JP3256385B2 - Image forming device - Google Patents

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 having a charger for facing a photosensitive drum and uniformly charging the photosensitive drum, and more particularly to an invention for suitably positioning or mounting a charging device. .

[0002]

2. Description of the Related Art Conventionally, respective process means of exposure, development, transfer, cleaning (removal of residual toner), charge elimination and charging are arranged on the outer peripheral surface of a photosensitive drum, and an image is formed by a predetermined electrophotographic process. Electrophotographic apparatuses based on the so-called Carlson process are well known.

This type of electrophotographic apparatus generally uses a corona charger in which a corona wire is stretched in a shield case in order to uniformly charge the surface of the photoreceptor, and a high voltage of 4 to 8 KV or more is applied to the corona wire. Is applied, the voltage gradient in the generatrix direction of the photoconductor drum, that is, the height regulation with respect to the photoconductor surface must be accurately controlled in order to perform uniform charging. In order to rotate the inside of the drum, it is necessary to accurately control the height due to a run-out or the like generated when the drum rotates.

On the other hand, since the upper and lower sides of the shield case facing the photosensitive drum are open on the charger side as well, floating toner and the like adhere to the corona wire, which necessitates periodic maintenance and replacement. Come. However, when the charger is configured to be replaceable, the positional accuracy tends to be degraded accordingly.

For this reason, various techniques for controlling the height of the surface of the photoconductor by contacting the supports provided at both ends of the charger with the photoconductor drum have been conventionally disclosed. For example, JP-A-2-21
No. 2858 discloses a technique in which the charger and the photosensitive drum are brought into contact with each other via a spacer, and the position is regulated by applying an elastic force from the back side of the charger.
In Japanese Patent No. 5748, the distance between the charger and the photosensitive drum is regulated using a tracking rail, and the position is regulated by applying elastic force from the back side of the charger. Similar technology.

[0006]

However, all of the above-mentioned prior arts only deal with the restriction on the height between the charger and the photosensitive drum. However, as the diameter of the drum is reduced as in the present case, the number of printed sheets is reduced. Attempting to maintain the predetermined 6 to 10 sheets / min greatly increases the linear velocity of the drum, which causes the charger, which is in contact with the photosensitive drum via the support member, to oscillate in the circumferential direction. There has been a problem that smooth uniform charging is not performed.

In view of the drawbacks of the prior art, the present invention regulates the position precisely both in the circumferential direction of the drum and in the direction of the height, so that even when the linear velocity of the drum is greatly increased, smooth and uniform charging can be easily achieved. Provided is an image forming apparatus that enables the image forming apparatus, particularly, a mounting structure of a charger.

[0008]

As shown in FIGS. 1 and 2, the height of the charging device 2 which faces the photoconductor drum 1 and uniformly charges the photoconductor drum 1, preferably the height of the photoconductor is required. The present invention is applied to an image forming apparatus provided with a corona discharger, and is characterized in that a support 3 provided at both ends of a corona charger 2 is brought into contact with a photoreceptor drum 1 to make contact with a photoreceptor surface. with performing the height regulation, the shield case one
Position regulation portions on the side surface in the circumferential direction of the photosensitive drum 1
Forming a, the position regulating portion is brought into contact with the fixing surface 4a positioned downstream in the rotational direction of the photosensitive drum 1, have rows position regulating the photoconductor Dora <br/> arm circumferential direction, the fixing surface Exposure hand
One side of a regulating member that regulates the height of the step from the photoconductor surface
It is characterized by having done, Preferably , as described in Claim 2,
An elastic force is applied to the support from the back side, and the photosensitive drum is driven.
And more preferably as described in claim 3.
A support provided at both ends of the charger applies a charging voltage to the charger.
Characterized in that it functions as an electrical contact point for supplying
You.

According to this configuration, two-point regulation is performed at a point where the height of the photosensitive drum is different from the circumferential direction by approximately 90 °, and the position can be regulated accurately and reliably. In addition, even when the drum linear velocity is greatly increased due to the reduction in the diameter of the drum, since the regulating surface is provided on the downstream side in the rotation direction of the drum, the charger 2 follows the rotation of the drum and does not swing and smoothly and uniformly. Enables charging.

In this case, by applying elastic force to the support body 3 from the back side and bringing the support body 3 into contact with the photosensitive drum 1, the vibration caused by the rotation of the photosensitive drum 1 is absorbed, and a precise height regulation is achieved. It becomes possible. When the charger 2 is a corona charger 2 in which a corona wire 21 is stretched in a shield case 20, a support provided at both ends of the shield case is used.
The height regulation with respect to the photoconductor surface by contacting the photoconductor drum
And a position regulating portion 20a in the circumferential direction of the drum is formed on one side surface of the shield case 20, and the position regulating portion 20a abuts on the fixed surface 4a located on the downstream side in the rotation direction of the photosensitive drum. And the photoreceptor
The fixing surface 4a is one side surface of a regulating member (optical system regulating portion 41) that regulates the position in the drum circumferential direction and regulates the height of the exposure unit 5 from the photosensitive member surface. Accordingly, it is easy to regulate the interval between the exposure unit 5 and the charger 2, and as a result, the charging potential of the photoconductor reaching the exposure position after charging is also constant.

The support 3 is made of PBT or PB
By using a mixture of T mixed with a fluororesin and further using ultra-high molecular polyethylene, wear can be reduced with low sliding resistance. Also, the sliding portion of the support on the photosensitive drum 1 side does not directly contact the support with the drum.
The contact may be made via a contact ring. When the photosensitive drum 1 is formed of a-Si, the support 3 can directly contact the surface of the photosensitive drum 1.

The support 3 functions as an electric contact portion 30a for supplying a charging voltage to the charger 2, whereby
This leads to a reduction in the number of parts.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just. FIG.
2 is a perspective view of the image forming apparatus according to the embodiment of the present invention, showing a main part around the photosensitive drum 1. Reference numeral 1 denotes a photosensitive drum made of a-Si. It comprises a transfer roller 8, a cleaning unit 10, a charging unit 2, and an optical system unit 5 supported by a support frame 9.

The cleaning unit 10 has a cleaning blade 11 whose leading end contacts the photosensitive drum 1 to remove residual toner, a transport screw 12 that transports the residual toner removed by the blade 11 to a waste toner bottle (not shown), and It comprises a housing body 13 for housing or fixing them. The housing body 13 is formed of a resin body, is positioned and fixed to a main body housing (not shown), and has an upper end facing the charging unit 2 obliquely bent in a key shape so that the charging guide 14 of the charging unit 2 Eggplant

Numeral 40 denotes a height regulating member of the optical system which forms a part of the main body housing, and has a V-shaped concave portion for regulating the optical system 41 in contact with the tip of an adjusting screw for regulating the height of the optical system. At the same time, the side end facing the charging unit 2 is bent obliquely upward in the shape of a key so as to be a charging guide for the charging unit 2 and a charging unit regulating surface in the circumferential direction (hereinafter referred to as a regulating guide 4).
And Since the optical system restricting portion 41 only comes into contact with the tip of the adjusting screw 51 for restricting the height of the optical system, it is not necessary to dispose the optical system restricting portion over the entire length of the photosensitive drum 1, and the end portion in the longitudinal direction of the drum 1 Only need to be located at
Is configured to be able to abut on the side wall 20a of the shield case 20 of the charging unit 2 over the entire width. The regulating guide 4 and the charging guide 14 are set to be equal to or slightly larger than the width of the shield case 20 of the charging unit 2.

The charging unit 2 has a rectangular cross section and is open on both upper and lower sides facing the photosensitive drum 1. A control grid 22 is arranged on the lower surface and a resin reinforcing member 23 is mounted on the upper surface. The reinforcing member 23 has a key shape 23a along the loading guide 14 at the upper left end in the drawing, and
Reference numeral 3b denotes a horizontal surface that can be pressed by the coil spring of the head cover. At both ends in the longitudinal direction of the shield case 20, a corona wire 21 is stretched and a support 3 for regulating the height between the corona wire 21 and the surface of the photosensitive drum 1 is fixed.

The support 3 is made of PBT or a mixture of PBT and a fluororesin, and furthermore, is made of ultra-high molecular polyethylene or other insulating resin, and has parallel projections formed on the lower surface to be in contact with the photosensitive drum 1. In addition, as shown in FIG. 3, a slit groove 31 for engaging and fixing the plate mechanical hook 30 is formed at the upper end side. The plate mechanical hook 30 is formed of a highly conductive metal material, and has a portion 30a for engaging and supporting the corona wire 21 and a tongue piece 30b serving as an electrical contact.

The charging guide 14 and the regulating guide 4
When the charging unit 2 is inserted into the rectangular space sandwiched between the support members 3, the bottom surface of the support 3 abuts on the surface of the photosensitive drum 1, but the lower surface 23 a of the reinforcing member and the upper surfaces 14 b, 4 b between the loading guide and the regulating guide are The height of the support 3 is set so as to maintain the non-contact state.

The support frame 9 located on the upper surfaces of the charging unit 2 and the cleaning housing body 13 is configured to be rotatable about a fulcrum 90 located on the cleaning housing body 13 side. A coil spring 91 for pressing the upper surface of the unit 2 is attached. Further, an optical system main body 50 composed of an LED array and an optical lens is provided on the tip side thereof, and adjustment screws 51 located at both ends in the longitudinal direction of the main body form the spring 52. Mounted through. As a result, by turning the adjusting screw 51, the length in the screw axis direction, in other words, the focal length of the optical system lens can be adjusted, and the supporting frame 9 is turned clockwise to close the adjusting screw. The tip of the 51 abuts on the V-shape of the optical system restriction portion 41, and the backlash of the adjusting screw 51 is eliminated by the pressing of the spring 52, so that accurate focal length accuracy can be guaranteed.

Next, the operation of the embodiment based on this embodiment will be described. 2, the charging unit 2 is inserted into a rectangular space between the charging guide 14 and the regulating guide 4, so that the bottom surface of the support 3 contacts the surface of the photosensitive drum 1. Next, by rotating the support frame 9 clockwise to close it, the tip of the adjusting screw 51 comes into contact with the V-shape of the optical system regulating portion 41 and the coil spring 91 presses the upper surface of the charging unit 2. At this time, since the non-contact state is maintained between the lower surface 23A of the reinforcing member and the upper surfaces of the loading guide 14 and the regulating guide 4, the urging force of the coil spring can be directly transmitted to the support 3. When the photosensitive drum 1 is rotated in this state, the charging unit 2 sandwiched between the loading guide 14 and the regulating guide 4 slightly swings following the rotation of the photosensitive drum 1. Since the side surface 4a (fixed surface) of the regulation guide 4 faces the side surface 20a (position regulation surface) of the shield case 20, the rotation of the photosensitive drum 1 causes the side surface of the shield case 20 to contact the side surface 4a of the regulation guide 4. Touch and position fixed. Accordingly, the charging unit 2 is supported at two points, that is, the bottom surface of the support 3 is in contact with the surface of the photosensitive drum 1 and the side of the shield case 20 is in contact with the regulation guide, so that the above-described operation of the present invention is smoothly achieved. .

[0021]

As described above, according to the present invention, the position can be regulated precisely in both the circumferential direction and the height direction of the drum. Enables charging. And so on.

[Brief description of the drawings]

FIG. 1 shows a configuration of a main part around a photosensitive drum of an image forming apparatus according to an embodiment of the present invention, and particularly shows a state where a support frame is closed and an image forming operation is being performed.

FIG. 2 shows a state before the charging unit is mounted with the support frame of FIG. 1 opened.

FIG. 3 is a schematic perspective view of the charging unit shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 2 charging unit 3 support 4a fixing surface 5 exposure means 9 support frame 20a position regulating portion 21 corona wire 30a electric contact portion

Continuation of the front page (56) References JP-A-5-289477 (JP, A) JP-A-5-19592 (JP, A) JP-A-62-222271 (JP, A) JP-A-2-58247 (JP) , U) Japanese Utility Model Application Hei 3-81950 (JP, U) Japanese Utility Model Application Hei 4-59852 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/02

Claims (3)

(57) [Claims] And a shield cable facing the photosensitive drum.
An image forming apparatus comprising comprises a corona charger for performing uniform charging of the photosensitive drum and stretched the corona wire inside the scan, the photosensitive member surface contacting the support provided to the corona charger across the photosensitive drum And height regulation and seal
Position on one side of the case in the circumferential direction of the photoconductor drum
Forming a restriction site, the position regulating portion is abutted against the fixed surface located on the photosensitive drum rotation direction downstream side, it has rows position regulating the photoconductor Dora <br/> arm circumferential direction, wherein the fixed surface is exposed hand
One side of a regulating member that regulates the height of the step from the photoconductor surface
An image forming apparatus comprising the it. 2. An elastic force is applied to the support from the back side.
And contacting the photosensitive drum with the photosensitive drum.
2. The image forming apparatus according to 1. 3. A support provided at both ends of the charger is provided with the charging member.
Functioned as an electrical contact point for supplying charging voltage to the heater
3. An image forming apparatus according to claim 1, wherein
apparatus.