JPS6015258B2 - Scanning exposure device in copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning exposure device in a copying machine.

An exposure method is known in which, while scanning an original to be copied, a light image of a scanned portion of the original is projected onto the surface of a photoreceptor whose surface is moving in a fixed direction, thereby exposing the photoreceptor to light. ing.

In such an exposure method, the document is scanned by moving the movable part of the exposure optical system along the surface of the document, or by moving the document itself relative to the exposure device. Generally, scanning of a document is performed only while the movable portion or the document is moving in a predetermined direction.

When obtaining multiple copies from the same original using a repeat mechanism, the original or the movable part of the exposure optical system repeatedly moves back and forth to scan the surface of the original. Since this is carried out only during the reciprocating operation, the time required to obtain one copy is substantially the time required for the reciprocating movement.

In order to shorten this time and improve copying efficiency, a method is conventionally known in which the speed of the backward movement in the above-mentioned reciprocating movement is made larger than the speed of the forward movement. Alternatively, the driving mechanism of the movable part of the exposure optical system becomes complicated, and the effectiveness is limited. SUMMARY OF THE INVENTION An object of the present invention is to provide a scanning exposure device for a copying machine that can expose the photoreceptor even during the backward movement of the reciprocating movement, in order to eliminate such drawbacks and improve the copying speed. .

Hereinafter, the present invention will be described by way of examples with reference to the drawings.

In FIG. 1, reference numeral 0 indicates an original to be copied, reference numeral 1 indicates a scanning exposure device according to the present invention, and reference numeral 2 indicates a photoreceptor.

The document 0 is laid flat on a document glass (not shown) with the document surface facing downward.

In this example, the photoreceptor 2 is formed into a drum shape, and its axial direction is oriented perpendicular to the drawing, that is, parallel to the document surface of the original ○, and is directed below the original ○ in the direction of the arrow. Rotatably arranged. The scanning exposure device 1 installed between the document ○ and the photoreceptor 2 includes plane mirrors 11, 12, 15,
16, 17, 18, 20, 21, an imaging through lens system 13, and prisms 14, 19 as roof-type reflecting mirrors.
and a light shielding plate 22. Each of these optical members is collectively referred to as an optical path component. this,
The main features of the present invention, which are embodied in the scanning exposure apparatus example, are the following three points.

That is, two sets of optical paths from the scanned portion of the document 0 to the circumferential surface of the photoreceptor 2 are formed by the above-mentioned optical path components.

These two sets of optical paths share the imaging through lens 13,
In addition, the arrangement of the optical path components is determined such that the light beams following each optical path enter the imaging through lens system from mutually opposite lens surfaces, and each optical path is
It has prisms 14 and 19 as roof-type reflecting mirrors, and the directions of the ridge lines of these prisms are 90 degrees different from each other. The plane mirrors 11, 12, 15, 16, the imaging through lens system 13, and the prism 14 form a first optical path,
Similarly, the plane mirrors 17, 18, 20, 21, the imaging through lens system 13, and the prism 19 form a second optical path.

The plane mirrors 11 and 17 are combined and integrated into a roof shape with their mirror surfaces facing upward, and are arranged parallel to the surface of the original with their ridgelines facing the original 0.

Therefore, without the light-shielding plate 22, if the illumination lamp (not shown) illuminates the portion of the document surface above the plane mirrors 11 and 17 of the document ○ in the form of a long and narrow slit in the direction perpendicular to the drawing, light from the illuminated portion will be removed. The reflected light beams are reflected in different directions by the plane mirrors 11 and 17, and then guided to the cylindrical surface of the photoreceptor 2 following different optical paths. The light beam reflected by the plane mirror 11 is reflected by the plane mirror 12 and then passes through the imaging through lens system 13 from the left side to the right side.

The light beam reflected by the plane mirror 17 is reflected by the plane mirror 18 and then enters the right lens surface of the imaging through lens system 13. The plane mirrors 11 and 17 are integrated with each other, but they can reciprocate along the document 0 in the left and right directions in the figure. During scanning, they move from the position shown in FIG. 1 to the position shown in FIG. It moves rightward to the position shown, and further moves leftward from the position shown in FIG. 2 to the position shown in FIG. In this way, these plane mirrors 11 and 12
Accordingly, scanning of the original 0 is performed, and in this sense, these plane mirrors 11 and 17 are referred to as scanning plane mirrors. The movement of the plane mirrors 11 and 17 is accompanied by the light shielding plate 22 and the aforementioned illumination lamp (not shown).

Scanning performed by moving the plane mirrors 11 and 17 to the right in the drawing is referred to as forward scanning, and scanning to the left is referred to as backward scanning. As shown in FIGS. 1 and 2, the light shielding plate 22 blocks reflected light from entering the plane mirror 17 during forward scanning, and
In the backward scan, the reflected light east is prevented from entering the plane mirror 11. Thus, the second optical path is blocked during forward scanning, and the first optical path is blocked during backward scanning.
Now, the plane mirrors 12 and 18 can reciprocate from left to right in the figure and from right to left in parallel to the document surface. That is, these plane mirrors 12 and 18 follow the movement of the scanning plane mirror at a moving speed that is 1/2 of the movement speed of the scanning plane mirror, and during forward scanning, they follow the movement of the scanning plane mirror as shown in FIG. It moves to the right from the position shown in Figure 2 to the position shown in Figure 2, and during backward scanning, it moves from the position shown in Figure 2 to the position shown in Figure 2.
Move to the left to the position shown in the diagram. These plane mirrors 12
, 18, the first and second optical paths and Z also move to the original ○
The length of the optical path from the scanned part to the imaging through lens system 13 is kept unchanged during scanning, and the angle of incidence of the optical beam on each optical path to the imaging through lens system 13 is also kept unchanged throughout the scanning. It will be done. In the first optical path, the light transmitted through the imaging through lens system 132 enters the prism 14 and is reflected, and then guided onto the circumferential surface of the photoreceptor 2 by reflection by the plane mirrors 15 and 16, and An image of the scanned portion of the document ○ is formed on the circumferential surface. On the other hand, in the second optical path, the light emitted from the imaging through lens 2 lens system 13 passes through the prism 1.
9, and after being reflected, it is guided onto the circumferential surface of the photoreceptor 2 by reflection by the reflecting mirrors 20 and 21, and on the same surface,
An image of the scanned area is formed.

The plane mirrors 16 and 21 are combined into a roof 3 shape with their mirror surfaces facing outward, and are arranged with their ridges facing the photoreceptor 2 and parallel to the photoreceptor spreading axis.

In both optical paths, the optical path components are fixed at predetermined positions and in predetermined postures on the mound space side of the imaging through lens system.

Now, the prisms 14 and 19 function as roof-shaped reflecting mirrors because the two surfaces combined in a roof shape with an angle smaller than 180 degrees are used as mirror surfaces.
The directions of the ridge lines formed by these two surfaces differ by 90 degrees between the prisms 14 and 19.

That is, the prism 14 has its ridgeline oriented in a direction perpendicular to the drawing, and the prism 19 has its ridgeline oriented in a direction perpendicular to the document surface of the document ○. of course,
The positions of the prisms 14 and 19 are constrained by the condition that they are in their respective optical paths and that the optical ridges of the scanned area are correctly imaged on the circumferential surface of the photoreceptor, and the orientations of their ridges are It does not mean that they can be placed in any position as long as they are 90 degrees apart. Now, the exposure of the photoreceptor 2 by this apparatus is performed as follows.

That is, when a document ○ is sent as shown in Fig. 1 and the counterfeit is activated, the photoreceptor 2 starts rotating in the direction of the arrow, and its peripheral surface is uniformly charged by a charger (not shown). To go. When the uniformly charged peripheral surface of the photoreceptor reaches the exposed area,
The scanning plane mirror starts forward scanning. An illumination lamp (not shown) emits light and follows the scanning plane mirror to illuminate the illuminated area, and the reflected light from the illuminated area is transmitted to the photoreceptor 2 through a first optical path that is not closed by the light shielding plate 22. The document light image of the scanned portion is successively projected onto the circumferential surface by the function of the imaging through lens system 13. In this way, a static exposure latent image corresponding to the document 0 is formed on the circumferential surface of the photoreceptor 2. Since the number of mirror surfaces existing in the optical path is an even number, and the moving direction of the photoreceptor peripheral surface in the exposure section and the forward scanning direction are the same, the electrostatic tank image formed on the photoreceptor peripheral surface can be developed. The visible image obtained is a mirror image when viewed from outside the photoreceptor, and is transferred onto the recording sheet as a normal image.

Now, when the forward scanning is completed, the light shielding plate 22 moves to open the second optical path and block the first optical path.

Then, the scanning plane mirror starts backward scanning.

This time, although the moving direction of the photoreceptor periphery and the scanning direction in the exposure section are opposite, the direction of the ridgeline of the prism 19 is
Since the direction of the ridgeline of the prism 14 in the first optical path is 90 degrees different, when reflected by the two mirror surfaces of the prism,
The direction in which the image is reversed is 90 degrees different from that in the first optical path, and as a result, a mirror image of the original is applied to the photoreceptor in this case as well. However, the visible image obtained by developing this mirror image is obtained by rotating the image obtained using the first optical path by 180 degrees around an axis perpendicular to the mating surface.

As described above, according to the scanning exposure apparatus according to the present invention, a document is scanned back and forth, and a predetermined optical image (a mirror image in the above embodiment) of the document is transferred to the photoconductor during both forward and backward scanning. The efficiency of copying can be significantly improved since the photoreceptor can be illuminated almost continuously.

Further, since scanning only needs to be performed at the same speed for both forward scanning and backward scanning, the drive mechanism for the movable part may be relatively simple. Other embodiments of the present invention will be briefly described below.

In the above embodiment, the optical path was switched using the light shielding plate 22, but the optical path may be switched as described below.

In the example shown in FIG. 3, there is a single scanning plane mirror, and this plane mirror 11 is shared by the first and second optical paths.

As shown in FIG. 3 0', this plane mirror 11 is swingable about an axis perpendicular to the drawing. This plane mirror 11
is rotated clockwise or counterclockwise within the swing range every time forward scanning or backward scanning is completed, thereby changing the direction of the mirror surface. Furthermore, in the example shown in FIG. 4, the single scanning plane mirror 11a is a double-sided mirror that can swing around an axis perpendicular to the drawing, and is shared by the first and second optical paths. .

The optical path can be switched by rotating the plane mirror 11a clockwise or counterclockwise each time scanning is completed (FIG. 4) to switch the mirror surface facing the document 0. It should be noted that in FIGS. 3 and 4, to avoid complication, the same reference numerals as in FIG. 1 are used for parts that are unlikely to be confused. In the above embodiment,
The original was scanned by moving the scanning plane mirror, but
It is also possible to scan the original by disposing the optical path components immovably and transporting the original itself back and forth.

In this case, the main part of the scanning means is constituted by the document conveyance means, but any known document conveyance means may be used as appropriate. Further, the roof-shaped reflecting mirror is not limited to the above-mentioned prism, but may be one in which two plane mirrors are combined into a roof shape. Furthermore, the present invention is applicable not only to drum-shaped photoreceptors, but also to
Of course, the present invention can also be applied to cases where a belt-shaped or sheet-shaped photoreceptor is used. In addition, the number of plane mirrors that constitute the optical path is
Needless to say, the method may be changed as appropriate depending on the design conditions of the apparatus and whether Masatoshi or a mirror image is to be administered to the photoreceptor.

[Brief explanation of the drawing]

FIG. 1 is a front view schematically showing only the essential parts of an embodiment of the present invention, FIG. 2 is a diagram for explaining the state during backward scanning in the above embodiment, and FIG. FIG. 4 is an explanatory diagram showing only the essential parts necessary for explanation of another embodiment. FIG. 4 is an explanatory diagram schematically showing only the essential parts necessary for explanation of yet another embodiment of the present invention. 0... Original document, 11, 12, 11a... Scanning plane mirror, 13... Imaging through lens system, 14
, 19... Roof type reflector. Rare 1 figure, seat 2 figure, seat 3 figure, rare 4 figure

Claims (1)

[Claims] 1. While scanning a document to be copied, an optical image of the document is
A scanning exposure device that irradiates onto a photoreceptor whose surface is moving in a fixed direction, in synchronization with the movement of the surface of the photoreceptor.
A scanning means for reciprocating a document, an imaging through lens system, and an odd or even number of plane mirrors that together with the imaging through lens system form a first optical path from the scanned area to the surface of the photoreceptor. A first roof-type reflecting mirror having a mirror surface angle smaller than 2 right angles shares the imaging through lens system with the first optical path, forming a second optical path from the scanned part to the surface of the photoreceptor. an odd or even number of plane mirrors and a second roof-type reflector having a mirror surface angle smaller than 2 right angles, which blocks the second optical path during forward scanning and blocks the first optical path during backward scanning; and an optical path switching means, in the first and second optical paths, the light beams traveling through the optical path components are arranged from opposite sides to each other,
By arranging the mirrors to be incident on the imaging lens system, and by making the directions of the ridge lines of the roof-type reflectors in each optical path different from each other by 90 degrees, it is possible to 1. A scanning exposure device for a copying machine, characterized in that a light image, either a mirror image or a normal image, of a document is projected onto the surface of a photoreceptor. 2. In claim 1, the first and second optical paths each have a pair of plane mirrors on the object space side of the imaging through lens, that is, in the document side space, and each of these pair of plane mirrors is The scanning plane mirror moves in a fixed direction along the surface, and the scanning plane mirror moves in a direction parallel to the moving direction of the scanning plane mirror in order to keep the optical path length and the angle of incidence of the light beam to the imaging through lens system unchanged. A plane mirror that follows the scanning plane mirror at a moving speed that is 1/2 of the moving speed of the plane mirror, and scanning of the original is performed by moving the pair of plane mirrors.
A scanning exposure device in a copying machine. 3 In claim 2, the scanning plane mirror is a single single-sided or double-sided mirror, and this scanning plane mirror is shared by the first and second optical paths, and the direction of the mirror surface can be switched or A scanning exposure device for a copying machine, characterized in that an optical path is selected by selectively using mirror surfaces on both sides. 4. Claim 1 is characterized in that the elements constituting the first and second optical paths are each fixed at a fixed position, and the document is scanned by transporting the document back and forth. A scanning exposure device in a copying machine.