JP2939320B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] The present invention relates to an image forming apparatus in which spacers formed of a resin material are provided at both longitudinal ends of a paper guide for guiding recording paper to a photosensitive surface of a photosensitive drum. An object of the present invention is to provide an image forming apparatus capable of preventing a photosensitive surface from being damaged when taken out of the apparatus. Both ends of a central shaft are supported by bearings, respectively, and one of the bearings is attached to an apparatus frame. The other is detachably mounted in an opening provided in a side portion of the apparatus frame, is attached to a lid plate forming a part of the apparatus frame, and forms an image of a cylindrical image forming body having an image forming surface on an outer periphery. An image forming apparatus that develops an electrostatic image formed on a surface, transfers the image to a print medium guided by a paper guide, and fixes the transferred image, wherein the print medium can pass through the image forming surface of the image forming body. During the first The image forming surface is formed of a resin material opposed to the image forming surface via a second gap smaller than the first gap at both ends which do not hinder the passage of the print medium in the longitudinal direction at the leading end of the medium guide facing the gap. When the image forming body is taken out of the apparatus, the lid is detached from the side of the apparatus frame, and the image forming body is taken out from the opening.

[Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying apparatus and an electrophotographic printing apparatus used for a printer or the like, and in particular, a resin is provided at both longitudinal ends of a paper guide for guiding recording paper to a photosensitive surface of a photosensitive drum. The present invention relates to an image forming apparatus provided with a spacer formed of a material.

2. Description of the Related Art In recent years, with the rapid spread of office automation equipment, electrophotographic printing apparatuses have been widely used in copiers, printers, and the like.

In this apparatus, when the photosensitive drum is pulled out of the apparatus during maintenance or the like, the mounting table on which the paper guide and the transfer device are mounted is retracted from the photosensitive drum, and is taken out so that the photosensitive surface of the photosensitive drum does not touch the paper guide and the like. However, since the mounting table is pulled out without being retracted, the photosensitive surface is damaged and the life of the photosensitive drum is shortened. Therefore, a mechanism for preventing 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 section, 2 is a cassette, 3 is a feeding roller, 4 is a conveyance path, 5 is a printer section, and 6 is a stacker.

The printer unit 5 includes an optical unit 50, a photosensitive drum 51a, a cleaner unit 52, a charger 53, a developing unit 54, a paper guide 55a, and a transfer unit 5.
6. It comprises a static eliminator 57 and a fixing device 58.

A cassette 2 is set in the cassette mounting section 1, and a desired size of printing paper (hereinafter referred to as paper) 20 is set in the cassette 2.
a is housed collectively.

With this configuration, the fusing unit can be
58 is heated to a predetermined temperature to be in a printable state, and the sheet 20a is moved from the cassette 2 to the arrow B based on the print instruction signal.
The sheet is fed in the direction, is conveyed along the conveyance path 4 and is guided by the paper guide 55a to be sent below the photosensitive drum 51a. By this time, the photosensitive drum 51a has been discharged by the discharger 57, the residual toner has been cleaned by the cleaner 52a, and has been charged again by the charger 53.

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

Here, at the time of maintenance such as cleaning and replacement of the photosensitive drum 51a, the photosensitive drum 51a needs to be taken out of the apparatus, so that the configuration is as follows.

As shown in the sectional view of FIG.
Is engaged with the shaft 7a in the rotational direction and slidably fitted in the axial direction.The right end in the drawing of the shaft 7a is supported by a support housing 80 having spaced bearings 8a and 8b. The housing 80 is the side frame 9a of the device
Attached to.

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 mounted on the side frame 9b to form a part of the side frame 9b, and includes a plurality of positioning pins 10c. And is attached with screws not shown.

The cover plate 11a faces the end surface of the photosensitive drum 51a and is formed to have a larger area than the end surface.When the cover plate 11a is removed, an opening 90 large enough to allow the photosensitive drum 51a to be pulled out is formed in the side frame 9b. It is designed to open. The end surface of the photosensitive drum 51a is provided with a plurality of holes 510 into which a finger can enter so that the operator can pull it out.

Further, as shown in the side view of FIG.
The transfer device 55a and the transfer device 56 are mounted on the mounting table 12a. Paper guide 55a is formed a metal so as not to deform with time or the like, for example, a stainless steel plate, have been screwed to the mounting member 120, the gap epsilon ₁ tip passes the paper 20a to the photosensitive drum surface of the photosensitive drum 51a (e.g. 0.5 mm).

One end of the mounting table 12a, the left end in the figure, is rotatably supported by a support shaft 13a, and the other end is a free end. Mounting stand 12a
The roller R1 at the upper end of the swing lever 14 is in rolling contact with the lower surface of the swing lever 14, and the lower end of the swing lever 14 is fixed to the rotating shaft 15.
A lever handle (not shown) is provided on the rotating shaft 15,
The swing lever 14 is swung in the directions of arrows C and D by turning the lever handle in the forward and reverse directions. The swing of the swing lever 14 causes the mounting table 12a to rotate in the directions of arrows E and F about the support shaft 13a, and the paper guide 55a and the transfer device 56 to move the photosensitive drum 51.
Approach (set) and retreat (reset) the photosensitive surface of a.

In addition, a roller R indicated by a broken line in the drawing
2 is provided, and when the roller R2 sets the mounting base 12a,
Rolling contact with the feed roller R3 for transporting the upper sheet 20a determines the position of the mounting table 12a.

With such a configuration, when the photosensitive drum 51a is taken out of the apparatus, first, when the lever handle is rotated in the direction of arrow D, as shown by a two-dot chain line in FIG.
Is rotated in the direction of arrow F and reset.
11a, remove the photosensitive drum 51a from the opening 90 into the hole 510.
Grab with and pull out. When mounting the photosensitive drum 51a, this is performed in reverse order.

[Problems to be solved by the invention]

According to the above conventional method, when pulling out the photosensitive drum from the apparatus, the mounting table is reset and then the lid plate is removed and the photosensitive drum is pulled out. The shaft is bent by the weight of the photosensitive drum, and the photosensitive surface hits the leading edge of the paper guide and damages the photosensitive surface. When the photosensitive drum is removed from the opening in that state, the photosensitive surface is moved to the leading end of the paper guide during the removal process. Rubbing the surface of the photosensitive drum and causing a larger damage, thereby shortening the life of the photosensitive drum.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing a photosensitive surface from being damaged when a photosensitive drum is taken out of the apparatus.

[Means for solving the problem]

FIG. 1 is a view showing the principle of the present invention, wherein FIG.
(B) is a front view as viewed in the direction of arrow A.

In the figure, 7 is a central axis, 8 is a bearing, 9 is an apparatus frame, 11 is a cover plate, 20 is a printing medium, 51 is an image forming body, 55 is a medium guide, 90 is an opening, and 16 is an image forming body 51. The first end of the medium guide 55 that opposes the image forming surface via the first gap through which the print medium 20 can pass does not hinder the passage of the print medium 20 in the longitudinal direction. It is a spacer formed of a resin material opposed to the small second gap.

Therefore, when taking out the image forming body 51 from the apparatus, the lid 11 is detached from the side of the apparatus frame 9 and the image forming body 51 is taken out from the opening 90.

[Action]

When removing the image forming body 51 from the apparatus, first remove the cover plate 11, the center axis 7 is bent by the weight of the image forming body 51, and the image forming surface has a second gap smaller than the first gap. In this case, the image forming body 51 can be removed from the opening 90 without damaging the image forming surface by the spacer 16 because the medium guide 55 can be prevented from hitting the medium guide 55. can do.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. The same reference numerals indicate the same objects throughout the country.

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

The shaft 7a, bearings 8a to 8c, side frames 9a and 9b, photosensitive drum 51a, and paper guide 55b in FIG. 2 are the same as the central shaft 7, bearing 8, apparatus frame 9, image forming body 51, and medium guide 55 in FIG.
Respectively.

2A is a side view of a main part, FIG. 2B is a front view as viewed in the direction of the arrow A ′, and FIGS. 2C and 2D are enlarged side views of the mounting table.

As shown in FIGS. 2A and 2B, the paper guide 55
Spacers 16a, 16b formed of resin material at both ends of the tip of b
Is provided. The spacers 16a and 16b face the photosensitive surface below the photosensitive drum 51a via a slight gap ε ₂ (for example, 0.25 mm), and the interval between the spacers 16a and 16b is determined by the distance of the conveyed paper 20a.
Is set to be larger than the width. Accordingly, the sheet 20a is guided by the sheet guide 55b, passes between the spacers 16a and 16b, and is sent to the photosensitive surface.

As shown in FIGS. 2C and 2D, the paper guide 55b at the end corresponding to the longitudinal lid plate 11a on the upper surface of the mounting table 12b on which the paper guide 55b and the transfer device 56 are mounted. The projection 17 is provided at a position substantially corresponding to the above.

When the mounting table 12b is rotated by the rotation of the swing lever 14 and the paper guide 55b and the transfer unit 56 approach the photosensitive surface of the photosensitive drum 51a, the tip of the protrusion 17 When the paper guide 55b and the transfer device 56 are retracted from the photosensitive surface, the paper guide 55b and the transfer device 56 are retracted from the photosensitive surface.
As shown in FIG. 3, the photosensitive drum 51a is formed to retreat from between the end face of the photosensitive drum 51a and the cover plate 11a.

With such a configuration, when the photosensitive drum 51a is taken out of the apparatus for maintenance or the like, when the swing lever 14 is retracted by the lever handle, that is, when the lever handle is rotated in the direction of arrow D, 12b is rotated in the direction of arrow F, the tip of the projection 17a is retracted from between the end face of the photosensitive drum 51a and the cover plate 11a, and the paper guide 55b and the transfer device which have approached the photosensitive surface of the photosensitive drum 51a. 56 retreats.

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

At this time, do not accidentally retract the lever handle,
In other words, not to retract the paper guide 55b and the transfer unit 56 from the photosensitive surface, by removing the cover plate 11a, but the shaft 7a is bent by the weight of the photosensitive drum 51a, the spacer than the gap epsilon ₁ of the photosensitive surface paper guide 55a since towards the gap epsilon ₂ of 16b and the photosensitive surface is small, the photosensitive surface without hitting the paper guide 55b, but hits the spacer 16b, being scratched on the photosensitive surface to the spacer 16b is formed of a resin material.

Also, if you try to take out the photosensitive drum 51a as it is,
The end surface of the photosensitive drum 51a engages with the tip of the projection 17 and cannot be taken out. Then, the retracting operation of the lever handle is performed, and the mounting table 12b is rotated to move the protrusion 17 to the photosensitive drum 5.
By retracting from the end face of 1a, the photosensitive drum 51a can be taken out. At this time, the paper guide 55b and the transfer unit 56 are naturally receded from the photosensitive surface, and the photosensitive surface does not rub against the spacers 16a and 16b, and does not scratch.

In this way, when the cover plate 11a is removed without retreating the lever handle, the shaft 7a bends without hitting the paper guide 55b without damaging the photosensitive surface, and the protrusion 17 retracts the lever handle. Since the photosensitive drum 51a cannot be pulled out without performing the operation, and the photosensitive drum 51a is taken out from the opening 90a after performing the retreat operation, the photosensitive surface is not rubbed, and no scratch is generated. The service life can be extended.

FIG. 4 shows a different embodiment. As shown in the figure,
Over the entire length of the width of the leading end of the sheet guide 55c, friction small spacer 16c made of resin material is attached a coefficient, and the paper 20a is a gap epsilon ₁ can pass is provided on the photosensitive surface of the photosensitive drum 51a I have.

Accordingly, the spacer 16c guides the sheet 20a and does not damage the photosensitive surface of the photosensitive drum 51a.

Although not shown, the spacer of the above-described different embodiment is not shown.
16c may be divided into a plurality of portions and attached to a plurality of locations symmetrical from the center of both ends and the front end of the paper guide 51c.

〔The invention's effect〕

As described above, according to the present invention, by providing a spacer at the end of the front end of the medium guide, the image forming body is removed when the image forming body is taken out by removing the lid plate on the side of the apparatus frame. Even if the central axis is deflected by the weight of the body, it is possible to prevent the image forming surface from hitting the spacer and the medium guide, thereby preventing the image forming surface from being damaged,
Further, a mounting table is provided on which a medium guide and a projection engaging with an end surface of the image forming body are mounted, and the medium guide is retracted from the image forming surface by the rotation of the mounting table, and the projection is retracted from the end surface of the image forming body. By making it possible, the projections prevent the image forming body from being taken out unless the medium guide and the projections are retracted. It can be prevented from sticking. Therefore, there is an effect that the life of the image forming body can be extended.

[Brief description of the drawings]

1 is a principle diagram of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is an explanatory diagram of the embodiment, FIG. 4 is a configuration diagram showing a different embodiment, and FIG. FIG. 6 is a configuration diagram showing a conventional example of an electrophotographic printing apparatus showing a conventional example. In the figure, 7 is a central axis, 7a is a shaft, 8 is a bearing, 8a to 8c are bearings, 9 is a device frame, 9a and 9b are side frames, and 11 and
11a is a cover plate, 16 and 16a to 16c are spacers, 17 is a protrusion, 20 is a print medium, 20a is a sheet, 51 is an image forming body, 51a is a photosensitive drum, 55 is a medium guide, 55a is a paper guide, and 90, 90a indicates an opening.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-125755 (JP, A) JP-A-63-189880 (JP, A) JP-A-63-33770 (JP, A) 13559 (JP, U) Japanese Utility Model 4-3460 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 21/00 G03G 15/00

Claims (2)

(57) [Claims] An end of a center shaft is supported by a bearing, and one of the bearings is mounted on an apparatus frame, and the other is removably mounted on an opening provided in the apparatus frame to form one side of the apparatus frame. Developing an electrostatic image formed on the image forming surface of a cylindrical image forming body having an image forming surface on the outer periphery, which is attached to a cover plate that constitutes a unit, and onto a printing medium guided and transported by a medium guide An image forming apparatus for transferring, wherein both ends of a front end of the medium guide opposed to an image forming surface of the image forming body via a first gap through which the print medium can pass do not hinder the passage of the print medium in the longitudinal direction. A spacer formed of a resin material opposed to the image forming surface via a second gap smaller than the first gap. When the image forming body is taken out of the apparatus, the lid plate is attached to the apparatus frame. From the side of the Image forming apparatus characterized by retrieving a more image forming body. 2. A mounting table on which the medium guide and the protruding portion are mounted, one end of which is rotatably supported; and a rotation of the mounting table to move the medium guide toward and away from the image forming surface of the image forming body. A rotation unit for causing the projection to enter at least a part of the front surface of the end surface of the image forming body facing the cover plate when the medium guide approaches the image forming surface of the image forming body; When the guide is retracted, it is formed to retreat from the front surface of the end surface, and only when the protrusion retreats from the front surface of the end surface of the image forming body,
The image forming apparatus according to claim 1, wherein the image forming apparatus has a configuration in which the image forming body can be taken out from the opening of the apparatus frame from which the cover plate has been removed.