JPS61184526A - Copying machine provided with optical system shielding member - Google Patents

Abstract

PURPOSE:To prevent reaching of irregularly reflected light from the original surface to a photosensitive body by providing a shading device that prevents the incidence of incident light on a detecting device to the back of a lens optical system in a part of the moving lens optical system. CONSTITUTION:An original density detecting member 21 and an original size detecting member are fixed in parallel at the same height with a lens 10 on the side of the image forming lens 10. The lens 10 is housed in a dark box 10a long in lateral direction to prevent reaching of reflected light from the original surface so as not to reach directly the lens 11, and moves in left and right direction along the optic axis 30 of the optical system in accordance the with variable power. Detecting members 21, 22 are fixed with a support 20 at angles directed respectively to the original surface at positions off from the dark box 10a by a space 23. An optical system shielding member 24 provided in the dark box 10a is placed at a position that covers the rear of the space 23 and the back of the support to check arriving of reflected light from the original surface that passed the space 23 at the photosensitive body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying machine equipped with an optical system light shielding member in which the structure of a light shielding device disposed in the optical system of the copying machine is improved.

[Conventional technology]

When a copying machine is used to make a normal size copy, the selection of the image density, as well as the size of the recording paper required, is determined by the user's experience and satisfactorily results are obtained.

However, when switching to variable magnification copying to enlarge or reduce the original surface, it is necessary to use same-size recording paper or copy without converting the image density. There are many cases where mistakes are made.

For this reason, especially in variable-magnification copying machines, based on the respective information regarding the original size and original density, recording paper of a size suitable for the image area to be copied is selected, and the photoreceptor is charged in order to obtain the appropriate image density. 2. Description of the Related Art Copying machines have been provided that have the ability to perform various density controls.

Information regarding the size or density of these originals is obtained by a detection member such as a sensor placed in the optical system of the copying machine detecting the reflected light from the surface of the original that is pre-scanned by an exposure lamp. Due to their characteristics, these detection members are often fixedly provided near the imaging lens at an angle oriented toward the original image.

On the other hand, the imaging lens is housed in a large dark box to prevent excess light caused by diffuse reflection from the document surface from directly reaching the photoreceptor from around the imaging lens. Although the dark box can be placed in a forward or backward position, a slight gap is required between it and the fixed detection member group in order to move the dark box. This gap is in the form of a narrow slit, but it can be enlarged by the movement of the imaging lens during zooming, and also because it is located near the optical axis of the optical system, there is no excess leakage from it to the rear. The amount of light cannot be ignored and causes harmful fog on the photoreceptor, impairing image contrast and deteriorating the quality of copies.

[Problem that the invention seeks to solve]

The present invention always shields the gap between the imaging lens and each of the detection members for detecting the document described above, regardless of the position of the imaging lens that moves as the magnification changes, so that diffusely reflected light from the surface of the document does not reach the photoreceptor. The purpose is to provide a copying machine with

[Means for solving problems]

The present invention provides an elastic light-shielding member that can move together with the imaging lens as the magnification changes, so that it is located on the detection section and the back surface of the material, and when the imaging lens moves forward during enlarged copying, The light shielding member contacts the substrate of the detection member and is elastically deformed to close the gap with the imaging lens. In a copying machine installed nearby, a light shielding means for preventing light incident on the detection means from entering behind the lens optical system is provided in a part of the movable lens optical system. This is achieved by a copying machine equipped with a system light shielding member.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 and 2.

At the top of the copying machine main body 1, there are arranged an original tray 2 made of transparent glass on which a document tray is placed, and a platen cover 3 that covers the original tray after the document tray is placed on the document tray 2.

A first mirror unit 6 including an exposure lamp 4 and a first mirror 5 is provided below the original table 2 and inside the copying machine body 1, and is arranged parallel to the document table 2 and toward the right in the drawing. It is installed so that it can move in a straight line and optically scans the entire surface of the document tray.

Further, 7 and 8 are a second mirror and a third mirror, respectively, and a second mirror unit 9 is formed by integrating these mirrors.
The first mirror unit 60 is configured to maintain a predetermined optical path length.
move in a straight line to the right at speed A. Of course, the movement of the second mirror unit 9 is parallel to the original table 2, similar to the first mirror unit 6. The reflected light from the original on the original placing table 2 is reflected by the first mirror 5, the second mirror 7, and the third mirror 8, and then passes through the imaging lens 10 and the fourth mirror 11, which are moving lens optical systems, and is exposed to light. The light is incident on the body drum 12.

Figure 1 shows the initial position of the optical system when copying at the same magnification, but when enlarging or reducing copying, it is necessary to increase the projection distance according to each magnification. The second mirror unit 9 is placed at a position moved to the left, while the imaging lens 0 is placed at a position moved leftward in the case of enlarged copying and rightward in the case of reduced copying. The above-mentioned optical scanning is then performed.

A detection member 21 as an original density detection means and a detection member n as an original size detection means are fixed to the side of the imaging lens 10 in parallel at the same height as the imaging lens 10. , the details of which are shown in the plan view of FIG. That is, the imaging lens IO allows the reflected light from the document surface that does not pass through the imaging lens 10 to directly pass through the fourth lens.
It is housed in a transversely long dark box tOa so as not to reach the mirror 11, and is moved in the left-right direction along the optical axis (9) of the optical system as the magnification is changed.

A detection member 2 is located at a distance n from the dark box 10a.
1 and 22 are each fixed at an angle facing the document surface by adding a support member, and at a position beyond the gap and covering the back surface of the support member, there is a light shielding means of the present invention provided in the dark box LQa. An optical system light shielding member is disposed to prevent light reflected from the surface of the document that has passed through the gap n from reaching the photoreceptor 12.

The optical system light shielding member is an elastic member made of a black-treated thin metal plate, a black resin plate, etc., and is connected to the support fitting 5.
As shown through! It is fixed to the dark box tOa with an inclination angle of 45 degrees.

The optical system light shielding member 24 has a length and width such that even if the imaging lens 10 moves to the right due to reduction copying, the reflected light entering the gap will not directly enter the fourth mirror 11. On the other hand, when the imaging lens 10 is moved to the left for enlarging copying, the optical system light shielding member 21 and 22 are sized as shown by the dashed line. By slidingly contacting the side edge of the support member to which the support member is attached, the support member is curved over its entire width, and as a result, the gap is forcibly closed.

Further, when the imaging lens IO returns to the same magnification position, the optical system light shielding member 24 returns to its flat shape due to its elasticity, as shown by the solid line in FIG. When the image lens lO occupies a position corresponding to the same magnification or reduction magnification, it is placed in a state where it can block the reflected light incident from the gap n and prevent it from directly reaching the photoreceptor. In this embodiment, a dark box 10ak:J light member is provided, but a light shielding member may be provided in the imaging lens frame.

As is clear from the above description, the present invention utilizes extremely simple members to prevent harmful reflected light that is not involved in the projection of the imaging lens from reaching the photoreceptor, thereby increasing the contrast of the copied image. This is useful for improving the quality of copies.

〔Effect of the invention〕

According to the present invention, even in a variable-magnification copying machine that incorporates each detection member for document detection in the optical system, reflected light from the document surface that is harmful to image formation can be removed, and the entire range from full-size copying to variable-magnification copying can be achieved. Copies with excellent image quality can be obtained over the entire period.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of an optical system of a copying machine according to the present invention. Figure 2 is a plan view of the main part. 10...Imaging lens lOa...Dark 1
f addition...Supporting member 21.22...Detection member...Gap Sae...Light shielding member 5...Supporting metal fitting (9)... (Optical system) Optical axis Applicant Konishi Roku Photo Industry Co., Ltd. Figure 2 Procedural amendment March 14, 1985 Commissioner of the Patent Office Dear ゛, Pa. 1, Indication of case 1985 Patent application No. 18038 No. 2, Name of the invention Copying machine equipped with an optical system light-shielding member 3, Relationship with the person making the amendment Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Contact address: Sakura, Hino-shi, Tokyo 191 Japan Town 1 Konishiroku Photo Industry Co., Ltd. (1! Talk 0425-83-15
21) Patent Part 5, “Detailed Description of the Invention” column of the specification subject to amendment. 6. Contents of correction

Claims (2)

[Claims] (1) In a copying machine in which an original density detection means and/or an original size detection means is provided near a movable lens optical system, light that is incident on the detection means is prevented from being incident on the rear side of the lens optical system. A copying machine equipped with an optical system light shielding member, characterized in that a light shielding means is provided in a part of a moving lens optical system. (2) A copying machine equipped with an optical system light shielding member according to claim 1, wherein the light shielding means is constituted by an elastic member.