JPS6122334A - Exposing device of copying machine - Google Patents

Abstract

PURPOSE:To prevent a black stripe image of the binding part of a thick original from being formed by using platen glass which is sectioned in an isosceles triangle shap, and controlling the quantity of light from an exposure lamp according to the thickness of the glass. CONSTITUTION:A platen transparent body 2 made of glass, etc., is sectioned in an isosceles triangle shape so as to contact an original such as a thick book. Then, the quantity of light from the exposure lamp 5 which scans on the platen is increased from the home position to the center part and decreased from the center to the scanning end part through a light quantity control part 11 according to the arithmetic value of a specific counter 10. Consequently, a deficiency in the quantity of light to the binding part of the original like the thick book, etc., is eliminated and a black stripe image of the binding part due to the deficiency of the quantity of light is prevented from being formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure device disposed in a copying machine, and particularly to an exposure device in a copying machine that copies a document such as a book facing upward.

[Conventional technology]

Conventionally, in this type of copying machine, an original such as a book is placed facing upward on the lower surface of a flat platen glass, and the original is appropriately pressed against the platen glass to make copies. However, in this method, since the binding portion of the document does not come into close contact with the platen glass, the amount of light from the exposure lamp projected onto the surface of the document at the binding portion is insufficient, resulting in the binding portion appearing as a black line. Furthermore, when pressing a document against a platen glass, since the binding portion is curved, the image of the same binding portion is copied in a curved shape, making the image unclear. Therefore, it is conceivable that the platen has a V-shaped cross section and that the original is brought into close contact with the platen from the bottom surface.

[Problem that the invention seeks to solve]

In such a structure, by bringing the binding part into close contact with the platen, it is possible to prevent the image at the binding part from becoming curved. However, the lack of light intensity of the sheath light lamp becomes particularly noticeable at the binding part, and There was a problem in that the color appeared as a black line.

According to the present invention, the image at the edge of the original has a curved shape,
The purpose of this is to prevent the dark spots from appearing as black lines due to insufficient light intensity.

[Means and effects for solving the problems] The present invention uses a transparent platen body having an isosceles triangular cross section with an apex at the bottom as a platen, and furthermore, the light projected onto the original document can be directed to any part of the original document. A control device is provided to control the amount of light from the exposure lamp according to the thickness of the transparent platen so that the amount of light is constant.

With the above configuration, it is possible to prevent the binding part of the document from coming into close contact with the lower surface of the transparent platen, thereby preventing the image at the border from becoming curved, and also preventing insufficient light intensity at the border. be.

〔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 a copying machine, and has a photoconductive thin film formed on its circumferential surface. The photosensitive drum (1) is charged by a charging device (not shown) while rotating in the direction shown in the drawing, and then exposed to light as described later.

(2) is a transparent platen body made of glass or the like, and has an isosceles triangular cross section with an apex at the bottom, so that the lower surface of the transparent platen body (2) has a ■-shaped structure. At the bottom of this transparent platen body (2), a document f8 such as a book is placed parallel to the two lower sides of the platen body (2).
) on which are placed facing upwards (31, (31
has been set up. And the manuscript mounting plate (3).

(3) With the left and right surfaces of the document fat in contact with the V-shaped lower surface of the transparent platen body (2), and with the document (8
The binding portion (bl) of No. 1 is placed in contact with the apex of the transparent platen (2). This prevents the image of the binding portion (bl) from becoming curved, resulting in a high-quality image. An image can be obtained.It should be noted that the document placement plate f31.
(A biasing device (not shown) made of, for example, a spring is provided at the bottom of the document mounting plate f31. (By biasing the document mounting plate f31 upward,
The surface of the original (al) is appropriately pressed against the lower surface of the transparent platen (2).

Two exposure lamps (5) housed in a case (4) are provided on the upper surface of the transparent platen (2), and the exposure lamps (5) scan the document (al) in the direction shown. The light reflected from the original (al) is reflected by the scanning mirror (6) together with the exposure lamp (5), and is then sent to the fixed mirror (8) via the lens (7).
is projected onto the photosensitive drum (
1) It is designed to project onto the surrounding surface. As a result, exposure is performed as described above, and the original Cal is placed on the photosensitive drum +11.
It is designed to form an electrostatic latent image.

FIG. 2 shows a block diagram of the first embodiment.

In the figure, (9) is a motor that scans and drives the exposure lamp (5) and mirror (6) in the direction shown in the figure at a constant speed. The rotation angle 14 of this motor (9) is measured by an encoder (not shown) and counted by a counter (10). The light amount of the exposure lamp (5) is controlled by the light amount control section (11) controlling the electric power given to the exposure lamp (5) according to the value of the counter (1G+(+)iil). ＋!11 As shown in Figure 3, the exposure lamp (5) is in position (A).
When scanning from the position (13) corresponding to the central apex of the transparent platen (2), the exposure lamp (5)
The amount of light is increased and the light is controlled to decrease from the same position (B) to the scanning end position (C). in this case,
The light intensity at the home position (A) and the scanning end position (C) is the same, and is maximum at the position (B) corresponding to the vertex. Also, the light intensity of the exposure lamp (5) is adjusted to the home position (
The brightness gradually increases from A) to the bottom of the apex (B) in proportion to the thickness of the transparent platen body (2), and from the same position (B) to the scanning end position (C), it increases in proportion to the thickness of the transparent platen body (2). The light gradually decreases proportionally. Therefore, the amount of light emitted to the binding area (BL) will not be insufficient, and this can prevent the phenomenon that the binding area (BL) appears as a black line as in the past. After exposure, toner is applied to the electrostatic latent image formed on the circumferential surface of the photosensitive drum (1) for development, and further transfer and fixing are performed to complete the copying operation.

〔Effect of the invention〕

As explained above, according to the present invention, the platen is a transparent platen body having an isosceles diagonal cross section with an apex at the bottom, so that the binding portion of the original comes into close contact with the lower surface of the transparent platen body, and thereby the binding portion It is possible to prevent the image from becoming curved. In addition, since the light intensity of the flashing lamp was controlled according to the thickness of the transparent platen, it was possible to prevent insufficient light coverage at the binding area, thereby preventing black lines from appearing only at the edges. The effect is that it is possible to prevent this and obtain high-quality images.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a block diagram of an electric circuit of the embodiment shown in Fig. 1, and Fig. 3 shows the relationship between the light amount of the exposure lamp and the scanning position. FIG. (1); Photosensitive drum (2) Nibraten transparent body (
3): Original plate (4): Case (5): Exposure lamp (6): Mirror (7): Lens
(8): Fixed mirror (9): Motor 0
01: Counter (11): Light amount control section (a
): Manuscript (b): Binding section 1 Figure exposure lamp position!

Claims (1)

[Claims] 1. A transparent platen body having an isosceles triangular cross section with an apex at the bottom, and an exposure lamp that scans the upper surface of this platen body, gradually increasing the light from the home position until the lamp reaches the apex above, and 1. An exposure device for a copying machine, comprising: a light amount control device that gradually reduces light from the apex to a scanning end position.