JPH06276372A - Picture reader - Google Patents

Abstract

PURPOSE:To attain accurate feeding of a carriage in the subscanning direction by using a belt so as to move the carriage. CONSTITUTION:When a drive source 13 drives a drive shaft 11, a torque of the shaft 11 is delivered to a drive roller 9 to drive a strip thin film belt 8. A carriage 5 connecting to the belt 8 to be driven is moved in the subscanning direction shown in the direction Y and reads an original 1 sequentially line by line each and picture data of the entire original 1 are obtained finally. A torque exerted to the carriage 5 is distributed uniformly in the main scanning direction by using the belt 8 to drive the carriage 5 as above. Moreover, the belt 8 restrict a play of the carriage 5 in the main scanning direction. Thus, highly accurate picture reading is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device which can read image data used in facsimiles, digital copying machines, scanners and the like.

[0002]

2. Description of the Related Art In recent years, an image reading apparatus has been used for a digital copying machine or the like, which reads an entire image by moving a carriage equipped with a linear image reading means in the sub-scanning direction.

A carriage driving mechanism of a conventional image reading apparatus will be described below. FIG. 4 is a schematic diagram of a mechanical system of a conventional image reading device, and FIG. 5 is a schematic diagram of a carriage driving mechanism of the conventional image reading device. As shown in FIG. 4, the image reading apparatus has a document placing glass 2 on which the document 1 is placed and a document cover 3 for bringing the document 1 into close contact with the document placing glass 2, and a linear image reading means for reading the document 1. It has a carriage 5 with 4. The carriage 5 is supported by the support rollers 26 and the movement thereof is restricted only in the sub-scanning direction. As shown in FIG. 5, a pair of steel wire rings 27a and 27b are connected to the carriage 5, the steel wire ring 27a is wound around a driving pulley 28a and a driven pulley 29a, and the steel wire ring 27b is driven to a driving pulley 28b and a driven pulley 28b. It is wound around the pulley 29b. The pair of drive pulleys 28a and 28b is the drive shaft 1
1 and is connected to another pair of driven pulleys 29a, 2a.
9b is connected to the driven shaft 12. A drive source 13 is connected to one end of the drive shaft 11, and steel wire rings 27a and 27b are attached to both ends of the driven shaft 12.
Pair of tension generating members 3 such as springs that give tension to the
3a and 33b are connected.

When the drive shaft 13 is rotated by the drive source 13 in the above structure, the rotation of the drive shaft 11 is transmitted to the drive pulleys 28a and 28b, and the steel wire rings 27a and 27b rotate. Therefore, the carriage 5 connected to the steel wire rings 27a and 27b moves in the sub-scanning direction shown by the Y direction in FIG. 4, and the images are sequentially read by the image reading means 4.

[0005]

However, in the above-mentioned conventional structure, when the paired drive pulleys 28a and 28b are eccentric, as shown in FIG.
A tension difference (F1-F2) is generated between a and 27b, and the tension difference fluctuates, so that the carriage 5 rotationally vibrates as shown in FIG. 7 about the Z axis shown in FIG.

Further, the carriage 5 is usually provided with guides such as the support roller 26 shown in FIG. 4 for restraining the movement in the main scanning direction. However, play or play is provided between the support roller 26 and the carriage 5. There is play, and it is difficult to restrain play of the carriage 5 in the main scanning direction with the steel wire rings 27a and 27b, and vibration easily occurs in the main scanning direction.

When the steel wire rings 27a and 27b are used to drive the carriage 5, vibration of the steel wire rings 27a and 27b in the twisting direction and springs for applying tension to the steel wire rings 27a and 27b. Since 33a and 33b have elasticity in the direction of applying tension, the carriage 5 vibrates in the sub-scanning direction as shown in FIG.

Therefore, it is difficult to accurately move the carriage 5 in the sub-scanning direction, and the accuracy of the read image data is lowered.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an image reading apparatus capable of improving the accuracy of image reading by realizing accurate feeding of the carriage in the sub-scanning direction. And

[0010]

In order to achieve the above object, the present invention provides a belt having a width substantially the same as the width of the carriage connected to the carriage in the main scanning direction, and a rotatable belt around the belt. A pair of rollers and driving means for transmitting power to the rollers to move the belt are provided.

[0011]

According to the present invention, by moving the carriage by the belt, the moving force can be uniformly distributed in the main scanning direction of the carriage and the rattling of the carriage in the main scanning direction can be restrained.

[0012]

1 (a) is a sectional view of a mechanical system of an image reading apparatus according to an embodiment of the present invention, and FIG. 1 (b) is FIG.
FIG. 2A is a sectional view taken along the line AA of the image reading device in the embodiment of the present invention shown in FIG. 2A, and FIG. 2 is a perspective view of a carriage driving portion of the image reading device in the embodiment of the present invention.

1 (a), 1 (b) and 2, the image reading apparatus includes an original placing glass 2 on which an original 1 is placed, an original cover 3 for bringing the original 1 into close contact with the original placing glass 2, and a main scan. And a carriage 5 having a line-shaped image reading unit 4 for reading the original 1 in the direction. The carriage 5 is supported by support shafts 6a and 6b and support rollers 7a and 7b, and its movement is restricted only in the sub-scanning direction.
A belt-shaped thin film belt 8 having a width substantially the same as the width of the carriage 5 in the main scanning direction is connected to the carriage 5, and the belt-shaped thin film belt 8 is wound around a driving roller 9 and a driven roller 10. The drive roller 9 of the drive roller 9 and the driven roller 10 is rotatably supported by the drive shaft 11, and the other driven roller 10 is rotatably supported by the driven shaft 12. A drive source 13 is connected to one end of the drive shaft 11, and a braking device 14 that applies a constant tension to the belt-shaped thin film belt 8 is connected to one end of the driven shaft 12. Reference numeral 15 is an outer cover.

The operation of the image reading apparatus of the present invention constructed as above will be described below.

First, the drive shaft 13 is driven by the drive source 13.
When is rotated, the rotation of the drive shaft 11 is transmitted to the drive roller 9 and the belt-shaped thin film belt 8 is rotated. By the rotation of the belt-shaped thin film belt 8, the carriage 5 connected to the belt-shaped thin film belt 8 moves in the sub-scanning direction shown by the Y direction in FIG.
Finally, the image data of the entire original 1 is obtained.

When the belt-shaped thin film belt 8 is rotated, for example, a braking device 14 such as an electromagnetic brake is used to control the exciting current of the braking device 14 to make the braking torque constant and to apply the belt-shaped thin film belt 8. The tension can be constant.

By driving the carriage 5 by the belt-shaped thin film belt 8 as described above, the driving force applied to the carriage 5 is uniformly distributed in the main scanning direction as shown in FIG. Further, the belt-shaped thin film belt 8 can restrain the carriage 5 from rattling in the main scanning direction. For this reason, the vibration and unevenness of the carriage 5 are suppressed, and highly accurate image reading becomes possible. In particular, vibrations in the X and Y directions shown in FIG. 2, rotational vibrations around the Z axis, and uneven feeding are suppressed.

Further, since the braking device 14 is connected to the driven roller 10 that winds the strip-shaped thin film belt 8 and a constant tension is constantly applied to the strip-shaped thin film belt 8, vibration and unevenness of the carriage 5 are further suppressed, and the carriage 5 can be accurately moved in the sub-scanning direction, and more highly accurate image reading can be performed.

[0019]

As described above, according to the present invention, the moving force is uniformly distributed in the main scanning direction of the carriage by moving the carriage by the belt, and the rattling of the carriage in the main scanning direction is restricted. Therefore, vibration of the carriage and uneven feeding can be suppressed, the carriage can be accurately fed in the sub-scanning direction, and highly accurate image reading can be performed.

[Brief description of drawings]

FIG. 1A is a sectional view of a mechanical system of an image reading apparatus according to an embodiment of the present invention. FIG. 1B is a sectional view taken along the line AA of the image reading apparatus according to the embodiment of the present invention shown in FIG.

FIG. 2 is a perspective view of a carriage driving unit of the image reading apparatus according to the embodiment of the present invention.

FIG. 3 is a driving force distribution diagram of the carriage of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a schematic diagram of a mechanical system of a conventional image reading device.

FIG. 5 is a schematic view of a carriage driving mechanism of a conventional image reading device.

FIG. 6 is a schematic view of vibration of a carriage of a conventional image reading device in a sub-scanning direction.

FIG. 7 is a schematic diagram of rotational vibration of a carriage of a conventional image reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 original 2 original placing glass 3 original cover 4 image reading means 5 carriage 6a, 6b support shafts 7a, 7b support roller 8 belt-shaped thin film belt 9 drive roller 10 driven roller 11 drive shaft 12 driven shaft 13 drive source 14 braking device 15 outside cover

Claims (2)

[Claims] 1. A carriage having line-shaped image reading means in the main scanning direction, a belt connected to the carriage and having a width substantially the same as the width of the carriage in the main scanning direction, and the belt is wound. An image reading apparatus comprising: a pair of rotatable rollers; and a driving unit that transmits power to the rollers to move a belt. 2. The image reading apparatus according to claim 1, further comprising braking means for transmitting power from a driving means to one of the pair of rollers and braking rotation of the other roller.