JP2007212843A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of avoiding such failure that an image defect is caused by the occurrence of reverse electrification when starting driving. <P>SOLUTION: The image forming apparatus which forms an image on a recording medium by forming a toner image and transferring and fixing the toner image on the recording medium is equipped with: an image carrier which rotates at predetermined speed and on the surface of which an electrostatic latent image is formed while rotating; a rubber abutting body which abuts on the surface of the image carrier at a standstill position relative to the rotation of the image carrier; and a control part which controls the rotating speed of the image carrier to initial speed lower than the predetermined speed temporarily when starting the rotation of the image carrier. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium by transferring and fixing a toner image formed on an image carrier onto the recording medium.

Conventionally, the surface of a rotating photoreceptor is charged, the surface of the charged photoreceptor is exposed to form a latent image, the latent image is developed to form a toner image, and the toner image is directly In addition, there is known an image forming apparatus employing an electrophotographic system in which an image is finally transferred onto a recording medium through an intermediate transfer member or the like. For the charger for charging the surface of the photosensitive member, a conductive metal core is a rubber whose electric resistance is adjusted to about 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω · cm by carbon black, an ionic conductive agent, or the like. In many cases, a semiconductive elastic roll covered with is provided, and the elastic roll is brought into contact with the photoconductor at a predetermined pressure, and is driven to rotate with the photoconductor to uniformly charge the photoconductor. It is generally done.

  Here, in the image forming apparatus described above, since the rubber elastic roll provided in the charger is in contact with the photosensitive member at a predetermined pressure, when left unused for a long time under high temperature and high humidity, Depending on the affinity between the materials constituting the photoconductor and the charger, tack (sticking) may occur at the boundary surface, and when the drive of the photoconductor is resumed and the tack is peeled off, the peeling discharge May occur.

  In addition, as the cumulative number of images formed by the image forming apparatus increases, a small amount of paper dust generated by friction or the like when passing through the surface of the photoreceptor or charger, or a small amount remaining during transfer or cleaning. In some cases, toner or the like is accumulated, and uneven charging or uneven transfer may occur in the accumulated portion. For this reason, photoreceptors and chargers are coated with a highly releasable material containing fluorine on the surface, or the surface is formed smoothly, thereby reducing the adhesion of unnecessary materials such as paper dust and toner. Is planned. In such an image forming apparatus, since the friction between the photoconductor and the charger is reduced, the charger cannot be driven when the photoconductor starts to be driven, and the rubbing between the photoconductor and the charger is performed. May occur and frictional discharge may occur.

  As described above, when peeling discharge or frictional discharge occurs between the photosensitive member and the charger, the surface of the photosensitive member is charged with a polarity opposite to that of charging by the charger (hereinafter referred to as charging by the charger). Is called reverse charging), and the portion where the reverse charging occurs appears as white stripes or black stripes in the image.

Normally, a negatively charged toner is used, the photoreceptor is negatively charged by a charger, and the photoreceptor is often positively charged by the above-described peeling discharge and frictional discharge. Document 1 describes a technique for reducing the reverse charging of the photoreceptor due to the discharge by interposing a powder charged on the positive side of the charge on the photoreceptor surface between the photoreceptor and the charger. ing.
JP-A-7-84432

  However, according to the technique described in Patent Document 1, the positively charged powder adheres to the surface of the charger, and the adhered portion increases the electrical resistance to cause uneven charging, or rotation of the photoreceptor. As a result, there is a problem that the powder enters the gap between the charger and the developing device or the developing device, and the powder hinders development, resulting in image defects.

  Such a problem is not a problem that occurs only between the photosensitive member and the charger, but a problem that also occurs in a rubber cleaning blade that contacts the photosensitive member.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which a problem that reverse charging occurs at the start of driving to cause an image defect is avoided.

An image forming apparatus of the present invention that achieves the above object is an image forming apparatus for forming an image on a recording medium by forming a toner image and transferring and fixing the toner image on the recording medium.
An image carrier that rotates at a predetermined speed and forms an electrostatic latent image on the surface during rotation;
A rubber contact member that contacts the surface of the image carrier at a position stationary relative to the rotation of the image carrier;
And a controller for temporarily controlling the rotation speed of the image carrier to an initial speed lower than a predetermined speed when the rotation of the image carrier is started.

  According to the image forming apparatus of the present invention, when the rotation of the image carrier is started, the rotation speed of the image carrier is temporarily controlled to the initial speed and then accelerated to a predetermined speed. For this reason, even when a tack occurs between the rubber contact body and the image carrier, the tack is slowly peeled off, so that the occurrence of peeling discharge can be avoided. The contact body can reliably follow the rotation of the image carrier, and the occurrence of frictional discharge can be avoided. Therefore, even when the image forming apparatus is left unused for a long period of time or the friction between the image carrier and the abutting member is reduced, the image carrying due to peeling discharge or frictional discharge is performed. The reverse charging of the body is avoided, and the problem that white stripes and black stripes are generated in the image can be reduced.

  In the image forming apparatus according to the aspect of the invention, the control unit may detect the length of the contact portion between the image carrier and the contact member in the rotation direction of the image carrier after the rotation of the image carrier is started. It is preferable that the rotational speed of the image carrier is controlled to the initial speed until the rotational movement.

  According to the image forming apparatus of the preferred embodiment of the present invention, even when a tack occurs at the contact portion between the image carrier and the abutting body, the image bearing body is removed until the tack is removed. Since the rotation speed is controlled to the initial speed, it is possible to reliably avoid the occurrence of peeling discharge.

In the image forming apparatus of the present invention, the control unit controls the acceleration as well as the rotation speed of the image carrier, and controls the angular acceleration of the image carrier to 60 rad / s ² or less. Is preferred.

By controlling the acceleration to 60 rad / s ² or less, it is possible to reliably reduce the occurrence of peeling discharge and frictional discharge.

In the image forming apparatus of the present invention, “the abutting body is driven and moved along with the rotation of the image carrier,
The control unit controls the acceleration as well as the rotation speed of the image carrier. The force required to rotate the image carrier at the angular acceleration is determined by the contact body and the image carrier. A configuration in which the static friction force between the body and the body is controlled so as not to be exceeded is preferable.

  According to this preferred embodiment of the image forming apparatus, it is possible to reliably avoid the occurrence of frictional discharge.

  Further, in the image forming apparatus of the present invention, the image carrier has a surface roughness with Rz of 5 μm or less, so that a great effect is obtained.

  An image carrier having a surface roughness Rz of 5 μm or less can avoid the adhesion of unnecessary objects with high accuracy, but the friction between the image carrier and the contact member is also reduced, so the image carrier starts to drive. The contact body slips without being driven, and frictional discharge is likely to occur. Therefore, a great effect can be obtained by being applied to the image forming apparatus of the present invention.

In addition, the image forming apparatus of the present invention includes a “main body housing,
An image carrier, and a cartridge in which the contact body is housed, and a cartridge that is detachably attached to the main body housing,
It is preferable that the control unit controls the rotational speed of the image carrier to the initial speed only when the image carrier first rotates after the cartridge is mounted on the main body casing.

  When the cartridge is replaced and the image carrier is rotated for the first time, tack often occurs between the image carrier and the contact member, so the rotation speed of the image carrier is controlled to the initial speed. By doing so, generation of peeling discharge can be avoided. In addition, once the image carrier is rotated, the tack between the image carrier and the abutting member is peeled off, so that the rotation speed of the image carrier is immediately controlled without being controlled to the initial speed. By accelerating the speed, the startup speed of the image forming apparatus can be improved.

In the image forming apparatus of the present invention, “a main body housing,
An image carrier, and a cartridge in which the contact body is housed, and a cartridge that is detachably attached to the main body housing;
A detection unit for detecting whether or not the cartridge is unused,
It is preferable that the control unit controls the rotational speed of the image carrier to the initial speed only when the detection unit detects that the cartridge is unused.

  According to this preferred embodiment of the image forming apparatus, it is possible to reliably achieve avoidance of image defects and improvement of processing speed.

  According to the present invention, it is possible to provide an image forming apparatus in which a problem that reverse charging occurs at the start of driving to cause an image defect is avoided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a main part of an image forming apparatus to which an embodiment of the present invention is applied.

  The image forming apparatus 1 shown in FIG. 1 forms an electrostatic latent image on a photoreceptor 11, develops the electrostatic latent image with toner, forms a toner image, and transfers and fixes the toner image on a recording medium. Thus, the image forming apparatus forms an image composed of a fixed toner image on the recording medium. Specifically, the image forming apparatus 1 is a single-color printer that prints a black and white image using black (K) toner, and a cartridge in which a developing device (described later) in which toner is stored is stored. Can be attached to and detached from the main body housing 1a.

  The image forming apparatus 1 includes a cartridge 10 in which a photoreceptor 11, a charger 12, a developing device 13, and a cleaner 14 are stored, an exposure device 20, a transfer device 41, a fixing device 42, and a conveyance belt 43. A paper feed tray 44 and a control unit 50, and a memory 31 mounted in the cartridge 10, an access device 30 for accessing the memory 31, and the like. The control unit 50 corresponds to an example of a control unit according to the present invention, and various elements constituting the image forming apparatus 1 are controlled by the control unit 50.

  A basic operation in image formation of the image forming apparatus 1 will be described.

  First, as a preparation for forming an image, the cartridge 10 is mounted on the main body housing 1a by the user. The cartridge 10 corresponds to an example of a cartridge according to the present invention.

  In the memory 31 attached to the cartridge 10, a flag indicating the use state of the cartridge 10 is recorded. In the unused cartridge 10, “0: Unused” is set in the flag.

  When the image forming apparatus 1 is turned on, the access device 30 accesses the memory 31 at every predetermined timing. When the cartridge 10 is mounted, the flag recorded in the memory 31 is read by the access device 30 to detect the mounting of the cartridge 10 and whether or not the cartridge 10 is unused. The access device 30 corresponds to an example of the detection unit referred to in the present invention.

  Subsequently, the rotation of the photoconductor 11 is started. The image forming apparatus 1 has a surface roughness Rz of 5 μm or less in order to avoid a problem that residual toner or paper powder remaining without being transferred adheres to the surface of the photoreceptor 11. A smooth photoreceptor 11 is used. The photoconductor 11 corresponds to an example of an image carrier referred to in the present invention.

  FIG. 2 is a schematic configuration diagram showing various elements for driving the photoconductor 11.

  2 includes a control unit 50, a transmitter 114 that emits a pulse signal, a drive circuit 113 that rotates and drives the drive motor 112 at a rotational speed corresponding to the pulse signal, and the photosensitive member 11 shown in FIG. A drive motor 112 for rotating in the direction and a speed reducer 111 for increasing the torque by decelerating the rotation by the drive motor 112 are shown.

  The type of the drive motor may be either an AC motor or a DC motor, but a DC motor is more preferable because the output torque of the motor is less likely to decrease even when the rotational speed is low. In addition, as a method for controlling the rotational speed of the drive motor, a method of inputting current and voltage to the drive circuit and controlling by the input amount, a pulse signal being input to the drive circuit, the amplitude of the pulse signal, the pulse width, A method of controlling by the pulse interval is known. In the control by current or voltage, if the input amount is reduced, the output torque of the drive motor is also reduced, and the rotational speed of the drive motor is not stabilized due to the increase or decrease of the load torque, so the control by the pulse signal is more preferable. . In the present embodiment, a DC motor is applied as the drive motor 112, and the rotation speed of the drive motor 112 is adjusted by controlling the pulse interval of the pulse signal transmitted from the transmitter 114 by the control unit 50.

  When the photosensitive member 11 is rotationally driven, first, an instruction is transmitted from the control unit 50 to the access device 30 shown in FIG. 1, and the flag of the memory 31 is read by the access device 30. When the flag is “0: unused”, the access device 30 rewrites the flag to “1: used”. The method of using this flag will be described in detail later.

  Subsequently, a pulse interval is instructed from the control unit 50 to the transmitter 114, and a pulse signal is generated from the transmitter 114. The pulse signal is transmitted to the drive circuit 113, and the drive circuit 113 rotates the drive motor 112 at a drive speed according to the pulse interval of the pulse signal. The rotation of the drive motor 112 is transmitted to the speed reducer 111, and the speed is reduced by the speed reducer 111 to increase the torque. The photoconductor 11 is rotated in the direction of arrow A by the increased torque.

  Here, the charger 12 shown in FIG. 1 is in contact with the photoconductor 11 at a predetermined pressure, and when the photoconductor 11 is driven to rotate, the charger 12 is rotated in accordance with the rotation.

  FIG. 3 is a schematic configuration diagram of the charger 12.

  The charger 12 includes a roll core material 121 having conductivity, a conductive rubber layer 122 that covers the roll core material 121, and a surface protective layer 123 that covers the rubber layer 122. By applying the surface protective layer 123, a problem that unnecessary substances adhere to the charger 12 is reduced. The charger 12 corresponds to an example of a contact body according to the present invention.

  A predetermined charge is applied to the surface of the photoconductor 11 by the charger 12 being in contact with the photoconductor 11 and being driven to rotate.

  Subsequently, image data generated by reading an original image with an image reading device (not shown) is sent to the exposure device 20 shown in FIG. In the exposure device 20, laser light corresponding to the image data is applied to the photoconductor 11 in the cartridge 10.

  When the exposure device 20 irradiates the photoconductor 11 with laser light, an electrostatic latent image (electrostatic latent image) is formed on the surface of the photoconductor 11. The electrostatic latent image is developed by a developing voltage applied to a developing position between the developing device 13 and the photoconductor 11 with toner contained in the developer circulated and supplied by the developing device 13, and the photoconductor A toner image is formed on 11.

  The recording paper stored in the paper feed tray 44 reaches the transfer position in synchronization with the timing at which the toner image formed on the photoconductor 11 reaches the transfer position between the transfer device 41 and the photoconductor 11. In addition, the recording sheet is conveyed by the conveying belt 43. When a transfer bias voltage is applied to the transfer device 41, the toner image formed on the photoconductor 11 is transferred onto the recording paper conveyed to the transfer position.

  A cleaner 14 provided with a rubber blade is disposed on the downstream side of the transfer position in the rotation direction of the photoconductor 11 (arrow A direction). When the toner image on the photoconductor 11 is transferred onto the recording paper, the residual toner remaining on the photoconductor 11 is scraped off and removed by a blade provided in the cleaner 14. The cleaner 14 also corresponds to an example of the contact body according to the present invention.

  The toner image transferred onto the recording paper is conveyed together with the recording paper and fixed on the recording paper by the fixing device 42 to form a black and white image. The recording paper on which the black and white image is formed is discharged out of the main body housing 1a by the transport belt 43 that moves in the arrow B direction.

  Basically, an image is formed on a recording sheet as described above.

  Next, the relationship between the rotation speed of the photoconductor 11 and the charger 12 and the cleaner 14 will be described in detail.

  FIG. 4 is a diagram showing the arrangement of the photoconductor 11, the charger 12, and the cleaner 14.

As shown in FIG. 4, the charger 12 and the cleaner 14 are in contact with the photoconductor 11 at a predetermined pressure. Since the charger 12 and the cleaner 14 are made of rubber at the portion that comes into contact with the photoconductor 11, the photoconductor 11 and the charger 12 are used when an unused cartridge 10 is mounted on the main body housing 1a. In many cases, tack is generated in the contact portion P ₂ between the photosensitive member 11 and the contact portion P ₁ between the photosensitive member 11 and the cleaner 14. Discharge occurs.

  Further, the charger 12 is driven to rotate in the direction of arrow A ′ as the photoconductor 11 rotates in the direction of arrow A. In the present embodiment, the surface of the photoconductor 11 is formed smoothly in order to prevent unwanted substances from adhering to the photoconductor 11 and the charger 12, and the surface protection layer 123 (see FIG. 3), and the friction between the photoconductor 11 and the charger 12 is small. For this reason, when the photosensitive member 11 is rotationally driven at a high speed, the charger 12 cannot be driven and slips, and frictional discharge occurs.

  The peeling discharge and frictional discharge as described above charge the photosensitive member 11 with a polarity opposite to that of the charging by the charger 12, and may cause an image defect in an image formed on the recording paper. Therefore, in the image forming apparatus 1 of the present embodiment, when the unused cartridge 10 is mounted on the main body housing 1a and the photosensitive member 11 is first rotated, the rotational speed of the photosensitive member 11 is a normal steady state. Controlled to an initial speed slower than the speed.

  First, the flag recorded in the memory 31 is read by the access device 30 shown in FIG. 1, and the value of the read flag is transmitted to the control unit 50. When the value of the flag is “1: used”, the control unit 50 notifies the transmitter 114 shown in FIG. 2 of a pulse interval for rotating the photoconductor 11 at a normal steady speed, When the value is “0: unused”, a pulse interval for rotating the photoconductor 11 at the initial speed is transmitted. As a result, the drive motor 112 is rotationally driven at a drive speed corresponding to the pulse interval of the pulse signal emitted from the transmitter 114, and the rotational speed of the photoconductor 11 is controlled.

  FIG. 5 is a graph showing the rotation speed of the photoconductor 11.

In FIG. 5, the horizontal axis is associated with time (sec), and the vertical axis is associated with the rotational speed (mm / sec) of the surface due to the rotation of the photoconductor 11. The rotation speed of the photoreceptor 11 is controlled to an initial speed V ₀ (0.1 to 10 mm / sec: 10 mm / sec in the present embodiment) from the start of driving to a specified time T, and the specified time. After T has elapsed, the normal steady speed V ₁ (V ₁ > V ₀ : 170 mm / sec in the present embodiment) is controlled.

Further, the angular acceleration of the photoconductor 11 is controlled to an angular acceleration (60 rad / s ² in this embodiment) that suppresses the slip of the charger 12. The condition that the charger 12 slips is that the sum of the sliding resistance of the bearing portion of the charger 12 and the torque obtained by the moment of inertia of the charger 12 x angular acceleration is between the charger 12 and the photoconductor 11. It exceeds the static friction force generated in Therefore, the slip of the charger 12 can be suppressed by adjusting the pulse interval of the pulse signal emitted from the transmitter 114 and controlling the angular acceleration of the photoconductor 11. Further, shown in FIG. 4, the photosensitive member 11 and the charger 12 contact portion between P _2, and the photosensitive member 11 and the contact portion of the larger of the abutment portion P ₁ of the cleaner 14 P _2, the direction of rotation when a length of the nip width w in (arrow a direction), the specified time T = a nip width w / initial velocity V _0. By applying such a predetermined time T, the photosensitive member 11 can be rotated at the initial speed V ₀ until the tack generated at the contact portions P ₁ and P ₂ is reliably peeled off.

Thus, until the tack generated at the contact portions P ₁ and P ₂ is peeled off, the occurrence of peeling discharge can be reduced by rotating the photoconductor 11 at the slow initial speed V ₀ . Further, since the angular acceleration of the photoconductor 11 is suppressed to 60 rad / s ² or less, the charger 12 can be reliably driven to rotate, and frictional discharge can be suppressed. From the above, according to the image forming apparatus of the present embodiment, it is possible to avoid a problem that an image defect occurs when the rotational driving of the photosensitive member 11 is started.

In the present embodiment, the speed control described above is executed and the flag recorded in the memory 31 only when the photosensitive member 11 is rotated for the first time after the unused cartridge 10 is mounted on the main body housing 1a. When the value of “1” is “used”, the rotational speed of the photosensitive member 11 is accelerated to the steady speed V _{1 as} soon as the rotation of the photosensitive member 11 is started. In a state where the photosensitive member 11 is rotated at least once, because the tack that occurs between the a photosensitive member and the charging device has been removed, by accelerating immediately steady speed V _1, the processing speed Can be improved.

  Here, the example in which the charger and the cleaner are applied as the contact body according to the present invention has been described above. However, the contact body according to the present invention is made of rubber and is in contact with the photoreceptor. If present, it may be an element other than the charger and the cleaner.

  In the above description, an example of a monochrome printer that forms a monochrome image has been described. However, the image forming apparatus of the present invention may be a color printer that forms a color image using multicolor toners.

  In the above description, the example in which the rotation speed control of the photosensitive member is executed only when an unused cartridge is mounted on the main body housing has been described. However, the image forming apparatus in which a used cartridge is mounted However, when it is left unused for a long period of time without being used in a hot and humid environment, there is a risk that image defects due to reverse charging as described above may occur. Therefore, for example, the rotation speed control as described above may be executed whenever the photosensitive member starts rotating immediately after the power of the image forming apparatus is turned on.

  Examples of the present invention will be described below.

An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 is applied. The image forming apparatus, the contact portion P ₂ of the photoreceptor 11 and charging unit 12 shown in FIG. 4, the length in the rotational direction (the nip width w in FIG. 4) is 0.5 mm, in the direction along the rotation axis The length is 330 mm, the weight of the charger 12 is 195 g, the outer diameter of the charger 12 is 14 mm, and the static friction coefficient on the surface of the charger 12 is 0.6.

As described above, the angular acceleration ω at which the charger 12 does not slip reliably with respect to the photoreceptor 11 can be obtained from the calculation formula. However, since the surface of the charger 12 is made of rubber, Therefore, it is difficult to calculate an accurate value because the contact area, frictional force, and the like of the battery or the sliding resistance of the bearing portion of the charger 12 are not uniform. For this reason, by using the large charger 12 to increase the moment of inertia and sliding resistance, and by conducting an experiment under conditions where the charger 12 is likely to slip, the angular acceleration ω = 60 rad at which the charger 12 does not slip. / S ² was determined.

In such an image forming apparatus 1, an unused cartridge 10 was prepared and left in a hot and humid environment of 43 ° C. and 90% RH for 169 hours. In this state, the tack is considered to have occurred at the contact portion P ₂ of the photosensitive member 11 and the charger 12. Thereafter, in driving the image forming apparatus 1, examples and comparative examples were prepared in which the rotational speed of the photoconductor 11 was changed as follows.

Example 1
The rotational speed of the photoconductor 11 was controlled in two stages as shown below.

1. First stage (2 seconds after the rotation of the photoconductor 11 is started)
The angular acceleration of the photoreceptor 11 was controlled so as not to exceed 60 rad / s ^2, and the rotational speed of the photoreceptor 11 was further suppressed to an initial speed of 10 mm / sec.

2. Second stage (2 seconds after the rotation of the photoconductor 11 is started)
The rotational speed of the photoconductor 11 was accelerated until the steady speed reached 170 mm / sec.
(Comparative example)
The angular acceleration of the photoconductor 11 was controlled to 125 rad / s ^2, and immediately after the rotation of the photoconductor 11 was started, the rotation speed of the photoconductor 11 was accelerated to a steady speed of 170 mm / sec.
(Evaluation methods)
A black and white image was formed on the recording paper under the above conditions, and it was evaluated whether white stripes or black stripes were generated on the image.
(Evaluation results)
In the example, white stripes and black stripes were not generated in the formed image. This is because when the driving of the photoconductor 11 is started, the rotation speed is suppressed to an initial speed slower than the steady speed, and the tack generated between the photoconductor 11 and the charger 12 is slowly peeled off. For this reason, it is considered that the occurrence of peeling discharge is avoided, and furthermore, since the charger 12 is reliably driven and rotated as the photoconductor 11 rotates, the occurrence of frictional discharge is also prevented.

  In the comparative example, black streaks were detected in the formed image.

  From the above results, the usefulness of the present invention was confirmed.

1 is a schematic configuration diagram illustrating a main part of an image forming apparatus to which an embodiment of the present invention is applied. It is a schematic block diagram which shows the various elements for driving a photoreceptor. It is a schematic block diagram of a charging device. It is a figure which shows arrangement | positioning of a photoconductor, a charger, and a cleaner. It is a graph which shows the rotational speed of a photoreceptor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Cartridge 11 Photoconductor 12 Charging device 13 Developing device 14 Cleaner 20 Exposure device 30 Access device 31 Memory 41 Transfer device 42 Fixing device 43 Conveying belt 44 Paper feed tray 50 Control part

Claims (1)

In an image forming apparatus that forms a toner image, and forms an image on the recording medium by transferring and fixing the toner image on the recording medium.
An image carrier that rotates at a predetermined speed and forms an electrostatic latent image on the surface during rotation;
A rubber contact member that contacts the surface of the image carrier at a position stationary relative to the rotation of the image carrier;
An image forming apparatus comprising: a control unit that temporarily controls a rotation speed of the image carrier when the rotation of the image carrier is started to an initial speed lower than the predetermined speed.

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