JPH0563916A - Picture reader - Google Patents

Abstract

PURPOSE:To attenuate the vibration of a read means by adhering a dynamic damper with a butyl rubber and a lead sheet adhered thereto to a rail. CONSTITUTION:A glass plate holding an original 1, a lighting unit 3 lighting an original to form a picture light E and a rail 2 with a mirror unit 4 held movably thereto are mounted on the reader main body. Moreover, a CCD 10 reading the picture of the original 1 is held by the rail 2. In this case, a dynamic damper with a butyl rubber and a lead sheet adhered thereto is formed and adhered to the rail 2. By such constitution, the vibration of the CCD 10 is attenuated and the picture is read excellently.

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 having optical means for illuminating an original and reading means for receiving image light, such as a digital copying machine and an image scanner.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional image reading apparatus of this type. Reference numeral 100 denotes a document, and the document 100 is placed on a document holding member (not shown), that is, a document table glass with the document surface facing down. The original platen glass is attached to the upper portion of the main body of the apparatus (not shown). Further, a pair of rails 101 as guide members are fixed in parallel inside the apparatus main body, that is, below the document table glass. This rail 1
01 is parallel to the platen glass.

Reference numerals 102 and 103 denote an illumination unit and a mirror unit as optical means, and the illumination unit 102 and the mirror unit 103 are reciprocally held on the rail 101 in the directions of arrows A and B. Specifically, this holding is performed by rolling elements such as rollers. Lighting unit 102
Has a light source, a mirror and the like not shown. The mirror unit 103 also includes mirrors 104 and 105.

Further, a plate-shaped support base 106 is attached between the pair of rails 101, and the support base 106 is attached.
A condenser lens 107 and a photoelectric conversion element (hereinafter referred to as CCD) 108 as an image reading unit are provided on the upper surface of the.

In this way, the respective parts, that is, the original table glass, the illumination unit 102, the mirror unit 103, the condenser lens 107, and the CCD 108 are positioned relative to each other.

In the above structure, the original 100 is illuminated by the light source of the illumination unit 102, and the illumination unit 102 moves in the direction of arrow A at a speed of Dmm / sec.
The mirror unit 103 moves in the same direction at a speed of 0.5 × D mm / sec. As a result, the image light E formed by the illumination is condensed by the mirrors 104 and 105.
The image is guided to the image forming device 7, and is condensed by the condensing lens 107 and then imaged on the CCD.

In the CCD 108, the image light E is subjected to pixel decomposition, and an image reading operation is performed in which the image light E is converted into an electric signal corresponding to the density of each pixel.

[0008]

However, in the above-mentioned conventional example, since the CCD 106 is indirectly held by the rail 101 for the purpose of maintaining the positional relationship between the respective parts with high precision, the illumination unit 102 and the mirror unit 1 are provided.
Rail 10 due to the frictional resistance generated by the movement of 03.
1 is vibrated, or the vibration of the device itself causes the rail 1
When 01 vibrates, the vibration causes the holding table 106
Is transmitted as a force to the CCD 108 via
The CCD 108 vibrates.

As a result, the above-mentioned positional relationship, especially the original 100
The positional accuracy between the CCD 108 and the CCD 108 is incorrect, which leads to an image reading failure, that is, an electric signal blur.

An object of the present invention is to solve the above problems and an object thereof is to provide an image reading apparatus capable of damping the vibration of the reading means.

[0011]

In order to achieve the above object, the present invention provides a guide for movably holding a document holding member for holding a document and an optical means for illuminating the document to form image light. And a reading means for receiving the image light to read the image of the original, and holding the reading means by the guide member, the reading means is attached to the original holding portion. In the image reading apparatus which is positioned, vibration damping means for damping the vibration of the reading means is provided.

[0012]

In the present invention based on the above construction, the optical means moving along the guide member illuminates the original document to form image light. The image light is received by the reading means, and the image of the document is read. The reading means is held by a guide member and positioned at a predetermined position with respect to the document.

During the reading operation, when a forcing force is applied to the reading means through the guide member and the reading means vibrates, this vibration is damped by the vibration damping means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to FIGS. 1 and 2 in which the present invention is applied to an image scanner and a digital copying machine. Reference numeral 1 denotes a document, which is a document holding member (not shown), that is,
The original is placed on the platen glass with the original side facing down. The platen glass is horizontally attached to the upper portion of the apparatus main body (not shown). Further, a pair of rails 2 as guide members are fixed in parallel inside the apparatus main body, that is, below the original platen glass. The rail 2 is parallel to the platen glass and has a substantially U-shaped cross section.

Numerals 3 and 4 are an illuminating unit and a mirror unit as optical means, and the illuminating unit 3 and the mirror unit 4 are provided at both ends thereof so as to be able to reciprocate on the rail 2 in the directions of arrows F and G. It is held by the guide surface of the rail 2 via rolling elements such as rollers. The illumination unit 3 has a light source, a mirror, etc., which are not shown. Further, the mirror unit 4 has mirrors 5, 6 and the like.

Further, a horizontal projecting portion 7 is provided at a portion where the pair of rails 2 face each other, and a plate-shaped support base 8 is attached (fixed) on the projecting portion 7. A condenser lens 9 and a photoelectric conversion element (hereinafter referred to as CCD) 10 as an image reading means are provided on the upper surface of the support base 8. The CCD 10 is connected to an image processing unit such as a central processing unit (not shown). In the case of a copying machine, the image processing unit is further connected to an image forming unit (not shown).

In this way, with respect to the platen glass,
Illumination unit 2, mirror unit 4, condenser lens 9, C
The CD 10 is accurately positioned and positioned at a predetermined position. The term "position" here means a distance relationship in the vertical direction and a horizontal relationship with the end of the placement area of the document 1.

A damping material 11 is attached to the lower surface of the rail 2 as a vibration damping means for damping the vibration of the CCD 10. FIG. 2 is an enlarged view of the damping material 11. The damping material 11 is composed of a sheet-shaped butyl rubber 12 bonded to the rail 2 along the longitudinal direction, and a lead sheet 13 bonded to the lower surface of the butyl rubber 12. Here, the natural frequency of the damping material 11 is set to be equal to the natural frequency of the rail 2 and the CCD 10.

In the above structure, the original 1 is illuminated by the light source of the illumination unit 3, the illumination unit 3 moves in the direction of arrow F at a speed of Hmm / sec, and the mirror unit 4 moves at a speed of 0.5 × Hmm / sec. To move in the same direction.
As a result, the image light J formed by the illumination is guided to the condenser lens 9 by the mirrors 5 and 6, is condensed by the condenser lens 9, and then is imaged on the CCD 10.

In the CCD 10, the image light J is decomposed into pixels, and an image reading operation is performed in which the image light J is converted into an electric signal corresponding to the density of each pixel.

The electric signal is transferred to an image processing unit (not shown), and an image is formed on the image forming unit based on the signal.

During the above operation, when the illumination unit 3 and the mirror unit 4 are moved, if a forcible force is applied to the rail 2 and the CCD 10 due to frictional resistance or stick-slip to generate vibration, or an external force is applied to the main body of the apparatus, the rail 2 vibrates. In this case, the lead sheet 13 vibrates through the butyl rubber 12 to absorb the force applied to the rail 2 and the CCD 10. That is, the damping material 11 functions as a so-called dynamic damper. As a result, rail 2, CCD 1
The vibration of 0 is attenuated, the position with respect to the document 1 can be properly maintained, and a stable image reading operation can be secured.

The density gradation of the formed image is also stable. Further, when the CCD 10 is capable of separating three colors of red, blue and yellow, color reproducibility for the original 1 is secured and image quality can be maintained.

Although butyl rubber 12 is used in the above embodiment, other different materials such as silicone rubber and chloroprene rubber may be laminated.

Furthermore, the vibration damping means may be constituted by a so-called friction damper in which a friction material is interposed between the rail 2 and the support plate 8. According to this structure, when the rail vibrates, a displacement occurs between the rail and the support plate, and the frictional force can dampen the vibration of the CCD on the support plate.

[0026]

Since the present invention is configured as described above, the vibration of the reading means, which is generated when an external force is applied to the apparatus body or the guide member vibrates due to the movement of the optical means, is dampened. The position of the reading means with respect to can be maintained. Therefore, a stable image reading operation can be performed at all times.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a main part of FIG.

FIG. 3 is an overall perspective view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 original 2 rail (guide member) 3 illumination unit (optical means) 4 mirror unit (optical means) 10 CCD (reading means) 11 damping material (vibration damping means) J image light

Claims (1)

[Claims] 1. An original holding member for holding an original, and a guide member for movably holding an optical means for illuminating the original to form image light are attached to a main body of the apparatus to receive the image light. And an image reading device for reading the image of the original by positioning the reading means with respect to the original holding section by holding the reading means by the guide member. An image reading apparatus provided with a vibration damping means for damping the.