JPH07287215A - Liquid crystal/high molecular composite type optical element - Google Patents

Abstract

PURPOSE:To provide a liquid crystal/high molecular composite type optical element which can make a pattern display and a liquid crystal/high molecular composite type optical element which can represent the shading of the display with superior gradations without making the electrode structure, driving circuit, etc., of the element complex and expensive. CONSTITUTION:The liquid crystal/high molecular composite type optical element having its composite film 5 composed of two kinds of patterned composite films A-C containing liquid crystal particles of mutually different mean particle size on a liquid crystal optical element formed by forming the liquid crystal/high molecular composite films having the liquid crystal particles dispersed in a high/molecular matrix on a conductive substrate, and the liquid crystals/high molecular composite type optical element which has its composite film formed by laminating at least two kinds of composite film containing liquid crystal particles of mutually different mean particles size are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal optical element using a liquid crystal / polymer composite film which has a response to an electric field and heat and can display and record various information. Relates to a liquid crystal optical element capable of displaying a pattern only by changing an applied voltage, and further capable of performing a display excellent in density gradation only by changing an applied voltage.

[0002]

2. Description of the Related Art Conventionally, since liquid crystal optical elements such as liquid crystal displays have the characteristics of low power consumption, light weight, and thin shape, they are used as display media for characters and images such as wrist watches, calculators, personal computers, and televisions. Widely used in. General T
The N- and STN- liquid crystal displays are obtained by enclosing a liquid crystal in a liquid crystal cell in which a glass plate having transparent electrodes is provided with a predetermined seal or the like, and further sandwiching a polarizing plate from both sides.

However, the liquid crystal optical element as described above (1) requires two polarizing plates, so that the viewing angle is narrow and the brightness is insufficient. Therefore, a backlight with high power consumption is required. (2) cell thickness dependency is large, it is difficult to increase the area, and (3) there is a problem that the manufacturing cost is high because the structure is complicated and it is difficult to enclose the liquid crystal in the cell.
There are limits to the weight reduction, thickness reduction, large area, low power consumption, and cost reduction of liquid crystal displays.

As a liquid crystal display medium for solving such problems, application of a liquid crystal optical element based on a light scattering mechanism using a liquid crystal / polymer composite film in which liquid crystal particles are dispersed in a polymer matrix is expected, The research and development has become active. A large number of liquid crystal optical elements using a liquid crystal / polymer composite film and a method for producing the same have already been disclosed. One of them is a method for producing a liquid crystal from an emulsion in which a polyvinyl alcohol (PVA) aqueous solution is dispersed ( Japanese Patent Fair 3-52
No. 843). The liquid crystal optical element manufactured by this method has characteristics such as a high contrast ratio because the light transmittance when voltage is turned off is lowered by adding a dichroic dye.

[0005]

However, when a pattern display is performed using the above liquid crystal / polymer composite film type liquid crystal optical element, or in order to improve the gradation of the display, the electrodes are formed into a complicated pattern. It is necessary to form the liquid crystal optical element or to laminate the liquid crystal optical element itself to perform the segment type static drive, and it is indispensable to design and manufacture a drive circuit and pattern electrodes. As a result, the device becomes complicated, and high cost and an increase in size of the device cannot be avoided.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to enable liquid crystal / polymer composite type optical element capable of pattern display without making the electrode structure of the element and the driving circuit complicated and expensive. To provide. Another object of the present invention is to provide a liquid crystal / polymer composite type optical element capable of expressing light and shade of display with excellent gradation without making the electrode structure of the element, the driving circuit, etc. complicated and expensive. To do.

[0007]

The above object can be achieved by the present invention described below. That is, the present invention provides a liquid crystal optical element in which a liquid crystal / polymer composite film in which liquid crystal particles are dispersed in a polymer matrix is formed on a conductive substrate, wherein the composite film has different average particle diameters. A liquid crystal / polymer composite type optical element characterized by being formed in a pattern from at least two kinds of composite films containing, and at least 2 containing liquid crystal particles having different average particle diameters. A liquid crystal / polymer composite-type optical element comprising a stack of seed composite films.

[0008]

The driving voltage of the liquid crystal display element depends on the diameter of the liquid crystal particles used in the element (see FIGS. 3 to 5). The present invention applies this principle. That is, in a liquid crystal / polymer composite type liquid crystal element, by forming the composite film in a pattern from at least two kinds of composite films containing liquid crystal particles having different average particle diameters, the electrode structure of the element, the driving circuit, etc. It is possible to display patterns only by changing the magnitude of the driving voltage without making the device complicated and expensive. Further, by forming the above composite film by laminating at least two kinds of composite films containing liquid crystal particles having different average particle diameters, the electrode structure of the device, the driving circuit, etc. are not complicated and expensive,
The gradation of display can be expressed with excellent gradation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The display element according to the first aspect of the present invention has a liquid crystal / polymer composite film 5 in which liquid crystal particles are dispersed in a polymer matrix, at least one of which has a transparent conductive property, as shown in the cross section of FIG. The composite film 5 is sandwiched between two conductive substrates 1 and 2 which are substrates, and the composite film 5 contains at least two kinds, for example, three kinds of composite films A containing liquid crystal particles having different average particle diameters. , B and C are formed in a pattern.

The display element according to the second aspect of the present invention has a liquid crystal / polymer composite film 5 in which liquid crystal particles are dispersed in a polymer matrix, as shown in the cross section of FIG.
Is sandwiched between two conductive substrates 1 and 2 at least one of which is a transparent conductive substrate, wherein the composite film 5 contains at least two kinds of liquid crystal particles having different average particle diameters, For example, it is characterized by laminating three kinds of composite films A, B and C. The above is about the case where the liquid crystal optical element is used as a display, but other applications include the case where the composite film of any of the above is formed on a conductive substrate and a protective film is formed on the composite film. Some cards can be rewritten. Hereinafter, a display element using two electrodes will be described in detail.

The conductive substrate used in the above display element is generally used in a conventionally known liquid crystal display element, and any conventionally known conductive substrate can be used in the present invention. Yes, specifically, for example, IT
Transparent conductive materials such as O, SnO ₂ series, ZnO series 3, 4
Is a pair of electrode substrates obtained by adhering to transparent substrates 1 and 2 such as glass or polymer film. At this time, when an opaque conductive substrate is used for the other side, its electrode is also required to function as a reflection plate, and therefore, for example, a substrate provided with an aluminum reflection electrode is preferable. The substrate itself is glass,
It may be a polymer film or the like.

Liquid crystal sandwiched between the pair of conductive substrates
The polymer composite film 5 is a film in which liquid crystal particles are uniformly dispersed in a polymer matrix, and is formed of liquid crystal and a polymer material that is incompatible with the liquid crystal. The liquid crystal used for forming the liquid crystal / polymer composite film is an organic mixture which exhibits a liquid crystal state at around room temperature, and includes nematic liquid crystal, cholesteric liquid crystal and smectic liquid crystal, and any known liquid crystal material in the present invention. However, nematic liquid crystals or nematic liquid crystals to which cholesteric liquid crystals are added are preferable in terms of characteristics. These liquid crystals may be microencapsulated.

The above liquid crystal may be colored with a dichroic dye before use. The reason for coloring the liquid crystal is also for the purpose of color display by coloring, but also for the purpose of enhancing the contrast of the displayed image by utilizing the difference in light absorption between when voltage is applied and when voltage is not applied. As the dichroic dye used for coloring, guest-host type ones commonly used in TN- and STN-type liquid crystal displays may be used.

As the polymer material used as the polymer matrix for fixing the liquid crystal particles, any polymer material which is not compatible with liquid crystal and is excellent in transparency and film forming ability can be used. . Specifically, a suitable polymer material is used according to the method for forming the composite film. The amount of the liquid crystal and the polymer matrix used is such that the mixture ratio (weight ratio) of polymer matrix / liquid crystal is 5/95 to 5
It is 0/50, and if the amount of liquid crystal used is too small, not only is the transparency insufficient when the voltage is turned on, but also a large amount of voltage is required to bring the film into a transparent state. Yes,
On the other hand, if the amount of the liquid crystal used is too large, not only the scattering (turbidity) when the voltage is turned off becomes insufficient, but also the strength of the film decreases, which is not preferable.

In the present invention, when the liquid crystal / polymer composite film 5 is formed between the pair of conductive substrates 1 and 2, as shown in FIG. 1 or 2, two or more kinds having different average particle diameters are used. Need to facilitate liquid crystal particles. As a method for forming and dispersing the liquid crystal particles in the polymer matrix, any conventionally known method such as a phase separation method or an emulsion method can be used, but the most useful method is the emulsion method.
The emulsion method will be described below as a typical example. However, the present invention is not limited to the emulsion method.

In the emulsion method, the liquid crystal is emulsified and dispersed in a medium mainly containing water containing a surfactant and a protective colloid as necessary, and polyvinyl alcohol, gelatin, an acrylic acid copolymer and a water solution are added to the emulsion. Of a water-soluble or water-dispersible polymer material such as a water-soluble alkyd resin is applied and dried on a suitable substrate to form a film having a suitable thickness. A liquid crystal / polymer composite film in which liquid crystal particles are uniformly dispersed is formed in the formed film.

In the present invention, when the above liquid crystal emulsion is prepared, various emulsification conditions are changed to obtain
It is possible to form two or more kinds of liquid crystal emulsions containing liquid crystal particles having an arbitrary average particle diameter. In the present invention, two or more kinds of liquid crystal particles having different average particle diameters are produced, and the range of the average particle diameter is about 5 as the maximum average particle diameter.
On the other hand, the minimum average particle size is about 0.
The limit is about 5 μm. In the case of liquid crystal particles having an average particle diameter exceeding the maximum average particle diameter, there is a problem that the display quality is not good because sufficient light scattering cannot be obtained when no electric field is applied, while the minimum average particle diameter In the case of liquid crystal particles having an average particle size less than the particle size, it is unsuitable because the voltage for transitioning from the light scattering state to the light transmitting state becomes high, and,
Since there are problems such as insufficient light transmission, it is preferable that the two or more kinds of liquid crystal particles having different average particle sizes used in the present invention fall within the range of about 0.5 to 5 μm.

As a method for emulsifying and dispersing the above liquid crystal in an aqueous solution or an aqueous dispersion of the above polymer matrix, a mixing method using various stirring devices such as an ultrasonic disperser or a film emulsification method [Tadao Nakajima and Masataka Shimizu] , PHARMTECH JAP
The dispersion method such as AN Vol. 4, No. 10 (1988)] is effective. By using these emulsification dispersion methods and changing the emulsification dispersion conditions to disperse the liquid crystal in the aqueous medium, two or more kinds of liquid crystal emulsions containing liquid crystal particles having different average particle diameters can be obtained. For example, when an O / W emulsion of liquid crystal is obtained by a porous glass (MPG) film emulsification system, the average particle size of liquid crystal particles to be emulsified and dispersed can be arbitrarily changed by changing the average pore size of MPG to be used. I can.

In the first invention of the present invention, a method of forming a liquid crystal / polymer composite film in a pattern on an electrode substrate by using two or more kinds of liquid crystal emulsions containing liquid crystal particles having different average particle diameters. Examples thereof include an electrodeposition coating method, screen printing, stencil printing using a metal mask, brush coating, spray coating, blade coating, doctor coating and the like. Among these coating methods, the preferable method is the electrodeposition coating method. According to this method, two or more kinds of liquid crystal emulsions for electrodeposition coating containing liquid crystal particles having different average particle diameters are prepared, and first, First, a liquid crystal emulsion containing liquid crystal particles having a specific average particle diameter is prepared only in a desired region of an electrode substrate of a display element, for example, by using a mask method or dividing an electrode into a desired pattern. By coating as an electrodeposition bath, then by coating a liquid crystal emulsion for electrodeposition coating containing liquid crystal particles having another average particle diameter as an electrodeposition bath, and repeating such operations, the average particle size on the electrode substrate surface is increased. The patterned liquid crystal / polymer composite film 5 can be formed from at least two kinds of composite films containing liquid crystal particles having different diameters. Also in the second invention of the present invention, a liquid crystal in a state where at least two kinds of composite films containing liquid crystal particles having different average particle sizes as shown in FIG. The polymer composite film 5 can be formed.

After the liquid crystal / polymer composite film 5 is formed in a pattern or laminated on the electrode substrate as described above, it is dried at room temperature or at a temperature not affecting the liquid crystal particles. The liquid crystal / polymer composite film 5 is formed. When the liquid crystal / polymer composite film 5 is formed in a pattern,
The thickness of the liquid crystal / polymer composite film 5 is preferably about 3 to 5 μm. Further, when the liquid crystal / polymer composite film 5 is formed by laminating, the total thickness of the liquid crystal / polymer composite film 5 in the laminated state is preferably about 9 to 15 μm, and the thickness of each laminated layer is Is preferably about 3 to 5 μm. Finally, a liquid crystal optical element of the present invention can be obtained by laminating a counter electrode on the surface of the liquid crystal / polymer composite film 5 according to a conventional method.

Next, the application as a card in which information can be rewritten will be described focusing on the difference from the case of the display element of the form using the two electrodes described above. For cards, only one electrode is used. A polymer film needs to be particularly suitable as a substrate for the electrode. White polyethylene terephthalate (P
ET) film is preferred. For the conductive layer, a metal such as aluminum can be used in addition to a transparent conductive material such as ITO. Further, in order to protect the liquid crystal / polymer composite film, a protective film is provided on the composite film. The protective film is not particularly limited, but a cured resin having mechanical strength, water resistance and the like is preferable. For example, UV or electron beam curable poly (meth) acrylate, polyurethane (meth) acrylate and the like are used. When the protective layer film cannot be directly formed on the liquid crystal / polymer composite film, a thin film of a water-soluble polymer such as polyvinyl alcohol may be formed as an intermediate layer between the composite film and the protective film. Good. Alternatively, the protective film material formed on another sheet may be transferred, laminated, and cured to form the protective film material. In the case of a card, since the information recorded on the card is required to have stability over time, the liquid crystal used is preferably a liquid crystal exhibiting a smectic property unlike the case of a display. In the case of card applications, the ratio of liquid crystal and polymer used is different from that of display, and the liquid crystal / polymer ratio (weight ratio) is 55/4.
The range of 5 to 35/65 is preferable. Further, it is preferable that the liquid crystal contains a dichroic dye in order to increase the display contrast.

Next, recording and erasing of information on the card having the above structure will be described. Information is erased by applying a necessary electric field to the liquid crystal / polymer composite film layer and aligning the liquid crystal molecules in the electric field direction. The corona charging method is particularly effective as a method for applying an electric field. Information is recorded by applying necessary heat to the composite film layer and disturbing the alignment of liquid crystal molecules in the heated part. As a method for applying heat, a method using a thermal head is preferable.

[0023]

EXAMPLES Next, the present invention will be specifically described with reference to examples. Example 1 The applied voltage (driving voltage) at which the light transmittance is 90% is 1
A liquid crystal / polymer composite film of 0 V, 30 V, and 60 V was formed in a pattern on the electrode substrate surface from the liquid crystal emulsion prepared as follows.

In a liquid crystal microencapsulated porous glass (MPG) membrane emulsification system [manufactured by Ise Chemical Industry Co., Ltd.], an O / W emulsion was prepared from the following composition using porous glass having an average pore diameter of 0.20 μm. It was made. Oil phase: Methyl methacrylate (MMA) 3 parts by weight Nematic liquid crystal (BL-010, manufactured by Merck Ltd.) 100 parts by weight Azobisisobutyronitrile 0.08 parts by weight Water phase: Polyvinyl alcohol (KP-06, Nippon Synthetic Chemical Industry) 5 parts by weight Water 95 parts by weight

The liquid crystal particles were encapsulated with PMMA walls by heating this emulsion at 70 ° C. for 20 hours. The average particle size of the obtained microencapsulated liquid crystal particles was 1.7 μm. A microencapsulated liquid crystal was produced by the same method as described above except that MPG having an average pore size of 0.37 μm was used, and the average particle size was 2.8 μm. A microencapsulated liquid crystal was produced by the same method as described above except that MPG having an average pore size of 0.49 μm was used, and the average particle size was 4.3 μm.

Preparation of Electrodeposition Bath Each of the solutions containing the above-mentioned three kinds of microencapsulated liquid crystal particles was centrifuged to precipitate the microcapsules and then washed with water. This process was repeated, and the three kinds of microencapsulated liquid crystals were repeated. The particles were isolated. Using the three types of isolated microcapsulated liquid crystal particles, three types of electrodeposition baths having the following compositions were prepared. Microencapsulated liquid crystal particles (or) 40 parts by weight Acrylic copolymer 5 parts by weight Triethylamine 1.4 parts by weight Ethanol 30 parts by weight Water 200 parts by weight

The above acrylic copolymer was synthesized by polymerizing a monomer mixture having the following composition under a nitrogen stream at 60 ° C. for 7 hours, and then purified and isolated by a reprecipitation method. Methacrylic acid 10 parts by weight Methyl methacrylate 11 parts by weight Butyl methacrylate 38 parts by weight 2-Ethoxyethanol 89 parts by weight Azobisisobutyronitrile 1.2 parts by weight

Formation of Liquid Crystal / Polymer Composite Film Using the three kinds of electrodeposition baths obtained as described above, transparent electrodes previously divided into desired pattern shapes are used, and only corresponding electrode portions are sequentially energized. By doing so, a coating film of a liquid crystal / polymer composite film containing the microcapsulated liquid crystal particles of was obtained. Finally, it was sufficiently dried to form a liquid crystal / polymer composite film having a pattern as shown in FIG. 1 and a thickness of 5 μm.
The liquid crystal / polymer composite film containing the capsules is formed in the region C of FIG. 1, the liquid crystal / polymer composite film containing the capsules is formed in the region B, and the liquid crystal / polymer composite film containing the capsules is formed in the region A. A liquid crystal / polymer composite film including the capsules was formed. When driving, the divided electrodes are combined as appropriate, and
The combination of C is treated as one pixel.

A glass substrate with ITO was laminated on the surface of the liquid crystal / polymer composite film to prepare a liquid crystal / polymer composite type optical element of the present invention. When a voltage of 10 V is applied to this optical element, only the region C in FIG. 1 becomes light transmissive, and when a voltage of 30 V is applied next, the regions C and B become light transmissive, and the voltage of 60 V is further applied. Is applied,
All areas of A, B and C became transparent. Therefore, it is possible to display a pattern by changing the applied voltage without patterning the electrodes of the device. The relationship between the applied voltage (V) in the region C and the light transmittance (T) of the device is shown in FIG.
FIG. 4 shows the relationship between the applied voltage (V) in the region B and the light transmittance (T) of the device, and FIG. 5 shows the relationship between the applied voltage (V) in the region A and the light transmittance (T) of the device. It was

Example 2 A glass-coated ITO substrate was coated with a dispersion liquid containing capsules using a blade coater and dried to form a liquid crystal / polymer composite film A. To form a liquid crystal / polymer composite film B, and finally, the capsule-containing dispersion liquid is similarly applied and dried to form a liquid crystal / polymer composite film C. 3 A liquid crystal / polymer composite film consisting of layers was formed, and a laminated body as shown in FIG. 2 was formed into a liquid crystal / polymer composite film having a total thickness of 12 μm. A liquid crystal / polymer composite film (thickness 5 μm) including the capsule is formed as the layer C in FIG. 2, a liquid crystal / polymer composite film (thickness 4 μm) including the capsule is formed as the layer B, and the layer A is formed. A liquid crystal / polymer composite film (thickness 3 μm) containing the capsule was formed.

A glass substrate with ITO was laminated on the surface of the liquid crystal / polymer composite film to prepare a liquid crystal / polymer composite optical element of the present invention. When a voltage of 10 V was applied to this optical element, the light transmittance was slightly improved, and when a voltage of 30 V was applied next, it became semitransparent, and when a voltage of 60 V was further applied, the whole became almost transparent. Therefore, it becomes possible to change the shading of the display only by changing the applied voltage. In particular, it was possible to change the color tone according to the applied voltage by changing the type of guest / host dye added to the liquid crystal used in each layer. FIG. 6 shows the relationship between the voltage applied to each layer and the light transmittance in the above-mentioned laminated device.

Example 3 A liquid crystal / polymer composite film having applied voltages (driving voltages) of 90%, 90 V, 160 V, and 210 V, respectively, which gives a light transmittance of 90%, was prepared in the following manner to prepare liquid crystal microcapsules. It was used to form a pattern on an electrode substrate.

In a liquid crystal micro-encapsulated porous glass (MPG) film emulsification system [manufactured by Ise Chemical Industry Co., Ltd.], an O / W emulsion was prepared from the following composition using porous glass having an average pore diameter of 0.75 μm. It was made. Oil phase: Methyl methacrylate (MMA) 10 parts by weight Smectic liquid crystal (S-6, manufactured by Merck) 100 parts by weight Azobisisobutyronitrile 0.2 parts by weight Water phase: Polyvinyl alcohol (EG-05, Nippon Synthetic Chemical Industry) (Manufactured by Ltd.) 10 parts by weight Water 200 parts by weight

The liquid crystal particles were encapsulated with PMMA walls by heating this emulsion at 70 ° C. for 20 hours. The average particle size of the obtained microencapsulated liquid crystal particles was 4.5 μm. A microencapsulated liquid crystal having an average particle diameter of 2.7 μm was produced by the same method as described above except that the MPG having an average pore diameter of 0.49 μm was used. A microencapsulated liquid crystal having an average particle diameter of 1.9 μm was produced by the same method as described above except that MPG having an average pore diameter of 0.33 μm was used. Formation of liquid crystal / polymer composite film

In the same manner as in Example 1, a composite film composed of the above-mentioned microencapsulated liquid crystal and polymer and having a pattern similar to that shown in FIG. 1 and a thickness of 5 μm was formed. A transparent PET film with ITO was laminated on the above composite film surface to prepare a liquid crystal optical element. When a voltage of 90 V was applied to this optical element, the portion using the microcapsules became light transmissive. This state was kept stable even after the voltage application was stopped. When a voltage of 160 V was applied, the part using the microcapsules became transparent, and this state was kept stable even after the voltage application was stopped. 21 at the end
When a voltage of 0 V was applied, the part using the microcapsules also became light-transmitting, and this state was kept stable even after the voltage application was stopped. Therefore, it is possible to display a pattern by changing the voltage applied to the laminated composite film without patterning the electrodes of the optical element. This pattern display was kept stable even after the voltage application was stopped.

Example 4 A liquid crystal / polymer composite film containing a dichroic dye in the liquid crystal was prepared as follows. Dye-containing liquid crystal microencapsulated dichroic dye S-428 [black, manufactured by Mitsui Toatsu Co., Ltd.]
Was added in the same manner as in the microcapsule of Example 3 except that 1.8 parts by weight of was added to obtain a dye-containing liquid crystal microcapsule having an average particle diameter of 4.5 μm. Dichroic dye M-412 [blue, manufactured by Mitsui Toatsu Co., Ltd.]
Was added in the same manner as in the microcapsule of Example 3 to obtain a dye-containing liquid crystal microcapsule having an average particle diameter of 2.6 μm. Dichroic dye M-361 [yellow, manufactured by Mitsui Toatsu Co., Ltd.]
Was added in the same manner as in the microcapsule of Example 3 except that 1.8 parts by weight of was added to obtain a dye-containing liquid crystal microcapsule having an average particle diameter of 1.9 μm.

Formation of Liquid Crystal / Polymer Composite Film PVA (KH-20, manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to each of the dye-containing liquid crystal microcapsule dispersions described above.
Was added so that the liquid crystal / PVC would be 1/1 (weight ratio). A white PET film with ITO is coated with a dispersion liquid containing a capsule using a blade coater and dried to form a liquid crystal / polymer composite film A, and the next dispersion liquid containing a capsule is similarly applied in an overlapping manner. And dry LCD /
A polymer composite film B is formed, and finally, a dispersion liquid containing a capsule is similarly overlaid, coated and dried to form a liquid crystal / polymer composite film C, and a liquid crystal / polymer composite film composed of three layers is formed. The laminated body as shown in FIG. 2 has a total thickness of 12 μm.
m liquid crystal / polymer composite film. A liquid crystal / polymer composite film (thickness 5 μm) containing the above-mentioned capsule as the layer C in FIG.
To form a liquid crystal / polymer composite film (thickness 4 μm) containing the capsule as layer B, and a liquid crystal / polymer composite film (thickness 3 μm) containing the capsule as layer A. PVA (KH-2 as an intermediate layer on the C layer
The 0) layer was formed to a thickness of 2 μm. Furthermore, trimethylolpropane triacrylate (EXG-408,
2) by coating with Dainichiseika Kogyo Co., Ltd. and curing with an electron beam
A protective film of μm was formed.

When a corona voltage of 4.5 KV was applied to the above optical element, the display changed from black to greenish blue due to the alignment of the liquid crystal molecules and the dichroic dye molecules in the film C, This state was maintained even after the voltage application was stopped. Next, when a corona voltage of 5.5 KV was applied, the display changed from greenish blue to yellow due to the orientation of the liquid crystal molecules and the dichroic dye molecules in the film B. In this state, the voltage was not applied. It was retained even after stopping. Finally 6.5KV
When the corona voltage of 2 is applied, the liquid crystal molecules in film A
The color dye molecules were oriented, and the display was white. This state was maintained even after the voltage application was stopped. When printing was performed on this film using a thermal head, black characters could be recorded.

[0039]

According to the present invention as described above, in a liquid crystal / polymer composite type liquid crystal device, the composite film is formed in a pattern from at least two kinds of composite films containing liquid crystal particles having different average particle diameters. As a result, pattern display can be performed only by changing the magnitude of the driving voltage without making the electrode structure of the element, the driving circuit, etc. complicated and expensive. Further, by forming the above composite film by laminating at least two kinds of composite films containing liquid crystal particles having different average particle diameters, it is possible to realize a display without complicating an electrode structure of an element, a driving circuit and the like. It is possible to express light and shade with excellent gradation. Therefore, the liquid crystal optical element of the present invention described above can be widely applied to a display, a light control panel, a rewritable display recording medium (card, OHP, etc.) and the like.

[0040]

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a liquid crystal optical element of the present invention.

FIG. 2 is a schematic sectional view of a liquid crystal optical element of the present invention.

FIG. 3 is a diagram showing a relationship between an applied voltage and a light transmittance in a region (layer) C.

FIG. 4 is a diagram showing a relationship between an applied voltage and a light transmittance in a region (layer) B.

FIG. 5 is a diagram showing a relationship between an applied voltage and light transmittance in a region (layer) A.

FIG. 6 is a diagram showing the relationship between the applied voltage of each layer and the light transmittance in the laminated device.

[Explanation of symbols]

 1, 2: substrate 3, 4: electrode 5: overall liquid crystal / polymer composite film A, B, C: individual liquid crystal / polymer composite film

Claims (10)

[Claims] 1. A liquid crystal optical element comprising a liquid crystal / polymer composite film having liquid crystal particles dispersed in a polymer matrix formed on a conductive substrate, wherein the composite film comprises liquid crystal particles having different average particle diameters. A liquid crystal / polymer composite type optical element, which is formed in a pattern from at least two kinds of composite films contained therein. 2. A liquid crystal optical element comprising a liquid crystal / polymer composite film having liquid crystal particles dispersed in a polymer matrix formed on a conductive substrate, wherein the composite film comprises liquid crystal particles having different average particle diameters. A liquid crystal / polymer composite type optical element comprising a laminate of at least two kinds of composite films contained therein. 3. The liquid crystal / polymer composite type optical element according to claim 1, wherein the liquid crystal particles are microencapsulated. 4. The liquid crystal / polymer composite optical element according to claim 1, wherein the liquid crystal particles contain a dichroic dye. 5. The liquid crystal / polymer composite optical element according to claim 1, wherein the liquid crystal / polymer composite film is formed by an emulsion method. 6. A liquid crystal / polymer composite type optical element according to claim 1, wherein a protective layer is provided on the composite film according to claim 1 or 2. 7. The liquid crystal / polymer composite optical element according to claim 1, wherein a conductive substrate is provided on the composite film according to claim 1 or 2. 8. A card in which information can be rewritten by forming a protective layer on the composite film according to claim 1. 9. A rewritable card according to claim 8, wherein the liquid crystal contains a dichroic dye. 10. The method of using the card according to claim 8, wherein the information is recorded by heat and the information is erased by an electric field.