JPS6113230B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic apparatus that can simultaneously form a first image and a second image.

As electrophotographic methods, electrofax method, Xerox method, PIP method, NP method (for example, Japanese Patent Publication No. 42-23910, etc.) are known. The electrofax method and Xerox method form electrostatic images using the so-called Carlson process, in which a photoconductor layer of zinc oxide (Electrofax), non-quality selenium (Xerox), etc. is placed on a support. The photoconductor surface of the formed photosensitive plate is uniformly charged by corona discharge, and then an original image is irradiated to attenuate the charge in the irradiated area, and an electrostatic image that follows the light and dark pattern of the original image is created using charged colored particles. After being developed and visualized, it is fixed or transferred onto another support such as paper and then fixed to obtain an electrophotographic image, and the PIP method is based on the physical properties of fluorescent substances, etc. That is, a latent image is formed using persistent internal polarization and photoconductivity, while the NP method uses the capacitance difference and photoconductivity between the photoconductor layer and the insulating layer used above it. An electrostatic image is formed, and then an electrophotographic image is obtained through development, transfer, and fixing steps in the same manner.

To date, copying devices using these electrophotographic methods have been developed, but there are devices that overlap multiple originals on a photosensitive plate and expose them to form a composite latent image, which is then developed into a developed image. Although the demand for these products has been increasing, there has been no product that fully satisfies this demand, and their uses have been extremely limited. In addition, such a composite image forming process itself obtains a composite image using optically composite images or electrically composite signals, and involves different steps that make up the electrostatic image forming process. Superimposition or overlay methods for combining to form a composite image on a photosensitive plate have been extremely limited.

SUMMARY OF THE INVENTION In response to the above-mentioned needs, it is an object of the present invention to improve the previously proposed methods and provide a simple apparatus for performing overlay using the first and second steps of the electrostatic image forming process. be.

Next, embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram of the structure of a photosensitive plate for forming an electrostatic image according to the present invention, and 1 is a conductive support 2 coated on the conductive support 1 by spraying or using a coater, a faller, etc. In the coated photoconductive layer, a small amount of binder, mainly a resin, may be added, if necessary, to improve bonding with other layers. Reference numeral 3 denotes an insulating layer that is uniformly formed in close contact with the photoconductive layer 2 . In this way, the photosensitive plate A is basically formed of three layers: the conductive support 1, the photoconductive layer 2, and the insulating layer 3. A layer for trapping charges may be formed between the support and the photoconductive layer, and may also or solely be added to the surface or near the surface of the photoconductive layer. In addition, it is preferable that the photoconductive property has as high a resistance as possible in a dark place.

The conductive support 1 is made of a metal conductor such as tin, copper, or aluminum, or hygroscopic paper, but a support made of paper with aluminum foil attached is inexpensive and is used by wrapping it around a drum or the like. This is convenient if you want to do so. The material of the photoconductive layer is CdS, CdSe, crystalline
Se, ZnO, ZnS, Se, TiO ² , SeTe, PbO, or a mixture thereof can be used.

Some such photoconductive layers have a charge injection property in which charges of a specific polarity are injected from the conductive support into the photoconductive layer when charged in the dark. In embodiments, if such properties have an undesirable effect on the charge distribution due to the first light image irradiation performed almost simultaneously with the primary charging, such charge in the dark may be used as the primary charging polarity. It shall be charged with a polarity that does not cause injection. In the case of a photoconductive material that does not substantially have a charge injection property, or even if it does have it, it does not substantially affect the charge distribution due to the above-mentioned photoimage irradiation, it can be charged to either polarity.

The material constituting the insulating layer 3 may be any material that satisfies the following three requirements: high abrasion resistance, high resistance and ability to retain static charge, and transparency, and may include fluororesin, polycarbonate resin, polyethylene resin, Coatings such as cellulose acetate resin and polyester resin can be used, and fluororesin in particular has the property of being easy to clean. Preferred materials in embodiments.

FIGS. 2 and 5 illustrate the process of forming a composite latent image on the photosensitive plate constructed as described above and the charging pattern of the photosensitive plate.

In FIG. 2, first, when the surface of the insulating layer 3 of the photosensitive plate A is charged negatively (-) by a corona discharger 4 in a dark place, the photoconductive layer 2 has a high resistance in the dark and becomes conductive. A positive (+) charge 32 is induced at the interface between the support 1 and the photoconductive layer 2 or at a portion of the photoconductive layer 2 close to the conductive support 1 (FIG. 2). Through this process, the surface potential of the insulating layer 3 increases negatively (-) with the charging time, and exhibits the characteristics shown in FIG. 6Vp. Of course, the charging may be performed using an electrode instead of corona discharge.

Next, a first optical image is irradiated from the insulating layer surface 3 side. At this time, in the bright area of the photosensitive plate A, since the photoconductive layer 2 becomes conductive due to optical stimulation, the interface between the conductive support 1 and the photoconductive layer 2 or the conductive support 1 of the photoconductive layer 2 is caused by pre-charging. The positive (+) charges 32 induced near the photoconductive layer 2 and the insulating layer 3 are attracted by the negative (-) charges on the surface of the insulating layer 3.
moves to the interface of and stops there. On the other hand, in the dark area, since the resistance value of the photoconductive layer 3 is high, the charge state is maintained almost as it is (FIG. 3). Through this process, the surface potential of the insulating layer 3 exhibits characteristics as shown in FIG. 6, VL (potential on the surface of the insulating layer in the bright part) and Vb (potential on the surface of the insulating layer in the dark part).

Next, an alternating current corona discharge is applied to the surface of the insulating layer 3 by an alternating current corona discharger 8 almost simultaneously with the second light image irradiation (FIG. 4).

In addition, since the corona discharger 4 and the AC corona discharger 8 perform discharge almost simultaneously with the irradiation of the light image, it is preferable that the upper part thereof is transparent or has an optically open structure without a shield plate.

The part that was a dark part during the first light image irradiation,
Negative (-) charge 3 on the surface of the insulating layer 3
1 has no binding force, so all or most of it is discharged.

Further, the interface between the photoconductive layer 2 and the insulating layer 3 where the photoconductive layer 2 is made conductive by optical stimulation also in the bright area during the first optical image irradiation and in the bright area in the second optical image. The positive (+) charges 33 that had been stuck on the surface are now easily released to the conductive support 1, so the negative (-) charges 31 that had been charged on the surface of the insulating layer 3 lose their binding force and stop. All or most of the accumulated positive (+) charges 33 are discharged. The amount of these discharges depends on the AC corona discharge time and intensity.

On the other hand, in the part that was a bright part when the first light image was irradiated and a dark part when the second light image was irradiated, the resistance value of the photoconductivity 3 was high and the conductive support of the positive (+) charge 33 remained near the interface. Since there is no emission to the body 1, the negative (-) charges 31 on the surface of the insulating layer 3 are restrained by the positive (+) charges 33, and the negative (-) charges 31 on the surface of the insulating layer 3 are discharged by the alternating current corona. The degree of irradiation is smaller than that of the dark part when the first light image is irradiated or the bright part when the second light image is irradiated.

In this way, when the first optical image is bright and the second optical image is dark, the amount of negative (-) charges remaining on the surface of the insulating layer 3 is large, but at the same time, the amount of negative (-) charges remaining on the surface of the photoconductive layer 2 is large. Since a large amount of positive (+) charges 33 remain trapped, the field due to the surface charges of the insulating layer 3 acts quite strongly in the direction of the positive (+) charges 33 remaining on the photoconductive layer 2. The external field due to surface charges becomes extremely small.

Next, the entire surface of the insulating layer 3 is exposed from the surface side (or from this side if the conductive support is translucent) (FIG. 5).

In the dark part of the first optical image or the bright part of the second optical image, the electric charge distribution state in the photoconductive layer 2 does not substantially change, so the potential on the surface of the insulating layer 3 also changes. As in Figure 3, the potential is almost 0. However, in the bright part of the first light image and the dark part of the second light image, the photoconductive layer 2 exhibited high resistance because there was no light irradiation during exposure of the second light image; As a result, the resistance value decreases rapidly and becomes conductive. Therefore, the positive (+) charges 33 that had been trapped inside the insulating layer 3
All but an amount of charge equivalent to the negative charge 31 on the surface of the conductive support 1 is released to the conductive support 1 and disappears. As a result, the negative charge 31 on the surface of the insulating layer
, the external field increases rapidly and the surface potential increases. (FIG. 5) Changes in the surface potential of the insulating layer 3 due to these processes exhibit characteristics as shown in FIG. In other words, the potential of only the bright area during the first light image irradiation and the dark area during the second light image irradiation is significantly negative than V _LD , and in the other areas, V _DD , V _DL , V _LL
It becomes almost zero potential.

Therefore, if this photoreceptor A is developed with toner, the first
A composite image of the light image and the second light image is visualized. 7th
The figure shows the case where development is performed with a toner having a polarity opposite to the primary charge polarity, that is, a toner having a positive polarity.
The toner adheres to the bright areas when the first light image is irradiated and to the dark areas when the second light image is irradiated. Figure 8 shows reversal development, that is, development with a toner having the same negative polarity as the above-mentioned primary charging polarity. adhere to. In this case, it is well known that better development can be achieved if a developing electrode is used.

Figures 9 to 12 show examples of such composite image formation, in which a is the original of the first optical image, b is the original of the second optical image, and c is the toner with positive polarity. d shows a composite microscopic image of a and b when developed, and d shows a composite microscopic image of a and b when developed with toner having negative polarity. As can be seen from these composite images, different composite images can be obtained according to the light and dark patterns of the first and second light images and their yin and yang, and can be selected depending on the purpose.

Next, the visible image formed on the surface of the insulating layer is transferred onto a transfer material 11 such as paper by applying a corona discharge 10, an external voltage such as a bias voltage, or an internal electric field, as shown in FIG. Finally, the transferred image is fixed by a fixing means such as infrared rays, a hot plate, or pressure fixing to obtain an electrophotographic image.

On the other hand, since the photosensitive plate is used repeatedly, after the transfer is performed, the surface of the insulating layer is cleaned by a known cleaning method to remove charged particles remaining on the surface. At this time, the cleaning effect will be increased if the cleaning is performed after the electrostatic image formation charges that have been accumulated on the surface of the insulating layer in the bright areas of the original image are removed mainly by recharging. To do this, before cleaning, the surface of the insulating coating may be subjected to an alternating current corona discharge to eliminate the charge caused by the electrostatic image formation, and then cleaning may be performed with an elastic blade, fur brush, or the like. In that case, the cleaning effect can be enhanced by providing the cleaning means with a potential of opposite polarity to that of the charged colored particles.

The cleaning effect also depends on the properties and tackiness of the material of the insulating film, so all of the above-mentioned resins are suitable as the electrostatic image forming material according to the present invention, but among them, fluorine The resin coating is the most effective in that it has excellent non-adhesive properties and assists in the removal of charged colored particles during cleaning, resulting in a remarkable cleaning effect.

Preferable electrostatic images for development include (1) a sufficient surface potential difference between the above-mentioned V _LD and V _DD , V _DL , and V _LL ;

(2) No surface potential difference occurs between the V _DD , V _DL , and V _LL .

It is. In order to satisfy these (1) Photoconductive substance 2 (2) First and second exposure amounts (3) Polarity and intensity of the initial charge (4) Intensity of AC corona discharge It is necessary to set the following appropriately.

Next, a quantitative explanation of one embodiment of the electrophotographic method according to the present invention is as follows.

100g of cadmium sulfide activated by copper
Add 10g of vinyl chloride, add a small amount of thinner, mix, and apply the photosensitive material to a thickness of about 50μ on an aluminum cylinder with a polished surface. Next, an insulating layer with a thickness of 35 μm is laminated on the surface of this photoconductive film to obtain a photosensitive plate. Next, a +7KV corona discharge is applied to the surface of the insulating layer of the photosensitive plate to uniformly charge it with a positive (+) charge. Next, the first light image (the bright part is approximately
12 lux (light intensity for 0.3 seconds), and then
A second light image having the same amount of light as the first light image is irradiated almost simultaneously with the alternating current corona discharge of AC7.5KV. Further, the entire surface is uniformly exposed to light at about 12 lux for about 0.8 seconds to form a high-contrast electrostatic image on the surface of the insulating layer. When the surface potential during this electrostatic image formation process is measured with a surface electrometer, the part corresponding to V _D in Fig. 6 is +1700V, the part corresponding to V _L is 1400 V, and the part corresponding to V _LD and V _LL , V _DD , V The surface potential difference with _{the DL} equivalent part is approximately
I got a 400V one.

Next, as an embodiment of the present invention, an apparatus in which an overlay function such as a fixed format is added to a laser beam recording apparatus will be described in detail with reference to the drawings.
FIG. 14 is a perspective view of this embodiment, and FIG. 15 is a cross-sectional view of the same embodiment.

In FIGS. 14 and 15, a document 11 in a standard format is placed on a document table 10 that can be moved in synchronization with laser light, as described later, and is illuminated by a document exposure lamp 12, and the document image is reflected. The original image is bent by the mirror 13 toward the imaging lens 14, and is exposed onto the photosensitive drum 20 as a first exposure described later.

Second exposure, which will be described later, is performed on the photosensitive drum 40 using a laser beam that is synchronized with the exposure of an original image in a standard format or the like. This laser beam second exposure will be explained below.

A laser beam oscillated by a laser oscillator 21 is guided to an input aperture of a deflection/modulator 23 via a reflection mirror 22. The reflecting mirror 22 is inserted to bend the optical path in order to reduce the space of the apparatus, and can be removed if unnecessary. For the deflection/modulator 23, an acousto-optic deflection/modulation element using a known acousto-optic effect or an electro-optic element using an electro-optic effect is used. In the deflection/modulator 23, the laser beam is subjected to intensity modulation and deflection according to the input signal to the deflection/modulator 23.

In addition, when the laser oscillator is a semiconductor laser, or when using an internally modulated laser such as a gas laser that can perform current modulation or a type that incorporates a modulation element in the oscillation optical path, the modulator 2 is used.
3 is unnecessary. The light from each of these light sources passes through a suitable optical system and then enters a beam expander 24.
reach.

The beam diameter of the laser beam from the modulator 23 is expanded by a beam expander while it remains a parallel beam. Furthermore, the laser beam whose beam diameter has been expanded is incident on a polyhedral rotating mirror 25 having one or more mirror surfaces. The polyhedral rotating mirror 25 is mounted on a shaft supported by a high-precision bearing (for example, an air bearing) and driven by a motor 26 that rotates at a constant speed (for example, a hysteresis synchronous motor, a DC servo motor).
is horizontally scanned by a polyhedral rotating mirror 25 driven by. This scanning may be performed using galvano mirrors.

The laser beam horizontally scanned by the polyhedral rotating mirror 25 passes through an imaging lens 27 having f-θ characteristics.
As a result, an image is formed on the photosensitive drum 40 as a spot.

In a general imaging lens, when the incident angle of the light ray is θ,
Regarding the image forming position r on the image plane, there is the following relationship: r=f・tanθ−(1) (f: focal length of the imaging lens). , the angle of incidence of the reflected laser beam 28 on the imaging lens 27 changes linearly with time. Therefore, the moving speed of the imaged spot position on the photosensitive drum 40, which is the image surface, changes non-linearly and is not constant. That is,
The speed of movement increases at the point where the angle of incidence increases. Therefore, when a row of spots is drawn on the photosensitive drum 40 by turning on the laser beam at regular time intervals, the spacing between the spots will be wider at both ends than at the center. In order to avoid this phenomenon, the imaging lens 27 is designed to have the following characteristics: r=f·θ (2).

Such an imaging lens 27 is called an f-θ lens. Furthermore, when collimated light is imaged into a spot by an imaging lens, the minimum diameter of the spot dmin is dmin=fλ/A...(3) where f: focal length of the imaging lens λ; wavelength of the light used A: Given by the entrance aperture of the imaging lens; if f and λ are constant, a smaller spot diameter dmin can be obtained by increasing A. The beam expander 24 mentioned above is used to provide this effect. Therefore, if the required dmin can be obtained by the beam diameter of the laser oscillator, the beam expander 24 is omitted.

The beam detector 29 consists of a small entrance slit and a photoelectric conversion element (for example, a pIN diode) with a fast response time. The beam detector 29 detects the position of the swept laser beam 28 and uses this detection signal to determine the start timing of a horizontal scanning input signal to the modulator 23 for providing desired optical information on the photosensitive drum. do. As a result, it is possible to greatly reduce synchronization errors in the horizontal direction signals due to errors in the division accuracy of each reflective surface of the polygonal rotating mirror 25 and rotational unevenness, and to obtain a high-quality image. The tolerance range of accuracy required for this method is widened, and it can be manufactured at a lower cost.

In the manner described above, the laser beam 28 modulated by the external signal is exposed onto the photosensitive drum 40 as second exposure, which will be described later.

Next, the printing section shown in FIGS. 14 and 15 will be described. First, the surface of the insulating layer of the photosensitive plate 40, which basically consists of a conductive support, a photoconductive layer, and an insulating layer, is uniformly charged negatively (-) by a corona discharger 41 for initial charging. Next, the surface of the insulating layer, which is uniformly negatively charged, is subjected to first exposure, which is an original image in a standard format or the like. When the first exposure portion of the photosensitive plate 40, which is rotating in the direction of the arrow, comes to the position of the AC corona discharger 42, a laser beam, which is a second exposure synchronized with the first exposure, is emitted. Exposure is performed on the surface of the insulating layer, and at about the same time, the AC corona discharger 42 removes static electricity from the surface of the insulating layer. Next, the lamp 43 exposes the entire surface of the insulating layer. Through the above process, a surface potential difference is created between the bright part (white background) of the original image in the first exposure of the photosensitive plate and the part not hit by the laser beam in the second exposure, and the other parts to form a composite electrostatic image. form. In this case, a negative (-) charge remains on the surface of the insulating layer in a portion that is a bright portion in the first exposure and a dark portion in the second exposure, and the other surface of the insulating layer has approximately zero potential. Next, the composite electrostatic image is developed and visualized by a developing means 44 using a developer mainly composed of negatively (-) charged colored particles for reversal development, and then the composite electrostatic image is visualized on a transfer material 45 such as paper. A visible image is transferred using an internal or external electric field 46, and then the transferred image is fixed by a fixing means 47, such as an infrared lamp hot plate or a pressure fixing means, to obtain an electrophotographic print image 48. On the other hand, after the transfer is performed, the surface of the insulating layer of the photosensitive plate 40 is cleaned by a cleaning means 49 to remove remaining charged particles, and the photosensitive plate 40 is used repeatedly.

As described above, in this example, when reversal development is performed,
Because charged colored particles adhere to the dark part of the first exposure and the bright part of the first exposure and the bright part of the second exposure (see Figure 8), the format of the original as the first exposure A positive original, which is easy to create, can be used, and the signal control of the laser beam for the second exposure can use the control method of a laser beam recording device, which has been developed in recent years, as is.

Furthermore, although this embodiment has been described with reference to a device in which an overlay function such as a fixed format is added to a laser beam recording device, the present invention can also be applied to a device in which an overlay function such as a fixed format is added to an electrophotographic copying machine, such as a CRT. It is similarly effective for devices that use a laser instead of a laser, and devices that combine an electrophotographic copying machine and a microfilm enlargement printing machine.

Next, an example of a method for positionally synchronizing the first optical image and the second optical image will be described. Of course the first
There are cases where it is not necessary to synchronize the optical image and the second optical image. For example, when the first light image or the second light image is used repeatedly for a pattern on a printed material, a squash pattern, etc. The explanation in this case will be omitted.

There are the following types of combinations of the first optical image and the second optical image to be synchronized.

(1) The first light image is the reflected light of the original, and the second light image is the laser light. (2) The first light image is the reflected light of the original, and the second light image is the reflected light of the original. (3) The first light is Laser light on the image, laser light on the second light image (4) Laser light on the first light image, reflected light of the original on the second light image Instead of the reflected light of the original, light transmitted through the film-like original, microfilm Expanded transmitted light, etc., laser light, spot exposure of beam light, etc.
Spot light from a CRT or the like may also be used.

Below, one embodiment of how to achieve synchronization will be explained step by step for cases 1 to 4 above.

First, case (1) is the case of the above-mentioned device embodiment. When the document table 10 moving at a constant speed moves to a predetermined position in FIGS. 14 and 15, it is detected by, for example, a micro switch (not shown), and a ready signal is generated as shown in the time chart of FIG. do. Thereafter, exposure of the top portion of the document is started after a certain period of time _T1 . Further, after the adjustment time, data is inputted and laser beam exposure is started.

The time difference T ₂ between the start of exposure of the top part of the original and the start of laser beam exposure is T ₂ =E ₂ -E ₁ /VP, where E ₂ -E ₁ is the difference between the first light image exposure part and the second light image exposure part. Distance to the exposure section VP: This is the circumferential speed of the photosensitive drum.

The time chart at this time is shown in Figure 16. Here, T ₁ is determined mechanically, that is, by the relationship between the mounting position of the ready signal generating switch on the document table and the top position of the document, and T ₂ is electrically set by a known counting means or the like.

Next, an example of how to achieve synchronization in the case (2) in which the original reflected light is applied to the first optical image and the original reflected light is applied to the second optical image will be described.

This will be explained using the explanatory diagram shown in FIG. 1st
And if the top position of the second original (11-1, 11-2) and the position of the exposure part (E ₁ , E ₂ ) on the first and second photosensitive drum surfaces are set in the following relationship. The first and second documents can be synchronized.

l ₂ −l ₁ /Vf=E ₂ −E ₁ /Vp However, l ₁ ; The moving distance of the document table until it rises during constant speed movement, or a greater distance than this l ₂ - _{l 1} ; First and second Displacement amount of the top of the document Vf; Speed of the document table 10 Vp; Peripheral speed of the photosensitive drum 20 E ₂ −E ₁ ; Distance between the first light image exposure section and the second light image exposure section. A well-known means may be used as a specific means for achieving synchronization.

Next, an example of case (3) will be shown. A laser beam is used for the first optical image and a laser beam is used for the second optical image, and they are synchronized at T ₂ at the start of the first laser beam exposure.
after which a second laser light exposure is started;
The time T ₂ may be electrically set to a time that satisfies the following relationship.

T ₂ =E ₂ −E ₁ /Vp However, E ₂ −E ₁ ; Distance between the first light image exposure section and the second light image exposure section Vp; Circumferential speed of the photosensitive drum An example will be shown in which a laser beam is used for the first optical image and original reflected light is used for the second optical image. An explanatory diagram is shown in FIG. When the document table 10, which moves at a constant speed, reaches a predetermined position, it issues a ready signal as shown in FIG. Then, after an adjustment time, the data is input and laser beam exposure 28 is started. The time is adjusted so that the top of the original 11 is exposed when the laser beam exposure starting portion of the photosensitive drum rotates and comes to the original reflected light exposure position, that is, the second light image exposure position. The time difference T ₂ between the start of laser beam exposure data input and the start of top exposure of the original 11 is T ₂ = E ₂ - _{E 1} /Vp, where E ₂ - _{E 1} is the laser beam exposure position, that is, the first light image exposure position. Distance of the original top light exposure position, that is, the second light image exposure position Vp: This is the circumferential speed of the photosensitive drum, and the time T ₁ from the generation of the ready signal to the start of top exposure of the original 11 is T ₁ =lr-f/Vf However, lr-f is the distance between the ready signal generation switch mounting position and the document top position (not shown), and Vf is the moving speed of the document table 10.

Generation of the ready signal is made possible by installing a micro switch or the like to be turned on by movement of the document table.

As can be seen from the time chart shown in FIG. 17, the time from receiving the ready signal to the start of data input/exposure by the laser beam and the start of top exposure of the original, that is, (T ₁ to T ₂ ), is adjusted. The data input timing is adjusted to synchronize the top of the manuscript.

The method for synchronizing the first optical image and the second optical image has been briefly described above.

As described in detail above, the present invention includes a movable photosensitive plate whose basic components are a conductive support, a photoconductive layer, and an insulating layer, and a method in which the surface of the insulating layer of this movable photosensitive plate is charged and thereby conductive. a charge imparting means for inducing a charge having a polarity opposite to that on the surface of the insulating layer at or near the interface between the photoconductive layer and the photoconductive layer; and a charge imparting means for eliminating charge from the photosensitive plate after being acted on by the charge imparting means. an AC charge eliminating means; a first image light exposure means for exposing the photosensitive plate to a first image light at a position between the operating position of the charge applying means and the operating position of the AC charge eliminating means; a second image light exposure means that exposes a region of the photosensitive plate irradiated with the first image light with a second image light at a working position;
an entire surface exposure means for uniformly exposing the entire surface of the photosensitive plate after being acted on by the AC static elimination means, the surface potential of the portion that was a dark area in both the first light image and the second light image, An electrostatic latent image is formed in which the surface potential of the dark area, the bright area in the second light image, and the bright area in both the first and second light images are approximately zero potential. However, this electrophotographic device develops this electrostatic latent image using toner charged to only one type of polarity.

Therefore, by combining the first image and the second image, various composite latent images can be formed using the second and third steps of latent image formation. Since V _DD , V _DL , and V _LL are approximately zero potential, the surface potential of this composite latent image is the surface potential V _LD portion, and the surface potential V _DD ,
It is possible to obtain a developed image in which the V _DL and V _LL portions are clearly distinguished. Therefore, the image forming apparatus can be adapted to a wide range of uses, and is extremely useful for synthetic recording of various data and information.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of the structure of a photosensitive plate that can be applied to the present invention, and FIGS. 2 to 5 show how the photosensitive plate shown in FIG. , an explanatory diagram showing the process of forming a composite latent image, and FIG. Figures 7 and 8 are diagrams showing the process of developing a latent image, Figure 9 is a diagram showing the process of transferring a transparent image, and Figure 10 is a diagram showing the process of developing a latent image.
Figures a, b, c, d to Figure 13 are explanatory diagrams showing the original patterns of the first and second images and the composite microscopic image, and Figure 14 is an electronic image according to the present invention. FIG. 15 is a perspective view of an embodiment of the photographic apparatus, FIG. 15 is a cross-sectional view thereof, and FIGS. 16 and 17 are time charts of the synchronization method of exposure for first and second image formation in the embodiment of the present invention. Figures 18 and 18 respectively show
FIG. 19 is an explanatory diagram showing two examples of the synchronization method. DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Photoconductive layer, 3... Insulating layer, A, 20... Photosensitive plate, 4, 41... Charge imparting means, 8, 42... AC charge eliminating means, 43... Whole surface exposure means.

Claims (1)

[Scope of Claims] 1. A movable photosensitive plate whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer; the surface of the insulating layer of this movable photosensitive plate is charged, and thereby the conductive support charge applying means for inducing a charge having a polarity opposite to that on the surface of the insulating layer at or near the interface between the photoconductive layer and the photoconductive layer; and an AC charge removing means for removing charge from the photosensitive plate after being acted on by the charge applying means. and a first image light exposure means for exposing the photoreceptor to first image light at a position between the action position of the charge imparting means and the action position of the AC charge removal means, and at the action position of the AC charge removal means. , a second image light exposure means for exposing a region of the photosensitive plate irradiated with the first image light with a second image light; and an entire surface for uniformly exposing the entire surface of the photosensitive plate after being acted on by the AC static elimination means. an exposure means, a surface potential of a portion that was a dark portion in both the first light image and the second light image, a surface potential of a portion that was a dark portion in the first light image and a bright portion in the second light image, and a surface potential of a portion that was a dark portion in the first light image and a bright portion in the second light image; Electrons form an electrostatic latent image in which the surface potential of the bright portion of both the optical image and the second optical image is approximately zero potential, and develop this electrostatic latent image with toner charged to only one type of polarity. Photographic equipment.