Image forming apparatus

Abstract

To provide an image forming apparatus that can achieve both prevention of a harmful effect on an image and conveyability of a recording material at a transfer unit.SOLUTION: An image forming apparatus has: an image carrier; a rotatable transfer member that is in contact with a surface of the image carrier to form a transfer nip part and transfers a toner supplied to the surface of the image carrier to a recording material at the transfer nip part; a guide unit that is in contact with a surface of the recording material opposite to a surface to which the toner is transferred, to guide conveyance of the recording material to the transfer nip part; and a static eliminating unit that eliminates static electricity from a surface of the transfer member at a facing part that faces the surface of the transfer member on the upstream side of the transfer nip part in the direction of rotation of the transfer member and on the upstream side of the transfer nip part in the direction of movement of the recording material. The image forming apparatus has a conveyance guide that guides the conveyance of the recording material to the transfer nip part, and a transfer voltage application unit that applies a transfer voltage to the transfer member. The static eliminating unit eliminates static electricity from the surface of the transfer member at the facing part, while the transfer voltage is applied to the transfer member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunction machine that uses an electrophotographic system or an electrostatic recording system. [Background technology]

[0002] Conventionally, some electrophotographic image forming apparatuses use an endless belt that rotates while carrying a toner image. For example, in an intermediate transfer image forming apparatus, a toner image is primarily transferred from a photosensitive member to an intermediate transfer belt, which is an intermediate transfer member formed of an endless belt, at a primary transfer section. The toner image primarily transferred to the intermediate transfer belt is then transferred to a recording material at a secondary transfer nip by a transfer voltage applied to a secondary transfer roller.

[0003] In image forming devices using such intermediate transfer belts, abnormal discharge occurs between the recording material and the intermediate transfer belt in the discharge area formed just before the secondary transfer nip, resulting in image defects (whiteouts) in which the toner image in the abnormally discharged area is not transferred and is missing.

[0004] As a method for suppressing this image degradation, a configuration has been proposed in which a grounded static eliminator is brought into contact with the surface of the secondary transfer roller immediately before the secondary transfer position, thereby lowering the potential on the surface of the secondary transfer roller and weakening the electric field in the discharge area (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-197114 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the configuration of Cited Document 1 had the following problems: In particular, under conditions where image defects are likely to occur, such as when the recording material is thick paper that has been left in a low-temperature, low-humidity environment and dried, requiring a high transfer voltage, or when transferring a full-area, high-print pattern in which missing toner is easily noticeable, it was sometimes impossible to achieve both image defects and paper conveyance performance.

[0007] To suppress image defects even under conditions where image defects are likely to occur, the static eliminator is positioned closer to the secondary transfer nip, which brings the static eliminator closer to the recording material. This can lead to problems with transport, such as damage to the recording material, due to contact between the recording material and the control electrode when the recording material is thin, stiff, or curled paper. On the other hand, if a transport guide is positioned immediately before the secondary transfer nip to improve the transportability of the recording material, space limitations force the static eliminator to be positioned farther away from the secondary transfer nip. This can make it difficult to suppress image defects under conditions where image defects are likely to occur.

[0008] The object of the invention of this application is to provide an image forming apparatus that can suppress image defects in the transfer section while also improving the transportability of recording materials, in consideration of the above-mentioned conventional problems. [Means for solving the problem]

[0009] The image forming apparatus of the present invention comprises an image carrier, a rotatable transfer member that contacts the surface of the image carrier to form a transfer nip and transfers toner supplied to the surface of the image carrier at the transfer nip to a recording material, a guide section that contacts the surface of the recording material opposite to the surface to which the toner is transferred to guide the recording material as it is transported to the transfer nip, a discharge section that discharges electricity from the surface of the transfer member at an opposing section that is upstream of the transfer nip in the rotation direction of the transfer member and faces the surface of the transfer member upstream of the transfer nip in the movement direction of the recording material, and a transport guide that guides the recording material to be transported to the transfer nip, and a transfer voltage application section that applies a transfer voltage to the transfer member, and the discharge section discharges electricity from the surface of the transfer member at the opposing section while the transfer voltage is applied to the transfer member. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress image defects in the transfer section and to improve the conveyance efficiency of the recording material. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram for explaining an image forming apparatus according to a first embodiment. [Figure 2] FIG. 3 is an enlarged view of a secondary transfer portion according to the first embodiment. [Figure 3] 10 is an enlarged view of a secondary transfer portion according to Comparative Examples 1 and 2. FIG. [Figure 4] 10A and 10B are an enlarged view of a secondary transfer portion and a schematic view of a conveyance guide according to a second embodiment. [Figure 5] 10 is an enlarged view of a secondary transfer portion according to Comparative Examples 3 and 4. FIG. [Figure 6] FIG. 2 is a control block diagram according to the first embodiment. [Figure 7] FIG. 10 is a diagram for explaining an image forming apparatus according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail exemplary embodiments of the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions, and the scope of the present invention is not limited to the following embodiments.

[0013] [Example 1] <Overall Configuration and Operation of Image Forming Apparatus> An image forming apparatus 500 according to this embodiment shown in FIG. 1 is a tandem-type full-color image forming apparatus that uses an intermediate transfer member as an image carrier, and the figure is a vertical cross-sectional view showing the schematic configuration thereof.

[0014] In the image forming apparatus 500 of the first embodiment, four image forming units, i.e., image forming units 1a, 1b, 1c, and 1d, which respectively form toner images of yellow (Y), magenta (M), cyan (C), and black (Bk), are arranged from upstream to downstream. These four image forming units are arranged in a line (side by side) at regular intervals. The four image forming units are image forming unit 1a, which forms yellow images, image forming unit 1b, which forms magenta images, image forming unit 1c, which forms cyan images, and image forming unit 1d, which forms black images. When the image forming apparatus 500 is installed, an intermediate transfer belt 8, which is an intermediate transfer member stretched over rollers 12 and 13, is disposed below the image forming units 1a, 1b, 1c, and 1d in the direction of gravity.

[0015] Each image forming unit 1a, 1b, 1c, and 1d is provided with a photosensitive drum 2a, 2b, 2c, and 2d, respectively, as an image carrier. In this embodiment, the photosensitive drums 2a, 2b, 2c, and 2d are negatively charged organic photosensitive members having a photosensitive layer on a drum substrate made of aluminum or the like, and are driven to rotate at a predetermined process speed by a drive unit 60 (FIG. 6) as a drive device. In this embodiment, the process speed was set to 100 mm / sec.

[0016] Developing devices 5a, 5b, 5c, and 5d are arranged around the photosensitive drums 2a, 2b, 2c, and 2d, respectively, and include charging rollers 3a, 3b, 3c, and 3d, which serve as charging members, and developing rollers 4a, 4b, 4c, and 4d, which serve as developing members and developer carriers. Developing devices 5a, 5b, 5c, and 5d contain toners 90a, 90b, 90c, and 90d, respectively, corresponding to yellow (Y), magenta (M), cyan (C), and black (Bk). Non-magnetic, single-component polymerized toners with a charge of -20 to -50 μC / mg were used for the toners 90a, 90b, 90c, and 90d. The normal charge polarity of the toners 90a, 90b, 90c, and 90d is negative. This image forming apparatus 500 employs a reverse development system. Furthermore, cleaning devices 6a, 6b, 6c, and 6d having cleaning blades 7a, 7b, 7c, and 7d as cleaning members are installed around each of the photosensitive drums 2a, 2b, 2c, and 2d. The cleaning blades 7a, 7b, 7c, and 7d scrape off foreign matter such as toner, paper dust, and fillers remaining on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, and collect the remaining foreign matter inside the cleaning devices 6a, 6b, 6c, and 6d. Furthermore, exposure devices 9a, 9b, 9c, and 9d are installed above each of the photosensitive drums 2a, 2b, 2c, and 2d in the direction of gravity.

[0017] Here, the configuration and operation of each image forming unit 1 are essentially the same except for the different colors of toner used. Therefore, unless a particular distinction is required in the following description, the suffixes a, b, c, and d given to the reference numerals in FIG. 1 will be omitted to indicate that the element is provided for one of the colors, and the description will be generalized. Also, in this embodiment, four image forming units 1 will be described, but this is not limited to this, and multiple image forming units 1 may be provided. Also, as will be described later, it is possible to use a monochrome printer having a single image forming unit 1.

[0018] A rotatable, endless intermediate transfer belt 8 is installed as an intermediate transfer body at positions facing the image forming units 1a, 1b, 1c, and 1d. Primary transfer rollers 41a, 41b, 41c, and 41d are arranged to transfer the toner images formed on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d onto the surface of the intermediate transfer belt 8. The intermediate transfer belt 8 is stretched by a secondary transfer opposing roller 12 and a tension roller 13, which also serve as tensioning members and drive the intermediate transfer belt 8. The secondary transfer opposing roller 12, which is connected to a drive unit 60 serving as a motor, rotates (moves) the intermediate transfer belt 8 in the direction indicated by arrow Z in FIG. 1 (counterclockwise in FIG. 1). As shown in FIG. 1, four image forming units 1 and four primary transfer rollers 41 are arranged in parallel along the rotational direction of the intermediate transfer belt 8. Hereinafter, the rotational direction of the intermediate transfer belt 8 will be referred to as the circumferential direction of the intermediate transfer belt 8. The thickness of the intermediate transfer belt 8 is preferably 50 μm to 200 μm, because if it is too thin, the belt strength weakens, and if it is too thick, it loses elasticity and becomes difficult to bend. Furthermore, the thickness affects the electrostatic capacitance of the intermediate transfer belt 8. If it is too thin, the electrostatic capacitance increases and it is prone to charging. In consideration of this, in this embodiment, the thickness of the intermediate transfer belt 8 is set to 80 μm. Materials commonly used for the intermediate transfer belt 8 include PI, PET, PEN, and PVDF, but PI was used for its strength. The resistance of the intermediate transfer belt 8 must be adjusted by adding a conductive agent to achieve the desired electrical resistance. In this embodiment, carbon black is used as the conductive agent. Generally, the conductive mechanism of carbon black is electronic conductivity, which has little environmental dependency but high voltage dependency. On the other hand, ionic conductive agents have little voltage dependency but high environmental dependency. In this embodiment, the resistance increase of the intermediate transfer belt 8 in a low-humidity environment is suppressed, and abnormal discharge during secondary transfer is suppressed by lowering the secondary transfer voltage required for secondary transfer. In addition, the addition of a small amount of carbon black makes it possible to adjust the electrical resistance, and it is preferable because it can be produced at low cost. 8 ~10 14 The range is Ω·cm. 10 8If the resistivity is less than Ω·cm, the charge of the toner transferred onto the intermediate transfer belt 8 will flow out onto the intermediate transfer belt 8, which will cause the toner image to become distorted. 14 If it exceeds Ω·cm, the voltage required for secondary transfer becomes large, making abnormal discharge more likely to occur.

[0019] The drive unit 60 may have a drive unit for the secondary transfer opposing roller 12 separate from the photosensitive drum 2.

[0020] 6, a transfer voltage (bias) of positive polarity opposite to the normal polarity of toner 90 is applied to primary transfer roller 41. The transfer voltage (bias) is constant voltage or constant current controlled from primary transfer power source 73 as a primary transfer voltage application unit shown in FIG. 6. Then, the toner image formed on photosensitive drum 2 is transferred onto intermediate transfer belt 8.

[0021] The secondary transfer roller 15 as a secondary transfer member transfers the toner image formed on the intermediate transfer belt 8 onto the transfer material S as a recording material. In this embodiment, a secondary transfer roller having a diameter of φ18 and made of a metal core metal having a diameter of φ8 covered with an NBR foam sponge body is used. A constant voltage or constant current controlled positive voltage is applied to the secondary transfer roller 15 from the secondary transfer power source 74 as a secondary transfer voltage application unit shown in FIG.

[0022] The secondary transfer opposing roller 12 is provided with a high friction rubber layer on the surface to drive the intermediate transfer belt 8. This rubber layer has a volume resistivity of 10 5 It has a conductivity of Ω·cm or less. It also abuts against a secondary transfer roller 15, which serves as a secondary transfer member, via the intermediate transfer belt 8, to form a secondary transfer section SN. Here, the secondary transfer roller 15 is disposed so as to abut against the intermediate transfer belt 8, and forms a secondary transfer nip SN between it and the intermediate transfer belt 8, as shown in FIG. 1. The tension roller 13 applies a total tension of approximately 60 N to the intermediate transfer belt 8, and rotates in accordance with the intermediate transfer belt 8.

[0023] The secondary transfer opposing roller 12 (opposing member) and the tension roller 13 are each grounded via a resistive element having the same resistance value. In this embodiment, three types of resistive elements are used: 100 MΩ, 10 MΩ, and 10 MΩ. The resistance of the rubber layer of the secondary transfer opposing roller 12 is sufficiently smaller than 100 MΩ and 10 MΩ, so electrical influences can be ignored.

[0024] The secondary transfer roller 15 has a volume resistivity of 10 7 ~10 9 An elastic roller with a resistance of Ωcm and a rubber hardness of 30° (Asker C hardness scale) was used. The transfer roller 15 was configured to press the secondary transfer opposing roller 12 with a total pressure of approximately 39.2 N via the intermediate transfer belt 8. The secondary transfer roller 15 rotates in accordance with the rotation of the intermediate transfer belt 8. A secondary transfer voltage of -2.0 to 7.0 kV can be applied to the transfer roller 15 from a secondary transfer voltage application unit 74, which serves as a secondary transfer (high-voltage) power source, as shown in FIG. 6. The secondary transfer roller 15 corresponds to the transfer member, and the secondary transfer roller 15 and the secondary transfer power source 74 correspond to the secondary transfer means. A belt cleaning device 75 having a belt cleaning blade 80 as a belt cleaning member for removing and collecting residual toner remaining on the surface of the intermediate transfer belt 8 is installed on the outer periphery of the intermediate transfer belt 8.

[0025] As shown in FIG. 2, the secondary transfer roller 15 has a cylindrical core 15b and a cylindrical elastic layer 15a that covers the outer circumferential surface of the core 15b. The outer diameter of the core 15b is 6 mm, and the outer diameter of the elastic layer 15a is 16 mm. The core 15b is made of a highly rigid conductive material, and in this embodiment, iron is used. The elastic layer 15a is made of commonly used acrylonitrile butadiene rubber (NBR) ion conductive rubber that has been foamed into a sponge-like shape. The volume resistivity of the elastic layer 15a in this embodiment is 10 7 ~10 9The volume resistivity of the secondary transfer roller 15 is set to 10 Ω·cm. If the volume resistivity of the secondary transfer roller 15 is too low, the resistance of the transfer material S will have a large effect on the transferability, which may result in unstable transferability depending on the environment. Conversely, if the volume resistivity is too high, the voltage required for secondary transfer will increase, making it more likely that abnormal discharge will occur. Therefore, the volume resistivity of the elastic layer 15a is set to 10 5 ~10 11 A hardness in the Ω·cm range is desirable. If the hardness of the secondary transfer roller 15 is too soft, the width of the transfer nip portion SN will increase, which will increase the torque of the driven secondary transfer roller 15. If the hardness is too hard, the nip width of the transfer nip portion SN will narrow, which may result in poor transfer. Therefore, the hardness of the secondary transfer roller 15 is preferably 20° to 40° when using an Asker C hardness tester with a 500g load. The secondary transfer roller 15 used had a hardness of 30° when using an Asker C hardness tester with a 500g load.

[0026] Line W in FIG. 1 is a conveyance line indicating the conveyance path along which transfer material S is conveyed when an image is formed on the first surface (front surface) of transfer material S. The paper feed unit feeds and conveys transfer material S to secondary transfer unit SN, and multiple transfer materials S are stored in paper feed cassette 16. During image formation, a pickup roller 17 (a half-moon roller) picks up the top transfer material S stacked on paper feed cassette 16, and a pair of paper feed rollers 18 conveys the transfer material S to a pair of registration rollers 19, which are conveyance rollers. The leading edge of transfer material S strikes the pair of registration rollers 19 and stops temporarily. A toner image formed by image forming unit 1 is transferred to intermediate transfer belt 8. At this time, the transfer material S is conveyed to secondary transfer unit SN by registration roller pair 19, while being regulated by regulating portion A, which serves as a guide portion of conveyance guide 32, in synchronization with the leading edge of the toner image on intermediate transfer belt 8 moving to secondary transfer unit SN. Then, the toner image on intermediate transfer belt 8 is transferred to transfer material S. The recording material S is guided to the transfer nip SN. Then, the recording material S receives the charge required for secondary transfer from the transfer roller 15 at the transfer nip SN, and the toner on the intermediate transfer belt 8 is transferred to the side of the recording material S that is on the intermediate transfer belt 8.

[0027] A downstream charge elimination needle 40 is disposed downstream in the conveyance direction of the transfer material S to eliminate charge formed on the transfer material S. The downstream charge elimination needle 40 is a 0.1 mm-thick SUS304 thin plate processed into a sawtooth shape, with a pitch of 1 mm between adjacent sawtooth teeth. The downstream charge elimination needle 40 is installed at a height that does not contact the conveyed transfer material S, with the tip of the sawtooth facing the second surface (back surface) of the transfer material S. By eliminating the charge on the transfer material S downstream in the conveyance direction of the transfer material S that has passed through the secondary transfer unit T, the electrostatic attraction force to the intermediate transfer belt 8 is reduced, improving the separation of the transfer material S. In this embodiment, the distance between the tip of the downstream charge elimination needle 40 and the secondary transfer roller 15 is 3 mm.

[0028] The fixing member 20, which serves as a fixing unit, fixes the multicolor toner image transferred to the transfer material S. The heating member 21 on the print surface side is composed of a ceramic heater 21a (hereinafter referred to as the heater), a ceramic plate-shaped heating element, a holder member 21b for holding the heater, and a fixing film 21c of the heating member that completely encases the heater and holder member. A thermistor is located behind the heater 21 to control the heater temperature. A pressure roller 22 applies pressure from the opposing side, forming a fixing nip. This heats and presses the print surface side with the heating member 21 and the non-print surface side with the pressure roller 22, melting and fixing the toner image to the transfer material S. A pair of paper discharge rollers 23 is located downstream of the fixing member 20 in the conveyance direction of the transfer material S, and discharges the transfer material S to a paper discharge tray 24 of the device main body.

[0029] <Control unit> Reference numeral 502 in Fig. 1 denotes a control unit of the image forming apparatus 500. The control unit 502 controls the operations of the image forming unit 1 and the like. Fig. 6 is a block diagram showing the control configuration of the main parts of the image forming apparatus 500 of this embodiment. The control unit 502 will be described in further detail with reference to Fig. 6.

[0030] The control unit 502 includes a CPU 31 as a central processing unit that performs various arithmetic operations, and main memory such as a RAM 33, a ROM 34, and a nonvolatile memory (NVRAM) 35 that store information. The CPU 31 is connected to the exposure unit 9 as well as the RAM 33, the ROM 34, and the nonvolatile memory NVRAM 35. The ROM 34 is a read-only storage unit (memory) that stores programs and various data used by the CPU 31 to control the image forming apparatus 500. The RAM 33 is a readable / writable memory, and data stored in the RAM 34 is expanded and various data is saved therein. The NVRAM 35 is a readable / writable memory that retains its contents even when the image forming apparatus is turned off. The RAM 33 temporarily stores sensor detection results, counter count results, calculation results, and the like. The ROM 34 also stores a control program and data tables obtained in advance through experiments, etc. The NVRAM 35 also stores counter count results, various setting information, sensor results, and the like. The environment sensor 36 is made up of a temperature sensor and a relative humidity sensor, and temperature information and relative humidity information inside the engine section 501 are taken into the CPU 31 and used to control the image forming section 1 and the like.

[0031] Signals indicating various types of information are input to and output from the control unit 502 via the electrical connections. The control unit 502 processes signals input from various process devices and sensors, and processes signals output to issue operation commands to the various process devices.

[0032] The control unit 502 is connected to each control target, sensor, counter, etc. in the image forming apparatus 500. The control unit 502 controls the input and output of various signals, the timing of driving each unit, etc., and controls a predetermined image formation sequence.

[0033] The control unit 502 controls, for example, a charging power supply 71 as a charging voltage application unit for applying a charging voltage to the charging roller 3, and a developing power supply 72 as a developing voltage application unit for applying a developing voltage to the developing roller 4. In addition, the control unit 502 controls the exposure device 9, a primary transfer power supply 73 as a primary transfer voltage application unit, a secondary transfer power supply 74 as a secondary transfer voltage application unit, the fixing unit 20, the drive unit 60, etc.

[0034] The drive unit 60 is configured to include a drive motor as a drive source, a drive transmission member, etc. The drive sources that drive the rotating members such as the photosensitive drum 2 and the developing roller 4 may be provided independently, or at least a portion may be shared. The drive sources that drive the elements for each color may be provided independently, or at least a portion may be shared.

[0035] Here, the image forming apparatus 500 executes an image forming operation (print job), which is a series of operations initiated by a single start command to form and output an image on one or more transfer materials S. The image forming operation generally includes an image forming process, a pre-process (pre-rotation process, pre-printing operation), an inter-sheet process when forming images on multiple transfer materials S, and a post-process (post-rotation process, post-printing operation). The image forming process is a period during which an electrostatic latent image of the image to be actually formed and output on the transfer material S is formed, a toner image is formed, the toner image is primarily transferred, and the toner image is fixed. This period is referred to as the image formation time. More specifically, the timing of the image formation time varies depending on the position where each of the processes of charging, exposure, development, primary transfer, secondary transfer, and fixing is performed. The pre-process, which is a pre-rotation operation, is a period from when a start command is input until the actual start of image formation, during which preparatory operations are performed before the image forming process. The inter-sheet process, which is an inter-sheet operation, is a period corresponding to the interval between transfer materials S when image formation is continuously performed on multiple transfer materials S (continuous image formation). The post-rotation process, which is a post-rotation operation, is a period in which a rearrangement operation (preparation operation) is performed after the image forming process. The non-image formation time is a period other than the image formation time, and includes the pre-process, the inter-sheet process, the post-process, and further the pre-multiple rotation process, which is a preparatory operation when the image forming apparatus 500 is turned on or when it returns from a sleep state.

[0036] <Image formation operation> When image formation begins, the photosensitive drum 2, intermediate transfer belt 8, etc., are driven by the drive unit 60 at a predetermined process speed (100 mm / sec in this example) and begin to rotate in the direction of the arrow. The photosensitive drum 2 is uniformly charged to a surface potential of approximately -450 V due to discharge between the photosensitive drum 2 and the charging roller 3, to which a predetermined charging voltage (approximately -1000 V) is applied by the charging power supply 71. This surface potential of approximately -450 V is referred to as the dark potential Vd. An electrostatic latent image based on the output image data is then formed by the scanning beam from the exposure device 9. When the solid electrostatic latent image is formed, the surface potential of the photosensitive drum is approximately -100 V. This surface potential of approximately -100 V is referred to as the light potential Vl.

[0037] At this time, the electrostatic latent images of each color are formed at a predetermined timing so that the four colors will later be superimposed on the intermediate transfer belt 8 to form a full-color image. As the exposed photosensitive drum 2 continues to rotate, the electrostatic latent images on the photosensitive drum 2 are visualized (developed) by the developing roller 4, to which a developing voltage of approximately -300 V is applied by the developing power supply 72. The developing roller 4 rotates in the forward direction relative to the rotation direction of the photosensitive drum 2. Then, toner images of Y, M, C, and Bk are formed on the photosensitive drum 2, respectively. As the toner images on the photosensitive drum 2 continue to rotate, the toner images are transferred onto the intermediate transfer belt 8 by the primary transfer roller 41, to which a primary transfer voltage of approximately +800 V is applied by the primary transfer power supply 73.

[0038] The transfer material S loaded in the paper feed cassette 16 is fed by a crescent-shaped pickup roller / paper feed roller 17, separated into individual sheets by a separation roller / paper feed roller 18, and conveyed to a registration roller 19, where it is temporarily stopped. The stopped transfer material S is supplied to the secondary transfer nip SN by the registration roller 19 in synchronization with the timing at which the four-color toner image formed on the intermediate transfer belt 8 reaches the secondary transfer nip SN. Then, a secondary transfer voltage is applied by a secondary transfer power supply 74, and the toner image on the intermediate transfer belt 8 is transferred onto the transfer material S.

[0039] The transfer material S onto which the toner image has been transferred is separated from the intermediate transfer belt 8 and sent to the fixing device 20. Here, the print side is heated and pressed by a heating member 21, and the non-print side is heated and pressed by a pressure roller 22, melting the toner image and fixing it to the transfer material S. Downstream of the fixing member 20 in the conveyance direction of the transfer material S, there is a pair of discharge rollers 23, which discharge the transfer material S onto a discharge tray 24 of the device main body. Residual toner remaining on the surface of the intermediate transfer belt 8 is collected by a belt cleaning device 75 having a belt cleaning blade 80 as a belt cleaning member.

[0040] <Configuration of the conveying guide in this embodiment> Next, the configuration of the transport guide 32 in this embodiment will be described.

[0041] In this embodiment, the conveying guide 32 is formed from a 1.0 mm thick iron plate, and has both a regulating portion A as a guide portion for the recording material S and a discharging portion B that contacts the secondary transfer roller 15 to release the transfer current. The structure of the conveying guide in this embodiment will be described in detail below.

[0042] The transport guide 32 has a restricting portion A that protrudes toward the secondary transfer opposing roller 12 and an inclined guide portion 32a that inclines away from the transport path of the recording material S as it moves downstream from the restricting portion A in the transport direction of the recording material S. The downstream end of the inclined guide portion 32a in the transport direction of the recording material S serves as a charge-removing member and contacts the secondary transfer roller 15 at a charge-removing portion B. The transport guide 32 is electrically grounded via a conductive path 60, as shown in FIG. 2. This allows the transfer current to escape from the secondary transfer roller 15 through the transport guide 32 when the secondary transfer voltage is applied, thereby preventing white spots. White spots are an image defect in which abnormal discharge occurs between the recording material S and the intermediate transfer belt 8 in a discharge region H formed immediately before the secondary transfer nip SN. This causes the toner image in the abnormal discharge region to be lost and not transferred. Having the restricting portion A and the charge-removing portion B in the transport guide 32 increases the flexibility of its placement, allowing the restricting portion A and the charge-removing portion B to be positioned closer to the upstream side of the nip SN. In this embodiment, the distance α between the regulating unit A and the entrance SNa of the nip SN is set to 5 mm. The shorter this distance α, the more stably the leading edge of the recording material S can be guided to the nip SN. The distance β between the discharge unit B and the entrance SNa of the nip SN is set to 3 mm. The shorter this distance β, the more the potential of the surface of the secondary transfer roller 15 in the discharge region H decreases, thereby increasing the effect of suppressing blank spots. Furthermore, in the configuration of this embodiment, the regulating unit A and the discharge unit B are formed from the same material, which reduces manufacturing variations in the relative positional relationship between the regulating unit A and the discharge unit B, which is more advantageous in achieving both blank spot suppression and conveyance performance.

[0043] In this embodiment, the regulating portion A of the conveying guide 32 is positioned on the opposite side (L2) of the secondary transfer roller 15 (the side of the secondary transfer opposing roller 12) from the straight line L connecting the entrance SNa and exit SNb of the transfer nip SN. By positioning the regulating portion A in this manner, the conveying path of the recording material S regulated by the regulating portion A approaches the intermediate transfer belt 8 at the discharge portion H. This short distance between the recording material S and the intermediate transfer belt 8 at the discharge portion H makes it less likely for abnormal discharge to occur, further reducing whiteout. In addition, the toner image printing range on the recording material S of the image forming apparatus in this embodiment is up to 5 mm from the trailing edge of the recording material S, and the 5 mm at the trailing edge of the recording material S is left blank. By setting the distance α to be equal to or less than the length of the blank, as in this embodiment, blankouts in the toner image near the trailing edge of the recording material S can also be reduced.

[0044] In this embodiment, the conveyance guide 32 has an inclined guide portion 32a, located downstream of the regulating portion A in the conveyance direction of the recording material S, that is inclined so as to approach the secondary transfer roller 15 in a direction perpendicular to the straight line L as it moves downstream in the conveyance direction of the recording material S. A static eliminator B is formed at the tip of the inclined guide portion 32a. As described above, in a cross section perpendicular to the rotation axis of the transfer roller 15, the regulating portion A is located in the region L2 where the intermediate transfer belt 8 is located, among the regions L1 and L2 divided by the tangent line L of the transfer nip portion SN. Meanwhile, the static eliminator B is located on the side of the region L1 where the secondary transfer roller 15 is located, among the regions L1 and L2 divided by the tangent line L of the secondary transfer roller 15 and the intermediate transfer belt 8. The downstream end of the inclined guide portion 32a in the conveyance direction of the recording material S is located in the region L1 where the transfer roller 15 is located, among the regions L1 and L2 divided by the tangent line L of the transfer nip portion SN.

[0045] <Evaluation test> In order to confirm the effect of this embodiment, recording material S was fed under an environment of room temperature 15°C and humidity 10%, where blank spots are likely to occur, and blank spots and conveyance performance were evaluated. Three types of image forming apparatuses were prepared for evaluation: Example 1, and Comparative Examples 1 and 2, which are conventional configurations.

[0046] The configuration of Comparative Example 1 will be described with reference to FIG. 3( a) and the configuration of Comparative Example 2 with reference to FIG. 3( b). In Comparative Example 1 and Comparative Example 2, a conveyance guide 32 having a conventional restricting portion A and a contact electrode 29 having a charge eliminating portion B are arranged as separate components. In Comparative Example 1, the charge eliminating portion B is located in the same position as in Example 1, and the restricting portion A is located close to the nip to a degree that does not cause interference between the contact electrode 29 and the conveyance guide 32, even when individual variations are taken into consideration. Specifically, in Comparative Example 1, the distance between the restricting portion A and the entrance SNa of the nip portion SN is 9 mm, and the distance between the charge eliminating portion B and the entrance SNa of the nip portion SN is 3 mm. On the other hand, in Comparative Example 2, the restricting portion A is located in the same position as in Example 1, and the charge eliminating portion B is located close to the nip to a degree that does not cause interference between the contact electrode 29 and the conveyance guide 32, even when individual variations are taken into consideration. Specifically, in Comparative Example 1, the distance between the restricting portion A and the entrance SNa of the nip portion SN is 5 mm, and the distance between the charge eliminating portion B and the entrance SNa of the nip portion SN is 6 mm.

[0047] The evaluation methods for white spots and conveyability are as follows.

[0048] Evaluation method for white spots: The recording material S is 163 g / m, which is prone to white spots. 2 We used Vitality (Xerox), paper size LTR, which had been left to dry in the above environment for a week. Then, using paper with a moisture content of 2.9% (measured with a Moistrex MX8000 paper moisture meter), we printed 10 full-black images. If there were no visible white spots on the printed toner image, it was considered OK; if even one of the images had white spots, it was considered NG.

[0049] Transportability evaluation method: The recording material S is 60 g / m 2 We used paper (CS-060F (Canon Inc.), paper size A4) that had been left to dry in the above environment for one week. When the moisture content reached 2.9% (measured with a paper moisture meter, Moistrex MX8000), 10 sheets of all-black images were printed. If no folds or scratches were found on the leading edge of the printed paper, it was deemed OK, but if even one sheet was found to have folds or scratches, it was deemed NG.

[0050] The evaluation results are shown in Table 1.

[0051] [Table 1]

[0052] As shown in Table 1, in Comparative Example 1, the white spots were OK, but the conveyance was NG. The reason for the NG conveyance was that although the static elimination unit B was close to the conveyance path of the recording material S, the regulating unit A was too far from the nip, causing the leading edge of the recording material S to come into contact with the static elimination unit B, resulting in part of the recording material S being broken.

[0053] In Comparative Example 2, unlike Comparative Example 1, the regulating unit A is close to the transfer nip SN, so the conveyance is OK, but the static elimination unit B is too far from the transfer nip SN, so the suppression of discharge by the electric field formed in the discharge region H is insufficient, and white spots are NG. In contrast to these, in Example 1, the static elimination unit B is moved closer to the transfer nip SN, so white spots are OK, and the regulating unit A is also moved closer to the transfer nip SN, so the conveyance variation of the recording material S is suppressed and the conveyance is OK.

[0054] As described above, with the embodiment of this invention, it is possible to suppress blank spots without impairing the paper conveyance performance under conditions where blank spots are likely to occur.

[0055] The configuration of the first embodiment has the following features.

[0056] The device includes an intermediate transfer belt 8 and a rotatable secondary transfer roller 15 that contacts the surface of the intermediate transfer belt 8 to form a transfer nip SN and transfers toner 90 supplied to the surface of the intermediate transfer belt 8 to a recording material S at the transfer nip SN. The device also includes a transport guide 32 that guides the recording material S to the transfer nip SN. The transport guide 32 has a regulating section A that contacts the surface of the recording material S opposite to the surface onto which the toner 90 is transferred, thereby guiding the recording material S to the transfer nip SN. The device also includes a charge eliminating section B that is located upstream of the transfer nip SN in the rotation direction of the secondary transfer roller 15 and faces the surface of the secondary transfer roller 15 upstream of the transfer nip SN in the movement direction of the recording material S, and that eliminates charge from the surface of the secondary transfer roller 15. The device also includes a secondary transfer power source 74 that applies a transfer voltage to the secondary transfer roller 15. The charge eliminating section B eliminates charge from the surface of the secondary transfer roller 15 at the opposing section while a transfer voltage is applied to the secondary transfer roller 15. The charge removal unit B is in contact with the secondary transfer roller 15 at the opposing portion. In a cross section perpendicular to the rotation axis of the secondary transfer roller 15, the regulating unit A is located in the region L2 where the intermediate transfer belt 8 is located, of the regions L1 and L2 divided by the tangent line L of the transfer nip SN. The conveying guide 32 further has an inclined regulating unit 32a that is inclined so as to approach the secondary transfer roller 15 from the regulating unit A. The downstream end of the inclined regulating unit 32a in the conveying direction of the recording material S is located in the region L1 where the secondary transfer roller 15 is located, of the regions L1 and L2 divided by the tangent line L of the transfer nip SN.

[0057] The secondary transfer opposing roller 12 is in contact with the inner surface of the intermediate transfer belt 8 and serves as an opposing member opposing the secondary transfer roller 15, and a transfer nip portion SN is formed by the intermediate transfer belt 8, the secondary transfer roller 15, and the secondary transfer opposing roller 12. The normal polarity of the toner 90 is opposite to the polarity of the transfer voltage. In a cross section perpendicular to the rotation axis of the secondary transfer roller 15, the charge removal portion B is located in the region L1 where the secondary transfer roller 15 is located, among the regions L1 and L2 divided by the tangent line L to the secondary transfer roller 15 and the intermediate transfer belt 8. The transfer voltage is of a magnitude that discharges with the charge removal portion B. The charge removal portion B forms an opposing portion B-B' upstream in the rotation direction of the secondary transfer roller 15 from the region where discharge occurs between the secondary transfer roller 15 and the intermediate transfer belt 8.

[0058] [Example 2] The configuration of the image forming apparatus to which Example 2 is applied is the same as that of Example 1, except that the static eliminator B is not in contact with the secondary transfer roller 15, and the transfer current is released from the secondary transfer roller 15 to the static eliminator B by discharging. Therefore, elements having the same or corresponding functions and configurations as those in Example 1 are denoted by the same reference numerals, and detailed explanations thereof will be omitted.

[0059] FIG. 4(a) is an enlarged view showing the vicinity of the secondary transfer portion formed by the intermediate transfer belt 8 and the secondary transfer roller 15 in this embodiment, and FIG. 4(b) is a schematic view of the conveying guide 32 in this embodiment as viewed from the direction of arrow X in FIG. 4(a).

[0060] As shown in FIG. 4A, the conveyance guide 32 of this embodiment includes a restricting portion A that protrudes toward the region L2 on the secondary transfer opposing roller 12 side, and an inclined guide portion 32a that is inclined so as to move away from the conveyance path of the recording material S as it moves downstream from the restricting portion A in the conveyance direction of the recording material S. Also, as shown in FIG. 4B, the downstream end of the inclined guide portion 32a in the conveyance direction of the recording material S includes a static eliminator B as a static eliminator. The static eliminator B is a static eliminator needle processed into a sawtooth shape, with the pitch C of adjacent sawtooth teeth being 3.5 mm, the length D of the sawtooth being 2 mm, and the tip angle E of the sawtooth being 18.9°. The static eliminator B was formed by punching the end of the conveyance guide 32, which is formed by forming a 1.0 mm thick iron sheet metal, into a sawtooth shape using a press, and then polishing the tip of the static eliminator B to a thickness of 0.1 mm. If the sawtooth pitch C is too wide, there will be areas where static electricity is not removed, and if it is too narrow, the effect of tip discharge will be reduced, so it is preferable that it be approximately 0.5 mm to 8.0 mm. Furthermore, static removal section B forms opposing section B-B' upstream in the rotation direction of secondary transfer roller 15 from area H where discharge occurs between secondary transfer roller 15 and intermediate transfer belt 8.

[0061] The tip of the charge elimination needle of this charge elimination unit B is positioned so that it faces the secondary transfer roller 15 while being non-contact with the secondary transfer roller 15, separated by a gap of 1 mm. The conveyance guide 32 is also electrically grounded via a conductive path 60. With this configuration, when the secondary transfer voltage is applied, ion current concentrates at the tip of the charge elimination needle of charge elimination unit B, causing a corona discharge between charge elimination unit B and charge elimination position B'. This lowers the potential on the surface of the secondary transfer roller 15, thereby suppressing whiteout. Charge elimination position B' is the position on the surface of the secondary transfer roller 15 closest to charge elimination unit B. As shown in Figure 4(a), the line B-B' is perpendicular to the tangent to the surface of the secondary transfer roller 15. The greater the current generated by this corona discharge, the lower the potential at charge elimination position B', resulting in a greater whiteout effect. Therefore, the distance between charge elimination unit B and charge elimination position B' must be closer than the corona discharge initiation distance between charge elimination unit B and charge elimination position B'. In order to obtain a sufficient effect of suppressing white spots, it is desirable that the amount of current flowing between the charge removal portion B and the charge removal position B' due to corona discharge is equal to or greater than the transfer current flowing through the transfer nip SN.

[0062] In this way, the conveyance guide 32 has the regulating portion A and the charge eliminating portion B, which increases the degree of freedom in placement, allowing the regulating portion A and the charge eliminating portion B to be located closer to the upstream side of the nip portion SN. In this embodiment, as in the first embodiment, the distance α between the regulating portion A and the entrance SNa of the nip portion SN is set to 5 mm. The distance β' between the charge eliminating position B' and the entrance SNa of the nip portion SN is set to 3 mm. The shorter this distance β', the lower the potential on the surface of the secondary transfer roller 15 in the discharge region H, thereby increasing the effect of suppressing white voids. Furthermore, in the configuration of this embodiment, the regulating portion A and the charge eliminating portion B are formed from the same material, which reduces manufacturing variations in the relative positional relationship between the regulating portion A and the charge eliminating portion B, which is more advantageous in achieving both white void suppression and conveyance performance.

[0063] Furthermore, by using a non-contact static eliminator such as a static eliminator needle as the static eliminator B in this embodiment, the transfer current is released to the static eliminator B without contacting the secondary transfer roller 15, which is more advantageous than the configuration of Example 1 in terms of durability of the secondary transfer roller 15. However, the configuration of this embodiment requires a gap to be provided between the static eliminator B and the secondary transfer roller 15, which may reduce the degree of freedom in design. Therefore, the static eliminator B can be selected to be contact or non-contact depending on the characteristics required by the image forming apparatus.

[0064] <Evaluation test> To confirm the effect of this embodiment, paper was passed through in an environment of room temperature 15°C and humidity 10%, and evaluation of white spots and conveyance performance was performed. Three types of image forming apparatuses were prepared for evaluation: Example 2 and Comparative Examples 3 and 4, which are conventional image forming apparatuses.

[0065] The configuration of Comparative Example 3 will be described with reference to FIG. 5( a) and the configuration of Comparative Example 4 with reference to FIG. 5( b). In Comparative Example 3 and Comparative Example 4, a conveyance guide 32 having a conventional restricting portion A and a discharge electrode 28 serving as a non-contact electrode having a static eliminator B are arranged as separate components. In Comparative Example 3, the static elimination position B' is located in the same position as in Example 2, and the restricting portion A is located close to the nip to a degree that does not cause interference between the non-contact electrode 28 and the conveyance guide 32, even when individual variations are taken into consideration. Specifically, the distance α between the restricting portion A and the entrance SNa of the nip portion SN in Comparative Example 1 is 11 mm, and the distance β' between the static elimination position B' and the entrance SNa of the nip portion SN is 3 mm. On the other hand, in Comparative Example 4, the restricting portion A is located in the same position as in Example 2, and the static eliminator B is located close to the nip to a degree that does not cause interference between the non-contact electrode 28 and the conveyance guide 32, even when individual variations are taken into consideration. Specifically, in Comparative Example 1, the distance between the restricting portion A and the entrance SNa of the nip portion SN was set to 5 mm, and the distance between the static eliminating portion B and the entrance SNa of the nip portion SN was set to 6 mm.

[0066] The evaluation methods for white spots and transportability were the same as those used in Example 1. The evaluation results are shown in Table 2.

[0067] [Table 2]

[0068] As can be seen from Table 2, in Comparative Example 3, white spots were acceptable, but the conveyance performance was unacceptable. The reason for the unacceptable conveyance performance is that although the charge eliminating unit B was close to the conveyance path of the recording material S, the regulating unit A was too far from the nip SN, causing the leading edge of the recording material S to come into contact with the charge eliminating unit B and part of the recording material S to break. In Comparative Example 4, unlike Comparative Example 3, the regulating unit A was close to the transfer nip SN, so the conveyance performance was acceptable, but white spots were unacceptable because the charge eliminating unit B was too far from the transfer nip SN. In contrast to these, in Example 2, it can be seen that white spots were acceptable by bringing the charge eliminating unit B closer to the transfer nip SN, and conveyance performance was also acceptable by reducing conveyance variation in the recording material S by bringing the regulating unit A closer to the transfer nip SN.

[0069] As described above, in the present embodiment as well, it was possible to suppress blank spots without impairing the paper conveyance performance under conditions where blank spots are likely to occur.

[0070] Although the transport guide 32 in this embodiment is configured such that only the charge eliminating section B is thin, the present invention is not limited to this configuration. For example, the thickness of the charge eliminating section B may remain at 1.0 mm. In this case, the discharge between the charge eliminating section B and the secondary transfer roller 15 becomes slightly unstable, resulting in a slightly inferior effect in suppressing whiteout compared to the configuration of this embodiment, but this can be selected according to the specifications. In this configuration, the strength of the restricting section A of the transport guide 32 is ensured while the discharge between the charge eliminating section B and the secondary transfer roller 15 is stabilized, thereby further suppressing whiteout. Furthermore, as long as the charge eliminating member is non-contact, it is not necessary to use a charge eliminating needle; instead, a charge eliminating brush or charge eliminating cloth can be selected as long as it can eliminate charge on the surface of the transfer member.

[0071] In the first and second embodiments, the transport guide 32 is formed from a metal sheet made of iron, but the present invention is not limited to such a configuration, and it is sufficient if the transport guide 32 has conductivity for dissipating the transfer current. For example, the transport guide 32 may be formed from a conductive resin.

[0072] Furthermore, the intermediate transfer belt 8 in the configuration of this embodiment is stretched by a secondary transfer opposing roller 12 and a tension roller 13, which serve as tensioning members and also serve to drive the intermediate transfer belt 8. However, as shown in FIG. 7, a configuration in which the intermediate transfer belt 8 is stretched by a three-axis configuration using a tension roller 11 as an assist roller is also applicable.

[0073] The effects of the present invention are not limited to image forming apparatuses that use an intermediate transfer belt, but similar effects can also be obtained in configurations such as monochrome image forming apparatuses in which toner is transferred directly from a photosensitive drum to a recording material.

[0074] The disclosure of the embodiments of the present invention includes the following configurations.

[0075] (Configuration 1) an image carrier; a rotatable transfer member that contacts the surface of the image carrier to form a transfer nip and transfers the toner supplied to the surface of the image carrier to a recording material at the transfer nip; a conveyance guide that includes: a guide portion that contacts a surface of the recording material opposite to the surface onto which the toner is transferred, thereby guiding the conveyance of the recording material to the transfer nip portion; and a discharge portion that discharges electricity from the surface of the transfer member at an opposing portion that is located upstream of the transfer nip portion in the rotation direction of the transfer member and that faces the surface of the transfer member upstream of the transfer nip portion in the movement direction of the recording material, and that guides the recording material so that it is conveyed to the transfer nip portion; a transfer voltage application unit that applies a transfer voltage to the transfer member, The image forming apparatus is characterized in that the charge eliminating section eliminates electricity from the surface of the transfer member at the opposing section while the transfer voltage is applied to the transfer member.

[0076] (Configuration 2) 2. The image forming apparatus according to claim 1, wherein the charge removing section contacts the transfer member at the facing section.

[0077] (Configuration 3) 2. The image forming apparatus according to claim 1, wherein the charge removing section is not in contact with the transfer member at the facing section.

[0078] (Configuration 4) The image forming apparatus according to any one of configurations 1 to 3, characterized in that, in a cross section perpendicular to the rotation axis of the transfer member, the guide portion is arranged in an area in which the image carrier is arranged, among areas divided by a tangent line of the transfer nip portion.

[0079] (Configuration 5) the conveying guide has an inclined guide portion inclined so as to approach the transfer member from the guide portion, The image forming apparatus according to configuration 4, characterized in that the downstream end of the inclined guide portion in the conveying direction of the recording material is arranged in an area in which the transfer member is arranged, among areas divided by tangents of the transfer nip portion.

[0080] (Configuration 6) a facing member that contacts the inner surface of the image carrier and faces the transfer member; 2. The image forming apparatus according to claim 1, wherein the transfer nip portion is formed by the image carrier, the transfer member, and the opposing member.

[0081] (Configuration 7) 2. The image forming apparatus according to claim 1, wherein the normal polarity of the toner and the polarity of the transfer voltage are opposite to each other.

[0082] (Configuration 8) The image forming apparatus according to configuration 1, characterized in that, in a cross section perpendicular to the rotation axis of the transfer member, the charge removal unit is arranged in the area where the transfer member is arranged among the areas divided by tangents to the transfer member and the image carrier.

[0083] (Configuration 9) 2. The image forming apparatus according to claim 1, wherein the static eliminator is configured by a static eliminator needle.

[0084] (Configuration 10) The image forming apparatus according to Configuration 1, wherein the transfer voltage is large enough to discharge the transfer voltage to the charge removing section.

[0085] (Configuration 11) The image forming apparatus according to configuration 1, wherein the neutralization unit forms the opposing portion upstream in the rotation direction of the transfer member from an area where discharge occurs between the transfer member and the image carrier.

[0086] (Configuration 12) The image forming apparatus according to Configuration 1, wherein the image carrier is an intermediate transfer belt.

[0087] (Configuration 13) The image forming apparatus according to Configuration 1, wherein the image carrier is a photosensitive drum. [Explanation of symbols]

[0088] 2 Photosensitive drum 8 Intermediate transfer belt 15 Secondary transfer roller 32 Transport guide 74 Secondary transfer voltage application unit A. Regulatory Department B. Static elimination section

Claims

1. an image carrier; a rotatable transfer member that contacts the surface of the image carrier to form a transfer nip and transfers the toner supplied to the surface of the image carrier to a recording material at the transfer nip; a conveyance guide that includes a guide portion that contacts a surface of the recording material opposite to the surface onto which the toner is transferred, thereby guiding the conveyance of the recording material to the transfer nip portion, and a discharge portion that discharges electricity from the surface of the transfer member at an opposing portion that is located upstream of the transfer nip portion in the rotation direction of the transfer member and that faces the surface of the transfer member upstream of the transfer nip portion in the movement direction of the recording material, and that guides the recording material so that it is conveyed to the transfer nip portion; a transfer voltage application unit that applies a transfer voltage to the transfer member, The image forming apparatus is characterized in that the charge eliminating section eliminates electricity from the surface of the transfer member at the opposing section while the transfer voltage is applied to the transfer member.

2. 2. The image forming apparatus according to claim 1, wherein the charge eliminating section contacts the transfer member at the facing section.

3. 2. The image forming apparatus according to claim 1, wherein the charge eliminating section is not in contact with the transfer member at the facing portion.

4. 4. An image forming apparatus according to claim 1, wherein, in a cross section perpendicular to the rotation axis of the transfer member, the guide portion is arranged in an area in which the image carrier is arranged, among areas divided by a tangent to the transfer nip portion.

5. the conveying guide has an inclined guide portion inclined so as to approach the transfer member from the guide portion, 5. An image forming apparatus according to claim 4, wherein the downstream end of the inclined guide portion in the conveying direction of the recording material is located in the area divided by the tangent of the transfer nip portion where the transfer member is located.

6. a facing member that contacts the inner surface of the image carrier and faces the transfer member; 2. The image forming apparatus according to claim 1, wherein the transfer nip portion is formed by the image carrier, the transfer member, and the opposing member.

7. 2. The image forming apparatus according to claim 1, wherein the normal polarity of the toner and the polarity of the transfer voltage are opposite to each other.

8. 2. The image forming apparatus according to claim 1, wherein, in a cross section perpendicular to the rotation axis of the transfer member, the charge removal unit is arranged in an area where the transfer member is arranged among areas divided by tangents to the transfer member and the image carrier.

9. 2. The image forming apparatus according to claim 1, wherein the static eliminator is configured by a static eliminator needle.

10. 2. The image forming apparatus according to claim 1, wherein the transfer voltage is a voltage that discharges the transfer voltage to the charge removing section.

11. 2. The image forming apparatus according to claim 1, wherein the charge eliminating section forms the facing section upstream in the rotation direction of the transfer member from a region where discharge occurs between the transfer member and the image carrier.

12. 2. The image forming apparatus according to claim 1, wherein the image carrier is an intermediate transfer belt.

13. 2. The image forming apparatus according to claim 1, wherein the image carrier is a photosensitive drum.

Images