JPH0699055B2 - Belt drive - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat belt driving device, and more particularly to a belt driving device such as a photoconductor belt or a transfer / conveying belt of a device using an electrophotographic method. .

(Prior Art) Conventionally, for example, in an electrophotographic apparatus, a photosensitive layer or a dielectric layer is formed on the surface of a plurality of roller members arranged substantially parallel to each other for the purpose of reducing the weight and size of the apparatus. It is known to span a flat belt and use the flat belt as a photoconductor belt or a transfer / transport belt instead of the photoconductor drum.

However, flat belts used for such applications are often formed using a material having small elongation and high strength, such as a plastic film metal foil, as a base material. Therefore, since this type of flat belt is difficult to elastically deform, the dimensional error of each related component, the mounting error of the roller member, the unbalance of the belt tension, and the unevenness of the belt circumference are absorbed by the deformation of the belt itself. As a result, there is a problem that meandering is likely to occur when the flat belt travels.

However, in such an electrophotographic apparatus, high precision and high resolution are required in order to perform accurate image formation, so it is necessary to prevent the meandering of the flat belt.

As a conventional technique for preventing such meandering of the belt, JP-A-56-127501 and JP-A-59-127501.
It is proposed that a belt is provided with a guide for preventing meandering as shown in Japanese Patent No. 205052, or a regulating member is provided as shown in Japanese Patent Laid-Open No. 57-60347 to forcibly prevent meandering of a flat belt. Has been done. Further, there is also a device in which the meandering is corrected by using a complicated mechanism structure as shown in Japanese Utility Model Laid-Open No. 58-110609 and Japanese Utility Model Laid-Open No. 64-48457.

(Problems to be Solved by the Invention) However, JP-A-56-127501 and JP-A-59-20
In the configurations disclosed in Japanese Patent Laid-Open No. 5052 and Japanese Patent Laid-Open No. 57-60347, the flat belt is forcibly received due to an external factor. Therefore, the flat belt and the roller member may be combined with each other depending on the condition of the combination. In some cases, it cannot be established.
That is, the greater the deviation force caused by the meandering of the flat belt,
It is necessary to increase the strength of the guide and the regulation member. Further, it is necessary to increase the widthwise buckling strength of the flat belt itself, and at the same time, to increase the end strength so that the end portion of the flat belt is not damaged. Therefore, the thinner the belt, the more difficult it is to adopt the above method. Further, when the guide is provided on the flat belt, it is necessary to provide the guide with high accuracy, and particularly in the case of the seamless belt, it is very difficult to form the guide.

In addition, in Japanese Utility Model Laid-Open No. 58-110609 and Japanese Utility Model Laid-Open No. 64-48457, an expensive and extra space is required to correct the meandering using a complicated mechanism, and the entire device is required. Not only does it lead to an increase in size, but the number of parts is large due to the complicated mechanism, and the number of failure occurrence factors increases accordingly, so it is hard to say that the reliability of the device is sufficiently secured. It was

SUMMARY OF THE INVENTION An object of the present invention is to provide a belt drive device that can prevent belt meandering at a low cost with a simple mechanism and a small required space without performing complicated processing on a roller member and a flat belt.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, when meandering occurs in the flat belt, the running end of the flat belt displaces the axial end portion of the roller member in a predetermined direction. To generate a meandering component in the opposite direction. Specifically, in the invention according to claim (1), a flat belt, and a plurality of the flat belts, which are hung on each other and rotatably supported by respective shafts, at least one of which is configured as a meandering detection roller member. A book roller member, a meandering detection member rotatably supported on at least one shaft end of the meandering detection roller member independently of the meandering detection roller member, and the meandering detection roller member. And a roller support member for movably supporting the shaft end portion on which the meandering detection member is arranged in a predetermined direction orthogonal to the rotation axis. Also, connected to the meandering detection member,
A roller end displacing means for displacing the shaft end of the meandering detection roller member in a predetermined direction by converting the rotational movement into a linear movement when a flat belt comes into contact with the meandering detection member and a rotational torque acts on the meandering detection member. It is configured to include.

According to a second aspect of the present invention, the roller end displacing means is provided with a flexible winding member, one end of which is connected to the meandering detection member in a windable manner and the other end of which is connected to the fixing member. It was configured like this.

In the invention according to claim (3), a biasing means is provided for biasing the shaft end portion of the meandering detection roller member in a direction opposite to the displacement direction of the roller end portion displacement means.

The invention according to claim (4) is such that the flat belt is moved in a meandering direction toward the position where the meandering detection member is arranged when the meandering detection member is not subjected to rotational torque due to contact with the flat belt. did.

In the invention according to claim (5), the flat belt is made of a film material having a tensile elastic modulus of at least 200 kg / mm ² .

In the invention according to claim (6), the photosensitive layer or the dielectric layer is formed on the surface of the flat belt.

According to a seventh aspect of the present invention, the roller support member has a structure in which the shaft end of the meandering detection roller member is inserted to form an elongated hole extending in the displacement direction of the shaft end.

The invention according to claim (8) is such that, in the belt drive device according to claim (7), at least the inner surface of the elongated hole is made of a lubricious plastic.

(Operation) Next, the operation of the present invention having the above configuration will be described.

According to the invention described in claim (1), when the flat belt is displaced by the meandering and comes into contact with the meandering detection member, the meandering detection member is rotated by contact friction with the flat belt, and the meandering means is caused by the roller end displacing means. The rotational movement of the detection member is converted into a linear movement. As a result, one shaft end of the meandering detection roller member is displaced in a predetermined direction. When the shaft end of the meandering detection roller member is displaced in this way, the meandering displacement in the opposite direction occurs in the flat belt, and the initial meandering is eliminated. As a result, the displacement of the shaft end of the meandering detection roller member corresponding to the initial amount of meandering displacement is automatically given, and the meandering of the flat belt is eliminated and stable traveling is performed.

According to the invention described in claim (2), when the rotation torque is generated in the meandering detection member, the winding member is wound around the meandering detection member, so that the meandering detection roller member can be easily displaced in the predetermined direction. You can

According to the invention of claim (3), the contact area between the flat belt and the meandering detection member decreases during the operation of eliminating the initial meandering, and the rotational torque decreases. When the rotational torque decreases, the displacement amount of the shaft end portion of the meandering detection roller member is reduced by the biasing means that biases the shaft end portion in the opposite direction.

According to the invention as set forth in claim (4), since the flat belt is configured so as to be displaced in the meandering direction toward the arrangement position of the meandering detection member in advance, the meandering detection member and the roller end displacing means are: It is sufficient to dispose only one on the belt meandering direction side, which simplifies the structure.

According to the invention described in claim (5), since the flat belt is formed of a film material having a tensile elastic modulus of 200 kg / mm ² or more and which is not easily elastically deformed, the end portion of the flat belt is damaged. Stable running can be obtained without any.

According to the invention described in claim (6), since the photosensitive layer body or the dielectric layer is formed on the surface of the flat belt, the flat belt is provided as a photosensitive belt or a transfer / conveying belt for electrophotographic direction. And stable image quality is obtained.

According to the invention described in claim (7), when the shaft end portion of the meandering detection roller member is displaced, it moves along the elongated hole of the roller support member, and thus the shaft end portion has a simple structure. The part can be supported movably.

According to the invention as set forth in claim (8), since at least the inner surface of the elongated hole is formed of the lubricating plastic, the shaft end of the meandering detection roller member can be moved smoothly.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a flat belt drive unit housed in an electrophotographic apparatus according to the present invention. In FIG. 1, which shows the entire three-axis photosensitive belt driving device, reference numerals 1, 2, and 3 denote first, second, and third roller members, respectively, and shaft members 1a and 2 respectively.
a, 3a and the elastic members 1b, 2b, 3b formed concentrically with the shaft members 1a, 2a, 3a and having a slightly larger diameter at the portions excluding the left and right ends of the shaft members 1a, 2a, 3a. And consists of. As a material for the elastic body rollers 1b, 2b, 3b, for example, EPDM cross-linked rubber is adopted. However, each of the rollers 1b, 2b, 3b may not be an elastic material such as resin or aluminum.

Further, a photosensitive belt 4 as a flat belt in the present invention, in which a photosensitive layer is formed on the surface of a base material, is movably wound around each of the roller members 1, 2, and 3. The photoconductor belt 4 functions as a photoconductor of the electrophotographic apparatus. As the base material of the photoreceptor belt 4, for example, biaxially stretched polyester is adopted, and the tensile elastic modulus is set to 200 kg / mm ² or more.

The shaft member 1a of the first roller member 1 is linked to the drive shaft of the drive motor 5 so that the driving force of the drive motor 5 can be transmitted, and the first roller member 1 functions as a so-called drive roller.

The second roller member 2 is a so-called driven roller, and its axis is inclined with respect to the axis of the first roller member 1. For example, only the shaft end of the shaft member 2a on the A direction side is slightly moved in the C direction with respect to the horizontal parallel position with the first roller member 1 (for example, 1 m.
m) It is displaced.

The third roller member 3 is a meandering detection roller member according to the present invention, and its axis is arranged substantially parallel to the axis of the first roller member 1. Further, the third roller member 3 is C-shaped by the springs 3c, 3c arranged at the left and right shaft ends thereof.
A biasing force is applied in the direction, and the tension of the photosensitive belt 4 is adjusted by this biasing force.

By arranging the roller members 1, 2, and 3 in this manner, the photosensitive drum 4 that is laid over the roller members 1, 2, and 3 is configured to always meander in the A direction. Has become.

The shaft end of the shaft member 3a of the third roller member 3 is rotatably supported by the lower frame 8a via a bush 7 which is a bearing member, as shown in FIGS. A frame 8a is engaged with an upper frame 8b mounted and fixed to the movable member 6 via a slide bearing 9 so that the frame 8a can approach and separate from the shaft end of the first roller member 1. The roller support member 8 according to the present invention is constituted by 8a, the upper frame 8b and the slide bearing 9. A meandering detection member is located inside the lower frame 8a of the shaft member 3a of the third row member 3
11 is coaxially arranged with the third roller member 3 and is rotatably arranged independently of the third roller member 3, and a ring member 12 is mounted at an outer position.

The meandering detection member 11 has a taper in which the outer diameter of the end on the elastic roller 3b side is set to be equal to or slightly smaller than the outer diameter of the elastic roller 3b, and the diameter increases as the distance from the end surface of the elastic roller 3b increases. When the photosensitive belt 4 has a meandering portion 11a, the photosensitive belt 4 rides on the meandering detection member 11 due to the meandering displacement.

In addition, the meandering detection member 11 is connected to the other end of the cord member 13 as a winding member whose one end is attached and fixed to the fixing member S, and the meandering displacement of the photoconductor belt 4 causes the photoconductor belt 4 to move.
When the meandering detection member 11 rides on and the rotational torque acts on the meandering detection member 11, the cord member 13 is wound around the meandering detection member 11 by the rotation of the meandering detection member 11, and the third
The shaft end of the shaft member 3a of the roller member 3 is attached to the first roller member 1
The shaft member 1a is displaced in the direction away from the shaft member 1a, that is, in the direction of FIG. 1B. This constitutes a roller end displacing means 14 for displacing the shaft end of the shaft member 3a in a predetermined direction when a rotational torque acts on the meandering detection member 11. That is, when the shaft end portion of the shaft member 3a is displaced in the B direction, a meandering component in the direction opposite to the A direction is generated in the photoconductor belt 4 and cancels out with the initial meandering component (A direction component). The shaft end of the shaft member 3a is displaced up to.

Further, as shown in FIG. 4, a spring 15 as a biasing means is connected to the ring member 12 at the shaft end of the shaft member 3a,
The cord member 13 is always biased in a direction opposite to the displacement direction due to the winding operation, and the spring 15 suppresses displacement of the shaft end portion of the shaft member 3a by a predetermined amount or more. . When the meandering component in the reverse direction due to the displacement of the shaft end of the shaft member 3a becomes larger than the initial meandering component, the photosensitive belt 4 starts to meander in the opposite direction, and the amount of riding on the meandering detection member 11 is increased. The meandering detection member
The rotation torque of 11 also decreases, and as a result, the amount of displacement of the shaft end portion of the shaft member 3a is also reduced by the spring 15.

Further, the movement of the meandering detection member 11 to the outside of the roller end portion is restricted by the stopper 16.

With the above configuration, the first and third roller members 1, 3
Due to the inclined arrangement of the second roller member 2 with respect to, a force acts on the photoconductor belt 4 so that it is always displaced in the A direction.

Then, due to the displacement of the photoconductor belt 4,
When the end portion of the meandering rides on the taper portion 11a of the meandering detection member 11, as shown in FIG. 5, the meandering detection member 11 is moved by the frictional force acting between the photosensitive belt 4 and the meandering detection member 11. The cord member 13 is rotated with respect to 3a, and the cord member 13 is wound by the rotation.

Due to the winding of the cord member 13, the shaft end of the shaft member 3a, which is the end of the third roller member 3 on which the meandering detection member 11 is arranged, is displaced, and the displacement causes a further movement of the photosensitive belt 4. The displacement is controlled. At the same time, due to the displacement of the shaft end portion, the spring 15 extends and the spring force also acts. Therefore, the displacement amount of the third roller member 3 is determined by the balance between the winding force of the cord member 13 and the spring force of the spring 15. Is regulated, and the position of the end portion of the photoconductor belt 4 is maintained at a certain fixed position.

Since the photoconductor belt 4 travels in this manner, the meandering of the photoconductor belt 4 is eliminated, and the meandering amount of the photoconductor belt 4 can be suppressed to, for example, ten and several μm.

In the present embodiment, the second roller member 2 is inclined and a component for displacing the photoconductor belt 4 in the A direction is given. However, when the photoconductor belt 4 is not in contact with the meandering detection member 11, The three-roller member 3 may be arranged so as to be inclined so that the photosensitive belt 4 is displaced in the A direction by the spring 15.

In this embodiment, the roller end displacing means 14 has a winding member.
Although a string member is used as 13, a spring 15 can be omitted by using a spring spring instead. Further, as shown in FIG. 6, the outer gear 21a is provided on the outer peripheral surface of the ring member 21 without using the string member 13.
The shaft end may be displaced by meshing with the rack gear 22. Further, as shown in FIG. 7, the friction coefficient of the outer peripheral surface of the ring member 31 can be increased to utilize the frictional action with the friction plate 32. Further, as shown in FIG. 8, a rigid rod 17 connected to a position apart from the center of rotation of the meandering detection member 11 and having the other end connected independently of the third roller member 3 is provided. It may be configured.

Further, forming the tapered portion 11a on the meandering detection member 11
It is desirable to ensure that the torque generated by the rotation of the belt can be transmitted to the meandering detection member 11.
“A” is not always necessary, and a member having the same diameter as the elastic roller 3b may be used without providing the tapered portion 11a.

Further, in the present embodiment, the spring 15 is used as the urging means in the direction opposite to the displacement direction of the roller end displacing means 14, but any spring other than this spring 15 may be used as long as it has the same action.

(Modification) Next, a modification of the present invention will be described. In this example, since the roller support member is different from that of the above-described embodiment, only the characteristic part will be described.

As shown in FIG. 9, the roller support member 8 of this example is
A long hole 18 is formed through which the shaft end of the shaft member 3a of the roller member 3 is inserted. The long hole 18 is extended toward the direction in which the shaft end of the shaft member 3a moves when the cord member 13 is wound up, and when the shaft end of the shaft member 3a moves, the shaft end of the shaft member 3a moves. The end portion is adapted to move inside the elongated hole 18.

Then, in the normal running state in which the photoconductor belt 4 does not meander, as shown in FIG. 10, when the synthetic tension vector of the tension belts T ₁ and T ₂ of the photoconductor belt 4 is T, this synthetic X tension vectors T, Y-direction component becomes T _x, T _y. When the rolling friction coefficient of the inner surface of the shaft member 3a and the elongated hole 18 and _{μ r, T x -μ r T} y> 0 ...... relationship are composed, the shaft member 3a is in FIG. 10 The photosensitive belt 4 is run at the position shown.

On the other hand, meandering occurs in the photoconductor belt 4 and the photoconductor belt 4
When the cord member 13 rides on the meandering detection member 11 and the cord member 13 is wound by the rotation torque of the meandering detection member 11, the component in the X direction of the winding tension is T _mx, and the inside of the shaft member 3a and the long hole 18 is Assuming that the sliding friction coefficient with the side surface is μ _s , the relationship of T _mx −μ _s T _y > T _x −μ _r T _y is established, and the shaft end portion 3a moves to the left in FIG. The meandering of the photoconductor belt 4 is eliminated.

Since the shaft end of the shaft member 3a of the third roller member 3 is inserted into the elongated hole 18 in this way, it is possible to guide the moving direction of the shaft member 3a, and in the case of a slide bearing or the like. The shaft member 3a can be movably supported with a simple structure without using a mechanism.

In addition, it is desirable that the inner surface of the long hole 18 has a small friction coefficient with the shaft member 3a, and oil-free plastics, plastics containing a solid lubricant, and the like, which are oil-free, for ease of production. Bearing material is adopted.

Further, as a modification of the shape of the elongated hole 18, it may be formed by a curved elongated hole 19 which is convex upward as shown in FIG. In addition, depending on the case, a curved elongated hole that is convex downward may be used.

In FIG. 1, the roller end displacing means 14 of the third roller member 3 as the meandering detection roller member may be provided at both ends of the roller. In this case, when the photoconductor belt 4 is not riding on the meandering detection member 11, it is not necessary to preliminarily make the photoconductor belt 4 meander in the arrangement direction of the meandering detection member 11. It is also possible to provide two or more meandering detection roller members 3.

Further, in the above-described embodiment, the example applied to the photosensitive belt driving device of the electrophotographic apparatus is described, but the present invention is not limited to this, and the driving device of the transfer / conveying device or a normal flat belt is used. The same can be applied to the drive device.

(Effects of the Invention) As described above, according to the present invention, the following effects are exhibited.

According to the invention described in claim (1), when the flat belt comes in contact with the meandering detection member due to the meandering displacement and the meandering detection member rotates, the rotational movement of the meandering detection member is converted into a linear movement by the roller end displacement means. Then, by displacing one shaft end of the meandering detection roller member in a predetermined direction and causing meandering displacement in the opposite direction on the flat belt to eliminate the initial meandering, it is possible to respond to the initial meandering. Since the displacement amount of the shaft end of the meandering detection roller member is automatically given, and the meandering of the flat belt is eliminated, stable running can be performed,
Particularly when applied to an electrophotographic apparatus, accurate image formation can be performed.

According to the invention of claim (2), since the roller end displacing means is provided with the flexible winding member, the meandering detection member generates a meandering torque when a rotational torque is generated. The movement operation of the shaft end portion of the detection roller member can be performed.

According to the invention as set forth in claim (3), the urging means for urging the shaft end portion of the meandering detection roller member in a direction opposite to the displacement direction by the roller end portion displacement means is provided,
When the meandering of the flat belt is eliminated, the displacement of the shaft end gradually becomes smaller due to the balance between the biasing force of the biasing means and the rotational torque acting on the meandering detecting member. Does not displace the part.

According to the invention of claim (4), the meandering detection member and the roller end portion displacing means are configured such that the flat belt is displaced in the meandering direction toward the arrangement position of the meandering detection member.
Since only one belt needs to be set on the belt meandering direction side, the structure can be simplified.

According to the invention of claim (5), since the flat belt is formed of a film material having a tensile elastic modulus of 200 kg / mm ² or more and which is not easily elastically deformed, the end portion of the flat belt is not damaged. Stable running can be obtained.

According to the invention of claim (6), since the photosensitive layer or the dielectric layer is formed on the surface of the flat belt, the flat belt is provided as an electrophotographic photosensitive belt or a transfer / conveying belt, and stable printing quality is obtained. can get.

In the invention of claim (7), when the shaft end of the meandering detection roller member is displaced, it moves along the elongated hole of the roller support member, and the shaft end is moved with a simple configuration. It can be supported freely.

According to the invention of claim (8), at least the inner surface of the long hole is formed of the lubricating plastic,
It is possible to smoothly move the shaft end of the meandering detection roller member.

[Brief description of drawings]

1 to 5 show one embodiment of the present invention, FIG. 1 is a schematic perspective view of a belt driving device, FIG. 2 is a vertical sectional front view of the periphery of a meandering detection member, and FIG. 3 is a periphery of the meandering detection member. Is a perspective view seen from the inside, FIG. 4 is a perspective view seen from the outside, and FIG. 5 is a view for explaining the operation of the roller end portion displacement means. 6 to 8 are views corresponding to FIG. 5 showing modified examples of the roller end portion displacement means. FIG. 9 is a front view showing a modified example of the roller supporting member, and FIG. 10 is a view for explaining the tension acting in this modified example. FIG. 11 is a front view showing a modified example of the long hole. 1 …… First roller member 2 …… Second roller member 3 …… Third roller member (roller member for detecting meandering) 4 …… Photosensitive belt (flat belt) 11 …… Meandering detecting member 13 …… String member ( Winding member) 14 …… Roller end displacing means 15 …… Spring (biasing means) S …… Fixing member

Continuation of the front page (56) References JP 59-205052 (JP, A) JP 62-186286 (JP, A) JP 63-1655 (JP, A) JP 57-60347 (JP , A) Actual opening Sho 53-8932 (JP, U) Actual opening Sho 57-70238 (JP, U) Actual opening Sho 58-110609 (JP, U) Actual opening Sho 64-48457 (JP, U) Actual opening Sho 56-34516 (JP, U)

Claims (8)

[Claims] 1. A flat belt, a plurality of roller members, each of which is composed of a driving and a driven roller member, and at least one of which is a meandering detection roller member, around which the flat belt is stretched, and the meandering detection member. A meandering detection member rotatably supported independently of the meandering detection roller member on at least one shaft end of the roller member, and a shaft end on which the meandering detection member of the meandering detection roller member is arranged. The roller support member that supports the part so that it can move in a predetermined direction perpendicular to the axis of rotation, and the meandering detection member are connected to the meandering detection member. A belt driving device comprising: roller end displacing means for displacing the shaft end of the meandering detection roller member in a predetermined direction by converting it into motion. 2. The roller end displacing means is provided with a flexible winding member, one end of which is connected to the meandering detection member in a windable manner, and the other end of which is connected to a fixing member. The belt drive device according to claim (1). 3. A urging means for urging the shaft end of the meandering detection roller member in a direction opposite to the displacement direction of the roller end displacing means. The belt drive device according to item 1) or 2). 4. At least one of the driven roller members comprises:
The shaft is arranged so as to be inclined relative to the drive roller member so that the flat belt meanders toward the position where the meandering detection member is arranged. 1) The belt drive device according to item (2) or (3). 5. The flat belt has a tensile elastic modulus of at least 200 k.
The belt drive device according to claim (1), (2), (3) or (4), characterized in that the belt drive device is made of a film material of g / mm ² or more. 6. The flat belt has a photosensitive layer or a dielectric layer formed on the surface thereof. Claims (1), (2), (3) and ((3) 4) or the belt drive device according to the item (5). 7. The roller support member is formed with an elongated hole which extends through the shaft end of the meandering detection roller member in the displacement direction of the shaft end. The belt drive device according to (1), (2), (3), (4), (5) or (6). 8. The belt drive device according to claim 7, wherein at least the inner surface of the elongated hole is formed of a lubricious plastic.