JP2011203502A - Image forming apparatus and electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for stably electrifying a photoreceptor drum by an electrifying film.SOLUTION: The image forming apparatus includes an electrostatic latent image carrier, on the surface of which an electrostatic latent image is formed, an electrifying member which electrifies the electrostatic latent image carrier, and an energizing member which energizes the electrifying member to the electrostatic latent image carrier side, and is provided with an adhesion preventing means for preventing adhesion of toner and external additive to a surface of the electrifying member.

Description

  The present invention relates to an image forming apparatus such as an electrophotographic printer, a copying machine, and a facsimile, and a charging device, and more particularly to a charging film for charging a photosensitive drum.

  A conventional image forming apparatus includes a charging film for charging a photosensitive drum. The charging film is supported by a conductive support plate at one end, and a part of the free end contacts the photosensitive drum. As a result, the photosensitive drum is charged (for example, see Patent Document 1).

JP-A-4-249270 (paragraph "0029", FIG. 2)

  However, since the conventional technology described above does not include a cleaning mechanism for removing foreign matter or the like on the surface of the charging film, the external additive detached from the toner adhering to the photosensitive drum is not contained in the charging film. When adhering to the surface, the external additive remains on the surface of the charging film and gradually accumulates on the surface of the charging film, and the area where the external additive is deposited contacts the photosensitive drum. However, there is a problem that the photosensitive drum cannot be charged satisfactorily at the contacted place, and the printing quality is deteriorated due to the occurrence of vertical stripes when printing on the printing paper.

  An object of the present invention is to provide means for solving the above problems.

  In order to solve the above-described problems, the present invention provides an electrostatic latent image carrier on which an electrostatic latent image is formed, a charging member for charging the electrostatic latent image carrier, and the charging member as the static member. An image forming apparatus including an urging member that urges toward the electrostatic latent image carrier, the image forming apparatus having an adhesion preventing unit that prevents adhesion of toner and an external additive to the surface of the charging member. .

  As a result, the present invention provides an effect that the photosensitive drum can be stably charged and the occurrence of printing defects can be prevented.

Explanatory drawing which shows the image forming apparatus of Example 1. Explanatory drawing which shows the part urged | biased by the sponge part of the charging film which comprises the charging part of FIG. 1 of Example 1. FIG. 1 is a block diagram illustrating an image forming apparatus according to a first exemplary embodiment. Explanatory drawing which shows a mode that the charging film of Example 1 was urged | biased by the sponge part to the photosensitive drum side. Explanatory drawing which shows the part urged | biased by the sponge part of the charging film of Example 2. Explanatory drawing which expanded the uneven surface of the charging film of Example 2.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram illustrating an image forming apparatus according to the first exemplary embodiment.

  In FIG. 1, reference numeral 1 denotes an image forming apparatus.

  Reference numeral 2 denotes a paper cassette having a stacking bottom surface for storing a plurality of print sheets as print media in a stacked state.

  Reference numeral 3 denotes a paper feed roller, which is disposed at a position facing the stacking bottom surface of the paper cassette 2 with the print paper to be stacked therebetween, and feeds and feeds the print paper stacked in the paper cassette 2.

  Here, the accumulation bottom surface of the sheet cassette 2 is configured to be able to lift the accumulated printing sheets by an elastic material such as a spring. For this reason, the uppermost printing paper accumulated on the bottom surface of the accumulation is pressed against the paper feed roller 3, and the printing paper is fed out from the paper cassette 2 by rotating the paper feed roller 3 as it is.

  Reference numeral 4 denotes a conveyance roller unit, which has a pair of conveyance rollers arranged opposite to each other, and holds the printing paper fed from the paper feed roller 3 and conveyed along the direction of arrow A by a conveyance path (not shown) between the conveyance rollers. Then, it is sent out to the downstream printer unit 8.

  A printer unit 8 includes a photosensitive drum 10 as an electrostatic latent image carrier, a developing roller 11 as a developer carrier facing the photosensitive drum 10, and a developer supply member that supplies toner to the developing roller 11. A toner supply roller 12; a toner cartridge 13 for supplying the toner contained therein; a developing blade 14 that is positioned between the toner cartridge 13 and the developing roller 11 and forms a thin layer of toner supplied on the developing roller 11; The printing paper is conveyed along the arrow B direction.

  The toner dropped from the toner cartridge 13 is supplied onto the developing roller 11 and thinned on the developing roller 11 by the developing blade 14.

  The photosensitive drum 10, the developing roller 11, and the toner supply roller 12 rotate in the directions of arrows shown on the respective parts in FIG.

  Reference numeral 9 denotes a charging unit, which includes a charging film 15, a holding member 16, and a sponge unit 17 which will be described later, and has a function of charging the photosensitive drum 10.

  Here, FIG. 2 is an explanatory view showing a portion urged by the sponge portion of the charging film constituting the charging portion of FIG. 1, wherein (a) shows the shape of the surface facing the photosensitive drum, and (b). Shows the shape on the side.

  In FIGS. 1 and 2, reference numeral 15 denotes a charging film as a charging member, which is disposed above the photosensitive drum 10 to charge the photosensitive drum 10, and has one end supported by a conductive holding member 16. The central portion is urged toward the photosensitive drum 10 by the sponge portion 17 that is an urging member, so that the free end contacts the photosensitive drum 10 so as to rotate.

  The sponge part 17 is a porous body, and has cavities and irregularities (cells) inside and on the surface, and has elasticity. The material is selected from polyurethane, polyethylene, polyamide, olefin, melamine or polypropylene, NBR, EPDM, natural rubber and styrene butadiene rubber, chloroprene, silicone, nitrile, or other foamable resin or rubber. The diameter of the cell provided in the sponge portion 17 is preferably 500 μm or less, and most preferably about 50 to 100 μm in diameter.

  As shown in FIG. 2B, the charging film 15 is formed by applying a conductive coating material having a thickness of 10 .mu.m to the surface of one side of a 50 .mu.m-thick PET film so as to be electrically connected to the power source and securing a discharge surface. A conductive layer 15a is provided.

  As shown in FIG. 2A, the charging film 15 has a length in the longitudinal direction (direction parallel to the axial direction of the photosensitive drum 10) of the conductive layer 15 a that is urged by the sponge portion 17 and contacts the photosensitive drum 10. The length in the short direction is 224 mm and 20 mm. Further, a length of 5 mm is secured as the length holding portion length of the portion attached to the holding member 16 shown in FIG.

  The charging film 15 is provided with a plurality of holes 15b having a diameter of 1 mm, which are uniformly arranged at a pitch of 2 mm on the surface in contact with the photosensitive drum 10, so as to be arranged in two rows in a staggered manner in the longitudinal direction. The hole 15b penetrates the charging film.

  In addition, although the hole 15b which is a through hole was 1 mm in diameter, it is not restricted to it, It is preferable that the maximum aperture is 5 mm or less.

  Further, on the rear side of the hole 15b (downstream direction in the rotation direction of the photosensitive drum 10), convex portions 15c having a diameter of 1 mm and a height of several μm to several tens of μm arranged uniformly at a pitch of 2 mm are staggered toward the longitudinal direction. A plurality are provided so as to be arranged in two rows.

  The height of the convex portion 15c is preferably 20 μm or less, and more preferably 10 μm or less. Moreover, although the convex part 15c was 1 mm in diameter, it is not restricted to this, It is preferable to form with a maximum diameter of 5 mm or less.

  The paint used to form the conductive layer 15a of the charging film 15 is a conductive member having conductivity, such as polyurethane, polyamide, polyimide, polyethylene, polycarbonate, polyolefin, polyurethane, polyvinylidene fluoride, vinyl chloride, phenol resin, Any conductive resin such as gold, silver, copper, iron, chromium, nickel, platinum, carbon black, or carbon fiber may be added to a synthetic resin such as acrylic or epoxy.

  If the resistance value is too low with respect to the conductivity imparted at that time, a leak that causes a current to flow locally into the pinhole or scratch on the photosensitive drum 10 occurs. On the other hand, if the resistance value is too high, the amount of current used for discharge decreases and the surface charge amount of the photosensitive drum 10 decreases, so the resistance value of the conductive layer 15a in the present invention is about 10E + 3 to 10E + 8 [Ω]. preferable.

  Although the present invention has been described as using a PET film as the base material of the charging film 15, if a base material such as polyester, polycarbonate, polyimide, ETEF, or PVDF is used, there is no need to provide the conductive layer 15a as the discharge surface. .

  In FIG. 1, reference numeral 18 denotes a cleaning blade, which is provided below the charging film 15, and has its tip end in contact with the outer peripheral surface of the photosensitive drum 10, whereby toner, foreign matter, and external additives remaining on the surface of the photosensitive drum 10. Scrap off etc.

  A collection container 19 is located below the cleaning blade 18 and accumulates toner scraped off by the cleaning blade 18.

  A print head 20 irradiates the surface of the photosensitive drum 10 with light from the LED toward the surface of the photosensitive drum 10 to expose the surface of the photosensitive drum 10 to generate an electrostatic latent image. Here, the voltage of the negative charge is weakened at the portion where the electrostatic latent image is formed.

  Reference numeral 21 denotes a transfer roller that transfers toner adhering to the photosensitive drum 10 to printing paper by a positive voltage and pressure contact force.

  A fixing device 22 is provided on the downstream side of the printer unit 8 in the conveyance direction of the printing paper, has a heat source such as a halogen lamp (not shown) and is in contact with the printing paper from above, and is pressed toward the fixing roller 23. A backup roller 24 that rotates under the pressure of the fixing roller 23 under pressure, and heats the fixing roller 23 by applying electric power to the heat source, and holds the printing paper between the backup roller 24 and the fixing roller 23. At the same time, the toner adhering to the printing paper is fused by the heat of the fixing roller 23 to fix the toner on the printing paper.

  Reference numeral 25 denotes a discharge roller. The toner is fixed by the fixing device 22, the printing paper conveyed along the direction of arrow C is conveyed to the discharge port 26, and the printing paper is in the direction indicated by arrow D, that is, an image forming apparatus. Drain out of 1.

  FIG. 3 is a block diagram illustrating the image forming apparatus according to the first embodiment.

  In FIG. 3, reference numeral 30 denotes a control unit composed of a microprocessor, ROM, RAM, input port, timer, and the like. The print data and the control command are received, and the entire sequence of the image forming apparatus 1 is controlled to perform the printing process.

  The control unit 30 includes a drum counter 30a that counts the number of rotations of the photosensitive drum 10 and a dot counter 30b that counts printing dots.

  A reception memory 32 temporarily stores print data input from a host device (not shown) via the interface control unit 31.

  An image data editing memory 33 receives the print data recorded in the reception memory 32 and stores the image data formed by editing the print data.

  A display operation unit 34 includes a display screen such as an LED and a switch for giving an instruction from the operator to the image forming apparatus.

  A sensor group 35 includes various sensors for monitoring the operation state of the image forming apparatus 1, such as a paper position detection sensor, a temperature / humidity sensor, and a density sensor.

  A charging film power source 36 applies a voltage to the charging film 15 of the charging unit 9 according to an instruction from the control unit 30 to charge the surface of the photosensitive drum 10.

  A developing roller power source 37 applies a predetermined voltage to the developing roller 11 in order to attach toner to the electrostatic latent image.

  Reference numeral 38 denotes a power supply for a supply roller, which applies a predetermined voltage to the toner supply roller 12 in order to supply toner to the developing roller 11.

  A transfer roller power supply 39 applies a predetermined voltage to the transfer roller 21 in order to transfer the toner image formed on the photosensitive drum 10 onto the printing paper.

  The charging film power source 36, the developing roller power source 37, and the supply roller power source 38 can change the voltage according to an instruction from the control unit 30.

  Reference numeral 40 denotes a fuse power supply, and the power is supplied to the old and new discrimination fuse 41 for discriminating whether or not the image forming apparatus 1 is in an unused state.

  A head drive control unit 42 controls the drive of the print head 20 based on the image data recorded in the image data editing memory 33.

  A fixing control unit 43 controls the operation of the fixing unit 22 such as energizing the heat source of the fixing unit 22 to fix the toner image transferred to the printing paper, so that the fixing unit 22 is kept at a constant temperature.

  A conveyance motor control unit 44 controls driving of a sheet conveyance motor 45 that rotates various rollers such as a paper feed roller 3, a conveyance roller unit 4, and a discharge roller 25 for conveying printing paper. In response to this instruction, the printing paper is conveyed or stopped at a predetermined timing.

  A drive control unit 46 controls driving of a drive motor 47 for operating the photosensitive drum 10.

  The operation of the above configuration will be described. First, printing processing by the image forming apparatus 1 will be described.

  When the control unit 30 receives print data from a host device (not shown) via the interface control unit 31, the control unit 30 temporarily stores the print data in the reception memory 32.

  The control unit 30 reads the print data, forms image data with the image data editing memory 33, and stores the image data in the image data editing memory 33.

  The control unit 30 reads the image data from the image data editing memory 33 and performs a printing operation based on the image data.

  Specifically, the control unit 30 transmits a signal for driving various rollers to the transport motor control unit 44, thereby operating the paper transport motor 45 at a predetermined timing to transport the printing paper.

  As a result, the printing paper is fed from the paper cassette 2 by the paper feed roller 3 and conveyed to the conveyance roller unit 4.

  In this way, the printing paper that has passed through the transport roller unit 4 reaches the printer unit 8, and toner is transferred to the printing paper by the photosensitive drum 10 and the transfer roller 21 with physical pressure and electrical electrostatic force. .

  The process up to toner transfer starts when the control unit 30 transmits control data to the drive control unit 46 and rotates the photosensitive drum 10 by the drive motor 47. At this time, the charged film 15 is placed on the surface of the photosensitive drum 10. Are in contact.

  The control unit 30 sends an operation instruction to the charging film power supply 36 to apply a negative voltage to the charging film 15 to charge the photosensitive drum 10, and further drives the print head 20 via the head drive control unit 42. Thus, the surface of the photosensitive drum 10 is exposed by the print head 20 to generate an electrostatic latent image.

  Further, toner adheres on the developing roller 11, and a thin layer of toner is formed on the developing roller 11 by the rotation of the developing roller 11 and the developing blade 14.

  When the toner image is transferred to the printing paper by the printer unit 8, the control unit 30 conveys the printing paper to the fixing device 22 and controls the fixing device 22 by the fixing control unit 43 to convert the toner image to the printing paper. Let it settle.

  The control unit 30 further conveys the printing paper and discharges it by the discharge roller 25, and ends the printing process.

  Next, the detailed operation of the charging film 15 will be described.

  The surface of the photosensitive drum 10 is charged by discharge from the conductive layer 15a of the charging film 15 that is in contact.

  Since the discharge phenomenon occurs when there is a certain gap between the surface of the photosensitive drum 10 and the conductive layer of the charged film, the discharge phenomenon is caused at a portion where the distance between the surface of the photosensitive drum 10 and the conductive layer is too far or in contact. Does not happen.

  The dischargeable gap length is determined by the voltage applied to the charging film 15, but is usually several μm to several tens of μm, and preferably about 5 μm.

  4A and 4B are explanatory views showing a state in which the charged film of Example 1 is urged toward the photosensitive drum by the sponge portion, where FIG. 4A is a side sectional view and FIG. 4B is a perspective sectional view.

  Since the charging film 15 is provided with holes 15b and convex portions 15c, the discharge gap indicated by the numbers 60 to 65 is provided between the surface of the photosensitive drum 10 and the charging film 15 as shown in FIG. Is formed.

  Foreign matter, transfer residual toner, and external additives detached from the toner are removed from the photosensitive drum 10 through the holes 15b, and the photosensitive drum 10 is precharged by the discharge gaps 61 and 62, and the discharge gaps 63 and 64 of the convex portion 15c. To charge the photosensitive drum 10 to a predetermined charge amount.

  For example, in the charging film 15 in which the hole 15b and the convex portion 15c are not formed, the discharge gaps 61 to 64 do not exist. Therefore, a discharge gap is formed at the locations indicated by 60 and 65 where the photosensitive drum 10 is charged.

  On the other hand, there are innumerable toners, external additives, and foreign matters that could not be removed by the cleaning blade 18 on the surface of the photosensitive drum 10. By repeating the printing operation, they are dammed up and deposited at the discharge gap 60 on the upstream side in the rotation direction of the photosensitive drum 10.

  In particular, since the external additive has a high resistance value so that electrons obtained by frictional charging do not escape, when it is deposited in the discharge gap 60, it acts as a high resistance layer between the photosensitive drum 10 and the conductive layer. This prevents charging of the surface of the drum 10.

  Further, since the discharge gap 65 existing on the downstream side in the rotation direction of the photosensitive drum 10 is on the free end side of the charging film 15, the free end of the charging film 15 in the printing process fluctuates, and the interval thereof fluctuates. Cannot be charged.

  As a result, in the charging film 15 in which the holes 15b and the convex portions 15c are not formed, the charging amount of the photosensitive drum 10 varies, and charging failure occurs. When the toner passes through the printer unit 8 and is fixed on the printing paper by the fixing unit 22 In addition, density unevenness, vertical stripes, etc. occur.

  Therefore, in the charging film 15 used in the present embodiment, the charge amount varies with respect to the discharge gaps 60 and 65 in the same manner as described above. The surface can be charged uniformly.

  First, toner and external additives on the surface of the photosensitive drum 10 that have passed through the discharge gap 60 are collected (cleaned) by attaching to the sponge portion 17 through the holes 15b as indicated by arrows in FIG. The At that time, the photosensitive drum 10 is also charged by the discharge gaps 61 and 62. However, since the photosensitive drum 10 also has a cleaning function, the charge amount itself is scarce. In particular, since the external additive accumulates in the discharge gap 62, the charge amount is scarce. Become.

  Thereafter, the photosensitive drum 10 can be stably charged by charging the photosensitive drum 10 with the discharge gaps 63 and 64 of the convex portion 15c for pure charging only.

  As described above, in this embodiment, the charging film is provided with a plurality of holes and protrusions to form discharge gaps at a plurality of locations, and the charging film is biased toward the photosensitive drum by the sponge portion. Since a plurality of discharge gaps can be provided between the drum and the charging film, the photosensitive drum can be stably charged.

  In addition, when the external additive detached from the toner adhering to the photosensitive drum adheres to the charged film, the external additive is collected from the hole of the charged film to the sponge portion, so that the external additive is added to the charged film. Accumulation can be prevented.

  In the present embodiment, the holes 15b and the convex portions 15c having a diameter of 1 mm are provided. However, uniform charging is possible if the holes and the convex portions have a diameter of 5 mm or less. However, in the case of holes and protrusions of 5 mm or more, although it is related to the moment of the charged film, the charged film is distorted and uniform charging cannot be performed due to uneven charging.

  Further, the pitch of the holes and convex portions to be arranged is preferably not more than twice the diameter, and is preferably arranged in a staggered manner. Regarding the shape of the hole and the convex portion, a circular shape is used in the present embodiment, but there are various shapes of the hole and the convex portion such as a triangle, a quadrangle, an ellipse, and a semicircle.

  Portions similar to those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  5A and 5B are explanatory views showing a portion urged by the sponge portion of the charging film of Example 2, wherein FIG. 5A shows the shape of the surface facing the photosensitive drum, and FIG. 5B shows the shape of the side surface. Yes.

  In FIG. 5, 50 is the charging film of Example 2, and a conductive paint for securing a surface that conducts electricity and discharges is provided on one side of a 50 μm-thick PET film on the entire surface of one side. It has a conductive layer 50a formed by applying 10 μm.

  The surface of the charging film 50 on the side of the conductive layer 50a is an irregular surface formed by randomly arranging minute irregularities, and the gaps and lengths of the irregularities on the irregular surface are random, but the depth of the grooves is irregular. The 10-point average roughness Rz in the longitudinal direction of the surface is required to be at least 30 μm or less. In this embodiment, the uneven surface is formed so that the average roughness Rz is about 5 to 15 μm.

  Here, FIG. 6 is an enlarged explanatory view of the uneven surface of the charging film of Example 2, and shows the uneven surface of the charging film 50 as viewed from the photosensitive drum 10 side. Therefore, as shown in FIG. 6, the tip of the convex portion 51 of the concavo-convex surface protrudes toward the photosensitive drum 10.

  Further, as shown in FIG. 6, the convex portion 51 extends so as to have a predetermined length along the rotation direction of the photosensitive drum 10, so that the concave portion 52 formed between the convex portions 51 also rotates the photosensitive drum 10. Extends along the direction.

  The operation of the above configuration will be described. When the conductive layer 50 a of the charging film 50 comes into contact with the photosensitive drum 10, the convex portion 51 of the conductive layer 50 a comes into contact with the surface of the photosensitive drum 10 to form a discharge gap between the concave portion 52 of the conductive layer 50 a and the photosensitive drum 10. Is done. Therefore, it becomes possible to charge the charging area of the photosensitive drum 10 by a predetermined amount.

  Next, accumulation of external additives and the like will be described. When the external additive is removed from the toner adhering to the photosensitive drum 10, the external additive is conveyed by the rotation of the photosensitive drum 10, and the convex where the photosensitive drum 10 and the charging film 50 come into contact as shown in FIG. 6. Deposited at the end of the portion 51.

  Further, the external additive that does not accumulate on the convex portion 51 moves while passing through the convex portion 51 along the rotation of the photosensitive drum 10 while being attached to the photosensitive drum 10, and is removed by the cleaning blade 18.

  As described above, in this embodiment, similarly to the effect of the first embodiment, charging failure caused by accumulation of toner, external additives, and foreign matters can be prevented, and stable charging can be performed. It is.

  In addition, since the unevenness is provided over the entire surface of the charging film facing the photosensitive drum, it is possible to prevent the external additive that is caught by the protrusion from being deposited in a certain amount or more.

  The present invention is applicable to electrophotographic copying machines, facsimiles, and the like.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper cassette 3 Paper feed roller 4 Conveyance roller part 8 Printer part 9 Charging part 10 Photosensitive drum 11 Developing roller 12 Toner supply roller 13 Toner cartridge 14 Developing blade 15, 50 Charged film 15a, 50a Conductive layer 15b Hole 15c Convex part 16 Holding member 17 Sponge part 18 Cleaning blade 19 Collection container 20 Print head 21 Transfer roller 22 Fixing device 23 Fixing roller 24 Backup roller 25 Discharge roller 26 Discharge port 30 Control part 30a Drum counter 30b Dot counter 31 Interface control part 32 Reception Memory 33 Image data editing memory 34 Display operation section 35 Sensor group 36 Power supply for charged film 37 Power supply for developing roller 38 Power supply for supply roller 39 Power supply for transfer roller 40 Fuse Power 41 old discrimination fuse 42 head drive controller 43 fixing control unit 44 conveying motor controller 45 paper conveying motor 46 drive control unit 47 drives the motor 60 to 65 discharge gap

Claims (11)

An electrostatic latent image carrier on which an electrostatic latent image is formed, a charging member that charges the electrostatic latent image carrier, and a biasing member that biases the charging member toward the electrostatic latent image carrier An image forming apparatus comprising:
An image forming apparatus comprising: an adhesion preventing unit that prevents adhesion of toner and an external additive to the surface of the charging member. The image forming apparatus according to claim 1.
The charging member is provided with a plurality of holes, and the biasing member is formed of a porous body capable of absorbing toner and external additives that have passed through the holes of the charging member, and the hole of the charging member and the biasing member An image forming apparatus characterized in that the adhesion preventing means is used. The image forming apparatus according to claim 1.
A convex portion having a predetermined length is provided along the rotation direction of the electrostatic latent image carrier on the surface of the charging member that faces the electrostatic latent image carrier, and the convex portion serves as the adhesion preventing means. An image forming apparatus. A charging device having a charging unit that contacts an electrostatic latent image carrier and a power source that applies a voltage to the charging unit,
The charging unit includes a conductive member, a holding unit that holds the conductive member, and a biasing member that biases the conductive member to the electrostatic latent image carrier.
The charging device according to claim 1, wherein the conductive member is provided with a through hole and a convex portion at a position where the conductive member comes into contact with the electrostatic latent image carrier. The charging device according to claim 4,
The charging device, wherein the through hole has a maximum diameter of 5 mm or less. The charging device according to claim 4,
The charging device according to claim 1, wherein the convex portion has a maximum diameter of 5 mm or less and a height of 20 μm or less. The charging device according to claim 4,
The charging device, wherein the convex portion is provided on the downstream side of the through hole with respect to the rotation direction of the electrostatic latent image carrier. The charging device according to claim 4,
The charging device according to claim 1, wherein a plurality of the through holes and the convex portions are provided over the image forming region. The charging device according to claim 4,
The charging device, wherein the through holes and the convex portions are provided in a staggered manner with respect to the longitudinal direction of the electrostatic latent image carrier. The charging device according to claim 4,
The charging device, wherein the urging member is made of a foam.   An image forming apparatus comprising the charging device according to claim 4.

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