JP2002182483A - Belt driving device and electrophotographic device provided with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the elongation of a belt side edge part in a belt length direction even though the belt side edge part always comes over a detection ring 29 having a tapered cross section in the color printer of an electrophotographic system by which a transfer-feeding belt run and driven so as to feed recording paper to several image forming parts is deviated on the side of the movable end 6a of a control roller 6, and on the other hand, the movable end 6a is moved on a front side in a belt running direction by the torque of the detection ring 29 so as to control belt meandering. SOLUTION: The end part size ϕ1 of the detection ring 29 on the side of the control roller 6 is set as less than the outside diameter ϕ0 of the control roller 6 (ϕ1<ϕ0).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt drive for controlling the meandering of a belt for conveying an object such as a recording sheet by utilizing the torque of a detecting member which is rotated by contact with the belt. The present invention relates to an apparatus and an electrophotographic apparatus including the same, and particularly to a measure for suppressing belt elongation caused by contact with a detection member.

[0002]

2. Description of the Related Art For example, in an electrophotographic color printer, as shown in FIG. 2, a plurality of colors for a plurality of colors are placed on a traveling path of a transfer conveyance belt 1 wound around a plurality of rollers 4 to 7 so as to be able to travel. (4 colors in the example shown)
, D,... D are arranged so that each toner image is sequentially transferred onto the recording sheet p while the recording sheet p supplied on the transfer conveying belt 1 is conveyed by the belt.

In such a color printer,
When the transfer conveyance belt meanders, the position of the toner image is shifted in the belt width direction, and the image quality is degraded. To cope with this, a meandering control technique described in, for example, JP-A-11-263469 is known. In this one,
One of the plurality of rollers constitutes a control roller whose one shaft end is a movable end movable along the belt running direction on the roller.

Then, the transfer / conveying belt is biased toward the movable end of the control roller in the belt width direction. On the other hand, as shown in FIG. In addition, a detection ring c having a tapered cross section whose diameter gradually increases as it moves away from the control roller a in the axial direction (the left-right direction in the figure) is provided so as to be relatively rotatable. By moving the movable end a to the front side in the belt traveling direction by the torque at the time of rotationally driving the detection ring c, without using an electric meandering detection circuit or a dedicated driving means, and in the belt width direction. Belt meandering can be controlled without increasing the belt tension on the movable end side.

[0005]

In the above-described color printer, since the transfer roller is biased toward the movable end b of the control roller a, this transfer roller belt is A minute displacement in the axial direction is repeated with the side edge always riding on the detection ring c. As a result, in the case of the related art, there is a problem that the belt side edge is stretched and durability is likely to be reduced.

Further, the transfer / conveying belt includes a control roller a
In addition, since the vehicle travels while always straddling the gap in the axial direction between the detection rings c, there is also a problem that a portion of the belt base material corresponding to the gap is easily deformed into a state of being depressed in the gap.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and a main object of the present invention is to provide a belt which is driven so as to convey an object to be conveyed, such as recording paper, on a movable end side of a control roller. A belt whose belt side edge portion rides on the movable end while being shifted, and the movable end is moved to the front side in the belt traveling direction by the torque of a detecting member having a tapered cross section that is rotationally driven to control belt meandering. An object of the present invention is to improve the taper shape of the detection member in the drive device so as to suppress the belt elongation caused by the belt side edge always riding on the detection member.

[0008]

In order to achieve the above object, according to the present invention, the diameter of the end of the detection member on the control roller side is made smaller than the outer diameter of the control roller. In spite of the fact that the edge always rides on the detecting member, the extension of the belt side edge can be suppressed.

More specifically, according to the first aspect of the present invention, a plurality of rollers arranged so that their axes are substantially parallel to each other,
An endless belt wrapped around the rollers so as to be able to travel, and one of a plurality of rollers, and the belt is driven so as to transport an object placed on the belt. A driving roller, a control roller having at least one of a plurality of rollers, and one shaft end serving as a movable end movable along the belt traveling direction; A bias imparting means for imparting a bias toward the movable end of the control roller; and a rotatable drive provided on the movable end of the control roller by contact with a belt biased toward the movable end. A detecting member having a tapered cross section whose diameter gradually increases as it moves away from the control roller in the axial direction, and receives a torque generated by rotating the detecting member to move the movable end of the control roller in the belt traveling direction. Along a belt drive system including a moving means for moving is a prerequisite.

[0010] It is assumed that the end diameter of the detection member on the control roller side is smaller than the outer diameter of the control roller.

In the above configuration, in the belt driving device, the belt is driven by the driving rollers and travels between the rollers, so that the object placed on the belt is conveyed.

On the other hand, the above-mentioned belt is shifted to the movable end side of the control roller in the belt width direction by the offset imparting means, and the belt side edge rides on the detecting member to rotate and drive the detecting member. Then, a torque corresponding to the riding amount of the belt side edge is generated in the detecting member. Then, the movable end of the control roller is moved to the front side in the belt traveling direction by the moving means that has received the torque of the detection member, so that the belt on the control roller is displaced away from the detection member. Due to this displacement, the amount of rise of the belt side edge portion with respect to the detection member is reduced, and the torque of the detection member is reduced. To increase the amount by which the side edge of the belt rides. That is, the belt repeats the axial displacement while the side edge portion always stays on the detection member, and the axial position of the belt becomes constant through the repetition.

At this time, the end of the detection member on the control roller side
Diameter φ₁Is the outer diameter of the control roller φ₀Less than (φ₁<Φ₀)
Therefore, the side edge of the belt always rides on the detecting member.
However, the elongation at the side edge of the belt is
Diameter φ of end part of material on control roller side ₁Is the outer diameter of the control roller φ₀
Same as (φ₁= Φ₀) Is less than the conventional case
available.

According to a second aspect of the present invention, in the first aspect, the axial gap between the detection member and the control roller is less than 2 mm.

In the above configuration, when the belt runs at a substantially constant position in the axial direction with a slight displacement in the axial direction, the belt of the belt portion corresponding to the axial gap between the control roller and the detecting member is moved. The base material tends to deform into a state of sinking into the gap.

At this time, since the size s of the gap is less than 2 mm (s <2 mm), the deformation as described above is smaller than the conventional case where the size s of the gap is 2 mm or more (s ≧ 2 mm). Can be suppressed.

According to a third aspect of the present invention, in the electrophotographic apparatus provided with the above-described belt driving device, the transported object is a recording sheet on which a toner image is transferred. And an image forming means disposed along a belt running path of the belt driving device and forming a toner image and transferring the formed toner image to the recording paper on the belt of the belt driving device. And

In the above configuration, in the electrophotographic apparatus,
As the belt is driven to travel, the toner image is transferred to the recording paper placed on the belt by the image forming means. Therefore, the functions of the first and second aspects of the present invention are specifically performed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 schematically shows the overall structure of a transfer / transport unit according to an embodiment of the present invention. The transfer / transport unit is incorporated in an electrophotographic color printer and is mounted on a recording paper p. Used to transfer and fix the toner image.

The transfer and transport unit includes a plurality of (four in the illustrated example) image forming units A to D for transferring the toner images onto the recording paper p while forming the toner images of the respective colors; And a fixing unit E for fixing the toner image transferred to the image forming apparatus. Further, the image forming apparatus has a transfer conveyance belt 1 and, by driving the transfer conveyance belt 1 in a counterclockwise direction in FIG. 2, the recording paper p supplied from a paper supply unit (not shown).
, A belt driving device F that sends the toner image to the fixing unit E via the four image forming units A to D in order.

In each of the image forming sections A to D, a cylindrical photosensitive drum 2 for transferring the toner image onto the recording paper p by contact with the recording paper p while forming a toner image, Are transfer rollers 3 for holding the transfer conveyance belt 1 between the transfer rollers and the corresponding photosensitive drum 2 to bring the recording paper p on the transfer conveyance belt 1 into contact with the photosensitive drum 2. And These four image forming units A to D are arranged in order in the belt running direction (the direction indicated by the arrow in FIG. 2) toward the fixing unit E, and the first image forming unit A is a yellow toner. Statue, 2
The third image forming unit B forms a magenta toner image, the third image forming unit C forms a cyan toner image, and the fourth image forming unit D forms a black toner image. The image is transferred onto the sheet p.
In addition, the base material of the transfer / conveying belt 1 includes P having a high relative dielectric constant.
A resin film such as ET (polyester), ETFE (ethylene / tetrafluoroethylene copolymer), or PVDF (vinylidene fluoride resin) is used, and a dielectric material is disposed on the surface thereof.

As shown in FIG. 3, the belt driving device F has four rollers 4 to 7 arranged so that their axes are substantially parallel to each other.
Is wrapped around these rollers 4 to 7 so as to run. Among these rollers 4 to 7, the roller 4 disposed near the fixing unit E is a driving roller that drives the transfer conveyance belt 1 to travel by frictional contact with the transfer conveyance belt 1. Transfer unit chassis 8
And is drivingly connected to an electric motor (not shown). As a material of the drive roller 4, a material having a high friction coefficient with the transfer / conveying belt 1, for example, EPDM (ethylene-propylene-diene copolymer)
Crosslinked rubber or the like is used. In addition, other rollers 5
As the material of 7, a metal such as stainless steel or an aluminum alloy, or the same type of rubber as that of the drive roller 4 is used.

A roller 5 disposed on the front side (lower right side in FIGS. 2 and 3) of the drive roller 4 in the belt traveling direction is a tension roller for applying tension to the transfer / conveyance belt 1. The tension roller 5 is rotatably attached to each end of a pair of L-shaped members 9 attached to the chassis 8. Each L-shaped member 9 is pivotally supported by a chassis 8 at a bent portion in a vertical plane perpendicular to the axis of the tension roller 5, and an L-shaped member is provided between the other end and the chassis 8. A tension coil spring 10 that constantly urges the letter-shaped member 9 in the direction in which the tension roller 5 presses the inner peripheral surface of the transfer / transport belt 1 (clockwise direction in FIG. 3) is interposed. A tension is applied to the belt 1.

The roller 6 disposed in front of the tension roller 5 in the belt traveling direction (right side in FIGS. 2 and 3)
It is a control roller for controlling the meandering of the transfer conveyance belt 1. As will be described later in detail, one end of the control roller 6 is a movable end 6a that can move along the belt running direction on the control roller 6, and the movement of the movable end 6a causes the transfer conveyance belt to move. One meander is controlled.

A roller 7 disposed in front of the control roller 6 in the belt traveling direction (left side in FIGS. 2 and 3) is a guide roller, and a transfer roller formed between the guide roller 7 and the drive roller 4 is provided. Of the two upper and lower spans of the transport belt 1, the upper span is the transport span. Also,
Above the guide roller 7, an auxiliary roller 11 rotatable around an axis parallel to the guide roller 7 is arranged. The pair of upper and lower rollers 7 and 11 hold the transfer conveyance belt 1 in a state where the transfer conveyance belt 1 is sandwiched in the belt thickness direction.
, The recording paper p supplied from the paper feeding unit is received on the transfer conveyance belt 1 in accordance with the traveling speed of the transfer conveyance belt 1.

The transfer rollers 3 of the three image forming units A to C other than the black image forming unit D among the four image forming units A to D, the guide roller 7 and the auxiliary roller 11 are illustrated in FIG. As shown in FIG. 3, the transfer frame 12 is rotatably held by the transfer frame 12, and the transfer frame 12 is pivotally supported on the chassis 8 so as to be swingable about the same axis as the transfer roller 3 of the image forming section D for black. Have been. At this time, the transfer roller 3 of the black image forming unit D is disposed at a position where the transfer roller 1 is always sandwiched between the transfer roller 3 and the corresponding photosensitive drum 2 and is directly attached to the chassis 8. The transfer frame 12 is moved by a swing mechanism described below in a full-color mode in which full-color printing is performed.
The transfer rollers 3 of all the image forming units A to D
In the monochrome mode in which monochrome printing is performed, the transfer rollers 3 of each of the three image forming units A to C other than the black type are in contact with the photosensitive drum 2. Transfer conveyor belt 1 between
Is pivoted downward from the above-described position for sandwiching.

Below the transfer frame 12, a swing mechanism 13 for swinging the transfer frame 12 according to the mode is provided.
Is provided. The oscillating mechanism 13 has a drive shaft 14 arranged in parallel with the rollers 3 to 7 and 11 described above. The drive shaft 14 is drivingly connected to a driving means (not shown). Each time it is switched, it is driven to rotate by half a turn. A cam member 15 is connected to the drive shaft 14 so as to rotate integrally therewith. A support shaft 16 disposed parallel to the drive shaft 14 is provided on a side (right side in FIG. 3) of the drive shaft 14. Is provided. The support shaft 16 is supported by the chassis 8 at both ends. An intermediate member 17 and a pressing member 18 are provided on the support shaft 16 so as to extend in a direction orthogonal to the support shaft 16.
It is mounted so that it can swing around. Intermediate member 17
The lower surface of one end (the left end in the figure) has the cam member 1
5, and the pressing member 18 is
The upper surface of one end (the left end in the figure) is arranged to contact the lower surface of the transfer frame 12 from below. The other end portions (both right end portions in the figure) of the intermediate member 17 and the pressing member 18 are disposed so as to face up and down, and a compression coil spring 19 is compressed between these two other end portions. In this case, the intermediate member 17 and the pressing member 18 are constantly urged so that each one end thereof is pressed against the cam member 15 and the transfer frame 12, respectively. And in full color mode,
When the cam member 15 pushes up one end of the intermediate member 17 by the rotation of the drive shaft 14, the other end of the pressing member 18 is pushed down, and one end of the pressing member 18 pushes up the transfer frame 12. At times, the rotation of the drive shaft 14 allows the cam member 15 to allow the one end of the intermediate member 17 to move downward, thereby
Rotates downward.

As shown in FIG. 4, the control roller 6 has a shaft member 20 and is fitted over the shaft member 20.
The roller body 22 is rotatably held by the shaft member 20 via bearings 21 and 21 arranged at both ends in the axial direction. The movable end 6a is formed by one end (left side in FIG. 4) of both ends of the shaft member 20, and the movable end 6a is attached to the chassis 8 by screws 42, 42,. Supported by the supporting member 23. The other end (right side in the figure) of the shaft member 20 is a fixed end 6b that is immovable in a direction orthogonal to the axis. The fixed end 6b is directly supported by the chassis 8.

As shown in FIGS. 5 and 6, the periphery of the support member 23 has a substantially semicircular shape.
Reference numeral 3 denotes a transfer / conveying belt 1
It is arranged so as to be located in a direction to receive a force applied to the control roller 6 at a substantially right angle by the tension of the control roller 6. A relatively small first recess 24 is formed in the center of the linear portion in a cut-out state. Big second
Is formed in a cut-out state. The movable end 6a of the control roller 6 is connected to the first and second
It is arranged so as to penetrate the recesses 24 and 25 in the axial direction.
At this time, the bottom surface of the first concave portion 24 is in the belt running direction (FIG. 5).
The movable end 6a is supported by the guide surface 23a so as to be slidable forward and backward in the belt traveling direction. Then, when the movable end 6a moves forward (upper side in each figure) in the belt traveling direction, the roller body 22 displaces the transfer conveyor belt 1 toward the fixed end 6b side (right side in FIG. 5). When the movable end 6a moves rearward (downward in each drawing) in the belt running direction, the roller body 22 is transferred to the transfer / transport belt 1 by the guide. The belt 1 is rotated while being guided in a direction for displacing the belt 1 toward the movable end 6a (the left side in FIG. 5).

A protruding portion 26 protruding laterally in the belt width direction is provided behind the support member 23 in the portion of the chassis 8 (left portion in FIG. 4) on which the support member 23 is mounted. Is provided. On the other hand, on the movable end 6 a of the control roller 6, an annular locking member 27 is connected so as to be fitted to the shaft member 20 outside. Between the protruding ends of the protruding portions 26 and the locking members 27, tension coil springs 28 as offset imparting means are interposed in an extended state, and move the movable end 6a of the control roller 6 in the belt running direction. Side, and the flat belt 1 on the control roller 6 is biased toward the movable end 6a.

As shown in FIG. 7, a detection ring 29 as a detection member is disposed between the roller body 22 of the control roller 6 and the support member 23. The detection ring 29 is rotatably provided on the shaft member 20 of the control roller 6, and a certain axial gap is secured between the detection ring 29 and the roller body 22. The detection ring 29 is formed in a tapered cross section whose diameter gradually increases as it moves away from the roller main body 22 along the axis. By doing so, it is designed to be rotationally driven in the counterclockwise direction in FIGS. Also, the detection ring 29
7 is formed in an outward flange shape protruding outward in the radial direction. The side peripheral surface of the tapered portion and the surface of the flange portion on the side of the roller body 22 (right side in the figure) are formed of a material having a required friction coefficient with the transfer / transport belt 1. Examples of such materials include metals such as stainless steel, hard resins such as polyacetal and polyamide, and rubbers mixed with short fibers and made to project short fibers on the surface in a certain direction.

On the movable end 6a of the control roller 6, a pinion 30 is disposed on the side of the detection ring 29 opposite to the roller body 22 (the left side in FIGS. 4 and 5).
The pinion 30 is connected to the shaft member 20 so as to rotate integrally therewith. On the other hand, a rack 31 that meshes with the pinion 30 is provided at the bottom of the second recess 25 of the support member 23. The pitch line of the rack 31 is set so that the dimension between the pitch line of the rack 31 and the guide surface 23a in the direction perpendicular to the axis of the control roller 6 is constant, that is, the movable end 6
The pinion 30 is set so as to always mesh when a slides on the guide surface 23a. And the control roller 6
When the upper transfer conveyance belt 1 rotationally drives the detection ring 29, the pinion 30 rotates in the same direction as the detection ring 29 and rolls forward on the rack 31 in the belt traveling direction. The movable end 6a moves forward in the belt running direction against the urging force of the extension coil spring 28. That is, the moving means in the present invention is
It is constituted by the pinion 30 and the rack 30.

In this embodiment, FIG.
As shown, the control roller 6 of the detection ring 29
Side end diameter φ₁Is the outer diameter φ of the control roller.₀Less than (φ₁
<Φ ₀) Has been made.

Specifically, the axial dimension L of the tapered surface portion
Is, for example, several cm, the angle α between the ridge line on the tapered surface of the detection ring and the axis is α = 1.0 to 1.5.
° and the axial center position of the tapered surface ((1/2)
Diameter phi ₂ in L) has been made equal (φ ₂ = φ ₀₎ to the outer diameter phi ₀ axis of the control roller.

The detection ring 29 and the control roller 6
Is less than 2 mm (s <2
mm).

Next, the operation of the belt meandering control in the belt driving device F of the transfer / transport unit configured as described above will be described.

In the color printer, the transfer / conveying belt 1 is driven by a driving roller 4 to travel in a counterclockwise direction between rollers 3-7. At this time, the control roller 6
Is moved on the guide surface 23a of the support member 23 rearward in the belt running direction by the urging force of the tension coil spring 28, so that the transfer / conveyance belt 1 6 displaces to the movable end 6a side. That is, the transfer conveyance belt 1 on the control roller 6 is shifted toward the movable end 6a as it travels.

When the transfer / transport belt 1 is shifted toward the movable end 6a and the belt side edge rides on the detection ring 29,
The detection ring 29 is driven to rotate by the transfer / transport belt 1, and the detection ring 2
9 generates torque. Then, the torque causes the pinion 30 to rotate in the same direction as the detection ring 29 and roll forward on the rack 31 of the support member 23 in the belt traveling direction. As a result, the movable end 6a of the control roller 6 moves forward on the guide surface 23a of the support member 23 in the belt traveling direction against the urging force of the tension coil spring 28. 1, this time, fixed end 6b
The force in the direction displaced to the side is applied.

When the transfer / conveying belt 1 is displaced toward the fixed end 6b, the amount of rise of the belt side edge with respect to the detection ring 29 is reduced, and the torque of the detection ring 29 is reduced. A pinion 30 for moving the movable end 6a of the roller 6 forward in the belt running direction;
And the force of the rack 31 also decreases. As a result, the movable end 6a of the control roller 6 is again moved rearward in the belt running direction by the urging force of the tension coil spring 28. As a result, a force biasing toward the movable end 6a again is applied to the transfer conveyance belt 1 on the control roller 6.

Through the repetition of the above operation, the transfer / conveying belt 1 is kept constant in the belt width direction on the detection ring 29 and the control roller 6 with the belt side edge always riding on the detection ring 29. Will be traveling in the position. That is, the transfer conveyance belt 1 travels without meandering.

At this time, as shown in FIG. 1A, the end diameter φ _{1 of the} detection ring 29 on the control roller 6 side is smaller than the outer diameter φ ₀ of the control roller 6 (φ ₁ <φ ₀ ). because, despite the belt side edge is riding always on the detection ring 29, elongation occurs in the belt side edges, as shown in FIG. 1 (b), the end portion diameter phi ₁ of the detection ring c Control roller a
Is smaller than the conventional case where the outer diameter is the same as the outer diameter φ ₀ (φ ₁ = φ ₀ ).

When the transfer / conveyor belt 1 travels at a substantially constant position in the axial direction with a slight displacement in the axial direction, it corresponds to the axial gap between the detection ring 29 and the control roller 6. The belt base material of the belt portion is going to be deformed into a state of sinking into the gap.

At this time, since the size s of the gap is less than 2 mm (s <2 mm), the size s of the gap is as shown in FIG.
As shown in (2), the above-mentioned deformation is suppressed as compared with the conventional case of 2 mm or more (s ≧ 2 mm).

Therefore, according to the present embodiment, the transfer conveyance belt 1 that is driven to travel to convey the recording paper p to the four image forming units A to D is controlled by the control roller 6 by the urging force of the tension coil spring 28. The pinion 30 rolls on the rack 31 by receiving the torque of the detection ring 29 having a tapered cross section that is rotated and driven to rotate on the movable end 6a while the belt side edge rides on the movable end 6a. in an electrophotographic color printer which is adapted to control the belt meandering by moving the movable end 6a in the belt traveling direction front side by the end diameter phi ₁ of the control roller 6 side of the detection ring 29, the control roller 6 Less than φ ₀ (φ ₁ <
(φ ₀ ), the belt side edge can be prevented from elongating in the belt length direction even though the belt side edge always rides on the detection ring 29.

The detection ring 29 and the control roller 6
Is set to less than 2 mm (s <2 mm), so that the gap size s is 2 mm or more (s ≧ 2 m
m), it is possible to suppress deformation of the belt base material of the belt portion corresponding to the gap in a state of being depressed in the gap, as compared with the conventional case of m).

In the above embodiment, the bias applying means is constituted by the tension coil spring 28 which constantly biases the movable end 6a of the control roller 6 rearward in the belt running direction. The configuration is not particularly limited, for example, a roller other than the control roller is arranged to be inclined with respect to the belt width direction.

In the above embodiment, the pinion 30
In the present invention, one end of the wire is wound around the boss of the detection ring 29, and the other end of the wire is fixed to the support member 23. Other types of moving means such as a moving means can be used.

Further, in the above embodiment, the case of the belt driving device F of the transfer / transport unit incorporated in the electrophotographic color printer has been described, but the present invention can be applied to various belt driving devices. it can.

[0050]

As described above, according to the first aspect of the present invention, the belt driven to move the conveyed object is biased toward the movable end of the control roller, while the belt is shifted on the movable end. In the belt driving device, the belt meandering is controlled by moving the movable end to the front side in the belt traveling direction by the torque of the detecting member having a tapered cross section that is rotated and driven by the side edge portion of the belt being driven. Since the end diameter on the roller side is set to be smaller than the outer diameter of the control roller, the belt side edge in the belt length direction of the belt side edge is irrespective of the belt side edge always riding on the detecting member. Elongation can be suppressed.

According to the second aspect of the present invention, the gap between the detection member and the control roller is set to be smaller than 2 mm, so that the gap is smaller than the conventional case where the gap is 2 mm or more. It can be suppressed that the belt base material of the belt portion to be deformed into a state of being depressed in the gap.

According to the third aspect of the present invention, since the above-described belt driving device is provided as an electrophotographic apparatus,
The effects of the first and second aspects of the invention can be specifically obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a main part (a) of a color printer according to an embodiment of the present invention, together with a conventional case (b).

FIG. 2 is a side view schematically illustrating the entire configuration of the transfer / conveyance unit.

FIG. 3 is a side view showing the overall configuration of the belt driving device.

FIG. 4 is a front view showing a control roller and a peripheral portion thereof.

FIG. 5 is a perspective view showing a movable end of a control roller and a peripheral portion thereof.

FIG. 6 is a side view showing a movable end of a control roller and a peripheral portion thereof.

FIG. 7 is a side view showing a detection ring on a movable end of a control roller.

[Explanation of symbols]

F Belt drive 1 Transfer / transport belt (belt) 4 Drive roller 5 Tension roller (roller) 6 Control roller 6a Movable end 7 Guide roller (roller) 28 Tension coil spring (side-off imparting means) 29 Detection ring (detection member) 30 Pinion (moving means) 31 Rack (moving means) φ ₀ Outer diameter of the control roller φ ₁ End diameter (on the control roller side of the detection ring) s Gap (in the axial direction between the detection ring and the control roller) Dimensions A to D Image forming unit (image forming means) p Recording paper (conveyed object)

Continued on the front page (72) Inventor Tetsushi Kurokawa 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo Office (72) Inventor Hiroshi Mihashi 3-2-15 Meiwadori, Hyogo-ku, Kobe-shi, Hyogo Prefecture F term in Bando Chemical Co., Ltd. (reference) 2H032 BA18 BA23 2H072 AB07 CA07 JA03 3F049 AA02 BB07 BB11 DA04 LA01 LB03

Claims (3)

[Claims] A plurality of rollers arranged so that their axes are substantially parallel to each other; an endless belt wrapped around the plurality of rollers so as to be able to run; and one of the plurality of rollers A driving roller, which comprises a roller, and which drives the belt to travel so as to convey an object placed on the belt, comprising one or more rollers of the plurality of rollers,
A control roller having one shaft end as a movable end movable along the belt traveling direction, and a bias applying means for imparting a bias to the movable end of the control roller in the belt width direction to the belt. Is provided on the movable end of the control roller so as to be rotationally driven by contact with the belt biased to the movable end side,
A detecting member having a tapered cross section whose diameter gradually increases as the distance from the control roller in the axial direction increases, and a torque generated by rotating the detecting member is received,
A moving means for moving the movable end of the control roller along the belt traveling direction, wherein the end diameter of the detection member on the control roller side is smaller than the outer diameter of the control roller. A belt drive device characterized in that: 2. The belt driving device according to claim 1, wherein an axial gap between the detecting member and the control roller is 2 mm.
mm. 3. An electrophotographic apparatus comprising the belt driving device according to claim 1, wherein the conveyed object is a recording sheet onto which a toner image is transferred, and the conveyance object includes a belt running path of the belt driving device. Are placed along
An electrophotographic apparatus comprising: an image forming unit that forms the toner image and transfers the formed toner image to the recording sheet on a belt of a belt driving device.