JP2005308854A - Liquid crystal light modulator and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal light modulator excellent in flexibility and strength and having a good light modulation function, and a liquid crystal display device using the liquid crystal light modulator.
A first substrate 11 on which a first electrode 12 is formed, a second substrate 13 on which a second electrode 14 is formed, and the first substrate 11 and the second substrate 13 are provided. A liquid crystal optical modulator having a maintaining unit for maintaining a distance and a liquid crystal 18 held between the first substrate 11 and the second substrate 13, wherein the support unit is the first substrate. And a second substrate made of a support layer 19 made of an organic material. The support layer 19 has a plurality of holes 20 filled with the liquid crystal 18.
[Selection] Figure 1

Description

  The present invention relates to a liquid crystal light modulator and a liquid crystal display device using the liquid crystal light modulator.

  In recent years, optical modulators using liquid crystals, such as liquid crystal display devices, have been attracting attention because they are less likely to be damaged by impact and have excellent flexibility that can be folded and rolled. .

  For example, such an optical modulator has a structure in which liquid crystal is injected between two opposing substrates, and the state of the liquid crystal is changed by changing the voltage applied to the liquid crystal to perform light modulation. doing. In this case, the distance between the two substrates needs to be kept constant. Particularly in the case of an optical modulator having flexibility, when the optical modulator is bent or rounded and deformed. However, it is preferable that the distance between the opposing substrates is kept constant.

  For this reason, in an optical modulator that requires such flexibility, it is difficult to keep the distance between the opposing substrates constant with the conventional spacer structure that is dispersed in the liquid crystal layer.

  For this reason, in a flexible optical modulator, the support portion (spacer) that supports two opposing substrates can maintain a constant spacing between the opposing substrates, and can be flexible. It is preferable to have.

  As a structure of an optical modulator that meets such requirements, a structure in which a support portion made of a synthetic resin is formed between substrates has been proposed.

As a method of forming a support portion made of a synthetic resin between substrates, for example, a mixed solution in which a raw material of a synthetic resin (monomer, oligomer, etc.) is dissolved in liquid crystal is injected between two opposing substrates, A synthetic resin and a liquid crystal are separated by a photopolymerization reaction of raw materials (for example, see Non-Patent Document 1) or a thermal polymerization reaction (for example, see Non-Patent Document 2), and the substrate, for example, in the shape of a rib or a column, is placed between opposing substrates There has been proposed a method of forming a support part for supporting the slab.
NAVaz, GWSmithand GPMontgomery, Jr. "A light control film composed of liquid crystaldroplets dispersed in a UV-curable polymer", Mol. Cryst. Liq. Cryst., Vol. 146, pp. 1-15 (1987) NAVaz, GWSmith and GPMontgomery, Jr. "A light controlfilm composed of liquid crystal droplets dispersed in an epoxy matrix", Mol. Cryst. Liq. Cryst., Vol. 146, pp. 17-34 (1987)

  However, as described above, in the case where the support portion for supporting the substrate is formed by polymerizing the raw material of the synthetic resin, the following problems occur.

  First, in the process of separating the liquid crystal and the synthetic resin by photopolymerization or thermal polymerization and forming the support part, the liquid crystal is mixed into the resin, so that the mechanical strength of the formed support part decreases. there were. In addition, since the raw material of unreacted synthetic resin remains in the liquid crystal, the light modulation function of the liquid crystal deteriorates. For example, a display device using the light modulator has a problem that display quality deteriorates.

  In addition, when forming a rib-like or columnar support using a polymerization reaction, for example, the shape and size vary in the liquid crystal, and it is difficult to control the shape particularly in the depth direction. It was difficult to uniformly form the shape of the support portion or the mechanical strength of the support portion.

  In addition, in a rib-like or columnar support portion formed by polymerization, for example, when the resin is bent or rounded and the substrate is bent, it is limited to keep the distance between the two opposing substrates constant. was there.

  Accordingly, an object of the present invention is to provide a novel and useful liquid crystal light modulator and a liquid crystal display device using the liquid crystal light modulator, which solve the above problems.

  A specific problem of the present invention is to provide a liquid crystal light modulator excellent in flexibility and strength and having a good light modulation function, and a liquid crystal display device using the liquid crystal light modulator.

  The present invention solves the above-described problem by providing a first substrate on which a first electrode is formed, a second substrate on which a second electrode is formed, and an interval between the first substrate and the second substrate. And a liquid crystal optical modulator having a liquid crystal held between the first substrate and the second substrate, wherein the maintaining unit includes the first substrate and the second substrate. This is solved by a liquid crystal light modulator comprising a support layer made of an organic material formed between substrates, and a plurality of holes filled with the liquid crystal are formed in the support layer.

  In the present invention, since the support layer made of an organic material is formed between the first substrate and the second substrate, even when stress is applied to the liquid crystal optical modulator, the support layer is the first substrate. It is possible to keep the distance between the substrate and the second substrate uniform.

  In addition, it is preferable that the first substrate and the second substrate are made of an organic material because the liquid crystal light modulator has flexibility.

  Further, when the thickness of the support layer is 0.5 μm to 10 μm, good light modulation characteristics can be obtained at a low voltage.

  Further, when the ratio of the thickness of the support layer to the hole diameter of the hole is 0.01 to 100, the liquid crystal light modulator can have flexibility while holding the liquid crystal in the hole, Is preferred.

  Further, it is preferable that a fibrous polymer material is added to the liquid crystal because the switching characteristics of the liquid crystal can be freely changed.

  The liquid crystal may be a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal.

  In addition, since the liquid crystal display device using the liquid crystal light modulator has flexibility, it can be bent and rounded, and the display quality is good.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the liquid crystal light modulator which is excellent in a softness | flexibility and intensity | strength, and has a favorable light modulation function, and a liquid crystal display device using the said liquid crystal light modulator.

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

  FIG. 1 is a schematic cross-sectional view schematically showing a liquid crystal light modulator 10 according to a first embodiment of the present invention.

  Referring to FIG. 1, a liquid crystal light modulator 10 according to the present embodiment includes a first substrate 11 on which a first electrode 12 is formed, a second substrate 13 on which a second electrode 14 is formed, A support layer 19 that supports the first substrate 11 and the second substrate 13 is provided between the first substrate 11 and the second substrate 13.

  The first substrate 11 and the second substrate 13 are installed, for example, substantially in parallel, and are installed so that the first electrode 12 and the second electrode 14 face each other.

  A liquid crystal 18 is held between the first substrate 11 and the second substrate 13. When a voltage is applied to the liquid crystal 18 via the first electrode 12 and the second electrode 14, the state of transmitting light changes. Therefore, the incident light L1 incident from the second substrate 13 side is optically modulated by the liquid crystal 18 and can be emitted as the emitted light L2 from the first substrate 11 side.

The first electrode 12 and the second electrode 14 are preferably transparent, and for example, indium oxide doped with tin (ITO, In ₂ O ₃ : Sn) can be used. A wiring 15 and a wiring 16 are connected to the first electrode 12 and the second electrode 14, respectively, and the wiring 15 and the wiring 16 are connected to a power supply 17. As the power source 17, either a DC power source or an AC power source can be used.

  In the liquid crystal light modulator 10 according to the present embodiment, since the support layer 19 is made of an organic material such as a resin material, the liquid crystal light modulator 10 can be bent or rounded. In addition, since the support layer 19 is formed so as to extend between the first substrate and the second substrate, the first substrate 11 and the second substrate 13 are extended to the support layer 19. Even when stress is applied to the liquid crystal light modulator, the distance between the first substrate 11 and the second substrate 13 is larger than that of, for example, a columnar or rib-shaped spacer. Is structured to be able to be held substantially uniformly in the plane of the substrate. In this case, if the support layer 19 is formed to adhere to the first electrode 12 and the second electrode 14 or the first substrate 11 and the second substrate 13, the support layer 19 is supported when stress is applied. When the layer 19 has a large effect of maintaining the distance between the first substrate 11 and the second substrate 13 substantially the same and uniformly in the plane of the substrate, for example, when the liquid crystal light modulator is bent or rounded In addition, the distance between the first substrate 11 and the second substrate 13 can be held substantially the same and uniformly in the plane of the substrate.

  The support layer 19 has a plurality of holes 20 filled with the liquid crystal 18. The hole 20 is filled with the liquid crystal 18 so as to penetrate, and light modulation is performed by the liquid crystal 18 as described above. The intermediate layer M formed by the support layer 19 and the liquid crystal 18 and formed between the first substrate 11 and the second substrate 13 is also subjected to stress such as bending while performing optical modulation. It has a function of supporting the first substrate 11 and the second substrate 13 substantially uniformly within the plane of the substrate.

  The material used for the first substrate 11 and the second substrate 13 is preferably transparent, and when a flexible organic material is used, the liquid crystal light modulator can be bent or rolled. This is preferable. As the organic material, for example, a flexible plastic film such as polycarbonate, polyethylene terephthalate, or polyethersulfone having a thickness of 0.3 mm or less is preferably used. In this case, for example, if the first substrate 11 and the support layer 19 are integrally formed, it is possible to form a liquid crystal light modulator that is lightweight and can be bent, which is preferable. Moreover, as an inorganic material, it is also possible to use a thin glass plate of 0.6 mm or less.

  Next, FIG. 2 shows a perspective view schematically showing the support layer 19. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted. The size of the support layer 19 and the number of holes can be arbitrarily changed and used.

  Referring to FIG. 2, the support layer 19 is formed with a plurality of, for example, columnar holes 20 filled with the liquid crystal 18 so as to penetrate the support layer 19. In the case of the present embodiment, the thickness D1 of the support layer 19 is preferably 100 μm or less, for example, in order to obtain good light modulation characteristics at a low voltage, the thickness D1 is 0.5 μm to 10 μm. It is particularly preferable to do this.

  Further, when the ratio of the thickness D1 of the support layer to the hole diameter d1 of the hole 20 is 0.01 to 100, the liquid crystal light modulator has flexibility while holding the liquid crystal 19 in the hole 20. Although it is possible and preferable, it is not limited to this value.

  The material of the support layer 19 is preferably an organic material such as a flexible resin material. Examples of the resin material that can be used for the support layer 19 include acrylic resin, methacrylic resin, epoxy resin, urethane resin, polystyrene, polyvinyl alcohol, fluororesin, polyvinyl chloride, vinyl acetate, phenol resin, cellulose resin, and polyethylene. , Polypropylene, melanin resin, polyester, polyvinyl butyral, polyvinyl carbazole, polyvinyl acetate, a resin material selected from the group consisting of polycarbonate and silicone resin, or a copolymer of these resin materials (for example, acrylic urethane resin), cellulose, etc. However, it is not limited to these.

  Further, when the liquid crystal light modulator needs to be bent greatly, such as by bending or rounding, a liquid crystal light modulator can be obtained by using a material excellent in flexibility such as synthetic rubber or natural rubber for the support layer 19. It is possible to make a large curve of

  Further, the contrast and response speed of the optical modulator can be variously changed by changing the size of the hole 20 and the density to be formed.

  FIGS. 3A to 3E are plan views showing examples of the state of the holes formed in the support layer 19. However, in the drawings, illustrations are omitted except for the holes.

  FIG. 3A shows the hole 20 shown in FIG. 2, and the holes 20 having a plurality of hole diameters d1 are formed in the support layer, for example, on a lattice.

  3B is an example in which a hole 20a having a smaller diameter than the hole 20 is formed in the support layer, and FIG. 3C is a hole having a larger diameter than the hole 20 in the support layer. This is an example in which 20b is formed. If the hole diameter of the hole is reduced as shown in FIG. 3B, the contrast due to the light modulator is reduced, and if the hole diameter of the hole is increased as shown in FIG. 3C, the contrast due to the light modulator is increased. Become. Thus, the contrast of the optical modulator can be easily changed by changing the hole diameter of the hole.

  In the case shown in FIG. 3D, the density of the holes 20c formed in the support layer is increased, and in the case shown in FIG. 3E, the density of the holes 20d formed in the support layer is reduced. doing. In this case, if the density of the holes formed in the support layer is large, the contrast of the liquid crystal light modulator increases, and if the density is small, the contrast decreases. The contrast of the liquid crystal light modulator can be adjusted also by the density of the holes formed in this way.

  In the case of the present embodiment, the support layer 19 is formed by forming a hole in a flat organic material made of, for example, a resin material. Therefore, it is easy to change the hole diameter of the holes and the density of the holes to be formed as described above, and there is an effect that the contrast of the liquid crystal light modulator can be easily changed. Moreover, the cross-sectional shape of the hole is not limited to a circle, and can be variously formed such as an ellipse, a triangle, a quadrangle, a rectangle, a polygon, or a shape obtained by combining these shapes.

  The liquid crystal light modulator 10 including the support layer 19 can be manufactured as follows.

  First, the hole 20 is formed in the flat organic material made of, for example, a resin material by, for example, laser irradiation to form the support layer 19. The hole 20 can be formed by various methods other than laser irradiation. For example, a photoresist is applied, and the photoresist is patterned by a photolithography method. It is also possible to form the hole 20 by performing dry etching, wet etching with a chemical solution, or the like using the formed photoresist as a mask. It is also possible to form the hole 20 by machining.

  Next, the liquid crystal 18 is permeated into the hole 20 of the support layer 19 so that the liquid crystal 18 is filled in the hole 20.

  Next, the first substrate 11 on which the first electrode 12 is formed is disposed on one surface of the support layer 19 into which the liquid crystal 18 has penetrated, and is opposite to the surface on which the first substrate 11 is disposed. The second substrate 13 on which the second electrode 14 is formed is installed on the side, and the support layer 19 is sandwiched between the first substrate 11 and the second substrate 13 so that the two substrates The liquid crystal light modulator 10 is formed by sealing the gap.

  Conventionally, as a method of forming a support portion for supporting a substrate, a mixed solution in which a raw material of a synthetic resin (monomer, oligomer, etc.) is dissolved in liquid crystal is injected between two opposing substrates, and the light of the raw material is injected. A method has been proposed in which a synthetic resin and a liquid crystal are separated by a polymerization reaction or a thermal polymerization reaction, and a support portion for supporting the substrate, for example, in a rib shape or a column shape, is formed between opposing substrates.

  However, when the support part for supporting the substrate is formed by polymerizing the above synthetic resin raw materials, liquid crystal is mixed into the resin, so that the mechanical strength of the formed support part is lowered. In addition, since the raw material of unreacted synthetic resin remains in the liquid crystal, there has been a problem that the light modulation function of the liquid crystal deteriorates.

  In addition, when forming a rib-like or columnar support using a polymerization reaction, for example, the shape and size vary in the liquid crystal, and it is difficult to control the shape particularly in the depth direction. It was difficult to uniformly form the shape of the support portion or the mechanical strength of the support portion.

  In this embodiment, it is possible to solve the above-described problem and to configure a liquid crystal light modulator having a support layer that has good mechanical strength and has uniform mechanical strength in the plane of the substrate to be supported. ing. In this example, since the polymerization reaction as described above is not used, liquid crystal is not mixed in the support layer, and it is possible to form a support layer having excellent mechanical strength. Further, since no unreacted resin material remains in the liquid crystal, the liquid crystal according to this embodiment has a good light modulation function without deterioration of the light modulation function of the liquid crystal.

  In addition, the support layer according to this embodiment has a feature that it is easy to form the shape uniformly in the plane of the substrate, and the mechanical strength can be easily made uniform in the plane. In addition, even when stress is applied to the liquid crystal light modulator by the support layer formed so as to extend between the first substrate and the second substrate, the distance between the first substrate and the second substrate is reduced. It is possible to hold the substrate substantially constant in the plane of the substrate. In addition, as compared with the conventional spacers that are diffused and distributed in the liquid crystal, it is advantageous in uniformly supporting the substrate surface.

  In addition, when forming a support portion using a polymerization reaction, it is necessary to increase the content of the polymer in the synthetic resin, which increases the alignment regulating force of the liquid crystal on the surface of the support portion, There was a problem that the drive voltage increased, but in the case of the present embodiment, since there is no such restriction, it is possible to arbitrarily select an organic material that constitutes the support layer, and the support layer has a liquid crystal drive power, etc. Can be avoided.

  In addition, as the liquid crystal 18 used in this embodiment, various liquid crystals can be used. For example, nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, polymer liquid crystal, and the like can be used. Even when used, the effects described in the above embodiments can be obtained.

  In order to obtain a high-speed response, for example, a low-viscosity and high-elasticity liquid crystal material is suitable. Biphenyl, terphenyl, pyrimidine, tolan, and fluorine nematic liquid crystals are suitable. When a smectic liquid crystal is used, a ferroelectric liquid crystal having spontaneous polarization and high-speed response is useful. For example, Schiff base ferroelectric liquid crystal, azo ferroelectric liquid crystal, azoxy ferroelectric liquid crystal, biphenyl ferroelectric liquid crystal, ester ferroelectric liquid crystal, or phenylpyrimidine ferroelectric liquid crystal is preferable.

  It is also possible to add fine fibrous polymers so as to be dispersed in the liquid crystal 18. As a method for forming the fibrous polymer, for example, the hole 20 may be filled with a liquid crystal / monomer mixed solution, and then formed by a polymerization separation method by ultraviolet irradiation or heating. In this case, the switching characteristics of the liquid crystal can be freely changed. For example, the response speed can be improved, and the control threshold voltage of memory characteristics and analog gradation characteristics can be adjusted.

  It is also possible to add a small amount of chiral material to the liquid crystal 18 to twist the alignment of the liquid crystal.

  The modulation method of the liquid crystal light modulator 10 includes a dynamic scattering effect utilization type (DS mode), a field effect refraction type (ECB type), a twisted nematic type (TN mode, STN mode), and a ferroelectric type (FLC). The operation modes used in conventional liquid crystal light modulators such as a type, a guest host type (GH type), a phase transition type (cholesteric type), and a polymer dispersion type (PDLC type) can be used.

  In addition, the liquid crystal light modulator 10 can be used with various modifications as required depending on the operation mode used, the type of liquid crystal, and the like. In this case, the same effect as described in this embodiment can be obtained. Play. A modification of such a liquid crystal light modulator is shown below.

  FIG. 4 is a schematic cross-sectional view schematically showing a liquid crystal light modulator 10A according to the second embodiment of the present invention. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted.

  Referring to FIG. 4, in this embodiment, an alignment film 22 and an alignment film 24 are formed on the first electrode 12 and the second electrode 14 on the side facing the liquid crystal, respectively. Therefore, the alignment of the liquid crystal 18 can be controlled.

Further, in order to insulate the first electrode 12 and the second electrode 14, transparent between the first electrode 12 and the alignment film 22 or between the second electrode 14 and the alignment film 24. An organic insulating film or an inorganic insulating film (for example, SiO ₂ or TiO ₂ ) may be provided.

  The first substrate 11 and the second substrate 13 may be provided with a polarizing plate 32 and a polarizing plate 34, respectively. For example, in the operation mode in which the birefringence is changed by controlling the orientation of the liquid crystal, Use of a polarizing plate is suitable for light modulation.

  On the other hand, when light modulation is performed using light scattering of the liquid crystal layer, it is preferable to align the liquid crystals randomly.

  FIG. 5 is a schematic cross-sectional view schematically showing a liquid crystal light modulator 10B according to Embodiment 3 of the present invention. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted.

  Referring to FIG. 5, in the case of the present embodiment, a first electrode 12 </ b> A made of a material that reflects incident light L <b> 1 is formed on the first substrate 11. For this reason, the liquid crystal light modulator 10B according to the present embodiment is a reflective liquid crystal light modulator. Therefore, the incident light L1 is modulated and reflected as reflected light L3 toward the side on which the incident light L1 is incident.

  The first electrode 12A can be formed of a metal material such as Al. In this case, the first substrate 11 does not necessarily need to be transparent. Moreover, you may provide such a reflecting plate separately from an electrode.

  In addition, it is possible to operate in a transflective liquid crystal mode by partially providing a reflector in the plane of the liquid crystal light modulator.

  The liquid crystal optical modulators described in the first to third embodiments can be used for optical communication devices such as various optical communication switching circuits. For example, the liquid crystal optical modulator is preferably used for a liquid crystal display device. In this case, in addition to the effects described in the first to third embodiments, a liquid crystal display device having good display quality and good flexibility and capable of handling bending such as folding and rounding is formed. It becomes possible.

  When the liquid crystal light modulators of the first to third embodiments are used in a liquid crystal display device, for example, the shape or pattern of the first electrode 12 or the second electrode 14 is arbitrarily changed as necessary to display It is sufficient to configure a pixel for use.

  In this case, a high-speed and high-contrast liquid crystal display device can be configured by providing a backlight on either the first substrate 11 side or the second substrate 13 side.

  Furthermore, it is not limited to the case described in Examples 1 to 3, and within the scope described in the claims, the substrate, the electrode, the reflective film, the alignment film, etc. may be variously modified and changed as necessary. Is possible.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the liquid crystal light modulator which is excellent in a softness | flexibility and intensity | strength, and a favorable light modulation function, and a liquid crystal display device using the said liquid crystal light modulator.

1 is a schematic cross-sectional view of a liquid crystal light modulator according to Example 1. FIG. It is a perspective view of the support layer which supports the board | substrate of the liquid crystal light modulator of FIG. (A)-(D) are top views which show the example of the state in which the hole was formed in the support layer of FIG. 6 is a schematic cross-sectional view of a liquid crystal light modulator according to Embodiment 2. FIG. 6 is a schematic cross-sectional view of a liquid crystal light modulator according to Embodiment 3. FIG.

Explanation of symbols

10, 10A, 10B Liquid crystal light modulator 11 First substrate 12, 12A First electrode 13 Second substrate 14 Second electrode 15, 16 Wiring 17 Power supply 18 Liquid crystal 19 Support layer 20, 20a, 20b, 20c, 20d Hole 22, 24 Alignment film 32, 34 Polarizing plate M Intermediate layer L1 Incoming light L2 Outgoing light L3 Reflected light D1 Thickness d1 Hole diameter

Claims (7)

A first substrate on which a first electrode is formed;
A second substrate on which a second electrode is formed;
A maintaining unit for maintaining a distance between the first substrate and the second substrate;
A liquid crystal light modulator comprising: a liquid crystal held between the first substrate and the second substrate,
The maintenance part is composed of a support layer made of an organic material formed between the first substrate and the second substrate, and the support layer has a plurality of holes filled with the liquid crystal. A liquid crystal light modulator characterized by that.   The liquid crystal light modulator according to claim 1, wherein the first substrate and the second substrate are made of an organic material.   The liquid crystal light modulator according to claim 1, wherein the support layer has a thickness of 0.5 μm to 10 μm.   The ratio of the thickness of the said support layer with respect to the hole diameter of the said hole is 0.01-100, The liquid crystal light modulator of any one of Claims 1 thru | or 3 characterized by the above-mentioned.   5. The liquid crystal light modulator according to claim 1, wherein a fibrous polymer material is added to the liquid crystal.   The liquid crystal light modulator according to claim 1, wherein the liquid crystal includes any one of a nematic liquid crystal, a cholesteric liquid crystal, and a smectic liquid crystal.   A liquid crystal display device using the liquid crystal light modulator according to claim 1.

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