JP2007248848A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a contact failure in a feeding path to the charging roller of a drum unit. <P>SOLUTION: A printer 200 has a drum unit DU that is inserted from a thorough-hole 64 in one side wall 60 of the main body of the printer and fitted between the side walls 60 and 62 of the main body. At one end of the charging case 80 of the drum unit DU, a power supply compression coil spring 142 is disposed such that when the drum unit DU is fitted between the side walls 60 and 62 of the main body, the spring 142 is brought into press contact with a terminal 150 disposed on the one side wall 60 of the main body. At the one end of the charging case 80, a conductive member 144 is also disposed so as to connect the power supply compression coil spring 142 and one of pressing compression coil springs 140, which is disposed at one end of the charging case 80. These members are formed from a single wire rod that is elastic and conductive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile machine, and more specifically, a pair of main body side walls disposed at a distance from each other, and a drum unit is inserted into one main body side wall. The present invention relates to an image forming apparatus including a pair of main body side walls in which through holes are formed and a drum unit that is inserted through the through holes and is mounted between the main body side walls.

A pair of main body side walls disposed at a distance from each other in the apparatus main body, a pair of main body side walls in which a through hole for inserting a drum unit is formed in one main body side wall, and a main body inserted through the through hole An image forming apparatus including a drum unit that is detachably mounted between side walls has already been disclosed (see Patent Document 1). A drum unit generally includes a photosensitive drum and a charging unit. When a charging roller is provided as a charging unit, the charging roller is pressed against the photosensitive drum by a spring unit.

In the image forming apparatus of the above form, it is necessary to apply a voltage to the charging roller by connecting the charging roller and a power source provided in the apparatus main body in a state where the drum unit is mounted between the side walls of the main body. For this purpose, a terminal connected to the power source is arranged on one side wall of the main body, and a terminal that is pressed against the terminal on one side wall of the main body when the drum unit is mounted between the main body side walls on the drum unit side. Further, it is conceivable to dispose a conductive member that connects a terminal disposed on the drum unit side and a metal shaft of the charging roller. However, there is a contact failure between the terminal on one side wall of the main body and the terminal of the drum unit, between the terminal of the drum unit and the conductive member, and between the conductive member and the shaft of the charging roller. The possibility increases. If a contact failure occurs in the power feeding path to the charging roller, a charging failure occurs on the surface of the photosensitive drum, and a desired good image cannot be obtained. In addition, the number of parts is large, resulting in an increase in cost.
Japanese Patent Laid-Open No. 2004-294631

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel image forming apparatus capable of preventing a problem that a contact failure occurs in a power feeding path to a charging roller in a drum unit and reducing the cost by minimizing the number of parts constituting the power feeding path. Is to provide

According to the present invention,
A pair of main body side walls disposed at a distance from each other, the pair of main body side walls having a through hole formed in one main body side wall, and a drum unit inserted between the through hole and mounted between the main body side walls In an image forming apparatus comprising:
A power supply terminal connected to a power source is disposed on one side wall of the main body, a charging unit extending in the axial direction of the photosensitive drum and the photosensitive drum is disposed in the drum unit, and the charging unit is non-conductive. Charging case and a charging roller rotatably supported via a conductive bearing member attached to both ends of the charging case, and between the both ends of the charging case and the corresponding bearing member Is provided with a compression coil spring for pressing the bearing member so that the charging roller is pressed against the photosensitive drum, and one end of the charging case protrudes in a direction perpendicular to the axial direction. And a power supply compression coil spring that is disposed so as to protrude from the protrusion toward the other end of the charging case and is pressed against the terminal when the drum unit is mounted between the side walls of the main body. Compression coil And a conductive member for connecting one of the compression coil springs for pressing disposed on the one end side of the charging case, and the compression coil spring for feeding, the one compression coil spring for pressing, and the conductive member are elastic. And is formed from a single wire having conductivity,
An image forming apparatus is provided.
It is preferable that a cleaning roller for cleaning the surface of the charging roller is rotatably supported by the pair of bearing members.

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

Referring to FIG. 7, a laser printer (hereinafter simply referred to as “printer”) 200 that is an image forming apparatus includes a printer main body 10 that is a substantially rectangular parallelepiped apparatus main body. A paper discharge tray 14 is formed on the upper surface 12 of the printer main body 10. A paper discharge port 16 is formed in a vertical step formed between the upstream end (left end in FIG. 7) of the paper discharge tray 14 in the paper discharge direction and the upper surface 12.

A photosensitive drum 18 is disposed at a substantially central portion in the printer main body 2. Around the photosensitive drum 18, a charging unit 20, a developing device 22, a transfer roller 24, a cleaning device 26, a static eliminator (not shown), and the like are disposed. The photosensitive drum 18, the charging unit 20, and the cleaning device 26 are disposed in a drum unit DU described later. A laser scanning unit LSU that converts input image information into laser light and irradiates the surface of the photosensitive drum 18 is disposed at an upper position in the printer main body 10. On the front side surface (right side surface in FIG. 7) side of the printer body 2, a manual paper feed tray 28 is disposed so as to protrude obliquely upward. The paper feed tray 28 can be folded so as to extend along the front side surface of the printer main body 2.

A main transport path 30 for transporting paper is disposed at a substantially central portion in the vertical direction in the printer main body 2, and a paper feed cassette 32 is disposed at the lower end of the front side surface in FIG. It is mounted so that it can be pulled out. The main conveyance path 30 passes between the photosensitive drum 18 and the transfer roller 24 and extends almost horizontally in the tangential direction thereof. The upstream end region of the main transport path 30 is inverted downward and connected to the paper feed cassette 32. On the upstream side of the photosensitive drum 18 in the main conveyance path 30, a separation roller pair 34, a conveyance roller pair 36, and a registration roller pair 38 are arranged along the main conveyance path 30 in that order from upstream to downstream. Has been. In the paper feed cassette 32, there are disposed a bottom plate 42, which is a paper placement plate supported at one end so as to be rotatable around the shaft 40, and a compression coil spring (not shown) that pushes the other end of the bottom plate 42 upward. ing. The upper surface of the front end portion of the sheet (not shown) stacked and accommodated on the bottom plate 42 is pressed against a pickup roller 44 provided in the printer main body 2.

A fixing unit 50 is disposed on the downstream side of the photosensitive drum 18 in the main conveyance path 30. The fixing unit 50 includes a fixing device 52 and a conveyance roller pair 54 disposed on the downstream side of the fixing device 52. The fixing device 52 includes a heat fixing roller 52A and a pressure roller 52B pressed against the heat fixing roller 52A. A discharge conveyance path 56 is disposed on the downstream side of the fixing unit 50. The discharge conveyance path 56 extends in the vertical direction along the upper end region on the inner side in the upper end region of the rear side surface (left side surface in FIG. 1) which is one side surface of the printer main body 2. A pair of conveyance rollers 57 is disposed at a substantially central position in the vertical direction of the discharge conveyance path 56. The upper end portion of the discharge conveyance path 56 is curved upward and toward the front side surface 4 toward the discharge port 16, and a discharge roller pair 58 is disposed at the upper end (downstream end) of the discharge conveyance path 56. Yes.

As is well known, while unillustrated paper fed from the paper feed cassette 32 is transported through the main transport path 30, a toner image is recorded on one side (upper surface), and the toner image is fixed by the fixing device 52. The The sheet on which the toner image is fixed is conveyed to the discharge conveyance path 56 by the conveyance roller pair 54. The sheet conveyed to the discharge conveyance path 56 is discharged face-down to the sheet discharge tray 14 through the sheet discharge port 16 by the pair of conveyance rollers 57 and the pair of discharge rollers 58.

Referring to FIG. 6, a pair of main body side walls 60 and 62 are disposed on the printer main body 10 so as to face each other with a space therebetween. A through hole 64 for inserting a drum unit DU is formed in one main body side wall 60. The drum unit DU is inserted through the through hole 64 and supported between the main body side walls 60 and 62. The mounting of the drum unit DU will be described later.

Referring to FIGS. 1 and 2, the drum unit DU includes a unit frame UF including a pair of unit side walls 66 and 68 that face each other with a space therebetween. The unit frame UF that can be formed from an appropriate synthetic resin is provided with a photosensitive drum 18, a charging unit 20, and a cleaning device 26, as shown in FIG. The photosensitive drum 18 is rotatably supported by a shaft 70 fixed between the unit side walls 66 and 68. Since the cleaning device 26 is disposed in the unit frame UF on the back side of the photosensitive drum 18 in FIGS. 1 and 2, it does not appear in FIGS. 1 and 2. The cleaning device 26 includes a cleaning roller, a cleaning blade, and a toner recovery roller, which are shown without reference numerals in FIG. The cleaning roller and the cleaning blade are in contact with the surface of the photosensitive drum 18.

2 to 4, the charging unit 20 includes a charging case 80. The charging case 80, which can be formed of a suitable non-conductive synthetic resin (for example, polycarbonate), has a top wall 82 that is elongated in a straight line with a substantially constant width in the longitudinal direction, A pair of side walls 84 and 86 extending downward from both sides so as to face each other and a pair of end walls 88 and 90 extending downward from both longitudinal ends of the top wall 82 are provided, and generally open downward. It has a box shape. An upper end region 89 (existing at one end of the charging case 80) outside the end wall 88 of the charging case 80 has a certain width in the direction matching the longitudinal direction of the charging case 80 and matches the width direction of the charging case 80. In this direction, the other side wall 86 extends beyond the one side wall 84 and extends outward at a right angle. The upper end region 89 is a substantially rectangular top wall 92 and one end of the top wall 92, and extends downward from one end far from the end wall 88 and extends parallel to the end wall 88. The other end wall 96 extending downwardly from the other end of the region extending from the side wall 84 and extending in parallel to the end wall 94, A side wall 98 extending downward from the tip, which is one side of the wall 92, and another side wall 100 extending downward from the other side of the top wall 92 are provided. The other side wall 100 exists on the extension of the side wall 86. A portion of the upper end region 89 that protrudes from the side wall 84 at a right angle to the side outward constitutes a protrusion 91. The top wall 92 in the region of the upper end region 89 that does not extend laterally outward from one side wall 84 exists on the extension of the top wall 82.

On the end wall 94 of the upper end region 89, a rectangular flat plate-like projecting piece 102 that extends from the end wall 94 outward in the longitudinal direction of the charging case 80 is formed. The lowermost surface of the upper end region 89 is substantially on the same plane. A protrusion 104 that extends from the end wall 88 in the longitudinal direction of the charging case 80 is formed on the end wall 88 below the one end 89 of the charging case 80. The protrusion 104 has a rectangular cross section, and is formed substantially in a V shape so that the tip portion becomes narrower toward the tip when viewed from a plane. The end piece 90 (FIG. 2) of the charging case 80 is provided with a locking piece 106 having elasticity. The locking piece 106 has a rectangular flat plate body elongated in the vertical direction when the outer surface of the end wall 90 is viewed in the longitudinal direction of the charging case 80, and only the lower end is integrally connected to the end wall 90. Is formed to be elastically displaceable in the longitudinal direction. The upper end of the main body of the locking piece 106 is provided with a locking protrusion having an upper surface extending horizontally outward in the longitudinal direction and an inclined surface inclined downward from the tip of the upper surface toward the main body. .

Referring to FIG. 5, charging roller 110 and cleaning roller 112 are rotatably supported by a pair of bearing members 114 (only one bearing member 114 is shown in FIG. 5). Since each of the bearing members 114 has substantially the same shape and size as each other, the configuration of the one bearing member 114 will be described.

A bearing member 114 integrally formed from a suitable synthetic resin (for example, polyacetal) having conductivity is a rectangular plate-shaped main body 116 and upper bearing portions 118 disposed at the upper end portion and the lower end portion of the main body 116, respectively. And a lower bearing portion 120. The upper bearing portion 118 has a long hole shape that is long in the vertical direction. The lower bearing portion 120 has an arc shape larger than a semicircle and is opened downward. The upper bearing portion 118 and the lower bearing portion 120 protrude from both surfaces of the main body 116, and their axes are parallel to each other and extend in a direction perpendicular to both surfaces of the main body 116. An upper protrusion 122 and a lower protrusion 124 that extend outward are formed on the upper end and the lower end on both sides of the main body 116, respectively. Each of the upper protrusions 122 having substantially the same shape and size as each other has a lower surface 122a extending perpendicularly from a corresponding side surface of the main body 116, and an inclination from the tip of the lower surface 122a toward the upper end surface 116a of the main body 116. And an inclined surface 122b. The width of each of the lower protrusions 124 having substantially the same shape and size as each other is wider than the width of the upper protrusion 122 (the axial width of the upper bearing portion 118 and the lower bearing portion 120). A protrusion 117 extending upward is formed at the center of the upper end surface 116 a of the main body 116.

The charging roller 110 and the cleaning roller 112 include metal shafts 110a and 112a, respectively. Both ends of the shaft 110a of the charging roller 110 are rotatably supported by the lower bearing portion 120 of the corresponding bearing member 114. The charging roller 110 includes a shaft 110 and a conductive elastic layer (synthetic rubber layer) 110b that covers the periphery of the shaft 110 with a substantially constant thickness. Both end portions of the shaft 112a of the cleaning roller 112 are supported by the upper bearing portion 118 of the corresponding bearing member 114 so as to be rotatable and vertically movable. The cleaning roller 112 includes a shaft 112a and a brush 112b that covers the periphery of the shaft 112a. The outer peripheral portion of the brush 112 b of the cleaning roller 112 is brought into contact with the surface of the elastic layer 110 b of the charging roller 110.

3 and 4, a pair of guide ribs 130 extending from the lower end to the top wall 82 are formed inside the side walls 84 and 86 at one end (the left end in FIGS. 1 and 2) of the charging case 80. Has been. In each pair of guide ribs 130, each of the guide ribs 130 extends linearly parallel to each other. The pair of guide ribs 130 on the side wall 84 and the pair of guide ribs 130 on the side wall 86 face each other. A through-hole 132 extending downward from the top wall 82 is formed between the pair of guide ribs 130 on the side walls 84 and 86. The lower end of each of the through holes 132 is located slightly below the center of the side walls 84 and 86 in the vertical direction. Although not shown, a pair of guide ribs 130 and through holes 132 having substantially the same configuration as that at one end of the charging case 80 are also formed on the side walls 84 and 86 at the other end of the charging case 80. ing.

When the upper protrusion 122 and the lower protrusion 124 of each of the bearing members 114 on which the charging roller 110 and the cleaning roller 112 are supported are inserted between the two pairs of guide ribs 130 formed at both ends of the charging case 80, The tip of the lower surface 122a of each protrusion 122 protrudes on the lower end surface 132a of the corresponding through hole 132 (FIG. 3). The charging roller 110 and the cleaning roller 112 are rotatably supported by the charging case 80 via bearing members 114. Such an operation is performed while elastically deforming so as to widen the interval between the side walls 84 and 86 at the front ends of the upper protrusions 122 from the front ends of the side walls 84 and 86 of the charging case 80 to the lower end surfaces of the corresponding through holes 132. (The interval between the tips of the upper protrusions 122 is formed slightly wider than the interval between the corresponding inner surfaces of the side walls 84 and 86). The lower end region of the surface of the charging roller 110 is positioned so as to protrude downward from the lower ends of the side walls 84 and 86 of the charging case 80.

Referring to FIGS. 3 to 5, the bearing member 114 is urged between the both ends of the charging case 80 and the corresponding bearing member 114 so that the charging roller 110 is pressed against the photosensitive drum 18. A pressing compression coil spring 140 is disposed (in FIGS. 3 to 5, only one pressing compression coil spring 140 is shown). A protrusion 134 (FIG. 3) extending downward is formed on the lower surface of the top wall 82 at one end of the charging case 80 and at the central portion of the lower surface of the region where each pair of guide ribs 130 is opposed to each other. One end of the compression coil spring 140 for pressing one side that biases the member 114 is fitted and held by the protrusion 134. At the other end (the right end in FIG. 2) of the charging case 80, one end of the other pressing compression coil spring 140 (not shown) is formed on the upper end surface 116a of the main body 116 (FIG. 5) of the other bearing member 114 (not shown). The projection 117 is fitted and held.

The charging case 80 is connected to one end of the charging case 80 by a power supply compression coil spring 142, the power supply compression coil spring 142, and one pressing compression coil spring 140 disposed on one end of the charging case 80. 144. The power supply compression coil spring 142 is disposed so as to protrude from the protruding portion 91 of the charging case 80 toward the other end of the charging case 80. As shown in FIGS. 3 and 4, a protrusion 146 extending from the inner surface of the side wall 94 toward the other end of the charging case 80 is formed on the side wall 94 of the protrusion 91. A through hole 148 is formed on the side wall 96 of the protrusion 91 and on the extension of the protrusion 146. One end of the power feeding compression coil spring 142 is wound around the protrusion 146, and the other end extends through the through hole 148 from the side wall 96 toward the other end of the charging case 80.

One end of one of the compression coil springs for pressing 140 (one end closest to the inner surface (lower surface) of the top wall 82 fitted and held by the projection 134) and one end of the compression coil spring 142 for feeding (projection) The conductive member 144 is connected to one end of the side wall 94 that is wound around the inner wall 146 around the inner surface. The conductive member 144 extends from one end of one of the compression coil springs 140 for pressing to the inside of the side wall 94 of the upper end region 89 along the inner side surfaces (lower surface) of the top walls 82 and 92, and then the side wall 94 and the top wall 92. Extending to one end of the power supply compression coil spring 142. A gap through which the conductive member 144 can pass is formed between the end wall 88 and the top wall 82 of the charging case 80. The feeding compression coil spring 142, the one pressing compression coil spring 140, and the conductive member 144 are made of a single wire having elasticity and conductivity. In the embodiment, a single wire having elasticity and conductivity is formed from a single wire made of metal, for example, a wire made of one SUS304CSP.

With reference to FIG. 2, regions above the photosensitive drum 18 in the side walls 66 and 68 of the unit frame UF are formed so as to face each other in the axial direction of the photosensitive drum 18. A high side wall 66A and a low side wall 66B are formed on one side wall 66 in the upper region. The low side wall 66B exists on the inner side in the axial direction with respect to the high side wall 66A. A horizontal step 66C is formed between the high side wall 66A and the low side wall 66B. A hole (not shown) for receiving the protruding piece 102 formed on the end wall 94 (FIGS. 3 and 4) of the charging case 80 is formed at the boundary between the high side wall 66A and the horizontal step portion 66C. Further, a hole (not shown) for receiving the protrusion 104 formed on the end wall 88 (FIGS. 3 and 4) of the charging case 80 is formed in the lower side wall 66B. The other side wall 68 in the upper region is formed with a locking hole (not shown) into which the locking piece 106 (FIG. 1) of the charging case 80 is so-called snap fit.

2 to 4, the charging unit 20 configured as described above has a protruding piece 102 (FIG. 3 and FIG. 4) formed at the upper end at one end of the charging case 80, and a horizontal wall 66 </ b> A and a horizontal side. The charging case is inserted into a hole (not shown) formed at the boundary with the step 66C and the protrusion 104 (FIGS. 3 and 4) of the charging case 80 is inserted into a hole (not shown) formed on the low side wall 66B. When the other end of 80 is lowered along the inside of the side wall 68, the locking piece 106 (FIG. 1) of the charging case 80 is locked after being elastically deformed in a locking hole (not shown) of the other side wall 68 (so-called). Snap fit). The lower end surface (existing on a substantially common plane) of the upper end region 89 (FIGS. 3 and 4) formed on one end side of the charging case 80 is placed on the horizontal step portion 66C. As described above, the charging unit 20 is mounted substantially detachably between the side walls 66 and 68 of the unit frame UF so as to be detachable. Since the charging roller 110 is slightly pushed up against the spring force of each of the pressing compression coil springs 140 by the photosensitive drum 18, the charging roller 110 is driven by the spring force of each of the pressing compression coil springs 140. The photosensitive drum 18 is pressed. The shaft 110a of the charging roller 110 (FIG. 5) and the shaft 112a of the cleaning roller 112 are arranged so that a gear (not shown) can rotate integrally and mesh with each other, and the shaft 110a of the charging roller 110 (FIG. 5). Is engaged with the drive gear 18a (FIGS. 1 and 2) of the photosensitive drum 18.

Referring to FIGS. 1, 5, and 6, drum unit DU is inserted in a horizontal direction from through hole 64 in one main body side wall 60 with side wall 68 as the head. The shaft 70 of the photosensitive drum 18 protruding from the side wall 68 is rotatably fitted and supported on a bearing (not shown) disposed on the other main body side wall 62. Further, a locking pin 68P (FIG. 1) protruding from the side wall 68 is fitted and locked in a locking hole (not shown) provided in the other main body side wall 62. In this way, the side wall 68 of the drum unit DU is detachably supported by the other main body side wall 62. The photosensitive drum 18 is drivingly coupled to a driving gear disposed on the other main body side wall 62 via a coupling (not shown). A plurality of locking pins and hooks (not shown) are arranged on the side wall 66 of the drum unit DU. Then, each of the locking pins is fitted and locked in a corresponding locking hole (not shown) provided on one side wall 60 of the main body, and the locking pin (not shown) provided on the one side wall 60 of the main body. It is locked to the part. In this way, the side wall 66 of the drum unit DU is detachably supported by one main body side wall 60.

On one side wall 60 of the main body, a power supply terminal 150 (FIG. 5) connected to a power source (not shown) provided in the printer main body 2 is provided. When the drum unit DU is mounted between the main body side walls 60 and 62, the power supply compression coil spring 142 disposed in the charging case 80 of the drum unit DU is pressed against the terminal 150 disposed on one main body side wall 60. (In FIG. 5, the arrow indicates the direction in which the terminal 150 relatively presses the power supply compression coil spring 142). As a result, a predetermined voltage is applied to the charging roller 110 from a power source (not shown) disposed in the printer main body 2 via the compression coil spring 142 for feeding, the conductive member 144, the compression coil spring 140 for pressing one side, and the bearing member 144. It becomes possible to apply. The power supply compression coil spring 142, the one pressing compression coil spring 140, and the conductive member 144 are formed of a single wire having elasticity and conductivity, so that the charging roller 110 in the drum unit DU is connected to the charging roller 110. It is possible to prevent a problem that a contact failure occurs in the power supply path, and to reduce the cost by minimizing the number of parts constituting the power supply path. Further, since the cleaning roller 112 that cleans the surface of the charging roller 110 is rotatably supported by the pair of bearing members 144, the cleaning roller 112 can have the same potential as the charging roller 110. As a result, leakage of the voltage applied to the charging roller 110 is prevented, and uneven charging on the surface of the photosensitive drum 18 can be prevented. When the cleaning roller 112 is not provided, only the charging roller 110 is supported by the pair of bearing members 144.

FIG. 8 is a perspective view of a drum unit provided in the laser printer shown in FIG. 7. FIG. 2 is a perspective view showing the charging unit separately in the drum unit shown in FIG. 1. It is a perspective view which shows the one end part of the charging unit shown in FIG. It is a perspective view which shows the inner side of the charging unit shown in FIG. FIG. 4 is a perspective view schematically showing a main part of the charging unit shown in FIG. 3. FIG. 2 is a perspective view illustrating a state where the drum unit illustrated in FIG. 1 is mounted on a main body side wall of a printer main body. 1 is a cross-sectional view showing the overall configuration of an embodiment of a laser printer configured according to the present invention.

Explanation of symbols

2: Printer main body 18: Photoconductor drum 20: Charging unit 60, 62: Main body side wall 64: Through hole 66, 68: Side wall of charging case 80: Charging case 91: Projecting portion 110 of charging case 110: Charging roller 112: Cleaning roller 114: Bearing member 140: Pressing compression coil spring 142: Feeding compression coil spring 144: Conductive member 150: Feeding terminal 200: Laser printer DU: Drum unit UF: Unit frame

Claims (2)

A pair of main body side walls disposed at a distance from each other, the pair of main body side walls having a through hole formed in one main body side wall, and a drum unit inserted between the through hole and mounted between the main body side walls In an image forming apparatus comprising:
A power supply terminal connected to a power source is disposed on one side wall of the main body, a charging unit extending in the axial direction of the photosensitive drum and the photosensitive drum is disposed in the drum unit, and the charging unit is non-conductive. Charging case and a charging roller rotatably supported via a conductive bearing member attached to both ends of the charging case, and between the both ends of the charging case and the corresponding bearing member Is provided with a compression coil spring for pressing the bearing member so that the charging roller is pressed against the photosensitive drum, and one end of the charging case protrudes in a direction perpendicular to the axial direction. And a power supply compression coil spring that is disposed so as to protrude from the protrusion toward the other end of the charging case and is pressed against the terminal when the drum unit is mounted between the side walls of the main body. Compression coil And a conductive member for connecting one of the compression coil springs for pressing disposed on the one end side of the charging case, and the compression coil spring for feeding, the one compression coil spring for pressing, and the conductive member are elastic. And is formed from a single wire having conductivity,
An image forming apparatus. The image forming apparatus according to claim 1, wherein a cleaning roller for cleaning the surface of the charging roller is rotatably supported by the pair of bearing members.

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