JPS597085B2 - Original scanning device of electronic copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document scanning device for an electronic copying machine.

In the document scanning device of a conventional electronic copying machine, which has a means for exposing a light image of an A4 size and a B4 size book or a sheet document, and a means for scanning an A3 size document, two imaging optical systems are required. Therefore, when switching the document scanning device, unevenness in image surface illumination occurs.

Therefore, there is a drawback that, in order to make the image plane illuminance distribution uniform, it is necessary to correct the image plane illuminance distribution when switching the document scanning device. In addition, in order to eliminate this drawback, the imaging lens is arranged so that the chief ray of the image light passes through the vertical optical axis of the imaging lens, and the two document surfaces are arranged on the vertical optical axis. However, such an arrangement requires that the scanning optics for each document be aligned with the vertical optical axis, so that
There is a drawback that the installation conditions for the above-mentioned scanning optical device are limited. SUMMARY OF THE INVENTION An object of the present invention is to provide a document scanning device for an electronic copying machine that can eliminate the above-mentioned drawbacks.

The present invention will be explained below based on the illustrated embodiments.

In FIG. 1, reference numeral 1 indicates a contact glass on which a book or a sheet-like original is placed.

Disposed near the contact glass 1 are sheet feeding rollers 2 and 3 that transport a sheet-like original at high speed in the direction of arrow a. A light shielding plate 4 is provided below the sheet feeding rollers 2 and 3, and the light shielding plate 4 has a slit 5 for passing light between the sheet feeding rollers 2 and 3.
is formed. Illumination means 6 consisting of a lamp 6a and a lamp reflector 6b is arranged below the contact glass 1.

The original on the illumination means contact glass 1 (hereinafter referred to as the "stationary original") is illuminated in a slit shape while moving in the direction of the arrow at a speed of V, stops at the position shown by the 0-dot chain line, and then turns the original into a stationary original again. When illuminating, it returns to the position shown by the solid line, that is, the illumination start position. In addition, sheet feed roller 2,
When illuminating a sheet-like original (hereinafter referred to as a "moving original") transported by 3, the illumination means 6 is moved from the position shown by the one-dot chain line to the position shown by the two-dot chain line, and stopped at that position, and the moving original is illuminated. to illuminate. When illuminating a stationary document again, use the illumination means 6 as a solid line! 3-Move to the indicated position, that is, the illumination start position.

The first document scanning device will be described below. The first mirror 7 for receiving light from the stationary document moves at the same speed in synchronization with the illumination device 6 only when the illumination device 6 illuminates the stationary document. When scanning a stationary document again, the illumination means 6 returns to the position shown by the solid line.

A second mirror 8 is arranged to receive the reflected light from the first mirror 7, and the second mirror 8 moves in the direction of arrow c at a speed -FV in synchronization with the first mirror 7 during exposure. Then, it returns to the position shown by the solid line in preparation for exposure to light from the next stationary document. An imaging lens 9 is arranged to receive the reflected light from the second mirror 8. The principal ray of the reflected light from the original, which becomes image light with respect to the imaging lens 9, passes through the oblique optical axis of the imaging lens 9. 2nd above
A third mirror 10 is arranged to receive the reflected light from the mirror 8 after passing through the imaging lens 9.
A rotating mirror 12 is arranged so as to receive the reflected light from the third mirror 10 and form an image on a photosensitive drum 11 which rotates at a circumferential speed of V in the direction of arrow d. The rotary mirror 12 can be rotated in the direction of arrow e to change its inclination angle so that the light from the stationary original and the light from the moving original are imaged at the same position on the photoreceptor drum 11. It's getting old. Next, the second document scanning device will be described.

This second document scanning device has a document scanning optical system that is separate from the optical system of the first document scanning device described above, and has a first mirror configured to receive light from the moving document. 13 are arranged. The first mirror 13 directs the reflected light toward the imaging lens 9. The angle of incidence with respect to the optical axis of the imaging lens 9 when the light from the stationary original is incident on the imaging lens 9 is θ1, and the imaging lens 9 when the light from the moving original is incident on the imaging lens 9 The document scanning optical system is configured so that θ1 - θ, where θ2 is the incident angle with respect to the optical axis. A second mirror 14 and a third mirror 15 are arranged so that after the reflected light from the first mirror 13 passes through the imaging lens 9, the reflected light is directed toward the rotary mirror 12. In the above description, the illumination means 6 moves from the position shown by the solid line to the position shown by the dashed line when illuminating the stationary original, and returns to the position shown by the solid line after illumination, and the illumination means 6 moves the moving original to the position shown by the solid line. It may also be configured to be illuminated by another illumination means having the same light distribution characteristics as those of 6. The document scanning device shown in FIG. 2 has two illumination means 16, 1 compared to the one shown in FIG.
7, the sheet feeding rollers 2 and 3 are located higher than the contact glass 1, and the optical path switching plate 18 is provided, but the other points are substantially the same as that shown in FIG.

In FIG. 2, the illumination means 16 illuminates the stationary document in a slit shape while moving in the direction of arrow b, and returns to its original position after the illumination is completed when the stationary document is to be illuminated next. Next, when illuminating the moving original, the illuminating means 16 and the mirror 7
, 8 may be stopped at the position shown by the one-dot chain line, or may be returned to the stationary document scanning start position. When stopping at the position shown by the one-dot chain line, it is preferable to place a light absorbing member at an appropriate position to cover the reflective surfaces of the mirrors 7 and 8 at the same time as the stop to remove harmful light.
The illumination means 17 is fixed at the illustrated position and illuminates the document between the sheet feed rollers 2 and 3. The light distribution characteristics of the illumination means 17 are the same as those of the illumination means 16. The optical path switching plate 18 is fixed to a rotating shaft 19.
9 is rotated in the direction of arrow f, and is placed at the position shown by the solid line when exposing a stationary original so that the light from the illumination means 17 does not reach the photoreceptor drum 11. It is placed at the position shown by the one-dot chain line when a moving document is exposed, and blocks the light from the illumination means 16 so that it does not reach the photoreceptor drum 11. If only the illumination means 16 is turned on when illuminating a stationary original, and only the illumination means 17 is turned on when illuminating a moving original, the optical path switching plate 18 becomes unnecessary. According to the present invention, when arranging the scanning devices constituting the document scanning optical system that are installed independently, there is no need to add setting conditions to the device, such as aligning the device with the vertical optical axis of the imaging lens. , the layout of each member of the scanning device can be set with a degree of freedom;
When light from a stationary document in the document scanning optical system that is independent of the shared lens is incident on the imaging lens, the incident angle with respect to the optical axis of the imaging lens is when light from a moving document is incident on the imaging lens. Since the incident angle with respect to the optical axis of the imaging lens is the same as that of the image forming lens, there is no need for means for correcting the image plane illuminance distribution when switching the document scanning optical system. Sao 3
64m7! L, the length of the contact glass 1 in the width direction of the photoreceptor drum 11 is 257 m1L, and
Set the length of sheet feed rollers 2 and 3 to 29711 or more and 364
m77! With the following, it is possible to place an A4 size or B4 size book or sheet original on the contact glass and scan the original, and also scan an A3 size sheet original while transporting it with a sheet feed roller. This has the advantage that the copying machine can be much smaller than the conventional copying machine.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing the main parts of an embodiment of a document scanning device for an electronic copying machine according to the present invention, and FIG. 2 is a layout diagram showing the main parts of another embodiment of the invention. 1... Contact glass, 2, 3...゜゜Sheet feed roller, 6, 16, 17... Lighting means, 7, 8, 10... First Mirror of document scanning device, 9... Imaging lens, 11゜゛゜''゜゜photosensitive drum, 12... Rotating mirror, 13, 14
, 15...Mirror of the second document scanning device.

Claims (1)

[Claims] 1. A first document scanning optical system, which forms independent imaging optical paths from the document surface to the photosensitive surface, performs slit exposure while keeping the document still, and a second document scanning optical system, which performs slit exposure by moving the document.
In the document scanning optical system of a copying machine, the principal ray of the image light from the document is directed to the imaging lens of the first and second document scanning optical systems. A document scanning device for an electronic copying machine, characterized in that the incident light passes through an oblique optical axis, and the incident angles of the incident light from the first and second document scanning optical systems to the imaging lens are set to be substantially the same.