JP2012134591A - Oscillation device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillation device in which the directivity of sound waves can be narrowed with high efficiency.SOLUTION: Since an electroacoustic transducer 100 utilizes a cantilever supporting structure, the sound wave radiation part is limited to the end of a piezoelectric vibrator 110. Consequently, the sound wave radiation positions of adjoining piezoelectric vibrators 110 can be brought close to each other. In other words, phase cancelling of sound waves oscillated from adjoining piezoelectric vibrators 110 can be suppressed by controlling the distance between the piezoelectric vibrators 110 in the short diameter direction, and the directivity of sound waves can be narrowed with high efficiency.

Description

  The present invention relates to an oscillation device using a piezoelectric vibrator, and an electronic apparatus using the oscillation device.

  In mobile phones, we are working on the development of thin, stylish mobile phones with commercial features such as videophones, video playback, and hands-free phone functions, and there is an increasing demand for the development of small, high volume electroacoustic transducers. Yes. Further, from the viewpoint of privacy protection, development of a super-directional speaker that can form a sound field only at a specific position is required. As a super-directional speaker, a parametric speaker that uses an ultrasonic wave as a carrier wave such as sound and demodulates in a non-linear state in the air has been developed.

  Currently, there are various proposals as the above-described electroacoustic transducer (Patent Documents 1 and 2).

Utility Model Registration No. 3068450 Japanese Unexamined Patent Publication No. 2000-134697

  However, in order to narrow down the directivity of ultrasonic waves, a main beam that combines ultrasonic waves transmitted at different timings is generated from an array probe in which a large number of minute ultrasonic transducers are arranged, as in the phased array method. The method to make was taken. In this case, since it is necessary to arrange a large number of piezoelectric vibrators in an array, there is a problem that the size of the ultrasonic device increases.

  The present invention has been made in view of the above-described problems, and provides a small oscillation device having high directivity and an electronic apparatus using such an oscillation device.

  An oscillation device according to the present invention includes a plurality of piezoelectric elements that expand and contract by application of an electric field, a plurality of elongated elastic members each having a plurality of piezoelectric elements attached to one end, and the other ends of the plurality of elastic members. A frame-shaped support member.

  A first electronic device according to the present invention includes the oscillation device according to the present invention and an oscillation drive unit that causes the oscillation device to output an ultrasonic wave demodulated into an audible sound wave.

  A second electronic device according to the present invention includes an oscillation device according to the present invention, an oscillation drive unit that outputs an ultrasonic wave to the oscillation device, and an ultrasonic detection that detects an ultrasonic wave oscillated from the oscillation device and reflected from a measurement object. And a distance measuring unit that calculates a distance from the detected ultrasonic wave to the measurement object.

  In the oscillation device of the present invention, a plurality of piezoelectric elements are individually attached to one end of a plurality of elongated elastic members whose other ends are supported by a frame-shaped support member. Since the cantilever support structure is used, the sound wave radiating portion is limited to the end portion of the vibrator composed of the elastic member and the piezoelectric element. For this reason, the sound wave radiation positions of adjacent vibrators can be brought close to each other. That is, by controlling the distance in the minor axis direction between the transducers, it is possible to suppress the phase canceling of the sound waves oscillated from the adjacent transducers, and to narrow down the directivity of the sound waves with high efficiency.

It is a typical top view which shows the structure of the electroacoustic transducer which is an oscillation apparatus of embodiment of this invention. It is a typical vertical front view which shows the structure of an electroacoustic transducer. It is a typical top view which shows the structure of the electroacoustic transducer of one modification. It is a typical top view which shows the structure of the electroacoustic transducer of another modification.

  An electroacoustic transducer 100 that is an oscillation device of the present embodiment will be described below with reference to FIGS. 1 and 2. As shown in FIG. 1, an electroacoustic transducer 100 according to the present embodiment has a plurality of piezoelectric elements 111 that expand and contract when an electric field is applied, and an elongated shape in which a plurality of piezoelectric elements 111 are individually attached to one end. A plurality of elastic members 112 and a frame-shaped support member 120 that supports the other ends of the plurality of elastic members 112 are provided.

  In the electroacoustic transducer 100 of this embodiment, the support member 120 is formed in a rectangular shape with a planar shape, and the elastic member 112 is supported at the other end by two opposite sides of the support member 120. More specifically, the support member 120 is formed in a rectangular shape having a planar shape and four sides on the front, rear, left and right sides, and a plurality of elastic members 112 are elongated in the left and right direction and arranged in the front and rear direction. The aspect ratio of the elastic member 112 is 3 to 10, for example.

  However, the elastic members 112 are arranged in two right and left rows, and the piezoelectric element 111 is attached to the left end of the right elastic member 112 and the piezoelectric element 111 is attached to the right end of the left elastic member 112. In the electroacoustic transducer 100 of the present embodiment, a rectangular piezoelectric element 111 is formed over the entire upper surface of one end of the rectangular elastic member 112.

  The electroacoustic transducer 100 according to the present embodiment is connected to a driver circuit 130 that is an oscillation drive unit that outputs a sound wave in the audible range to the piezoelectric vibrator 110 including the piezoelectric element 111 and the elastic member 112.

  The mechanism of sound wave generation utilizes a stretching motion generated by applying an electric field to the piezoelectric element 111. Moreover, the frequency of an ultrasonic wave is limited to 20 kHz or more. Since the piezoelectric element 111 has a high mechanical quality factor Q, energy is concentrated in the vicinity of the basic resonance, so that a high sound pressure level can be obtained at the basic resonance frequency, but the sound pressure is attenuated in other frequency bands. .

  In this configuration, since the ultrasonic wave limited to a specific frequency is oscillated, it is rather advantageous that the mechanical quality factor Q of the piezoelectric element 111 is high. In addition, since the basic resonance frequency of the piezoelectric vibrator is affected by the shape of the piezoelectric element 111, when the resonance frequency is adjusted to a high frequency band, for example, an ultrasonic band, it is advantageous for miniaturization.

  In this configuration, FM (Frequency Modulation) and AM (Amplitude Modulation) modulated ultrasonic waves are oscillated, and the modulated waves are demodulated using the non-linear state (dense state) of air to reproduce audible sound. Sound reproduction is performed based on the principle of a so-called parametric speaker. In the electroacoustic transducer 100 of the present embodiment, the piezoelectric element 111 has a configuration limited to oscillation in a high frequency band, and thus can be miniaturized.

  In the configuration as described above, the electroacoustic transducer 100 of the present configuration performs acoustic reproduction using the principle of a parametric speaker that uses ultrasonic waves as a carrier wave of sound. By utilizing the principle of this parametric speaker, a super-directional sound field can be formed. In order to control the directivity of sound waves, it is preferable to emit sound waves from a plurality of arrayed piezoelectric vibrators 110 as in the phased array method, and the electroacoustic transducer 100 of this configuration is also arranged in an array. A super-directional sound field can be formed by using a plurality of arranged piezoelectric vibrators 110.

  In the electroacoustic transducer 100 according to the present embodiment, a plurality of piezoelectric elements 111 are individually attached to one end of a plurality of elongated elastic members 112 whose other ends are supported by a frame-shaped support member 120 as described above. Has been.

  Since the cantilever support structure is used in this way, the sound wave radiating portion is limited to the end portion of the piezoelectric vibrator 110 including the elastic member 112 and the piezoelectric element 111. For this reason, the sound wave radiation positions of the adjacent piezoelectric vibrators 110 can be brought close to each other. That is, by controlling the distance in the minor axis direction between the piezoelectric vibrators 110, it is possible to suppress the phase canceling of the sound waves oscillated from the adjacent piezoelectric vibrators 110, and to narrow down the directivity of the sound waves with high efficiency. be able to.

  When a plurality of piezoelectric elements 111 are driven by the driver circuit 130, the same drive signal may be input to all to generate highly directional sound waves with high efficiency. The output direction of highly efficient sound waves with high directivity may be controlled by individually controlling the signals.

  The present invention is not limited to the present embodiment, and various modifications are allowed without departing from the scope of the present invention. For example, in the above embodiment, the unimorph electroacoustic transducer 100 in which only the upper surface of the elastic member 112 is restrained by the piezoelectric element 111 is illustrated. However, it is also possible to implement a bimorph structure oscillation device in which the upper and lower surfaces of the elastic member 112 are constrained by two piezoelectric elements 111. In this case, it is possible to output a large volume more efficiently without increasing the size of the entire apparatus.

  Further, in the above embodiment, the elastic members 112 are arranged in two right and left rows, the piezoelectric element 111 is attached to the left end of the right elastic member 112, and the piezoelectric element 111 is attached to the right end of the left elastic member 112. Exemplified that

  However, like the electroacoustic transducer 200 illustrated as an oscillation device in FIG. 3, a plurality of elastic members 112 may be formed in four directions from the four sides of the rectangular support member 120 in a hook shape. Further, like the electroacoustic transducer 300 illustrated as an oscillation device in FIG. 4, the support member 310 may be formed in a circular shape, and the plurality of elastic members 112 may be formed in a radial shape.

  Moreover, in the said form, it assumed that the piezoelectric element 111 consists of one piezoelectric layer. However, the piezoelectric element may have a laminated structure in which piezoelectric layers and electrode layers are alternately laminated (not shown).

  Furthermore, in the said form, it illustrated that the rectangular piezoelectric element 111 was formed in the whole region of the one end upper surface of the rectangular elastic member 112. FIG. However, a small piezoelectric element (not shown) may be formed on a part of the upper surface of one end of the rectangular elastic member 112.

  Further, in the above embodiment, the elastic members 112 are arranged in two right and left rows, the piezoelectric element 111 is attached to the left end of the right elastic member 112, and the piezoelectric element 111 is attached to the right end of the left elastic member 112. Exemplified that However, for example, a one-row structure in which the elastic member 112 is not formed on one of the left and right sides can be implemented.

  Further, in the above embodiment, an electronic device in which the electroacoustic transducer 100 is connected to the driver circuit 130 that is an oscillation driving unit is assumed. However, such an electroacoustic transducer 100, an oscillation drive unit that outputs an ultrasonic wave to the electroacoustic transducer 100, and an ultrasonic wave that is detected from the ultrasonic wave that is oscillated from the electroacoustic transducer 100 and reflected by the measurement object. An electronic device (not shown) such as a sonar that includes a detection unit and a distance measurement unit that calculates a distance from the detected ultrasonic wave to the measurement target can also be implemented.

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

DESCRIPTION OF SYMBOLS 100 Electroacoustic transducer 110 Piezoelectric vibrator 111 Piezoelectric element 112 Elastic member 120 Support member 130 Driver circuit 200 Electroacoustic transducer 300 Electroacoustic transducer 310 Support member

Claims (6)

A plurality of piezoelectric elements that expand and contract by application of an electric field;
A plurality of elongated elastic members in which a plurality of the piezoelectric elements are individually attached to one end;
A frame-like support member supporting the other ends of the plurality of elastic members;
An oscillation device having The support member is formed in a rectangular shape with a planar shape,
The oscillation device according to claim 1, wherein the elastic member has the other end supported by at least one side of the support member.   The elastic member is arranged in two right and left rows, the piezoelectric element is attached to the left end of the right elastic member, and the piezoelectric element is attached to the right end of the left elastic member. The oscillation device described.   4. The oscillation device according to claim 1, wherein one piezoelectric element is mounted on each side of each of the plurality of elastic members. 5. The oscillation device according to any one of claims 1 to 4,
An oscillation driver for outputting an ultrasonic wave demodulated into an audible sound wave to the oscillation device;
Electronic equipment having The oscillation device according to any one of claims 1 to 4,
An oscillation driver that outputs ultrasonic waves to the oscillation device;
An ultrasonic detector for detecting the ultrasonic wave oscillated from the oscillation device and reflected by the measurement object;
A distance measuring unit for calculating a distance from the detected ultrasonic wave to the measurement object;
Electronic equipment having

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