JPH02148962A - Focus hold mechanism for optical picture reader - Google Patents

Abstract

PURPOSE:To read accurately a picture face of paper with various thickness by pressing a paper guide freely elevated and descended in a paper guide direction opposite to the guide by a spring force elastically. CONSTITUTION:A lower paper guide 8 made of a white shading plate supported freely elevated and descended is in elastic contact to the lower face of an upper paper guide 2 with a pressing spring 10 fitted to a device side while being kept in parallel with the upper paper guide 2. Moreover, the focus of an image sensor 4 is set onto the face of the paper guide of the upper paper guide 2. When the paper 28 is loaded between the upper and lower paper guides 2,8, the paper is fed in a prescribed direction while being in close contact onto the paper guide face, the distance with the image sensor 4 is kept constant and the picture face is located to the focus of the image sensor 4 and the picture face is read. Thus, the picture is read accurately in response to the thickness and width of the paper.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a focus holding mechanism for an optical image reading device.

[Conventional technology]

In this type of optical image reading device, conventionally, the thickness of the paper is limited, and a guide gap is provided between the image sensor and the paper guide by the thickness. Also, by the suction force from the negative pressure hole.

Suction the paper to the paper guide surface on the image sensor side,
The distance from the image sensor to the paper is kept constant, thereby focusing the image surface of the paper on the image sensor.

[Problem that the invention seeks to solve]

In the conventional methods described above, where the guide gap is fixed, depending on the thickness of the paper, the image surface of the paper may not be in focus of the image sensor.

Additionally, those using negative pressure holes have the disadvantage that they have a complicated structure and are difficult to suction thick sheets of paper.

The present invention aims to eliminate the above-mentioned defects.

[Means to solve problems]

In order to achieve the above object, the present invention provides a method for feeding paper between upper and lower paper guides, and disposing an image sensor on one paper guide side of the upper and lower paper guides at a constant distance from the paper guide. In the optical image reading device configured to read an image on the paper, the focus of the image sensor is set on the paper guide surface of the one paper guide, and one of the upper and lower paper guides is set on the paper guide surface of the paper guide. supports the other paper guide facing it so that it can move up and down in the direction toward and away from it while remaining parallel to it, and the paper guide, which can go up and down, is elastically moved in the direction of the paper guide facing it by a spring force. This is what I did.

[Effect]

When paper is inserted between the upper and lower paper guides, the paper guide on the elevating side moves against the spring force due to pressure from the paper depending on the thickness and width of the paper, and the image surface of the paper moves. The paper is brought into close contact with the paper guide on the image sensor side, and the image surface of the paper matches the focal point of the image sensor set on the paper guide surface of this paper guide.

〔Example〕

The structure of the present invention will be described in detail below with reference to embodiments shown in the accompanying drawings.

Reference numeral 2 denotes an upper paper guide fixed to the body (not shown) of the optical image reading device, and a known image sensor 4 is fixed above this.

A reading slit 6 is transparently provided in the upper paper guide 2, located directly below the image sensor 4.

Reference numeral 8 denotes a lower paper guide made of a white shading plate that is supported on the machine body so as to be movable up and down while being parallel to the upper paper guide 2, and is supported by a pressure spring 10 attached to the machine body side. , is in elastic contact with the lower surface (paper guide surface) of the upper paper 2. 1
2, 14, 16° 18 are paper feed drive rollers provided on the machine body side; 20.22. 24 and 28 are pinch rollers rotatably attached to the machine body, and the surface thereof is located on the same plane as the upper surface (paper guide surface) of the lower paper guide 8, and the lower paper guide 8 and is rotatably supported.

The focus of the image sensor 4 is set on the paper guide surface of the upper paper guide 2. In the above configuration, when the paper 28 is inserted between the upper and lower paper guides 2.8, the paper 2.8 The lower paper guide 8 moves downward against the elasticity of the pressure spring 10, and the guide gap between the upper and lower paper guides 2 and 8 is set to an appropriate state according to the width of the paper 28. 6 In this state, the paper 28 between the upper and lower paper guides 2 and 8 is
The paper is fed in a predetermined direction while being in close contact with the paper guide surfaces of the upper and lower paper guides 2 and 8. As a result, the paper 28 directly below the image sensor 4 maintains a constant distance from the image sensor 4, and moves in a predetermined direction with the image plane positioned at the focal point of the image sensor 4, and is moved in a predetermined direction by the image sensor 4. The image plane directly below it is read.

Note that the thickness of the paper may be detected by a separate detector and the elevating side paper guide may be moved according to the thickness.
The lower paper guide s side may be fixed.

〔effect〕

Since the present invention is constructed as described above, the image surface of sheets of paper of various thicknesses can be focused on the image sensor using a simple mechanism, and the image surface of the paper can be accurately read.

[Brief explanation of the drawing]

FIG. 1 is a side view, FIG. 2 is an explanatory side view, and FIG. 3 is an explanatory side view.

Claims (1)

[Claims] (1) A sheet of paper is sent between the upper and lower paper guides, and an image on the sheet of paper is read by an image sensor placed on one of the upper and lower paper guides at a constant distance from the paper guide. In the optical image reading device, the focus of the image sensor is set on the paper guide surface of the one paper guide,
One of the upper and lower paper guides is supported so that it can move up and down in a direction toward and away from the paper guide while keeping its paper guide surface parallel to the other paper guide facing it, and the paper guide that can be moved up and down is supported. A focus holding mechanism characterized in that a spring force is used to spring the paper guide in the direction opposite to the paper guide.