JPH10104912A - Feed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably feed power, regardless of the motion of an image carrier contact member such as an electrified roller in the direction for nearing and parting from a photosensitive drum. SOLUTION: As a power feed route to an electrified roller 2, a route is formed along an area from a body power supply 20 to a shaft part 15 via a body receptacle 22, a body application spring 21, an electrode plate 18, a conductive presser spring 12 and a bearing 17 respectively. In addition, a similar power feed route is established along an area from the body power supply 20 to the conductive presser spring 12, and then reaching the shaft part 15 of the electrified roller 2 via a leaf spring 19 having one end in direct contact with the shaft part 15 and the other end positioned between the bearing 17 and the body application spring 21. When two power feed routes are established in that way, power can be properly fed via one of the routes, even upon the occurrence of a conductivity failure in the other route.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an image carrier contact member such as a charging member or a transfer member to which power is supplied from a power source while being in direct contact with the image carrier or via paper. The present invention relates to a power supply device that supplies power from a power supply to an image carrier contact member via a plurality of power supply paths.

[0002]

2. Description of the Related Art For example, a charging device which is a power supply device for charging a photosensitive drum as an image carrier by supplying power to a charging member is disclosed in Japanese Patent Application Laid-Open No. 5-303263 as shown in FIG. There is something. This charging device rotatably supports a shaft (core bar) 32 of a charging roller 31, which is a charging member having a surface in contact with the photoreceptor drum, with a bearing 33. An interposed spring 35 presses and biases the photosensitive drum (downward in the figure).

[0003] The spring 35 is formed of a conductive member. The electrode 34 is connected to a power supply 36. The electrode 34 has a tip portion 34 a that has the charging roller 31.
Directly in contact with the end face of the shaft portion 32. Thereby,
A first power supply path A is formed from the power supply 36 to the shaft 32 of the charging roller 31 via the tip 34a of the electrode 34.

[0004] A second power supply path B is also formed from the power supply 36 to the shaft 32 of the charging roller 31 through the electrode 34 and the spring 35. According to this charging device, since the two power supply paths A and B are provided as described above, even when one of the power supply paths becomes defective, power is reliably supplied to the charging roller 31 by the other power supply path. Can do it.

[0005]

However, in the case of the charging device as described above, there are several problems as follows. (1) When the charging roller 31 moves in the compression / extension direction of the spring 35 due to the urging force of the spring 35, the contact point between the tip 34a of the electrode 34 and the end surface of the shaft 32 of the charging roller 31 changes. The contact becomes unstable. (2) The electrode 34 may be deformed when the charging roller 31 moves up and down in FIG. (3) The electrode 34 may be deformed when the charging roller 31 is assembled (for example, in a unit state).

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a charging device in which power is supplied from a power source while being rotated by being directly or in contact with an image carrier by an urging force of an urging member. It is an object of the present invention to stably supply power to an image carrier contact member such as a roller even when the image carrier contact member is moved by the urging force of the urging member.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention achieves the above-mentioned objects, and is rotatably held and brought into contact with an image carrier directly or via a sheet by the urging force of an urging member, and power is supplied from a power supply. An image carrier contact member to be carried out, wherein power is supplied to the image carrier contact member from a power supply via a plurality of power supply paths, wherein one of the plurality of power supply paths is connected to the image carrier by the power supply. A power supply path for supplying power to the shaft section via a bearing formed of a conductive material that rotatably supports the shaft section of the contact member, and one other power supply path has one end directly connected to the shaft section. A power supply path extending through the power supply member contacting the bearing with the other end interposed between the bearing and a member supplied with power from the power supply to the shaft portion; In contact with the shaft of the body contact member The shaft portion and is obtained by the move integrally with the bearing.

In this case, the image carrier contact member may move toward the image carrier or move away from the image carrier by the urging force of the urging member. A power supply member that constitutes a power supply path in a state of being directly in contact with the shaft portion of the image carrier contact member; a bearing that rotatably supports the shaft portion of the image carrier contact member and the image carrier contact member; Since they move together, poor conduction does not easily occur. Therefore, stable power supply from the power source to the image carrier contact member can be performed.

The power supply member may be a leaf spring. Then, the one end portion directly contacts the shaft portion of the image carrier contact member due to the spring property of the material itself, so that more reliable contact can be obtained. Further, it is preferable that a member to be supplied with power from a power supply is formed of an elastic member, and the power supply member is pressed against the bearing by the urging force of the elastic member. Then, the power supply member is pressed against the bearing that rotatably supports the image carrier contact member by the biasing force of the elastic member, so that a special component for stopping the power supply member to the bearing is not particularly required. Therefore, the number of parts can be reduced. In addition, assemblability and decomposability are improved.

The image carrier contact member may be a charging member for charging the surface of the image carrier. In this case, the charging device is less likely to cause conduction failure, so that a more stable image can be provided. Further, the image carrier contact member may be a transfer member for transferring the toner image formed on the surface of the image carrier to a sheet. that way,
Since image transfer can be performed more stably, image quality can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a charging device showing an embodiment in which a power supply device according to the present invention is applied to a charging device, and FIG. 2 is a schematic diagram showing the periphery of an image forming unit of an image forming apparatus provided with the charging device. is there. A copying machine, which is an image forming apparatus showing the vicinity of an image forming unit in FIG. 2, has a contact charging system including a charging roller 2 serving as an image carrier contact member for charging a photosensitive drum (image carrier) 1 in a contact state. In the image forming apparatus, the charging roller 2 is driven to rotate at a constant speed in a direction indicated by an arrow E by rotating together with the photosensitive drum 1 rotating at a predetermined peripheral speed in a direction indicated by an arrow C in FIG. The surface 1a of the body drum 1 is uniformly charged to a predetermined potential.

The photosensitive drum 1 is driven by a motor which is driven to rotate via a drum drive timing belt, a drum drive pulley (both not shown), and the like. Due to the urging force of the spring 12, for example, a contact pressure of 10 g / cm (substantially line contact)
It is pressed against.

Around the photosensitive drum 1, in addition to the charging roller 2, a developing device 6, a transfer roller 7 constituting a transfer device, and a cleaning unit 8 are provided, respectively. Light is applied to the surface 1a of the photosensitive drum 1.
And the charged surface uniformly charged by the charging roller 2 is exposed to form an electrostatic latent image thereon, which is developed by the toner supplied by the developing sleeve 6a of the developing device 6 to form a toner. It becomes an image (visible image).

On the other hand, the transfer paper P, which is a paper housed in a paper cassette (not shown), is fed one by one by a paper feed roller which rotates at a predetermined timing, and the paper P is pressed against the registration roller 13. After being temporarily stopped between the rotating pressure roller 14 and timing adjustment, the sheet is conveyed toward the transfer section provided with the transfer roller 7 at an accurate timing coincident with the toner image on the photosensitive drum 1. You.

The toner image is transferred to the transfer paper P on the upper surface side in FIG. 2, is separated from the photosensitive drum 1, and is conveyed to a fixing device (not shown). It is discharged to a paper tray or the like. After the transfer is completed, foreign matters such as residual toner and paper dust remaining on the photosensitive drum 1 are removed by a cleaning blade 8a provided in the cleaning unit 8, and the residual potential remaining on the photosensitive drum 1 is reduced. It is removed by an unillustrated static elimination lamp to prepare for the next charging by the charging roller 2.

As shown in FIG. 1, the charging roller 2 has a conductive elastic layer 16 made of rubber integrally mounted on the outside of a shaft (conductive core) 15 made of, for example, stainless steel (SUS). is there. Then, the small diameter portions 15a, 15a formed at both ends of the shaft portion 15 are formed of a conductive material.
The bearings 17 are rotatably supported (only one shaft end is visible in FIG. 1), and the bearings 17 thereof are moved in the direction of the photosensitive drum 1 by a conductive pressure spring (elastic member) 12 which is a member to which power is supplied. To make contact with the surface 1 a of the photosensitive drum 1 in a state where the axis of the charging roller 2 is parallel to the axis of the photosensitive drum 1.

The charging roller 2 is formed in a unitary shape with the charging case 11. An electrode plate 18 bent in an L-shape is fixed to the charging case 11, and a convex spring receiver 18 a formed on the lower surface of one end thereof is provided.
One end of the conductive pressurizing spring 12 is fitted into and held therein. The charging case 11 is
Small-diameter portions 15a, 15a at both ends of shaft 15 of charging roller 2
Are rotatably supported in FIG. 1 (only one side is shown in FIG. 1).

The bearing 17 can be moved by a predetermined amount only in a direction in which the charging roller 2 approaches and separates from the photosensitive drum 1 by a bearing holding groove (not shown) formed in the charging case 11. A spring receiver 17a is projected from the upper surface of the bearing 17, and a leaf spring 19, which is a power supply member formed of a conductive material, is fitted into a hole formed at the left end in FIG. It is attached by doing.

The leaf spring 19 has an arc-shaped sliding contact portion 19b at the right end in FIG.
Is in direct contact with the shaft 15 of the charging roller 2. The other end of the bearing 17 fitted into the spring receiver 17a is
The leaf spring 19 is interposed between the bearing 17 and the conductive pressure spring 12 so that the leaf spring 19 is pressed against and fixed to the upper surface of the bearing 17 by the urging force of the conductive pressure spring 12.

As described above, the charging roller 2 includes the charging case 1
1 and other various parts, are formed in a unit shape, and in a state where the leaf spring 19 is in contact with the shaft portion 15 of the charging roller 2, the shaft portion 15 and the bearing 17 are integrally formed in the vertical direction in FIG. It is moving. One end of a main body side application spring 21 is pressed against the electrode plate 18 fixed to the charging case 11, and the other end of the main body side application spring 21 is held by a spring receiver of the main body side receptacle 22.

Further, the main body side receptacle 22 is connected to the main body power supply 20, so that the charging roller 2 is supplied with power (bias application) from the main body power supply 20 through two power supply paths. . That is, one of the two power supply paths passes from the main body power supply 20 to the main body side receptacle 22 and the main body side application spring 21, passes from the electrode plate 18 of the charging roller unit to the conductive pressure spring 12, and passes through the bearing 17. This is a power supply path for supplying power to the shaft 15.

The other power supply path extends from the main power supply 20 to the conductive pressure spring 12 in the same power supply path, one end of which is in direct contact with the shaft 15, and the other end of which is the bearing 1.
7 and the main body side application spring 21
7 of the charging roller 2 through a leaf spring 19 that contacts the
This is a power supply path leading to. As described above, in this charging device (power supply device), the power supply from the main body power supply 20 to the charging roller 2 is performed by providing the two power supply paths. Even if the charging roller 2 can be reliably supplied with power by the other power supply path, a more stable image can be provided.

That is, when power is supplied to the charging roller 2, the charging roller 2 rotates together with the photosensitive drum 1. At this time, the roundness of the charging roller 2 and the photosensitive drum 1 is determined. Alternatively, the charging roller 2 is moved in the vertical direction in FIG. 1 by the urging force of the conductive pressure spring 12 or the vibration of the drive system of the apparatus due to the play of the supporting portion which rotatably supports the rotating bodies. Sometimes.

In this case, in the conventional charging device, as described with reference to FIG. 3, the electrode for supplying power to the charging roller is temporarily separated from the end surface of the shaft (core bar) of the charging roller. As a result, there was a fear that the contact became unstable. Also, when the charging roller moves up and down, there is a fear that the electrode in contact with the end face may be deformed,
When the charging roller is set in the unit state, the electrodes may be deformed.

However, according to the charging device of this embodiment, even if the charging roller 2 moves up and down in FIG. Since the plate spring 19 constituting the power supply path of the first embodiment moves integrally with the shaft portion 15 of the charging roller 2 and the bearing 17 rotatably supporting the small diameter portion 15a of the shaft portion 15, Since a conduction failure hardly occurs in the contact portion, stable power supply from the main body power supply 20 to the charging roller 2 can be performed.

In this embodiment, since the power supply member that comes into contact with the bearing 17 is a leaf spring 19, the sliding contact portion 19a formed on one end side of the charging roller 2 is formed by the spring property of the material itself. Since the contact is made directly with the contact 15, more reliable contact can be obtained. Since the leaf spring 19 is pressed against the bearing 17 by the urging force of the conductive pressure spring 12, there is no need to provide a dedicated fixing part for fixing the leaf spring 19 to the bearing 17 in particular. Therefore, the number of parts can be reduced, and the assemblability and disassembly are improved.

While the above description has been made of an example in which the power supply device according to the present invention is applied to a charging device of an image forming apparatus, the power supply device according to the present invention can also be applied to a transfer device. In that case, the image carrier contact member is the one shown in FIG.
The transfer roller 7 transfers the toner image formed on the surface 1a of the photosensitive drum 1 described above to the transfer paper P. In this case, the image can be transferred more stably, so that the image quality can be improved.

[0028]

As described above, according to the present invention, according to the present invention, there is provided a charging roller in which power is supplied from a power source while being rotated by being directly or in contact with an image carrier by an urging force of an urging member. An image carrier contact member such as a transfer roller is
Even when the power supply member is in contact with the shaft of the image carrier contact member, it moves integrally with the bearing that rotatably supports the shaft and the image carrier contact member even when the power supply member is in contact with the shaft of the image carrier contact member. Therefore, poor conduction is less likely to occur. Therefore, stable power supply from the power source to the image carrier contact member can be performed. In addition, there is no possibility that other parts such as electrodes are deformed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a charging device showing an embodiment in which a power supply device according to the present invention is applied to a charging device.

FIG. 2 is a schematic diagram showing the periphery of an image forming unit of an image forming apparatus provided with the charging device.

FIG. 3 is a schematic diagram illustrating a part of a charging device that is a power supply device that supplies power to a conventional charging member to charge a photosensitive drum that is an image carrier.

[Explanation of symbols]

 1: Photoconductor drum (image carrier) 1a: Surface 2: Charging roller (image carrier contact member) 7: Transfer roller (image carrier contact member) 12: Conductive pressure spring (member supplied with power) 15: Shaft 17: Bearing 19: Leaf spring (power supply member) 20: Body power supply

Claims (5)

[Claims] An image carrier contact member which is rotatably held and is brought into contact with the image carrier directly or via paper by the urging force of an urging member, and is supplied with power from a power supply; In a power supply device in which a member is supplied with power from a power supply via a plurality of power supply paths, one of the plurality of power supply paths is a conductive material rotatably supporting a shaft of the image carrier contact member from the power supply. A power supply path for supplying power to the shaft portion via a bearing formed by the other. One of the other power supply paths is in direct contact with the shaft portion at one end and power is supplied from the bearing and the power supply at the other end. A power supply path to the shaft portion through a power supply member that contacts the bearing in a state interposed between the power supply member and the shaft portion of the image carrier contact member. So that it moves integrally with the shaft and the bearing The power supply device to a child and features. 2. The power supply device according to claim 1, wherein the power supply member is a leaf spring. 3. The power supply member according to claim 1, wherein the power supply member is formed of an elastic member, and the power supply member is pressed against the bearing by a biasing force of the elastic member. Power supply. 4. The power supply device according to claim 1, wherein the image carrier contact member is a charging member that charges a surface of the image carrier. 5. The image bearing member according to claim 1, wherein the image carrier contact member is a transfer member for transferring a toner image formed on the surface of the image carrier onto a sheet. The power supply device according to claim 1.