JPH0512819U - Belt drive - Google Patents

Abstract

(57) [Summary] [Purpose] For a belt drive device capable of automatically detecting and correcting deviation, it is possible to reliably perform deviation correction operation while preventing damage to the belt. [Structure] The transfer belt 4 is laid over the first to third rollers 1, 2, and 3 so as to be able to run. The deviation detecting member 11 is arranged at the shaft end of the third roller 3, and the rotational torque of the deviation detecting member 11 generated by the deviation of the transfer belt 4 coming into contact with the deviation detecting member 11 The axial end portion of the third roller 3 is displaced to generate an eccentric deviation component on the transfer belt 4 to eliminate the initial deviation. The shaft end of the third roller 3 is inserted into and supported by the elongated hole 6a of the roller end supporting member 6.
The extension direction of the elongated hole 6a is set to a direction in which the tension of the transfer belt 4 does not change even if the shaft end of the third roller 3 moves, and the extension of the transfer belt 4 during the deviation correction operation is performed. Prevent the occurrence of elongation.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a belt driving device which is built in a device using an electrophotographic method and uses a transfer belt, a photoconductor belt, or the like.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, for example, in an electrophotographic apparatus, a flat belt having a dielectric layer or a photosensitive layer on its surface is formed on a plurality of rollers arranged substantially in parallel with each other in order to reduce the weight and the size of the apparatus. It is known that the flat belt is used as a transfer belt or a photoconductor belt instead of the transfer drum, the photoconductor drum, or the like by being stretched over.

In the flat belt used for such an application, the base material is often formed of a material having small elongation and high strength such as a plastic film or a metal foil. Therefore, this type of flat belt is not easily elastically deformed. Therefore, if there are dimensional errors in the parts housed in the electrophotographic device, roller mounting errors, belt tension imbalances, and uneven belt circumferences, these may cause deformation of the belt itself. Cannot be absorbed by. As a result, there is a problem that the flat belt deviates in the belt width direction during traveling.

However, since the electrophotographic apparatus is required to have high precision and high resolution in order to form an accurate image, it is necessary to prevent the flat belt from deviating.

As a conventional technique for preventing such a deviation of the flat belt, the deviation of the flat belt as described in JP-A-56-127501 and JP-A-59-205052 is adopted. There is one in which a deviation of the flat belt is forcibly prevented by providing a preventing guide or providing a restricting member as disclosed in Japanese Patent Laid-Open No. 57-60347. Further, as disclosed in Japanese Utility Model Laid-Open No. 58-110609, one roller is used as an eccentricity adjusting roller and a belt position sensor for eccentricity detection is provided. When the deviation of the flat belt is detected by the flat belt, the deviation is corrected by displacing the shaft end of the deviation adjusting roller according to the deviation, or the actual deviation is As shown in Japanese Patent Publication No. 48457, when the flat belt is deviated, the roller is moved in the direction of the rotation axis along with the deviation, and the movement of the roller causes the rotation axis of the roller to move. There is one in which the deviation is corrected by swinging and moving the roller in the opposite direction.

[0006]

[Problems to be solved by the device]

 However, in the structures disclosed in JP-A-56-127501, JP-A-59-205052 and JP-A-57-60347, the deviation of the flat belt is caused by an external factor. Since it is forcibly regulated, the mechanism may not be established depending on the conditions of the combination of the flat belt and the roller. That is, if the deviation force of the flat belt is large, it is necessary to increase the strength of the guide and the regulating 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 of the flat belt so as not to damage it. 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 it is very difficult to form this guide especially in the case of the seamless belt.

Further, in the configurations as disclosed in Japanese Utility Model Laid-Open No. 58-110609 and Japanese Utility Model Laid-Open No. 64-48457, in order to detect and correct the deviation using a complicated mechanism, It is expensive and requires an extra space, leading to an increase in the size of the entire device. Not only that, but because of the complicated mechanism, the number of parts increases 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

In order to solve these problems, the inventors of the present invention are improving the structure of a belt drive device capable of automatically detecting and correcting the deviation. Specifically, one of the plurality of rollers is used as the deviation adjusting roller, and one side of this deviation adjusting roller is rotatable independently of the deviation adjusting roller. A deviation detection member should be provided. Further, the deviation detecting member has an outer diameter which gradually increases as the outer diameter thereof moves away from the deviation adjusting roller, and has a taper-like riding surface on the outer periphery thereof. Further, the flat belt is preliminarily biased toward the deviation detection member. Then, when the flat belt travels, the flat belt rides on the riding surface of the deviation detecting member due to the deviation thereof, and the deviation detecting member rotates due to the riding. Then, this rotational force is converted into a force for moving the shaft end portion of the deviation adjusting roller in a predetermined direction. In this way, we are developing a belt drive device that cancels the deviation by giving a deviation component in the opposite direction to the flat belt.

However, in the belt driving device of this type, as described above, the shaft end portion of the deviation adjusting roller is moved, and therefore, when the moving direction is not properly set. It is possible that the belt tension at only one edge of the flat belt will increase abnormally, causing stretching at the edge of the flat belt, and it may not be possible to perform proper eccentricity elimination operation. Obtaining a configuration in which the moving direction of the end portion is appropriately set leads to a great improvement in the practicality of this type of device.

The present invention has been made in view of these points, and as described above, the deviation is automatically detected by moving one shaft end portion of the deviation adjusting roller. For a belt drive that can be corrected, the movement of this shaft end can be set in the optimum direction to perform a good deviation correction operation, and the practicality of this belt drive can be greatly improved. The purpose is to obtain a configuration that can.

[0011]

[Means for Solving the Problems]

 In order to achieve this object, the present invention is based on moving the flat belt in advance in a predetermined direction while moving the shaft end of the deviation adjusting roller. With respect to the belt driving device that is sequentially corrected, the movement direction of the shaft end of the deviation adjusting roller is restricted to the optimum direction. Specifically, the invention according to claim 1 is such that a flat belt, a plurality of rollers around which the flat belt is stretched, and at least one roller is configured as a deviation adjusting roller, and the deviation. An eccentricity detection roller rotatably supported independently of the eccentricity adjustment roller and a flat belt are provided on one shaft end of the eccentricity adjustment roller. And a biasing means for moving toward the position. When the flat belt is connected to the deviation detecting member and the flat belt is in contact with the deviation detecting member and a rotational torque acts on the deviation detecting member, the rotational movement of the flat belt is caused by the shaft end portion of the deviation adjusting roller in a predetermined direction. And a roller end displacing means for converting the flat belt into a movement in the direction opposite to the movement direction of the offset imparting means. Further, a shaft end portion of the deviation adjusting roller on the side where the deviation detecting member is disposed is rotatably supported by a roller end supporting member to support the roller end portion. A long hole is formed in the member for inserting and supporting the shaft end portion of the deviation adjusting roller. Then, the long hole is defined by a line connecting the shaft centers of the rollers adjacent to the deviation adjusting roller as a long axis, and the deviation adjusting roller is long while being regulated by a flat belt. The structure is such that it extends along the locus of an ellipse drawn when moving around the axis.

According to a second aspect of the present invention, a flat belt, a plurality of rollers around which the flat belt is stretched, and at least one roller is configured as a deviation adjustment roller, and the deviation adjustment. A deviation detecting member rotatably supported independently of the deviation adjusting roller at one shaft end of the operating roller, and the flat belt at the position where the deviation detecting member is disposed. It is equipped with one-sided donation means to move toward. When the flat belt is connected to the deviation detecting member and the flat belt comes into contact with the deviation detecting member and a rotational torque acts on the deviation detecting member, the rotational movement of the flat belt is caused by the shaft end portion of the deviation adjusting roller in a predetermined direction. And a roller end displacing means for moving the flat belt in a direction opposite to the moving direction of the offset imparting means. Further, a shaft end portion of the deviation adjusting roller on the side where the deviation detecting member is arranged is rotatably supported by a roller end portion supporting member to support the roller end portion. A long hole is formed in the member for inserting and supporting the shaft end of the deviation adjusting roller. The inner peripheral surface of the elongated hole, which is in contact with the shaft end of the deviation adjusting roller, is formed in a shape such that the contact area with the shaft end is reduced. ..

According to a third aspect of the present invention, a flat belt, a plurality of rollers around which the flat belt is wound, and at least one roller is configured as a deviation adjustment roller, and the deviation adjustment. A deviation detecting member rotatably supported independently of the deviation adjusting roller at one shaft end of the operating roller, and the flat belt at the position where the deviation detecting member is disposed. It is equipped with one-sided donation means to move toward. A winding member integrally formed with the deviation detecting member is provided with a cord member that is windably connected to the deviation detecting member, and when the flat belt contacts the deviation detecting member and a rotational torque acts, By winding the cord member by the winding unit, the shaft end of the deviation adjusting roller is displaced in a predetermined direction to move the flat belt in the direction opposite to the direction of movement by the offset imparting means. Roller end displacement means. Further, the shaft end portion of the deviation adjusting roller on the side where the deviation detecting member is disposed is supported by a roller end supporting member via a bearing member, and the roller is supported. The end portion support member is formed with a long hole for rollingly supporting the bearing member. Further, the outer diameter of the bearing portion member is formed to be larger than the outer diameter of the winding portion.

[0014]

[Action]

 With the above configuration, the present invention provides the following actions. According to the invention described in claim 1, when the flat belt is biased toward the position where the deviation detecting member is arranged by the action of the deviation imparting means and comes into contact with the deviation detecting member, the deviation detecting member is detected. Rotates due to contact friction with the flat belt. Then, the roller end displacing means displaces the shaft end of the deviation adjusting roller in a predetermined direction as the deviation detecting member rotates. When the shaft end of the deviation adjusting roller is displaced in this manner, the flat belt undergoes an eccentric displacement opposite to the eccentric direction, so that the initial eccentricity is corrected. In other words, the displacement of the shaft end of the deviation adjusting roller is automatically given according to the initial deviation, and the deviation of the flat belt is corrected. Therefore, the flat belt can travel stably, and particularly when the belt driving device is applied to an electrophotographic apparatus, accurate image formation can be performed. Further, the displacement direction of the shaft end of the deviation adjusting roller is regulated by the long hole of the roller end supporting member. In other words, this long hole has a line connecting the shaft centers of the rollers adjacent to the deviation adjusting roller as a long axis, and the deviation adjusting roller is regulated by a flat belt. Since it extends along the track of the ellipse drawn when moving around the long axis, the shaft end of this deviation adjusting roller moves without changing the belt tension of the flat belt. Correct the initial deviation. Therefore, the flat belt is prevented from being stretched, and the life of the flat belt can be extended.

According to the second aspect of the present invention, the inner peripheral surface of the elongated hole formed in the roller end supporting member, which comes into contact with the shaft end of the deviation adjusting roller, is used for the deviation adjusting. Since it is formed in a shape that reduces the contact area with the shaft end of the roller, the coefficient of friction between the elongated hole and the shaft end of the deviation adjusting roller is reduced, During the deviation correcting operation by the roller end displacing means, the shaft end is smoothly moved, and the deviation correcting operation is promptly performed even if the deviation amount of the flat belt is small.

According to a third aspect of the present invention, the shaft end of the deviation adjusting roller is supported by the roller end supporting member via the bearing member, and the roller end supporting member is provided with: Since the long hole that rotatably supports the bearing member is formed, the bearing member moves while rolling in the long hole during the deviation correcting operation. During the correction operation, only a small rolling resistance acts as resistance, and the shaft end moves smoothly. Further, since the outer diameter of the bearing member is formed to be larger than the outer diameter of the winding portion, the bearing is supported with respect to the rotation angle of the deviation detecting member that rotates to wind the cord member. The rotation angle of the member is reduced, and as a result, the rolling resistance of the bearing member is greatly reduced. Therefore, also by this, the displacement of the shaft end portion of the deviation adjusting roller during the deviation correcting operation is smoothly performed.

[0017]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a belt driving device housed in an electrophotographic apparatus according to this example. In FIG. 1, which shows the entire drive device for a three-axis transfer belt, reference numerals 1, 2, and 3 are first, second, and third rollers, respectively. Each of the rollers 1, 2 and 3 is concentric with the shaft members 1a, 2a and 3a except the shaft members 1a, 2a and 3a and the left and right ends of the shaft members 1a, 2a and 3a. It is made up of tubular members 1b, 2b, 3b made of rubber or the like having a slightly larger diameter. As a material for the tubular bodies 1b, 2b, 3b, for example, EPDM cross-linked rubber is adopted. However, the tubular bodies 1b, 2b, 3b may be made of an elastic material such as resin or aluminum.

A transfer belt 4 as a flat belt according to the present invention, which is formed by forming a dielectric layer on the surface of a base material, is movably wound around each of the rollers 1, 2, and 3. Therefore, in the belt driving device, the transfer belt 4 functions as a transfer carrier of the electrophotographic device. Further, as the base material of the transfer belt 4, for example, biaxially stretched polyester is adopted, and the tensile elastic modulus is set to 200 kg / mm ² or more.

In the first roller 1, the shaft member 1a is connected to the drive shaft of the drive motor 5 so that the drive force of the drive motor 5 can be transmitted. That is, the first roller 1 functions as a drive roller.

The second roller 2 is a driven roller, and its axis is arranged parallel to the axis of the first roller 1.

The third roller 3 is an eccentricity adjusting roller referred to in the present invention, and a biasing force is applied in the C direction by springs 3c, 3c arranged at both left and right shaft ends. ing. Then, the tension of the transfer belt 4 is adjusted by this urging force. As shown in FIG. 2, the rotation axis O3 of the third roller 3 is the rotation axis O1 of the first roller 1 and the rotation axis O2 of the second roller 2. The straight line L1 connecting the two lines is arranged on the side closer to the position where the second roller 2 is arranged than the vertical bisector L2, that is, on the left side in FIG.

One of the features of this example is that one shaft end of this third roller 3 (the shaft end on the front side in FIG. 1) is rotated by the roller end support member 6. It is supported freely. As shown in FIG. 3, the roller end portion supporting member 6 is formed with a long hole 6a extending in a predetermined direction described later, and the shaft end portion of the shaft member 3a of the third roller 3 is formed. Is rotatably supported by being inserted into the long hole 6a. Further, the position of the right end face of the elongated hole 6a in FIG. 3 is such that the axis of the third roller 3 is arranged parallel to the axes of the other rollers 1 and 2 (phantom line in FIG. 3). It is slightly extended to the right side position from the shaft end position (in the position indicated by D). That is, as shown in FIG. 3, when the shaft member 3a of the third roller 3 is in contact with the right end surface of the elongated hole 6a, the axis of the third roller 3 is aligned with the first roller. The first and second rollers 2 are inclined with respect to the axes thereof.

Further, the belt tension given by the spring 3c is. The periphery of the third roller 3 acts as indicated by arrows T1 and T2. As described above, the rotation axis O3 of the third roller 3 is the straight line L1 connecting the rotation axis O1 of the first roller 1 and the rotation axis O2 of the second roller 2. Since the second roller 2 is disposed on the side closer to the position where the second roller 2 is disposed than the vertical bisector L2, the resultant force T of each belt tension is slightly lower than the vertical direction. It will be inclined toward the side. Therefore, the x-axis direction component Tx of the resultant force T of the vector tension is directed to the right in FIG. Therefore, assuming that the rolling friction coefficient between the outer peripheral surface of the shaft member 3a and the inner peripheral surface of the elongated hole 6a is μr, and the y-axis direction component of the resultant force T of the vector tension is Ty, Tx−μr Ty> 0. When the relationship of (1) is established and the other force is not acting on the third roller 3, its shaft end is located at the right end position of the elongated hole 6a as shown in FIG. Will be. That is, the third roller 3 is arranged so as to be inclined with respect to the shaft end portions of the first and second rollers 1 and 2, so that the third roller 3 is bridged over the respective rollers 1, 2, and 3. The transfer belt 4 is always wound around in the direction A in FIG. 1 during the running, and is biased in the direction A while running. In this way, the axis of the third roller 3 is arranged to be inclined with respect to the axes of the first roller 1 and the second roller 2, so that the deviation imparting means in the present invention is constructed. Has been done.

Further, as shown in FIG. 4, one of the characteristic members of the present embodiment is located inside the position where the roller end supporting member 6 is provided on the shaft member 3 a of the third roller 3. The deviation detecting member 11 is coaxially with the third roller 3 and is supported by the shaft member 3a so as to be rotatable independently of the third roller 3. A ring member 12 is attached to the outer end of the shaft member 3a.

The deviation detecting member 11 is formed of urethane elastomer or the like. Then, the deviation detecting member 11 is arranged such that its inner end surface is close to the end surface of the cylindrical body 3b of the third roller 3 with a small gap. Further, in the deviation detecting member 11, the outer diameter of the inner end surface portion facing the end surface of the cylindrical body 3b of the third roller 3 is the same as the outer diameter of the cylindrical body 3b of the third roller 3. It has a riding surface 11a which is set to a diameter and which is inclined in a taper shape so that the diameter thereof gradually increases as the distance from the end surface of the cylindrical body 3b increases. When the transfer belt 4 is thereby deviated in the A direction, the deviation causes the transfer belt 4 to ride on the riding surface 11a of the deviation detecting member 11 as shown by a phantom line in FIG. It has become.

Further, the deviation detecting member 11 is integrally formed with a cylindrical portion 11b as a winding portion according to the present invention at a position outside the riding surface 11a. Then, one end of the string member 13 is connected to the cylindrical portion 11b. On the other hand, the other end of the cord member 13 is attached to the fixing member S. That is, when the transfer belt 4 rides on the riding surface 11a of the deviation detecting member 11 due to the deviation of the transfer belt 4 caused by the operation of the bias applying means, and the rotational torque acts on the deviation detecting member 11, the deviation occurs. The cord member 13 is wound around the cylindrical portion 11b of the deviation detecting member 11 by the rotation of the detecting member 11, and the shaft end portion of the third roller 3 in the A direction is moved to the first roller 1. Displacement is made in the direction away from the shaft end, that is, in the direction B in FIG. That is, the third roller 3 is tilted rightward in the belt traveling direction to move the transfer belt 4 in the direction opposite to the A direction in the drawing. This constitutes a roller end displacing means 14 for displacing the shaft end of the third roller 3 in a predetermined direction when a rotational torque acts on the deviation detecting member 11. That is, when the shaft end of the third roller 3 is displaced in the B direction, the transfer belt 4 travels while being wound in the direction opposite to the A direction, so that the initial deviation component (A direction). A deviation component opposite to the (component) is generated, and the shaft end portion of the shaft member 3a is displaced until it cancels out with the initial deviation component. That is, the component in the x direction of the winding tension when the cord member 13 is wound is Tmx, and the sliding friction coefficient between the outer peripheral surface of the shaft member 3a of the third roller 3 and the inner periphery of the elongated hole 6a is calculated. As μs, the relationship of Tmx−μsTy−Tx + μrTy> 0 (2) is established, so that the shaft end of the third roller 3 is displaced in the B direction.

A characteristic feature of the present embodiment is the extending direction of the long hole 6a formed in the roller end supporting member 6. As shown in FIG. 5, the elongated hole 6a has a straight line L1 connecting the respective axial centers O1 and O2 of the first roller 1 and the second roller 2 as a major axis, and the third roller 6a. 3 is formed along an elliptic locus E 1 drawn when moving around the long axis L1 while being regulated by the transfer belt 4, that is, in contact with the back surface of the transfer belt 4. On this locus E, the shaft end of the third roller 3 can be moved without changing the belt tension, and the third roller 3 by the roller end displacing means 14 is moved. When the shaft end of the transfer belt 4 is moved, the shaft end can be moved only on the elliptic locus E, so that the deviation correction operation can be performed without generating abnormal tension at the edge of the transfer belt 4. You can do it.

The operation of the above configuration will be described below. First, when the transfer belt 4 runs, the transfer belt 4 is always moved in the direction A in FIG. 1 by the inclined arrangement of the third roller 3 by the component force Tx of the resultant force T of the belt tensions T1 and T2 in the x-axis direction. A biasing force acts on the transfer belt 4, which causes the transfer belt 4 to move toward the deviation detection member 11 while running, and the deviation of the transfer belt 4 causes the end of the transfer belt 4 to move. When the portion rides on the riding surface 11a of the deviation detecting member 11, as shown in FIG. 6, the deviation detecting member 11 is moved by the frictional force acting between the transfer belt 4 and the riding surface 11a of the deviation detecting member 11. Is rotated with respect to the shaft member 3a, and the cord member 13 is wound by the rotation.

By the winding of the cord member 13, the shaft end portion of the third roller 3 on which the deviation detecting member 11 is arranged is guided by the long hole 6 a of the roller end portion supporting member 6 and B The transfer belt 4 travels while being wound in the direction opposite to the A direction without changing the tension. This limits the deviation of the transfer belt 4 in the A direction. At the same time, since the component force Tx of the resultant force T in the x-axis direction is always acting, the displacement amount of the third roller 3 is regulated by the balance between the force that moves the shaft end and this component force Tx. The position of the end portion of the transfer belt 4 is maintained at a certain fixed position.

Since the transfer belt 4 travels in this way, a large deviation of the transfer belt 4 can be prevented, and the deviation amount of the transfer belt 4 can be suppressed to, for example, ten and several μm. That is, while the transfer belt 4 is biased in one direction in advance, the bias is automatically and sequentially corrected, so that the amount of deviation can be made small and the transfer belt 4 can be stably run. With the electrophotographic apparatus of this example, accurate image formation can be performed.

As described above, according to the configuration of this embodiment, the transfer force is obtained by inclining the axis of the third roller 3 with respect to the axes of the other rollers 1 and 2 by the resultant force T of the belt tension. Since the belt 4 is subjected to the initial deviation and the movement direction of the shaft end portion of the third roller 3 as the deviation correction operation is set to the direction in which the belt tension is not changed. In addition to the stable running of the transfer belt 4 with a simple structure, the life of the transfer belt 4 can be extended, which greatly enhances the practicality of this type of belt driving device. Can be improved.

Second Embodiment Next, a second embodiment according to the invention of claim 2 will be described. This example is a modification of the roller end supporting member 6, and the overall structure of the belt driving device is the same as that of the first embodiment described above, so only the characteristic parts will be described. stop. FIG. 7 shows a vertical cross section of the roller end support member 6 taken along a vertical plane perpendicular to the extension direction of the elongated hole 6a. As described above, the inner peripheral surface of the elongated hole 6a has a mountain shape. Therefore, the contact portion between the inner peripheral surface of the elongated hole 6a and the outer peripheral surface of the shaft member 3a of the third roller 3 becomes a line contact, and the contact area is small, and the friction between them is small. The coefficient (sliding friction coefficient μs in the above-described first embodiment) is reduced. Therefore, during the deviation correction operation by the roller end displacing means 6, the shaft member 3a is smoothly moved because the friction coefficient is small, and the deviation amount of the transfer belt 4 is small. Even in this case, the deviation correction operation can be promptly performed. Further, if both of these 3a and 6 are made of the same material, that is, lubricious plastic (for example, polyacetal), the deviation correcting operation can be performed more smoothly.

Further, as a modified example of the shape of the inner peripheral surface of the elongated hole 6a, a convex portion as shown in FIG. 8 may be formed, or an arc shape may be formed as shown in FIG. Good. (Third Embodiment) Next, a third embodiment of the invention according to claim 3 will be described. Even in this example, only the characteristic part will be described. As shown in FIG. 10, as the support structure of the shaft end portion of the third roller 3 in the present example, the height dimension of the long hole 6a of the roller end portion supporting member 6 is the above-mentioned first and the first. It is made larger than that of the second embodiment, and the shaft end of the shaft member 3a of the third roller 3 is rotatably supported via a bush 15 as a bearing member in the present invention. Further, the bush 15 is rollable in the elongated hole 6a. As a result, when the transfer belt 4 is running, the shaft member 3a is rotating with respect to the bush 15, and the bush 15 is located at the right end portion in the elongated hole 6a as in the case of FIG. 3 shown in the first embodiment. Has been done. Since the bush 15 moves while rolling in the elongated hole 6a during the deviation correcting operation, only the rolling resistance, which is a small resistance, acts during the deviation correcting operation. Therefore, the movement of the shaft end is smoothly performed. Further, in this example, the outer diameter of the bush 15 is set to be larger than the outer diameter of the cylindrical portion 11a of the deviation detecting member 11. In other words, the bush 15 is configured such that the rotation angle of the bush 15 is smaller than the rotation angle of the deviation detection member 11 that rotates to wind up the string member 13. Therefore, the rolling resistance of the bush 15 is significantly increased. Has been reduced to. Therefore, also by this, the shaft end portion of the third roller 3 can be smoothly moved during the deviation correcting operation. Also in the configuration of this example, if the material of the bush 15 and the inner peripheral surface of the elongated hole 6a is made of a lubricating plastic of the same material (for example, ultra-high molecular polyethylene or polyacetal). , It is possible to perform the deviation correction operation more smoothly.

Incidentally, in each of the above-mentioned examples, the driving device for the transfer belt of the electrophotographic apparatus has been described, but the present invention is not limited to this, and the driving device for the photosensitive belt or the ordinary flat belt driving device. Can be similarly applied. Further, as the biasing means, the second roller 2 is arranged to be inclined with respect to the first roller 1, and the biasing force of the springs 3c, 3c for imparting tension to the transfer belt 4 is left and right. The configurations may be different.

[0035]

[Effect of the device]

 As described above, according to the present invention, the following effects are exhibited. According to the invention as set forth in claim 1, a long hole through which the shaft end of the deviation adjusting roller is inserted and supported, and a line connecting the shaft centers of the rollers adjacent to the deviation adjusting roller are connected. Is set as a long axis and the deviation adjusting roller extends along the locus of an ellipse drawn when moving around the long axis while being regulated by a flat belt. Since the shaft end moves without changing the belt tension of the flat belt to correct the initial deviation, the flat belt is prevented from being stretched and its life is extended. As a result, the practicability of the belt drive device can be greatly improved.

According to the second aspect of the invention, the inner peripheral surface of the elongated hole formed in the roller end supporting member is in contact with the shaft end of the deviation adjusting roller. Since the contact area with the shaft end of the deviation adjusting roller is reduced, the friction coefficient between the slot and the shaft end of the deviation adjusting roller is reduced. The shaft end can be smoothly moved during the deviation correction operation by the roller end displacement means, and the deviation correction operation can be performed swiftly and reliably even if the flat belt has a slight deviation. Can be done.

According to the invention of claim 3, the shaft end of the deviation adjusting roller is supported by the roller end supporting member via the bearing member, and the roller end supporting is supported. Since the member has a long hole for supporting the bearing member in a rollable manner, the bearing member will move while rolling in the long hole during the deviation correcting operation. During this deviation correction operation, only a small rolling resistance acts as resistance, and the movement of the shaft end can be performed smoothly. Further, the outer diameter of the bearing member is formed to be larger than the diameter of the winding portion, and the rotation angle of the bearing member is smaller than the rotation angle of the deviation detecting member that rotates to wind the cord member. As a result, the rolling resistance of the bearing member is greatly reduced, which also makes it possible to smoothly move the shaft end portion of the deviation adjusting roller during deviation correction operation. ..

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a belt driving device according to a first embodiment.

FIG. 2 is a view showing the arrangement position of each roller.

FIG. 3 is a diagram showing a force acting on a shaft end portion of a third roller.

FIG. 4 is a cross-sectional view showing the vicinity of the deviation detection member.

FIG. 5 is a diagram for explaining an extension direction of a long hole.

FIG. 6 is a view showing the operation of the roller end portion displacement means.

FIG. 7 is a vertical cross-sectional view showing an inner peripheral surface of a long hole in the second embodiment.

FIG. 8 is a vertical cross-sectional view showing a modified example of the inner peripheral surface of the long hole.

FIG. 9 is a vertical cross-sectional view showing a modified example of the inner peripheral surface of the long hole.

FIG. 10 is a view corresponding to FIG. 4 in the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st roller 2 2nd roller 3 3rd roller (roller for deviation adjustment) 4 Transfer belt (flat belt) 6 Roller end support member 11 Deviation detection member 14 Roll- La end displacement means O1, O2, O3 rotation axis L1 long axis E elliptical locus

Front Page Continuation (72) Inventor Keizo Nonaka 3-2-15 Meiwadori, Hyogo-ku, Kobe-shi, Hyogo Bando Kagaku Co., Ltd.

Claims (3)

[Scope of utility model registration request] 1. A flat belt, and the flat belt is stretched around the flat belt.
A plurality of rollers, at least one of which is configured as a deviation adjusting roller, and one shaft end portion of the deviation adjusting roller is independent of the deviation adjusting roller. And a bias detection member rotatably supported, and a bias imparting means for moving the flat belt toward the position where the bias detection member is disposed. The bias detection member is linked to the bias detection member, When the flat belt comes into contact with the deviation detecting member and a rotational torque acts on the deviation detecting member, the rotational movement of the flat belt is converted into movement in which a shaft end portion of the deviation adjusting roller is displaced in a predetermined direction. A roller end displacing means for moving the roller in a direction opposite to the direction of movement by the offset imparting means, and the shaft on the side of the deviation adjusting roller on which the deviation detecting member is arranged. The end portion is rotatably supported by a roller end supporting member, and the roller end supporting member includes A long hole is formed through which the shaft end of the deviation adjusting roller is inserted and supported, and the long hole connects the shaft centers of the rollers adjacent to the deviation adjusting roller. Is a long axis, and the deviation adjusting roller is extended along a locus of an ellipse drawn when moving about the long axis while being regulated by a flat belt. 2. A flat belt, a plurality of rollers around which the flat belt is stretched, at least one of which is configured as a deviation adjusting roller, and one of the deviation adjusting rollers. A deviation detecting member that is rotatably supported independently of the deviation adjusting roller at an end of the shaft, and a single donation that moves the flat belt toward a position where the deviation detecting member is disposed. And a flat belt is brought into contact with the deviation detection member and a rotational torque acts on the deviation detection member, the rotational movement of the deviation adjustment roller is provided. And a roller end displacing means for converting the flat end of the flat belt into a movement displacing in a predetermined direction and for moving the flat belt in a direction opposite to the moving direction of the offset imparting means. -The shaft end of the roller on the side where the deviation detecting member is disposed is rotatable by the roller end supporting member. A long hole is formed in the roller end supporting member so as to insert and support the shaft end of the deviation adjusting roller, and the deviation adjusting hole in the long hole is used. The belt driving device, wherein the inner peripheral surface of the roller, which is in contact with the shaft end, is formed in a shape such that the contact area with the shaft end is reduced. 3. A flat belt, a plurality of rollers around which the flat belt is stretched, at least one of which is configured as a deviation adjusting roller, and one of the deviation adjusting rollers. A deviation detecting member that is rotatably supported independently of the deviation adjusting roller at an end of the shaft, and a single donation that moves the flat belt toward a position where the deviation detecting member is disposed. And a cord member that is rotatably connected to a winding portion integrally formed with the deviation detecting member, and the flat belt is in contact with the deviation detecting member to apply a rotational torque. Then, the winding portion winds the cord member to displace the shaft end portion of the deviation adjusting roller in a predetermined direction to move the flat belt in a direction opposite to the moving direction by the offset imparting means. A roller end displacing means for moving the roller, wherein the deviation detecting member of the deviation adjusting roller is arranged. Shaft end of the are side is b via a bearing member - is supported in La end support member, the b - La end support member,
A belt driving device, wherein an elongated hole for rotatably supporting the bearing member is formed, and an outer diameter of the bearing member is formed to be larger than an outer diameter of the winding portion.