JPH0865461A - Original reader - Google Patents

Abstract

PURPOSE: To control the fluctuation in the feed speed of an original read scanning unit in the subscanning direction. CONSTITUTION: A friction member 15 is installed between an original read scanning unit 1 and a frame 16 fixed to the reader to suppress the fluctuation in the speed of the original read scanning unit 1 when the original read scanning unit 1 is driven in the subscanning direction. Furthermore, anisotropic material whose load characteristic differs from a moving direction is used for the friction member 15. Furthermore, the load of the anisotropic material in the read direction of the original read scanning unit 1 is set higher than the load in the initial position restoring direction to attain high speed restoration of the original read scanning unit 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device, and more particularly to a device for controlling fluctuations in the feed speed of a document reading / scanning unit in the sub-scanning direction.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 5-30289 discloses a document reading / scanning unit that moves in a sub-scanning direction in a plane parallel to a document placing surface inside a document reading device, and the document reading / scanning unit is moved. A document reading apparatus is disclosed that includes a motor and a drive transmission system, and a load unit that suppresses fluctuations in the feed speed of the document reading and scanning unit when the document reading and scanning unit moves in the sub-scanning direction. According to this conventional apparatus, the feeding speed of the document reading / scanning unit can be kept stable.

[0003]

However, in the above-mentioned conventional example, in order to reduce the speed fluctuation of the motor, a complicated structure such as a magnet damper and a one-way clutch for speeding up the initial position returning operation must be used. There wasn't. Also,
The mounting is complicated, and the cost is high.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in order to suppress the speed fluctuation of the document reading / scanning unit when the document reading / scanning unit is driven in the sub-scanning direction, the document reading / scanning unit. A friction member is installed between the frame and a frame fixed to the device. In the present invention,
An anisotropic material having different load characteristics depending on the moving direction is used as the friction member. Further, in the present invention, the anisotropic material is set such that the load value in the reading direction of the document reading / scanning unit is larger than the load value in the initial position returning direction.

[0005]

According to the present invention, the friction member suppresses the speed fluctuation of the document reading and scanning unit. Further, the anisotropic material having different load characteristics depending on the moving direction suppresses the speed fluctuation of the document reading / scanning unit. Further, the anisotropic material reduces the load at the time of the initial position returning operation of the document reading / scanning unit.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic side view showing an embodiment of a document reading apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes an original reading / scanning unit that optically reads an original 3 placed on an original placing table 2 on the main body of the original reading apparatus while moving in the sub-scanning direction indicated by an arrow in the figure. A light source 4 for illuminating the original 3
Reflecting mirrors 6a, 6b, 6c for guiding the reflected light from the original 3 to the CCD image sensor 5, and the reflected light for the CCD
It is composed of an optical lens 7 for forming an image on the image sensor 5. The bearing portion 1a, which is a part of the document reading / scanning unit 1, is pivotally supported by a guide shaft 8 fixed to the main body of the apparatus, and is movable in the sub-scanning direction. A friction member 15 is attached to the bearing portion 1a, and has a structure that slides on a frame 16 attached to the apparatus body. The friction member 15 may be attached to the frame 16. Further, the pulling wire 10a is fixed to the side surface of the bearing portion 1a of the document reading / scanning unit 1.

FIG. 2 is a schematic perspective view of an embodiment of the document reading apparatus according to the present invention. In FIG. 2, the bearing portion 1a is axially supported by a guide shaft 8 fixed to the main body of the apparatus, and the other end is supported by a guide rail 9, which enables the document reading / scanning unit 1 to move in the sub-scanning direction. .
In addition, the loop-shaped pulling wire 10 is connected to the drive pulleys 11 and 3
It is relayed by individual relay pulleys 12a, 12b, 12c, and the upper pulling wire 10a (shown in FIG. 1) is fixed to the side surface of the bearing portion 1a of the document reading / scanning unit 1. Further, the drive pulley 11 rotates integrally with a belt pulley (not shown) and is connected to the motor pulley 13 via a belt (not shown). Therefore, when the stepping motor 14 rotates in the direction of arrow B in the figure, the document reading / scanning unit 1 is moved in the sub-scanning direction in FIG. 2 by the motor pulley 13, the drive pulley 11, and the pulling wire 10.

FIG. 3 is an explanatory diagram of speed fluctuations when the stepping motor rotates. As shown in FIG. 3, as a characteristic of the stepping motor 14 itself, when a signal of only one pulse is input to the stepping motor 14, the rotor of the stepping motor 14 advances by a predetermined step angle in a certain time, but the inertia of the rotor is increased. Causes an overshoot by a certain angle, continues the operation of pulling back in the opposite direction again, and stops at the theoretical angle. Actually, the input signal is input as not only one pulse but continuous pulses, but the basic movement of the rotor is the same. Therefore, the stepping motor 1
4 rotates while changing the speed.

FIG. 4 is an explanatory diagram of speed fluctuations when the document reading / scanning unit moves in the sub-scanning direction. As shown in FIG. 4, similar to the description of the operation of the rotor of the stepping motor 14 described above,
Since the document reading / scanning unit 1 itself driven by the stepping motor 14 also has inertia, even if the stepping motor 14 rotates smoothly, the moving speed of the document reading / scanning unit 1 is positive from the reference speed shown by the broken line in the figure.・ Fluctuates negatively.

In order to solve the above problems, as shown in FIG. 1, a friction member 15 made of an anisotropic material having a load characteristic depending on the moving direction is attached to the bearing portion 1a of the document reading / scanning unit 1. Has been. The friction member 15
Is always in contact with the frame 16 fixed to the main body of the apparatus, and gives a load resistance to the document reading / scanning unit 1 during scanning of the document reading / scanning unit 1.
As an example of the friction member 15 made of the anisotropic material, a recently developed rubber material is used as a base to control the dispersibility and orientation of various fibers inside (the direction in which short fibers are arranged). , Blended short fiber reinforced rubber, etc. (for example, Short Fiber Reinfor manufactured by Bando Kagaku Co., Ltd.
ced Rubber).

When the orientation of the internal fibers is arranged in the hatching direction shown in FIG. 1, the friction coefficient between the original reading scanning unit 1 and the fixed frame 16 becomes large when the original reading scanning unit 1 moves in the sub scanning direction, and conversely, after the reading is completed. During the operation of returning the original position of the document reading / scanning unit 1 (the direction opposite to the sub-scanning direction in FIG. 1), the friction coefficient becomes small. That is, while the document reading / scanning unit 1 is moving in the sub scanning direction, a constant load is applied to the document reading / scanning unit 1 to suppress the speed fluctuation due to inertia. Further, the stepping motor 14 rotates in the opposite direction to that of the stepping motor 14 so that the operation of returning the initial position of the document reading and scanning unit starts. That is, during the initial position return operation, the load is reduced,
The high speed return operation of the document reading / scanning unit 1 becomes possible.

[0012]

As described above, according to the present invention, by using the friction member made of an anisotropic material having different load characteristics depending on the moving direction, it is possible to suppress the variation of the feed speed of the document reading / scanning unit. The read image quality can be improved. Also, as a friction member,
By using an anisotropic material having different load characteristics depending on the moving direction of the document reading / scanning unit, the initial position return moving speed of the document reading / scanning unit can be set higher than that at the time of reading / scanning.

Further, since the structure for applying a load to the document reading / scanning unit is simple, the mounting is simple and the cost is low.

[Brief description of drawings]

FIG. 1 is a schematic side view of a document reading apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a document reading apparatus showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of speed fluctuations during rotation of a stepping motor.

FIG. 4 is an explanatory diagram of a speed fluctuation when the document reading scanning unit moves in a sub scanning direction.

[Explanation of symbols]

 1 Document Reading and Scanning Unit 10 Traction Wire 12a Relay Pulley 12b Relay Pulley 12c Relay Pulley 14 Stepping Motor 15 Friction Member 16 Frame

Claims (3)

[Claims] 1. A document reading / scanning unit that moves in the sub-scanning direction within a plane parallel to the document placing surface inside the document reading device, a motor and a drive transmission system for moving the document reading / scanning unit, and the document. In a document reading apparatus having a load means for suppressing a feed speed fluctuation of the document reading / scanning unit when the reading / scanning unit moves in the sub-scanning direction, the load means is a frame fixed to the document reading / scanning unit and the apparatus main body. An original reading device, which is a friction member installed between the original reading device and the document reading device. 2. The document reading device according to claim 1, wherein the friction member is an anisotropic material having different load characteristics depending on a moving direction. 3. The anisotropic material according to claim 2,
An original reading device characterized in that a value of a load in a reading direction of the original reading and scanning unit is larger than a value of a load in an initial position returning direction.