JPS623242A - Exposing device for copying machine - Google Patents

Abstract

PURPOSE:To perform fast exposure by moving the 1st and the 3rd plane mirrors and the 2nd and the 4th plane mirrors provided between an image forming lens and a photosensitive body according to an exposure scan on an original, and putting them in partial charge of a function of image formation on the photosensitive body in a half of their scanning stroke. CONSTITUTION:When a light source 1 begins to make an exposure scan on the original 2 from a point A to a point B, plane mirrors M1 and M3 form a scanned original image at an image formation position P while moving on straight lines L1 and L3 as shown by arrows. When the light source 1 reaches a point C in the center of the original 2, the plane mirrors M1 and M3 stop. When the light source 1 makes the exposure scan continuously beyond the point C, plane mirrors M2 and M4 begin to move on straight lines L2 and L4 as shown by arrows and form a scanned original image at the image formation point P; when the light source 1 reaches the point B, the plane mirrors M2 and M4 stop and the original image of the original 2 is exposed and scanned entirely from A to B and then recorded on the photosensitive drum 3 electrostatically. Consequently, the movement distance of the moving part may be short and fast exposure is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to an exposure device for a copying machine with a fixed document table that exposes a document to light and forms the document image on a photoreceptor.

(B) Prior art A conventional exposure device for a copying machine with a fixed document table that guides the document image to a predetermined position on the photoreceptor drum and forms the image includes a fixed imaging lens; There is a so-called moving mirror type exposure device, which is composed of a plurality of plane mirrors that move in conjunction with an exposure light source between the document surface and an imaging lens, and an exposure device in which the imaging lens is moved in conjunction with an exposure light source. A moving lens type exposure device can be seen.

(c) Problems to be Solved by the Invention However, in the former method, the plane mirror must be moved by the distance of the exposure light source, so it is not suitable for high-speed exposure. In addition, in the latter case, it is necessary to move the lens, which is heavy and requires high positional accuracy.
Not suitable for high-speed exposure.

In contrast, a planar mirror provided between the imaging lens and its virtual imaging surface is moved by a distance corresponding to the length of the document.
No. 6258) is also available, but it does not significantly shorten the moving distance of the plane mirror and is not suitable for high-speed exposure.

This invention was made in view of these circumstances,
The present invention provides an exposure device that has a simple structure and is capable of high-speed exposure.

(d) Means for Solving Problems The exposure device of this copying machine includes a light source for exposing an original, a photoreceptor, and an imaging lens provided between the original and the photoreceptor, and further includes: first and second plane mirrors that reflect the original image incident from the lens, between the lens and the photoreceptor;
third and fourth plane mirrors that respectively reflect the incident light from the first and second plane mirrors and form an image on the image forming position of the photoreceptor, the first and third plane mirrors are arranged approximately halfway through the document scanning stroke; The second and fourth plane mirrors are configured to move in response to the exposure scan so that the second and fourth plane mirrors form the original image corresponding to the remaining half at the image forming position. It is characterized by:

(e) Operation The first and third plane mirrors and the second and fourth plane mirrors provided between the imaging lens and the photoconductor move in accordance with the exposure scanning of the original, and form an image on the photoconductor. Since each plane mirror performs half of the scanning stroke, the moving distance of each plane mirror is sufficiently shortened compared to the entire scanning stroke, making high-speed exposure possible.

(f) Examples Hereinafter, the present invention will be described in detail based on examples shown in the drawings. Note that this invention is not limited to this. In FIGS. 1 and 2 showing an embodiment of the present invention, (1) is a light source that exposes and scans a document ('2J from <A) to (B), (3) is a photosensitive drum, (4) is is FA
The imaging lenses (Ml) and (M2) are provided between the lens (2) and the photoreceptor drum (3), and the imaging lenses (Ml) and (M2) are provided between the lens (4) and the photoreceptor drum (3). ), (M3) and (M4) are plane mirrors (
It is a plane mirror that reflects the incident light from Ml) (M2) and forms an image on the imaging position (P) of the photoreceptor drum (3), and the plane 11 (Ml) (M3) is the scanning path of the document + 2). The original image corresponding to approximately half AC of AB is captured using a plane mirror (M2
) (M4) moves the document image corresponding to the remaining half CB to position (P
), each of the planes 1*(Ml) to (M4) is configured to move in response to exposure scanning.

In this example, the distance (a) from the document (2) to the lens (4) is set to twice the focal length (') of the lens, that is, a=2f, and the distance between the lens (4) and the imaging position is The distance (b) is set to b = 0,8a.Furthermore, the plane mirrors (Ml) to (M4) move on straight lines (Ll) to (L4) parallel to the scanning direction of the original (2), respectively. The distances of the straight lines (11) and (L2) to the lens (4) are set to 0.3a and 0.55a, respectively.

In FIG. 1, when the light source (1) starts exposure scanning of the document +21 from point (A) to point (B), the plane mirror (Ml
) (M3) move the original image scanned while moving in the direction of the arrow on the straight line (Ll) (L3), respectively, to the imaging position (P).
to form an image. The light source (1) is located at the center point of the original ('2J) (
When reaching C), the plane mirrors (Ml) (M3) stop. Furthermore, as shown in Figure 2, the light source (1) continues the exposure scan at the point (
C), the plane mirror (M2>(M4) becomes a straight line (L
2) (L4) Start moving the top ' in the direction of the arrow, focus the scanned document image on the imaging position (P), and when the light source (1) reaches the point (B), it will move to the plane M (M2). (M4) stopped and started.

The original image of '2J is exposed and scanned from point (A) to point (B), and electrostatically recorded on the photoreceptor drum (3).Furthermore, the plane mirrors (Ml) to (M4) are
It has a mechanism in which each angle is adjusted in conjunction with the lens (4) so that the original image from the lens (4) is focused on a point (P).

In this example, the plane mirror that moves the longest distance is (M2), as can be seen from FIGS.
(Distance between lens (4) and straight line (L2)) ÷ (original 4i (
21 and the lens (4)], which is only 28% of the total exposure scanning distance of the document.

In this way, between the lens (4) and the photoreceptor drum (3), a set of two planes that move in accordance with the exposure scan are installed.
By installing two sets of surface mirrors and dividing the exposure-scanned original image into each set by half, it is possible to perform exposure in which the moving distance of the moving parts is less than half.

In addition, in this example, each plane lft(Ml) to (M
4) are configured to move on straight lines (Ll) to (L4), respectively, but they may also move on curved lines.

(G) Effects of the Invention According to this invention, two sets of two plane mirrors are installed between the lens and the photosensitive drum, and each set is assigned to form an original image generated by exposure scanning. As a result, the moving distance of the moving part is much smaller than in the past, and an exposure device for a copying machine suitable for high-speed exposure is provided.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing the configuration and operation of an embodiment of the present invention. (1)...Light source, [21...
・Document, (3)... Photoreceptor drum, (4)
・・・・・・Lens, (Ml)～(M4)・・・・・・
plane mirror. Figure 1 Figure 2

Claims (1)

[Claims] 1. A light source for exposing an original, a photoreceptor, and an imaging lens provided between the original and the photoreceptor, and an image of the original incident from the lens is provided between the lens and the photoreceptor. and third and fourth plane mirrors that respectively reflect the incident light from the first and second plane mirrors and form an image on the image forming position of the photoreceptor; , the third plane mirror transfers the original image corresponding to approximately half of the original scanning stroke to the second plane mirror.
, wherein each of the plane mirrors is configured to move in response to exposure scanning so that the fourth plane mirror forms an image of the document corresponding to the remaining half at the image formation position. .