. The binarized data is sent to the image forming unit to form an image. The density data corrected by the γ correction unit 306 is sent to the video count unit 308, and the count is performed for each density data of YMCK.

  FIG. 7 is a diagram illustrating an example of a detailed configuration of the video signal count unit 308. In FIG. 7, reference numeral 700 denotes an image signal for one color sent from the γ correction unit 306, and the image signal for one image is counted by 29-bit counters 701 to 708 in parallel every 8 bits. Are added by a 32-bit adder 709 to obtain a video count for one image as 32-bit data.

  In the example shown in FIG. 7, one video signal count unit that sequentially counts each density data of YMCK is shown. However, four count units may be provided in parallel to count simultaneously. .

  Returning to FIG. 8, the operation unit 900 is connected to the CPU 801. Here, a detailed configuration of the operation unit 900 will be described.

  FIG. 9 is a diagram illustrating an example of the configuration of the operation unit 900 in the present embodiment. In FIG. 9, reference numeral 901 denotes a touch panel display, which displays a copy number 1001, a selected paper size 1002, a magnification 1003, and a copy density 1004 as shown in FIG. In the example shown in FIG. 10, the A4 size is selected using the paper selection key 1005, and the number of copies is set to 11 using the numeric keypad described later.

  Returning to FIG. 9, reference numeral 902 denotes a reset key, which returns the function set in the operation unit 900 to the default value. Reference numeral 903 denotes a start key, which starts a copy operation. A stop key 904 interrupts the copying operation. A clear key 905 returns the copy mode to the standard mode. Reference numeral 906 denotes a numeric keypad for setting the number of copies. Reference numeral 907 denotes a color mode selection key, which automatically determines whether the document is color or black and white, and outputs an ACS (auto color select) key for outputting in color if it is in color and outputting in black and white if it is in black and white. There are a Color key for color output regardless of the original and a Black key for monochrome output regardless of the original, and one of these keys is lit.

  Next, the density of the toner image remaining on the intermediate transfer belt is detected when the job is abnormally stopped, which is a characteristic part in the present embodiment, and the residual toner on the intermediate transfer belt is determined as the residual toner density in the recovery operation. A method for returning to the photosensitive drum selected according to the durability of the photosensitive drum and recovering it by the photosensitive drum cleaning device will be described in detail.

  When the start key 903 is pressed in the state shown in FIG. 10, the information is transmitted to the CPU 801 from the operation unit 900 shown in FIG. 8, information such as the paper size and the number of copies is stored in the RAM 803, and the print job is started.

  Here, a data structure for detecting the image density on the intermediate transfer belt 30 during printing will be described.

  FIG. 5 is a diagram showing a data structure for detecting the image density. The data shown in FIG. 5 is allocated on the work RAM 803, all values are cleared to 0 at the start of the print job, and data is written as the image forming operation proceeds.

  Reference numeral 501 denotes an image ID, which identifies each toner image primarily transferred onto the intermediate transfer belt 30. The image ID 501 is written when the primary transfer of the yellow image is started. Reference numeral 502 denotes a video count value of a yellow image formed on the photosensitive drum 11d and primarily transferred onto the intermediate transfer belt 30, and is written when the primary transfer of the yellow image with the corresponding ID is completed.

  Reference numeral 503 denotes a video count value of the magenta image formed on the photosensitive drum 11c and primarily transferred onto the intermediate transfer belt 30, and is written when the primary transfer of the corresponding magenta image is completed. Reference numeral 504 denotes a video count value of the cyan image formed on the photosensitive drum 11b and primary-transferred onto the intermediate transfer belt 30, and is written when the primary transfer of the corresponding cyan image is completed.

  Reference numeral 505 denotes a video count value of a black image formed on the photosensitive drum 11a and primarily transferred onto the intermediate transfer belt 30, and is written when the primary transfer of the black image with the corresponding ID is completed. Reference numeral 506 denotes information indicating whether or not the image on the intermediate transfer belt 30 has been secondarily transferred to the recording material. 1 is written when the primary transfer of the yellow image is started, and 0 when the secondary transfer is completed. Is written. When the secondary transfer is completed, the video count values 502 to 505 corresponding to the image ID for which the secondary transfer has been completed are cleared to zero.

  Here, with reference to FIG. 4, when a print job is started and the toner image on the third intermediate transfer belt 30 from the start is secondarily transferred to the recording material P, processing when an abnormal stop is caused by a jam. Will be described.

  FIG. 4 is a diagram illustrating a state of a toner image on the intermediate transfer belt that has been abnormally stopped due to the occurrence of a jam. In FIG. 4, a toner image 401 and a toner image 402 are formed by overlapping toner images of four colors of yellow, magenta, cyan, and black. Further, the toner image 403 is a toner image in the middle of the primary transfer of cyan onto a superposition of yellow and magenta toner images. A toner image 404 is a toner image in the middle of the primary transfer of yellow. The toner images 401 to 404 correspond to the image IDs 3 to 6 shown in FIG.

  FIG. 5 shows an example of the data structure written in the state shown in FIG. 4. Data corresponding to image IDs 501 of 1 and 2 is written with 0 at the end of the secondary transfer. The values V-Y3, V-M3, V-C3, and V-K3 of the video counts 502, 503, 504, and 505 corresponding to the image ID 501 of 3 are written at the end of each primary transfer. 1 is written when the primary transfer of the yellow image is started. Further, the values V-Y4, V-M4, V-C4, and V-K4 of the video counts 502, 503, 504, and 505 corresponding to the image ID 501 of 4 are written at the end of each primary transfer, 506 is written when the yellow image primary transfer is started.

  Also, the video counts 502 and 503 values V-Y5 and V-M5 corresponding to the image ID 501 of 5 are written at the end of the primary transfer, and 506 is when the primary transfer of the yellow image is started. 1 is written. In the field 506 corresponding to the image ID 501 of 6, 1 is written when the primary transfer of the yellow image is started.

  Here, when the print job is normally completed, all the images on the intermediate transfer belt 30 are secondarily transferred to the recording material P and are finished, and the values of 506 and 502 to 505 are all 0. In the data of FIG. 5, since the value of 506 corresponding to the image ID 501 of 3, 4, 5, 6 is 1, it can be detected that the job has ended abnormally.

  Next, a method for obtaining the durability state of each photosensitive drum will be described.

  FIG. 6 is a diagram showing a data structure for obtaining the durability state of the photosensitive drum. The data shown in FIG. 6 is allocated on the work RAM 803. In FIG. 6, reference numeral 601 denotes the color of the photosensitive drum and identifies the photosensitive drum. Reference numeral 602 denotes a durability level, which is a value indicating the durability of the photosensitive drum. Reference numeral 603 denotes an integrated value of the number of image formations, which is a value indicating the total number of images formed on the photosensitive drum. NY, NM, NC, and NK represent the number of image formations from the initial state of the photosensitive drum at the time of installation in terms of A4 paper size It is the value which added sequentially. Reference numeral 604 denotes an integrated video count value that indicates the total video count of images formed on the photosensitive drum. VY, VM, VC, and VK sequentially add video counts during image formation from the initial photosensitive drum state at the time of installation. It is the value that was done. The values EY, EM, EC, and EK of the durability level 602 are calculated as follows using the image formation number integrated value 603 and the video count integrated value 604.

  Here, assuming that the video count integrated value is Vsum, the image formation number integrated value is Nsum, the lifetime number of drums is D, and the A4 size solid image video count value is VA4, the durability level value E is obtained by the following equation.

E = (Nsum / D) × (Vsum / VA4)
Note that the value of 601 is always maintained, the values of 602 to 604 are cleared to 0 when the photosensitive drum unit including the photosensitive drum and the photosensitive drum cleaning device is replaced, and the value is written for each subsequent image formation.

  Next, a method for recovering residual toner of a toner image formed on the intermediate transfer belt 30 by the recovery operation after the occurrence of a jam by each photosensitive drum cleaning device and the intermediate transfer belt cleaning device will be described with reference to FIG.

  FIG. 1 is a flowchart illustrating a residual toner cleaning method according to the present exemplary embodiment. First, in step S101, after the jam stops, the user removes the jammed paper from the inside of the machine and monitors whether all the covers are closed. Here, when all the covers are closed, the process proceeds to step S102, and the front multi-rotation is started. In step S102, a message 1101 shown in FIG. 11 is displayed on the screen 901 of the operation unit 900, and driving of the intermediate transfer belt 30 and the photosensitive drum is started.

  Next, in step S103, it is determined with reference to the data shown in FIG. 5 whether or not the previous job ended abnormally. Specifically, the secondary transfer incomplete information 506 in the data structure shown in FIG. 5 allocated on the work RAM 803 is accessed, and if there is an image ID in which 1 is written, the intermediate in the previous job. It is determined that the transfer is completed abnormally with the toner image remaining on the transfer belt 30. As a result of the determination, if not abnormally terminated, the process proceeds to step S106, and if abnormally terminated, the process proceeds to step S104, and the next cleaning method is executed.

  First, in step S104, among the photosensitive drums of yellow, magenta, cyan, and black, the photosensitive drum for executing the process of returning the toner on the intermediate transfer belt 30 onto the photosensitive drum and collecting it by the photosensitive drum cleaning device. select. This procedure accesses the data 502 to 505 of the data shown in FIG. 5 allocated on the work RAM 803, adds all of the values, and obtains the density value Vitb of the toner image remaining on the intermediate transfer belt 30. Ask. Next, if the value of the density value Vitb is equal to or less than the predetermined threshold value T, the data of the durability level 602 of FIG. 6 allocated on the work RAM 803 is accessed, and the photosensitive drum having the smallest value is selected. If the density value Vitb is larger than the predetermined threshold value T, the photosensitive drums for all colors are selected. Here, the threshold value T is a value that depends on the cleaning capability of the intermediate transfer belt cleaning device.

  In this embodiment, whether one photosensitive drum or four photosensitive drums are used is determined based on one threshold value T. However, a plurality of threshold values are prepared and the number of photosensitive drums to be selected is changed. You may select in order with a low level value.

  Next, in step S105, processing for returning the residual toner on the intermediate transfer belt 30 to the photosensitive drum selected in step S104 is executed. Specifically, in order to prevent the fur brush of the intermediate transfer belt cleaning device from being contaminated by a large amount of toner and deteriorating the cleaning performance, a bias in the direction opposite to that at the time of toner collection is applied to the fur brush. In this embodiment, a high voltage of −700 V is applied. Next, the surface potential of the photosensitive drum selected in step S104 is set to about 0 V by a roller charger, and a bias -1100 V in the reverse direction to the image formation is applied to the primary transfer roller to rotate the intermediate transfer belt 30 once. Rotate. At this time, in the nip portion between the intermediate transfer belt 30 and the photosensitive drum, the toner on the intermediate transfer belt 30 is returned onto the photosensitive drum due to the potential difference between the surface potential of the intermediate transfer belt 30 and the photosensitive drum, and the residual toner transferred onto the photosensitive drum. Is recovered by a photosensitive drum cleaning device.

  Next, in step S106, the normal intermediate transfer belt 30 is cleaned by the intermediate transfer belt cleaning device. Specifically, the reverse bias application of the primary transfer roller is stopped, and the toner recovery bias +700 V is applied to the fur brush of the intermediate transfer belt cleaning device. In step S107, the applied bias, photosensitive drum, and intermediate transfer belt are stopped, and the screen 901 of the operation unit 900 is changed to the screen shown in FIG. 10 so that the next print job can be started. To do.

  As described above, in the image forming apparatus according to the present embodiment, when cleaning a large amount of toner images on the intermediate transfer belt, in order to complete the cleaning in a short time, in addition to the intermediate transfer belt cleaning apparatus, each color photosensitive device Using the drum cleaning device, the toner on the intermediate transfer belt can be returned to the photosensitive drum and recovered by the photosensitive drum cleaning device.

  Furthermore, the collection performance of the photosensitive drum cleaning device can be maintained by collecting the four photosensitive drums so that the collection amounts are not biased.

  Even if the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), it is applied to an apparatus (for example, a copier, a facsimile machine, etc.) composed of a single device. It may be applied.

  Another object of the present invention is to supply a recording medium in which a program code of software realizing the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus stores the recording medium in the recording medium. Needless to say, this can also be achieved by reading and executing the programmed program code.

  In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium storing the program code constitutes the present invention.

  As a recording medium for supplying the program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like is used. be able to.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Further, after the program code read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

6 is a flowchart illustrating a residual toner cleaning method according to the present exemplary embodiment. 1 is a cross-sectional view illustrating a schematic configuration of a full-color copying machine that is an example of an image forming apparatus according to an exemplary embodiment. 3 is a block diagram illustrating an example of a configuration of an image processing unit 805. FIG. FIG. 6 is a diagram illustrating a state of a toner image on an intermediate transfer belt that has stopped abnormally due to a jam. It is a figure which shows the data structure for detecting image density. It is a figure which shows the data structure for calculating | requiring the durable state of a photosensitive drum. 3 is a diagram illustrating an example of a detailed configuration of a video signal count unit 308. FIG. 3 is a block diagram illustrating an example of a configuration of a control unit 59. FIG. It is a figure which shows an example of a structure of the operation part 900 in this embodiment. It is a figure which shows an example of the screen displayed on an operation part at the time of copying. It is a figure which shows an example of the screen displayed on an operation part by the operation | movement of the recovery after jam generation.

Claims (8)

A residual toner collecting method for collecting residual toner in an image forming process in an electrophotographic image forming apparatus,
When an abnormal stop occurs in an image forming process in which an image is formed by a plurality of image carriers and an intermediate transfer belt, the plurality of image carriers are selected according to the density of residual toner on the intermediate transfer belt. Selecting at least one image carrier;
Back-transferring the residual toner to the selected image carrier and collecting it with a cleaning device on the image carrier;
And a step of recovering the residual toner by the intermediate transfer belt cleaning device.   2. The residual toner collecting method according to claim 1, wherein in the selecting step, the number of image carriers to be selected is increased as the density of the residual toner on the intermediate transfer belt is higher. Further comprising detecting a durability state of the plurality of image carriers,
2. The residual toner collecting method according to claim 1, wherein, in the selecting step, the image carrier that has not progressed in durability is selected in order according to the durability state detected in the detecting step.   4. The residual toner collecting method according to claim 3, wherein the durability state is a value based on a video count value of an image formed by the plurality of image carriers.   4. The residual toner collecting method according to claim 3, wherein the durability state is a value based on the number of images formed by the plurality of image carriers. In an image forming apparatus that forms an image by electrophotography,
When an abnormal stop occurs in an image forming process in which an image is formed by a plurality of image carriers and an intermediate transfer belt, the plurality of image carriers are selected according to the density of residual toner on the intermediate transfer belt. Selecting means for selecting at least one image carrier;
A first collecting means for reversely transferring the residual toner to the selected image carrier and collecting the residual toner by a cleaning device on the image carrier;
An image forming apparatus comprising: a second collecting unit that collects the residual toner by the intermediate transfer belt cleaning device.   A program for causing a computer to execute each step of the residual toner collecting method according to claim 1.   A computer-readable recording medium on which the program according to claim 7 is recorded.

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