JP2018200349A - Image formation apparatus - Google Patents

Abstract

To speedily form an image of excellent picture quality and to prolong a lifetime of a photoreceptor.SOLUTION: An image formation apparatus comprises: a cylindrical photoreceptor which has a photosensitive layer forming a peripheral surface and is rotated; an electrification device which applies a charging voltage to an electrifier in contact with or close to the peripheral surface so as to electrify the peripheral surface; a transfer device which applies a transfer voltage to a transfer unit close to the peripheral surface so as to transfer a toner image to a transfer body; an execution part which executes image formation processing for forming the toner image on the peripheral surface after electrifying the peripheral surface with the photoreceptor being rotated and then transferring the toner image to the transfer body; an application part which controls the electrification device to apply the electrifier with a first adjustment voltage of the same polarity as a charging voltage and also controls the transfer device to apply, to the transfer unit, a second adjustment voltage of the same polarity as the charging voltage; and an adjustment part which makes the first and second adjustment voltages lower when the photosensitive layer has a first thickness than when the photosensitive layer has a second thickness thicker than that first thickness.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus that transfers a toner image formed on a peripheral surface of a charged photoreceptor to a sheet.

  Conventionally, with a cylindrical photoconductor rotated, after charging the peripheral surface of the photoconductor, a toner image is formed on the peripheral surface, and the toner image is transferred to the paper, thereby transferring the image onto the paper. An image forming apparatus for forming is known.

  Further, in such an image forming apparatus, as shown in FIG. 8, in an initial stage (time t11 to t12) of charging the peripheral surface of the photoconductor, trap carriers are formed in the photosensitive layer forming the peripheral surface of the photoconductor. Therefore, the surface potential of the peripheral surface becomes a potential (V1, V2) lower than the rated potential V3, and it is difficult to charge the surface potential to the rated potential V3 in a short time. Are known. It is also known that when an image forming process is started at the initial stage (time t11 to t12), an image defect such as a ghost occurs in an image formed on a sheet.

  For this reason, generally, before the image forming process is started, a pre-charging process is performed in which the surface potential of the peripheral surface of the photoreceptor reaches the rated potential V3. Specifically, as shown in FIG. 9, after the motor for rotating the photoconductor is turned on (time t21), when the rotation speed of the photoconductor becomes stable (time t22), the pre-charging process starts. Then, as shown in FIG. 10, a charging voltage Vb is applied to a charging roller disposed in contact with or close to the peripheral surface of the photoreceptor.

  As a result, while the photoconductor rotates about three times, the trap carrier contained in the photoconductive layer forming the peripheral surface of the photoconductor moves toward the charging roller and disappears from the photoconductive layer. Thereafter, when the surface potential of the peripheral surface of the photoconductor reaches the rated potential V3 (FIG. 8) (time t23 (FIG. 9)), the pre-charging process is terminated and the image forming process is started.

  However, with this method, there is a possibility that the so-called first print time from when an instruction to form an image on a sheet is input by the user until the sheet on which the image is formed is first output may be long.

  In view of this, Japanese Patent Application Laid-Open No. 2004-228867 proposes that a voltage having the same polarity larger than the transfer voltage used at the time of transfer is applied to the transfer roller used for transferring the toner image after the toner image transfer operation is completed. That is, according to the technique described in Patent Document 1, when the image forming process is started next, the trap carrier has already disappeared from the photosensitive layer that forms the peripheral surface of the photoreceptor, so that the image forming process can be quickly performed. Can be executed. Thereby, the first print time can be shortened.

JP 2010-39168 A

  However, in the technique described in Patent Document 1, the voltage applied to the transfer roller after completion of the toner image transfer operation remains the same polarity voltage larger than the transfer voltage used at the time of transfer. For this reason, the use of the peripheral surface of the photoreceptor increases, and the resistance value of the photosensitive layer decreases as the thickness of the photosensitive layer forming the peripheral surface decreases due to wear of the peripheral surface. The amount of current flowing into the peripheral surface after the transfer operation is finished increases. As a result, there is a possibility that the life of the photoreceptor is shortened as a result of an increase in the load on the peripheral surface.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus capable of rapidly forming an image with a good image quality and extending the life of a photoreceptor.

  An image forming apparatus according to the present invention includes a photosensitive layer that forms a peripheral surface on which a toner image is formed, a rotating cylindrical photosensitive member, and a charger that is disposed in contact with or close to the peripheral surface. A charging device for charging the peripheral surface by applying a charging voltage to the charger, and a transfer device disposed close to the peripheral surface, and applying the transfer voltage to the transfer device to the peripheral surface A transfer device for transferring the toner image formed on the transfer member to the transfer member, and the charging device charging the peripheral surface with the photoconductor rotated, and then forming the toner image on the peripheral surface. An execution unit for executing an image forming process for transferring the toner image to the transfer body by the transfer device; and the charging device in a state where the photoconductor is rotated when the image forming process is not executed. The first polarity of the same polarity as the charging voltage A voltage applying process for applying a regulated voltage to the charger and controlling the transfer device to apply a second adjustment voltage having the same polarity as the charging voltage to the transfer device; and The first adjustment voltage and the second adjustment voltage when the thickness is the first thickness are adjusted to be lower than when the thickness of the photosensitive layer is the second thickness larger than the first thickness. An adjustment unit.

  According to this configuration, the voltage application process is performed when the image forming process is not performed, and the first adjustment voltage having the same polarity as the charging voltage is applied to the charger in a state where the photosensitive member is rotated, and A second adjustment voltage having the same polarity as the charging voltage is applied to the transfer device. For this reason, a trap carrier having a polarity opposite to that of the charging voltage contained in the photosensitive layer is applied to a trap carrier having the same polarity as that of the charging voltage more quickly than when the first adjustment voltage is applied only to the charger without using a transfer device. The trap carrier can be quickly extinguished from the photosensitive layer by moving toward the applied charger and transfer device. In other words, according to this configuration, the image forming process can be started quickly with the photosensitive layer forming the peripheral surface of the photosensitive member being quickly brought into a state that does not include trap carriers and hardly causes image defects such as ghosts. . As a result, an image with good image quality can be quickly formed.

  Further, according to this configuration, the first adjustment voltage and the second adjustment applied to the charger and the transfer unit in the voltage application process as the thickness of the photosensitive layer forming the peripheral surface of the photosensitive member becomes thinner. The voltage is adjusted low. For this reason, even when the resistance value of the photosensitive layer is reduced by increasing the opportunities for using the peripheral surface of the photosensitive member and reducing the thickness of the photosensitive layer forming the peripheral surface due to wear of the peripheral surface. It is possible to suppress an increase in the amount of current flowing into the peripheral surface of the photoreceptor. Thereby, the burden concerning the said surrounding surface can be reduced. As a result, the life of the photoreceptor can be extended.

  The image forming unit includes a plurality of image forming units including the photoconductor, the charging device, and the transfer device, the photoconductor is a replaceable part, and the execution unit includes each of the plurality of image forming units. Performing the target image forming process that is the image forming process using the photosensitive member, the charging device, and the transfer device included in the target unit that is the image forming unit to be controlled. The application unit executes a target voltage application process that is the voltage application process using the photoconductor, the charging device, and the transfer device included in the target unit when the target image forming process is not performed. The adjustment unit is configured to change the first adjustment voltage and the second adjustment voltage used in the target voltage application process when the photoconductor included in the target unit is replaced with a new one. It may be adjusted to a predetermined initial value.

  According to this configuration, in the target voltage application processing in which the target unit is an image forming unit including a new photoconductor after replacement, the initial value of the first adjustment voltage is applied to the charger, and the initial value of the second adjustment voltage. Is applied to the transfer unit. For this reason, by setting the initial values of the first adjustment voltage and the second adjustment voltage according to the amount of trap carriers that can be included in the photosensitive layer forming the peripheral surface of a new photoconductor, the target voltage application is performed. In the processing, trap carriers that can be included in the photosensitive layer forming the peripheral surface of a new photoreceptor can be quickly eliminated.

  The image forming unit further includes a storage device that stores a cumulative value of the number of rotations of the photoconductor included in the image forming unit, and the adjustment unit includes the storage device included in the target unit. It is preferable to calculate the thickness of the photosensitive layer of the photoconductor included in the target unit based on the accumulated value stored in the target unit.

  According to this configuration, the photosensitive member that forms the peripheral surface of the photoconductor included in each image forming unit using the cumulative value of the number of rotations of the photoconductor stored in the storage device included in each image forming unit. The layer thickness can be calculated individually and appropriately.

  Alternatively, the image forming unit further includes a storage device that stores a cumulative value of the rotation time of the photoconductor included in the image forming unit, and the adjustment unit includes the storage device included in the target unit. It is preferable to calculate the thickness of the photosensitive layer of the photoconductor included in the target unit based on the accumulated value stored in the target unit.

  According to this configuration, the photosensitive member that forms the peripheral surface of the photoconductor included in each image forming unit using the accumulated value of the rotation time of the photoconductor stored in the storage device included in each image forming unit. The layer thickness can be calculated individually and appropriately.

  The photosensitive layer may be a single organic photosensitive layer that can be positively charged.

  A single-layer organic photosensitive layer that can be positively charged is trapped from other organic photosensitive layers such as a single-layer or multi-layer organic photosensitive layer that can be negatively charged and a multi-layer organic photosensitive layer that can be positively charged. It has the characteristic that the ratio including a carrier is high. According to this configuration, a relatively large number of trap carriers contained in the photosensitive layer having such characteristics can be quickly reduced, and the life of the photoreceptor provided with the photosensitive layer can be extended.

  The charger is preferably a charging roller arranged in contact with the peripheral surface.

  According to this configuration, the charging roller used as a charger in the image forming process and the voltage application process is disposed in contact with the peripheral surface. For this reason, it is possible to execute an image forming process and a voltage applying process by applying a voltage lower than that of the charger disposed close to the peripheral surface to the charging roller. That is, according to this configuration, it is possible to reduce the power required for the image forming process and the voltage application process.

  According to the present invention, it is possible to provide an image forming apparatus capable of rapidly forming an image with a good image quality and extending the life of the photoreceptor.

1 is a front sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged view around an image forming unit. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus. FIG. It is a conceptual diagram of a voltage application process. It is a figure which shows an example of an applied voltage table. It is a figure which shows an example of the execution result of the conventional precharging process and a voltage application process. It is a figure which shows an example of the execution result of the conventional precharging process and a voltage application process. It is explanatory drawing of the problem in the case of charging the surrounding surface of a photoconductive drum. It is explanatory drawing of the start timing of a pre-charging process. It is a conceptual diagram of the pre-charging process.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a front sectional view of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view of the periphery of the image forming units 20B, 20Y, 20C, and 20M (FIG. 1). FIG. 3 is a block diagram illustrating an electrical configuration of the image forming apparatus 1.

  In the present embodiment, the image forming apparatus 1 primarily transfers (transfers) the toner image to the intermediate transfer belt 8 (transfer body) as shown in FIG. Assume that the image forming apparatus is a color printing type image that is secondarily transferred to the image forming apparatus.

  Specifically, a paper feed cassette 3 is disposed inside the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores printing paper P stacked therein. The sheets P are sent one by one toward the upper left of the sheet feeding cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A first paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The first paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The first paper transport unit 4 receives the paper P sent out from the paper feed cassette 3, and transports the received paper P along the left side surface of the main body 2 to the secondary transfer device 40 vertically above.

  A manual paper feed unit 5 is provided above the paper feed cassette 3 and on the right side opposite to the left side of the main body 2 on which the first paper transport unit 4 is formed. In the manual paper feed unit 5, paper P having a size that cannot be accommodated in the paper feed cassette 3, paper P to be manually fed one by one, such as thick paper and OHP sheet, and the like are placed.

  A second paper transport unit 6 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 6 extends substantially horizontally from the manual paper feed unit 5 to the first paper transport unit 4 above the paper feed cassette 3 and joins the first paper transport unit 4. The second paper transport unit 6 receives the paper P sent out from the manual paper feed unit 5 and transports it to the first paper transport unit 4 substantially horizontally.

  An exposure device 7 is disposed above the second paper transport unit 6. The exposure device 7 is configured to charge the photosensitive drums 21M, 21C under the control of the control device 100 after the peripheral surfaces of the photosensitive drums (photosensitive members) 21M, 21C, 21Y, 21B (FIG. 2), which will be described later, are charged. , 21Y and 21B are irradiated with laser light L based on image data input from the control device 100. Thereby, electrostatic latent images of images indicated by the image data are formed on the peripheral surfaces of the photosensitive drums 21M, 21C, 21Y, and 21B.

  Above the exposure device 7, four (plural) image forming units 20M, 20C, 20Y, and 20B are provided. Above each of the image forming units 20M, 20C, 20Y, 20B, an endless belt-like intermediate transfer belt 8 that rotates clockwise in FIGS. 1 and 2 is provided.

  As shown in FIGS. 1 and 2, the intermediate transfer belt 8 is supported by being wound around a plurality of drive rollers. Each driving roller rotates clockwise in FIGS. 1 and 2 by a rotational driving force applied by a driving motor (not shown). As a result, the intermediate transfer belt 8 also rotates clockwise in FIGS.

  The four image forming units 20M, 20C, 20Y, and 20B are arranged in a line from the upstream side to the downstream side along the circumferential direction of the intermediate transfer belt 8. Each of the four image forming units 20M, 20C, 20Y, and 20B is supplied with toner of each color by a toner supply container and a toner transport device (not shown) corresponding to magenta, cyan, yellow, and black, respectively. Is done.

  The image forming unit 20M forms a magenta toner image on the peripheral surface of the photosensitive drum 21M under the control of the control device 100, and primarily transfers the toner image to the intermediate transfer belt 8. Similarly, the image forming units 20C, 20Y, and 20M respectively form cyan, yellow, and black toner images on the peripheral surfaces of the photosensitive drums 21C, 21Y, and 21B under the control of the control device 100. The toner image is primarily transferred to the intermediate transfer belt 8. In the following description, the identification symbols “M”, “C”, “Y”, and “B” are omitted unless particularly limited.

  Specifically, as shown in FIGS. 2 and 3, the image forming unit 20 includes a photosensitive drum 21, a charging device 22, a developing device 23, a primary transfer device (transfer device) 24, a cleaning device 25, and a storage device 26. It has.

  The photosensitive drum 21 is a cylindrical photosensitive member. The photosensitive drum 21 includes a photosensitive layer that forms a peripheral surface on which a toner image is formed. Specifically, the photosensitive layer is a single-layer organic photosensitive layer that can be charged to a positive polarity (positive polarity). The photosensitive drum 21 is disposed to face the intermediate transfer belt 8. The photosensitive drum 21 is rotated counterclockwise in FIGS. 1 and 2 by a drive motor (not shown) under the control of the control device 100 (FIG. 3). The photosensitive drum 21 is a replaceable part and is configured to be detachable from the main body 2 (FIG. 1) of the image forming apparatus 1.

  The charging device 22 includes a charging roller 221 (charging device). The charging roller 221 is disposed in contact with the peripheral surface of the photosensitive drum 21 and rotates following the photosensitive drum 21. The charging device 22 applies a positive polarity charging voltage Vb to the charging roller 221 under the control of the control device 100 (FIG. 3), thereby charging the peripheral surface of the photosensitive drum 21 substantially uniformly. The charging device 22 applies a negative polarity charging voltage Vb to the charging roller 221 when the peripheral surface of the photosensitive drum 21 is configured to be negatively charged.

  The developing device 23 supplies toner to the electrostatic latent image formed on the peripheral surface of the photoconductive drum 21 under the control of the control device 100 (FIG. 3), so that the static surface is applied to the peripheral surface of the photoconductive drum 21. A toner image corresponding to the electrostatic latent image is formed.

  The primary transfer device 24 includes a primary transfer roller 241 (transfer device). The primary transfer roller 241 is disposed in the vicinity of the peripheral surface of the photosensitive drum 21 so as to sandwich the intermediate transfer belt 8 at a location facing the photosensitive drum 21. The primary transfer device 24 applies a primary transfer voltage Vt1 (transfer voltage) having a polarity opposite to that of the toner to the primary transfer roller 241 under the control of the control device 100 (FIG. 3).

  In this embodiment, it is assumed that the toner has a positive polarity and the primary transfer voltage Vt1 has a negative polarity. That is, it is assumed that the primary transfer voltage Vt1 has a negative polarity opposite to the positive polarity charging voltage Vb. However, not limited to this, the charging voltage Vb may have a negative polarity, the toner may have a negative polarity, and the primary transfer voltage Vt1 may have a positive polarity.

  When the primary transfer voltage Vt1 is applied to the primary transfer roller 241 at a predetermined timing as the intermediate transfer belt 8 rotates, a predetermined current flows between the peripheral surface of the photosensitive drum 21 and the intermediate transfer belt 8. As a result, the toner image formed on the peripheral surface of the photosensitive drum 21 moves toward the primary transfer roller 241. As a result, the toner image formed on the peripheral surface of the photosensitive drum 21 is primarily transferred onto the surface of the intermediate transfer belt 8 (the lower surface in FIG. 2) between the primary transfer roller 241 and the photosensitive drum 21. The In this way, a color toner image is formed on the surface of the intermediate transfer belt 8 by superimposing four color toner images of magenta, cyan, yellow, and black.

  The cleaning device 25 removes the toner remaining on the peripheral surface of the photosensitive drum 21 after the toner image is primarily transferred to the intermediate transfer belt 8. The peripheral surface of the photosensitive drum 21 from which the residual toner is removed by the cleaning device 25 is uniformly charged again by the charging device 22. Thereafter, as described above, a toner image is newly formed on the peripheral surface of the photosensitive drum 21.

  The storage device 26 is configured by a storage device such as a wireless tag (IC chip) that can communicate with the control device 100 and stores information related to the image forming unit 20. Specifically, the storage device 26 stores an accumulated value of the number of rotations of the photosensitive drum 21 included in the image forming unit 20 and an accumulated value of the time of rotation of the photosensitive drum 21 under the control of the control device 100. Etc. are memorized. The storage device 26 stores in advance data used for controlling the image forming unit 20 by the control device 100, such as an applied voltage table described later.

  The secondary transfer device 40 includes a secondary transfer roller 41. The secondary transfer roller 41 is disposed close to the intermediate transfer belt 8 at a location facing the drive roller 8 a that supports the intermediate transfer belt 8. The secondary transfer device 40 applies a secondary transfer voltage having a polarity opposite to that of the toner to the secondary transfer roller 41 under the control of the control device 100 (FIG. 3).

  In this embodiment, it is assumed that the toner has a positive polarity and the secondary transfer voltage has a negative polarity. However, not limited to this, the charging voltage Vb may have a negative polarity, the toner may have a negative polarity, and the secondary transfer voltage may have a positive polarity.

  When the second transfer voltage is applied to the secondary transfer roller 41, a predetermined current flows between the secondary transfer roller 41 and the intermediate transfer belt 8. As a result, the color toner image carried on the surface of the intermediate transfer belt 8 moves toward the secondary transfer roller 41. As a result, the color toner image is secondarily transferred onto the surface of the paper P (the surface on the intermediate transfer belt 8 side) sent between the secondary transfer roller 41 and the intermediate transfer belt 8 by the first paper transport unit 4. Is done. The secondary transfer roller 41 conveys the paper P after the color toner image is transferred upward.

  A fixing unit 10 is provided above the secondary transfer device 40. The fixing unit 10 fixes the color toner image secondarily transferred to the paper P onto the paper P by heating and pressurizing the paper P under the control of the control device 100 (FIG. 3).

  A branch portion 11 is provided above the fixing portion 10. The sheet P discharged from the fixing unit 10 is discharged from the branching unit 11 to the sheet discharging unit 12 provided on the upper part of the image forming apparatus 1 when double-sided printing is not performed. A discharge port portion through which the paper P is discharged from the branching unit 11 toward the paper discharge unit 12 functions as a switchback unit 13. When performing duplex printing, the switchback unit 13 switches the transport direction of the paper P discharged from the fixing unit 10. Then, the paper P is sent downward through the branching unit 11, the left side of the fixing unit 10, and the left side of the secondary transfer device 40, and again passes through the first paper transport unit 4 to the secondary transfer device 40. Sent.

  In the circumferential direction of the intermediate transfer belt 8, a cleaning device 9 is provided on the upstream side of the image forming unit 20M. After the color toner image carried on the surface of the intermediate transfer belt 8 is secondarily transferred to the paper P, the cleaning device 9 is a toner remaining on the surface of the intermediate transfer belt 8 under the control of the control device 100 (FIG. 3). Recover.

  The image forming apparatus 1 further includes an operation unit 70, a communication unit 80, a storage unit 90, and a control device 100 (FIG. 3).

  The operation unit 70 is configured to allow input of various operation instructions by the user. Specifically, the operation unit 70 includes a display unit (not shown) such as a liquid crystal display and an operation key unit (not shown). The operation key unit includes various keys such as a numeric keypad for inputting numerical values and symbols and a direction key for moving a cursor displayed on the display unit.

  The communication unit 80 is connected to a network (not shown) and transmits / receives various data to / from an external device such as a personal computer connected to the network. For example, the communication unit 80 receives data indicating a print job (hereinafter abbreviated as “print job”) input by the user in the external apparatus via the network, and outputs the received print job to the control apparatus 100. .

  The print job includes image data representing an image to be formed on the paper P, printing conditions such as the number of paper P to be output (printed) and the type of the paper P (eg, plain paper, cardboard, OHP sheet, etc.). Data to be represented (hereinafter abbreviated as printing conditions) is included.

  The storage unit 90 is configured by a storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive). In the storage unit 90, data used for controlling the exposure device 7, the secondary transfer device 40, the cleaning device 9, the fixing unit 10, the operation unit 70, and the communication unit 80 by the control device 100 is stored in advance.

  The control device 100 controls the entire image forming apparatus 1. The control device 100 is composed of a microcomputer provided with a CPU, RAM, ROM and the like. The control device 100 functions as, for example, the execution unit 101, the application unit 102, and the adjustment unit 103.

  When a print job is input to the control apparatus 100 by the communication unit 80, the execution unit 101 controls each of the four image forming units 20M, 20C, 20Y, and 20B according to the print conditions included in the print job. Thus, an image forming process (target image forming process) using the photosensitive drum 21, the charging device 22, and the primary transfer device 24 included in the image forming unit 20 to be controlled (hereinafter referred to as a target unit) is executed.

  Specifically, when a print job is input to the control device 100 by the communication unit 80, the execution unit 101 in the rotation direction of the intermediate transfer belt 8 among the four image forming units 20M, 20C, 20Y, and 20B. The image forming unit 20M arranged on the most upstream side is a control target. The execution unit 101 executes an image forming process using the photosensitive drum 21M, the charging device 22M, and the primary transfer device 24M included in the image forming unit 20M that is the target unit.

  When the image forming unit 20M is started as the target unit, the execution unit 101 controls a drive motor (not shown) to rotate the photosensitive drum 21M. The execution unit 101 controls the charging device 22M to apply the charging voltage Vb to the charging roller 221M, thereby charging the peripheral surface of the photosensitive drum 21M.

  Thereafter, the execution unit 101 controls the exposure device 7 to form an electrostatic latent image represented by the image data included in the print job on the circumferential surface of the photosensitive drum 21M. Thereafter, the execution unit 101 controls the developing device 23M to supply magenta toner to the electrostatic latent image, and forms a magenta toner image corresponding to the electrostatic latent image on the peripheral surface. Then, the execution unit 101 controls the primary transfer device 24M to apply the primary transfer voltage Vt1 to the primary transfer roller 241 so that the magenta toner image is primarily transferred to the intermediate transfer belt 8.

  Thereafter, similarly, the execution unit 101 sequentially controls the image forming units 20C, 20Y, and 20B, sets the image forming unit 20C as the target unit, and sets the image forming unit 20Y as the target unit. , And an image forming process using the image forming unit 20B as a target unit.

  The execution unit 101 includes at least one of an accumulated value of the number of rotations of the photosensitive drum 21 and an accumulated value of the time of rotation of the photosensitive drum 21 in the image forming process in which each image forming unit 20 is the target unit. One accumulated value is stored in the storage device 26 (FIG. 3) provided in the target unit.

  When the execution unit 101 completes the image forming process for each of the four image forming units 20M, 20C, 20Y, and 20B, the secondary transfer device 40 and the fixing unit 10 (FIG. 1) are controlled. Then, the toner image primarily transferred to the intermediate transfer belt 8 is secondarily transferred to the paper P, and the toner image is fixed on the paper P. Then, the paper P is discharged to the paper discharge unit 12. Further, the execution unit 101 controls the cleaning device 9 to collect the toner remaining on the intermediate transfer belt 8 after the secondary transfer by the secondary transfer device 40.

  When the image forming process using the photosensitive drum 21, the charging device 22, and the primary transfer device 24 included in the target unit is not performed, the applying unit 102 includes the photosensitive drum 21 and the charging device included in the target unit. 22 and a voltage application process (target voltage application process) using the primary transfer device 24 are executed.

  Specifically, the application unit 102 uses the photosensitive drum 21M, the charging device 22M, and the primary transfer device 24M included in the target unit when the image forming process using the image forming unit 20M as the target unit is not executed. The applied voltage application process is executed. The time when the image forming process with the image forming unit 20M as the target unit is not executed means a period from the end of the control of the primary transfer device 24M to the next control of the charging device 22M.

  FIG. 4 is a conceptual diagram of the voltage application process. When the voltage application process using the photoconductor drum 21M, the charging device 22M, and the primary transfer device 24M is started with the image forming unit 20M as a target unit, the applying unit 102 controls a drive motor (not shown) to control the photoconductor drum. 21M is rotated. Then, as shown in FIG. 4, the application unit 102 controls the charging device 22M to apply the first adjustment voltage Vb1 having the same polarity as the charging voltage Vb to the charging roller 221M, and the primary transfer device 24M. The second adjustment voltage Vb2 having the same polarity as the charging voltage Vb is applied to the primary transfer roller 241M.

  Similarly, the application unit 102 executes voltage application processing using the photosensitive drum 21C, the charging device 22C, and the primary transfer device 24C when the image forming processing with the image forming unit 20C as the target unit is not executed. To do. The application unit 102 executes voltage application processing using the photosensitive drum 21Y, the charging device 22Y, and the primary transfer device 24Y when the image forming processing using the image forming unit 20Y as a target unit is not executed. The application unit 102 executes voltage application processing using the photosensitive drum 21B, the charging device 22B, and the primary transfer device 24B when the image forming processing with the image forming unit 20B as the target unit is not executed.

  The application unit 102 is stored in the storage device 26 (FIG. 3) included in the target unit in the voltage application process using the photosensitive drum 21, the charging device 22, and the primary transfer device 24 included in each image forming unit 20. The cumulative value of the number of times the photosensitive drum 21 has been rotated and the cumulative value of the time that the photosensitive drum 21 has been rotated are updated.

  The adjusting unit 103 uses the first adjustment voltage Vb1 and the second adjustment voltage Vb2 when the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 is the first thickness, and the thickness of the photosensitive layer is the first. Adjust lower than when the second thickness is greater than one thickness.

  Specifically, the adjustment unit 103 uses the applied voltage table Tb stored in advance in the storage device 26 (FIG. 3) of the target unit, and the photosensitive drum 21 and the charging device in which the application unit 102 is included in the target unit. The first adjustment voltage Vb1 and the second adjustment voltage Vb2 used in the voltage application process are determined immediately before the voltage application process using the 22 and the primary transfer device 24 is executed.

  FIG. 5 is a diagram illustrating an example of the applied voltage table Tb. As shown in FIG. 5, the applied voltage table Tb includes the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 included in the target unit (for example, mid-life 2 (20 μm)) and the target during the image forming process. A charging voltage Vb (for example, +700 V) to be applied to the charging roller 221 by the charging device 22 included in the unit, a primary transfer voltage Vt1 (for example, -1200 V) to be applied to the primary transfer roller 241 by the primary transfer device 24, and voltage application processing. Sometimes, the charging device 22 included in the target unit applies the charging roller 221 with the first adjustment voltage Vb1 having the same polarity as the charging voltage Vb (for example, + 700V) and the primary transfer device 24 applies the charging to the primary transfer roller 241. This is information that associates the voltage Vb with the second adjustment voltage Vb2 (for example, +700 V) having the same polarity.

  In the applied voltage table Tb, the charging voltage Vb (for example, +1200 V) associated with the thickness of the photosensitive layer (for example, 34 μm) that forms the peripheral surface of the new photosensitive drum 21 included in the target unit. The primary transfer voltage Vt1 (eg: -1200V), the first adjustment voltage Vb1 (eg: + 1200V) and the second adjustment voltage Vb2 (eg: + 1200V) are the charging voltage Vb, the primary transfer voltage Vt1, and the first adjustment, respectively. The initial values of the voltage Vb1 and the second adjustment voltage Vb2 are shown.

  Further, as shown in FIG. 5, in the applied voltage table Tb, the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 included in the target unit is the first thickness (eg, middle life 1 (30 μm)). When the first adjustment voltage Vb1 (e.g. + 1050V) and the second adjustment voltage Vb2 (e.g. + 1050V) are equal to each other, the photosensitive layer has a second thickness (e.g. new article (34 [mu] m) thicker than the first thickness. )) Is set lower than the first adjustment voltage Vb1 (example: +1200 V) and the second adjustment voltage Vb2 (example: +1200 V).

  When the adjustment unit 103 determines the first adjustment voltage Vb1 and the second adjustment voltage Vb2 used in the voltage application process using the photosensitive drum 21, the charging device 22, and the primary transfer device 24 included in the target unit, first, the adjustment unit 103 Based on the at least one cumulative value stored in the storage device 26 included in the unit, the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 included in the target unit is calculated.

  For example, when the accumulated value of the number of rotations of the photosensitive drum 21 is stored in the storage device 26 included in the target unit, the adjustment unit 103 uses the accumulated value stored in the storage device 26 and a predetermined first value. The product with the coefficient is calculated as the thickness (for example, 30 μm) of the photosensitive layer forming the peripheral surface of the photosensitive drum 21. Similarly, when the accumulated value of the rotation time of the photosensitive drum 21 is stored in the storage device 26 included in the target unit, the adjustment unit 103 and the accumulated value stored in the storage device 26 and a predetermined value The product with the second coefficient is calculated as the thickness (for example, 20 μm) of the photosensitive layer forming the peripheral surface of the photosensitive drum 21.

  In this way, the adjustment unit 103 stores the accumulated value of the number of times the photosensitive drum 21 has been rotated and the accumulated value of the time that the photosensitive drum 21 has been rotated, which are stored in the storage device 26 included in each image forming unit 20. Among these, the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 included in each image forming unit 20 can be calculated appropriately using at least one cumulative value.

  The adjusting unit 103 then calculates the thickness of the photosensitive layer that forms the calculated peripheral surface of the photosensitive drum 21 in the applied voltage table Tb (FIG. 5) stored in the storage device 26 (FIG. 3) of the target unit. The first adjustment voltage Vb1 and the second adjustment voltage Vb2 that are used in the voltage application process using the first adjustment voltage Vb1 (example: +1050 V) and the second adjustment voltage Vb2 (example: +1050 V) associated with (example: 30 μm). Determine as.

  In addition, the adjustment unit 103 stores, in the storage device 26 included in the target unit, neither an accumulated value of the number of times that the photosensitive drum 21 has been rotated nor an accumulated value of the time that the photosensitive drum 21 has been rotated. It is determined that the photosensitive drum 21 included in the target unit has been replaced with a new one. In this case, the adjusting unit 103 determines the thickness of the photosensitive layer that forms the peripheral surface of the new photosensitive drum 21 in the applied voltage table Tb (FIG. 5) stored in the storage device 26 (FIG. 3) of the target unit. (Example: 34 μm) First adjustment voltage Vb1 and second adjustment voltage Vb2 initial values (Vb1 initial value: +1200 V, Vb2 initial value: +1200 V) associated with the first adjustment voltage Vb1 and the second adjustment voltage Vb2 The voltage Vb1 and the second adjustment voltage Vb2 are determined.

  In the image forming process, the execution unit 101 sets the charging voltage Vb and the primary transfer voltage Vt1 applied to the charging roller 221 and the primary transfer roller 241 to the storage device 26 ( This is determined using the applied voltage table Tb (FIG. 5) stored in FIG.

  Specifically, the execution unit 101 calculates the thickness of the photosensitive layer that forms the peripheral surface of the photosensitive drum 21 included in the target unit, just like the adjustment unit 103, immediately before executing the image forming process. And the execution part 101 is the applied voltage table Tb (FIG. 5) memorize | stored in the memory | storage device 26 (FIG. 3) of an object unit, and the charging voltage matched with the calculated thickness (example: 30 micrometers). Vb (example: +1050 V) and primary transfer voltage Vt1 (example: -1200 V) are determined as the charging voltage Vb and primary transfer voltage Vt1 applied to the charging roller 221 and the primary transfer roller 241 respectively in the image forming process.

  When the execution unit 101 stores neither the accumulated value of the number of rotations of the photosensitive drum 21 nor the accumulated value of the time of rotation of the photosensitive drum 21 in the storage device 26 included in the target unit, In the applied voltage table Tb (FIG. 5) stored in the storage device 26 (FIG. 3) of the target unit, it is associated with the thickness (eg 34 μm) of the photosensitive layer forming the peripheral surface of the new photosensitive drum 21. The initial values of the charging voltage Vb and the primary transfer voltage Vt1 (the initial value of Vb: +1200 V, the initial value of Vt1: -1200 V) are applied to the charging roller 221 and the primary transfer roller 241 respectively in the image forming process. The charging voltage Vb and the primary transfer voltage Vt1 are determined.

  However, the execution unit 101 uses the charging voltage Vb and the primary transfer voltage Vt1 applied to the charging roller 221 and the primary transfer roller 241 in the image forming process, respectively, to form the photosensitive layer that forms the circumferential surface of the photosensitive drum 21. It may be set to a fixed value not related to the thickness of the target unit and stored in advance in the storage device 26 (FIG. 3) or the storage unit 9 of the target unit.

  That is, according to the configuration of the present embodiment, when the image forming process is not executed, the voltage application process is performed, and the first adjustment voltage having the same polarity as the charging voltage Vb in the state where the photosensitive drum 21 is rotated. Vb1 is applied to the charging roller 221 and a second adjustment voltage Vb2 having the same polarity as the charging voltage Vb is applied to the primary transfer roller 241. For this reason, the trap carrier having the opposite polarity to the charging voltage Vb included in the photosensitive layer is more rapidly charged than the charging voltage Vb without applying the primary transfer roller 241 and applying the first adjustment voltage Vb1 only to the charging roller 221. The trap carrier can be quickly extinguished from the photosensitive layer by moving toward the charging roller 221 and the primary transfer roller 241 to which a voltage of the same polarity is applied. In other words, according to the configuration of the present embodiment, the photosensitive layer forming the peripheral surface of the photosensitive drum 21 is quickly brought into a state that does not include a trap carrier and is unlikely to cause image defects such as ghosts. Can start quickly. As a result, an image with good image quality can be quickly formed.

  Further, according to the configuration of the present embodiment, as the photosensitive layer forming the peripheral surface of the photosensitive drum 21 becomes thinner, it is applied to the charging roller 221 and the primary transfer roller 241 in the voltage application process. The first adjustment voltage Vb1 and the second adjustment voltage Vb2 are adjusted low. For this reason, the use opportunity of the peripheral surface of the photosensitive drum 21 is increased, and the resistance value of the photosensitive layer is reduced by reducing the thickness of the photosensitive layer forming the peripheral surface due to wear of the peripheral surface. Even in this case, an increase in the amount of current flowing into the peripheral surface of the photosensitive drum 21 can be suppressed. Thereby, the burden concerning the said surrounding surface can be reduced. As a result, the life of the photosensitive drum 21 can be extended.

  In addition, according to the configuration of the present embodiment, in the voltage application processing in which the image forming unit 20 including the new photosensitive drum 21 after replacement is the target unit, the initial value of the first adjustment voltage Vb1 (example: +1200 V (FIG. 5)) is applied to the charging roller 221, and an initial value (eg, +1200 V (FIG. 5)) of the second adjustment voltage Vb2 is applied to the primary transfer roller 241. For this reason, by setting the initial values of the first adjustment voltage Vb1 and the second adjustment voltage Vb2 according to the amount of trap carriers that can be included in the photosensitive layer forming the peripheral surface of the new photosensitive drum 21, In the voltage application process, trap carriers that can be included in the photosensitive layer forming the peripheral surface of the new photosensitive drum 21 can be quickly eliminated.

  Conventionally, a single-layer organic photosensitive layer that can form a peripheral surface of the photosensitive drum 21 of the present embodiment and can be charged positively has a single-layer or laminated organic photosensitive layer or positive electrode that can be negatively charged. It is known that it has a characteristic that the ratio including trap carriers is higher than other organic photosensitive layers such as a laminated organic photosensitive layer that can be electrically charged. According to the configuration of the present embodiment, a relatively large number of trap carriers contained in the photosensitive layer having such characteristics can be quickly reduced, and the life of the photosensitive drum 21 including the photosensitive layer can be extended. Can do.

  Further, according to the configuration of the present embodiment, the charging roller 221 used in the image forming process and the voltage application process is disposed in contact with the peripheral surface of the photosensitive drum 21. For this reason, instead of the charging roller 221, a voltage lower than that in the case where a charging device other than the charging roller 221 is disposed in the vicinity of the peripheral surface is applied to the charging roller 221 to perform image forming processing. And a voltage application process. That is, according to the configuration of the present embodiment, the power required for the image forming process and the voltage application process can be reduced.

  Hereinafter, execution results of the conventional precharging process and the voltage application process according to the present invention will be described. 6 and 7 are diagrams showing examples of execution results of the conventional precharging process and voltage application process. In the following description, it is assumed that the thickness of the photosensitive layer forming the peripheral surface of the new photosensitive drum 21 is 34 μm.

  FIG. 6 shows that when one image forming unit 20 is a target unit and the thickness of the peripheral surface of the photosensitive drum 21 of the target unit is worn down to 30 μm, + 500V before the charging process in the target unit as in the conventional case. The result of having performed the pre-charging process which applies the charging voltage Vb is shown. Further, only after the completion of the entire image forming process in the target unit, the result of executing the voltage application process using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +900 V, and the first adjustment voltage Vb1 and the second adjustment voltage of +1050 V The result of having performed the voltage application process using Vb2 is shown. Moreover, the result of having performed the voltage application process using the 1st adjustment voltage Vb1 of + 900V and the 2nd adjustment voltage Vb2 at the time of a paper gap is shown.

  Here, the entire image forming process in the target unit is all that is performed in the target unit when a print job instructing to form an image on each of a plurality of sheets P is input to the control device 100 ( The same number of image forming processes as a plurality of sheets) is shown. The charging process in the target unit indicates a process of charging the peripheral surface of the photosensitive drum 21 by the charging device 22 that is first performed in the entire image forming process in the target unit. The time between sheets indicates a period from the end of one image forming process included in all image forming processes in the target unit to the start of the next one image forming process.

  As shown in the first line of FIG. 6, when the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 is worn down to 30 μm, a charging voltage Vb of +500 V is applied before the charging process in the target unit. It has been found that in order to obtain an image with good image quality free from ghosts by executing the pre-charging process, it is necessary to rotate the photosensitive drum 21 four or more times in the pre-charging process.

  On the other hand, as shown in the second row of FIG. 6, the voltage application process is executed by using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +900 V only after the completion of the entire image forming process in the target unit. It has been found that in order to obtain an image with good image quality free from ghosting, it is necessary to rotate the photosensitive drum 21 three or more times in the voltage application process.

  Further, as shown in the third row of FIG. 6, by performing the voltage application process using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +1050 V only after the completion of the entire image forming process in the target unit. It has been found that in order to obtain an image with good image quality free from ghosting, it is necessary to rotate the photosensitive drum 21 two or more times in the voltage application process.

  In addition, as shown in the fourth line of FIG. 6, no ghost is generated by performing the voltage application process using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +900 V during the interval between sheets. It has been found that in order to obtain an image with high image quality, the photosensitive drum 21 may be rotated one or more times in the voltage application process.

  That is, by executing the voltage application process from the execution result shown in the first row and the execution results shown in the second and subsequent rows in FIG. 6, the ghost can be performed more quickly than the conventional precharging process. It was found that an image with a good image quality in which no occurrence occurred can be obtained. Further, from the execution results shown in the second and third rows in FIG. 6, the higher the first adjustment voltage Vb1 and the second adjustment voltage Vb2 used in the voltage application process, the faster the ghost does not occur. It was found that an image with good image quality can be obtained. Further, from the execution results shown in the third and fourth lines in FIG. 6, it is found that the more the number of execution opportunities of the voltage application process, the quicker the image with good image quality in which no ghost is generated. It was.

  FIG. 7 shows a case where one image forming unit 20 is a target unit, and when the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 of the target unit is further worn down to 20 μm, A result of executing a pre-charging process of applying a charging voltage Vb of +500 V before the charging process is shown. Further, only after the completion of all the image forming processes in the target unit, the result of executing the voltage application process using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +600 V, and the first adjustment voltage Vb1 and the second adjustment voltage of +700 V The result of having performed the voltage application process using Vb2 is shown. In addition, the result of executing the voltage application process using the first adjustment voltage Vb1 and the second adjustment voltage Vb2 of +700 V during the sheet interval is shown.

  From the execution results shown in the first row and the execution results shown in the second and subsequent rows in FIG. 7, the ghost is generated more quickly than the conventional pre-charging process by executing the voltage application process. It was found that an image with good image quality that does not occur can be obtained. Further, from the execution results shown in the second and third rows in FIG. 7, the higher the first adjustment voltage Vb1 and the second adjustment voltage Vb2 used in the voltage application process, the faster the ghost is not generated. It was found that an image with good image quality can be obtained.

  Further, from the execution results shown in the third row of FIG. 6 and the third row of FIG. 7, the thinner the photosensitive layer forming the peripheral surface of the photosensitive drum 21, the better the ghost is not generated. It has been found that the first adjustment voltage Vb1 and the second adjustment voltage Vb2 used in the voltage application process, which are necessary for quickly obtaining an image having an image quality, may be low.

  In addition, the said embodiment is only the illustration of embodiment which concerns on this invention, and is not the meaning which limits this invention to the said embodiment. For example, the following modified embodiment may be used.

  (1) Instead of the charging roller 221 (FIG. 2), the charging device 22 is applied with a voltage higher than that of the charging roller 221 that is disposed in close proximity without contacting the peripheral surface of the photosensitive drum 21. A corona discharge charger may be provided.

  (2) The photosensitive layer forming the peripheral surface of the photosensitive drum 21 may be a laminated organic photosensitive layer that can be charged to a positive polarity, a single-layer or laminated organic photosensitive layer that can be charged to a negative polarity, or the like. .

  (3) The thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 determined in the applied voltage table Tb is set to the four thicknesses shown in FIG. 5 (example: 34 μm, 30 μm, 20 μm, 15 μm). Not exclusively. In the applied voltage table Tb, the thickness of the photosensitive layer forming the peripheral surface of one or more photosensitive drums 21 is associated with the charging voltage Vb, the primary transfer voltage Vt1, the first adjustment voltage Vb1, and the second adjustment voltage Vb2. May be. Further, in the applied voltage table Tb, the thickness of the photosensitive layer forming the peripheral surface of the photosensitive drum 21 associated with the charging voltage Vb, the primary transfer voltage Vt1, the first adjustment voltage Vb1, and the second adjustment voltage Vb2, respectively. You may make it have a predetermined range (Example: 34 micrometers-30 micrometers, 30 micrometers-20 micrometers, 20 micrometers-15 micrometers, less than 15 micrometers).

  (4) Each image forming unit 20 may not include the storage device 26 (FIG. 3). Accordingly, the cumulative value of the number of times that the execution unit 101 and the adjustment unit 103 have rotated the photosensitive drum 21 of each image forming unit 20 and the cumulative value of the time that the photosensitive drum 21 of each image forming unit 20 has rotated. Of these, at least one cumulative value may be stored in the storage unit 90 (FIG. 3). However, in this case, when the photosensitive drum 21 of each image forming unit 20 is replaced, the at least one of the photosensitive drums 21 stored in the storage unit 90 (FIG. 3) is stored. The accumulated value must be deleted (reset). Further, the applied voltage table Tb (FIG. 5) stored in advance in the storage device 26 of each image forming unit 20 may be stored in advance in the storage unit 90 (FIG. 3).

  (5) In the above embodiment and modified embodiments, the image forming apparatus 1 is a color printing type image forming apparatus that transfers the toner image onto the paper P using the intermediate transfer belt 8. However, the present invention is not limited to this, and the image forming apparatus according to the present invention does not include the three image forming units 20Y, 20C, and 20M (FIGS. 1 and 2), and the image forming unit 20B (FIGS. 1 and 2). A monochrome printing type image forming apparatus that transfers the black toner image onto the paper P using the intermediate transfer belt 8.

  Alternatively, the image forming apparatus according to the present invention does not include the intermediate transfer belt 8 (FIGS. 1 and 2) and the three image forming units 20Y, 20C, and 20M (FIGS. 1 and 2), and the image forming unit 20B. The image forming apparatus may be a monochrome printing type that includes only (FIGS. 1 and 2) and transfers the toner image directly to the paper P by the primary transfer device 24B.

1 Image forming device 8 Intermediate transfer belt (transfer body)
20, 20B, 20C, 20M, 20Y Image forming unit 21, 21B, 21C, 21M, 21Y Photosensitive drum (photosensitive member)
22, 22B, 22C, 22M, 22Y Charging device 23, 23B, 23C, 23M, 23Y Developing device 24, 24B, 24C, 24M, 24Y Primary transfer device (transfer device)
26 Storage Device 101 Execution Unit 102 Application Unit 103 Adjustment Unit 221, 221B, 221C, 221M, 221Y Charging roller (charger)
241, 241B, 241C, 241M, 241Y Primary transfer roller (transfer device)
Vb Charging voltage Vb1 First adjustment voltage Vb2 Second adjustment voltage Vt1 Primary transfer voltage

Claims (6)

A cylindrical photoreceptor that includes a photosensitive layer that forms a peripheral surface on which a toner image is formed, and is rotated;
A charging device comprising a charger disposed in contact with or in proximity to the peripheral surface, and charging the peripheral surface by applying a charging voltage to the charger;
A transfer device including a transfer device disposed close to the peripheral surface, and applying a transfer voltage to the transfer device to transfer the toner image formed on the peripheral surface to a transfer member;
Image formation in which the peripheral surface is charged by the charging device while the photosensitive member is rotated, and then the toner image is formed on the peripheral surface, and the toner image is transferred to the transfer member by the transfer device. An execution unit for executing processing;
When the image forming process is not being performed, the charging device is controlled to apply a first adjustment voltage having the same polarity as the charging voltage to the charger while the photoconductor is rotated, and An application unit that controls the transfer device to perform a voltage application process to apply a second adjustment voltage having the same polarity as the charging voltage to the transfer unit;
The first adjustment voltage and the second adjustment voltage when the thickness of the photosensitive layer is the first thickness are greater than when the thickness of the photosensitive layer is the second thickness greater than the first thickness. An adjustment unit that adjusts the
An image forming apparatus comprising: A plurality of image forming units including the photoconductor, the charging device, and the transfer device;
The photoreceptor is a replaceable part,
The execution unit uses each of the plurality of image forming units as a control target, and uses the photosensitive member, the charging device, and the transfer device included in the target unit that is the image forming unit to be controlled. Executing the target image forming process as the image forming process;
The application unit performs a target voltage application process that is the voltage application process using the photoconductor, the charging device, and the transfer device included in the target unit when the target image forming process is not performed. And
The adjustment unit adjusts the first adjustment voltage and the second adjustment voltage used in the target voltage application process to predetermined initial values when the photoconductor included in the target unit is replaced with a new one. The image forming apparatus according to claim 1. The image forming unit further includes a storage device that stores a cumulative value of the number of rotations of the photoconductor included in the image forming unit,
The said adjustment part calculates the thickness of the said photosensitive layer of the said photoreceptor contained in the said target unit based on the said cumulative value memorize | stored in the said memory | storage device contained in the said target unit. Image forming apparatus. The image forming unit further includes a storage device that stores a cumulative value of a time during which the photoconductor included in the image forming unit is rotated.
The said adjustment part calculates the thickness of the said photosensitive layer of the said photoreceptor contained in the said target unit based on the said cumulative value memorize | stored in the said memory | storage device contained in the said target unit. Image forming apparatus. The image forming apparatus according to claim 1, wherein the photosensitive layer is a single-layer organic photosensitive layer that can be positively charged. The image forming apparatus according to claim 1, wherein the charger is a charging roller disposed in contact with the peripheral surface.

Images