JP4923561B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus having a function of performing photoconductor film thickness detection operation.

In recent years, electrophotographic image forming apparatuses have become widespread. In the electrophotographic system, after charging the photoreceptor with a charger, the writing light source emits light to form (exposure) an electrostatic latent image on the photoreceptor, and this is developed with toner in the developer and visualized. In this method, the visible image is transferred from a photosensitive member to a recording medium such as printing paper and output.
In such an electrophotographic image forming apparatus, when used for a long time, the thickness of the photosensitive layer formed on the surface of the photoreceptor is reduced, and the charging ability of the photoreceptor is reduced compared to the initial stage. It is known.
For this reason, some electrophotographic image forming apparatuses have a function of detecting the film thickness of the photosensitive layer in the photosensitive member. This is because if the film thickness of the photosensitive layer can be detected, the use limit can be recognized based on the detection result of the film thickness, or the charge amount of the photoconductor can be controlled in accordance with the change in the film thickness. In the photosensitive layer thickness detection operation, apart from the image forming operation for outputting an image on a recording medium, for example, at a timing prior to the image forming operation, the photosensitive layer in the photosensitive member is charged by a charger, and at that time In general, the integrated value of the applied current is measured, and the film thickness of the photosensitive layer is estimated from the measurement result (see, for example, Patent Document 1).

JP 2001-159838 A

By the way, when performing the film thickness detection operation of the photosensitive layer, since the film thickness of the photosensitive layer is estimated from the integrated value of the current applied to the photosensitive body, the photosensitive body in a charged state is rotated a plurality of times. It is necessary to let
However, in the conventional photosensitive layer thickness detection operation, the toner image formed on the surface of the photoreceptor is not formed on the surface of the photoreceptor, and charged without the toner image formed on the recording medium. The photoconductor is rotated a plurality of times for the film thickness detection operation without performing neutralization for each subsequent photoconductor. For this reason, during the film thickness detection operation, the surface of the photosensitive member and the cleaning member that removes the residue (residual toner, attached contaminants, etc.) on the surface by rubbing with the surface are compared with those during image formation. There is a risk that the coefficient of friction of this will increase.
Such an increase in the coefficient of friction can cause damage to the cleaning member, such as scratches, dents, turn-ups, and the like, and can cause an increase in the degree to which the photoconductor wears due to friction with the cleaning member. Should be suppressed.

  Therefore, the present invention suppresses an increase in the coefficient of friction between the photoconductor and the cleaning member even when performing the film thickness detection operation of the photoconductive layer, thereby causing wear of the photoconductor, damage to the cleaning member, and the like. An object of the present invention is to provide an image forming apparatus capable of avoiding occurrence of the above.

The present invention provides an image forming apparatus devised to achieve the above object, a photoreceptor having a photosensitive layer formed on a surface thereof, a charger for charging the photoreceptor, and the charging after charging by the charger. an exposure device for exposing the surface of the photosensitive member, wherein a developing device for forming a toner image on the surface of the photoconductor, and a cleaning member for removing residues on the surface by rubbing the surface of the photosensitive member, the non The photosensitive layer is rotated a plurality of times in a state where a charging voltage is applied during image formation, and the photosensitive layer is based on an integrated value of current supplied to the charger when the rotating operation is performed. a thickness detecting means for performing a film thickness detection operation for detecting the thickness of the film thickness during the sensing operation or to supply the toner to the surface of the photosensitive member in the developing device before the start of the film thickness detection operation The surface of the photoreceptor and the cleaning Characterized in that it comprises a friction reducing means for reducing the friction coefficient between the members.

  In the image forming apparatus having the above configuration, when the film thickness detecting unit detects the film thickness, the friction reducing unit reduces the friction coefficient between the surface of the photoreceptor and the cleaning member. The friction coefficient can be reduced, for example, by supplying a lubricant between the surface of the photoreceptor and the cleaning member, or by changing the contact pressure between the surface of the photoreceptor and the cleaning member. If such a reduction in the friction coefficient is performed, the respective wear due to the friction between the photosensitive member and the cleaning member is suppressed as compared with the case where the reduction is not performed.

  According to the image forming apparatus of the present invention, it is possible to suppress each wear by reducing the coefficient of friction between the surface of the photoreceptor and the cleaning member. That is, even if it is necessary to rotate the charged photosensitive member a plurality of times in order to detect the film thickness of the photosensitive layer, the cleaning member is reduced by reducing the friction coefficient between the surface of the photosensitive member and the cleaning member. Damage and wear of the photosensitive member can be suppressed.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. The image forming apparatus described here is an electrophotographic system used for a copying machine, a printer apparatus, a facsimile apparatus or the like.

First, a schematic configuration of the image forming apparatus according to the present invention will be described.
FIG. 1 is an explanatory diagram showing a schematic configuration example of an image forming apparatus according to the present invention. As shown in the figure, the electrophotographic image forming apparatus includes a photoreceptor 1, a charger 2, an exposure device 3, a developing device 4, a transfer device 5, a cleaning member 6, a static eliminator 7, A power supply 8 and a control unit 9 are provided.

  The photoreceptor 1 functions as an image carrier, and is, for example, a drum-like member that is rotationally driven at a predetermined peripheral speed. A photosensitive layer (not shown) is formed on the surface (surface on the periphery) of the photoreceptor 1 in order to function as an image carrier.

  The charger 2 is for charging the photosensitive member 1. For example, it is conceivable to use a roller type that contacts the surface of the photosensitive member 1 and uniformly charges (for example, negatively charges) to a predetermined polarity and potential. .

  The exposure device 3 irradiates (scans and exposes) an image-modulated laser beam onto the surface of the photoreceptor 1 charged by the charger 2 to form an electrostatic latent image on the surface of the photoreceptor 1. Is.

  The developing device 4 supplies toner to the surface of the photoconductor 1 to develop the electrostatic latent image formed on the surface of the photoconductor 1 to form a visible toner image. .

  The transfer unit 5 transfers the toner image formed on the surface of the photoreceptor 1 from the photoreceptor 1 to a recording medium such as a printing paper.

  In order to prepare for the next image formation, the cleaning member 6 removes the residue (residual toner, adhering contaminants, etc.) on the surface of the photoreceptor 1 after the transfer of the toner image by the transfer device 5 and the surface thereof. It is a blade-like (plate-like) thing removed by rubbing.

  The static eliminator 7 performs static elimination exposure on the surface of the photoreceptor 1 and erases the electrostatic latent image formed on the surface.

  The power source 8 supplies power to the above-described units, particularly the charger 2 and the developing unit 4 as necessary. Among these, the charger 2 is supplied with a voltage obtained by superimposing an alternating voltage and a direct current voltage in order to charge the photosensitive member 1. Further, a bias voltage is supplied to the developing device 4 in order to supply toner to the photosensitive member 1.

  The control unit 9 performs operation control on the above-described units 1 to 8. The operation control performed by the control unit 9 includes control of power supply performed by the power supply 8. That is, for the power supply performed by the power supply 8, the control unit 9 gives an operation instruction to the power supply 8, sets parameters such as a voltage value and a current value during operation, and monitors the power supply performed by the power supply 8. To do. Through such operation control, the control unit 9 can detect the film thickness of the photosensitive layer in the photoreceptor 1 as described later. Note that the details of the power supply control (parameter setting, etc.) performed by the control unit 9 and the monitoring method thereof may be realized using a known technique in the same manner as in the prior art, and the description thereof is omitted here.

Next, a processing operation example of the image forming apparatus configured as described above will be described.
FIG. 2 is an explanatory diagram showing a specific example of the processing operation in the image forming apparatus according to the present invention.

  Processing operations performed by the image forming apparatus include an image forming operation for transferring a toner image formed on the surface of the photoconductor 1 to a recording medium, and a film thickness detecting operation for detecting the film thickness of the photosensitive layer in the photoconductor 1. There is.

The image forming operation is a processing operation performed in response to a job issuance by a user operation or a job issuance by an instruction from a host device.
When the image forming operation is performed, the charger 2 charges the photosensitive member 1 with a charge having a constant polarity, and the exposure device 3 performs scanning exposure on the surface of the charged photosensitive member 1, and the photosensitive member. An electrostatic latent image is formed on the surface of 1. At this time, the charger 2 applies a DC voltage of about −400 to −1000 V, specifically, for example, −700 V to the photoconductor 1 in order to charge the photoconductor 1. At this time, the bias voltage in the developing device 4 is, for example, about -580V. Therefore, the potential on the surface of the photosensitive member 1 is about −700 V, for example, and the potential difference with the developing device 4 is about 120 V, for example. By utilizing this potential difference, the developing device 4 supplies toner to the surface of the photoreceptor 1 and thereby visualizes the electrostatic latent image.
Then, after the toner image is formed by visualization of the electrostatic latent image, the transfer device 5 applies a charge having the same polarity as that of the electrostatic latent image while the recording medium is in contact with the surface of the photoreceptor 1. The toner image on the surface of the photoreceptor 1 is transferred to a recording medium. As a result, a visible image is formed and output on the recording medium. After that, the cleaning member 6 removes the toner and adhered contaminants remaining on the surface of the photosensitive member 1, and the static eliminator 7 performs the entire surface exposure on the surface of the photosensitive member 1 to erase the residual charge, Prepare for image forming operations.

On the other hand, the film thickness detection operation is a processing operation performed at a predetermined timing set in advance. Examples of the predetermined timing include when the apparatus is activated and before the image forming operation is started. Examples of conditions for performing the film thickness detection operation include a case where the number of rotations of the photoconductor reaches a predetermined number, a case where the number of image formation reaches a predetermined number, and the like.
When performing the film thickness detection operation, the charger 2 charges the photosensitive member 1 with a charge having a constant polarity, as in the case of the image forming operation described above. This charging is performed until the potential on the surface of the photoreceptor 1 is saturated. Therefore, if necessary, charging is performed over a plurality of circumferences of the photoconductor 1 without operating the static eliminator 7 and without performing neutralization of the photoconductor 1 for each circumference. When the charger 2 charges the photosensitive member 1, the controller 9 monitors (detects and measures) the integrated value of the current supplied from the power supply 8 to the charger 2 at that time. Thereby, the film thickness of the photosensitive layer in the photoreceptor 1 is detected. In other words, since the film thickness of the photosensitive layer and the amount of charge stored by charging are unambiguous, if the information regarding the correspondence is specified in advance, the integrated value of the current that flows when charging the photosensitive layer is determined. By measuring, the film thickness of the photosensitive layer can be detected.

  Note that stepwise voltage application can be considered at the beginning of charging of the photosensitive member 1 by the charger 2. That is, a voltage smaller than a predetermined DC applied voltage (for example, −700 V) is applied to the first round of the photoreceptor 1. This is because the charging of the photoreceptor 1 can be ensured if stepwise voltage application is performed. The same applies to the bias voltage in the developing device 4. However, stepwise voltage application may not be performed if the certainty of charging can be ensured from the beginning of the operation.

  Here, when the predetermined timing at which the film thickness detection operation is performed is before the start of the image forming operation, that is, after the film thickness detection operation is performed, the image forming operation is subsequently performed. The detection operation and the image forming operation will be described in more detail.

When there is a job issuance by a user operation or a job issuance by an instruction from a host device, the image forming apparatus first performs a film thickness detection operation before the image forming operation. That is, as shown in FIG. 2A, the control unit 9 causes the charger 2 to apply a stepwise voltage to the photoreceptor 1. The same applies to the bias voltage in the developing device 4. However, the static eliminator 7 is not operated. Then, the transition of the current value performed by the power source 8 at this time is monitored, and the electric charge accumulated in the photosensitive member 1 is calculated by integrating the potential value. Based on the charge amount, the thickness of the photosensitive layer in the photoreceptor 1 is detected. In order to accurately detect the film thickness, it is necessary to accurately measure the amount of charge that can be stored in the photoreceptor 1. Therefore, it is preferable to measure the amount of charge after the photoconductor 1 is rotated a plurality of times.
Further, the film thickness and the current flowing through the charger 2 have a certain degree of correlation. Therefore, as a simpler film thickness detection method, it is possible to detect the film thickness in an estimated manner based on the current value flowing through the charger 2.
When the film thickness of the photosensitive layer is detected in this way, the control unit 9 determines whether or not to perform the subsequent image forming operation based on the detection result, and if it has a parameter variable function, After setting an operation parameter (for example, DC applied voltage value) when performing the image forming operation according to the film thickness detection result, the image forming operation is started. At this time, since the certainty of charging can be sufficiently ensured by the film thickness detection operation already performed, it is not necessary to perform stepwise voltage application.

  By the way, when the film thickness detection operation of the photosensitive layer is performed, an increase in the coefficient of friction between the surface of the photoreceptor 1 and the cleaning member 6 can be a problem as described above. In the film thickness detection operation, unlike the image formation, the toner image is not formed on the surface of the photoconductor 1, and the film thickness detection is not performed on the photoconductor 1 after charging. This is because the photoreceptor 1 is rotated a plurality of times for operation.

  For this reason, the image forming apparatus according to the present embodiment performs the following characteristic processing operation when performing the film thickness detection operation. That is, a process for reducing the coefficient of friction between the surface of the photoreceptor 1 and the cleaning member 6 is performed.

  As a process for reducing the friction coefficient, for example, a process for causing the developing device 4 to supply toner to the surface of the photosensitive member 1 to generate a so-called toner fog may be mentioned. If the toner fog is generated, the toner functions as a lubricant between the surface of the photosensitive member 1 and the cleaning member 6, which makes it possible to reduce the friction coefficient between them.

  It is conceivable that the toner supply to the surface of the photoreceptor 1, that is, the occurrence of toner fog, is performed using the setting of operation parameters by the control unit 9 during the film thickness detection operation. As operation parameters used at this time, a charging parameter in the charger 2 (a parameter for specifying the magnitude of the DC applied voltage by the charger 2) and a development parameter in the developing unit 4 (the magnitude of the bias voltage in the developing unit 4). And the like). That is, the control unit 9 sets the charging parameter in the charger 2 and / or the developing parameter in the developing device 4 so that toner fog is easily generated. That is, the control unit 9 functions as a friction reducing unit in the present invention that reduces the friction coefficient between the surface of the photoreceptor 1 and the cleaning member 6 by setting at least one of the charging parameter and the development parameter. is there.

  Specifically, for example, as shown in FIG. 2B, the charging amount (the magnitude of the DC applied voltage) applied to the photosensitive member 1 by the charger 2 is made smaller than that during image formation (see A in the figure). . If the charge amount is reduced, when the potential polarity of the photosensitive member 1 and the polarity of the toner in the developing device 4 are the same polarity, the potential difference between the photosensitive member 1 and the developing device 4 becomes smaller. As a result, the developing device 4 This is because the transfer of toner (electrostatic attraction) from the toner to the photoreceptor 1 is promoted. That is, the toner is supplied to the surface of the photoreceptor 1 by causing the developing unit 4 to reduce the charge amount.

  For example, as shown in FIG. 2C, the magnitude of the bias voltage applied to the developing device 4 is made larger than that during image formation (see B in the figure). Even when the bias voltage is increased, as in the case where the charge amount is decreased, as long as the potential polarity of the photosensitive member 1 and the polarity of the toner in the developing device 4 are the same polarity, the photosensitive member 1 and the developing device 4 This is because the potential difference between the two becomes small, and the transfer of toner from the developing device 4 to the photoreceptor 1 is promoted. That is, increasing the bias voltage causes the developing device 4 to supply toner to the surface of the photoreceptor 1.

  As described above, if the toner fog is generated by reducing the potential difference between the photosensitive member 1 and the developing device 4, the toner is lubricated between the photosensitive member 1 and the cleaning member 6 due to the occurrence of the toner fog. In addition to being able to reduce the coefficient of friction between them, the potential difference is reduced, so that the carrier (metal magnetic body) of the toner developer is transferred to the photoreceptor 1 side. The suppression of the phenomenon of “bead carry over” can also be expected.

  When the potential polarity of the photosensitive member 1 and the polarity of the toner in the developing device 4 are different, the potential difference between the photosensitive member 1 and the developing device 4 is increased, contrary to the case of the same polarity described above. As described above, the control unit 9 may set either the charging parameter in the charger 2 or the developing parameter in the developing device 4 or both of them. This is because the transfer of toner from the developing device 4 to the photoreceptor 1 is promoted.

  Further, the toner fog can be generated by causing the exposure device 3 to perform exposure together with the parameter setting described above or separately from the parameter setting. That is, for example, as shown in FIG. 2D, the exposure device 3 performs scanning exposure on the surface of the photoreceptor 1 charged by the charger 2 (see C in the figure), and the photoreceptor 1 An electrostatic latent image is formed on the surface. If such an electrostatic latent image is formed, the developing device 4 develops the electrostatic latent image, and as a result, the same state as the occurrence of toner fog is obtained.

  The electrostatic latent image at this time may be uniform on the surface of the photoconductor 1 or may be a band-like image that exists only at a predetermined location on the surface of the photoconductor 1. This means that even when the toner fog is generated by the parameter setting described above, the toner fog may be generated in a band shape. This is because even if it is in a band shape, the toner does not substitute for functioning as a lubricant. When the band-shaped toner fog is generated by parameter setting, for example, as shown in FIG. 2E, the development parameter can be variably set in a plurality of stages within one rotation of the photosensitive member 1. It should be possible (see D in the figure). However, the parameter to be varied may be a charging parameter.

The processing operation for generating the toner fog as described above may be performed during the film thickness detection operation. This is because an increase in the coefficient of friction between the surface of the photoreceptor 1 and the cleaning member 6 during the film thickness detection operation can be a problem.
However, the occurrence of the toner fog does not necessarily have to be performed during the film thickness detection operation, and may be performed before the film thickness detection operation starts. Even if the toner fog is generated before the start of the film thickness detection operation, if the space between the surface of the photoreceptor 1 and the cleaning member 6 is in a so-called toner-rich state, the photosensitive film can be detected even after the film thickness detection operation is started. This is because the toner in a rich state can be expected to function as a lubricant between the surface of the body 1 and the cleaning member 6. Here, the term “before the start of the film thickness detection operation” refers to before the control unit 9 starts monitoring for film thickness detection. For example, when stepwise voltage application is performed to the photosensitive member 1 at the beginning of charging, even if charging is started, if the control unit 9 has not started monitoring, before the film thickness detection operation starts. Equivalent to.

  As described above, when performing the film thickness detection operation, if the toner fog is generated before or during the operation start, the friction coefficient between the surface of the photoreceptor 1 and the cleaning member 6 is reduced. As compared with the case where the reduction is not performed, each wear due to the rubbing between the photosensitive member 1 and the cleaning member 6 is suppressed. Therefore, in order to detect the film thickness of the photosensitive layer in the photosensitive member 1, even if it is necessary to rotate the charged photosensitive member 1 a plurality of times, the surface of the photosensitive member 1 and the cleaning member 6 By reducing the friction coefficient between them, damage to the cleaning member 6, wear of the photosensitive member 1, and the like can be suppressed.

  In addition, as described above, if the toner fog is generated by setting the parameters in the film thickness detection operation or by setting the exposure timing of the exposure unit 3, it is possible to cope with the change only by the control programming executed by the control unit 9. As a result, it is possible to avoid complicating the configuration of the apparatus and increasing the size and cost of the apparatus.

  Here, the case where the toner fog is generated through the operation control by the control unit 9 and the friction coefficient between the surface of the photosensitive member 1 and the cleaning member 6 is thereby reduced is described as an example. The reduction of the coefficient may be realized using another method. As another method, for example, during the film thickness detection operation, it is conceivable that the contact pressure of the cleaning member 6 to the surface of the photoreceptor 1 is made smaller than that during image formation. The contact pressure may be varied using a drive source such as an electromagnetic solenoid. It is possible to reduce the coefficient of friction between the surface of the photosensitive member 1 and the cleaning member 6 by changing the contact pressure. In this case as well, damage to the cleaning member 6 and photosensitivity can be achieved through the reduction of the friction coefficient. Wear of the body 1 can be suppressed. That is, the friction reducing means in the present invention can be realized by a mechanism that varies the contact pressure of the cleaning member 6. Further, it has a function of applying a lubricant such as zinc stearate, and it is possible to realize a friction reducing means by increasing the application amount when detecting the film thickness.

Next, another processing operation example regarding the film thickness detection operation will be described.
3 and 4 are explanatory diagrams showing specific examples of other processing operations in the image forming apparatus according to the present invention.

  As already described, when the film thickness detection operation is performed, the photosensitive member 1 is rotated a plurality of times. That is, a plurality of rotation times of the photoreceptor 1 are required for the film thickness detection operation. Since the time spent for the film thickness detection operation cannot perform image formation, it does not contribute to improvement in image formation productivity in the image forming apparatus. From this, it is conceivable that the control unit 9 sets operation parameters as described below when performing the film thickness detection operation.

  In general, some image forming apparatuses can select productivity for a job when the job is issued to the image forming apparatus. Specifically, as shown in FIG. 3, for example, the productivity of the job is set to 10 sheets / minute or 20 sheets / minute, for example, the type of recording medium or whether or not to form a color image. Some can be switched based on conditions for image formation. When 10 sheets production / minute is selected, the rotational peripheral speed of the photosensitive member 1 is set to 50 mm / s, and when 20 sheets production / minute is selected, the rotational peripheral speed of the photosensitive member 1 is set to 100 mm / s. As described above, the control unit 9 sets operation parameters when performing an image forming operation. Therefore, normally, it is conceivable to set the operation parameters for performing the film thickness detection operation to the same operation parameters as the image forming operation.

However, as described above, since the time for the film thickness detection operation cannot perform image formation, the control unit 9 is the most capable of operating the photoconductor 1 as the operation parameter when performing the film thickness detection operation. Set so that the slow setting is not adopted. Specifically, regardless of whether 10 sheet production / minute or 20 sheet production / minute is selected as the productivity of the job, the operational parameters for performing the film thickness detection operation are as follows: Is set to 100 mm / s, which is the faster rotational peripheral speed at which the photosensitive member 1 can operate.
Moreover, it is preferable not to use the slowest speed when productivity can be switched between three or more speeds. Further, it is most preferable to set the speed at which the photosensitive member 1 can operate at the time of film thickness detection (see E in the figure). Note that “the fastest speed at which the photoconductor 1 can operate” means that the photoconductor 1 can operate, and each unit (charger 2, developer 4, etc.) that operates accompanying the photoconductor 1 operates. The speed that is possible.

  In this way, in an image forming apparatus capable of variable speed control, if the film thickness detection operation is performed at a fast speed (not the slowest speed) that can be selected by the apparatus, the film thickness can be detected. The period during which image formation cannot be performed can be shortened, which is suitable for improving the productivity of image formation. Furthermore, the function that the image forming apparatus has, such as a variable speed control function, is used, and it is possible to cope with the change only by the control programming executed by the control unit 9, so that the apparatus configuration is complicated. It is possible to avoid the increase in the size and cost of the apparatus.

  Further, as described above, the timing of performing such a film thickness detection operation is the image formation operation before the start of the image formation operation, that is, after the film thickness detection operation is performed as shown in FIG. Can be considered. However, on the contrary, as shown in FIG. 4B, the film thickness detection operation may be performed after the image forming operation.

  However, in any case, if the cycle down operation is performed between the respective operations, the productivity is reduced accordingly. The cycle down operation is, for example, an operation for performing static elimination by the static eliminator 7 so as to return the photosensitive member 1 to an uncharged state. That is, the cycle down operation is an operation performed to return the state of the photoreceptor 1 to the initial state between the operations. Further, the cycle down operation includes reducing the rotational speed of a rotating body (for example, a photoreceptor or a rotating polygon mirror of an exposure device) necessary for image formation.

  Therefore, when the image forming operation is performed following the film thickness detecting operation or when the film thickness detecting operation is performed following the image forming operation, the control unit 9 performs each operation as shown in FIG. The image forming operation or the film thickness detecting operation to be continued is started without performing the cycle down operation between the two. As described above, if the film thickness detection operation and the image forming operation are continuously performed without interposing the cycle down operation, the processing time can be shortened by the cycle down operation. This is very suitable for improvement.

  The image forming apparatus according to the present embodiment has been described above as a preferred specific example of the present invention. However, the present invention is not limited to the content, and may be appropriately changed without departing from the gist thereof. Is possible. For example, specific numerical values for parameter setting are not limited to those described in the present embodiment.

1 is an explanatory diagram illustrating a schematic configuration example of an image forming apparatus according to the present invention. FIG. 6 is an explanatory diagram illustrating a specific example of a processing operation in the image forming apparatus according to the present invention. FIG. 6 is an explanatory diagram (part 1) illustrating a specific example of another processing operation in the image forming apparatus according to the present invention. FIG. 11 is an explanatory diagram (part 2) illustrating a specific example of another processing operation in the image forming apparatus according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Charger, 3 ... Exposure device, 4 ... Developing device, 5 ... Transfer device, 6 ... Cleaning member, 7 ... Static eliminator, 8 ... Power supply, 9 ... Control part

Claims (7)

A photoreceptor having a photosensitive layer formed on the surface;
A charger for charging the photoreceptor;
An exposure unit that exposes the surface of the photoreceptor after charging by the charger;
A developer for forming a toner image on the surface of the photoreceptor;
A cleaning member that removes residues on the surface by rubbing against the surface of the photoreceptor;
During non-image formation, the photosensitive member is rotated a plurality of times while a charging voltage is applied, and the photosensitive member is based on an integrated value of the current supplied to the charger when the rotating operation is being performed. A film thickness detection means for performing a film thickness detection operation for detecting the film thickness of the layer;
The film thickness during the sensing operation or the thickness before the start of the detection operation of the toner to the surface of the photosensitive member by causing supplied to the developing device, reducing the friction coefficient between the cleaning member and the surface of the photosensitive member An image forming apparatus comprising: a friction reducing unit. The friction reducing means reduces the amount of charge by the charger to a value smaller than that at the time of image formation in which a toner image formed on the surface of the photoconductor is transferred onto a recording medium. The image forming apparatus according to claim 1, wherein toner is supplied to the image forming apparatus. The friction reducing means increases the amount of voltage applied to the developing device larger than that during image formation in which a toner image formed on the surface of the photosensitive member is transferred onto a recording medium. The image forming apparatus according to claim 1, wherein toner is supplied to the surface of the image forming apparatus. The image forming apparatus according to claim 1, wherein the friction reducing unit causes the developing unit to supply toner to the surface of the photosensitive member by causing the exposure unit to perform exposure. During the film thickness detection operation, the friction reducing means applies the contact pressure of the cleaning member to the surface of the photoconductor from the time of image formation to transfer a toner image formed on the surface of the photoconductor onto a recording medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is also made smaller. The operation control means for rotating the photoconductor at a speed other than the slowest peripheral speed among the different peripheral speeds when the photoconductor can rotate at different peripheral speeds. The image forming apparatus according to 1. When the image forming operation for transferring the toner image onto a recording medium is performed following the film thickness detecting operation, or when the film thickness detecting operation is performed following the image forming operation. The image forming apparatus according to claim 6, wherein a cycle down operation is not performed between the operations.

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