JPS6123138A - Focus correcting device of copying machine for original binding part - Google Patents

Abstract

PURPOSE:To form a sharp image of the binding part of an original even when the binding part does not contact platen glass by allowing a transparent body whose refractive index is >=1 to cross an optical path when the binding part is exposed. CONSTITUTION:The plate type transparent body 9 of glass, etc., whose refractive index is >=1 is provided nearby a lens 7. Light from an exposure lamp 4 which is reflected by the original (a) is projected on a photosensitive drum 1 from a fixed mirror 8 through a full-rate mirror 5, half-rate mirrors 6 and 6, and the lens 7 to perform exposure, and when the binding part (b) of the original (a) is exposed, the transparent body 9 is driven by an unshown moving mechanism to cross the optical path. Thus, the focal length of the lens 7 becomes long and light based upon the long focal length is projected on the photosensitive drum 1. Consequently, an image of the binding part (b) is in focus even when the original (a) does not contact the platen glass 2 and formed on the photosensitive drum 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a focus correction device for correcting the focus of the binding portion of a document in a copying machine that copies a document having a binding portion, such as a book, facing upward. Regarding.

[Conventional technology]

Conventionally, in this type of copying machine, an original such as a book is placed on an original placing plate, and an exposure lamp, a full rate mirror, and a half rate mirror scan the upper surface of a platen glass arranged above the original. The structure was such that an electrostatic latent image of the original document was formed on the photoreceptor.

[Problem that the invention seeks to solve]

In such conventional copying machines, because the binding part of the document does not come into contact with the platen glass, the focus of the image at the binding part does not match the photoreceptor, and as a result, the image at the binding part is copied in an unclear state. There was a problem with being exposed.

An object of the present invention is to make the image of the binding portion of a document clear even if the binding portion of the document does not come into close contact with the platen glass.

[Means and effects for solving the problem] The present invention provides a plate-shaped transparent body with a refractive index greater than 1 so that light reflected from an original can enter and leave an optical path for projecting light onto a photoreceptor, and this transparent body When exposing the binding area of a document, the optical path is made to cross the above-mentioned optical path, thereby correcting the focus of the binding area and forming an image on the photoreceptor.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

In FIG. 1, (1) is a photosensitive drum disposed inside the copying machine, and a photoconductive thin film is formed on the peripheral surface of the photosensitive drum. As the photosensitive drum fil rotates in the direction shown in the figure, its circumferential surface is charged by a charging device (not shown), and then exposure, development, transfer, and fixing are performed as will be described later, thereby performing a copying operation. There is.

(2) shows the platen glass, and below the platen glass (2) are two left and right original document placement plates (3).

(3) is installed. And this manuscript mounting plate (31,
(A) such as a book is placed facing upward on the placing plate (31, (31). (a
) is pressed appropriately against the lower surface of the platen glass (2).

An exposure lamp (4) is provided above the platen glass (2) for scanning while projecting light onto the original (a), and an exposure lamp (4) is provided on the side of the exposure lamp (4).
), a full rate mirror (5) and a half rate mirror (61, (61) are provided.
The light of the exposure lamp (4) reflected from the full rate mirror (5), the half rate mirror f6), (61
It is further reflected by the fixed mirror (8) via the lens (7).
) is projected onto the circumferential surface of the photosensitive drum (11), thereby forming an electrostatic latent image of the original (al) on the photosensitive drum ω.

Further, in the vicinity of the lens (7), a plate-shaped transparent body (9) made of glass or the like having a refractive index greater than 1 is placed.
) has been established.

This transparent body (9) has a structure that allows it to be moved in and out of the optical path formed by the plurality of mirrors by a moving mechanism (not shown). (9) is arranged to cross the optical path.The lens (7) is arranged to move in a direction perpendicular to the optical path.

The present invention is constructed as described above, and when the copying machine is started, the exposure lamp (4), full rate mirror (5), and half rate mirror (6) are exposed as shown in FIG.

(6) scans, and the original (al
to project light. Then, the reflected light is transferred to the full rate mirror (5), the half rate mirror +61. F6), the fixed mirror (8) projects the light onto the photosensitive drum (1) for exposure. Next, as shown in FIG. 2, when exposing the binding portion (b) of the original (a), the transparent body (9) is moved across the optical path by a moving mechanism (not shown). In this case, the transparent body (9
), the focal length of the lens (7) becomes longer by 8l as shown in equation (1), and as a result, light with an extended focal length is projected onto the photosensitive drum (11).

Δβ−t・(1−1/n) ・・・fullHowever, t
is the thickness of the transparent body (9), and n is the refractive index of the transparent body (9). After that, when the exposure of the binding part (bl) is completed, the transparent body (9) is positioned below the optical path as shown in Figure 3. However, when the scanning of the exposure lamp (4) and the like is completed and the exposure of the original (al) is completed, the original position is returned.

Therefore, in order to correct the focus of the binding part (bl) by changing the focal length when exposing the binding part (bl),
Even if the original (al) does not come into close contact with the platen glass (2),
The binding part (the focus of the image of BL matches and the photosensitive drum (1)
can be imaged. In addition, the material of the transparent body (9),
The thickness etc. may be arbitrarily selected depending on the depth of the binding portion fb).

〔Effect of the invention〕

As explained above, according to the present invention, when exposing the binding portion of a document, a transparent body having a refractive index larger than the moon crosses the optical path that projects the light reflected from the document onto the photosensitive drum. Therefore, the images of the binding portion of the document can be aligned and focused on the photosensitive tram, which has the effect that the image of the binding portion can be made clearer.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, and FIGS. 2 and 3 are front views showing the operating state of the present invention. (1): Photosensitive drum (2) Nibraten glass (3)
): Original plate (4): Exposure lamp (5): Full rate mirror (6): Half rate mirror (7): Lens (8): Fixed mirror (9):
transparent body

Claims (1)

[Claims] 1. A plate-shaped transparent body having a refractive index greater than 1 is provided, which crosses the optical path for projecting the light of the exposure lamp reflected from the original onto the photoreceptor when exposing the binding portion of the original. A focus correction device for the binding section of a copying machine.