JP2014052558A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus that efficiently performs toner refresh is provided.
An image forming apparatus includes first and second drums, an image forming unit including a transfer belt, first and second cleaners, and a control unit. The image forming means transfers a first toner image on the first drum to a first recording medium via the transfer belt and forms a first image corresponding to the first toner image. Or the second toner image corresponding to the first and second toner images by transferring the first and second toner images held on the first and second drums to the second recording medium. A second image forming mode for forming an image is executed. The first and second cleaners remove the first and second toners from the first and second drums. The control means supplies the second toner to the second drum for the purpose of cleaning and removes the second toner during the execution of the first image forming mode.
[Selection] Figure 3

Description

  Embodiments described herein relate generally to an image forming apparatus.

  If the toner in the developing device of the image forming apparatus continues to stay without being consumed for a long time, the toner may deteriorate due to the stirring operation and cause an image defect. As a countermeasure against such a problem, a technique related to toner refresh is known in which the toner in the developing device is periodically replaced with new toner.

JP 2011-221531 A

  If the toner refresh is automatically executed regardless of the user's intention, the use of the image forming apparatus is restricted while the toner refresh is being executed. For example, when the user tries to use the image forming apparatus while toner refresh is being performed, the user waits for the toner refresh to be completed before using the image forming apparatus, which is inconvenient.

  In addition, the image forming apparatus can perform toner refresh in response to a toner refresh instruction from the user. However, when performing toner refresh only by an instruction from the user, the user can perform toner refresh at an appropriate timing. An instruction must be given, which is a burden on the user.

  An object of the present invention is to provide an image forming apparatus that can efficiently perform toner refresh.

  The image forming apparatus according to the embodiment includes a first drum, a second drum, an image forming unit including a transfer belt, a first cleaner, a second cleaner, and a control unit. The image forming means transfers a first toner image held on a first drum to a first recording medium, and forms a first image corresponding to the first toner image on the first recording medium. The first image forming mode, or the first and second toner images held on the first and second drums are transferred to a second recording medium, and correspond to the first and second toner images. A second image forming mode for forming a second image on the second recording medium is executed. The first cleaner is configured to transfer the first toner image after the first toner image transfer process in the first image forming mode or after the first toner image transfer process in the second image formation mode. The first toner supplied to the drum is removed. The second cleaner removes the second toner supplied to the second drum after the transfer processing of the second toner image in the second image forming mode. In response to execution of the first image forming mode, the control unit supplies the first toner to the first drum, and further supplies the second toner to the second drum. In a toner refresh mode in which the first toner image held on the first drum is transferred, and the second toner supplied to the second drum is removed by the second cleaner. Control execution.

2 is a diagram illustrating an example of an MFP according to an embodiment. FIG. FIG. 2 is a diagram illustrating an example of a configuration around an MFP photosensitive drum according to the embodiment. 1 is a diagram illustrating an example of an MFP control system according to an embodiment. FIG. 6 is a flowchart illustrating an example of toner refresh control according to the exemplary embodiment.

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

  FIG. 1 is a diagram illustrating an example of an MFP (Multi-Functional Peripheral) to which the embodiment is applied.

  An MFP 101 shown in FIG. 1 is an image forming unit 1 that outputs image information as image output in a state in which toner is fixed on, for example, plain paper or an OHP sheet that is a transparent resin sheet. , A sheet supply unit 3 that supplies a sheet of an arbitrary size used for image output to the image forming unit 1, image information that is an object on which an image is formed in the image forming unit 1, and a reading object that holds the image information ( (Hereinafter referred to as a manuscript) includes an image reading unit 5 that captures image data.

  The image reading unit 5 includes a document table (document glass) 5a that supports a document and an image sensor, for example, a CCD sensor, that converts image information into image data. The image reading unit 5 converts the reflected light obtained by irradiating the illumination light from the illumination device onto the document set on the document table 5a into an image signal by the CCD sensor.

  Further, when the document is a sheet, the image reading unit 5 discharges the read document from the discharge unit, and at the reading position following the image formation or image capture (hereinafter referred to as reading) of the next document. An automatic document feeder (ADF) 7 for guiding is integrally provided. A document cover may be used in place of the ADF 7.

  In addition, the CCD sensor of the image reading unit 5 may be positioned in the document movement path of the document table 5 a to which the document is moved by the ADF 7. The CCD sensor of the image reading unit 5 is positioned in the document movement path of the document table 5a to which the document is moved by the ADF 7, so that the image information included in the document can be read without positioning the document on the document table 5a. .

  An operation panel (operation unit) 9 that is an operation input unit that gives an instruction to start reading image information of a document by the image reading unit 5 and start image formation to the image forming unit 1 is on the left side or right side of the image reading unit 5. Are positioned on the support 9a and the swing arm 9b (fixed to the image forming unit 1).

  The image forming unit 1 includes first to fourth photosensitive drums 11a to 11d that hold latent images, and a developing device 13a that supplies a developer, that is, toner, to the latent images held by the photosensitive drums 11a to 11d to develop the latent images. To 13d, a transfer belt 15 for sequentially holding toner images held by the photosensitive drums 11a to 11d, and first to fourth cleaners for removing toner remaining on the photosensitive drums 11a to 11d from the individual photosensitive drums 11a to 11d. 17a to 17d, a transfer device 19 that transfers the toner image held by the transfer belt 15 to a sheet that is a transparent resin sheet such as plain paper or an OHP sheet, and the toner image transferred to the sheet by the transfer device 19 is fixed to the sheet. It includes a fixing device 21 and a laser unit (exposure device) 23 that forms latent images on the photosensitive drums 11a to 11d.

  The first to fourth developing devices 13a to 13d can be any one of Bk (black, black), C (cyan), M (magenta), and Y (yellow, yellow) used to obtain a color image by subtractive color mixing. The color toner is accommodated, and the latent image held by each of the photosensitive drums 11a to 11d is visualized in any one of Bk, C, M, and Y. The order of the colors is determined in a predetermined order according to the image forming process and the characteristics of the toner.

  The transfer belt 15 holds the toner images of the respective colors formed by the first to fourth photosensitive drums 11a to 11d and the corresponding developing devices 13a to 13d in the order of toner image formation.

  The transfer belt 15 sets the pressure exerted by the belt facing member 51 that sets the pressure between the photosensitive drums 11 a to 11 d of the image forming unit 1 and the transfer belt 15 and the belt cleaner 53 that cleans the surface of the transfer belt 15. The belt cleaner facing member 55 and the sheet receive a predetermined pressure that is a tension toward the outside from each of the support rollers 57 that sets the pressure on the transfer belt 15 side when contacting the transfer belt 15 by the pressure from the transfer device 19. .

  The paper supply unit 3 supplies a sheet for moving the toner image to the transfer device 19 at a predetermined timing.

  Cassettes not described in detail located in the plurality of cassette slots 31 accommodate sheets of any size, and the pickup roller 33 takes out the sheets from the corresponding cassettes according to the image forming operation. The sheet size corresponds to the magnification required for image formation and the size of the toner image formed by the image forming unit main body 1.

  The separation mechanism 35 prevents the pickup roller 33 from taking out two or more sheets from the cassette.

  The plurality of transport rollers 37 send the sheet separated by the separation mechanism 35 into one sheet toward the aligning roller 39.

  The aligning roller 39 sends the sheet to a transfer position where the transfer device 19 and the transfer belt 15 are in contact with the transfer device 19 at a timing when the toner image is transferred from the transfer belt 15.

  The fixing device 21 fixes a toner image corresponding to image information on a sheet, and as an image output (hard copy or printout), a stock unit 47 located in a space between the image reading unit 5 and the image forming unit main body 1. Send to.

  The transfer device 19 is positioned in an automatic duplex unit (ADU) 41 that replaces both sides of a sheet that is an output image (hard copy / printout) on which a toner image is fixed by the fixing device 21. A bypass tray is attached to the ADU 41.

  In the image forming unit 1, the ADU 41 is jammed between the (final) transport roller 37 and the aligning roller 39, or between the aligning roller 39 and the fixing device 21 or between the transfer device 19 and the fixing device 21. If it is jammed, move to the side (right side). The ADU 41 integrally includes a cleaner 43 that cleans the transfer device 19.

  A media sensor 45 positioned between the conveying roller 37 and the aligning roller 39 detects the thickness of the sheet conveyed to the aligning roller 39.

  FIG. 3 is a diagram showing an example of a control system of the MFP shown in FIG.

  The MFP 101 includes a system bus 111. The system bus 111 is connected to a main control block that processes output of a copy of a document by the image forming unit 1, that is, a main CPU 112. The MFP 101 includes a scanner (image reading unit) 5 and an image processing unit 117. The MFP 101 includes a motor driver 119 that supplies a pulse for rotating the stepping motor 151. The rotation angle of the stepping motor 151 is defined by the number of pulses. The stepping motor 151 rotates the first to fourth photosensitive drums 11a to 11d. The MFP 101 includes a motor driver 120 that supplies a pulse for rotating the stepping motor 75. The rotation angle of the stepping motor 75 is defined by the number of pulses. The main control block 112 includes a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, a non-volatile memory 115 that stores the total number of image formations, a total operation time, and the like, and a media sensor 45. Are connected to the interface 116 and the operation panel 9 for inputting the output to the main CPU 112. The image processing unit 117 is connected to the page memory 118.

  Hereinafter, an example of toner refresh control by the MFP 101 described above will be described.

Overview of Toner Refresh Control Upon receiving a monochrome printing request, the MFP 101 executes monochrome printing (first image formation mode). In response to execution of the first image formation mode, the MFP 101 executes toner refresh. .

  Corresponding to the execution of the first image forming mode, the Y, M, and C drums (photosensitive drums 11d, 11c, and 11b) are separated (completely separated) from the transfer belt 15. For example, as shown in FIG. 2, the transfer belt 15 is inclined from the horizontal state, the transfer belt 15 is in contact with the photosensitive drum 11a, and the transfer belt 15 is separated from the photosensitive drums 11d, 11c, and 11b. Become. Alternatively, the transfer belt 15 maintains a horizontal state, the photosensitive drums 11d, 11c, and 11b move (fall), the transfer belt 15 and the photosensitive drum 11a come into contact, and the transfer belt 15 and the photosensitive drums 11d and 11c. , 11b are separated from each other.

  As described above, with the Y, M, and C drums being separated from the transfer belt, the MFP 101 charges the entire Y, M, and C drums so that the Y, M, and C toners are covered with the cleaner (first 4, the toner is discharged as waste toner by the third and second cleaners 17d, 17c, and 17b). At this time, the Y, M, and C drums are not exposed. As described above, since the Y, M, and C drums are separated from the transfer belt, the toner on the Y, M, and C drums is not transferred onto the transfer belt 15.

  As described above, since the MFP 101 executes toner refresh control in the background of monochrome printing, various image forming processes can be executed without waiting for the user.

Details of Toner Refresh Control FIG. 4 is a flowchart illustrating an example of toner refresh control.

  When the main control device 112 of the MFP 101 receives a monochrome printing request from the operation panel 9 (ACT1, YES), it instructs the execution of monochrome printing (first image forming mode) (ACT2). In response to the execution of the image forming mode, it is determined whether or not to perform toner refresh.

  For example, when the deterioration of the image quality is detected (ACT3, YES), the main control device 112 instructs the execution of the toner refresh in response to the execution of the first image forming mode (ACT4). Conversely, if the CPU 51 has not detected a decrease in image quality, the CPU 51 does not instruct execution of toner refresh in response to execution of the first image forming mode.

  That is, when the main control device 112 detects a decrease in image quality (ACT3, YES), the image forming unit 1 corresponds to the first image forming mode execution instruction and the toner refresh execution instruction. In the execution of the first image forming mode, toner refresh is executed (ACT5). When main controller 112 detects a decrease in image quality (ACT3, NO), image forming unit 1 executes the first image forming mode in response to the instruction to execute the first image forming mode. (ACT6).

  For example, the toner concentration detection unit 121 includes the toner concentration scraped off from the photosensitive drum 11a by the first cleaner 17a, the toner concentration scraped off from the photosensitive drum 11b by the second cleaner 17b, and the third cleaner 17c. Detects the density of the toner scraped off from the photosensitive drum 11c, and the density of the toner scraped off from the photosensitive drum 11d by the fourth cleaner 17d. The main control device 112 instructs toner replenishment based on the toner density detected by the toner density detecting unit 121. For example, when the density of the toner scraped off from the photosensitive drum 11d by the fourth cleaner 17d is lower than the reference value, the main control unit 112 instructs the supply of Y toner.

  The toner replenishment control unit 122 includes a toner replenishment motor, and replenishes Y toner from the Y toner replenishment unit to the developing device 13d based on a toner replenishment instruction from the main control device 112, and develops from the M toner replenishment unit. M toner is supplied to the device 13c, C toner is supplied from the C toner supply portion to the developing device 13b, and K toner is supplied from the K toner supply portion to the developing device 13a. That is, the toner replenishment control unit 122 replenishes the amount of Y toner (how long) or when the amount of M toner is replenished (or how long). Replenished), how much C toner was replenished (or how long), and how much K toner was replenished (or how long) Toner replenishment information.

  The main control device 112 can detect a decrease in image quality from the toner supply information. For example, if Y toner has not been replenished for a long time, it can be determined that the image quality of Y has deteriorated. Alternatively, a decrease in image quality may be detected based on the count values of the Y, M, C, and K pixel counters of the image forming unit.

  It should be noted that execution of toner refresh may be instructed when a decrease in image quality of at least one of Y, M, and C is detected, and if a decrease in image quality of Y is detected, the Y toner When refresh is instructed and a decrease in image quality of M is detected, an instruction to refresh M toner is instructed. When a decrease in image quality of C is detected, refresh of C toner is executed. You may make it indicate.

  For example, if it is determined that any one of the past 500 Y, M, and C printing rates is low, monochrome printing is started with the Y, M, and C drums separated from the transfer belt. The toner is charged so that the toner is covered on the drum of the color determined to be low printing on the back side, and scraped off as waste toner by a cleaner. Further, the toner density detection unit 121 is monitored, and if it is determined that the toner density is low, toner supply is also performed. The condition for determining low printing may be from the driving time of the toner replenishing motor or from the total of the pixel force counters.

  Here, the first image formation mode (monochrome printing) in which an image is formed with K toner, the second image formation mode in which an image is formed with Y, M, C, and K toners, and toner refresh will be summarized.

First image forming mode (monochrome printing)
The image forming unit 1 transfers the K toner image formed by the K toner held on the K drum to the recording medium via the transfer belt and the transfer device based on the execution instruction of the first image forming mode. A first image forming mode for forming an image corresponding to the K toner image on the recording medium is executed.

Second Image Forming Mode The image forming unit 1 is formed with Y, M, C, and K toners held on Y, M, C, and K drums based on the execution instruction of the first image forming mode. Second image forming mode in which Y, M, C, and K toner images are transferred to a recording medium via a transfer belt and a transfer device, and an image corresponding to the Y, M, C, and K toner images is formed on the recording medium. Execute.

Toner refresh The image forming unit 1 supplies K toner to the K drum for the purpose of image formation based on the first image forming mode and the toner refresh execution instruction, and further the Y drum for the purpose of toner refresh. The first refresh toner supply for supplying Y toner to the second, the second refresh toner supply for supplying M toner to the M drum for the purpose of toner refresh, and the C drum for the purpose of toner refresh For at least one of the third refresh toner supplies for supplying the C toner, the K toner image held on the K drum is transferred to the transfer belt, and the first refresh toner is supplied. When the supply is being performed, the Y toner supplied to the Y drum is removed by a cleaner, and the second refreshing step is performed. When toner supply is executed, the M toner supplied to the M drum is removed by a cleaner, and when the fourth refresh toner supply is executed, it is supplied to the C drum by a cleaner. Remove C toner. As described above, the Y, M, and C drums are separated (completely separated) from the transfer belt 15 in correspondence with the execution of the first image forming mode. In this embodiment, the first image formation mode using one type of toner (first toner) and four types of toner (first toner are used) are not transferred to the transfer belt. The refresh toner control according to the present embodiment is based on the first image forming mode using one type of toner (first toner) and two or more types. The present invention can be applied to a device that presupposes the second image forming mode using the toner (including the first toner).

  Hereinafter, embodiments will be summarized.

  (1) An image forming apparatus having a mechanism capable of performing monochrome printing with the Y, M, and C drums separated from the transfer belt and capable of determining the deterioration of each color toner is , C When the deterioration of the toner is detected, the toner of the corresponding color is charged so that it is covered with the toner during monochrome printing, and the toner is scraped off by the blade, so that the deteriorated toner can be discharged. .

  (2) Further, the image forming apparatus is equipped with an auto toner sensor, and when the deteriorated toner is discharged, the toner can be replenished when it is determined by the auto toner sensor that the toner density in the developing device is low.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Image formation part, 101 ... MFP, 112 ... Main-control apparatus

Claims (5)

A first drum that receives the supply of the first toner and holds the first toner;
A second drum that receives the second toner and holds the second toner;
A first toner image formed by the first toner held on the first drum is transferred to a first recording medium, and a first image corresponding to the first toner image is transferred to the first toner image. The first image forming mode to be formed on the recording medium, or the first and second toner images formed by the first and second toners held on the first and second drums are second recorded. Transfer means including a transfer belt for executing a second image forming mode in which a second image corresponding to the first and second toner images is transferred to the medium and formed on the second recording medium;
After the transfer process of the first toner image in the first image formation mode or after the transfer process of the first toner image in the second image formation mode, the first toner supplied to the first drum is supplied. A first cleaner that removes one toner;
A second cleaner for removing the second toner supplied to the second drum after the transfer processing of the second toner image in the second image forming mode;
Corresponding to the execution of the first image forming mode, the first toner is supplied to the first drum, the second toner is supplied to the second drum, and Control means for executing a toner refresh mode for transferring the first toner image held on the first drum and removing the second toner supplied to the second drum by the second cleaner; ,
An image forming apparatus comprising: A third drum for receiving a third toner and holding a third toner image;
A fourth drum for receiving a fourth toner and holding a fourth toner image;
A third cleaner for removing the third toner supplied to the third drum after the transfer processing of the third toner image in the second image forming mode;
A fourth cleaner for removing the fourth toner supplied to the fourth drum after the transfer processing of the fourth toner image in the second image forming mode;
The transfer means includes first, second, third, and fourth toners formed by the first, second, third, and fourth toners held on the first, second, third, and fourth drums. 3. Transfer the fourth toner image to the second recording medium and form the second image corresponding to the first, second, third, and fourth toner images on the second recording medium. Execute the second image forming mode,
In response to execution of the first image forming mode, the control unit supplies the first toner to the first drum, and further supplies the second toner to the second drum. The first refresh toner is supplied to the third drum, the second refresh toner is supplied to the third drum, and the fourth toner is supplied to the fourth drum. At least one refresh toner supply of the third refresh toner supply is executed, the first toner image held on the first drum is transferred to the transfer belt, and the first refresh toner supply is performed. When the second refresh toner supply is executed, the second toner supplied to the second drum is removed by the second cleaner when the second refresh toner supply is executed. The third cleaner removes the third toner supplied to the third drum by the third cleaner, and the fourth cleaner supplies the fourth toner when the fourth refresh toner supply is executed. The image forming apparatus according to claim 1, wherein a toner refresh mode for removing the fourth toner supplied to the drum is executed. The transfer unit executes the first image forming mode by bringing the first drum and the transfer belt into contact with each other and separating the second, third, and fourth drums from the transfer belt. Performing the second image forming mode by bringing the first, second, third, and fourth drums into contact with the transfer belt,
The image forming apparatus according to claim 2, wherein the control unit rotates the first, second, third, and fourth drums in response to execution of the first image forming mode. Image quality detecting means for detecting a decrease in image quality due to at least one of the second, third, and fourth toners;
The image forming apparatus according to claim 2, wherein the control unit executes the toner refresh mode based on the detection of the deterioration of the image quality. Image quality detecting means for detecting a first image quality degradation due to the second toner, a second image quality degradation due to the third toner, and a third image quality degradation due to the fourth toner;
The control means executes the first refresh toner supply based on the detection of the first image quality degradation by the second toner, and the second cleaner supplies the second drum to the second drum. When the second toner is removed, and when the second image quality deterioration due to the third toner is detected, the second refresh toner supply is executed, and the third cleaner performs the third drum. When the third toner supplied to the printer is removed, and when the third image quality deterioration due to the fourth toner is detected, the third refresh toner supply is executed, and the fourth cleaner 4. The image forming apparatus according to claim 2, wherein the toner refresh mode for removing the fourth toner supplied to the fourth drum is executed. 5.

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