JPH07120123B2 - Image holding member, image forming method and electrophotographic method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image holding member and an image holding method for storing image information by the movement of particles in a heat softening resin, and a plurality of continuous copies using the image holding member. The present invention relates to an electrophotographic method for forming an image.

[0002]

2. Description of the Related Art In the conventional electrophotographic copying method, the surface of an electrophotographic photosensitive member is uniformly charged, then imagewise exposure is performed to attenuate the surface potential in an imagewise manner, and then toner development is performed. The Carlson method of transferring to paper is widely applied as a general method. However, in this method, each time one image is copied, exposure must be performed once. Therefore, high-speed copying complicates the device,
There was a problem of increasing the size.

In order to improve this point, a system has been proposed in which image information is stored in an electrophotographic photosensitive member and a large number of copies are obtained by one image exposure. For example, JP-A-53
-102037 and JP-A-2-269357 describe that a specific compound is added to a photosensitive layer to obtain a continuous photoreceptor. However, it is difficult to obtain a satisfactory one in terms of storage time of image information, contrast at the time of copying, and the like. On the other hand, U.S. Pat. No. 4,883,731 describes an electrophotographic system in which photosensitive particles move inside a heat-softening layer to store image information and make a large number of copies.

FIGS. 9 to 16 are views for explaining the case. In these figures, reference numeral 80 denotes a photosensitive original plate, which is a substrate 81, a conductive layer 82, and a thermoplastic resin softened by heat. It is composed of a heat-softening layer 83 containing a charge-transporting substance, and photosensitive particles 84 embedded in the vicinity of the surface of the heat-softening layer to generate charges by light.

In using this photosensitive original plate,
As shown in FIG. 9, first, the corona charger 60 uniformly negatively charges the surface. Next, as shown in FIG. 10, imagewise exposure is performed with an imagewise light beam 61. As a result, the photosensitive particles in the exposed portion generate positive and negative charges, the positive charges are transported to the surface to neutralize the surface charges, and the negative charges remain in the particles. Then, FIG.
As shown in FIG. 1, when heated by the heat ray 62, the charged particles in the photosensitive particles move in the layer softened by electrostatic attraction. That is, the particles 842 that move according to the image due to heating
Of the image holding member 9 in a state of being divided into a portion including the particles and a portion including the particles 841 held in the state without moving.
0 is formed.

In order to make a copy using the image holding member 90 in such a state, first, as shown in FIG. 12, the surface is uniformly positively charged by the corona charger 71. Then Fig. 1
As shown in 3, light irradiation 72 is performed on the entire surface. Thereby,
The photosensitive particles generate electric charges, but since the portion having the particles 841 in the original position and the portion having the moved particles 842 have different potential attenuation characteristics, that is, the particles 84
Since the portion having 1 has a higher sensitivity and the attenuation is faster, a difference in surface potential occurs, and a latent image having a higher potential is formed in the portion having the particles 842. Then, as shown in FIG.
15 is used for developing, and further, as shown in FIG.
Form a toner image on top. After that, as shown in FIG.
The electric potential of the portion having is attenuated, and the image holding member returns to the original state.

By repeating the steps shown in FIGS. 12 to 16 for this image holding member, it is possible to perform a copying operation on a large number of sheets by simply charging and irradiating the entire surface without requiring an image exposure step. Since the image holding member after copying is unnecessary, a new photosensitive original plate 80 is prepared again. In the case of negative charging during uniform charging in FIG. 12, when the next whole surface irradiation 72 is performed, the surface charge of the portion having the particles 842 is attenuated and the portion having the particles 841 is developed. As a result, an inverted toner image is obtained as compared with the case shown in FIG.

[0008]

The above electrophotographic method is
This is a very preferable method when a large number of copies are made by one image exposure. However, as photosensitive particles,
Since selenium is used, the spectral sensitivity is dominated by selenium. FIG. 8 is a graph showing the spectral sensitivity characteristics of the photosensitive layer, and B is the spectral sensitivity curve of the photosensitive layer using selenium.

In recent years, as a light source for image exposure, a method of operating image-wise modulated laser light with a rotary reflecting mirror has become widespread with the progress of electronic technology. It is common practice to use 780 nm laser diodes. However,
As is clear from FIG. 8, the photosensitive layer using selenium is 78
Since it has no sensitivity to 0 nm, it has a drawback that it is not possible to write an image with such a laser beam. Furthermore, in the above electrophotographic method, when copying,
There is a problem that the entire surface light irradiation as shown in FIG. 13 must be repeated for each sheet, and although image exposure is unnecessary, simplification of the process is still required.

An object of the present invention is to provide an image holding member and an image forming method which are writable with light having a wavelength of 780 nm and which can make a large number of copies with one image exposure. Another object of the present invention is to provide an electrophotographic method capable of continuously performing copying at a high speed by repeatedly charging and developing.

[0011]

The image holding member of the present invention comprises:
A charge generation layer and a heat-softening layer containing a charge-transporting substance and a heat-softening resin are sequentially laminated on the conductive surface of a substrate having a conductive surface, and conductive particles are embedded near the surface of the heat-softening layer. It is characterized in that it is provided with a conductive particle layer formed by the above method.

The image forming method of the present invention comprises the above-mentioned image holding member.
Negative charge is applied to the surface of the to accumulate charge in the conductive particles,
Then, by performing image exposure corresponding to the image information to eliminate the charge of the conductive particles in the exposed area, the heat-softening layer is heated to a temperature above the softening point of the heat-softening resin to accumulate the charge. Conductive particles that have been moved in the thermal softening layer,
It is characterized by storing image information.

In the electrophotographic method of the present invention, the step of charging the image holding member in which the image information is stored by the above-mentioned image forming method, the formed electrostatic latent image is formed using the electrophotographic developer. By repeating the steps of developing and developing, and transferring the formed visible image to a transfer paper, a copy image is continuously formed.

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of an image holding member of the present invention. An image holding member 10 has a conductive layer 2 formed on a substrate 1 and a charge generation layer 3 provided thereon. Furthermore, a heat-softening layer 4 made of a charge-transporting substance and a heat-softening resin which is softened by heat is further provided thereon.
Conductive particles 5 are embedded near the surface of the thermal softening layer 4 to form a conductive particle layer.

In the image holding member of the present invention, as the substrate, any material can be used as long as it can be used in an electrophotographic photoreceptor such as plastic film, paper, metal foil, glass and the like. The shape is not particularly limited, and any shape can be used.

The substrate must have at least a conductive surface. The conductive surface may be formed by providing a conductive layer. The conductive layer may be made of any material as long as the charge flows freely. For example, a metal film is formed by a method such as a vapor deposition method, a sputtering method, a plasma CVD method, a plating method, or a metal or a metal having a low resistance is used. A conductive paint in which conductive particles such as oxides are dispersed in resin may be applied. Also, if the substrate is conductive, it is not necessary to form a conductive layer. An undercoat layer may be provided on the conductive surface in order to improve adhesiveness, chargeability, image quality, and the like.

The charge generation layer provided on the conductive surface of the substrate is the same as the charge generation layer used in a usual function-separated electrophotographic photoreceptor. That is,
As the charge generating material, a phthalocyanine pigment such as metal or metal-free phthalocyanine, a squarylium compound, an azurenium compound, a perylene pigment, an indigo pigment, a quinacridone pigment, anthanthrone, a brominated anthanthrone, pyranthrone, a polycyclic quinone such as flavanthrone,
A cyanine dye, a xanthene dye, a charge transfer complex composed of poly-N-vinylcarbazole and trinitrofluorenone, a eutectic complex composed of a pyrylium dye and a polycarbonate resin, and the like are used as a binder resin and optionally a charge transporter. It may be formed by dispersing and coating the material. Further, a film formed by vapor-depositing the charge generating material, a vapor-deposited film of amorphous silicon, or the like is also effective. Furthermore, it is also possible to use a titanyl phthalocyanine or bisazo pigment having a specific crystal structure which has been developed in recent years. The thickness of the charge generation layer is usually 0.1 to 2
It is set in the range of μm.

As the charge-transporting substance used in the heat-softening layer, any substance can be used as long as it is used in the charge-transporting layer in the electrophotographic photosensitive member. For example, polycyclic aromatic compounds such as anthracene, pyrene, and phenanthrene, compounds having a nitrogen-containing heterocycle such as indole, carbazole, and imidazole, pyrazoline compounds, hydrazone compounds, triphenylmethane compounds, triphenylamine compounds, stilbene compounds, benzidine Examples include compounds.

As the thermosoftening resin, a glass transition point (T
A thermoplastic resin having a g) of 30 to 90 ° C. and a viscosity at a temperature of Tg or higher of 10 ² to 10 ⁶ poise is preferably used. For example, polyethylene, vinyl chloride resin, polypropylene, styrene resin, ABS resin, polyvinyl alcohol, acrylic resin, acrylonitrile-
Styrene resin, vinylidene chloride resin, AAS (AS
A) resin, AES resin, fibrin derivative resin, thermoplastic polyurethane, polyvinyl butyral, poly-4-methylpentene-1, polybutene - 1, rosin ester resin and the like, among which styrene-acrylic acid ester copolymer A terpolymer of styrene-acrylic acid ester-acrylic acid is particularly preferable. The film thickness of the heat softening layer is usually set in the range of 3 to 15 μm.

A single layer or a plurality of layers of conductive particles are formed in the vicinity of the surface of the heat softening layer, that is, within several times the diameter of the conductive particles from the surface. The size of the conductive particles is 0.05
It is preferably in the range of ˜1 μm. If the size of the conductive particles is too large, it becomes difficult for the conductive particles to move, and
If it is too small, it becomes difficult to be charged, which is not preferable. Also,
When the conductive particles have a thin film shape, they are difficult to move, which is not preferable.

As the conductive material forming the conductive particles, carbon black, copper iodide, silver iodide, zinc sulfide, silicon carbide and the like, as well as metal oxides are preferably used. In particular, metal oxides containing oxygen vacancies and those containing a small amount of a foreign atom forming a donor with respect to the metal oxide used are preferable because they have high conductivity, that is, they contain many electron-hole pairs. . Examples of metal oxides include
ZnO, SnO ₂ , TiO ₂ , In ₂ O ₃ , MoO
₃ or the like, or a composite oxide of these, and examples of containing a different atom include ZnO, Al, In, etc.
Examples thereof include those containing Nb and Ta for TiO ₂ and those containing different atoms such as Sb, Nb, In and halogen elements for SnO ₂ . The addition amount of these heteroatoms is 0.0
The range of 1 to 30 mol% is preferable, and the range of 1 to 10 mol% is particularly preferable.

As a method for forming the conductive particle layer by embedding these conductive particles in the vicinity of the surface of the thermal softening layer, vapor deposition method (resistance heating, electron beam heating), ion plating method, glow discharge sputtering method, An ion beam sputtering method or the like can be used. For example, in the case of the vapor deposition method, the thermosoftening layer may be heated to be in a softened state and the conductive material may be evaporated under a low pressure of 10 to 10 ⁻³ Torr. As a result, the conductive material is aggregated on the surface of the heat-softening layer to form a fine particle having a particle size of 1 to 0.1 μm, and the particles are aligned in a single layer or in a plurality of layers to form a surface of the heat-softening layer. Embedded in the vicinity of.

The glow discharge sputtering method known as a method for forming a transparent conductive film on a plastic film such as polyester can be used as it is for producing the image holding member of the present invention. Also in this case, by heating the thermosoftening resin in advance, the conductive material becomes fine particles and a conductive particle layer is formed near the surface.

As another method of forming the conductive particle layer in the vicinity of the surface of the heat-softening layer, the conductive particles are dispersed in a coating solution having the same composition as the coating solution for forming the heat-softening layer, and the dispersion is heated. A wet method of coating on the softening layer can be applied. In this case, when the dispersion liquid is applied, it is necessary to quickly dry the coating film of the dispersion liquid so that the thermosoftening layer existing in the lower layer is not dissolved.

Next, an image forming method for storing image information in the image holding member manufactured as described above will be described with reference to the drawings. 2 to 4 are drawings for explaining the image forming method. First, as shown in FIG.
By moving the corona charger 60 relative to 0,
Apply a negative charge to the surface. As a result, the above-mentioned conductive particles have electron-hole pairs at room temperature, and holes are immediately released to the negative charge on the surface to neutralize the surface charge through the charge transport material. Then, negative charges remain inside the conductive particles. At that time, when the surface potential is measured, it is 80 to 80% as compared with the case where the conductive particles are not present.
It is about 95%.

Next, as shown in FIG. 3, image exposure is performed. Reference numeral 61 is light that sensitizes the charge generation layer, and most of the light reaches the charge generation layer 3 through the sufficiently thin conductive particle layer. In the case of the diode laser light, it is image-wise modulated by an electronic means and exposed, and in that case, the light may be applied to the portion to which the developer is attached.
As a result, positive charges are injected from the charge generation layer into the thermal softening layer and are transported through the layer to neutralize the negative charges of the conductive particles. On the other hand, the conductive particles in the part that was not exposed to light,
Negative charge remains.

Thereafter, as shown in FIG. 4, the image holding member is heated by heat 62. As a heating method, any method such as a method of passing through a heating roller, a method of putting in a heating container, a method of heating with a heating wire, or the like can be adopted, and heating is performed at a temperature of Tg or higher for several seconds. As a result, the conductive particles having the negative charges remaining therein move to the side of the base body to be an electrode in the heat-softened layer which is softened and whose viscosity is lowered, by electrostatic attraction. On the other hand, the heating lowers the electrical resistance of the thermosoftening layer, and the electric charge of the conductive particles suddenly discharges spontaneously.Therefore, all the conductive particles do not move to the electrode side, and the particle size and charge Due to variations in density, etc., they are sparsely distributed in the thermal softening layer and stop. In this way, a portion containing the moved conductive particles (moving particles 52) is formed.

Next, when the image holding member is returned to room temperature, the image holding member 20 in which the image information is stored is obtained. In addition, since the light transmittance is reduced in the portion where the conductive particles have moved, it is possible to visually confirm the difference in light and shade.

Next, an electrophotographic method for obtaining a copy by using the image holding member in which the image information is stored as described above will be described. As shown in FIG. 5, the entire surface of the image holding member in which the image information is stored is negatively charged. As a result, the conductive particles that have not moved (non-moving particles 5
In the portion where 1) is present, as in the case shown in FIG. 2, negative charges remain on the conductive particles, and the surface potential is about 85 to 95% of the case where no conductive particles are present. On the other hand, in the portion where the moved conductive particles (moving particles 52) are present, positive charges are sequentially injected from particles closer to the electrode to neutralize the negative charges on the surface side, and as a result, The surface potential is 0 to 20%, which is very low compared to the case where no conductive particles are present. Therefore, only uniform negative charging on the entire surface
A latent image having an electrostatic contrast according to the image is formed.

The latent image thus formed is developed using a positively chargeable developer. This makes the latent image visible,
Then, by a conventional method, a copy can be obtained by transferring to a transfer paper.

Then, by recharging, a latent image can be formed as shown in FIG. 5, and therefore copying can be continuously performed without performing image exposure. After copying, cleaning can be performed as needed.

[0032]

Example 1 A polyester film having a thickness of 50 μm and having a conductive layer on which aluminum was vapor-deposited was used as a substrate. Cyclohexanone 19 parts by weight in advance with polyvinyl butyral resin (S-REC BM-1, manufactured by Sekisui Chemical Co., Ltd.) 1
8 parts by weight of a solution prepared by dissolving 1 part by weight was mixed with 1.6 parts by weight of X-type phthalocyanine and 12.8 parts by weight of cyclohexanone, and glass beads having a diameter of about 2 mm were used as a dispersion medium.
The dispersion treatment was performed for about 1 hour using a paint shaker. The obtained dispersion was applied onto the conductive layer with a wire bar and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.3 μm.

On the other hand, 62 parts by weight of styrene, 36 parts by weight of ethyl acrylate, and 2 parts by weight of acrylic acid were used as starting materials.
Weight average molecular weight of about 80 synthesized using toluene as solvent
00 terpolymer was prepared. The Tg of this polymer is 48
C. and the viscosity at 110.degree. C. was 28,000 poise. 78 parts by weight of this polymer and N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-
Biphenyl] -4,4 'diamine (22 parts by weight) was dissolved in toluene (500 parts by weight). The resulting solution is applied on the charge generation layer with a wire bar and the temperature is 110 ° C. for 1 hour.
After drying for 5 minutes, a heat softening layer having a film thickness of 8 μm was formed. This thermal softening layer functions as a charge transport layer.
And the laminated structure of this thermal softening layer and charge generation layer
When the spectral sensitivity of the layer was measured, the result indicated by the curve A in FIG. 8 was obtained, and it was confirmed that the layer had sufficient practical sensitivity in the wavelength 780 nm portion.

Next, this film is 220 mm × 300
Cut to a size of mm and I under pressure of 10 ^-1 Torr
n ₂ O ₃ was vapor deposited. At that time, the film was attached to a stainless steel plate, and the entire surface was heated to 110 ° C. By controlling the deposition time to a short time, In
₂ O ₃ particles were formed embedded in the surface of the thermosoftening layer. The formed image holding member had the sectional structure shown in FIG.

This image holding member was negatively charged under the condition of -800V. As a result, the negative charge becomes In ₂ O ₃
Transferred to the particles, the surface potential became −750V. (Fig. 2) Next, using a diode laser, 12 ergs /
Image exposure was performed with an intensity of cm ² (FIG. 3). At that time, while conveying the film on a roller having a diameter of 25 mm, the bent portion thereof is irradiated with laser light,
It was possible to prevent stripes from appearing on the image due to interference of laser light. (See JP-A-1-281475) After that, in the dark, the film was passed over a heat roll kept at 115 ° C. for a heating time of 5 seconds to perform overheat treatment. As a result, the In ₂ O ₃ particles in the unexposed portion moved to the substrate side. (Figure 4)
As described above, the storage by writing the image is completed.

The image holding member in which the obtained image information is stored is wound around an aluminum pipe of 108 mm × 340 mm, charged at -800 V, developed with a two-component positively charged developer, transferred to A4 paper, and brush cleaned. Was mounted on an electrophotographic copying machine. As shown in FIG. 5, the latent image is charged by the charger 60 and has a surface potential of −100 V in the portion containing the moving particles 52 and −750 V in the portion containing the non-moving particles 51. Was formed. This latent image was developed with a two-component positively charged developer and transferred to obtain a copy image having a high contrast. This process is performed at a speed of 100 sheets per minute,
It was carried out repeatedly. As a result, it was confirmed that there was no problem even when continuous 2000 sheets were copied.

Example 2 80 parts by weight of styrene and 20 parts by weight of hydroxymethacrylate were synthesized as monomers, and the weight average molecular weight was about 1.
2000, Tg 38 ° C, 110 ° C viscosity 25000
A poise copolymer was prepared. An image holding member was produced in exactly the same manner as in Example 1 except that this copolymer was used as a thermosoftening resin. In this image holding member, although the adhesion strength of the heat softening layer is slightly inferior to that in the case of Example 1,
Image formation could be carried out in the same manner, and continuous copying was possible.

Example 3 The film was continuously coated with a web coater. FIG. 6 is a side view of the web coater, in which the film is supplied from the roll 16 and the paint drawing roll 1
The coating liquid is applied to the surface of the film by 3 and the coating roll 12, is dried through the drying zone 14, and is wound up by the winding roll 15. Reference numeral 17 is a pressing roll, and 18 is an exhaust duct. The film thickness can be controlled by the concentration of the coating liquid, the rotation speed of the coating roll, and the like. Using this web coater, the same substrate and material as in Example 1 were used to coat the charge generation layer at a rate of 30 cm / sec and the heat softening layer at a rate of 20 cm / sec to obtain a coated film having a length of 100 m. .

Then, conductive particles were continuously attached by a magnetron sputtering apparatus. FIG. 7 is a diagram showing a schematic configuration of a magnetron sputtering apparatus. In a vacuum chamber 21, a magnetron 22 targeting an indium-tin (10%) alloy and an annular gas (argon and oxygen) are supplied to the tip. A shield 23 having a mouth 31 is arranged. The film is fed from roll 28,
It is conveyed through the surface of the rotating drum 29 held at 110 ° C. and wound on a roll 30. On the other hand, around the film, a shield 24 having a slit on the front surface of the target, an aluminum plate 25, and a Teflon insulator 26 are provided, and the aluminum plate 25 is coupled to a high frequency circuit through a cooled high frequency waveguide 27.

With this magnetron sputtering device, particles of indium-tin oxide (ITO) (particle size: about 0.3 μm) were conveyed while the film was conveyed at a speed of 5 cm / sec.
Was formed near the surface of the heat softening layer. According to this method
A large number of image holding members could be produced. The obtained image holding member could be used in the same manner as in Example 1.

Example 4 A charge generation layer and a thermal softening layer were formed in the same manner as in Example 1. On the other hand, ITO powder was prepared, and this was mixed with 60 parts by weight of the same coating solution for forming a heat softening layer as in Example 1 at a ratio of 1 part by weight and dispersed by a paint shaker. The particle size after dispersion was about 0.2 μm. With a wire bar, this dispersion liquid on the heat-softening layer,
Apply quickly to a dry film thickness of 0.5 μm and
It was dried at 0 ° C for 10 minutes. The obtained image holding member could be used in the same manner as in Example 1.

[0042]

Since the image holding member of the present invention has the above-mentioned structure, a wide range of exposure light source can be used by selecting the charge generating material. For example, wavelength 780
It is possible to easily use a diode laser of nm, and it is also possible to correspond to an arbitrary one such as a light emitting diode and a liquid crystal shutter module. Further, the image holding member of the present invention is capable of continuously copying a large number of sheets with one image exposure. Therefore, according to the image forming method and the electrophotographic method of the present invention, the copying process is very simple and continuous copying can be performed at high speed. For example, high speed copying of 100 sheets or more per minute is possible. It is possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image holding member of the present invention.

FIG. 2 is a diagram illustrating an image forming process of the present invention.

FIG. 3 is a diagram illustrating an image forming process of the present invention.

FIG. 4 is a diagram illustrating an image forming process of the present invention.

FIG. 5 is an explanatory diagram of an electrophotographic method using the image holding member of the present invention.

FIG. 6 is a side view of a web coater for making the imaging member of the present invention.

FIG. 7 is a schematic configuration diagram of a magnetron sputtering apparatus for manufacturing the image forming member of the present invention.

FIG. 8 is a graph showing a spectral sensitivity characteristic of a photosensitive layer.

FIG. 9 is a diagram illustrating a conventional image forming process.

FIG. 10 is a diagram illustrating a conventional image forming process.

FIG. 11 is a diagram illustrating a conventional image forming process.

FIG. 12 is an explanatory diagram of an electrophotographic method using a conventional image holding member.

FIG. 13 is an explanatory diagram of an electrophotographic method using a conventional image holding member.

FIG. 14 is an explanatory diagram of an electrophotographic method using a conventional image holding member.

FIG. 15 is an explanatory diagram of an electrophotographic method using a conventional image holding member.

FIG. 16 is an explanatory diagram of an electrophotographic method using a conventional image holding member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Conductive layer, 3 ... Charge generation layer, 4 ... Thermal softening layer, 5 ... Conductive particles, 10 ... Image holding member, 20 ... Image holding member storing image information, 51 ... Non-moving particles, 52 ... Moving particles 1, 60 ... Corona charger, 61 ... Light, 62 ... Heat

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/05 16/00

Claims (5)

[Claims] 1. A charge-generating layer and a heat-softening layer containing a charge-transporting substance and a heat-softening resin are sequentially laminated on the conductive surface of a substrate having a conductive surface, and the heat-softening layer is provided near the surface of the heat-softening layer. An image holding member comprising a conductive particle layer formed by embedding conductive particles. 2. The image holding member according to claim 1, wherein the conductive particles are conductive metal oxide particles. 3. The surface of the image holding member according to claim 1 is negatively charged to accumulate electric charges in the conductive particles, and then image exposure corresponding to image information is performed, whereby the conductivity of the exposed portion is reduced. After the charge of the conductive particles is eliminated, the thermosoftening layer is heated to a temperature equal to or higher than the softening point of the thermosoftening resin to move the conductive particles in which the charge is accumulated in the thermosoftening layer, and to display image information. An image forming method characterized by storing. 4. The image forming method according to claim 3, wherein image exposure is performed using a laser beam modulated by an electric signal. 5. A step of charging an image holding member having image information stored therein by the image forming method according to claim 3, a step of developing the formed electrostatic latent image with an electrophotographic developer, An electrophotographic method characterized by continuously forming copied images by repeating each step of transferring the formed visible image onto a transfer paper.