JPH0733232Y2 - Reciprocating drive device for scanning moving body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reciprocating drive device for a scanning moving body such as a document table in an image forming apparatus.

2. Description of the Related Art In a copying machine, which is an example of an image forming apparatus, a document table is driven to reciprocate to illuminate and scan a document with a fixed optical system. Further, in a copying machine in which a document table is fixed, an optical system is reciprocally driven, and the document is illuminated and scanned during this forward movement.

Conventionally, a chain loop system has been generally adopted as a device for reciprocally driving a scanning movable body such as a document table and an optical system. FIG. 5 shows a conventional example of a reciprocating drive device for a document table using such a chain loop.

In the figure, a chain 3 is stretched over the drive sprocket 1 and the driven sprocket 2, and when the chain 3 rotates in the direction of the arrow, the drive pin 4 directly connected to the chain 3 and fitted in the long hole 5a moves the document table 5 into place. The original table 5 is adapted to be reciprocally driven. That is, the rotational movement of the chain is converted into the reciprocating movement of the platen.

However, the drive system using the chain 3 and the sprocket has a problem that the chain moves in a polygonal manner, which causes a speed fluctuation on the document table, appears as jitter on the image, and deteriorates the image quality.

On the other hand, there is one that uses a timing belt loop. Recently, the timing belt has been improved in its tooth profile so as to be closer to a circular motion, and the speed fluctuation is smaller than that of the chain.

However, the belt itself is vulnerable to twisting, so that there is a problem that the connecting portion with the document table is disengaged or that the velocity of the document table varies due to the influence of the twisting and the vertical vibration of the belt.

OBJECT The object of the present invention is to solve the above-mentioned problems in a reciprocating drive device for a scanning moving body using a timing belt.

To achieve the above object, the present invention relates to a reciprocating drive device for a scanning moving body according to the present invention, wherein an endless timing belt stretched between a drive pulley and a driven pulley and reciprocatingly driven by the timing belt. A scanning moving body,
A connecting member provided at both ends of the scanning movable body and having elongated holes formed in a direction orthogonal to the extending direction of the timing belt, and a drive extending from both end portions of the timing belt and fitted into the elongated holes. A pin, a guide member fixedly disposed on both side ends of the timing belt, and a pressing member for pressing the drive pin against a side edge portion of the guide member are provided.

Hereinafter, the present invention will be described based on an embodiment.

In FIG. 1, an endless timing belt 13 is stretched between a drive pulley 11 and a driven pulley 12. A connecting member is provided at both end portions of a document table 15 which is an example of a scanning moving body.
16 is fixed by a screw or the like, or is formed integrally with the document table.

A drive pin 17 is fixedly inserted into the bulged portion 13a of the timing belt 13 as shown in FIG. 2, and both ends of the drive pin 17 extend in a direction orthogonal to the belt tension direction of the connecting member 16. It is fitted in the long hole 16a (FIG. 3) drilled in.

As shown in FIG. 3, guide members 18, 18 are arranged at both ends of the timing belt 13, and the notches 1 at both ends are provided.
8a is fitted on the pulley shaft 19 (Fig. 4) and is held stationary.

In FIG. 1, the base end of a pressing member 20 made of a leaf spring or the like is fixed to the lower surface side of the document table 15, and the free end presses the bulging portion 13a of the timing belt 13 and the drive pin 17
As shown in FIG. 4, the upper edge portions of both guide members 18 are pressed against each other.

As shown in FIG. 4, the pulley shaft 19 is rotatably supported by a machine frame 23 via a bearing 22, and the document table 15 is movably supported by a slide rail device 24.

In FIG. 1, when the drive pulley 11 rotates with the start of copying, the timing belt 13 rotates, and at this time, the drive pin 17 carries the connecting member 16 and moves the document table 15.
The drive pin 17 moves along this loop locus together with the timing belt 13 to drive the document table 15 back and forth with one rotation.

When the timing belt 13 is rotationally driven, as shown in FIG. 3, the pressing action of the pressing member 20 causes the drive pin 17 to move in pressure contact with the upper edge portions of both guide members 18. That is, the drive pin 17 is always held in a constant posture and displaced, and the drive pin is prevented from coming off the connecting member due to the twisting of the belt itself. Further, since the vertical vibration of the belt between both pulleys is suppressed, the document table can be constantly driven at a constant speed, and the image quality is not deteriorated.

As described above, according to the present invention, since the connecting member of the drive pin is prevented from coming off, it is possible to continuously drive the scanning moving body reliably. Further, since the vertical vibration of the belt is suppressed, the scanning moving body can be driven at a constant speed, and the image quality is not deteriorated.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of a timing belt portion to which a drive pin is attached, FIG. 3 is a perspective view showing a main part of the apparatus, and FIG. And FIG. 5 is a schematic diagram showing a conventional example. 11 ... Drive pulley, 12 ... Followed pulley 13 ... Timing belt 15 ... Document table 16 as scanning moving body 16 ... Connecting member, 17 ... Drive pin 18 ... Guide member, 20 ... Pressing member

Claims (1)

[Scope of utility model registration request] 1. An endless timing belt stretched between a drive pulley and a driven pulley, a scanning movable body reciprocally driven by the timing belt, and a timing belt provided at both end portions of the scanning movable body. A connecting member having a long hole formed in a direction orthogonal to the extending direction, drive pins extending from both side ends of the timing belt and fitted into the long hole, and fixedly arranged on both side ends of the timing belt. Reciprocating drive device for a scanning moving body, which includes a guide member and a pressing member that presses the drive pin against a side edge portion of the guide member.