JPH02308273A - Optical system of a copying machine with original reading function - Google Patents

Abstract

PURPOSE:To provide a compact copying machine in which light utilization efficiency is excellent and the aperture of a variable focal distance lens or an additional lens is not so large and whose cost is low by using the variable focal distance lens in common in a photosensitive body exposing mode and in an original reading mode and using transmitted light in both modes. CONSTITUTION:Reflection mirrors 2, 3, 4 and 6 and the variable focal distance lens 5 constitute an exposing optical system with a displacement mechanism 10. A solid state image pickup element 8 is disposed on an extension which is obtained by extending the optical axis of the lens 5 toward the back of the reflection mirror 6. In the original reading mode, the reflection mirror 6 is retreated from an optical path for exposing a photosensitive body with the counterclockwise turning. A read optical system is constituted of the reflection mirrors 2, 3 and 4, the variable focal distance lens 5 and the additional lens 9. An optical element from an original to the variable focal distance lens, that is, the reflection mirrors 2, 3 and 4 and the variable focal distance lens 5 are shared with an exposing optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system of a copying machine having a document reading function.

[Prior Art] A so-called analog copying machine functions by directly projecting an optical image of a document onto a photoreceptor to form an electrostatic latent image corresponding to the document, and by converting the document into an electrical signal by reading it. Copying machines that have the function of a digital copying machine that writes and forms an electrostatic latent image corresponding to a document on a photoreceptor using intensity-modulated laser light are being put into practical use.

In the case of such a copying machine that has both digital and analog functions, the imaging magnification of the optical image of the original projected onto the photoreceptor is around 172x to 2x, which is close to the same magnification with the analog copying function, whereas The magnification of the image formed on the solid-state image sensor for reading is approximately 115 to 1/10 times, and since the area of N image magnification does not overlap between analog and digital functions, exposure optical systems for analog are generally used. A separate digital reading optical system is required.

On the other hand, Japanese Patent Application Laid-Open No. 56-4116 discloses a system in which a single lens is used as both an imaging lens for a digital reading optical system and an imaging lens for analog.

[Problems to be Solved by the Invention] The imaging lens disclosed in JP-A-56-4116 uses a lens with a half-mirror surface, an in-mirror lens for reflected light, and an in-mirror lens for transmitted light. is used as a through lens, an in-mirror lens is used as an imaging lens for exposure, and a through lens is used as an imaging lens for reading.

For this reason, the light from the original is divided into two parts by the imaging lens, one for exposing the photoreceptor and the other for reading the original, and it is necessary to increase the diameter of the imaging lens to obtain the amount of light necessary for exposing the photoreceptor and reading the original. However, there are problems such as an increase in the size of the imaging lens, an increase in cost, and a decrease in the depth of the document surface.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a novel optical system for a copying machine having a document reading function.

[Means to solve the problem] One aspect of the present invention will be explained below.

The present invention is an optical system for a copying machine having a document reading function, and includes an exposure optical system and a reading optical system.

The "exposure optical system" is for exposing the photoreceptor, and projects an original optical image onto the photoreceptor.

The "reading optical system" is for reading a document, and forms a light image of the document on a solid-state image sensor.

The above exposure optical system includes a "variable focal length lens" that can change the imaging magnification near the same magnification, a "displacement mechanism" that displaces this variable focal length lens in the optical axis direction, and an image side of the variable focal length lens. It has a "reflector" that is placed in the mirror and can be retracted from the optical path for exposing the photoreceptor.

The reading optical system is arranged in front of the solid-state image sensor.
The optical element from the original to the variable focal length lens is shared with the optical element of the exposure optical system.

In the document reading mode, the reflecting mirror is retracted from the optical path for exposing the photoreceptor, and the variable focal length lens is displaced toward the solid-state image sensor by the displacement mechanism. The additional lens and the displaced variable focal length lens constitute an imaging optical system for reading.

The above-mentioned additional lens may always be placed at a predetermined position in front of the solid-state image sensor, or it may be moved in and out of the position in front of the solid-state image sensor so that it can move in and out of the solid-state image sensor in front of the solid-state image sensor according to the evacuation and return of the 5 reflecting mirror. If you want to make it possible for the additional lens to enter and exit the predetermined position,
The additional position of the additional lens may be set on the object side of the variable focal length lens.

[Function] As mentioned above, when performing analog copying, the optical image of the original can be projected onto the photoreceptor by the imaging effect of the variable focal length lens alone, and the imaging magnification can be varied in the magnification range near the same magnification. can.

When reading a document, a light image of the document is formed on a solid-state image sensor by a reading imaging optical system composed of a variable focal length lens and an additional lens. By combining the variable focal length lens with an additional lens, an imaging magnification outside the original imaging magnification range can be realized.

[Examples] Hereinafter, specific examples will be described with reference to the drawings.

FIG. 1 diagrammatically shows one embodiment of the invention.

FIG. 1 (1) shows a mode when analog copying is performed.

An original 0 to be copied is placed flatly on an original glass 1.

Light from the original is guided to the photoreceptor 7 via the reflecting mirrors 2, 3, 4, variable focal length lens 51 and reflecting mirror 6, and the optical image of the original is formed on the photoreceptor 7 by the action of the variable focal length lens 5. Form an image.

To scan the original O, the reflecting mirror 2 may be moved to the right, and the reflecting mirrors 3 and 4 may be integrally moved to the right at a speed of 172 times the moving speed of the reflecting mirror 2, or the reflecting mirrors 2, 3, . 4 may be fixed and the document glass 1 and the document 0 may be moved to the left.

When performing such analog copying, the variable focal length lens 5 can change the imaging magnification in a magnification range of about 172 to 2 times, and can change the magnification and the displacement of the lens position accompanying the magnification change. The displacement of the variable focal length lens 5 accompanying the zero magnification switching performed by the displacement mechanism 10 is performed in the optical axis direction of the lens 5.

The reflecting mirrors 2, 3, 4, and 6 and the variable focal length lens 5 together with the displacement mechanism IO constitute an exposure optical system. A reflecting mirror 6 is located on the image side of the variable focal length lens 5 and reflects the imaging light beam onto the photoreceptor 7 so as to turn it back toward the photoreceptor 7.
can swing around a swing shaft 6A, and can be displaced by a swing mechanism (not shown).

A solid-state image pickup device 8 is disposed on an extension line of the optical axis of the variable focal length lens 5 toward the rear of the reflecting mirror 6.

FIG. 1 (II) shows the state of the optical system in the document reading mode of this embodiment. In this state, the reflecting mirror 6 is retracted from the optical path for exposing the photoconductor by rotating counterclockwise. Therefore, the light transmitted through the variable focal length lens 5 is directly inserted into the additional lens 9 (in response to switching to the fM document reading mode, from the standby position shown by the broken line to the position shown in the figure, that is, the position in front of the solid-state image sensor). ) onto the solid-state image sensor 8. The variable focal length lens 5 and the additional lens 9 constitute an imaging optical system for reading at the positions shown in the figure.
That is, it is displaced to the vicinity of the additional lens 9 by the displacement means lO.

In other words, the reading optical system is composed of one reflecting mirror 2, 3, 4, a variable focal length lens 5, and an additional lens 9.
The optical elements from the original to the variable focal length lens, ie, the reflecting mirrors 2, 3, 4, and the variable focal length lens 5, are shared with the exposure optical system.

The imaging magnification of the imaging optical system for reading using the variable focal length lens 5 and the additional lens 9 is about 175 to 1710.

By scanning the original in the same manner as in the case of photoreceptor exposure, the original can be read by the solid-state image sensor 8. As described above, the additional lens 9 may be always fixedly disposed in front of the solid-state image sensor, or the additional lens may be placed on the object side of the variable focal length lens 5.

In the embodiment described above, the reflector 6 was rotated to retreat from the optical path for exposing the photoconductor, but as in the embodiment shown in FIG. In order to withdraw the mirror 61 from the optical path for exposing the photoreceptor, it may be displaced translationally from the position shown by the broken line to the position shown by the reference numeral 61A or 61B.

Further, the number of reflecting mirrors forming the optical path of the exposure optical system may be an even number, and as in the embodiment shown in FIG. Various modifications are possible, such as combining the three reflecting mirrors 6, 11, and 12 on the image side of the lens and constructing the optical path of the exposure optical system with six reflecting mirrors.

Further, the lens arrangement of the variable focal length lens is controlled to take the optimum arrangement when used in combination with an additional lens.

[Effects of the Invention] As described above, according to the present invention, a novel optical system for a copying machine having a document reading function can be provided.

This optical system uses a variable focal length lens in common in the photoreceptor exposure mode and original reading mode, but since transmitted light is used in both modes, the light utilization efficiency is high, and the variable focal length lens and additional lenses are also used. It does not require a large diameter, and can be realized compactly and at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIG.
The figure shows another embodiment, and FIG. 3 shows another embodiment.

110. Original glass, 2, 3, 4, 6. ,,reflector,5
50. Variable focal length lens, 711. Photoreceptor, 803.
Solid-state image sensor! , I Cyo] (I) (I) Ryo? ■ Brother 3 ■

Claims (1)

[Scope of Claims] The above-mentioned exposure optical system has an exposure optical system for exposing a photoreceptor to project an optical image of the original onto a photoreceptor, and a reading optical system that forms an optical image of the original onto a solid-state image sensor. The system includes a variable focal length lens that can change the imaging magnification near the same magnification, a displacement mechanism that displaces the variable focal length lens in the optical axis direction, and a mechanism that is arranged on the image side of the variable focal length lens for exposing the photoreceptor. The reading optical system has an additional lens disposed in front of the solid-state image sensor, and the optical element from the original to the variable focal length lens is connected to the exposure optical system. In document reading mode, the reflecting mirror is retracted from the optical path for exposing the photoconductor, and the variable focal length lens is displaced toward the solid-state image sensor by the displacement mechanism, and the variable focal length lens is shared with the additional lens. 1. An optical system for a copying machine having a document reading function, characterized in that an imaging optical system for reading is constituted by a focal length lens.