JPH0844271A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an electrophotographic image forming device constituted so that a developing sleeve is shielded when a developing unit is taken out from a main body and opened when the developing unit is loaded in the main body and a photoreceptive drum is protected by simple constitution. CONSTITUTION:A photoreceptor unit 10 including the photoreceptive drum 15 and the developing unit 20 including the developing sleeve 25 are set so that they can be independently attached/detached with respect to a fixed-side frame 1. Then, the unit 20 is provided with a shutter plate 24. When the unit 20 is detached from the frame 1, the sleeve 25 is covered with the plate 24. When it is attached to the frame 1, the plate 24 is moved to a position where the upper part of the drum 15 is covered with it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly to
The present invention relates to an electrophotographic image forming apparatus that exposes and develops an image on a photosensitive drum and transfers the image onto a sheet.

[0002]

2. Description of the Related Art In recent years, various small laser printers based on electrophotography have been provided as devices for outputting image information from a computer. In this type of laser printer, the printer main body is divided into two along a substantially paper-passing path for maintenance, inspection and elimination of jammed paper, and the upper frame can be opened with respect to the lower frame. The so-called clamshell type is common. In addition, in order to simplify maintenance, the photoconductor drum and the developing device are unitized, and the structure that is detachable from the body frame is adopted.

By the way, in the clamshell type, when the upper frame is opened, the surface of the photoconductor drum is exposed to the outside, and the photoconductor is subject to light fatigue.
There is a risk that other objects may collide and damage the photoconductor. Further, when the developing unit is removed from the main body frame, the developing sleeve carrying the developer is exposed to the outside. Therefore, a shutter is required to shield the developing sleeve when detached.

Japanese Patent Publication No. 4-49106 discloses a developing device provided with a shutter that shields the developing sleeve when the developing unit is taken out, and the shutter has a shielding position when the developing unit is set in the main body. The developing sleeve is moved away from the photosensitive drum so as to face the photosensitive drum.
However, when the developing unit is taken out to the outside, a measure to protect the photoconductor drum from light and an object from the outside has not been solved.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to have a simple structure and to shield the developing sleeve when the developing unit is taken out from the main body and to keep the developing sleeve when the developing unit is attached to the main body. An object of the present invention is to provide an image forming apparatus capable of opening and protecting the photoconductor.

In order to achieve the above object, in the image forming apparatus according to the present invention, a developing unit having a developing sleeve is attachable to and detachable from the main body of the apparatus in a direction orthogonal to the axial direction of the photosensitive drum. Is provided with a shutter member forming a part of the casing. The shutter member moves to a first position that covers the outer peripheral portion of the developing sleeve when the developing unit is detached from the main body of the apparatus, and retracts from the first position when the developing unit is attached to the main body of the apparatus and the photosensitive drum. Move to a second position covering.

With the above arrangement, when the developing unit is detached from the apparatus main body, the shutter member moves to the first position for covering the developing sleeve. This prevents the developing sleeve from being shielded by the shutter member, and prevents the developer adhering to the outer peripheral surface of the developing sleeve from being scattered or the operator's hand being touched carelessly to soil the hand. on the other hand,
When the developing unit is set at the predetermined position on the main body of the device,
The shutter member retracts from the first position and moves to a second position that covers the photosensitive drum. As a result, the developing sleeve faces the photoconductor drum, and the upper part of the photoconductor drum is shielded by the shutter member.
Therefore, for example, even if the main body of the apparatus is a clamshell type and the main body is opened upward to remove jammed paper, etc., the photoconductor drum is protected by the shutter member, and the light is emitted from the outside. It is possible to prevent fatigue and damage due to contact with other objects.

[0008]

Embodiments of the image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. The embodiment described below is one in which the present invention is applied to a laser printer.

The laser printer has a photoconductor unit 10 (see FIG. 3) and a developing unit 20 (see FIG. 4) at the center.
1, the laser scanning optical unit 30 is arranged on the right side in FIG. 1, the paper feeding section 40 is arranged on the lower part, and the fixing device 50 is arranged on the upper part.

The printer body is constructed as a clamshell type, which is divided into a fixed side frame 1 and a movable side frame 7, and the direction indicated by arrow A is the front side. That is,
The operator faces the printer in the direction of arrow A to set printing conditions or remove jammed paper. The photoconductor unit 10 and the developing unit 20 are detachably installed on the fixed side frame 1 as described below, and the laser scanning optical unit 30 is installed on the front side of the fixed side frame 1. The fixing device 50 is a heating roller 51.
And the pressure contact roller 52, the movable side frame 7
That is, it is mounted on the back side from the operator standing in front of the printer.

The movable side frame 7 is rotatable around a support shaft 2 provided on the fixed side frame 1 as a fulcrum, and the printer body can be opened upward by lifting and rotating the frame rearward (see FIG. 2). ). The photoconductor unit 10 has a casing 11 in which a photoconductor drum 15 and a charging brush 16 are housed, and the photoconductor drum 15 can be rotationally driven in the direction of arrow a. A transfer charger 9 is attached to the fixed-side frame 1 so as to face the photoconductor drum 15.

The developing unit 20 has a casing 21 in which a developing sleeve 25 and a developer stirring roller 26 are accommodated. Toner is accommodated in a tank portion 27 and is appropriately replenished to the stirring roller 26. The toner is supplied to the outer peripheral surface of the developing sleeve 25 while being agitated with the developer by the agitating roller 26. The laser scanning optical unit 30 includes a housing 31.
Laser diode (not shown) inside, polygon mirror 3
2, a lens 33, 34, a mirror 35, etc., which modulates a laser diode based on image information transferred from an external host device (for example, a microcomputer) and deflects the laser beam by the polygon mirror 32. , The photoconductor drum 15 from the mirror 35 through the optical path b.
Illuminate the surface of.

The sheet feeding section 40 is constructed such that the sheet S is inserted into the sheet feeding table 41 from the front side, and the sheets are fed one by one from the uppermost one by the rotation of the sheet feeding roller 42. Go. The sheet that has been fed and to which the image has been transferred is immediately separated from the photosensitive drum 15 and conveyed upward, where it passes between the rollers 51 and 52 of the fixing device 50 to fix the toner, and the discharge roller. The paper is discharged from the pair 55 onto the paper discharge tray 7a. The paper discharge tray 7a is formed integrally with the movable frame 7.

The image forming steps of exposure, development and transfer in this laser printer are well known, and detailed description thereof will be omitted.

Next, the detachable structure of the photoconductor unit 10 and the developing unit 20 and various shutter members and their operations will be described. The photoconductor unit 10 has guide grooves 4 formed on both side walls of the stationary frame 1 by plates 13 fixed to both sides of a casing 11 via pins 12 (see FIG. 5).
It is attached and detached by moving up and down inside, and has a handle 11a for attachment and detachment. The guide groove 4 extends in the vertical direction, and when the plate 13 reaches the bottom of the guide groove 4, the photoconductor unit 10 is set at a predetermined position.

The developing unit 20 is attached / detached by vertically moving guide pins 22 and 23 projecting on both sides of the casing 21 in guide grooves 5 and 6 (see FIG. 5) formed on both side wall portions of the stationary frame 1. And handle 2 for attaching and detaching
1a. The guide groove 5 includes an inlet portion 5a, a first inclined portion 5b and a second inclined portion 5c. The guide groove 6 is composed of an inlet portion 6a and a vertical portion 6b extending in the vertical direction at a position slightly deviated from the inlet portion 6a. When the developing unit 20 is attached to the main body, first, the guide pins 22 and 23 are inserted into the guide grooves 5 and 6, respectively.
It is positioned at a (see FIG. 5), and the inner side of the casing 21 is rotated downward with the guide pin 23 as a fulcrum. At this time, the guide pin 22 is guided by the first inclined portion 5b and moves downward. Then, the guide pin 22 has the inclined portions 5b, 5
Although it is in a state of being temporarily hooked at the connection portion of c, it immediately enters the second inclined portion 5c due to the weight of the developing unit 20. Accordingly, the guide pin 23 moves from the inlet portion 6a to the vertical portion 6b (see FIG. 6). Then, when the operator loosens the force holding the developing unit 20, the guide pin 22 moves downward on the second inclined portion 5c, and the guide pin 23 moves downward on the vertical portion 6b.
The developing unit 20 is set at a predetermined position when the reference numerals 2 and 23 reach the bottoms of the respective guide grooves 5 and 6 (see FIG. 7).

The photoconductor unit 10 is provided with a first shutter plate 18 and a second shutter plate 19 as a part of the casing 11 (see FIG. 3). First shutter plate 1
8 is rotatably attached to a pin 18a provided in the casing 11, and is constantly urged in a counterclockwise direction by a torsion spring (not shown). The first shutter plate 18 covers the inner side of the photoconductor drum 15, that is, the transfer area by the spring force of the torsion spring when the photoconductor unit 10 is taken out of the body and when the body is opened. When the movable frame 7 is closed, the protrusion (not shown) provided on the movable frame 7 causes the first shutter plate 1 to move.
8 is pressed, the first shutter plate 18 rotates clockwise about the pin 18a as a fulcrum, and retracts upward to open the transfer area (see FIG. 1).

The second shutter plate 19 is rotatably attached to a pin 19a provided on the casing 11, and is constantly urged counterclockwise by a torsion spring (not shown). The second shutter plate 19 covers the developing area of the photosensitive drum 15 by the spring force of the torsion spring when the developing unit 20 is taken out from the main body (see FIGS. 3 and 5). Therefore, as shown in FIG. 5, at the initial stage of mounting the developing unit 20, the second shutter plate 19 covers and protects the developing area of the photosensitive drum 15. When the developing unit 20 is mounted on the stationary frame 1 along the guide grooves 5 and 6, the corner portion 2 of the casing 21
1b abuts against the second shutter plate 19 and presses downward, the second shutter plate 19 rotates clockwise around the pin 19a as a fulcrum, and retreats downward to open the developing area (FIG. 1, FIG. 1). 7).

On the other hand, the developing unit 20 is provided with a shutter plate 24 as a part of the casing 21 (see FIGS. 4 and 5). This shutter plate 24 has side plates 24 on both sides.
a, and is rotatably supported by the guide pin 23 at the end of the side plate 24a. When the developing unit 20 is separated from the main body (see FIGS. 4 and 5), the shutter plate 24
Covers the developing sleeve 25 by rotating counterclockwise by its own weight until its tip comes into contact with the corner 21c of the casing 21. When the developing unit 20 is mounted on the fixed frame 1, the tip of the shutter plate 24 contacts the handle 11a of the photoconductor unit 10 and is lifted upward to open the developing sleeve 25 (see FIG. 7).

In the present embodiment, as described above, the shutter plate 24 covers the outer peripheral portion of the developing sleeve 25 when the developing unit 20 is detached from the fixed side frame 1 to prevent the toner from scattering and the operator's hand from getting dirty. Prevent. On the other hand, when the developing unit 20 is mounted on the stationary frame 1, the developing sleeve 25 is retracted upward and the developing sleeve 25 is moved to the photosensitive drum 1.
5 and covers the upper side of the photosensitive drum 15 (see FIG. 1). At this time, the laser scanning optical unit 30
The exposure light path b radiated from the laser beam passes below the shutter plate 24. Further, as shown in FIG. 2, when the jammed paper S ′ is removed or the internal maintenance is performed, the movable side frame 7 is rotated to the back side to open the main body. Is protected by a shutter plate 24, so that the photoconductor is not fatigued by light from the outside and is not damaged by the contact of other objects.

Further, in this embodiment, the photoconductor unit 1
0 is provided with a first shutter plate 18 and a second shutter plate 19, the first shutter plate 18 protects the transfer area of the photosensitive drum 15 when the main body is opened, and the second shutter plate 19 develops. When the unit 20 is detached, the developing area of the photosensitive drum 15 is protected.

Further, the fixing device 50 is attached to the movable side frame 7, and when the main body is opened (see FIG. 2), the fixing device 50 moves in a direction away from the front side on which the operator stands. It is possible to eliminate the risk that an operator carelessly touches the hot fixing device 50.

Further, when the developing unit 20 is mounted, the guide pin 23 is once held by the stepped portion of the inlet portion 6a, so that the guide grooves 5 and 6 do not drop suddenly and the impact at the time of mounting is alleviated. it can.

The image forming apparatus according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. In particular, the clamshell mechanism of the main body, the photoconductor unit, and the attachment / detachment mechanism of the developing unit are optional.
Further, the photosensitive drum may be of a type fixed to the main body.

[Brief description of drawings]

FIG. 1 is a sectional view showing an internal structure of a laser printer which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state where the main body of the laser printer is opened.

FIG. 3 is a cross-sectional view showing a photoconductor unit.

FIG. 4 is a sectional view showing a developing unit.

FIG. 5 is an explanatory view showing a mounting operation of the developing unit.

FIG. 6 is an explanatory view showing a mounting operation of the developing unit.

FIG. 7 is an explanatory view showing a mounting operation of the developing unit.

[Explanation of symbols]

 1 ... Fixed-side frame 7 ... Movable-side frame 15 ... Photosensitive drum 20 ... Developing unit 21 ... Casing 24 ... Shutter plate 25 ... Developing sleeve b ... Exposure optical path

Claims (2)

[Claims] 1. An electrophotographic image forming apparatus having the following structure: a developing unit having a developing sleeve; the developing unit being attached to and detached from a main body of the apparatus in a direction orthogonal to an axial direction of a photosensitive drum. It is possible; a shutter member forming a part of the casing of the developing unit, the shutter member being moved to a first position covering the outer peripheral portion of the developing sleeve when the developing unit is detached from the apparatus main body, The image forming apparatus, which is retracted from the first position when moved to the main body of the apparatus and moves to the second position where the photosensitive drum is covered. 2. The image forming apparatus according to claim 1, wherein:
The apparatus main body is divided into a fixed side main body frame and a movable side main body frame that can be opened upward; the photosensitive drum and the developing unit are housed in the fixed side main body frame, and the developing unit is the movable side main body frame. When the developing unit is attached to the fixed side frame, the shutter member is above the exposure optical path to the photosensitive drum when the developing unit is mounted on the fixed side frame.
The photosensitive drum is moved to a position that covers a space substantially above the photosensitive drum.