JPH06118748A - Image forming device - Google Patents

Abstract

PURPOSE:To restrict a developing gap, exposure position and focal distance of an exposure head at a high precision by retaining the spacing between a developing sleeve and a photosensitive drum by a pair of restriction rollers disposed in a space where the two members are faced to each other. CONSTITUTION:The pair of restriction rollers 41 and 42 are disposed in the space where the developing sleeve 7 and the photosensitive drum 1 are faced to each other in a cross sectional surface at right angle of an axis with the developing position in between and the spacing between the two members is retained by bringing the periphery surfaces of each of the developing sleeve 7 and the photosensitive drum 1 into contact with these restriction rollers 41 and 42. Therefore, even when a variation is generated in a crossing DELTAL1 of the photosensitive drum 1 or the sleeve 7, the developing gap X can be restricted regardless of this. Furthermore, because the space between the photosensitive drum 1 and the sleeve 7 is supported at two points by the pair of restriction rollers 41 and 42 restricted in the direction of the gap with the developing gap X in between, the degree of parallelism between the drum 1 and the photosensitive drum can be maintained in good precision even when the diameter of the photosensitive drum 1 is made smaller. Thus, the exposure and the developing can be maintained in good precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an image forming method in which a developing sleeve carrying a developer is made to face a photosensitive drum having an exposure head inserted therein, and image development is carried out at the same time as or immediately after exposure. Forming apparatus

[0002]

2. Description of the Related Art Conventionally, for example, in a photosensitive drum formed by laminating a transparent conductive layer and a photoconductive layer on a transparent support,
An exposure head for generating a light output corresponding to image information is inserted, and the light output of the exposure head is focused to form a latent image on the photoconductor layer. The latent image is formed into a visible image (toner image) by the developer carried on the developing sleeve, and then the toner image is transferred onto plain paper through a transfer roller or other transfer means. Devices are known. (JP-A-58-153957, etc.)

In this type of image forming apparatus, the developing gap between the photosensitive drum and the developing sleeve is precisely regulated, and the photosensitive drum is rotated while the exposure head is inserted and fixed in the photosensitive drum. Because of the configuration, setting the focal length between the photoconductor drum and the exposure head is extremely troublesome, and since the apparatus performs development almost simultaneously with exposure, the angle regulation between the exposure position and the development position is also accurate. As a result, it is quite difficult to accurately set the interval and regulate the angle among the three members, the photosensitive drum, the developing sleeve, and the photosensitive head.

Therefore, according to the technique disclosed in, for example, Japanese Patent Laid-Open No. 141774/1990, a support frame for supporting the exposure head integrally incorporated in the drum is provided with three units which can be inscribed on the inner peripheral surface of the drum. While mounting the support roller, the support roller located on the side facing the inner developing roller of the support roller is fixed,
As a result, the focal length between the photosensitive drum and the exposure head is fixedly set, and the head is positioned and fixed by the three rollers so that the drum is rotatable about the axis and the drum unit and the developing roller are fixed. A gap adjusting member is arranged between the gap adjusting members, and the gap is adjusted by using the gap adjusting member.

[0005]

However, although it is important for the developing gap to maintain a precise gap between the developing roller and the outer peripheral surface of the drum, in the above technique, the photosensitive drum has a hollow sleeve shape. In order to do so, the fixed shaft of the exposure head inserted in the drum is used as a substitute to adjust the distance between the shaft and the rotary shaft of the developing roller. It is not always possible to accurately adjust the spacing, and in particular, as shown in FIG. 3, the outer diameter L of the photoconductor drum 1 cannot always be set accurately due to the processing tolerance ΔL ₁ or the like, and there is a tolerance error in the outer diameter L of the drum. When ΔL ₁ occurs, the developing gap X cannot be accurately regulated even if the axial distance is regulated. For this reason, in the prior art, the developing sleeve 7 is configured to be movable in the drum contacting / separating direction to adjust the developing gap X.
The developing unit in which the developing sleeve 7 is incorporated needs to be properly removed by changing the color or replacing the toner, and adjusting the gap X each time the replacement is performed imposes an excessive burden on the user. Further, in the configuration in which the support roller 40 of the photosensitive drum 1 is inserted into the drum 1, there is a limitation in reducing the diameter of the photosensitive drum 1, and it is impossible to manufacture a drum having a diameter smaller than a certain value.
This is an obstacle to device miniaturization, which is the most important feature of this technology.

On the other hand, in the conventional Carlson type electrophotographic apparatus, as shown in FIGS. 4 and 6, there is a configuration in which annular rollers 70 are provided on both ends of the developing sleeve 7, but in such a configuration. Even if the drum machining tolerance ΔL ₁ occurs as shown in FIG. 4, the developing gap X can be accurately regulated. However, since the annular roller 70 is in point contact with the peripheral surface of the photosensitive drum 1, As shown, in the case where the tilt deviation θ is apt to occur in the sleeve axis direction S-S with respect to the drum axis D-D, especially when the photosensitive drum 1 is reduced in diameter and the drum length is set so that a paper width of about A3 can be inserted. To
The positional deviation between the exposure position and the development position at both ends in the axial direction becomes large, and particularly in the exposure apparatus of this type, in which the distance between the exposure position and the development position in the circumferential direction must be set with high accuracy, the image sharpness is greatly affected. To do.

In view of the above-mentioned drawbacks of the prior art, the present invention takes into account the development gap X, the exposure position and the development position in the circumferential direction even when the photosensitive drum tolerance ΔL ₁ occurs and the diameter of the drum is reduced. It is an object of the present invention to provide an image forming apparatus capable of accurately controlling the three elements of the inter-space distance, and further, the focal length of the exposure head.

[0008]

According to the present invention, in the above-mentioned device, a pair of supporting rollers (hereinafter referred to as a regulating roller 41) are formed on a section perpendicular to the developing sleeve 7 in a space facing the developing drum 7 with a developing position interposed therebetween. , 42) are provided, and the developing sleeve 7 and the outer peripheral surface of the photosensitive drum 1 are brought into contact with the pair of regulating rollers to maintain a gap between the two members. In this case, the term "on the axis-perpendicular cross section" means that the axis lines are aligned and a pair is disposed on each side of the shaft end, as shown in FIG. Stipulated.

The second feature is that the pair of regulating rollers 41,
At least one of the rollers 42 is rotatably supported at a predetermined position, that is, the point where the movement of 42 is regulated at least in the direction of the line connecting the axis of the sleeve 7 and the axis of the drum 1 (hereinafter referred to as the gap direction). Alternatively, it may be constituted by a fixed roller, or its movement is restricted in the gap direction, but it may be constituted so as to be movable in a cross-section perpendicular to the axis orthogonal to the gap direction. In this case, the regulation in the gap direction is not limited to, for example, a single regulation using an elongated hole, but as shown in FIG.
Movement may be restricted by a combination of the fixed developing sleeve 7 and the vertical wall of the support frame of the exposure unit 2. Further, one or a plurality of support rollers 43 acting in the direction opposite to the acting direction of the regulation rollers 41, 42 are brought into contact with the outer peripheral surface side or the inner peripheral surface side of the photosensitive drum 1 to bring the photosensitive drum 1 into contact. The third feature is that the above is rotatably supported by the support roller group.

In this case, it is preferable that at least one roller 41 of the pair of regulating rollers 41, 42 is a fixed roller rotatably supported at a predetermined position, while the outer peripheral surface side of the photosensitive drum 1 is formed. Alternatively, one or a plurality of support rollers 43 which are brought into contact with the inner peripheral surface side and act in the opposite direction to the fixed roller are constituted by one support roller 43 which is swingable in the contacting and separating direction with the peripheral surface of the photosensitive drum 1. However, it is advisable to adopt a three-point support structure. Further, it is preferable that the one fixed roller 41 is rotatably supported by the support frame 20 that supports the exposure head.

[0011]

According to such technical means, the regulating roller 4 is
Since the photosensitive drum 1 and the developing sleeve 7 are regulated in the gap direction on the outer peripheral surface via the first and the second 42, even if the tolerance ΔL ₁ changes in the drum 1 or the sleeve 7, the developing gap is irrelevant. X can be regulated accurately.
Further, between the drum 1 and the sleeve 7, a pair of regulating rollers 41 are regulated in the gap direction with a developing gap X interposed therebetween.
Since it is supported by 42 at two points, in other words, even when the photosensitive drum 1 is reduced in diameter and the length of the drum 1 is set so that a paper width of about A3 can be inserted, two points are supported at both ends in the axial direction. For the drum 1
It is possible to maintain the parallelism between the axes of the sleeve 7 and the sleeve 7 with high accuracy, and thereby, it is possible to maintain the exposure and the development with high accuracy without causing misalignment between the exposure position and the development position over the entire axial direction. I can.

Further, the present invention particularly relates to the one fixed roller 41.
Is rotatably supported by the support frame 20 that supports the exposure head 2, so that the distance between the photosensitive drum 1 and the exposure head 2, that is, the focal length can be accurately regulated with the fixed roller 41 as a reference surface. As a result, the development gap X, the exposure focal length, and the exposure position / development position can be regulated on the basis of the common standard of the fixed roller, and the three factors that further affect the development quality are of high quality. Can be maintained at Further, the photosensitive drum 1 is one or a plurality of supporting rollers acting in a direction opposite to the acting direction of the pair of regulating rollers 41, 42, more specifically, the photosensitive drum 1 at a position opposite to the developing position. Since it is supported by the one support roller 43 that swings in the direction of contact with and away from the peripheral surface, even if the drum tolerance ΔL ₁ occurs, it is absorbed and efficiently supported by three-point support, so that the drum play Centerless and accurate rotation is possible without causing or rocking. In this case, by applying a driving force from the developing sleeve 7 side through a driving system (not shown), the regulation rollers 41, 4
The photosensitive drum 1 is smoothly rotated via 2 and a predetermined development can be performed.

[0013]

Embodiments of the present invention will now be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely examples, unless otherwise specified. Not too much.

FIG. 1 is a schematic view showing a structure around a drum unit of an exposure apparatus according to an embodiment of the present invention. Reference numeral 1 is a photosensitive drum in which an exposure head 3 is inserted, and the photosensitive drum 1 faces the photosensitive drum 1 for development. The sleeve 7 is disposed, the magnet assembly 71 is inserted into the developing sleeve 7, and the developer in the developing container 72 is conveyed to the developing gap X side while being magnetically held on the sleeve 7 by the magnet assembly 71. Configure as possible. A transfer roller 5 is abutted on the lower surface side of the photoconductor drum 1 so as to be synchronously rotatable, and a recording paper conveying path is formed along the tangential direction of the transfer roller 5, A sheet feeding cassette (not shown), a registration roller 6, and a fixing roller pair 8 sandwiching the transfer position are sequentially arranged from the upstream side.

Next, the respective process means will be described. The photosensitive drum 1 is a drum-shaped light-transmitting support 1a.
A transparent conductive layer b and a photoconductor layer 1c are laminated on top of each other, and the transparent conductive layer 1b is grounded, and a developing bias Vg is applied between the developing sleeves 7 via the developing gap X.
Is configured to be applicable.

The exposure head 2 has an LED or EL head array 21 for generating a light output corresponding to image information and a converging lens array 22 (trade name: SELFOC lens).
And a unit frame 23 that integrally supports them. A support shaft 24 is provided on both ends of the unit frame 23 in the longitudinal direction so as to be concentric with the photosensitive drum 1, and a photoconductive layer substantially corresponding to the developing gap X. The support shaft 24 is shown in FIG. 2 so that an image can be formed at a predetermined position on the body layer 1c.
It is supported and fixed to the side.

A pair of fixed rollers 41 and 42 are arranged on both sides of the developing gap X on the drum shaft end side, which is located outside the image forming area, and the fixed rollers 41 and 4 are provided.
2, the developing sleeve 7 and the outer peripheral surface of the photosensitive drum 1 are brought into contact with each other to maintain a gap between the both members 7-1, and the outer peripheral surface of the photosensitive drum 1 located on the opposite side of the developing gap X. The support roller 43 is brought into contact with the peripheral surface of the photosensitive drum 1 so as to be swingable in the contacting and separating direction.

The rollers will be described in detail below. The fixed rollers 41, 42 are arranged on both ends in the drum axis direction at respective symmetrical positions in a direction orthogonal to an imaginary line connecting the sleeve axis and the drum axis with the developing gap X interposed therebetween so that the axes are aligned with each other. A pair of fixed rollers 4 are provided.
Positions 1 and 42 are fixed to the drum frame bodies 10 and 10 arranged in parallel to the shaft ends via roller shafts 41a and 42a, respectively. Further, the fixed rollers 41, 42 are formed of a hard resin whose diameter does not change due to the pressure contact between the sleeve 7 and the drum 1, and the diameter of the fixed rollers 41, 42 is based on the rotation ratio of the sleeve 7 / drum 1. decide. The supporting roller 43 has an elongated hole 431 extending along an imaginary line connecting the sleeve 7 axis and the drum axis, in the drum frame 10, and the elongated hole 431 has a short diameter of the supporting roller 43. The support roller shaft 43a having the same diameter is fitted to the photosensitive drum 1
It is configured to be swingable only in the horizontal direction in which it comes in contact with and separates from the peripheral surface, and an elastic force is applied to the photosensitive drum 1 side by a spring 432 or the like. On the other hand, the developing unit in which the developing sleeve 7 is incorporated is also configured to be detachable as is known, and the spring 74 force can be biased to the fixed rollers 41, 42 side at the time of a predetermined mounting operation.

According to this embodiment, the photosensitive drum 1 is supported by the pair of fixed rollers 4 by the urging force of the supporting roller 43.
1, 42, and the developing sleeve 7 is also pressed against the fixed rollers 41, 42 by the biasing force of the spring 74 when the fixed sleeve 41, 42 is fixed in position.
The developing sleeve 7 and the outer peripheral surface of the photosensitive drum 1 contact with each other to maintain the space between the two members 1 and 7, and to fix the fixing rollers 41 and 42 through the supporting roller 43.
Since the urging force is urged to the side, the photosensitive drum 1
Is accurately supported at three points even in the centerless state,
The position is retained. Further, the pair of fixed rollers 41, 42 are arranged on both end sides of the drum along the same axis, and therefore, both left and right shaft ends are supported by two-point support in the cross-section perpendicular to the shaft. The parallelism between the sleeve 7 axis and the drum axis can be accurately maintained through the fixed rollers 41 and 42. Further, by applying a driving force from the developing sleeve 7 side through a driving system (not shown), the photosensitive drum 1 smoothly rotates through the fixed rollers 41 and 42,
Predetermined development can be performed.

FIG. 2 shows another embodiment of the present invention, focusing on the differences from the above embodiment. Reference numeral 20 denotes a support frame for supporting the exposure head 2, which positions and supports the support shaft 24, and the upper side wall of the developing sleeve 7 side is horizontally projected toward the sleeve 7 in a U-shaped 201 shape, and one lower side The part is the vertical wall 202. The roller shaft 4 is attached to the U-shaped portion 201.
The fixed roller 41A is fitted through 1a to regulate the position in the vertical direction and the horizontal direction on the drum side, and the roller shaft 42a of the regulating roller 42A is brought into contact with the lower vertical wall surface 202 so that the roller shaft 42a extends along the vertical wall surface 202. Regulation roller 42A
Is configured to be movable only in the vertical direction. Support roller 4
3 is an elongated hole 431 and a roller shaft 43 as in the above embodiment.
It is configured so as to be swingable only in the horizontal direction in which it comes in contact with and separates from the peripheral surface of the photosensitive drum 1 via a, and an elastic force is applied to the photosensitive drum 1 side by a spring 432 or the like. Development sleeve 7
Is positioned and fixed by a shaft. According to this embodiment, the support shaft 24, the exposure head 2, and the photosensitive drum 1 are integrally moved to the sleeve 7 side by the urging force of the support roller 43, the fixed roller 41A and the regulation roller 42A, and the fixed roller 41A and the regulation roller. The position of 42A is regulated in a state of being in contact with the developing sleeve 7. In this case, the regulation roller 4
By using 2A as a fixed roller, it is possible to adjust the developing gap with high accuracy.
2A is vertically moved back and forth to adjust the developing gap X, and then fixed by a fixing means (not shown). In addition, the support roller 2 for supporting the exposure head 2 with the one fixed roller 41.
By axially rotatably supporting the shaft at 0, in other words, the distance between the center axis of the exposure head 2 and the center axis of the fixed roller 41A:
Since (A ² + B ² ) ^1/2 is always constant, the distance between the photosensitive drum 1 and the exposure head 2, that is, the focal length can be accurately regulated with the fixed roller 41 as a reference surface. The development gap X, the exposure focal length, and the exposure position / development position can be regulated on the basis of a common reference between the fixed rollers 41 and 42, and the three factors that further affect the development quality are of high quality. Can be maintained at

[0021]

As described above, according to the present invention, in the so-called in-drum exposure apparatus, even when the photosensitive drum tolerance ΔL ₁ is generated and the diameter of the drum is reduced, the developing gap X and the circumferential direction are reduced. It is possible to regulate the three factors of the distance between the exposure position and the developing position in (3) and the focal length of the exposure head with high accuracy. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration around a drum of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of a main part around a drum of an exposure apparatus according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a schematic configuration of a main part around a drum of an exposure apparatus according to a conventional technique.

FIG. 4 is a cross-sectional view showing a schematic configuration of a main part around a drum of an exposure apparatus according to another conventional technique.

5 is a front view showing a schematic configuration of the exposure apparatus shown in FIG. 1 in a drum axis direction.

6 is a front view showing a schematic configuration of the exposure apparatus shown in FIG. 4 in a drum axis direction.

[Explanation of symbols]

 1 Photoreceptor Drum 7 Developing Sleeve 2 Exposure Head 41, 42, 41A Fixed Roller 42A Regulation Roller 43 Support Roller

Claims (3)

[Claims] 1. An image forming apparatus in which a developing sleeve carrying a developer is confronted with a photosensitive drum in which an exposure head is inserted, and image formation is carried out at the same time as or immediately after exposure while performing image formation. A pair of supporting rollers (hereinafter, referred to as restriction rollers) are arranged on a cross section perpendicular to the axis in a space facing the development sleeve and the photoconductor drum with the development position interposed therebetween, and the development sleeve and the photoconductor drum are respectively provided to the pair of restriction rollers. The outer peripheral surfaces of the two are brought into contact with each other to maintain a gap between the two members, and at the same time, the pair of regulation rollers are regulated to move at least in the direction of the line connecting the sleeve axis and the drum axis, while being opposed to the acting direction of the regulation rollers. One or a plurality of supporting rollers acting in a direction are brought into contact with the outer peripheral surface side or the inner peripheral surface side of the photosensitive drum, and the photosensitive drum can be rotated by the supporting roller group. An image forming apparatus characterized in that were supported. 2. A fixed roller that rotatably supports at least one of the pair of regulating rollers at a predetermined position, and one or a plurality of supporting rollers that act in the opposite direction to the regulating roller. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises one support roller that is capable of swinging in a contacting / separating direction with the peripheral surface of the photosensitive drum. 3. The image forming apparatus according to claim 2, wherein the one fixed roller is rotatably supported by a support frame that supports an exposure head.