JP2010002547A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make service life color printing photoreceptors longer and ensure quick start of printing, in an image forming apparatus. <P>SOLUTION: The belt section 21 is stretched in a loop and moved in the direction of the loop. The image forming section 17 forms toner images of different colors on the surfaces of photoreceptors 17b to 17y. The displacing section 25 operates in a pressure-contact by which the photoreceptors 17b to 17y are brought into pressure-contact with the belt section 21 in order to transfer the toner images formed on the photoreceptors 17b to 17y to the belt section 21, and a separation by which the photoreceptors 17m to 17y used for only a color operation are separated from the belt section 21. An operation period obtaining section 13a obtains a color operation cumulative period and the monochrome operation cumulative period of a monochrome operation. According to levels of the color operation cumulative period and the monochrome operation cumulative period, a displacement control section 13c controls the displacing section 25 to be operated in the pressure-contact or the separation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an improvement of a so-called tandem full-color image forming apparatus in which a plurality of image forming units are arranged along a predetermined direction.

  Conventionally, as a full-color image forming apparatus, black, magenta, cyan, and yellow image forming units are arranged along a linear sheet conveying path formed by a conveying belt, and for a sheet conveyed by the conveying belt, A so-called tandem system is provided in which a toner image formed on a photoconductor in each image forming unit is sequentially transferred to form a color image.

  In this type of image forming apparatus, the photosensitive member and the conveying belt of each image forming unit are in close contact, and the sheet is conveyed by the adsorption force of the conveying belt and the pressure contact force between the photosensitive member and the conveying belt.

  However, in this type of image forming apparatus, when a monochrome image is formed, a toner image is formed only by a black image forming unit, and a toner image is not formed by magenta, cyan, and yellow image forming units other than black. Nevertheless, the photoreceptor is in close contact with the conveyor belt.

  Therefore, in order to convey the paper, it is necessary to operate the image forming unit other than black to rotate the photosensitive member, and the conveying belt unnecessarily contacts the magenta, cyan and yellow three-color photosensitive members. There is a risk of shortening the life of the photoconductor.

  Therefore, in order to extend the life of these three-color image forming units, a three-color canceling mechanism has been proposed in which the color photoconductor is separated from the conveying belt during monochrome printing, and printing is performed by driving only the monochrome photoconductor.

  As this kind of thing, there exist Unexamined-Japanese-Patent No. 2-292553 (patent document 1) and Unexamined-Japanese-Patent No. 10-293437 (patent document 2), for example.

  Patent Document 1 discloses that when a monochrome image of a specific color is formed, the transfer belt is displaced from the transfer roller of a multicolor image forming station other than black by displacing the transfer belt around the axis of the transfer roller of the monochrome image forming station. And a three-color release mechanism that switches between pressing and retracting the conveyance belt to and from the image carrier when switching between monochrome / multicolor image formation, thereby extending the life of the conveyance belt and the image carrier.

Further, Patent Document 2 discloses that when a full-color image is formed, a transfer belt for black, magenta, cyan, and yellow is pressed against each photosensitive drum, and the transfer roller is displaced downward when a monochrome image is formed. The configuration is such that the pressure contact state between the conveying belt and the photosensitive drum is released, and the life of the photosensitive drum is prevented from being shortened.
Japanese Patent Laid-Open No. 2-292754 Japanese Patent Laid-Open No. 10-293437

  However, in the above-described full-color image forming apparatus, at the start of printing, the image carrier (photosensitive drum) and the conveying belt are shifted from the pressure contact state to the separation state, or from the separation state to the pressure contact state. Can not do it.

  Therefore, it is necessary to wait for the start of printing until these transitions are completed, and there is room for improvement in order to immediately start the printing operation and improve productivity.

  The present invention has been made to solve such a problem, and provides an image forming apparatus capable of extending the life of a photoconductor for color printing and easily ensuring the start of printing promptly. Objective.

  In order to solve such a problem, an image forming apparatus according to the present invention includes a belt unit that is looped and controlled to move in the loop direction, and a photosensitive member that has a color on the surface of the photosensitive member. A plurality of image forming portions that form toner images of different sizes, and a pressure-contact operation that presses each photoconductor and the belt portion in order to transfer the toner images formed on the surfaces of the plurality of photoconductors onto the belt portion. A displacement operation unit that performs a separation operation that relatively separates the photosensitive member and the belt unit that are used only for the color operation, and a color operation accumulation period of the color operation in the image forming unit at the end of the operation of the image forming unit. The operation period acquisition unit for acquiring the monochrome operation accumulation period of the monochrome operation and the color operation accumulation period are compared with the monochrome operation accumulation period. Displacement control its displacement operation unit so as to the, is provided when the monochrome cumulative operation time is greater and the displacement control unit for displacing controlling the displacement operation unit so as to the separating operation, the.

  In the image forming apparatus of the present invention, the belt portion may be a transfer belt to which a toner image formed on the surface of the photoreceptor is transferred.

  In the image forming apparatus of the present invention, the belt unit may be a conveyance belt that conveys a sheet onto which a toner image formed on the surface of the photosensitive member is transferred.

  In the image forming apparatus of the present invention, the displacement control unit may control the displacement operation unit based on the acquisition operation of the operation period acquisition unit immediately after the operation of the image forming unit is finished.

  In the image forming apparatus of the present invention, the operation period acquisition unit acquires the color operation accumulation period from the operation period of the color operation photoreceptor, and acquires the monochrome operation accumulation period from the operation period of the monochrome operation photoreceptor. Configuration is also possible.

  In the image forming apparatus according to the present invention, the operation period acquisition unit includes, as the monochrome operation accumulation period, the photosensitive element used only for the color operation from the operation accumulation period of the photoconductor used for both the color operation and the monochrome operation. A configuration in which the body motion accumulation period is subtracted is also possible.

  In such an image forming apparatus according to the present invention, when the operation period acquisition unit acquires the color operation accumulation period and the monochrome operation accumulation period every time the operation of the image formation unit ends, the displacement control unit performs the color operation accumulation period. Is compared with the monochrome operation accumulation period, and if the color accumulation operation period is longer, the displacement operation unit is controlled to contact the photoconductor and the belt unit, and the color operation is performed when the monochrome accumulation operation period is long. Since the displacement operation unit is controlled so as to separate the photosensitive member used only for the conveyance belt, the photosensitive member and the belt unit are brought into contact with or separated from each other according to the length of the color operation period and the monochrome operation period. It is possible to prepare for the next printing operation, extending the life of the photoconductor for color printing, and facilitating the prompt start of printing.

  In the image forming apparatus according to the present invention, in the configuration in which the belt portion is a transfer belt to which the toner image formed on the surface of the photosensitive member is transferred, the belt portion is first transferred from the photosensitive member to the transfer belt and then onto the sheet. It can be implemented in a configuration where the next transfer is performed.

  In the image forming apparatus according to the aspect of the invention, in the configuration in which the belt unit is a conveyance belt that conveys a sheet on which the toner image formed on the surface of the photosensitive member is transferred, the toner image is transferred from the photosensitive member to the conveyance sheet. It can be implemented in the configuration.

  In the image forming apparatus according to the present invention, in the configuration in which the displacement control unit controls the displacement operation unit based on the acquisition operation of the operation period acquisition unit immediately after the operation of the image formation unit ends, the image forming apparatus It is possible to surely speed up the printing operation when starting up.

  In the image forming apparatus of the present invention, the operation period acquisition unit acquires the color operation accumulation period from the operation period of the color operation photoreceptor, and acquires the monochrome operation accumulation period from the operation period of the monochrome operation photoreceptor. In the configuration, since these photoconductors generally have an operation period measurement function, it is easy to acquire the color operation accumulation period and the monochrome operation accumulation period, and it is difficult to complicate the configuration.

  In the image forming apparatus of the present invention, the operation period acquisition unit is configured so that the monochrome operation accumulation period includes a photosensitive member used only for the color operation from the operation accumulation period of the photoconductor used for both the color operation and the monochrome operation. In the configuration obtained by subtracting the body operation accumulation period, the monochrome operation accumulation period is obtained from the operation period of the photoconductor used for both the color operation and the monochrome operation and the operation period of the photoconductor used for the color operation. Therefore, independent acquisition of the monochrome operation period is unnecessary, and the configuration can be simplified correspondingly.

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

An image forming apparatus according to an embodiment of the present invention will be schematically described with reference to FIG.
FIG. 1 is a schematic diagram showing the internal configuration of the image forming apparatus A described above.

  In FIG. 1, an image reading unit 3, an operation panel unit 5, a printing unit 7, a storage unit 9, a communication unit 11, and a main control unit 13 that controls these are arranged in a main body case 1 of the image forming apparatus A. A multifunction device is configured.

  The image reading unit 3 is disposed on the upper part of the main body case 1 and optically reads an image from, for example, a printed document under the control of the main control unit 13, and generates electronic print data by performing filter processing or the like. This is a known scanner or the like, and the generated print data is sequentially stored in the storage unit 9 for each page of the document.

  The operation panel unit 5 is disposed on the upper part of the main body case 1 of the image forming apparatus A, functions as a liquid crystal display unit that displays the operation state of the image forming apparatus A, and sets printing paper that is a printing medium to be printed. In addition to a function as an instruction input unit for selecting paper feed stages 15a and 15b to be described later, starting or stopping printing, the number of copies, etc., an input unit for selecting and inputting color printing and monochrome printing, and an input unit for receiving these change inputs It functions and is controlled by the main control unit 13.

  The printing unit 7 is arranged in the main body case 1 and receives a plurality of paper feeding stages 15a and 15b on which printing paper is set, and paper that is primarily fed from the paper feeding stages 15a and 15b. In the conveyance process of the secondary paper feeding, the printing data is transferred and fixed to form a monochrome image or a color image. Reference numeral 19 in FIG. 1 denotes a paper discharge tray in the cylinder to which the paper printed by the printing unit 7 is discharged.

  In addition to the image forming unit 17 described above, the printing unit 7 includes a belt unit 21, a driving roller 23a, a tension roller 23b, driven rollers 23c, 23d, 23e, and 23f, a displacement operating unit 25, and a secondary unit as shown in FIG. A transfer roller 27a, a pressure roller 27b, a cleaner 29, and the like are formed.

  The image forming unit 17 includes four color image forming units 17B, 17M, 17C, and 17Y for black, magenta, cyan, and yellow that are supported in a row at predetermined intervals along the moving direction of the belt unit 21. .

  Each of the image forming units 17B to 17Y as the individual image forming unit 17 includes known photosensitive drums 17b, 17m, 17c, and 17y, and black, magenta, cyan, and yellow formed on these surfaces, respectively. A full color image can be obtained by transferring the toner image on the belt portion 21 by sequentially superimposing colors.

  The configuration shown in FIG. 2 is a so-called tandem-type full-color image forming unit 17, and shows a configuration in which a toner image is transferred to the surface of the belt unit 21. A configuration for directly transferring the toner image to the conveyed paper will be described later.

  Among the image forming units 17B to 17Y, the image forming unit 17B is used for all of monochrome printing and color printing, and the image forming units 17M to 17Y are used only for color printing.

  Each of the photosensitive drums 17b to 17y of the image forming units 17B to 17Y can output data indicating the operation accumulation period from the use start time of the toner image forming operation period. That is, monochrome and color operation accumulation period data can be output to the main control unit 13 from each photosensitive drum 17b, and color operation accumulation period data can be output from each of the photosensitive drums 17m to 17y.

  In general, each of the photosensitive drums 17m to 17y includes a measurement unit (not shown) of the operation accumulation period data in order to measure the accumulation period use period from the use start time point.

  The print data is converted into laser light or the like and formed as a latent image on the photosensitive drums 17b to 17y, and a toner image is formed by, for example, attaching each color toner to the latent image. Therefore, detailed description and illustration thereof will be omitted.

  The belt portion 21 is a known one to which a toner image is primarily transferred from the photosensitive drums 17b to 17y, and is an endless belt that is looped around a driving roller 23a, a tension roller 23b, and a secondary transfer roller 27a. is there.

  The belt unit 21 is controlled to move at a constant speed in the loop direction (from left to right in FIG. 2 and from the photosensitive drum 17b to 17y) by a driving roller 23a that is rotationally driven by a motor or the like (not shown). .

  The tension roller 23b applies tension by pulling the belt portion 21 so that the belt portion 21 does not loosen.

  Under the respective photosensitive drums 17b to 17y, driven rollers 23c to 23g are arranged with the belt portion 21 interposed therebetween, and when the belt portions 21 are elastically contacted, the driven rollers are freely rotated according to the movement of the belt portion 21. It has become.

  In addition, the driven roller 23c is fixedly supported by a predetermined portion of the main body case 1, and is constantly in pressure contact with the belt portion 21 from below so that the belt portion 21 and the photosensitive drum 17b come into contact with each other.

  The driven rollers 23d to 23g are supported by, for example, a plate-like displacement operation unit 25. When the displacement operation unit 25 is displaced upward, the belt unit 21 and the photosensitive drums 17b to 17y come into contact with each other. .

  The displacement operation unit 25 is supported on the main body case 1 so as to be movable back and forth with respect to the belt unit 21 by a solenoid or the like (not shown), and the displacement is controlled by a displacement control unit 13b described later.

  Therefore, when the displacement operation unit 25 moves forward with respect to the belt unit 21, the driven rollers 23d to 23g press the belt unit 21 so that the belt unit 21 and the three color photosensitive drums 17m to 17y come into contact with each other. When the displacement operation unit 25 moves backward with respect to the belt unit 21, the driven rollers 23d to 23g descend to separate the belt unit 21 from the photosensitive drums 17m to 17y.

  FIG. 3 shows a state in which the driven rollers 23d to 23g are lowered to separate the belt portion 21 from the photosensitive drums 17m to 17y.

  The secondary transfer roller 27a is primarily transferred to the belt portion 21 with respect to the paper 31 passing between them (strictly, between the belt portion 21 and the pressure roller 27b) in cooperation with the belt portion 21. The toner image is secondarily transferred. The paper 31 on which the toner image is secondarily transferred is conveyed to a paper discharge tray 19 by a roller (not shown) and discharged.

  A cleaner 29 in FIG. 2 is a known one that cleans the surface of the belt portion 21 after the toner image is secondarily transferred to the paper 31.

  Returning to FIG. 1, the storage unit 9 is a readable / writable hard disk (HDD) that stores print data (to be described later) from the image reading unit 3 and the communication unit 11 and an operation program of the main control unit 13.

  Under the control of the main control unit 13, the communication unit 11 receives print data including an image and a document with a predetermined protocol from, for example, another multifunction device (none shown) via the network. , An interface unit for sequentially storing each page in the storage unit 9.

  The main control unit 13 includes a CPU, a memory unit that stores a startup program for the CPU, and an input / output interface (none of which are shown), and includes the above-described image reading unit 3, operation panel unit 5, printing unit 7, While controlling the memory | storage part 9 and the communication part 11, it bears a part.

  FIG. 4 is a block diagram illustrating the relationship among the image reading unit 3, the operation panel unit 5, the printing unit 7, the storage unit 9, the communication unit 11, and the displacement operation unit 25 described above with the main control unit 13 as the center. become.

  The main control unit 13 stores and controls the print data from the image reading unit 3 and the communication unit 11 in the storage unit 9, controls display and input on the operation panel unit 5, and print data from the storage unit 9 to the print unit 7 and has the following functions.

  That is, the main control unit 13 monitors the photosensitive drums 17b to 17y of the image forming units 17, and performs monochrome operation from the photosensitive drums 17b to 17y every time the operation of the image forming unit 17 ends (immediately after the end of each operation). It has a function as the operation period acquisition part 13a which acquires accumulation period data and color operation accumulation period data.

  The operation period acquisition unit 13a monitors the operation period of each of the photosensitive drums 17b to 17y when the photosensitive drums 17b to 17y do not have the function of outputting the monochrome operation accumulation period data and the color operation accumulation period data. It is possible to provide a function for integrating and calculating the monochrome operation accumulation period data and the color operation accumulation period data.

  Further, the main control unit 13 compares the color operation accumulation period with the monochrome operation accumulation period based on the acquisition result by the print number acquisition unit 13a, and when the color accumulation operation period is larger, the image forming unit 17 The displacement operation unit 25 is controlled so that the photosensitive drums 17b to 17y come into contact with the belt unit 21, and when the monochrome cumulative operation period is longer, the photosensitive drums 17b to 17b of the image forming unit 17 used only for color operation. It has a function as a displacement control unit 13b that controls the displacement operation unit 25 so that the 17y and the belt unit 21 are separated from each other.

  The operation accumulation period obtained from the photosensitive drum 17b described above is data in which the color operation accumulation period and the monochrome operation accumulation period are overlapped, and does not indicate only the monochrome operation accumulation period. Therefore, the displacement control unit 13b may be formed so as to obtain only the monochrome operation accumulation period by subtracting the color operation accumulation period from the monochrome operation accumulation period.

  If the operation accumulation period obtained from the photoconductor drum 17b indicates only the monochrome operation accumulation period, this may be acquired.

  By the way, the image forming apparatus A has various configurations other than this, but since it is not a main part of the present invention, description and illustration are omitted.

  Next, the operation of the image forming apparatus A according to the present invention will be described with reference to the flowchart of FIG.

  In the initial stage in which the image forming apparatus A according to the present invention is installed, the displacement control unit 13b of the main control unit 13 controls the displacement operation unit 25 in response to a color printing or monochrome printing instruction from the operation panel unit 5. Then, the displacement control is performed so that only the photosensitive drums 17 b to 17 y or the photosensitive drum 17 b of the image forming unit 17 are brought into contact with the belt unit 21.

  When the program is started, printing is started in step S1, for example, print data is sequentially sent from the storage unit 9 to the printing unit 7, and toner images formed on the photosensitive drums 17b to 17y of the image forming unit 17 are formed. Primary transfer is performed on the belt portion 21.

  On the other hand, in the process in which the paper 31 of the first page is primarily fed from the paper feed stages 15a and 15b and is secondarily fed, it is secondarily transferred and fixed by the secondary transfer roller 27a and the pressure roller 27b. An image or a color image is formed and discharged from the paper discharge tray 19, and the process proceeds from step S1 to step S2.

  In step S2, the operation period acquisition unit 13b determines whether it is color printing or monochrome printing. If the printing process is color printing and step S2 is YES, the operation period acquisition unit 13b determines in step S3. Then, the accumulated operation period of all the color photoconductive drums 17b to 17y is acquired and the process proceeds to step S5. If the printing process is monochrome printing and step S2 is NO, the operation period acquisition unit 13b performs monochrome processing in step S4. The cumulative operation period of the photosensitive drum 17b is acquired, and the process proceeds to step S5.

  In step S5, it is determined whether or not the printing process is the last page. If it is not the last page and step S5 is NO, the process returns to step S2, and steps S2 to S5 are repeated until step S5 becomes YES.

  When the printing process reaches the last page and step S5 becomes YES, drive stop control is performed in step S6, and the process proceeds to step S7.

  In step S7, the displacement control unit 13b compares the color operation accumulation period with the monochrome operation accumulation period to determine whether or not the color accumulation operation period is longer, and the color accumulation operation period is longer and step S7 is YES. If so, the process proceeds to step S8, and if the color cumulative operation period is shorter and step S7 is NO, the process proceeds to step S9.

  In step S9, the displacement control unit 13b determines whether or not the displacement operation unit 25 is in the release state. If the displacement control unit 25 is in the release state and step S8 is YES, the process proceeds to step S10, and the displacement control unit 13b is displaced in step S10. The operation unit 25 is controlled to perform displacement processing to the pressure contact state, and the process ends. If not in the released state and step S8 is NO, the process ends directly.

  On the other hand, in step S9, the displacement control unit 13b determines whether or not the displacement operation unit 25 is in the pressure contact state. If the displacement operation unit 25 is in the pressure contact state and step S9 is YES, the process proceeds to step S11. Controls the displacement operation unit 25 to perform the displacement processing in the released state, and ends. If not in the press-contact state and step S9 is NO, the process ends directly.

  Thereafter, in accordance with the length of the monochrome operation accumulation period relative to the color operation accumulation period, the displacement control is performed so that all the photosensitive drums 17b to 17y and the belt portion 21 are in contact with each other in advance, or the three-color photoconductors. The next printing operation is awaited in a state where the drums 17m to 17y and the belt portion 21 are separated from each other.

  As described above, the image forming apparatus A according to the present invention includes the belt portion 21 that is looped and controlled to move in the loop direction, and the photosensitive drums 17b to 17y, and the surfaces of the photosensitive drums 17b to 17y. A plurality of image forming units 17 for forming toner images having different colors from each other, and toner images formed on the surfaces of the plurality of photosensitive drums 17b to 17y are transferred to the belt unit 21 for primary transfer. A displacement operation unit 25 for performing a pressure contact operation for pressing the photosensitive drums 17b to 17y and the belt portion 21 and a separation operation for relatively separating the photosensitive drums 17m to 17y used only for the color operation and the belt portion 21; Each time the operation of the image forming unit 17 is finished, an operation for acquiring the color operation accumulation period of the color operation and the monochrome operation accumulation period of the monochrome operation in the image formation unit 17 The inter-time acquisition unit 13a is compared with the color operation accumulation period and the monochrome operation accumulation period, and when the color accumulation operation period is longer, the displacement operation unit 25 is subjected to displacement control so that the press operation is performed, and the monochrome accumulation is performed. A displacement control unit 13c that controls the displacement operation unit 25 to perform the separation operation when the operation period is longer.

  Therefore, when the printing operation or the like is completed and the operation is stopped, the operation accumulation periods of the photosensitive drums 17b to 17y used for the previous color printing and monochrome printing are compared, and the photosensitive drums 17m to 17y are previously compared. In order to prepare for the next printing by shifting to the pressure contact state or the separation state with the belt portion 21, the displacement operation is not generated at the next printing.

  Accordingly, it is possible to ensure the prompt start of printing of the first page, suppress a decrease in productivity, and extend the life of the photosensitive drums 17m to 17y for color printing.

  Immediately after the end of the operation of the image forming unit 17, the displacement operation unit 13b controls the displacement operation unit 25 based on the acquisition operation of the operation period acquisition unit 13a. Quick printing operation is possible.

  In general, since the photosensitive drums 17m to 17y of the image forming unit 17 can output the operation accumulation period data, even if the operation period acquisition unit 13a does not have the accumulation calculation function, the photosensitive drums 17b to 17y. The color operation accumulation period and the monochrome operation accumulation period can be acquired from the 17y operation period, and it is difficult to complicate the configuration.

  Moreover, even when the operation accumulation period data from the photosensitive drums 17m to 17y of the image forming unit 17 is used, the operation period acquisition unit 13a uses the photosensitive operation used for both the color operation and the monochrome operation as the monochrome operation accumulation period. Since the operation period of the photosensitive drums 17b to 17y used for the color operation is subtracted from the operation period of the body drums 17b to 17y, it is not necessary to calculate only the monochrome operation period, and the configuration is simplified accordingly. Is possible.

  In the image forming apparatus A of the present invention described above, the toner images formed on the surfaces of the photosensitive drums 17b to 17y are primarily transferred to the belt portion 21 that is a transfer belt, and the belt portion 21 transfers the toner image 2 to the paper 31. Although the configuration is such that the next transfer is performed, the present invention is not limited to this.

  In other words, the belt unit 21 is also used in a configuration in which the paper 31 is placed and transported to be used as a transport belt, and the toner images formed on the surfaces of the photosensitive drums 17b to 17y are directly transferred to the paper 31. Is possible.

  If such a configuration is illustrated by using FIG. 2 described above, for example, as shown in FIG. 6, the paper 31 may be placed on the belt portion 21 and conveyed from the drive roller 23a side.

  Thus, the present invention can be implemented as long as the toner image is transferred onto the belt portion 21 such as directly transferring the toner images on the photosensitive drums 17b to 17y to the belt portion 21 or transferring to the paper 31. It is.

  Further, the above-described image forming apparatus A of the present invention is not limited to the configuration in which the pressure contact state or the separation state between the photosensitive drums 17m to 17y and the belt portion 21 is enabled by the driven rollers 23c to 23f and the displacement operation portion 25. .

  For example, although not shown, the image forming apparatus 17, that is, the color photoconductive drums 17 m to 17 y themselves may be configured to be movable back and forth with respect to the belt portion 21. The point is that the photosensitive drums 17m to 17y and the belt portion 21 may be relatively separated from each other.

  In the image forming apparatus A of the present invention, the color operation accumulation period and the monochrome operation accumulation period are not limited to the original color printing and monochrome printing, but include a warm-up operation, a color adjustment operation, and the like. If the period for operating 17b to 17y is acquired, the object of the present invention can be achieved.

  Further, the image forming apparatus A according to the present invention can be implemented in a copying machine, a facsimile machine, a multifunction machine such as a multifunction machine (MFP).

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating a main configuration of the image forming apparatus in FIG. 1. FIG. 2 is a diagram illustrating an operation of the image forming apparatus in FIG. 1. 1 is a block diagram illustrating an image forming apparatus according to the present invention. 3 is a flowchart for explaining the operation of the image forming apparatus in FIG. 1. It is a figure explaining the main structures in the other form of the image forming apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body case 3 Image reading part 5 Operation panel part 7 Printing part 9 Storage part 11 Communication part 13 Main control part 13a Operation period acquisition part 13b Displacement control part 15a, 15b Paper feed stage 17 Image formation part 17B, 17M, 17C, 17Y Image forming unit (image forming unit)
17b, 17m, 17c, 17y Photosensitive drum (photosensitive member)
19 discharge tray 21 belt portion 23a drive roller 23b tension rollers 23c, 23d, 23e, 23f, 23g driven roller 25 displacement operation portion 27a secondary transfer roller 27b pressure roller 29 cleaner 31 paper A image forming apparatus

Claims (6)

A belt portion that is looped and controlled to move in the loop direction;
A plurality of image forming units having a photoreceptor and forming toner images of different colors on the surface of the photoreceptor;
A pressure contact operation in which each of the photoconductors and the belt portion are pressed to transfer the toner images formed on the surfaces of the plurality of photoconductors onto the belt portion; and the photoconductor used only for a color operation; A displacement operation unit that performs a separation operation that relatively separates the belt unit;
An operation period acquisition unit that acquires a color operation accumulation period of a color operation and a monochrome operation accumulation period of a monochrome operation each time the operation of the image formation unit is completed;
When the color operation accumulation period is compared with the monochrome operation accumulation period, and when the color accumulation operation period is longer, the displacement operation unit is subjected to displacement control so as to perform the press-contact operation, and when the monochrome accumulation operation period is longer A displacement control unit that controls the displacement operation unit to perform the separation operation;
An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein the belt portion is a transfer belt to which the toner image formed on the surface of the photoconductor is transferred. The image forming apparatus according to claim 1, wherein the belt unit is a conveyance belt that conveys a sheet onto which the toner image formed on the surface of the photoconductor is transferred. The image forming apparatus according to claim 1, wherein the displacement control unit controls the displacement operation unit based on the acquisition operation of the operation period acquisition unit immediately after the operation of the image forming unit is finished. The operation period acquisition unit acquires the color operation accumulation period from the operation period of the photoconductor for color operation, and acquires the monochrome operation accumulation period from the operation period of the photoconductor for monochrome operation. 4. The image forming apparatus according to any one of 4 above. The operation period acquisition unit calculates an operation accumulation period of the photoconductor used only for the color operation from an operation accumulation period of the photoconductor used for both the color operation and the monochrome operation as the monochrome operation accumulation period. The image forming apparatus according to claim 1, which is obtained by subtraction.

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