JPH04156578A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the photosensitive surface of a photosensitive drum from being scratched during removal of the drum from a photosensitive drum device, by providing spacers made of a resin material, at the front end of a sheet guide for guiding a recording sheet onto the photosensitive surface of the photosensitive drum. CONSTITUTION:A recording sheet 20a is guided by a sheet guide 55b and is led between spacers 16a, 16b which are provided at the front end of the guide 55b. Upon removal of a photosensitive drum 51a from an image forming device for maintenance or the like, when an mounting bed 12b is turned, the front end of a projection 17 is retracted from a space between one end face of the drum 51a and a cover plate 11a, and the guide 55b and an image transfer unit 56a are retracted. Accordingly, the cover plate 11a is removed from a side frame 9b in order to remove the drum 51a through an opening 90a. At this time, should the cover plate 11 be erroneously removed with no retracting operation, a shaft 7a defects, and accordingly the photosensitive surface abuts against spacer 16b without abutting against the guide 55b. However, since the spacers 16a, 16b are made of resin, the photosensitive surface is prevented from being scratched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] An image forming apparatus in which a spacer made of a resin material is provided at both longitudinal ends of a paper guide that guides recording paper to a photosensitive surface of a photosensitive drum. The purpose of the present invention is to provide an image forming apparatus that can prevent the photosensitive surface from being scratched when taken out from the apparatus.The image forming apparatus is supported by bearings at both ends of the central shaft, one of the bearings is attached to the apparatus frame, and the other is supported by bearings. is removably attached to an opening provided in the device frame and attached to a lid plate that constitutes a part of the device frame, and is formed on the image forming surface of a cylindrical image forming body having an image forming surface on the outer periphery. An image forming device that develops an electrostatic image and transfers and fixes it onto a printing medium guided by a paper guide, the image forming device having a first gap that allows the printing medium to pass through the image forming surface of the image forming body. At least on the lid plate side of both ends that do not obstruct the passage of the printing medium in the longitudinal direction of the tips of the media guides facing each other, a first
The apparatus includes spacers facing each other with a second gap smaller than the gap therebetween, and when the image forming body is taken out from the apparatus, the lid part is removed from the apparatus frame and the image forming body is taken out from the opening.

[Industrial application field]

The present invention relates to an image forming apparatus such as an electrophotographic printing apparatus used in a copying apparatus and a printer, and in particular, a resin material is used at both longitudinal ends of the tip of a paper guide that guides recording paper to the photosensitive surface of a photosensitive drum. The present invention relates to an image forming apparatus provided with a spacer formed of.

2. Description of the Related Art Recently, with the rapid spread of office automation equipment, electrophotographic printing devices such as copying machines and printers are becoming widespread.

In this device, when pulling out the photosensitive drum from the device during maintenance, etc., the mounting base on which the paper guide and transfer device are mounted is evacuated from the photosensitive drum, and the photosensitive surface of the photosensitive drum is taken out without touching the paper guide, etc. However, if the mounting base is pulled out without being evacuated, the photosensitive surface will be damaged and the life of the photosensitive drum will be shortened, so a mechanism to prevent this is desired.

[Conventional technology]

FIG. 5 illustrates an internal side view of the electrophotographic printing apparatus. In the figure, 1 is a cassette mounting part, 2 is a cassette, and 3 is a cassette mounting part.
4 is a feeding roller, 4 is a conveyance path, 5 is a printer section, and 6 is a stacker.

The printer section 5 includes an optical unit 50. Photosensitive drum 51a
, cleaner section 52. Charger 53. Developing device 54. Paper guide 55a, transfer device 56. Static eliminator 57. and a fixing device 58.

A cassette 2 is set in the cassette loading section 1, and the cassette 2 contains printing paper (hereinafter referred to as paper) 20 of a desired size.
A is accumulated and stored.

With this configuration, when the power of the apparatus is turned on, the fixing section 58 is heated to a predetermined temperature and becomes ready for printing, and then the paper 20a is fed out from the cassette 2 in the direction of arrow B based on the print instruction signal, and the paper 20a is fed out to the transport path 4. paper guide 5.
5a and sent below the photosensitive drum 51a. By this time, the photosensitive drum 51a has been neutralized by the static eliminator 57, residual toner has been cleaned by the cleaner section 52a, and charged again by the charger 53.

Light data emitted from an optical unit 50 composed of a laser light source or the like is scanned onto a photosensitive drum 51a, and the electrostatic image formed on the photosensitive drum 51a is transferred to a developing device 54.
The toner image is developed into a toner image, transferred to the paper 20a by the transfer device 56, fixed by the fixing device 58, and the paper 20a is sent to the stacker 6.

Here, since it is necessary to take out the photosensitive drum 51a from the apparatus during maintenance such as cleaning or replacement of the photosensitive drum 51a, the configuration is as follows.

As shown in the cross-sectional view of FIG. 6(a), the photosensitive drum 51a
is engaged with the shaft 7a in the rotational direction and slidably fitted in the axial direction, and the right end of the shaft 7a in the figure is supported by a support housing 80 having bearings 8a and 8b spaced apart, The support housing 80 is attached to the side frame 9a of the device.

The right end of the shaft 7a protruding from the side frame 9a is connected to a drive source (not shown). The left end of the shaft 7a is supported by a bearing 8c, the bearing 8C is attached to a cover plate 11a, and the cover plate 11a is detachably attached to a sight frame 9b to constitute a part of the side frame 9b, and a plurality of positioning pins 1 It is positioned at an angle of 100 degrees and attached with screws not shown.

The cover plate 11a is formed to face the end surface of the photosensitive drum 51a and has a larger area than the end surface, and when the cover plate 11a is removed, there is an opening in the side frame 9b large enough to allow the photosensitive drum 5 to be pulled out. Section 9o is designed to open. Furthermore, a plurality of holes 510 are provided on the end surface of the photosensitive drum 51a, into which an operator's fingers can be inserted.

Further, as shown in the side view of FIG. 6(b), the paper guide 5
5a, and transfer device 56 or mounting stand! It is installed in 2a. The paper guide 55a is made of a metal 1, for example, a stainless steel plate, so as not to deform over time, and is attached to the member 12.
0, and the tip is fixed to the photosensitive drum surface of the photosensitive drum 51a through a gap ε, (for example, 0
．． 5mm).

One end of the mounting base 12a (in FIG. 3), the left end is rotatably supported by a support shaft 13a, and the other end is a free end. A roller R1 at the upper end of the swing lever 14 is in rolling contact with the lower surface of the mounting base 12a, and the lower end of the swing lever 14 is fixed to a rotation shaft 15. The pivot shaft 15 is provided with a lever handle (not shown), and the pivot lever 14 is pivoted in the directions of arrows EIIC and D by rotating the lever handle in forward and reverse directions. As the swinging lever 14 swings, the mounting base 12a rotates about the support shaft 13a in the directions of arrows E and F, and the paper guide 55a and transfer device 56 approach (set) and retreat from the photosensitive surface of the photosensitive drum 51a. (Reset.

Further, a roller R2 shown by a broken line in the figure is provided on the right side surface of the mounting table 12a, and when the mounting table 12a is set, the roller R2 rolls into contact with the feed roller R3 that conveys the paper 20a above to position the mounting table 12a. is decided.

With this configuration, when taking out the photosensitive drum 51a from the apparatus, first rotate the lever handle in the direction of the arrow, and as shown by the two-dot chain line in the figure, the mounting base 12
Since it is reset by rotating in the direction of arrow F, next remove the cover plate 11a and remove the photosensitive drum 51 from the opening 90.
a by the hole 510 and pull it out. When installing the photosensitive drum 51a, perform this process in reverse order.

[Problem to be solved by the invention]

According to the conventional method described above, when pulling out the photosensitive drum from the device, the mounting base must be reset and the cover plate removed before pulling out the photosensitive drum. However, if the cover plate is removed while the mounting base is set, , the shaft bends due to the weight of the photosensitive drum, and the photosensitive surface hits the tip of the paper guide, damaging the photosensitive surface.Also, if you take the photosensitive drum out of the opening in this condition, the photosensitive surface or the tip of the paper guide will be damaged in the process of taking it out. There is a problem in that the photosensitive drum is rubbed against the drum, causing even larger scratches, and shortens the life of the photosensitive drum.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can prevent the photosensitive surface from being scratched when the photosensitive drum is taken out of the apparatus.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention, and (a) is a side view of the main part.

(b) is a front view as viewed from the A direction.

In the figure, 7 is a central axis, 8 is a bearing, 9 is an apparatus frame, 11 is a lid plate, 20 is a printing medium, 51 is an image forming body, 55
90 is a medium guide, 90 is an opening, and 16 is a print medium 2 in the longitudinal direction at the tip of the medium guide 55 facing the image forming surface of the image forming body 51 through a first gap through which the print medium 20 can pass.
0 at both ends (both on the cover plate 11 side,
The spacer faces the image forming surface with a second gap smaller than the first gap interposed therebetween.

Therefore, when taking out the image forming body 51 from the apparatus, the cover 11
The image forming body 51 is removed from the apparatus frame 9 and the image forming body 51 is taken out from the opening 90.

[Effect]

When taking out the image forming body 5I from the apparatus, first remove the cover plate 11, and the central axis 7 is bent by the weight of the image forming body 51, and the image forming surface or at least the second gap smaller than the first gap is bent. Since it hits the spacer 16 at the tip on the lid plate 11 side and prevents it from hitting the medium guide 55, the image forming body 5J can be taken out from the opening 90 without damaging the image forming surface by the spacer 16. The life of the image forming body 5I can be ensured.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 2 and 3. The same reference numerals indicate the same objects throughout the figures.

FIGS. 2(a) to 2(d) show main part configuration diagrams in which the present invention is applied to the electrophotographic printing apparatus described in the conventional example.

The shaft 7a, bearings 88 to 8c, sights, frames 9a, 9b, photosensitive drum 51a, and paper guide 55b in FIG. 2 are connected to the central shaft 7 in FIG. Bearing 8. Equipment frame9. image forming body 5] and medium guide 55, respectively.

FIG. 2(a) is a side view of the main part, and FIG. 2(b) is a front view as viewed from the arrow A'.

(C) and (d) are enlarged side views of the mounting base.

As shown in FIGS. 2(a) and (b), the paper guide 55
Spacers 16a and 16b are provided at both ends of the tip of b. Spacers 16a and 16b are photosensitive drums 51
There is a slight gap ε2 (for example, 0.25 m) on the photosensitive surface below a.
The distance between the spacers 16a and 16b is set to be larger than the radius of the paper 20a being conveyed.

Therefore, the paper 20a is guided by the paper guide 55b, passes between the spacers 16a and 16b, and is sent to the photosensitive surface.

Further, as shown in FIGS. 2(C) and (d), the paper guide 55b is located at the end of the upper surface of the mounting table 12b on which the paper guide 55b and the transfer device 56 are mounted, on the side corresponding to the cover plate 11a in the longitudinal direction. A protrusion 17 is provided at a position approximately corresponding to .

The tip of the protrusion 17 is attached to the paper guide 55b and the transfer device 5 when the mounting base 12b rotates as the swing lever 14 rotates.
6 approaches the photosensitive surface of the photosensitive drum 51a, it enters between the end surface of the photosensitive drum 51a and the cover plate 11a as shown in the figure, and when the paper guide 55b and the transfer device 56 retreat from the photosensitive surface , as shown in FIG. 3, is formed so as to be retracted from between the end surface of the photosensitive drum 51a and the cover plate 11a.

With this configuration, when taking out the photosensitive drum 51a from the apparatus for maintenance or the like, the swinging lever 14 is moved to the retracting position of the lever handle, that is, by rotating the lever handle in the direction of the arrow. 12b rotates in the direction of arrow F, and the tip of the projection 17a or the photosensitive drum 51a
and the cover plate 11a, and the photosensitive drum 5
The paper guide 55b and the transfer device 56, which were close to the photosensitive surface 1a, retreat.

Then, the lid plate 11a is removed from the side frame 9b and the photosensitive drum 51a is taken out from the opening 90a.

At this time, if the cover plate 11a is removed without accidentally retracting the lever handle, that is, without retracting the paper guide 55b and the transfer device 56 from the photosensitive surface, the photosensitive drum 51
If the shaft 7a bends due to the weight of a, the gap ε between the paper guide 55a and the photosensitive surface, or the gap ε between the spacer 16b and the photosensitive surface.
2 is smaller, so the photosensitive surface does not hit the paper guide 55b, but hits the spacer 16b, or the photosensitive surface hits the spacer 16
Since it is made of a resin material, it does not scratch the photosensitive surface.

Also, if you try to take out the photosensitive drum 51a,
The end surface of the photosensitive drum 51a or the tip of the protrusion 17 engages with the photosensitive drum 51a and it cannot be taken out. Then, the photosensitive drum 51a can be taken out by operating the lever handle to rotate the mounting base 12b and retracting the protrusion 17 from the end surface of the photosensitive drum 51a. At this time, the paper guide 55b and the transfer device 56 are naturally retracted from the photosensitive surface, so that the photosensitive surface does not rub against the spacers 16a, 16b and will not cause any damage.

In this way, when the cover plate 11a is removed without retracting the lever handle, the photosensitive surface will not be damaged even if it hits the paper guide 55b due to the deflection of the shaft 7a, and the lever handle can be retracted by the protrusion 17. The photosensitive drum 51a cannot be pulled out without operation,
Since the photosensitive drum 51a is taken out from the opening 90a after the retracting operation, the photosensitive surface will not be rubbed and no scratches will occur, and therefore the life of the photosensitive drum 51a can be extended.

Further, FIG. 4 shows a different embodiment. As shown in the figure, a spacer 16c formed of a resin material with a small coefficient of friction is attached to the entire length of the width of the tip of the paper guide 55c, creating a gap on the photosensitive surface of the photosensitive drum 51a through which the paper 20a can pass. ε, is provided.

Therefore, the spacer 16c guides the paper 20a and prevents scratches when the photosensitive surface of the photosensitive drum 51a hits the spacer 16c.

In addition, spacers 1 of the above-mentioned embodiments are not shown in the drawings.
It is also possible to divide the paper guide 51c into a plurality of parts and attach them to a plurality of locations symmetrically from the center of both ends and the tip of the paper guide 51c.

〔Effect of the invention〕

As described above, according to the present invention, by providing a spacer at the tip end of the medium guide, when the image forming body is taken out from the apparatus, the medium guide is not retracted from the image forming surface of the image forming body. When removing the cover plate from the device frame,
This prevents damage even if the central axis bends due to the weight of the image forming body and hits the image forming surface, and image formation is prevented unless the medium guide is retracted from the image forming surface by the protrusion that engages the end surface of the image forming body. Since the body is prevented from being taken out, it is pulled out after being evacuated, so it does not rub against the image forming surface or the spacer, and it is possible to prevent scratches or damage, which can extend the life of the image forming body. It's effective.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of the present invention, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is an explanatory diagram of the embodiment, Fig. 4 is a block diagram showing a different embodiment, and Fig. 5 is a block diagram showing an embodiment of the present invention. FIG. 6 is an internal side view of an electrophotographic printing apparatus showing a conventional example. FIG. 6 is a configuration diagram showing a conventional example. In the figure, 7 is the central axis, 7a is the shaft, 8 is the bearing,
8a to 8C are bearings, 9 is device frame, 9a, 9b are side frames, 11), 1
a is a cover plate, 16.16a to 16c are spacers, 17 is a projection, 20 is a printing medium, 20a is paper, 51 is an image forming body, 51a is a photosensitive drum, 55 is a medium guide, 55a is a paper guide,
90.90a indicates an opening. 90 Opening (θ) One view of the wife's stool (b) Front view of the A direction Hisae Principle diagram of the present invention No. 1 Drawing lees P+1 (k) One view of the sheep's stool (1)) A' direction arrow Front view of Tachibana showing undefined fireworks Figure 2 (Zone 1) (C) Enlarged 911 view of Jigyo 0 ((I) Kaisou C part and Ichiku I3 Stone skin part 1 7. Right 1 M - B Complete example and illustration of the tree Figure Wl z Figure (Part 2) 1!Original part 3 Figure 4 Blink Repetition Electrophotograph ET shown in the example 'J Printing's Internal Plan No.
5 Figure

Claims (1)

[Claims] 1) Both ends of the central shaft (7) are supported by bearings (8), respectively;
One of the bearings (8) is attached to the device frame (9), and the other is attached to the opening (9) provided in the device frame (9).
0) and is attached to a lid plate (11) that constitutes a part of the device frame (9), and has an image forming surface on its outer periphery. An image forming apparatus that develops an electrostatic image formed on a surface of the image forming body (51), and transfers and fixes the electrostatic image onto a printing medium (20) that is guided and conveyed by a medium guide (55). The printing medium (20
) at least on the lid plate (11) side of both ends that do not obstruct the passage of the print medium (20) in the longitudinal direction of the tip of the medium guide (55) facing each other with a first gap through which the medium guide (55) can pass; A spacer (16) facing the image forming surface with a second gap smaller than the first gap is provided, and the image forming body (
51) from the device, remove the lid (11) from the device frame (9) and open the opening (9).
An image forming apparatus characterized in that the image forming body (51) is taken out from the image forming body (51). 2) The spacer (16) is made of a resin material with a small coefficient of friction, and extends over the entire length of the tip of the medium guide (55) in the longitudinal direction, or at multiple locations symmetrical from both ends and the center. The image forming apparatus according to claim 1, wherein the image forming apparatus is attached to the forming body (51) so as to face each other with the first gap interposed therebetween. 3) Consisting of a rotating means and a mounting base, the rotating means is for rotating the mounting base by a predetermined angle, the mounting base is equipped with the medium guide (55), and one end is rotated by a support shaft. The medium guide (55), which is freely supported, approaches and retreats from the image forming surface of the image forming body (51) by rotating the mounting base by the rotating means, and when it approaches, the medium guide (55) approaches and retreats from the image forming surface of the image forming body (51). (51) has a protrusion that at least partially enters the front surface of the end surface facing the lid plate (11) and retreats from the front surface of the end surface when the lid plate (11) is retreated; Only when the base is rotated and the protrusion is retracted from the front surface of the end face of the image forming body (51),
Claim 1 characterized in that the apparatus is configured such that the image forming body (51) can be taken out from the opening (90) after the lid plate (11) is removed from the apparatus frame (9).
Alternatively, the image forming apparatus according to 2.