JP3264105B2 - 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,
The present invention relates to an electrophotographic image forming apparatus that exposes and develops an image on a photosensitive drum and transfers the image to a sheet.

[0002]

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

By the way, in the clamshell type, when the upper frame is opened, the surface of the photosensitive drum is exposed to the outside, and the photosensitive drum may suffer from light fatigue,
The photoconductor may be damaged by collision of another object. Further, when the developing unit is detached from the main body frame, the developing sleeve carrying the developer is exposed to the outside. Therefore, a shutter that shields the developing sleeve when detached is required.

Japanese Patent Publication No. 4-49106 discloses a developing device provided with a shutter for shielding a developing sleeve when the developing unit is taken out. The shutter is located at a shielding position when the developing unit is set on the main body. To make the developing sleeve face the photosensitive drum.
However, when the developing unit is taken out, measures for protecting the photosensitive drum against external light and objects have not been solved.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a simple configuration in which the developing sleeve is shielded when the developing unit is removed from the main body, and the developing sleeve is mounted when the developing unit is mounted on the main body. An object of the present invention is to provide an image forming apparatus that can be opened and protect a photoconductor.

In order to achieve the above object, in an image forming apparatus according to the present invention, a developing unit having a developing sleeve can be attached to and detached from an apparatus main body in a direction perpendicular to an axial direction of a photosensitive drum. Provided a shutter member forming a part of the casing. The shutter member moves to a first position covering the outer peripheral portion of the developing sleeve when the developing unit is detached from the apparatus main body, and retracts from the first position when the developing unit is mounted on the apparatus main body, and moves to the photosensitive drum. Drum above the exposure light path for
Is moved to the second position which covers the substantially upper space portion of the.

In the above configuration, when the developing unit is separated from the apparatus main body, the shutter member moves to the first position 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 scattering or causing the operator to carelessly touch his / her hands. on the other hand,
When the developing unit is set at a predetermined position on the apparatus main body,
The shutter member is retracted from the first position and moves to a second position covering a substantially upper space portion of the photosensitive drum. As a result, the developing sleeve faces the photosensitive drum, and the upper part of the photosensitive drum is shielded by the shutter member. Therefore, for example, even when the apparatus main body is a clamshell type and the main body is opened upward for the purpose of removing jammed paper, the photosensitive drum is protected by the shutter member, and the photosensitive drum is exposed to light from the outside. Fatigue and damage due to contact with other objects can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, the present invention is applied to a laser printer.

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

The printer body is configured as a clamshell type which is divided into a fixed frame 1 and a movable 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 print conditions and the like, and removes jammed paper. The photoconductor unit 10 and the developing unit 20 are detachably mounted on the fixed frame 1 as described below, and the laser scanning optical unit 30 is installed on the front side of the fixed frame 1. The fixing device 50 includes a heating roller 51.
And the pressing roller 52, and the movable frame 7
That is, it is mounted on the back side from the operator standing in front of the printer.

The movable frame 7 is rotatable with the support shaft 2 provided on the fixed frame 1 as a fulcrum, and the printer body can be opened upward by lifting it and rotating it 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 driven to rotate in the direction of arrow a. The transfer charger 9 is attached to the fixed frame 1 so as to face the photosensitive drum 15.

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

The sheet feeding section 40 is configured to insert a sheet S into the sheet feeding table 41 from the front side. The sheets are fed one by one from the uppermost layer by the rotation of the sheet feeding roller 42. Go. The sheet that has been fed and onto which the image has been transferred is immediately separated from the photosensitive drum 15 and conveyed upward, where toner is fixed by passing between the rollers 51 and 52 of the fixing device 50, and a 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 the laser printer are well known, and a detailed description thereof will be omitted.

Next, a description will be given of the attachment / detachment structure of the photoconductor unit 10 and the developing unit 20, various shutter members and their operations. The photoconductor unit 10 has guide grooves 4 formed on both side walls of the fixed frame 1 by plates 13 fixed on 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 and detached by vertically moving guide pins 22 and 23 projecting from both sides of a casing 21 into guide grooves 5 and 6 (see FIG. 5) formed on both side walls of the fixed frame 1. The handle 2
1a. The guide groove 5 includes an inlet 5a, a first inclined portion 5b, and a second inclined portion 5c. The guide groove 6 includes an inlet portion 6a and a vertical portion 6b extending in a vertical direction at a position slightly deviated from the inlet portion 6a. When the developing unit 20 is mounted on the main body, first, the guide pins 22 and 23 are connected to the entrances 5 a and 6 of the guide grooves 5 and 6.
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 moves downward while being guided by the first inclined portion 5b. Then, the guide pin 22 includes the inclined portions 5b, 5
At this time, the developing unit 20 is temporarily hooked at the connection portion, but immediately enters the second inclined portion 5c due to the weight of the developing unit 20. As a result, the guide pin 23 moves from the entrance 6a to the vertical portion 6b (see FIG. 6). Thereafter, when the operator loosens the force holding the developing unit 20, the guide pin 22 moves down the second inclined portion 5c, and the guide pin 23 moves down the vertical portion 6b.
The developing unit 20 is set at a predetermined position when the second and third rollers 23 reach the bottoms of the guide grooves 5 and 6 (see FIG. 7).

The photosensitive unit 10 includes 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
Numeral 8 is rotatably attached to a pin 18a provided on the casing 11, and is constantly urged in a counterclockwise direction by a torsion spring (not shown). When the photoconductor unit 10 is removed from the main body and when the main body is opened, the first shutter plate 18 covers the back side of the photoconductor drum 15, that is, the transfer area, by the spring force of the torsion spring. When the movable frame 7 is closed, a projection (not shown) provided on the movable frame 7
8, the first shutter plate 18 rotates clockwise with the pin 18a as a fulcrum, and retreats upward to open the transfer area (see FIG. 1).

The second shutter plate 19 is rotatably mounted on a pin 19a provided on the casing 11, and is constantly urged in a counterclockwise direction by a torsion spring (not shown). When the developing unit 20 is removed from the main body, the second shutter plate 19 covers the developing area of the photosensitive drum 15 by the spring force of the torsion spring (see FIGS. 3 and 5). Therefore, as shown in FIG. 5, the second shutter plate 19 covers and protects the developing area of the photosensitive drum 15 at the initial stage of mounting the developing unit 20. When the developing unit 20 is mounted on the fixed side frame 1 along the guide grooves 5 and 6, the corner 2 of the casing 21
1b abuts against the second shutter plate 19 and presses downward, the second shutter plate 19 pivots clockwise about the pin 19a as a fulcrum, and retracts downward to open the developing area (FIGS. 1 and 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.
and is rotatably supported by the guide pin 23 at the end of the side plate 24a. When the developing unit 20 is detached from the main body (see FIGS. 4 and 5), the shutter plate 24
Is rotated counterclockwise by its own weight until its tip comes into contact with the corner 21 c of the casing 21, and covers the developing sleeve 25. When the developing unit 20 is mounted on the fixed frame 1, the shutter plate 24 is lifted upward with its leading end in contact with the handle 11a of the photoconductor unit 10 to open the developing sleeve 25 (see FIG. 7).

In this embodiment, 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 as described above, and scatters toner and stains an operator's hand. To prevent On the other hand, when the developing unit 20 is mounted on the fixed frame 1, the developing unit 25 is retracted upward to move the developing sleeve 25 to the photosensitive drum 1.
5 and covers the upper part of the photosensitive drum 15 (see FIG. 1). At this time, the laser scanning optical unit 30
The exposure light path b emitted from the light source passes below the shutter plate 24. Further, as shown in FIG. 2, when the jammed paper S 'is removed or the maintenance and inspection of the inside is performed, the movable frame 7 is rotated to the rear side to open the main body. Is protected by the shutter plate 24, so that the photoreceptor is not fatigued by external light or damaged by contact with other objects.

Further, in this embodiment, the photosensitive unit 1
0, a first shutter plate 18 and a second shutter plate 19 are provided. 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 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 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 where the operator stands. It is possible to eliminate the possibility that the operator accidentally touches the hot fixing device 50.

Further, when the developing unit 20 is mounted, the guide pins 23 are temporarily held at the steps of the entrance 6a, so that the guide grooves 5 and 6 do not drop suddenly, and the shock at the time of mounting is reduced. 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 attachment / detachment mechanism of the clam shell mechanism, the photoconductor unit, and the developing unit of the main body is optional.
Further, the photosensitive drum may be of a type fixed to the main body.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a state in which a main body of the laser printer is opened.

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

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixed side frame 7 ... Movable side frame 15 ... Photoconductor drum 20 ... Developing unit 21 ... Casing 24 ... Shutter plate 25 ... Developing sleeve b ... Exposure optical path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 G03G 15/08 G03G 21/16-21/18

Claims (1)

(57) [Claims] 1. An electrophotographic image forming apparatus comprising: a fixed body frame and a movable body frame that can be opened upward.
2 split device body and over arm; photosensitive drum is housed in the fixed body frame; a developing unit having a developing sleeve, the developing unit be perpendicular to the axial direction of the photosensitive drum to the stationary body frame
The main body is detachably housed in the direction
When the frame is released, upward from the fixed body frame
Can be released into; the shutter member constituting a part of a casing of the developing unit, the shutter member developing unit is stationary body
When the developing unit is removed from the frame, it moves to the first position covering the outer peripheral portion of the developing sleeve, and the developing unit moves to the fixed side main body frame.
When mounted to the over arm is an upper exposure light path to the photosensitive drum is retracted from the first position of the photosensitive drum
Moving to a second position covering a substantially upper space portion ;