JPH0895167A - Image reader - Google Patents

Abstract

PURPOSE: To provide an image reader improved in image quality and reduced in a cost without requiring the high accuracy of parts, and assembling accuracy by always maintaining a wire in parallel with a subscanning direction and preventing the occurrence of the component of force. CONSTITUTION: In the image reader provided with scanners 11 and 12 for reading an original set at a fixed position while moving, a wire rope 15 for moving the scanners 11 and 12 and a pulley 17 on which the wire rope 15 is wound, the pulley 17 is made to be movable in an orthogonal direction with the subscanning direction so as to make the wire rope 15, stretched between plural pulleys 14 and 17 arranged along the subscanning direction at attitude in parallel with the subscanning direction, so that the straightening operation of the wire rope 15 is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an image reading apparatus used as an input means of a copying machine, a printer, a facsimile, or an image forming apparatus having a combination of these functions. The present invention relates to improvement of a moving mechanism of a scanning scanner.

[0002]

2. Description of the Related Art An image forming apparatus utilizing an electrophotographic process, such as a copying machine, a printer, a facsimile machine, etc., is equipped with an image reading device as an image information input means. An image reading device (image scanner) having no image forming unit is also known. The image reading apparatus includes a first scanner having a light source, a reflector and a first mirror, and a second scanner having second and third mirrors for guiding the reflected light of the document to a photoconductor, a CCD or the like. , Each scanner is engaged with a wire rope driven by a motor and driven in the sub-scanning direction. The wire rope is stretched by a pulley, and as the pulley, a drive pulley directly connected to the output shaft of the motor, an idle pulley rotatably supported by the main frame of the apparatus, and further rotatably supported by the carriage of the scanner. There is a carriage pulley. When driving the scanner in the sub-scanning direction, it is necessary that the pulleys are parallel to each other in the sub-scanning direction, and as a result, the wire rope between the pulleys arranged in the sub-scanning direction is parallel to the sub-scanning direction. is there. When the wire rope is tilted from the sub-scanning direction, the stability of the running of the scanner is lost, and fluctuations in magnification, image distortion, image jitter, etc. occur.

That is, FIG. 5 is a schematic diagram showing the structure of a conventional flat bed type image reading device (image input device), in which a light source 3 is placed on an original 2 fixed on a contact glass 1.
From the CCD, the reflected light of the original is reflected by the mirrors 4, 5 and 6 and folded back, condensed by the lens 7, and then the CCD.
The image is formed at 8, and photoelectrically converted by the CCD 8. The light source 3 and the first mirror 4 constitute a first scanner 11 which is mounted on one carriage and independently advances and retracts in the sub-scanning direction, and the second and third mirrors 5 and 6 are arranged on another carriage. The second scanner 12 which is mounted and independently moves back and forth in the sub-scanning direction.
Make up. FIG. 6 is a perspective view of the image reading apparatus, and the driving mechanism for driving each scanner is a motor 13
A drive pulley 14 driven by a motor 13, a carriage pulley 16 rotatably supported on the carriage side surface of the second scanner 12, an idle pulley 17 rotatably supported by the apparatus body, and these pulleys 16 1
Wire rope 15 wound around 7 to transmit driving force
Have and.

As shown in FIGS. 7 (a) and 7 (b), in the conventional apparatus, the wire rope portion between the drive pulley 14 and the first scanner 11 and the portion between the drive pulley 14 and the idle pulley 17 are provided. The wire rope or the wire rope 15 between the idle pulley 17 and the second scanner 12 (second carriage pulley 16B) cannot always maintain the posture parallel to the sub-scanning direction. The reason is that each pulley 1
This is because the distance between the scanners 4 and 17 and the scanners 11 and 12 changes due to the movement of the scanners 11 and 12, and the tilt angle of each wire portion changes accordingly. That is, as shown in FIGS. 8A and 8B, the second scanner pulley 16
The distance from the idle pulley 17 is different when the position B is at the solid line position and when it is at the two-dot chain line position, and as a result, the inclination angle of the wire portion 15b changes, and the distance with respect to the sub-scanning direction. The situation that is not parallel occurs. When the wire rope is tilted from the state parallel to the sub-scanning direction, as shown in the figure, in addition to the pulling forces F and F ′ along the wire rope at the pulley 16B portion,
A component force f ₂ (f ₂ ') in the main scanning direction is generated. Also,
Also in the wire rope portion wound around the idle pulley 17, a component force f ₂ ″ in the main scanning direction is generated in addition to the original force F ″ along the wire. These component forces f ₂ (f ₂
', F ₂ ″) is a force that displaces the scanners 11 and 12 in the main scanning direction, and causes fluctuations in the moving speed in the sub-scanning direction and displacement in the main scanning direction.

In order to solve such a problem, Japanese Utility Model Laid-Open No. 62-51334 discloses a structure using a retaining ring as a method for preventing the carriage pulley from coming off.
This conventional example cannot prevent the inclination of the wire, which is a problem to be solved by the present invention. Further, Japanese Utility Model Laid-Open No. 63-4540 does not disclose a space in which the idle pulley and the carriage pulley can be moved in the lateral direction, so it is clear that the wire does not have a function of correcting the posture of the wire. is there.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the wire rope is always maintained parallel to the sub-scanning direction without an increase in the number of parts and a high degree of accuracy in parts and assembly. It is an object of the present invention to provide an image reading device that improves image quality and reduces cost. That is, the present invention
By configuring the idle pulley so that it can move in the axial direction, the tension that tends to make the wire rope parallel to the sub-scanning direction is used, and the positional relationship between the drive pulley, carriage pulley, and idle pulley is always in a straight line. It is possible to drive with high accuracy at a fixed cost. In addition, since the idle pulley can be moved in the axial direction, there is a problem that the pulley will come off, but since a bolt having a large diameter portion is used as the shaft member of the idle pulley,
It can be prevented from falling off. Furthermore, if the carriage pulley is also configured to be movable in the lateral direction, there is a risk that the carriage pulley will fall off the shaft due to vibration or shock, but the wire tension should be set high and the shaft length should be long. By doing so, the problem can be solved.

[0007]

To achieve the above object, the present invention comprises a scanner for reading a document set at a fixed position while moving it, a wire rope for moving the scanner, and a pulley for winding the wire rope. In the image reading apparatus, in order to make the wire rope stretched between the plurality of pulleys arranged along the sub-scanning direction parallel to the sub-scanning direction, the pulleys are moved in the direction orthogonal to the sub-scanning direction. It is configured to be movable so as to exert a straightening effect on the wire rope. The pulley is composed of a drive pulley and an idle pulley that do not move and a carriage pulley that moves when mounted on the scanner. The freely supporting shaft is bolt-shaped, and the large-diameter head of the bolt-shaped shaft prevents the pulley from falling off. The pulley is composed of a stationary drive pulley, a movable idle pulley, and a carriage pulley that is mounted on the scanner and moves, and has a long axial dimension of a shaft that supports the shaft center of the carriage pulley in a floating manner. And the tension of the wire rope stretched between the carriage pulley and other pulleys is set to a high value to prevent the carriage pulley from falling off the shaft. .

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 1 (a) and 1 (b) are a plan view and a front view for explaining the principle of an image reading apparatus according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are configurations of a shaft portion of an idle pulley of the present invention. It is explanatory drawing and the figure which shows the fault of the prior art example. In addition,
Referring to FIGS. 5 and 6 together, the same parts are designated by the same reference numerals for description. The first scanner 11 (first traveling body) is fixed to a proper position 15A of the wire rope 15, and the first scanner 11 (first traveling body) is connected to the first scanner by a first carriage pulley 16A pivotally supported on the side surface of the second scanner 12 (second traveling body). The wire rope extending rearward from the fixed portion 15A is inverted into a U shape, and the tip portion 15B is fixed to the apparatus main body side. The other end of the wire rope 15 is wound around the idle pulley 17 and then inverted by the second carriage pulley 16B so that the tip end 15C is supported by the reading device main body via a spring or the like. As a result, the second scanner 12 is translated in the same direction at a speed half that of the first scanner 11, for example. In this embodiment, the idle pulley 17 and / or the carriage pulley 16 (16A, 16B) are supported so as to be able to advance and retreat in the axial direction (thrust direction = main scanning direction), so that the scanners 11 and 12 move and the pulleys are moved. Even if the distance between the pulleys changes, the pulleys that are adjacent to each other in the sub-scanning direction are arranged in parallel in the sub-scanning direction due to the original shape restoring force of the wire rope 15. It is designed so that a posture parallel to can always be maintained.

FIG. 2 (a) shows an example of the structure for supporting the idle pulley 17 so as to be capable of advancing and retracting in the axial direction. The shaft 21 for rotatably supporting the idle pulley has a bolt shape, and the shaft 21 The screw portion 21a at the tip is screwed into the screw hole 25a of the side plate 25, and the bolt-shaped shaft 2
The large-diameter head 21a of No. 1 prevents the pulley from falling off. As a result, the pulley 17 can be moved by the axial length L. FIG. 2 (b) is a conventional configuration diagram. In the related art, the pulley 17 inserted into the shaft 26 is attached to the E retaining ring 2
Since it was prevented from coming off by 0, the axial movement of the pulley 17 was prohibited, and as a result, the above-mentioned trouble occurred.

Next, FIGS. 3 (a) and 3 (b) are a front view and a vertical sectional view showing the bearing structure of the idle pulley 17 and the shaft 21, and allow the idle pulley 17 to move in the axial direction with respect to the shaft 21. Therefore, the bearing 27 is attached to the inner diameter of the pulley 17 and is separated from the shaft 21. That is, the bearing 27 has a structure in which the ball 27c is rotatably supported between the outer member 27a and the inner member 27b.
If the inner member 27b is fixed to the shaft 21 as in the conventional case, the pulley 17 cannot move in the axial direction.
Is provided on the pulley side. FIG. 3C shows another example, in which the ball bearing 27 is replaced by a thrust bearing 28.
A characteristic is that the shaft 21 is supported by a clearance fit using.

FIGS. 4 (a), 4 (b) and 4 (c) are a plan view and a magnified view of an essential part showing the operation of the carriage pulley. The carriage pulley 16 (16A, 1A, 1 supported by the second scanner 12
6B) is configured to be movable in the axial direction with respect to the shaft 22, but since the E-ring is not used, the pulley 16 may fall off the shaft 22. However, in the present invention, the tension of the wire rope 15 is set high (strong),
Moreover, since the axial length of the shaft 22 is set to be long, it is possible to reliably prevent the shaft 22 from falling off due to the wire tension. The length of the shaft 22 may be determined by the weight of the second scanner 12 and the impact value, and the movement distance l (ell) may be increased according to the increase of the value. As described above, according to the present invention, the movement of the scanner is prevented by maintaining the wire in parallel with the sub-scanning direction and preventing the above-mentioned component force from occurring, without requiring a high degree of component accuracy and assembly accuracy. It is possible to prevent fluctuations in speed, positional deviations in the main scanning direction, and deterioration in image quality due to these deviations.

[0012]

As described above, according to the present invention, the positional relationship among the drive pulley, the idle pulley, and the carriage pulley arranged in the main scanning direction is automatically aligned by the wire tension so that the wire is sub-scanned. Since it is parallel to the direction, the movement of the scanner will be smooth,
The influence on the read image is reduced. Further, the shaft for preventing the idler pulley from slipping off is formed in a bolt shape so that the shaft also serves as the shaft. Therefore, the number of parts can be reduced, the assemblability can be improved, and the cost can be reduced. Furthermore, the carriage pulley vibrates without the use of a special slip-out prevention member,
Since it does not fall off the shaft due to impact, the structure can be simplified and the cost can be reduced.

[Brief description of drawings]

1A and 1B are explanatory views showing the principle of an image reading apparatus according to an embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a front view.

2A and 2B are an exploded perspective view showing a support structure of an idle pulley according to the present invention, and a view showing a conventional support structure.

3 (a) and 3 (b) are a front view and a vertical sectional view showing an assembled state when a ball bearing is incorporated on the idle pulley side, and FIG. 3 (c) is a sectional view when a thrust bearing is incorporated.

4 (a), (b) and (c) are a plan view showing an operation of a carriage pulley and an enlarged view of a main part.

FIG. 5 is a schematic diagram showing a configuration of a conventional flat bed type image reading device (image input device).

FIG. 6 is a perspective view showing the overall configuration of a conventional reading device.

7 (a) and (b) are views showing a conventional defect.

8 (a) and 8 (b) are diagrams for explaining the defect shown in FIG. 7 in detail.

[Explanation of symbols]

1 contact glass, 2 originals, 3 light sources, 4, 5,
6 mirror, 7 lens, 8 CCD, 11 first scanner, 12 second scanner, 13 motor, 14 drive pulley, 15 wire rope, 15 carriage pulley,
15A, 15B carriage pulley, 17 idle pulley, 20 E ring, 21 bolt, 21a screw part,
21b Large diameter part, 25 Side plate.

Claims (3)

[Claims] 1. An image reading apparatus comprising a scanner for reading a document set at a fixed position while moving it, a wire rope for moving the scanner, and a pulley for winding the wire rope, in an auxiliary scanning direction. In order to make the wire rope stretched between a plurality of pulleys arranged in parallel with each other in the posture parallel to the sub-scanning direction, the pulley can be moved in the direction orthogonal to the sub-scanning direction, and the wire rope correction effect is exhibited. An image reading device characterized in that 2. The pulley comprises a drive pulley that does not move and a movable idle pulley, and a carriage pulley that is mounted on the scanner and moves, and a shaft that rotatably supports the idle pulley has a bolt shape. 2. An image reading apparatus according to claim 1, wherein the head portion having a large diameter of the bolt-shaped shaft is configured to prevent the pulley from falling off. 3. The shaft comprises a drive pulley that does not move and a movable idle pulley, and a carriage pulley that is mounted on the scanner and moves, and a shaft that axially supports the shaft center of the carriage pulley. By preventing the carriage pulley from falling off the shaft, the direction dimension is set to be long and the tension of the wire rope stretched between the carriage pulley and other pulleys is set to be high. The image reading apparatus according to claim 1, wherein: