JPH03219270A - Voltage application exposure method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage application exposure method for forming a high resolution electrostatic latent image on a charge retention medium.

[Conventional technology]

The present applicant has developed an electrostatic image recording and reproducing method that forms a high-resolution electrostatic latent image on a charge-retaining medium by imagewise exposure while applying a voltage between the electrodes of a photoreceptor and a charge-retaining medium that are arranged facing each other. A method has already been proposed.

FIG. 10 is a diagram for explaining such an electrostatic image recording method. In the figure, 1 is a photoreceptor, 3 is a charge retention medium, and 5
1 is a photoconductive layer support, 7 is a photoreceptor electrode, 9 is a photoconductive layer, 1
1 is an insulating layer, 13 is a charge retention medium electrode, 15 is an insulating layer support, and 17 is a power source.

In FIG. 10, exposure is performed from the side of the photoreceptor 1. First, a transparent photoreceptor electrode 7 made of ITO with a thickness of 100 OA is formed on a photoconductive layer support 5 made of glass with a thickness of 100 OA. A photoconductive layer 9 of about 10 μm is formed on this to constitute a photoreceptor 1. For this photoreceptor 1, 10
The charge retention medium 3 is arranged with a gap of approximately μm in size interposed therebetween.

The charge retention medium 3 is formed by forming an A1 electrode 13 with a thickness of 100 OA by vapor deposition on an insulating layer support 15 made of glass with a thickness of lll1fll, and an insulating layer 1 with a thickness of 10 μm on this electrode 13.
1 was formed.

First, as shown in FIG. 10(a), for the photoreceptor 1,
The charge retention medium 3 is set with a gap of about 10 μm in between.

In such a configuration, a voltage is applied between the electrodes 7 and 13 by the power source 17 as shown in FIG. 10(b). In a dark place, the photoconductive layer 9 is a high-resistance material, so no change occurs between the electrodes, or the Paschen discharge starting voltage increases in the gap due to the magnitude of the applied voltage and leakage current from the substrate electrode. When the above voltage is applied, discharge occurs in the gap, and electrostatic charges corresponding to dark current are formed on the charge retention medium. When light is incident on the photoreceptor 1 side, photocarriers (electron holes) are generated in the photoconductive layer 9 where the light is incident, and charges with the opposite polarity to the charge retention medium electrode move therein toward the surface. During this process, if the voltage distribution in the air gap exceeds the Paschen discharge starting voltage, a corona discharge will occur between the insulating layer 11 or the photoconductive layer 9 will be discharged due to field emission.
Charges are extracted from the insulating layer 1 and accelerated by the electric field.
Charge is accumulated in 1.

When the exposure is completed, the voltage is turned off as shown in FIG. 10(c), and then the charge holding medium 3 is taken out as shown in FIG. 10(d), thereby completing the formation of the electrostatic latent image. In this way, an electrostatic latent image is formed by turning the voltage ON and OFF, that is, by the voltage shutter, and it is possible to omit the mechanical and optical shutters used in ordinary cameras.

The photoconductive layer 9 is a conductive layer in which photocarriers (electrons, holes) are generated in the irradiated area when light is irradiated, and these carriers can move across the layer width, especially in the presence of an electric field. This is the layer where the effect is noticeable in some cases. The materials include inorganic photoconductive materials, organic photoconductive materials, organic-inorganic composite photoconductive materials, and the like.

Examples of inorganic photoreceptor materials include amorphous silicon, amorphous selenium, cadmium sulfide, and zinc oxide.

Organic photoreceptors include single-layer photoreceptors and functionally separated photoreceptors.

A single-layer photoreceptor is made of a mixture of a charge-generating substance and a charge-transporting substance, and the charge-generating substance is a substance that absorbs light and easily generates a charge, such as azo pigments, disazo pigments, trisazo pigments, etc. Pigments, phthalocyanine pigments, perylene pigments, biryllium dyes, cyanine dyes, and methine dyes are used. In addition, charge transport materials include materials with good transport properties for ionized charges, such as hydrazone, pyrazoline, polyvinylcarbazole, carbazole, stilbene, anthracene, naphthalene, tridiphenylmethane, azine, etc. amine type,
There are aromatic amines, etc.

Further, in the functionally separated photoreceptor, the charge generating material easily absorbs light but has the property of trapping light, and the charge transporting material has good charge transport properties but poor light absorption properties. Therefore, it is a type in which a charge generation layer and a charge transport layer are laminated in order to separate the two and fully exhibit their respective characteristics.

Examples of substances forming the charge generation layer include azo-based, disazo-based, trisazo-based, phthalocyanine-based,
Acidic xanthene dye system, cyanine system, styryl dye system, biryllium dye system, perylene system, methine system, a-3e 5
a-3i, azulenium salts, squarium bases, etc., and examples of substances forming the charge transport layer include hydrazones, pyrazolines, PVKs, carbazoles,
Examples include oxazole type, triazole type, aromatic amine type, amine type, triphenylmethane type, and polycyclic aromatic compound type.

[Problem to be solved by the invention]

In general, the characteristics of the generated carriers are that in the case of inorganic photoreceptors, the mobility μ is large and the lifetime τ is short, while in the case of organic photoreceptors, the mobility μ is small and the lifetime τ is long, and μτ is approximately the same. It is known that there is. Formation of an electrostatic latent image during voltage application exposure is possible with only a mechanical exposure shutter or only a voltage shirt, but in the case of only a mechanical exposure shutter, a voltage is applied between the photoreceptor and the charge retention medium. Therefore, there is a problem in that a dark current flows even when not exposed to light and a fog potential is generated.

Further, in the case of using only a voltage shutter, there is a problem that when an organic photoreceptor is used, the amount of exposure and the amount of charge differ depending on the voltage shutter time. This point will be explained with reference to FIG.

In Figure 9, the light intensity is constant and the voltage shutter time is 0.0.
This is a diagram showing the amount of charge on the charge holding medium when the time is changed to 1 second, 0.1 second, and 1 second. In the case of an inorganic photoreceptor, the carrier mobility is large, so the voltage shutter time is changed as shown in characteristic A. Even if the amount of charge is changed, the amount of charge will correspond to the amount of exposure. on the other hand,
When an organic photoreceptor is used, as shown in characteristic B, the voltage shutter time is 0.01 seconds and 0.01 seconds. In the case of 1 second, a phenomenon occurs in which the amount of charge differs between 0.1 seconds and 1 second even if the exposure amount is the same. This is because organic photoreceptors have low carrier mobility, so the voltage is reduced to O before the carriers generated by exposure reach the charge retention medium.
This is because it disappears because it is FFed. Therefore, there is a problem that the image potential varies depending on the voltage shutter time even if the exposure amount is the same.

The present invention is intended to solve the above problems, and it is an object of the present invention to provide a voltage application exposure method that allows an amount of charge to be obtained in accordance with the amount of exposure regardless of the voltage shutter time even when an organic photoreceptor is used. This is the purpose.

2 [Means for Solving the Problems] FIG. 1 is for explaining the voltage application exposure method of the present invention.

As described above, when an organic photoreceptor is used, the carriers have low mobility, so when the voltage is turned off, the carriers generated by exposure disappear without reaching the charge retention medium. Therefore, as shown in FIG. 1, for example, if the exposure shutter is turned on at time t, the voltage shutter is ONL, and the exposure shutter is turned off at time t2, the time Δ for all the generated carriers to reach the charge retention medium can be increased by The voltage shutter is turned off at time t. By doing so, it is possible to form an image with an amount of charge depending on the amount of exposure. Note that the time Δt from when the exposure shutter is turned off to when the voltage shutter is turned off depends on the material of the photoreceptor,
Since it changes depending on the thickness, etc., calculate the time Δt when changing these conditions and create a table in advance. Once the conditions are set, refer to this table to find Δt and set the OFF timing of the voltage shutter. good.

FIG. 2 is a diagram showing an example of an electrostatic camera that uses voltage applied exposure. In the figure, the same numbers as in FIG. 10 indicate the same contents, 21 is a photographing lens, 22 is a shutter, 23 is a mirror, 25 is a focusing glass, 27 is a pentaprism, 29
is an eyepiece, and 31 is a negative image.

An electrostatic camera uses a photoreceptor 1 and a charge holding medium 3 shown in FIG. 10 instead of the film of a single-lens reflex camera, and when a switch (not shown) is operated to turn on the power supply 17, the photoreceptor and the charge are removed. A voltage is applied to the holding medium, the shutter 22 is opened for a set time, and the mirror 23 is opened.
is flipped up to the position indicated by the dotted line, and an electrostatic latent image of the subject is formed on the charge retention medium 3. Then, after a predetermined time after the shutter 22 is closed, the voltage application between the photoreceptor and the charge holding medium is turned off. Then, if necessary, the charge holding medium is developed with toner to obtain a negative image 31. It is also possible to read the electrostatic potential and output it as an electrical signal, which can be displayed on a CRT or transcribed onto a recording means such as a magnetic tape.

[Effect]

In the present invention, when an electrostatic latent image is formed on a charge holding medium by a voltage application exposure method, all the generated carriers are transferred to the charge holding medium by turning off the voltage shutter after a predetermined time after the exposure shutter is FF. The amount of charge corresponding to the amount of exposure can be accumulated regardless of the voltage shutter time.

〔Example〕

Examples will be described below.

[Example 1] An organic photoreceptor with a film thickness of 10 μm was used as the photoreceptor, a fluororesin with a film thickness of 3 μm was used as the charge retention medium, and a voltage of 750 V was applied with a gap of 10 μm provided and the photoreceptor side being positive. A Dungesten lamp with a color temperature of 3000° was used as a light source.

In Figure 3, the horizontal axis shows the exposure amount applied to the photoreceptor, and the vertical axis shows the potential recorded on the charge holding medium. Apply voltage and turn off the voltage at the same time as exposure is turned off
The characteristics when (Δt=0) are shown.

Figure 4 shows the same sample as in Figure 3, irradiated with light for 0°1 seconds at the exposure intensity, and applied voltage for 0.1 seconds after light irradiation (Δt=o,
is) This is the result when the application is continued.

Comparing Figures 3 and 4, it can be seen that although the amount of exposure applied to the photoreceptor is the same, the potential recorded on the charge retention medium in Figure 4 is a voltage pulse. A larger potential is obtained than in the case of FIG. 3, in which the voltage is synchronized with exposure, and the effect of applying voltage is clearly visible even after the optical shutter is closed.

[Example 2] Under the same conditions as [Example 1], the voltage application time after light irradiation was 0. This is a case where the time is set to 2 seconds (Δt=0.2s). The results are as shown in FIG. 5, and a remarkable effect appears compared to the case where the optical shutter and voltage shutter of FIG. 3 are synchronized.

[Example 3] This is a case where the voltage application time after light irradiation was set to 0.3 seconds (Δt=o, 3s) under the same conditions as [Example 1]. The results are shown in FIG. 6, and a remarkable effect appears compared to the case where the optical shutter and voltage shutter shown in FIG. 3 are synchronized.

[Example 4] This is a case where the voltage application time after light irradiation was set to 0.4 seconds (Δt=0.4 s) under the same conditions as [Example 1]. The results are shown in FIG. 7, and a remarkable effect appears compared to the case where the optical shutter and voltage shutter of FIG. 3 are synchronized.

[Example 5] Under the same conditions as [Example 1], the voltage application time after light irradiation was 0. This is a case where the time is 5 seconds (Δt=o, 5s). The results are shown in FIG. 8, and a remarkable effect appears compared to the case where the optical shutter and voltage shutter of FIG. 3 are synchronized.

〔Effect of the invention〕

As described above, according to the present invention, all generated carriers can be accumulated as charges on the charge holding medium, and the amount of charges corresponding to the exposure amount can be accumulated regardless of the voltage shutter time.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the voltage application exposure method of the present invention, Fig. 2 is a diagram showing an example of an electrostatic camera using voltage application exposure, and Fig. 3 is a diagram showing an example of an electrostatic camera using voltage application exposure, and Fig. 3 is a diagram showing an example of an electrostatic camera using voltage application exposure. Figures 4 to 8 are diagrams showing the recording potential versus exposure when the voltage shutter time after exposure is varied, and Figure 9 is for the conventional voltage application exposure method. FIG. 10 is a diagram for explaining the electrostatic image recording method. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 3... Charge retention medium, 5... Photoconductive layer support, 7... Photoconductor electrode, 9... Photoconductive layer,
11... Insulating layer, 13... Charge retention medium electrode, 15
... Insulating layer support, 17 ... Power supply, 22 ... Shutter applicant

Claims (1)

[Claims] (1) A photoreceptor having a photoconductive layer formed on a support with a conductive layer interposed therebetween and a charge retention medium having an insulating layer formed on the support with a conductive layer interposed therebetween are arranged facing each other, An exposure method that performs image exposure from the photoreceptor side while applying a voltage between the conductive layer of the photoreceptor and the charge retention medium to accumulate charges in the charge retention medium in the form of an image, and after the image exposure is turned off,
A voltage application exposure method characterized in that the voltage applied between the conductive layers is turned off after a predetermined period of time.