JPS5949527A - Partial image erasing device of electrophotographic copying machine of reversal development type - Google Patents

Abstract

PURPOSE:To form easily a white part in a required part of a copy, by providing a liquid crystal having an optical path intercepting opaque part partially between a condenser lens and a photoreceptor. CONSTITUTION:A movable mirror 8 is projected into the optical path of an optical system 1 to project the image of a nagetive film original 10 onto a screen 9 by a mirror 3. A control circuit 15 is operated to apply a voltage selectively, and an opaque part 14 is formed. Then, images of a liquid crystal plate 11 and the original 10 are projected to the screen 9 through a lens 5 and the mirror 8 by a light source 2, a reflective mirror 3, and a lens 4. When the movable mirror 8 is moved back from the optical path and each part of the copying machine including a drum-shaped photoreceptor 7 is operated, the crossing opaque part 14 on the liquid crystal plate 11 is subjected to reversal development and becomes the white part, and the image of the liquid crystal plate 11 in this state is superposed onto the positive image of the negative film original 10, and they are copied on the copy. Thus, the white part having an optional area is formed very easily independently of the original.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an evil part erasing device for a reversal development type electrophotographic copying machine.
In other words, the white part that does not exist in the original is placed on the copy at an arbitrary number N.
The present invention relates to a device that can be formed to any size.

Conventionally, if you wanted to correct a part of an image on a copy, you had to erase that part with chemicals or a knife, which had the disadvantage of not being easily erased, leaving behind stains, and becoming fluffy. Ta.

In addition, in the copying process, there is a method in which the unfixed toner image is output as an unfixed copy, and after the necessary toner P is deleted, the fixing operation is performed using a fixing device separate from the copying machine, but this method does not destroy the unfixed toner image. It is difficult to handle the device, and requires a separate external fixing device.

The present invention relates to an improvement of a copying machine that eliminates such drawbacks, and its purpose is to arrange a liquid crystal plate in the optical path between the condenser lens and the photoreceptor, and to make a part of the liquid crystal plate. The object of the present invention is to provide an evil image erasing device that can easily form a white part at a desired part on a copy by exposing an opaque part.

The present invention will be explained below based on one embodiment shown in the drawings.

The optical system 1 is the optical system of a reversal development type electrophotographic copying machine.
is an exposure lamp 2, a mirror 3, a condenser lens 4,
The light projected from the exposure lamp 2 is transmitted through a negative film original 10 which is composed of a projection lens 5 and a slit 6 and is interposed between the condenser lens 4 and the projection lens 5, and the transmitted light is applied to the surface of a drum-shaped photoreceptor 70. The image of the negative film original 10 is formed on the surface of the drum-shaped photoreceptor 7 by irradiation.

In addition, a movable mirror 8 is disposed in the optical path closer to the photoreceptor 7 than the projection lens 5, so that when the movable mirror 8 is protruded into the optical path of the optical system 10, the negative film original 10 is The image is projected onto a reader screen 9.

Rough condenser lens 4 and negative film original 100
A transparent liquid crystal plate 11 is arranged in between.

The liquid crystal plate 11 is a transmissive type IJ Lux display type liquid crystal plate, and includes a large number of X electrodes 12 oriented in one direction and arranged in a direction perpendicular to the direction, and The control circuit 15 selectively applies a voltage to both the XN poles 12 and the YN poles 13, so that the voltage on the liquid crystal plate 11 is An opaque portion 14 of an arbitrary width is exposed at an arbitrary position.

Further, the drum-shaped photoreceptor 7 is provided with a developing device (not shown).
A reversal developing device with an L pole is attached, so that a positive toner image is formed on the photoreceptor 7.

Since the illustrated embodiment is constructed as described above, the movable mirror 8 is projected into the optical path of the optical system 10 as shown by the dotted line, and the reader screen 9 is irradiated with light that has completely passed through the negative film original 10. , negative film original 10
is projected onto the reader screen 9.

In this state, the control circuit 157i is operated so that the required portion 14 becomes opaque, and the image is transferred to the negative film original 10.
The image is projected onto the reader screen 9 superimposed on the image of .

Therefore, by comparing the image of the cross-opaque area 14 of the liquid crystal plate 11 projected on the reader screen 9 with the image of the negative film original i10 and selecting its position and width appropriately, it corresponds to the white area to be erased. The cross-opaque area 14 on the liquid crystal plate 11 can be visually compared by comparing it with the image of the negative film original M410.

Next, when the movable mirror 8 is moved backward and each part of the copying machine including the drum-shaped photoreceptor 72 is operated, the cross-opaque area 14 on the liquid crystal plate 11 is reversely developed and becomes a white area. The image is superimposed on the positive image of the negative film original 10 and copied onto the copy.

As described above, according to the present invention, it is possible to extremely easily form a white portion of any width at any position, regardless of the document, without performing correction work using knives or chemicals.

Further, since correction work using a knife or chemicals is not performed, the corrected copy is free from defects such as stains and fluff, and a uniform and high-quality copy can be obtained.

In general, the copying machine using the present invention does not require an unfixed copy ejecting device or an external fixing device, resulting in a simple structure and low cost.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view illustrating an embodiment of a partial erasing device for a reversal development type electrophotographic copying machine according to the present invention, FIG. 2 is an enlarged view of its main parts, and FIG. It is a plan view showing the main parts of the liquid crystal plate. 0 1... Optical system, 2°... Exposure lamp, 3... Mirror, 4... Condenser lens, 51 Projection lens, 6...
... Slit, 7... Drum-shaped photoreceptor, 8... Movable mirror, 9... Reader screen, 1o... Negative film original 1 m, 11... Liquid crystal plate, 12... X electrode,
13...X electrode, 14...cross opaque part, 15...
・Control circuit. Agent: Patent attorney Nozomi Ehara (1 person) No. 20 Figure 3

Claims (1)

[Claims] In a reversal development type electrophotographic copying machine, a liquid crystal is placed in the optical path between the condenser lens and the photoreceptor, and a control circuit is provided in a part of the liquid crystal plate to expose an opaque area that blocks light in the optical path 2. An evil removal device for a reversal development type electrophotographic copying machine, which is characterized by: