JP3135904B2 - Electrostatic image potential correction method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for correcting the potential of an electrostatic image by generating a maximum and / or minimum reference potential on a charge storage medium.

[Conventional technology]

The present applicant forms an electrostatic latent image on an insulating layer by disposing a photoconductive layer having electrodes and an insulating layer having electrodes facing each other and exposing the image while applying a voltage between both electrodes. We have already proposed a method.

FIG. 5 is a diagram for explaining such an electrostatic image recording method, in which 1 is a photoconductor, 3 is a charge holding medium, 5 is a photoconductive layer support, 7 is a photoconductor electrode, and 9 is a photoconductor electrode. A photoconductive layer, 11 is an insulating layer, 13 is a charge holding medium electrode, 15 is an insulating layer support, and 17 is a power supply.

FIG. 5 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,
As shown in FIG. 5B, a voltage is applied between the electrodes 7 and 13 by the power supply 17. In a dark place, since the photoconductive layer 9 is a high-resistance body, no change occurs between the electrodes. When light is incident from the photoreceptor 1 side, the photoconductive layer 9 in the portion where the light is incident shows conductivity, and a discharge occurs between the photoconductive layer 9 and the insulating layer 11.
The electric charge is accumulated.

When the exposure is completed, a voltage is applied as shown in FIG.
Turn off, and then take out the charge holding medium 3 as shown in FIG. 5 (d), thereby completing the formation of the electrostatic latent image.

The photoconductor 1 and the charge holding medium 3 may be of a contact type instead of a non-contact type as described above. In the case of the contact type, a positive or negative charge is applied to the exposed portion of the photoconductive layer 9 from the photoconductor electrode 7 side. Charges are injected, and the charges are drawn by the electrode 13 on the charge holding medium 3 side, pass through the photoconductive layer 9, and stop moving when reaching the surface of the insulating layer 11. Is done. Then, when the photoconductor 1 and the charge holding medium 3 are separated, the insulating layer
11 are separated while keeping the charge.

In the case of such a recording method as planar analog recording,
High resolution can be obtained in the same manner as silver halide photography, and the surface charge on the formed insulating layer 11 is exposed to the air environment.However, air has good insulation performance, so it can be used in bright places and dark places. Irrespective of the temperature, the battery is stored for a long time without discharging, and the charge storage period is determined by the properties of the insulator. In addition, it is described that the injected charges are simply accumulated on the surface, but microscopically penetrates into the vicinity of the surface of the insulator, and electrons or holes are trapped in the structure of the substance. In some cases, it is trapped inside the insulator, and long-term storage is performed. Further, if the surface of the insulating layer 11 is stored by covering it with an insulating film or the like in order to prevent physical damage of the charge holding medium or discharge when the humidity is high, storage can be performed for a longer period of time.

[Problems to be solved by the invention]

The electrostatic image potential formed on the charge holding medium as shown in FIG. 2 depends on the characteristics of the photoreceptor, the thickness of the photoreceptor, the gap, and the thickness of the charge holding medium, the voltage of the power supply voltage, the application time or the exposure time. It depends on the environment. Such a change in the initial image potential makes it impossible to faithfully reproduce recorded information. As described above, the electrostatic image recorded on the charge holding medium is
It can be stored for a long period of time, and in the ideal state, the image potential at the time of recording should be kept as it is, but in reality, leakage due to natural discharge may occur depending on environmental conditions such as ambient temperature and humidity. Inevitably, the potential of the electrostatic image decreases. If such a decrease in image potential occurs, it becomes impossible to faithfully reproduce recorded information.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an electrostatic image potential correction that reliably corrects an initial fluctuation and a temporal decrease of a recorded electrostatic image potential and enables faithful reproduction of an electrostatic image. The aim is to provide a method.

[Means for solving the problem]

For this purpose, the present invention disposes a photoreceptor having a photoconductive layer having electrodes formed thereon and a charge holding medium having an insulating layer having electrodes formed thereon, and performs image exposure by applying a voltage between the two electrodes. A method of recording an electrostatic image on an insulating layer by forming a bright portion and / or an unexposed portion comprising a maximum exposure portion on a charge holding medium to generate a reference potential, and based on the reference potential. It is characterized in that the image potential is corrected.

[Action]

In the present invention, when a photoreceptor and a charge holding medium are arranged facing each other to perform image exposure, at least one of a bright light portion including a maximum exposure portion and an unexposed portion is formed to form a maximum potential and / or a minimum potential on the charge holding medium. By generating the potential as a reference potential and measuring the reference potential in advance, the correction of the fluctuation of the initial image potential and the image potential correction using the fact that both the reference potential and the image potential attenuate equally, that is, as shown in FIG. By measuring the minimum potential and the maximum potential of the light intensity-potential curve to be corrected, the correction can be performed, and the electrostatic image can be faithfully reproduced.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

Since the recording of the electrostatic image in the present invention uses the method described with reference to FIG. 5, the details thereof will be omitted below.

FIGS. 1 to 4 show an embodiment of the present invention in which a bright light portion (maximum exposed portion) and an unexposed portion are formed on the surface of a charge holding medium. In the drawings, the same reference numerals as those in FIG. Is shown. Here, 151 is a bright light portion, 153 is an unexposed portion, 155 is an illumination light source, 157 and 160 are light shielding portions, 159 is an opaque electrode portion, and 161 is a photoconductive layer defective portion.

When an image is exposed while applying a voltage between the photosensitive member and the electrode of the charge holding medium as shown in FIG. 5, a potential distribution corresponding to the exposure intensity as shown in FIG. 2 is formed on the charge holding medium. Is done. This potential increases as the exposure intensity increases, but saturates above a predetermined value, and there is a maximum potential defined by the power supply voltage. Conversely, the exposure intensity decreases as the exposure intensity decreases, but the potential does not eventually reach 0,
Even before exposure, a dark current flows between both electrodes, and there is a minimum potential based on this. In the present invention, the maximum potential and the minimum potential are positively generated on the charge holding medium and used as reference potentials, and even when exposure is performed between the exposure amounts C and D in FIG. This is for correcting the image potential.

FIG. 1 shows a bright light portion 151 where the maximum potential is formed and an unexposed portion 1 where the minimum potential is formed on the charge holding medium 3.
53 is shown.

First, a method of forming the bright light portion 151 in FIG. 1 will be described with reference to FIG.

In FIG. 3A, the exposed portion 7a is formed by bending a part of the electrode 7 of the photoreceptor 1 so that the exposed portion 7a is exposed flush with the surface of the photoconductive layer facing the charge holding medium. It is. When such a photoreceptor is arranged to face the charge holding medium and the image is exposed by the method shown in FIG. 5, the area of the charge holding medium facing the electrode exposed portion 7a has a maximum value locally determined by the power supply voltage. And an electric charge is accumulated on the opposing charge holding medium so as to have the maximum potential.

In FIG. 3 (b), the thickness of a part of the electrode is increased to form an electrode-exposed portion 7b which is exposed flush with the surface of the photoconductive layer. An electric potential is generated.

FIG. 3 (c) shows an example in which light is emitted from an illumination light source 155 capable of obtaining a sufficiently large amount of light from the photoreceptor side to form a bright light portion by setting the exposed portion of the charge holding medium to a saturation potential.
A maximum potential is locally obtained in a region of the charge holding medium facing the illumination light source 1.

In FIG. 3D, a part of the photoreceptor 1 is removed by masking, etching, a solvent or the like so that the electrode 7d is exposed. In this case, (a), (b),
Unlike (c), they are not flush, so the difference in the maximum potential on the charge holding medium caused by the difference in the gap distance is:
It must be corrected in advance according to Paschen's law regarding discharge.

Next, a method of forming the unexposed portion 153 will be described with reference to FIG.

In FIG. 4 (a), a light shielding portion is provided on the surface of the electrode support.
157 formed. When such a photoconductor is exposed while facing the charge holding medium, the portion facing the light blocking portion 157 is not exposed, so that a minimum potential corresponding to the dark current is locally generated on the charge holding medium.

In FIG. 4 (b), a part of the transparent electrode is made of Al to make it opaque so as not to transmit light.
A minimum potential is generated in the same manner as in FIG.

In FIG. 4 (c), a transparent electrode is provided after forming an opaque portion on a part of the support by Al vapor deposition, and the minimum potential is the same as in FIGS. 4 (a) and 4 (b). Is generated. In this case, it is necessary to make the thickness obtained by vapor deposition or the like sufficiently smaller than the thickness of the photoreceptor in order to make them even.

In FIG. 4 (d), a defective portion 161 of the photoconductive layer, that is, a non-photoconductive portion is formed in a part of the photoconductive layer so that carriers are not generated even when irradiated with light. is there. In the non-photoconductive portion, carrier injection from the electrode occurs as in the dark-state photoconductive layer, and transport characteristics of the injected carrier occur in the dark-state photoconductive layer as well as the wavelength of the light to be exposed. On the other hand, any material can be used as long as it is non-photoconductive. In other words, any material that performs the same function as the unexposed photoconductive layer upon exposure can be used. An example of such a material is to use PVK / TNF as the photoconductive layer, use PVK alone as the non-photoconductive portion, A part containing no charge generating agent is provided as a non-photoconductive part. It is also possible to use an insulating polymer material whose resistance value is adjusted.

When a bright light portion and an unexposed portion are formed in this way,
As shown in FIG. 2, the maximum potential and the minimum potential are A,
If B is set, the potential of the portion where the image is recorded takes a value between A and B. Fluctuations in the initial image voltage due to the characteristics of the photoreceptor, each thickness, applied voltage, environment, and the like can be easily corrected by measuring the potential of the bright light portion and the unexposed portion.
Further, when the image potential decreases due to a change over time, the potentials of the bright light portion and the unexposed portion also attenuate similarly. Therefore, if the potentials of the bright light portion and the unexposed portion are measured in advance, the potential of the exposed portion can be easily corrected.

In the above description, an example is shown in which both the bright light portion and the unexposed portion are provided, but only one of them may be provided.

〔The invention's effect〕

As described above, according to the present invention, a bright potential portion and / or an unexposed portion are provided to set a reference potential, and by measuring this potential, the initial fluctuation and the decay with time of the image potential are based on the reference potential. Correction can be performed easily and an electrostatic image can be faithfully reproduced.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a bright light portion and an unexposed portion on a charge holding medium, FIG. 2 is a diagram for explaining an image potential correcting method, and FIG. 3 is a diagram for explaining a bright light portion forming method. Figure, 4th
FIG. 5 is a diagram for explaining a method of forming an unexposed portion, and FIG. 5 is a diagram for explaining an electrostatic 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 supply, 151… bright part, 153… unexposed part, 155…
Illumination light source, 157: Shielding part, 159: Opaque electrode part, 161
... Defects in photoconductive layer.

Continuation of the front page (56) References JP-A-57-67948 (JP, A) JP-A-56-92549 (JP, A) JP-A-54-102125 (JP, A) JP-A-57-105837 (JP, A) , A) JP-A-58-189873 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/05 H04N 1/00 H04N 1/04

Claims (6)

(57) [Claims] 1. A photoreceptor having a photoconductive layer on which an electrode is formed and a charge holding medium having an insulating layer on which an electrode is formed are opposed to each other, and a voltage is applied between the two electrodes to perform image exposure. An electrostatic image recording / reproducing method of recording an electrostatic image on an insulating layer by separating an electric charge holding medium and reproducing recorded information by an electrostatic image potential of the electric charge holding medium. Forming a bright portion and / or an unexposed portion including a reference portion, generating a reference potential, and correcting the image potential based on the reference potential. 2. The electrostatic image potential according to claim 1, wherein said bright light portion comprising said maximum exposure portion is formed by exposing a part of a photoreceptor electrode to a photoconductive layer surface and exposing it. Correction method. 3. The electrostatic image potential correcting method according to claim 1, wherein the bright light portion comprising the maximum exposure portion is formed by providing an illumination light source on a back surface of the photosensitive member. 4. The electrostatic image potential correcting method according to claim 1, wherein said unexposed portion is formed by providing a light-shielding portion on an electrode support of a photosensitive member. 5. The electrostatic image potential correcting method according to claim 1, wherein said unexposed portion is formed by making a part of the photoconductive layer of the photoreceptor opaque. 6. The electrostatic image potential correcting method according to claim 1, wherein said unexposed portion forms a part of a photoconductive layer of a photosensitive member as a non-photoconductive portion.