Audio device, driving method, and display device

Abstract

The present technology relates to an audio device, a driving method, and a display device with which a sufficient sound pressure level can be obtained over a wider frequency band. The audio device is provided with a vibrating plate, an electromotive excitation portion that outputs sound by vibrating the vibrating plate, and a piezoelectric excitation portion that outputs sound by vibrating the vibrating plate. The present technology can be applied to a display device.

Description

TECHNICAL FIELD

[0001] The present technology relates to an audio device and a driving method thereof and a display device, and more particularly, to an audio device and a driving method thereof and a display device configured to obtain sufficient sound pressure level in a wider frequency band. BACKGROUND

[0002] Conventionally, a speaker system in which an exciter is arranged at the back of a television display to vibrate the display and the display itself functions as a speaker vibration plate has been proposed (see, for example, Patent Literature 1 and Patent Literature 2).

[0003] In such a speaker system, the display is vibrated by an electric or piezoelectric exciter, and acoustic energy is emitted from the surface of the display.

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent No. 6489291

[0006] Patent Literature 2: Japanese Patent No. 4317957 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the above-described technology, it is difficult to obtain sufficient sound pressure level in a wider frequency band.

[0009] For example, in a speaker system using an electric exciter, in a case where the vibration plate (diaphragm) is heavy, the sound pressure level decreases at high frequencies, making it difficult to obtain sufficient volume.

[0010] Further, in a case where the area of the vibration plate is large, the improvement direction at high frequencies, i.e., the directivity angle becomes small, and the sound pressure level in the high frequency band further decreases at a position away from the front face of the speaker system (more specifically, the electric exciter) in the lateral direction.

[0011] Further, in a case where a piezoelectric exciter is used, it is difficult to obtain sufficient sound pressure level at low frequencies.

[0012] As described above, in a speaker system in which an exciter is arranged at the back of a television display and acoustic energy is emitted from the surface of the display, it is difficult to obtain sufficient sound pressure level in a sound reproduction frequency band having a larger directivity angle.

[0013] The present technology is made in view of such circumstances, and aims to obtain sufficient sound pressure level in a wider frequency band.

[0014] SOLUTION TO PROBLEM

[0015] The audio device according to the first aspect of the present technology includes: a diaphragm; an electromotive vibrator that vibrates the diaphragm to output sound; and a piezoelectric vibrator that vibrates the diaphragm to output sound.

[0016] The driving method according to the first aspect of the present technology is a driving method of an audio device including a diaphragm, an electromotive vibrator, and a piezoelectric vibrator, and the driving method includes: vibrating the diaphragm by the electromotive vibrator to output sound; and vibrating the diaphragm by the piezoelectric vibrator to output sound.

[0017] According to the first aspect of the present technology, in an audio device including a diaphragm, an electromotive vibrator, and a piezoelectric vibrator, the electromotive vibrator vibrates the diaphragm to output sound, and the piezoelectric vibrator vibrates the diaphragm to output sound.

[0018] The display device according to the second aspect of the present technology includes: a display that displays an image; an electromotive vibrator that vibrates the display to output sound; and a piezoelectric vibrator that vibrates the display to output sound.

[0019] According to the second aspect of the present technology, in a display device including a display that displays an image, an electromotive vibrator, and a piezoelectric vibrator, the electromotive vibrator vibrates the display to output sound, and the piezoelectric vibrator vibrates the display to output sound. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a diagram showing a configuration example of an appearance of a display device.

[0021] Figure 2 is a diagram showing a functional configuration example of a display device.

[0022] Figure 3 is a diagram showing a configuration example of a piezoelectric exciter.

[0023] Figure 4 is a diagram showing a configuration example of a piezoelectric exciter.

[0024] Figure 5 is a diagram for describing an operation of a piezoelectric exciter.

[0025] Figure 6 is a diagram showing an example of a method of attaching a piezoelectric exciter.

[0026] Figure 7 is a diagram showing an example of a method of attaching a piezoelectric exciter.

[0027] Figure 8 is a diagram showing an example of a method of attaching a piezoelectric exciter.

[0028] Figure 9is a diagram showing an example of a method of attaching a piezoelectric exciter.

[0029] Figure 10 is a diagram for describing a frequency characteristic of a display device.

[0030] Figure 11 is a diagram for describing a frequency characteristic and a directional characteristic of a display device.

[0031] Figure 12 is a flowchart for describing a reproduction process. DETAILED DESCRIPTION

[0032] Hereinafter, an embodiment to which the present technology is applied will be described with reference to the drawings.

[0033] <First Embodiment>

[0034] <Configuration Example of Appearance of Display Device>

[0035] The present technology is to vibrate a diaphragm using an electric exciter and a piezoelectric exciter to emit acoustic energy, so that a sufficient sound pressure level can be obtained in a wider frequency band.

[0036] Note that, hereinafter, an example in which the present technology is applied to a display device will be described, but the present technology can be applied to any device intended to have a sound reproduction function, such as an audio device that realizes only a sound reproduction function without having a display function.

[0037] Figure 1 is a diagram showing a configuration example of an appearance of a display device that is an example of a speaker system to which the present technology is applied.

[0038] The display device 11 includes a display 21, an electric exciter 22-1, an electric exciter 22-2, a piezoelectric exciter 23-1, and a piezoelectric exciter 23-2.

[0039] The display 21 includes a flat panel-shaped display panel that realizes a display function, and displays an image based on image data supplied from a display controller (not shown).

[0040] The electric exciter 22-1 and the electric exciter 22-2 are electric vibrators (vibration devices) each including a voice coil, a magnet, and the like, and are fixed to the back surface of the display 21, that is, the surface opposite to the surface on which an image is displayed. Figure 1 is a view of the display device 11 viewed from the back surface of the display 21.

[0041] The electric exciter 22-1 and the electric exciter 22-2 are driven to vibrate the display 21 and emit acoustic energy (sound) from the display 21 in accordance with an input sound signal.

[0042] Note that, in the following, the electromotive exciter 22-1 and the electromotive exciter 22-2 are simply referred to as electromotive exciters 22, in a case where it is not particularly necessary to distinguish between the electromotive exciter 22-1 and the electromotive exciter 22-2.

[0043] The piezoelectric exciters 23-1 and 23-2 are, for example, piezoelectric vibrators (vibration devices) each including a piezoelectric element, and are fixed to the back of the display 21.

[0044] The piezoelectric exciters 23-1 and 23-2 are driven in accordance with an input acoustic signal to vibrate the display 21 and emit acoustic energy (sound) from the display 21.

[0045] Note that, in the following, the piezoelectric exciter 23-1 and the piezoelectric exciter 23-2 are also simply referred to as piezoelectric exciters 23, in a case where it is not particularly necessary to distinguish between the piezoelectric exciter 23-1 and the piezoelectric exciter 23-2.

[0046] In the display device 11, the display 21 not only realizes a display function, but also the display 21, the electromotive exciter 22, and the piezoelectric exciter 23 function as an audio device (speaker system) that outputs sound based on an acoustic signal.

[0047] In this case, the electromotive exciter 22 and the piezoelectric exciter 23 vibrate the display 21 to make the display 21 function as a vibration plate of the audio device (speaker system).

[0048] In a case where the electromotive exciter 22 functions as a vibrator, a sufficient sound pressure level and a wide (large) directional angle can be obtained, particularly at a low frequency (low frequency band).

[0049] On the other hand, in a case where the piezoelectric exciter 23 functions as a vibrator, a sufficient sound pressure level and a wide (large) directional angle can be obtained, particularly at a high frequency (high frequency band).

[0050] Therefore, since the electromotive exciter 22 and the piezoelectric exciter 23 are combined to function as a vibrator in the display device 11, a uniform and sufficient sound pressure level can be obtained in the entire frequency band as a sound reproduction target.

[0051] Further, since the electromotive exciter 22 and the piezoelectric exciter 23 are used in combination, an audio device having a wide (large) directional angle in the entire frequency band as a sound reproduction target can be realized.

[0052] That is, the user can listen to a reproduced sound at a uniform and sufficient sound pressure level in the entire frequency band as a sound reproduction target, not only at the front of the display device 11, but also at a position laterally offset (away) from the front.

[0053] Further, in the display device 11, the piezoelectric exciter 23-1 is arranged near the electrodynamic exciter 22-1, and the piezoelectric exciter 23-2 is arranged near the electrodynamic exciter 22-2.

[0054] Specifically, when the piezoelectric exciter 23 is arranged at the position of the vibration node of the electrodynamic exciter 22, the influence of the vibration reproduced by the low frequency band of the display 21 can be reduced, and sound reproduction can be performed with higher sound quality.

[0055] In Figure 1 the example, the display device 11 performs stereo sound reproduction including L and R channels.

[0056] Therefore, in the display 21, the electrodynamic exciter 22-1 and the piezoelectric exciter 23-1 and the electrodynamic exciter 22-2 and the piezoelectric exciter 23-2 are arranged symmetrically with respect to the center of the display 21.

[0057] Note that, here, an example in which a pair of electrodynamic exciters 22 and a pair of piezoelectric exciters 23 are provided has been described, but any number of electrodynamic exciters 22 and any number of piezoelectric exciters 23 can be provided.

[0058] For example, the electrodynamic exciter 22 and the piezoelectric exciter 23 can be provided for each channel of sound reproduction, or a plurality of piezoelectric exciters 23 can be provided near one electrodynamic exciter 22.

[0059] Further, here, an example in which the piezoelectric exciter 23 is provided on the upper side of the electrodynamic exciter 22 has been described in the drawings, but the arrangement position of the piezoelectric exciter 23 is not limited thereto, and can be any position.

[0060] <Function configuration example of display device>

[0061] Figure 2 A function configuration example of the display device 11 is shown.

[0062] Note that, in Figure 2 corresponding to the components in Figure 1 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0063] Further, Figure 2 Only some of the functional blocks and parts configured to cause the display device 11 to function as an audio device are shown. Specifically, in order to simplify the description, only functional blocks related to one channel are shown in this example.

[0064] In Figure 2In the illustrated example, the display device 11 includes a low-pass filter (LPF) 51, an amplifier 52, an electrodynamic exciter 22, a high-pass filter (HPF) 53, an amplifier 54, a piezoelectric exciter 23, and a display 21.

[0065] In this example, for example, the LPF 51 and the HPF 53 are provided with an acoustic signal of one identical channel (such as an R channel or an L channel) of content.

[0066] The LPF 51 filters the provided acoustic signal to block high-band components, and provides a mid-low band signal (i.e., mid-low band components) including the thus obtained mid-band components and low-band components to the amplifier 52.

[0067] The amplifier 52 amplifies the mid-low band signal provided from the LPF 51, and provides the amplified mid-low band signal to the electrodynamic exciter 22.

[0068] The electrodynamic exciter 22 is driven based on the mid-low band signal provided from the amplifier 52 to vibrate the display 21, thereby outputting a mid-low band sound from the display 21.

[0069] The HPF 53 filters the provided acoustic signal to block the mid-low band components, and provides a high-band signal including only the thus obtained high-band components to the amplifier 54.

[0070] The amplifier 54 amplifies the high-band signal provided from the HPF 53, and provides the amplified high-band signal to the piezoelectric exciter 23.

[0071] The piezoelectric exciter 23 is driven based on the high-band signal provided from the amplifier 54 to vibrate the display 21, thereby outputting a high-band sound from the display 21.

[0072] For example, in a case where the LPF 51 generates a mid-low band signal including components of a predetermined frequency or below, the HPF 53 generates a high-band signal including components of at least the above-described predetermined frequency or a frequency above the above-described predetermined frequency in a frequency band that is an object of sound reproduction. That is, a sound of a frequency of the entire frequency band that is an object of sound reproduction is output by vibration of the electrodynamic exciter 22 and vibration of the piezoelectric exciter 23.

[0073] Furthermore, here, only functional blocks related to one channel are illustrated. However, more specifically, the display device 11 is provided with the above-described LPF 51, amplifier 52, electrodynamic exciter 22, HPF 53, amplifier 54, and piezoelectric exciter 23 for each channel.

[0074] Furthermore, an example in which each of the amplifiers 52 and 54 is provided in a stage subsequent to each of the LPF 51 and the HPF 53 has been described here, but an amplifier can also be provided in a stage anterior to each of the LPF 51 and the HPF 53. In this case, for example, the output of one amplifier can be provided to the LPF 51 and the HPF 53.

[0075] <About the Piezoelectric Exciter>

[0076] Next, the piezoelectric exciter 23 will be described.

[0077] As Figure 3 indicated, for example, the piezoelectric exciter 23 includes a plate-shaped piezoelectric element 81 and electrodes 82-1 and 82-2 formed on the upper surface and the lower surface of the piezoelectric element 81 in the drawing. Note that the electrodes 82-1 and 82-2 will also be simply referred to as electrodes 82 hereafter in cases where it is not particularly necessary to distinguish between the electrodes 82-1 and the electrodes 82-2.

[0078] Here, the direction in which the electrodes of the piezoelectric exciter 23 are arranged (i.e., the direction perpendicular to the surface of the piezoelectric element of the piezoelectric exciter 23 on which the electrodes are provided) is referred to as the thickness direction, and the direction perpendicular to the thickness direction is referred to as the length direction.

[0079] In the example of Figure 3 , the direction in which the electrodes 82-1 and 82-2 are arranged (i.e., the up-down direction in the drawing) is the thickness direction, and the left-right direction and the depth direction in the drawing are the length direction.

[0080] In the piezoelectric exciter 23, when a voltage as an acoustic signal (a high-band signal) is applied to the piezoelectric element 81 via the electrodes 82, the piezoelectric element 81 extends and contracts in the length direction in accordance with the applied voltage. Therefore, the plate-shaped display 21 on which the piezoelectric exciter 23 is fixed is bent to vibrate, and outputs sound based on the input acoustic signal.

[0081] Note that Figure 3 an example in which the piezoelectric exciter 23 includes one piezoelectric element 81 (i.e., one layer of piezoelectric elements 81) has been described, but the piezoelectric exciter 23 can include a plurality of piezoelectric elements stacked in multiple layers.

[0082] In this case, the piezoelectric exciter 23 is configured, for example, as indicated in Figure 4 .

[0083] In the example of Figure 4 , the piezoelectric exciter 23 includes piezoelectric elements 111-1 to 111-4 and electrodes 112-1 to 112-8.

[0084] In this example, the piezoelectric elements 111-1 to 111-4 are arranged in the thickness direction, and the electrodes 112-1 to 112-8 are arranged in the length direction.Figure 3 The plate-shaped piezoelectric elements 111-1 to 111_4 corresponding to the piezoelectric element 81 shown are stacked in the vertical direction shown in the figure, that is, stacked in the thickness direction of the piezoelectric elements 111-1 to 111_4.

[0085] Note that unless there is a special need to distinguish between piezoelectric elements 111-1 to 111_4, piezoelectric elements 111-1 to 111_4 will be referred to as piezoelectric element 111 in the following text.

[0086] Furthermore, electrodes configured to apply a voltage as an acoustic signal (high-frequency band signal) are formed on the surfaces of each piezoelectric element 111 that are opposite each other in the thickness direction.

[0087] That is, electrodes 112-1 and 112-2 are formed on the upper and lower surfaces of the piezoelectric element 111-1 in the figure, respectively, and electrodes 112-3 and 112-4 are formed on the upper and lower surfaces of the piezoelectric element 111-2, respectively.

[0088] Similarly, electrodes 112-5 and 112-6 are formed on the upper and lower surfaces of piezoelectric element 111-3 in the figure, respectively, and electrodes 112-7 and 112-8 are formed on the upper and lower surfaces of piezoelectric element 111-4, respectively.

[0089] Note that unless there is a specific need to distinguish between electrodes 112-1 to 112-8, electrodes 112-1 to 112-8 will be referred to as electrode 112 in the following text.

[0090] exist Figure 4 In the example shown, the piezoelectric actuator 23 has a stacked structure obtained by arranging four piezoelectric elements 111 along the thickness direction of the piezoelectric element 111.

[0091] In the same example, when a voltage, which is the same acoustic signal (high-frequency band signal), is applied to each piezoelectric element 111 via electrode 112, each piezoelectric element 111 extends and contracts along its length.

[0092] For example, here, for all four piezoelectric elements 111 constituting the piezoelectric actuator 23, the piezoelectric elements 111 are stacked such that the same electric field is applied to the polarization direction of each piezoelectric element 111, that is, such that when a voltage is applied, all the piezoelectric elements 111 deform (extend and contract) in the same direction.

[0093] Therefore, with Figure 3 Compared to the example shown, in Figure 4 A greater extension / contraction force can be obtained in the piezoelectric actuator 23 with the stacked configuration shown.

[0094] Here, we will refer toFigure 5 An example of the operation of the piezoelectric actuator 23 is described. Note that, for simplicity of description, it is assumed that the piezoelectric actuator 23 has Figure 3 the configuration shown.

[0095] For example, it is assumed that the electrode 82-2 is provided on the side of the display 21 of the piezoelectric actuator 23, and the electrode 82-1 is provided on the side opposite to the side of the display 21 of the piezoelectric actuator 23. Note that the illustration of the electrode 82 is omitted here.

[0096] In this case, for example, as shown by an arrow 011, when a voltage is applied to the piezoelectric actuator 23 so that the side of the display 21 (i.e., the electrode 82-2) becomes negative and the electrode 82-1 on the opposite side becomes positive, the piezoelectric actuator 23 contracts (wrinkles).

[0097] On the other hand, for example, as shown by an arrow 012, when a voltage is applied to the piezoelectric actuator 23 so that the side of the display 21 (i.e., the side of the electrode 82-2) becomes positive and the electrode 82-1 on the opposite side becomes negative, the piezoelectric actuator 23 extends outward.

[0098] For example, for the piezoelectric actuator 23 having only Figure 3 or Figure 4 the configuration (structure) shown, even when a voltage is applied to the piezoelectric actuator 23, only the surface of the piezoelectric actuator 23 on which the electrode 82 is provided extends and contracts, and no acoustic wave is emitted in a direction perpendicular to the surface.

[0099] Therefore, in the display device 11, the piezoelectric actuator 23 is fixed to the display 21 by adhesion or the like to form a monomorph structure, so that excitation can be performed.

[0100] Specifically, when a voltage is applied to the piezoelectric actuator 23 in a state where the piezoelectric actuator 23 is fixed to the display 21, the piezoelectric actuator 23 extends and contracts as shown by an arrow Q11 and an arrow Q12, thereby causing the display 21 to bend.

[0101] In this way, since the display 21 vibrates due to the display 21 being bent by the piezoelectric actuator 23 in accordance with the acoustic signal, an acoustic wave (acoustic energy) based on the acoustic signal is emitted from the surface of the display 21.

[0102] As described above, since the audio device having the monomorph structure is configured by the piezoelectric actuator 23 and the display 21 in the display device 11, the display 21 can be bent to vibrate by applying a voltage to the piezoelectric actuator 23, and can output an acoustic wave.

[0103] Note that it has been described that the piezoelectric actuator 23 has the configuration as Figure 4In the case of the stacked structure shown, the same electric field is applied to the polarization direction of each piezoelectric element 111, but different electric fields can be applied to the polarization direction of the respective piezoelectric element 111.

[0104] That is, when a voltage is applied, some of the piezoelectric elements 111 constituting the piezoelectric actuator 23 (such as piezoelectric elements 111 arranged adjacent to each other) can deform in different directions.

[0105] In this case, the piezoelectric actuator 23, for example, has a double-layer piezoelectric sheet structure for applying voltage, such that different electric fields are applied to the polarization directions in some piezoelectric elements 111. As a specific example of a double-layer piezoelectric sheet structure, for example, a structure provided with... Figure 4 The upper piezoelectric elements 111-1 and 111-2 have a structure that extends along the length direction (outward) according to the relationship between the polarization direction and the electric field direction. On the other hand, for example, in Figure 4 In this design, the piezoelectric elements 111-3 and 111-4 in the lower half of the piezoelectric actuator 23 have a structure that contracts along the length direction according to the relationship between the polarization direction and the electric field direction. In this case, for example, an electric field is applied along the direction of the piezoelectric element 111 in the upper half of the piezoelectric actuator 23, which is the same as the polarization direction, and an electric field is applied along the direction of the piezoelectric element 111 in the lower half, which is opposite to the polarization direction. Note that a structure can be adopted in which the piezoelectric element 111 in the upper half of the piezoelectric actuator 23 contracts along the length direction and the piezoelectric element 111 in the lower half extends along the length direction (a double-layer piezoelectric sheet structure).

[0106] In the piezoelectric actuator 23 with this double-layer piezoelectric structure, when one piezoelectric element 111 performs a contraction movement, the other piezoelectric element 111 performs an extension movement, so not only the display 21 but also the piezoelectric actuator 23 itself bends to vibrate.

[0107] Only the piezoelectric actuator 23 with a double-layer piezoelectric sheet structure or as per the reference needs need to be selected. Figure 4 The corresponding piezoelectric element 111 has a similarly modified structure (configuration).

[0108] <Regarding the attachment of piezoelectric actuators>

[0109] Next, we will refer to Figures 6 to 9 An example is given describing a method of attaching the piezoelectric exciter 23 to the display 21 (i.e., a method of fixing the piezoelectric exciter 23 to the display 21).

[0110] Note that in Figures 6 to 9 In and in Figure 1 In the case of [the specific component], the corresponding component is indicated by the same reference numeral, and its description will be appropriately omitted. Furthermore, in [the specific context]...Figures 6 to 9 Parts corresponding to each other will also be denoted by the same reference signs, and description thereof will be omitted as appropriate.

[0111] For example, as shown in Figure 6 Fig. 21, the piezoelectric exciter 23 can be directly bonded and fixed (adhesively fixed) to the back surface of the display 21 with an adhesive or the like.

[0112] At this time, for example, the plate-shaped display 21 serving as a vibration plate is preferably configured to be as thin and hard as possible.

[0113] Specifically, the material forming the display 21 is preferably formed to be as close as possible to the material of the piezoelectric exciter 23, so that the strength of the display 21 serving as a vibration plate approaches the strength of the piezoelectric exciter 23 serving as a vibrator. In this way, the display 21 is more easily bent, and higher sound reproduction performance can be obtained.

[0114] Further, in the example shown in Figure 7 Fig. 21, the piezoelectric exciter 23 is adhesively fixed to the back surface of the display 21 by a plurality of double-sided tapes 141-1 to 141-3.

[0115] Specifically, in this example, the piezoelectric exciter 23 and the display 21 are adhesively bonded to each other at three positions of the double-sided tapes 141-1 to 141-3, and a gap is provided between the piezoelectric exciter 23 and the display 21 at other positions. That is, the piezoelectric exciter 23 is adhesively fixed to the display 21 in a floating state (f10atin g state).

[0116] Therefore, the display 21 is bent to vibrate when vibrating by the piezoelectric exciter 23.

[0117] Note that, in the case where it is not particularly necessary to distinguish between the double-sided tape 141-1 and the double-sided tape 141-3, the double-sided tape 141-1 and the double-sided tape 141-3 are also simply referred to as the double-sided tape 141 hereinafter.

[0118] Further, in Figure 7 , in order to promote the visibility of the drawing, the double-sided tape 141 is drawn very thick along the up-down direction in the drawing, but in reality, the thickness of the double-sided tape 141 is about 0.1 mm or the like.

[0119] Also in this example, the display 21 is preferably configured to be as thin and hard as possible, similarly to the example shown in Figure 6 Fig. 21. Further, the material forming the display 21 can be formed to be as close as possible to the material of the piezoelectric exciter 23.

[0120] Further, the example in which the piezoelectric exciter 23 and the display 21 are adhesively fixed at three positions by the double-sided tape 141 has been described here, but as long as the number of positions is three or more, the piezoelectric exciter 23 and the display 21 can be adhesively fixed at any positions.

[0121] In Figure 8 In the example shown, the piezoelectric exciter 23 is joined and fixed to the back of the display 21 via a thin-plate-shaped spacer plate 171 (flat plate).

[0122] That is, the spacer plate 171 is adhesively fixed to the back of the display 21, and the piezoelectric exciter 23 is further adhesively fixed to the spacer plate 171.

[0123] Therefore, when the piezoelectric exciter 23 is driven, the display 21 vibrates via the spacer plate 171, so the display 21 is bent to vibrate.

[0124] Note that the display 21 and the spacer plate 171 are preferably configured to be as thin and hard as possible. Further, the material forming the display 21 or the spacer plate 171 can be formed to be as close as possible to the material of the piezoelectric exciter 23.

[0125] The ceramic piezoelectric element constituting the piezoelectric exciter 23 is easily broken and requires careful handling, but the spacer plate 171 provided between the display 21 and the piezoelectric exciter 23 suppresses the piezoelectric element from breaking and facilitates handling.

[0126] Further, in Figure 9 In the example shown, the spacer plate 171 is adhesively fixed to the piezoelectric exciter 23, and the spacer plate 171 is adhesively fixed to the back of the display 21 by the plurality of double-sided tapes 141-1 to 141-3.

[0127] In this example, the spacer plate 171 and the display 21 are adhesively bonded to each other at three positions by the double-sided tape 141, and a floating state is formed at other positions due to the gap between the spacer plate 171 and the display 21.

[0128] Therefore, the display 21 is bent to vibrate when vibrating by the piezoelectric exciter 23.

[0129] Note that, also in this example, similarly to the above example, the display 21 and the spacer plate 171 are preferably configured to be as thin and hard as possible. Further, the material forming the display 21 or the spacer plate 171 can be formed to be as close as possible to the material of the piezoelectric exciter 23.

[0130] In addition, as long as at least three positions are provided, the number of adhesion positions between the spacer plate 171 and the display 21 via the double-sided tape 141 can be any number.

[0131] When the piezoelectric exciter 23 is driven as described aboveFigures 6 to 9 When the piezoelectric exciter 23 is fixed to the display 21 as shown, a single-layer piezoelectric sheet structure can be configured by the piezoelectric exciter 23 and the display 21, so that the display 21 can be bent to vibrate.

[0132] Note that the display 21 having a display function is described here as an example of a vibration plate, but the vibration plate does not necessarily have a display function.

[0133] For example, a gasket plate in a plate shape can be used as a vibration plate, and the electrodynamic exciter 22 and the piezoelectric exciter 23 can be attached to the vibration plate to realize an audio device having only a sound reproduction function. In this case, for example, as shown in Figures 6 to 9 only the piezoelectric exciter 23 needs to be attached to the gasket plate used as a vibration plate.

[0134] <Regarding the frequency characteristics and the directional characteristics>

[0135] Next, the frequency characteristics and the directional characteristics of the display device 11 will be described.

[0136] Figure 10 is a graph showing the frequency characteristics of the display device 11. Note that in Figure 10 , the vertical axis represents the sound pressure level, and the horizontal axis represents the frequency.

[0137] In Figure 10 , the broken line L11 represents the frequency characteristics of the electrodynamic exciter 22, and the broken line L12 represents the frequency characteristics of the piezoelectric exciter 23.

[0138] For example, in the electrodynamic exciter 22, it can be seen that the sound pressure level is high in the mid-low frequency band, and the sound pressure level is lower than that in the mid-low frequency band in the high frequency band.

[0139] On the contrary, in the piezoelectric exciter 23, it can be seen that the sound pressure level is high in the high frequency band, and the sound pressure level is lower than that in the high frequency band in the mid-low frequency band.

[0140] Further, when the electrodynamic exciter 22 is compared with the piezoelectric exciter 23, it can be seen that the sound pressure level of the electrodynamic exciter 22 is higher in the mid-low frequency band, and the sound pressure level of the piezoelectric exciter 23 is higher in the high frequency band.

[0141] Therefore, by using the electrodynamic exciter 22 and the piezoelectric exciter 23 in combination, a sufficient sound pressure level can be obtained in a wider frequency band, that is, in the entire frequency band as a sound reproduction object.

[0142] Further, Figure 11 is a graph showing the measurement results of the directional characteristics and the frequency characteristics of the electrodynamic exciter 22 and the piezoelectric exciter 23.

[0143] Here, the directional characteristic (contour map) of the electrodynamic exciter 22 is shown in the portion indicated by an arrow 041, and the frequency characteristic of the electrodynamic exciter 22 is shown in the portion indicated by an arrow 042. Similarly, the directional characteristic (contour map) of the piezoelectric exciter 23 is shown in the portion indicated by an arrow 043, and the frequency characteristic of the piezoelectric exciter 23 is shown in the portion indicated by an arrow 044.

[0144] In the portion indicated by an arrow Q41 and the portion indicated by an arrow Q43, the vertical axis represents an angle in the left-right direction from the center of the display 21, the horizontal axis represents a frequency, and the gray scale (color) in the graph represents a sound pressure level.

[0145] For example, in the electrodynamic exciter 22, it can be seen that in the mid-low frequency band, the contour color is uniform over a wide angle, and a wide directivity, i.e., a large directional angle, is obtained, whereas in the high frequency band, the range in which the contour color is uniform is narrow and the directional angle is small. Specifically, in the electrodynamic exciter 22, it can be seen that the sound pressure level decreases as the angle from the center increases in the high frequency band.

[0146] On the other hand, in the piezoelectric exciter 23, it can be seen that in the high frequency band, the contour color is uniform over a wide angle range, and a wide directivity, i.e., a large directional angle, is obtained.

[0147] Further, in the portion indicated by an arrow Q42 and the portion indicated by an arrow Q44, the vertical axis represents a sound pressure level, and the horizontal axis represents a frequency. Specifically, in the portion indicated by an arrow 042 and the portion indicated by an arrow 044, the frequency characteristics near the electrodynamic exciter 22 and the piezoelectric exciter 23 are shown, and it can be seen that characteristics similar to those in the case of Figure 10 are obtained.

[0148] The piezoelectric exciter 23 has a larger vibration force than the electrodynamic exciter 22, and thus, even if the vibration plate is somewhat hard, the piezoelectric exciter 23 can vibrate the entire vibration plate.

[0149] Therefore, even at a high frequency, a wide area of the vibration plate (display 21), i.e., the entire vibration plate (entire surface), can be bent to vibrate, and the directional angle can be increased. That is, a sufficiently high sound pressure level can be obtained over a wider angle range.

[0150] As described above, since the piezoelectric exciter 23 and the electrodynamic exciter 22 are used to vibrate the display 21 according to the display device 11 and output sound, a sufficient sound pressure level can be obtained in a wider frequency band.

[0151] That is, in the display device 11, the electrodynamic exciter 22 having a high sound pressure level and a large directivity angle in the middle-low frequency band and the piezoelectric exciter 23 having a high sound pressure level and a large directivity angle in the high frequency band operate in the respective frequency bands with good characteristics, so that a sufficiently high sound pressure level and a sufficiently large directivity angle can be obtained in the entire frequency band as a sound reproduction object.

[0152] Therefore, the user can watch and listen to the content with the same volume and the same sound quality not only at the front of the display device 11 but also at a position laterally away from the front.

[0153] Specifically, in the display device 11, by making the display 21 itself serve as a vibration plate, sound can be emitted from the display screen, and content reproduction with a higher sense of immersion can be achieved. For example, a display object on the display screen can be made to coincide with a sound image positioning position of sound emitted from the display object.

[0154] <Description of reproduction processing>

[0155] Here, the operation of the above-described display device 11 will be described.

[0156] When reproduction of content is instructed and a sound signal of the content is provided, the display device 11 starts reproduction processing. Hereinafter, the reproduction processing performed by the display device 11 will be described with reference to the flowchart of Figure 12

[0157] In step Sll, the LPF 51 performs filtering on the provided sound signal by the LPF, and provides a middle-low frequency band signal thus obtained to the amplifier 52.

[0158] In step S12, the HPF 53 performs filtering on the provided sound signal by the HPF, and provides a high frequency band signal thus obtained to the amplifier 54.

[0159] In step S13, the amplifier 52 and the amplifier 54 amplify the middle-low frequency band signal provided from the LPF 51 and the high frequency band signal provided from the HPF 53, and provide the amplified signals to the electrodynamic exciter 22 and the piezoelectric exciter 23, respectively.

[0160] In step S14, the electrodynamic exciter 22 is driven based on the output of the LPF 51 (i.e., the middle-low frequency band signal provided from the LPF 51 via the amplifier 52), and the display 21 is vibrated. Thus, sound of the middle frequency band to the low frequency band of the content is output from the display 21.

[0161] In step S15, the piezoelectric exciter 23 is driven based on the output of the HPF 53 (i.e., the high frequency band signal provided from the HPF 53 via the amplifier 54), and the display 21 is vibrated. Thus, sound of the high frequency band of the content is output from the display 21.​

[0162] Note that the processing in steps S14 and S15 is performed simultaneously. When the display 21 is vibrated by the piezoelectric exciter 23 and the electrodynamic exciter 22 and the sound of the content is output from the display 21 in this way, the reproduction processing ends.

[0163] At this time, in a case where the content that is the reproduction target is a video content, the display 21 also displays an image of the content.

[0164] As described above, the display device 11 drives the piezoelectric exciter 23 and the electrodynamic exciter 22 in combination to reproduce the sound of the content. Therefore, it is possible to obtain sufficient sound pressure level in a wider frequency band.

[0165] Note that embodiments of the present technology are not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present technology.

[0166] Further, the present technology can also be configured as follows. (1)

[0168] An audio device comprising:

[0169] a vibration plate;

[0170] an electrodynamic vibrator that vibrates the vibration plate to output sound; and

[0171] a piezoelectric vibrator that vibrates the vibration plate to output sound. (2)

[0173] The audio device according to (1), wherein

[0174] the vibration plate and the piezoelectric vibrator form a single-layer piezoelectric sheet structure, and

[0175] the piezoelectric vibrator bends the vibration plate to vibrate. (3)

[0177] The audio device according to (1) or (2), wherein

[0178] the piezoelectric vibrator includes one piezoelectric element. (4)

[0180] The audio device according to (1) or (2), wherein

[0181] the piezoelectric vibrator includes a plurality of piezoelectric elements stacked. (5)

[0183] The audio device according to (4), wherein

[0184] The plurality of piezoelectric elements forming the piezoelectric vibrator are stacked so that, with application of a voltage, the plurality of piezoelectric elements are deformed in the same direction. (6)

[0186] The audio apparatus according to (4), wherein

[0187] With application of a voltage, some of the plurality of piezoelectric elements forming the piezoelectric vibrator are deformed in directions different from each other. (7)

[0189] The audio apparatus according to any one of (1) to (6), further comprising:

[0190] an LPF that performs filtering on the sound signal to block a high-band component; and

[0191] an HPF that performs filtering on the sound signal to block a low-band component,

[0192] wherein the electrodynamic vibrator vibrates the vibration plate based on a signal obtained by the LPF, and

[0193] the piezoelectric vibrator vibrates the vibration plate based on a signal obtained by the HPF. (8)

[0195] The audio apparatus according to (7), wherein

[0196] The electrodynamic vibrator and the piezoelectric vibrator are provided for each channel of the sound signal. (9)

[0198] The audio apparatus according to any one of (1) to (8), wherein

[0199] The vibration plate is a display. (10)

[0201] A driving method of an audio apparatus including a vibration plate, an electrodynamic vibrator, and a piezoelectric vibrator, the driving method including:

[0202] vibrating the vibration plate by the electrodynamic vibrator to output sound; and

[0203] vibrating the vibration plate by the piezoelectric vibrator to output sound. (11)

[0205] A display apparatus including:

[0206] a display that is a plate-shaped display that displays an image;

[0207] an electrodynamic vibrator that vibrates the display to output sound; and

[0208] a piezoelectric vibrator that vibrates the display to output sound.

[0209] Reference mark list

[0210] 11 display device

[0211] 21 display

[0212] 22-1, 22-2, 22 electric exciter

[0213] 23-1, 23-2, 23 piezoelectric exciter

[0214] 51 LPF

[0215] 52 amplifier

[0216] 53 HPF

[0217] 54 amplifier

Claims

1. An audio device, comprising: Vibrating plate; An electric vibrator causes the vibrating plate to vibrate in order to output sound; as well as A piezoelectric vibrator causes the vibrating plate to vibrate to output sound, wherein... The piezoelectric vibrator is positioned at the vibration node of the electric vibrator to reduce Doppler distortion caused by the vibration reproduced in the low-frequency band, and the electric vibrator and the piezoelectric vibrator are used in combination.

2. The audio device according to claim 1, wherein, The vibrating plate and the piezoelectric vibrator form a single-layer piezoelectric sheet structure, and The piezoelectric vibrator causes the vibrating plate to bend and vibrate.

3. The audio device according to claim 1, wherein, The piezoelectric vibrator includes a piezoelectric element.

4. The audio device according to claim 1, wherein, The piezoelectric vibrator comprises multiple stacked piezoelectric elements.

5. The audio device according to claim 4, wherein, The piezoelectric elements forming the piezoelectric vibrator are stacked such that, when a voltage is applied, the piezoelectric elements deform in the same direction.

6. The audio device according to claim 4, wherein, When a voltage is applied, some of the piezoelectric elements forming the piezoelectric vibrator deform in different directions from each other.

7. The audio device according to claim 1, further comprising: A low-pass filter filters acoustic signals to block high-frequency components. as well as A high-pass filter performs filtering on the acoustic signal to block low-frequency components. The electric vibrator causes the vibrating plate to vibrate based on a signal obtained through the low-pass filter, and The piezoelectric vibrator causes the vibrating plate to vibrate based on a signal obtained through the high-pass filter.

8. The audio device according to claim 7, wherein, The electric vibrator and the piezoelectric vibrator are provided for each channel of the sound signal.

9. The audio device according to claim 1, wherein, The vibrating plate is a display.

10. A driving method for an audio device, the audio device comprising a vibrating plate, an electric vibrator, and a piezoelectric vibrator, the driving method comprising: The vibrating plate is vibrated by the electric vibrator to output sound; as well as The piezoelectric vibrator causes the vibrating plate to vibrate in order to output sound, wherein... The piezoelectric vibrator is positioned at the vibration node of the electric vibrator to reduce Doppler distortion caused by the vibration reproduced in the low-frequency band, and the electric vibrator and the piezoelectric vibrator are used in combination.

11. A display device, comprising: A panel-shaped monitor that displays images; An electric vibrator causes the display to vibrate in order to output sound; as well as A piezoelectric vibrator causes the display to vibrate to output sound, wherein... The piezoelectric vibrator is positioned at the vibration node of the electric vibrator to reduce Doppler distortion caused by the vibration reproduced in the low-frequency band, and the electric vibrator and the piezoelectric vibrator are used in combination.

Images