JPH10301214A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb vibration and shock in the case of starting the scanning of a scanner when the scanner is on a home position and in the case of stopping the scanning of the scanner at a low cost without lowering scanning performance due to environment and the lapse of time by adding inexpensive parts. SOLUTION: This image reader reads the image of an original on an original platen by radiating light to the image of the original and using a first scanner 3 performing scanning at a first speed and a second scanner 5 performing scanning at a second speed which is lower than the first speed. In this case, a guide member 7 is provided so that the one end part of the scanner 3 and the one end part of the scanner 5 are supported and guided in a scanning direction, and also an elastic body 31 is arranged on the one end part of the scanner 5, brought into elastically contact with the one end part of the scanner 3 when the one end part of the scanner 3 and the one end part of the scanner 5 are positioned on the home position HP. Thus, the body 31 can absorb the vibration and the shock at the low cost in the case of the startup for performing the scanning of the scanner when the scanner is on the home position, and in the case of stopping the scanning of the scanner.

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 such as a copying machine and a scanner, and more particularly, to a first scanner and a first scanner which scan light at a first speed by irradiating an image of a document on a document table with light. The present invention relates to an image reading apparatus that reads an image on a document using a second scanner that scans at a second speed lower than one speed.

[0002]

2. Description of the Related Art A so-called original platen fixed type image reading apparatus for performing copying, such as a copying machine or a scanner, has the following structure. In the image reading apparatus, a guide rod is arranged below the glass plate of the platen so as to be parallel to the glass plate. One end of the first scanner and one end of the second scanner can slide on the guide rod. Attached to. The first scanner and the second scanner are reciprocally scanned in parallel to the glass plate along the guide rod, so that the optical image of the image of the original placed on the glass of the original platen is transferred to the photosensitive drum through the lens. Irradiate on top.

[0003] The drive system of this type of image reading apparatus is called a one-side drive system of a scanner, and a wire or a toothed belt (timing belt) is arranged near a guide rod to form a wire or a tooth. By fixing the attached belt to one end of the scanner and operating the wire or the toothed belt, the one end of the first scanner and the one end of the second scanner are moved along the guide rod to copy the contents of the original on the platen. Reciprocating scanning is performed to read.

[0004] Such a one-sided driving system of the scanner requires only half the space for disposing the driving system as compared with the system for driving both ends of the scanner, so that the size of the image reading apparatus can be reduced and a wire or toothed belt can be used. There is an advantage that the arrangement can be simplified.

[0005]

However, such a one-side driving system of the scanner has the following structural problems. That is, when one end of the first scanner and one end of the second scanner are at the home position of the guide rod, vibrations and impacts are likely to occur when starting the scanning of the scanner or when stopping the scanning of the scanner. This amplifies the vibration at the free end of the first scanner and the free end of the second scanner, so that image quality is degraded when reading an image.

More specifically, the clearance between the diameter of a guide rod (bearing) and the inner diameter of a slide member, which is a slider that moves along the guide rod, is very large in scanning by a scanner. This is an important factor, and if too much clearance is taken, vibration at the time of starting the scanner will be amplified, and the driven side (free end) will vibrate, thus deteriorating the quality particularly at the leading end of the image. Conversely, when the clearance is reduced, the sliding resistance between the slide member and the guide rod increases, so that the scanner is locked and the quality of the image is partially or wholly deteriorated. The scanner may not be able to scan.

In consideration of the operating environment of the machine, the difference between the maximum temperature and the minimum temperature is not only about 40 ° C.
Since the scanner is equipped with an exposure lamp (not shown), especially the bearings of the slider of the first scanner are more heated and have a considerable thermal expansion. For example, if the material of the bearing of the slider is POM (polyacetal) and the inner diameter is 16 mm, when calculating the heat shrinkage and expansion,

[0008]

(Equation 1)

[0009] Under the environment of 10 ° C,
When the slider shrinks by 0.024 mm and the slider temperature reaches 60 ° C., it expands by +0.056 mm (provided that the thermal expansion at room temperature is zero).

FIG. 6 shows the vibration at the time of starting the scanner at the free end of the first scanner when the clearance has not increased with respect to the room temperature. On the other hand, +0.05
FIG. 7 shows the vibration at the time of starting the scanner at the free end of the first scanner when the mm clearance is increased. FIG.
7 and FIG. 7, as the clearance increases, the vibration at the time of starting the scanner at the free end of the first scanner increases considerably.

As described above, it is difficult to set a clearance between the inner diameter of the slider of the scanner and the diameter of the guide rod.
In addition, it is necessary to select a material having a small thermal expansion for the material. As a result, conventionally, it is necessary to manufacture the scanner, the slider, and the guide rod with high-precision dimensions by using expensive materials. Scanning performance decreases,
This has been a factor in deteriorating image quality.

In Japanese Utility Model Publication No. Hei 6-33463, in order to absorb the impact when the two slide members are stopped,
It is disclosed that a shock absorber using gas is provided at a contact portion between two slide members. However, high costs are unavoidable due to gas encapsulation. In Japanese Patent Application Laid-Open No. 56-39564, an elastic member is provided on the side of the first mirror to attenuate the vibration of the first mirror, and this elastic member contacts a receiving member arranged on the inner surface of the contact glass. It comes into contact.

Accordingly, the present invention solves the above-mentioned problems, and does not reduce the scanning performance over time and the environment by adding inexpensive parts. It is an object of the present invention to provide an image reading apparatus capable of absorbing vibration and impact at low cost when scanning is stopped.

[0014]

According to a first aspect of the present invention, a first scanner which scans at a first speed and a second scanner which is slower than the first speed are provided by irradiating light on an image of a document on a document table. A guide member for supporting one end of the first scanner and one end of the second scanner to guide in the scanning direction in an image reading apparatus that reads an image of a document using a second scanner scanned at a speed; An elastic body disposed at one end of the second scanner and elastically contacting one end of the first scanner when one end of the first scanner and one end of the second scanner are located at the home position; It is characterized by having.

According to the first aspect of the present invention, by adding inexpensive parts, the scanning performance is not degraded even in the environment or over time. When the scanning is stopped, vibration and impact can be absorbed at low cost.

According to a second aspect of the present invention, in the first aspect, the elastic body is formed by attaching a film to a surface of a foam.

According to a third aspect of the present invention, in the first aspect, the elastic foam is a foamed polyurethane and the film is a polyester film.

According to the second and third aspects of the present invention, the use durability of the foam can be improved by attaching the film to the foam.

According to a fourth aspect of the present invention, in the first aspect, the elastic body is a leaf spring.

According to the fourth aspect of the invention, the use durability can be further improved.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an image reading apparatus of the present invention, and FIG.
It is sectional drawing in a line. The image reading apparatus shown in FIGS. 1 and 2 is a copying machine, and has an optical unit 1 of a so-called one-side belt drive system.

The optical unit 1 of the one-side belt drive system comprises:
It has a first scanner 3, a second scanner 5, a guide rod 7 as a guide member, an optical unit frame 9, and the like. The guide rod 7 is arranged in the optical unit frame 9 in the X direction.

As shown in FIGS. 1 and 2, a slide member 11 is provided at one end of the first scanner 3, and a slide member 13 is provided at one end of the second scanner 5. A guide rod 7 passes through these slide members 11 and 13.

The slide member 11 of the first scanner 3 has a mounting member 15, which is fixed to a timing belt 17. Timing belt 1
Reference numeral 7 is attached to the pulleys 19 and 21 so that the pulleys are driven by an electric motor. The first scanner 3 has a light source that irradiates light on an image of a document.

Similarly, the slide member 1 of the second scanner 5
3 is provided with a mounting member 20;
Is fixed to the timing belt 23. The timing belt 23 is hung on pulleys 25 and 27. These timing belts 17 and 23 are located near the guide rod 7.

Thus, by driving the motor, the first scanner 3 can reciprocally scan the guide rod 7 at the first speed V along the X direction. The second scanner 5 can perform reciprocating scanning with the guide rod 7 at the second speed V / 2 along the X direction. When the light from the light source of the first scanner 3 is reflected by the original, the reflected light is received by the mirror of the first scanner 3 and inverted by the mirror of the second scanner 5, and the reflected light is transmitted to the photosensitive drum via the lens. Irradiated.

The slide member 13 of the second scanner 5 has a substantially U-shape when viewed in a longitudinal section as shown in FIG. As shown in FIG. 2, when the first scanner 3 and the second scanner 5 are at the home position HP, the slide member 11 of the first scanner 3 can be positioned within the slide member 13 of the second scanner 5. The slide member 13 of the second scanner 5 and the slide member 11 of the first scanner 3
It is arranged coaxially by a guide rod 7.

Elastic bodies 31, 31 are arranged in the slide member 13 of the second scanner 5. This elastic body 3
1, as shown in FIG. 1, when the first scanner 3 and the second scanner 5 are located at the home position HP, the first scanner 3 elastically contacts and holds the outer peripheral surface of the slide member 11 of the first scanner 3. . The elastic body 31 includes, as shown in FIG. 3, a rectangular parallelepiped foam body 33 such as polyurethane foam, for example.
A film 35 such as a polyester film is attached to the surface of the foam 33, and the film 35 is attached to the surface of the foam 33 using double-sided tapes 37 and 39.

In the embodiment of the present invention, the elastic body 31 is arranged on the fixed end side (drive side) of the second scanner 5 as described above, and the first scanner 3 and the second scanner 5 shown in FIG. When placed in the home position HP, the elastic body 31
Contact the first scanner 3. The polyester film 35 shown in FIG. 5 is used when the first scanner 3 enters the home position HP.
In addition to the role of reducing the frictional resistance between the slide member 11 and the elastic body 31, the first scanner 3 and the second
Is repeatedly slid along the guide rod 7, wear and fatigue of the elastic body 31 can be reduced.

In the embodiment of the present invention shown in FIG. 5, when the elastic members 31 are attached to the slide members 11 and 13 with the increased inner diameter, the vibration at the time of starting the scanner at the free end of the first scanner 3 is shown. 7 shows a waveform example. According to the vibration waveform of the embodiment of the present invention, it can be seen that the vibration is considerably suppressed.

FIG. 4 shows still another elastic body 131 of the present invention. This elastic body 131 is formed by forming a leaf spring into a predetermined shape, for example, a substantially S-shape. By using such an elastic body 131, the margin for use durability and life can be further increased.

Incidentally, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the claims. For example, the configuration of the image reading apparatus of the present invention is not limited to a copying machine or a scanner, but can be applied to other types of image reading apparatuses.

[0033]

According to the first aspect of the present invention, by adding an inexpensive part, the scanning performance is not degraded even in the environment or over time. Vibration and impact can be absorbed at low cost when scanning of the scanner is stopped.

According to the second and third aspects of the present invention,
By sticking the film to the foam, the use durability of the foam can be improved.

According to the fourth aspect of the invention, the use durability can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an image reading apparatus of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of the image reading apparatus of FIG.

FIG. 3 is a perspective view showing an example of an elastic body.

FIG. 4 is a perspective view showing another example of the elastic body.

FIG. 5 is a diagram showing an example of a vibration waveform in the image reading device of the present invention.

FIG. 6 is a diagram illustrating a vibration waveform when the scanner is activated at the free end of the first scanner when almost no clearance is secured at room temperature in the conventional image reading apparatus.

FIG. 7 is a diagram illustrating a vibration waveform when the scanner is activated at the free end of the first scanner when the +0.05 mm clearance increases in the conventional image reading apparatus.

[Explanation of symbols]

 3 First Scanner 5 Second Scanner 7 Guide Rod (Guide Member) 31 Elastic Body HP Home Position 33 Foam 35 Film 131 Leaf Spring (Elastic Body)

Claims (4)

[Claims] A light source for irradiating an image of the original on the original placing table with light;
An image reading apparatus for reading an image of a document using a first scanner scanned at a first speed and a second scanner scanned at a second speed lower than the first speed, comprising: an end of the first scanner; A guide member for supporting one end of the first scanner and guiding it in the scanning direction; and a guide member disposed at one end of the second scanner, wherein one end of the first scanner and one end of the second scanner are located at the home position. And an elastic member that elastically contacts one end of the first scanner. 2. The image reading apparatus according to claim 1, wherein the elastic body is formed by attaching a film to a surface of a foam. 3. The image reading apparatus according to claim 1, wherein the elastic foam is a polyurethane foam, and the film is a polyester film. 4. The image reading apparatus according to claim 1, wherein the elastic body is a leaf spring.