JP2002258326A - Ultrasonic liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize a display function by making liquid crystal which is made turbid with an elastic wave transparent by applying an electric field to the liquid crystal. SOLUTION: When a 1st electric signal is applied to a dispersion type interdigital electrodes 3, a frequency-modulated chirp type surface acoustic wave is excited in a piezoelectric substrate 2. This surface acoustic wave is propagated to the liquid crystal 8 by traveling on the upper end surface of a non-piezoelectric plate 1 to make the liquid crystal 8 turbid. When a 2nd electric signal is applied between a 1st transparent electrode 4 and a 2nd transparent electrode 5, the electric field is applied to the liquid crystal 8, which becomes transparent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal having a turbid state by inducing a dynamic scattering mode in a liquid crystal by a frequency-modulated chirp type surface acoustic wave, and applying an electric field to the turbid liquid crystal. The present invention relates to an ultrasonic liquid crystal display that realizes a display function by making the liquid crystal transparent by changing the liquid crystal.

[0002]

2. Description of the Related Art In order to increase the information processing capability of information terminals such as computers and mobile phones, it is essential to improve the functions of liquid crystal displays. Thin-film transistor driven displays, which are typical of conventional liquid crystal displays, are of high quality, but also need to be improved, for example, the power consumption of the light source accounts for 70-80% of the total power consumption. Many. In recent years, interest has been shifted to reflective displays instead of transmissive displays for the purpose of saving power. Typical examples of the reflection type display include a polymer dispersion type and a guest-host type. However, there are many problems with respect to miniaturization and weight reduction of the device, power saving, high accuracy, and long life. On the other hand, a dynamic scattering display, which is an early liquid crystal display, is practically poor.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to induce a dynamic scattering mode in a liquid crystal by a frequency-modulated chirped surface acoustic wave to bring the liquid crystal into a turbid state, and to apply an electric field to the turbid liquid crystal to apply the electric field to the liquid crystal. It is an object of the present invention to provide an ultrasonic liquid crystal display using a transparent material. Further, a further object of the present invention is to provide a precise image, have excellent visual field characteristics, hardly deteriorate the liquid crystal, enable low voltage and low power consumption self-oscillation driving, and have a simple circuit configuration. , Fast response speed, mass production possible, small size and light weight,
An object of the present invention is to provide an ultrasonic liquid crystal display which has excellent durability and does not necessarily require a light source and a polarizer.

[0004]

An ultrasonic liquid crystal display according to claim 1, wherein a transparent non-piezoelectric plate, a piezoelectric substrate provided on a first portion of an upper end surface of the non-piezoelectric plate, and the piezoelectric liquid crystal display. At least one distributed interdigital transducer provided on a substrate, a first transparent electrode provided on a second portion of the upper end surface of the non-piezoelectric plate, a transparent non-piezoelectric canopy plate, and the non-piezoelectric canopy An ultrasonic liquid crystal display comprising a second transparent electrode provided on a lower end surface of a plate and a liquid crystal sandwiched between the first and second transparent electrodes, wherein a first electric signal is applied to the dispersed interdigital transducer. Thereby, the frequency modulation chirp type surface acoustic wave is excited on the piezoelectric substrate, and the frequency modulation chirp type surface acoustic wave is propagated to the liquid crystal, whereby the liquid crystal becomes turbid, and the first and second liquid crystals become opaque. Second electricity between transparent electrodes By No. is applied, the liquid crystal becomes transparent electric field is applied to the liquid crystal.

[0005] In the ultrasonic liquid crystal display according to the second aspect, a light source is provided below the non-piezoelectric plate.

[0006] In the ultrasonic liquid crystal display according to the third aspect, a reflection plate is provided below the non-piezoelectric plate.

An ultrasonic liquid crystal display according to a fourth aspect is an ultrasonic liquid crystal display comprising at least two display devices, wherein the at least two display devices are stacked to form a laminated structure,
Each of the display devices is a transparent non-piezoelectric plate, a piezoelectric substrate provided on a first portion of an upper end surface of the non-piezoelectric plate, and at least one distributed interdigital transducer provided on the piezoelectric substrate, A first transparent electrode provided on a second portion of the upper end surface of the non-piezoelectric plate, a transparent non-piezoelectric canopy plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, A frequency-modulated chirp type surface acoustic wave is excited on the piezoelectric substrate by applying a first electric signal to the dispersion-type interdigital transducer, comprising a liquid crystal sandwiched between first and second transparent electrodes. When the modulated chirp type surface acoustic wave is propagated to the liquid crystal, the liquid crystal becomes turbid,
When a second electric signal is applied between the first and second transparent electrodes, an electric field is applied to the liquid crystal to make the liquid crystal transparent.

In the ultrasonic liquid crystal display according to the fifth aspect, the piezoelectric substrate is made of a piezoelectric ceramic plate, and the direction of the polarization axis of the piezoelectric ceramic plate is parallel to the thickness direction.

In the ultrasonic liquid crystal display according to the present invention, the thickness of the piezoelectric substrate is smaller than the minimum electrode cycle length of the dispersed interdigital transducer, and the thickness of the non-piezoelectric plate and the non-piezoelectric canopy plate. Is larger than twice the maximum electrode cycle length of the dispersed IDT.

[0010] In the ultrasonic liquid crystal display according to the present invention, the phase velocity of the frequency-modulated chirped surface acoustic wave propagating through the non-piezoelectric plate itself may be different from the phase velocity of the frequency-modulated chirped surface acoustic wave propagating through the piezoelectric substrate itself. Faster than speed.

In the ultrasonic liquid crystal display according to the present invention, another one of the non-piezoelectric plates may be provided on a third portion of the upper end face.
One piezoelectric substrate is provided, and the other piezoelectric substrate is provided with at least one input interdigital electrode having an electrode finger pattern opposite to the electrode finger pattern of the distributed interdigital electrode; A third electric signal is applied to the input IDT at the same time as the first electric signal is applied to the piezoelectric electrode, so that another frequency-modulated chirped surface acoustic wave is applied to the other piezoelectric substrate. Is excited, and the another frequency-modulated chirped surface acoustic wave is propagated to the liquid crystal, whereby the liquid crystal is further clouded.

In the ultrasonic liquid crystal display according to the ninth aspect, another one of the non-piezoelectric plates may be provided on a third portion of the upper end surface.
One piezoelectric substrate is provided, and the other piezoelectric substrate is provided with at least one output interdigital electrode having the same electrode finger pattern as the distributed interdigital electrode, and the distributed interdigital electrode is provided. And an amplifier connected between the output IDT and the output IDT.

The ultrasonic liquid crystal display according to claim 10, wherein the transparent piezoelectric substrate, at least one distributed interdigital transducer provided on a first portion of an upper end surface of the transparent piezoelectric substrate, and the transparent piezoelectric substrate. A first transparent electrode provided on a second portion of the upper end surface of the piezoelectric substrate, a transparent non-piezoelectric canopy plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, An ultrasonic liquid crystal display comprising a liquid crystal sandwiched between first and second transparent electrodes, wherein a first electric signal is applied to the dispersed interdigital electrode to thereby form a first electrode on the upper end surface of the piezoelectric substrate. A frequency-modulated chirped surface acoustic wave is excited in a portion of the piezoelectric substrate, and the frequency-modulated chirped surface acoustic wave is applied to the second end surface of the piezoelectric substrate.
Is propagated to the liquid crystal through the portion, and the liquid crystal is turbid, and the second liquid crystal is interposed between the first and second transparent electrodes.
When an electric signal is applied, an electric field is applied to the liquid crystal to make the liquid crystal transparent.

In the ultrasonic liquid crystal display according to the eleventh aspect, the first and second transparent electrodes are each formed of an aggregate of elongated sub-electrodes, and each of the aggregates of the sub-electrodes forms a stripe pattern. The stripe pattern of one transparent electrode and the stripe pattern of the second transparent electrode are orthogonal to each other, and are between at least one sub-electrode of the first transparent electrode and at least one sub-electrode of the second transparent electrode. When the second electric signal is applied, an electric field is applied to the liquid crystal in an intersection region between the sub-electrode of the first transparent electrode and the sub-electrode of the second transparent electrode, and the electric field is applied to the liquid crystal. The above liquid crystal becomes transparent.

In the ultrasonic liquid crystal display according to the twelfth aspect, the liquid crystal is a nematic liquid crystal.

In the ultrasonic liquid crystal display according to the thirteenth aspect, the liquid crystal has a homogeneous alignment before the frequency modulation chirp type surface acoustic wave is propagated.

In the ultrasonic liquid crystal display according to the present invention, the first and second polarizers and the color filter are provided.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The ultrasonic liquid crystal display of the present invention comprises a transparent non-piezoelectric plate, a piezoelectric substrate, at least one dispersed interdigital electrode, first and second transparent electrodes, a non-piezoelectric canopy plate and a liquid crystal. It has a simple structure. The dispersed interdigital transducer is provided on a piezoelectric substrate, and the piezoelectric substrate is provided on a first portion on the upper end surface of the non-piezoelectric plate. The first transparent electrode is provided on a second portion on the upper end surface of the non-piezoelectric plate. The second transparent electrode is provided on a lower end surface of the non-piezoelectric canopy plate. Liquid crystal is injected between the first and second transparent electrodes.

If the first electric signal is applied to the dispersed interdigital transducer, the frequency-modulated chirped surface acoustic wave is applied to the piezoelectric substrate because the dispersed interdigital transducer has a wide electrode cycle length. Excited. At this time, since the piezoelectric substrate is formed of a piezoelectric ceramic plate, and the direction of the polarization axis of the piezoelectric ceramic plate is parallel to the thickness direction, the frequency modulation chirp type surface acoustic wave is efficiently excited on the piezoelectric substrate. . If the phase velocity of the frequency-modulated chirped surface acoustic wave is substantially equal to the phase velocity of the Rayleigh wave of the surface-acoustic wave propagating through the non-piezoelectric plate itself, the first electric signal can be efficiently transmitted to the frequency-modulated chirped surface acoustic wave. Converted to waves. The frequency-modulated chirped surface acoustic wave propagates along the upper end surface of the non-piezoelectric plate through the liquid crystal portion without leaking into the non-piezoelectric plate. The reason that the frequency-modulated chirped surface acoustic wave does not leak into the non-piezoelectric plate is, first, that the thickness of the piezoelectric substrate is smaller than the minimum electrode period length of the dispersed IDT; The thickness of the plate is greater than twice the maximum electrode period length of the interdigital transducer;
This is because the phase velocity of the frequency-modulated chirped surface acoustic wave propagating in the non-piezoelectric plate itself is faster than the phase velocity of the frequency-modulated chirped surface acoustic wave propagating in the piezoelectric substrate itself. When the frequency-modulated chirped surface acoustic wave propagates through the liquid crystal portion, a dynamic scattering state is induced in the liquid crystal. Thus, the liquid crystal becomes turbid. When a second electric signal is applied between the first and second transparent electrodes when the liquid crystal is in a cloudy state, an electric field is applied to the liquid crystal, so that the orientation of the liquid crystal changes and the liquid crystal transmits light. , The liquid crystal becomes transparent.

In the ultrasonic liquid crystal display of the present invention, a structure in which a light source and a reflector are provided below a non-piezoelectric plate is possible. By employing a reflector, a reflective ultrasonic liquid crystal display can be configured. The reflective ultrasonic liquid crystal display can be driven with lower power consumption than a structure using a light source.

In the ultrasonic liquid crystal display of the present invention, a structure including the first and second polarizers and the color filter is possible. In this way, it is possible to configure an all-color ultrasonic liquid crystal display.

In the ultrasonic liquid crystal display of the present invention, a structure in which the liquid crystal is composed of a nematic liquid crystal is possible. Also,
A structure in which the liquid crystal before the frequency modulation chirp type surface acoustic wave is propagated forms a homogeneous alignment is possible.

In the ultrasonic liquid crystal display of the present invention, a structure in which the first and second transparent electrodes are each formed of an aggregate of elongated sub-electrodes is possible. At this time, each of the aggregates of the sub-electrodes forms a stripe pattern, and the stripe patterns of the first transparent electrode and the second transparent electrode are orthogonal to each other. That is, both form a matrix electrode. If the second electric signal is applied between at least one sub-electrode of the first transparent electrode and at least one sub-electrode of the second transparent electrode when the liquid crystal is in a cloudy state, the first and second electric signals are applied.
Since an electric field is applied to the liquid crystal in the cross region of each sub-electrode of the transparent electrode, the liquid crystal in the cross region becomes transparent.

In the ultrasonic liquid crystal display of the present invention, another piezoelectric substrate is provided on the third portion of the upper end surface of the non-piezoelectric plate, and at least one IDT electrode is provided on the other piezoelectric substrate. A configured structure is possible. The input interdigital transducer has an electrode finger pattern that is opposite to the electrode finger pattern of the distributed interdigital transducer provided in the first portion. When a third electric signal is applied to the input interdigital transducer at the same time as the first electric signal is applied to the dispersed interdigital transducer, a frequency-modulated chirp type surface acoustic wave is excited on the piezoelectric substrate in the first portion. At the same time, another frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate in the third portion. Since the two frequency-modulated chirped surface acoustic waves are simultaneously transmitted to the liquid crystal in this manner, the liquid crystal is further clouded.

In the ultrasonic liquid crystal display of the present invention, another piezoelectric substrate is provided on the third portion of the upper end surface of the non-piezoelectric plate, and at least one output IDT is provided on the other piezoelectric substrate. A structure is possible in which an amplifier is connected between the output IDT and the dispersed IDT. The output IDT has the same electrode finger pattern as that of the dispersed IDT provided in the first portion. The first type of interdigital electrode
When an electric signal is applied, a frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate in the first portion. The frequency-modulated chirped surface acoustic wave is propagated to the liquid crystal and is also propagated to the piezoelectric substrate in the third portion to be converted into a pulse signal. This pulse signal is again applied to the distributed IDT via the amplifier. In this way, a self-pulsation type ultrasonic liquid crystal display can be configured. Accordingly, the circuit configuration is simplified, the size and weight of the device are promoted, and low-voltage driving with low power consumption is possible.

In the ultrasonic liquid crystal display according to the present invention, a structure having a laminated structure in which at least two display devices are stacked is possible. Each display device includes a transparent non-piezoelectric plate, a piezoelectric substrate provided on a first portion of an upper end surface of the non-piezoelectric plate, at least one distributed interdigital transducer provided on the piezoelectric substrate, and a non-piezoelectric canopy plate. A first transparent electrode provided on a second portion of the upper end surface of the non-piezoelectric plate;
It comprises a second transparent electrode provided on the lower end surface of the non-piezoelectric canopy plate, and a liquid crystal sandwiched between the first and second transparent electrodes. By separately driving such display devices, it is possible to project a fluoroscopic image. Also, if three display devices corresponding to red, blue, and green are used, it is possible to display a full-color perspective image.

In the ultrasonic liquid crystal display according to the present invention, a transparent piezoelectric substrate, at least one interdigital transducer, a transparent non-piezoelectric canopy plate, first and second transparent electrodes, and first and second transparent electrodes are provided. A structure consisting of liquid crystal sandwiched between transparent electrodes is possible. In this structure, the dispersed IDT is provided on a first portion of the upper end surface of the piezoelectric substrate, and the first transparent electrode is provided on a second portion of the upper end surface of the piezoelectric substrate.
The second transparent electrode is provided on a lower end surface of the non-piezoelectric canopy plate. If the first electric signal is applied to the interdigital transducer, a frequency-modulated chirped surface acoustic wave is excited at the first portion of the upper end surface of the piezoelectric substrate. The frequency-modulated chirped surface acoustic wave propagates to the liquid crystal via the second portion on the upper end surface of the piezoelectric substrate, and the liquid crystal becomes turbid. When a second electric signal is applied between the first and second transparent electrodes while the liquid crystal is in a cloudy state, an electric field is applied to the liquid crystal to make the liquid crystal transparent.

[0028]

FIG. 1 is a sectional view showing a first embodiment of an ultrasonic liquid crystal display according to the present invention. This embodiment includes a non-piezoelectric plate 1, a piezoelectric substrate 2, a dispersed interdigital electrode 3, a first transparent electrode 4, a second transparent electrode 5, auxiliary plates 6 and 7, a liquid crystal 8, and a non-piezoelectric canopy plate 9. Auxiliary plates 6 and 7 are not depicted in FIG. The non-piezoelectric plate 1 and the non-piezoelectric canopy plate 9
Each is made of a transparent glass plate with a thickness of 1.1 mm. The phase velocity of the surface acoustic wave propagating on the non-piezoelectric plate 1 itself is higher than the phase velocity of the surface acoustic wave propagating on the piezoelectric substrate 2 itself. The piezoelectric substrate 2 is made of a 230 μm thick piezoelectric ceramic plate, and the direction of the polarization axis of the piezoelectric ceramic plate is parallel to the thickness direction. The piezoelectric substrate 2 is provided on a first portion on the upper end surface of the non-piezoelectric plate 1. The dispersed IDT 3 is made of an aluminum thin film and is provided on the piezoelectric substrate 2.
The liquid crystal 8 is composed of a nematic liquid crystal MBBA. The first transparent electrode 4 and the second transparent electrode 5 are made of an oxide of indium and tin. The first transparent electrode 4 is a second transparent electrode on the upper end surface of the non-piezoelectric plate 1.
Is deposited on the part. The second transparent electrode 5 is deposited on the lower end surface of the non-piezoelectric canopy plate 9. The liquid crystal 8 is injected into a space having a thickness of 6 μm between the first transparent electrode 4 and the second transparent electrode 5 after rubbing. At this time, the liquid crystal 8 has a homogeneous alignment. Thus, the non-piezoelectric plate 1, the first transparent electrode 4, the liquid crystal 8, the second transparent electrode 5, and the non-piezoelectric canopy plate 9 form a five-layer structure.

FIG. 2 is a partial plan view of the ultrasonic liquid crystal display of FIG. The dispersed IDT 3, the second transparent electrode 5, the liquid crystal 8, and the non-piezoelectric canopy plate 9 are not shown in FIG. The auxiliary plates 6 and 7 provided on the first transparent electrode 4 form a space having a thickness of 6 μm between the first transparent electrode 4 and the second transparent electrode 5 in FIG.

FIG. 3 is a plan view of the dispersed IDT 3. The dispersed IDT 3 has an electrode period length of 400 to 500 μm.

FIG. 4 is a partially enlarged plan view of the first transparent electrode 4. The first transparent electrode 4 is composed of an aggregate of elongated sub-electrodes,
The aggregate of the sub-electrodes forms a stripe pattern as a whole. The second transparent electrode 5 has the same structure as the first transparent electrode 4.
However, the stripe pattern of the first transparent electrode 4 and the stripe pattern of the second transparent electrode 5 are orthogonal to each other.

In the ultrasonic liquid crystal display of FIG.
If the first electric signal is applied to the interdigital transducer 3, since the interdigital transducer 3 has a wide electrode cycle length as shown in FIG. A surface acoustic wave is excited. This frequency-modulated chirped surface acoustic wave travels along the upper end surface of the non-piezoelectric plate 1 and is not leaked into the non-piezoelectric plate 1 without being leaked into the liquid crystal 8.
Is propagated to Thus, the liquid crystal 8 becomes cloudy. At this time, one of the sub-electrodes of the first transparent electrode 4 and one of the sub-electrodes of the second transparent electrode 5, for example, the third sub-electrode of the first transparent electrode 4 and the ninth sub-electrode of the second transparent electrode 5 When a second electric signal is applied between the electrodes, an electric field is applied to the liquid crystal 8 in a region where the third sub-electrode of the first transparent electrode 4 and the ninth sub-electrode of the second transparent electrode 5 intersect. . The electric field applied to the cross region makes the liquid crystal 8 in the cross region transparent. Similarly, if a second electric signal is applied between the fourth and sixth sub-electrodes of the first transparent electrode 4 and the ninth and eleventh sub-electrodes of the second transparent electrode 5, The liquid crystal 8 in four areas where the fourth and sixth sub-electrodes of the first transparent electrode 4 intersect with the ninth and eleventh sub-electrodes of the second transparent electrode 5 become transparent.

FIG. 5 is a characteristic diagram showing a velocity dispersion curve of a surface acoustic wave propagating in a two-layer structure of the non-piezoelectric plate 1 and the piezoelectric substrate 2. However, the fd value depends on the frequency f of the surface acoustic wave and the piezoelectric substrate 2
And the product of the thickness d. The broken line in FIG.
Represents the velocity of the shear wave propagating through itself. It can be seen that the phase velocity of the surface acoustic wave propagating in the two-layer structure is lower than the velocity of the transverse wave propagating in the non-piezoelectric plate 1 itself.

FIG. 6 is a characteristic diagram showing a velocity dispersion curve of an elastic wave propagating through a three-layer structure composed of the non-piezoelectric plate 1, the liquid crystal 8, and the non-piezoelectric canopy plate 9. It can be seen that there are three modes as elastic waves propagating in the three-layer structure.

FIG. 7 is a characteristic diagram showing the relationship between the frequency of surface acoustic waves and the insertion loss in the ultrasonic liquid crystal display of FIG. However, the solid line shows the case where the liquid crystal 8 is injected between the first transparent electrode 4 and the second transparent electrode 5, and the broken line shows the case where no liquid crystal 8 is injected. It can be seen that the increase in insertion loss due to the injection of the liquid crystal 8 is not so large.

FIG. 8 is a sectional view showing a second embodiment of the ultrasonic liquid crystal display of the present invention. In this embodiment, the non-piezoelectric plate 10, the piezoelectric substrate 2, the piezoelectric substrate 11, the dispersed interdigital electrodes 12, 13 and 14, and the input interdigital electrodes 15, 16 are used.
And 17, a first transparent electrode 4, a second transparent electrode 5, auxiliary plates 6 and 7, a liquid crystal 8, and a non-piezoelectric canopy plate 9. Auxiliary plates 6 and 7, dispersed interdigital electrodes 13 and 14,
The input interdigital electrodes 16 and 17 are not shown in FIG. The non-piezoelectric plate 10 is made of the same material as the non-piezoelectric plate 1 and has a similar thickness. The piezoelectric substrate 11 is made of the same material as the piezoelectric substrate 2 and has a similar size. Non-piezoelectric plate 1
A piezoelectric substrate 2, a first transparent electrode 4, and a piezoelectric substrate 11 are provided on the first, second, and third portions of the upper end surface of 0, respectively. Dispersed interdigital electrodes 12, 13 and 14
Is provided on a piezoelectric substrate 2 and has an IDT electrode 1 for input.
5, 16 and 17 are provided on the piezoelectric substrate 11. The second transparent electrode 5 is provided on a lower end surface of the non-piezoelectric canopy plate 9. The liquid crystal 8 includes a first transparent electrode 4 and a second transparent electrode 5.
2 is injected into the space having a thickness of 6 μm in the same manner as in FIG.

FIG. 9 is a plan view of the ultrasonic liquid crystal display of FIG. The first transparent electrode 4, the second transparent electrode 5, the auxiliary plates 6 and 7, and the liquid crystal 8 are not shown in FIG.
The dispersed IDTs 12, 13 and 14 are made of the same material as the IDT 3.
Has the same electrode finger pattern. Input IDT 1
5, 16 and 17 are made of the same material as the interdigital transducer 3, but have an electrode finger pattern that is line-symmetrically opposite to the electrode finger pattern of the interdigital transducer 3.

In the ultrasonic liquid crystal display shown in FIG. 8, the first electric signals are sequentially applied to the interdigital transducers 12, 13 and 14, and simultaneously the first electric signals are applied to the interdigital transducers 15, 16 and 17. Three electrical signals are applied sequentially. At this time, the frequency-modulated chirped surface acoustic wave is sequentially excited in the vicinity of the dispersed interdigital electrodes 12, 13 and 14 of the piezoelectric substrate 2, and at the same time, the piezoelectric substrate 11
Are also sequentially excited in the vicinity of the input IDTs 15, 16 and 17. The frequency-modulated chirped surface acoustic wave propagates along the upper end surface of the non-piezoelectric plate 10 and propagates to the liquid crystal 8 without leaking into the non-piezoelectric plate 10. Thus, the liquid crystal 8 becomes cloudy.

FIG. 10 is a sectional view showing a third embodiment of the ultrasonic liquid crystal display of the present invention. In this embodiment, the non-piezoelectric plate 10, the piezoelectric substrate 2, the piezoelectric substrate 11, the dispersion type interdigital electrodes 12, 13 and 14, and the output interdigital electrodes 18, 1 are used.
9 and 20, amplifier 21, switch 22, reflector 2
3, a first transparent electrode 4, a second transparent electrode 5, auxiliary plates 6 and 7, a liquid crystal 8, and a non-piezoelectric canopy plate 9. Auxiliary plates 6 and 7, distributed interdigital electrodes 13 and 14, output interdigital electrodes 19 and 20, amplifier 21 and switch 22 are not shown in FIG. The first, second and third portions of the upper end surface of the non-piezoelectric plate 10
The transparent electrode 4 and the piezoelectric substrate 11 are provided respectively. The dispersed interdigital electrodes 12, 13 and 14 are provided on the piezoelectric substrate 2 in the same manner as in FIG. The output interdigital electrodes 18, 19 and 20 are provided on the piezoelectric substrate 11. The reflection plate 23 is provided below the non-piezoelectric plate 10.

FIG. 11 is a plan view of the ultrasonic liquid crystal display of FIG. The first transparent electrode 4, the second transparent electrode 5, the auxiliary plates 6 and 7, the liquid crystal 8, and the reflector 23 are not shown in FIG. The dispersed IDTs 12, 13 and 14 and the output IDTs 18, 19 and 20 are made of the same material as the IDT 3 and have the same electrode finger pattern as the IDT 3. The amplifier 21 has a switch 22 and output interdigital electrodes 18, 19 and 2
0.

In the ultrasonic liquid crystal display shown in FIG. 10, when the first electric signal is sequentially applied to the dispersed interdigital electrodes 12, 13 and 14 via the switch 22, the dispersed interdigital electrodes 12 of the piezoelectric substrate 2 are turned on. , 13 and 14, frequency modulated chirped surface acoustic waves are sequentially excited. The frequency-modulated chirp type surface acoustic wave is transmitted to the liquid crystal 8 and the piezoelectric substrate 11 via the upper end surface of the non-piezoelectric plate 10. Liquid crystal 8
The frequency-modulated chirp type surface acoustic wave at (1) makes the liquid crystal 8 turbid. The frequency-modulated chirped surface acoustic wave on the piezoelectric substrate 11 is output to the IDT electrodes 18, 19 and 2.
At 0, it is sequentially converted into a pulse signal. After being amplified by the amplifier 21, the pulse signal is sequentially applied again to the dispersed IDTs 12, 13 and 14 via the switch 22 as a first electric signal. In this way, a self-excited oscillation type ultrasonic liquid crystal display becomes possible. Therefore, not only the size and weight of the device can be reduced and the circuit configuration can be simplified, but also driving with low voltage and low power consumption can be performed.

On the other hand, when the liquid crystal 8 is in a cloudy state, the first
When a second electric signal is applied to the sub-electrode of the transparent electrode 4 and the sub-electrode of the second transparent electrode 5, an electric field is applied to the liquid crystal 8 at the intersection of these sub-electrodes. The electric field applied to the cross region makes the liquid crystal 8 in the cross region transparent. At this time, the reflection plate 23 reflects the light passing through the liquid crystal 8.
Thus, a reflection type ultrasonic liquid crystal display can be realized. Further, a light source 24 can be used instead of the reflection plate 23.

FIG. 12 is a partially enlarged sectional view showing a fourth embodiment of the ultrasonic liquid crystal display of the present invention. This embodiment is different from FIG. 1 except that a light source 24, a first polarizer 25, a second polarizer 26, and a color filter 27 are used.
It has the same structure as The light source 24 is provided below the non-piezoelectric plate 1. The piezoelectric substrate 2, the dispersed interdigital electrodes 3, and the auxiliary plates 6 and 7 are not shown in FIG. The first polarizer 25 is provided between the non-piezoelectric plate 1 and the light source 24, and the second polarizer 26 is provided on the upper end surface of the non-piezoelectric canopy plate 9.
The polarization directions of the first polarizer 25 and the second polarizer 26 are inclined by 90 degrees from each other. The color filter 27 is provided between the second transparent electrode 5 and the liquid crystal 8.

In the ultrasonic liquid crystal display of FIG. 12, similarly to FIG. 1, a frequency modulation chirp type surface acoustic wave excited in the piezoelectric substrate 2 by applying a first electric signal to the dispersion type interdigital electrode 3. Makes the liquid crystal 8 cloudy. At this time, the liquid crystal 8 blocks light from the light source 24. Here, if the sub-electrode of the first transparent electrode 4 and the second transparent electrode 5
When a second electric signal is applied between the sub-electrodes, an electric field is applied to the liquid crystal 8 in the cross region of these sub-electrodes, and light is transmitted to the first polarizer 25, the cross region of the liquid crystal 8, and the color filter 2.
7 and the second polarizer 26 one after another. Therefore, if voltages having different amplitudes are respectively applied to three adjacent crossing regions corresponding to red, blue and green, the three colors can be mixed, and the type and degree of the colors can be adjusted. Will be possible. In this way, an all-color ultrasonic liquid crystal display is made possible. Further, it is possible to use the reflection plate 23 instead of the light source 24.

FIG. 13 is a sectional view showing a fifth embodiment of the ultrasonic liquid crystal display of the present invention. This embodiment has a laminated structure in which two display devices are stacked. Each display device has a structure similar to FIG. However,
The non-piezoelectric plate 28 between the two display devices is common to the two display devices and serves as the non-piezoelectric canopy plate 9 of FIG. 1 for the lower display device and for the upper display device. Plays the role of the non-piezoelectric plate 1 in FIG.

In the ultrasonic liquid crystal display shown in FIG.
By driving two display devices separately, it becomes possible to project a perspective image. Also, if three display devices corresponding to red, blue, and green are used, it is possible to display a full-color perspective image.

[0047] FIG. 14 is a sectional view showing a sixth embodiment of the ultrasonic liquid crystal display of the present invention. This embodiment comprises a transparent piezoelectric substrate 29, dispersed interdigital electrodes 30, a first transparent electrode 4, a second transparent electrode 5, auxiliary plates 6 and 7, a liquid crystal 8, and a transparent non-piezoelectric canopy plate 31. Auxiliary plates 6 and 7 are not shown in FIG. The non-piezoelectric canopy plate 31 is made of the same material as the non-piezoelectric canopy plate 9 and has a similar thickness. The dispersed IDT 30 is made of an aluminum thin film,
It has an electrode cycle length of up to 300 μm and is provided on the first portion of the upper end surface of the piezoelectric substrate 29. The piezoelectric substrate 29 has a thickness of 1 mm
Transparent piezoceramic plate, for example (Pb _0.92 La _0.08 )
(Zr _0.53 Ti _0.47 ) O ₃ . First of the upper end surface of the piezoelectric substrate 29
Is polarized in advance so that the direction of the polarization axis of the portion is parallel to the thickness direction. The first transparent electrode 4 is provided on a second portion of the upper end surface of the piezoelectric substrate 29. The second transparent electrode 5 is provided on a lower end surface of the non-piezoelectric canopy plate 31. If a first electric signal is applied to the interdigital transducer 30, a frequency-modulated chirped surface acoustic wave is excited in the first portion of the upper end surface of the piezoelectric substrate 29. The frequency-modulated chirp type surface acoustic wave propagates through the liquid crystal 8 through the second portion on the upper end surface of the piezoelectric substrate 29, and the liquid crystal 8 becomes turbid.
At this time, when a second electric signal is applied between one of the sub-electrodes of the first transparent electrode 4 and one of the sub-electrodes of the second transparent electrode 5, each of the first transparent electrode 4 and the second transparent electrode 5 An electric field is applied to the liquid crystal 8 in the region where the sub-electrodes cross. The electric field applied to the cross region makes the liquid crystal 8 in the cross region transparent.

[0048]

According to the ultrasonic liquid crystal display of the present invention, a transparent non-piezoelectric plate, a piezoelectric substrate provided on a first portion of the upper end surface of the non-piezoelectric plate, and at least one distributed type provided on the piezoelectric substrate are provided. An interdigital transducer, a non-piezoelectric canopy plate, a first transparent electrode provided on a second portion of an upper end surface of the non-piezoelectric plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, It consists of liquid crystal injected between the first and second transparent electrodes.

If the first electric signal is applied to the interdigital transducer, a frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate. The frequency-modulated chirped surface acoustic wave propagates along the upper end surface of the non-piezoelectric plate through the liquid crystal portion without leaking into the non-piezoelectric plate. When the frequency-modulated chirped surface acoustic wave propagates through the liquid crystal portion, a dynamic scattering state is induced in the liquid crystal. Thus, the liquid crystal becomes turbid.
When a second electric signal is applied between the first and second transparent electrodes when the liquid crystal is in a cloudy state, an electric field is applied to the liquid crystal, so that the orientation of the liquid crystal changes and the liquid crystal transmits light. , The liquid crystal becomes transparent.

In the ultrasonic liquid crystal display of the present invention, a structure in which a light source and a reflecting plate are provided under a non-piezoelectric plate is possible. By employing a reflector, a reflective ultrasonic liquid crystal display can be configured. The reflective ultrasonic liquid crystal display can be driven with lower power consumption than a structure using a light source.

In the ultrasonic liquid crystal display of the present invention, a structure including the first and second polarizers and a color filter is possible. In this way, it is possible to configure an all-color ultrasonic liquid crystal display.

In the ultrasonic liquid crystal display of the present invention, a structure in which the liquid crystal is composed of a nematic liquid crystal is possible. Also,
A structure in which the liquid crystal before the frequency modulation chirp type surface acoustic wave is propagated forms a homogeneous alignment is possible.

In the ultrasonic liquid crystal display of the present invention, a structure in which the first and second transparent electrodes are each composed of an aggregate of elongated sub-electrodes is possible. At this time, each of the aggregates of the sub-electrodes forms a stripe pattern, and the stripe patterns of the first transparent electrode and the second transparent electrode are orthogonal to each other. If a second electric signal is applied between the at least one sub-electrode of the first transparent electrode and the at least one sub-electrode of the second transparent electrode when the liquid crystal is in a cloudy state, the first and second transparent electrodes are applied. Since an electric field is applied to the liquid crystal in the cross region of each sub-electrode of the electrode, the liquid crystal in the cross region becomes transparent.

In the ultrasonic liquid crystal display of the present invention, another piezoelectric substrate is provided on the third portion of the upper end surface of the non-piezoelectric plate, and at least one IDT electrode is provided on the other piezoelectric substrate. A configured structure is possible. The input interdigital transducer has an electrode finger pattern that is opposite to the electrode finger pattern of the distributed interdigital transducer provided in the first portion. When a third electric signal is applied to the input interdigital transducer at the same time as the first electric signal is applied to the dispersed interdigital transducer, a frequency-modulated chirp type surface acoustic wave is excited on the piezoelectric substrate in the first portion. At the same time, another frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate in the third portion. Since the two frequency-modulated chirped surface acoustic waves are simultaneously transmitted to the liquid crystal in this manner, the liquid crystal is further clouded.

In the ultrasonic liquid crystal display of the present invention, another piezoelectric substrate is provided on the third portion of the upper end surface of the non-piezoelectric plate, and at least one output IDT is provided on the other piezoelectric substrate. A structure is possible in which an amplifier is connected between the output IDT and the dispersed IDT. The output IDT has the same electrode finger pattern as that of the dispersed IDT provided in the first portion. The first type of interdigital electrode
When an electric signal is applied, a frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate in the first portion. The frequency-modulated chirped surface acoustic wave is propagated to the liquid crystal and is also propagated to the piezoelectric substrate in the third portion to be converted into a pulse signal. This pulse signal is again applied to the distributed IDT via the amplifier. In this way, a self-pulsation type ultrasonic liquid crystal display can be configured. Accordingly, the circuit configuration is simplified, the size and weight of the device are promoted, and low-voltage driving with low power consumption is possible.

In the ultrasonic liquid crystal display of the present invention, a structure having a laminated structure formed by stacking at least two display devices is possible. At this time, it is also possible to employ only one non-piezoelectric plate instead of the non-piezoelectric canopy plate of the lower display device and the non-piezoelectric plate of the upper display device. By separately driving such display devices, it is possible to project a fluoroscopic image. Also, if three display devices corresponding to red, blue, and green are used, it is possible to display a full-color perspective image.

According to the ultrasonic liquid crystal display of the present invention, a transparent piezoelectric substrate, at least one dispersed IDT provided on a first portion of the upper end surface of the piezoelectric substrate, a transparent non-piezoelectric canopy plate, A first transparent electrode provided on a second portion of the upper end surface of the substrate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, and a liquid crystal sandwiched between the first and second transparent electrodes. Structures are possible. In this structure, if a first electric signal is applied to the interdigital transducer, a frequency-modulated chirped surface acoustic wave is excited in the first portion of the upper end surface of the piezoelectric substrate. The frequency-modulated chirped surface acoustic wave propagates to the liquid crystal via the second portion on the upper end surface of the piezoelectric substrate, and the liquid crystal becomes turbid. When a second electric signal is applied between the first and second transparent electrodes while the liquid crystal is in a cloudy state, an electric field is applied to the liquid crystal to make the liquid crystal transparent.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an ultrasonic liquid crystal display according to the present invention.

FIG. 2 is a partial plan view of the ultrasonic liquid crystal display of FIG.

FIG. 3 is a plan view of a dispersed interdigital electrode 3;

FIG. 4 is a partially enlarged plan view of a first transparent electrode 4;

FIG. 5 is a characteristic diagram showing a velocity dispersion curve of a surface acoustic wave propagating in a two-layer structure of a non-piezoelectric plate 1 and a piezoelectric substrate 2.

FIG. 6 is a characteristic diagram showing a velocity dispersion curve of an elastic wave propagating through a three-layer structure including the non-piezoelectric plate 1, the liquid crystal 8, and the non-piezoelectric canopy plate 9.

FIG. 7 is a characteristic diagram showing a relationship between a frequency of a surface acoustic wave and an insertion loss in the ultrasonic liquid crystal display of FIG. 1;

FIG. 8 is a sectional view showing a second embodiment of the ultrasonic liquid crystal display of the present invention.

FIG. 9 is a plan view of the ultrasonic liquid crystal display of FIG. 8;

FIG. 10 is a sectional view showing a third embodiment of the ultrasonic liquid crystal display of the present invention.

FIG. 11 is a plan view of the ultrasonic liquid crystal display of FIG. 10;

FIG. 12 is a partially enlarged sectional view showing a fourth embodiment of the ultrasonic liquid crystal display of the present invention.

FIG. 13 is a sectional view showing a fifth embodiment of the ultrasonic liquid crystal display of the present invention.

FIG. 14 is a sectional view showing a sixth embodiment of the ultrasonic liquid crystal display of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-piezoelectric plate 2 Piezoelectric substrate 3 Distributed type interdigital electrode 4 1st transparent electrode 5 2nd transparent electrode 6 Auxiliary plate 7 Auxiliary plate 8 Liquid crystal 8 9 Non-piezoelectric canopy plate 10 Non-piezoelectric plate 11 Piezoelectric substrates 12, 13, 14 Dispersion IDT electrodes 15, 16, 17 IDT electrodes 18, 19, 20 IDT electrodes 21 Amplifier 22 Switch 23 Reflector 24 Light source 25 First polarizer 26 Second polarizer 27 Color filter 28 Non-piezoelectric plate 29 Non-piezoelectric plate 30 Distributed interdigital electrodes 31 Non-piezoelectric canopy plate

Claims (14)

[Claims] 1. A transparent non-piezoelectric plate, a piezoelectric substrate provided on a first portion of an upper end surface of the non-piezoelectric plate, and at least one distributed interdigital transducer provided on the piezoelectric substrate.
A first transparent electrode provided on a second portion of the upper end surface of the non-piezoelectric plate, a transparent non-piezoelectric canopy plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, An ultrasonic liquid crystal display comprising a liquid crystal sandwiched between first and second transparent electrodes, wherein a first electric signal is applied to the dispersion type interdigital transducer, whereby a frequency modulation chirp type elastic surface is applied to the piezoelectric substrate. When a wave is excited and the frequency-modulated chirped surface acoustic wave propagates through the liquid crystal, the liquid crystal becomes turbid and a second electric signal is applied between the first and second transparent electrodes. An ultrasonic liquid crystal display in which an electric field is applied to the liquid crystal to make the liquid crystal transparent. 2. The ultrasonic liquid crystal display according to claim 1, wherein a light source is provided below the non-piezoelectric plate. 3. The ultrasonic liquid crystal display according to claim 1, wherein a reflection plate is provided below the non-piezoelectric plate. 4. An ultrasonic liquid crystal display comprising at least two display devices, wherein the at least two display devices are stacked to form a laminated structure, each of the display devices being a transparent non-piezoelectric plate, A piezoelectric substrate provided on a first portion of an upper end surface of the non-piezoelectric plate, at least one distributed IDT provided on the piezoelectric substrate, and a second portion of the upper end surface of the non-piezoelectric plate A first transparent electrode, a transparent non-piezoelectric canopy plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, and a liquid crystal sandwiched between the first and second transparent electrodes. When a first electric signal is applied to the dispersed IDT, a frequency-modulated chirped surface acoustic wave is excited on the piezoelectric substrate, and the frequency-modulated chirped surface acoustic wave is applied to the liquid crystal. The liquid crystal becomes turbid, and a second electric signal is applied between the first and second transparent electrodes, whereby an electric field is applied to the liquid crystal and the liquid crystal becomes transparent. Sonic liquid crystal display. 5. The ultrasonic liquid crystal display according to claim 1, wherein said piezoelectric substrate is made of a piezoelectric ceramic plate, and a direction of a polarization axis of said piezoelectric ceramic plate is parallel to a thickness direction thereof. 6. A method according to claim 1, wherein the thickness of the piezoelectric substrate is smaller than the minimum electrode period length of the interdigital transducer, and the thickness of the non-piezoelectric plate and the non-piezoelectric canopy plate is the maximum electrode of the interdigital transducer. 3. The method according to claim 1, wherein the period length is larger than twice the period length.
6. The ultrasonic liquid crystal display according to 3, 4, or 5. 7. The phase velocity of a frequency-modulated chirped surface acoustic wave propagating in the non-piezoelectric plate itself is faster than the phase velocity of the frequency-modulated chirped surface acoustic wave propagating in the piezoelectric substrate itself. 7. The ultrasonic liquid crystal display according to 3, 4, 5, or 6. 8. A third piezoelectric substrate is provided on a third portion of the upper end face of the non-piezoelectric plate, and the other piezoelectric substrate has an opposite electrode finger pattern to the dispersed interdigital transducer. At least one input interdigital transducer having an electrode finger pattern is provided, and a third electric signal is applied to the input interdigital transducer simultaneously with the application of the first electric signal to the dispersed interdigital transducer. Accordingly, another frequency-modulated chirped surface acoustic wave is excited on the another piezoelectric substrate, and the another frequency-modulated chirped surface acoustic wave is propagated to the liquid crystal, whereby the liquid crystal is further transformed. Claims 1, 2, 3, 4, 5, 6, which become cloudy.
Or the ultrasonic liquid crystal display according to 7. 9. A third piezoelectric substrate is provided on a third portion of the upper end surface of the non-piezoelectric plate, and the other piezoelectric substrate has the same electrode finger pattern as the electrode finger pattern of the distributed interdigital transducer. 7. An output interdigital transducer having at least one output interdigital transducer having a pattern, and an amplifier connected between the distributed interdigital transducer and the output interdigital transducer. , 7 or 8. 10. A transparent piezoelectric substrate, at least one distributed interdigital transducer provided on a first portion of an upper end surface of the transparent piezoelectric substrate, and a second interdigital transducer provided on the upper end surface of the transparent piezoelectric substrate. A first transparent electrode provided in the portion, a transparent non-piezoelectric canopy plate, a second transparent electrode provided on a lower end surface of the non-piezoelectric canopy plate, and the first and second transparent electrodes. An ultrasonic liquid crystal display comprising a liquid crystal, wherein a first electric signal is applied to the dispersion type interdigital transducer, so that a frequency modulated chirp type surface acoustic wave is applied to the first portion on the upper end surface of the piezoelectric substrate. Is excited, and the frequency-modulated chirped surface acoustic wave is transmitted to the liquid crystal through the second portion of the upper end surface of the piezoelectric substrate, so that the liquid crystal becomes turbid, and the first and second liquid crystals become opaque. A second electrical signal between the transparent electrodes Is applied, an electric field is applied to the liquid crystal, and the liquid crystal becomes transparent. 11. The first and second transparent electrodes are each formed of an aggregate of elongated sub-electrodes, and each of the aggregates of the sub-electrodes forms a stripe pattern. The stripe patterns of the two transparent electrodes are orthogonal to each other, and the second electric signal is applied between at least one of the first transparent electrodes and at least one of the second transparent electrodes. An electric field is applied to the liquid crystal at an intersection between the sub-electrode of the first transparent electrode and the sub-electrode of the second transparent electrode, whereby the liquid crystal at the intersection becomes transparent. , 2,3,4,5
The ultrasonic liquid crystal display according to 6, 7, 8, 9 or 10. 12. The ultrasonic liquid crystal display according to claim 1, wherein said liquid crystal is a nematic liquid crystal. 13. The liquid crystal of claim 1, wherein said liquid crystal has a homogeneous orientation before said frequency modulated chirp type surface acoustic wave is propagated.
Or the ultrasonic liquid crystal display according to 12. 14. The system according to claim 1, further comprising a first and a second polarizer and a color filter.
The ultrasonic liquid crystal display according to 7, 8, 9, 10, 11, 12 or 13.