JP5032881B2 - Image forming apparatus, image forming apparatus control method, program, and recording medium - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile, and a control method for the image forming apparatus.

  In recent years, full-color copying machines as well as monochrome copying machines are often used as image forming apparatuses. As such a full-color copying machine, a developing unit storing cyan, magenta, yellow and black toners and a one-drum type color copying machine provided with a single photosensitive drum are known. Yes. On the other hand, in recent years, a tandem color copying machine in which a photosensitive drum is provided for each color toner has been often used (see, for example, Patent Document 1).

  FIG. 6 is a partial configuration diagram of a tandem full-color copying machine. In FIG. 6, a black image forming unit 301, a yellow image forming unit 302, a cyan image forming unit 303, and a magenta image forming unit 304 are provided. Each image forming unit includes photosensitive drums 301a, 302a, 303a, and 304a, and developing rollers 301b, 302b, 303b, and 304b that supply positively charged toner of each color to the photosensitive drums 301a, 302a, 303a, and 304a. is doing. Further, primary transfer rollers 311, 312, 313, and 314 that are charged to a negative charge at the time of primary transfer are arranged opposite to the respective photosensitive drums.

  An intermediate transfer belt 315 is provided between the photosensitive drum and the primary transfer roller, and an elastic layer such as rubber is formed on the surface of the intermediate transfer belt 315. A secondary transfer roller 316 is provided near the downstream side of the black image forming unit 301 so as to press the intermediate transfer belt 315 with reference to the rotation direction of the intermediate transfer belt 315 (see the arrow in the figure). A driving roller 317 is provided inside the intermediate transfer belt 315 so as to face the secondary transfer roller 316, and the driving roller 317 rotates the intermediate transfer belt 315.

  Near the upstream side of the magenta image forming unit 304 is a negatively charged fur brush roller 318 in order to remove the positively charged toner that has not been transferred to the paper during the secondary transfer and remains on the intermediate transfer belt 315. A driven roller 319 is provided inside the intermediate transfer belt 315 so as to face the fur brush roller 318. Further, a tension roller 320 for applying tension to the intermediate transfer belt 315 is provided inside the intermediate transfer belt 315, upstream of the driven roller 319 and downstream of the driving roller 317.

  In such an image forming apparatus, at the time of image formation, a toner image is formed on the photosensitive drums 301a, 302a, 303a, and 304a by the toner carried on the developing rollers 301b, 302b, 303b, and 304b.

  Then, the toner images formed on the respective photosensitive drums are primarily transferred and superimposed on the intermediate transfer belt 315, and the superimposed images are transferred onto the paper by the secondary transfer roller 316.

  As described above, as the intermediate transfer belt 315, an elastic belt having an elastic layer provided on the surface of a resin belt is used. This elastic belt is generally used as an elastic body. Since the nip width can be made longer than that of a resin belt having no layer, the transfer performance can be improved.

  Further, as described above, the fur brush roller 318 is used to remove the residual toner on the surface of the elastic intermediate transfer belt 315. In general, when a resin belt is used, as the belt cleaning, a blade cleaning method is used in which a residual blade is removed by pressing a rubber blade against the belt. However, when this blade cleaning method is adopted for an elastic belt, the friction between the blade and the belt is large, so that tackiness is large and problems such as color misregistration and jitter of each color occur.

Therefore, when an elastic belt is used, as described above, a bias brush cleaning method in which electrostatic cleaning is mainly performed using the fur brush roller 318 is used.
JP 2005-49413 A

  However, in the bias brush cleaning method, cleaning is mainly performed by electrostatic force. Therefore, the removal of external additives having no charging performance detached from the toner, paper dust and the like physically attached to the brush is necessary. It will be done only by the scraping power. Therefore, deposits are likely to remain as compared with the blade cleaning method.

  Further, since the elastic belt has a large stretch and contraction, it tends to embrace deposits such as external additives, making it more difficult to remove.

  In addition, when the additive adheres to the elastic belt and the belt surface is whitened and the background color gradually changes, the color correction (calibration) is performed properly on the intermediate transfer belt. May not be done. In addition, the adhesion value may change the resistance value of the intermediate transfer belt and the optimum value of the transfer bias, which may cause a transfer failure.

  An object of the present invention is to provide an image forming apparatus capable of improving the cleaning performance and a control method thereof in consideration of the problems of the conventional image forming apparatus.

In order to achieve the above object of the present invention, the first present invention provides:
A transfer belt to which a toner image is transferred;
A sensor for detecting the surface reflectance of the transfer belt;
A transfer member for transferring the toner image on the transfer belt onto a recording medium;
A removal unit provided to remove toner on the transfer belt, and applied with a voltage so as to have a polarity opposite to that of the toner;
The transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member, and the surface of the transfer member is transferred to the transfer member. After maintaining a state in which a voltage is applied to the transfer member so as to have a polarity opposite to the toner on the belt, the toner moved from the transfer belt onto the transfer member and the surface of the transfer member have the same polarity. And a controller that performs control to apply a voltage to the transfer member;
With
The control unit performs the control when the surface reflectance becomes a predetermined value or less,
The toner that has moved from the transfer member to the transfer belt by the control is removed from the transfer belt by the removing unit.

The second aspect of the present invention is
The controller is
At least a portion of the predetermined time;
In the image forming apparatus according to the first aspect of the present invention, control is performed so as to maintain a state in which there is a difference in moving speed between the surface of the transfer member and the surface of the transfer belt.

The third aspect of the present invention
In the image forming apparatus according to the first aspect of the present invention, the predetermined time is at least a time required for the intermediate transfer belt to make one round.

The fourth aspect of the present invention is
The removing unit is
A fur brush roller in contact with the transfer belt;
The transfer belt is the image forming apparatus according to the first aspect of the present invention, the surface of which is formed of a material whose main component is rubber.

The fifth aspect of the present invention is
A voltage is applied to the transfer member so that the surface of the transfer member for transferring the toner image on the transfer belt onto which the toner image is transferred onto the recording medium has a polarity opposite to that of the toner discharged to the transfer belt. Reverse polarity application step,
A state after the reverse polarity application step in a state where the transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member. Holding step to hold,
After the holding step, the as from the transfer belt and toner moved onto the transfer member and the surface of the transfer member is the same polarity, the same polarity application step of indicia pressurizing a voltage to the transfer member,
A removal step of removing the toner moved from the transfer member to the transfer belt by the same polarity application step from the transfer belt by a removal unit ;
The reverse polarity applying step, the holding step, the same polarity applying step, and the removing step are performed when the surface reflectance of the transfer belt becomes a predetermined value or less. This is a control method.

The sixth aspect of the present invention
Along with the reverse polarity application step,
A speed changing step for performing a control for making a difference between the moving speeds of the surface of the transfer member and the surface of the transfer belt;
The holding step is a control method for an image forming apparatus according to a fifth aspect of the invention, wherein the difference in the moving speed is held for at least a part of the predetermined time.

The seventh aspect of the present invention
In the control method of the image forming apparatus of the fifth aspect of the present invention,
A voltage is applied to the transfer member so that the surface of the transfer member for transferring the toner image on the transfer belt onto which the toner image is transferred onto the recording medium has a polarity opposite to that of the toner discharged to the transfer belt. Reverse polarity application step,
A state after the reverse polarity application step in a state where the transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member. Holding step to hold,
After the holding step, the same polarity application step of applying a voltage to the transfer member is executed on the computer so that the toner moved from the transfer belt onto the transfer member and the surface of the transfer member have the same polarity. It is a program to make it.

Further, the eighth aspect of the present invention is
A recording medium on which a program of the seventh aspect of the present invention is recorded, which can be processed by a computer.

  According to the present invention, it is possible to provide an image forming apparatus capable of improving the cleaning performance and a control method thereof.

  Hereinafter, a copying machine as an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a front sectional view of a copying machine according to an embodiment of the present invention. As shown in FIG. 1, the copying machine 1 according to the first embodiment includes a plurality of paper feed cassettes 2 for storing paper on which images are formed on the bottom. In addition, the copying machine 1 includes a document reading unit 3 that reads an image of a document by using an exposure lamp, a lens, a mirror, and the like.

  The copying machine 1 according to the present embodiment is a color copying machine using a tandem method, and includes a black image forming unit 4, a yellow image forming unit 5, a cyan image forming unit 6, and a magenta arranged in order in the horizontal direction. An image forming unit 7 is provided. An intermediate transfer belt 8 for superimposing images formed by these image forming units is disposed. Further, a secondary transfer unit 9 that transfers the toner image superimposed on the intermediate transfer belt 8 to a sheet and a fixing unit 10 that fixes the transferred toner image to the sheet are provided.

  A registration roller 25 is provided upstream of the secondary transfer unit 9 in the paper conveyance direction, and a conveyance belt 26 for conveying the paper is provided between the secondary transfer unit 9 and the fixing unit 10. It has been. Further, a discharge roller pair 12 for discharging the paper that has passed through the fixing unit 10 to the outside of the copying machine 1 is provided on the side surface, and a discharge tray 13 on which the paper discharged by the discharge roller pair 12 is placed is provided. Is provided. In FIG. 1, the sheet conveyance direction is indicated by an arrow E.

  Next, the image forming unit will be described. Since the basic configurations of the four image forming units 4, 5, 6, and 7 are the same, the black image forming unit 4 will be described as an example. FIG. 2 is an enlarged configuration diagram in the vicinity of the intermediate transfer belt 8. As shown in FIGS. 1 and 2, the black image forming unit 4 includes a photosensitive drum 40 made of amorphous silicon, a charger 41, a developing unit 42, a cleaning unit 43, a static eliminator 44, and the like. A laser scanner unit (hereinafter referred to as LSU) 46 that forms an electrostatic latent image by optically scanning the surface of the photosensitive drum 40 charged by the charger 41 of the black image forming unit 4 is a photosensitive drum. 40 is provided above. Similarly, the other image forming units 5, 6, 7 also have photosensitive drums 50, 60, 70, chargers 51, 61, 71, developing units 52, 62, 72, cleaning units 53, 63, 73, static eliminators. 54, 64, 74 and LSUs 56, 66, 76 and the like.

  Further, primary transfer rollers 14, 15, 16, and 17 are disposed so as to face the photosensitive drums 40, 50, 60, and 70 with the intermediate transfer belt 8 interposed therebetween. The developing units 42, 52, 62, and 72 are provided with developing rollers 45 and 55 that are disposed in contact with the photosensitive drums to supply toner to the surfaces of the photosensitive drums 40, 50, 60, and 70, respectively. , 65, 75 are provided. In FIG. 2, only the blade is shown in the cleaning unit, and only the developing roller is shown in the developing unit, as compared with FIG.

Further, the intermediate transfer belt 8 is provided with a layer of an elastic member such as rubber on a resin belt in order to achieve both running performance and high image quality. As shown in FIG. 2, the secondary transfer unit 9 includes a secondary transfer roller 92 and a voltage application unit 91 that applies a voltage to the secondary transfer roller 92. The secondary transfer roller 92 is disposed in the vicinity of the downstream side of the black image forming unit 4 with respect to the rotation direction of the intermediate transfer belt 8 (see arrow A). For example, the secondary transfer roller 92 is made of ethylene-propylene-diene rubber (EPDM). A foam rubber roller having a resistance value of about 10 ⁵ to 10 ⁸ Ω by applying a conductive agent is used.

  A driving roller 21 is provided inside the intermediate transfer belt 8 so as to face the secondary transfer roller 92. The drive roller 21 is grounded, and the intermediate transfer belt 8 is rotated by the rotation of the drive roller 21. A driven roller 22 is provided inside the intermediate transfer belt 8 in the vicinity of the upstream side of the magenta image forming unit 7. A cleaning device 11 for removing residual toner on the surface of the intermediate transfer belt 8 is disposed on the upstream side of the driven roller 22 and on the downstream side of the secondary transfer roller 92. A counter roller 23 is provided inside the intermediate transfer belt 8 so as to face the cleaning device 11. A driven roller 24 is provided inside the intermediate transfer belt 8 in the vicinity of the downstream side of the black image forming unit 4. Although not shown in FIG. 2, a tension roller for applying tension to the intermediate transfer belt 8 is also disposed.

  A sensor 80 for measuring the reflectance of the surface of the intermediate transfer belt 8 is provided in the vicinity of the intermediate transfer belt 8 downstream of the driven roller 24 and upstream of the drive roller 21. The sensor 80 includes a light emitting portion and a light receiving portion, and the light emitted from the light emitting portion is reflected by the surface of the intermediate transfer belt 8 and the reflectance is measured by detecting the reflected light at the light receiving portion. It is.

  Next, the configuration of the cleaning device 11 of the present embodiment will be described.

  FIG. 3 is an enlarged configuration diagram of the cleaning device 11.

  As shown in FIG. 3, the cleaning device 11 includes a fur brush roller 111 disposed opposite to the opposing roller 23 with the intermediate transfer belt 8 interposed therebetween, and a collection roller disposed in contact with the fur brush roller 111. 112 and a rubber blade 113 for removing the toner on the collection roller 112. A conveyance spiral 115 for conveying the collected toner to a toner disposal box (not shown) is disposed below the rubber blade 113.

  One of the bearings of the collection roller 112 is conductive, and a voltage application unit 114 that supplies a voltage to the collection roller 112 through the bearing is provided. On the other hand, the bearing of the fur brush roller 111 is non-conductive, and the voltage applied to the recovery roller 112 can act as a cleaning voltage without loss. Since the toner supplied to the photosensitive drums 40, 50, 60, and 70 is positively charged, a voltage is applied to the recovery roller 112 so that the surface of the fur brush roller 111 is negatively charged. Note that the opposing roller 23 disposed to face the collection roller 112 is grounded.

  Further, the rotation direction B of the fur brush roller 111 is a direction facing the rotation direction A of the intermediate transfer belt 8 at a portion in contact with the intermediate transfer belt 8. The rotation direction C of the collection roller 112 is the same as the rotation direction B at the portion in contact with the fur brush roller 111.

  The transfer belt of the present invention corresponds to, for example, the intermediate transfer belt 8 of the present embodiment, and the transfer member of the present invention corresponds to, for example, the secondary transfer roller 92 of the present embodiment. The removal unit of the present invention corresponds to, for example, the cleaning device 11 of the present embodiment, and the control unit of the present invention corresponds to the control unit 30 of the present embodiment.

  Next, the operation of the copying machine according to the first embodiment will be described.

  First, the operation during image formation will be described.

  A photoconductor uniformly charged by a charger in the magenta image forming unit 7, the cyan image forming unit 6, the yellow image forming unit 5 and the black image forming unit 4 based on the image data read by the document reading unit 3. A latent image is formed on the surfaces of the drums 40, 50, 60, and 70 by the LSUs 46, 56, 66, and 76, and a toner image visualized by the developing units 42, 52, 62, and 72 is formed (see FIG. 1). At this time, the toners on the photosensitive drums 40, 50, 60, and 70 are positively charged, and magenta, cyan, yellow, and black are transferred by the primary transfer rollers 14, 15, 16, and 17 to which a negative voltage is applied. The toner images are superimposed on the intermediate transfer belt 8 in order. The toner remaining on the photosensitive drum by the primary transfer is removed by the cleaning units 43, 53, 63, and 73, and the surface of the photosensitive drum is charged by the static eliminators 44, 54, 64, and 74.

  At the same time, a sheet is fed from the sheet feeding cassette 2, temporarily stopped by the registration roller 25, and the secondary transfer unit 9 according to the movement timing of the area (image forming area) where the toner image is formed on the intermediate transfer belt 8. To be sent to.

  Then, the superimposed toner image on the intermediate transfer belt 8 is transferred onto the paper P by the secondary transfer roller 92 (see FIG. 2). Here, since the toner image is positively charged, a voltage is applied to the secondary transfer roller 92 by the voltage applying unit 91 so that the surface thereof is negatively charged. Constant current control is performed during the secondary transfer. In order to prevent the fog toner and floating toner from adhering, after the paper P passes, the applied voltage of the secondary transfer roller 92 is switched so that the surface is again charged positively.

  Then, the sheet on which the toner image is fixed by the fixing unit 10 is discharged onto the discharge tray 13 through the discharge roller pair 12 (see FIG. 1). Incidentally, the toner remaining on the intermediate transfer belt 8 during the transfer onto the paper is removed by the negatively charged fur brush roller 111 via the recovery roller 112 (see FIG. 3). Here, a voltage is applied to the collection roller 112, and the counter roller 23 disposed via the fur brush roller 111 and the intermediate transfer belt 8 is grounded. Therefore, a voltage difference is generated between the fur brush roller 111 and the collecting roller 112, and between the fur brush roller 111 and the intermediate transfer belt 8, and the residual toner is electrostatically transferred to the intermediate transfer belt 8, the fur brush roller 111, and the collecting roller. It is sent to the rollers 112 in order.

  The toner that has moved to the collection roller 112 is removed from the collection roller 112 by the blade 113, and is conveyed to the toner disposal box by the conveyance spiral 115 and discarded.

  When printing of the read image data is completed, the operations of the photosensitive drum, the intermediate transfer belt 8, the secondary transfer roller 92, and the like are stopped, and the image forming operation is completed.

  On the other hand, the reflectance of the surface of the intermediate transfer belt 8 is measured by the sensor 80 during the image formation. In this embodiment, since an elastic body is used on the surface of the intermediate transfer belt 8 and a fur brush cleaning method is used for cleaning the belt, toner additives, paper dust, and the like adhere to the intermediate transfer belt 8. There is. When the deposit is present on the surface of the intermediate transfer belt 8, the reflectance detected by the sensor 80 is low due to scattering by the deposit.

  Therefore, when the control unit 30 determines that the reflectance in the non-image forming area (the area where the toner image is not formed) on the surface of the intermediate transfer belt 8 is equal to or less than a predetermined value, after the image forming operation is finished, An operation of cleaning the intermediate transfer belt 8 is executed.

  Next, the cleaning operation of the intermediate transfer belt 8 will be described, and an example of the control method of the image forming apparatus of the present invention will also be described.

  FIG. 4 is a control flow diagram of the cleaning operation. 5A to 5E are enlarged schematic views of the secondary transfer portion for explaining the cleaning operation.

  When performing the cleaning operation, the control unit 30 first rotates the intermediate transfer belt 8 and the secondary transfer roller 92 (S1 in FIG. 4).

  Then, the control unit 30 operates the yellow image forming unit 5 so as to discharge a predetermined amount of yellow toner onto the intermediate transfer belt 8 (S2 in FIG. 4). FIG. 5A shows the toner 100 ejected on the intermediate transfer belt 8, and S denotes the area where the toner 100 is ejected.

  Next, the controller 30 controls the surface of the secondary transfer roller 92 to be negatively charged by operating the voltage application unit 91 before the region S reaches the secondary transfer roller 92 (FIG. 4). S3). This S3 corresponds to an example of the reverse polarity applying step of the present invention.

  In this state, when the region S on the intermediate transfer belt 8 from which the yellow toner 100 is discharged passes through the secondary transfer roller 92, the positively charged toner is transferred from the intermediate transfer belt 8 to the secondary transfer roller 92. Will move to the surface. FIG. 5B shows a state where the toner is moving.

  FIG. 5C shows a state in which toner adheres to the entire surface of the secondary transfer roller 92. The predetermined amount of toner discharged onto the intermediate transfer belt 8 described above corresponds to the amount of toner that can cover the entire surface of the secondary transfer roller 92 as shown in FIG.

  Next, the rotational speed of the secondary transfer roller 92 is reduced to cause a difference between the moving speed of the surface of the secondary transfer roller 92 and the moving speed of the surface of the intermediate transfer belt 8 (S4 in FIG. 4). This S4 corresponds to an example of the speed changing step of the present invention.

  The controller 30 holds this state for a predetermined time. As this holding time, the time from when the area S where the toner is discharged reaches the secondary transfer roller 92 until the intermediate transfer belt 8 rotates once is secured (S5 in FIG. 4). This state is shown in FIG. This S5 corresponds to an example of the holding step of the present invention. Since the cleaning operation of the present embodiment is performed during non-image formation, the sheet does not pass between the secondary transfer roller 92 and the intermediate transfer belt 8, and the secondary transfer roller 92 and the intermediate transfer belt. 8 is in rotational contact with no paper.

  As described above, the secondary transfer roller 92 in a state where the toner is attached and the intermediate transfer belt 8 are brought into rotational contact, thereby adsorbing the adhering matter (toner additive, paper, etc.) on the intermediate transfer belt 8 and the toner. Can be used to move the deposit from the intermediate transfer belt 8 to the toner on the secondary transfer roller 92.

  Then, after the predetermined time has elapsed, the control unit 30 performs control so that the rotation speed of the secondary transfer roller 92 is returned to the original state (S6 in FIG. 4). Subsequently, the control unit 30 performs control so that the surface of the secondary transfer roller 92 is positively charged by the voltage application unit 91 (S7 in FIG. 4). This S7 corresponds to an example of the same polarity application step of the present invention.

  When the surface of the secondary transfer roller 92 is positively charged in this way, the positively charged toner moves to the intermediate transfer belt 8 together with the adhering matter adsorbed on the toner. This state is shown in FIG.

  The toner moved onto the intermediate transfer belt 8 is conveyed to the cleaning device 11 and is removed from the intermediate transfer belt 8 by the electrostatic force of the fur brush roller 111 and the physical disturbance by the brush together with the adhering deposits. (S8 in FIG. 4). This S8 corresponds to an example of the removal step of the present invention.

  Finally, the control unit 30 stops the rotation of the intermediate transfer belt 8 and the secondary transfer roller 92, and the cleaning operation ends.

  As described above, the image forming apparatus according to the first embodiment uses the adsorptivity of toner and deposits (toner additive, paper powder, etc.) to increase the deposit removal efficiency from the intermediate transfer belt 8. Can be improved. Further, since the deposit removal efficiency is improved, whitening of the surface of the intermediate transfer belt can be suppressed.

  Further, as in the present embodiment, by causing a difference between the moving speed of the surface of the secondary transfer roller 92 and the moving speed of the surface of the intermediate transfer belt 8, the number of contact between the toner and the belt deposit increases. It is considered that the adhering substance can be adsorbed to the toner more efficiently.

  In this embodiment, the sensor 80 measures the reflectance at the time of image formation. However, the sensor 80 may measure the reflectance by rotating the intermediate transfer belt 8 during the time of non-image formation.

  Further, in the present embodiment, the cleaning operation is performed when the reflectance measured by the sensor 80 is smaller than a predetermined value. However, when the sensor 80 is not used and the printing is performed a predetermined number of times, or for a predetermined time. When the time elapses, the cleaning operation may be performed.

  Also, when the printing rate of the document is low, the amount of toner supplied from the developing roller to the photosensitive drum decreases, so that toner particles remain on the developing roller and are excessively charged and move to the photosensitive drum. There is a case where it does not stop and deteriorates. In such a case, an alternating bias larger than that at the time of image formation is applied when image formation is not being performed, and the remaining toner is forcibly moved onto the photosensitive drum and discharged onto the intermediate transfer belt. There is a case where an operation of replacing toner on the developing roller is performed. The cleaning operation of the present embodiment may be performed using toner discharged onto the intermediate transfer belt during such toner replacement operation.

  In the present embodiment, an example of the predetermined time of the present invention is the time from when the region S where the toner is discharged reaches the secondary transfer roller 92 until the intermediate transfer belt 8 rotates once. Although it corresponds, it may be the time until a plurality of rotations. As another example, the predetermined time is defined as the time until it is determined that the reflectance of the intermediate transfer belt 8 detected by the sensor 80 is equal to or greater than the predetermined value at all positions of the intermediate transfer belt 8. Also good.

  Further, it is not necessary to clean the entire circumference of the intermediate transfer belt 8, and the cleaning operation of the present embodiment may be performed only in an area where the sensor 80 determines that there is an adhering substance. In this case, as an example of the predetermined time of the present invention, after the area S where the toner has been ejected reaches the secondary transfer roller 92, the area determined to be attached passes through the secondary transfer roller 92. It corresponds to the time until.

  In this embodiment, the rotational speed of the secondary transfer roller 92 is slowed. However, the rotational speed of the intermediate transfer belt 8 may be slowed without changing the rotational speed of the secondary transfer roller 92. Further, the speeds of the secondary transfer roller 92 and the intermediate transfer belt 8 need not be changed.

  In this embodiment, the secondary transfer roller 92 is controlled so that the surface of the secondary transfer roller 92 is negatively interrupted (S3), and then the speed of the secondary transfer roller 92 is reduced (S4). A state in which a difference in speed from the intermediate transfer belt 8 is generated from the time when the next transfer roller 92 is rotated may be employed.

  Further, after the predetermined time has elapsed, the rotational speed of the secondary transfer roller 92 is restored to the original in S6, but the rotational speed may be restored before the predetermined time has elapsed. In short, it may be decelerated only for a part of the predetermined time, or it may be decelerated for the entire time.

  In the present embodiment, the cleaning operation of the intermediate transfer belt 8 is performed using yellow toner, but any toner of yellow, cyan, magenta, and black may be used. Furthermore, the toner remaining amount may be detected, and the cleaning operation of the present embodiment may be performed using toner with a large remaining amount.

  In the above embodiment, the intermediate transfer belt 8 has a resin belt provided with an elastic member layer. However, a resin belt having no elastic member layer provided on the surface is used. It may be.

  In the above embodiment, the tandem type copying machine has been described. However, the present invention may be applied to cleaning an intermediate transfer belt of a one-drum type color copying machine.

  An example of the recording medium of the present invention corresponds to the sheet of the present embodiment, but may be an OHP sheet or the like.

  An example of the image forming apparatus of the present invention corresponds to the copying machine of the present embodiment, but may be a facsimile, a printer, or the like.

  The program of the present invention is a program for causing a computer to execute the operations of the reverse polarity application step, the holding step, and the same polarity application step of the above-described image forming apparatus control method of the present invention. A program that operates in cooperation with a computer.

  The recording medium of the present invention is a recording medium that records a program for causing a computer to execute all or part of the operations of all or part of the control method of the image forming apparatus of the present invention described above. A recording medium that is readable by a computer and in which the read program executes the operation in cooperation with the computer.

  The “part of steps” of the present invention means one or several steps among the plurality of steps.

  The “step operation” of the present invention means the operation of all or part of the step.

  Further, one use form of the program of the present invention may be an aspect in which the program is recorded on a recording medium such as a ROM readable by a computer and operates in cooperation with the computer.

  Also, one use form of the program of the present invention is an aspect in which the program is transmitted through a transmission medium such as the Internet, a transmission medium such as light, radio wave, and sound wave, read by a computer, and operates in cooperation with the computer. Also good.

  The computer of the present invention described above is not limited to pure hardware such as a CPU, but may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the present invention may be realized by software or hardware.

  The image forming apparatus and the control method for the image forming apparatus of the present invention have an effect of improving the cleaning performance, and are useful as a copying machine, a printer, a facsimile, and the like.

1 is a front configuration diagram of a copying machine according to a first embodiment of the present invention. 1 is a configuration diagram near an intermediate transfer belt of a copying machine according to a first embodiment of the present invention. 1 is a configuration diagram of a cleaning device according to a first embodiment of the present invention. Control flow chart at the time of cleaning operation of the copying machine according to the first embodiment of the present invention. (A)-(e) The figure for demonstrating the cleaning operation of the copying machine in Embodiment 1 concerning this invention. Configuration diagram of the vicinity of an intermediate transfer belt of a conventional image forming apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copier 2 Paper feed cassette 3 Original reading part 4 Black image formation part 5 Yellow image formation part 6 Cyan image formation part 7 Magenta image formation part 8 Intermediate transfer belt 9 Secondary transfer part 10 Fixing part 11 Cleaning device 12 Discharge roller pair 13 Discharge tray 14, 15, 16, 17 Primary transfer roller 21 Drive roller 22 Driven roller 23 Opposed roller 24 Driven roller 25 Registration roller

Claims (8)

A transfer belt to which a toner image is transferred;
A sensor for detecting the surface reflectance of the transfer belt;
A transfer member for transferring the toner image on the transfer belt onto a recording medium;
A removal unit provided to remove toner on the transfer belt, and applied with a voltage so as to have a polarity opposite to that of the toner;
The transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member, and the surface of the transfer member is transferred to the transfer member. After maintaining a state in which a voltage is applied to the transfer member so as to have a polarity opposite to the toner on the belt, the toner moved from the transfer belt onto the transfer member and the surface of the transfer member have the same polarity. And a controller that performs control to apply a voltage to the transfer member;
With
The control unit performs the control when the surface reflectance becomes a predetermined value or less,
By said control, said toner moved to the transfer belt from the transfer member may be removed from the transfer belt by the removal unit, the image forming apparatus. The controller is
At least a portion of the predetermined time;
The image forming apparatus according to claim 1, wherein control is performed so as to maintain a state in which there is a difference in moving speed between the surface of the transfer member and the surface of the transfer belt.   The image forming apparatus according to claim 1, wherein the predetermined time is at least a time for the intermediate transfer belt to make a round. The removing unit is
A fur brush roller in contact with the transfer belt;
The image forming apparatus according to claim 1, wherein a surface of the transfer belt is formed of a material whose main component is rubber. A voltage is applied to the transfer member so that the surface of the transfer member for transferring the toner image on the transfer belt onto which the toner image is transferred onto the recording medium has a polarity opposite to that of the toner discharged to the transfer belt. Reverse polarity application step,
A state after the reverse polarity application step in a state where the transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member. Holding step to hold,
After the holding step, the as from the transfer belt and toner moved onto the transfer member and the surface of the transfer member is the same polarity, the same polarity application step of indicia pressurizing a voltage to the transfer member,
A removal step of removing the toner moved from the transfer member to the transfer belt by the same polarity application step from the transfer belt by a removal unit ;
The reverse polarity applying step, the holding step, the same polarity applying step, and the removing step are performed when the surface reflectance of the transfer belt becomes a predetermined value or less. Control method. Along with the reverse polarity application step,
A speed changing step for performing a control for making a difference between the moving speeds of the surface of the transfer member and the surface of the transfer belt;
The image forming apparatus control method according to claim 5 , wherein the holding step holds the difference in the moving speed for at least a part of the predetermined time. The control method of the image forming apparatus according to claim 5 .
A voltage is applied to the transfer member so that the surface of the transfer member for transferring the toner image on the transfer belt onto which the toner image is transferred onto the recording medium has a polarity opposite to that of the toner discharged to the transfer belt. Reverse polarity application step,
A state after the reverse polarity application step in a state where the transfer belt and the transfer member are in rotational contact without passing through the recording medium for a predetermined time after the toner discharged on the transfer belt reaches the transfer member. Holding step to hold,
After the holding step, the same polarity application step of applying a voltage to the transfer member is executed on the computer so that the toner moved from the transfer belt onto the transfer member and the surface of the transfer member have the same polarity. Program to let you. A recording medium on which the program according to claim 7 is recorded, wherein the recording medium can be processed by a computer.

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