JP2022036798A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can reliably prevent an abnormal discharge phenomenon from an electrifying roller to an image carrier and thereby can effectively prevent an image defect.SOLUTION: An image forming apparatus electrifies an image carrier to a predetermined potential with an electrifying roller, exposes the image carrier electrified to the predetermined potential to form a latent image, develops the latent image formed on the image carrier with toner to form a toner image, electrostatically transfers the toner image formed on the image carrier to a sheet material with a transfer unit, and eliminates a residual potential remaining on the image carrier after the transfer with a static elimination unit. The image forming apparatus comprises a process control unit that, during an image formation process operation, controls the image formation process operation with predetermined control conditions. The process control unit performs switching control of switching between a static elimination operation for actuating the static elimination unit and a non-static elimination operation for not actuating the static elimination unit, and when switching the static elimination unit to the non-static elimination operation, changes a control condition related to a transfer process in the predetermined control conditions.SELECTED DRAWING: Figure 6

Description

The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a multifunction device, a printer, and a facsimile machine, and particularly to an image forming apparatus including a charging roller and a static elimination unit.

In an electrophotographic image forming apparatus, an image carrier is usually charged to a predetermined potential by a charging roller, and the image carrier charged to the predetermined potential is exposed to form a latent image, and the image carrier is formed on the image carrier. The latent image is visualized with toner to form a toner image, the toner image formed on the image carrier is electrostatically transferred to the sheet material by the transfer unit, and the residual potential remaining on the image carrier after transfer is removed by the static eliminator. Eliminate static electricity. Conventionally, such an image forming apparatus has the following inconveniences.

That is, during the operation of the image forming process, an abnormal discharge phenomenon from the charging roller to the image carrier may occur in the vicinity of the upstream side and the downstream side of the transfer nip portion between the charging roller and the image carrier. Then, in the image formed on the subsequent sheet material, discharge streaks (random white streaks) appear, and image defects occur. This is particularly remarkable under a predetermined environment (for example, an environment of a predetermined temperature and / or a predetermined humidity).

In this regard, Patent Document 1 describes a configuration in which light diffused by a diffuser member is applied to the upstream side of the nip portion of the image carrier with the charging roller.

Japanese Unexamined Patent Publication No. 7-191519

However, with the configuration described in Patent Document 1, the abnormal discharge phenomenon from the charging roller to the image carrier as described above cannot be reliably suppressed.

Therefore, an object of the present invention is to provide an image forming apparatus capable of reliably suppressing an abnormal discharge phenomenon from a charging roller to an image carrier, thereby effectively preventing image defects. ..

In order to solve the above problems, in the image forming apparatus according to the present invention, the image carrier is charged to a predetermined potential by a charging roller, and the image carrier charged to the predetermined potential is exposed to form a latent image. The latent image formed on the image carrier is visualized with toner to form a toner image, and the toner image formed on the image carrier is electrostatically transferred to a sheet material by a transfer unit, and after transfer. An image forming apparatus that eliminates static electricity remaining on the image carrier by a static eliminating unit, comprising a process control unit that controls the image forming process operation under predetermined control conditions during the image forming process operation, and the process control. The unit performs switching control for switching between a static electricity elimination operation that operates the static electricity elimination unit and a non-static electricity elimination operation that does not operate the static electricity elimination unit, and when the static electricity elimination unit is switched to the non-static electricity elimination operation, among the predetermined control conditions. It is characterized by changing the control conditions related to the transcription process.

According to the present invention, it is possible to reliably suppress the abnormal discharge phenomenon from the charging roller to the image carrier, thereby effectively preventing image defects.

It is a schematic sectional drawing of the image forming apparatus which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the image forming part in an image forming apparatus in an enlarged manner. It is a system block diagram of an image forming apparatus. It is explanatory drawing for demonstrating the inconvenience when the static elimination part is switched to the non-static elimination operation. It is a timing chart which shows the operation state of the image formation process corresponding to the preceding sheet material and the succeeding sheet material in the conventional configuration. In the first embodiment, it is a timing chart which shows the operation state of the image formation process corresponding to the preceding sheet material and the succeeding sheet material. In the second embodiment, it is a timing chart which shows the operation state of the image formation process corresponding to the preceding sheet material and the succeeding sheet material. It is a graph for demonstrating the environment table of humidity and temperature stored in advance in a storage part.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of them will not be repeated.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an enlarged image forming portion 3 in the image forming apparatus 100.

The image forming apparatus 100 of the present embodiment is an electrophotographic image forming apparatus, and as shown in FIG. 1, an image reading unit 1, an image forming unit 3 arranged below the image reading unit 1, and an image. A paper feeding unit 2 arranged below the forming unit 3 is provided.

The image reading unit 1 includes a document mounting table 11 made of transparent glass, an automatic document feeding device 12 (ADF) for automatically supplying documents onto the document mounting table 11, and a document placed on the document mounting table 11. The original image reading unit 13 for scanning and reading the image of the above is provided. The image forming unit 3 is provided in the image forming apparatus main body 110. The image forming unit 3 is provided with various components for performing an electrophotographic process centering on a photoconductor drum 30 (image carrier).

The image forming unit 3 includes a photoconductor drum 30, a charging unit 31, an exposure unit 32 (optical scanning unit) (not shown in FIG. 2, see FIG. 1), a developing unit 33 (developing unit), and a transfer unit. It includes 50 (transfer unit), a static elimination unit 34 (static elimination unit), and a cleaning unit 35 (cleaning device).

A charging unit 31, an exposed unit 32, a developing unit 33, a transfer unit 50, a static elimination unit 34, and a cleaning unit 35 are provided around the photoconductor drum 30 in this order.

The charging unit 31 is of a DC voltage application type, and uniformly charges the surface of the photoconductor drum 30 to a predetermined potential. The charging unit 31 includes a charging roller 31a and a charging cleaning roller 31b (see FIG. 2). Only the DC voltage component that does not include the AC voltage component is applied to the charging roller 31a. The charging roller 31a is driven to rotate with the rotation (surface movement) of the photoconductor drum 30 while being in contact with the surface of the photoconductor drum 30. The charged cleaning roller 31b cleans the surface of the charged roller 31a. The charging cleaning roller 31b is driven to rotate with the rotation (surface movement) of the charging roller 31a while in contact with the surface of the charging roller 31a.

The exposure unit 32 emits the image writing light L (laser light) (see FIG. 2) modulated based on the image data from the laser light source 32a (see FIG. 1). The exposure unit 32 irradiates the surface of the photoconductor drum 30, which is uniformly charged to a predetermined potential and is rotated, with the image writing light L while scanning in the main scanning direction. As a result, the exposure unit 32 can write a latent image (electrostatic latent image) on the photoconductor drum 30.

The developing unit 33 visualizes the latent image formed on the photoconductor drum 30 with toner. The developing unit 33 attaches the charged toner to the latent image formed on the photoconductor drum 30 by the exposure unit 32. As a result, the developing unit 33 can visualize the latent image on the photoconductor drum 30 to form a toner image. As shown in FIG. 2, the developing unit 33 is provided with a toner accommodating unit 41 that supplies toner to the developing tank 33a of the developing unit 33.

The transfer unit 50 electrostatically transfers the toner image formed on the photoconductor drum 30 onto a sheet material P such as transfer paper. The transfer unit 50 includes a transfer roller 51 (transfer member). The transfer roller 51 is driven to rotate with the rotation (surface movement) of the photoconductor drum 30 while being in contact with the surface of the photoconductor drum 30. A transfer bias (voltage) is applied to the transfer roller 51.

The static elimination unit 34 eliminates the residual potential remaining in the photoconductor drum 30 after transfer. The static elimination unit 34 is located downstream of the transfer unit 50 and upstream of the charging unit 31 in the rotation direction R (see FIG. 2) of the photoconductor drum 30, between the transfer unit 50 and the cleaning unit 35 in this example. It is arranged. The static elimination unit 34 includes a static elimination light source 34a and a static elimination light guide plate 34b. The static elimination light source 34a emits light toward the static elimination light guide plate 34b. As the static elimination light source 34a, for example, a light emitting element such as an LED can be exemplified. The static elimination light guide plate 34b guides the light from the static elimination light source 34a to the surface of the photoconductor drum 30.

The cleaning unit 35 includes a cleaning blade 36 and a waste toner transfer screw 37. The cleaning blade 36 removes the transfer residual toner remaining on the photoconductor drum 30 without being transferred by the transfer unit 50. The waste toner transfer screw 37 conveys the transfer residual toner removed from the photoconductor drum 30 by the cleaning blade 36 in the direction perpendicular to the drawing (upward). As a result, the image forming apparatus 100 puts the transfer residual toner conveyed by the waste toner conveying screw 37 into the waste toner collecting container (not shown) installed between the front cabinet of the image forming apparatus 100 and the image forming portion 3. Can be recovered.

As shown in FIG. 1, the image forming unit 3 includes a fixing unit 38 (fixing unit). The fixing unit 38 heats and fixes the toner image transferred on the sheet material P by the transfer unit 50 to the sheet material P. The fixing portion 38 includes a heating roller 39 and a fixing roller 40. The heating roller 39 is heated to a predetermined fixing temperature. The fixing roller 40 is crimped toward the heating roller 39 with a predetermined fixing pressure. As a result, the fixing portion 38 can melt the toner image on the sheet material P by the heat of the heating roller 39 and fix it to the sheet material P by the fixing pressure of the fixing roller 40 on the heating roller 39.

The image forming apparatus 100 further includes a paper feeding unit 2 and a conveying unit 4. The paper feed unit 2 includes a paper feed cassette 21 and a manual paper feed tray 22 as a plurality of paper feed devices. The image forming apparatus 100 selects any one of the paper feed cassette 21 and the manual paper feed tray 22. Further, the image forming apparatus 100 separates the sheet materials P one by one by the pickup roller 23 provided in the selected paper feeding device and conveys them toward the conveying unit 4. The transport unit 4 includes a resist roller 20, a discharge roller 25, and a transport roller 26. The resist roller 20 conveys the sheet material P sent from the paper feed unit 2 toward the transfer nip unit N in the transfer direction Y. The resist roller 20 is stationary before the sheet material P is fed. In the resist roller 20, the electrostatic latent image in the photoconductor drum 30 and the image forming region [region excluding the void (margin) region] in the sheet material P coincide with each other in a state where the sheet material P abuts on the transfer nip portion N. Rotational drive is started.

The image forming apparatus 100 includes transport paths S1 and S2, reverse transport paths S3, and a discharge tray 24. The transport paths S1 and S2 transport the sheet material P from the paper feed unit 2 to the image forming unit 3, and transport the sheet material P on which the toner image is fixed to the discharge tray 24. The reverse transfer path S3 is used for double-sided printing. In the reverse transfer path S3, the toner image is printed on the surface and the front and back of the sheet material P switched back by the discharge roller 25 are reversed and guided to the resist roller 20 again. As a result, the image forming apparatus 100 can form a toner image not only on the front surface of the sheet material P but also on the back surface during double-sided printing. In the vicinity of the transport paths S1 and S2 and the reverse transport path S3, transport rollers for transporting the sheet material P are appropriately arranged.

(About this embodiment)
FIG. 3 is a system block diagram of the image forming apparatus 100. As shown in FIG. 3, the image forming apparatus 100 includes a control unit 200 that controls the image forming process operation under predetermined control conditions during the image forming process operation.

The control unit 200 has a processing unit 210 made of a microcomputer such as a CPU (Central Processing Unit), and a storage unit 220 including a non-volatile memory such as ROM and a volatile memory such as RAM. The control unit 200 controls the operation of various components by loading the control program stored in advance in the ROM of the storage unit 220 into the RAM of the storage unit 220 and executing the processing unit 210. As a result, the control unit 200 can drive and control each component of the paper feed unit 2, the image forming unit 3, the transport unit 4, and the fixing unit 38.

Specifically, the control unit 200 includes a process control unit 211. The process control unit 211 controls the timing of applying a DC voltage to the charging roller 31a in the charging unit 31. The process control unit 211 controls the transfer roller 51 in the transfer unit 50 with a constant current. The process control unit 211 controls the transfer unit 50 so that it is always on during the operation of the image forming process. The process control unit 211 controls the operation of the laser light source 32a in the exposure unit 32. The process control unit 211 controls the operation of the static elimination light source 34a in the static elimination unit 34. The process control unit 211 performs switching control for switching between a static elimination operation in which the static elimination unit 34 (static elimination light source 34a) is operated and a non-static elimination operation in which the static elimination unit 34 (static elimination light source 34a) is not operated. The process control unit 211 controls the static elimination unit 34 (static elimination light source 34a) so that it is always on during the image formation process operation when the static elimination unit 34 (static elimination light source 34a) is switched to the static elimination operation. Further, the process control unit 211 controls the timing of starting and stopping the rotation of the resist roller 20 in the transport unit 4.

By the way, according to the knowledge of the present inventor, the abnormal discharge phenomenon from the charging roller 31a to the photoconductor drum 30 starts from a state in which the potential before charging the photoconductor drum 30 is low (a state of substantially 0 V) to the photoconductor drum 30. It is conceivable that the electric potential rises sharply when the drum is charged. Therefore, when the static elimination unit 34 is switched to the non-static elimination operation when the abnormal discharge phenomenon from the charging roller 31a to the photoconductor drum 30 occurs, the static elimination unit 34 does not perform the static elimination operation, so that the photoconductor drum 30 is charged. The photoconductor drum 30 can be charged from a state in which the previous potential is slightly high (a state of several tens of volts). Then, it is possible to suppress the occurrence of an abnormal discharge phenomenon from the charging roller 31a to the photoconductor drum 30.

However, when the static elimination unit 34 is switched to the non-static elimination operation, the occurrence of an abnormal discharge phenomenon from the charging roller 31a to the photoconductor drum 30 can be suppressed, but there are the following inconveniences.

FIG. 4 is an explanatory diagram for explaining the inconvenience when the static elimination unit 34 is switched to the non-static elimination operation. FIG. 5 is a timing chart showing the operating state of the image forming process corresponding to the preceding sheet material P (1) and the succeeding sheet material P (2) in the conventional configuration.

In the example shown in FIG. 5, the “photoreceptor rotation signal” is a signal for rotating the photoconductor drum 30. The “charging unit on signal” is a signal for applying a DC voltage to the charging roller 31a. The "exposure amount (writing)" is a signal for turning on the laser light source 32a. Here, the exposure by the laser light source 32a is a halftone exposure. The “photoreceptor surface potential” is the surface potential of the photoconductor drum 30. The "transfer bias (voltage)" is the transfer bias voltage of the transfer roller 51. Here, since the transfer bias voltage is controlled by a constant current, the voltage value fluctuates according to the transfer state in order to keep the transfer current i constant regardless of the transfer state. The “transfer current (constant current control)” is the transfer current i of the transfer roller 51 under constant current control. For example, when the sheet material P passes through the transfer nip portion N, the resistance value between the photoconductor drum 30 and the transfer roller 51 increases, and the transfer current i decreases as it is. Control is performed to increase the transfer bias voltage so that the transfer current i becomes constant. The "residual surface potential of the photoconductor" is the potential remaining on the surface of the photoconductor drum 30 after the transfer process, and is about −50 V in this example. Further, the total length d of the sheet material P (A4 size) in the transport direction Y is 297 mm, and the peripheral length f (circumference) of the photoconductor drum 30 is 94.2 mm (diameter 30 mm). These things are the same in the examples shown in FIGS. 6 and 7 described later. Further, in the examples shown in FIGS. 5 and 7, the transport interval e between the sheet materials P (1) and P (2) is smaller than the peripheral length f (94.2 mm) of the photoconductor drum 30 (76. 3 mm).

When the static elimination unit 34 is switched to the non-static elimination operation, as shown in FIG. 4, when the rear end of the sheet material P (1) passes through the transfer nip portion N of the transfer unit 50 (transfer roller 51), the transfer unit 50 The transfer current i (see FIG. 4) from the (transfer roller 51) tends to wrap around at the boundary portion with the rear end of the sheet material P (1) of the photoconductor drum 30. Then, the transfer current i is concentrated at the boundary portion between the photoconductor drum 30 and the rear end of the sheet material P (so-called potential memory is generated). At this time, since the static elimination unit 34 does not perform the static elimination operation (the static elimination light source 34a is not turned on), the potential fluctuation of the photoconductor drum 30 cannot be statically eliminated and affects the charging of the photoconductor drum 30. Therefore, as shown in FIG. 5, minute potential unevenness that cannot be measured by an electrometer is formed on the surface of the photoconductor drum 30. As a result, in the image (halftone image) formed on the subsequent sheet material P (2), the potential memory image MI [corresponds to the rear end of the preceding sheet material P (1) at one round of the photoconductor drum 30. Anomalous images such as horizontal streaks] appear, and image defects occur in the subsequent images on the sheet material P (2).

In this respect, in the present embodiment, the process control unit 211 performs switching control for switching the static elimination unit 34 between the static elimination operation and the non-static elimination operation, and when the static elimination unit 34 is switched to the non-static elimination operation, a predetermined control condition is obtained. The control conditions related to the transcription process are changed. By doing so, it is possible to effectively prevent the generation of the potential memory image in the succeeding sheet material P (2) due to the potential memory of the portion corresponding to the rear end of the preceding sheet material P (1) in the photoconductor drum 30. Can be done. As a result, the abnormal discharge phenomenon from the charging roller 31a to the photoconductor drum 30 can be reliably suppressed, and the potential memory image in the sheet material P can be suppressed. This is particularly effective under a predetermined environment (for example, an environment with a predetermined temperature and / or a predetermined humidity).

Next, specific examples of control conditions relating to the transcription process will be described below with reference to the first to third embodiments.

(First Embodiment)
FIG. 6 is a timing chart showing the operating state of the image forming process corresponding to the preceding sheet material P (1) and the succeeding sheet material P (2) in the first embodiment.

In the first embodiment, the control condition relating to the transfer process changes the transport interval between two adjacent sheet materials P (1) and P (2) that are transported during continuous image formation in which images are continuously formed. It is a control condition. By doing so, the position of the potential memory corresponding to the rear end of the preceding sheet material P (1) in the photoconductor drum 30 can be set to an arbitrary position [tip void (front margin), rear end void (rear end margin), or the like. The potential memory image can be positioned in an inconspicuous or inconspicuous position). As a result, the potential memory image can be made inconspicuous or inconspicuous in the subsequent sheet material P (2).

In the first embodiment, the transport interval e between the sheet materials P (1) and P (2) is one circumference or more of the peripheral length f (94.2 mm) of the photoconductor drum 30 (in the example shown in FIG. 6, the circumference). It is 94.2 mm, which is the same as the length f). By doing so, although the number of images formed per unit time is slightly reduced, the position of the potential memory corresponding to the rear end of the preceding sheet material P (1) in the photoconductor drum 30 is set to [Transport interval e]> [ In the case of [perimeter f], between the sheet materials P (1) and P (2) (position where no image is formed), or in the case of [transport interval e] = [perimeter f] as shown in FIG. It can be positioned at the position of the tip of the subsequent sheet material P (2) (the position where the image is not formed, which is the void region B at the tip). Thereby, the potential memory image can be eliminated in the sheet material P.

(Second Embodiment)
FIG. 7 is a timing chart showing the operating state of the image forming process corresponding to the preceding sheet material P (1) and the succeeding sheet material P (2) in the second embodiment.

In the second embodiment, the control conditions relating to the transfer process are the transfer unit 50 (transfer roller 51) from the predetermined first time T1 before the rear end of the sheet material P (1) passes through the transfer unit 50 (transfer roller 51). ), And the transfer conditions are changed until the predetermined second time T2. By doing so, it is possible to reduce the potential memory of the portion of the photoconductor drum 30 corresponding to the rear end of the preceding sheet material P (1). As a result, the potential memory image in the subsequent sheet material P (2) can be suppressed.

In the second embodiment, the process control unit 211 forcibly lowers the transfer voltage (transfer bias voltage) of the transfer unit 50 (transfer roller 51) between the first time T1 and the second time T2. That is, since the process control unit 211 controls the transfer roller 51 in the transfer unit 50 with a constant current, the transfer unit 50 (transfer roller 51) is transferred between the first time T1 and the second time T2. The current i is forcibly reduced (for example, reduced from 6 μA to 5 μA). By doing so, the potential memory of the portion of the photoconductor drum 30 corresponding to the rear end of the sheet material P can be easily reduced. The wavy line portion of the transfer bias (voltage) in FIG. 7 indicates a state in which the transfer bias voltage is not forcibly lowered.

(Third Embodiment)
In the third embodiment, the control unit 200 further includes an environmental condition detection unit 60 (see FIG. 1) (environmental condition sensor) that detects ambient environmental conditions (temperature and / or humidity). In this example, as shown in FIG. 3, the environmental condition detection unit 60 includes a temperature detection unit 61 (temperature sensor) for detecting temperature and a humidity detection unit 62 (humidity detection sensor) for detecting humidity. .. The process control unit 211 switches the static elimination unit 34 (static elimination light source 34a) to the non-static elimination operation when the environmental condition detection unit 60 detects a predetermined environmental condition. Further, the process control unit 211 switches the static elimination unit 34 (static elimination light source 34a) to the static elimination operation when the environmental condition detection unit 60 detects an environmental condition other than the predetermined environmental condition.

By doing so, the static elimination unit 34 (static elimination light source 34a) is switched to the non-static elimination operation only under a predetermined environment (for example, an environment of a predetermined temperature and / or a predetermined humidity), and the static elimination operation is performed under the predetermined control conditions. The control conditions for the transcription process can be changed.

In this example, the storage unit 220 stores the humidity and temperature environment table 221 (see FIG. 3) in advance.

FIG. 8 is a graph for explaining the environment table 221 of humidity RH and temperature RT stored in advance in the storage unit 220.

As shown in FIG. 8, the environment table 221 has a plurality of environment points E (1) to E (n) (n is an integer of 3 or more, n = 19 in this example) of humidity RH and temperature RT. There is. In the process control unit 211, the specific environment region α connecting the plurality of environment points E (1) to E (n) stored in the storage unit 220 by the environmental condition detection unit 60 (temperature detection unit 61 and humidity detection unit 62) When the inside is detected, the static elimination unit 34 (static elimination light source 34a) is switched to the non-static elimination operation. By doing so, when the humidity RH and the temperature RT are within the specific environment region α, the static elimination unit 34 (static elimination light source 34a) can be reliably switched to the non-static elimination operation.

The present invention is not limited to the embodiments described above, and can be implemented in various other forms. Therefore, such embodiments are merely exemplary in all respects and should not be construed in a limited way. The scope of the present invention is set forth by the claims and is not bound by the text of the specification. Further, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

1 Image reading unit 2 Feeding unit 3 Image forming unit 4 Transporting unit 20 Resist roller 21 Paper feed cassette 30 Photoreceptor drum 31 Charging unit 31a Charging roller 31b Charging cleaning roller 32 Exposure unit 32a Laser light source 33 Developing unit 34 Static elimination unit 34a Static elimination Light source 34b Static light guide plate 35 Cleaning unit 38 Fixing unit 50 Transfer unit 51 Transfer roller 60 Environmental condition detection unit 61 Temperature detection unit 62 Humidity detection unit 100 Image forming device 200 Control unit 210 Processing unit 211 Process control unit 220 Storage unit 221 Environment Table B Void area E Environment point L Image writing Optical MI Potential memory Image N Transfer nip part P Sheet material RH Humidity RT Temperature T1 1st time T2 2nd time Y Transport direction d Total length e Transport interval f Circumferential length i Transfer current α Specific Environmental area

Claims (6)

The image carrier is charged to a predetermined potential by a charging roller, the image carrier charged to the predetermined potential is exposed to form a latent image, and the latent image formed on the image carrier is visualized with toner. The toner image formed on the image carrier is electrostatically transferred to the sheet material by the transfer unit, and the residual potential remaining on the image carrier after the transfer is statically eliminated by the static eliminator. It ’s a device,
A process control unit that controls the image formation process operation under predetermined control conditions during the image formation process operation is provided.
The process control unit performs switching control for switching between a static elimination operation that operates the static elimination unit and a non-static elimination operation that does not operate the static elimination unit, and when the static elimination unit is switched to the non-static elimination operation, the predetermined control conditions are met. An image forming apparatus characterized in that the control conditions relating to the transfer process are changed. The image forming apparatus according to claim 1.
It also has an environmental condition detector that detects the surrounding environmental conditions.
The process control unit is an image forming apparatus characterized in that when the environmental condition detection unit detects a predetermined environmental condition, the static elimination unit is switched to a non-static elimination operation. The image forming apparatus according to claim 1 or 2.
The image forming apparatus is characterized in that the control condition relating to the transfer process is a control condition for changing the transfer interval between two adjacent sheet materials to be conveyed during continuous image formation in which an image is continuously formed. The image forming apparatus according to claim 3.
An image forming apparatus characterized in that the transport interval between the sheet materials is one circumference or more of the circumference of the image carrier. The image forming apparatus according to claim 1 or 2.
The control conditions relating to the transfer process change the transfer conditions from a predetermined first time before the rear end of the sheet material passes through the transfer portion to a predetermined second time after passing through the transfer portion. An image forming apparatus characterized in that it is a control condition to be performed. The image forming apparatus according to claim 5.
An image forming apparatus, characterized in that the transfer voltage of the transfer unit is forcibly lowered between the first time and the second time.

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