JPS6022865A - Image reading device - Google Patents

Abstract

PURPOSE:To attain miniaturization of the entire optical system and device by reducing the distance between a photoelectric converting element and a mirror approaching it less than the length to an original in the main scanning direction. CONSTITUTION:Image information on the original 5 is reflected by the 1st mirror 7 and the 2nd mirror 11, the surrounding luminous amount is corrected at a shading plate 13 and the image is formed on the photoelectric converting element 9 via a lens system 8. In selecting the shrinking rate as nearly 1/10, the effective reading width in the main scanning direction as 256mm., a half image angle of a wide-angle lens 8 as 25 deg. and a total optical length as 310mm., the distance between the 1st mirror 7 and the 2nd mirror 11 is 110mm. and the distance between the 2nd mirror 11 and the photoelectric converting element 9 is 171mm., and the distance between the mirror 11 and the photoelectric converting element 9 is smaller than the effective reading width in the direction of main scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image reading device, and more particularly to an image reading device with an improved configuration of a reading optical system.

Prior Art The configuration of the reading optical system of a conventional image reading device is as follows.
As shown in the figure.

In FIG. 1, reference numerals 31 to 34 indicate transport rollers that transport the original 35 along guides 45 and 46.

When the document 35 comes to the reading position, it is irradiated by a light source 36, and the reflected light is guided to a lens 38 by a mirror 37 located below.

The mirror 37 is fixed to a side plate 44 on the device main body side via a mirror stay 43, and the lens 38 is fixed to a side plate 44 on the side of the main body of the device via a mirror stay 43.
1 to the side plate 44 of the main body of the apparatus.

A shading plate 42 is fixed to the lens stay 41, and a photoelectric conversion element 39 is fixed on a support plate 40 fixed via a stud 41a.

By the way, if the above structure is adopted, the mirror 37
Since the lens 38 and the lens 38 are arranged on the same straight line, the optical path length from the mirror 37 to the photoelectric conversion element 39 is longer than the length of the document in the main scanning direction, making the entire optical system larger and downsizing the entire apparatus. The drawback was that it couldn't be done.

OBJECTIVES The present invention has been made to eliminate the conventional drawbacks as described in 4-1 above, and has an object of 1-1 to provide an image reading device configured such that the entire device can be miniaturized.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIGS. 2 and 3 are for explaining one embodiment of the present invention. In the figures, numerals 1 to 4 are document conveying rollers, numeral 5 is a document, and numeral 6 is a light source. be.

A first mirror, designated by numeral 7, reflects the original image; a first mirror, designated by numeral 9;
It is located between the mirror and the mirror, and this arrangement contributes to reducing the size of the entire device in the direction perpendicular to the main scanning direction. 8 is a wide-angle lens, 10 is a printed circuit board for controlling a photoelectric conversion element, 12 is a support for holding an optical system, and 13 is a support body for holding an optical system.
2 is a shading plate used in the photoelectric conversion element 9 to make the light wall uniform. The reference numeral 14 is a locking screw, and the reference numeral 15 is a pin that restricts rotation of the support body 12. This pin is fixed to an L-shaped fitting 12b fixed to the support body 12. 16 is a stay fixed to the side plate 17, 20 of the main body of the apparatus, and 18, 19 is a pin that rotatably supports the support body 12.

Next, the operation of the embodiment of the present invention configured as described above will be explained. When the original 5 is conveyed to the image reading position by the original conveyance roller 3.4, the image information on the original 5 is transferred to the first mirror disposed between the photoelectric conversion element 9 and the second mirror 11.
The light is reflected by the mirror 7 and the second mirror 11 disposed on the opposite side of the photoelectric conversion element 9 with the first mirror 7 as the border, and the amount of peripheral light is corrected by the shading plate 13 disposed directly below the first mirror 7. The light passes through the lens 8 disposed between the photoelectric conversion element 9 and the shading plate 13 and forms an image on the photoelectric conversion element 9 . A support body 12 holding the first mirror 7, second mirror 11, shape ink plate 13, lens 8, and photoelectric conversion element 9 is connected to a pin 19 fixed to the support body 12 between the side plates 17 and 20 of the main body of the apparatus, and a side plate 20. It is supported by a fixed pin 18 at an extension 1a-1- on the image reflection surface of the first mirror 7, and a pin 15 fixed to the support body 12 fits into a hole 16a provided in the stay 16. , restricts the rotation of the support body 12.

Next, in the configuration of the optical system described above, how the size can be reduced in the direction orthogonal to the main scanning direction will be explained using an example.

The reduction ratio is approximately 1/10, the effective reading width in the main scanning direction is 256 mm, and the half angle of view of the wide-angle lens 8 is 25 degrees.
When the total optical path length is 310 mm, as shown in FIG. It can be seen that the distance C between the second mirror 11 and the photoelectric conversion element 9 is 171 square meters, which is smaller than the effective reading width in the main scanning direction. In addition, 00840 due to the use of a wide-angle lens with a half-field angle of 25 degrees
The shading plate 13 is also used to reduce the amount of peripheral light due to the
By arranging it at the center of the mirror 7, sufficient correction can be achieved. Note that as the shading plate 13 approaches the lens, the R (radius) of the side edge forming the hole 13a (see FIG. 4) of the shading plate becomes smaller.
R increases as the distance from the lens increases. In this configuration, the shading plate 13 is arranged directly below the first mirror 7 in consideration of ease of manufacture and assembly.

Since this embodiment is configured as described above, the support 1
In the shape of No. 2, it is possible to make the length between the second mirror and the photoelectric conversion element shorter than the width in the main scanning direction including the effective reading width. This has the effect of contributing to miniaturization of the main body of the facsimile machine.

In addition, since the image reading device is separated from the main body of the device except for the light source and is configured as a unit, distortion of the main body of the device due to external force will directly result in defects in the read image, unlike in conventional image devices. This has the effect of contributing to the weight reduction of the entire device and the use of plastic. Moreover, because of this unitization, the adjustment of the device can be performed completely separately from the device itself, which has the effect of greatly increasing work efficiency.

Effects As is clear from the explanation given below, according to the present invention, the length between the second mirror of the image reading device and the photoelectric conversion element can be made smaller than the length in the main scanning direction.
The effect is that the entire device in which the image reading device is mounted can be made smaller.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view for explaining the conventional structure, 21Δ
~Figure 5 is for explaining one embodiment of the present invention,
Fig. 2 is a longitudinal sectional view, Fig. 3 is a view taken along the line A-A in Fig. 2,
FIG. 4 is a sectional view taken along the line BB in FIG. 2, and FIG. 5 is an explanatory diagram of the optical system. 7... First mirror 11... Second mirror 8... Lens 9... Photoelectric conversion element 12... Support body 15.
18.19.9. Pin 13...Shading plate Fig. 1 Fig. 2 Fig. 4 Fig. 3 Fig. 5

Claims (1)

[Claims] At least two mirrors and a wide-angle lens are provided in an optical path for forming an image of information recorded on a document onto a photoelectric conversion element, and the mirror and the photoelectric conversion element are provided in a position close to the photoelectric conversion element in the optical path. An image reading device characterized in that the length between the gaps is smaller than the length of the document in the main scanning direction.