JPH05201576A - Rotation supporting device for image carrying belt with tensioning mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an image-bearing belt suspension supporting device with a tensioning mechanism, which does not require a control system when tensioning / releasing, can be easily made into a cartridge, and can be manufactured at low cost. An image bearing belt stretched between a plurality of rollers, and a drive unit for driving the image bearing belt,
In an image carrier belt suspension supporting device having a tension applying mechanism for applying tension to the image carrying belt, the tension applying mechanism is mechanically operated by the torque generated in the drive unit only when the drive unit is driven. Then, tension is applied to the image carrying belt, and the applied tension disappears when the drive unit is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for suspending and supporting an image-bearing belt with a tension applying mechanism, and more specifically, for example, a computerized image, an image reading device, or the like, which is an arithmetic signal output or an electrical signalized image. Information or image information obtained by using an electrophotographic method is carried as a toner image on an endless image carrying belt and is reproduced and displayed as it is, or the image visualized on the belt is further transferred onto a transfer paper or the like. The present invention relates to a belt suspension supporting device used in an image forming apparatus such as a copying machine having a function, and more specifically, it relates to a tension applying mechanism for applying a predetermined tension to an image carrying belt.

[0002]

2. Description of the Related Art Generally, an apparatus having an endless image carrier belt as described above has a structure in which the image carrier belt is stretched around a plurality of rollers and rotated. A means for applying an appropriate tension to the image bearing belt is provided in order to prevent the above problems and always rotate on a predetermined orbit.

Conventionally, as a method of applying tension to an image carrying belt, at least one of a plurality of rollers is used as a tension roller, and the tension roller is pressed against the image carrying belt by a spring or the like to form an image. A method of applying tension to a carrier belt is widely used.

By the way, since the image bearing belt has a property of easily bending, in order to drive the orbit while preventing the slack and waviness caused by meandering or vibration of the belt, a relatively strong tension is applied to the image bearing belt. Must be added to the carrier belt.

However, if the above-mentioned strong tension is continuously applied to the belt even when the image bearing belt is stopped, the portion of the image bearing belt which is in contact with the roller is gradually bent by the roller, and The problem shown below occurs.

First of all, when the image carrying belt is bent by the roller for a long time, the bent mark remains on the portion abutting on the roller.

If such a bending mark remains on the belt, the flatness of the image bearing belt cannot be maintained when the image is formed on this portion next time, and the amount of the adhered toner becomes non-uniform. Image quality defects such as density unevenness occur at the bend marks.

Secondly, the image bearing belt is coated with a substance having very delicate characteristics such as an electrophotographic photosensitive member on its surface, and when it is bent by a roller for a long time, Such delicate characteristics change in the portion in contact with the roller, and the characteristics of the portion as the image bearing member deteriorate, so that defective image quality easily occurs.

In order to solve these problems, Japanese Unexamined Patent Publication No.
In JP-A 0-186877, there is known a belt suspension supporting device which controls a roller position by using a solenoid.

[0010]

However, in such an apparatus, since control is performed by a solenoid, in order to put it into practical use, a cable and a control system are required in addition to the solenoid, and the cost is high. It also requires a wiring space for cables and cables.

When the cartridge for the belt photosensitive member is installed, it is difficult to connect the solenoid control cable to the machine body.

Therefore, the present invention provides an image-bearing belt suspension supporting device with a tension applying mechanism, which does not require a control system for applying and releasing tension, can be easily made into a cartridge, and can be manufactured at low cost. Is an issue.

[0013]

SUMMARY OF THE INVENTION The present invention is directed to an image bearing belt stretched between a plurality of rollers, a drive unit for driving the image bearing belt, and a tension for applying tension to the image bearing belt. In an image bearing belt suspension supporting device having an adding mechanism, the tension applying mechanism is mechanically operated by the torque generated in the driving unit only when the driving unit is driven to apply tension to the image carrying belt. The above-mentioned problem is solved by the configuration in which the additional tension disappears when the drive unit is stopped.

A tension gear attached to the shaft of the drive unit and having a torque limiter, a rack and / or lever arm to which an elastic force is applied, and a tension roller are provided. To the tension roller via a rack and / or a lever arm, thereby applying tension to the image bearing belt, and when no torque is applied to the tension gear, the additional tension is applied by the elastic force. It is preferable to cancel it.

Further, in an image carrier belt suspension supporting device having an image carrier belt stretched between a plurality of rollers and a drive unit for driving the image carrier belt, the drive unit comprises a wheel and a plurality of wheels. Even if it is composed of a variable diameter drive roller having a blade, the above problem can be solved.

It is preferable that one or more of the tips of the plurality of blades be connected with a stretchable material.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in the drawings.

FIG. 1 schematically shows a belt photosensitive member to which the belt suspension supporting device of the present invention is applied. This belt photosensitive member is composed of an image bearing belt 1, a driving roller 2, a tension roller 3, and driven rollers 4 and 5.

FIG. 2 shows a tension applying mechanism portion of a belt suspension supporting device according to an embodiment of the present invention. Drive roller 2
When the drive gear 8 receives the rotational force, the drive gear 8 rotates, for example, in the arrow direction. At this time, as the drive roller 2 rotates, the tension gears 9a and 9b also rotate in the same direction to move the racks 10a and 10b.

FIG. 3 shows a side view of the tension applying mechanism portion of FIG. In the figure, the tension gear 9b
Starts rotating in the driving direction, clockwise in the figure, the rack 10b moves to the left side in the figure and pushes the lever arm 11b. As a result, the tension roller 3 moves rightward about the fulcrum 7 of the arm and applies tension to the image carrying belt 1.

A torque limiter is provided between the tension gears 9a and 9b and these shafts, and when a predetermined tension is applied to the image carrying belt 1, the tension gear 9 is released.
The rotation of a and 9b is stopped. And the image bearing belt 1
, A constant tension is maintained while the drive roller 2 is rotating.

When the drive roller 2 stops rotating, the tension gear 9b becomes free, the spring 12 pushes the rack 10b back, and the tension of the image carrying belt 1 is released.

It is a matter of course that the present embodiment is merely an example and does not limit the present invention.
Other than the combination of the gear and the rack, the combination of the pulley and the wire may be used.

FIG. 4 conceptually shows a tension applying mechanism portion of a belt suspension supporting device according to another invention. That is, FIG. 4A shows a state where the drive roller 13 having a variable diameter is stopped, and FIG. 4B shows a state where the diameter is increased as the drive roller rotates. Show.

FIG. 5 shows details of an embodiment of the variable diameter drive roller 13. The variable-diameter driving roller 13 is composed of a wheel 13a and a blade 13b, and a material having a high friction coefficient such as rubber is attached to the surface of the blade 13b in order to prevent slippage with the image carrying belt during rotation. It may be. When the variable-diameter drive roller 13 starts rotating from the stopped state of FIG. 5A, as shown in FIG. 5B, the centrifugal force overcomes the tension force of the belt when the belt is stationary. The blades 13b spread, the roller diameter is increased, tension is applied to the image bearing belt, and the frictional force with the belt realizes suspension without slippage.

FIG. 6 shows a modification of the variable diameter drive roller 13. By connecting at least one of the tips of the plurality of blades 13b with a stretchable film or the like, the outermost peripheral surface of the roller can be brought close to a smooth curved surface, and the rotation of the image bearing belt becomes smoother.

[0027]

In the belt suspension support device according to the first aspect of the invention, the tension applying mechanism is mechanically operated by the torque generated in the drive unit only when the drive unit is driven,
Since tension is applied to the image bearing belt and the tension is eliminated when the drive unit is stopped, a control system is not required when tension is applied or released, and it can be made into a cartridge. It is easy and inexpensive to manufacture.

In the belt suspension support device of the third aspect, since the drive portion is composed of a variable diameter drive roller having a wheel and a plurality of blades, the control is similarly performed when tension is applied or released. It does not require a system, can be easily made into a cartridge, and can be manufactured at low cost.

In the belt suspension supporting device according to the fourth aspect, since at least one of the tips of the plurality of blades is connected with the stretchable material, the effect of the third aspect is provided, and in addition, the image carrying is carried. The rotation of the belt can be made smoother, and thus stability can be given to the belt conveyance.

[Brief description of drawings]

FIG. 1 is a schematic view of a belt photosensitive member to which a belt suspension supporting device of the present invention is applied.

FIG. 2 is a perspective view of a tension applying mechanism portion of the belt suspension supporting device according to the embodiment of the present invention.

3 is a side view of the tension applying mechanism portion of FIG. 2. FIG.

4A and 4B are conceptual diagrams of a tension applying mechanism portion of a belt suspension supporting device according to another aspect of the invention, FIG. 4A showing a stopped state and FIG. 4B showing a rotating state.

FIG. 5 is a schematic view of a variable diameter drive roller, and FIG.
Indicates a stop state, and FIG. 5B shows a rotating state.

FIG. 6 is a schematic view of a variable diameter drive roller according to an improvement,
FIG. 6 (a) shows a stopped state and FIG. 6 (b) shows a rotated state.

[Explanation of symbols]

 2 drive roller 3 tension roller 8 drive gear 9a, 9b tension gear 10a, 10b rack 11a, 11b lever type arm

Claims (4)

[Claims] 1. An image bearing belt having an image bearing belt stretched between a plurality of rollers, a drive unit for driving the image bearing belt, and a tension applying mechanism for applying tension to the image bearing belt. In the suspension supporting device, the tension applying mechanism is mechanically actuated by the torque generated in the drive unit only when the drive unit is being driven to apply tension to the image carrying belt, and the drive unit is stopped. An image-bearing belt suspension supporting device, characterized in that the additional tension is eliminated when the image-bearing belt is suspended. 2. A tension gear attached to a shaft of a drive unit, the tension gear having a torque limiter, a rack and / or a lever arm to which elastic force is applied, and a tension roller. The elastic force is transmitted to a tension roller via a rack and / or a lever arm, thereby applying tension to the image carrying belt, and when no torque is applied to the tension gear, the elastic force causes 2. The image supporting belt suspension supporting device according to claim 1, wherein the additional tension is released. 3. An image carrier belt suspension supporting apparatus having an image carrier belt stretched between a plurality of rollers and a drive unit for driving the image carrier belt, wherein the drive unit comprises a wheel and a plurality of wheels. Image bearing belt suspension support device comprising a variable-diameter drive roller having a blade. 4. The apparatus for suspending and suspending an image carrying belt according to claim 3, wherein one or more positions of the tips of the plurality of blades are connected with a stretchable material.