JPS6014225A - Optical system of slit exposure type electrophotography copying machine - Google Patents

Abstract

PURPOSE:To lead selectively the light of two direcions to a photosensitive body in a state that the element of an optical system remains fixed, by placing a prism in an optical path for leading selectively the light of two directions to the photosensitive body. CONSTITUTION:Two exposing optical systems 20a, 20b are provided on the right and left in a copying machine 1, and the light which has scanned an original on platen glasses 2a, 2b is led to an exposing area of a photosensitive body 4 of the lower part through a prism 24 provided on an optical path, two shutters 25a, 25b for cutting off so as to be openable and closable, the optical paths of the exposing optical systems 20a, 20b respectively, and a slit 27 of the lower part of the prism 24. The shutters 25a, 25b are operated selectively by shutter solenoids 26a, 26b, respectively, therefore, for instance, by moving to the right the exposing optical system 20b of the side where the shutter 25b is opened by the shutter solenoid 26b, a slit image of an original 17 is projected continuously and successively onto the photosensitive body 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application' The present invention relates to a slit exposure type electrophotographic copying machine having two optical systems.

BACKGROUND OF THE INVENTION In the optical system of a conventional slit exposure type electrophotographic copying machine, a plane mirror has been used to reflect light and change the direction of the optical path.

A plane mirror has a simple structure and is low in cost.1 For example, as shown in FIG. This is impossible because it interferes with the optical path of the plane mirror 02b.
Also, in order to avoid interference between both plane mirrors 02a and 02b,
The distance between both plane mirrors 02a102b is widened, and the plane mirrors 02a and 102b collide with each other obliquely to the normal to the surface of the drum-shaped photoreceptor 01, and this deviation distorts the original image. Also, both plane mirrors 02
Since a, 02b interfere with each other, plane mirrors o2a, o
The range of the incident angle of light with respect to 2b is narrower, and the width of the exposure light beam is narrower.

In order to eliminate this inconvenience, one plane mirror 02
When reflecting light at point a, it is sufficient to move or tilt the other plane mirror 02b so that it is located outside the range of the optical path. It is difficult to fix the document, and this causes a shift in the optical path length and optical axis of the optical system, making it difficult to form a clear slit original image without distortion on the photoreceptor.

OBJECT OF THE INVENTION The present invention relates to an improvement of the optical system of a slit exposure type electrophotographic copying machine that overcomes the above-mentioned drawbacks. The object of the present invention is to provide an optical system with a simple structure that can guide the light to the photoreceptor.

Structure of the Invention The present invention provides a slit exposure type electrophotographic copying machine that performs copying by exposing an original image to a photoreceptor through a slit, in which a prism is disposed in the optical path that selectively guides light from two directions to the photoreceptor. It is characterized by:

EXAMPLE An example of the present invention illustrated in FIGS. 2 and 3 will be described below.

Reference numeral 1 denotes a slit exposure type dry electrophotographic copying machine equipped with two sets of exposure optical systems 20a and 20b 7 on the left and right sides, and platen glasses 2a and 2b are installed on both left and right sides of the top of the copying machine 1. , 2b, platen covers 3a, 3b are provided so as to be openable and closable.

Also, in the center of the copying machine 1, there is a drum-shaped photoreceptor 4.

A charging corotron 5, an exposure area 6. Developing device7. Transfer corotron 8° Peeling corotron 9. A static eliminating corotron 1o and a cleaning device 11 are provided.

Furthermore, two sets of exposure optical systems 20a are provided on one side of these.

20b are arranged on the left and right, and the same exposure optical system 20a.

Reference numeral 20b denotes exposure lamps 21a and 21b that illuminate the lower surface of the document J8 on the platen glass 2, and the exposure lamp 21a.
, 21b and diffusely reflected on the lower surface of the original 18, mirrors 22a and 22b successively reflect the light irradiated by the mirrors 22a and 21b.
A lens 23at23b, a prism that guides these lights to the exposure area 6 of the drum-shaped photoreceptor 4 below, and two shutters 25a125b that can open and close the optical paths of the exposure optical systems 20a and 20b, respectively. It consists of shutter solenoids 26a and 26b that drive the shutters 25a and 25b to open and close, respectively, and a slit 27 disposed below the prism 24.For example, the shutter 252 is exposed on the side where the shutter 252 is opened by the shirt turn lens 26a. By moving the optical system 20a to the right, the slit images of the original 17 are sequentially transferred to the drum-shaped photoreceptor 4.
It is designed to be continuously projected upward.

The prism 24 has a regular triangular cross section, is made of glass with a refractive index of 1.6, and is set so that light can enter the surface of the prism 24 at an incident angle θ1 of 8°. has been done.

Further, paper feed trays 12a and 12b are arranged in two stages, upper and lower, on the right side 1 of the developing device 7.
After any of the sheets of paper 18 stored in the paper feeder 13 is sent to the drum-shaped photoreceptor 4 and transferred.

The image is sent to a fixing device 14 and fixed thereon.

Further, the copy is exposed by either one of the exposure optical systems 20a and 20b and fixed by the fixing device 14.

A switching finger 15 is used to switch and send the light to either one of the trays 16 (L, 16b) corresponding to the exposure.

Furthermore, a movable piece of a paper ejection switching solenoid (not shown) is connected to the switching finger 15, and when the paper ejection switching solenoid is not operating, the switching finger 15 is swung upward, and the copies are transferred to the lower tray. 16. When the paper discharge switching solenoid is operated, the switching finger 15 is swung downward and the copy is sent to the upper tray 16b.

Since the embodiment shown in FIGS. 2 and 3 is constructed as described above, the left platen cover 33 is opened and the original 17 is placed on the platen glass 2a.

After closing the platen cover 384, the left exposure optical system 20
When A and the main body of the copying machine are operated, the original image on the left side platen glass 2a is exposed in the form of a slit onto the drum-shaped photoreceptor 4 via the left side exposure optical system 2a. The document 1 is continuously projected onto the body 4 and the document 1 is projected onto the paper 18.
After the toner image No. 7 is transferred.

The image is fixed by the fixing device 14 and sent to the lower tray 17a.

In this case, as shown in FIG. 3, the light passing through the exposure optical system 20 is incident on the first surface of the prism 24 at an incident angle θ of 8°, so the prism The refraction angle θ2 in the path is approximately 5°.

The light hits the second surface of the prism 24 at an angle θ3 of 55°, and the critical angle of the prism 24 with a refractive index of 16 is 38.
Since it exceeds 7Y, it is totally reflected on the second surface of the prism 24 and forms an angle θ4 of 5° with respect to the third surface of the prism 24.
The light is refracted by this surface and exits at an exit angle θ5 of 8°.

In this way, the output angle θ of 8° with respect to the third surface of the prism 24 is
, the light is emitted from the exposure area 6 of the drum-shaped photoreceptor 4.
Since the original image is formed at an angle 82'' that is nearly perpendicular to the surface of the exposure area 6, distortion of the image due to a deviation in the angle formed by the light with respect to the normal to the surface of the exposure area 6 is small.

Furthermore, since the prism 24 may remain fixed, even if either the left or right exposure optical system 20a, 20b is switched, the optical path will not shift due to this switching.

In the above example, the cross-sectional shape is a regular triangle and the refractive index is 1.6.
Although the prism 24 is used, a prism having an appropriate cross-sectional shape such as an isosceles triangle and a refractive index of an appropriate value may also be used.

Alternatively, light may be passed through one exposure optical system and laser light may be passed through the other exposure optical system.

Effects of the Invention In the present invention, in a slit exposure type electrophotographic copying machine that performs copying by slit exposure of an original image onto a photoreceptor, a prism is disposed in the optical path that selectively guides light from two directions to the photoreceptor. Therefore, there is no need to rotate or move the optical system's mirrors or prisms.

The prism can selectively refract and reflect 10,000 of the light in the two directions and guide it to the photoreceptor, making it possible to prevent optical path errors due to rotation and movement of the optical system.

Further, in the present invention, since the optical path is deflected in two directions by the prism, the angle formed by this optical path can be set over a wide range to guide light to the photoreceptor.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a case where two plane mirrors are used to guide light from two directions to a photoreceptor, and FIG. 2 is an illustration of an embodiment of the optical system of a slit exposure type electrophotographic copying machine according to the present invention. FIG. 3 is an enlarged side view of the main part. 1...Slit exposure type dry type electrophotographic copying machine, 2...
platen glass, 3... platen cover, 4... drum-shaped photoreceptor. 20... Exposure optical system, 21... Exposure lamp, 22.
··mirror. 23... Lens, 24... Prism, 25... Shutter, 26... Shutter solenoid, 27...
·slit. Agent: Patent Attorney Ehara, 1 person penalty, 1 figure

Claims (1)

[Claims] A slit exposure type electrophotographic copying machine that performs copying by slit exposure of an original image onto a photoreceptor, characterized in that a prism is disposed in the optical path that selectively guides light in two directions to the photoreceptor. Optical system of electrophotographic copying machine.