JP2002196291A - Optical switching element and its manufacturing method, optical writing type recording medium, device, display and writing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switching element and its manufacturing method, a device, an optical writing type recording medium, a display and a writing device wherein sensitivity is not deteriorated even when an upper electric charge generating layer is formed by applying a dispersion liquid. SOLUTION: In the optical switching element and its manufacturing method, the device in which the element is combined to a function element, the optical writing type recording medium, the display and the writing device, the upper electric charge generating layer is manufactured from an upper electric charge generating layer forming dispersion liquid containing a solvent which does not damage at least an electric charge generating material, a binder and an electric charge carrying layer in a photoconductive switching element for switching the function element in which at least an electrode layer, a lower electric charge generating layer, the electric charge carrying layer and the upper electric charge generating layer are successively laminated on a substrate and which is driven by an AC electric field or AC current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching element, and a device such as an optical writing type recording medium using the same.
The present invention relates to a display device and a writing device.

[0002]

2. Description of the Related Art In recent years, an optical writing type spatial modulation device combining a photoconductive switching element and a display element has been developed, and has been put to practical use as a light valve in projectors and the like. LCD, Vo
As described in l.2, No. 1, '98, pp. 3-18, possibilities are being studied in the field of optical information processing. The optical writing type spatial modulation device drives the display element by controlling the voltage applied to the display element by changing the impedance of the photoconductive switching element according to the amount of light received while applying a predetermined voltage to the element. Then, an image is displayed. In particular, an optical writable medium that can be separated by using an element having a memory property as a display control element of the optical writable spatial modulation device has attracted attention as an electronic paper medium.

As a display control element of an optically rewritable medium, for example, a liquid crystal display element such as a nematic liquid crystal, a cholesteric liquid crystal, or a ferroelectric liquid crystal dispersed in a polymer to impart a memory property, or an electrophoretic element or an electric field rotating element is used. An element, a toner electric field transfer element, an element encapsulating them, and the like have been studied. Examples of the optical switching element capable of controlling the voltage or current by the received light amount include, for example, an amorphous silicon element, an OPC element having a function-separated two-layer structure using an organic photoconductor, and furthermore, the present inventors Et al., JP-A-2000-180
888, a structure in which a charge generation layer (CGL) is formed above and below a charge transport layer (CTL)
An OPC element having a CGL structure (referred to as a dual CGL structure) is known (FIG. 1). In particular, since the OPC element does not require a high-temperature heat treatment, it can be applied to a flexible substrate such as a PET film, and has an advantage that it can be manufactured at low cost because there is no vacuum process. Above all,
The Dual CGL structure is particularly effective because AC driving is possible, and even when a liquid crystal element is used as the display element, the image sticking phenomenon due to the movement of ions hardly occurs due to the bias component included in the applied voltage. Structure. FIG. 1 shows a conceptual diagram of an optical writing type electronic paper in which this optical switching element is applied to an electronic paper.

[0004] As a method for producing the charge generation layer used in the optical switching element, a method using a vacuum process such as vapor deposition or sputtering and a method using at least a dispersion liquid in which a binder resin, a solvent thereof and a charge generation material are dispersed are applied. However, in a method using a vacuum process, it is difficult to produce a low-priced medium because the apparatus is expensive, while a coating type can be mass-produced at low cost and has an advantage in cost. As a method for forming the charge transport layer, a coating type has been drawing attention.

However, there are the following problems in fabricating this structure by a coating method. Upper CGL
The problem is that the solvent of the CG dispersion liquid damages the charge transport layer during the preparation. Usually, a polycarbonate-based material is used as the binder for the charge transport layer, while a chloro-based solvent such as monochlorobenzene is used as the solvent for the dispersion of the charge-generating material. For this reason, when the charge generation layer is laminated on the charge transport layer, there arises a problem that the polycarbonate swells, the surface is roughened, and in the worst case, the charge generation layer is missing. In addition, the optical switching element with this structure has the phenomenon of re-entry of carriers from the charge transport layer to the charge generation layer during operation, which is a phenomenon that does not occur with the two-layer function separation structure OPC that is a normal charge transport layer / charge generation layer. However, at this time, the efficiency is reduced at the damaged charge transport layer / charge generation layer interface, and the sensitivity may be deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent the sensitivity from deteriorating even when the upper charge generation layer is formed by applying a dispersion. An object of the present invention is to provide an optical switching element, a method of manufacturing the same, a device, an optical writing type recording medium, a display device, and a writing device.

[0006]

The above object can be attained by providing the following optical switching element and its manufacturing method, device, optical writing type recording medium, display device and writing device. (1) At least an electrode layer, a lower charge generation layer,
The charge transport layer, and the upper charge generation layer sequentially laminated, in the photoconductive switching element for performing the switching of the functional element driven by an AC electric field or AC current, the upper charge generation layer, at least a charge generation material, a binder and An optical switching element manufactured from a dispersion for forming an upper charge generation layer containing a solvent that does not damage the charge transport layer. The optical switching element of the present invention has high quality and low cost because the upper charge generation layer is made of a dispersion for forming the upper charge generation layer containing a charge generation material, a binder and a solvent that does not damage the charge transport layer. In addition, since the charge transport layer is not damaged when the upper charge generation layer is formed, the sensitivity of the optical switching element does not deteriorate.

(2) By sequentially stacking at least an electrode layer, a lower charge generation layer, a charge transport layer, and an upper charge generation layer on a substrate, switching of a functional element driven by an AC electric field or an AC current is performed. In the method for manufacturing a photoconductive switching element for use in the present invention, the upper charge generation layer comprises a charge generation material, a binder and a dispersion for forming an upper charge generation layer containing a solvent that does not damage the charge transport layer. The method of manufacturing the optical switching element, further comprising a step of forming the optical switching element by applying to the substrate. According to the method for manufacturing an optical switching element of the present invention, since the upper charge generation layer can be formed by applying a dispersion, a high-quality optical switching element can be manufactured at low cost. (3) A device in which the optical switching element according to (1) and a functional element are electrically connected. By combining the optical switching element with various functional elements, a device equivalent to a conventional one can be obtained at low cost.

(4) An optical writing type recording medium in which at least an electrode, a display layer, an optical switching element, and an electrode are laminated between a pair of substrates, the optical switching element according to (1). An optical switching element, wherein an upper charge generation layer of the element is located on a display layer side, and at least a substrate and an electrode on a side on which writing light is incident are light-transmissive. Medium. Since the optical writing type recording medium of the present invention uses the optical switching element as described above, the recording sensitivity does not deteriorate. (5) A display device comprising at least the optical recording medium for recording according to (4), a recording medium driving device for driving the recording medium, a writing device for performing optical writing on the recording medium, and a control unit. (6) A recording medium drive device to which the optical writing type recording medium according to (4) can be connected, a writing device which performs optical writing on the recording medium, and a control device.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An optical switching element of the present invention
Basically, it comprises a light transmitting substrate, a light transmitting electrode layer, a lower charge generation layer, a charge transport layer and an upper charge generation layer. (In the following, "light transmission"
This property is sometimes described as "transparent." The optical switching element of the present invention will be described with reference to FIG. FIG. 1 shows an optical switching element 30 (dual
Fig. 1 shows the structure of an optical switching device (CGL structure).
Reference numeral 10 denotes a substrate, 12 denotes a conductive film (electrode), 14 denotes a lower charge generation layer, 16 denotes a charge transport layer, and 18 denotes an upper charge generation layer. In the device or the optical writing medium described below, the upper charge generation layer is located on the functional layer, for example, the display layer side.

The charge generating materials for the lower and upper charge generating layers include perylene-based, phthalocyanine-based, bisazo-based, dithiopitokelopyrrole-based, squalilium-based, and the like.
Organic materials that generate electric charge by light irradiation, such as azulhenium-based and thiapyrylium-polycarbonate-based materials, can be used. In particular, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, titanyl phthalocyanine can be used as a highly sensitive charge generating material. Among them, (1) the crystal structure has a Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum. , At least i) 7.4 °, 16.
6 °, 25.5 ° and 28.3 °, ii) 6.8 °, 17.3 °, 23.6 ° and 26.9 °, or iii) 8.7 ° to 9.2 °, 17.6 °, 24.0 °,
Chlorogallium phthalocyanine having strong diffraction peaks at 27.4 ° and 28.8 °, (2) a crystal structure having a Bragg angle (2θ ± 0.2 °) in an X-ray diffraction spectrum of at least i) 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1
° and 28.3 °, ii) 7.7 °, 16.5 °, 25.1 ° and 26.6
°, iii) 7.9 °, 16.5 °, 24.4 ° and 27.6 °, iv) 7.0
°, 7.5 °, 10.5 °, 11.7 °, 12.7 °, 17.3 °, 18.1
°, 24.5 °, 26.2 ° and 27.1 °, v) 6.8 °, 12.8 °,
15.8 ° and 26.0 °, or vi) 7.4 °, 9.9 °, 25.0
Hydroxygallium phthalocyanine having strong diffraction peaks at 0 °, 26.2 ° and 28.2 °, and (3) a crystal structure whose Bragg angle (2θ ± 0.
2 °) has i) strong diffraction peaks at least at 9.3 ° and 26.3 °, or ii) 9.5 °, 9.7 °, 11.7
Titanyl phthalocyanine having strong diffraction peaks at °, 15 °, 23.5 °, 24.1 °, and 27.3 ° is preferable because of its high sensitivity, and at least one or more charge generation materials selected from these groups can be used.

As the binder resin for the lower and upper charge generation layers, polyvinyl butyral resin, polyarylate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate resin, carboxyl-modified vinyl chloride-vinyl acetate copolymer, polyamide resin ( Nylon resin), acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, and the like are applicable. In particular,
Polyvinyl butyral resins and polyamide resins, especially nylon resins such as methoxymethylated 6 nylon, are soluble in many alcohols and keto alcohols and are effective. Further, a carboxyl-modified vinyl chloride-vinyl acetate copolymer is a preferable binder resin because it is soluble in keto alcohol and disperses hydroxygallium phthalocyanine or the like as a charge generating material well.

As a method of forming the lower charge generation layer, a dry film forming method such as a vacuum evaporation method or a sputtering method, a spin coating method using a solution or a dispersion, a dipping method, and the like can be applied. Either method does not require substrate heating or strict process control as in a-Si or photodiode fabrication. The upper charge generation layer is produced by applying a coating solution for the upper charge generation layer by various printing methods such as spin coating, dipping, spray coating, curtain coating, and gravure. The film thickness of the upper and lower charge generation layers is 10 nm to 1 μm, preferably 20 nm to 50 μm.
0 nm is appropriate. When the thickness is less than 10 nm, the photosensitivity is insufficient and it is difficult to form a uniform film. On the other hand, when the thickness is more than 1 μm, the photosensitivity is saturated and peeling is likely to occur due to stress in the film.

As the charge transport material, trinitrofluorene, polyvinylcarbazole, oxadiazole, pyrarizone, hydrazone, stilbene, triphenylamine, triphenylmethane, and the like can be used. Further, polyvinyl alcohol to which LiClO ₄ is added
It is also possible to apply an ion conductive material such as polyethylene or polyethylene oxide.

The binder resin for the charge transport layer includes polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, chloride Vinylidene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinyl carbazole, polysilane and the like are applicable. In particular, when a polycarbonate resin is used as a binder, it is very effective for improving the characteristics of the charge transport material.

As a method for forming the charge transport layer, a dry film forming method such as a vacuum evaporation method and a sputtering method, a spin coating method using a solution or a dispersion, a dipping method, and the like can be applied. The thickness of the charge transport layer is 0.1 μm to 100 μm.
μm, preferably 1 μm to 10 μm, is suitable. 0.1 μ
If the thickness is less than m, the withstand voltage is low and it is difficult to ensure the reliability. If the thickness is more than 100 μm, the impedance matching with the functional element becomes difficult and the design becomes difficult.

According to the present invention, in the optical switching element having the above-described structure, the upper charge generation layer is
It is prepared from a dispersion for forming an upper charge generation layer containing at least a charge generation material, a binder and a solvent that does not damage the charge transport layer. Here, damage to the charge transport layer refers to swelling of the charge transport layer in the charge transport layer, dissolution of the charge transport material or the binder resin, or solvent This means that the above-mentioned deterioration of the surface properties and deterioration of the electric characteristics occur due to crystallization of the charge transporting material in contact with the substrate. By manufacturing the upper charge generation layer in this manner, an optical switching element having a dual CGL structure with low cost and high sensitivity can be obtained.

The solvent used in the present invention includes:
Although it depends on the material constituting the charge transporting layer, in general, solvents such as alcohols, ketones, ethers, and esters are effective. Among them, a solvent having a hydroxyl group in a molecule such as an alcohol is most suitable as a solvent of a dispersion for a charge generation layer prepared on a charge transport layer using a polycarbonate resin as a binder. Further, the solvent used in the present invention is preferably a protic solvent, and its solubility parameter (SP value) is preferably 9.0 or more. Generally, as the charge transporting material, a substance that is insoluble or hardly soluble in a protonic solvent such as alcohol is often used. On the other hand, as the binder resin of the charge transport layer, a resin compatible with the charge transport material is selected. At this time, regarding the solubility, a resin having the same properties as the charge transport material, that is, insoluble or insoluble in the proton solvent. This is because a resin that is hardly soluble is selected. Further, since the solubility parameter of the binder resin generally used for the charge transport layer is about 8.0 to 9.0, it is useful to use a solvent of 9.0 or more in order to increase the poor solubility.

Applicable alcohols are compounds having one or more hydroxyl groups in the molecule, for example, methanol,
Ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-
Butyl alcohol, 1-pentanol, 2-pentanol,
3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-2 -
Pentanol, 2-methyl-1-butanol, 1-peptanol, 2-peptanol, 3-peptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-nonanol, 3,5,5-trimethyl -1-hexanol, 1-decanol, 1-undecanol, 1
-Dodecanol, allyl alcohol, propargyl alcohol, benzylgyl alcohol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, α-terpineol, abietinol, fusel oil, , 2-ethanediol, 1,
2-propanediol, 1,3-propanediol,
1,3-butanediol, 1,2-butanediol,
1,4-butanediol, 2,3-butanediol,
1,5 pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, glycerin, 2-ethyl-2- (hydroxymethyl) -1 , 3-propanediol, 1,2,6-hexanetriol and the like.

Compounds having a hydroxyl group and a keto group in the molecule are also effective. For example, keto alcohols such as 3-methyl-3-hydroxy-2-butanone and 4-methyl-4-hydroxy-2-pentanone are applicable. It is possible.

Of course, some of these solvents may be mixed, and if these are the main components, it is also possible to mix other solvents within a range that does not damage the charge transport layer. For example, it is also possible to mix a small amount of a solvent that dissolves polycarbonate and to slightly dissolve polycarbonate without affecting the surface properties. For example, regarding surface properties, changes in surface roughness
If it is 0.4 μm or less in terms of Ra, the surface property has almost no influence on the medium characteristics and the surface property does not deteriorate. Also, as long as the charge transport material does not melt or crystallize,
For example, the dispersibility can be increased by adding cyclohexanone or the like. In this case, the ratio (volume ratio) of cyclohexanone to the solvent is preferably about 1: 100 to 1: 2.

In preparing the dispersion for the upper charge generation layer, the ratio of the binder to the charge generation material is preferably about 1:20 to 20: 1 by mass, more preferably 1: 3 to 3: 1. : 1
It is. If the ratio is less than 1:20, the binding force will decrease, and
Then, the electrical characteristics deteriorate. In addition, the concentration of the solid content of the dispersion for the upper charge generation layer is preferably about 1 to 30% by mass, but when it is 1% or less, the film thickness is too thin to obtain electrical characteristics, and 30
% Or more, the viscosity is too high and film formation becomes difficult, so the above range is appropriate.

In particular, in order to disperse the high-sensitivity charge generating material containing phthalocyanine having the specific crystal structure, a polyvinyl butyral resin is used as a binder resin, and 1-butanone and 3-methyl-3 are used as a solvent. The use of -hydroxy-2-butanone and 4-methyl-4-hydroxy-2-pentanone is very effective because the charge generating material can be dispersed well.

As the substrate of the optical switching element of the present invention, a substrate made of glass, PET (polyethylene terephthalate), PC (polycarbonate), polyethylene, polystyrene, polyimide, PES (polyether sulfone) or the like is used. In addition, when an organic material is used for the photoconductive layer (charge generation layer, charge transport layer), there is no step of heat treatment at a high temperature, so that a flexible substrate can be obtained, molding is easy, and cost is low. It is advantageous to use a light-transmitting plastic substrate. Generally, the thickness of the substrate is preferably about 100 μm to 500 μm. Further, as the electrode layer in the present invention, an ITO film, Au, SnO ₂ , Al, Cu or the like is used. Further, the substrate and the electrode do not necessarily need to be light-transmitting. That is, as shown in Japanese Patent Application No. 11-273663, the display element of the optical writing type recording medium is
In the case of a selectively reflective or backscattering display element having a memory property and selectively reflecting a wavelength required for display, writing can be performed from the display side. It is sufficient that at least the substrate and the electrode layer on the display element side are light-transmitting. Therefore, when optical writing is performed from the display element side, the substrate or the electrode layer of the optical switching element does not need to be light-transmissive.
One layer can be used.

Further, in the optical switching element of the present invention, when the photoconductive characteristics of the charge generation layers formed above and below the charge transport layer of the optical switching element are not the same,
As described in JP-A-2000-180888, [0022] to [0025], it is effective to provide a functional film having a capacitive component capable of removing a DC component, that is, a functional film for removing a DC component in an optical switching element. It is effective for removing DC bias.

In addition to the DC component removing functional film, another functional layer can be provided. For example, a layer for preventing carrier intrusion can be formed between the electrode and the charge generation layer. In addition, a reflective film or a light-shielding film can be formed, or a functional layer having a plurality of these functions may be used. Such a functional layer can be applied in a range that does not significantly impede the flow of current. Further, as the structure of the optical switching element of the present invention, a charge generation layer is produced between the charge transport layers,
A configuration such as a charge generation layer / a charge transport layer / a charge generation layer / a charge transport layer / a charge generation layer may be employed.

The optical switching element of the present invention has excellent voltage symmetry when an AC electric field is applied to the optical switching element, and furthermore, the upper charge generation layer includes a charge generation material, a binder, and a charge transport layer. Since it is manufactured from the dispersion for forming the upper charge generation layer containing a solvent that does not cause damage, it is an optical switching element that can be manufactured at high quality and at low cost, and the charge transport layer is used for forming the upper charge generation layer. Since there is no damage at the time, the sensitivity of the optical switching element does not deteriorate.

This optical switching element can be used by being electrically connected to a functional element as described below. The optical switching element and the functional element may be connected in series or in parallel, or a combination thereof. Furthermore, it may be connected to another element. Examples of the functional element include a liquid crystal display element for displaying an image, a display element such as an electrochromic element, an electrophoretic element, and an electric field rotating element, a spatial modulation element and an optical operation element other than an image display, a memory element used for a storage device, and a thermal element. And an image recording element for a head. The optical switching element of the present invention is effective for switching an image display element, particularly a liquid crystal display element. When a liquid crystal display element is used, it can be used as a light-writing type liquid crystal spatial modulation element. In particular, liquid crystal display devices
Since the AC driving is fundamental and the DC component is disliked as described above, the application of the optical switching element of the present invention is effective. Liquid crystals that can be used include nematic, smectic, discotic and cholesteric.

The functional element of the present invention includes a functional element having a memory property. Examples of the functional element having a memory property include a liquid crystal display element having a memory property among the above liquid crystal display elements. A liquid crystal with memory properties means that the orientation of the liquid crystal is controlled by applying a voltage,
The liquid crystal has a characteristic that the alignment of the liquid crystal is maintained for a certain period of time even after the application of the voltage is released. For example, ferroelectric liquid crystal such as polymer dispersed liquid crystal (PDLC) and chiral smectic C phase, or cholesteric liquid crystal. Further, a liquid crystal element in which these are encapsulated is also applicable. A liquid crystal having a memory property does not require power for holding an image display because of the memory property, and an integrated device described later can be manufactured and used separately from the main body. Further, the device can be manufactured at low cost. Examples of the display element having a memory property include an electrochromic element, an electrophoretic element, and an electric field rotating element in addition to the above-described liquid crystal display element.

Further, in the present invention, when connecting the optical switching element and the functional element as described above, it is preferable to integrate these into a device. By integrating them, the connection between the optical switching element and the functional element can be stabilized. In particular, it is effective to integrate a functional element having a memory function and an optical switching element. A device in which these are integrated can be separated from a main body that drives the device. Therefore, for example, the device separated from the main body can be distributed. In addition, the user can browse in a free place and in a free posture. Of course, the present invention can also be applied to separating only the image display of the liquid crystal unit. However, in some cases, it is difficult to secure the reliability when the functional element and the optical switching element are connected again. Therefore, the one in which the functional element and the organic photoconductive switching are integrated is more effective. A device (image display medium) in which a liquid crystal element having a memory function and photoconductive switching are integrated as the functional element having a memory function is particularly effective as the device of the present invention. Further, among the liquid crystal elements having a memory property, cholesteric liquid crystal has a high reflectance and excellent display performance. Therefore, a device in which a cholesteric liquid crystal display element and an optical switching element are integrated is particularly desirable as an image display medium. Further, in the present invention, it is advantageous to form a device in which the optical switching element, the DC component removing functional film, and the functional element are sequentially laminated and integrated. In a device in which an optical switching element and a functional element are connected in series, a functional film may be provided between the upper charge generation layer of the optical switching element and the functional element. For example, an isolation layer for separating the optical switching element from the functional element, a DC component removing functional film, and the like can be given.

FIG. 2 is a conceptual diagram of an optical writing type spatial modulation device (optical writing type recording medium) having a functional film as described above as an example of a device in which the optical switching element and the functional element of the present invention are integrated. Is shown. The optical writing type recording medium 20 includes an optical switching element 30, a display element 40, and a functional film 50 sandwiched between the optical switching element and the display element.
Is composed of a substrate 31, an electrode 32, a lower charge generation layer 33, a charge transport layer 34, and an upper charge generation layer 35, and the display element 40 is composed of a substrate 41, an electrode 42, and a display layer (liquid crystal layer or the like) 43. . As is clear from the figure, the upper charge generation layer 35 is located on the display element side. In the optical writing type recording medium 20, it is necessary to make the substrate and electrode of the element on the light incident side light-transmitting depending on whether the optical writing is performed from the optical switching element side or the display element side. An alternating electric field is applied between the electrodes 32 and 42.

In the present invention, a device having various functions is manufactured by electrically connecting a drive mechanism for driving the device to the device in which the optical switching element and the functional element are integrated as described above. be able to. Also, at this time, by configuring the drive mechanism so as to be detachable from the device, the device can be separated from the apparatus main body for browsing or distribution. Examples of the functional element include a functional element having a memory property, a display element, a display element having a memory property, a liquid crystal display element, a liquid crystal display element having a memory property, and a cholesteric liquid crystal display element. For example, a liquid crystal display element having a memory property, particularly, a cholesteric liquid crystal display element is preferably used. Further, when the device of the above apparatus is a device provided with the above-described DC component removing functional film, the voltage symmetry when driven by an AC electric field is further improved.

Next, the display device of the present invention will be described. FIG. 3 shows a schematic view of an example of the display device. The display device shown in FIG. 3 includes a recording medium driving device, a writing device, and a control device that controls these devices. These devices may be combined into one unit or may be separated. The recording medium driving device includes a waveform generator 62, an input signal detector 64, a controller 66, and a connector 65.
Consists of The connector 65 is a connector for connecting the transparent electrode of the optical switching element side substrate and the electrode of the display element side substrate, and has a contact on each side, and the recording medium driving device and the optical writing type recording medium 20 are connected. It is possible to separate them freely. The writing device includes a control unit 82, a light pattern generation unit (for example, a transmission type TFT liquid crystal display) 84, and a light irradiation unit (for example, a halogen light source) 8.
The control means 82 is connected to the PC. The control device is for controlling the recording medium driving device and the writing device. The control device 70, the driving wave generation signal output device 72, and the optical writing data output device 74
Consists of The optical writing type recording medium 20 includes:
In this case, a DC component removing functional film 52 is provided between the optical switching element 30 and the display element 40.

A voltage applying means (not shown) for applying a driving pulse for display in synchronization with the optical writing by the optical writing means includes means for generating an applied pulse and means for detecting a trigger input for output. Have. The pulse generation means includes, for example, a waveform storage means such as a ROM, a DA conversion means, and a control means, and a means for applying a voltage to a spatial modulation device by DA-converting a waveform read from the ROM when a voltage is applied is applicable. In addition, a means for generating a pulse by an electric circuit method such as a pulse generation circuit instead of a ROM can be applied, but other means for applying a drive pulse can be used without any particular limitation. be able to. The writing device includes a unit for generating a pattern of light to be irradiated on the light incident side of the spatial modulation device, and a light irradiating unit for irradiating the spatial modulation device with the pattern. For generating the pattern, for example, a transmission type display such as a liquid crystal display using a TFT or a simple matrix type liquid crystal display can be applied. As the light irradiating means, any device that can irradiate a spatial modulation device, such as a fluorescent light, a halogen lamp, and an electroluminescence (EL) light, is applicable. Needless to say, a light emitting display such as an EL display, a CRT, and a field emission display (FED) having both a pattern generating unit and a light irradiating unit can be applied. In addition to the above, the light amount, wavelength,
Any other means that can control the irradiation pattern may be used.

The driving method for driving the functional element according to the present invention is not particularly limited, but includes an AC voltage, a frequency,
Irradiation light quantity and wavelength control are applicable. The applied voltage applied in the recording apparatus or recording method of the present invention is an AC voltage, but a sine wave, a rectangular wave, a triangular wave, or the like can be used as a waveform. Needless to say, the present invention can be applied to a combination of these or a completely arbitrary waveform. In order to improve the display performance and the like, a sub-pulse that cannot be switched by itself may be added to the drive pulse. Depending on the display element, application of a slight bias component may be effective, but it goes without saying that this may be adopted in the device of the present invention.

[0035]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to these Examples. In the following,% means “mass%”,
Parts means "parts by mass". Example 1 Here, assuming that the optical switching element was more simplified, a charge transport layer was prepared and immersed in each solvent on a transparent PET substrate on which ITO was laminated, and the surface of the charge transport layer was evaluated. . The solvents used are 2-propanol, 1-butanol, 3-methyl-3-hydroxy-2-butanone, 4-methyl-4-hydroxy-2-pentanone. For the preparation of the charge transport layer, a charge transport material N, N-bis (3,4-dimethylphenyl) b
iphenyl-4-amine and binder resin PolyCarbonate bis
After mixing phenol-Z and (poly (4,4'-cyclohexylidenediphenylene carbonate)) at a mass ratio of 4: 6, these were dissolved in monochlorobenzene to form a 10% solution. The solution was pulled up at a speed of 120 mm / min by dip coating, and 3
A charge transport layer having a thickness of μm was formed.

Example 2 (Optical Switching Element-OPC Cell) In this example, an OPC cell was manufactured to evaluate the optical sensitivity of the optical switching element. As a dispersion for the lower charge generation layer, the Bragg angle of X-ray diffraction is 7.5 °, 9.9 °,
12.5 °, 16.3 °, 18.6 °, hydroxygallium phthalocyanine having peaks at 25.1 ° and 28.3 ° as a charge generating material, using polyvinyl butyral as a binder resin, the mass ratio of both to 1: 1, this is diacetone After mixing (concentration: 4%) with alcohol (proton solvent, SP value: 9.41), the mixture was dispersed by a paint shaker for 1 hour to prepare a dispersion. This dispersion was applied onto the ITO surface of a 125 μm-thick PET film with ITO (Toray High Beam) having a thickness of 125 μm by a spin coating method and then dried to form a lower charge generation layer having a thickness of 0.2 μm.

As the solution for the charge transport layer, charge transport materials N, N-
bis (3,4dimethylphenyl) biphenyl-4-amine, binder resin PolyCarbonate bisphenol-Z, (poly (4,4'-cyclohexylidene diphenylene carbonate))
After mixing at a mass ratio of 4: 6, this was dissolved in monochlorobenzene to prepare a 10% solution. This solution was pulled up by dip coating at a speed of 120 mm / min to form a 3 μm thick charge transport layer on the lower charge generation layer.

On the charge transport layer, an upper charge generation layer was formed to a thickness of 0.2 μm in the same manner as the lower charge generation layer. In this way, an optical switching element including the substrate, the lower charge generation layer, the charge transport layer, and the upper charge generation layer was manufactured. On the upper charge generation layer of the optical switching element,
An Au electrode having a thickness of 50 mm was produced and used as an OPC cell. O made
The PC cell was connected to an impedance measuring device, and an AC sine wave of 50 Hz was applied thereto under light irradiation and darkness, and the contrast at light and dark was measured by the voltage to measure the optical switching characteristics.

Example 3 In the optical switching element of Example 2, diacetone alcohol, which is a solvent used for forming the upper charge generation layer, was replaced with 1
-An optical switching element was produced in the same manner except that butanol (proton type, SP value: 11.6) was used.

Example 4 (Optical writing type recording medium) In this example, the optical switching element manufactured in Example 2 and a display element having a memory function were integrated, and optical writing recording for confirming that an image could be displayed was performed. A medium was prepared. A layer of polyvinyl alcohol having a thickness of 0.2 μm was formed as a separation layer on the upper charge generation layer of the optical switching element manufactured in Example 2 by spin coating.

(Production of Display Element) As a display layer of the display element, a capsule liquid crystal element produced by the following method was used. Nematic liquid crystal E8 with positive dielectric anisotropy
(Merck) 74.8 parts, chiral agent CB15 (BDH) 21
And 4.2 parts of the chiral agent R1011 (manufactured by Merck) were heated and dissolved, and then returned to room temperature to obtain a chiral nematic liquid crystal that selectively reflects blue-green light. An adduct of 3 mol of xylene diisocyanate and 1 mol of trimethylolpropane was added to 10 parts of this blue green chiral nematic liquid crystal.
(D-110N manufactured by Takeda Pharmaceutical Co., Ltd.) (3 parts) and 100 parts of ethyl acetate were added to make a homogeneous solution, and a liquid to be an oil phase was prepared. On the other hand, 10 parts of polyvinyl alcohol (Kuraray Poval 217EE),
After adding to 1000 parts of heated ion-exchanged water, stirring, and leaving to cool, a liquid to be an aqueous phase was prepared.

Next, the oil phase was emulsified and dispersed in the aqueous phase for 1 minute by a household mixer to which a 30 V AC was applied with a slide lacquer to prepare an oil-in-water emulsion in which oil phase droplets were dispersed in the aqueous phase. did. The oil-in-water emulsion was stirred for 2 hours while being heated in a water bath at 60 ° C. to complete interfacial polymerization and form liquid crystal microcapsules. The average particle size of the obtained liquid crystal microcapsules was estimated to be about 12 μm by a laser particle size distribution meter. The microcapsule dispersion was filtered through a 38 μm mesh stainless steel mesh, allowed to stand for 24 hours, and the milky white supernatant was removed to obtain a slurry of microcapsules having a solid content of about 40 wt%. A coating solution for a display layer was prepared by adding a polyvinyl alcohol solution (10%) containing polyvinyl alcohol to the slurry in an amount of 2/3 mass of a solid component composed of microcapsules. 125μm thickness I
By applying the above coating solution with a # 44 wire bar on the ITO surface of PET film with TO (Toray High Beam),
A liquid crystal layer was formed, and a display element was manufactured.

(Preparation of Optically Writable Recording Medium) As described above, the surface of the polyvinyl alcohol isolating layer formed on the upper charge generating layer of the optical switching element is covered with Dick Dry WS-321A, a completely aqueous dry laminating adhesive. / LD-
55 (Dai Nippon Ink Chemical Industry Co., Ltd.)
An adhesive layer having a thickness of μm was formed. The adhesive layer provided on the optical switching element and the liquid crystal layer of the display element are brought into close contact with each other, and after laminating at 70 ° C., black polyimide BKR-105 (manufactured by Nippon Kayaku) is applied to the surface of the PET film of the display element, This was adhered to obtain an optically writable recording medium for monochrome display.

The optical writing type recording medium is connected to a voltage application device, and a monochrome liquid crystal panel is brought into close contact with the substrate of the optical switching element so that light is incident on the optical switching element like an image. And a rectangular pulse of 50 Hz and 300 V was input in four pulses to form an image on the optically writable recording medium.

Comparative Example 1 A charge transporting layer prepared on a transparent PET substrate laminated with ITO, prepared in Example 1, was immersed in the following solvents to evaluate the surface of the charge transporting layer. The solvents used were acetone, butyl acetate, 2-butanone, dimethylformamide, and dimethylacetamide, and the surfaces were immersed in each solvent and the surface thereof was observed to examine the resistance to the solvent.

Comparative Example 2 In the optical switching element of Example 2, when the upper charge generation layer was formed, the procedure was the same except that diacetone alcohol as a solvent was changed to acetone (non-proton type, SP value: 9.73). The optical switching element was manufactured by
The C cell swelled and partially dissolved, and it was impossible to measure impedance and the like. Comparative Example 3 As in Comparative Example 2, when isopropoxypropanol (proton system, SP value: 8.94) was used as a solvent,
Similarly, the OPC cell swells and partially dissolves, making it impossible to measure impedance and the like. Comparative Example 4 IT of 125 μm thick PET film with ITO (Toray High Beam)
On the O-plane, benzimidazole perylene BZP was formed to a thickness of 0.08 μm by a vapor deposition method as a lower charge generation layer, and a charge transport layer was formed thereon to a thickness of 3 μm in the same manner as in Example 2, and further formed thereon. An optical switching element was fabricated by forming benzimidazole perylene BZP as a charge generation layer to a thickness of 0.08 μm by a vapor deposition method. On the upper charge generating layer of the optical switching element, a Au electrode having a thickness of 50 mm was prepared, and the OPC was performed.
Cell. The fabricated OPC cell was connected to an impedance measuring device, and an AC sine wave of 50 Hz was applied thereto under light irradiation and darkness, and the contrast at light and dark was measured by the voltage to measure the optical switching characteristics.

[Evaluation of Optical Switching Element and Optical Writing Recording Medium] (1) The resistance of the charge transport layer to the solvent of Example 1 and Comparative Example 1 was visually inspected. The solvent No. 1 did not change the charge transport layer and did not damage it, but the solvent of the comparative example caused surface turbidity and, in the worst case, dissolution of the charge transport layer.

[0048]

[Table 1]

(2) Evaluation of Voltage Dependence of Resistance Component of Optical Switching Element The voltage dependence of the resistance component, which is an impedance characteristic, was measured for the optical switching element of Example 3 and the optical switching element of Comparative Example 4. Hewlett-Packard HP4194A was used for the measurement. In order to achieve high sensitivity, a lower resistance component of the impedance is required. In the dark, both Example 3 and Comparative Example 4 exhibited high resistance of 1 GΩ / cm ² or more. FIG. 4 shows the light-weight impedance characteristics measured in the same manner. The light amount was 170 μW / cm ² and 1 mW / cm ² from a halogen light source. As shown in FIG. 4, the resistance component of the example is smaller than that of the comparative example at any light amount. Therefore, it can be seen that the sensitivity when a predetermined amount of light is applied is higher.

(3) Evaluation of Light Dependence of Resistance Component of Optical Switching Element The light switching of the resistance component, which is an impedance characteristic, was measured for the optical switching elements of Example 3 and Comparative Example 4. Hewlett-Packard HP4194A was used for the measurement. FIG. 5 shows the measured impedance characteristics at the time of light. As a voltage waveform, a sine wave of 100 Hz and 100 V was applied. As shown in FIG. 5, the resistance component of Example 3 is smaller than that of Comparative Example 4 at any light amount. Therefore, the light sensitivity when a predetermined voltage is applied is as follows:
It can be seen that the sensitivity is higher.

(4) Recording Evaluation of Optically Writable Recording Medium The optically writable recording medium produced in Example 4 was connected to a writing apparatus as shown in FIG. 3, and a voltage was applied to both electrodes of the optically writable recording medium. And tried to display a monochrome color image. A rectangular wave, 50 Hz, 4 pulses, and 300 Vpp were applied as write pulses. As a result, in the dark area (1 μw / cm ² ) and the light irradiation area (500 μw / cm ² ), a monochrome image was obtained in which the light irradiation area was blue and the dark area was black. This was repeated 1,000 times and was stable.

[0052]

According to the present invention, the solvent of the coating solution for producing the upper charge generation layer of the optical switching element is:
Since the charge transport layer is not damaged when the upper charge generation layer is manufactured, the upper charge generation layer is formed by vacuum deposition without using an expensive apparatus such as a vacuum deposition apparatus. An optical switching element having a performance comparable to that of the case of forming can be manufactured. Also, by combining such an optical switching element with various functional elements, a device equivalent to a conventional one, for example, an optical writing type recording medium can be obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a cross-sectional structure of an optical switching element having a dual CGL structure.

FIG. 2 is a schematic view showing an example of an optical writing type recording medium of the present invention.

FIG. 3 is a schematic diagram illustrating an example of a writing device and a display device of the present invention.

FIG. 4 is a graph showing the voltage dependence of the resistance component of the impedance of the optical switching elements of Example 3 and Comparative Example 4.

FIG. 5 is a graph showing the light quantity dependence of the resistance component of the impedance of the optical switching elements of Example 3 and Comparative Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Electrode 14 Lower charge generation layer 16 Charge transport layer 18 Upper charge generation layer 20 Optical writing type recording medium 30 Optical switching element 40 Display element 50 Functional film 65 Connector 70, 82 Control means 84 Light pattern generation means 86 Light irradiation means

Continued on the front page F term (reference) 2H079 AA08 AA15 BA01 CA02 CA22 CA23 DA07 DA08 EA14 GA05 2H092 GA05 GA50 JA24 JA28 KA05 MA04 MA05 MA29 NA25 PA13 QA07 QA11 QA13 RA05

Claims (12)

[Claims] 1. A light for switching a functional element driven by an AC electric field or an AC current, in which at least an electrode layer, a lower charge generation layer, a charge transport layer, and an upper charge generation layer are sequentially laminated on a substrate. An optical switching element comprising a conductive switching element, wherein the upper charge generation layer is formed from a dispersion for forming an upper charge generation layer containing at least a charge generation material, a binder, and a solvent that does not damage the charge transport layer. 2. The optical switching element according to claim 1, wherein the solvent is a protic solvent and has a solubility parameter of 9.0 or more. 3. The charge transport layer according to claim 1, wherein the binder of the charge transport layer is a polycarbonate resin, and the solvent is a solvent having at least one hydroxy group in a molecule. Optical switching element. 4. The binder according to claim 1, wherein the binder of at least the upper charge generation layer of the lower charge generation layer and the upper charge generation layer contains a polyvinyl butyral resin or a polyamide resin carboxyl-modified vinyl chloride-vinyl acetate copolymer. An optical switching element according to claim 3. 5. The method according to claim 1, wherein the solvent is 1-butanol, 3-methyl-
The optical switching element according to any one of claims 1 to 4, wherein the optical switching element is at least one of 3-hydroxy-2-butanone and 4-methyl-4-hydroxy-2-pentanone. 6. The binder of the upper charge generation layer is a polyvinyl butyral resin or a polyamide resin,
The solvent is 1-butanol, 3-methyl-3-hydroxy-2-butanone, or 4-methyl-4-hydroxy-2-
2. The method according to claim 1, which is at least one of pentanone.
An optical switching element according to claim 5. 7. The charge generation material of the upper charge generation layer is at least one of chlorogallium phthalocyanine, hydroxygallium phthalocyanine or titanyl phthalocyanine, the binder of the upper charge generation layer is polyvinyl butyral resin or polyamide resin, and The solvent is 1-butanol, 3-methyl-3-hydroxy-2-
The optical switching element according to any one of claims 1 to 6, wherein the optical switching element is at least one of butanone and 4-methyl-4-hydroxy-2-pentanone. 8. Switching of a functional element driven by an AC electric field or an AC current by sequentially laminating at least an electrode layer, a lower charge generation layer, a charge transport layer, and an upper charge generation layer on a substrate. In the method of manufacturing a photoconductive switching element of the above, the upper charge generating layer, the upper charge generating layer forming dispersion containing at least a charge generating material, a binder and a solvent that does not damage the charge transporting layer, on the charge transporting layer A method for manufacturing the optical switching element, comprising a step of forming by applying. 9. A device in which the optical switching element according to claim 1 and a functional element are electrically connected. 10. An optical writing type recording medium in which at least an electrode, a display layer, an optical switching element, and an electrode are laminated between a pair of substrates, the optical switching element according to any one of claims 1 to 7, The optical switching element according to any one of claims 1 to 3, wherein the upper charge generation layer of the element is located on the display layer side, and at least the substrate and the electrode on the side where the writing light is incident are light-transmissive. Optical writing type recording medium. 11. A display device comprising: the optically writable recording medium according to claim 10, a recording medium driving device for driving the recording medium, a writing device for performing optical writing on the recording medium, and a control unit. 12. A recording medium drive device to which the optical recording medium according to claim 10 can be connected, a writing device that performs optical writing on the recording medium, and a control device.