JP2011234096A - Sound-generating apparatus and speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit ultrasonic waves with greater directivity.SOLUTION: The sound-generating apparatus that comprises a speaker having a plurality of ultrasonic wave generating elements arranged on a first area and a second area adjacent to the first area on the same plane, and a signal supply circuit supplying a first signal to ultrasonic wave generating elements arranged on the first area and a second signal with a substantially inverse phase to the first signal, to ultrasonic wave generating elements arranged on the second area. The second area is rectangular in shape, and the first area may be arranged in contact with the two opposing sides of the rectangle. The ultrasonic waves may be modulated by voice and demodulated into the voice by nonlinear characteristics of a medium such as air.

Description

  The present invention relates to a sound generator and a speaker. In particular, the present invention relates to a sound generator and a speaker that increase directivity using ultrasonic waves modulated by an audio signal.

  2. Description of the Related Art A technique for reproducing sound by emitting ultrasonic waves modulated by a sound signal using a principle that sound is demodulated by nonlinearity of a propagation medium such as air is known. For example, Patent Document 1 discloses a technique for reproducing sound using an ultrasonic wave amplitude-modulated by a sound signal. Patent Document 2 discloses a technique using frequency modulation, and Patent Document 3 discloses a technique using phase modulation.

  Ultrasound has a shorter wavelength than audible sound and can be emitted in a specific direction. Therefore, by emitting an ultrasonic wave modulated by an audio signal, it is possible to transmit the audio to a narrower range than when directly emitting the audio.

  Further, when a plurality of ultrasonic wave generating elements are arranged in a matrix and radiate ultrasonic waves modulated by the audio signal, by gradually changing the phase of the audio signal according to the arrangement order of the ultrasonic wave generating elements, A technique for changing the sound radiation direction is also known (see, for example, Patent Document 4).

JP 58-119293 A JP 11-164384 A JP-A-2005-204288 JP-A-2-265398

  However, in the prior art, an ultrasonic wave is not emitted only in the front direction of an ultrasonic source such as a speaker, and an ultrasonic wave is emitted in a range of about 20 ° around the ultrasonic source. For this reason, when the ultrasonic wave is modulated by the sound, the sound is demodulated other than in front of the ultrasonic source. The present invention discloses a sound generator, a speaker, and the like that can emit ultrasonic waves in a narrower range.

  In one embodiment of the present invention, a speaker in which a plurality of ultrasonic wave generating elements are arranged in a first region in the same plane and a second region adjacent to the first region, and in the first region A first signal is supplied to the arranged ultrasonic generating element, and an absolute value of a phase difference from a signal having a phase opposite to that of the first signal is supplied to the ultrasonic generating element arranged in the second region. A sound generation device is provided that includes a signal supply circuit that supplies a second signal having a value of 0.1 radians or less.

  In an embodiment of the present invention, an ultrasonic wave having a wavelength of λ is applied to a first region on a protrusion protruding from the substrate by a predetermined distance Δ and a second region on the substrate adjacent to the protrusion. There is provided a loudspeaker characterized in that a plurality of ultrasonic wave generating elements are arranged and an absolute value of a difference between (2πΔ / λ) and a value obtained by multiplying a certain odd number by π is 0.1 radians or less. Provided.

  In one embodiment of the present invention, a plurality of ultrasonic wave generating elements are provided in a first region on the protrusion that protrudes from the substrate by a predetermined distance Δ and a second region on the substrate adjacent to the protrusion. The first signal is supplied to the arranged speaker and the ultrasonic generating element arranged in the first region, and the first signal is supplied to the ultrasonic generating element arranged in the second region. And a signal supply circuit for supplying a second signal having a phase difference δ, where λ is the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element, and a value obtained by multiplying a certain odd number by π ( An acoustic generator is provided in which the absolute value of the difference from (2πΔ / λ) + δ) is 0.1 radians or less.

  The present invention provides a sound generator and a directional speaker that can emit ultrasonic waves in a narrower range. Thereby, a sound can be transmitted to a narrower range by modulating an ultrasonic wave with a sound. In addition, the range in which the ultrasonic waves are emitted can be narrowed, and the ultrasonic waves in front of the central portion of the speaker can be enhanced. Furthermore, the signal from the signal supply element that supplies the second signal has many portions that are not out of phase in front of the central portion of the speaker, contributing to the enhancement of ultrasonic waves that contribute to the enhancement of ultrasonic waves. can do.

The figure for demonstrating the principle of this invention The functional block diagram of the sound generator which concerns on one Embodiment of this invention The figure which illustrates the positional relationship of the ultrasonic wave generation element arrange | positioned in a 1st area | region, and the ultrasonic wave generation element arrange | positioned in a 2nd area | region. The functional block diagram of the sound generator which concerns on one Embodiment of this invention The conceptual diagram of the example of application to the pedestrian traffic light of the sound generator which concerns on one Embodiment of this invention. The conceptual diagram of the application example to the digital signage system of the sound generator which concerns on one Embodiment of this invention The figure which shows the measurement result of the magnitude | size of the white noise demodulated in front of a speaker in one Embodiment of this invention. The figure which shows the measurement result of the magnitude | size of white noise at the time of supplying the signal of the same phase to all the ultrasonic wave generation elements The figure which shows the measurement result of the magnitude | size of the white noise demodulated in front of a speaker in one Embodiment of this invention. The figure which shows the measurement result of the magnitude | size of white noise at the time of supplying the signal of the same phase to all the ultrasonic wave generation elements The figure explaining the drip-proof cover concerning one embodiment of the present invention. Illustration of tools used in the experiment The figure which shows the state after jetting a water flow with the mesh sheet vertical The figure which shows the state after injecting a shower stream with the mesh sheet vertical The figure which shows the state after injecting weak straight water flow with the mesh sheet vertical The figure which shows the mode after inclining a mesh sheet | seat 30 degrees and injecting a sprinkling water flow The figure which shows the mode after inclining a mesh sheet | seat 30 degrees and injecting a shower water flow The figure which shows the mode after inclining a mesh sheet 30 degrees and injecting a weak straight water flow

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and can be implemented with various modifications.

(Principle of the present invention)
FIG. 1 is a diagram for explaining the principle of the present invention. FIG. 1A is a front view of a speaker used in an embodiment of the present invention. In FIG. 1A, a plurality of ultrasonic wave generating elements 101 and 102 are arranged on a speaker 100. As each ultrasonic wave generating element, for example, a piezoelectric element can be used. By applying a signal that changes with time, such as a pulse signal, to the piezoelectric element, physical displacement occurs. Therefore, by adding an electrical signal such as a pulse signal that changes at the same frequency as the ultrasonic wave radiated from the speaker, the ultrasonic wave can be radiated to a medium such as air.

  In FIG. 1A, the figure of the ultrasonic wave generating element viewed from the front is circular, but any figure can be used. For example, an oval, a triangle, a quadrangle such as a square or a rectangle, or a regular hexagon can be used. Further, in FIG. 1A, the rows of the ultrasonic wave generating elements are arranged adjacent to each other by being vertically shifted by the radius of the ultrasonic wave generating element with respect to the adjacent row. That is, when the circular centers of adjacent ultrasonic wave generating elements viewed from the front are connected to each other by line segments, a shape in which equilateral triangles are arranged is obtained. However, the arrangement of the ultrasonic wave generating elements is not limited to this, and for example, an arrangement can be used such as a matrix arrangement, a concentric arrangement, or the like.

  FIG. 1B is a left side view of the speaker 100. As shown in FIG. 1B, the plurality of ultrasonic wave generating elements are arranged to form a plane on the speaker 100. For example, if the ultrasonic wave generating element is a piezoelectric element, the part that causes physical displacement is arranged to form a plane. With such an arrangement, when signals that change in the same phase are supplied to a plurality of ultrasonic wave generating elements, a plane wave can be radiated in the front direction of the speaker 100 according to the Huygens principle.

  In addition, arrangement | positioning in the speaker 100 of a some ultrasonic wave generation element is not limited to what forms a plane. As in the embodiment described later, some ultrasonic wave generating elements may be arranged in front of and behind the other ultrasonic wave generating elements by a length that is an integral multiple of a half wavelength of the emitted ultrasonic wave. it can.

  In one embodiment of the present invention, a region where a plurality of ultrasonic generating elements are arranged is divided into a first region and a second region adjacent to the first region. The ultrasonic wave generation element arranged in the first region is supplied with a signal having a phase opposite to that of the signal supplied to the ultrasonic wave generation element arranged in the second region, and radiates ultrasonic waves. Of the ultrasonic waves radiated from the ultrasonic wave generating elements arranged in the second region, the ultrasonic waves radiated from the ultrasonic elements radiated from the ultrasonic element arranged adjacent to the first region are: It interferes with the ultrasonic element emitted from the ultrasonic element arranged in the first region. Thereby, the ultrasonic wave radiated | emitted from the ultrasonic element arrange | positioned adjacent to the 1st area | region can be prevented from spreading. That is, the directivity characteristic of the ultrasonic wave radiated from the speaker 100 can be improved.

  For example, in FIG. 1A, the first region is a region indicated by reference numerals 103 and 105 and is a region on the left side and the right side of the speaker 100, and the ultrasonic wave generating elements are arranged in a line. Area. In addition, the second area is an area indicated by reference numeral 104 and is an area in which the ultrasonic elements are arranged in three rows in the central portion of the speaker 100. In this case, it is possible to drive the ultrasonic generating elements in one row on each of the left and right sides so as to emit ultrasonic waves whose phases are opposite to those of the ultrasonic waves emitted from the three rows of ultrasonic generating elements in the central portion.

  Note that the number of ultrasonic wave generating elements arranged in the first region and the second region need not be the same. In general, the second region is preferably arranged in the center of the speaker. The first region is preferably arranged so as to surround the second region. For this reason, the number of ultrasonic wave generating elements arranged in the first region is often smaller than the number of ultrasonic wave generating elements arranged in the second region.

  Further, it is not necessary to supply the same phase signal to each of the ultrasonic elements arranged in the first region. It is not necessary to supply signals having the same phase to each of the ultrasonic elements arranged in the second region. For example, among the ultrasonic wave generation elements arranged in the second region, the ultrasonic wave generation element arranged in the first region adjacent to the second region is adjacent to the ultrasonic wave generation element adjacent to the first region. A signal having a phase reversed from that of the element may be supplied, and a signal having a different phase may be supplied to another ultrasonic wave generation element disposed in the second region. An example of such a case is that a signal is supplied to each of the ultrasonic wave generating elements in the second region so that the phase gradually changes in accordance with the position of the ultrasonic wave generating element in the second region. This is a case of controlling the direction in which the ultrasonic waves emitted from the light are emitted.

  For example, a signal having a different phase may be supplied to each of the ultrasonic wave generating elements arranged in each of the three columns in the central portion of the region denoted by reference numeral 10. For example, signals having a phase difference of 15 ° are supplied to adjacent columns. In this case, a signal having a phase opposite to that of the signal supplied to the ultrasonic generators arranged in the left column of the area 104 is supplied to the ultrasonic generators arranged in the area 103.

  Similarly, among the ultrasonic wave generation elements arranged in the first area, the ultrasonic wave elements arranged in the second area adjacent to the first area are adjacent to the ultrasonic wave generation elements adjacent to the second area. A signal whose phase is reversed is supplied to the generation element, and a signal having a different phase may be supplied to the other ultrasonic generation elements arranged in the first region.

  In addition, the shapes of the first region and the second region may be fixed, and the shapes of the first region and the second region are controlled by controlling the signals supplied to the respective ultrasonic wave generating elements. May change. Thereby, it is possible to control the number of ultrasonic generating elements arranged in the first region and the second region and the range of the arrangement.

  For example, in FIG. 1A, the area 103 is the area where the left ultrasonic generators are arranged, but the area where the left ultrasonic elements are arranged are the 103 areas. The signal supplied to the ultrasonic wave generating element may be controlled so as to be in the region that is set.

  Note that the ultrasonic waves emitted by the three rows of ultrasonic generating elements in the central portion and the ultrasonic waves emitted by the left and right ultrasonic generating elements do not need to be in exactly opposite phases. For example, among the three rows of ultrasonic elements in the central portion, the left row of ultrasonic devices (hereinafter referred to as the first ultrasonic device) and the left row of ultrasonic generators (hereinafter referred to as the second ultrasonic device). ) At a position equidistant from the first ultrasonic element, the magnitude of the sound wave obtained by the interference between the ultrasonic wave emitted from the first ultrasonic element and the ultrasonic wave emitted from the second ultrasonic element is sufficiently small. It is because it only has to be.

A sound wave radiated from the first ultrasonic element is represented by sin (x), and a sound wave radiated from the second ultrasonic element is a sound wave sin (x + π) = sin (−x ) = Interference between the sound wave represented by sin (x) and the sound wave represented by −sin (x−a) when represented by the equation −sin (x−a) of the sound wave having phase difference a and −sin (x) Can be expressed by (sin (x) −sin (x−a)). Therefore, the absolute value of (sin (x) −sin (x−a)) ((sin (x) −sin (x−a))) is integrated in the range where x is from 0 to 2π. Value) is 1/10 of the average of the absolute values of sin (x), that is,

When the case where is satisfied, a is about 0.1. In fact, consider integrating the absolute value of (sin (x) −sin (x−a)) from 0 to 2π. For example, if a is 0.10, the integral value is 0.399833, and if a is 0.11, the integral value is 0.439778.

  If the average value of the absolute values of (sin (x) −sin (x−a)) is equal to or less than one tenth of the average value of the absolute values of sin (x), the super value modulated by the audio signal is exceeded. Even if sound waves are radiated and sound is demodulated, it is considered that humans cannot hear it due to the interference of ultrasonic waves.

  Therefore, the phase difference between the sound wave having the opposite phase of the ultrasonic wave emitted from the ultrasonic wave generating element arranged in the first region and the ultrasonic wave emitted from the ultrasonic wave generating element arranged in the second region If the absolute value of is 0.1 radians or less, it is possible to improve the directivity characteristics of the ultrasonic waves emitted from the speaker. In other words, a signal having a phase opposite to that of the electrical signal supplied to the ultrasonic generator arranged in the first region, and an electric signal supplied to the ultrasonic generator arranged in the second region, If the absolute value of the phase difference is 0.1 radians or less, the directivity characteristics of the ultrasonic waves emitted from the speaker can be improved. Therefore, in the following description of the present specification, “substantially opposite phase” represents an exact opposite phase or a phase difference within a range of 0.1 radians centered on the exact opposite phase. .

  The first region is not limited to the region where the ultrasonic wave generating elements are arranged in the left and right columns. For example, the first region may be a region in which a predetermined number of rows of ultrasonic generating elements on the right side of the second region are arranged. Alternatively, the first region may be a region in which a predetermined number of rows of ultrasonic generating elements on the left side of the second region are arranged. In addition, the second region may be located above and / or below the second region. In addition, the first region may be located so as to surround the second region.

  FIG. 1C shows the directivity characteristics of the speaker in the prior art, and the directivity characteristics of the speaker in the example in which the first area is located on the left and right of the second area as shown in FIG. Indicates. As in the prior art, the sound pressure level of the ultrasonic wave radiated when signals having the same phase are supplied to the ultrasonic wave generating element arranged in the speaker 100 is indicated by reference numeral 106. Reference numeral 106 is obtained as a figure obtained by connecting the positions where the sound pressure equal to the predetermined sound pressure is obtained by a curve. In this case, the audible range (the range in which the emitted ultrasonic wave is radiated) is a range between two half lines 107 having the speaker 100 as an end point. In the prior art, the angle formed by the two half lines 107 is around 20 °.

  On the other hand, as described above, when the ultrasonic generating elements in the left and right rows are driven so as to emit ultrasonic waves substantially in phase opposite to the ultrasonic waves emitted by the three rows of ultrasonic generating elements in the central portion, reference numeral 103 is obtained. Ultrasonic waves having a sound pressure level indicated by reference numeral 108 are radiated from the ultrasonic wave generating elements arranged in the area of, and sound pressures indicated by reference numeral 109 are emitted from the ultrasonic wave generating elements arranged in the area of reference numeral 105. Level of ultrasound is generated. However, the ultrasonic wave generating element arranged in the area of reference numeral 103 and the ultrasonic wave generating element arranged in the area of reference numeral 105 are substantially opposite to the ultrasonic waves emitted by the ultrasonic wave generating element arranged in the area of reference numeral 104. Phase ultrasonic waves are emitted. For this reason, when the directivity characteristic of the ultrasonic wave radiated from the speaker 100 is illustrated, the width becomes smaller in FIG. 1C than the shape indicated by the reference numeral 106 due to interference, and is indicated by the reference numeral 110. As a result, the audible range is a range between the two half lines 111 and is narrower than the range in the prior art.

  By supplying a signal that emits unmodulated ultrasonic waves to the ultrasonic wave generation elements 101 and 102, ultrasonic waves for sensing the presence of a person can be emitted so as not to be noticed by the person. According to one embodiment of the present invention, the range in which ultrasonic waves for sensing are radiated can be made smaller than in the prior art.

  Further, the ultrasonic wave generating elements 101 and 102 arranged in the speaker 100 may be supplied with a signal that emits an ultrasonic wave modulated by the audio signal. Thereby, the sound is demodulated in a narrower range, and the sound can be transmitted to a narrower range.

(Embodiment 1)
As an embodiment of the present invention, an audio device including a speaker and a signal supply circuit will be described. As shown in FIG. 1, the speaker has a plurality of ultrasonic wave generating elements arranged in a first region in the same plane and a second region adjacent to the first region. The signal supply circuit supplies the first signal to the ultrasonic wave generating element arranged in the first region, and the ultrasonic wave generating element arranged in the second region has a phase substantially opposite to that of the first signal. The second signal is supplied.

  Each of FIG. 2 (A) and FIG. 2 (B) shows an example of a functional block diagram of a more detailed configuration of the sound generator according to one embodiment of the present invention.

  First, a description will be given with reference to FIG. The sound generation apparatus includes a carrier signal generation unit 201, a sound source supply unit 202, a modulation unit 203, a phase inversion unit 204, a phase inversion control unit 205, and a speaker 200. It can be said that the carrier signal generation unit 201, the sound source supply unit 202, the modulation unit 203, the phase inversion unit 204, and the phase inversion control unit 205 correspond to a signal supply circuit.

  The speaker 200 is provided with a plurality of ultrasonic wave generating elements 210. The plurality of ultrasonic wave generating elements 210 arranged are divided into an ultrasonic wave generating element arranged in the first area and an ultrasonic wave generating element arranged in the second area. It is assumed that the first region and the second region are in the same plane.

  2A, the speaker 200 is shown as a left side view of the speaker 100 shown in FIG. In this case, the area 104 at the center of the speaker 200 is the first area, and the areas 103 and 105 in the left and right columns are the second areas. However, the first region and the second region are not limited to those described here. As described above, the first region may be disposed above and / or below the second region, or the second region may be surrounded by the first region.

  FIG. 3 shows two examples of the positional relationship between the ultrasonic wave generating elements arranged in the first area and the ultrasonic wave generating elements arranged in the second area. In FIG. 3A, the ultrasonic wave generating elements are arranged concentrically. In this case, as an example of the first region, there is a region within the range of a predetermined angle α from the center of the concentric circle in the outermost periphery, and the other region is the second region. In addition, when the ultrasonic wave generation element is arranged in both the first region and the second region, for example, if the shape of the ultrasonic wave generation element is circular, the center thereof is in the first region. If it is, it can be defined as being arranged in the first region. In this definition, as shown in FIG. 3A, the ultrasonic wave generating elements 301, 302, 303, 304, 305, 306, and 307 are the ultrasonic wave generating elements arranged in the first region.

  In FIG. 3A, the signals supplied to the ultrasonic wave generating elements 301, 302, 303, 304, 305, 306, and 307 are substantially in phase with the signals supplied to the ultrasonic wave generating elements inside them. Become.

  In FIG. 3B, the ultrasonic wave generating elements are arranged such that the row of the ultrasonic wave generating elements is shifted up and down by the radius of the ultrasonic wave generating element with respect to the adjacent row. In this case, as an example of the first region, there is a region where the ultrasonic wave generating elements 308, 109, 310, and 311 arranged at the top of every other row are arranged.

  In FIG. 3B, the signals supplied to the ultrasonic wave generating elements 308, 109, 310, and 311 are substantially opposite in phase to the signals supplied to the ultrasonic wave generating elements 312, 313, and 314.

  The carrier signal generation unit 201 generates a signal for radiating ultrasonic waves having a predetermined frequency from the speaker 100. A pulse wave or sine wave signal having a frequency of, for example, 40 kHz is generated. The sound source supply unit 202 supplies an audio signal for modulating the signal generated by the carrier signal generation unit 201 to the modulation unit 203. The modulation unit 203 modulates the signal generated by the carrier signal generation unit 201 with the audio signal supplied from the sound source supply unit 202. The modulation unit 203 modulates the signal generated by the carrier signal generation unit 201 using, for example, amplitude modulation, frequency modulation, or phase modulation. In the case where unmodulated ultrasonic waves are radiated from the speaker 200, the sound source supply unit 202 and the modulation unit 203 are not essential components.

  If the frequency of the audio signal supplied by the sound source supply unit 202 is 20 Hz or more and 20 kHz or less and the frequency of the signal generated by the carrier signal generation unit 201 is 40 kHz, the modulation unit 203 has a range of ± 20 kHz of 40 kHz. A signal representing a modulated ultrasonic wave of 20 kHz or more is output. However, if suppressed carrier single sideband modulation is used in modulation section 203, a signal representing a modulated ultrasonic wave of 40 kHz or higher can be output.

  Note that a filter that removes a component having a frequency lower than that of the signal generated by the carrier signal generation unit 201 from the signal output from the modulation unit 203 may be disposed between the modulation unit 203 and the speaker 400.

  If the sound generator generates unmodulated ultrasonic waves, the sound source supply unit 202 and the modulation unit 203 are not essential. A signal generated by the carrier signal generation unit 201 may be directly supplied to the phase inversion unit 204 or the ultrasonic wave generation element 230.

  The phase inversion unit 204 is substantially configured such that the phase of the signal supplied to the ultrasonic wave generating element arranged in the first area and the phase of the signal supplied to the ultrasonic wave generating element arranged in the second area are substantially the same. The phase of the signal output from the modulation unit 203 is controlled so as to have an opposite phase. As a result, for example, the ultrasonic waves radiated from each of the ultrasonic generating elements arranged in the first region have the same phase, but from each of the ultrasonic generating elements arranged in the second region. The phase is substantially opposite to that of the emitted ultrasonic wave.

  There are several methods for controlling the phase, and any of them may be used. For example, when the signal output from the modulation unit 203 is expressed as a voltage between the first terminal and the second terminal, which are output terminals of the modulation unit 203, the signal is arranged in the first region. The first polarity terminal and the second polarity terminal of the ultrasonic generation element are connected to the first terminal and the second terminal of the modulation unit 203 and the like, and the ultrasonic generation element arranged in the second region The first polarity terminal and the second polarity terminal are respectively connected to the second terminal and the first terminal of the modulation unit 203. As a result, the physical displacement generated by the ultrasonic wave generating element arranged in the first region and the physical displacement generated by the ultrasonic wave generating element arranged in the second region have the same size. , The signs will be different.

  Alternatively, by delaying the signal supplied from the modulation unit 203 to the ultrasonic wave generating element arranged in the first area, the phase of the signal supplied to the ultrasonic wave generating element arranged in the second area Can be made to have a phase substantially opposite to that of the signal supplied to the ultrasonic wave generating element disposed in the first region. Or you may delay the signal supplied to the ultrasonic wave generation element arrange | positioned in a 2nd area | region.

  The phase inversion control unit 205 controls the operation of the phase inversion unit 204 and, as a result, controls the shapes of the first region and the second region. For example, the phase inversion control unit 205 includes an ultrasonic generation element to which the output signal of the modulation unit 203 is supplied without performing phase inversion, and an ultrasonic generation element to which the output signal of the modulation unit 203 is supplied after being phase inverted. Change the number and distribution range. Further, it is controlled whether or not the signal supplied to the ultrasonic wave generating element arranged in the second region is set to be substantially in phase with the signal supplied to the ultrasonic wave generating element arranged in the first region. May be performed.

  Note that the shapes of the first region and the second region are fixed, and the ultrasonic waves radiated from the ultrasonic wave generating elements that are always disposed in the second region are disposed in the first region. It is not essential to control the phase inversion unit 206 by the phase inversion control unit 205 if the phase is substantially opposite to that of the ultrasonic wave radiated from the ultrasonic wave generation element.

  Further, the ultrasonic waves radiated from the respective ultrasonic wave generating elements arranged in the first region do not need to be in phase. For example, in order to radiate an ultrasonic wave in a specific direction, the phase of the ultrasonic wave that is gradually emitted may be changed according to the position where the ultrasonic wave generating element is arranged. In this case, among the ultrasonic wave generating elements arranged in the second region, the ultrasonic wave generating element arranged adjacent to the first region is an ultrasonic wave arranged adjacent to the first region. It is preferable to emit an ultrasonic wave having an approximately opposite phase to the ultrasonic wave emitted by the sound wave generating element.

  Next, description will be made with reference to FIG. The sound generation apparatus includes a carrier signal generation unit 201, a sound source supply unit 202, a modulation unit 203, a phase inversion unit 206, a phase inversion control unit 205, and a speaker 220. The difference between the sound generator shown in FIG. 2B and the sound generator shown in FIG. 2A is that the signal output from the phase inversion control unit 205 is at most two lines at the top. Are supplied to the ultrasonic generators 240 arranged in the, and are not supplied to the other ultrasonic generators 230. With such a configuration, the number of ultrasonic generating elements to which the phase inversion control unit 205 supplies signals can be reduced, and the size and power consumption as a circuit can be reduced.

  In the case of FIG. 2B, the phase inversion control unit 205 causes the phase inversion unit 206 to place the signal supplied to the ultrasonic wave generating elements arranged in the second region in the first region. Control is performed to determine whether the phase of the signal supplied to the ultrasonic wave generating element is substantially opposite or in phase.

  For example, the phase inversion control unit 205 is a signal that has an approximately opposite phase to the signal that is supplied to the ultrasonic wave generating element that is disposed in the second area. Instead of this, a signal supplied to the ultrasonic wave generating element arranged in the second region may be supplied. In addition, the phase inversion control unit 205 is a signal whose phase is substantially opposite to that of the signal supplied to the ultrasonic wave generating element arranged in the second area. Instead, the signal supplied to the ultrasonic wave generating elements arranged in the second region may be supplied at a predetermined time interval. For example, at an interval of 3 seconds, a signal having a phase substantially opposite to that of the signal supplied to the ultrasonic generator arranged in the second region is supplied to the ultrasonic generator arranged in the first region. This and alternately supplying the signal to be supplied to the ultrasonic wave generating element arranged in the second region may be repeated.

  Further, in FIG. 2B, the size of the first region is changed, and an ultrasonic wave that generates an ultrasonic wave having an approximately opposite phase to the ultrasonic wave radiated from the ultrasonic wave generating element arranged in the first region. It is possible to select whether the generation element is an ultrasonic generation element in the uppermost row of the speaker or an ultrasonic generation element arranged in the upper two rows. Thereby, the magnitude | size etc. of the range which the ultrasonic wave radiated | emitted from the speaker 220 can be changed. As described above, this change may be performed at predetermined time intervals. By doing so, when a sound signal of a certain magnitude is supplied by the sound source supply unit 202, by knowing whether or not the magnitude of the sound reproduced by the ultrasonic wave radiated from the speaker 100 changes. The relative position with respect to the speaker 100 can be known. That is, if the change in the volume of the sound is large, it can be determined that the speaker 100 is positioned in an oblique direction, and if the change in the volume of the sound is smaller, it is determined that the speaker 100 is positioned in front of the speaker 100. Can do.

(Embodiment 2)
As another embodiment of the present invention, a sound generator including a speaker and a signal supply circuit will be described. In this embodiment, the speaker has a substrate. The substrate has a protrusion. The first region is located on the protrusion. The substrate has a second region adjacent to the protrusion. A plurality of ultrasonic wave generating elements are arranged in the first region and the second region. Further, the signal supply circuit supplies the first signal to the ultrasonic wave generation element arranged in the first region and the second region if the predetermined distance is an even multiple of the half wavelength of the ultrasonic wave. A second signal having a phase substantially opposite to that of the first signal is supplied to the arranged ultrasonic wave generating element. In addition, when the predetermined distance is an odd multiple of the half wavelength of the ultrasonic wave, the signal supply circuit includes the ultrasonic element arranged in the first region and the ultrasonic element arranged in the second region, Supply signals of the same phase.

  Each of FIG. 4 (A) and FIG. 4 (B) shows an example of a more detailed functional block diagram of the sound generator according to one embodiment of the present invention.

  4A, the sound generation device includes a carrier signal generation unit 201, a sound source supply unit 202, a modulation unit 203, a phase inversion unit 204, a phase inversion control unit 205, and a speaker 400. 4B, the sound generation device includes a carrier signal generation unit 201, a sound source supply unit 202, a modulation unit 203, and a speaker 400. Since the carrier signal generation unit 201, the sound source supply unit 202, the modulation unit 203, the phase inversion unit 204, and the phase inversion control unit 205 can be the same as those in the first embodiment, description thereof is omitted.

  In this embodiment, as shown in FIG. 4B, a spacer 401 can be provided as a protrusion on the substrate of the speaker 400. A portion protruding from the front surface of the speaker 400 by the protruding portion becomes the first region. In other words, the first region is on the protruding portion. A second region is provided adjacent to the protrusion. That is, the ultrasonic wave generating elements arranged in the first region are arranged so as to protrude in the direction in which the speaker faces the ultrasonic wave generating elements arranged in the second region. In other words, the second region is located behind the first region by a predetermined distance. Thereby, a phase difference can be generated between the ultrasonic wave radiated from the ultrasonic wave generating element arranged in the first area and the ultrasonic wave radiated from the ultrasonic wave generating element arranged in the second area.

  In FIG. 4A, a spacer 401 is provided in a part of the speaker 400, and a part of the ultrasonic wave generating elements 420 is disposed on the spacer 401. The thickness Δ of the spacer 401 is an integral multiple of half the wavelength of the ultrasonic wave emitted by the ultrasonic wave generating element 410 and the ultrasonic wave generating element 420. In general, the ultrasonic waves radiated from the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420 are radiated by a signal obtained by modulating the signal generated by the carrier signal generation unit 201 by the modulation unit 203, so the wavelength is unambiguous. There are times when it is not determined. In that case, it is preferable to use the wavelength corresponding to the center frequency in the frequency range of the signal output from the modulation unit 203. For example, if the frequency of the signal generated by the carrier signal generation unit 201 is 40 kHz and the frequency of the audio signal supplied from the sound source supply unit 202 to the modulation unit 203 is 20 Hz or more and 20 kHz or less, the signal output by the modulation unit 203 The frequency range is about 40 kHz to 60 kHz. Therefore, the center frequency is about 50 kHz, and the wavelength of the ultrasonic wave of 50 kHz in the air is about 6.64 mm. Therefore, Δ is preferably an integer multiple of 3.32 mm.

  In the following, “the wavelength of the ultrasonic wave radiated by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420” is set to any frequency within the frequency range of the signal output from the modulation unit 203 as described above (for example, the center The frequency is defined as the wavelength of the ultrasonic wave having the frequency of the highest frequency or the frequency with the highest energy).

  When Δ is an even multiple of half the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, when a signal having the same phase is supplied to the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, The ultrasonic wave emitted from the ultrasonic wave generation element 420 has a phase difference that is an integral multiple of the wavelength of the ultrasonic wave emitted from the ultrasonic wave generation element 410. Therefore, when Δ is an even multiple of half the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, the phase inversion unit 206 inverts the phase of the signal output from the modulation unit 203. By doing so, the directivity of the speaker 400 can be improved as in the first embodiment.

  In this embodiment, since the spacer 401 is provided, the ultrasonic wave radiated from the ultrasonic wave generating element 410 is reflected on the lower surface of the spacer 401 in FIG. Spreading can be prevented and directivity can be further enhanced.

  When Δ is an odd multiple of half the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, a signal having the same phase is supplied to the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420 The ultrasonic wave radiated from the ultrasonic wave generation element 420 has a phase difference of approximately half wavelength from the ultrasonic wave radiated from the ultrasonic wave generation element 410. Therefore, by supplying signals having the same phase to the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, the directivity of the speaker 400 can be increased as in the first embodiment. Moreover, normal directivity can be obtained by inverting the phase difference between the signal supplied to the ultrasonic generator 410 and the signal supplied to the ultrasonic generator 420.

  If the directivity is always increased, the signal output from the modulation unit 203 is directly supplied to the ultrasonic generation element 410 and the ultrasonic generation element 420 without passing through the modulation unit as shown in FIG. Δ is an odd multiple of half the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420. Thereby, a circuit configuration etc. can be simplified and power consumption can be reduced.

  Heretofore, Δ has been described as an odd multiple or an even multiple of the wavelength of the ultrasonic wave radiated from the ultrasonic generator 410 and the ultrasonic generator 420, but is not limited thereto. For example, Δ is set to a value other than an odd multiple or even multiple of the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 420, and a signal supplied to the ultrasonic wave generation element 410 and a signal supplied to the ultrasonic wave generation element 420 May have a phase difference.

  For example, let λ be the wavelength of the ultrasonic wave emitted by the ultrasonic wave generation element 410 and the ultrasonic wave generation element 420, and let δ be the phase difference between the signal supplied to the ultrasonic wave generation element 410 and the signal supplied to the ultrasonic wave generation element 420. To do. Further, it is assumed that the ultrasonic wave emitted by the ultrasonic wave generating element 420 at the position of the ultrasonic wave generating element 420 is sin (t) as a function of time t. At this time, the ultrasonic wave emitted by the ultrasonic wave generating element 410 at the position of the ultrasonic wave generating element 410 can be expressed as sin (t−δ). When the ultrasonic wave radiated from the ultrasonic wave generating element 410 reaches the distance Δ ahead of the ultrasonic wave generating element 410, the waveform becomes sin (t−δ−2πΔ / λ).

  Therefore, the value of the phase difference between the ultrasonic wave radiated from the ultrasonic wave generation element 410 and the ultrasonic wave radiated from the ultrasonic wave generation element 420 can be expressed by 2πΔ / λ + δ. If this value represents a substantially opposite phase, the directivity characteristic of the ultrasonic wave radiated from the speaker 400 can be improved. That is, if there is an odd number and the absolute value of the difference between the odd number multiplied by π and 2πΔ / λ + δ is 0.1 or less, the directivity of the ultrasonic wave radiated from the speaker 400 is reduced. The characteristics of the sex can be improved. Here, the odd number is not limited to a positive integer of 1, 3, 5,..., And may be a negative integer of −1, −3, −5,.

  In particular, it is assumed that Δ is an even multiple of λ / 2, that is, an integer n exists, and Δ is m times λ. At this time, since 2πΔ / λ is 2mλ, if the absolute value of a value obtained by multiplying a certain odd number by π and 2mλ + δ is 0.1 or less, the directivity characteristic can be improved. Since 2m is an even number, considering the range of δ, (2n + 1) π−0.1 ≦ δ ≦ (2n + 1) π + 0.1 holds for a certain integer n.

  Further, if Δ is an odd multiple of λ / 2, 2πΔ / λ has an odd number p and becomes pπ. Therefore, the absolute value of the value obtained by multiplying a certain odd number by π and the value of pλ + δ is If it is 0.1 or less, the directivity characteristic can be improved. Since the difference between the odd number and another odd number is an even number, considering the range of δ, 2nπ−0.1 ≦ δ ≦ 2nπ + 0.1 holds for a certain integer n.

  In particular, when δ is 0, there is an odd number, and if the absolute value of the difference between the odd number multiplied by π and 2πΔ / λ is 0.1 or less, The directivity characteristic of the ultrasonic wave radiated from the speaker 400 can be improved.

(Application 1)
FIG. 5 is a conceptual diagram of an example in which the sound generator according to one embodiment of the present invention is applied to a pedestrian traffic light. A signal control device 502 is installed on the column 501. In addition, a pedestrian traffic light 503, a speaker 504, and an ultrasonic detector 505 are also installed on the column 501.

  A signal supply circuit is disposed in the signal control device 502. For example, the signal control device 502 includes a carrier signal generation unit 201, a sound source supply unit 202, and a modulation unit 203, and also includes a phase inversion unit 204 and a phase inversion control unit 205 as necessary. Is done. Signals generated by these units are supplied to a speaker 504 disposed in the vicinity of the pedestrian traffic light 503. The speaker 504 is configured using a plurality of rows in which ultrasonic wave generating elements are arranged vertically. When the pedestrian traffic light 503 displays a blue signal, an ultrasonic wave whose phase is substantially opposite to the ultrasonic wave radiated from the ultrasonic wave generating element in the central row is radiated to the left and right ultrasonic wave generating elements. It can be made to. A plurality of speakers 504 may be arranged on the left and right according to the width of the pedestrian crossing.

  As described above, the sound generator according to the embodiment of the present invention is used for a pedestrian traffic light, and an ultrasonic wave having a phase substantially opposite to that of the ultrasonic wave emitted by the central ultrasonic wave generating element is emitted. Then, the sound can be transmitted from the speaker 504 to pedestrians in a predetermined range with high directivity. Therefore, the sound can be demodulated from the ultrasonic wave in a narrower range than in the case of using the prior art, and the pedestrian can be safely guided on the pedestrian crossing by the sound.

  Note that the speaker 504 does not need to be installed vertically. The surface on which the ultrasonic wave generating element is arranged may be directed slightly downward, for example, about 8 °. This is to prevent the ultrasonic wave radiated from the speaker 504 from reaching a position at a distance longer than the length of the pedestrian crossing.

  Note that the ultrasonic detector 505 is not an essential component. By using the ultrasonic detector 505, the reflected wave of the ultrasonic wave radiated from the speaker 504 can be detected to detect whether or not a person is on the pedestrian crossing. Thereby, it is possible to prevent the pedestrian traffic light from displaying a red signal before the person has crossed the pedestrian crossing. In addition, the signal can be changed according to the traffic situation of the car.

  Further, when guiding a pedestrian using the speaker 504, (1) the case where ultrasonic waves of the same phase are emitted from the ultrasonic wave generating elements of the speaker 504, and (2) the ultrasonic wave generating elements in the left and right rows are You may alternately repeat the case where the ultrasonic wave which a center ultrasonic wave generation element radiates | emits and the ultrasonic wave which a phase becomes a substantially reverse phase is radiated | emitted. At this time, in (1), the ultrasonic wave reflected from the pedestrian is detected by the ultrasonic detector 505, and in (2), the ultrasonic wave reflected from the pedestrian is not detected by the ultrasonic detector 505. Is detected, it can be determined that the pedestrian has gone off the pedestrian crossing and appropriate measures can be taken. For example, a message that calls attention from another speaker can be broadcast, or if it is an intersection, all roadway signals can be displayed in red.

  Further, as described above, whether the pedestrian listening to the sound is located in front of the speaker 504 or obliquely from the front due to a change in the size of the sound reproduced by the ultrasonic wave radiated from the speaker 504. It can be determined whether it is located in the direction. Thereby, guidance can be performed so that a visually handicapped pedestrian moves in an appropriate direction on a pedestrian crossing.

(Application example 2)
FIG. 6 is a conceptual diagram of an example in which the sound generator according to the embodiment of the present invention is applied to a digital signage system. Digital signage is an advertising medium using a liquid crystal display, speakers, and a network. Digital signage has the merit that it can provide information in real time and does not require time and effort to replace posters such as paper.

  In FIG. 6, a plurality of monitors 601, 602, 603, 604 are arranged along the sidewalk, and a predetermined time length (for example, 2 seconds) is assigned to one frame of content based on the moving speed of the pedestrian. Display content on the monitor. In addition, speakers 605, 606, 607, and 608 of the sound generator according to the embodiment of the present invention are arranged on the ceiling in association with the respective monitors. Then, for example, the ultrasonic waves emitted from the speakers are emitted toward the corresponding monitors.

  With such a configuration, even if the distance between the monitors is small, it is possible to prevent a person in front of the monitor from hearing sound from a speaker corresponding to another monitor, and to provide effective information Can do.

(Measurement Example 1)
In FIG. 7, after the 40 kHz signal generated by the carrier signal generation unit 201 is modulated by white noise, as shown in FIG. 1, the ultrasonic wave generation elements arranged in the left and right regions 103 and 105 of the speaker emit radiation. Measures the size of white noise demodulated in front of the speaker when the ultrasonic wave is emitted in the opposite phase of the ultrasonic wave emitted by the ultrasonic wave generator arranged in the central region 104. It is the result.

  In this measurement example, circular ultrasonic wave generating elements are five, four, five, four, five, four, five, four, five, four, and five from the left column. Are arranged in a rectangular range. In this case, in adjacent rows, the upper and lower positions of the ultrasonic wave generating elements are shifted up and down by the radius of the ultrasonic wave generating elements.

  In FIG. 7, the positions where the magnitude of the white noise was measured were “processing width 1 m”, “processing width 2 m”, and “processing width 3 m”, respectively, 1 m from the front of the speaker and perpendicular to the surface of the speaker. 2m or 3m away. In addition, “−80 cm”, “−60 cm”, “−40 cm”, “−20 cm”, “0 cm”, “20 cm”, “40 cm”, “60 cm”, and “80 cm” are measured positions of the speaker. Indicates how far to the right it is in a direction parallel to the surface. The vertical axis represents the magnitude of white noise at each measured position.

  Referring to FIG. 7, it is shown that about 65 dB, which is the largest at the position of 1 m and 0 cm in the processing width, was measured, but when moving to the left and right, the measured value rapidly decreases and the sound is transmitted to a narrow range. I understand that.

  On the other hand, FIG. 8 performs measurement under the same conditions as those in which the measurement results of FIG. 7 were obtained. The conditions different from those in FIG. It is an example. When FIG. 8 is compared with FIG. 7, for example, as can be seen from the shape in the vicinity of “working width 1 m” and “non-processing width 1 m” at 20 cm, it can be seen that the entire shape spreads in the horizontal direction. Therefore, it can be seen that the case of FIG. 7 has higher directivity than the case of FIG.

  Further, FIG. 9 is a diagram in which the speakers used in the measurement examples of FIGS. 7 and 8 are vertically arranged, and the phase of the ultrasonic wave radiated from the ultrasonic wave generating elements arranged in the left and right columns in that case is the column in the center portion. This is a measurement result when an ultrasonic wave is emitted so as to be in an opposite phase to the ultrasonic wave emitted by the ultrasonic wave generating element arranged in the.

  FIG. 10 shows a measurement example in which measurement is performed under the same conditions as those in which the measurement result of FIG. 9 was obtained, and different conditions are the same phase signals supplied to all ultrasonic wave generating elements.

  Comparing FIG. 9 with FIG. 10, it can also be seen that voice is transmitted in a narrower range in FIG.

(Embodiment 3)
As a third embodiment of the present invention, a drip-proof cover for a speaker in the above-described embodiment will be described.

  As shown in FIG. 5, when the speaker is applied to a traffic light, the traffic light is presumed to be used outside, and it becomes rainy. Therefore, consideration and experiment on drip-proofing were performed as follows.

  11 (A) is a front view of the drip-proof cover 1100, FIG. 11 (B) is a plan view thereof, FIG. 11 (C) is a bottom view thereof, and FIG. It is the left view. The right side view is symmetric with the left side view, and is omitted. An example of the rear view is a rectangular figure obtained by removing a line segment indicating the net 1101 from the front view. FIG. 11E shows a cross section of the drip-proof cover taken along the line II of FIG. 11B.

  As can be seen from FIGS. 11A to 11E, the overall shape of the drip-proof cover is not a rectangular parallelepiped, but is a shape obtained by obliquely cutting the rectangular parallelepiped from the vertical direction at the angle of β, and the slope that appears after cutting. The normal to is directed diagonally downward. A speaker is installed on the opposite side of this slope. That is, when the drip-proof cover 1100 is viewed from the front, a speaker 1110 in which a plurality of ultrasonic wave generating elements are arranged is installed at the back of the drip-proof cover.

  In front of the speaker 1110, seats 1102 and 1103 are arranged in parallel so as to have an angle of β obliquely from the vertical direction. In other words, the upper sides of the sheets 1102 and 1103 are located in front of the speaker 1110 than the lower sides. Further, a net 1101 is installed in front of the sheet 1103 in parallel with the sheets 1102 and 1103.

  In this embodiment, β is provided to prevent water such as rain from entering from the front of the drip-proof cover, and is 20 ° or more and 60 ° or less, preferably 25 ° or more and 35 ° or more. When it is larger than 60 °, the length of the front and rear of the drip-proof cover is increased, resulting in an increase in manufacturing cost. In addition, when the angle is less than 20 °, it is difficult to prevent intrusion when a water droplet tries to invade horizontally. Further, from the following experimental example, it was found that β is most preferably 30 °.

  Further, by making β larger than 0, the top surface of the drip-proof cover extends in front of the speaker 1110 from the bottom surface. Thereby, it is possible to prevent the ultrasonic waves emitted from the speaker 1110 from spreading upward.

  Here, it is preferable that the sheets 1102 and 1103 do not attenuate the ultrasonic wave radiated from the speaker 1110 as much as possible. When searching for a sheet suitable for this condition, it was found that a mesh sheet made of nylon was preferable. Moreover, it turned out that the nylon mesh sheet | seat which has the following characteristics especially is preferable. The thickness of the sheet is 380 μm, the wire diameter of the yarn used in the sheet is 200 μm, the distance between the yarn and the yarn is 308 μm, and the mesh cloth space ratio (ratio of the opening area) is 37%.

  In addition, it was found from the experimental example that when two sheets are installed than when one sheet is installed, water can be more reliably prevented from entering from the front of the drip-proof sheet. This is because even if a water droplet enters from the front of the drip-proof cover, the water droplet is divided into smaller water droplets by the opening area of the sheet 1103, and the momentum is absorbed by the sheet 1103. Therefore, even if a water droplet passes through the sheet 1103, it cannot pass through the sheet 1102 and is prevented from reaching the speaker 1110.

  The net 1101 is not an essential component, but has a function of dividing large water droplets into the small water droplets by colliding with the net 1101, and can more reliably prevent the passage of the sheets 1103 and 1102. In order to achieve this function, the net 1101 is preferably a metal net or a metal plate provided with a plurality of holes.

(Experimental example)
As the sheets 1102 and 1103, two nylon mesh sheets (product number NB50) purchased from Tech Jam Co., Ltd. are arranged in parallel at a predetermined distance, and are set to be vertical and inclined at an angle of 30 ° from the vertical direction. The box which can be made to prepare was prepared (refer FIG. 12). In the experiment, as shown in the photograph of FIG. 12, a cardboard box is used. By using such a corrugated cardboard and tilting it 30 ° obliquely from the vertical direction, the same shape as the front surface of the drip-proof cover 1100 can be created.

  The nylon mesh sheet installed in this way uses a hose nozzle that can change the water flow. (1) Jolo water flow, (2) Shower water flow, and (3) Weak straight water flow are horizontal and vertical nylon mesh. It sprayed on the sheet | seat and the nylon mesh sheet | seat inclined 30 degrees.

(When vertical)
FIG. 13 shows a photograph of the first nylon mesh sheet (nylon mesh sheet to which water is directly sprayed) after jetting the water flow. After spraying, water droplets were applied in the range of 13 cm width and 11.5 cm length, and a large amount of water reached the back surface particularly in the range of 11 cm width and 6.3 cm length. Note that water did not pass (penetrate) through the second nylon mesh sheet.

  FIG. 14 shows a photograph of the first nylon mesh sheet after spraying the shower water stream. After jetting, water droplets were applied in a range of 16 cm in width and 21 cm in length, and a large amount of water reached the back surface particularly in a range of 11 cm in width and 7 cm in width. The second nylon mesh sheet did not penetrate water.

  FIG. 15 shows a photograph of the first nylon mesh sheet after jetting a weak straight water stream. As shown in FIG. 15, a large amount of water reached the back surface in a wide range. The second nylon mesh sheet did not penetrate water.

(When tilted 30 °)
FIG. 16 shows a photograph of the first nylon mesh sheet after jetting the water flow. After jetting, in the range of 65 mm wide and 18 mm wide, much less water had reached the back surface than in the case of FIG. The second nylon mesh sheet did not penetrate water.

  FIG. 17 shows a photograph of the first nylon mesh sheet after spraying the shower water stream. After injection, in the range of 11 cm wide and 4.6 cm wide, much less water had reached the back surface than in the case of FIG. The second nylon mesh sheet did not penetrate water.

  FIG. 18 shows a photograph of the first nylon mesh sheet after jetting a weak straight water stream. After spraying, water droplets adhered within a range of 9 cm width and 45 mm width. In particular, water reached the back surface in the range of 5.5 cm wide and 2 cm wide. The second nylon mesh sheet did not penetrate water.

  As can be seen from the above, in all cases, water did not penetrate into the second nylon mesh sheet. For this reason, the drip-proof effect can be expected by making the nylon mesh sheet at least double. The degree of penetration of water in the first nylon mesh sheet was different depending on whether the nylon mesh sheet was inclined. That is, when the nylon mesh sheet is inclined by 30 °, the intrusion of water droplets can be prevented more effectively than when the nylon mesh sheet is made vertical.

  Further, the nylon mesh sheet was doubled and the inclination was made larger than 30 ° and sprayed with a strong straight water flow. In each case, the second nylon mesh sheet was penetrated. However, the amount of water entering can be reduced by attaching a metallic wire mesh in front of the nylon mesh sheet.

100 Speakers 101 and 102 Ultrasonic wave generating elements 103 and 105 First region 104 Second region 106 Directivity characteristic 107 Range in which ultrasonic waves are emitted 108 Directivity characteristic 109 of the ultrasonic wave generating element in the first region 103 Directivity characteristic 110 of ultrasonic generating element in one region 105 Directivity characteristic 111 in one embodiment of the present invention Range in which ultrasonic waves are emitted in one embodiment of the present invention

Claims (14)

A speaker in which a plurality of ultrasonic generating elements are arranged in a first region in the same plane and a second region adjacent to the first region;
A first signal is supplied to the ultrasonic wave generating element arranged in the first region, and a signal having a phase opposite to that of the first signal is supplied to the ultrasonic wave generating element arranged in the second region. And a signal supply circuit that supplies a second signal having an absolute value of a phase difference of 0.1 radians or less.   The acoustic generator according to claim 1, wherein the shape of the second region is a rectangle, and the first region is disposed in contact with two opposite sides of the rectangle.   The signal supply circuit includes a control unit that controls the number of the ultrasonic generation elements to which the first signal is supplied and the number of the ultrasonic generation elements to which the second signal is supplied and a range in which the ultrasonic generation elements are arranged. The sound generator according to claim 1. A method for driving a speaker in which a plurality of ultrasonic wave generating elements are arranged in a first region in the same plane and a second region adjacent to the first region,
The ultrasonic generator arranged in the first region has an absolute value of a phase difference of 0. 0 with respect to the opposite phase signal of the first signal supplied to the ultrasonic generator arranged in the second region. A method for driving a speaker, which supplies a second signal of 1 radian or less. A speaker in which a plurality of ultrasonic generating elements are arranged in a first region on a protruding portion protruding by a predetermined distance Δ from a substrate and a second region on the substrate adjacent to the protruding portion;
A first signal is supplied to the ultrasonic wave generating element arranged in the first region, and the ultrasonic wave generating element arranged in the second region has a phase difference δ with the first signal. A signal supply circuit for supplying a second signal having
When the wavelength of the ultrasonic wave emitted from the ultrasonic wave generating element is λ, the absolute value of the difference between a value obtained by multiplying a certain odd number by π and ((2πΔ / λ) + δ) is 0.1 or less. The sound generator characterized by the above-mentioned.   6. The acoustic generator according to claim 5, wherein Δ is an even multiple of λ / 2, and (2n + 1) π−0.1 ≦ δ ≦ (2n + 1) π + 0.1 holds for a certain integer n. .   6. The acoustic generator according to claim 5, wherein Δ is an odd multiple of λ / 2, and 2nπ−0.1 ≦ δ ≦ 2nπ + 0.1 holds for a certain integer n. A speaker in which a plurality of ultrasonic wave generating elements for generating ultrasonic waves are arranged in a first region on a protruding portion protruding by a predetermined distance Δ from a substrate and a second region on the substrate adjacent to the protruding portion. Driving method,
The phase difference between the signal supplied to the ultrasonic element arranged in the first region and the signal supplied to the ultrasonic element arranged in the second region is δ, and the ultrasonic generation When the wavelength of the ultrasonic wave emitted from the device is λ, the absolute value of the difference between the value obtained by multiplying a certain odd number by π and ((2πΔ / λ) + δ) is 0.1 or less. Method.   The signal supply circuit supplies, as the first signal and the second signal, a signal obtained by modulating a signal that causes the plurality of ultrasonic wave generating elements to generate ultrasonic waves of a predetermined frequency with an audio signal. The sound generation device according to any one of claims 1 to 3, or any one of claims 5 to 7.   The sound generation according to claim 9, wherein the signal supply circuit supplies the first signal instead of the second signal to the ultrasonic wave generation element arranged in the second region at a predetermined time interval. apparatus.   In front of the speaker, two mesh sheets that are inclined 20 ° or more and 60 ° or less in front of the vertical direction and whose upper side is positioned in front of the speaker with respect to the lower side are arranged with a gap therebetween. The sound generator according to any one of claims 1 to 3, claim 5, claim 7, or claim 9, wherein:   The sound generator according to claim 11, wherein the mesh sheet is made of nylon.   The mesh sheet has a thickness of 380 μm, the yarn diameter used in the mesh sheet is 200 μm, the distance between the yarn and the yarn is 308 μm, and the ratio of the mesh opening area is 37%. The sound generator according to claim 11 or 12, characterized by the above.   A plurality of ultrasonic wave generating elements that generate ultrasonic waves having a wavelength of λ in a first region on a protruding portion protruding by a predetermined distance Δ from the substrate and a second region on the substrate adjacent to the protruding portion And the absolute value of the difference between a value obtained by multiplying a certain odd number by π and (2πΔ / λ) is 0.1 radians or less.