JP3354203B2 - Belt drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt driving device and, more particularly, to a belt driving device having a mechanism for correcting deflection by displacing a shaft end of a roller when the belt is deflected.

[0002]

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

In such an apparatus, high precision and high resolution are required in order to form an accurate image (character). However, when the flat belt is deviated in the width direction when the flat belt travels, accurate image formation cannot be performed, and the performance is greatly reduced. For this reason, conventionally, various configurations have been proposed as a configuration for suppressing this deviation. For example, as disclosed in Japanese Patent Application Laid-Open No. 56-127501, a flat belt is forcibly prevented from being deflected,
As disclosed in Japanese Utility Model Laid-Open Publication No. 58-110609, the deviation of the flat belt is detected by a belt position sensor, and when the deviation of the flat belt is detected, one roller is driven in accordance with the amount of the deviation. There is one that corrects the deflection by displacing the shaft end.

However, the conventional configuration as described above has a problem in practicality. That is, if the flat belt is forcibly prevented from being deflected, it is necessary to increase the strength of the flat belt so that the flat belt is not damaged, and a thin belt cannot be used.
Also, in the one that detects the deviation by the belt position sensor, the deviation is detected using a complicated mechanism,
The correction requires an expensive and extra space, which leads to an increase in the size of the entire apparatus.

In order to solve these problems, the inventors of the present invention are improving the structure of a belt driving device capable of automatically detecting and correcting deviation. Specifically, one of the plurality of rollers is used as a deviation adjusting roller, and a deviation detecting member that is rotatable independently of the deviation adjusting roller is provided coaxially on one side of the deviation adjusting roller. Let it be. Then, the flat belt is configured to be deflected in advance toward the deviation detecting member, and when the flat belt travels, the flat belt contacts the outer peripheral surface of the deviation detecting member due to the deviation. By this contact, the deviation detecting member rotates, and by converting this rotational force into a force for moving the shaft end of the deviation adjusting roller, a deviation component in a direction opposite to the deviation is given to the flat belt. In addition, a configuration that corrects the deviation has been developed.

[0006]

In order to make the mechanism capable of correcting the deviation of the flat belt more practical, it is necessary to improve the following points. In other words, when such a device is operated for a long period of time, the contact portion of the flat belt in the deflection detecting member is always the same portion, so that the contact portion is worn, thereby causing Due to a change in the contact state between the deviation detection member and the flat belt (a change in the coefficient of friction, etc.), there is a possibility that the deviation correction operation cannot be performed quickly and stably.

For this reason, it is conceivable to replace the deflection detecting member every predetermined period. However, this causes an increase in running cost, and the practicality of this device cannot be ensured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in view of the fact that a belt driving device capable of automatically detecting and correcting deviation is used from the viewpoint of wear of the deviation detecting member. It is an object of the present invention to obtain a configuration that can be improved.

[0009]

In order to achieve this object, a means according to the first aspect of the present invention is to change the arrangement state of the deviation detecting member so that the entire circumference of the deviation detecting member can be changed. The surface was used effectively. Specifically, the invention according to claim 1 provides a flat belt and a plurality of rollers each of which is wound around the flat belt and at least one of which is configured as an eccentricity adjusting roller.
A deflection detecting member rotatably supported on one shaft end of the deflection adjusting roller independently of the deflection adjusting roller; and A biasing means for moving toward the arrangement position of the detecting member, and the flat belt is connected to the deviation detecting member, and the flat belt is deflected by the biasing means. When the flat belt comes into contact with a partial area of the surface and a rotational torque acts on the deviation detecting member, the rotation end of the deviation adjusting roller is rotated in a predetermined direction by the rotation of the deviation detecting member. And a roller end displacement means for moving the flat belt in a direction away from the deviation detecting member. Then, by changing the position of the deviation detecting member with respect to the roller end displacement means, the area of the outer peripheral surface of the deviation detecting member that the flat belt displaced by the offset applying means contacts is variable.
The configuration is such that the linked position of the roller end displacement means in the deviation detecting member can be freely changed.

According to a second aspect of the present invention, in the belt driving device according to the first aspect, the roller end displacement means includes a flexible member which can be wound around a part of the deviation detecting member. The deflection detection member is provided with a plurality of locking holes to which a locking member for locking one end of the flexible member can be attached. By changing the locking hole in which the locking member is mounted, the connecting position of the roller end displacement means in the deviation detecting member is changed.

According to a third aspect of the present invention, in the belt driving device according to the first or second aspect, the outer peripheral surface of the deviation detecting member which is contacted by the flat belt deviated by the offset applying means is formed as a tapered surface. A plurality of inclined areas partitioned in the circumferential direction are formed on the tapered surface. Each of the inclined regions is set such that the taper angles of the tapered surfaces are different from each other.

[0012]

According to the present invention, the following effects can be obtained in the present invention. According to the first aspect of the invention, when the flat belt is deflected by the action of the offset imparting means and comes into contact with the deviation detecting member, the deviation detecting member is rotated by contact friction with the flat belt. The rotational movement of the deflection detecting member is converted by the roller end displacement means into a movement in which the shaft end of the deviation adjusting roller is displaced in a predetermined direction. When the shaft end of the deviation adjusting roller is displaced in this way, the initial deviation is corrected because the flat belt is displaced in a direction opposite to the direction of the deviation. That is, the amount of displacement of the shaft end of the deviation adjusting roller according to the initial deviation is automatically given to correct the deviation of the flat belt. For this reason, the flat belt can run stably, and in particular, when this belt driving device is applied to an electronic printer device or an electrophotographic device, accurate image (character) formation can be performed. A situation in which a change in the contact surface with the flat belt is required, for example, when such an operation is performed for a long time and the deflection detection member is partially worn due to the contact with the flat belt. Then, by changing the connecting position of the roller end displacement means in the deviation detecting member, the area of the outer peripheral surface of the deviation detecting member with which the deviating flat belt comes into contact is changed. The new outer peripheral surface of the detection member comes into contact with the flat belt.

According to the second aspect of the present invention, by changing the locking hole in which the locking member is mounted, the connecting position of the roller end displacement means in the deflection detecting member is changed, and the flat belt which is deflected is changed. The area of the outer peripheral surface of the deviation detecting member which is contacted by the first member is changed, and the new outer peripheral surface of the deviation detecting member comes into contact with the flat belt.

According to the third aspect of the present invention, as described above, not only can the new outer peripheral surface of the deviation detecting member be brought into contact with the flat belt as required, but also the deviation correcting operation can be performed quickly and reliably. In the case where the angle of the taper surface of the deviation detecting member to be performed is selected, the optimum taper angle can be selected only by selecting the locking hole in which the locking member is mounted. There is no need to prepare a large number of deflection detecting members having different angles.

[0015]

【Example】

(First Embodiment) Next, a first embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, a case will be described in which the belt driving device according to the present invention is employed in a small printer.

FIG. 1 shows a longitudinal section of a small printer 2 provided with a belt driving device 1 according to the present embodiment. The small printer 2 is provided with the belt driving device 1 at a central portion in a main body casing 2a. The belt driving device 1 includes first, second, and third three rollers 3, 4, and 5, on which the photosensitive belt 6 travels (arrow A in FIG. 1). See) made possible. The details of the belt driving device 1 will be described later.

The belt drive 1 is housed in a pair of upper and lower unit cases 1a and 1b. And, at a plurality of locations of each unit case 1a, 1b,
An opening is formed to extend over substantially the entire area of the unit cases 1a and 1b in the width direction (the direction perpendicular to the plane of FIG. 1). Then, around the belt driving device 1,
The following devices are arranged at positions facing the openings. That is, at the formation positions of the three openings formed in the lower unit case 1b, a cleaner 7, a charger 8, and an exposure unit 9 are arranged in order from the left side in FIG. Have been. Also,
A developing device 10 is disposed at a position where an opening is formed in a right connecting portion between the upper unit case 1a and the lower unit case 1b so as to face the photosensitive belt 6. Further, a transfer charger 11 is provided at a position where an opening formed in the upper unit case 1a is formed so as to face the photosensitive belt 6.

Further, a paper cassette 12 provided with print paper P is inserted into the right side surface of the main body casing 2a in FIG. A plurality of transport rollers 13, 1 for taking out and transporting the printing paper P in the paper cassette 12 are provided above the belt driving device 1.
3, ... are provided. Further, a fixing device 14 is provided downstream of the transfer charger 11 in the print paper transport direction.
However, further, unloading rollers 15 are disposed downstream of the rollers. Reference numeral 16 in FIG. 1 denotes a control unit including a printed circuit board and transmitting a control signal to each device.

With such a configuration, the present small printer 2
When the photosensitive belt 6 is driven, the photosensitive belt 6 travels in a direction indicated by an arrow A in FIG. 1, and the photosensitive belt 6 is exposed by the charger 8 and the exposure unit 9 based on a control signal transmitted from the control unit 16 in accordance with the travel. An electrostatic latent image of an image (character) to be printed is formed on the surface of the belt 6. Then, the developing device 1
At 0, toner adheres to the electrostatic latent image portion on the surface of the photosensitive belt 6 and a toner image is formed on the surface of the photosensitive belt 6. Simultaneously with this operation, the transport roller 1
3, the printing paper P in the paper cassette 12
Is taken out and conveyed, and at the position where the transfer charger 11 is disposed, the photosensitive belt 6 and the printing paper P come into contact with each other, and the toner image on the surface of the photosensitive belt 6 is transferred onto the printing paper P. Thereafter, the print paper P on which the toner image has been transferred is conveyed to the fixing device 14, where the toner image is fixed, and then carried out by the carry-out roller 15 onto the upper casing 2b of the small printer 2. become. After the operation is completed, the toner remaining on the surface of the photosensitive belt 6 is scraped off by the cleaner 7 and collected, so that the surface of the photosensitive belt 6 is purified. By repeating such an operation, high-speed continuous printing is performed.

Since printing is performed by such an operation, in a situation where the photosensitive belt 6 is deviated, a toner image is formed on the surface of the photosensitive belt 6 and the toner image is formed on the printing paper P. Transfer is not performed well,
Accurate image (character) formation cannot be performed. Further, the belt driving device 1 of the present embodiment is provided with a mechanism for suppressing the deviation of the photosensitive belt 6.
Hereinafter, the belt driving device 1 will be described in detail.

As shown in FIG. 2, the belt driving device 1 of the present embodiment is a three-axis belt driving device. As described above, reference numerals 3, 4, and 5 in FIG. The second and third rollers. Each of the rollers 3, 4, 5 is a shaft member 3 respectively.
a, 4a, 5a, and a cylindrical member made of rubber or the like formed at a slightly larger diameter concentrically with the shaft members 3a, 4a, 5a except for the left and right ends of the shaft members 3a, 4a, 5a. Body 3b, 4
b, 5b. These cylindrical bodies 3b, 4b, 5
As the material b, for example, an EPDM-based crosslinked rubber is employed. However, each of the cylindrical bodies 3b, 4b, 5b may be made of a material other than an elastic material such as resin or aluminum.

A photosensitive belt 6 as a flat belt according to the present invention, in which a photosensitive layer is formed on the surface of a base material, is run around each of the rollers 3, 4, and 5. Therefore, in the present belt driving device 1, as described above, the photosensitive belt 6 functions as a photosensitive transfer carrier of the small printer 2. Further, as the base material of the photosensitive belt 6, for example, biaxially stretched polyester is employed, and the tensile elastic modulus is set to 200 kg / mm ² or more.

The first roller 3 has a shaft member 3a connected to a drive shaft of a drive motor (not shown) so that the drive force of the drive motor can be transmitted. That is, the first roller 3 functions as a driving roller.

The second roller 4 is a driven roller, the axis of which is arranged parallel to the axis of the first roller 3.

The third roller 5 is a roller for adjusting deflection in the present invention, and its axis is also parallel to the axis of the first roller 3 like the second roller 4 in the state shown in FIG. Are located in

As shown in FIG. 3, a pair of tension arms 17, 18 are provided between the left and right shaft ends of the second roller 4 and the third roller 5. Each of the tension arms 17 and 18 is formed of a sliding engineering plastic such as polyacetal resin or nylon resin. Of the pair of tension arms 17, 18, the first tension arm 17 disposed on the right side in FIG. 3 has a slightly larger diameter near the upper end than the shaft member 5a of the third roller 5. Is formed with a circular shaft member insertion hole 17a. The right end of the shaft member 5a of the third roller 5 is inserted into the shaft member insertion hole 17a and is rotatably supported. On the other hand, near the lower end of the first tension arm 17, the shaft member 4a of the second roller 4 is located.
Circular shaft member insertion hole 17 formed slightly larger in diameter than
b is formed. And this shaft member insertion hole 17b
The right end of the shaft member 4a of the second roller 4 is inserted through a bush 17c and is rotatably supported. Since the second roller 4 and the third roller 5 are supported by the first tension arm 17 in this manner, the right axial distance between the second roller 4 and the third roller 5 is fixed at a constant value. It has become so.

On the other hand, the second tension arm 18 disposed on the left side in FIG. 3 has a circular shaft member formed near its lower end portion and slightly larger in diameter than the shaft member 4a of the second roller 4. An insertion hole 18b is formed. The left end of the shaft member 4a of the second roller 4 is inserted into the shaft member insertion hole 18b via a bush 18c and is rotatably supported. Near the upper end of the second tension arm 18, a long hole 18a extending in a predetermined direction is formed. The length of the long hole 18 a is such that the opening dimension in the vertical (short axis) direction is the shaft member 5 of the third roller 5.
a is set slightly larger than the diameter of
The left end of the shaft member 5a of the third roller 5 is inserted into the shaft 8a via a bush 18d and is rotatably supported. That is, the left end of the shaft member 5a of the third roller 5 is supported so as to be movable along the extending direction of the long hole 18a. In this way, each of the tension arms 17, 18 has a shaft member insertion hole 17a, 17b, 1
8b and a long hole 18a are formed.
The shaft ends of the second roller 4 and the third roller 5 are supported by b, 18a, and 18b.

Next, the extending direction of the elongated hole 18a will be described in detail. As shown in FIG. 6, the extending direction of the elongated hole 18a is determined by the respective axes O1, O of the first roller 3 and the second roller 4.
When the third roller 5 is moved around the long axis S while the third roller 5 is regulated by the photosensitive belt 6, that is, while contacting the back surface of the photosensitive belt 6, It is set so as to substantially follow the locus T of the ellipse drawn by the axis O3. Specifically, as shown in FIG.
A straight line U connecting the axes O2 and O3 of the second roller 4 and the third roller 5 to each other and a straight line V connecting the axes O1 and O3 of the first roller 3 and the third roller 5 to each other 90 ° angle
In a three-axis system in which the angle between the straight line S and the straight line U is 50 ° and the angle between the straight line S and the straight line V is 40 °,
The straight line U and the extension direction of the elongated hole 18a, that is, the axis O
3 is set so that the angle θ formed with the straight line W passing through 3 is 42.5 °. The value of the angle θ is 37.5 °
It can be set arbitrarily between 47.5 °.

The position and length of the slot 18a are determined by the third roller 5 and the first roller 3 and the second roller 4.
In the state where the shaft member 5a of the third roller 5 is parallel to the bush 18d and the both end surfaces in the longitudinal direction of the long hole 18a, as shown in FIG. The gaps X and Y are set to be formed. Specifically, in this example, the position and length of the long hole 18a are set such that a gap of 1.5 mm is formed on the right side X and 2.0 mm on the left side Y of the bush 18d in FIG.

On the other hand, as shown in FIG. 2, a tension spring 1 is provided on the right side surface of the first tension arm 17 and the second tension arm 18 at the position where the third roller 5 is supported.
9 are attached. This tension spring 19
Are the axes O1, O3 of the first roller 3 and the third roller 5, respectively.
One end thereof is abutted on a spring supporting piece 1c extending from the upper unit case 1a, and the other end thereof is connected to a straight line (a straight line V in FIG. 6). It is formed on the side surface and is locked by the spring locking projection 18e.
It is contracted in between. Accordingly, the tension spring 19 applies an urging force to each of the tension arms 17 and 18 in a direction indicated by an arrow B in FIG. This urging force is applied to each of the tension arms 17 and 18.
Works around the axis O2 of the second roller 4 in the counterclockwise direction in FIG. 2, that is, the urging force moves the axis of the third roller 5 away from the first roller 3. Therefore, a predetermined belt tension is applied to the photosensitive belt 6 by the urging force. The tension springs 19 are set so that the right and left urging forces are different. That is, the urging force of the tension spring 19 attached to the first tension arm 17
The force is set to be larger than the urging force of the tension spring 19 attached to the tension arm 18. Thus, the belt tension on the right side in FIG. 3 is configured to be greater than the belt tension on the left side. The photosensitive belt 6 is configured to be displaced. This constitutes the offset imparting means according to the present invention.

Next, a mechanism for suppressing the deviation of the photosensitive belt 6 will be described. This mechanism is incorporated into the second tension arm 18 and is unitized. First, the second tension arm 18 will be described. This second tension arm 18 is shown in FIGS.
8 and 9, the long hole 18 supporting the left end of the shaft member 5 a of the third roller 5 is provided at the upper end in FIGS. 8 and 9.
The shaft member insertion hole 18b for supporting the left end of the shaft member 4a of the second roller 4 is formed at the lower end of the shaft member insertion hole 18b. A shaft insertion hole 20 is formed from the long hole 18a to extend diagonally to the lower left in FIG. 8 and open to one end face 18f of the second tension arm 18. The extension direction of the shaft insertion hole 20 coincides with the extension direction of the long axis of the long hole 18a. In addition, a screw hole 21 extending in the extension direction of the shaft insertion hole 20 is formed at a position close to the shaft insertion hole 20. Further, the shaft insertion hole 2 and the screw hole 21 are opened at the end face 18f.
A groove 22 is formed over the opening area of the O and the screw hole 21. As shown in FIG. 10, a locking pin 23 is provided upright on an inner end face 18g of the second tension arm 18 facing the position where the rollers 3, 4, and 5 are arranged. The locking pin 23 extends in a direction perpendicular to the inner end face 18g of the second tension arm 18, and has a large diameter portion 23a near the distal end.
Are formed, and the tip is formed in a conical shape.

As shown in FIGS. 2 and 10, a back tension shaft 24 is inserted into the shaft insertion hole 20 of the second tension arm 18. The tip of the back tension shaft 24 is formed in a conical shape. The tip of the back tension shaft 24 contacts the outer peripheral surface of the shaft member 5a of the third roller 5 via the bush 18d when the tip faces the long hole 18a. It has become. A large diameter portion 24a is formed at an intermediate portion of the back tension shaft 24 in its extension direction. A back tension spring 25 is inserted into the shaft insertion hole 20 from the back side of the back tension shaft 24, and the back tension spring 25 abuts on the back surface of the large diameter portion 24a of the back tension shaft 24. It has become. Further, from the back side of the back tension spring 25, a stopper plate 26 is fitted into the groove 22. This stop plate 2
6, an opening 26a is formed at a position corresponding to the screw hole 21.
A set screw 27 is screwed to 1. As a result, the back tension spring 25 is contracted between the large diameter portion 24a of the back tension shaft 24 and the stopper plate 26, and the back tension spring 25 is biased by the back tension spring 25. The tip of 24 is pressing the shaft member 5a of the third roller 5 in the direction of arrow D in FIG.

As shown in FIGS. 3, 11, and 12, the second roller at the left end of the shaft of the third roller 5 is provided.
An eccentricity detecting member 28 is provided inside the tension arm 18.
Are arranged. The deviation detecting member 28 has an insertion hole 28a having a diameter substantially the same as that of the shaft member 5a of the third roller 5 at the center thereof.
The shaft member 5a of the third roller 5 is inserted through the insertion hole 28a, so that the third roller 5 rotates coaxially and independently of the third roller 5. It is supported by the shaft member 5a so as to be free. The deviation detecting member 28 is formed of a urethane elastomer or the like which has a high friction coefficient with the belt material of the photosensitive belt 6 and has excellent wear resistance. The deviation detecting member 28 has its inner end face disposed close to the end face of the cylindrical body 5b of the third roller 5 with a small gap. A thin cylindrical contact ring 5c is embedded in the end face of the cylindrical body 5b facing the inner end face of the deviation detecting member 28, and the end face of the contact ring 5c is the inner end face of the deviation detecting member 28. , The direct contact between the deviation detecting member 28 and the cylindrical body 5b of the third roller 5 is avoided, the friction coefficient between the two is reduced, and the deviation detecting member 28 The position is regulated. Further, the deviation detecting member 28 is connected to the third roller 5.
The outer diameter of the portion facing the end face of the cylindrical body 5b is set to the same diameter as the outer diameter of the third roller 5, and is tapered so that the diameter gradually increases as the distance from the end face of the cylindrical body 5b increases. According to the third aspect of the present invention, there is provided a riding surface 28b as a tapered surface. As a result, when the photosensitive belt 6 is displaced in the direction of arrow C in FIG. 3, the deviation causes the edge of the photosensitive belt 6 to ride on the riding surface 28 b of the displacement detecting member 28. (See FIG. 3). A boss 28c is formed on the outer end surface of the deviation detecting member 28. This boss 28
c has an outer end face opposed to an inner end face of the bush 18d.

As a characteristic feature of this embodiment, as shown in FIGS. 4 and 5, an end face of the deflection detecting member 28 facing the second tension arm 18 is provided with:
Bottomed locking holes 31a, 31b, 31c into which locking pins 29 described later can be screwed at a plurality of positions (three positions) having a predetermined angle interval (in this example, an angle interval of 120 °) are third holes. The roller 5 extends along the extension direction of the axis of the roller 5. A locking pin 29 as a locking member according to the second aspect of the present invention is screwed into one of the plurality of locking holes 31a, 31b, 31c (see FIGS. 4 and 5). Lock hole 31
a), and the locking pin 29 is connected to the second tension arm 1 in the deviation detecting member 28.
8 stands perpendicularly to the end face. That is, at the base end of the locking pin 29, the locking hole 31a,
A screw portion 29a capable of being screwed is formed on each of the plurality of locking holes 31a, 3c.
It is adapted to be screwed to one of 1b and 31c. A notch is formed in the head of the locking pin 29, and a screwdriver is applied to the notch to rotate the locking pin 29 so that the locking pin 29 is detachable from the deviation detecting member 28. .

Then, as shown in FIG.
The locking pin 2 provided on the tension arm 18
A deviation detection belt 30 is stretched between the rotation detection member 3 and a locking pin 29 provided on the deviation detection member 28. The deflection detecting belt 30 is a flexible member according to the second aspect of the present invention, and is formed of a flexible film-like band, and both ends of the belt are wound to form hook portions 30a and 30b. In a state where the hook portions 30a and 30b are locked by the locking pins 23 and 29, a part of the deviation detection belt 30 is used as the boss portion 28c of the deviation detection member 28.
Is wrapped around.

With such a configuration, the photosensitive belt 6
When the photosensitive belt 6 rides on the riding surface 28b of the deviation detecting member 28 due to the deviation (the direction of the arrow C in FIG. 3) accompanying the traveling of the deviation detecting member 28, when the rotational torque acts on the deviation detecting member 28, the deviation detecting member 28 With the rotation of, the deviation detection belt 30 is wound around the boss portion 28c of the deviation detection member 28, and the left shaft end of the third roller 5 is moved along the long hole 18a, The roller 3 is displaced in a direction away from the shaft end of the roller 3, that is, in a direction indicated by an arrow E in FIG. That is, the third roller 5 is tilted rightward in the belt traveling direction A, and the photosensitive belt 6 is moved to the third roller 5.
The photosensitive belt 6 is configured to be moved in the direction of arrow F opposite to the direction of arrow C in FIG. Thus, when a rotational torque acts on the deviation detecting member 28, the third
Roller end displacement means for displacing the shaft end of the roller 5 in a predetermined direction is configured. That is, when the shaft end on the left side of the third roller 5 is displaced in the E direction, a deviation component opposite to the initial deviation component (C direction component) is generated, and cancels with the initial deviation component. The shaft end of the third roller 5 is displaced up to this point.

As described above, since the biasing force of the back tension spring 25 is applied to the shaft member 5a of the third roller 5 via the back tension shaft 24, the deviation of the photosensitive belt 6 is detected. When the riding operation on the member 28 is canceled, the left end of the shaft member 5a of the third roller 5 is returned to a predetermined position (the position shown in FIG. 2) by the urging force of the back tension spring 25. Has become. With such a configuration, when the component in the reverse direction due to the displacement of the shaft end of the third roller 5 becomes larger than the initial component, the photosensitive belt 6 starts to deflect in the reverse direction, and the deviation detecting member 28 Of the third roller 5 due to the back tension spring 25, the amount of displacement of the shaft end of the third roller 5 is also reduced. ing.

Next, the belt driving device 1 having the above configuration
The operation of will be described. First, when the photosensitive belt 6 travels, the photosensitive belt 6 always shifts in the direction C in FIG. 1 because the left and right belt tensions are different as described above. That is, the photosensitive belt 6 is deflected toward the deflection detecting member 28 while traveling.

The end of the photosensitive belt 6 is moved by the deflection of the photosensitive belt 6 so that the end of the photosensitive belt 6 rides on the running surface 28b
The deflection detection member 28 is rotated with respect to the shaft member 5a by the frictional force acting between the photosensitive belt 6 and the riding surface 28b of the deflection detection member 28, and the rotation detects the deviation detection belt. 30 will be wound up.

By winding the deviation detection belt 30,
The shaft end of the third roller 5 on which the deviation detecting member 28 is disposed is displaced in the E direction. The direction of displacement of the shaft end is approximated by a straight line substantially along the above-described elliptical locus T, whereby the shaft end of the third roller 5 can be changed without changing the belt tension. Will be displaced. This displacement causes the photosensitive belt 4 to travel while being wound in the direction opposite to the direction C, thereby limiting the deviation of the photosensitive belt 4 in the direction C. At the same time, the back tension shaft 24 is moved in the direction of coming out of the long hole 18a due to the displacement of the shaft end portion, whereby the back tension spring 25 is pressed and contracted, and the spring reaction force is also increased. The amount of displacement of the third roller 5 is regulated by the balance between the winding force and the spring reaction force of the back tension spring 25, and the position of the end of the photosensitive belt 6 is maintained at a certain fixed position.

Since the running of the photosensitive belt 6 is performed in this manner, large deviation of the photosensitive belt 6 is prevented, and for example, the amount of deviation of the photosensitive belt 6 can be suppressed to about 10 μm. That is, while the photoconductive belt 6 is previously deflected in one direction and the deflection is automatically corrected, the amount of deflection can be reduced to a small amount, and the photosensitive belt 6 can run stably. In the small printer 2 as in this example, accurate image (character) printing can be performed.

When such an operation is performed for a long period of time, the photosensitive belt 6 always comes into contact with the riding surface 28b of the deviation detecting member 28 at the same portion. Contact surface 2
8b is worn only in part. If such abrasion occurs, a stable deflection correcting operation cannot be performed. Then, in this example, in such a situation, the locking pin 29 is
Is removed from the screwed locking hole 31a and screwed into the other locking hole 31b. When the position of the locking pin 29 is changed in this manner, the posture of the disposition detecting member 28 in the disposition state is also changed. That is, the locking pin 2
With the movement of the position 9 by the angle interval 120 °, the posture of the disposition detecting member 28 in the disposition state is also turned by 120 °. Therefore, the contact portion of the photosensitive belt 6 that is displaced is changed, and the riding surface 28 is changed.
The area of b, where no wear occurs, comes into contact with the photosensitive belt 6. For this reason, it is possible to perform the same favorable deviation correction operation as in the initial operation without replacing the deviation detection member 28, thereby reducing running costs and improving the belt driving device 1 Of the present invention can be improved.

In this manner, the position of the locking pin 29 is changed to change the position of the photosensitive belt 6 in the deviation detecting member 28.
If the contact portion with the photosensitive belt 6 is worn again after the contact portion is changed, another locking hole 31c is formed.
Then, the locking pin 29 is screwed to the photosensitive belt 6 so that an area of the riding surface 28b where the wear has not occurred is brought into contact with the photosensitive belt 6 again. As described above, according to the configuration of the present embodiment, the contact portion of the riding-up surface 28b of the deviation detecting member 28 with the photosensitive belt 6 can be changed in three places, so that the locking pin 29 is fixed at one place. As a result, the life of the deviation detecting member 28 can be extended three times as compared with the above-described structure, and the frequency of replacement of the deviation detecting member 28 can be reduced to improve the practicality of the present apparatus. Can be.

(Second Embodiment) Next, a second embodiment of the present invention will be described in detail with reference to the drawings. Further, the basic structure of the belt driving device of the present embodiment is substantially the same as that of the above-described first embodiment, and therefore, in this embodiment, only the differences from the first embodiment will be described.

FIGS. 13 and 14 show the deviation detecting member 2 as a characteristic feature of the belt driving device according to this embodiment.
8 is shown. As can be seen from this figure, the deviation detecting member 28 of this example has three regions I, II, and III whose outer peripheral surfaces have an angular interval of about 110 ° and a connection that smoothly connects the regions. Sections IV, V, and VI are provided. And
Ride surface 28b in each divided area I, II, III
Are set to different values. Specifically, in region I in FIG. 13, the taper angle is set to a small value of about 1 °, and in region II, the taper angle is 3 °.
°, and in region III, the taper angle is 6 °.
It is set to be large. The positions of the locking holes 31a, 31b, 31c for locking the locking pin 29 are as follows.
Like the first embodiment described above, they are arranged at equal angular intervals (120 °), and in particular, are positioned so as to face the connecting parts IV, V, VI connecting the respective regions I, II, III. Is formed.

With such a configuration, for example, FIG.
By disposing the locking pin 29 at the position shown in FIG. 3, the area of the riding surface 28b of the deviation detecting member 28
III is in contact with the edge of the photosensitive belt 6, the photosensitive belt 6 is brought into contact with a region III where the taper angle is set to be as large as about 6 °, and the above-described deflection correcting operation can be performed. Become.

For example, if the locking pin 29 is disposed at a position as shown in FIG.
In the riding surface 28b of No. 8, the region I abuts on the edge portion of the photosensitive belt 6 and the photosensitive belt 6 is brought into contact with the region where the taper angle is set to be as small as about 1 ° to perform the above-described deflection correcting operation. Can be done.

Therefore, according to the structure of this embodiment, when selecting the taper angle for performing the deviation correcting operation most quickly and surely, the locking hole 31a into which the locking pin 29 is screwed. , 31b, and 31c, the optimum taper angle can be selected. A number of deviation detecting members having different taper angles are prepared, and they are sequentially assembled to the apparatus to select the optimum taper angle. It is not necessary to perform such complicated work.

Further, with the operation for a long time, the photosensitive belt 6
Even when the taper angle of the riding surface 28b for performing the optimal deflection correcting operation is changed, the locking holes 31a and 31 into which the locking pin 29 is screwed.
Only by selecting b and 31c, the taper angle at which the photosensitive belt 6 is in contact can be selected, and the maintenance performance can be improved.

In this embodiment, the belt-like displacement detection belt 30 is employed as a member for converting the rotational force of the displacement detection member 28 to the shaft end. However, the present invention is not limited to this. As long as the member 28 can be wound up, a string or the like may be adopted. In the above-described embodiment, the driving device for the photosensitive belt 6 of the small printer 2 has been described. However, the present invention is not limited to this, and is similarly applied to a driving device for a transfer belt or a normal flat belt driving device. can do. Further, the bias applying means is not limited to the one in which the right and left belt tensions are made different from each other, and may be configured so that one of the rollers is inclined and the initial deviation is performed. In each of the above-described embodiments, the locking holes 31a, 31b, into which the locking pins 29 are screwed, are provided.
Although the drilling positions of 31c are set at three positions, the present invention is not limited to this, and drilling may be performed at two positions or at four or more positions.

[0051]

As described above, according to the present invention,
The following effects are exhibited. First, claim 1
According to the invention described above, by changing the position of the deviation detecting member with respect to the roller end displacement means, the area of the outer peripheral surface of the deviation detecting member with which the flat belt displaced by the offset imparting means comes into contact is variable. As described above, since the connecting position of the roller end portion displacement means in the deviation detecting member is made freely changeable, when the operation is performed for a long period of time and the deviation detecting member is partially worn. For example, the area of the outer peripheral surface of the deviation detecting member with which the deviating flat belt contacts can be changed,
As a result, the new surface of the deviation detecting member comes into contact with the flat belt, so that the same favorable deviation correcting operation as in the initial operation can be performed without replacing the deviation detecting member. This can extend the life of the deviation detecting member, reduce the frequency of replacement of the deviation detecting member, reduce running costs, and improve the practicality of the present device. be able to.

According to the second aspect of the present invention, the roller end displacement means is provided with a flexible member that can be wound around a part of the deviation detecting member, while the deviation detecting member is provided with the flexible member. A plurality of locking holes into which a locking member to which one end of the sex member is locked can be mounted, and by changing the locking hole in which the locking member is mounted, a roller end portion in the deviation detecting member is provided. Because the connecting position of the displacement means is changed, the area of the outer peripheral surface of the deviation detecting member that the flat belt that is displaced contacts by a simple operation such as changing the mounting position of the locking member to the locking hole is changed. can do.

According to the third aspect of the present invention, the outer peripheral surface of the deviation detecting member contacted by the flat belt displaced by the offset imparting means is formed with a tapered surface, and the tapered surface is partitioned in the circumferential direction. A plurality of inclined regions are formed, and the respective inclined regions are set so that the taper angles of the tapered surfaces are different from each other. In order to select the taper angle for performing the quickest and most reliable taper angle selection, the optimum taper angle can be selected only by selecting the locking hole in which the locking member is mounted. There is no need to prepare a large number of deviation detecting members having different diameters and to sequentially assemble them into an apparatus to select an optimum taper angle, thereby improving the workability of the taper angle selecting operation. This Can. In addition, even when the environmental conditions are different and the frictional resistance changes, the selection can be adjusted.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a small printer.

FIG. 2 is a side view showing a part of the belt driving device in a cross section.

FIG. 3 is a partially broken front view showing a connection state of a second roller and a third roller by a tension arm.

FIG. 4 is a side view of the deflection detecting member according to the first embodiment.

FIG. 5 is a cross-sectional view at a position corresponding to the line VV in FIG. 4;

FIG. 6 is a diagram for explaining an extending direction of a long hole.

FIG. 7 is a longitudinal sectional view around a long hole.

FIG. 8 is a vertical sectional side view of a second tension arm.

FIG. 9 is a vertical sectional front view of a second tension arm.

FIG. 10 is an exploded perspective view of a second tension arm and its peripheral members.

FIG. 11 is an exploded perspective view around a roller end displacement unit.

FIG. 12 is a perspective view showing an assembled state of a second roller and a third roller to a unit case.

FIG. 13 is a diagram corresponding to FIG. 4 in a second embodiment.

FIG. 14 is a diagram corresponding to FIG. 5 in a second embodiment.

FIG. 15 shows a state in which the position of the locking pin is changed.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt drive device 3 1st roller 4 2nd roller 5 3rd roller (roller for deviation control) 6 Photosensitive belt (flat belt) 28 Deflection detection member 28b Riding surface (taper surface) 29 Locking pin (Locking member) 30) Deviation detection belt (flexible member) 31a-31b Locking holes I, II, III areas

Continuation of front page (56) References JP-A-5-338842 (JP, A) JP-A-5-44801 (JP, A) JP-A-6-255826 (JP, A) JP-A-5-24641 (JP) , U) Utility model registration 2554549 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 5/02

Claims (3)

(57) [Claims] 1. A flat belt, a plurality of rollers around which the flat belt is wound, and at least one of the rollers is configured as a deflection adjusting roller; and one of the deflection adjusting rollers. A deviation detecting member rotatably supported independently of the deviation adjusting roller at a shaft end of the shaft; and a one-side donation for moving the flat belt toward a position where the deviation detecting member is disposed. And the flat belt is deflected by the biasing means, and the flat belt comes into contact with a partial area of the outer peripheral surface of the deflection detecting member due to the deflection. When a rotational torque is applied to the deviation detecting member, the rotational movement of the deviation detecting member is converted into a movement in which the shaft end of the deviation adjusting roller is displaced in a predetermined direction, and the flat belt is moved. A roller end displacing means for moving in a direction away from the deviation detecting member; By changing the position of the deviation detecting member with respect to the shifting means, the area of the outer peripheral surface of the deviation detecting member contacted by the flat belt displaced by the offset imparting means is variable, A belt driving device, wherein a linked position of the roller end displacement means is changeable. The roller end displacement means includes a flexible member that can be wound around a part of the deviation detecting member, while one end of the flexible member is engaged with the deviation detecting member. Locking holes are provided at a plurality of places where a locking member to be stopped can be attached,
2. The belt according to claim 1, wherein the connecting position of the roller end displacement means in the deviation detecting member is changed by changing the locking hole in which the locking member is mounted. Drive. 3. An outer peripheral surface of the deviation detecting member which is contacted by the flat belt which has been deviated by the offset imparting means is formed by a tapered surface, and the tapered surface has a plurality of sections partitioned in the circumferential direction. The belt drive device according to claim 1, wherein an inclined region is formed, and each inclined region is set so that a taper angle of a tapered surface is different from each other.