JP3799192B2 - Driving device in image reading apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an image reading apparatus that reads document information in a facsimile machine, a copying machine, and the like, and particularly relates to a transport system driving device for transporting a document to a reading position.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a facsimile apparatus includes a conveyance roller that conveys a document to an image reading sensor, and the conveyance roller is rotationally driven by a drive motor via a timing belt and a timing pulley. In order to improve the conveyance accuracy of the conveyance roller, it is usually necessary to apply tension to the timing belt because it is necessary to prevent tooth skipping in the timing belt.
[0003]
As a structure for applying tension to the timing belt, a tension pulley described in Japanese Utility Model Publication No. 6-67952 or a structure in which a leaf spring is elastically contacted with the timing belt is used.
[0004]
[Problems to be solved by the invention]
In the conventional method of applying tension to the timing belt using a leaf spring, the leaf spring needs three functions in the case where the drive motor needs to be rotated forward and backward. That is,
First, in order to obtain an appropriate winding angle of the timing belt with respect to the timing pulley so as not to generate tooth jump in a normal load during normal rotation, a pressure is applied to regulate the position of the slack side belt.
The second is to apply a large pressure to prevent tooth skipping during reverse rotation.
The third is to generate tooth skipping as a fail-safe function when an overload occurs during normal rotation.
It is.
[0005]
However, it is very difficult to manufacture a leaf spring having the above three functions because it is very difficult to manage its shape or load (including belt tension management), increase the parts cost, increase the number of assembly steps, and further reduce the belt tension. There were many problems such as an increase in the load on the mechanical system accompanying the increase.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a driving device in an image reading apparatus that solves the above-mentioned conventional problems and prevents the occurrence of problems such as tooth skipping with a simple configuration so that smooth belt driving is performed. There is.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a separation roller for separating and conveying documents one by one and a conveyance roller for conveying the document to an image reading unit, and each of the rollers includes a timing belt and a timing pulley. In the image reading apparatus configured to appropriately rotate forward and reversely by a drive motor, a leaf spring that applies tension to prevent tooth skipping by elastic contact with the timing belt, and a height that restricts deformation of the leaf spring during reverse rotation. It is equipped with an elastic member such as a density sponge body or a low hardness rubber material, and with this configuration, the leaf spring has a characteristic of a small load that is easy to bend enough to prevent looseness during normal rotation. Even if it is set, excessive deformation in the leaf spring during reverse rotation can be restricted by the elastic member to prevent tooth skipping. The reduced even occurrence of problems such as a missing tooth that occurs by those of heavy load, it is easy to each part of the design. Furthermore, it is easy to attach a leaf spring having a small load, and the elastic member can function as a damper together with the leaf spring to prevent belt vibration.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is a schematic configuration diagram showing an image reading unit of a facsimile machine for explaining an embodiment of the present invention, FIG. 2 is an enlarged view of the image reading unit of FIG. 1, 1 is an apparatus main body, 2 is an apparatus main body 1 3 is a document setting table, 4 is a document discharge table, and 5 is a pickup roller for feeding a document on the document setting table 3, 6 is a pressure plate for pressing the document against the pickup roller 5, 7 and 8 are a feed roller and a separation roller for separating and conveying the document one by one, 9 is a reading sensor for reading document information, and 10 is installed above the reading sensor 9. White reference plates 11 and 12 are conveying rollers respectively installed on the upstream side and the downstream side in the document conveying direction of the reading sensor 9.
[0010]
In the image reading unit 2, the document set on the document setting table 3 is fed toward the feed roller 7 while being pressed against the pickup roller 5 by the pressure plate 6. Due to the difference in frictional resistance between the feed roller 7 and the separation roller 8, the document is conveyed one by one in the direction of the reading sensor 9 when the documents are fed in a known manner. The separated and conveyed original is read by the reading sensor 9 while being conveyed on the reading sensor 9 by the conveying rollers 11 and 12 at a predetermined conveying speed, and is then discharged to the original discharge table 4. .
[0011]
FIG. 3 is a block diagram showing the main part of the drive system of each roller in the image reading unit, 20 is a scanner base, 21 is a drive gear of a stepping motor (not shown), 22 is meshed with the drive gear and decelerated. , A driven timing pulley provided coaxially with the driven gear 22, 24 and 25 driven timing pulleys provided on the conveying rollers 11 and 12, and 26 a drive timing pulley 23 and a driven timing pulley 24, respectively. , 25 and a timing belt that transmits rotational driving force.
[0012]
Further, the driving force of the driving gear 21 of the stepping motor is transmitted to the feed roller 7 by a timing belt (not shown) or the like, and a position where the pickup roller 5 is brought into contact with the pressure plate 6 to feed paper, and the pressure plate It is used to move to a standby position away from 6.
[0013]
In FIG. 3, reference numeral 30 denotes a roller that presses the timing belt 26 and applies tension, 31 denotes a roller 30 that supports the roller 30 on the free end side 31a at one end, the intermediate portion 31b is curved in a substantially square shape, and the like. An end 31 c is a leaf spring fixed to the scanner base 20, and 32 is an elastic member such as sponge or rubber that is provided inside the leaf spring 31 and abuts against the free end 31 a of the leaf spring 31.
[0014]
In the present embodiment configured as described above, in FIG. 3, the timing belt 26 is moved in the forward rotation direction (arrow A direction) from the driving gear 21 of the stepping motor via the driven gear 22 and the driving timing pulley 23 during document conveyance. The rotational driving force is transmitted, and the transport rollers 11 and 12 are rotated in the forward rotation direction via the driven timing pulleys 24 and 25. At this time, the leaf spring 31 applies tension to the slack side of the timing belt 26 via the roller 30. The position of the roller 30 at this time is set at a position where the winding angle of the timing belt 26 with respect to the drive timing pulley 23 provided coaxially with the driven gear 22 does not cause tooth jump, and the leaf spring 31 Sufficient pressure (tension) is applied so as to be retained.
[0015]
When the timing belt 26 is moved in the direction of the arrow B in order to move the pickup roller 5 to the standby position, the slack side of the timing belt 26 becomes a tight side. However, the deformation is restricted by the elastic member 32 and excessive deformation of the leaf spring 31 is prevented, so that a tension state that prevents tooth skipping can be maintained.
[0016]
As described above, since the deformation of the leaf spring 31 at the time of reverse rotation is regulated by the elastic member 32, it is not necessary to perform a complicated shape design or load setting for the leaf spring 31 to cope with the deformation. It is possible to set a spring with a relatively small load that can prevent slack in the case.
[0017]
Further, since the leaf spring 31 has a small bending load, the assembly of the timing belt 26 is not hindered and the assembly is facilitated. Furthermore, since the spring load applied to each part is reduced, it is possible to prevent the occurrence of damage in each part, such as the occurrence of gear tooth chipping caused by an overload, which contributes to the improvement of durability.
[0018]
Further, since the elastic member 32 functions as a damper, vibration in the timing belt 26 is prevented, and smooth belt driving is realized.
[0019]
As the elastic member 32, any material having flexibility and elasticity that can be regulated by deformation of the leaf spring 31 can be used. For example, a high-density sponge body or a low-hardness rubber can be used. A material etc. are preferable.
[0020]
【The invention's effect】
As described above, according to the present invention, in a driving force transmission system using a timing belt, a configuration using a leaf spring to apply an appropriate tension to the timing belt has a complicated shape and spring. Without a load setting, it is possible to reliably prevent the occurrence of problems such as tooth skipping during forward and reverse rotation with a simple configuration, and smooth belt driving can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an image reading unit of a facsimile machine for explaining an embodiment of the present invention. FIG. 2 is an enlarged view of an image reading unit in the embodiment of the present invention. Schematic diagram showing the main part of the drive system of each roller of the image reading unit in
2 Image Reading Unit 5 Pickup Roller 7 Feed Roller 8 Separation Roller 9 Reading Sensors 11 and 12 Transport Roller 20 Scanner Base 21 Drive Gear 22 Driven Gear 23 Drive Timing Pulleys 24 and 25 Driven Timing Pulley 26 Timing Belt 30 Roller 31 Plate Spring 32 Elasticity Element

Claims (3)

A separation roller for separating and conveying the document one by one and a conveyance roller for conveying the document to the image reading unit are provided, and each of the rollers is appropriately forward / reversely driven by a drive motor via a timing belt and a timing pulley. An image reading apparatus comprising: a leaf spring that applies tension to elastically contact the timing belt to prevent tooth skipping; and an elastic member that restricts deformation of the leaf spring during reverse rotation. Drive device in reading device. 2. A driving device in an image reading apparatus according to claim 1, wherein the elastic member is a high-density sponge body. 2. The driving device in an image reading apparatus according to claim 1, wherein the elastic member is a rubber material having a low hardness.

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