JP2012029098A - Oscillation device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillation device that is small-sized but is capable of outputting high-directional acoustic waves in a plurality of directions.SOLUTION: In an oscillation device 100, a vibrator support mechanism 120 is displaced by a sound deflection mechanism 130 to deflect piezoelectric vibrators 111-113. As a result, directions of the piezoelectric vibrators 111-113 are changed so that directions of high-directional acoustic sounds to be output are changed. In spite of this, the whole device can be downsized because a plurality of the piezoelectric vibrators 111-113 do not need to be arranged in a matrix.

Description

  The present invention relates to an oscillation device including a piezoelectric element, and more particularly, to an oscillation device in which a piezoelectric element is mounted on a vibration member, and an electronic apparatus having the oscillation device.

  In recent years, demand for portable electronic devices such as mobile phones and notebook computers has been increasing. In such an electronic device, development of a thin portable terminal whose commercial value is an acoustic function such as a videophone, a video playback, and a hands-free phone is being promoted. Under such development, there is an increasing demand for high-quality sound, small size, and thinness for electroacoustic transducers (speaker devices) that are acoustic components.

  Currently, electrodynamic electroacoustic transducers are used as electroacoustic transducers in electronic devices such as mobile phones. This electrodynamic electroacoustic transducer is composed of a permanent magnet, a voice coil, and a diaphragm.

  However, there is a limit to reducing the thickness of electrodynamic electroacoustic transducers due to their operating principles and structures. On the other hand, Patent Documents 1 and 2 describe using a piezoelectric element as an electroacoustic transducer.

  As other examples of an oscillation device using a piezoelectric element, there are various types of devices such as a speaker device and a sound wave sensor (Patent Document 3) that detects a distance to an object using a sound wave oscillated from a piezoelectric element. There are known electronic devices and oscillators (Patent Document 4).

No. 2007-026736 Table 2007-083497 Japanese Patent Laid-Open No. 03-270282 Japanese Patent Laid-Open No. 04-074099

  An oscillating device using a piezoelectric element uses a piezoelectric effect of the piezoelectric element to generate a vibration amplitude by an electrostrictive action by inputting an electric signal. The electrodynamic electroacoustic transducer generates vibration by a piston-type forward / backward movement, whereas the oscillation device using the piezoelectric element has a bending-type vibration state and thus has a small amplitude.

  For this reason, it is superior in reducing the thickness of the electrodynamic electroacoustic transducer described above. However, since the output sound of the oscillation device is highly directional, the sound can be output only in one direction.

  As a method for outputting highly directional sound waves in a plurality of directions, there is a parametric speaker in which a plurality of piezoelectric vibrators are arranged in a matrix. In this parametric speaker, highly directional sound waves can be output in a plurality of directions by individually driving a plurality of piezoelectric vibrators arranged in a matrix. However, in this case, it is necessary to arrange a plurality of piezoelectric vibrators in a matrix, so that the oscillation device is naturally increased in size.

  The present invention has been made in view of the above-described problems, and provides an oscillation device capable of outputting highly directional sound waves in a plurality of directions while being small, and an electronic apparatus having the oscillation device. Is.

  An oscillation device according to the present invention includes a piezoelectric vibrator that outputs at least a highly directional sound wave including ultrasonic waves, a vibrator support mechanism that supports the piezoelectric vibrator, and a vibrator support mechanism that displaces the piezoelectric vibrator. And an audio deflection mechanism for deflecting.

  The first electronic device of the present invention includes the oscillation device of the present invention and oscillation drive means for causing the oscillation device to output a highly directional sound wave obtained by modulating a low-frequency audible sound wave with a high-frequency ultrasonic wave.

  The second electronic device of the present invention includes the oscillation device of the present invention, oscillation drive means for driving the oscillation device to output ultrasonic waves as highly directional sound waves, and being oscillated from the oscillation device and reflected by the measurement object. Ultrasonic detection means for detecting ultrasonic waves, and distance calculation means for calculating the distance from the detected ultrasonic waves to the measurement object.

  In the present invention, the focal position of the highly directional sound wave is a high directional sound wave obtained by modulating a low frequency audible sound wave to a high frequency ultrasonic wave, and the high directional sound wave is demodulated into an audible sound wave. In the case of an ultrasonic wave as a high-frequency highly directional sound wave, it means a position where the highly directional sound wave is reflected.

  In the oscillation device of the present invention, the sound deflection mechanism is displaced by the sound deflection mechanism to deflect the piezoelectric vibrator. For this reason, the direction of the highly directional sound output by changing the direction of the piezoelectric vibrator is changed. Nevertheless, since it is not necessary to arrange a plurality of piezoelectric vibrators in a matrix, the entire apparatus can be reduced in size.

It is a typical longitudinal section front view showing the structure of the electroacoustic transducer which is the oscillation device of the first embodiment of the present invention.

  A first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, an electroacoustic transducer 100 that is an oscillation device of the present embodiment includes piezoelectric vibrators 111 to 113 that output at least high directivity sound waves including ultrasonic waves, and piezoelectric vibrators 111 to 111, respectively. The vibrator support mechanism 120 that supports 113 and the sound deflection mechanism 130 that deflects the piezoelectric vibrators 111 to 113 by displacing the vibrator support mechanism 120 are provided.

  More specifically, three piezoelectric vibrators 111 to 113 are supported by four vibrator support mechanisms 120, and four sound deflection mechanisms 130 displace the four vibrator support mechanisms 120 to provide a plurality. The piezoelectric vibrators 111 to 113 are deflected.

  The sound deflection mechanism 130 is made of a piezoelectric element and is disposed at the base of the vibrator support mechanism 120. The vibrator support mechanism 120 supports the plurality of piezoelectric vibrators 111 to 113 in an arrangement in which the focal positions of the plurality of highly directional sound waves to be output are different.

  Further, in the electroacoustic transducer 100 of the present embodiment, one piezoelectric element 114 and one elastic member 115 are integrally formed, and the vibrator support mechanism 120 is integrally formed. The elastic member 115 is constrained and divided into three piezoelectric vibrators 111 to 113.

  The plurality of piezoelectric vibrators 111 to 113 output high directional sound waves obtained by modulating low frequency audible sound waves with high frequency ultrasonic waves, and the vibrator support mechanism 120 demodulates the high directional sound waves into audible sound waves. A plurality of piezoelectric vibrators 111 to 113 are supported in an arrangement with different focal positions.

  More specifically, in the electroacoustic transducer 100 of the present embodiment, the three piezoelectric vibrators 111 to 113 are formed to have the same overall length. The vibrator support mechanism 120 is formed in a gate shape that restrains one surface of the piezoelectric element 114.

  However, the two vibrator support mechanisms 120 on both sides are formed longer than the two vibrator support mechanisms 120 at the center. For this reason, the three piezoelectric vibrators 111 to 113 have one central surface positioned horizontally, and the two on both sides are inclined so that the surfaces face each other.

  The electroacoustic transducer 100 according to the present embodiment has a flat main body frame 140, and a plurality of transducer support mechanisms 120 are fixed to the surface thereof. The main body frame 140 serves as a fixed end, and the material thereof must be a material having high rigidity with respect to the elastic member 115. For example, stainless steel or brass can be used.

  In the piezoelectric element 114, upper / lower electrode layers are individually formed on upper and lower surfaces of the piezoelectric layer (not shown). The upper / lower electrode layers are connected to the oscillation driving means 150 with lead wires, and the piezoelectric element 114 is driven in the audible region or the ultrasonic region by the electric field applied from the oscillation driving means 150.

  In this oscillation driving means 150, the relationship between the directions of the plurality of highly directional sound waves output individually by the plurality of piezoelectric vibrators 111 to 113 and the displacement of the plurality of vibrator support mechanisms 120 by the sound deflection mechanism 130 is registered. In response to the registered relationship, at least a part of the plurality of vibrator support mechanisms 120 is displaced to deflect at least a part of the plurality of piezoelectric vibrators 111 to 113 in a predetermined direction.

The piezoelectric layer of the piezoelectric element 114 of the present embodiment is not particularly limited as long as it is a material having a piezoelectric effect. However, a material having high electromechanical conversion efficiency, for example, lead zirconate titanate ( Materials such as PZT (lead Zirco-titanate) and barium titanate (BaTiO ₃ ) can be used.

  The thickness of the piezoelectric layer of the piezoelectric element 114 is not particularly limited, but is preferably 10 μm or more and 500 μm or less. For example, when a thin film having a thickness of less than 10 μm is used as a ceramic material that is a brittle material, chipping or breakage occurs due to weak mechanical strength during handling, making handling difficult.

  In addition, when a ceramic having a thickness of more than 500 μm is used, the conversion efficiency for converting electrical energy into mechanical energy is significantly reduced, and sufficient performance as the electroacoustic transducer 100 cannot be obtained.

  In general, in a piezoelectric ceramic that generates an electrostrictive effect by inputting an electric signal, the conversion efficiency depends on the electric field strength. Since the electric field strength is expressed by the thickness / input voltage with respect to the polarization direction, an increase in thickness inevitably causes a decrease in conversion efficiency.

  In the piezoelectric element 114 of the present embodiment, the upper / lower electrode layers are formed on the main surface as described above in order to generate an electric field. The upper / lower electrode layer is not particularly limited as long as it is a material having electrical conductivity, but it is preferable to use silver or silver / palladium. Silver is used as a general-purpose electrode layer with low resistance, and has advantages in manufacturing process and cost.

  Further, since silver / palladium is a low-resistance material excellent in oxidation resistance, there is an advantage from the viewpoint of reliability. The thickness of the upper / lower electrode layer is not particularly limited, but the thickness is preferably 1 μm or more and 50 μm or less.

  For example, when the thickness is less than 1 μm, since the film thickness is thin, it cannot be uniformly formed, and conversion efficiency may be reduced. As a technique for forming a thin film upper / lower electrode layer, there is a method of applying it in a paste form.

  However, when the piezoelectric layer is a polycrystal such as ceramic, the surface state is textured, so that the wet state at the time of application is poor, and there is a problem that a uniform electrode film cannot be formed without a certain thickness.

  On the other hand, when the film thickness of the upper / lower electrode layer exceeds 100 μm, there is no particular problem in manufacturing, but the upper / lower electrode layer becomes a constraining surface for the piezoelectric ceramic material which is a piezoelectric layer, and energy conversion efficiency is improved. There is a problem that it lowers.

  As for the piezoelectric element 114 of the electroacoustic transducer 100 of this Embodiment, the one main surface is restrained by the elastic member 115. At the same time, the elastic member 115 has a function of adjusting the basic resonance frequency of the piezoelectric element 114. The basic resonance frequency f of the mechanical piezoelectric vibrators 111 to 113 depends on the load weight and compliance, as shown by the following expression.

[Equation 1]
f = 1 / (2πL√ (mC))
“M” is mass and “C” is compliance.

  In other words, since the compliance is the mechanical rigidity of the piezoelectric vibrators 111 to 113, this means that the basic resonance frequency can be controlled by controlling the rigidity of the piezoelectric element 114.

  For example, the fundamental resonance frequency can be shifted to a low frequency by selecting a material having a high elastic modulus or reducing the thickness of the elastic member 115. On the other hand, the basic resonance frequency can be shifted to a high range by selecting a material having a high elastic modulus or increasing the thickness of the elastic member 115.

  Conventionally, since the basic resonance frequency was controlled by the shape and material of the piezoelectric element 114, there were problems in design restrictions, cost, and reliability. However, as in the present invention, the elastic member 115, which is a constituent member. Since it can be easily adjusted to a desired fundamental resonance frequency by changing the above, the industrial value is great.

  The elastic member 115 is not particularly limited as long as it is a material having a high elastic modulus with respect to a ceramic which is a brittle material such as metal or resin, but general-purpose materials such as phosphor bronze and stainless steel are used from the viewpoint of workability and cost. used.

  The thickness of the elastic member 115 is preferably 5 μm or more and 1000 μm or less. When the thickness is less than 5 μm, the mechanical strength is weak, the function as a restraining member is impaired, and the mechanical accuracy of the piezoelectric element 114 is varied between manufacturing lots due to the reduction in processing accuracy.

  Further, when the thickness exceeds 1000 μm, there is a problem that the restraint on the piezoelectric element 114 due to the increase in rigidity is strengthened and the vibration displacement amount is attenuated. In addition, the elastic member 115 of the present embodiment preferably has a longitudinal elastic modulus, which is an index indicating the rigidity of the material, of 1 GPa or more and 500 GPa or less. As described above, when the rigidity of the elastic member 115 is excessively low or excessively high, there is a problem that characteristics and reliability are impaired as a mechanical vibrator.

  The material of the vibrator support mechanism 120 is not particularly limited, but a material having higher rigidity than the elastic member 115 and the piezoelectric element 114 is preferable, and brass or the like can be used. Moreover, the same material as the main body frame 140 or a single unit may be used.

  Here, the operation principle of the electroacoustic transducer 100 of the present embodiment will be described below. The electroacoustic transducer 100 according to the present embodiment generates highly directional sound waves from a plurality of piezoelectric vibrators 111 to 113 in parallel.

  The electroacoustic transducer 100 of the present invention includes a plurality of piezoelectric vibrators 111 to 113 separated by a vibrator support mechanism 120, and both ends of the plurality of piezoelectric vibrators 111 to 113 are fixed by the vibrator support mechanism 120. The elastic member 115 and the piezoelectric element 114 are formed.

  Since the piezoelectric element 114 is divided into a plurality of parts as described above, an audible sound is reproduced by oscillating an ultrasonic wave (for example, a frequency band of 20 kHz or less) using a small size. Here, the ultrasonic wave is used as a carrier for modulated waves, and is preferably outside the audible band, for example, 100 KHz is suitable.

  In addition, the sound reproduction method by the electroacoustic transducer 100 according to the present embodiment uses the operating principle of a parametric speaker that is an acoustic regenerator that uses ultrasonic waves as a modulated wave transporter.

  Non-linear characteristics when an ultrasonic wave that has been subjected to AM modulation, DSB (Double Sideband modulation) modulation, SSB (Single-Sideband modulation) modulation, FM (Frequency Modulation) modulation is emitted into the air, and the ultrasonic wave propagates into the air. Thus, sound reproduction is performed on the principle that audible sound appears.

  Non-linearity includes a phenomenon in which the flow changes from laminar flow to turbulent flow when the Reynolds number indicated by the ratio between the inertial action and the viscous action of the flow increases. That is, since the sound wave is slightly disturbed in the fluid, the sound wave propagates in a non-linear manner.

  However, the amplitude of the sound wave in the low frequency band is non-linear, but the amplitude difference is very small, and is usually handled as a phenomenon of linear theory. On the other hand, nonlinearity can be easily observed with ultrasonic waves, and when radiated into the air, harmonics accompanying the nonlinearity are remarkably generated.

  In summary, sound waves are a dense state where molecular groups are mixed in the air, and if it takes time for air molecules to recover rather than compress, air that cannot be recovered after compression will continue to propagate through the air. This is the principle that an audible sound is generated by colliding with a molecule and generating a shock wave.

  The piezoelectric element 114 has a high mechanical quality factor Q (hereinafter referred to as “machine Q”). This is because energy concentrates in the vicinity of the fundamental resonance frequency, so that the sound wave is large near the resonance frequency, but significantly attenuates in other bands.

  That is, in the piezoelectric element 114 that oscillates a sound wave at a single frequency, the higher the machine Q, the higher the sound pressure level of the sound wave, which is superior from the viewpoint of electromechanical conversion efficiency. This increases the effect.

  As shown in the figure, in the electroacoustic transducer 100 of the present embodiment, the plurality of piezoelectric vibrators 111 to 113 output highly directional sound waves in different directions. The plurality of highly directional sound waves intersect within the main body frame 140, but do not intersect at the focal position demodulated into audible sound waves.

  For this reason, it can be demodulated to an audible sound wave at a desired position without being unintentionally demodulated due to cross interference. The electroacoustic transducer 100 according to the present embodiment can output a highly directional sound wave demodulated into an audible sound wave at a desired position in a plurality of directions.

  Nevertheless, unlike the existing parametric speaker, there is no need to arrange the plurality of piezoelectric vibrators 111 to 113 in a matrix, so that the entire device can be reduced in size.

  In the electroacoustic transducer 100 of the present embodiment, the plurality of piezoelectric vibrators 111 are supported by the plurality of piezoelectric vibrators 111 to 113 supported by the voice deflection mechanism 130 that can be expanded and contracted vertically. ˜113 can be freely deflected.

  In the electroacoustic transducer 100, the relation between the directions of the three piezoelectric vibrators 111 to 113 and the expansion / contraction states of the four sound deflection mechanisms 130 is registered in the oscillation driving means 150. Therefore, when the piezoelectric vibrators 111 to 113 are deflected, at least one of the four sound deflection mechanisms 130 is expanded or contracted according to the registered data. In the electroacoustic transducer 100, since the directions of the plurality of piezoelectric vibrators 111 to 113 are variable (deflected) as described above, the direction of the output highly directional sound wave can be deflected.

  Furthermore, in the electroacoustic transducer 100 according to the present embodiment, the plurality of piezoelectric vibrators 111 to 113 are vibrated. Therefore, by adjusting the position of the vibrator support mechanism 120 when the electroacoustic transducer 100 is manufactured, The basic resonance frequency can be adjusted by changing the areas of the piezoelectric vibrators 111 to 113.

  Therefore, an arbitrary basic resonance frequency can be easily given to each of the plurality of piezoelectric vibrators 111 to 113. For example, by simultaneously driving the piezoelectric vibrators 111 to 113 having a plurality of fundamental resonance frequencies, it is possible to supplement a band having a low sound pressure level, and to improve the frequency characteristics of the sound pressure level.

  In the electroacoustic transducer 100 of the present embodiment, highly directional sound waves output from the plurality of piezoelectric vibrators 111 to 113 intersect. By utilizing the interference due to this intersection, the audible sound wave to be demodulated can be amplified or reduced, and the position where the audible sound wave is demodulated can be varied.

  Also, in audible sound reproduction using ultrasonic waves, since sound waves are generated from the plurality of piezoelectric vibrators 111 to 113, directivity control is possible, and functions such as three-dimensional sound can be provided.

  Moreover, in the electroacoustic transducer 100 according to the present embodiment, a single piezoelectric element 114 and a single elastic member 115 are joined together and restrained by a plurality of vibrator support mechanisms 120, whereby a plurality of piezoelectric vibrations are obtained. The children 111 to 113 are realized. Therefore, the structure is simple and the productivity is good, and the frequency characteristics of the plurality of piezoelectric vibrators 111 to 113 can be easily equalized.

  In summary, the electroacoustic transducer 100 of the present invention can also be used as a sound source of an electronic device (for example, a mobile phone, a notebook personal computer, a small game device, etc.). The increase in size of the electroacoustic transducer 100 can be suppressed, and the acoustic characteristics can be improved. Therefore, the electroacoustic transducer 100 can be favorably used for a portable electronic device.

  In addition, this invention is not limited to said embodiment and Example, A various deformation | transformation is accept | permitted in the range which does not deviate from the summary. For example, in the electroacoustic transducer 100 of the said form, it assumed that the several piezoelectric vibrators 111-113 were divided into the same size. However, the sizes of the plurality of piezoelectric vibrators 111 to 113 may be different (not shown).

  Moreover, it has illustrated having the some piezoelectric vibrators 111-113 from which a direction differs in the said form. However, each of the plurality of piezoelectric vibrators having different directions may be formed by a parametric speaker made of a matrix array, and the output direction of the highly directional sound wave may be deflected (not shown).

  Furthermore, in the said form, it illustrated that the electrode layer was uniformly formed in the whole region of the upper surface of the piezoelectric element 114, and a lower surface. However, the electrode layers may be individually formed for each of the plurality of piezoelectric vibrators 111 to 113, and the piezoelectric layers may be individually driven (not shown).

  In the above embodiment, one piezoelectric element 114 and one elastic member 115 are integrally formed, and the plurality of piezoelectric vibrators 111 to 113 are formed by being restrained by the vibrator support mechanism 120. Illustrated. However, piezoelectric vibrators formed individually from the beginning may be supported by a vibrator support mechanism (not shown).

  Furthermore, in the said form, it illustrated that the three piezoelectric vibrators 111-113 are arrange | positioned concavely. However, the plurality of piezoelectric vibrators 111 to 113 may be arranged in a convex shape, and the number of the piezoelectric vibrators may be two or less or four or more (not shown).

  Moreover, in the said form, electroacoustic transducer 100 grade | etc., Was illustrated as an oscillation apparatus. Such an electroacoustic transducer 100 or the like can be mounted on, for example, a mobile phone that is an electric device as described above.

  However, as an electronic device, an electroacoustic transducer 100 or the like that is an oscillation device, an oscillation drive unit that drives the electroacoustic transducer 100 or the like, and an ultrasonic wave that is oscillated from the electroacoustic transducer 100 and reflected by a measurement object. It is also possible to implement a sonar (not shown) having an ultrasonic detection unit for detecting the distance and a distance calculation unit for calculating the distance from the detected ultrasonic wave to the measurement object.

  Needless to say, the above-described plurality of embodiments and the plurality of modifications can be combined within a range in which the contents do not conflict with each other. In the above-described embodiment, the structure of each part has been specifically described. However, the structure and the like can be variously changed within a range that satisfies the present invention.

100 Electroacoustic transducers 111-113 Piezoelectric vibrator 114 Piezoelectric element 115 Elastic member 120 Vibrator support mechanism 130 Audio deflection mechanism 140 Main body frame 150 Oscillation driving means

Claims (10)

A piezoelectric vibrator that outputs at least a highly directional sound wave containing ultrasonic waves;
A vibrator support mechanism for supporting the piezoelectric vibrator;
An audio deflection mechanism for deflecting the piezoelectric vibrator by displacing the vibrator support mechanism;
An oscillation device having A plurality of the piezoelectric vibrators are supported by the plurality of vibrator support mechanisms,
The oscillation device according to claim 1, wherein the plurality of sound deflection mechanisms displace at least a part of the plurality of vibrator support mechanisms to deflect at least a part of the plurality of piezoelectric vibrators.   The oscillation device according to claim 1, wherein the vibrator support mechanism supports the plurality of piezoelectric vibrators in an arrangement in which focal positions of the plurality of high-directional sound waves to be output are different. One piezoelectric element and one elastic member are integrally formed,
4. The vibrator support mechanism according to claim 1, wherein at least one of the piezoelectric element and the elastic member that are integrally formed is constrained to be divided into a plurality of the piezoelectric vibrators. The oscillation device described.   The oscillation device according to any one of claims 1 to 4, wherein the sound deflection mechanism displaces the vibrator support mechanism by a piezoelectric element. The plurality of piezoelectric vibrators output the highly directional sound waves obtained by modulating low-frequency audible sound waves with the high-frequency ultrasonic waves,
The said vibrator | oscillator support mechanism supports the said some piezoelectric vibrator in the arrangement | positioning from which the said focal position from which the said highly directional sound wave is demodulated to the said audio field sound wave differs. Oscillation device. The plurality of piezoelectric vibrators output the highly directional sound waves composed of the high-frequency ultrasonic waves,
The oscillation device according to claim 1, wherein the vibrator support mechanism supports a plurality of the piezoelectric vibrators in an arrangement where the focal positions at which the highly directional sound waves are reflected are different. The oscillation device according to any one of claims 1 to 7,
Oscillation driving means for causing the oscillation device to output the highly directional sound wave obtained by modulating a low frequency audible sound wave with the high frequency ultrasonic wave;
Electronic equipment having The oscillation device according to any one of claims 1 to 7,
Oscillation drive means for driving the oscillation device to output ultrasonic waves that are the highly directional sound waves;
Ultrasonic detection means for detecting the ultrasonic wave oscillated from the oscillation device and reflected by the measurement object;
Distance calculating means for calculating a distance from the detected ultrasonic wave to the measurement object;
Electronic equipment having   The relationship between the directions of the plurality of highly directional sound waves individually output by the plurality of piezoelectric vibrators and the displacement of the plurality of vibrator support mechanisms by the sound deflection mechanism is registered. The electronic device according to claim 8 or 9, wherein at least a part of the plurality of vibrator support mechanisms is correspondingly displaced to deflect at least a part of the plurality of piezoelectric vibrators in a predetermined direction.

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