JP2581060B2 - Latent image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a latent image forming method using a ferroelectric substance.

Prior art Since the invention of the Carlson method (1938, USP 222176), the basic process of electrophotography is a method of corona charging a photoreceptor, exposing the image, developing the toner, transferring the toner to paper, and fixing it. Has been taken.

Therefore, even when copying the same image many times, the above steps must be repeated from the beginning. As long as the Carlson method is basically used, there is naturally a limit in simplifying the process and making it suitable for repeated copying.

As a copy method different from the Carlson method, a method using an inorganic ferroelectric substance (Japanese Journal of
Applied Physics (Japanese Journal of Appl
ied Physics), Volume 16, (1977), Supplement 16-1, Volume 325
328) has been proposed. In this method, the inorganic ferroelectric is subjected to liquid development utilizing the property of causing remanent polarization when irradiated with light under a certain electric field.

However, the above method is a wet development method, and furthermore, the erasing (erasing) of the latent image must be performed by heating.
It has the disadvantage that the erase speed is slow.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel copying method which is easy and quick to write and erase, and is suitable for copying many sheets by writing a single latent image. .

Means for Solving the Problems That is, the present invention comprises a stack of a photoconductive layer and a ferroelectric layer capable of forming remanent polarization, and a photoconductive layer having a thickness of 5 mm.
In a latent image recording body having a thickness of about 50 μm, the photoconductive layer is made conductive by uniform exposure and uniform voltage applying means in advance to form a uniform saturated internal polarization inside the ferroelectric layer. Optical information is given to the contacting photoconductive layer to make the optical information portion conductive, and when a saturated internal polarization is formed inside the ferroelectric layer, a voltage of the opposite polarity is applied to apply the voltage to the ferroelectric layer. The present invention relates to a latent image forming method characterized by inverting the polarization of an optical information portion.

The polarized latent image formed by the above method may be developed, transferred and fixed by a method adopted in a conventional general electrophotographic copying method.

Specific means for fixing and cleaning from a latent image are shown in FIGS. Hereinafter, the present invention will be described with reference to FIGS. 1 to 8, but the present invention is not limited thereto.

A preferred method for embodying the present invention comprises at least a ferroelectric layer (1), a photoconductive layer (2) and a transparent electrode (3).
Is used. The latent image recording body was uniformly exposed from the transparent electrode (3) side while applying a bias voltage to the ferroelectric layer (1) to form a saturated internal polarization in the ferroelectric layer (1). A latent image forming means for providing optical information while applying a bias voltage having a polarity opposite to that of the bias voltage to form a persistently saturated internal polarization is provided. This latent image is developed by toner developing means capable of electrostatically adsorbing charged toner having the opposite polarity to the latent image on the ferroelectric layer (1). The developed toner is transferred to paper and fixed. Next, the surface of the ferroelectric layer (1) is cleaned, and then uniform exposure and uniform voltage application (the same polarity as in the initial stage of the present process) are performed to return to the uniform saturated internal polarization state in the initial stage of the present process again. ,
Enter the following light information. Further, when the first optical information is to be retained and copied (multiple copies), the steps shown in FIGS. 4 to 7 may be repeated.

The latent image recording body includes at least a ferroelectric layer (1), a photoconductive layer (2), and a transparent electrode (3) (FIG. 1).

The transparent electrode may be any one having both properties of translucency and conductivity, for example, In ₂ O ₃ -SnO ₂ on PLZT .1 to 0.
Vacuum evaporation or spattering to a thickness of 5 μm may be performed, and a transparent resin or glass may be inserted from above.

Examples of the photoconductive substance that can be used in the photoconductive layer include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, bilylium dyes, and azo pigments. Organic substances such as plasma polymerized films such as quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments, phthalocyanine pigments, and thiophene, and selenium. , Selenium / tellurium, selenium / arsenic, cadmium sulfide, amorphous silicon and the like.

Amorphous silicon and phthalocyanine pigments are particularly preferred.

In addition, any material that absorbs light and generates charge carriers with extremely high efficiency can be used.

Next, phthalocyanine pigments particularly suitable for the present invention will be described in detail.

In this example, a photoconductive layer formed by dispersing a phthalocyanine-based photoconductive material powder in a binder resin is formed on a ferroelectric layer, ITO is vacuum-deposited on the photoconductive layer, and then sandwiched with a transparent resin. It is a thing. Further, the phthalocyanine-based photoconductive material powder is coated or adsorbed with a charge transporting material, and the phthalocyanine-based photoconductive member is applied on PLZT and fired.

As the phthalocyanine-based photoconductive material used in this example, any of phthalocyanines and derivatives thereof known per se can be used, and specifically, copper, silver, beryllium, magnesium, calcium, gallium, zinc, cadmium, barium, Mercury, aluminum, indium, lanthanum, neodymium, samarium, europium,
Gadolinium, dysprosium, holmium, sodium, lithium, ytterbium, lutetium, titanium,
A phthalocyanine containing tin, hafnium, lead, thorium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium, platinum and the like as a central nucleus.
Also, instead of metal atoms as the central core of phthalocyanine,
It may be a metal halide having a valence of 3 or more. Furthermore, metal-free phthalocyanine derivatives such as copper-4-aminophthalocyanine, iron polyhalophthalocyanine, cobalt hexaphenylphthalocyanine, tetraazophthalocyanine, tetramethylphthalocyanine, and dialkylaminophthalocyanine can be used. These can be used alone or in combination.

A phthalocyanine derivative in which a hydrogen atom of a benzene nucleus in a phthalocyanine molecule is substituted with at least one kind of electron-withdrawing group selected from the group consisting of a nitro group, a cyano group, a halogen atom, a sulfone group and a carboxyl group, phthalocyanine and the phthalocyanine; At least one unsubstituted phthalocyanine compound selected from compounds,
A phthalocyanine-based photoconductive material composition obtained by mixing with an inorganic acid capable of forming a salt with them and precipitating with water or a basic substance can also be used. In this case, as the electron-withdrawing group-substituted phthalocyanine derivative, any one having 1 to 16 substituents in one molecule can be used, and the electron-withdrawing group-substituted phthalocyanine derivative and another unsubstituted phthalocyanine compound can be used. The composition ratio of
It is preferred that the number of the former substituents is 0.001 to 2, preferably 0.002 to 1, per unit phthalocyanine molecule in the composition. As the inorganic acid capable of forming a salt with the phthalocyanine compound used when producing the phthalocyanine-based photoconductive material composition, sulfuric acid, orthophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid, And hydrobromic acid.

Among the photoconductive materials, particularly preferable for achieving the object of the present invention are metal-free phthalocyanine, copper phthalocyanine, aluminum chlorophthalocyanine, titanyl phthalocyanine, and derivatives thereof, for example, a nuclear electron-withdrawing group-substituted derivative. can give.

As the electrically insulating binder resin in the present example, any of known binders such as a thermoplastic resin or a thermosetting resin, a photocurable resin, or a photoconductive resin, which is electrically insulating, can be used. .

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), styrene- Thermoplastic binders such as butadiene block copolymers, polycarbonates, vinyl chloride-vinyl acetate copolymers, cellulose esters, and polyimides; epoxy resins, urethane resins, silicone resins, phenolic resins, melamine resins,
Thermosetting binders such as xylene resins, alkyd resins, and thermosetting acrylic resins; photocurable resins; photoconductive resins such as poly-N-vinylcarbazole, polyvinylpyrene, and polyvinylanthracene.

These electrically insulating resins were measured alone to be 1 × 10 ¹⁴ Ω
It is desirable to have a volume resistance of at least cm.

As the charge transport material described above, generally known compounds such as hydrazone-based, oxadiazole-based, triphenylmethane-based, pyrazoline-based, and styryl-based compounds can be used. Among them, a hydrazone compound represented by the following general formula [I] is particularly preferable.

Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group, an aralkyl group or an aryl group which may have a substituent, a condensed polycyclic group which may have a substituent, A Represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group, and n represents a number of 1 or 2. R ₂ and R ₃ may combine to form a ring. These compounds are described, for example, in JP-A-54-150128.
JP-A-55-46760, JP-A-55-154955, JP-A-55-52063, and the like.

Further, as the charge transporting material, polyvinyl carbazole or polyvinyl anthracene which is itself a polymer may be used.

The photoconductive layer has a thickness of 5 to 50 μm, preferably 6 to 30 μm. The photoconductive layer is formed by means corresponding to the material, for example, vapor deposition, sputtering, resin coating, CVD, plasma CVD, ion plating, or the like. Form.

The present invention can be achieved if the ferroelectric used for the ferroelectric layer (1) has a remanent polarization and the remanence is maintained. This will be described in more detail below.

FIG. 9 shows a hysteresis curve representing the polarization characteristics of the ferroelectric. The horizontal axis shows the applied bias voltage, and the vertical axis shows the polarity and magnitude of the polarization. When a positive bias voltage is applied to the surface of the ferroelectric (1), the ferroelectric layer (1) Polarized so that a positive polarity appears on the surface (bias voltage application side) and a negative polarity appears on the opposite side,
In this case, the polarization direction is positive. Ferroelectric layer (1) the size of the polarization in the application of internal polarization occurs + Vb is applied a bias voltage is substantially constant saturated (this point and S _1). The saturation polarization does not become 0 even by returning the applied voltage to zero, remains at the size of P _2. The P ₂ called residual polarization, the present invention is an application of the persistence of the residual polarization. Further internal polarization is longer when a bias voltage is applied to the negative, in the application of -Vb, + if you Vb applied opposite polarity internal polarization of saturated (this point and S _2). Then, the residual polarization P ₁ of the opposite polarity is observed with P ₂ Solving bias voltage. Saturated with applied again + Vb, return to _the point S. Thereafter, when the sweep of the bias voltage is performed between + Vb and −Vb, the ferroelectric material exhibits a polarization characteristic represented by a hysteresis curve connected by S ₁ , P ₂ , S ₂ , and P ₁ .

The ferroelectric material exhibits a hysteresis curve as described above, residual polarization P ₁ and P ₂ between the 0.2~100μc / cm ^2, preferably 0.9~50μc / cm ^2, more preferably indicates 1.5~30μc / cm ² There is no particular limitation as long as the remanent polarization is long-lasting. However, if the density is lower than 0.2 μc / cm ² , a sufficient density cannot be obtained when the toner is developed. 100μc / c
Although higher than m ² is theoretically possible, such substances are not known at present.

However, the internal polarization is represented by a value obtained by calculating D by a known DE hysteresis curve method and calculating the charge amount / (per unit area) from the value.

As a ferroelectric material exhibiting such persistent remanent polarization, for example, a transparent ceramic obtained by adding La ₂ O ₃ to a Pb (Zr, Ti) O ₃ -based solid solution and available as PLZT from Hayashi Kogyo Co., Ltd. is used. Preferably, what is called PLZT (70/60/35) is preferable. Hereinafter, the present invention is described by taking as an example the case where the PLZT (70/60/35) (hereinafter simply referred to as PLZT) is used for the ferroelectric layer (1).

The ferroelectric layer (1) is formed on the photoconductive layer (2) to a thickness of 50 μm or more, preferably 100 μm or more, by a hot press method or the like. If the thickness is less than 50 μm, processing is required due to the structure, the cost is increased, and the film is easily broken. However, this does not apply to the case where a thin film is formed on a substrate by using vacuum film formation or alcoholate.

FIGS. 1 to 8 show the concept of a series of copying processes utilizing the present invention.

In this copying process, first, the ferroelectric layer (1)
Is applied with a bias voltage by an appropriate means, and is further uniformly exposed from the side of the transparent electrode (3), so that the surface of the ferroelectric layer (1) is uniformly and continuously applied so that its surface becomes positive or negative. Polarization is induced (FIG. 2 (initial polarization step). Such internal polarization is achieved by irradiating the photoconductive layer (2) with light to make the photoconductive layer conductive. It occurs quickly at a speed on the order of seconds and continues even after the application of the bias voltage.In the following description, a negative bias voltage is applied to the surface of the ferroelectric layer (1) to apply the bias voltage to the ferroelectric layer (1). The case where the surface is induced to be positive will be described.The opposite case, that is, the case where a positive bias voltage is applied, is the same as the following description except that the positive and negative are reversed.
The voltage is preferably about 0.3 to 5 V / μm, and the application method is not particularly limited as long as the ferroelectric substance (the surface of 1 is uniformly applied). The method includes applying a voltage by scanning the surface of the body layer (1) and applying the voltage using a conductive roller (4). An exposure lamp (5) or a semiconductor laser beam can be used as appropriate, depending on the thickness of 2), the type of the photoconductive substance used therein, etc. In the initial polarization step, a ferroelectric substance is used. layer (1) is a state represented by a point in FIG. 9 in T _2.

After the remanent polarization is uniformly generated in the ferroelectric layer (1), only the portion desired to be embodied as information such as characters, for example, a semiconductor laser beam having a wavelength of 780 nm (GaAlAs semiconductor laser beam) is scanned by a polygon mirror. Then, a positive bias voltage reverse to that of the initial polarization step is applied to perform reverse polarization to form a polarization latent image (12) (latent image formation step) (fourth step).
Figure). Polarization latent image (12) portion is represented by the state of the ninth point of figure S _1. The magnitude of the bias voltage applied in the latent image forming step is equal to or smaller than the magnitude of the bias voltage applied in the initial polarization step. By doing so, the voltage of the driving IC can be reduced, which is advantageous in terms of practicality and cost.

After the completion of the latent image forming step, if it is desired to realize a portion irradiated with light, the polarized latent image (12) is developed with a toner (6) charged to a positive polarity opposite to the negative surface polarity (FIG. 4).
(Referred to as a developing step). When it is desired to realize a portion that has not been irradiated with light, a toner having a negative polarity may be developed. For the development, known means, for example, magnetic sleeve (7) development or cascade development can be applied.

The developed toner (6) is transferred to the transfer paper (9) from the back of the transfer paper by a conductive roller (9) or a corona charger (not shown) to a polarity opposite to that of the toner (6). 8) (transfer step) (FIG. 5). Alternatively, the image may be transferred to transfer paper by using the action of an electric field.

The transfer paper (8) to which the toner has been transferred is fixed by an appropriate means, for example, by a heating roller (10) (fixing step) (the sixth step).
Figure).

The toner (6) remaining on the ferroelectric layer (1) without being transferred is cleaned by, for example, means such as brush cleaning (11), blade cleaning, wave cleaning, or blow cleaning (cleaning step). 9). Ferroelectric layer using PLZT (1)
Since the PLZT itself is hard, even if the blade cleaning method is used, it will not be damaged.

When performing further copying, in the ferroelectric layer (1),
Since the polarized latent image (12) remains, the process returns to the latent image forming step shown in FIG. 4, and through the transfer and fixing steps, it becomes possible to carry out retention copying to obtain a second copy image. Thereafter, by repeating this cycle, a large number of copies can be made.
As described above, in the present invention, when copying the same image, only the latent image forming process is performed once, and thereafter, only the toner development and the transfer process to paper need to be repeated. Thus, the process can be sufficiently simplified.

To erase the polarization latent image, a bias voltage equal to or higher than the bias voltage applied in the initial polarization step may be applied to the ferroelectric layer (1) in the same manner as in the initial polarization step.
PLZT has a fast polarization response speed on the order of microseconds,
The polarization latent image can be quickly erased and the process can return to the information writing process.

Latent images based on these recording materials / methods can be used not only as printers, but also as recordable / erasable memories. .

Effects of the Invention The latent image forming method of the present invention is suitable for retention development, and can easily and quickly write and erase a latent image.

[Brief description of the drawings]

FIG. 1 to FIG. 8 are diagrams showing each step of a copying method utilizing the present invention. FIG. 9 is a diagram illustrating an example of polarization characteristics of a ferroelectric. DESCRIPTION OF SYMBOLS 1 ... Ferroelectric layer, 2 ... Photoconductive layer 3 ... Transparent electrode 4 ... Writing stylus head 5 ... Exposure lamp, 6 ... Toner 7 ... Magnetic sleeve, 8 ... Transfer paper 9 ... Conductive roller, 10 Heat roller 11 Cleaning brush 12, Polarized latent image

Claims (1)

(57) [Claims] 1. A photoconductive layer and a ferroelectric layer capable of forming remanent polarization are laminated, and the thickness of the photoconductive layer is 5 to 50 μm.
m, the photoconductive layer is made conductive by uniform exposure and uniform voltage applying means in advance to form a uniform saturated internal polarization inside the ferroelectric layer, and then contact the same. Optical information is given to the photoconductive layer to make the optical information portion conductive, and when a saturated internal polarization is formed inside the ferroelectric layer, a voltage of the opposite polarity is applied to apply light to the ferroelectric layer. A method of forming a latent image, comprising inverting the polarization of an information portion.