JPH03203729A - Original scanning device - Google Patents

Abstract

PURPOSE:To make a scanning/illuminating part compact and to facilitate the adjustment of the accuracy of a reflecting mirror by providing light sources in such a manner that they are fixed by shifting the heights in a vertical direction in which an original is scanned in the vicinity of both ends of an original platen. CONSTITUTION:The device has the two-stage structure by arranging the light source 1 from the start position side and the lighting source 1' from the end position side in such a manner that they are vertically shifted from each other. A gap between the parabolic mirrors 3 and 3', which face each other, requires only such a distance that it is longer than the width of a slit arranged below the parabolic mirror. Also, since the illumination luminous flux itself can be also made reflected in an acute angle direction with respect to the incident luminous flux, the parabolic mirrors 3 and 3' can be arranged nearly perpendicu lar to an original platen glass 5. Thus, the constitution of the entire device can be made compact, and accuracy in the inclinations of parabolic mirrors 3 and 3' can be easily adjusted.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a document scanning device suitable for a high-speed copying machine that performs scanning illumination by having a fixed light source and scanning only by a parabolic mirror and a scanning mirror. .

[Conventional technology]

Conventionally, in scanning devices such as copying machines, a system has been generally used in which an illumination light source, an elliptical mirror, and a scanning mirror are configured as one fixed unit, and the unit scans the bottom surface of the document with illumination. There is. In addition, in high-speed copying machines, moving the light source together with the scanning mirror etc. increases the weight, making it difficult to increase the moving speed sufficiently, and also because the cord extending from the light source must also be moved. However, there were many disadvantages in terms of durability. Therefore, as shown in FIG. A method has been proposed for scanning and illuminating the document on the document table glass 10 by moving only the scanning mirror in the direction of C in the figure.In FIG. 9 is a collimator lens for converting the light into parallel light, and 9 is a reflecting mirror for re-illuminating the front by returning the luminous flux emitted to the rear of the lamp to the position of the lamp.

However, in such a method, it is necessary that the light source section be placed behind the start position or end position of scanning, and that the scanning section including the parabolic mirror scan the entire scanning range. Therefore, there is a large difference in the amount of light on the document surface between an area close to the light source and an area far from the light source, often resulting in uneven illumination over the entire area of the document.

In order to solve this problem, as shown in FIG. 5, light sources 11 and 11' are arranged at the scanning start position and end position, respectively, and the parallel light beams from both sides are reflected by parabolic mirrors 13 and 13'. proposed a method of illuminating the upper surface of the document table glass 15.

When this method is used, when the scanning section moves in the direction C and approaches the light source 11, the parabolic mirror 13 approaches the light source 11, so the intensity of the illumination light flux from the left side of the figure increases. . On the other hand, since the parabolic mirror 13' moves away from the light source 11' at that time, the intensity of the illumination light beam decreases. However, when the scanning section approaches the light source 11', the exact opposite phenomenon occurs, so the total amount of light on the document surface becomes uniform no matter where the scanning section is located. will be corrected accordingly.

[Problem that the invention is trying to solve]

However, in the above-mentioned conventional example, in order to reflect the parallel light beam from the light source at an obtuse angle with respect to the incident direction,
It is necessary to similarly arrange the parabolic mirrors 13 and 13' at an obtuse angle, and the width of the parabolic mirror itself in the C direction must be increased. Therefore, IIB' in the C direction of the scanning section including the parabolic mirrors 13 and 13' generally becomes large. In addition, since the width of the reflected light beam from the parabolic mirror is narrow, it is necessary to take a long distance to focus the light beam, so the width A' in the height direction of the scanning illumination device is It became necessary to take a long time. In this way, the light source section is placed at both the start position and the end position, and illumination is provided by two parabolic mirrors. The method shown in FIG. 5 has the disadvantage that the width B' of the scanning section including the parabolic mirror and the height A' of the scanning illumination device become very large, making the overall size of the scanning illumination device very large. occured.

Furthermore, since the height A' of the scanning illumination device becomes large, there is a disadvantage that the adjustment accuracy for adjusting the image formation position of the illumination light beams from both sides on the document surface by adjusting the inclination of the parabolic mirror becomes extremely difficult. I was so excited.

[Means to solve the problem]

According to the present invention, in a scanning illumination device configured by separating a fixed light source and a scanning illumination unit, the illumination light source from the start position side and the illumination light source from the end position side are arranged vertically shifted from each other, and two It has a tiered structure. Furthermore, the document surface was configured to be illuminated by parabolic mirrors arranged in upper and lower stages in two stages facing each other so that the two stages of illumination light beams were reflected in acute angle directions with respect to the incident direction. . As a result, it is an object of the present invention to make the overall configuration of the scanning illumination device more compact, and to easily adjust the tilt accuracy of the parabolic mirror.

That is, in order to achieve the above object, the present invention includes a light source, an original placing table on which a document is placed, and a reflecting means for reflecting light from the light source onto the original placing table, and the reflecting means is moved to scan the original. In the document scanning device, the light sources are fixedly provided near both ends of the document table in the document scanning direction, with heights shifted in the vertical direction.

[Embodiment 1] FIG. 1 shows a first embodiment of the present invention, and is a sectional view that best represents the configuration.

In Fig. 1, 1 and 1' are light sources, 2 and 2' are collimator lenses for converting the illumination light flux emitted forward from the light source into parallel light fluxes, and 4.4' are collimator lenses for converting the light flux emitted backward from the light source. A reflector is shown being returned to the light source position for re-illumination. On the upper stage, the light beam emitted by the light source 1 from the start position side is irradiated in the direction of the end position as a parallel light beam. Further, a parabolic mirror 3 is disposed opposite to this, and reflects the incident light beam in an acute angle direction with respect to the advancing direction of the incident light beam, and irradiates the document surface in a focused manner. Further, on the end position side, the light beam emitted by the light source 1' faces the light beam from the light source 1 described above, and illuminates the start position side in the lower stage where it does not interfere. Opposite this, parabolic mirror 3
' is arranged to similarly focus the illumination on the upper surface of the document table glass 5.

With such an arrangement, the distance between the opposing parabolic mirrors 3 and 3' should be equal to or larger than the distance between the slits (not shown) placed at the bottom of the parabolic mirrors, and the illumination light beam itself can also be incident. Since the light beam can be reflected in an acute angle direction, the parabolic mirror can be placed in a direction closer to perpendicular to the document table glass. Therefore, the width B of the scanning system unit including the parabolic mirror can be configured to be smaller. Furthermore, the height A of the scanning illumination device is approximately twice the height of the parallel light beams from the light sources 1 and 1', and compactness in the height direction is achieved. This reduces the amount of movement of the focused light beam on the document surface with respect to the inclination of the parabolic mirrors 3 and 3', making it possible to easily perform adjustment.

[Example 2] FIG. 2 shows a second embodiment of the invention.

The light beams emitted by the light sources 16 and 16' are converted into a focused light beam by lenses 17 and 17'. The focused light beams emitted from both ends are arranged in two stages, upper and lower, so that they do not interfere with each other. These light beams are reflected by plane mirrors 18 and 18' and are imaged on the surface of the document. The scanning illumination part, which is composed of a plane mirror and a scanning mirror (not shown), moves in the C direction to perform scanning. At this time, the position to the image plane differs depending on the moved position, so in order to correct the optical path length, the lens 17 and 17' move in the direction E to correct the optical path length. Such a configuration also makes it possible to make the scanning illumination unit more compact and to facilitate the adjustment accuracy of the plane mirror.

[Example 3] FIG. 3 shows a third embodiment of the present invention.

The light beam emitted forward from the light source 21.21' is converted into parallel light by the Fresnel lens 22.22'.

This Fresnel lens, like a normal lens, is arranged so that its focal point matches the position of the light source. The parallel light beams silently emitted from both ends are similarly arranged in two stages, upper and lower, so that they do not interfere with each other. Even with such a configuration, effects equivalent to those of the first embodiment can be expected.

〔Effect of the invention〕

As explained above, by configuring the illumination light beams from both ends in two stages, upper and lower, so as not to interfere with each other, and by irradiating the light beams at an acute angle with respect to the incident direction, the scanning illumination unit can be made more compact and the adjustment accuracy of the reflector can be improved. It is possible to make it easier.

[Brief explanation of drawings]

1 is a cross-sectional view of a document scanning device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a document scanning device according to a second embodiment of the present invention, and FIG. 3 is a cross-sectional view of a document scanning device according to a second embodiment of the present invention. 4 and 5 are views showing a conventional example. 1.1'... Light source, 2.2'-... Collimator lens, 3, 3'... Parabolic mirror, 4, 4'... Concave mirror, 5
. . . Original table glass, 6. Light source, 7. Collimator lens, 8. Parabolic mirror, 9. Concave mirror, 10.
...Original table glass, 11.11'...Light source, 12.1
2'... Collimator lens, 13.13'... Parabolic mirror, 14.14'... Concave mirror, 15... Original table glass, 16.16'... Light source, 17.17' ...
Focusing lens, 18.18'...plane mirror 19.1
9'...Concave mirror, 20...Original table glass, 21.2
1'... Light source, 22. 22'... Fresnel lens, 23° 23'... Parabolic mirror, 24, 24... Concave mirror, 25... Original table glass, AA'...・Height of scanning illumination device, BB' ...Width of scanning illumination section, C...
Direction of movement of scanning illumination unit, D... Width of luminous flux, E... Direction of movement of focusing lens 3 Fig. 4-Fig.

Claims (2)

[Claims] (1) In a document scanning device that includes a light source, a document placement table on which a document is placed, and a reflection unit that reflects light from the light source onto the document placement table, and that moves the reflection device to scan the document, the light source An original scanning device characterized in that the original scanning device is fixedly provided near both ends of an original document mounting table in a vertically shifted height in the original scanning direction. (2) The document scanning device according to claim 1, wherein the reflection angle of the light from the light source by the reflection means is an acute angle.