JPS59152434A - Exposure optical device - Google Patents

Abstract

PURPOSE:To make a device compact by placing a lens array sideways against an optical path of a luminous flux coming from an original. CONSTITUTION:The first mirror 24 for magnification and a magnifying lens array 27, the first mirror 25 for unmagnification and an unmagnifying lens array 28, the first mirrror 26 for reduction and a reducing lens array 29, and the second common mirror 30 are provided respectively under an original face 21, and an electrophotographic photosensitive drum 31 is provided under the mirror 30. In order to obtain a uniform illuminance distribution on the surface of the photosensitive drum at the time of a variable power, the mirrors 24, 26 are provided with light shielding plates 41, 42 having a projected tip. An illuminating lamp 22 and a main illuminating shade 23 being a shade of this lamp 22 are provided at a slightly upper part of the mirrors 24, 25 and 26. The magnifying lens array 27 and the reducing lens arrays 29 are arranged to make the optical axis of the array lens sectorial in the direction vertical to the paper face, and the unmagnifying lens array 28 is arrayed to make parallel the optical axis of the lens array.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable magnification slit exposure optical device using a small-diameter lens array, and particularly to a variable-magnification slit exposure optical device that uses a plurality of lens arrays that transmit images at different magnifications for each aperture. The present invention relates to a compact slit exposure optical device that performs magnification switching to form an original image on an image forming surface.

Conventionally, image forming devices such as copying machines and facsimile machines often use exposure optical devices that use small-diameter rod-shaped refractive index focusing imaging elements (trade name: SELFOC) or bar lens lens arrays. . Such lens arrays are commonly used to transmit images at a 1:1 magnification. ``For a lens array having a magnification of 1:1, a lens array that creates a reduced image or an enlarged image is disclosed in Japanese Patent Application Laid-Open No. 16415/1983. JP-A-57-16415 discloses an apparatus as shown in FIG. 1 as an example of an exposure optical apparatus using a lens array that produces a reduced or enlarged image.

In FIG. 1, 1 is a document, 2 is a reduction lens array, and 3 is an image forming surface, that is, a photoreceptor. The small-diameter lens at the center of the lens array 2 is almost perpendicular to the object plane, that is, the surface of the original 1, and the image forming surface, that is, the surface of the photoreceptor 3, and the small-diameter lenses that continue next to each other are fan-shaped toward the ends of the lens array 2. The image 1.i of the original 1 is reduced in size, and the surface of the photoreceptor 3 is The statue of a neck above me is pitiful.

In order to perform magnification switching,
No. 5 discloses a variable power switching concept λ structure as shown in FIG. In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals. In FIG. 2, reference numeral 2 indicates the above-mentioned ear small lens array, 4 indicates an equal-circumference lens array, 5 indicates a fluorescent lamp for illumination, and 6 indicates a tri-1iii supplementary reflection mirror. As shown in the figure, a reduction lens array 2 and an equal-circumference lens array 4 are arranged below the document 1, and a photosensitive drum 3 is arranged below the lens array 2. A fluorescent lamp 5 for illumination and a mirror 6 for reflecting the illumination are provided at a suitable position near the lamp. The magnification changeover is performed by moving the lens array 2.degree. 4 in parallel in the direction of arrow 7.

However, as described above, multiple lens arrays that transmit images at different magnifications are arranged so that their optical axes are approximately perpendicular to the surface of the document and the image forming TKI.
In other words, a configuration in which the lens arrays are arranged so as to be parallel to the light flux coming from the original and switched in a direction parallel to the light flux by moving the lens arrays in the lateral direction with respect to the light flux is as follows. There are some drawbacks. That is, in the conventional 1'1 configuration, the distance between the document surface and the photosensitive drum must be matched to the conjugate length of the lens array, which has the disadvantage that the apparatus cannot be made compact. Furthermore, since the conjugate length of the lens array during magnification must match the conjugate length of the lens array during zooming, there is a drawback that the mechanism becomes complicated. Furthermore, in a lens array of equal magnification, the illuminance distribution of the light beam transmitted through the lens array is uniform, but in a zoom lens array, each small diameter lens has a narrow shape as shown in Figure 1. v
C. The small-diameter lenses other than the central portion are deviated from perpendicular to the surface of the document L and the surface of the photosensitive drum 30, so that the illuminance distribution of the light beam transmitted through the equal-borrowed lens array is as shown in the straight line 8, as shown in FIG. Although it is uniform as shown, there is also a drawback that the illuminance distribution of the light beam transmitted through the reduction lens array differs between the center and the periphery as shown by the curve.

The present invention is a conventional exposure optical system! (The purpose is to eliminate the drawbacks in (a) and (b), and by arranging the optical axis of each lens array horizontally with respect to the optical path of the light beam coming from the original, it is possible to construct a condensed slit optical system. It is an object of the present invention to provide an exposure optical device in which the conjugate length of the equal borrowed lens array and the conjugate length of the variable magnification lens array are made different, and the magnification can be changed by switching the mirrors. According to the present invention, a light shielding plate having a convex shape at the center is provided on the mirror for guiding the light flux coming from the original to the lens array for variable magnification.Thus, by VC, uniform exposure of 1% on the optical drum surface is achieved even when changing the magnification. An object of the present invention is to provide an exposure optical device that can obtain a large amount of light.

That is, the exposure optical device according to the present invention is characterized in that the exposure optical device focuses an original image on an image forming surface by selectively using a plurality of lens arrays that transmit images at different magnifications. The optical axis of each lens array is arranged horizontally with respect to the optical path of the light beam coming from the original,
A plurality of first mirrors are provided on the optical path to guide the light flux to each lens array, and a mirror 1 that guides the light flux transmitted through each lens array to the image forming surface.
This is because two second mirrors are provided, and magnification switching is performed by switching the first mirror and rotating the second mirror.

The present invention will be described below with reference to the drawings.

FIG. 4 is a diagram showing the principle of the present invention. In Figure 4, 11
has a slit extending perpendicular to the paper surface on the document surface.

15, 16, and 17 are lens arrays for enlarging, equal-magnification, and reducing, respectively, and these lens arrays are arranged horizontally with respect to the optical path of the light beam coming from the object point 11 on the document surface. .

Reference numerals 12, 13, and 14 denote first mirrors arranged on the optical path to guide the above-mentioned light beams to lens arrays 15, 16, and 17, respectively. It is possible to switch to 18
is a second mirror that guides the light beams transmitted through the respective lens arrays 15, 16, and 17 to the image forming surface 19, and this mirror can be rotated as shown by arrows C and D.

In FIG. 4, for equal magnification exposure, the first mirror 12 is
Therefore, the light beam from the object point 11 is reflected by the first mirror 13, passes through the equal frequency array lens 16, is reflected by the second mirror 18, and comes to the imaging plane 19. During magnification exposure, the first mirror 12 does not move, the second mirror 18 rotates in the direction of the arrow, and the light beam from the object point 11 is reflected by the first mirror 12 and passes through the magnification array lens 15. Second mirror 18
It is reflected at the image forming surface 19. During reduction exposure, the first
The mirror 12 moves toward A, the first mirror 13 also moves toward B, and the second mirror 18 rotates in the direction of arrow C. The light beam from the object point 11 is reflected by the mirror 14 and becomes a reduction play lens. 17, is reflected by a second mirror 18, and comes to an imaging plane 19.

By configuring the optical system as shown in FIG. 4, it becomes possible to narrow the distance between the optical system in the vertical direction, that is, in the upper and lower directions on the plane of the paper, and it becomes possible to create a continuous system. Furthermore, each array lens can be adjusted separately, making it easy to determine the conjugate length. The illuminance distribution that illuminates the surface of the original document can be made uniform in the longitudinal direction of the lens array, and when changing the magnification (reducing or enlarging), the illuminance is reduced on a portion of the mirror and at the center of the lens array. By providing a member that increases the peripheral illuminance, it is possible to make the illuminance distribution uniform in the longitudinal direction of the lens array on the photosensitive surface even during zooming.

FIGS. 5 and 6 show embodiments of the present invention. In FIG. 5, below the document surface 21, there are a first mirror 24 for magnification, a lens array 27 for magnification, a first mirror 25 of equal magnification, a lens array 28 for equal cans, and a first mirror 26 for reduction. A reduction lens array 29 and a common second mirror 30 are provided, and an electrophotographic photosensitive drum 31 is provided below the mirror 30. In order to obtain a uniform illuminance distribution on the photosensitive drum surface during zooming, the mirrors 24 and 26 are provided with light plates 41 and 4 having convex tips as shown in FIG.
2 is attached. Miller 24, 25.

A main illumination umbrella 23 which is an umbrella for the illumination lamp 22 and this illumination lamp 022 is provided slightly above the illumination lamp 26 . Here, the enlarging lens array 27 and the reducing lens array 2
9 (is a direction perpendicular to the plane of the paper (that is, a direction perpendicular to the document scanning direction and the drum rotation direction), and the optical axis of the array lens is arranged in a fan shape. are arranged so that the optical families of the array lenses are parallel (however, in each array 27, 28, 29, the direction in which a large number of small diameter lenses are arranged (is the direction perpendicular to the plane of the paper).

The light from the illumination lamp 22 is irradiated onto point Q on the original 21 by the main illumination umbrella 23, and the reflected light beam is reflected by the first mirrors 24, 2.
5.26 to the lens arrays 27, 28, and 29, and the second lens 30 forms an image on a point P on the photosensitive drum 31. Mirrors 24.25 are mirrors 12.25 in FIG.
13, and the mirror 30 is configured to be rotated like the mirror 18 in FIG.

The optical path for enlargement is Q-24-27-30-P, the optical path for equal frequency is Q-25-28-30-P, and the optical path for reduction is Q-26-29-30-P (not shown). The mirrors 24, 25 are switched and the mirror 30 is rotated by the means.

The operation of Kinobo and Akira's device having the above structure will be described below.

The electrophotographic photosensitive drum 31 rotates in the direction of the arrow, and is first charged by a charger 32, and then charged by the first mirror and lens array 24.27 or 25.28 or 26.29 and the second mirror 30. A light image is subjected to slit exposure at a selected magnification, thereby forming an electrostatic latent image. Note that the original 21 is moved in the direction of the arrow for scanning. The latent image is developed by a developing device 33, and the resulting toner image is transferred onto a sheet of paper 35 by a transfer charger 34. The toner image transferred to the paper 35 is fixed by a fixing device 36, while the surface of the drum 31 after the transfer is cleaned by a cleaning device 37 and reused for the above-mentioned copying process.

However, when this device is in operation, when performing projection at the same magnification, the mirror 24 is moved by a mechanism not shown, as shown in FIG. 5, and the optical path is changed to Q-25-28-3
It is used by setting it to 0-P.

Next, during magnification, the mirror 24 remains at the position shown in FIG. 5, and the mirror 30 rotates, so that the optical path is
7-30-P and used. At this time, mirror 2
4 has a light shielding plate 41 in the shape shown in FIG. 6.
Therefore, the illuminance distribution becomes uniform on the drum surface in the direction perpendicular to the paper surface.

As explained above, according to the present invention, by arranging the lens array horizontally with respect to the optical path of the light beam coming from the original, it is possible to make the exposure optical device compact. can be adjusted independently, and the conjugate length of the lens array for equal cans and the conjugate length of the lens array for variable power can be easily adjusted. The first one for variable magnification
By providing a light shielding plate on the mirror, it is possible to obtain a uniform exposure amount on the photosensitive surface even when changing the magnification.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram showing a conventional exposure optical device using a lens array that creates a reduced image, and Fig. 2 is a side view showing a magnification changing structure using the device shown in Fig. 1. , Fig. 3 is a diagram showing the illuminance distribution of the light beam transmitted through the lens array for equal cans and variable magnification, Fig. 4 is an explanatory diagram showing the principle of the invention, and Fig. 5 shows an embodiment of the invention. The side view, FIG. 6, is a diagram showing a light shielding plate used in the embodiment of FIG. 5. 1... Original body 2... Lens array 3.
・Photoreceptor 4...Lens array 5...Fluorescent lamp 6...Auxiliary reflecting mirror 12.13.
14... Sting A 1 Mira -15.16.
17... Lens array 18... Second mirror 19... Image forming surface (
Image forming plane) 22...Illumination rung 23...Umbrella 24
．． 25.26...First mirror 27.28.29...Lens array 30...Second mirror 31...Photosensitive drum 3
2... Band @ device 33... Developing device 34...
Transfer charger 35...Paper 36...Fuser
37...Cleaning equipment fee for 1 person per week Teru Goyama
Male -1- Not many small + 11: J □ Town □ Koshinbe Koji - 1 Figure / Suspension 2 Figure Ll, 3 ■ Figure 4 2-, J5 Figure 1,, 6 i2<1

Claims (1)

[Claims] In an exposure optical device that selectively uses multiple lens arrays that transmit images at different magnifications to form an original image on an image forming surface, the optical axis of each lens array is aligned with the optical path of the light beam coming from the original. A plurality of first mirrors are provided on the optical path to guide the light beams to the respective lens arrays, and a second mirror is provided to guide the light beams transmitted through the respective lens arrays to the image forming surface. 1. An exposure optical apparatus characterized in that a mirror is provided and magnification switching is performed by switching the first mirror and rotating the second mirror.