JP2007233063A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a performance in a single color image formation equivalent to that obtained in a color image formation regardless of the arranged order of process cartridges or the number of the arranged process cartridges loaded on an image forming apparatus. <P>SOLUTION: The image forming apparatus is loaded with a plurality of process cartridges with image carriers carrying images and forms an image of a plurality of colors or an image of a single color by the loaded process cartridges onto transfer material on a transfer material carrier installed in a position facing the image carrier. The image forming apparatus is provided with: a determining part for determining whether arrangement of the plurality of loaded process cartridges differs from the arrangement of the process cartridges when forming the image with a plurality of colors; a driving part for driving a retaining part that can make the image carriers abut on or be separated from the transfer material carrier, and a control part controlling an image forming action of the single color by driving the driving part according to a determination result by the determining part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus.

  A schematic configuration of a conventional color laser printer using an electrophotographic process is shown in FIG. This color laser printer is a quadruple drum type (inline) printer, and includes four process cartridges 106 of cyan 106C, yellow 106Y, magenta 106M, and black 106Bk as image forming units. According to this color laser printer, the image formed on the image carrier (electrophotographic photosensitive member) (101C, Y, M, Bk) in each process cartridge 106 is transferred onto the transfer material transported by the electrostatic transport belt 11. Sequentially transferred and fixed on top.

  The process cartridges (106C, Y, M, Bk) have the same size, mechanism, and the like from the overall balance and cost of the color laser printer. Further, the position where each process cartridge is mounted is determined, and the image forming operation cannot be performed unless all color process cartridges are mounted. For example, even when a single color image is formed, all process cartridges (106C, Y, M, Bk) must be mounted. In the conventional color laser printer configuration, there are many restrictions when a user uses the color laser printer for anything other than full-color printing, and there is a problem that various uses cannot be made when forming a monochrome image.

Patent Document 1 proposes an image forming apparatus capable of giving a degree of freedom to use such as mounting a process cartridge and the number of process cartridges to be mounted being one or more. This has reduced the restrictions on users who use color laser printers.
JP-A-5-35042

  However, even with the image forming apparatus proposed in Patent Document 1, all restrictions on the use of the user are eliminated, and it is not yet sufficient whether various uses can be realized. In particular, depending on the position where one or two process cartridges are mounted, the transfer material cannot be conveyed depending on the size due to the positional relationship with the conveyance mechanism for conveying the transfer material from the upstream side to the downstream side. There is. In view of such problems, the present invention is not limited to the arrangement order and the number of arrangements of the process cartridges to be mounted, and image formation that makes it possible to realize performance equivalent to color image formation by single-color image formation. The purpose is to provide a device.

In order to achieve the above object, an image forming apparatus according to the present invention has a plurality of process cartridges each having an image carrier that carries an image, and a plurality of color images or a single color image can be obtained by the attached process cartridges. An image forming apparatus for forming a transfer material on a transfer material carrier disposed at a position facing the image carrier,
Determining means for determining whether the arrangement of the plurality of process cartridges mounted is different from the arrangement of the process cartridges when forming the plurality of color images;
Driving means for driving a holding means capable of bringing the image carrier and the transfer material carrier into contact with or apart from each other;
Control means for controlling the single color image forming operation by driving the drive means in accordance with the determination result of the determination means;
It is characterized by providing.

  According to the present invention, the present invention is not limited to the arrangement order and the number of arrangement of the process cartridges to be mounted, and the image formation that makes it possible to realize the same performance as the color image formation by the single color image formation. A device can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention.

(First embodiment)
(Description of image forming apparatus)
(Configuration of image forming unit)
First, an overall configuration of a color image forming apparatus (hereinafter simply referred to as an image forming apparatus) will be described with reference to FIG. 1A. FIG. 1A is a diagram illustrating a schematic configuration of a color laser printer as one form of the image forming apparatus, and FIG. 1B is a diagram illustrating a configuration of a control unit of the image forming apparatus. The image forming apparatus includes four electrophotographic photosensitive members (hereinafter referred to as “photosensitive drums”) 101 (101C, 101Y, 101M, and 101Bk). Each of the photosensitive drums 101 (101C, 101Y, 101M, 101Bk) as an image carrier is configured by applying an organic photoconductive layer (OPC) to the outer peripheral surface of an aluminum cylinder. Both ends of the photosensitive drum 101 are rotatably supported by flanges, and are driven to rotate counterclockwise when a driving force is transmitted to one end from the photosensitive member driving motor 13 in FIG. 1A. . The photoconductor drive motor 13 is controlled by the photoconductor drive circuit 12 under the overall control of the CPU 11.

  Around each photosensitive drum (101C, 101Y, 101M, 101Bk), a charging unit 104, an exposure unit 108, a developing unit 103, a transfer unit 102, and the like are configured. The charging unit 104 (104C, 104Y, 104M, 104Bk) uniformly charges the surface of the photosensitive drum in order according to the rotation direction of the photosensitive drum. Each charging unit 104 is a conductive roller formed in a roller shape. The surface of the photosensitive drum 101 is brought into contact with the surface of the photosensitive drum 101 by applying the charging bias voltage to the surface of the photosensitive drum 101 and a power source (not shown). Is uniformly charged.

  The exposure unit 108 (108C, 108Y, 108M, 108Bk) irradiates a laser beam based on the image information to form an electrostatic latent image on the photosensitive drum 101. The CPU 11 generates a control signal for driving the rear road drive circuit 14 in accordance with the image information received via the interface 10, and the exposure unit drive circuit 14 irradiates the exposure unit 108 with a laser beam in accordance with the control signal. The exposure unit 108 irradiates a laser beam based on image information under the control of the exposure unit drive circuit 14 to form an electrostatic latent image on the photosensitive drum 101.

  The developing units 103 (103C, 103Y, 103M, and 103Bk) attach toner to the electrostatic latent image to visualize it as a toner image. The developing units 103 (103C, 103Y, 103M, and 103Bk) have toner storage units that store toners of cyan (C), yellow (Y), magenta (M), and black (Bk), respectively. The toner storage unit is adjacent to the surface of the photosensitive drum 101 (101C, 101Y, 101M, 101Bk), and is driven to rotate when a driving force is transmitted from the developing unit driving motor 16. The developing unit driving motor 16 is controlled by the developing unit driving circuit 15 under the overall control of the CPU 11. The development unit 103 performs development by applying a development bias voltage from a development bias power source (not shown).

  The transfer unit 102 (102C, 102Y, 102M, 102Bk) transfers the toner image on the photosensitive drum 101 to a transfer material. Inside the transfer conveyance belt 11, transfer rollers 102 (102C, 102Y, 102M, 102Bk) that abut on the transfer conveyance belt 11 are arranged in parallel corresponding to the four photosensitive drums 101C, 101Y, 101M, 101Bk. ing. These transfer rollers 102 are connected to a transfer bias power source (not shown), and positive charges are applied from the transfer roller 102 to the transfer material S via the transfer conveyance belt 11. By this electric field, the negative toners (C, Y, M, Bk) on the photosensitive drum 101 are sequentially transferred to the transfer material S in contact with the photosensitive drum 101 to form a color image.

  The transfer material S set in the paper feed cassette 150 is picked up one by one by the pickup roller 151, and is conveyed to the image forming unit constituted by the process cartridge 106 through the feed roller pair 140. In the image forming unit, each color toner image is sequentially transferred onto the transfer material S to form a color image. When the toner image transferred to the transfer material S passes through a fixing unit 152 having a heating roller that is driven to rotate and a pressure roller that is driven to rotate, heat and pressure are applied to the transfer material S, and the toner image is transferred to the transfer material S. S is fixed on S. Then, the transfer material S on which the toner image is fixed is discharged to a discharge portion by a discharge roller pair 153.

  The photosensitive drum 101, the charging unit 104, and the developing unit 103 are integrated into a cartridge to form a process cartridge 106 (106C, 106Y, 106M, 106Bk). The process cartridge 106 is detachably supported with respect to the image forming apparatus main body, and is configured so that it can be easily replaced according to the life of the photosensitive drum 101. The outer shape and internal components of each process cartridge 106 (106C, 106Y, 106M, 106Bk) are the same in terms of balance and cost in the printer.

(Configuration of transfer material transport unit)
The transfer material is fed from a feeding unit having a paper feed cassette 150 and then conveyed by the transfer conveyance belt 11 to an image forming region constituted by the image forming unit. A plurality of transfer materials are stored in the paper feed cassette 150, and a semimoon-shaped pickup roller 151 for picking up the transfer materials one by one is rotatably provided in the vicinity of the paper feed cassette 150. Then, the transfer material picked up by the intermittent rotation of the pickup roller 151 is fed to the transfer conveyance belt 11 by the feed roller pair 140. In FIG. 1A, there is one paper feed cassette 150, but the paper feed unit can include a plurality of paper feed cassettes depending on the type and size of the transfer material.

  The transfer conveyance belt 11 as a transfer material carrier constituting the transfer material conveyance unit is stretched and supported by three rollers of a drive roller 12 and driven rollers 13a and 13b. The transfer conveyance belt 11 is disposed to face all the photosensitive drums 101C, 101Y, 101M, and 101Bk. The transfer / conveying belt 11 is composed of an endless film member using a thin film having a high volume resistance (resistance per unit volume).

  The transfer conveyance belt 11 is circulated and moved by a driving roller 12 so that the transfer material S is electrostatically attracted to the outer peripheral surface facing the photosensitive drum 101 and the transfer material S is brought into contact with the photosensitive drum 101. The drive roller 12 is driven to rotate by the transfer material conveyance motor 18 in FIG. 1B, and the transfer material conveyance motor 18 is controlled by the transfer material conveyance unit drive circuit 17 under the overall control of the CPU 11.

  The transfer material S is transported to a transfer position where the transfer material S contacts the photosensitive drums 101C, 101Y, 101M, and 101Bk by the circulation movement of the transfer conveyor belt 11, and the toner images on the photosensitive drums 101C, 101Y, 101M, and 101Bk are transferred. .

  Further, an adsorption roller 154 that holds the transfer material S together with the transfer conveyance belt 11 and adsorbs the transfer material S to the transfer conveyance belt 11 is disposed at the most upstream position of the transfer conveyance belt 11. When the transfer material S is conveyed, an electric field is formed between the transfer roller S and the transfer material S by applying a bias voltage to the suction roller 154 so as to form an electric field between the opposed driven roller 13a. Dielectric polarization is generated to generate electrostatic adsorption force on both.

(Description of image forming operation)
Next, an image forming operation (recording mode) by the image forming apparatus having the above-described configuration will be described. As an image forming operation, it is possible to execute a full color recording mode for performing full color recording and a monochrome recording mode for performing monochrome recording of only one color. In the execution of the monochrome recording mode, it is not necessary for each process cartridge to be mounted for all colors, and it is sufficient that at least a process cartridge corresponding to a color for executing monochrome recording is mounted.

  Here, the monochrome recording mode is divided into a first monochrome recording mode and a second monochrome recording mode depending on the mounting state of the process cartridge. The first monochrome recording mode is a recording using any one of the process cartridges 106 at a normal position (for example, a position arranged in the order shown in FIG. 1A) arranged when performing full-color recording. Refers to the mode.

  The second monochrome recording mode is a recording mode performed by changing the arrangement of the process cartridge 106 in the first monochrome recording mode.

  In this embodiment, black (Bk) image formation will be described as an example of the monochrome recording mode. However, execution of the monochrome recording mode is not limited to black (Bk), and cyan (C), yellow (Y), and magenta. (M) can be executed in the same manner.

  FIG. 1C is a flowchart for explaining a flow of processing relating to selection of a recording mode. The process of this flowchart is executed under the control of the CPU 11.

  First, in step S101, it is determined whether the image output is full color. For example, it is determined whether a print job received via the interface 10 (FIG. 1B) has been generated as a full-color print job by the host computer 7 or has been designated as full-color from the operation unit 9 by user operation settings.

  If it is determined in step S101 that the image is full color (S101-Yes), the process proceeds to step S102, and image formation is performed in the color recording mode (S102).

  On the other hand, if it is determined in step S101 that the color is not full (S101-No), the process proceeds to step S103.

  In step S103, it is determined whether or not the process cartridge 106 is mounted at a normal position that is disposed when performing full-color recording. When the process cartridge 106 is mounted at the normal position (S103-No), the process proceeds to step S108, and image formation is executed in the first monochrome recording mode.

  On the other hand, if it is determined in step S103 that the process cartridge 106 is disposed at a position different from the normal position where the full color recording is performed (S103-Yes), the second monochrome recording mode is selected. (S104).

  In step S105, all the photosensitive drums of the mounted process cartridge are in contact with the transfer conveyance belt 11, and under the control of the CPU 11, the photosensitive member driving circuit 12 selects any one photosensitive drum 101. To control the rotation.

  In step S <b> 106, under the control of the CPU 11, the exposure drive circuit 14 selects any one exposure unit 108 and executes image formation.

  In step S107, it is determined whether the image formation of the print job is completed. If not completed (S107-No), the process returns to step S106 to select any one exposure unit 108 and continue the image formation. If the image formation for the print job is completed (S107—Yes), the process is terminated.

  Hereinafter, the contents of the color recording mode, the first monochrome recording mode, and the second monochrome recording mode will be specifically described.

(Color recording mode)
The execution of the color recording mode corresponds to the processing in step S102 in FIG. 1C. When the color recording mode is executed, as shown in FIG. 1A, four photosensitive drums 101C, 101Y, 101M, and 101Bk are mounted, and full-color image formation is performed with the transfer conveyance belt 11 and the photosensitive drums in contact with each other. Is done.

  The transfer material S is separated and fed one by one from the paper feed cassette 150, and abuts against the feed roller pair 140 to temporarily stop the transfer material conveyance. Then, the photosensitive drum 101 is rotated counterclockwise in the drawing in synchronization with the rotation of the transfer conveyance belt 11, and the transfer material S waiting on the feeding roller pair 140 is directed to the most upstream photosensitive drum 101C. To resume (re-feed).

  The surface of each photosensitive drum 101 (101C, 101Y, 101M, 101Bk) is uniformly charged by the charging unit 104 (104C, 104Y, 104M, 104Bk). Then, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 101 by the exposure unit 108 (108C, 108Y, 108M, 108Bk).

  The developing unit 103 applies a voltage having the same polarity as the charging polarity of the photosensitive drum 101 so that the toner adheres to the electrostatic latent image on the photosensitive drum 101, and attaches the toner to the electrostatic latent image. And develop. By this process, toner images of respective colors are formed on the peripheral surfaces of the photosensitive drums 101C, 101Y, 101M, and 101Bk.

  At the timing when the leading edge of the toner image formed on the peripheral surface of the photosensitive drum 101C comes to a point (opposing point) that contacts the transfer conveyance belt 11, the opposing point coincides with the recording start position of the transfer material S. The transfer material S is fed again to the transfer conveyance belt 11. The transfer material S electrostatically attracted by the formation of an electric field with the driven roller 13a grounded by applying a bias voltage to the attracting roller 154 is successively transferred along the transfer conveyance belt 11 to the photosensitive drum 101. It is conveyed to.

  The timing of feeding the transfer material S so that the recording start position coincides with the opposing point is controlled by the photosensitive drum 101C positioned on the most upstream side of the conveyance, and other photosensitive drums (101Y, 101M, 101Bk). But the same is true.

  By applying voltages from the transfer rollers 102C, 102Y, 102M, and 102Bk, the toner images on the photosensitive drums 101 are sequentially transferred onto the transfer material S in the order of cyan, yellow, magenta, and black. The transfer material S onto which the four color toner images have been transferred is separated from the transfer conveyance belt 11 by the drive roller 12 and sent to the fixing unit 152, where the toner image is thermally fixed, and then discharged to the discharge unit 153.

(First monochrome recording mode)
Next, the first monochrome recording mode will be described. The execution of the first monochrome recording mode corresponds to the process of step S108 in FIG. 1C.

  An example in which one process cartridge 106Bk is used in a state where the process cartridge 106 is arranged at a normal position (for example, a position arranged in the order shown in FIG. 1A) arranged when performing full-color recording will be described.

  FIG. 2 is a diagram illustrating a configuration example of the image forming apparatus for explaining the execution of the first monochrome recording mode according to the present embodiment. The same components as those in the image forming apparatus in FIG. 1A are denoted by the same reference numerals. When only the process cartridge 106Bk is used to form a single color image, the image forming apparatus operates the holding members 21C, Y, M, and Bk (FIG. 1B) under the control of the drive circuit 19. Then, the other process cartridges 106C, Y, and M that are not used for single color image formation are separated from the image formation process.

  Here, the holding members 21C, Y, M, and Bk can hold the transfer rollers 102C, 102Y, 102M, and 102Bk, respectively. The holding member drive motors 20C, Y, M (FIG. 1B) drive a swing mechanism (not shown) (for example, a cam or a lever) to swing the holding members 21C, Y, M, and transfer rollers 102C, Y, M The photosensitive drums 101C, Y, and M can be separated from each other. As a result, the transfer conveyance belt 11 and the photosensitive drums 101C, Y, and M are separated. At this time, the transfer conveyance belt 11 and the photosensitive drum 101Bk are in contact with each other.

  The photoconductor drive motors 13C, Y, M for driving the photoconductor drums 101C, Y, M are controlled so as not to operate under the control of the photoconductor drive circuit 12. The photoconductor drive circuit 12 drives only the photoconductor drive motor 13Bk to control the rotation of the photoconductor drum 101Bk. In this state, for the operations from feeding to discharging, the transfer material S is transported as in the color recording mode, and only the photosensitive drum 101Bk contacts the transfer material S to form a monochrome image. The transfer material S on which the monochrome image is formed is sent to the fixing unit 152, where the toner image is thermally fixed, and then discharged to the discharge unit 153.

(Second monochrome recording mode)
Next, execution of the second monochrome recording mode will be described. The execution of the second monochrome recording mode corresponds to the processing in steps S103 to S107 in FIG. 1C.

  FIG. 3 is a diagram illustrating a configuration example of the image forming apparatus for explaining the execution of the second monochrome recording mode according to the present embodiment. In the image forming apparatus shown in FIG. 3A, process cartridges (106Bk1 to 106Bk4) for black (Bk) are mounted at all four process cartridges.

  The detection sensor (8C to 8Bk in FIG. 1B) indicates whether the mounted process cartridge is for cyan (C), yellow (Y), magenta (M), black (Bk), or process cartridge It is possible to detect the presence or absence. The detection sensors (8C to 8Bk in FIG. 1B) read and detect identification information such as, for example, the outer shape of the process cartridge (for example, the number of protrusions and the number of slits) or a barcode attached to the cartridge. Based on the detection results of the detection sensors (8C to 8Bk), the CPU 11 can determine whether the mounted process cartridge has been changed from the arrangement of the process cartridge in the full-color recording mode. For example, if the black process cartridges 106Bk1, 106Bk2, and 106Bk3 are installed at the positions where the process cartridges for cyan (C), yellow (Y), and magenta (M) are originally installed, the arrangement is changed. It is determined that The change in the arrangement is not limited to the case where all the process cartridges are used for transferring the same color. For example, it is sufficient that at least two process cartridges used for transferring the same color are mounted.

  When the arrangement is changed, the image forming apparatus can select the second recording monochrome recording mode as the recording mode to be selected, and execute image formation in the second monochrome recording mode. For example, when the process cartridges shown in FIG. 3 are arranged in an order different from the arrangement order of the process cartridges shown in FIG. 1A, the second monochrome recording mode is selected.

  Note that the second monochrome recording mode is selected by the user via the operation unit 9 (FIG. 1B) regardless of the detection results of the detection sensors (8C to 8Bk). It is also possible.

  When the black (Bk) process cartridge (106Bk1 to 106Bk4) of the same color is mounted, all the photosensitive drums (101Bk1 to 101Bk4) are in contact with the transfer conveyance belt 11 as in the color recording mode. become. Under the control of the CPU 11, the photoconductor drive circuit 12 selects any one photoconductor drum 106 and controls the rotation. Then, under the control of the CPU 11, the exposure driving circuit 14 selects one arbitrary exposure unit 108 and executes image formation.

  In this case, one selected exposure unit and one photosensitive drum form a set. For example, when the most upstream exposure unit for transporting the transfer material S and the photosensitive drum are selected, the exposure unit 108C and the process cartridge 106Bk1 (the photosensitive member 101Bk1 is rotationally driven) in FIG. 3 are combined. In image formation for each sheet, the CPU 11 performs image formation by combining one process cartridge and one exposure unit, and controls the other process cartridges and the exposure unit that are not selected not to operate simultaneously. In this case, the unselected process cartridge serves as a transport roller when transporting the transfer material S, but does not contribute to image formation.

  Based on the selected exposure unit and process cartridge, the CPU 11 controls to synchronize the start timing of the image forming operation and the transfer start timing of the transfer material S according to the position where the process cartridge is mounted.

  The CPU 11 selects which process cartridge (106Bk1 to 106Bk4) and the exposure unit (108C, 108Y, 108M, 108Bk) to use when executing image formation. In this case, the CPU 11 can select to allocate the usage frequency of each process cartridge evenly according to the page unit for image formation, the print job unit, the toner consumption amount, and the like.

  For example, when the selection is switched for each transfer material, the CPU 11 selects the process cartridge 106Bk1 and the exposure unit 108C when forming the image of the first transfer material, and the process cartridge 106Bk2 and the exposure unit when forming the second image. 108Y is selected. The process cartridge and the exposure unit to be selected are cyclically shifted, the CPU 11 selects the process cartridge 106Bk3 and the exposure unit 108M when the third image is formed, and the process cartridge 106Bk4 and the exposure unit 108Bk when the fourth image is formed. Select. Then, when forming the fifth image, the CPU 11 selects the process cartridge 106Bk1 and the exposure unit 108C in the same manner as the first image. It is possible to equalize the frequency of use by cyclically switching the selection of process cartridges.

  It is also possible to equalize the frequency of use by selecting process cartridges and exposure units based on page units, print job units, image contents to be formed (toner consumption to be used), and the like.

  The image forming process by the selected one process cartridge and the exposure unit is the same as that in the first monochrome recording mode, and complicated control is not required. When forming an image in the second monochrome recording mode, using the mechanical configuration of the image forming apparatus, it is equivalent to mounting a process cartridge having a toner capacity four times that when executing the color recording mode. An effect can be obtained.

  The amount of toner contained in the process cartridge is measured by a sensor (not shown), and the CPU 11 can obtain the remaining amount of toner (toner consumption) based on information from the sensor. Even when the toner in any of the process cartridges runs out, the CPU 11 can switch to using another process cartridge of the same color and continue image formation. That is, the image forming apparatus can be controlled so that the entire apparatus can be used until all the toners of the same color are used up. By this apparatus control, it is possible to reduce the downtime of the image forming apparatus, the replacement frequency of process cartridges, the work required for the replacement, and the order cost by batch ordering of new process cartridges.

  In the description of the present embodiment, the case where all four process cartridges for black (Bk) are used as process cartridges of the same color has been described, but the same effect can be obtained even in the case of other colors. Is possible.

  Further, the process cartridge is not limited to the case where four same color cartridges are used. For example, the same effect can be realized if at least two process cartridges having the same color are used. For example, in printing that uses two process cartridges for black (Bk), one for yellow (Y), and one for magenta (M), and adds a red one-point color to monochrome printing The same effect can be obtained.

  According to the present embodiment, it is possible to realize performance equivalent to color image formation by single color image formation.

(Second Embodiment)
Next, an image forming apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a diagram illustrating a schematic configuration of an image forming apparatus according to the second embodiment. In the image forming apparatus, one process cartridge 106Bk is mounted. In order to be able to transport a transfer material whose size in the transport direction is LS (image formation is possible), the mounting position (L1, L2) of the process cartridge and the size in the transport direction of the transfer material (LS) It is necessary to satisfy the relationship of the following expressions (1) and (2).

L1 <Ls (1)
L2 <Ls (2)
Ls: Size in the transfer material conveyance direction L1: Distance from the suction roller 154 to the transfer roller 102M L2: Distance from the nip portion of the fixing unit 152 to the transfer roller 102M

  When a smaller number of process cartridges are mounted than when fully mounted (in this case, four), the transfer material S is held at both ends by the transfer roller 102M and the photosensitive drum 101Bk, the suction roller 154, and the driven roller 13a during transfer. become. Further, at the time of fixing, the transfer material S is held at both ends by the nip portion of the fixing unit 152, the transfer roller 102M, and the photosensitive drum 101Bk. If the above relations (1) and (2) are satisfied, an image can be formed on a transfer material having a size LS in the transport direction. The CPU 11 detects the position where the process cartridge is mounted by the detection sensor 8M, and determines the positional relationship between L1 and L2 and the size relationship between the conveyance direction size LS based on the detected position. From this determination result, it is possible to determine the size (Ls) in the conveyance direction of the transfer material capable of image formation. In addition, the CPU 11 displays the type information (for example, A4, A3, B4, etc.) of the transfer material that can be used on the operation unit 9 (FIG. 1B) based on the obtained size (Ls) in the transport direction to the user. Control is also possible.

  For a user who mainly performs single color printing (for example, monochrome printing) in the image forming apparatus, even when the C, Y, and M process cartridges are removed, the same performance as in color printing can be achieved with monochrome printing.

  FIG. 5 is a diagram illustrating a state where two process cartridges are mounted in the image forming apparatus. By mounting two process cartridges, the size (Ls) in the transport direction of the transfer material S capable of image formation can be further reduced.

  When two process cartridges 106 are mounted, a transfer material having a size (Ls) in the transport direction can be transported (image formation is possible), and the following relationships (3), (4), and (5) are satisfied. It is necessary to satisfy.

L3 <Ls (3)
L4 <Ls (4)
L5 <Ls (5)
Ls: Size in transfer material transfer direction L3: Distance from suction roller 154 to transfer roller 102Y L4: Distance from transfer roller 102Y to transfer roller 102Bk L5: Distance from transfer roller 102Bk to nip of fixing unit 152 distance

  The image forming apparatus according to the present embodiment can drive the holding member 21 under the control of the CPU 11 and the holding member drive circuit 19 to separate the photosensitive drum of any process cartridge from the transfer conveyance belt 11. is there. In the case of the image forming apparatus shown in FIG. 5, the photosensitive drum of any of the mounted process cartridges 106 Bk 1 and 106 Bk 2 can be separated from the transfer conveyance belt 11 by driving the holding member 21.

  By separating one of the photosensitive drums from the transfer / conveying belt 11, the image forming apparatus performs an operation equivalent to a state in which only one process cartridge is mounted. When the transfer material S having a long size (Ls) in the transport direction is used, control is performed so that the photosensitive drum 101 of one process cartridge contacts the transfer transport belt 11. When a transfer material having a short size (Ls) in the transport direction is used, the switching of the operation is controlled so that the photosensitive drums 101 of the two process cartridges 106 are in contact with the transfer transport belt 11.

  The holding member drive circuit 19 brings the photosensitive drum 101Bk1 into contact with the transfer conveyance belt 11 so as to satisfy the relationships of the expressions (3) to (5) for the transfer material having a short size Ls in the conveyance direction. Then, the driving of the holding member 21 is controlled so that the toner image is transferred by the photosensitive drum 101Bk1. When the size Ls in the conveyance direction of the transfer material is long and satisfies the expressions (3) to (5), the holding member drive circuit 19 separates the photosensitive drum 101Bk1 from the transfer conveyance belt 11. Then, control is performed so that only the photosensitive drum 101Bk2 is brought into contact with the transfer conveyance belt 11 to transfer the toner image.

  According to this embodiment, the contact and separation between the photosensitive drum and the transfer conveyance belt are controlled by the size of the transfer material in the conveyance direction to prevent the photosensitive drum from being consumed due to the constant contact with the transfer conveyance belt. It becomes possible. For example, the length of the process cartridge is controlled by controlling the photosensitive drums of the two process cartridges to contact the transfer conveyance belt only when a transfer material having a small size (Ls) in the conveyance direction is used. It becomes possible to extend the life.

  In addition, even when a single color image is formed by mounting a smaller number of process cartridges than when fully mounted in the image forming apparatus, it is possible to achieve the same performance as that of color image formation by single color image formation. It becomes possible.

(Third embodiment)
Next, an image forming apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram illustrating a schematic configuration of an image forming apparatus according to the third embodiment. This image forming apparatus has the same shape as the process cartridge, but is characterized in that a transport cartridge 110 having only a transport mechanism without an image forming function is mounted. Furthermore, one process cartridge capable of an image forming operation is mounted in the image forming apparatus. Here, as an example of forming a single color image, an example in which a process cartridge 106Bk for black (Bk) is mounted is shown, but the gist of the present invention is not limited to this example. May be mounted instead of the process cartridge 106Bk.

  The transport cartridge 110 uses the housing of the process cartridge 106, and a transport roller 111 mechanism is provided inside the process cartridge 106 as an alternative to the image carrier (photosensitive drum 101) in the process cartridge 106. . The conveyance roller 111 that contacts the transfer conveyance belt 11 is preferably made of a material having the same outer shape as the photosensitive drum 101 and having a conveyance property equivalent to that of the photosensitive drum 101.

  A photosensitive member driving motor (13 in FIG. 1B) for driving the photosensitive drum 101 is connected to the conveying roller 111. Under the control of the photosensitive member driving circuit 12, the conveying roller 111 connected to the driving motor is driven to rotate. Is controlled.

  In the configuration of FIG. 6, the transport cartridge 110 and the process cartridge 106Bk are mounted at the same position as the process cartridges 106Bk1 and 106Bk2 shown in FIG. As described in the second embodiment, the size (Ls) in the conveyance direction of the transfer material needs to satisfy the relationships of the expressions (3) to (5). In the configuration of the second embodiment, the photosensitive drum 101 </ b> Bk <b> 1 is brought into contact with the transfer conveyance belt 11 so that the relationship of the expressions (3) to (5) is satisfied for a transfer material having a short size Ls in the conveyance direction. Thus, the drive of the holding member 21 is controlled. If the size Ls of the transfer material in the conveyance direction is long and satisfies the expressions (3) to (5), the photosensitive drum 101Bk1 is separated from the transfer conveyance belt 11, and only the photosensitive drum 101Bk2 is applied to the transfer conveyance belt 11. The toner image is transferred in contact therewith.

  According to the present embodiment, the conveyance roller 111 of the conveyance cartridge 110 is always in contact with the transfer conveyance belt 11. Even if the contact of the photosensitive drum 101Bk1 is not controlled by driving the holding member 21 in accordance with the size Ls of the transfer material to be used in the conveyance direction, the conveyance conditions (relationships of equations (3) to (5)) are satisfied. It is filled.

  In addition, even when a single color image is formed by mounting a smaller number of process cartridges than when fully mounted in the image forming apparatus, it is possible to achieve the same performance as that of color image formation by single color image formation. It becomes possible.

(Fourth embodiment)
Next, an image forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS. 7A and 7B. In the image forming apparatus according to the first to third embodiments, the case where the transfer material carrier is used as the member facing the photosensitive drum has been described. In this embodiment, an example in which the first monochrome recording mode and the second monochrome recording mode described in the first embodiment are applied to an image forming apparatus in which the member facing the photosensitive drum is an intermediate transfer member. explain.

(First monochrome recording mode)
FIG. 7A is a diagram illustrating a schematic configuration of an image forming apparatus according to the fourth embodiment, and FIG. 7B is a diagram illustrating a configuration of a control unit of the image forming apparatus. The same reference numerals are assigned to the same components as those in FIGS. 1A and 1B.

  In FIG. 7A, an intermediate transfer member (intermediate transfer belt) 35 is a belt formed of a seamless resin, and is stretched around three axes of a drive roller 31, a secondary transfer counter roller 32, and a tension roller 33. The tension roller 33 is adjusted in tension by a spring (not shown), and can absorb the amount of change even if the circumference of the intermediate transfer belt 35 changes due to temperature and humidity in the image forming apparatus main body or changes with time. Yes. The intermediate transfer belt 35 is supported in the image forming apparatus with the driving roller 31 as a fulcrum. The intermediate transfer belt 35 is controlled by the intermediate transfer belt drive circuit 170 (FIG. 7B), and the driving force of the drive motor 180 (FIG. 7B) whose rotation is controlled is transmitted to the drive roller 31 so that the intermediate transfer belt 35 rotates in the direction indicated by the arrow (clockwise). ).

  The intermediate transfer member 35 is synchronized with the outer peripheral speed of the image carrier (photosensitive drum) 101 in order to multiplex-transfer the toner image on the image carrier (photosensitive drum) 101 visualized by each developing unit 103 during the color image forming operation. And rotate clockwise in the figure. This rotation control is executed by the intermediate transfer belt driving circuit 170 under the overall control of the CPU 11.

  The toner image formed on the photosensitive drum 101 is multiple-transferred onto the intermediate transfer member 35 at a primary transfer portion which is a contact point between the photosensitive drum 101 and the primary transfer roller 102 ′ to which a predetermined voltage is applied. Then, the transfer material S is sandwiched and conveyed by the secondary transfer roller 51 to which a predetermined voltage is applied in the secondary transfer portion T2, whereby the toner image that has been multiplex-transferred to the intermediate transfer body 35 is simultaneously transferred to the transfer material S in a multiple transfer manner. Is done. When the toner image transferred to the transfer material S passes through the fixing unit 152, heat and pressure are applied to the transfer material S to fix the toner image on the transfer material S. Then, the transfer material S on which the toner image is fixed is discharged to a discharge portion by a discharge roller pair 153.

  Four process cartridges 106 can be attached to the image forming apparatus. When the process cartridge 106 is mounted, the detection sensor 8 (FIG. 7B) detects whether the mounted process cartridge is for cyan (C), yellow (Y), magenta (M), or black (Bk). To detect. When the process cartridges shown in FIG. 1A are mounted in this order, the image forming apparatus can form an image in the first monochrome recording mode in addition to the image formation in the full color recording mode.

  The holding members 210C, Y, M, and Bk (FIG. 7B) can hold the primary transfer rollers 102C ′, 102Y ′, 102M ′, and 102Bk ′. A swing mechanism (not shown) is driven by the holding member drive motors 200C, Y, M (FIG. 7B) to swing the holding members 210C, Y, M, so that they are intermediate between the primary transfer rollers 102C ′, 102Y ′, 102M ′. The transfer belt 35 can be separated. In this state, only the photosensitive drum 101Bk comes into contact with the intermediate transfer belt 35, and a monochrome toner image is transferred. By controlling the contact and separation between the primary transfer rollers 102C ′, 102Y ′, and 102M ′ and the intermediate transfer belt 35, image formation corresponding to the first monochrome recording mode described in the first embodiment can be performed. (S108 in FIG. 1C).

(Second monochrome recording mode)
In the image forming apparatus shown in FIG. 7A, process cartridges (106Bk1 to 106Bk4) for black (Bk) are mounted at all the positions where the four process cartridges are arranged. The detection sensor (8C to 8Bk in FIG. 7B) indicates whether the mounted process cartridge is for cyan (C), yellow (Y), magenta (M), black (Bk), or process cartridge It is possible to detect the presence or absence.

  Based on the detection results of the detection sensors (8C to 8Bk), the CPU 11 determines whether the mounted process cartridge has been changed from the arrangement of the process cartridge in the full-color recording mode (see FIG. 1A). When the arrangement of the process cartridge is changed, the image forming apparatus can select the second recording monochrome recording mode as the recording mode and perform image formation in the second monochrome recording mode.

  The selection of the second monochrome recording mode may be performed by the user selecting the execution of the second monochrome recording mode via the operation unit 9 (FIG. 7B) without depending on the detection results of the detection sensors (8C to 8Bk). Is possible.

  When the same color black (Bk) process cartridge (106Bk1 to 106Bk4) is mounted, all the photosensitive drums (101Bk1 to 101Bk4) are in contact with the intermediate transfer belt 35 as in the color recording mode. become. Under the control of the CPU 11, the photoconductor drive circuit 12 selects any one photoconductor drum 106 and controls the rotation. Then, under the control of the CPU 11, the exposure driving circuit 14 selects one arbitrary exposure unit 108 and executes image formation.

  In this case, one selected exposure unit and one photosensitive drum form a set. For example, in image formation for each sheet, the CPU 11 performs image formation by combining one process cartridge and one exposure unit, and performs control so that other unselected process cartridges and exposure units do not operate simultaneously. .

  Based on the selected exposure unit and process cartridge, the CPU 11 controls to synchronize the start timing of the image forming operation and the rotation start timing of the intermediate transfer belt 35 according to the position where the process cartridge is mounted.

  The CPU 11 selects which process cartridge (106Bk1 to 106Bk4) and the exposure unit (108C, 108Y, 108M, 108Bk) to use when executing image formation. In this case, the CPU 11 can select to allocate the usage frequency of each process cartridge evenly according to the page unit for image formation, the print job unit, the toner consumption amount, and the like.

  For example, when the selection is switched for each transfer material, the CPU 11 selects the process cartridge 106Bk1 and the exposure unit 108C when forming the image of the first transfer material, and the process cartridge 106Bk2 and the exposure unit when forming the second image. 108Y is selected. The process cartridge and the exposure unit to be selected are cyclically shifted, the CPU 11 selects the process cartridge 106Bk3 and the exposure unit 108M when the third image is formed, and the process cartridge 106Bk4 and the exposure unit 108Bk when the fourth image is formed. Select. Then, when forming the fifth image, the CPU 11 selects the process cartridge 106Bk1 and the exposure unit 108C in the same manner as the first image. It is possible to equalize the frequency of use by cyclically switching the selection of process cartridges.

  It is also possible to select the process cartridge and the exposure unit on the basis of the print job unit, the content of the image to be formed (toner consumption amount to be used), and the like to equalize the use frequency.

  When forming an image in the second monochrome recording mode, using the mechanical configuration of the image forming apparatus, it is equivalent to mounting a process cartridge having a toner capacity four times that when executing the color recording mode. An effect can be obtained.

  The amount of toner contained in the process cartridge is measured by a sensor (not shown), and the CPU 11 can obtain the remaining amount of toner (toner consumption) based on information from the sensor. Even when the toner in any of the process cartridges runs out, the CPU 11 can control the image forming apparatus so that the entire apparatus can be used until all the toner of the same color is used up. By this apparatus control, it is possible to reduce the downtime of the image forming apparatus, the replacement frequency of process cartridges, the work required for the replacement, and the order cost by batch ordering of new process cartridges.

  In the description of the present embodiment, the case where all four process cartridges for black (Bk) are used as process cartridges of the same color has been described, but the same effect can be obtained even in the case of other colors. Is possible.

  Further, the process cartridge is not limited to the case where four same color cartridges are used. For example, the same effect can be realized if at least two process cartridges having the same color are used. For example, in printing that uses two process cartridges for black (Bk), one for yellow (Y), and one for magenta (M), and adds a red one-point color to monochrome printing The same effect can be obtained.

(Other embodiments)
Needless to say, the object of the present invention can also be achieved by supplying a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus. Needless to say, this can also be achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium.

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

  As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a nonvolatile memory card, a ROM, or the like can be used.

  Further, the functions of the above-described embodiment are realized by executing the program code read by the computer. In addition, an OS (operating system) running on a computer performs part or all of actual processing based on an instruction of a program code, and the above-described embodiment is realized by the processing. Needless to say.

1 is a diagram for explaining an outline of an overall configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a control unit of the image forming apparatus. It is a flowchart explaining the flow of the process regarding selection of a recording mode. FIG. 3 is a diagram illustrating a configuration example of an image forming apparatus for explaining execution of a first monochrome recording mode according to the first embodiment of the present invention. It is a figure which shows the structural example of the image forming apparatus explaining execution of the 2nd monochrome recording mode which concerns on 1st Embodiment of this invention. It is a figure which shows schematic structure of the image forming apparatus which concerns on 2nd Embodiment of this invention. FIG. 7 is a diagram illustrating a state where two process cartridges are mounted in an image forming apparatus according to a second embodiment of the present invention. It is a figure which shows schematic structure of the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows schematic structure of the image forming apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the structure of the control part of the image forming apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows schematic structure of the color laser printer using the electrophotographic process in a prior art example.

Claims (13)

A transfer material having a plurality of process cartridges each having an image carrier for carrying an image, and a plurality of color images or a single color image being arranged at positions facing the image carrier by the attached process cartridges. An image forming apparatus for forming a transfer material on a carrier,
Determining means for determining whether the arrangement of the plurality of process cartridges mounted is different from the arrangement of the process cartridges when forming the plurality of color images;
Driving means for driving a holding means capable of bringing the image carrier and the transfer material carrier into contact with or apart from each other;
Control means for controlling the single color image forming operation by driving the drive means in accordance with the determination result of the determination means;
An image forming apparatus comprising: When at least two process cartridges are mounted as process cartridges used for single color transfer according to the determination by the determination unit,
2. The image forming apparatus according to claim 1, wherein the control unit drives the driving unit to bring the image carrier of the at least two process cartridges into contact with the transfer material carrier.   3. The image forming apparatus according to claim 2, wherein the control unit selects any one of the at least two process cartridges to execute the single color image formation. 4.   The image forming apparatus according to claim 3, wherein the control unit selects one of the process cartridges based on at least one of a page unit, a print job unit, and a toner consumption amount. . A toner remaining amount detecting means for detecting the remaining amount of toner stored in each process cartridge;
When the toner in any of the process cartridges that form a single color image has run out as a result of detection by the toner remaining amount detecting means,
5. The image formation according to claim 1, wherein the control unit selects another process cartridge of the same color that is mounted and continues the image formation of the single color. 6. apparatus. When the process cartridges are arranged in the same order as the arrangement of the process cartridges when forming the multi-color image according to the determination by the determination unit,
The control means drives the drive means to bring the image carrier of the process cartridge that forms the toner image of the selected color into contact with the transfer material carrier, and the image carrier of the process cartridge of the non-selected color The image forming apparatus according to claim 1, wherein the transfer material carrier is separated from the image forming apparatus. The determination means further determines whether or not the number of process cartridges that are mounted is smaller than the number of process cartridges when forming the plurality of color images,
2. The image forming apparatus according to claim 1, wherein when the number of arrangements is small, the control unit determines a size of a transfer material on which image formation can be performed by the mounted process cartridge. An intermediate transfer in which a plurality of process cartridges having an image carrier that carries an image is mounted, and a plurality of color images or a single color image is arranged at a position facing the image carrier by the mounted process cartridge An image forming apparatus for forming a transfer material on a transfer material carrier via a body,
Determining means for determining whether the arrangement of the mounted process cartridge is different from the arrangement of the process cartridge at the time of forming the color image;
A driving means for driving a holding means capable of contacting or separating the image carrier and the intermediate transfer body;
Control means for controlling the single color image forming operation by driving the drive means in accordance with the determination result of the determination means;
An image forming apparatus comprising: When at least two process cartridges are mounted as process cartridges used for single color transfer according to the determination by the determination unit,
The image forming apparatus according to claim 8, wherein the control unit drives the driving unit to bring the image carrier of the at least two process cartridges into contact with the intermediate transfer member.   The image forming apparatus according to claim 9, wherein the control unit selects any one of the at least two process cartridges to execute the single color image formation.   The image forming apparatus according to claim 10, wherein the control unit selects any one of the process cartridges based on at least one of a page unit, a print job unit, and a toner consumption amount. . A toner remaining amount detecting means for detecting the remaining amount of toner stored in each process cartridge;
When the toner in any of the process cartridges that form a single color image has run out as a result of detection by the toner remaining amount detecting means,
12. The image formation according to claim 8, wherein the control unit selects another process cartridge of the same color that is mounted, and continues the image formation of the single color. apparatus. When the process cartridges are arranged in the same order as the arrangement of the process cartridges at the time of forming the color image according to the determination by the determination unit,
The control means drives the drive means to bring the image carrier of a process cartridge that forms a toner image of a selected color into contact with the intermediate transfer body, and the image carrier of the process cartridge of an unselected color The image forming apparatus according to claim 8, wherein the intermediate transfer member is separated.

Images