Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2006005845 PROBLEM TO BE SOLVED: To utilize all sound waves emitted from both sides of a push-pull type ultrasonic transducer as a sound source. SOLUTION: A vibrating membrane having a conductive layer, and a pair of fixed electrodes provided opposite to respective surfaces of the vibrating membrane, a DC bias voltage is applied to the conductive layer of the vibrating membrane, An alternating current signal is applied between the pair of fixed electrode parts to generate a sound wave in the vibrating membrane, and a sound wave generated from the vibrating membrane is output through two through holes provided in each of the pair of fixed electrodes. An ultrasonic speaker using an ultrasonic transducer outputting from a surface, wherein an acoustic wave output surface of the ultrasonic transducer is disposed in a direction orthogonal to an acoustic wave radiation direction, and two acoustic waves of the ultrasonic transducer And an acoustic wave reflection plate provided corresponding to the output surface and reflecting the acoustic waves outputted from the respective acoustic wave output surfaces in the acoustic wave radiation direction. [Selected figure] Figure 1 Ultrasonic speaker and projector [0001] The present invention relates to an ultrasonic speaker and a projector equipped with the ultrasonic speaker, and in particular, all sound waves emitted from both sound output surfaces of a push-pull electrostatic ultrasonic transducer are used as a sound source. The present invention relates to ultrasonic speakers and projectors that can be used. [0002] In recent years, with respect to a speaker having a parametric effect utilizing non-linearity of air 03-05-2019 1 with respect to ultrasonic waves, an application has been found that combines a reflector that reflects an audible sound wave by a reflector. [0003] For example, the invention is disclosed in which a reflector and an ultrasonic transducer array are incorporated in a speaker box. However, in the structure of the present invention, there is a problem that the sound pressure of the reflected sound becomes nonuniform because the sound emitting surfaces of the ultrasonic transducer array are not equidistant from the reflecting surface (for example, see Patent Document 1) . [0004] Further, the invention for the above-mentioned problems is disclosed, wherein an ultrasonic transducer array is formed on the concave surface of a parabolic substrate having an aperture at its central portion, and an audible sound wave is produced near the central point of the radius of curvature of the substrate. By providing a reflector, the above problem is solved by a configuration in which a highly directional secondary wave (audio sound wave) is reflected by the reflector and emitted through a hole opened at the center of the parabolic substrate. It is solving (for example, refer patent document 2). [0005] However, in any of the above methods, the acoustic wave output surface relates to a single transducer, and in the case of a push-pull electrostatic transducer having a structure in which acoustic waves are output in both directions of the transducer, the acoustic wave emitted to the back side Was not available effectively. [0006] FIG. 10 is a diagram for explaining the driving concept of the push-pull type electrostatic ultrasonic transducer. In the push-pull type electrostatic ultrasonic transducer, a pair of opposing fixation is made opposite to the vibrating film 41. An electrode portion 51 and an opposite fixed electrode portion 52 are provided. 03-05-2019 2 Then, a positive DC bias is applied to the vibrating film 41 by a DC bias power supply, and an alternating current signal is applied between the facing fixed electrode portion 51 and the facing fixed electrode portion 52. [0007] FIG. 10A is a diagram showing the amplitude state of the vibrating membrane 41 when the AC signal is zero (0), and the vibrating membrane 41 is neutral (the middle of the facing fixed electrode portion 51 and the facing fixed electrode portion 52). In the position of. FIG. 10B is a diagram showing the amplitude state of the diaphragm 41 when the positive voltage of the alternating current signal is applied to the opposite fixed electrode portion 51 and the negative voltage of the alternating current signal is applied to the opposite fixed electrode portion 52. The central portion of the diaphragm 41 is formed of the opposing fixed electrode portion 52 by the electrostatic force (suction force) between the opposing fixed electrode portion 52 and the electrostatic force (repulsion force) between the opposing fixed electrode portion 51. Be drawn in the direction. FIG. 10C is a diagram showing the amplitude state of the vibrating membrane 41 when the negative voltage of the alternating current signal is applied to the opposite fixed electrode portion 51 and the positive voltage of the alternating current signal is applied to the opposite fixed electrode portion 52. The central portion of the vibrating film 41 is directed in the direction of the opposite fixed electrode 51 by the electrostatic force (suction force) between the opposite fixed electrode 51 and the electrostatic force (repulsion) between the opposite fixed electrode 52. Be drawn to In this way, the vibrating membrane 41 vibrates in response to the alternating current signal to generate a sound wave, and the sound wave generated from the vibrating membrane 41 is radiated in both directions of the facing fixed electrode portion 51 and the facing fixed electrode portion 52. [0008] When using a push-pull type ultrasonic transducer having a structure in which sound waves are output in such both sides, as shown in FIG. 11A, sound waves output from both sides of the fixed electrode 50 are emitted as they are. (Leak) or, as shown in FIG. 11 (b), the sound wave output from one opposing fixed electrode portion 52 side is attenuated by the absorber 90, and the 03-05-2019 3 sound wave output from the ultrasonic transducer is It is not configured to use all. [0009] Also, as shown in FIG. 12A, conventionally, the ultrasonic speaker is circularly mounted so that the sound wave output surface faces the front of the projector. Therefore, the ultrasonic speaker is reflected behind the circular fixed electrode 50. When the plate 60a is provided, the reflecting plate 60a used for the plate 60a needs to have a diameter twice that of the fixed electrode 50, and it is difficult to fold the plate easily. There was a challenge to bring. (Note that FIG. 12 (b) shows a form in which the ultrasonic transducer shown in FIG. 12 (a) is mounted on a projector). Japanese Patent Application Laid-Open No. 61-123389 Patent Specification 2786531 [0010] The present invention has been made to solve such problems, and its object is to utilize all of the sound waves emitted from both sound output surfaces of a push-pull type electrostatic ultrasonic transducer as a sound source. Providing an ultrasonic speaker and a projector capable of [0011] The present invention has been made to solve the above problems, and an ultrasonic speaker according to the present invention comprises a vibrating membrane having a conductive layer, and a pair of fixed electrodes provided to face each surface of the vibrating membrane. And applying a DC bias voltage to the conductive layer of the vibrating membrane and applying an alternating current signal between the pair of fixed electrode parts to generate a sound wave in the vibrating membrane, and generating a sound wave generated from the vibrating membrane An ultrasonic speaker using ultrasonic transducers that output from two sound wave output surfaces through through holes provided in each of the pair of fixed electrodes, wherein the sound wave output surface of the ultrasonic transducers has a direction of sound wave emission. Sound wave which is disposed in the direction orthogonal to the above and is provided corresponding to the two sound wave output faces of the ultrasonic transducer, and reflects the sound waves output from each sound wave output face in the sound wave radiation direction Characterized in that it comprises a morphism plate. 03-05-2019 4 With such a configuration, in an ultrasonic speaker using a push-pull type electrostatic ultrasonic transducer having two sound wave output surfaces, the direction of the sound output surface of the ultrasonic transducer is in the direction of the sound emission of the ultrasonic speaker. The ultrasonic transducers are arranged to be orthogonal to each other. And a sound wave reflecting plate is provided corresponding to each sound wave output surface, and the sound wave outputted from each sound wave output surface is reflected in the sound wave radiation direction of an ultrasonic speaker. Thereby, in the push-pull type ultrasonic speaker, since the sound wave output from the sound output surface on one side which has been discarded without being used conventionally can be used, the output sound pressure can be improved, and the speaker with good directivity Can be configured. [0012] Also, in the ultrasonic speaker according to the present invention, the acoustic wave output surface of the ultrasonic transducer is disposed so as to be horizontal to a horizontal plane, or the acoustic wave output surface of the ultrasonic transducer is perpendicular to the horizontal plane It is characterized in that it is arranged as follows. According to such a configuration, when configuring the ultrasonic speaker, the sound wave output surface of the ultrasonic transducer is arranged to be horizontal to the horizontal plane, or the sound wave output surface of the ultrasonic transducer is horizontal Select and arrange vertically to the right. Thereby, when the ultrasonic speaker is mounted on a device (for example, a projector or the like), the degree of freedom in the mounting direction is increased. [0013] The ultrasonic speaker according to the present invention is characterized by comprising means for variably adjusting the attachment angle of the sound wave reflection plate with respect to the sound wave output surface of the ultrasonic transducer. With such a configuration, the attachment angle between the sound wave reflection plate and the sound wave output surface can be variably adjusted. Thereby, the sound wave reflected by the sound wave reflection plate can be adjusted to be directed to the sound wave radiation direction. [0014] 03-05-2019 5 The ultrasonic speaker according to the present invention is characterized in that an attachment angle of the sound wave reflection plate with respect to the sound wave output surface of the ultrasonic transducer is set to about 45 degrees. With such a configuration, the angle between the sound wave reflection plate and the sound wave output surface is set to be approximately 45 degrees. Thereby, the sound wave reflected by the sound wave reflection plate can be directed in the sound wave radiation direction. [0015] In the ultrasonic speaker according to the present invention, the position of the sound wave reflection plate on one side of the sound wave output surface is perpendicular to the position of the sound wave reflection plate on the other side of the sound wave output surface. A moving mechanism control means is provided for moving in the direction by a half wavelength of the frequency of the carrier wave. With such a configuration, a moving mechanism (slide mechanism) is provided on the sound wave reflection plate on one side, and the distance d (the distance from the vibrating membrane) is moved by a half wavelength according to the frequency of the carrier wave. Thus, the phases of the sound waves output from the sound wave output surfaces on both sides can be made the same phase, so that sound pressure cancellation near the central axis can be prevented, and the output sound pressure can be further improved. [0016] The ultrasonic speaker according to the present invention is characterized in that the sound wave reflection plate is formed to be foldable and storable. With such a configuration, the reflection plate is configured to be foldable and storable. As a result, since the reflection plate can be easily folded, the ultrasonic speaker can be easily stored in the projector. [0017] Further, the ultrasonic speaker according to the present invention is characterized by further comprising a curved reflection plate for reflecting a sound wave component reflected in a direction other than the sound wave emission direction by the sound wave reflection plate in the sound wave emission direction. With such a configuration, when the sound wave reflection plate is a flat plate, some of the sound waves emitted from the ultrasonic transducer are not perpendicularly incident on the sound wave reflection plate, and thus the reflected sound waves 03-05-2019 6 are not emitted forward, It is reflected in the direction. Therefore, by further providing a curved reflecting plate (preferably conical) to the flat reflecting plate, components reflected in a direction shifted from the desired direction (forward) by the flat reflecting plate are forwardly reflected by the curved reflecting plate. Reflect As a result, it is possible to more effectively utilize the one-side sound wave that has been discarded without prior utilization. [0018] A projector according to the present invention is characterized in that the ultrasonic speaker according to any one of the above is mounted. With such a configuration, the ultrasonic speaker according to the present invention is mounted on a projector. As a result, the output sound pressure of the ultrasonic speaker mounted on the projector can be improved, and the directivity of the speaker can be improved. [0019] Next, the best mode for carrying out the present invention will be described with reference to the drawings. [0020] FIG. 1 is a view showing a configuration example of an ultrasonic speaker according to the present invention. In FIG. 1, an audio frequency band signal oscillation source 11 generates an audio frequency band signal (for example, an audio signal or the like). The carrier wave signal source 12 generates a carrier wave signal (carrier wave signal) in the ultrasonic frequency band. The modulation unit 13 modulates the carrier wave signal of the ultrasonic frequency band generated by the carrier wave signal source 12 with an audio frequency band signal. The preamplifier 14 performs pre-stage amplification of the modulation signal, and the power amplifier 15 further amplifies the modulation signal. The ultrasonic transducer 30 converts the modulated signal amplified by the power amplifier 15 into a sound wave (ultrasound) and emits it into the air. [0021] The ultrasonic wave emitted from the ultrasonic transducer 30 has a parametric effect during air 03-05-2019 7 propagation, and the audio frequency sound is self-demodulated and can be heard as an audible sound. [0022] Here, the ultrasonic transducer 30 is composed of a vibrating membrane 41 and a fixed electrode 50 comprising a pair of opposed fixed electrode portions (a pair of fixed electrodes) 51 and 52 facing the vibrating membrane 41, and the vibrating membrane 41 is It has a push-pull type structure held by two opposing fixed electrode portions 51 and 52. In addition, reflecting plates 60 are provided on both sides of the fixed electrode 50 of the ultrasonic transducer 30. [0023] In FIG. 1, the ultrasonic transducer 30 and the reflection plate 60 are shown in a cross-sectional view. Actually, the vibrating film 41, the fixed electrode 50, and the reflection plate 60 are in the direction perpendicular to the drawing sheet. It has a spread configuration (see the structural example of the fixed electrode shown in FIG. 9). [0024] FIG. 2 is a view showing a configuration example of the vibrating film 41. The vibrating film 41 has a structure in which a conductive material (conductive layer) 42 is sandwiched by an insulator 43. [0025] Returning to FIG. 1, a single positive (+) or negative (-) bias voltage is applied to the vibrating film 41 from the constant voltage source 16 (the conductive layer of the vibrating film 41 is charged), and An alternating current signal output from the power amplifier 15 is applied to the fixed electrode portions 51 and 52 so that the polarity is alternately switched. Thereby, the suction action and the repulsion action by the electrostatic force are simultaneously exerted on the vibrating film 41 to vibrate. 03-05-2019 8 [0026] FIG. 3 is a view showing an example of the configuration of the ultrasonic transducer and the reflection plate, and a view showing a portion of the ultrasonic transducer 30 and the reflection plate 60. As shown in FIG. As described above, the fixed electrode 50 is configured of the opposite fixed electrode portion 51 facing the vibrating membrane 41 and the opposite fixed electrode portion 52, and the through holes 53 are the same in the opposite fixed electrode portions 51 and 52. It is provided in the shape and the same position (the same corresponding position). The vibrating membrane 41 is held in such a structure as to be sandwiched between the opposed fixed electrode portions 51 and 52, and the sound wave generated by the vibration of the vibrating membrane 41 is emitted into the air through the through hole 53. [0027] On both surface sides of the fixed electrode 50, reflecting plates 60 whose mount angles (θ) can be adjusted with respect to the sound wave emitting surface of the fixed electrode 50 are provided. Usually, the reflection plate 60 is attached at an angle of 45 degrees (about 45 degrees) to the sound wave output surface, and the traveling direction of the sound wave is changed by the reflection plate 60 in the direction orthogonal to the sound emission surface, As a result, sound is emitted toward the desired sound wave radiation direction (front side). [0028] At this time, since the sound waves emitted from the respective surfaces are in opposite phase, there is a possibility that the sound pressure may not be partially improved in the vicinity of the ultrasonic transducer (near the center), but compared with the conventional emission from one side As the sound pressure improves. [0029] FIG. 4 is a diagram showing a second configuration example of the ultrasonic speaker according 03-05-2019 9 to the present invention, and cancellation of partial sound pressure cancellation in the vicinity of the ultrasonic transducer (near the center) in the configuration example shown in FIG. An example of the configuration is shown. In the configuration example shown in FIG. 4A, according to the frequency of the carrier wave (carrier wave signal), the distance d between the vibrating film 41 and the reflecting plate 60 is moved by a half wavelength on the opposite fixed electrode portion 51 side. Let's do it. The distance between the vibrating film 41 and the reflection plate 60 may be moved on the opposite fixed electrode portion 52 side. Further, FIG. 4B shows the relationship between the carrier wave frequency (carrier wave signal frequency) and the half wavelength distance. [0030] As described above, by shifting the reflection plate on one side by a half cycle (= half wavelength) of the carrier wave, it is possible to make the phases of the sound waves output from the opposing fixed electrode portions 51 and 52 on both sides the same phase. Sound pressure near the central axis can be prevented, and the sound pressure can be further improved. [0031] FIG. 5 is a view showing an example of a control circuit of the ultrasonic speaker shown in FIG. Since the frequency of the carrier wave signal (carrier wave signal) is determined at the stage of modulation processing, as shown in FIG. 5, the information signal (frequency information signal) is transmitted from the modulation unit 13 to the moving mechanism control unit (moving mechanism control means Sent to 17). The movement mechanism control unit 17 calculates a half wavelength amount (= movement amount) corresponding to the frequency from the information signal (frequency information signal), and drives the movement mechanism (movement mechanism control means) 71. [0032] With such a configuration, it is possible to make the phases of the sound waves on both sides the same phase, so sound pressure cancellation near the central axis can be prevented, and sound pressure can be further improved. 03-05-2019 10 [0033] FIG. 6 is a view showing an example in which the ultrasonic speaker according to the present invention is mounted on a projector, and shows an example of a projector having a stereo reproduction function using two ultrasonic speakers on the left and right. As shown in FIG. If the ultrasonic speaker composed of the ultrasonic transducer 30 and the reflection plate 60 is set vertically or horizontally according to the size (width, height) of the projector 80, it can be easily incorporated into the projector 80. 6 (a) is an example in which the sound wave output surface of the ultrasonic transducer 30 is arranged in the vertical direction of the projector 80, and FIG. 6 (b) is a sound wave output surface of the ultrasonic transducer 30. This is an example in which the projector 80 is disposed in the left and right direction. [0034] In addition, with such an arrangement, it is possible to fold the reflection plate 60 and store the ultrasonic speaker in a very narrow space in the projector 80. [0035] In the conventional mounting form (see the conventional example of FIG. 12 (b)), the ultrasonic speaker is circular and mounted upright with the sound wave output surface facing the front of the projector. The reflecting plate requires a diameter twice as large as the diameter of the ultrasonic transducer, which is difficult to fold easily, and there is a problem that the size of the projector is increased or the output of the ultrasonic speaker is insufficient. [0036] FIG. 7 is a view showing the storage state of the ultrasonic speaker according to the present invention, and shows an example of a projector having a stereo reproduction function using two ultrasonic speakers on the left and right. According to the configuration of the present invention, as shown in FIG. 7, when the ultrasonic speaker composed of the ultrasonic transducer 30 and the reflection plate 60 is stored, the reflection plate 60 is folded to fit in a very compact size, and There will be no increase in size of 80. 03-05-2019 11 In addition, at the time of use, the ultrasonic speaker may be slid to the upper surface or the front surface of the projector 80 so as to protrude and at the same time the reflection plate 60 may be opened. [0037] FIG. 8 is a diagram showing an example in which a curved reflector is added to the ultrasonic transducer, and when the reflector is a flat plate, part of the sound wave emitted from the ultrasonic transducer is perpendicular to the reflector. Because the light is not incident, the reflected sound wave is not emitted forward but is reflected in the vertical direction. Therefore, as shown in FIG. 8, a curved reflector (preferably conical) 61 is further provided to the reflector (planar reflector) 60 to make the reflector 60 (planar reflector) 60 in a desired direction (forward The component reflected in the direction deviated from) can be reflected forward by the curved reflecting plate 61. [0038] FIG. 9 is a view showing an example of the shape of the fixed electrode, and in the configuration of the present invention, as shown in FIG. 9, the shape of the fixed electrode 50 may be any shape of circular, elliptical or rectangular. However, a square is desirable in terms of area efficiency. In addition, the shape of the through hole 53 may be circular, oval or rectangular, and the arrangement thereof may be linear, beehive or concentric. [0039] FIG. 9A shows an example in which the fixed electrode 50 is formed in a rectangular shape, and the through holes 53 are formed in a rectangular shape and arranged in parallel. Moreover, FIG.9 (b) and FIG.9 (c) have shown the example which made the through-hole part 53 circular, and has arrange ¦ positioned. [0040] 03-05-2019 12 As described above, in the ultrasonic speaker according to the present invention, by providing reflecting plates at 45 degrees on both sides of the sound output surface of the push-pull ultrasonic transducer, the phase difference between the sound waves on both sides is infinite. It can be emitted in a small amount. For this reason, it becomes possible to utilize the sound wave of the one side thrown away without utilizing conventionally, and an output sound pressure can be improved. In addition, by placing the ultrasonic speaker vertically or horizontally, the projector can be efficiently stored. Further, since the reflection plate can be easily folded, the ultrasonic speaker can be easily stored in the projector. [0041] As mentioned above, although an embodiment of the present invention was described, the ultrasonic speaker of the present invention is not limited only to the above-mentioned example of illustration, and various changes can be added in the range which does not deviate from the gist of the present invention Of course. [0042] The figure which shows the structural example of the ultrasonic speaker by this invention. The figure which shows the structural example of a vibrating film. The figure which shows the structural example of an ultrasonic transducer and a reflecting plate. The figure which shows the 2nd structural example of the ultrasonic speaker by this invention. FIG. 5 is a view showing an example of a control circuit of the ultrasonic speaker shown in FIG. 4; The figure which shows the example which mounted the ultrasonic speaker by this invention in the projector. The figure which shows the accommodation state of the ultrasonic speaker by this invention. The figure which shows the example which added the curved reflecting plate to the ultrasonic transducer. The figure which shows the example of the shape of a fixed electrode. Explanatory drawing which shows the drive concept of a push pull type electrostatic ultrasonic transducer. Explanatory drawing of a prior art example. Explanatory drawing of a prior art example. Explanation of sign [0043] DESCRIPTION OF SYMBOLS 11 audio frequency band signal oscillation source 12 carrier wave 03-05-2019 13 signal source 13 modulation part 14 preamplifier 14 power amplifier 16 constant voltage source 17 movement mechanism control part 30 ultrasonic transducer 41 ... vibrating film, 42 ... conductive material, 43 ... insulator, 50 ... fixed electrode, 51 ... opposite fixed electrode, 52 ... opposite fixed electrode, 53 ... through hole, 60 ... reflector, 61 ... curved reflector, 71: Movement mechanism, 80: Projector 03-05-2019 14
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