JP2005257796A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the press-contact period of a developing roller and a supply roller and to realize high-quality image formation by switching and operating a developing cartridge to be used as much as possible in loading a plurality of developing cartridges in which the same color toner is stored in order to realize long-term image formation which does not require the frequent replenishing work of the toner. <P>SOLUTION: In the image forming apparatus, the toner is stuck to an electrostatic latent image on the surface of a photoreceptor drum 32 so as to develop the image by rotating the developing roller 37b and the supply roller in a press-contact state only at a developing position where a plurality of developing cartridges 37 housed in a developing rotary unit 33 and storing the same color toner are opposed to the drum 32. An engine control part rotates the unit 33 so as to switch the cartridge 37 before the life of the cartridge 37 ends, for example, when integrated operation time attains set time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly, to an apparatus for mounting a plurality of developing cartridges that store toner of the same color and minimizing adverse effects caused by stopping other than operating developing cartridges.

  2. Description of the Related Art Conventionally, an electrophotographic recording type image forming apparatus that exposes and forms an electrostatic latent image on the surface of a carrier made of a photoreceptor is known. In this image forming apparatus, the electrostatic latent image is developed with toner. The toner image on the surface of the carrier carried in this manner is transferred to a recording medium such as recording paper to form an image. The electrostatic latent image is developed by rotating the developing roller facing the surface of the carrier and transferring the toner on the surface to adhere the toner. The supply roller that rotates in the space rotates by pressure to supply toner.

  An image forming apparatus that employs such an electrophotographic recording system replenishes toner by detaching a developing cartridge in which a developing roller and a supply roller are disposed in a container that accommodates the toner. In this image forming apparatus, it has been proposed that a plurality of developing cartridges can be mounted, and that the same color toner can be accommodated in the developing cartridge. In this case, by switching the developing cartridge for attaching the toner to the surface of the carrier at the timing of running out of the toner, it is possible to reduce the number of toner replenishments and continue image formation over a long period of time (for example, Patent Document 1). 2).

Here, the image forming apparatuses described in Documents 1 and 2 are of the rotary type in which a plurality of developing cartridges are housed and mounted around the rotary shaft of the rotary unit. There is also a tandem type device juxtaposed.
JP 2002-351190 A JP 2003-316106 A

  In such an image forming apparatus in which a plurality of developing cartridges can be mounted, as described in the above-mentioned documents 1 and 2, after the toner in the developing cartridge facing the carrier is used up, the next developing cartridge is used. By switching, long-term image formation that does not require toner replenishment is realized. Note that the document 1 also describes that the developing cartridge is switched before the toner around the supply roller runs out. With this configuration, the toner is completely lost and development is impossible. The time lag for determination can be eliminated, and more continuous image formation is realized.

  Further, such an image forming apparatus is configured to transmit a rotational driving force by connecting only a developing roller and a supply roller of a developing cartridge that develops an electrostatic latent image facing the surface of the carrier to a driving source. There are types that have been.

  However, in this type of image forming apparatus, since the developing cartridge other than the image forming process remains stopped, the developing roller and the supply roller are kept in pressure contact at the same location. For this reason, if an attempt is made to form a new image by switching the developing cartridge, the effect may occur. That is, when the developing roller is stopped for a long time, the trace of the pressure contact of the supply roller remains on the surface, and when the toner adheres to the surface of the carrier, the position corresponding to the pressure contact position There will be a difference with other locations. As a result, for a while after the start of image formation, streak marks (so-called neglected banding) for each rotation of the developing roller appear in the toner image, reducing the quality of the image to be formed. End up.

  Here, in this specification, as a so-called neglected banding, a case where the pressure contact trace with the supply roller appears in the toner image according to the period during which the developing roller stops is described as an example, but the image quality is deteriorated. The present invention is not limited to this, and includes a case where the development surface of the developing roller is divided into two inside and outside of the container, so that the characteristic varies depending on the stop period. For example, when the exposure period to the outside becomes longer, the case where the attached toner changes in quality or the development surface of the developing roller changes in quality due to the attached toner is also included as a disadvantage due to neglected banding. Such an inconvenience is solved by rotating the developing roller.

  Therefore, even if the present invention is a type in which only the developing cartridge to be used is driven, it is possible to switch the developing cartridge as much as possible to shorten the stop period of the developing roller and to reduce the frequency of toner. An object of the present invention is to provide an image forming apparatus capable of performing high-quality image formation while realizing long-term image formation that does not require replenishment.

  An image forming apparatus according to a first aspect of the present invention for solving the above-described problems includes a carrier for carrying a toner image in which an electrostatic latent image is formed on the surface and developing the electrostatic latent image, and an electrostatic latent image on the surface of the carrier. A plurality of developing cartridges for developing toner by attaching toner to the image, and cartridge switching means for forming a toner image by causing only one of the plurality of developing cartridges to face the surface of the carrier and operating only the developing cartridge And an image forming apparatus that mounts a plurality of developing cartridges containing toner of the same color and transfers a toner image formed on the surface of the carrier onto the surface of the recording medium to form an image. Comprises a container for containing toner, and a developing roller that rotates while facing the carrier and adheres the toner to the surface of the carrier, and the cartridge switching means includes a developer cartridge. Switched repeatedly developing cartridge to be used before reaching the lifetime is characterized in that to form a toner image.

  According to the present invention, by providing a plurality of developing cartridges that store toner of the same color, it is possible to realize long-term image formation that does not require toner replenishment work (development cartridge replacement work) each time the developing cartridge runs out of toner. Can do. In addition, before reaching the timing at which the developing cartridge with which the developing roller faces the carrying member has to be switched due to its life, the developing cartridge is switched to the next developing cartridge, and the individual developing rollers are sequentially driven and rotated. Therefore, the developing roller can be stopped as much as possible shorter than before, for example, the period during which the developing roller is in pressure contact with the supply roller that supplies the toner in the container can be made shorter than before. Thus, it is possible to avoid the so-called neglected banding in which the trace of the pressure contact position appears in the transferred toner image.

  According to a second aspect of the image forming apparatus for solving the above-mentioned problem, in addition to the specific matters of the first aspect, the cartridge switching means ends the processing before starting the processing of the image forming job or ends the processing. After that, by switching the developing cartridge opposed to the carrier, the developing cartridge is repeatedly used before reaching the end of its service life.

  In the present invention, when the developing cartridge facing the carrier receives an image forming job regardless of its lifetime, the developing cartridge is switched to the next developing cartridge before or after processing the job. In other words, the developing cartridge is switched to the next developing cartridge at least once between jobs regardless of the size of the image forming job. Therefore, it is possible to repeatedly switch the developing cartridge so as not to leave banding without disturbing the execution of the image forming job process.

  According to a third aspect of the image forming apparatus for solving the above-mentioned problems, in addition to the specific matter of the first or second aspect, the cartridge switching means counts an accumulated time for continuous image formation with one developing cartridge. When the accumulated time reaches a preset integration time, the developing cartridge is switched to be opposed to the carrier so that the developing cartridge is repeatedly switched before reaching the end of its service life. It is characterized by.

  In the present invention, the developing cartridge facing the carrier is switched to the next developing cartridge when the integrated time of the image forming operation after switching reaches the set time regardless of the lifetime. In other words, the developing cartridge is repeatedly switched to the next developing cartridge when the image formation is continuously processed. Therefore, it is possible to repeatedly switch the developing cartridge so that the neglected banding does not occur.

  According to a fourth aspect of the image forming apparatus for solving the above-mentioned problems, in addition to the specific matters of the first or second aspect, the cartridge switching means continuously forms an image with one developing cartridge and forms a toner on a recording medium. There is a counting means for counting the cumulative number of images to be transferred. When the counted number reaches the preset cumulative number, the developing cartridge is switched to the opposite side of the carrier to reach the end of its life. It is characterized by being repeatedly switched before and used.

  In the present invention, the developing cartridge facing the carrier is switched to the next developing cartridge when the cumulative number of images formed after switching reaches the set number regardless of the life. In other words, the developing cartridge is repeatedly switched to the next developing cartridge when the image formation is continuously processed. Therefore, it is possible to repeatedly switch the developing cartridge so that the neglected banding does not occur.

  According to the present invention, the plurality of developing cartridges containing toner of the same color are not used continuously until the developing cartridge facing the carrier becomes unusable (before reaching the timing at which switching is required depending on the life). For example, every time the image forming job is switched to the next developing cartridge before or after the image forming job, the operation time after switching reaches the set time, or the image forming number after switching reaches the set number Thus, the developing roller for each developing cartridge can be rotated one after another.

  Therefore, the period during which the developing roller is stopped can be shortened as much as possible to avoid the occurrence of neglected banding, and at the same time as long-term image formation that does not require toner replenishment work is achieved, and high quality Image formation can be performed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. 1 to 6 are views showing an example of a printer to which the first embodiment of the image forming apparatus according to the present invention is applied.

  1 and 2, the printer is used to create and output images such as characters, for example, connected to a personal computer PC, and a control unit 10 connected to the personal computer PC is used as a paper transport device. The image is formed (printed) on the recording paper (recording medium) S by comprehensively controlling the image recording apparatus 20 and the image recording apparatus 30.

  The control unit 10 is composed of a controller unit 11 and an engine control unit 12 constructed on a circuit board mounted in the printer. Execute drive control.

  In brief, the controller unit 11 executes various processing procedures according to a processing program stored in a memory by a CPU (not shown), thereby various information such as a print command with a printer driver of the personal computer PC. The image data to be printed (image formation) on the recording paper S is received and temporarily stored in a memory (not shown). The controller unit 11 is so-called RGB data of red (R), green (G), and blue (B) because the image data (image information signal) received from the personal computer PC is yellow (which can be printed). Y), magenta (M), cyan (C), and black (K) are converted into image data of so-called YMCK data, read out from the memory, and transferred to the engine control unit 12.

  In the engine control unit 12, the CPU 13 receives image data, for example, in units of pages from the controller unit 11 according to a control program stored in the ROM 14, temporarily stores it in the main body memory 15, and uses the RAM 16 as a work area. While various information is exchanged between the paper transport device 20 and the image recording device 30, an image based on the image data is formed on the recording paper S. At this time, when executing this image formation control, the CPU 13 causes each unit of the apparatus to operate optimally by measuring various processing times with a built-in timer function (timer) 13a.

  In FIG. 2, the I / O interface 17 connects the controller unit 11, the sheet transport device 20, the image recording device 30, and the engine control unit 12 so that various types of information can be exchanged. The D / A converter 18 and the A / D converter 19 are configured so that the engine control unit 12 can process various information exchanged between the controller unit 11, the sheet conveying device 20, and the image recording device 30, respectively. A digital signal is converted into an analog signal, or an analog signal is converted into a digital signal.

  In addition to the paper cassette 21, the paper discharge table 22, the pickup roller 23, the transport roller pair 24, the registration roller pair 25, the switching roller pair 26, the paper discharge roller pair 27, and the reverse roller pairs 28 and 29. The intermediate transfer belt 34, which is also a component of the image recording apparatus 30, the transfer roller 35, and the fixing roller pair 36 are constructed. The sheet conveying apparatus 20 separates and conveys a plurality of recording sheets S stacked in the sheet cassette 21 one by one and feeds them to the image recording position P of the image recording apparatus 30, thereby recording the recording sheets. After image data such as characters received on one side or both sides of S is recorded and formed, the recording paper S on which the image has been formed is carried out of the apparatus and stacked on the discharge table 22.

  Briefly, the pick-up roller 23 is pressed against the recording paper S loaded in the paper cassette 21 to pull out the recording paper S and to separate it one by one in cooperation with a separating means (not shown). Then, the sheet is fed to the conveyance path f. The conveyance roller pair 24 nips and conveys the recording sheet S and corrects the skew by abutting the leading end against the nip portion of the downstream registration roller pair 25. The registration roller pair 25 nipping and feeding the recording sheet S to the image recording position P in synchronization with the operation of the image recording apparatus 30.

  At the image recording position P, the intermediate transfer belt 34 and the transfer roller 35 rotate while sandwiching the fed recording paper S, thereby recording and forming an image on one side of the recording paper S. To do. The fixing roller pair 36 rotates while pinching the recording paper S, thereby fixing the image on the recording paper S and conveying it further downstream.

  Thereafter, the switching roller pair 26 and the discharge roller pair 27 carry the recording paper S from the fixing roller pair 36 onto the discharge table 22 and stack it. As a result, the recording sheet S is fed to the recording formation position P of the image by the image recording apparatus 30 and formed on one side with the one side as an image recording formation surface, and then discharged onto the discharge table 22. Is done.

  At this time, when the duplex control mode for forming an image on both sides of the recording paper S is instructed to the engine control unit 12, the paper transport device 20 carries the paper discharge roller pair 27 onto the paper discharge table 22. After temporarily stopping at a position where the rear end portion of the recording sheet S is sandwiched, the recording sheet S on which an image is recorded on one side is sent out to the reversing path r by being reversely driven together with the switching roller pair 26.

  Thereafter, the reversing roller pair 28, 29 sandwiches the recording paper S and feeds and conveys the recording paper S into the reversing path r, so that the rear end side at the time of image formation on one side is set as the front end side. The recording sheet S with the front and back reversed is fed again to the transport path f and delivered to the registration roller pair 25. As a result, the recording sheet S is fed again to the image recording position P by the image recording apparatus 30 with the other side (one side where no image is recorded and formed) as the image recording and forming surface. After being formed, the sheet is discharged onto the discharge table 22.

  On the other hand, the image recording device 30 includes a laser beam scanning device 31, a photosensitive drum (carrier) 32, a developing rotary unit 33, an intermediate transfer belt 34, a transfer roller 35, and a fixing roller pair 36. ing. This image recording apparatus 30 receives received image data such as characters on one side or both sides of the recording sheet S conveyed by the sheet conveying apparatus 20 and fed to the image recording position P by electrophotography. Record formation.

  In brief, the laser beam scanning device 31 selectively irradiates the surface of the photosensitive drum 32 with the laser beam L based on the received image data, and performs exposure scanning, thereby causing an electrostatic latent image based on the image data. An image is formed (image formation) on the surface of the photosensitive drum 32. The developing rotary unit 33 houses a developing cartridge 37 for each color that develops the electrostatic latent image on the photosensitive drum 32 with yellow (Y), cyan (C), magenta (M), and black (K) toners. Then, the developing cartridge 37 corresponding to the image data for forming the electrostatic latent image is attached to the toner accommodated facing the photosensitive drum 32 to develop the electrostatic latent image with toner.

  In the case of a monochrome image, the intermediate transfer belt 34 receives a toner image of black (K) toner formed on the photosensitive drum 32, and transfers the toner image (toner image) onto the recording paper S onto the belt surface. Hold. In addition, in the case of a color image, the intermediate transfer belt 34 sequentially forms toner images with yellow (Y), cyan (C), and magenta (M) toner formed on the photosensitive drum 32 (the order is the same). The toner image is received in a superimposed manner, and a color toner image to be transferred onto the recording paper S is formed and held on the belt surface. The transfer roller 35 presses (nips) the recording paper S fed between the intermediate transfer belt 34 (image recording position P) and sandwiches and conveys the toner image. Transfer onto the recording paper S. That is, in the present embodiment, a transfer system in which the transfer of the toner image onto the recording paper S is mediated by the intermediate transfer belt 34 is employed. Needless to say, the toner transfers from the developing cartridge 37 to the recording paper S via the photosensitive drum 32 and the intermediate transfer belt 34 in accordance with the bias voltage between the members.

  The fixing roller pair 36 fixes the toner image by heat-pressing the recording sheet S transferred from the recording position P of the image to which the toner image has been transferred, and sandwiches the recording sheet S further downstream. Transport. As a result, the recording sheet S is recorded (fixed) on one side or both sides of a monochrome image or a color image based on the received image data. By repeating such an operation, images are continuously displayed on a plurality of sheets. Records can be formed.

  Note that the toner remaining on the photosensitive drum 32 after being transferred to the intermediate transfer belt 34 is discharged and collected by the cleaning device 38, and thereafter the toner is received from the developing cartridge 37 of the developing rotary unit 33 by the charger 39. Charged to the potential to be deposited. Although not specifically shown, the intermediate transfer belt 34 is similarly discharged and charged, and toner transfer (attachment) and recovery are repeated.

  The developing rotary unit 33 of the printer is configured by housing a plurality of developing cartridges 37 for developing toner on the electrostatic latent image on the surface of the photosensitive drum 32 in a cylindrical housing 41. The developing rotary unit 33 rotates the housing 41 around the rotation shaft 41a based on a print command including image data from the personal computer PC received by the CPU 13 of the engine control unit 12 via the controller unit 11. The developing cartridge 37 that faces the photosensitive drum 32 is switched. That is, the CPU 13 of the engine control unit 12 constitutes a cartridge switching means.

  Specifically, the housing 41 is divided into four equal spaces 41y, 41m, 41c, and 41k extending in the axial direction around the rotation shaft 41 by a frame 41b that substantially matches the normal direction from the rotation shaft 41a. The printer accommodates (installs) a developing cartridge 37 that accommodates toner in each of the spaces 41y, 41m, 41c, and 41k so that a color image, a multicolor image, or a single color image can be printed on one side of the recording paper S or Can be formed on both sides. For example, in such a printer, development that accommodates yellow (Y), cyan (C), magenta (M), and black (K) toners in the housing spaces 41y, 41m, 41c, and 41k of the housing 41, for example. The developing rotary unit 33 (housing 41) is rotated to switch the developing cartridge 37 that develops the electrostatic latent image on the photosensitive drum 32 so that the cartridges 37 are housed and the respective color toners are overlapped or selected. Thus, it can be used as an apparatus capable of forming a color image to a single color image. In addition, the printer stores a developing cartridge 37 that stores toner of the same color in all of the storage spaces 41y, 41m, 41c, and 41k of the housing 41, and rotates the developing rotary unit 33 on the photosensitive drum 32. By sequentially switching the developing cartridge 37 that develops the electrostatic latent image, it can also be used as a dedicated machine for forming a monochrome image (monochrome image). In this case, image formation can be continued (continuous for a long period of time) without performing the replacement work (toner replenishment work) of the developing cartridge 37 every time the toner runs out. In this printer, a developing cartridge 37 that stores toner of the same color is stored in two or more locations in the storage spaces 41y, 41m, 41c, and 41k of the housing 41, and a multicolor image or a single color that is color-coded by each color toner is stored. It can also be used as an apparatus capable of forming an image.

  As described above, the developing cartridge 37 is housed in the housing spaces 41y, 41m, 41c, and 41k of the housing 41, and can sequentially face the photosensitive drum 32 by rotating around the rotation shaft 41a. The inside of the photosensitive drum 32 is similarly configured so that the electrostatic latent image on the surface of the photosensitive drum 32 can be developed with toner by the same drive control.

  As shown in FIG. 3, the developing cartridge 37 includes a container 37a, a developing roller 37b, a supply roller 37c, and a partition plate 37d. The container 37a is formed in a similar shape so that it can be stored in each of the storage spaces 41y, 41m, 41c, 41k of the housing 41, and stores toner. The developing roller 37b is rotatably supported on the outer peripheral side of the container 37a separated from the rotation shaft 41a of the housing 41, and causes the toner delivered from the supply roller 37c to adhere to the opposing photosensitive drum 32. The supply roller 37c is rotatably supported by the container 37a so as to be adjacent to the developing roller 37b on the rotating shaft 41a side of the housing 41, and wears and charges surrounding toner by rotating in pressure contact with the developing roller 37b. Supply. The partition plate 37d is installed so as to surround the supply roller 37c, and the toner storage space of the container 37a is communicated with the space on the rotating shaft 41a side of the housing 41 and the upper portion in the rotation direction of the installation space of the supply roller 37c. Partitioning.

  With this configuration, the developing cartridge 37 supplies the toner in the space on the outer periphery side of the container 37a partitioned by the partition plate 37d to the developing roller 37b in which the supply roller 37c rotates by pressure. In addition, when the housing 41 rotates by 90 degrees counterclockwise in FIG. 3 and rotates 180 degrees, the developing cartridge 37 separates toner stored in the rotating shaft 41a side and the supply roller 37c side of the container 37a. After being put together at the upper part of 37d (lower part in FIG. 3), the toner contained in the container 37a can be agitated and refreshed by further rotating by 90 degrees, and the contained toner can be supplied to the developing roller 37b. Collect on the supply roller 37c side. Here, the developing rotary unit 33 according to the present embodiment supplies toner while stirring the toner 41 toward the supply roller 37c by the rotation of the housing 41 as described above. Therefore, an apparatus (so-called agitator) for stirring and supplying toner to be stored is used. Apparatus and auger apparatus) can be omitted as appropriate. However, before the toner supplied to the developing roller 37b runs out, the developing cartridge 37, for example, a count value by a toner counter, the number of dots of an image, an accumulated developing operation (image forming) time, an accumulated number of developed images, or an actual measurement When the toner usage detected by the remaining amount of toner exceeds a preset value, it is necessary to rotate the developing rotary unit 33 to perform toner replenishment / stirring operation.

  The developing cartridge 37 includes a nonvolatile memory 42 and a developing side connector 43, and a control side connector 44 is disposed on the developing rotary unit 33 side. The nonvolatile memory 42 rewritably stores various information such as the color of toner to be stored, the date of manufacture, and the amount of consumption, along with identification information such as a manufacturing number. The development-side connector 43 is connected to the nonvolatile memory 42 and reads and rewrites information stored therein. The control-side connector 44 is arranged so as not to move to the outer periphery of the developing rotary unit 33, and exchanges various types of information by contactless communication when facing the developing-side connector 43 of any of the developing cartridges 37. As a result, the engine control unit 12 of the control unit 10 displays the toner color information of the developing cartridge 37 together with the presence / absence and position of the developing cartridge 37 stored in the storage spaces 41y, 41m, 41c and 41k of the developing rotary unit 33. It is possible to appropriately grasp various information such as.

  On the other hand, as shown in FIGS. 4 and 5, the developing rotary unit 33 that houses the developing cartridge 37 includes a rotary driving motor 47, a developing driving motor 48, a rotary input gear 51, a developing roller gear 52, and an idler. The gear 53, the development input gear 54, and the development drive gear 55 are operated in a gear train configuration in which the gears 53, the development input gear 54, and the development drive gear 55 are connected to each other, and the drive force of the rotary drive motor 47 is transmitted to drive the housing 41 to rotate. On the other hand, the developing cartridge 37 receives the driving force from the developing drive motor 48 and rotationally drives the developing roller 37b and the supply roller 37c.

  In brief, the rotary input gear 51 is fixed to one end side of the housing 41 so as to be coaxial with the rotary shaft 41 a and meshes with the motor pinion 47 a of the rotary drive motor 47. When the rotary drive motor 47 is driven in accordance with a control signal from the engine control unit 12, the development rotary unit 33 is rotated by 90 degrees and stored in the four storage spaces 41y, 41m, 41c, and 41k. The developing cartridge 37 is sequentially moved to a position facing the photosensitive drum 32.

  The developing roller gear 52 and the idler gear 53 are arranged on the individual developing cartridge 37 side, and a total of four sets are attached. The developing roller gear 52 is fixed so as to be coaxial with one end of the developing roller 37b, and is rotatably supported by the container 37a. The idler gear 53 meshes with the developing roller gear 52 and meshes with the container 37a. Is rotatably supported by the shaft. Thus, when the developing cartridge 37 is replaced, the developing roller gear 52 and the idler gear 53 are also pulled out from the housing 41 of the developing rotary unit 33 together with the developing roller 37b and the supply roller 37c.

  On the other hand, the development input gear 54 and the development drive gear 55 are disposed on the housing 41 side. A total of four development input gears 54 are attached so as to correspond to the development cartridges 37 for the storage spaces 41y, 41m, 41c, 41k of the development rotary unit 33, and idler gears for the development cartridges 37 to be inserted / removed. 53 is rotatably supported by a rotary frame 56 that rotates integrally with the rotary input gear 51 so as to be able to mesh with the rotary input gear 51. One development drive gear 55 is attached to correspond to the development drive motor 48, and meshes with a motor pinion 48 a of the development drive motor 48. The developing drive gear 55 is rotatably supported by the main body frame 57 at a position meshed with the rotating developing input gear 54, and the developing cartridge 37 to be operated is operated via the developing input gear 54. By being connected to the roller gear 52 and the idler gear 53, a transmission train wheel train for transmitting the driving force of the developing drive motor 48 is constructed.

  That is, when the development controller 37 moves to the development position facing the photosensitive drum 32 by rotating the development rotary unit 33 by driving the rotary drive motor 47 and controlling the rotary drive motor 47, the engine controller 12 The driving force from the developing drive motor 48 controlled by the motor is received via the train wheel composed of the developing roller gear 52, the idler gear 53, the developing input gear 54, and the developing driving gear 55, and the developing roller 37b and the supply roller 37c are operated. be able to. On the other hand, when the developing input gear 54 is disengaged from the developing drive gear 55 that meshes with the motor pinion 48a of the developing drive motor 48 and disengages from the train wheel from the developing drive motor 48, the developing cartridge 37 52 and the idler gear 53 do not rotate, and only move by 90 degrees in accordance with the rotation operation of the developing rotary unit 33. The developing drive gear 55 has a built-in one-way clutch so that the developing roller 37b rotates in the reverse rotation direction, and can escape when meshing with the rotating developing input gear 54. It avoids being damaged by collision.

  The CPU 13 of the engine control unit 12 executes various control operations in accordance with the control program in the ROM 14 after the power is turned on. When the power is turned on or when the developing cartridge 37 is replaced, the CPU 13 is not connected via the connectors 43 and 44. By performing contact communication, the presence / absence of the developing cartridge 37 set in the storage spaces 41y, 41m, 41c, 41k of the developing rotary unit 33 is held (stored) in the main body memory 15. Further, the CPU 13 sequentially reads out various information written in the nonvolatile memory 42 of each developing cartridge 37 via the connectors 43 and 44, and position information, toner color information and consumption for each developing cartridge 37. The amount (remaining amount) is stored in the main body memory 15. Further, the CPU 13 writes various information such as the amount of toner consumed by the image formation into the nonvolatile memory 42 of each developing cartridge 37 via the connectors 43 and 44 during the image forming operation or after the image formation is completed. rewrite.

  At this time, the CPU 13 includes a developing cartridge 37 that stores toners of each color of yellow (Y), cyan (C), magenta (M), and black (K) in the storage spaces 41y, 41m, 41c, and 41k of the developing rotary unit 33. When it is determined that the image has been set, general image formation control is executed, and the developing rotary unit 33 is rotated in accordance with the image data sent from the controller unit 11, so that a color image or A multicolor image or a single color image is recorded and formed on one side or both sides of the recording paper S. In other words, each color toner developing cartridge 37 attached to the developing rotary unit 33 operates by being appropriately switched according to the type of image based on the image data each time it receives a print command for image data. As a result, the developing cartridge 37 is appropriately changed each time the pressure contact position when the developing roller 37b and the supply roller 37c are stopped is operated, and the surface of the developing roller 37b has a pressure contact mark with the supply roller 37c. Effectively prevented. Accordingly, when the developing cartridge 37 containing different color toners is set in the developing rotary unit 33, the CPU 13 executes general image formation control to thereby form an electrostatic latent image on the surface of the photosensitive drum 32. It is possible to avoid streak marks due to the pressure contact marks of the developing roller 37b and the supply roller 37c from appearing every rotation of the developing roller 37b in the toner image adhering to and formed on the toner image. High quality image formation can be performed.

  If the CPU 13 knows that the developing cartridge 37 containing the same color toner is installed in all the storage spaces 41y, 41m, 41c, 41k of the developing rotary unit 33, the developing cartridge 37 The image data sent from the controller unit 11 is executed by performing image formation control while operating the set developing cartridge 37 as evenly as possible by repeatedly switching the timing 37 to an appropriate timing before reaching the service life limit. A single color image corresponding to the recording sheet S is formed on one side or both sides of the recording paper S. Here, the life of the developing cartridge 37 means that it is necessary to switch or replace. For example, the developing rotary unit 33 is run out because the toner to be stored runs out, or the supply roller 37c runs out of toner. This means that it is necessary to rotate the toner, or the toner to be contained cannot be frictionally charged.

  Specifically, for example, since a document or the like is often printed, a developing cartridge 37 that contains black (K) toner is installed in all of the storage spaces 41y and 41k of the developing rotary unit 33, so When forming a monochrome image, the CPU 13 executes image formation control including switching of the developing cartridge 37 in accordance with the accumulated operation time, as shown in the flowchart of FIG.

  First, when a print command for monochrome image data is received from the controller unit 11 (step S11), the developing rotary unit 33 is rotated to switch the developing cartridge 37 at the developing position (step S12). For example, when the developing cartridge 37 mounted in the storage space 41 c is waiting in a state of facing the photosensitive drum 32, the developing cartridge 37 mounted in the next storage space 41 k is opposed to the photosensitive drum 32. The developing cartridge 37 to be used is switched by moving to the developing position. Next, the built-in timer function 13a is started to measure the integrated time for developing operation (image formation) (step S13), and the drive control of the sheet conveying device 20 and the image recording device 30 for printing the received image data. To form an image on one side or both sides of the recording paper S (step S14).

  Thus, when there is a print command in the standby state, the developing cartridge 37 starts a developing operation for driving and rotating the developing roller 37b and the supply roller 37c after a switching operation for rotating the developing rotary unit 33. Accordingly, the pressure contact positions of the development roller 37b and the supply roller 37c of the development cartridge 37 can be changed sequentially (shorter than the conventional pressure contact period) every time a print command is received after waiting, and the surface of the development roller 37b It is possible to effectively prevent the pressure contact mark with the supply roller 37c from being attached to the surface. Here, in the present embodiment, the developing rotary unit 33 is rotated and the developing cartridge 37 is switched before executing the image forming operation using a print command received in the standby state as a trigger. However, the present invention is not limited to this. The developing rotary unit 33 may be rotated to switch the developing cartridge 37 after the image forming operation by the print command is completed (before shifting to the standby state).

  Next, it is confirmed whether or not there is a next print command (unprocessed print command) (step S15). If there is no unprocessed print command, the image formation control is stopped as it is. If there is, it is checked whether the accumulated operation time using the same developing cartridge 37 timed by the timer function 13a has exceeded a preset time (step S16). When the accumulated operation time does not exceed the set time, the process returns to step S14 as it is, and printing (development) of image data by the same developing cartridge 37 is continued, and image formation on the recording paper S is repeated (step S14). To S16). Here, the preset time may be set in the memory so as to be rewritable or incorporated in the control program itself. For example, the setting time is set to be short, such as 1/2 or 1/3 of the developing operation time in which it is necessary to rotate the developing rotary unit 33 and supply toner to the space between the developing roller 37b and the supply roller 37c. In an extreme case, the processing time for one recording sheet S may be set if there is no inconvenience caused by the image forming processing speed (so-called throughput), noise, and the like.

  On the other hand, when the integrated operation time using the same developing cartridge 37 counted by the timer function 13a exceeds the set time, the developing rotary unit 33 is turned on before the developing cartridge 37 reaches the use limit (life). The developing cartridge 37 mounted in the next storage space 41m is rotated and moved to the developing position facing the photosensitive drum 32 to switch (step S17). Thereafter, by returning to step S13, a series of image forming operations by switching the developing cartridge 37 is repeated every set time until there is no unprocessed print command, and a monochrome image is printed on one side or both sides of the recording paper S. Recording is performed (steps S13 to S17).

  As a result, the developing cartridge 37 is switched every time the accumulated operation time exceeds the set time, and the developing roller 37b and the supply roller 37c are sequentially driven and rotated. Accordingly, the pressure contact position when the developing roller 37b and the supply roller 37c are stopped is set to the set operation time of the developing cartridge 37 to be used in addition to the switching of the developing cartridge 37 when the printing command is received in the standby state. It is possible to effectively change the surface of the developing roller 37b from being in contact with the supply roller 37c.

  Similarly, when the developing cartridges 37 that store toner of the same color can be mounted in two or three storage spaces 41y, 41m, 41c, and 41k of the developing rotary unit 33, the developing to be used is similarly performed. Each time the integrated operation time of the cartridge 37 exceeds the set time, the developing rotary unit 33 is rotated to switch the developing cartridge 37 to be opposed to the photosensitive drum 32, whereby high-quality image formation without leaving banding occurs. It can be performed.

  As described above, in this embodiment, when the developing cartridge 37 containing the same color toner is set in the developing rotary unit 33, when the print command is received in the standby state, or the accumulated operation time exceeds the set time. Since each time the developing cartridge 37 is repeatedly switched (without continuing to use until the end of the service life), the developing roller 37b and the supply roller 37c for each developing cartridge 37 can be rotated one after another, and the pressure contact points of each other can be determined. Can be changed. Therefore, long-term continuous image formation that does not require replacement of the developing cartridge 37 every time when the toner runs out is realized, and at the same time, the period during which the developing roller 37b and the supply roller 37c are in pressure contact at the same place is made as short as possible. Therefore, it is possible to form a high-quality image without causing neglected banding.

  Next, FIGS. 7 and 8 are views showing an example of a printer to which the second embodiment of the image forming apparatus according to the present invention is applied. In addition, since this embodiment is configured in substantially the same manner as the above-described embodiment, the same reference numerals are given to the same configurations and the characteristic portions will be described using the drawings.

  In FIG. 7, the CPU 13 of the engine control unit 12 according to the present embodiment counts the number of processed sheets of recording paper S by the built-in counter function (counting unit) 13 b when executing image formation control, thereby performing paper formation. Each part of the apparatus such as the transport apparatus 20 and the image recording apparatus 30 is optimally operated.

  The CPU 13 is designed to execute image formation control including switching of the developing cartridge 37 according to the number of recording sheets S. As the number of processing sheets for switching the developing cartridge 37, for example, a developing rotary unit It is preferable to set it as small as 1/2, 1/3, etc. of the number of developed images (number of transferred toner images) that requires the toner to be replenished in the space between the developing roller 37b and the supply roller 37c by rotating 33. If there is no inconvenience due to image forming processing speed (so-called throughput), noise, etc., it may be set to one sheet. Here, the number of developed sheets may be the number of recording sheets S regardless of image formation on one or both sides, but the toner transferred to one side of the recording sheet S in order to operate the developing cartridge 37 as evenly as possible. It is preferable to count each time the image is developed.

  Then, the CPU 13 forms a monochrome image when a developing cartridge 37 containing, for example, black (K) toner is installed in all of the storage spaces 41y, 41m, 41c, 41k of the developing rotary unit 33. As shown in the flowchart of FIG. 8, image forming control is performed in which the developing cartridge 37 is repeatedly switched at an appropriate timing before reaching the service life limit according to the number of developed images. As a result, the CPU 13 executes image formation control while operating the set developing cartridges 37 as evenly as possible, and displays a monochrome image corresponding to the image data sent from the controller unit 11 on one or both sides of the recording paper S. To form a record.

  First, similarly to the above-described embodiment, when a print command is received from the controller unit 11 (step S11), the developing cartridge 37 is rotated so that the developing rotary unit 33 is rotated to oppose the photosensitive drum 32 (step S12), and built-in. After resetting the counter function 13b to start and counting the number of processed images to be processed (step S23), image formation control of the received image data is executed to form an image on one or both sides of the recording paper S (step S14). .

  Next, when it is confirmed that there is an unprocessed print command (step S15), the number of developed images using the same developing cartridge 37 counted by the counter function 13b is confirmed (step S26), and the number of developed images is set. If the number has not exceeded, the process returns to step S14 as it is, and image formation on the recording paper S using the same developing cartridge 37 is repeated (steps S14 to S26).

  On the other hand, when the number of developed images using the same developing cartridge 37 counted by the counter function 13b exceeds the set number, the developing rotary unit 33 is rotated before the developing cartridge 37 reaches the use limit (life). Then, the next developing cartridge 37 is moved to the developing position facing the photosensitive drum 32 and switched (step S17). Thereafter, by returning to step S13, a series of image forming operations by switching the developing cartridge 37 for each set number of sheets is repeated until there is no unprocessed print command, and a monochrome image is formed on one side or both sides of the recording paper S. Recording is performed (steps S13 to S17).

  As described above, also in the present embodiment, when the developing cartridge 37 that stores the same color toner is set in the developing rotary unit 33 in the same manner as the above-described embodiment, Since the developing cartridge 37 is repeatedly switched every time the number of developed sheets exceeds the set number (without being used until the lifetime of the use limit), the developing roller 37b and the supply roller 37c for each developing cartridge 37 are rotated one after another. It is possible to change the place of pressure contact with each other. Therefore, long-term continuous image formation that does not require replacement of the developing cartridge 37 every time when the toner runs out is realized, and at the same time, the period during which the developing roller 37b and the supply roller 37c are in pressure contact at the same place is made as short as possible. Therefore, it is possible to form a high-quality image without causing neglected banding.

  Here, in the first and second embodiments described above, a rotary type image that switches the developing cartridge 37 that faces the photosensitive drum 32 by rotating the developing rotary unit 33 that can store a plurality of developing cartridges 37. The forming apparatus will be described, but the present invention is not limited to this. For example, the forming apparatus can be applied to an image forming apparatus employing a tandem method.

  That is, the tandem type image forming apparatus, for example, as shown in FIG. , An intermediate transfer belt 65, a transfer roller 66, a fixing roller pair 67, and a paper discharge roller pair 68 are disposed, and an intermediate transfer is performed on one side of the recording paper S that is conveyed through the conveyance path f. An image is formed by transferring and fixing the toner image formed on the surface of the belt 65.

  The tandem intermediate transfer belt 65 includes a photosensitive drum and a developing cartridge for each color of yellow (Y), magenta (M), cyan (C), and black (K) that form a color image. It is juxtaposed in the transfer direction. The separate photosensitive drums 61y, 61m, 61c, and 61k are provided with developing cartridges that store toner of the same or different colors, and color images and multicolor images are respectively developed by the developing rollers 62y, 62m, 62c, and 62k. Alternatively, a toner image of a single color image is formed.

  For this reason, when a developing cartridge containing toner of the same color is mounted, the photosensitive drums 61y, 61m, 61c, 61k and the developing rollers 62y, 62m, 62c, 62k are individually operated, and other than those that are operated. Drive control to stop. Here, in order to individually operate the developing rollers 62y, 62m, 62c, and 62k, a separate drive motor may be disposed, or an electromagnetic clutch or the like may be interposed in the drive force transmission path.

  Therefore, such a tandem type image forming apparatus is configured in the same manner as in the above-described embodiment, and in addition to realizing long-term image formation that does not require replacement of the developing cartridge every time the toner runs out. When the print command is received in the standby state, or whenever the accumulated operation time or the accumulated number of developed sheets exceeds the set value (set time or set number), the developing roller for each developing cartridge is repeatedly switched. Etc. can be rotated one after another to form a high-quality image without leaving banding.

  The application of the first and second embodiments described above is not limited to the method using the intermediate transfer belt. For example, as shown in FIG. 10, the recording paper S is conveyed through the conveyance path f and conveyed. The present invention can also be applied to an image forming apparatus that directly transfers and fixes a toner image.

  That is, in this image forming apparatus, instead of the intermediate transfer belt 55 and the transfer roller 56, a conveyance belt 65 and a conveyance roller 66 are provided, so that the conveyance belt 65 and the photosensitive drums 61y and 61m between the conveyance rollers 66 are provided. An image is formed by transferring and fixing the developed color image, multicolor image, or single-color toner image onto the recording paper S while the recording paper S is nipped and conveyed between the recording paper 61c and 61k.

  For this reason, when setting a developing cartridge that contains toner of the same color, similarly, the developing rollers 62y, 62m, 62c, and 62k are operated individually and controlled to be stopped except for those that are operated.

  For this reason, the direct transfer type image forming apparatus is configured in the same manner as in the above-described embodiment, and in addition to realizing long-term image formation without having to replace the developing cartridge every time the toner runs out. When the print command is received in the standby state, or whenever the accumulated operation time or the accumulated number of developed images exceeds a set value (set time or set number of sheets), the developing cartridge to be operated is repeatedly switched to perform development for each developing cartridge. By rotating rollers and the like one after another, high-quality image formation without leaving banding can be performed.

  Furthermore, in the first and second embodiments described above, the cumulative operation time and the cumulative number of developed sheets are determined based on whether or not the development cartridge has reached a set value so as not to continue to be used until the lifetime of the use limit. Needless to say, the count value by the toner counter, the number of dots of the image, or the remaining amount of the toner to be actually measured is detected and operated every time the detected value exceeds the set value. By repeatedly switching the developing cartridge, the developing roller for each developing cartridge may be rotated one after another to realize high quality image formation without leaving banding.

  Whether or not the cumulative operation time or the cumulative number of developed sheets has reached a set value is determined every time a print command is received. This print command is a job for printing one document from the personal computer PC ( It may be received for each job (a job that collects a plurality of image data), or may be received for each job that occurs for each page in the document (a job that occurs for each page). Needless to say.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

1 is a perspective view showing an example of a printer to which an image forming apparatus according to a first embodiment of the present invention is applied, showing a schematic overall configuration thereof. It is a related block diagram explaining the drive control. It is a partial longitudinal cross-sectional front view which shows the image development rotary unit which accommodates the image development cartridge. It is a see-through | perspective front view which shows transmission of the drive force of the image development rotary unit or a image development cartridge. It is a see-through | perspective side view which shows transmission of the driving force of the image development rotary unit or a image development cartridge. 6 is a flowchart for explaining switching control of the developing cartridge. It is a figure which shows an example of the printer to which 2nd Embodiment of the image forming apparatus which concerns on this invention is applied, and is a related block diagram explaining the drive control. 6 is a flowchart for explaining switching control of the developing cartridge. It is a see-through | perspective front view which shows the image forming apparatus which can apply the 1st, 2nd embodiment. It is a see-through | perspective front view which shows the image forming apparatus which can apply the 1st, 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control unit 11 Controller part 12 Engine control part 13 CPU
13a Timer function 13b Counter function 15 Main body memory 20 Paper transport device 30 Image recording device 31, 73 Laser beam scanning device 32, 71y, 71m, 71c, 71k Photosensitive drum 33 Developing rotary unit 34, 65 Intermediate transfer belt 35, 66 Transfer Roller 36, 67 Fixing roller pair 37 Developing cartridge 37a Container 37b, 72y, 72m, 72c, 72k Developing roller 37c Supply roller 37d Partition plate 41 Housing 41a Rotating shaft 41y, 41m, 41c, 41k Storage space 42 Non-volatile memory 43 Development side Connector 44 Control side connector 47 Rotary drive motor 48 Development drive motor 75 Conveying belt 76 Conveying roller P Recording forming position S Recording paper

Claims (4)

A carrier carrying a toner image in which an electrostatic latent image is formed on the surface and developing the electrostatic latent image; a plurality of developing cartridges for developing the toner by attaching the toner to the electrostatic latent image on the surface of the carrier; Cartridge switching means for forming a toner image by causing only one of the plurality of developing cartridges to face the surface of the carrier and operating only the developing cartridge;
An image forming apparatus that mounts a plurality of developing cartridges containing toner of the same color and transfers a toner image formed on the surface of a carrier to the surface of a recording medium to form an image.
The developing cartridge includes a container that stores toner, and a developing roller that rotates while facing the carrier and attaches the toner to the surface of the carrier.
An image forming apparatus characterized in that the cartridge switching means repeatedly switches the developing cartridge to be used before reaching the end of the life of the developing cartridge to form a toner image.   The cartridge switching means is used by repeatedly switching the developing cartridge before reaching the end of its life by switching the developing cartridge facing the carrier before starting the processing of the image forming job or after finishing the processing. The image forming apparatus according to claim 1, wherein:   The cartridge switching means has a time measuring means for measuring an accumulated time for continuous image formation with one developing cartridge, and is opposed to the carrier when the accumulated time reaches a preset accumulated time. 3. The image forming apparatus according to claim 1, wherein the developing cartridge is used by repeatedly switching the developing cartridge before reaching the end of its life by switching the developing cartridge.   The cartridge switching means has counting means for counting the cumulative number of images to be continuously formed with one developing cartridge and transferring the toner image to the recording medium, and the counted number has reached a preset cumulative number. 3. The image forming apparatus according to claim 1, wherein the developing cartridge is repeatedly switched and used before reaching the end of its life by switching the developing cartridge opposed to the carrier. 4.

Images