JP3031694B2 - Voltage application exposure method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a voltage application exposure method for forming a high-resolution electrostatic latent image on a charge holding medium.

[Conventional technology]

The present applicant performs image exposure while applying a voltage between both electrodes of a photoconductor and a charge holding medium that are arranged opposite to each other,
An electrostatic image recording / reproducing method for forming a high-resolution electrostatic latent image on a charge holding medium 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 holding medium, 5
Is a photoconductive layer support, 7 is a photoreceptor electrode, 9 is a photoconductive layer, 11
Is an insulating layer, 13 is a charge storage medium electrode, 15 is an insulating layer support,
17 is a power supply.

FIG. 10 shows an embodiment in which exposure is performed from the photoreceptor 1 side. First, a transparent photoreceptor electrode 7 made of ITO having a thickness of 1000 mm is formed on a photoconductive layer support 5 made of glass having a thickness of 1 mm. The photoconductor 1 is formed by forming a photoconductive layer 9 of about 10 μm thereon. The charge holding medium 3 is arranged on the photoconductor 1 with a gap of about 10 μm. The charge holding medium 3 is placed on an insulating layer support 15 made of glass having a thickness of 1 mm.
An Al electrode 13 having a thickness of 0 mm is formed by evaporation, and
In this case, an insulating layer 11 having a thickness of 0 μm is formed.

First, as shown in FIG.
The charge holding medium 3 is set through a gap of about 10 μm.

In such a configuration, a voltage is applied between the electrodes 7 and 13 by the power supply 17 as shown in FIG. In a dark place, since the photoconductive layer 9 is a high-resistance material, there is no change between the electrodes, or the magnitude of the applied voltage and the leak current from the substrate electrode cause the Paschen discharge start voltage to be generated in the gap. When the above voltage is applied, discharge occurs in the air gap, and an electrostatic charge corresponding to a dark current is formed on the charge holding medium. When light is incident on the photoreceptor 1 side, photocarriers (electron holes) are generated in the photoconductive layer 9 at the portion where the light has entered, and charges of the opposite polarity to the charge holding medium electrode move toward the surface through the inside. If the voltage distribution in the air gap exceeds the Paschen discharge start voltage in the process, corona discharge occurs between the insulating layer 11 and the electric charge is drawn out of the photoconductive layer 9 by electric field emission, and accelerated by the electric field to insulate. Charge is stored in the layer 11.

After the exposure is completed, the voltage is applied as shown in Fig. 10 (c).
Turn off, and then take out the charge holding medium 3 as shown in FIG. As described above, the electrostatic latent image is formed by the ON / OFF of the voltage, that is, by the voltage shutter, so that a mechanical or optical shutter such as an ordinary camera can be omitted.

The photoconductive layer 9 is a conductive layer in which photocarriers (electrons and holes) are generated in the irradiated portion when light is irradiated, and the carriers can move in a layer width. In particular, an electric field exists. In this case, the effect is remarkable. The material is composed of an inorganic photoconductive material, an organic photoconductive material, an organic-inorganic hybrid type photoconductive material, or the like.

Inorganic photoreceptor materials include amorphous silicon, amorphous selenium, cadmium sulfide, zinc oxide and the like.

Organic photoconductors include a single-layer photoconductor and a function-separated photoconductor.

The single-layer type photoreceptor is composed of a mixture of a charge generating substance and a charge transporting substance, and the charge generating substance type is a substance that easily absorbs light to generate electric charges, such as an azo pigment, a disazo pigment, and a trisazo pigment. Pigments, phthalocyanine pigments, perylene pigments, pyrylium dyes, cyanine dyes, and methine dyes are used. Further, as the charge transporting substance system, a substance having good ionizing charge transporting properties, for example, hydrazone type, pyrazoline type, polyvinylcarbazole type, carbazole type, stilbene type, anthracene type, naphthalene type, tridiphenylmethane type, azine type, There are amine type and aromatic amine type.

In addition, the function-separated type photoreceptor has a property that the charge generating substance easily absorbs light but traps light, and the charge transporting substance has good charge transporting properties but poor light absorbing properties. Therefore, the two are separated so as to sufficiently exhibit their respective characteristics, and the charge generation layer and the charge transport layer are stacked. Examples of the material for forming the charge generation layer include, for example, azo, disazo, trisazo, phthalocyanine, acid xansen dye, cyanine, styryl dye, pyrylium dye, perylene, methine, a-Se , A-Si, azulhenium salt type, squarium salt type, etc., as the substance forming the charge transport layer, for example, hydrazone type, pyrazoline type, PVK type, carbazole type, oxazole type, triazole type, aromatic amine type, There are amine type, triphenylmethane type, polycyclic aromatic compound type and the like.

[Problems to be solved by the invention]

Generally, as a property of the generated carrier, the mobility μ is large and the life τ is short in the case of the inorganic photoconductor, and the mobility μ is small and the life τ is long in the case of the organic photoconductor, and μτ is almost the same. It is known that there is. The formation of an electrostatic latent image in voltage application exposure can be performed only with a mechanical exposure shutter or only with a voltage shutter. In the case of only a mechanical exposure shutter, a voltage is applied between the photoconductor and the charge holding medium. As a result, there is a problem that a dark current flows even during non-exposure and fog potential is generated.

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

FIG. 9 shows that the light intensity is constant and the voltage shutter time is 0.01.
FIG. 4 is a diagram showing the amount of charge on the charge holding medium when the time is changed to seconds, 0.1 seconds, and 1 second. In the case of an inorganic photoconductor, the carrier mobility is large, so that even if the voltage shutter time is changed as shown in the characteristic A The amount of charge will correspond to the amount of exposure. On the other hand, when an organic photoreceptor is used, as shown as a characteristic B,
When the voltage shutter time is 0.01 second and 0.1 second, a phenomenon occurs that the charge amount is different between 0.1 second and 1 second even if the exposure amount is the same. This is because the organic photoconductor is extinguished because the voltage is turned off before the carrier generated by exposure reaches the charge holding medium because the mobility of the carrier is small. Therefore, there is a problem that the image potential varies depending on the voltage shutter time even with the same exposure amount.

The present invention has been made to solve the above problems, and provides a voltage application exposure method that can obtain a charge amount according to an exposure amount regardless of a voltage shutter time even when an organic photoconductor is used. It is the purpose.

[Means for solving the problem]

FIG. 1 is a view for explaining a voltage application exposure method according to the present invention.

As described above, when the organic photoreceptor is used, when the voltage is turned off because the mobility of the carrier is small, the carrier generated by the exposure disappears when it reaches the charge holding medium. Therefore, as shown in FIG. 1, for example, the exposure shutter ON at time t _1, a voltage shutter ON, When shutting OFF the exposure shutter at time t _2, the time generated carriers reach on all the charge keeping medium Δt or Time t ₃ with allowance
To turn off the voltage shutter. By doing so, it is possible to form an image having a charge amount corresponding to the exposure amount. Since the time Δt from when the exposure shutter is turned off to when the voltage shutter is turned off varies depending on the material, thickness and the like of the photoconductor, the time Δt when these conditions are changed is obtained in advance and tabulated. After the setting, Δt is obtained by referring to this table, and the OFF timing of the voltage shutter may be set.

FIG. 2 is a diagram showing an example of an electrostatic camera using voltage application exposure, in which the same reference numerals as those in FIG. 10 denote the same contents, 21 is a photographing lens, 22 is a shutter, 23 is a mirror, twenty five
Is a focus glass, 27 is a pentaprism, 29 is an eyepiece, and 31 is a negative image.

The electrostatic camera uses the photoconductor 1 and the charge holding medium 3 shown in FIG. 10 instead of the film of the single-lens reflex camera. When the power supply 17 is turned on by operating a switch (not shown), the photoconductor and the charge are charged. A voltage is applied to the holding medium and
The shutter 22 is opened for the set time, the mirror 23 is flipped up to the position indicated by the dotted line, and an electrostatic latent image of the subject is formed on the charge holding medium 3. Then, a predetermined time after the shutter 22 is closed, the voltage application between the photoconductor and the charge holding medium is turned off. If necessary, a negative image 31 can be obtained by developing the charge holding medium with toner. It is also possible to read out the electrostatic potential and output it as an electric signal, display it on a CRT, or transcribe it to another recording means such as a magnetic tape.

[Action]

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

〔Example〕

 Hereinafter, examples will be described.

Example 1 An organic photoreceptor having a thickness of 10 μm was used for the photoreceptor, a fluororesin having a thickness of 3 μm was used for the charge holding medium, and a voltage of 750 V was applied with a 10 μm gap, with the photoreceptor side being positive. The light source used was a 3000 ° K color temperature dangsten lamp.

FIG. 3 shows the amount of exposure applied to the photoreceptor on the horizontal axis, and the potential recorded on the charge holding medium on the vertical axis. And turn off the voltage at the same time as the exposure turns off (Δt
= 0).

FIG. 4 shows the same sample as in FIG. 3, irradiation with light at the exposure intensity for 0.1 second, and application of the voltage for 0.1 second (Δt = 0.1 s).
This is the result when the application is continued.

Comparing FIG. 3 with FIG. 4, the potential recorded on the charge holding medium is a voltage pulse in FIG. 4 even though the amount of exposure applied to the photosensitive member is the same. 3 is synchronized with the exposure, a larger potential is obtained, and even after the optical shutter is closed, the effect of applying a voltage is remarkably exhibited.

Example 2 This is a case in which the voltage application time after light irradiation is set to 0.2 seconds (Δt = 0.2 s) under the same conditions as in Example 1. The result is as shown in FIG. 5, and a remarkable effect is obtained as compared with the case where the optical shutter and the voltage shutter in 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 = 0.3 s) under the same conditions as in Example 1. The result is as shown in FIG. 6, and a remarkable effect appears as compared with the case where the optical shutter and the voltage shutter 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 in Example 1. The result is shown in FIG. 7, which shows a remarkable effect as compared with the case where the optical shutter and the voltage shutter in FIG. 3 are synchronized.

Example 5 This is a case in which the voltage application time after light irradiation is set to 0.5 seconds (Δt = 0.5 s) under the same conditions as in Example 1. The result is shown in FIG. 8, which shows a remarkable effect as compared with the case where the optical shutter and the voltage shutter in FIG. 3 are synchronized.

〔The invention's effect〕

As described above, according to the present invention, it is possible to accumulate all generated carriers as electric charges on the electric charge holding medium and accumulate the electric charge amount corresponding to the exposure amount regardless of the voltage shutter time.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a 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 in which an optical shutter and a voltage shutter are synchronized. Showing the recording potential with respect to the exposure amount in the case, FIG. 4 to FIG.
FIG. 8 is a diagram showing a recording potential with respect to an exposure amount when the voltage shutter ON time after exposure is changed, FIG. 9 is a diagram for explaining a problem of the conventional voltage application exposure method, and FIG. FIG. 4 is a diagram for explaining an electronic image recording method. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 3 ... Charge holding medium, 5 ... Photoconductive layer support, 7 ... Photoconductor electrode, 9 ... Photoconductive layer, 11 ... Insulating layer, 13 ... Charge holding medium electrode, 15 ... insulating layer support, 17
... power, 22 ... shutter.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/05 H04N 1/032

Claims (1)

(57) [Claims] 1. A photoconductor having an organic photoconductive layer formed on a support with a conductive layer interposed therebetween and a charge holding medium having an insulating layer formed on the support with a conductive layer interposed therebetween. Place,
An exposure method for performing image exposure from the photoconductor side while applying a voltage between the conductive layers of the photoconductor and the charge holding medium to accumulate charge in an image-like manner on the charge holding medium, comprising:
A voltage application exposure method, characterized in that a voltage applied between the conductive layers is turned off after a predetermined time after turning off.