JPH10291672A - Conveyer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend endurance life of a belt-shaped member and a conveyer roller and improve their skew prevention function, by setting configuration of one conveyer roller to a crown configuration and one of conveyer rollers near the crown-shaped conveyer roller to a reverse crown configuration. SOLUTION: The conveyer includes an endless belt 1, a reverse-crown-shaped conveyer roller 2, and a crown-shaped conveyer roller 3 near the reverse-crown- shaped conveyer roller 2. Diameters of central part and both end parts of conveyer rollers 4-6 are equaled so that contact face between the belt 1 and the conveyer rollers is uniformed, tension adding mechanism 7 is provided for the conveyer roller 4, and a driving mechanism 8 is provided for the conveyer roller 6. Material of outer periphery, that is contact surface with the belt 1, of the reverse- crown-shaped conveyer roller 2 and the crown-shaped conveyer roller 3 is preferably material with small friction resistance. For example, a fluoric resin, stainless steel, or aluminum is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transport device suitable for use in an electrophotographic apparatus such as a printer, a facsimile, and a copying machine.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a printer, a facsimile, and a copying machine, a belt-shaped member (hereinafter, simply referred to as a belt) is used in a photosensitive member (such as an OPC), an intermediate transfer member, and a fixing device. There are cases. When a belt is used, the problem is to prevent skew in the traveling path (a problem that the belt moves in the axial direction of the transport roller during traveling). In particular, in the case of a photoreceptor or an intermediate transfer member, the position of a printed image is affected, and it is necessary to provide a means for preventing this skew.

[0003] Conventional means for preventing skew are roughly classified into first means for mechanically inhibiting or controlling skew of the belt.
And second means for preventing skew of the belt by the shape of the conveying roller or the shape of the support member inside the belt and the tension of the belt.

[0004] As the first means, for example, there is provided a structure in which a belt and a conveying roller are engaged with each other, and the displacement of the belt is mechanically prohibited from being shifted by the engagement. The shift of the line or transport position is detected by a sensor or the like, and mechanical means such as a solenoid
There is a means for correcting skew by controlling the tension on the belt.

The second means is to provide one or a plurality of transport rollers with a crown shape,
Alternatively, a plurality of transport rollers may have an inverted crown shape. Here, the crown-shaped roller refers to a roller in which the diameter of the center of the conveying surface of the roller is larger than the diameter of both ends of the conveying surface, and the inverted crown-shaped roller refers to the center of the conveying surface of the roller. The diameter of the portion is smaller than the diameter of both ends of the transport surface.

Incidentally, the crown-shaped roller is, for example,
JP-A-5-127543, JP-B-3-55825
JP, JP-A-4-44076, JP-A-3-23
No. 3,586, JP-A-3-12682, JP-A-63-301084, JP-A-62-95571, and the like. Further, rollers having an inverted crown shape are also disclosed in, for example, JP-A-7-109047, JP-A-4-116012, and JP-A-56-16.
No. 5,159, Japanese Utility Model Application Laid-Open No. 61-68055, and the like.

[0007]

However, the conventional first type
In the means of (1), the strength of the members constituting the belt is required or a member for controlling the tension of the belt is required. It is difficult in terms of price to adopt such a device for an inexpensive electrophotographic apparatus.

On the other hand, the second means is relatively easy to employ in an inexpensive electrophotographic apparatus because the components are inexpensive. However, when the belt is not skewed, the belt is not functioning as skew prevention.Therefore, the crown-shaped roller is located at the center of the belt, and the inverted crown-shaped roller is located at both ends of the belt. In this case, tension is always applied to the belt, which shortens the service life of the belt and the transport roller.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a transport device capable of extending the life of a belt-shaped member and a transport roller, thereby improving the skew prevention function. To provide.

[0010]

Means for Solving the Problems In order to solve the above problems, the present invention employs the following transport apparatus. That is,
A belt-shaped member, comprising a plurality of conveying rollers for conveying while applying a predetermined tension to the belt-shaped member, of the plurality of conveying rollers, one of the conveying rollers has a crown shape, One of the transport rollers near the transport roller has an inverted crown shape.

In this conveying device, tension is concentrated on the central portion of the belt-shaped member in the crown-shaped conveying roller, whereas tension is concentrated on both ends of the belt-shaped member in the inverted crown-shaped conveying roller. It will be. Therefore, the tension is evenly applied to the center and both ends of the belt-shaped member by the crown-shaped conveyance roller and the inverted crown-shaped conveyance roller, so that the tension is not concentrated on a specific portion. In addition, since tension is not concentrated on a specific portion, problems such as wear of the transport roller are reduced. Thereby, the durability life of the belt-shaped member and the transport roller is extended, and the skew preventing function is improved.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a transfer apparatus according to an embodiment of the present invention.

(First Embodiment) FIG. 1 is a longitudinal sectional view showing a transport device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an endless belt (belt-like member); Is a crown-shaped conveyance roller, 3 is a crown-shaped conveyance roller provided near the inverted crown-shaped conveyance roller 2, and 4 to 6 are a central portion and both end portions so that the contact surface with the belt 1 is uniform. A conveying roller having the same diameter, a tension applying mechanism (tension applying means) provided on the conveying roller 4, and a driving mechanism (driving means) provided on the conveying roller 6.

The material forming the outer peripheral surface of the reverse-crown-shaped conveying roller 2 and the crown-shaped conveying roller 3 which is in contact with the belt 1 is preferably a material having a small frictional resistance. steel,
Aluminum or the like is preferably used. On the other hand, as the material forming the outer peripheral surface of the transport roller 6 which is the contact surface with the belt 1, a material having a large frictional resistance is desirable, and for example, urethane rubber, silicon rubber, or the like is suitably used.

Here, the respective rotating shafts of the conveying rollers 2, 3, 5, and 6 are fixed, and the belt 1 is pushed by pressing the rotating shaft of the conveying roller 4 to the upper left in the figure by a tension applying mechanism 7.
Is tensioned. Further, the belt 1 can be rotated clockwise or counterclockwise in the figure by rotating the conveying roller 6 clockwise or counterclockwise in the figure by the drive mechanism 8. Here, it is rotated clockwise in the figure.

Next, a method for correcting skew of the transport mechanism according to the present embodiment will be described with reference to FIGS. When the belt 1 is not skewed, as shown in FIG. 2, since the tension is applied by the tension applying mechanism 7, the belt 1 is pressed against the surfaces of the inverted crown-shaped conveyance roller 2 and the crown-shaped conveyance roller 3. As a result, high tension occurs at positions B, C, and D in FIG. Here, these points are referred to as high tension points B, C, and D.

In practice, the surface shapes of the reverse crown-shaped transport roller 2 and the crown-shaped transport roller 3 are set so that the tension applied to these high tension points B, C, and D is substantially constant. You. Further, tension (BD) is generated between the high tension points B and D, and tension (CD) is generated between the high tension points C and D, and the belt 1 is skewed. Otherwise, the relational expression of tension (BD) = tension (CD) holds.

Next, as shown in FIG. 3, the case where the belt 1 is skewed to the right in FIG. 3 will be considered. At this time, the high tension points B and C move to B ′ and C ′, respectively.
Does not move. Here, the reverse crown-shaped transport roller 2
Since the central portion has a small diameter and both end portions have a large diameter, the tension at the high tension point B ′ at the left end of the belt 1 that has moved toward the central portion of the reverse-crown-shaped conveying roller 2 becomes small, and The tension at the high tension point C 'of the portion becomes large.

The change in the tension at the high tension points B 'and C' acts on the tension between the high tension points B 'and D and between the high tension points C' and D in the same manner. B'-
The relational expression of tension (B'-D) <tension (C'-D) holds between D) and tension (C'-D).

As a result, the high tension point C 'having a large tension moves in a direction approaching the high tension point D, so that the belt 1 returns to the original position from the skewed state. At this time, the high tension points B 'and C' move to the high tension points B and C.

As described above, according to the belt 1 of the first embodiment, since the inverted crown-shaped transport roller 2 is provided near the crown-shaped transport roller 3, only the inverted crown-shaped transport roller can be used. The load applied to the belt 1 is smaller than that of a transport device having only a crown-shaped transport roller, and the durability life of the belt 1 can be extended.

Further, as in the conventional transport device, the belt 1
This eliminates the need for a sensor such as a sensor for detecting skew and mechanical correction means, so that the components can be inexpensive, and low-cost skew can be applied to inexpensive products such as small electrophotographic devices. Preventive measures can be provided.

In the first embodiment, the transport roller 4 is provided with the tension applying mechanism 7;
As long as tension is applied to the belt 1, the belt may be provided on the other transport rollers 5 and 6. Although the drive mechanism 8 is provided on the transport roller 6, the drive mechanism 8 only needs to be able to rotate the belt 1 clockwise or counterclockwise in the figure, and may be provided on any of the transport rollers 4 to 6. Absent.

Further, it is desirable that the inverted crown-shaped transport roller 2 and the crown-shaped transport roller 3 rotate freely, but if sufficient smoothness can be obtained on the contact surface with the belt 1, the rotating shaft is fixed. It does not matter. In this case, the inverted crown-shaped transport roller 2 and the crown-shaped transport roller 3 need not be cylindrical.

(Second Embodiment) FIG. 4 is a longitudinal sectional view showing a transport device according to a second embodiment of the present invention.
Is provided on the crown-shaped conveyance roller 3 ′ instead of being provided on the conveyance roller 6.

Here, the belt 1 can be rotated clockwise or counterclockwise in the figure by rotating the crown-shaped conveying roller 3 ′ clockwise or counterclockwise in the figure by the drive mechanism 8. Here, it is rotated clockwise in the figure. In this case, as a material forming the outer peripheral surface of the crown-shaped conveying roller 3 ′ which is a contact surface with the belt 1, a material having a large frictional resistance, for example, urethane rubber, silicon rubber, or the like is desirable.

The skew correction can be performed in the transport apparatus of the present embodiment in exactly the same manner as in the transport apparatus of the first embodiment. In this case, the crown-shaped transport roller 3 in FIGS. 2 and 3 may be replaced with a crown-shaped transport roller 3 '.

[0028]

As described above, according to the transport device of the present invention, one of the transport rollers has a crown shape, and one of the transport rollers in the vicinity of the transport roller has a crown shape. With the inverted crown shape, tension can be evenly applied to the center and both ends of the belt-shaped member by the crown-shaped conveyance roller and the inverted crown-shaped conveyance roller, so that the tension is not concentrated on a specific portion. Can be Further, since the tension is not concentrated on a specific portion, problems such as wear of the transport roller can be reduced. Therefore, the durability life of the belt-shaped member and the transport roller can be extended, and the skew preventing function can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a transport device according to a first embodiment of the present invention.

FIG. 2 is a front view showing a state in which the belt of the transport device is not skewed as viewed from a viewpoint A in FIG. 1;

FIG. 3 is a front view showing a state in which the belt of the transport device is skewed as viewed from a viewpoint A in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a transport device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt (belt-shaped member) 2 Conveying roller of reverse crown shape 3, 3 'Conveying roller of crown shape 4-6 Conveying roller 7 Tension applying mechanism (tension applying means) 8 Drive mechanism (driving means) A Viewpoint B, C, D High tension point B ', C' High tension point when skewed

Claims (1)

[Claims] 1. A belt-like member, and a plurality of carry rollers for carrying the belt-like member while applying a predetermined tension, wherein one of the plurality of carry rollers has a crown shape. A conveying roller in the vicinity of the conveying roller, wherein one of the conveying rollers has an inverted crown shape.