JPH08201928A - Image reader - Google Patents

Abstract

(57) [Summary] [Purpose] To stabilize the carriage movement speed in a short section. [Structure] Friction resistance between a scanner rail 4 and a shoe 6 of a carriage 5 is determined by an image reading standby position H of the carriage 5.
The section from P to the image reading start position LE is made larger than the other sections to eliminate the forced vibration after reaching the target speed of the carriage 5 in a short section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to shortening the acceleration distance of an illuminating device for illuminating a document.

[0002]

2. Description of the Related Art In an image reading apparatus which moves on a scanner rail while sliding a shoe which is a contact body of a carriage on which an illuminating device is mounted, a carriage on which an illuminating device for scanning an original is mounted is accelerated in a short section. After that, it is moving at a constant speed.

Conventionally, in such an image reading apparatus, in order to reduce the fluctuation of the speed of the carriage, the frictional resistance between the carriage and the scanner rail for mounting and guiding the carriage has been reduced. However, due to the elasticity of the wires that transmit the driving force to the carriage when the drive of the carriage rises, forcible vibration occurs after the target speed is reached by rapid acceleration, and the frictional resistance between the scanner rail and the carriage increases. If it is small, the vibration damping characteristics deteriorate, and the acceleration distance of the carriage becomes long.

On the other hand, in the document scanning device in the copying machine disclosed in Japanese Patent Laid-Open No. 64-66677, a damper is attached to the reciprocating part of the illuminating device so that the damper moves relative to the reciprocating part. Further, the vibration damping effect is enhanced by mounting the reciprocating unit so that the resonance frequency is different from the vibration frequency of the reciprocating unit.

Further, in the image forming apparatus disclosed in Japanese Utility Model Laid-Open No. 4-27452, a roller having a one-way clutch is attached to a portion where a carriage on which an illuminating device is placed and a scanner rail are in contact with each other, and a carriage and a scanner are used during image scanning. By increasing the frictional resistance between the rail and the rail, the lighting device travels at a stable speed.

[0006]

However, a machine provided with an image reading device such as a copying machine and an image scanner is required to be downsized, and the original scanning device in the copying machine has a complicated structure and the number of parts is increased. Therefore, it is not suitable for miniaturization.

Further, in the image forming apparatus, since the frictional resistance between the carriage and the scanner rail is large, a strong driving device is required to accelerate the carriage, and the acceleration distance of the carriage becomes long.

The present invention has been made to solve the above disadvantages, and the effect of damping forced vibration after reaching the target speed by increasing the frictional resistance in the section from the start of acceleration of the carriage to the start of image reading is provided. The purpose is to accelerate and stabilize the carriage in a short section.

[0009]

SUMMARY OF THE INVENTION An image reading apparatus according to the present invention has a frictional resistance between a scanner rail and a shoe of a carriage which is different from that of the carriage between the image reading standby position and the image reading start position. It was made larger than the section.

Further, the image reading apparatus may increase the frictional resistance between the scanner rail and the shoe of the carriage in the section from the acceleration end position of the carriage to the image reading start position as compared with other sections. .

Further, it is desirable to change the frictional resistance only between the shoe of the first carriage provided with the illuminating device and the reflecting mirror and the scanner rail depending on the section.

Further, it is preferable that the frictional resistance between the scanner rail and the shoe of the carriage is gradually changed.

[0013]

According to the present invention, the frictional resistance between the shoe of the carriage having the exposure optical system and the scanner rail is
The interval from the image reading standby position to the image reading start position of the carriage is made larger than the other intervals to eliminate the forced vibration after the carriage reaches the target speed in a short interval.

Further, the frictional resistance between the shoe of the carriage having the exposure optical system and the scanner rail is increased in the section from the acceleration end position of the carriage to the image reading start position as compared with other sections, Accelerate the carriage over a short distance.

Further, the frictional resistance only between the shoe of the first carriage provided with the illuminating device and the reflecting mirror and the scanner rail is changed depending on the section, and the forced vibration after the target speed of the first carriage is reached with a simple structure. To be a short section.

Further, the frictional resistance between the scanner rail and the shoe of the carriage is gradually changed to reduce the reaction due to the abrupt increase of the frictional resistance.

[0017]

1 is a side sectional view showing the construction of an embodiment of the present invention. The image reading device irradiates a document placed on the document stacking table 1 with the illumination device 2, reads the light reflected by the document by the image forming device 3, and reads the document on the document stacking table 1. The image reading device includes a lighting device 2 and a first reflecting mirror 5.
It has a first carriage 5a on which the carriage 1 is mounted and travels on the scanner rail 4, and a second carriage 5b which mounts the second reflecting mirror and the third reflecting mirror and travels on the scanner rail 4. As shown in the side sectional view of FIG. 2, the illumination device 2 moves along with the first carriage 5a along the document stacking table 1 to scan the document. A document 8 placed on the document stacking table 1 from the illumination device 2
The light irradiating the laser beam is reflected by the original 8 and the first carriage 5a
Reflected by the first reflecting mirror 51 of the second carriage 5b
After being reflected by the reflected light 52 and the third reflecting mirror 53 and reversing the direction thereof, the reflected light 52 is reflected by the fourth reflecting mirror 9 and then the imaging device 3
Sent to Here, in order to keep the optical path length of the light reflected on the original 8 constant, the second carriage 5b on which the second reflecting mirror 52 and the third reflecting mirror 53 for reversing the optical path are placed is the illumination device 2 and the first. The first carriage 5a on which the reflecting mirror 51 is mounted travels at a half speed and a half distance.

The first carriage 5a is provided with a shoe 6 which is a contact body with the scanner rail 4 so as to slide on the scanner rail 4 at a contact portion with the scanner rail 4. First
The shoes 6 of the carriage 5a are provided on the left and right of the first carriage 5a, for example, as shown in FIG. in this way,
Since there are few portions where the shoe 6 and the scanner rail 4 contact each other, it is possible to reduce the frictional resistance between the first carriage 5a and the scanner rail. First with shoe 6
The carriage 5a travels on the scanner rail 4 by a driving force from a driving device (not shown) having, for example, a servo motor that generates the driving force of the first carriage 5a and a wire that transmits the driving force from the servo motor. Further, since the shoe 6 and the scanner rail 4 are not in contact with each other at a small portion, a portion of the surface of the scanner rail 4 where the frictional resistance value is increased is reduced and the processing is facilitated, so that the manufacturing cost can be reduced. The surface of the scanner rail 4 is processed so that the frictional resistance value is large in the section from the image reading standby position HP of the first carriage 5a to the image reading start position LE and is small in the other sections. . Here, since the second carriage 5b travels at a speed half that of the first carriage 5a during image reading, the vibration of the first carriage 5a with respect to the target speed at the time of rising is contracted until the vibration at the time of rising contracts. Less time to do. For this reason, the scanner rail 4 changes the frictional resistance value only with respect to the shoe 6 of the first carriage 5a so that the contraction time of the vibration with respect to the target speed when the first carriage 5a rises is shortened. Since the frictional resistance value of the scanner rail 4 is changed only with respect to the shoe 6 of the first carriage 5a, the scanner rail 4 on which the first carriage 5a runs and the second
Even when the carriage rail on which the carriage 5b travels is different, it is not necessary to process the scanner rail on which the second carriage 5b travels, and manufacturing and maintenance costs can be reduced.

The operation of the image reading apparatus having the above-described structure when reading an original will be described with reference to the process chart of FIG. 4 and the speed transition chart of FIG.

The first carriage 5a is at the image reading standby position HP on the scanner rail 4 as shown in FIG. When an instruction to start reading a document is input, the driving device transmits a driving force to the first carriage 5a so as to move at the image reading speed. The first carriage 5a is driven by the driving force from the driving device, so that the section A in FIG.
The moving speed is rapidly accelerated as shown in. When the moving speed of the first carriage 5a reaches the image reading speed, the driving device transmits the driving force to the first carriage so as to move at the image reading speed. Therefore, the wire for transmitting the driving force to the first carriage 5a, etc. Due to the elasticity of the, the forced vibration occurs after the moving speed of the first carriage 5a reaches the image reading speed. Here, since the frictional resistance between the shoe 6 of the first carriage 5a and the scanner rail 4 is large,
As shown in section B of FIG. 5, the vibration of the moving speed of the first carriage 5a is rapidly attenuated, and the moving speed of the first carriage 5a becomes constant. The position at which the moving speed of the first carriage 5a is constant is the image reading start position LE shown in FIG. 4B, but the shoe 6 and the scanner rail of the first carriage 5a shown by the dotted line in FIG. It is faster than when the frictional resistance with 4 is small. Therefore, when the frictional resistance between the shoe 6 of the first carriage 5a and the scanner rail 4 is large, the illumination device is smaller than when the frictional resistance between the shoe 6 of the first carriage 5a and the scanner rail 4 is small. The distance until the moving speed of the first carriage 5a on which the sheet 2 is placed reaches a stable image reading speed is short and the time is fast. Therefore, the scanner rail 4 can be shortened, and the image reading apparatus can be downsized.

After the image reading start position LE shown in FIG. 4 (c), the frictional resistance of the scanner rail 4 becomes small.
The first carriage 5a on which the illuminating device 2 is mounted travels at a stable speed as shown in the section C of FIG. 5, and the illuminating device 2 scans the document on the document stacking table 1.

In the above embodiment, the first carriage 5a
Although only the frictional resistance between the shoe 6 and the scanner rail 4 is increased, the frictional resistance between the shoe of the second carriage 5b and the scanner rail 4 may be increased. Accordingly, even when the traveling speed of the second carriage 5b is high, the forced vibration after the target speed of the second carriage 5b is reached can be prevented.

Further, the frictional resistance value of the scanner rail 4 is
It may be increased in the section from the acceleration end position D of the first carriage 5a to the image reading start position LE shown in the upper sectional view of FIG. As a result, the image reading standby position HP
It is possible to shorten the traveling distance required to accelerate the moving speed of the first carriage 5a stopped at to the image reading speed.

Further, the frictional resistance value in the section 7 in which the frictional resistance of the scanner rail 4 is large may not be abruptly changed, but may be gently changed as shown in FIG. As a result, the frictional resistance between the shoe 6 of the first carriage 5a and the scanner rail 4 suddenly increases and the forced vibration after the target speed of the first carriage 5a is reached can be prevented.

Further, in the above embodiment, the first carriage 5
Although the shoes 6 are provided on the left and right of the a, but when the shoes 6 are provided on the front, back, left, and right of the first carriage 5a, the shoes 6 on the front and rear of the first carriage 5a are arranged on the scanner rail 4 as shown in the upper sectional view of FIG. The positions of the shoes 6 in the front and rear of the first carriage 5a may be shifted to the left and right so as not to pass through the same place. Since the front and rear shoes 6 do not pass through the same portion of the scanner rail 4, it is possible to set the section 7 where the friction resistance of the scanner rail 4 is large according to the movement section of the front and rear shoes 6, and the front and rear shoes 6 simultaneously provide a large friction resistance. I will receive it.

Further, the original of the first carriage 5a is placed on the surface of the scanner rail 4 so that the frictional resistance value becomes large in a specific section when the first carriage 5a moves forward, and becomes small in the preceding section when the carriage returns. The friction resistance may be changed by providing a groove facing the reading standby position.

In the above embodiment, the frictional resistance value of the surface of the scanner rail 4 is increased in a specific section, and the frictional resistance between the first carriage 5a and the scanner rail 4 is increased in a specific section. A roller with a brake is provided between the first carriage 5a and the scanner rail 4 in place of the shoe 6, and the brake is loosely applied in a specific section, so that the friction resistance between the first carriage 5a and the scanner rail 4 is increased. May be increased in a specific section.

[0028]

As described above, the present invention compares the frictional resistance between the scanner rail and the shoe of the carriage in the section from the image reading standby position of the carriage to the image reading start position with other sections. Therefore, the forced vibration after accelerating the carriage and reaching the target speed of the carriage can be eliminated in a short section.

Further, since the frictional resistance between the scanner rail and the shoe of the carriage is increased in the section from the acceleration end position of the carriage to the image reading start position as compared with the other sections, the target speed of the carriage is set. The forced vibration after reaching can be eliminated in a short section, and the carriage can be accelerated in a short distance.

Furthermore, since the frictional resistance only between the shoe of the first carriage, which has the illuminating device and the reflecting mirror and has a high moving speed, and the scanner rail is changed depending on the section, after reaching the target speed of the carriage with a simple structure. The forced vibration of can be eliminated in a short section.

Further, since the frictional resistance between the scanner rail and the shoe of the carriage is gradually changed to reduce the reaction due to the sudden increase of the frictional resistance, the carriage generated by the rapid change of the frictional resistance. The forced vibration after reaching the target speed can be prevented.

Further, since the carriage can be accelerated over a short distance as described above, the apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the image reading device showing an optical path of light reflected from a document.

FIG. 3 is a top cross-sectional view of the image reading device showing the position of the shoe.

FIG. 4 is a process diagram showing an operation when scanning a document.

FIG. 5 is a velocity transition diagram showing a velocity of a carriage when scanning a document.

FIG. 6 is a top cross-sectional view of the image reading apparatus in which the frictional resistance value is increased from the acceleration end position.

FIG. 7 is a plan view of the scanner rail when the frictional resistance value is gradually reduced.

FIG. 8 is a top cross-sectional view of the image reading apparatus when the shoes are provided on the front, rear, left, and right.

[Explanation of symbols]

 D Acceleration end position HP Image reading standby position LP Image reading start position 1 Document stacking table 2 Illumination device 3 Imaging device 4 Scanner rail 5a First carriage 5b Second carriage 6 Shoe

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[Procedure amendment]

[Submission date] April 5, 1995

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[Figure 8]

Claims (4)

[Claims] 1. An image reading apparatus that scans by moving a shoe, which is a contact body of a carriage having an exposure optical system, on a scanner rail while sliding the shoe, and detects the frictional resistance between the scanner rail and the shoe of the carriage. An image reading apparatus characterized in that a section from a reading standby position to an image reading start position is made larger than a section other than the section. 2. In an image reading apparatus which scans while moving a shoe, which is a contact body of a carriage having an exposure optical system, on a scanner rail, the friction resistance between the scanner rail and the shoe of the carriage is accelerated in the image reading apparatus. An image reading apparatus characterized in that the section from the end position to the image reading start position is made larger than the other sections. 3. The image reading apparatus according to claim 1, wherein the frictional resistance only between the shoe of the first carriage provided with the illuminating device and the reflecting mirror and the scanner rail is changed depending on the section. 4. The frictional resistance between the scanner rail and the shoe of the carriage is gradually changed.
The image reading device described.