JP4207269B2 - Belt drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a belt driving device, and more particularly to a belt driving device that stably and safely drives a photosensitive belt and a transfer belt of an electrophotographic apparatus such as a printer or a copying machine.
[0002]
[Prior art]
The conventional belt driving device has a configuration as shown in FIG. 3 in order to prevent the belt from being displaced. The belt 1 is stretched around three of a driving roller 2, a driven roller 3, and a tension roller 4. The driving roller 2 is rotated in the direction of the arrow P by the rotational force transmitted from a driving source (not shown), and the belt 1 travels in the direction of the arrow Q. The tension roller 4 is supported by an arm 6 that rotates about a rotation shaft 60 and applies tension to the belt 1 by a tension spring 7 that is hung on the arm 6.
[0003]
On the other hand, as shown in FIG. 4, a driving roller rotating shaft 2a is provided at the end of the driving roller 2, and a ring 5a that rotates independently of the driving roller 2 is provided on the driving roller rotating shaft 2a. When it is offset, the protrusion 1a and the ring 5a formed on the inner periphery of both ends of the belt 1 come into contact with each other, and the ring 5a is rotated by the frictional force between the protrusion 1a and the ring 5a.
[0004]
Here, the side end of the ring 5a and the tension roller 4 are connected via a link 8 as a transmission means, and the rotational force of the ring 5a is converted into a linear motion via the link 8, as shown in FIG. When the ring 5a is rotated, the arm 6 is rotated in the direction of the arrow R around the rotation point 60, and the tension roller 4 is moved in the direction in which the belt tension is loosened.
[0005]
Accordingly, when the belt 1 is shifted to the left or right, the tension on the side opposite to the offset direction is loosened, and the belt 1 moves in the direction in which the tension is relaxed to correct the offset.
[0006]
[Problems to be solved by the invention]
However, since the conventional belt driving device abruptly corrects the deviation via the transmission means at the moment when the ring formed on the inner periphery near the both ends of the belt contacts the ring, the belt causes a speed fluctuation. easy. Therefore, when the above-mentioned conventional apparatus is used for, for example, a photosensitive belt driving apparatus of an electrophotographic apparatus, an image defect such as an image formed on the belt is disturbed and a printed image is deformed when a speed fluctuation occurs in the belt. Arise.
[0007]
In the case of a color image, a color image is formed by superimposing different colors on the belt or on an intermediate transfer member adjacent to the belt in the electrophotographic apparatus. A desired color cannot be obtained due to the misalignment, resulting in an image defect.
[0008]
Further, since the ring is connected to the tension roller via the transmission means, the ring cannot be driven to rotate. Therefore, when correcting the deviation of the belt, the ring and the protrusion formed on the inner periphery in the vicinity of both ends of the belt slide with friction with a relative speed difference.
[0009]
In general, the protrusions formed on the inner periphery in the vicinity of both ends of the belt are often made of a soft material such as silicon rubber or urethane rubber so that the belt can follow the belt even at a small curvature. However, such materials have poor wear resistance, and wear progresses over time due to frictional sliding with the ring, and wear powder is generated due to wear.
[0010]
This abrasion powder adheres to the back surface of the belt and various rollers such as a driving roller, causing the belt to be deformed out of the plane, causing an obstacle at the time of image transfer, and causing an image defect such as a print defect, resulting in a problem in life. Further, the frictional sliding between the protrusion and the ring increases the driving force of the belt, and excessive stress is applied to the belt, resulting in damage to the belt.
[0011]
The object of the present invention is to gently correct the belt offset, and to prevent belt damage due to excessive stress and wear when correcting the offset of the protrusions formed on the inner circumference in the vicinity of both ends of the belt. To provide an apparatus.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the belt drive device according to the present invention is characterized by the fact that the first ring and the rotation shaft are the same at a position outside the first ring and adjacent to the first ring, so that the belt can rotate freely. The provided second ring is rotated by the rotational force transmitted when the protrusions of the belt come into contact with each other, and the side surface of the second ring and the side surface of the first ring are frictionally slid. The rotational force is configured to be transmitted to the first ring.
[0013]
Specifically, the present invention provides the following apparatus.
[0014]
The present invention includes a belt, a protrusion formed on an inner periphery near both ends of the belt, a driving roller that drives the belt, one or more driven rollers that span the belt, and tension on the belt. A tension roller for imparting a rotation, a first ring having the same rotation axis as the drive roller at both ends of the drive roller shaft, a free rotation at one end, and a free rotation at the other end of the first ring. A belt driving device configured to support the roller so as to freely rotate and transmit the rotational force of the first ring to the tension roller and move the tension roller;
A second ring having the same rotation axis as that of the first ring and free to rotate is provided outside the first ring and adjacent to the first ring. The second ring has a protrusion of the belt. The belt is rotated by the rotational force of the belt transmitted by the contact, and the side surface of the second ring and the side surface of the first ring are frictionally slid, whereby the rotational force of the second ring is A belt drive device is provided that is configured to transmit to a ring.
[0015]
Preferably, between the first ring and the second ring, at least one other ring having the same rotation axis as the first ring and the second ring and free to rotate is provided. The side surfaces of the rings are frictionally slid to each other so that the rotational force of the second ring is transmitted to the first ring.
[0016]
Preferably, the friction coefficient of the contact surface between the protrusion and the second ring is made larger than the friction coefficient of the sliding surface between the rings.
[0017]
Preferably, the friction coefficient of the contact surface between the protrusion and the second ring and the sliding surface between the rings is sequentially reduced in accordance with the transmission order of the rotational force.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a belt driving apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 shows a side view of a belt driving apparatus according to an embodiment of the present invention, and FIG. 2 shows a cross section taken along line AA of FIG.
As shown in FIG. 1, the belt 1 is stretched around three of a driving roller 2, a driven roller 3, and a tension roller 4. The belt 1 is made of a material having as little elongation as possible, such as plastic or thin metal, in order to stabilize traveling. The driving roller 2 receives rotational force from a driving source (not shown) and rotates in the direction of arrow P, and the belt 1 travels in the direction of arrow Q.
[0020]
The surface of the driving roller 2 is covered with rubber, or given a friction coefficient as high as possible by surface treatment or the like, so that the rotational force is efficiently transmitted to the belt 1. The tension roller 4 is supported by an arm 6 that rotates about a rotation shaft 60 and applies tension to the belt 1 by a tension spring 7 that is hung on the arm 6.
[0021]
On the other hand, as shown in FIG. 2, there are driving roller rotating shafts 2 a at both ends of the driving roller 2, and the driving roller rotating shaft 2 a is located outside both ends of the driving roller 2 and independent of the driving roller 2. Thus, a first ring 5a that rotates is provided.
[0022]
Further, a second ring 5b is provided adjacent to the outside of the first ring 5a, rotating independently of the drive roller 2 and the first ring 5a, and frictionally sliding with the first ring 5a.
[0023]
Further, a protrusion 1 a is formed on the inner periphery in the vicinity of both ends of the belt 1. The protrusion 1a is formed by adhering a soft member such as silicon rubber or urethane rubber so that it can follow the belt 1 even at a small curvature.
[0024]
Here, when the belt 1 is shifted to the left or right, the second ring 5b is rotated by the protrusion 1a formed on the inner periphery in the vicinity of both ends of the belt 1 contacting the second ring 5b. Further, when the belt 1 is offset, the second ring 5b and the first ring 5a come into contact with each other, and by sliding friction, the rotational force of the second ring 5b is transmitted to the first ring 5a, and the first ring 5a rotates. .
[0025]
The side end of the first ring 5 a and the tension roller 4 are connected via a link 8 that is a transmission means, and the rotational force of the first ring 5 a is converted into a linear motion via the link 8. As shown in FIG. 1, when the first ring 5a rotates, the arm 6 rotates in the direction of arrow R around the rotation point 60, and the tension roller 4 moves in the direction in which the belt tension is relaxed.
[0026]
Accordingly, when the belt 1 is shifted to the left or right, the belt tension on the side opposite to the offset direction is loosened, and the belt 1 moves in the direction in which the tension is relaxed to correct the offset.
[0027]
As described above, in the present embodiment, the second ring 5b can be rotated by being driven by the belt 1 by providing the second ring 5b to be freely rotatable. Therefore, even if the protrusion 1a formed on the inner periphery near the both ends of the belt and the second ring 5b come into contact with each other when the belt is shifted, the protrusion 1a and the second ring 5b do not slide due to friction because there is no relative speed difference. Even if a soft and poor wear-resistant material such as silicon rubber or urethane rubber is used for the protrusion 1a, the protrusion 1a is not worn. Therefore, it is possible to prevent image defects due to generation of wear powder and damage to the belt 1 due to excessive stress.
[0028]
Furthermore, the rotational force of the second ring 5b is transmitted to the first ring 5a by the frictional sliding between the second ring 5b and the first ring 5a. Therefore, when the belt is offset, the second ring 5b starts rotating at the moment when the protrusion 1a formed on the inner periphery near both ends of the belt and the second ring 5b come into contact with each other, but from the second ring 5b to the first ring 5a. The transmission of the rotational force is achieved by setting the friction coefficient between the protrusion 1a formed on the inner periphery in the vicinity of both ends of the belt 1 and the second ring 5b to be equal to or higher than the friction coefficient between the second ring 5b and the first ring 5a. The frictional sliding between the ring 5b and the first ring 5a can act as a dead zone for rotational force transmission, and the rotational force can be transmitted gradually.
Therefore, the correction can be made gently without correcting the deviation of the belt 1 abruptly, thereby reducing fluctuations in the speed of the belt 1 and generating image defects such as image deformation and color misregistration. It became possible to prevent.
[0029]
When this embodiment is applied to a photosensitive belt driving device of an electrophotographic apparatus, the belt material of the photosensitive belt is a PET film having a thickness of 0.075 mm, and a protrusion of silicon rubber or urethane rubber is provided near both ends of the belt. The part is formed.
[0030]
The first and second rings are made of POM plastic with excellent frictional slidability. Up to 50,000 prints, which is the target life of this device, the speed fluctuations and protrusions of the photoreceptor belt There is no image defect or belt damage due to wear of the belt, and stable belt running can be obtained.
[0031]
Next, another embodiment in which a more stable belt traveling can be obtained will be described.
A third ring is disposed between the first ring and the second ring in FIG. For the first, second and third rings, it is preferable to use a POM plastic as in the above-described embodiment.
[0032]
The first ring is coated with Teflon as a surface treatment in order to further reduce wear on the protrusions at both ends of the belt, thereby reducing the friction coefficient. On the other hand, a felt material is adhered to the contact surface with the first and second rings so that the rotational force can be efficiently transmitted to the third ring to increase the friction coefficient. At this time, when the belt is offset, the transmission order of the rotational force from when the protrusions at both ends of the belt contact the second ring until the belt offset correction is performed, that is, the protrusion at the belt end and the second ring, The friction coefficient is decreased in the order of the second ring, the third ring, the third ring, and the first ring.
[0033]
As a result, the transmission of the rotational force becomes smooth, and the belt offset correction is performed more gradually. Therefore, the belt speed fluctuation is further reduced, and this is particularly effective in the case of a color image that requires superposition of different colors in units of several microns in an electrophotographic apparatus.
[0034]
The third ring provided between the first ring and the second ring may be further replaced with a plurality of rings.
[0035]
As described above, by arranging another ring between the first ring and the second ring, or by adjusting the friction coefficient by the material and surface treatment of these series of rings, Correction ability can be obtained. If the belt offset correction capability is insufficient and the offset does not fit, increase the friction coefficient between the rings. Conversely, if the belt offset correction capability is excessive and the belt will fluctuate in speed, The friction coefficient between them may be reduced.
[0036]
By using the present invention, it is possible to optimize the correction effect on the belt side by simply changing the friction coefficient by changing the ring material, surface treatment, etc., for example, when used in an electrophotographic apparatus, Image defects due to wear on the protrusions on both ends of the photoreceptor belt and damage to the belt can be prevented, and stable belt running can be obtained.
[0037]
【The invention's effect】
According to the present invention, it is possible to gently correct the deviation of the belt, and to prevent the wear of the protrusion formed on the inner periphery in the vicinity of both ends of the belt from being worn or damage to the belt due to excessive stress. Therefore, for example, it is possible to provide a belt driving device capable of obtaining a high-reliability and high-quality printing apparatus.
[Brief description of the drawings]
FIG. 1 is a side view of a belt driving apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a side view of a conventional belt driving device.
FIG. 4 is a diagram showing a driving roller portion of a conventional belt driving device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Belt, 1a ... Projection part, 2 ... Drive roller, 2a ... Drive roller rotating shaft, 3 ... Drive roller, 4 ... Tension roller, 5a ... First ring, 5b ... Second ring, 6 ... Arm, 60 ... Arm Rotation point, 7 ... tension spring, 8 ... link, P ... drive roller rotation direction, Q ... belt running direction, R ... arm rotation direction when correcting belt deviation

Claims (4)

A belt, a protrusion formed on the inner periphery in the vicinity of both ends of the belt, a drive roller for driving the belt, one or more driven rollers that bridge the belt, and a tension that applies tension to the belt A roller, a first ring having the same rotation axis as the driving roller at both ends of the driving roller shaft, and one end freely rotating to the first ring side end and the other end freely rotating to the tension roller A belt driving device comprising: a transmission means for transmitting the rotational force of the first ring to the tension roller and moving the tension roller;
A second ring having the same rotation axis as that of the first ring and free to rotate is provided outside the first ring and adjacent to the first ring. The second ring has a protrusion of the belt. The belt is rotated by the rotational force of the belt transmitted by the contact, and the side surface of the second ring and the side surface of the first ring are frictionally slid, thereby reducing the rotational force of the second ring. A belt drive device configured to transmit to a ring. 2. The at least one other ring according to claim 1, wherein the first ring and the second ring have the same rotation axis as the first ring and the second ring, and are free to rotate. A belt drive device comprising: a belt driving device configured to transmit the rotational force of the second ring to the first ring by frictionally sliding the side surfaces of the series of rings. 3. The belt driving device according to claim 1, wherein a friction coefficient of a contact surface between the protrusion and the second ring is larger than a friction coefficient of a sliding surface between the rings. 3. The friction coefficient of the contact surface between the protrusion and the second ring and the sliding surface between the rings according to claim 1 or 2, wherein the friction coefficient decreases in order according to the transmission order of the rotational force. Belt drive device.

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