JP2009075259A - Image forming apparatus and control method for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for removing a matter adhered on the surface of an image carrier with less consumption of developer. <P>SOLUTION: The image forming apparatus includes a control means. The control means performs control such that in a non-image formation mode, toner is supplied to a photoreceptor drum 10 from a developing unit 13; a voltage is applied to a transfer roller 18 so that the surface of the transfer roller 18 has a polarity reverse to that of the toner; thereby the toner is moved to the transfer roller 18 from the photoreceptor drum 10; thereafter, a voltage applied to the transfer roller 18 is changed so that the surface of the transfer roller 18 has the same polarity as the toner; thereby the toner is moved to the photoreceptor drum 10 from the transfer roller 18. When changing the voltage, the control means applies different voltages at different timings. The absolute value of the voltage applied earlier is greater than that of the voltage applied later. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In an electrophotographic image forming apparatus, a charger, an exposure device, a developing device, a transfer device, a cleaning blade, and the like are provided around a photosensitive drum. After the surface of the photosensitive drum is uniformly charged by this charger, exposure is performed by the exposure device, an electrostatic latent image is formed on the surface of the photosensitive drum, and developed by the developing device. Thereafter, the developed toner image is transferred onto a recording medium by a transfer device, fixed by a fixing device, and then discharged outside the device. On the other hand, the toner remaining on the photosensitive drum during the transfer is removed by a cleaning blade.

  In such an image forming apparatus, ozone is generated during charging, and moisture in the air is decomposed by ozone to generate an ionic substance. When this ionic substance adheres to the surface of the photosensitive drum, the ionic substance is water-soluble, so that moisture in the atmosphere is taken in and the electrical resistance on the surface of the photosensitive drum is lowered. In this state where the low resistance layer water film is formed on the surface of the photosensitive drum, the surface charge of the electrostatic latent image formed on the surface of the photosensitive drum flows in the lateral direction, and the electrostatic latent image appears to be blurred. A problem called “turbulent image flow” that results in a distorted image occurs. In addition, since this malfunction occurs due to adhesion of moisture, it is more likely to occur in a high humidity environment.

  In addition, in the case of a photosensitive drum made of amorphous silicon, which has been often used in recent years to extend the life, such a problem is caused by the surface of the photosensitive member being oxidized by ozone, and easily adsorbing moisture. It occurs more prominently.

  In order to solve such a problem, an image forming apparatus is disclosed in which a low resistance layer water film is removed by providing a polishing roller in front of a cleaning blade (see, for example, Patent Document 1).

  FIG. 5 is a configuration diagram around the photosensitive drum of the conventional image forming apparatus. A conventional image forming apparatus includes a charger 201, an exposure device 202, a developing roller 203, a transfer roller 204, a rubbing roller 205, and a cleaning blade 206 around the photosensitive drum 200 as an image carrier in the rotation direction. , And a static eliminator 207 are provided.

  In such an image forming apparatus, when the temperature and humidity in the apparatus are detected and become a predetermined threshold value or more, a refining operation is performed in order to remove deposits such as ionic substances and water on the surface of the photosensitive drum 200. Is done. In this refining operation, a toner 210 as an example of a developer is supplied from the developing roller 203 onto the photosensitive drum 200, and a voltage having the same polarity as that of the toner is applied to the transfer roller 204 in the transfer area, whereby the rubbing roller Toner 210 is supplied between 205 and the photosensitive drum 200. Here, the toner exhibits the effect of wiping off the low-resistance water film as well as the effect of the abrasive.

  In the image forming apparatus shown in FIG. 5, the toner 210 attached to the rubbing roller 205 contains adhering substances such as the ionic substance and water. It is necessary to remove the deposits. As a method therefor, there is a method in which a voltage having a polarity opposite to that of the toner is applied. However, there are cases where deposits may remain, so it is more reliable to remove them by physical action, and a scraper 208 is provided. The toner and deposits removed by the scraper 208 are conveyed to a collection tank by a collection roller (not shown) and discarded.

In addition, in order to solve the above-described problem, another image forming apparatus that removes the low-resistance layer water film has been proposed (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-3014 JP 2004-279902 A

  However, the configuration in which the scraper is provided on the rubbing roller as described above has a problem that the toner consumption is increased for the following reason.

  FIG. 5 shows a state where the toner 210 is supplied to the rubbing roller. In FIG. 5, the charge of the toner 210 is described as positive. As shown in FIG. 5, since the toner supplied to the rubbing roller 205 is removed by the scraper 208, in order to polish the entire circumference of the photosensitive drum 200, the length is at least one circumference of the photosensitive drum 200. While toner is supplied, toner 210 needs to be supplied between the photosensitive drum 200 and the rubbing roller 205. On the other hand, at the time of polishing, it is not necessary to supply a large amount of toner between the photosensitive drum 200 and the rubbing roller 205 at once, and it is more important to supply toner for a long time even with a small amount.

  On the other hand, the amount of toner supplied from the developing roller 203 to the photosensitive drum 200 per unit time is not variable. Toner is required.

  Furthermore, since the refining operation is frequently performed under high temperature and high humidity, the amount of toner consumption increases, and the guaranteed number of prints in the toner container may not be achieved.

  In view of the above-described problems of the conventional image forming apparatus, the present invention provides an image forming apparatus and an image forming apparatus capable of removing deposits on the surface of the image carrier with a smaller amount of developer consumption than conventional ones. It is an object to provide a control method.

In order to achieve the above object, the first present invention provides:
An image carrier on which an electrostatic latent image is formed on the surface;
Developing means for supplying the developer to the image carrier to develop the electrostatic latent image and form a developer image;
A transfer member for transferring the developer image to a recording medium;
A cleaning member for removing deposits on the surface of the image carrier using the developer;
A removal member for removing the deposit from the surface of the cleaning member;
In the non-image forming mode, the developer is supplied from the developing unit to the image carrier, and a voltage is applied to the transfer member so that the surface of the transfer member has a polarity opposite to that of the developer. After the developer moves from the image carrier to the transfer member, the voltage applied to the transfer member for changing the surface of the transfer member to have the same polarity as the developer is changed from the transfer member. Control means for controlling the developer to move to the image carrier,
The control unit is an image forming apparatus in which when the voltage is changed, different voltages are applied at different timings, and the voltage applied at a later timing is larger in absolute value than the voltage applied at the previous timing. .

The second aspect of the present invention is
The cleaning member is a rubbing roller that removes deposits on the surface of the image carrier using the developer moved from the transfer member to the image carrier.
The removing member is a flexible member provided in contact with the rubbing roller to remove the developer and the adhering matter moved from the image carrier to the rubbing roller from the surface of the rubbing roller. 1 is an image forming apparatus according to a first aspect of the present invention, which is a plate-like member having a property.

The third aspect of the present invention
The transfer member is a roller-shaped member,
The control means includes
When the developer is supplied from the developing means to the image carrier, control is performed such that the outer circumference of the image carrier covered with the developer is longer than the outer circumference of the transfer member. 1 is an image forming apparatus according to a first aspect of the present invention.

The fourth aspect of the present invention is
The application of the different voltages at different timings is the image forming apparatus according to the first aspect of the invention in which the voltage applied to the transfer member is changed so that the absolute value thereof increases stepwise.

The fifth aspect of the present invention is
In the image forming apparatus according to the fourth aspect of the present invention, the time in one stage when increasing in stages is set to be longer than the time for one rotation of the transfer member.

The sixth aspect of the present invention
The image carrier is the image forming apparatus according to the first aspect of the present invention, the surface of which is formed of a material mainly composed of amorphous silicon.

The seventh aspect of the present invention
An image carrier on which an electrostatic latent image is formed on the surface;
Developing means for supplying the developer to the image carrier to develop the electrostatic latent image and form a developer image;
A transfer member for transferring the developer image to a recording medium;
A cleaning member for removing deposits on the surface of the image carrier using the developer;
A control method for an image forming apparatus, comprising: a removal member that removes the deposit from the surface of the cleaning member,
A supply step of supplying the developer from the developing means to the image carrier in a non-image forming mode;
A developer moving step of moving the developer from the image carrier to the transfer member by applying a voltage to the transfer member so that the surface of the transfer member has a polarity opposite to that of the developer;
After the developer moves, the voltage applied to the transfer member for changing the surface of the transfer member to the same polarity as the developer is changed, and the developer is transferred from the transfer member to the image carrier. A developer return step for performing control so as to move,
In the developer returning step, when changing the voltage, different voltages are applied at different timings, and the voltage applied at the later timing is larger in absolute value than the voltage applied at the previous timing. This is a control method.

  According to the present invention, it is possible to provide an image forming apparatus and an image forming apparatus control method capable of removing deposits on the surface of the image bearing member with a smaller amount of developer consumption than before.

  A copier as an example of an image forming apparatus according to the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a front view of the copying machine 100 according to the first embodiment of the present invention. The copying machine 100 is a copying machine that forms a monochrome image, and includes a document reading device 121 that reads an image of a document with an exposure lamp, a lens, a mirror, and the like at the top, and stores paper at the bottom. A plurality of paper feed cassettes 131 are provided.

  Further, the copying machine 100 includes an image forming unit 1 that creates a toner image based on image data read by the document reading device 121 from the center left.

  The image forming unit 1 includes an a-Si (amorphous silicon) photosensitive drum 10, a charger 11 for charging the photosensitive drum 10, and image data read by the document reading device 121. 10, an exposure device 12 that forms an electrostatic latent image, a developing device 13 that forms a toner image by attaching toner to the electrostatic latent image on the photosensitive drum 10, and a transfer for transferring the toner image to a sheet. A cleaning device 15 for polishing the surface of the photosensitive drum 10 to remove residual toner and the like on the surface of the photosensitive drum 10, and a static eliminator 16 for discharging the surface of the photosensitive drum 10. .

  The developing device 13 has a developing roller 17 for supplying toner to the photosensitive drum 10, and the transferring device 14 has a transfer roller 18 arranged so as to press the photosensitive drum 10. is doing. A voltage having a polarity opposite to that of the toner is applied to the transfer roller 18, and the toner image is transferred onto a sheet such as a recording medium.

  Further, as shown in FIG. 1, a fixing unit 141 for fixing the transferred toner image onto a sheet is provided on the downstream side of the photosensitive drum 10 with respect to the sheet conveyance path 30. A discharge roller 151 is provided further downstream of the fixing unit 141. A discharge tray 161 on which the paper discharged by the discharge roller 151 is placed is provided.

  Next, the configuration of the cleaning device 15 will be described.

  FIG. 2 is a configuration diagram of the image forming unit 1. As shown in FIG. 2, the cleaning device 15 according to the first embodiment contacts the rubbing roller 20 that presses the photosensitive drum 10, the scraper 21 that abuts against the rubbing roller 20, and the surface of the photosensitive drum 10. It has a cleaning blade 22 in contact therewith. As the rubbing roller 20, a roller having a brush shape or a sponge shape can be used. The cleaning blade 22 is in contact with the surface of the photosensitive drum 10 between the rubbing roller 20 and the static eliminator 16 at its tip.

  In addition, the cleaning device 15 has a scraper 21 for removing toner and the like on the surface of the rubbing roller 20. The scraper 21 is a flexible plate-like member, and is provided so that one end thereof is in contact with the surface of the rubbing roller 20. As the scraper 21, a PET film, urethane rubber, or the like can be used.

  Further, the cleaning device 15 includes a recovery screw 23 for recovering the toner and deposits removed by the scraper 21 and the cleaning blade 22, and the removed toner and deposits are conveyed by the recovery screw 23, Waste toner or the like is collected. A sheet 32 is provided below the rubbing roller 20 and between the cleaning device 15 and the photosensitive drum 10 so that the toner does not fall from the cleaning device 15. Since the sheet 32 is flexible and is arranged along the rotation direction of the photosensitive drum 10, the toner remaining on the surface of the photosensitive drum 10 is not obstructed by the sheet 32 and passes through the sheet 32. It reaches the rubbing roller 20.

  A temperature / humidity sensor 24 is provided in the vicinity of the photosensitive drum 10. In order to perform a refining operation for polishing the surface of the photosensitive drum 10 based on the value of the temperature / humidity sensor 24, the photosensitive drum 10, the developing roller 17, the transfer roller 18, the rubbing roller 20, and the recovery screw 23 are used. The control means 25 which controls etc. is provided.

  An example of the image carrier of the present invention corresponds to the photosensitive drum 10 of the present embodiment, and an example of the developing unit of the present invention corresponds to the developing device 13 of the present embodiment. An example of the transfer member of the present invention corresponds to the transfer roller 18 of the present embodiment, and an example of the cleaning member of the present invention corresponds to the rubbing roller 20 of the present embodiment. An example of the removing member and the plate-like member of the present invention corresponds to the scraper 21 of the present embodiment.

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

  First, the operation in the image forming mode will be described.

  Based on the image data read by the document reading device 121, an electrostatic latent image is formed by the exposure device 12 on the surface of the photosensitive drum 10 uniformly charged by the charger 11 in the image forming unit 1 and developed. A toner image visualized by the container 13 is formed (see FIG. 1).

  On the other hand, in accordance with the movement timing of the area on the photoconductive drum 10 where the paper is fed from the paper feed cassette 131 and the toner image is formed, the paper passes through the paper transport path 30 and the transfer roller 18 and the photoconductive drum 10. It is sent in between.

  At this time, the toner on the photoconductive drum 10 is positively charged, and the paper that has been conveyed through the paper conveyance path 30 by the negative charging due to the voltage applied to the transfer roller 18 and the pressing force of the transfer roller 18. The toner image is transferred to the toner image.

  Then, the sheet on which the toner image is transferred is conveyed to the fixing unit 141, and the toner image is fixed on the sheet. The sheet on which the toner image is fixed is discharged onto the discharge tray 161 through the discharge roller 151.

  As described above, the image forming operation is performed. However, when the temperature and humidity detected by the temperature / humidity sensor 24 are equal to or higher than a predetermined threshold (for example, temperature 28 ° C., humidity 60%), “turbulence image flow”. Therefore, in the non-image forming mode, a refining operation for removing deposits such as ionic substances and water on the surface of the photosensitive drum 10 is performed.

  Hereinafter, the refining operation of the copying machine of the first embodiment will be described, and an example of the control method of the image forming apparatus of the present invention will also be described. 3A to 3F are diagrams for explaining the refining operation. FIG. 4 is a diagram showing a timing chart during the refining operation.

  In the refining operation, first, a motor for driving the photosensitive drum 10 is operated to rotate the photosensitive drum 10 (see T1 in FIG. 4).

  Next, a motor for driving the developing roller 17 is operated, and the developing roller 17 rotates (see T2 in FIG. 4). Subsequently, when a voltage for development is applied to the developing roller 17 at T3, the toner 31 moves on the photosensitive drum 10 and a toner image is formed. This state is shown in FIG. The step of supplying the toner 31 to the photosensitive drum 10 in this way corresponds to an example of the supply step of the present invention.

  At the timing (T4) when the toner image formed on the photoconductive drum 10 reaches the transfer region, the transfer voltage at the time of image formation is applied to the transfer roller 18 so that the surface of the transfer roller 18 is negatively charged. The positively charged toner 31 applied to the photosensitive drum 10 is transferred onto the transfer roller 18. The step of moving the toner 31 from the photosensitive drum 10 to the transfer roller 18 in this way corresponds to an example of the developer moving step of the present invention. At this time, the toner 31 not transferred to the transfer roller 18 but remaining on the photosensitive drum 10 is supplied to the rubbing roller 20 and used for polishing the surface of the photoconductor drum 10 by the rubbing roller 20. .

  On the other hand, when the circumferential length of the toner supplied to the photoconductive drum 10 reaches the circumference of the transfer roller 18, the application of voltage to the developing roller 17 is stopped, and the supply of toner from the developing device 13 is performed. Is stopped (T5 in FIG. 4). That is, the time t from time T3 to time T5 corresponds to the time for which the transfer roller 18 makes one rotation. This state is shown in FIG.

  Then, a first reverse transfer voltage (for example, 100 V) is applied to the transfer roller 18 at a timing T6 when the transfer roller 18 rotates once after the transfer voltage is applied to the transfer roller 18. The state of the image forming unit 1 at the timing T6 is shown in FIG.

  Next, the first reverse transfer voltage is continuously applied to the transfer roller 18 from T6 to timing T7 when the transfer roller 18 makes one rotation. By this application, the surface of the transfer roller 18 is positively charged, and a part of the toner on the transfer roller 18 moves to the photosensitive drum 10. The toner 31 that has moved to the photosensitive drum 10 is supplied to the rubbing roller 20, and the low-resistance water film on the surface of the photosensitive drum 10 is wiped off by the abrasive contained in the toner 31 and the deposits are polished. Is done. The toner 31 and deposits supplied to the rubbing roller 20 are removed from the surface of the rubbing roller 20 by the scraper 21. This state is shown in FIG.

  Subsequently, a second reverse transfer voltage (for example, 300 V) having a larger absolute value than the first reverse transfer voltage is applied from timing T7 to timing T8 when the transfer roller 18 rotates once. By this application, a part of the toner remaining on the transfer roller 18 without moving to the photosensitive drum 10 by the application of the first reverse transfer voltage further moves to the photosensitive drum 10.

  Further, a third reverse transfer voltage (for example, 600 V) having an absolute value larger than the second reverse transfer voltage is applied to the transfer roller 18 from timing T8 to timing T9 when the transfer roller 18 rotates once. By this application, the toner that has not moved to the photosensitive drum 10 during T6 to T8 moves to the photosensitive drum 10, and polishing is performed by the rubbing roller 20 using this toner. This state is shown in FIGS. 3 (e) and 3 (f).

  At the timings T6 to T9, the absolute value of the reverse transfer voltage is increased step by step every time the transfer roller 18 rotates once. Here, in this embodiment, since the outer peripheral length of the photosensitive drum 10 is set to be smaller than three times the outer peripheral length of the transfer roller 18, the toner is continuously slid while the transfer roller 18 rotates three times. By supplying the rubbing roller 20, the entire circumference of the photosensitive drum 10 can be polished. Note that the step of gradually increasing the absolute value of the reverse transfer voltage like the timings T6 to T9 corresponds to an example of the developer returning step of the present invention.

  Subsequently, from timing T9 to T10, the surface of the transfer roller 18 is temporarily set to zero potential, and further, a transfer voltage is applied to the transfer roller 18 from T10 to T11. The period t9 to T10 and the period T10 to T11 are times t for which the transfer roller 18 makes one rotation. By the control from T9 to T11, the toner on the transfer roller 18 is charged again.

  Then, a voltage having the same value as the second reverse transfer voltage is applied to the transfer roller 18 from T11 to T12. Even when the control from T6 to T9 does not move onto the photosensitive drum 10 and the toner remains on the transfer roller 18, the control from T10 to T12 is performed to perform the control on the transfer roller 18. The remaining toner can be completely moved onto the photosensitive drum 10.

  As described above, in the image forming apparatus of the present embodiment, in the refining operation, the toner supplied from the developing roller 17 is not directly supplied to the rubbing roller 20 but is once attached to the surface of the transfer roller 18. Then, control is performed such that the toner is gradually supplied from the transfer roller 18 to the photosensitive drum 10.

  Therefore, it is sufficient to supply the toner for a time corresponding to one rotation of the transfer roller 18, and it is not necessary to supply the toner for a time corresponding to one rotation of the photosensitive drum 10 as in the prior art, so that the toner consumption can be reduced. .

(Example)
Hereinafter, specific examples will be described.

  In the above embodiment, the outer diameter of the photosensitive drum 10 is set to φ40 mm, the outer diameter of the developing roller 17 is set to φ20 mm, the outer diameter of the transfer roller 18 is set to φ16 mm, and the outer diameter of the rubbing roller 20 is set to φ14 mm. In this case, the outer peripheral length of the photosensitive drum 10 is 125.6 mm, the outer peripheral length of the developing roller 17 is 62.8 mm, the outer peripheral length of the transfer roller 18 is 50.2 mm, and the outer peripheral length of the rubbing roller 20 is 44. 0.0 mm.

  In the refining operation, the peripheral speed of the photosensitive drum 10 is 105 mm / s, the peripheral speed of the developing roller 17 is 164 mm / s, the peripheral speed of the transfer roller 18 is 108 mm / s, and the peripheral speed of the rubbing roller 20 is 115 mm. / S.

  Further, the current for transfer applied to the transfer roller 18 between T4 and T6 is −50 μA, the reverse transfer voltage applied to the transfer roller 18 between T6 and T7 is +100 V, and between T7 and T8. + 300V and between T8 and T9 are + 600V.

  At this time, conventionally, the toner of the length corresponding to one turn of the photosensitive drum 10 has been supplied, so that the toner consumption amount is 700 mg.

  On the other hand, when the toner is dividedly supplied by the transfer roller 18, the necessary toner amount is one turn of the transfer roller 18, which is 280 mmg.

  Therefore, for example, if the refining operation is performed twice a day at high humidity such as in the rainy season, the toner consumption amount is (700−280) mg × 2 × 40 days = 33.6 g in 40 days. Will be reduced.

  As described above, the copying machine of this embodiment can reduce the amount of toner consumed in the refining operation in the non-image forming mode as compared with the conventional case.

  In the present embodiment, for example, 100V is applied as the first reverse transfer voltage from T6 to T7, but it may be 0V. In the case of 0V, the number of times of voltage or current switching with respect to the transfer roller 18 can be reduced, and even in the case of 0V, in the first rotation, a large amount of toner adheres to the transfer roller 18. Since the toner can move to the photosensitive drum 10, the surface of the photosensitive drum 10 can be polished.

  In this embodiment, the toner is supplied to the photosensitive drum 10 for one rotation of the transfer roller 18, but may be more than one rotation, and may be longer than the entire circumference of the photosensitive drum 10. If it is short, the effect of the present invention can be exhibited.

  In this embodiment, the reverse transfer voltage is held constant during one rotation of the transfer roller 18 from T6 to T9. However, the reverse transfer voltage is held constant for a longer time than during one rotation. May be. Furthermore, the absolute value of the reverse transfer voltage may be controlled to increase in a shorter time than during one rotation of the transfer roller 18, but the toner for the entire circumference of the photosensitive drum 10 is continued. It is preferable to adjust the degree of increase of the reverse transfer voltage so that it can be supplied.

  In the above embodiment, since the toner as an example of the developer of the present invention is positively charged, a large voltage is applied stepwise so that the positive charge amount on the surface of the transfer roller 18 is increased. However, when the toner is negatively charged, a negative voltage whose absolute value increases stepwise may be applied so that the negative charge amount on the surface of the transfer roller 18 increases.

  In this embodiment, the voltage applied to the transfer roller 18 is changed so that the absolute value of the reverse transfer voltage increases in three stages. You may control in steps. Further, the control may be performed so that the absolute value of the potential difference increases linearly without being limited in stages.

  In short, if at least two different voltages are applied so that the absolute value of the voltage applied at the later timing is larger than the voltage applied at the earlier timing in time, the transfer roller 18 is applied. From the toner to the photosensitive drum 10 can be divided and supplied.

  In this embodiment, a transfer voltage is applied to the transfer roller 18 at T10 to T11, and after the toner on the transfer roller 18 is positively charged, a reverse transfer voltage is applied to the transfer roller 18 at T11 to T12. Thus, the toner on the transfer roller 18 is more reliably moved onto the photosensitive drum 10. For example, the toner 31 is transferred to the transfer roller 18 by controlling the reverse transfer voltage stepwise from T6 to T9. When it does not remain, the control shown in the above T10 to T12 may not be performed.

  In addition, when the absolute value of the voltage applied to the transfer roller 18 for reverse transfer is increased stepwise, control is performed so that the transfer voltage is applied to the transfer roller 18 and the charge is injected into the toner between the steps. It may be broken.

  In the present embodiment, when toner is supplied from the developing unit 13 to the photosensitive drum 10, the toner is supplied to the entire axial width of the photosensitive drum 10, but "turbulent image flow" occurs. You may make it supply only to the part which is easy to do. This “disturbed image flow” is more likely to occur in a place where the toner image is formed less frequently. For example, toner is supplied only to both ends in the axial direction of the photosensitive drum 10 where the toner image is formed less frequently. The toner consumption can be further saved by controlling so that only the both ends of the photosensitive drum 10 are polished. Further, a means for detecting the print amount in the axial direction of the photosensitive drum 10 is provided, and the toner supply amount in the axial direction of the photosensitive drum 10 is changed according to the detected print amount, thereby further saving the toner consumption. I can do it.

  In this embodiment, the transfer roller 18 is used as an example of the transfer member of the present invention. However, an intermediate transfer belt may be used, and the toner is transferred to an area of a predetermined length of the intermediate transfer belt. The effect of the present invention can be obtained by performing reverse transfer from the region to the photosensitive drum step by step.

  A program for causing a computer to execute the supplying step, the developer moving step, and the developer returning step of the control method for the image forming apparatus of the present invention described above may be created. By causing the computer to execute the program, the same effect as that obtained when the control method for the image forming apparatus is executed can be obtained.

  Further, a recording medium that records the above-described program and that can be processed by a computer may be created. By using the recording medium, the same effect as when the image forming apparatus control method is executed can be obtained.

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

  The “partial steps” means one or several steps out of the plurality of steps. Further, the “operation of some steps” means the operation of all or a part of the steps.

  Further, one usage form of the program 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.

  Further, one use form of the program may be an aspect in which the program is transmitted through a transmission medium such as the Internet or a transmission medium such as light, radio wave, and sound wave, read by a computer, and operated in cooperation with the computer. .

  The computer 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 the effect of removing deposits on the surface of the image carrier with a smaller amount of developer consumption than in the past. It is useful as a facsimile.

1 is a front configuration diagram schematically showing a copying machine according to a first embodiment of the present invention. 1 is a configuration diagram of an image forming unit 1 of a copying machine according to a first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the refining operation of the copying machine according to the first embodiment of the present invention. FIG. 3 is a timing chart of the refining operation of the copying machine according to the first embodiment of the present invention. Schematic diagram for explaining the conventional refining operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming unit 11 Charging device 12 Exposure device 13 Developing device 14 Transfer device 15 Cleaning device 16 Static eliminator 17 Developing roller 18 Transfer roller 20 Rub roller 21 Scraper 22 Cleaning blade 23 Collecting screw 24 Temperature / humidity sensor

Claims (7)

An image carrier on which an electrostatic latent image is formed on the surface;
Developing means for supplying the developer to the image carrier to develop the electrostatic latent image and form a developer image;
A transfer member for transferring the developer image to a recording medium;
A cleaning member for removing deposits on the surface of the image carrier using the developer;
A removal member for removing the deposit from the surface of the cleaning member;
In the non-image forming mode, the developer is supplied from the developing unit to the image carrier, and a voltage is applied to the transfer member so that the surface of the transfer member has a polarity opposite to that of the developer. After the developer moves from the image carrier to the transfer member, the voltage applied to the transfer member for changing the surface of the transfer member to have the same polarity as the developer is changed from the transfer member. Control means for controlling the developer to move to the image carrier,
The control unit applies different voltages at different timings when changing the voltage, and the voltage applied at a later timing has a larger absolute value than the voltage applied at the previous timing. The cleaning member is a rubbing roller that removes deposits on the surface of the image carrier using the developer moved from the transfer member to the image carrier.
The removing member is a flexible member provided in contact with the rubbing roller to remove the developer and the adhering matter moved from the image carrier to the rubbing roller from the surface of the rubbing roller. The image forming apparatus according to claim 1, wherein the image forming apparatus is a plate-like member having properties. The transfer member is a roller-shaped member,
The control means includes
When the developer is supplied from the developing means to the image carrier, control is performed such that the outer circumference of the image carrier covered with the developer is longer than the outer circumference of the transfer member. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein applying the different voltages at different timings is changing the voltage applied to the transfer member so that the absolute value thereof increases stepwise.   5. The image forming apparatus according to claim 4, wherein a time in one stage when increasing in stages is set to be equal to or longer than a time for one rotation of the transfer member.   The image forming apparatus according to claim 1, wherein the image carrier has a surface formed of a material mainly composed of amorphous silicon. An image carrier on which an electrostatic latent image is formed on the surface;
Developing means for supplying the developer to the image carrier to develop the electrostatic latent image and form a developer image;
A transfer member for transferring the developer image to a recording medium;
A cleaning member for removing deposits on the surface of the image carrier using the developer;
A control method for an image forming apparatus, comprising: a removal member that removes the deposit from the surface of the cleaning member,
A supply step of supplying the developer from the developing means to the image carrier in a non-image forming mode;
A developer moving step of moving the developer from the image carrier to the transfer member by applying a voltage to the transfer member so that the surface of the transfer member has a polarity opposite to that of the developer;
After the developer moves, the voltage applied to the transfer member for changing the surface of the transfer member to the same polarity as the developer is changed, and the developer is transferred from the transfer member to the image carrier. A developer return step for performing control so as to move,
In the developer returning step, when changing the voltage, different voltages are applied at different timings, and the voltage applied at the later timing is larger in absolute value than the voltage applied at the previous timing. Control method.

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