JPH03208015A - Liquid crystal optical modulator - Google Patents

Abstract

PURPOSE:To obtain the optical modulator with high speed responsiveness, high contrast and high luminance by dispersing a two-frequency driving liquid crystal in minute drops in a transparent polymer, and driving it by switching voltages of two kinds of frequencies. CONSTITUTION:A two-frequency driving nematic liquid crystal converted into a microcapsule of spherical minute drops is dispersed in a polymer 2 of a transparent acryl compound resin, etc., and the polymer 2 is placed by placing it between glass substrates 4 on which a transparent electrode film 3 is formed. When a high frequency power source 7 is connected to this transparent electrode 3 through a switch 6, liquid crystal molecules have negative dielectric constant anisotropy and are arranged in parallel to the transparent electrode 3, scattered light 11 is generated and an incident light 9 comes to a non-transmission state. On the other hand, when a low frequency power source 8 is connected to the electrode 3, the molecules come to vertical to the electrode surface and the light comes into a transmission state. In such a way, since the molecule orientation is controlled forcibly by a voltage, the modulator of a high speed and high contrast is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention relates to a liquid crystal light modulator that modulates light intensity using a liquid crystal, and is particularly used in displays and stereoscopic vision that require high-speed response and high contrast characteristics. The present invention relates to a liquid crystal light modulator (including a liquid crystal light shutter) that can be applied to eyeglasses, light control glasses, shutters for optical printers, and the like.

[Summary of the Invention] The present invention provides a liquid crystal light modulator that can modulate light intensity by transmitting or scattering incident light depending on a driving voltage (applied voltage). By adopting an inverting dual-frequency driving liquid crystal, dispersing this liquid crystal in a transparent polymer, and switching between two different frequency driving voltages, it is possible to achieve faster response and improved contrast ratio. This makes it possible to apply liquid crystal light modulators to devices that require high-speed response and high contrast, such as displays, stereoscopic glasses, light control glasses, and shutters for optical printers.

[Prior Art] An optical modulator can be realized by applying the electro-optic effect of liquid crystals, which involves applying a voltage to a liquid crystal cell to change the arrangement state of liquid crystal molecules. In particular, liquid crystal elements have attracted attention in recent years because they operate at lower voltages than other crystals that exhibit electro-optic effects, and can be manufactured inexpensively with relatively large areas.

As one such liquid crystal light modulator, a conventional liquid crystal light modulator made of a liquid crystal dispersion type polymer includes the elements described below.

(1) As shown in Figure 7, a phenylcyclohexane-based nematic liquid crystal l3 with positive dielectric constant anisotropy is
An element that is filled in a continuous manner in a membrane filter-like cellulose ester polymer 2 between transparent electrodes 3, and whose light transmittance is controlled by application of an AC driving voltage from a driving AC voltage source 14.

(Reference: H. Craighead J. Cheng
andS. Hackwood, Appl. Phy
s. Lett. Vol. 40, No. l, p. 22-
(See p. 24, 1982).

(2) As shown in FIG. 8, microdroplets of cyanobiphenyl nematic liquid crystal 13 having positive dielectric constant anisotropy are spherical or Elements that are dispersed in an ellipsoidal shape and whose light transmittance is controlled by application of an AC driving voltage from a driving AC voltage source l4.

(Reference: J. Ferguson, Society
for Information-mation Displays
(SID) International Sym-p
Osium Digest of Technical
Papers. p. 68-p. 70, 1985, or J. W. Doane, N-A. VaZ, B. G.
Wu and S. Zumer%Appl. Phys.
Lett. Vol. 48, No. 4, p. 269-p.
271, 1986).

Further, in order to improve the responsiveness of the electro-optic effect in a nematic liquid crystal cell, a liquid crystal optical modulator using a two-frequency driving method that utilizes the dielectric dispersion characteristics of liquid crystal has been proposed. This is a nematic liquid crystal (hereinafter referred to as dual-frequency drive nematic liquid crystal) that exhibits dielectric dispersion characteristics such that when the frequency of the applied voltage becomes higher than a certain frequency fc, the dielectric anisotropy is reversed and the alignment direction of the liquid crystal changes. By sandwiching it between transparent electrodes and changing the frequency of the applied voltage, homeotropic alignment (vertical alignment) and twisted nematic alignment (
This enables high-speed switching between states (twisted orientation). As such two-frequency driven nematic liquid crystals, compensation liquid crystals made of a mixture of cholesteryl chloride (CC) and cholesteryl laurate (CL), phenyl ester of penzoyloxybenzoic acid, and the like are known. (Literature:
C. S. Bak, K. Ko and M. M. Lab
es. J. Appl. Phys1Vol. 46, No.
1, p. 1-p4, 1975).

[Problem to be solved by the invention 1 However, the above (1) using the above-mentioned liquid crystal dispersed polymer
Conventional elements 1) and (2) have different shapes of dispersed nematic liquid crystals, but in both cases the modulation of light transmittance is controlled by utilizing the light scattering phenomenon that occurs at the interface between the liquid crystal and the polymer. They had two common problems as described below.

■ When an AC driving voltage is applied, the voltage exerts a strong torque on the liquid crystal molecules, causing a rapid transition from an opaque state to a transparent state. On the other hand, when the driving voltage is removed, the transparent state changes to an opaque state. The transition to this state is slow due to the elastic force (interfacial effect) of the liquid crystal that attempts to return to its initial orientation. That is, it has a drawback that the fall time is longer than the rise time. Conventionally, in order to speed up the falling motion, there is a method of reducing the effective size of liquid crystal grains (liquid crystal microdroplets), but when using this method, the liquid crystal molecules are affected by the elasticity of the liquid crystal itself. Because it is strongly constrained by force, the voltage amplitude required to drive the element increases.
Also, when the liquid crystal microdroplets become smaller than the wavelength of the incident light,
Problems also arise, such as light being easily transmitted through the microdroplets without being scattered, and the contrast ratio of the device being degraded.

■ In a state where no driving voltage is applied (non-transparent state), the orientation of liquid crystal molecules within each liquid crystal microdroplet is in a random direction for each microdroplet, and among these, the alignment direction perpendicular to the transparent electrode In a microdroplet with a large diameter, the incident light is transmitted without being scattered. Therefore, since not all the microdroplets contribute to scattering, the light transmittance in the non-transparent state is high, resulting in a disadvantage that the contrast ratio is low. Conventionally, there is a method of increasing the contrast ratio by increasing the overall amount of scattering by increasing the thickness of the element, but with this method, problems arise such as an increase in driving voltage and deterioration of resolution as the thickness increases.

On the other hand, the conventional liquid crystal optical modulator using a two-frequency drive nematic liquid crystal as described above uses a liquid crystal cell with a structure in which the two-frequency drive nematic liquid crystal is directly housed between transparent electrodes using a spacer. When returning to the twisted nematic alignment by switching the driving frequency, all liquid crystal molecules are aligned horizontally to the electric field, but not necessarily in a perfect twisted alignment.Therefore, although the response characteristics can be improved, the high contrast ratio is different from that of other conventional liquid crystal molecules. Similar to the liquid crystal light modulator, it was not obtained.

In addition, conventional liquid crystal optical modulators using dual-frequency driven nematic liquid crystals require polarizing plates before and after the liquid crystal cell to utilize electro-optic effects such as changes in the direction of optical rotation (twisted nematic effect). The disadvantages are that the utilization efficiency of light is low and the brightness of transmitted light is low. Furthermore, in conventional liquid crystal light modulators using dual-frequency drive nematic liquid crystals, liquid crystal must be sealed, making it difficult to maintain a uniform gap between liquid crystal cells, making it extremely difficult to manufacture large-area liquid crystal cells. Met.

Therefore, the present invention has been made in view of the above points, and
The purpose is to provide a liquid crystal optical modulator that can provide high contrast and brightness as well as high-speed response, and can be made to have a large area.

[Means for Solving the Problems 1] In order to achieve the above object, the present invention provides a composite consisting of a two-frequency driven liquid crystal whose dielectric anisotropy is reversed by switching the driving frequency and a transparent polymer; transparent electrodes sandwiching the composite, and a frequency ft. lower than the crossover frequency fc of the liquid crystal. an alternating current voltage source that generates an alternating voltage with a frequency fH higher than the crossover frequency fc of the liquid crystal; an alternating voltage source with the low frequency fL for controlling the transmission state of light incident on the composite; The high frequency f. and switching means for switching the alternating current voltage and applying it to the transparent electrode.

Further, in one embodiment of the present invention, the two-frequency driven liquid crystal uses any one of a nematic liquid crystal, a cholesteric liquid crystal, and a smectic liquid crystal.

Further, in another aspect of the present invention, the polymer has a refractive index that is any one of an ordinary refractive index of the liquid crystal, an extraordinary refractive index of the liquid crystal, or a refractive index when the liquid crystal is randomly oriented. It is characterized by having a refractive index equivalent to .

In another aspect of the present invention, a dichroic dye is added to the two-frequency driven liquid crystal.

In another aspect of the present invention, the switching means controls the transmission state of the light depending on whether or not a voltage is applied using a zero-voltage contact.

Further, in another aspect of the present invention, the frequencies fL, f. The present invention is characterized in that it has a drive voltage adjusting means for controlling the response speed and contrast ratio of optical modulation by adjusting at least one of the value of , and the value of its amplitude.

[Function 1] In the present invention, by dispersing the two-frequency driving liquid crystal in a transparent polymer in the form of microdroplets or in a continuous state as in the above structure, and applying driving voltages of two different frequencies while switching, Since the liquid crystal molecules inside the microdroplet are driven strongly by voltage rather than by the elastic force of the liquid crystal itself, the falling motion can be improved without increasing the amplitude of the drive voltage or decreasing the contrato ratio due to miniaturization of the microdroplet. You can get faster speeds. Furthermore, in the present invention, in the non-light transmitting state, the alignment direction of liquid crystal molecules in all microdroplets is forcibly controlled by voltage to increase the amount of scattering. The contrast ratio can be improved by reducing the light transmittance in the non-light transmitting state, without increasing the contrast ratio or decreasing the resolution.

As a result, according to the present invention, a high-speed, high-contrast liquid crystal light modulator (including an optical shutter) can be realized.

That is, in the present invention, the two-frequency drive liquid crystal is dispersed in a transparent polymer and the light scattering effect is used. Therefore, when a non-transparent state is achieved by applying a drive voltage, the liquid crystal molecules are dispersed in the conventional two-frequency drive nematic liquid crystal. Unlike elements using
It is not necessary to align in a specific direction, and a sufficient scattering effect can be obtained as long as the direction is horizontal to the electric field. Therefore, not only a faster response but also an improvement in the contrast ratio can be obtained at the same time, and when the structure of the liquid crystal cell of the present invention is used, the characteristics of the two-frequency driven liquid crystal can be efficiently utilized. Furthermore, since the present invention does not require a polarizing plate, the light utilization efficiency is high, and since scattering development is used and no light is absorbed, it does not generate heat and has excellent light resistance. Furthermore, since the above-mentioned polymer has self-retaining properties, it is easy to control the gap between the transparent electrodes, and it is possible to construct a large-area liquid crystal light modulator with excellent uniformity.

[Example 1] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 of FIG. 1 shows a schematic configuration of an embodiment of a liquid crystal optical modulator to which the present invention is applied. In the liquid crystal light modulator of this embodiment, a two-frequency driving nematic liquid crystal 1 microencapsulated in the form of spherical microdroplets is dispersed in a transparent polymer 2 such as a transparent acrylic resin, and is adhered to a glass substrate 4. The polymer 2 is sandwiched between two transparent electrode films 3. 2 more
The two transparent electrode films 3 are connected to a high-frequency driving AC voltage source 7 or a low-frequency driving AC voltage source 8 via lead wires 5 and switches 6 . Incident light 9 entering from one glass substrate 4 is subjected to intensity modulation by this element consisting of an active crystal 1 and a polymer 2, resulting in transmitted light, that is, output light 1O, and scattered light 1.
It becomes l. In addition, when the polymer 2 is soft, a spacer (not shown) may be provided between the transparent electrode films 3 to support the side surface of the polymer 2.

A composite consisting of a dual-frequency driven nematic liquid crystal and a polymer is produced by mixing the constituent materials of the liquid crystal and the polymer to form a homogeneous solvent, and then processing this by photocuring, heat curing, reaction curing, etc. to form a monomer. It can be obtained by polymerizing and precipitating liquid crystals. Alternatively, it can also be obtained by mixing and stirring a polymer material insoluble in the liquid crystal, a solvent, and the liquid crystal to create a cloudy emulsion, and then curing the polymer by removing the solvent. Furthermore, it can also be obtained by mixing a molten polymer and liquid crystal with heat, separating the liquid crystal (phase separation) by utilizing the assimilation of the polymer during cooling, and dispersing the liquid crystal within the polymer. It will be done.

Further, the shape of the liquid crystal dispersed in the polymer depends on the mixing ratio of the liquid crystal and the polymer and the presence or absence of stress applied during the formation of the polymer, and becomes a spherical, ellipsoidal, or amorphous communicating state. Furthermore, when the volume ratio of the liquid crystal is increased compared to the polymer, it is also possible to form a network-like polymer in the liquid crystal.

The effective size of the above-mentioned liquid crystal microdroplets becomes smaller as the curing speed of the polymer increases;
It has been found through experiments that a diameter on the order of μm is practical. Further, the film thickness of the above-mentioned composite is suitably about IO μm to 30 μm.

As shown in FIG. 2, the dielectric anisotropy Δε (=ε7−ε.) of the two-frequency drive nematic liquid crystal 1 used in the optical modulator of this embodiment has a positive value when the applied voltage is in the low frequency region. However, in the high frequency range, it reverses and becomes a negative value. The frequency at which the dielectric constant anisotropy Δε becomes zero is the crossover frequency f
It is called c. From this characteristic, the liquid crystal molecules have a crossover frequency fc? When a voltage of a low frequency fL is applied, the third direction is oriented parallel to the direction of the electric field (that is, perpendicular to the transparent electrode surface) as shown in FIG. 4, and when a voltage of a frequency fH higher than the crossover frequency fc is applied, As shown in the figure, the liquid crystal molecules are aligned perpendicular to the direction of the electric field (that is, parallel to the transparent electrode surface). At this time, the larger the absolute value of the dielectric anisotropy Δε, the greater the torque applied to the liquid crystal molecules, which is advantageous because the response becomes faster.

For example, the two-frequency drive nematic liquid crystal used in this example has a frequency dependence of dielectric constant anisotropy Δε as shown in FIG. 2, and the crossover frequency fc of the liquid crystal is
It is approximately 1kHz.

Furthermore, the refractive index np of the polymer 2 has a value equivalent to either the ordinary refractive index n0, the extraordinary refractive index n■, or the refractive index n when the liquid crystal 1 is randomly oriented. . Here, the refractive index nr is calculated from the following equation (1).

nr=(2n0+n.)/3...(l) Among these, the case where the refractive index n2 of the polymer 2 is made to match the ordinary refractive index n0 of the liquid crystal 1 has the highest contrast ratio and the best performance.

The light scattering phenomenon, which is the modulation principle of the optical modulator of this embodiment, is based on the three types of refractive index of the liquid crystal 1 (namely, the ordinary refractive index n0 of the liquid crystal 1, the extraordinary refractive index n6, and the random orientation of the liquid crystal 1). This is caused by the difference between the refractive index nr) of the polymer 2 and the refractive index np of the polymer 2, so it is advantageous for the refractive index anisotropy Δn (=ns-nO) of the liquid crystal l to be as large as possible. be.

1 of Next, the operation of the optical modulator of this example will be explained.

Note that since the light modulation operation of this optical modulator is polarization independent, it is possible to use unpolarized white light or visible light of any wavelength as the incident light 9.

First, the operating state during high frequency driving will be explained. 1st
The switch 6 in the figure is replaced by a high frequency power source 7 as shown in FIG.
(driving frequency f.), the liquid crystal molecules 1 have negative dielectric constant anisotropy (see Figure 2), and the liquid crystal molecules in all microdroplets are perpendicular to the applied electric field (i.e., the transparent electrode 3
parallel to the plane). At this time, the incident light 9 senses only the extraordinary light refractive index n# of the liquid crystal 1.

Here, the refractive index of the polymer 2 is n. is the ordinary refractive index n0 of the liquid crystal
If the refractive index n. of the polymer 2 matches, as shown in FIG. Due to the difference between the normal light refractive index and the extraordinary light refractive index n0, reflection and refraction occur at the interface of the microdroplets of the liquid crystal 1, and scattered light 1l is generated, and the device becomes cloudy and non-transparent.

On the other hand, the refractive index n of the polymer 2 is the extraordinary refractive index n of the liquid crystal l.
6, there is no discontinuity in the refractive index at the interface between the liquid crystal 1 and the polymer 2, so the light is not scattered but is transmitted as it is and becomes the output light, and the device is in a transparent transmission state. become.

Next, the operating state during low frequency driving will be shown. When the switch 6 in FIG. 1 is connected to the low frequency power source 8 (drive frequency fL) as shown in FIG. 4, the liquid crystal molecules 1 have positive dielectric constant anisotropy (see FIG. 2). , the liquid crystal molecules in all microdroplets are parallel to the applied electric field (i.e., perpendicular to the three planes of the transparent electrode)
Orient to.

At this time, the incident light 9 senses only the ordinary refractive index n0 of the liquid crystal 1.

Here, the refractive index of the polymer 2 is n. is the ordinary refractive index n of the liquid crystal l
0, as shown in Figure 4, the liquid crystal 1
Since there is no discontinuity in the refractive index at the interface between the polymer 2 and the polymer 2, the light is not scattered and the device is in a transmitting state.

On the other hand, the refractive index np of the polymer 2 is the extraordinary refractive index n of the liquid crystal 1.
．． If the difference between the refractive index n of the polymer 2 and the ordinary refractive index n0 causes reflection and refraction at the interface of the microdroplets of the liquid crystal 1, scattered light is generated, and the device becomes cloudy. becomes opaque.

As described above, the refractive index np of the polymer 2 is set to the ordinary refractive index of liquid crystal 0. When the cross-over frequency fc is made to match , and the device is switched and driven with a voltage having a frequency fH higher than the crossover frequency fc and a voltage fL lower than the crossover frequency fc, the present element becomes a light non-transmitting state and a light transmitting state, respectively.

On the other hand, the refractive index n of the polymer 2 is the extraordinary refractive index n of the liquid crystal 1,
If they match, the operation will be the opposite, resulting in a transparent state and an opaque state, respectively.

In either state, the liquid crystal molecules are forcibly oriented by the torque of the applied electric field, so the light transmittance of the device is switched at high speed.

Furthermore, since the torque acting on liquid crystal molecules is determined by the product of the dielectric anisotropy Δε and the voltage amplitude, the response speed and contrast ratio can be improved by changing the dielectric anisotropy Δε (that is, the driving frequency) and the amplitude of the driving voltage. It is also possible to control

A frequency modulation circuit, a variable amplification circuit, etc. for this purpose can be realized using general well-known techniques.

Furthermore, when the liquid crystal particles are randomly oriented, only 2/3 of the liquid crystal particles (aligned parallel to the substrate) contribute to scattering, whereas at high frequencies the drive efficiency is improved by about 1.5 times. . In this way, it has become possible to obtain a higher contrast ratio than conventional elements by increasing the amount of scattering by liquid crystal microdroplets in an opaque state, which allows the element to be made thinner to that extent. This element is also effective in reducing driving voltage and increasing resolution.

In addition, as shown in FIG. 5, the switch 6 in FIG. 1 is connected to the zero voltage contact C, and, for example, a driving voltage of a frequency fL lower than the crossover frequency fc is turned on (ON) and turned off (
OFF), it is also possible to control the light transmission state of this element in three stages. As shown in FIG. 5, when no driving voltage is applied between the transparent electrodes 3, the liquid crystal molecules 1 within the liquid crystal microdroplets are randomly oriented for each microdroplet.

Here, if the refractive index np of the polymer matches the ordinary refractive index n0 of the liquid crystal, as shown in FIG. However, in microdroplets with other orientation directions, a discontinuity between the refractive index of the liquid crystal material and the refractive index n2 of the polymer 2 is felt, and the scattered light 1
1 and becomes opaque. In this state, not all the liquid crystal microdroplets contribute to the scattering effect, so the amount of scattered light 1l is smaller than during the high frequency drive described above, and therefore a portion of the incident light is transmitted, resulting in a low contrast ratio. Therefore, three types of transmission states can be selectively obtained by switching the frequency of the applied voltage and by not applying any voltage. Note that the switching from the transparent state to the non-transparent state when no voltage is applied occurs due to the elastic force of the liquid crystal, so the response is slower than in the above-mentioned two-frequency drive.

Similarly, a frequency fL lower than the crossover frequency fe
The driving voltage is turned on and off, and the refractive index n of the polymer 2 is
When p is made to match the refractive index nr of the liquid crystal 1 at the time of random arrangement, the operation is opposite to the above case, and the state becomes opaque when a voltage is applied, and becomes a transmissive state when no voltage is applied.

Furthermore, if the refractive index np of the polymer matches the ordinary refractive index n0 of the liquid crystal, as shown in FIG. 6, the liquid crystal 1 has absorption anisotropy. By adding the dichroic dye 12, it is also possible to realize a black opaque state in which the contrast is further increased from a cloudy state in the opaque state during high-frequency driving.

Its operation is as follows. That is, when dichroic dye l2 is added to liquid crystal microdroplets and driven at high frequency by f+, the molecules of dichroic dye l2 follow liquid crystal molecules 1 and move in the direction of the electric field, as shown in FIG. Because the dichroic dye l
The long axis direction of the absorption anisotropy of No. 2 coincides with the polarization direction of the incident light 9. Therefore, this dichroic dye 12 has a large absorption rate for the incident light 9, and the light is attenuated within the device and does not leak to the output side. Therefore, in this case, the element is in a black non-transparent state.

In addition, as the above-mentioned polymer (bolima) 2, for example, polyvinyl alcohol, chlorinated polypropylene, epoxy resin, acrylic resin, etc. can be used. Further, as the above-mentioned two-frequency drive nematic liquid crystal 1, for example, a known ester compound having three or more rings containing a cyano group or a halogen can be used.

Furthermore, it is also possible to use cholesteric phase liquid crystal (i.e., cholesteric liquid crystal) or smectic phase liquid crystal (i.e., smectic liquid crystal) whose dielectric constant anisotropy is reversed depending on the driving frequency, similar to the two-frequency drive nematic liquid crystal. These phase liquid crystals have high viscosity and are disadvantageous in terms of response speed compared to nematic liquid crystals.

[Effects of the Invention 1] As explained above, according to the present invention, two-frequency driven liquid crystals are dispersed in a transparent polymer in the form of microdroplets or in a continuous state,
Furthermore, by switching between voltages at two different frequencies, the orientation of the liquid crystal molecules within the microdroplets in the transparent state and non-transparent state can be forcibly controlled by the voltage, which enables high-speed, high-contrast liquid crystal display. A light modulator can be provided.

Therefore, the liquid crystal light modulator of the present invention can be suitably applied to displays, stereoscopic glasses, light control glasses, shutters for optical printers, etc., and when the present invention is used, the performance of these devices can be improved. can be expected.

In addition, compared to conventional dual-frequency drive liquid crystal shutters, the present invention has a high light utilization efficiency (approximately 80% or more) because it does not require a polarizing plate, and does not absorb light using a scattering phenomenon. It has advantages such as no heat and excellent light resistance.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of a liquid crystal optical modulator to which the present invention is applied, Fig. 2 is a characteristic diagram showing the frequency dependence of dielectric constant anisotropy of a two-frequency driven nematic liquid crystal, and Fig. 3 is FIG. 1 is a state diagram showing the operating state of the optical modulator shown in FIG. 1 when driven at high frequency. FIG. 4 is a state diagram showing the operating state of the optical modulator shown in FIG. 1 when driven at low frequency. is a state diagram showing the operating state of the optical modulator shown in Fig. 1 when the driving voltage is removed, and Fig. 6 is a state diagram showing the state of operation when the driving voltage of the optical modulator shown in Fig. 1 is removed. FIG. 7 and FIG. 8 are block diagrams showing the structure of a conventional liquid crystal optical modulator, respectively. DESCRIPTION OF SYMBOLS 1...2-frequency driven nematic liquid crystal, 2...Polymer, 3...Transparent electrode film, 4...Glass substrate, 5...Lead wire, 6...Switch, 7...High frequency AC voltage source for driving 8... Low frequency AC voltage source for driving, 9... Incident light, lO... Outgoing light, 11... Scattered light, 12... Dichroic dye, l3...Nematic liquid crystal with positive dielectric constant anisotropy, 14
... AC voltage source for driving. 1st page I: Figure 3 shows the behavior of Hikari Mugihoki during Takao-style dado.

Claims (1)

[Scope of Claims] 1) A composite consisting of a dual-frequency driven liquid crystal whose dielectric constant anisotropy is reversed by switching the driving frequency and a transparent polymer, transparent electrodes sandwiching the composite, and a crossover of the liquid crystal. AC voltage of frequency f_L lower than frequency f_c, crossover frequency f_ of the liquid crystal
an alternating current voltage source that generates an alternating current voltage with a frequency f_H higher than c;
a switching means for switching an alternating current voltage and applying the alternating current voltage to the transparent electrode. 2) The liquid crystal optical modulator according to claim 1, wherein the two-frequency driven liquid crystal uses one of a nematic liquid crystal, a cholesteric liquid crystal, and a smectic liquid crystal. 3) The polymer has a refractive index equivalent to any one of the ordinary refractive index of the liquid crystal, the extraordinary refractive index of the liquid crystal, or the refractive index when the liquid crystal is randomly oriented. The liquid crystal optical modulator according to claim 1 or 2. 4) The liquid crystal light modulator according to claim 1, wherein a dichroic dye is added to the two-frequency driven liquid crystal. 5) The liquid crystal optical modulator according to claim 1, wherein the switching means controls the transmission state of the light depending on whether or not a voltage is applied using a zero voltage contact. 6) It is characterized by having a driving voltage adjusting means for controlling the response speed and contrast ratio of light modulation by adjusting at least one of the values of the frequencies f_L and f_H of the alternating current voltage and the value of the amplitude thereof. Claim 1
6. The liquid crystal optical modulator according to items 5 to 5.