Ultrasonic liquid crystal device and ultrasonic liquid crystal control method

Abstract

To provide an ultrasonic liquid crystal device capable of changing a diffusion state of light.SOLUTION: An ultrasonic liquid crystal device 1 comprises a substrate 2, an ultrasonic vibrator 3, a liquid crystal unit 4, and a drive control unit 5. The ultrasonic vibrator 3 includes a first vibrator part and a second vibrator part arranged opposite each other. The drive control unit 5 applies a first voltage signal to the first vibrator part and applies a second voltage signal having a reverse phase to the first voltage signal to the second vibrator part, thereby performing voltage control processing to generate a non-axisymmetric deflection standing wave in the liquid crystal unit 4. In the liquid crystal unit 4 during the voltage control processing, the belly and the node of the deflection standing wave are generated on a first straight line, and a nodal line of the deflection standing wave is generated on a second straight line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic liquid crystal device and an ultrasonic liquid crystal control method. [Background technology]

[0002] In general, lighting devices are optically designed to achieve a specified illuminance with a smaller total amount of light by combining lenses, reflectors, and light diffusers depending on the application and required illuminance distribution. However, it is difficult for the light diffusers used in lighting devices to change the direction of light diffusion without a mechanical mechanism. Furthermore, devices that can change the state of light diffusion without a mechanical mechanism are expected to be useful not only in the field of lighting devices but also in other fields (e.g., optical sensing).

[0003] The inventor of the present application has proposed a liquid crystal variable-focus lens as described in Patent Document 1. The liquid crystal variable-focus lens described in Patent Document 1 does not change the diffusion state of light, but it can change the focal length by generating first-order mode flexural vibrations (axially symmetric flexural standing waves) whose vibration intensity decreases continuously from the center side to the periphery side of the liquid crystal layer, thereby changing the orientation of the liquid crystal molecules. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6414994 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic liquid crystal device and an ultrasonic liquid crystal control method that are capable of changing the diffusion state of light. [Means for solving the problem]

[0006] In order to solve the above problems, an ultrasonic liquid crystal device according to the present invention comprises: a substrate that transmits visible light; an ultrasonic transducer arranged in a ring shape on the substrate; a liquid crystal portion disposed inside the ultrasonic vibrator of the substrate; a drive control unit that applies a voltage signal to the ultrasonic transducer to generate ultrasonic waves; An ultrasonic liquid crystal device comprising: The ultrasonic transducer includes N transducer portions (N is a multiple of 2) divided into N portions in the circumferential direction, the N transducer units include a first transducer unit and a second transducer unit that are arranged opposite to each other; The drive control unit a voltage control process is performed by applying a first voltage signal having a resonance frequency of the liquid crystal unit to the first vibrator unit, and applying a second voltage signal having a phase opposite to that of the first voltage signal to the second vibrator unit, thereby generating a non-axisymmetric flexural standing wave in the liquid crystal unit; In the liquid crystal unit during the voltage control process, When the direction in which the first vibrator part and the second vibrator part face each other is defined as a first direction and the direction intersecting the first direction is defined as a second direction, an antinode and a node of the flexural standing wave occur on one side on a first straight line extending in the first direction and a second straight line extending in the second direction, and a nodal line of the flexural standing wave occur on the other side.

[0007] In the ultrasonic liquid crystal device, The N transducer units include four or more transducer units, The drive control unit Before the voltage control process is performed, a selection process for selecting the first oscillator section and the second oscillator section from the N oscillator sections can be performed.

[0008] In the ultrasonic liquid crystal device, The drive control unit A series of processes consisting of the selection process and the voltage control process can be performed multiple times, and the combination of the first vibrator unit and the second vibrator unit selected in the selection process can be changed.

[0009] In the ultrasonic liquid crystal device, The drive control unit The combination may be changed so that the first straight line rotates.

[0010] In the ultrasonic liquid crystal device, The drive control unit during the voltage control process The voltage of the voltage signal applied to the oscillator parts other than the first oscillator part and the second oscillator part can be set to zero.

[0011] In order to solve the above problems, the ultrasonic liquid crystal control method according to the present invention includes: An ultrasonic liquid crystal control method using an ultrasonic liquid crystal device including a substrate that transmits visible light, an ultrasonic vibrator that is arranged in an annular shape on the substrate and includes N vibrator sections (N is a multiple of 2) that are divided into N sections in the circumferential direction, a liquid crystal section that is arranged inside the ultrasonic vibrator on the substrate, and a drive control section that applies a voltage signal to the ultrasonic vibrator to generate ultrasonic waves, the N transducer units include a first transducer unit and a second transducer unit that are arranged opposite to each other; a voltage control processing step of applying a first voltage signal having a resonance frequency of the liquid crystal section to the first vibrator section and applying a second voltage signal having a phase opposite to that of the first voltage signal to the second vibrator section by the drive control section, thereby generating a non-axisymmetric flexural standing wave in the liquid crystal section; In the voltage control processing step, when the direction in which the first vibrator section and the second vibrator section face each other is defined as a first direction and the direction intersecting the first direction is defined as a second direction, an antinode and a node of the flexural standing wave are generated on one side of a first straight line extending in the first direction of the liquid crystal section and a second straight line extending in the second direction, and a nodal line of the flexural standing wave is generated on the other side.

[0012] The ultrasonic liquid crystal control method includes: The N transducer units include four or more transducer units, The method can be configured to include, before the voltage control processing step, a selection processing step of selecting the first vibrator unit and the second vibrator unit from the N vibrator units by the drive control unit.

[0013] The ultrasonic liquid crystal control method includes: A series of processing steps consisting of the selection processing step and the voltage control processing step can be performed multiple times, and the combination of the first vibrator unit and the second vibrator unit selected in the selection processing step can be changed.

[0014] In the ultrasonic liquid crystal control method, The combination may be changed so that the first straight line rotates.

[0015] In the ultrasonic liquid crystal control method, In the voltage control processing step, the voltage of the voltage signal applied to the oscillator sections other than the first oscillator section and the second oscillator section can be set to zero. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an ultrasonic liquid crystal device and an ultrasonic liquid crystal control method that are capable of changing the diffusion state of light. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B are a plan view and a cross-sectional view, respectively, of an ultrasonic liquid crystal device according to the present invention. [Figure 2] 3A and 3B are diagrams illustrating the orientation of liquid crystal molecules in a liquid crystal portion. [Figure 3] 1A and 1B are diagrams showing a case where voltage signals of opposite phases are applied to the vibrator section ch1 and the vibrator section ch3, where (A) is a plan view and (B) is a diagram showing vibration modes. [Figure 4] 4A and 4B are diagrams showing flexural standing waves along line AA' and line BB' in Fig. 3, respectively. [Figure 5]4A and 4B are diagrams showing the alignment of liquid crystal molecules in a cross section taken along line AA' and line BB' in FIG. [Figure 6] (A) A diagram showing transmitted light when ultrasound is off, (B) A diagram showing transmitted light when ultrasound is on (when ch1 and ch3 are driven), and (C) A diagram showing transmitted light when ultrasound is on (when ch2 and ch4 are driven). [Figure 7] FIG. 1 is a diagram showing an experimental device using an ultrasonic liquid crystal device according to the present invention. [Figure 8] FIG. 10 is a diagram showing the change over time in transmitted light intensity. [Figure 9] FIG. 10 is a distribution diagram of transmitted light intensity along line AA'. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ultrasonic liquid crystal device and an ultrasonic liquid crystal control method according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] (ultrasonic liquid crystal device) Fig. 1 shows an ultrasonic liquid crystal device 1 according to one embodiment of the present invention. In Fig. 1, the X direction is the left-right direction of the ultrasonic liquid crystal device 1, the Y direction is the front-rear direction of the ultrasonic liquid crystal device 1, and the Z direction is the up-down direction of the ultrasonic liquid crystal device 1. The ultrasonic liquid crystal device 1 includes a substrate 2, an ultrasonic vibrator 3, a liquid crystal unit 4, and a drive control unit 5.

[0020] The substrate 2 is a substrate that transmits visible light. In this embodiment, a glass substrate formed in a disk shape is used as the substrate 2.

[0021] The ultrasonic vibrator 3 is an ultrasonic vibrator arranged in a ring shape on the upper surface of the substrate 2. In this embodiment, the ultrasonic vibrator 3 is a piezoelectric ultrasonic vibrator made of lead zirconate titanate (PZT) and having a circular ring shape with a central opening.

[0022] The ultrasonic transducer 3 includes N transducer sections (N is a multiple of 2) divided into N sections in the circumferential direction. In this embodiment, N=4, and the ultrasonic transducer 3 includes four transducer sections 31-34 divided equally into four sections in the circumferential direction. In this embodiment, the four transducer sections 31-34 are made up of an undivided piezoelectric ultrasonic transducer and electrodes divided into four sections, but the four transducer sections 31-34 may also be made up of a piezoelectric ultrasonic transducer divided into four sections and electrodes divided into four sections.

[0023] The transducer section 31 is composed of a right rear portion of the ultrasonic transducer, a positive electrode 31a formed on the upper surface of the right rear portion, and a negative electrode 31b formed on the entire lower surface of the ultrasonic transducer and drawn out to the upper surface via the side surface of the right rear portion. The positive electrode 31a and the negative electrode 31b are insulated from each other.

[0024] The transducer section 32 is composed of a left rear portion of the ultrasonic transducer, a positive electrode 32a formed on the upper surface of the left rear portion, and a negative electrode 32b formed on the entire lower surface of the ultrasonic transducer and drawn out to the upper surface via the side surface of the left rear portion. The positive electrode 32a and the negative electrode 32b are insulated from each other.

[0025] The transducer section 33 is composed of a left front portion of the ultrasonic transducer, a positive electrode 33a formed on the upper surface of the left front portion, and a negative electrode 33b formed on the entire lower surface of the ultrasonic transducer and drawn out to the upper surface via the side surface of the left front portion. The positive electrode 33a and the negative electrode 33b are insulated from each other.

[0026] The transducer section 34 is composed of a right front portion of the ultrasonic transducer, a positive electrode 34a formed on the upper surface of the right front portion, and a negative electrode 34b formed on the entire lower surface of the ultrasonic transducer and drawn out to the upper surface via the side surface of the right front portion. The positive electrode 34a and the negative electrode 34b are insulated from each other.

[0027] The positive electrodes 31a to 34a are insulated from each other, while the negative electrodes 31b to 34b form a common negative electrode on the lower surface of the ultrasonic vibrator. In this embodiment, silver baked electrodes are used as the positive electrodes 31a to 34a and the negative electrodes 31b to 34b. Known materials can be used as the electrodes.

[0028] The liquid crystal section 4 is disposed in the central opening of the ultrasonic transducer 3. As shown in Fig. 2, the liquid crystal section 4 includes a first substrate 41 and a second substrate 42 (substrate 2) disposed opposite each other, a first alignment film 43 provided on the lower surface side of the first substrate 41, a second alignment film 44 provided on the upper surface side of the second substrate 42, and a liquid crystal layer 45. The liquid crystal layer 45 includes liquid crystal molecules 46.

[0029] The first substrate 41 is a substrate (a glass substrate in this embodiment) that transmits visible light. The second substrate 42 is a portion of the substrate 2 that faces the first substrate 41, but may be a substrate that transmits visible light different from the substrate 2. The first alignment film 43 and the second alignment film 44 are vertical alignment films that cause the liquid crystal molecules 46 to have a pretilt angle of 90°, and are made of a polyimide-based material. The liquid crystal layer 45 contains nematic liquid crystal molecules 46, and a predetermined thickness is ensured by a spacer (e.g., a PET film). The periphery of the liquid crystal layer 45 is sealed with a sealant (e.g., an epoxy resin).

[0030] The drive control unit 5 is configured to apply a voltage signal (e.g., a continuous sine wave voltage signal) to the ultrasonic transducer 3, causing the ultrasonic transducer 3 to generate ultrasonic waves. The drive control unit 5 includes a first drive control unit 5a that applies a voltage signal to the transducer unit 31, a second drive control unit 5b that applies a voltage signal to the transducer unit 32, a third drive control unit 5c that applies a voltage signal to the transducer unit 33, a fourth drive control unit 5d that applies a voltage signal to the transducer unit 34, and a general control unit (not shown). The general control unit determines the phase, voltage value (peak-to-peak value), frequency, etc. of the voltage signals output from the first drive control unit 5a to the fourth drive control unit 5d. The drive control unit 5 is configured, for example, with a function generator and an amplifier for amplifying the amplitude of the electrical signal from the function generator.

[0031] The drive control unit 5 performs a selection process and a voltage control process. For example, the selection process is performed by the general control unit, and the voltage control process is performed by the general control unit and the first drive control unit 5a to the fourth drive control unit 5d.

[0032] During the selection process, the drive control unit 5 selects the first and second transducer units that are arranged opposite each other from among the four transducer units 31 to 34. For example, if the ultrasonic liquid crystal device 1 includes an operation unit configured to allow the user to select the first and second transducer units, the drive control unit 5 selects the first and second transducer units based on a command signal from the operation unit (a signal related to the combination of the first and second transducer units selected by the user). Alternatively, the combination of the first and second transducer units to be selected by the drive control unit 5 may be preset.

[0033] 3A, in this embodiment, transducer unit 31 (ch1) and transducer unit 33 (ch3) are arranged opposite each other, and transducer unit 32 (ch2) and transducer unit 34 (ch4) are arranged opposite each other. During the selection process, drive control unit 5 selects transducer unit 31 (ch1) and transducer unit 33 (ch3) as a combination of the first transducer unit and the second transducer unit, or selects transducer unit 32 (ch2) and transducer unit 34 (ch4).

[0034] In Figures 3(A) and 3(B), transducer unit 31 (ch1) and transducer unit 33 (ch3) are selected as the combination of the first transducer unit and the second transducer unit. In this case, the direction of line A-A' in Figure 3 corresponds to the "first direction" of the present invention, and line A-A' corresponds to the "first straight line" of the present invention. Also, the direction of line B-B' in Figure 3 corresponds to the "second direction" of the present invention, and line B-B' corresponds to the "second straight line" of the present invention.

[0035] During the voltage control process, the drive control unit 5 applies a first voltage signal to the first vibrator unit and a second voltage signal, which is opposite in phase to the first voltage signal, to the second vibrator unit. That is, the first and second voltage signals are continuous sine wave voltage signals that have the same voltage value (peak-to-peak value) and frequency but are 180° out of phase with each other. The frequencies of the first and second voltage signals are the resonant frequencies of the liquid crystal unit 4 and are frequencies that generate flexural standing waves in the liquid crystal unit 4, as described below. There are multiple resonant modes that resonate the liquid crystal unit 4, and flexural standing waves are generated in some of these modes.

[0036] When the vibrator unit 31 (ch1) and the vibrator unit 33 (ch3) are selected in the selection process, the drive control unit 5 applies a first voltage signal to the vibrator unit 31 (ch1), applies a second voltage signal to the vibrator unit 33 (ch3), and sets the voltage of the voltage signal to be applied to the vibrator unit 32 (ch2) and the vibrator unit 34 (ch4) to zero (i.e., does not apply a voltage signal).

[0037] Similarly, when the selection process selects the vibrator unit 32 (ch2) and the vibrator unit 34 (ch4), the drive control unit 5 applies a first voltage signal to the vibrator unit 32 (ch2), applies a second voltage signal to the vibrator unit 34 (ch4), and sets the voltage of the voltage signal to be applied to the vibrator unit 31 (ch1) and the vibrator unit 33 (ch3) to zero (i.e., does not apply a voltage signal).

[0038] During voltage control processing, a non-axisymmetric flexural standing wave is generated in the liquid crystal section 4. More specifically, if the direction in which the first vibrator section and the second vibrator section face each other is defined as a first direction and the direction perpendicular to the first direction is defined as a second direction, antinodes and nodes of the flexural standing wave are generated on a first straight line extending in the first direction, and nodal lines of the flexural standing wave are generated on a second straight line extending in the second direction.

[0039] Figure 3(B) shows the vibration mode when a first voltage signal is applied to the vibrator section 31 (ch1) and a second voltage signal is applied to the vibrator section 33 (ch3). Figure 3(B) shows the vibration mode analyzed using a simulation analysis tool (ANSYS14.5). As shown in Figure 3(B), an antinode and a node of the flexural standing wave occur on line A-A', and a node of the flexural standing wave occurs on line B-B'.

[0040] Fig. 4(A) shows the flexural standing wave along line A-A' in Fig. 3, and Fig. 4(B) shows the flexural standing wave along line B-B' in Fig. 3. Note that the solid line in Fig. 4 is the flexural standing wave at the moment shown in Fig. 3(B). As can be seen from Fig. 4, a non-axisymmetric flexural standing wave occurs in the liquid crystal section 4, and antinodes and nodes of the flexural standing wave occur on line A-A' in the liquid crystal section 4, and nodes of the flexural standing wave occur on line B-B' in the liquid crystal section 4.

[0041] 5A shows the orientation of the liquid crystal molecules 46 in the cross section taken along line AA' in FIG. 3, and FIG. 5B shows the orientation of the liquid crystal molecules 46 in the cross section taken along line BB' in FIG.

[0042] Here, when a voltage signal is applied to the first vibrator section and the second vibrator section, vibration occurs in the substrate 2 due to the inverse piezoelectric effect. When the frequency of the voltage signal is matched to the resonance frequency of the liquid crystal section 4, vibration in a resonance mode occurs in the liquid crystal section 4. There are multiple resonance modes, some of which generate flexural standing waves in the liquid crystal section 4. In this embodiment, the frequency of the voltage signal is set to a resonance mode that generates flexural standing waves in the liquid crystal section 4.

[0043] When flexural standing waves are generated in the liquid crystal section 4, differences in acoustic impedance cause differences in acoustic energy density at the interface between the substrate 2 and the liquid crystal layer 45 of the liquid crystal section 4, resulting in a static acoustic radiation force. The static acoustic radiation force is large at the antinodes of the flexural standing waves and small at the nodes of the flexural standing waves. As a result, the orientation of the liquid crystal molecules 46 changes at the antinodes of the flexural standing waves, but does not change at the nodes of the flexural standing waves.

[0044] During voltage control processing in which voltage signals of opposite phases are applied to the first vibrator section and the second vibrator section, antinodes and nodes of a flexural standing wave are generated on line A-A' of the liquid crystal section 4, causing liquid crystal molecules 46 to tilt at the antinodes of the flexural standing wave, as shown in Figure 5(A). In Figure 5(A), the liquid crystal molecules 46 are tilted to the right and left of the center. In this state, when light is incident on the liquid crystal section 4 from the first substrate 41 side, the transmitted light that passes through the liquid crystal section 4 is diffused.

[0045] On the other hand, a nodal line of the flexural standing wave occurs on line B-B' of the liquid crystal portion 4, so the liquid crystal molecules 46 do not tilt. The liquid crystal molecules 46 stand up perpendicular to the first alignment film 43 and the second alignment film 44, just as when the ultrasonic vibrator 3 is not generating ultrasonic waves. In this state, when light is incident on the liquid crystal portion 4 from the first substrate 41 side, the transmitted light that has passed through the liquid crystal portion 4 is not diffused.

[0046] Fig. 6(A) shows the transmitted light when the ultrasound is off, Fig. 6(B) shows the transmitted light when the ultrasound is on (when ch1 and ch3 are driven), and Fig. 6(C) shows the transmitted light when the ultrasound is on (when ch2 and ch4 are driven). Figs. 6(A) to (C) show the shape of the transmitted light as seen from the second substrate 42 (substrate 2) side of the liquid crystal section 4 when light is incident on the liquid crystal section 4 from the first substrate 41 side. Lines A-A' and B-B' in the figures are the same as lines A-A' and B-B' in Fig. 3.

[0047] When the ultrasound is off, that is, when no voltage signals are applied to the four transducer parts 31 to 34 (ch1 to ch4), the transmitted light does not diffuse (the incident light and transmitted light have the same shape) as shown in FIG. 6(A).

[0048] When ultrasound is on (channels 1 and 3 are driven), that is, when a first voltage signal is applied to one of transducer section 31 (channel 1) and transducer section 33 (channel 3), a second voltage signal is applied to the other, and no voltage signal is applied to transducer section 32 (channel 2) and transducer section 34 (channel 4), the transmitted light is diffused in the direction of line A-A' as shown in Figure 6(B). The width of the transmitted light in the direction of line B-B' is approximately the same as in Figure 6(A).

[0049] When ultrasound is on (ch2 and ch4 are driven), i.e., when a first voltage signal is applied to one of the transducer units 32 (ch2) and 34 (ch4) and a second voltage signal is applied to the other, and no voltage signal is applied to the transducer units 31 (ch1) and 33 (ch3), the transmitted light diffuses in the direction of line B-B' as shown in FIG. 6(C). The width of the transmitted light in the direction of line A-A' is approximately the same as in FIG. 6(A). Note that in FIG. 6(C), the direction of line B-B' corresponds to the "first direction" of the present invention, and line B-B' corresponds to the "first straight line" of the present invention. Furthermore, the direction of line A-A' in FIG. 6(C) corresponds to the "second direction" of the present invention, and line A-A' corresponds to the "second straight line" of the present invention.

[0050] In this way, in the ultrasonic liquid crystal device 1, the diffusion state of the light transmitted through the liquid crystal unit 4 can be changed (switching between diffusion and no diffusion) by turning on and off the ultrasonic waves of the ultrasonic vibrator 3 under the control of the drive control unit 5. Furthermore, in the ultrasonic liquid crystal device 1, the diffusion direction of the light transmitted through the liquid crystal unit 4 can also be changed by changing the combination of the first vibrator unit and the second vibrator unit to which a voltage signal is applied.

[0051] (Ultrasonic liquid crystal control method) Next, an ultrasonic liquid crystal control method according to one embodiment of the present invention will be described. The ultrasonic liquid crystal control method of this embodiment is a method for changing the diffusion state of transmitted light through the liquid crystal section 4 using the ultrasonic liquid crystal device 1.

[0052] The ultrasonic liquid crystal control method of this embodiment includes a selection processing step and a voltage control processing step. The selection processing step is a step in which the drive control unit 5 performs selection processing, and the voltage control processing step is a step in which the drive control unit 5 performs voltage control processing.

[0053] In the selection processing step, the drive control unit 5 performs a selection process to select the first and second transducer units that are arranged opposite each other from among the four transducer units 31 to .

[0054] In the voltage control processing step, the drive control unit 5 applies a first voltage signal to the first vibrator unit and a second voltage signal, which is opposite in phase to the first voltage signal, to the second vibrator unit through voltage control processing. That is, the first voltage signal and the second voltage signal are continuous sine wave voltage signals that have the same voltage value (peak-to-peak value) and frequency, but differ in phase by 180°. The frequencies of the first voltage signal and the second voltage signal are the resonant frequency of the liquid crystal unit 4 and are frequencies that generate non-axisymmetric flexural standing waves in the liquid crystal unit 4 (see, for example, FIG. 3(B)).

[0055] In the ultrasonic liquid crystal control method, it is possible to diffuse light transmitted through the liquid crystal section 4 by generating non-axisymmetric flexural standing waves in the liquid crystal section 4. Furthermore, in the ultrasonic liquid crystal control method, it is also possible to change the direction of diffusion of light transmitted through the liquid crystal section 4 by changing the combination of the first vibrator section and the second vibrator section in the selection processing step.

[0056] (Evaluation experiment) Next, an evaluation experiment of the ultrasonic liquid crystal device 1 and the ultrasonic liquid crystal control method will be described with reference to FIG.

[0057] In the evaluation experiment, vibrator section 31 (ch1) and vibrator section 33 (ch3) were selected as the combination of the first vibrator section and the second vibrator section, and a first voltage signal was applied to vibrator section 31 (ch1) and a second voltage signal was applied to vibrator section 33 (ch3), thereby generating a flexural standing wave in the vibration mode shown in Fig. 3(B) in the liquid crystal section 4. Then, light (laser light) was transmitted through the liquid crystal section 4 in this state.

[0058] The light source 6 used in the evaluation experiment was a linearly polarized He-Ne laser device. In the evaluation experiment, the laser light from the light source 6 was passed through a polarizing plate 7 and a half-wave plate 8 and incident on the liquid crystal section 4 from the first substrate 41 side. Then, a photodetector 9 was placed at a point on the optical axis of the laser light where the amount of transmitted light was maximum (in this experiment, a point approximately 700 mm from the liquid crystal section 4), and the transmitted light that passed through the liquid crystal section 4 was measured. The photodetector 9 was configured to be movable in the directions of lines A-A' and B-B' in FIG. 3.

[0059] Figure 8 shows the change over time in the transmitted light intensity at the center of the liquid crystal section 4. Regarding time t in Figure 8, t=0 is the time when voltage signals (first voltage signal, second voltage signal) of opposite phases are applied to the vibrator section 31 (ch1) and the vibrator section 33 (ch3) to generate a non-axisymmetric flexural standing wave in the liquid crystal section 4.

[0060] As can be seen from Figure 8, the transmitted light intensity at the center of the liquid crystal section 4 decreases over time. This indicates that the transmitted light is diffused due to the generation of non-axisymmetric flexural standing waves in the liquid crystal section 4. Furthermore, as the voltage value (peak-to-peak value) of the voltage signal increases, the transmitted light intensity at the center of the liquid crystal section 4 decreases. This indicates that the amount of diffused light increases as the voltage value increases. In other words, with the ultrasonic liquid crystal device 1 and ultrasonic liquid crystal control method, the amount of diffused light can be controlled by controlling the voltage values ​​(peak-to-peak values) of the first voltage signal and the second voltage signal.

[0061] Figure 9 shows the transmitted light intensity distribution along line A-A'. Line A-A' is the same as line A-A' in Figures 3 and 6. Regarding the distance d in Figure 9, d = 0 is the center of the liquid crystal section 4 along line A-A'. The diameter of the liquid crystal section 4 is approximately 15 mm.

[0062] As can be seen from Figure 9, as the voltage value increases, the transmitted light intensity at the center of the liquid crystal section 4 decreases, and the transmitted light intensity distribution spreads slightly in the A-A' direction. This indicates that as the voltage value increases, the range of diffusion in the A-A' direction spreads. In other words, in the ultrasonic liquid crystal device 1 and ultrasonic liquid crystal control method, the range of diffusion can be controlled by controlling the voltage values ​​(peak-to-peak values) of the first voltage signal and the second voltage signal.

[0063] Although the ultrasonic liquid crystal device and ultrasonic liquid crystal control method according to the present invention have been described above as embodiments, the present invention is not limited to the above embodiments.

[0064] The ultrasonic vibrator of the present invention can be configured to include N vibrator sections (N is a multiple of 2) divided into N in the circumferential direction, and may include, for example, six or more vibrator sections that are a multiple of 2, or may include two vibrator sections. When the ultrasonic vibrator is configured with two vibrator sections, the ultrasonic liquid crystal device of the present invention does not need to perform selection processing, and the ultrasonic liquid crystal control method of the present invention does not need to include a selection processing step.

[0065] The drive control unit of the present invention performs a series of processes consisting of a selection process and a voltage control process multiple times, and can change the combination of the first transducer unit and the second transducer unit selected in the selection process. For example, in the ultrasonic liquid crystal device 1 of the above embodiment, the combination of the first transducer unit and the second transducer unit can be alternately selected between the combination of transducer unit 31 (ch1) and transducer unit 33 (ch3) and the combination of transducer unit 32 (ch2) and transducer unit 34 (ch4). The same applies to the ultrasonic liquid crystal control method of the present invention.

[0066] When an ultrasonic transducer is composed of six or more transducer units and a series of processes consisting of a selection process and a voltage control process are performed multiple times, the ultrasonic liquid crystal device of the present invention can select a combination of first and second transducer units so that a first line extending in a direction in which the first and second transducer units face each other (first direction) rotates. For example, when an ultrasonic transducer is composed of 12 transducer units (ch1 to ch12 clockwise), the combination of first and second transducer units can be switched sequentially as follows: ch1 and ch7, ch2 and ch8, ch3 and ch9, ch4 and ch10, ch5 and ch11, ch6 and ch12, ch1 and ch7, etc. By transmitting light through the liquid crystal unit while switching at high speed, the transmitted light appears to the human eye to be diffused in all directions on the emission surface. Alternatively, when the first line is rotated in ±90° increments, the transmitted light appears to be diffused in all directions on the emission surface. The same applies to the ultrasonic liquid crystal control method of the present invention.

[0067] The combination of the first transducer unit and the second transducer unit may be selected not only by rotating the first line as described above, but also by changing the first line to any angle at any timing as described below. For example, a reciprocating motion may be performed in which the first line reciprocates between a fixed angle (for example, ±90°) like a wiper, such as 0° → 30° → 60° → 90° → 60° → 30° → 0° → -30° → -60°, etc. Naturally, the combination of the first transducer unit and the second transducer unit may be selected in a manner other than a reciprocating motion, and may be changed as appropriate.

[0068] In the above embodiment, the first oscillator section and the second oscillator section are each composed of one oscillator section, but each of the first oscillator section and the second oscillator section can be composed of multiple oscillator sections. However, it is preferable that the number of oscillator sections constituting the first oscillator section and the number of oscillator sections constituting the second oscillator section are the same.

[0069] Furthermore, by configuring both the first transducer unit and the second transducer unit with multiple transducer units, even if the ultrasonic transducer includes four or more transducer units, a ring-shaped ultrasonic transducer can be formed using only the first transducer unit and the second transducer unit. For example, in the above embodiment, the transducer unit 31 (ch1) and the transducer unit 34 (ch4) may be selected as the first transducer unit, and the transducer unit 33 (ch3) and the transducer unit 32 (ch2) may be selected as the second transducer unit.

[0070] The ultrasonic liquid crystal device 1 of the above embodiment includes a liquid crystal section 4 in which the liquid crystal molecules 46 have a pretilt angle of 90°, but may also include a liquid crystal section in which the liquid crystal molecules have a pretilt angle of 0° or a horizontal alignment close to 0°. In this case, as in the above embodiment, a non-axisymmetric flexural standing wave can be generated. In the liquid crystal section, the alignment of the liquid crystal molecules changes at the antinodes of the flexural standing wave, but does not change (remains horizontally aligned) at the nodes of the flexural standing wave. As a result, the transmitted light passing through the liquid crystal section can be contracted (converged).

[0071] In the case of a horizontally aligned liquid crystal section, for example, when ultrasound is on (when ch1 and ch3 are driven), that is, when a first voltage signal is applied to one of transducer section 31 (ch1) and transducer section 33 (ch3) and a second voltage signal is applied to the other, the transmitted light contracts (converges) in the direction of line A-A'. The width of the transmitted light in the direction of line B-B' is approximately the same as when ultrasound is off. Also, when ultrasound is on (when ch2 and ch4 are driven), that is, when a first voltage signal is applied to one of transducer section 32 (ch2) and transducer section 34 (ch4) and a second voltage signal is applied to the other, the transmitted light contracts (converges) in the direction of line B-B'. The width of the transmitted light in the direction of line A-A' is approximately the same as when ultrasound is off.

[0072] In this way, in the case of a horizontally aligned liquid crystal section, the ultrasonic liquid crystal device and ultrasonic liquid crystal control method according to the present invention can contract (converge) the light transmitted through the liquid crystal section by generating a non-axisymmetric flexural standing wave in the liquid crystal section, and further, by changing the combination of the first vibrator section and the second vibrator section, it is also possible to change the direction of contraction (convergence) of the light transmitted through the liquid crystal section. Note that in the present invention, contraction (convergence) can be considered as diffusion in the negative direction.

[0073] In the above embodiment, an example has been described in which antinodes and nodes of the flexural standing wave are generated on a first line extending in a first direction, and nodal lines of the flexural standing wave are generated on a second line extending in a second direction, but there are multiple resonance modes that generate non-axisymmetric flexural standing waves in the liquid crystal section 4. Among these, there is also a resonance mode (a resonance mode different from the above embodiment) in which antinodes and nodes of the flexural standing wave are generated on the second line, and nodal lines of the flexural standing wave are generated on the first line. That is, in the liquid crystal section of the present invention, antinodes and nodes of the flexural standing wave are generated on one of the first line and the second line, and nodal lines of the flexural standing wave are generated on the other of the first line and the second line.

[0074] In the above embodiment, a first voltage signal having the resonant frequency of the liquid crystal section 4 is applied to the first vibrator section, and a second voltage signal having an opposite phase and a phase difference of 180° from that of the first voltage signal is applied to the second vibrator section. However, the second voltage signal does not need to be strictly 180° out of phase, and may be shifted, for example, within a range of ±15° from 180°.

[0075] In the above embodiment, the direction in which the first vibrator section and the second vibrator section face each other is defined as the first direction, the direction perpendicular to the first direction is defined as the second direction, and the angle between the first line and the second line is defined as 90°. However, the angle between the first line and the second line does not need to be strictly 90°. In other words, the first line and the second line only need to intersect under conditions in which an antinode and a node of a flexural standing wave are generated on one line and a nodal line of a flexural standing wave is generated on the other line. The angle between the first line and the second line only needs to be within a range of 90°±10°, for example. [Explanation of symbols]

[0076] 1 Ultrasonic LCD device 2 boards 3 Ultrasonic transducer 4 LCD section 5 Drive control unit 6 light source 7 Polarizing Plate 8 half wave plate 9. Photodetector

Claims

1. a substrate that transmits visible light; an ultrasonic transducer arranged in a ring shape on the substrate; a liquid crystal portion disposed inside the ultrasonic vibrator of the substrate; a drive control unit that applies a voltage signal to the ultrasonic transducer to generate ultrasonic waves; An ultrasonic liquid crystal device comprising: The ultrasonic transducer includes N transducer portions (N is a multiple of 2) divided into N portions in the circumferential direction, the N transducer units include a first transducer unit and a second transducer unit that are arranged opposite to each other, The drive control unit a voltage control process is performed by applying a first voltage signal having a resonance frequency of the liquid crystal portion to the first vibrator portion, and applying a second voltage signal having a phase opposite to that of the first voltage signal to the second vibrator portion, thereby generating a non-axisymmetric flexural standing wave in the liquid crystal portion; In the liquid crystal unit during the voltage control process, When a direction in which the first vibrator section and the second vibrator section face each other is defined as a first direction and a direction intersecting the first direction is defined as a second direction, on a first line extending in the first direction and a second line extending in the second direction, an antinode and a node of the flexural standing wave occur on one side, and a nodal line of the flexural standing wave occurs on the other side.

1. An ultrasonic liquid crystal device characterized by:

2. the N transducer units include four or more transducer units, The drive control unit Before the voltage control process, a selection process is performed to select the first vibrator unit and the second vibrator unit from the N vibrator units.

2. The ultrasonic liquid crystal device according to claim 1.

3. The drive control unit A series of processes consisting of the selection process and the voltage control process is performed a plurality of times, and the combination of the first vibrator unit and the second vibrator unit selected in the selection process is changed.

3. The ultrasonic liquid crystal device according to claim 2.

4. The drive control unit The combination is changed so that the first straight line rotates.

4. The ultrasonic liquid crystal device according to claim 3.

5. The drive control unit during the voltage control process The voltage of the voltage signal applied to the vibrator unit other than the first vibrator unit and the second vibrator unit is set to zero.

3. The ultrasonic liquid crystal device according to claim 2.

6. An ultrasonic liquid crystal control method using an ultrasonic liquid crystal device including a substrate that transmits visible light, an ultrasonic vibrator that is arranged in an annular shape on the substrate and includes N vibrator sections (N is a multiple of 2) that are divided into N sections in the circumferential direction, a liquid crystal section that is arranged inside the ultrasonic vibrator on the substrate, and a drive control section that applies a voltage signal to the ultrasonic vibrator to generate ultrasonic waves, the N transducer units include a first transducer unit and a second transducer unit that are arranged opposite to each other, a voltage control processing step of applying, by the drive control unit, a first voltage signal having a resonance frequency of the liquid crystal unit to the first vibrator unit, and applying, to the second vibrator unit, a second voltage signal having a phase opposite to that of the first voltage signal, thereby generating a non-axisymmetric flexural standing wave in the liquid crystal unit; In the voltage control processing step, when a direction in which the first vibrator section and the second vibrator section face each other is defined as a first direction and a direction intersecting the first direction is defined as a second direction, an antinode and a node of the flexural standing wave are generated on one side of a first straight line extending in the first direction of the liquid crystal section and a second straight line extending in the second direction, and a nodal line of the flexural standing wave is generated on the other side.

2. An ultrasonic liquid crystal control method according to claim 1, wherein:

7. the N transducer units include four or more transducer units, a selection process step of selecting the first vibrator unit and the second vibrator unit from the N vibrator units by the drive control unit before the voltage control process step; 7. The ultrasonic liquid crystal control method according to claim 6.

8. A series of processing steps consisting of the selection processing step and the voltage control processing step is performed a plurality of times, and the combination of the first vibrator unit and the second vibrator unit selected in the selection processing step is changed.

8. The ultrasonic liquid crystal control method according to claim 7.

9. The combination is changed so that the first straight line rotates.

9. The ultrasonic liquid crystal control method according to claim 8.

10. In the voltage control processing step, the voltage of the voltage signal applied to the vibrator unit other than the first vibrator unit and the second vibrator unit is set to zero.

8. The ultrasonic liquid crystal control method according to claim 7.

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