JPH03200269A - Method and device for forming image - Google Patents

Abstract

PURPOSE:To obtain an image with high accuracy without necessitating an external light source by previously electrostatically charging a photosensitive body or a charge holding medium to a specified potential and turning on/off the electric connection between both conductive layers at the time of exposing the image so that a latent image may be controlled. CONSTITUTION:The charge holding medium 1 or the photosensitive body 2 are previously electrostatically charged and the connection of electrodes between the photosensitive body 2 and the charge holding medium 1 is turned on-off to control the exposure of the image at the time of exposing the image, so that shutter action is performed and the electrostatic latent image is formed on the charge holding medium 1. Thus, a power source for exposing the image is not necessitated as compared with exposure by impressing a voltage and a positive image is obtained. Since excess energy for other than exposure is not injected at the time of forming the image, the good-quality image is formed in a state where noises are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming method and apparatus for forming an electrostatic latent image on a charge retaining medium.

[Conventional technology]

2. Description of the Related Art Conventionally, imagewise exposure of a photoreceptor made of a photoconductor to form an electrostatic latent image and development with toner has been widely used in copying machines and the like. However, since such an electrophotographic method cannot retain an electrostatic latent image for a long period of time, the applicant placed a photoreceptor and a charge retention medium having an insulating layer facing each other,
A voltage application image exposure method has already been proposed in which a voltage is applied between these materials to perform image exposure and form an electrostatic latent image on a charge-retaining medium. According to this method, since charges are formed in the insulating layer, it is possible to retain a latent image for a long period of time, and high-precision analog recording is possible.

In addition, an insulating film having a conductive layer is charged with corona in advance, and a voltage is applied between the conductive layer of the insulating film and the photoreceptor electrode, or a short circuit is established between the two. It is also known that a latent image can be formed on an insulating film by exposure to light.

[Problems to be Solved by the Invention] However, the voltage application image exposure method requires an external power source to apply a voltage between the photoreceptor and the charge holding medium during exposure to cause discharge, which increases the size of the device. Moreover, there is a problem in that it is easily affected by power supply voltage fluctuations.

Furthermore, by applying a corona charge to the insulating film in advance, it is possible to omit an external power source during exposure, but the specific method of forming a latent image is not known. It wasn't.

The present invention is intended to solve the above problems, and an object of the present invention is to provide an image forming method and apparatus that do not require an external power source and can obtain highly accurate images.

[Means to solve the problem]

To this end, in the present invention, a photoreceptor in which a conductive layer and a photoconductive layer are formed on a support, and a charge retention medium in which an insulating layer is formed on the conductive layer are arranged facing each other, and the charge is charged by imagewise exposure. When forming an electrostatic latent image on a holding medium, the photoreceptor or charge holding medium is charged to a predetermined potential in advance, and the electrical connection between the two conductive layers is turned on and off during image exposure to control latent image formation. It is characterized by being made to do.

[Effect]

The present invention performs a shutter action by charging a charge holding medium or a photoreceptor in advance, and controlling the image exposure by turning on and off the connection between electrodes between the photoreceptor and the charge holding medium during image exposure. In addition, by forming an electrostatic latent image on a charge-retaining medium, it is possible to obtain a positive image without the need for a power source for image exposure compared to voltage-applied exposure. Since no extra energy is injected, it is possible to form high-quality images with less noise.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the image forming method according to the present invention. In the figure, 1 is a charge retention medium, 1a is an insulating layer, lb
is a charge retention medium electrode, IC is an insulating layer support, 2 is a photoreceptor, 2a is a photoconductive layer support, 2b is a photoreceptor electrode, 2c is a photoconductive layer, 3 is a charging device, E is a power source, and 5 is a switch , 6 is an ammeter.

In the figure, the charge retention medium 1 is made by forming an Al electrode 1b with a thickness of 100 OA by vapor deposition on an insulating layer support 1c made of glass with a thickness of 1 mm, and an insulating layer 1a with a thickness of 10 μm on this electrode lb. The photoreceptor 2 has a 100 OA thick I layer on a photoconductive layer support 2a made of 1 m thick glass.
The photoreceptor 2 is constructed by forming a transparent photoreceptor electrode 2b made of TO, and forming a photoconductive layer 2C of about 10 μm thereon. A charge holding medium 1 is placed with respect to the photoreceptor 2 with a gap of about 10 μm in between.

First, a voltage is applied to the charge holding medium 1, for example, to the electrode 3 to generate a discharge, and the insulating layer! a
is charged to a predetermined potential. Of course, charging may be performed by applying a voltage and exposing to light, or other methods such as frictional charging and peeling charging may be used.

In this case, the photoreceptor is charged with a charge of opposite polarity to the majority carriers (charges of polarity that are likely to be transported). The majority carrier is a positive charge in an organic photoreceptor, and a positive charge or a 4i negative charge in an inorganic photoreceptor depending on the material. Therefore, for example, when using an Ariiso scenic object, the charge holding medium is charged with a negative charge. next,
The charged charge holding medium l is placed at a distance of 10 μm to the photoreceptor 2.
The switch 5 is closed to short-circuit the electrodes 1b and 2b. A positive charge with a polarity opposite to the negative charge on the surface of the insulating layer is induced in the electrode 1b, but due to the short circuit between the electrodes 2b, a part of the charge is distributed to the electrode 2b, and the charge holding medium and the photoreceptor are separated. A predetermined voltage difference occurs between them. In this state, for example, when image exposure is performed from the photoreceptor side, carriers are generated in the photoconductive aX layer 2c, and positive charges are pulled and transported to the surface on the charge retention medium side. Then, it combines with and neutralizes the ionized negative charges in the voids on the surface of the photoconductive layer, and the ionized positive charges in the voids are pulled toward the charge retention medium and neutralized with the negative charges on the surface of the insulating layer.

Since the amount of positive charges that neutralize the negative charges on the surface of the insulating layer corresponds to the amount of exposure, the potential of the surface of the approximately 1i layer with respect to the amount of exposure is as shown in FIG. In this way, since the insulating layer surface potential corresponds to the image, an electrostatic latent image is formed. In this case, the potential decreases in areas that are exposed to a large amount of light, and for example, when developed with toner, the image becomes whitish, so the image obtained by this image forming method becomes a positive image. It is extremely advantageous when used to create frost images.

Note that when the switch is turned off, exposure is performed, but majority carrier transport does not occur, so no latent image is formed, and a shutter action can be performed by turning the switch on and off. Further, since the total amount of charge transported from the photoreceptor can be known by monitoring the ammeter 6, it can be used as an exposure meter when applied to, for example, an electrostatic camera. Furthermore, since no energy is injected other than image exposure during exposure, it is possible to achieve high image quality without noise.

Note that the photoreceptor 2 and the charge retention medium 1 may be connected not in a non-contact manner as described above, but in a contact type. In the case of a contact type, the charges generated in the exposed area are drawn to the charge retention medium side, and the photoconductive layer 2C
When it passes through and reaches the surface of the insulating layer 18, it neutralizes the charge on the surface of the insulating layer and forms an electrostatic latent image. And switch 5
The charge holding medium 1 is separated by opening.

Further, in the above embodiments, a method of pre-charging the charge holding medium has been described, but it is also possible to form an image in the same way by charging the photoreceptor after it has been darkened.

When this recording method is used for planar analog recording, high resolution can be obtained similar to silver salt photography, and the insulating layer formed is
The surface charge on a is exposed to the air environment, but since air has good insulating properties, it will not discharge and will be stored for a long time regardless of whether it is in a bright or dark place.

FIG. 3 is a diagram showing a configuration when the image forming method of the present invention is applied to an electrostatic camera.

In this embodiment, the charge retention medium 1 is formed into a film, and is sequentially supplied from a supply reel 11 to a take-up reel 12 to face the photoreceptor 2, with the take-up reel and the photoreceptor electrode short-circuited. One image is exposed through a photoreceptor.

An electrode 14 is arranged on the upstream side of the photoreceptor 2 to face the film-like charge holding medium 1, and a power supply 13 connects the electrode 14 and the charge holding medium 1.
An electrostatic latent image can be sequentially formed by applying a voltage between them to charge them and exposing them to image light through a photoreceptor.

FIG. 4 is a diagram showing another embodiment of the present invention using triboelectric charging.

In this embodiment, the insulating fiber 16 is formed into a roll and placed upstream of the photoconductor 2, and the roll is rotated to rub against the film-like charge retention medium to uniformly triboelectrically charge it. The other configurations are the same as those shown in FIG. This embodiment does not require a power source even when charging, so it is effective when constructing a portable electrostatic camera.

FIG. 5 is a diagram showing another embodiment of the present invention in which the charge retention medium is formed into a disk shape.

In this embodiment, the charge holding medium 1 is formed into a disk shape and is rotatable, and a voltage is applied to the electrode 14 to charge the disk surface. Then, the photoreceptor 2 is disposed downstream of the electrode so as to face a part of the surface of the charge retention medium, and the disk-shaped charge retention medium and the photoreceptor are electrically short-circuited. In this way, an electrostatic latent image can be similarly formed by imagewise exposure through the photoreceptor 2.

FIG. 6 is a diagram showing another embodiment of the present invention using peel-off charging.

The charge retention medium 1 in this example is a support film le
An insulating peeling layer 1d is formed thereon, and the peeling layer 1d is stacked to face the insulating layer 1a as shown in FIG. 6(a). The charge retention medium having such a structure is formed into a film, and as shown in FIG. The release layer side is wound up with a take-up reel 25, and the charge retention medium side is wound up with a take-up case 21. The surface of the insulating layer of the charge-retaining medium is charged by the peeling, and then an electrostatic latent image can be formed on the charge-retaining medium by exposing the charge-retaining medium and the photoreceptor 2 to each other and exposing the image through the photoreceptor 2. It is possible. This embodiment does not require a power source even when charging, so it is effective when constructing an electrostatic camera.

〔Effect of the invention〕

As described above, according to the present invention, the charge holding medium is charged in advance, and the charge holding medium and the photoreceptor are faced to each other, and the electrical connections between the respective electrodes are turned on and off to reduce the electrostatic charge. It becomes possible to control image formation, perform image formation by performing a shutter action, and obtain a positive image. Also,
Since no energy is injected other than image light during exposure, high image quality without noise can be achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the image forming method according to the present invention, FIG. 2 is a diagram showing the relationship between the exposure amount and the surface potential of the charge holding medium, and FIG. 4 is a diagram showing another embodiment of the present invention that utilizes frictional charging; FIG. 5 is a diagram showing another embodiment of the present invention in which the charge retention medium is in the form of a disk; FIG. 6 is a diagram showing another embodiment of the present invention using exfoliation charging. l...charge retention medium, 1a...insulating layer, 1b...
Charge retention medium electrode, IC...insulating layer support, 2...
Photoreceptor, 2a... Photoconductive layer support, 2b... Photoconductor electrode, 2C... Photoconductive layer, 3... Charging device, E...
- Power supply, 5... switch, 6... ammeter.

Claims (4)

[Claims] (1) A photoreceptor having a conductive layer and a photoconductive layer formed on a support and a charge retention medium having an insulating layer formed on the conductive layer are placed facing each other, and imagewise exposure is performed to form a charge retention medium. An image forming method for forming an electrostatic latent image on a
The photoreceptor or charge holding medium is charged to a predetermined potential in advance, and the electrical connection between the two conductive layers is closed during image exposure.
An image forming method characterized in that latent image formation is controlled by turning the power off. (2) A film-like charge holding medium having an insulating layer formed on a conductive layer is supplied intermittently or continuously to face a photoreceptor having a conductive layer and a photoconductive layer formed on a support, and an image A device that forms an electrostatic latent image on a film-like charge-retaining medium by exposure to light; a charge-retaining-medium charging means is provided on the film-like charge-retaining medium supply side, and during image exposure, the charge-retaining medium and the photoreceptor are connected to each other. ON-OF electrical connection between conductive layers
An image forming apparatus characterized in that it is provided with means for controlling latent image formation. (3) A rotatable disk-shaped charge holding medium having an insulating layer formed on a conductive layer and a photoreceptor having a conductive layer and a photoconductive layer formed on a support are placed facing each other and imagewise exposed. An apparatus for forming an electrostatic latent image on a charge retentive medium by
A disk-type charge holding medium charging means is provided, and during image exposure,
Turn on the electrical connection between the charge retention medium and the conductive layer of the photoreceptor
- An image forming apparatus characterized by comprising means for controlling latent image formation by turning it off. (4) The image forming apparatus according to claim 2 or 3, wherein the charging means performs charging by voltage application charging, voltage application exposure charging, frictional charging, or peeling charging.