JPH0934256A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of stably supplying biassed electricity to a developing sleeve for a long time without complicating or enlarging a device as a whole even when a plurality of developing devices are provided. SOLUTION: A developing sleeve 52 is supported in a developing canister by a bearing 59 so as to be freely rotated and a butt roller 55 for a driving gear 60 and a conductive bearing is provided integrally with a rotation center shaft 61. A conductive member 57 is integrally provided in a positioning member 56 attached to a main body side plate 62 brought into contact with the butt roller 55 and by bringing the butt roller 55 into contact with this conductive member 57, developing biassed electricity is supplied via this conductive member 57.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus such as an electrophotographic copying apparatus which visualizes a latent image by using a developer carrying member such as a developing sleeve.

[0002]

2. Description of the Related Art An electrophotographic copying apparatus is provided with a rotating developing sleeve as a developer carrying member, and the toner is held on the surface of the developing sleeve by magnetic force or electrostatic force. By flying to a latent image,
Means for visualizing are used. Therefore, a means for supplying a developing bias to the developing sleeve is indispensable.

FIG. 7 shows a sectional view of a developing device and a moving means which have been conventionally used. Reference numeral 100 denotes a photosensitive drum that is a latent image carrier, and the photosensitive drum 100 is rotatably arranged in the arrow direction while carrying a latent image. The latent image on the photosensitive drum 100 is the developing sleeve 10 which is a developer carrier.
Although it is visualized by the developer carried on the No. 1, the developer is the screws 102, 103 in the developing container 104.
The surface of the developing sleeve 101 is coated with a uniform thickness by the blade 105. By rotating the developing sleeve 101 in the direction of the arrow, the developer is conveyed to a position facing the latent image, and the bias voltage causes the developer to fly to the latent image.

A moving means is attached to the developing device so that the developing sleeve 101 is brought close to the photosensitive drum 100 only when the developing is required. That is, the developing container 104 is the same as the developing movable table 10
6 is attached to the rail 6 so that it can be inserted and removed freely.
3 and 114 are configured to be movable with respect to the round elongated holes 116 and 117 of the main body side plate. Then, a leaf spring 107 provided to pressurize the development moving table 106 comes into contact with a cam 108 pivotally supported by the drive shaft 109, and when the cam 108 is at the position shown by the solid line, the development is performed. The container 104 is moved to the position shown by the solid line. Further, a guide 110 that comes into contact with the cam 108 is attached to the developing movement table 106, and when the cam 108 is at the position shown by the chain double-dashed line, the developing container 104 is retracted to the position shown by the chain double-dashed line.

As described above, the developing device has the photosensitive drum 1
However, even in this case, since it is necessary to apply the developing bias voltage to the developing sleeve 101, the power feeding portion is configured as follows.

FIG. 8 shows a sectional view of the developing sleeve power feeding portion. First, since the developing device can be moved in the direction of arrow A by the above-described developing pressure unit, the developing sleeve 1
The outer periphery of the bearing 119 on the rotation center shaft 120 of 01 is the abutting roller 1 which is an abutting member made of resin.
18 is press-fitted so that the surface of the photosensitive drum 100 is not damaged. Further, a drive gear 121 is integrally attached to the rotation center shaft 120 of the developing sleeve 101, and is driven to rotate by a main body side drive source (not shown). An axial positioning member 122 of the developing sleeve 101 is attached to the tip of the rotation center shaft 120, and the positioning member 122 abuts on the end surface of the power feeding case 123 fixed to the main body side plate 124 to position the shaft. In this state, the rotation center shaft 12
The end surface of 0 is pressed against the leaf spring 125. The leaf spring 125 is connected to a high-voltage power supply device (not shown) by a cord 126, and if the contact state between the leaf spring 125 and the end surface of the rotation center shaft 122 is ensured, the developing sleeve 101 is provided. A developing bias is applied to the.

[0007]

However, according to the above-mentioned conventional example, the developing sleeve 101 has several tens to several hundreds rpm.
Since it rotates in the direction of arrow A as described above, the leaf spring 125 is rubbed and worn by the end surface of the rotation center shaft 120, or foreign matter (toner or the like) enters the contact portion,
In some cases, stable bias power supply may be difficult for a long period of time.

Further, when a plurality of developing devices are provided as in a color copying machine, power supply means are required for the number of developing devices, and the entire device may become complicated and large.

Therefore, according to the present invention, the bias power can be stably supplied to the developing sleeve for a long period of time, and even when a plurality of developing devices are provided, the image forming device does not become complicated and large in size. Is intended to provide.

[0010]

According to the first invention of the present application, the above object is to provide a latent image carrier for carrying a latent image,
A developer carrying member arranged to face the latent image carrying member to develop the latent image, a positioning member for maintaining a predetermined gap between the developer carrying member and the latent image carrying member, and the positioning member. An abutting member attached to a developer carrying member that comes into contact with the developing device, a developing device having the developer carrying member, and moving the developing device together with the developer carrying member with respect to the latent image carrying member. In an image forming apparatus including a moving unit, a conductive member is attached integrally with the positioning member at a contact position of the positioning member with the abutting member,
This is achieved by forming at least a portion of the abutting member that is in contact with the conductive member with a conductive member, and contacting the portion of the abutting member formed with the conductive member with the developer carrier.

Further, according to the second invention of the present application,
The above object is achieved in the first invention by the abutting member being a conductive bearing.

Further, according to a third invention of the present application, in the above-mentioned first object, the abutting member has an outer diameter portion formed of a conductive member, and the outer diameter portion is formed in the outer diameter portion. ,
This is achieved by providing an arm portion that comes into contact with the rotation center axis of the developer carrier to which the abutting member is attached.

[0013]

According to the first invention of the present application, at least the positioning member for maintaining the gap between the developer carrying member and the latent image carrying member and the abutting member for the developer carrying member are brought into contact with each other. Since the portion is formed to have conductivity and the conductive portion of the butting member is brought into contact with the developer carrying member, by supplying a developing bias to the positioning member, the developing is performed via the butting member. A developing bias is supplied to the agent carrier. Further, since the power feeding portion is provided in the positioning portion, even if the developing device is moved toward and away from the latent image carrier, the power feeding portion is not rubbed.

According to a second aspect of the present invention,
Since a conductive bearing is used as the abutting member, by attaching the abutting member to the developer carrying member, the developer carrying member and the abutting member are electrically connected.

Further, according to the third invention of the present application, only the outer diameter portion of the abutting member is made of a conductive member, and the arm portion which comes into contact with the rotation center axis of the developer carrier is provided.
Even if the core portion of the abutting member attached to the rotation center shaft is not formed of a conductive member, conduction with the developer carrying member can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic sectional view of a color image forming apparatus to which the present invention is applied. In FIG. 1, reference numeral 0 is an original on the platen glass, and the original 0 is read as image information by an optical system known to those skilled in the art, and according to the image information, an exposure device 3 including a laser scanner or the like is used. The laser light L is irradiated onto the photosensitive drum 1 which is a latent image carrier uniformly charged by the primary charger 2 to form a latent image. Next, the latent image is developed by the developing device 4, but in a full-color copy like the device of the present embodiment, toner of four colors is normally used, so the developing device 4 uses the magenta color developing device 4M and the cyan color developing device. 4C, a yellow developing device 4Y, and a black developing device 4Bk are provided, and each developing device is placed on a moving table 26 as described in the conventional example.
The developing device for the required color is movable so as to be close to the photosensitive drum 1. Further, the transfer paper P as a transfer material is
Paper feed roller 4 from paper feed cassette 40 or manually
1 is conveyed to the transfer drum 6 as a transfer device, and is supported on the surface of the transfer drum 6 by the suction roller 20.
The transfer drum 6 is charged by being charged by the power supply charger 19.
Electrostatically adsorbed on the surface.

At this time, since the photosensitive drum 1 and the transfer drum 6 are connected and driven by gears to rotate synchronously at a predetermined process speed, the transfer paper P adsorbed on the surface of the transfer drum 6 is transferred between the photosensitive drum 1 and the transfer drum 6. The image is transferred to the contact position, and the image is transferred by the transfer charger 30. A pressing sheet 30 for pressing the transfer sheet P against the surface of the photosensitive drum 1 is further arranged at the transfer position.

The transfer paper P, which has been transferred, is separated from the transfer drum 6 by the separating claw 14, sent to the fixing device 18 by the conveying section 17, and discharged onto the discharge tray after fixing. Then, when the transfer paper P is separated from the transfer drum 6, the charge-eliminating chargers 10, 11, 2 are used to remove the residual charges on the surface thereof.
9 turns on. After that, the surface of the transfer drum 6 is cleaned by the cleaner 15.

Further, in order to make a full-color copy, four-color visible images are transferred in superposition on the transfer paper P adsorbed and held on the surface of the transfer drum 6 at a timing.
Residual toner is removed from the photosensitive drum 1 by the cleaner 5, and then the photosensitive drum 1 is uniformly charged by the primary charger again, and then a latent image is formed by the laser light L, and this cycle is repeated.

In the apparatus of the present embodiment as described above, each developing device of the developing device 4 is arranged by the moving table 26 so as to come in contact with and separate from the photosensitive drum 1 as described above. In order to stably supply the bias voltage, the power supply unit is configured as follows.

First, as shown in FIG. 2, the developing sleeve 52, which is the developer carrying member of each developing device, is rotatably supported by a bearing 59 in a developing container 53, and a rotation center shaft 61 is provided.
A drive gear 60 integrally attached to the drive gear 60 receives a drive force from a drive source (not shown) on the main body side to rotate the drive. Further, a conductive bearing having conductive grease enclosed therein is attached to the rotation center shaft 61 as an abutting roller 55 as an abutting member. By making the abutting roller conductive, the rotation center shaft 61 of the developing sleeve 52 and the outer peripheral surface of the abutting roller 55 are electrically connected.

The abutting roller 55 is positioned by the positioning member 56 attached to the main body side plate 62 when the developing container 53 moves in the direction of approaching the photosensitive drum 1.
The position of the developing device is determined by abutting against the contacting member, but in the present embodiment, a conductive member 57 is provided integrally with the positioning member 56, and the abutting roller 55 contacts the conductive member 57. Is configured as follows. The contact surface 58 of the conductive member 57 is, as shown in FIG.
Since it is aligned with the outer diameter surface of the positioning member 56, the conductive abutting roller 5 does not affect the positioning.
Power can be supplied to the developing sleeve 52 via 5, and the conductive member 57 is drawn to the outside through the hole 63 of the main body side plate 62 and connected to a high voltage power supply device (not shown).

With this structure, even if the developing container 53 repeats the contact / separation operation in the direction of arrow B with respect to the photosensitive drum 1 as in the conventional example, the conductive member 57 is not rubbed. Further, since there is no rubbing due to the rotation of the developing sleeve 52, the developing bias from the high-voltage power supply device is stably applied to the developing sleeve 52 while maintaining an appropriate gap between the developing sleeve 52 and the photosensitive drum 1. It becomes possible to do.

In the present embodiment, the conductive bearing is used for the abutting roller. However, when the copying speed of the copying machine is slow and the rotation speed of the developing sleeve is slow, the abutting roller has a sintered member and a conductive resin. It is also possible to use Further, in the present embodiment, the developing bias supplying means is arranged on the developing sleeve driving gear side, but it may be arranged on the other sleeve supporting means side or on both sides.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 4 is a longitudinal sectional view of the vicinity of the developing device according to the second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 4, 64 is an abutting roller,
The member 6 supported by the rotation center shaft 69 of the developing sleeve 52.
5 and a conductive ring 66 press-fitted on the outer periphery thereof. A plate spring 67, which is an arm portion, is integrally formed with the conductive ring 66, and as shown in FIG.
As shown in FIG. 7, the tip 68 is pressed against the center of the rotation center shaft 69 of the developing sleeve 52. Therefore, when the developing container 53 moves toward the photosensitive drum 1 and the abutting roller 64 comes into contact with the positioning member 70 attached to the body side plate, the conductive ring 66 of the abutting roller 64 is positioned. The developing bias voltage is supplied to the developing sleeve 52 via the leaf spring 67 by contacting the conductive member 71 formed integrally with the member 70.

Also in this embodiment, since the contact surface of the conductive member 71 is aligned with the outer diameter surface of the positioning member 70, the gap between the photosensitive drum 1 and the developing sleeve 52 is appropriately maintained.

In the present embodiment, the member 65 forming the abutting roller 64 does not need to be conductive, and may be made of any material that can be simply used as a bearing.

(Third Embodiment) Next, a third embodiment of the present invention is shown in FIG. The present embodiment is applied to an image forming apparatus having a plurality of developing devices such as a color copying machine.
The positioning member 72 has the same structure as the first and second embodiments, except that a plurality of conductive members 73 are integrally formed. That is, each developing device can be freely moved in and out of the directions of arrows C, D, E, and the device developing sleeves 77, 78, 79 are provided with abutting rollers 74, 75, 76. Although a plurality of developing devices are all in a pressurized state for the sake of explanation in the figure, in an actual color copying machine, only one developing device is controlled to be in a pressurized state.

Then, one of the developing units is the photosensitive drum 1.
When it is moved in the direction of approaching to, the conductive member 73 formed integrally with the positioning member 72 and the abutting rollers 74, 7
Either one of the contact holes 5 and 76 comes into contact, and the developing bias as described above can be applied.

As is apparent from the above configuration, even when there are a plurality of developing devices, it is possible to supply the developing bias simply by increasing the number of conductive members having a simple structure as described above, which complicates the entire apparatus. It has become possible to avoid upsizing.

[0033]

As described above, the first embodiment according to the present application is described.
According to the invention, the positioning member for maintaining the gap between the developer carrying member and the latent image carrying member and the abutting member for the developer carrying member are formed so that at least their respective contact portions have conductivity. However, since the conductive portion of the butting member and the developer carrying member are brought into contact with each other, it is possible to stably supply the developing bias for a long period of time. Further, even when a plurality of developing devices are provided as in a color copying machine, it is possible to avoid making the entire device complicated and large.

According to the second aspect of the present invention,
Since the conductive bearing is used as the abutting member, it is possible to surely establish electrical continuity between the developer carrying member and the abutting member, and to stably supply power to the developing bias.

Further, according to the third invention of the present application, only the outer diameter portion of the abutting member is made of a conductive member, and the arm portion which comes into contact with the rotation center axis of the developer carrying member is provided.
Even if the core of the abutting member attached to the rotation center shaft is not formed of a conductive member, it can be electrically connected to the developer carrying member, and the material of the abutting member can be selected in a wide range. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a transverse cross-sectional view showing the vicinity of a power supply section of the developing device in the apparatus shown in FIG.

FIG. 3 is a vertical cross-sectional view showing the vicinity of a power supply unit of the developing device in the apparatus shown in FIG.

FIG. 4 is a horizontal cross-sectional view showing the periphery of a power supply unit of a developing device according to a second embodiment of the present invention.

5 is a view of the abutting member of the apparatus of FIG. 4 viewed from the direction of arrow F in FIG.

FIG. 6 is a diagram showing the vicinity of a power supply unit of a developing device according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of a developing device in a conventional example.

FIG. 8 is a diagram showing the vicinity of a power supply unit of a developing device in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum (latent image carrier) 4 Developing device 26 Moving stand (moving means) 52,77,78,79 Developing sleeve (developer carrying body) 55,64,74,75,76 Member, conductive bearing) 56, 70, 72 positioning member 57, 71, 73 conductive member (conductive member integrally attached to positioning member) 67 leaf spring (arm portion)

Claims (3)

[Claims] 1. A latent image bearing member carrying a latent image, a developer bearing member disposed opposite to the latent image bearing member to develop the latent image, the developer bearing member and the latent image. A positioning member that maintains a predetermined gap of the carrier, and an abutting member attached to the developer carrier that contacts the positioning member;
An image forming apparatus comprising: a developing device having the developer carrying member; and a moving means for moving the developing device together with the developer carrying member to and from the latent image carrying member. A conductive member is attached integrally with the positioning member at the contact position with the abutting member, and at least a portion of the abutting member that abuts the conductive member is formed of a conductive member, and is formed of the conductive member. An image forming apparatus, wherein the portion of the abutting member and the developer carrying member are brought into contact with each other. 2. The image forming apparatus according to claim 1, wherein the butting member is a conductive bearing. 3. An outer diameter portion of the abutting member is formed of a conductive member, and an arm portion that comes into contact with the central axis of rotation of the developer carrier to which the abutting member is attached is formed in the outer diameter portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.