JPH07261493A - Image forming device - Google Patents

Abstract

PURPOSE:To provide the transfer belt of a belt module at a prescribed position, with a simple constitution and high accuracy, and moreover, capable of reducing vibration between a photoreceptor and the transfer belt having possibility of causing a banding. CONSTITUTION:In the image forming device provided with plural image forming units 1a, 1b, 1c and 1d, and the belt module 12 equipped with a transfer belt 5 extended over plural rolls 14, held in contact with each photoreceptor of the respective image forming unit 1a, 1b, 1c and 1d, and transporting the transfer material along the respective image forming unit 1a, 1b, 1c and 1d, the belt module 12 is supported movably in the up and down directions with respect to a drawer frame 3 and energized upward by the spring force, and the positioning in the direction of the upward movement of the belt module 12 is performed by butting at the position of an image forming unit 1a on the most upstream side and an image forming unit 1d on the most downstream side.

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 used in an electrophotographic copying machine, a printer or the like, and more specifically, a plurality of image carriers are brought into contact with a sheet conveying belt and conveyed by the sheet conveying belt. The present invention relates to an image forming apparatus configured to transfer a toner image formed on an image carrier to a sheet (transfer material) that is used.

[0002]

2. Description of the Related Art An image forming apparatus of this type is shown in FIG. 1. For example, four photosensitive drums 2a of each of the first to fourth sets of image forming units 1a, 1b, 1c and 1d. , 2b, 2c, 2d, the belt module 4 supported by the drawer frame 3 is abutted,
On the sheet conveyed by the endless transfer belt 5 of the belt module 4, the toner images developed and carried on the photosensitive drums 2a and 2d of the image forming units 1a to 1d are transferred to the transfer charger 6a. , 6b, 6c, 6d are sequentially transferred.

The belt module 4 is vertically rotatable about one end of the belt module 4 as a positioning fulcrum, and a push-up member 7a abutting on a lower side surface of the belt module 4 is handled by a handle 7b. By moving up and down,
This belt module 4 is used for each image forming unit 1a, ...
It comes into contact with and separates from 1d. The drawer frame 3 is guided by the left and right rails 8, 8 and can be pulled out to the front side. The transfer belt 5 is rotatably driven by a drive device provided on the machine body side which is connected by setting the drawer frame 3.

In the above-mentioned conventional image forming apparatus, an abutting member 9 is provided on the upper surface of the belt module 4 in the direction of rotation, and the abutting member 9 is brought into contact with the photosensitive drum housing 10 of one image forming unit 1a to move it in the vertical direction. Is positioned.

Further, at this time, as shown in FIG. 2, the photosensitive drums 2a, 2d are tracked by the tracking rolls 11 provided inside the transfer belt 5 of the belt module 4 to deform the shape of the transfer belt 5. The position of the transfer belt 5 with respect to each of the photosensitive drums 2a to 2d is also ensured.

[0006]

SUMMARY OF THE INVENTION In the above conventional configuration,
The structure for abutting and positioning the photoconductor drum housing 10 is complicated in its structure, and the tolerances of the parts are too large to accumulate, requiring an adjustment action, and the positioning with high precision is difficult.

The transfer belt 5 is a tracking roll 1.
Since the photosensitive drums 1 are in contact with each other at 1, the vibration of each photosensitive drum is transmitted to the transfer belt 5 side,
This caused the banding. further,
When foreign matter adheres to the tracking roll, banding becomes remarkable. Further, there is also a problem that a tracking roll is required for each photoconductor drum in order to guarantee the positions of the plurality of photoconductor drums with respect to the transfer belt.

The present invention has been conceived in view of the above, in which the transfer belt of the belt module is placed in a predetermined position with a simple structure and with high accuracy, and vibration between the photosensitive drum and the transfer belt causes banding. It is an object of the present invention to provide an image forming apparatus capable of reducing the above.

[0009]

In order to achieve the above-mentioned object, an image forming apparatus according to the present invention comprises a plurality of image forming units and a plurality of rolls which are stretched by a plurality of rolls so as to expose the respective image forming units. An image forming apparatus comprising: a belt module having a transfer belt that is in contact with a body and conveys a transfer material along each image forming unit, wherein the belt module is vertically movable in parallel with respect to a drawer frame, and The belt module is supported by being biased upward by the spring, and the belt module is positioned in the upward movement direction by abutting at the positions of the most upstream image forming unit and the most downstream image forming unit. ing.

Further, the positioning of the belt module in the upward movement direction in the image formation is performed by any one of the image forming unit on the most upstream side and any image forming unit other than the image forming units on the most upstream side and the most downstream side. Or one of the other image forming units except the most downstream image forming unit and the most downstream and most upstream image forming units. The configuration is such that the two image forming units are butted against each other.

[0011]

[Operation] The belt module supported by the drawer frame is moved in parallel upward by the biasing force of the spring, and both ends of the belt module in the conveying direction are at the most upstream side and most downstream side of the image forming unit, or at the most upstream side. , The part of the image forming unit other than the most upstream side and the most downstream side, and the most downstream side,
The image forming unit is positioned except for the most downstream side and the most upstream side. As a result, the transfer belt of the belt module is positioned without adjustment on the photoconductor of each image forming unit, and the transfer belt and each photoconductor are positioned without directly transmitting vibrations to each other.

[0012]

EXAMPLE An example of the present invention will be described with reference to FIG. It should be noted that members having the same configurations as those of the conventional technique shown in FIGS. The belt module 12 is similar to that of the above-mentioned conventional art,
Between the front and rear frames 13a and 13b, there is provided a transfer belt 5 wound around a plurality of rolls 14 supported by these and driven by a drive motor (not shown). The belt module 12 is movably supported in the vertical direction within a predetermined range with respect to the drawer frame 3, and is urged upward by the spring member 15 so that the upper ends of the front and rear frames 13a and 13b are not supported. Positioning is carried out by abutting bearings 17 supporting the most upstream and most downstream photosensitive drums 2a and 2d supported by the body frame 16. In this state, the transfer belt 5 of the belt module 12 is attached to each photosensitive drum 2
It is adapted to come into contact with a and 2d at a predetermined contact pressure.

The belt module 12 can be moved downward by the operator against the spring member 15 with respect to the drawer frame 3, and can be held in the downward movement state if necessary. . As this lowering mechanism,
For example, two handles 18 may be provided so as to be spaced apart from each other in the left-right direction from the frame 13a side on the front side of the belt module 12 to the front side of the drawer frame 3, and the operator may hold and move the handles 18 downward. As another configuration, the frames 13a and 13b may be connected to the drawer frame 3 via a parallel link, and the parallel link may be moved up and down by rotating with a handle.

Each of the photoconductor drums 2a, 2d is driven by a photoconductor drive motor 20 via a gear train 19. Further, the belt module 12 is adapted to be connected to a drive source (not shown) while being moved upward.

FIG. 4 shows another embodiment, in which the front and rear frames 13a and 13b of the belt module 12 are brought into contact with bearings 17 and 17 on the body frame 16 side. The two contact positions are the most upstream image forming unit 1a and the most downstream image forming unit 1d.

FIG. 5 shows another different embodiment, in which projecting members 21 and 21 are provided on the front and rear frames 13a and 13b of the belt module 12 so as to project therefrom.
The stoppers 22, 22 fixed to the side are contacted. The contact positions of the both are at two positions on the upstream side and the downstream side of the endless belt 5.

In the structure of each of the above-described embodiments, the belt module 12 in the drawer frame 3 is urged upward by the spring member 15 in the free state of the drawer frame 3.
The upper and lower surfaces of the transfer belt 5 are brought into contact with the respective photoconductor drums 2a to 2d at a predetermined contact pressure in this state by abutting against the 6-side positioning member. At this time, the above-mentioned positioning is performed on the upstream side and the downstream side of the transfer belt 5.
As a result of being carried out in several places, a plurality of photosensitive drums 2
The belt module 12 is positioned in parallel with a, ..., 2d, and the transfer belt 5 is attached to each of the photosensitive drums 2a ,.
It is contacted with d so that the contact pressure is substantially the same.

In the above positioning, the belt module 12 may be horizontally moved up and down and abutted at two positions at the same time for positioning. In addition to the above-described embodiment, the above-mentioned two positions are positioned by any one of the most upstream image forming unit 1a and any other image forming unit other than the most upstream and downstream image forming units. Position with one image forming unit, or the image forming unit on the most downstream side,
The positioning may be performed at positions of any one of the image forming units other than the most downstream side image forming unit and the most upstream side image forming unit.

[0019]

According to the present invention, the belt module 12
Side abutting member and the abutting member on the main body frame 16 side, the positions of the transfer belt 5 with respect to the respective photosensitive drums 2a, 2d are set to high precision only by making the parts precision of the abutting surfaces high.
Without adjustment, the transfer belt 5 and each photoconductor drum 2a,
~ 2d are positioned without directly transmitting vibrations to each other.

Therefore, the transfer belt 5 of the belt module 12 can be placed at a predetermined position with a simple structure and with high accuracy, and vibration between the photosensitive drums 2a to 2d and the transfer belt 5 which causes banding can be reduced. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of a conventional example.

FIG. 2 is a sectional view schematically showing a configuration of a photosensitive drum portion in a conventional example.

FIG. 3 is a front view showing a schematic configuration of an embodiment of the present invention.

FIG. 4 is a sectional view schematically showing a configuration of a main part of an embodiment of the present invention.

FIG. 5 is a sectional view schematically showing a configuration of a main part of another embodiment of the present invention.

[Explanation of symbols]

1a, 1b, 1c, 1d ... Image forming unit, 2a, 2
b, 2c, 2d ... Photosensitive drum, 3 ... Drawer frame, 4, 12 ... Belt module, 5 ... Transfer belt, 6
a, 6b, 6c, 6d ... Transfer charger, 7a ... Push-up member, 7b ... Handle, 8 ... Rail, 9 ... Abutting member,
10 ... Photosensitive drum housing, 11 ... Tracking roll, 13a, 13b ... Frame, 14 ... Roll, 15
... Spring member, 16 ... Main body frame, 17 ... Bearing, 18 ...
Steering wheel, 19 ... gear train, 20 ... drive motor, 2
1 ... Projection member, 22 ... Stopper.

Claims (3)

[Claims] 1. A plurality of image forming units, and a transfer belt which is stretched by a plurality of rolls and is in contact with each photoconductor of each of the image forming units to convey a transfer material along each image forming unit. In an image forming apparatus equipped with a belt module, the belt module is supported so as to be movable in the vertical direction with respect to the drawer frame and is biased upward by a spring, and is positioned in the upward movement direction of the belt module at the maximum. An image forming apparatus characterized in that the upstream image forming unit and the most downstream image forming unit are butted against each other. 2. A plurality of image forming units, and a transfer belt which is stretched by a plurality of rolls and is in contact with each photoconductor of each of the image forming units to convey a transfer material along each image forming unit. In an image forming apparatus equipped with a belt module, the belt module is supported so as to be movable in the vertical direction with respect to the drawer frame and is biased upward by a spring, and is positioned in the upward movement direction of the belt module at the maximum. The image forming unit on the upstream side and the one image forming unit other than the image forming units on the most upstream side and the most downstream side are brought into contact with each other at a position. A characteristic image forming apparatus. 3. A plurality of image forming units, and a transfer belt which is stretched by a plurality of rolls and is in contact with each photoconductor of each of the image forming units to convey a transfer material along each image forming unit. In an image forming apparatus equipped with a belt module, the belt module is supported so as to be movable in the vertical direction with respect to the drawer frame and is biased upward by a spring, and is positioned in the upward movement direction of the belt module at the maximum. The image forming unit on the downstream side and one of the image forming units other than the image forming units on the most downstream side and the most upstream side are butted against each other. A characteristic image forming apparatus.