Display device

Abstract

The present invention comprises at least one parametric speaker (300) and a display (400). The at least one parametric speaker (300) reproduces an audible sound by means of modulation driving of an ultrasonic transducer in which a plurality of ultrasonic vibrators having a longitudinal direction following a horizontal direction are arranged so as to be aligned along the vertical direction. The display (400) has a display surface (410). The at least one parametric speaker (300) can reproduce an audible sound in a given region on the display-surface (410) side of the display (400). The vertical-direction range of the given region is wider than the horizontal-direction range thereof.

Description

display device

[0001] The present invention relates to a display device.

[0002] Japanese Patent Laid-Open Publication No. 2012-29096 (Patent Document 1) is a prior art document disclosing the configuration of an audio output device. The audio output device described in Patent Document 1 includes a parametric speaker, a first measurement unit, a second measurement unit, and a control unit. The parametric speaker generates ultrasonic waves toward a surrounding structure, reflects the waves off the structure, and then demodulates the waves to form a sound field in which audio is reproduced. The first measurement unit measures a first distance, which is the distance between the parametric speaker and the structure. The second measurement unit measures a second distance, which is the distance between the parametric speaker and a user who is located in a different direction from the structure as viewed from the parametric speaker. The control unit adjusts the angle of incidence of the ultrasonic waves with respect to the structure based on the measurement results of the first and second measurement units, thereby selectively delivering audio to the user.

[0003] JP 2012-29096 A

[0004] The audio output device described in Patent Document 1 does not take into consideration the directivity of the parametric speaker, and the configuration for delivering audio to the user is complex.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a display device that can stably produce audible sounds for users with a simple configuration by taking into account the directionality of a parametric speaker.

[0006] A display device according to the present invention comprises at least one parametric speaker and a display. The at least one parametric speaker reproduces audible sound by modulating and driving ultrasonic transducers in which a plurality of ultrasonic vibrators, each having a longitudinal direction along the horizontal direction, are arranged in a vertical direction. The display has a display surface. The at least one parametric speaker is capable of reproducing audible sound in a fixed area on the display surface side of the display. The vertical range of the fixed area is wider than the horizontal range.

[0007] According to the present invention, by taking into consideration the directivity of the parametric speaker, it is possible to enable a user to hear a stable audible sound with a simple configuration.

[0008] 9 is a longitudinal sectional view showing the configuration of an ultrasonic transducer having one ultrasonic vibrator. It is an exploded perspective view showing the configuration of an ultrasonic transducer having one ultrasonic vibrator. It is a perspective view showing the configuration of a frame included in an ultrasonic transducer having one ultrasonic vibrator. It is a sectional view showing the configuration of an ultrasonic vibrator. It is a perspective view showing a displacement state simulated and analyzed using the finite element method when an ultrasonic transducer having one ultrasonic vibrator is transmitting or receiving ultrasonic waves. It is a sectional view of the ultrasonic transducer of FIG. 5 as seen from the direction of the arrows VI-VI. It is a graph obtained by simulating and analyzing, using the finite element method, the transition of the resonance frequency of the first diaphragm when the longitudinal dimension is changed while the short side dimension inside the frame is fixed. It is a graph obtained by simulating and analyzing, using the finite element method, the transition of the sound pressure of ultrasonic waves transmitted from the ultrasonic transducer when the longitudinal dimension is changed while the short side dimension inside the frame is fixed. It is a side view showing the configuration of an ultrasonic transducer included in a parametric speaker according to a first embodiment of the present invention. It is a rear view of the ultrasonic transducer shown in FIG. 9 as seen from the direction of the arrow X. 1 is an exploded perspective view showing a stacked state in a process of stacking and bonding each component of the ultrasonic transducer included in the parametric speaker according to embodiment 1 of the present invention. FIG. 2 is a plan view showing a positional relationship in a first direction (X-axis direction) in a process of cutting a piezoelectric body of the ultrasonic transducer included in the parametric speaker according to embodiment 1 of the present invention. FIG. 3 is a perspective view showing a displacement state simulated and analyzed using the finite element method when the ultrasonic transducer included in the parametric speaker according to embodiment 1 of the present invention is transmitting or receiving ultrasonic waves. FIG. 4 is a perspective view showing a configuration of an ultrasonic element array according to a comparative example. FIG. 5 is a graph showing actual measurements of the transition of attenuation of sound pressure level over propagation distance in the ultrasonic transducer according to this embodiment and an ultrasonic element array according to the comparative example. FIG. 6 is a graph showing actual measurements of the directivity in the horizontal direction (longitudinal direction) of ultrasonic waves transmitted from the ultrasonic transducer according to this embodiment. FIG. 7 is a graph showing actual measurements of the directivity in the vertical direction (transverse direction) of ultrasonic waves transmitted from the ultrasonic transducer according to this embodiment.28 is a perspective view showing the configuration of a parametric speaker according to a first embodiment of the present invention. FIG. 29 is a graph showing actual measurements of the directivity of audible sound emitted from the parametric speaker according to the present embodiment. FIG. 30 is a schematic view showing the configuration of a display device according to the first embodiment of the present invention. FIG. 31 is a schematic view showing the configuration of a display device according to a first modification of the first embodiment of the present invention. FIG. 32 is a schematic view showing the relationship between the vertical directivity V of a parametric speaker provided in the display device according to the first embodiment of the present invention and the position of a user's ears. FIG. 33 is a schematic view showing the relationship between the horizontal directivity H of a parametric speaker provided in the display device according to the first embodiment of the present invention and the position of a user's ears. FIG. 34 is a schematic view showing the configuration of a display device according to a second modification of the first embodiment of the present invention. FIG. 35 is a schematic view showing the state in which the display of a display device according to a third modification of the first embodiment of the present invention is oriented horizontally. FIG. 36 is a schematic view showing the state in which the display of a display device according to the third modification of the first embodiment of the present invention is oriented vertically. FIG. 37 is a schematic view showing a display device according to a second embodiment of the present invention as viewed from the side. FIG. 38 is a schematic view showing a display device according to the second embodiment of the present invention as viewed obliquely from above on the front side. FIG. 39 is a schematic view showing the positional relationship between the parametric speaker shown in FIG. 28 and the user's ears as viewed from above. 1 is a schematic diagram showing a display device according to a modification of embodiment 2 of the present invention as viewed from the side; FIG. 2 is a schematic diagram showing a display device according to embodiment 3 of the present invention as viewed from the side; and FIG. 3 is a schematic diagram showing a display device according to a modification of embodiment 3 of the present invention as viewed from the side.

[0009] Hereinafter, display devices according to embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are designated by the same reference numerals, and description thereof will not be repeated.

[0010] (Embodiment 1) First, the configuration of an ultrasonic transducer having one ultrasonic vibrator will be described. Fig. 1 is a longitudinal cross-sectional view showing the configuration of an ultrasonic transducer having one ultrasonic vibrator. Fig. 2 is an exploded perspective view showing the configuration of an ultrasonic transducer having one ultrasonic vibrator. As shown in Figs. 1 and 2, an ultrasonic transducer 100 having one ultrasonic vibrator includes a first diaphragm 110, a frame 120, and an ultrasonic vibrator 130.

[0011] The first diaphragm 110 has a flat plate shape and is made of an aluminum alloy such as aluminum-containing duralumin, or a metal such as stainless steel. The thickness of the first diaphragm 110 is, for example, 0.1 mm or more and 0.2 mm or less.

[0012] The frame body 120 has a rectangular annular shape. The frame body 120 has a short side direction along a first direction (X-axis direction) and a long side direction along a second direction (Y-axis direction). The frame body 120 extends in the second direction (Y-axis direction). The axial direction of the frame body 120 is along a third direction (Z-axis direction). One end of the frame body 120 in the third direction (Z-axis direction) is bonded to the first diaphragm 110 with a bonding agent made of epoxy resin or the like.

[0013] The frame body 120 is formed from a metal such as an aluminum alloy or stainless steel, glass epoxy, or resin. From the viewpoint of suppressing changes in the characteristics of the ultrasonic transducer 100 due to temperature changes, the frame body 120 is preferably made of metal. On the other hand, from the viewpoint of lowering the frequency of the ultrasonic waves transmitted or received by the ultrasonic transducer 100 and from the viewpoint of miniaturizing the ultrasonic transducer 100, the frame body 120 is preferably made of resin. The thickness of the frame body 120 is, for example, 0.2 mm or more and 0.8 mm or less.

[0014] 3 is a perspective view showing the configuration of a frame body provided in an ultrasonic transducer having one ultrasonic vibrator. As shown in FIG. 3, the frame body 120 has a pair of long sides 121 extending in the second direction (Y-axis direction) and a pair of short sides 122 extending in the first direction (X-axis direction). The average distance between the short sides 122 is four or more times the shortest distance between the long sides 121. In other words, the longitudinal dimension La in the second direction (Y-axis direction) inside the frame body 120 is four or more times the lateral dimension Lb in the first direction (X-axis direction) inside the frame body 120.

[0015] The corners between the long side portion 121 and the short side portion 122 may be chamfered. Furthermore, the short side portion 122 does not have to be linear when viewed from the third direction (Z-axis direction), and may have an arc shape that is convex toward the inside of the frame body 120 or an arc shape that is convex toward the outside of the frame body 120.

[0016] The resonant frequency of the first diaphragm 110 can be adjusted by changing the short-side dimension Lb in the first direction (X-axis direction) inside the frame body 120. For example, when the resonant frequency of the first diaphragm 110 is set to 100 kHz or higher, the short-side dimension Lb is 1.5 mm or more and 3 mm or less.

[0017] The longitudinal dimension La in the second direction (Y-axis direction) inside the frame body 120 is four times or more the short dimension Lb, and from the viewpoint of increasing the sound pressure level of the ultrasound transmitted by the ultrasonic transducer 100, the longitudinal dimension La is, for example, 20 mm or more.

[0018] 1, the ultrasonic vibrator 130 is attached to the frame body 120 and faces the first vibration plate 110 with a gap therebetween. Specifically, the ultrasonic vibrator 130 is attached to the other end of the frame body 120 in the third direction (Z-axis direction), and faces the first vibration plate 110 with the inner space of the frame body 120 sandwiched therebetween.

[0019] FIG. 4 is a cross-sectional view showing the configuration of an ultrasonic vibrator. As shown in FIGS. 1, 2, and 4, the ultrasonic vibrator 130 is a piezoelectric element including a piezoelectric body 131. As shown in FIG. 4, the ultrasonic vibrator 130 includes two stacked piezoelectric bodies 131. The polarization directions Dp of the two piezoelectric bodies 131 are different from each other. Specifically, the polarization directions Dp of the two piezoelectric bodies 131 face each other in the third direction (Z-axis direction). The two piezoelectric bodies 131 are sandwiched between a first electrode 132 and a second electrode 133, and an intermediate electrode 134 is disposed between the two piezoelectric bodies 131. The first electrode 132 and the second electrode 133 are electrically connected to a processing circuit 140 capable of applying an AC voltage. The ultrasonic vibrator 130 is a so-called series-type bimorph piezoelectric vibrator. The total thickness of the two piezoelectric bodies 131 is, for example, 0.5 mm or more and 0.85 mm or less.

[0020] Fig. 5 is a perspective view showing a displacement state simulated and analyzed using the finite element method when an ultrasonic transducer having one ultrasonic vibrator transmits or receives ultrasonic waves. Fig. 6 is a cross-sectional view of the ultrasonic transducer of Fig. 5 as seen from the direction of the arrows along line VI-VI. The simulation analysis conditions were as follows: the thickness of the first diaphragm 110 was 0.1 mm, the combined thickness of the two piezoelectric bodies 131 was 0.8 mm, the longitudinal dimension La inside the frame body 120 was 20 mm, the lateral dimension Lb was 2 mm, and the thickness of the frame body 120 in the third direction (Z-axis direction) was 0.4 mm.

[0021] 5 and 6, in the vibration mode of the ultrasonic transducer 100, the first diaphragm 110 resonates in an opposite phase to the ultrasonic vibrator 130 in a third direction (Z-axis direction) perpendicular to the first diaphragm 110. That is, as shown in Fig. 6, the displacement direction of the resonant vibration Bm of the first diaphragm 110 and the displacement direction of the resonant vibration Bp of the ultrasonic vibrator 130 are opposite to each other in the third direction (Z-axis direction). The resonant frequencies of the first diaphragm 110 and the ultrasonic vibrator 130 are, for example, 100 kHz or higher.

[0022] In first diaphragm 110, middle portion 110c located at the middle in the longitudinal direction inside frame body 120 becomes the antinode of the resonant vibration, and end portions 110e located at both ends in the longitudinal direction inside frame body 120 become nodes of the resonant vibration. In other words, the portion of first diaphragm 110 located above the internal space of frame body 120 becomes the vibration region that resonates. The longitudinal dimension of the vibration region of first diaphragm 110 is the same as longitudinal dimension La inside frame body 120, and the lateral dimension of the vibration region of first diaphragm 110 is the same as lateral dimension Lb inside frame body 120.

[0023] Here, the relationship between the resonance frequency of the first diaphragm 110 and the longitudinal dimension La inside the frame 120 will be described.

[0024] 7 is a graph showing the results of a simulation analysis using the finite element method of the change in the resonant frequency of the first diaphragm 110 when the longitudinal dimension is changed while the transverse dimension inside the frame is fixed. In FIG. 7, the vertical axis represents the resonant frequency (kHz) of the first diaphragm 110, and the horizontal axis represents the longitudinal dimension La (mm) inside the frame 120. As a condition for the simulation analysis, the transverse dimension Lb inside the frame 120 was fixed at 2 mm.

[0025] 7, when the longitudinal dimension La inside the frame body 120 is 2 mm, the resonant frequency of the first diaphragm 110 is 220 kHz, and when the longitudinal dimension La increases to 8 mm and the longitudinal dimension of the vibration region of the first diaphragm 110 increases, the resonant frequency of the first diaphragm 110 decreases to 122 kHz. Thereafter, even when the longitudinal dimension La inside the frame body 120 exceeds 8 mm and the longitudinal dimension of the vibration region of the first diaphragm 110 further increases, the resonant frequency of the first diaphragm 110 remains approximately constant at 122 kHz.

[0026] In other words, the resonant frequency of the first vibration plate 110 is determined by the speed of sound of the first vibration plate 110 and the reflection of vibration with the frame body 120 as the fixed end, but when the longitudinal dimension La inside the frame body 120 exceeds four times the lateral dimension Lb, the influence of the lateral dimension Lb becomes dominant in terms of the reflection of vibration, and the state of vibration reflection does not change even if the longitudinal dimension La becomes even larger than four times the lateral dimension Lb.

[0027] Next, the results of a simulation analysis using the finite element method on the relationship between the sound pressure of the ultrasonic waves transmitted from the ultrasonic transducer 100 and the longitudinal dimension La inside the frame body 120 will be described.

[0028] Fig. 8 is a graph showing the results of a simulation analysis using the finite element method of the transition of the sound pressure of the ultrasonic waves transmitted from the ultrasonic transducer when the longitudinal dimension is changed while the lateral dimension inside the frame body is fixed. In Fig. 8, the vertical axis shows the sound pressure (Pa) transmitted from the ultrasonic transducer 100, and the horizontal axis shows the longitudinal dimension La (mm) inside the frame body 120. As a simulation analysis condition, the lateral dimension Lb inside the frame body 120 was fixed at 2 mm, and the sound pressure (Pa) was calculated at a position 30 cm away in the third direction (Z-axis direction) from the first diaphragm 110 on the front side of the ultrasonic transducer 100.

[0029] 8, as the longitudinal dimension La inside the frame body 120 increases, the sound pressure of the ultrasonic waves transmitted from the ultrasonic transducer 100 increases. This means that even when the longitudinal dimension of the vibration region of the first diaphragm 110 is increased, the entire vibration region of the first diaphragm 110 between both end portions 110e vibrates. In other words, the area of ​​the vibration region can be increased by the amount that the vibration region of the first diaphragm 110 is longer, and as a result, the change in air pressure due to the vibration of the first diaphragm 110 can be increased, thereby obtaining a high sound pressure.

[0030] In this way, the ultrasonic transducer 100 can increase the sound pressure while maintaining a substantially constant resonant frequency by increasing the longitudinal dimension of the vibration region of the first diaphragm 110. Furthermore, since there are nodal points at both ends in the longitudinal direction, the ends can be supported or fixed, making it easy to mount the ultrasonic transducer 100.

[0031] The ultrasonic transducer included in the parametric speaker according to the first embodiment of the present invention will be described below with reference to the drawings. The ultrasonic transducer included in the parametric speaker according to the first embodiment of the present invention differs from ultrasonic transducer 100 in that a plurality of ultrasonic vibrators are arranged in an array, and therefore, the description of the configuration that is the same as that of ultrasonic transducer 100 will not be repeated.

[0032] Fig. 9 is a side view showing the configuration of an ultrasonic transducer provided in the parametric speaker according to embodiment 1 of the present invention, Fig. 10 is a rear view of the ultrasonic transducer shown in Fig. 9 as seen from the direction of arrow X.

[0033] 9 and 10 , in an ultrasonic transducer 200 provided in the parametric speaker according to the first embodiment of the present invention, the ultrasonic transducers 100 according to the first embodiment are arranged in an array in a first direction (X-axis direction) and are integrally configured. The ultrasonic transducer 200 includes a first diaphragm 210, a plurality of frame bodies 220, and a plurality of ultrasonic vibrators 130. The plurality of frame bodies 220 are bonded to the first diaphragm 210, and the plurality of ultrasonic vibrators 130 are bonded to the plurality of frame bodies 220, respectively.

[0034] Here, a description will be given of a manufacturing method of the ultrasonic transducer 200. Fig. 11 is an exploded perspective view showing a stacked state in the process of stacking and bonding the components of the ultrasonic transducer included in the parametric speaker according to the first embodiment of the present invention.

[0035] 11 , the first diaphragm 210 has a flat plate shape, and a plurality of slits 211 extending in the second direction (Y-axis direction) are formed at intervals in the first direction (X-axis direction). The first diaphragm 210 is made of an aluminum alloy such as aluminum-containing duralumin, or a metal such as stainless steel. In this embodiment, the first diaphragm 210 is made of stainless steel. The plurality of slits 211 are formed by etching, cutting, or the like.

[0036] Each of the multiple frame bodies 220 has a rectangular ring shape. Each of the multiple frame bodies 220 has a short side direction along a first direction (X-axis direction) and a long side direction along a second direction (Y-axis direction). Each of the multiple frame bodies 220 extends in the second direction (Y-axis direction). The axial direction of each of the multiple frame bodies 220 is along a third direction (Z-axis direction). Each of the multiple frame bodies 220 has a pair of long side portions 221 extending in the second direction (Y-axis direction) and a pair of short side portions 222 extending in the first direction (X-axis direction). The shortest distance between the long side portions 221 is four or more times the shortest distance between the short side portions 222.

[0037] The multiple frame bodies 220 are arranged side by side in a first direction (X-axis direction). A slit 223 is formed between adjacent frame bodies 220 in the first direction (X-axis direction). The multiple slits 223 are formed by etching, cutting, or the like. Adjacent long side portions 221 of adjacent frame bodies 220 in the first direction (X-axis direction) are separated from each other by the slits 223.

[0038] The frame bodies 220 adjacent to each other in the first direction (X-axis direction) are connected to each other at the short side portions 222. That is, among the multiple frame bodies 220, the frame bodies 220 adjacent to each other in the short side direction are connected to each other at both ends in the longitudinal direction.

[0039] Each of the plurality of frame bodies 220 is formed from a metal such as an aluminum alloy or stainless steel, glass epoxy, resin, etc. In this embodiment, the plurality of frame bodies 220 are formed from a single thin plate, but this is not limiting, and the plurality of frame bodies 220, each formed from a plurality of thin plates, may be integrated by joining the short side portions 222 of the frame bodies 220 together.

[0040] In this embodiment, each of the plurality of ultrasonic vibrators 130 includes two stacked piezoelectric bodies 131. As shown in Fig. 11, the two piezoelectric bodies 131 constituting the plurality of ultrasonic vibrators 130 are stacked and bonded in the form of two thin plates.

[0041] 12 is a plan view showing the positional relationship in the first direction (X-axis direction) in the process of cutting the piezoelectric body of the ultrasonic transducer included in the parametric speaker according to Embodiment 1 of the present invention. In FIG. 12, only one piezoelectric body 131 is shown.

[0042] 12, the slits 211 and 223 are arranged at the same position in the first direction (X-axis direction) so as to overlap with each other in the third direction (Z-axis direction). The piezoelectric body 131 is cut and divided by a dicer or the like along a plurality of cut lines LC extending in the second direction (Y-axis direction) so as to overlap with the slits 211 and 223 in the third direction (Z-axis direction). As a result, the ultrasonic transducer 200 shown in FIGS. 9 and 10 is formed.

[0043] FIG. 13 is a perspective view showing a displacement state obtained by simulation analysis using the finite element method when the ultrasonic transducer included in the parametric speaker according to the first embodiment of the present invention transmits or receives ultrasonic waves.

[0044] 13 , in the first diaphragm 210, intermediate portions 210c located at the middle of the longitudinal direction inside each frame body 220 become antinodes of the resonant vibration, and end portions 210e located at both ends of the longitudinal direction inside each frame body 220 become nodes of the resonant vibration. That is, the portions of the first diaphragm 210 located above the inner spaces of each frame body 220 become vibration regions that resonate. The longitudinal dimension of the vibration region of the first diaphragm 210 is the same as the longitudinal dimension inside each frame body 220, and the lateral dimension of the vibration region of the first diaphragm 210 is the same as the lateral dimension inside each frame body 220.

[0045] Since the ultrasonic transducer 100 has nodal points at both ends in the second direction (Y-axis direction), which is the longitudinal direction, even if the ultrasonic transducers 100 are connected to each other at the both ends to form an array to constitute the ultrasonic transducer 200 according to embodiment 1, the resonant vibration of each ultrasonic transducer 100 is not inhibited. Therefore, by increasing the number of ultrasonic transducers 100 that constitute the ultrasonic transducer 200 according to embodiment 1, the sound pressure level can be easily increased.

[0046] Here, we will explain the results of actual measurements of the relationship between the frequency of ultrasonic waves and the attenuation of the sound pressure level due to the propagation distance. We actually measured the transition of attenuation due to the propagation distance of a 4 kHz audible sound reproduced from ultrasonic waves with a resonant frequency of 146 kHz transmitted from the ultrasonic transducer 200 according to this embodiment, and a 4 kHz audible sound reproduced from ultrasonic waves with a resonant frequency of 40 kHz transmitted from the ultrasonic element array according to the comparative example.

[0047] Fig. 14 is a perspective view showing the configuration of an ultrasonic element array according to a comparative example. As shown in Fig. 14, in the ultrasonic element array according to the comparative example, 50 ultrasonic elements 900 are arranged in a matrix at intervals.

[0048] Fig. 15 is a graph showing actual measurements of the transition of attenuation of sound pressure level over propagation distance in the ultrasonic transducer according to this embodiment and an ultrasonic element array according to a comparative example. In Fig. 15, the vertical axis represents sound pressure level (dB) and the horizontal axis represents propagation distance (cm). The solid line represents data for the ultrasonic transducer 200 according to this embodiment, and the dotted line represents data for the ultrasonic element array according to the comparative example. The sound pressure level is a value normalized by setting the sound pressure level of an audible sound with a frequency of 4 kHz at a point 30 cm away in the third direction (Z-axis direction) from the front of each of the ultrasonic transducer and the ultrasonic element array to 0 dB.

[0049] 15, the audible sound reproduced from the ultrasonic waves having a resonant frequency of 146 kHz transmitted from the ultrasonic transducer 200 according to the present embodiment was attenuated more due to the propagation distance than the audible sound reproduced from the ultrasonic waves having a resonant frequency of 40 kHz transmitted from the ultrasonic element array according to the comparative example. This is because high-frequency ultrasonic waves are easily absorbed by the air as heat, and therefore audible sounds reproduced using high-frequency ultrasonic waves as carrier waves are attenuated more due to the propagation distance.

[0050] In this way, the ultrasonic transducer 200 according to this embodiment, which transmits ultrasonic waves at high frequencies of 100 kHz or higher, can suppress sound from traveling unnecessarily far and suppress sound leakage due to unnecessary reflections, thereby reproducing audible sound only in a limited space. Furthermore, the ultrasonic transducer 200 can increase the attenuation of audible sound over the propagation distance without requiring a configuration for transmitting an opposite-phase carrier wave, allowing for a simple and compact configuration. Furthermore, because ultrasonic waves at high frequencies of 100 kHz or higher are outside the audible range of animals such as dogs and cats, the effects on these animals can be suppressed.

[0051] As shown in Figure 15, in order for audible sound to attenuate after a propagation distance of 30 cm, the Rayleigh distance must be set to 30 cm or less. The Rayleigh distance R0 is given by R0 = (k × a 2 ) / 2, where k is the wave number and a is the radius of the sound source. Therefore, if the speed of sound in air is 340 m / s, when the ultrasonic frequency is 100 kHz, the longitudinal dimension of the vibration region of first diaphragm 210 is 36 mm or less, when the ultrasonic frequency is 150 kHz, the longitudinal dimension of the vibration region of first diaphragm 210 is 29.4 mm or less, and when the ultrasonic frequency is 200 kHz, the longitudinal dimension of the vibration region of first diaphragm 210 is 25.5 mm or less. When the ultrasonic frequency is 100 kHz or more, the longitudinal dimension La is 4 to 24 times the lateral dimension Lb.

[0052] Fig. 16 is a graph showing actual measurements of the horizontal (longitudinal) directivity of ultrasonic waves transmitted from the ultrasonic transducer according to this embodiment. In Fig. 16, the vertical axis represents the sound pressure level (dB) of the ultrasonic waves transmitted from the ultrasonic transducer 200, and the horizontal directivity angle is shown in a semicircular shape.

[0053] 16, the horizontal directionality of the ultrasonic waves transmitted from the ultrasonic transducer 200 is narrow with almost no side lobes generated. This is because the vibration area of ​​the first diaphragm 210 is continuous in the longitudinal direction, so that the sound sources are continuously connected in the longitudinal direction, and interference between the sound sources is continuous, making it difficult for side lobes to be generated.

[0054] Fig. 17 is a graph showing actual measurements of the directivity in the vertical direction (short side direction) of ultrasonic waves transmitted from the ultrasonic transducer according to this embodiment. In Fig. 17, the vertical axis shows the sound pressure level (dB) of the ultrasonic waves transmitted from the ultrasonic transducer 200, and the vertical directivity angle is shown in a semicircular shape.

[0055] 17, side lobes are generated and the vertical directivity of the ultrasonic waves transmitted from the ultrasonic transducer 200 is wide. This is because the vibration area of ​​the first diaphragm 210 is discontinuous in the short side direction, resulting in a state in which sound sources are intermittently present in the short side direction, and interference between the sound sources becomes rough, making it easier for side lobes to be generated.

[0056] Fig. 18 is a perspective view showing the configuration of a parametric speaker according to the first embodiment of the present invention. As shown in Fig. 18, the parametric speaker 300 according to the first embodiment of the present invention has an ultrasonic transducer 200 in which a plurality of ultrasonic vibrators 130, each having a longitudinal direction along the horizontal direction, are arranged in a vertical direction. The parametric speaker 300 is capable of modulating the ultrasonic waves emitted from the ultrasonic transducer 200 by modulating and driving the ultrasonic transducer 200, thereby reproducing audible sound. Modulation methods include AM modulation (amplitude modulation) and FM modulation (frequency modulation).

[0057] The parametric speaker 300 further includes a support 310 that supports the ultrasonic transducer 200. The support 310 includes a pair of joints 311 joined to node points at both longitudinal ends of the ultrasonic transducer 200, and a plurality of connection portions 312 that connect the pair of joints 311 to each other. The pair of joints 311 extend in a first direction (X-axis direction). Because the pair of joints 311 are joined to node points at both longitudinal ends of the ultrasonic transducer 200, the ultrasonic transducer 200 can be supported or fixed without inhibiting vibration of the first diaphragm 210. The plurality of connection portions 312 extend in a second direction (Y-axis direction) while being spaced apart from each other in the first direction (X-axis direction). The plurality of connection portions 312 are positioned at a distance from each other with respect to the first diaphragm 210 so as not to inhibit transmission or reception of ultrasonic waves by the ultrasonic transducer 200.

[0058] Due to the influence of the directionality of the ultrasonic waves transmitted from the ultrasonic transducer 200 shown in Figures 16 and 17, the horizontal directivity H of the audible sound reproduced by the parametric speaker 300 becomes narrower and the vertical directivity V becomes wider, as shown in Figure 18.

[0059] Fig. 19 is a graph showing actual measurements of the directionality of audible sound emitted from the parametric speaker according to this embodiment. In Fig. 19, the vertical axis represents the sound pressure level (dB) of the audible sound emitted from the parametric speaker 300, and the semicircular shape represents the directivity angle. The measurement conditions were as follows: the length of the ultrasonic vibrator 130 in the second direction (Y-axis direction) was 30 mm; the length of the vibration region in the first direction (X-axis direction), which is the short side direction of the ultrasonic transducer 200, was 28.4 mm; the resonant frequency of the ultrasonic vibrator 130 was 100 kHz; the sound pressure level is a value normalized to 0 dB, which is the sound pressure level of audible sound with a frequency of 1 kHz at a point 30 cm away from the front of the ultrasonic transducer in the third direction (Z-axis direction).

[0060] 19, the horizontal directivity H of the audible sound reproduced by the parametric speaker 300 had an angle width of 52° up to -6 dB, and the vertical directivity V had an angle width of 75° up to -6 dB. From this result, it was confirmed that the horizontal directivity H of the audible sound reproduced by the parametric speaker 300 was narrow, and the vertical directivity V was wide.

[0061] FIG. 20 is a schematic diagram showing the configuration of a display device according to the first embodiment of the present invention. As shown in FIG. 20 , the display device according to the first embodiment of the present invention includes two parametric speakers 300 and a display 400. Note that the number of parametric speakers 300 included in the display device is not limited to two and may be at least one. The display device may be, for example, a television, a personal computer, or any of various operation terminal devices. The display 400 has a display surface 410. The display surface 410 also includes the surface of a frame surrounding the display area. In this embodiment, the two parametric speakers 300 are disposed below the display surface 410. The two parametric speakers 300 can reproduce audible sounds in a certain area on the display surface 410 side of the display 400. As a result, audible sounds are delivered from the two parametric speakers 300 to both ears 2 of a user 1.

[0062] Fig. 21 is a schematic diagram showing the configuration of a display device according to a first modification of embodiment 1 of the present invention. As shown in Fig. 21, the display device according to the first modification of embodiment 1 of the present invention includes two parametric speakers 300 and a display 500. The display device according to the first modification is a laptop computer, and the display 500 has a display surface 510. In this modification, the two parametric speakers 300 are arranged on an upper surface 520 of the housing of the main body of the laptop computer. The two parametric speakers 300 can reproduce audible sounds in a certain area on the display surface 510 side of the display 500. As a result, audible sounds are delivered from the two parametric speakers 300 to both ears 2 of a user 1.

[0063] 22 is a schematic diagram showing the relationship between the vertical directivity V of the parametric speaker included in the display device according to the first embodiment of the present invention and the position of the user's ear. As shown in Fig. 22, the vertical position of the ear 2 of the user 1 relative to the display surface 410 of the display 400 can vary relatively greatly depending on the posture of the user 1. Because the vertical directivity V of the audible sound reproduced by the parametric speaker 300 is wide, it is possible to deliver the audible sound to the entire vertical displacement range of the ear 2 of the user 1.

[0064] 23 is a schematic diagram showing the relationship between the horizontal directivity H of the parametric speaker included in the display device according to the first embodiment of the present invention and the position of the user's ear. As shown in Fig. 23, the horizontal position of the ear 2 of the user 1 relative to the display surface 410 of the display 400 is relatively small because the user 1 is positioned so as to face the center of the display surface 410. Therefore, even if the horizontal directivity H of the audible sound reproduced by the parametric speaker 300 is narrow, it is possible to deliver the audible sound to the entire horizontal displacement range of the ear 2 of the user 1.

[0065] 22 and 23 , the parametric speaker 300 can reproduce audible sound in a fixed area on the display surface 410 side of the display 400. The vertical range of this fixed area is wider than the horizontal range. In this way, the display device according to the first embodiment of the present invention can stably reproduce audible sound for the user 1 with a simple configuration by taking into account the directionality of the parametric speaker 300.

[0066] In this embodiment, the frequency of the carrier wave radiated from the parametric speaker 300 is 100 kHz or higher. In other words, the frequency of the ultrasonic waves transmitted from the ultrasonic transducer 200 is 100 kHz or higher. This prevents audible sound from reaching unnecessarily far distances from the parametric speaker 300 and suppresses sound leakage due to unnecessary reflections, making it possible to deliver audible sound only to a limited space.

[0067] Fig. 24 is a schematic diagram showing the configuration of a display device according to a second modified example of embodiment 1 of the present invention. As shown in Fig. 24, in the display device according to the second modified example of embodiment 1 of the present invention, two parametric speakers 300 are arranged above a display surface 410. The two parametric speakers 300 are configured to be movable in the vertical direction. When the parametric speakers 300 are in use, they are pulled out to the outside of the display 400, and when the parametric speakers 300 are not in use, they are stored on the back side of the display 400, opposite the display surface 410.

[0068] When two parametric speakers 300 are mounted, the distance between the centers of the parametric speakers 300 is, for example, 15 cm, corresponding to the distance between the ears 2. When one parametric speaker 300 is mounted, the parametric speaker 300 is placed above the center of the display 400.

[0069] Fig. 25 is a schematic diagram showing a state in which the display of a display device according to a third modified example of embodiment 1 of the present invention is oriented horizontally. Fig. 26 is a schematic diagram showing a state in which the display of a display device according to a third modified example of embodiment 1 of the present invention is oriented vertically. As shown in Figs. 25 and 26 , in the display device according to the third modified example of embodiment 1 of the present invention, the display surface 410 is rectangular having long sides 411 and short sides 412. The display 400 is configured to be rotatable so that either the long side 411 or the short side 412 is selectively aligned horizontally.

[0070] At least one parametric speaker is provided on each of the long sides 411 and the short sides 412. In this modification, four parametric speakers are provided, one on each of the long sides 411 and the short sides 412. Specifically, two parametric speakers 300a are provided on each of the two long sides 411, and two parametric speakers 300b are provided on each of the two short sides 412.

[0071] As shown in FIG. 25, when the display 400 is in the landscape orientation, the parametric speaker 300b installed on the short side 412 is operated, and the parametric speaker 300a installed on the long side 411 is stopped.

[0072] As shown in FIG. 26, when the display 400 is in the portrait orientation, the parametric speaker 300a installed on the long side 411 is operated, and the parametric speaker 300b installed on the short side 412 is stopped.

[0073] In this modification, it is possible to stably deliver audible sounds to the ears 2 of the user 1 regardless of the orientation of the rotatable display 400 shown in FIGS.

[0074] (Embodiment 2) A display device according to embodiment 2 of the present invention will be described below with reference to the drawings. The display device according to embodiment 2 of the present invention differs from the display device according to embodiment 1 of the present invention in that the carrier wave is reflected by the mounting surface, and therefore the description of the configuration that is the same as that of the display device according to embodiment 1 of the present invention will not be repeated.

[0075] Fig. 27 is a schematic diagram showing a display device according to embodiment 2 of the present invention as viewed from the side. Fig. 28 is a schematic diagram showing a display device according to embodiment 2 of the present invention as viewed from diagonally above the front side.

[0076] 27 and 28 , a display device according to a second embodiment of the present invention includes two parametric speakers 300 and a display 400. The display device is placed on a mounting surface 600. In this embodiment, the two parametric speakers 300 are disposed below a display surface 410 and face obliquely relative to the mounting surface 600. The display device according to the second embodiment of the present invention reproduces audible sound in a certain area by carrier waves emitted from the two parametric speakers 300 and reflected by the mounting surface 600.

[0077] 27 , the angle of incidence and angle of reflection of the carrier wave radiated from the parametric speaker 300 with respect to the mounting surface 600 is θ1. Let L1 be the vertical distance from the mounting surface 600 to the center of the parametric speaker 300, L2 be the vertical distance from the mounting surface 600 to the ear 2 of user 1, and (L3 + L4) be the horizontal distance from the parametric speaker 300 to the ear 2 of user 1. For example, when the vertical distance L1 is 10 cm, the vertical distance L2 is 30 cm, and the horizontal distance (L3 + L4) is 70 cm, θ1 is 35.5°. When the vertical distance L1 is 20 cm, the vertical distance L2 is 50 cm, and the horizontal distance (L3 + L4) is 30 cm, θ1 is 69.4°.

[0078] 29 is a schematic diagram showing the positional relationship between the parametric speakers 300 shown in FIG. 28 and the user's ears, viewed from above. As shown in FIGS. 28 and 29, when the horizontal distance L6 between the centers of the parametric speakers 300 is greater than the horizontal distance L5 between the ears 2 of the user 1, it is preferable to tilt the orientation of the parametric speakers 300 inward with respect to the front direction of the display surface 410. For example, when the horizontal distance L5 is 15 cm, the horizontal distance L6 is 50 cm, and the distance L7 from the center of the parametric speaker 300 to the ear 2 of the user 1 in the front direction of the display surface 410 is 70 cm, the tilt angle θ2 of the parametric speaker 300 with respect to the front direction of the display surface 410 is 14°. When the horizontal distance L5 is 15 cm, the horizontal distance L6 is 70 cm, and the distance L7 from the center of the parametric speaker 300 to the ear 2 of the user 1 in the front direction of the display surface 410 is 30 cm, the inclination angle θ2 of the parametric speaker 300 with respect to the front direction of the display surface 410 is 42.5°.

[0079] Fig. 30 is a schematic diagram showing a display device according to a modified example of the second embodiment of the present invention, as viewed from the side. As shown in Fig. 30, the display device according to the modified example of the second embodiment of the present invention includes a parametric speaker 300 and a display 500. The display device is placed on a mounting surface 600. In this modified example, the parametric speaker 300 is disposed on a side surface 530 of the housing of the main body of the laptop computer that faces the user 1, and faces obliquely relative to the mounting surface 600. The display device according to the modified example of the second embodiment of the present invention reproduces audible sound in a certain area by a carrier wave emitted from the parametric speaker 300 and reflected by the mounting surface 600.

[0080] As shown in Figure 30, the angle of incidence and angle of reflection of the carrier wave radiated from the parametric speaker 300 with respect to the mounting surface 600 is θ1. Let L1 be the vertical distance from the mounting surface 600 to the center of the parametric speaker 300, L2 be the vertical distance from the mounting surface 600 to the ear 2 of user 1, and (L3 + L4) be the horizontal distance from the parametric speaker 300 to the ear 2 of user 1. For example, when the vertical distance L1 is 1 cm, the vertical distance L2 is 30 cm, and the horizontal distance (L3 + L4) is 30 cm, θ1 is 45.9°. When the vertical distance L1 is 1 cm, the vertical distance L2 is 50 cm, and the horizontal distance (L3 + L4) is 10 cm, θ1 is 88.9°.

[0081] In the display devices according to the second embodiment and the modified example of the present invention, audible sound is reproduced in a certain area by carrier waves emitted from two parametric speakers 300 and reflected by the mounting surface 600. This makes it possible to prevent the placement of the parametric speakers 300 from impairing the design of the display device. It also makes it possible to prevent the placement of the parametric speakers 300 from impeding the implementation of user interface functions in the display device. Furthermore, because the parametric speakers 300 face obliquely relative to the mounting surface 600, it is possible to prevent foreign matter such as dust from accumulating inside the parametric speakers 300.

[0082] (Embodiment 3) A display device according to embodiment 3 of the present invention will be described below with reference to the drawings. The display device according to embodiment 3 of the present invention differs from the display device according to embodiment 1 of the present invention in that the carrier wave is reflected by a movable reflector, and therefore, description of the configuration that is the same as that of the display device according to embodiment 1 of the present invention will not be repeated.

[0083] Fig. 31 is a schematic diagram showing a display device according to embodiment 3 of the present invention as seen from the side. As shown in Fig. 31, the display device according to embodiment 3 of the present invention has a movable reflector 700 provided on a display 400. In this embodiment, the movable reflector 700 is disposed below a display surface 410 and faces obliquely toward the parametric speaker 300. The movable reflector 700 is configured to be swingable so that the angle at which it faces the parametric speaker 300 can be changed.

[0084] The display device according to the third embodiment of the present invention reproduces an audible sound in a certain area by a carrier wave emitted from a parametric speaker 300 and reflected by a movable reflector 700 .

[0085] Fig. 32 is a schematic diagram showing a display device according to a modified example of the third embodiment of the present invention, as viewed from the side. As shown in Fig. 32, in the display device according to the modified example of the third embodiment of the present invention, the display 500 is configured to be swingable so that the angle between the display surface 510 and the parametric speaker 300 can be changed. In this modified example, the parametric speaker 300 is disposed on a side surface 540 of the laptop computer's main body housing on the display 500 side, and faces obliquely relative to the display surface 510. The display device according to the modified example of the third embodiment of the present invention reproduces audible sound in a certain area by a carrier wave emitted from the parametric speaker 300 and reflected by the display surface 510.

[0086] In the display devices according to the third embodiment and the modified example of the present invention, audible sound is reproduced in a fixed area by a carrier wave emitted from the parametric speaker 300 and reflected by the movable reflector 700 or the display surface 510. This makes it possible to prevent the placement of the parametric speaker 300 from impairing the design of the display device. It also makes it possible to prevent the placement of the parametric speaker 300 from impeding the implementation of user interface functions in the display device. Furthermore, the position of the fixed area in which the audible sound is reproduced can be easily changed, allowing the user 1 to hear the audible sound stably.

[0087] (Note) It will be understood by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.

[0088] <1> A display device comprising: at least one parametric speaker that reproduces audible sound by modulating and driving ultrasonic transducers in which a plurality of ultrasonic vibrators having a longitudinal direction along the horizontal direction are arranged in a vertical direction; and a display having a display surface, wherein the at least one parametric speaker is capable of reproducing audible sound in a fixed area on the display surface side of the display, and the vertical range of the fixed area is wider than the horizontal range.

[0089] <2> The display device according to <1>, wherein the frequency of the carrier wave radiated from the at least one parametric speaker is 100 kHz or higher.

[0090] <3> The display device according to <1> or <2>, wherein the display device is placed on a placement surface, and reproduces audible sound in the certain area by a carrier wave radiated from the at least one parametric speaker and reflected by the placement surface.

[0091] <4> The display device according to <1> or <2>, wherein the display is provided with a movable reflector configured to be swingable so that the facing angle with the at least one parametric speaker can be changed, and an audible sound is reproduced in the certain area by a carrier wave emitted from the at least one parametric speaker and reflected by the movable reflector.

[0092] <5> The display device according to <1> or <2>, wherein the display is configured to be swingable so that a facing angle between the display surface and the at least one parametric speaker can be changed, and an audible sound is reproduced in the certain area by a carrier wave emitted from the at least one parametric speaker and reflected by the display surface.

[0093] <6> The display device according to any one of <1> to <4>, wherein the display surface is a rectangle having long and short sides, the display is configured to be rotatable so that either the long side or the short side is selectively aligned horizontally, and at least one parametric speaker is installed on each of the long and short sides.

[0094] In the above-described embodiments, configurations that can be combined may be combined with each other.

[0095] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0096] 1 User, 2 Ear, 100, 200 Ultrasonic transducer, 110, 210 First diaphragm, 110c, 210c Middle portion, 110e, 210e End portion, 120, 220 Frame body, 121, 221 Long side portion, 122, 222 Short side portion, 130 Ultrasonic vibrator, 131 Piezoelectric body, 132 First electrode, 133 Second electrode, 134 Intermediate electrode, 140 Processing circuit, 211, 223 Slit, 300, 300a, 300b Parametric speaker, 310 Support, 311 Joint, 312 Connection portion, 400, 500 Display, 410, 510 Display surface, 411 Long side, 412 Short side, 520 Top surface, 530, 540 Side, 600 Mounting surface, 700 movable reflector, 900 ultrasonic element, L1, L2 vertical distance, L5, L6 horizontal distance, L7 distance, LC cut line, La longitudinal dimension, Lb lateral dimension, R0 Rayleigh distance.

Claims

1. A display device comprising: at least one parametric speaker that reproduces audible sound by modulating and driving ultrasonic transducers in which multiple ultrasonic vibrators having a longitudinal direction along the horizontal direction are arranged in a vertical direction; and a display having a display surface, wherein the at least one parametric speaker is capable of reproducing audible sound in a fixed area on the display surface side of the display, and the vertical range of the fixed area is wider than its horizontal range.

2. The display device according to claim 1, wherein the frequency of the carrier wave radiated from said at least one parametric speaker is 100 kHz or higher.

3. The display device according to claim 1 or 2, which is placed on a support surface and reproduces audible sound in the certain area by a carrier wave emitted from the at least one parametric speaker and reflected by the support surface.

4. A display device as described in claim 1 or claim 2, wherein the display is provided with a movable reflector configured to be oscillated so that the facing angle with the at least one parametric speaker can be changed, and an audible sound is reproduced in the certain area by a carrier wave emitted from the at least one parametric speaker and reflected by the movable reflector.

5. A display device as described in claim 1 or claim 2, wherein the display is configured to be oscillating so that the facing angle between the display surface and the at least one parametric speaker can be changed, and an audible sound is reproduced in the certain area by a carrier wave emitted from the at least one parametric speaker and reflected by the display surface.

6. A display device as claimed in any one of claims 1 to 4, wherein the display surface is a rectangle having long and short sides, the display is configured to be rotatable so that either the long side or the short side is selectively aligned horizontally, and the at least one parametric speaker is provided at each of the long side and the short side.

Images