JP2012217041A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus provided with an oscillation device in which formation of a sound field can be controlled in the direction of travel of ultrasonic wave.SOLUTION: The electronic apparatus comprises a first oscillation device outputting a modulation wave of a parametric speaker, a second oscillation device outputting a modulation wave of a parametric speaker in the same direction as that of the first oscillation device, and a control unit connected with the first and second oscillation devices and controlling the outputs from the first and second oscillation devices independently from each other. The control unit controls the second oscillation device so as to output a modulation wave having a frequency lower than that of a modulation wave output from the first oscillation device, and controls the second oscillation device so that a phase of a sound wave demodulated by a modulation wave output from the second oscillation device has a phase opposite from that of a sound wave demodulated by a modulation wave output from the first oscillation device.

Description

  The present invention relates to an electronic apparatus having an oscillation device.

  As a technique related to a speaker, for example, there is a technique using ultrasonic waves. According to the parametric speaker using ultrasonic waves, it is possible to output sound waves with high directivity. Examples of the technology related to the parametric speaker include those described in Patent Documents 1 to 3.

The techniques described in Patent Documents 1 and 2 control the demodulation distance by controlling the frequency of the carrier wave. The technique described in Patent Document 3 relates to a speaker device including an audible speaker and an ultrasonic speaker.
In particular, the techniques described in Patent Documents 2 and 3 disclose speaker devices using piezoelectric vibrators.

  Other technologies related to speakers using piezoelectric vibrators include those described in Patent Document 4, for example. The technique described in Patent Document 4 is to provide a ring-shaped piezoelectric element having a film material attached to the back side of a small speaker.

JP 2006-81117 A JP 2006-245731 A JP 2007-67514 A JP 2008-211162 A

  Since the parametric speaker uses ultrasonic waves, a sound field having high directivity can be formed. However, it is difficult to control the distance direction regarding the formation of the sound field.

  An object of the present invention is to provide an electronic device including an oscillating device that can control a distance direction with respect to formation of a sound field.

According to the present invention, a first oscillation device that outputs a modulated wave of a parametric speaker;
A second oscillator that outputs a modulated wave of a parametric speaker in the same direction as the first oscillator;
A control unit connected to the first oscillation device and the second oscillation device, and controlling the outputs of the first oscillation device and the second oscillation device independently of each other;
With
The controller is
Controlling the second oscillating device to output a modulated wave having a frequency lower than the frequency of the modulated wave output from the first oscillating device;
The second oscillator so that the phase of the sound wave demodulated by the modulated wave output from the second oscillator is opposite to the phase of the sound wave demodulated by the modulated wave output from the first oscillator An electronic device for controlling is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic device provided with the oscillation apparatus which can perform control of a distance direction regarding formation of a sound field can be provided.

It is a mimetic diagram explaining control of sound field formation by electronic equipment concerning this embodiment. It is a block diagram which shows the structure of the electronic device shown in FIG. It is sectional drawing which shows the oscillation apparatus shown in FIG. It is sectional drawing which shows the piezoelectric vibrator shown in FIG. It is a graph explaining control of sound field formation by the electronic device shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  FIG. 1 is a schematic diagram for explaining control of sound field formation by the electronic apparatus 200 according to the present embodiment. FIG. 2 is a block diagram showing a configuration of the electronic device 200 shown in FIG. The electronic device 200 according to this embodiment includes an oscillation device 100, an oscillation device 102, and a control unit 90. The electronic device 200 is a mobile terminal device such as a mobile phone.

  The oscillation device 100 outputs a modulated wave of a parametric speaker. The oscillation device 102 outputs a modulated wave of a parametric speaker in the same direction as the oscillation device 100. The control unit 90 is connected to the oscillation device 100 and the oscillation device 102 and controls the outputs of the oscillation device 100 and the oscillation device 102 independently of each other. Further, the control unit 90 controls the oscillation device 102 so as to output a modulated wave having a frequency lower than the frequency of the modulated wave output from the oscillation device 100. Further, the control unit 90 determines that the phase of the sound wave demodulated by the modulated wave output from the oscillation device 102 is opposite to the phase of the sound wave demodulated by the modulated wave output from the oscillation device 100. 102 is controlled. Hereinafter, the configuration of the electronic device 200 will be described in detail.

FIG. 3 is a cross-sectional view showing the oscillation devices 100 and 102 shown in FIG. As shown in FIG. 3, the oscillation devices 100 and 102 include a piezoelectric vibrator 10, a vibration member 20, and a support member 30. The vibration member 20 restrains the piezoelectric vibrator 10 on one surface. The support member 30 holds the edge of the vibration member 20.
In the present embodiment, the resonance frequency of the piezoelectric vibrator 10 included in the oscillation device 102 is lower than the resonance frequency of the piezoelectric vibrator 10 included in the oscillation device 100.

  The vibration member 20 has, for example, a flat plate shape. The vibration member 20 is made of a material having a high elastic modulus with respect to a ceramic that is a brittle material, such as metal or resin, and is made of a general-purpose material such as phosphor bronze or stainless steel. The thickness of the vibration member 20 is preferably 5 to 500 μm. The longitudinal elastic modulus of the vibration member 20 is preferably 1 to 500 GPa. When the longitudinal elastic modulus of the vibration member 20 is excessively low or high, the vibration characteristics and reliability of the oscillation device may be impaired.

  4 is a cross-sectional view showing the piezoelectric vibrator 10 shown in FIG. As shown in FIG. 4, the piezoelectric vibrator 10 includes a piezoelectric body 70, an upper electrode 72, and a lower electrode 74. The piezoelectric body 70 is sandwiched between the upper electrode 72 and the lower electrode 74. The piezoelectric body 70 is polarized in the thickness direction (vertical direction in FIG. 4). The piezoelectric vibrator 10 has, for example, a circle or an ellipse in a plane direction parallel to one surface of the vibration member 20.

The piezoelectric body 70 is made of a material having a piezoelectric effect, for example, lead zirconate titanate (PZT) or barium titanate (BaTiO ₃ ) as a material having high electromechanical conversion efficiency. The thickness of the piezoelectric body 70 is preferably 10 μm to 1 mm. When the thickness is less than 10 μm, the piezoelectric body 70 is made of a brittle material, and thus is easily damaged during handling. On the other hand, when the thickness exceeds 1 mm, the electric field strength of the piezoelectric body 70 is reduced. For this reason, the energy conversion efficiency is reduced.

  The upper electrode 72 and the lower electrode 74 are made of a material having electrical conductivity, for example, silver or a silver / palladium alloy. Silver is a low-resistance general-purpose material and is advantageous from the viewpoint of manufacturing cost and manufacturing process. Further, the silver / palladium alloy is a low resistance material excellent in oxidation resistance and excellent in reliability. The thickness of the upper electrode 72 and the lower electrode 74 is preferably 1 to 50 μm. When the thickness is less than 1 μm, it becomes difficult to form the film uniformly. On the other hand, when the thickness exceeds 50 μm, the upper electrode 72 or the lower electrode 74 serves as a restraint surface with respect to the piezoelectric body 70 and causes a decrease in energy conversion efficiency.

  As shown in FIG. 2, the electronic device 200 includes a signal generation unit 92. The signal generator 92 is connected to each of the piezoelectric vibrators 10 included in the oscillation device 100 and the oscillation device 102, and generates an electric signal input to each piezoelectric vibrator 10. The control unit 90 is connected to the signal generation unit 92 and controls signal generation by the signal generation unit 92. The control unit 90 can control the output of the oscillation device 100 and the oscillation device 102 by controlling the signal generation of the signal generation unit 92 based on information input from the outside. Further, the control unit 90 can control the oscillation device 100 and the oscillation device 102 so as to output sound waves having different frequencies.

  In the present embodiment, the oscillation device 100 and the oscillation device 102 are used as parametric speakers. When the oscillation device 100 and the oscillation device 102 are used as a parametric speaker, the control unit 90 inputs a modulation signal as a parametric speaker via the signal generation unit 92. In this case, the piezoelectric vibrator 10 uses a sound wave of 20 kHz or more, for example, 100 kHz, as a signal transport wave.

Note that the oscillation device 100 can also be used as a normal speaker. When the oscillation device 100 is used as a normal speaker, the control unit 90 inputs an audio signal as it is to each piezoelectric vibrator 10 via the signal generation unit 92.
The oscillation device 100 can also be used as a sound wave sensor. When the oscillation device 100 is used as a sound wave sensor, the signal input to the control unit 90 is a command signal for oscillating sound waves. When the oscillation device 100 is used as a sound wave sensor, the signal generation unit 92 causes each piezoelectric vibrator 10 to generate a sound wave having a resonance frequency of each piezoelectric vibrator 10.

Next, control of sound field formation by the electronic device 200 according to the present embodiment will be described.
FIG. 5 is a graph for explaining the control of the sound field formation by the electronic device 200 shown in FIG. Specifically, a state of distance attenuation between an ultrasonic wave of 20 kHz and an ultrasonic wave of 60 kHz is shown. The directivity of ultrasonic waves increases as the frequency decreases. Along with this, distance attenuation tends to occur in the ultrasonic wave, so that the ultrasonic reach distance is shortened. On the other hand, the ultrasonic wave has higher directivity as the frequency is higher. For this reason, distance attenuation is unlikely to occur in the ultrasonic waves, and the ultrasonic reach distance becomes long.

In the present embodiment, the modulated wave output from the oscillation device 102 has a lower frequency than the modulated wave output from the oscillation device 100. For this reason, as shown in FIG. 1, the demodulation region 42 formed by the modulated wave output from the oscillation device 102 is more electronic device 200 than the demodulation region 40 formed by the modulated wave output from the oscillation device 100. The distance from is short.
In this embodiment, the phase of the sound wave demodulated by the modulated wave output from the oscillation device 102 is opposite to the phase of the sound wave demodulated by the modulated wave output from the oscillation device 100. For this reason, in the portion where the demodulation region 40 and the demodulation region 42 overlap, the sound waves forming each cancel each other. That is, in the canceling region 44 in FIG. 1, the sound wave that forms the demodulation region 40 is canceled by the sound wave that forms the demodulation region 42.

Therefore, a sound field is not formed in a portion of the demodulation region 40 that overlaps the demodulation region 42, and a sound field is formed in a portion of the demodulation region 40 that does not overlap the demodulation region 42. That is, a sound field is not formed by a portion near the electronic device 200 in the demodulation region 40, and a sound field is formed by a portion far from the electronic device 200.
In this way, control in the distance direction can be performed with respect to the formation of the sound field. The distance direction refers to a direction that coincides with the traveling direction of the ultrasonic wave.

  Next, the effect of this embodiment will be described. In the electronic device 200 according to the present embodiment, the control unit 90 controls the oscillation device 102 so as to output a modulated wave having a frequency lower than the frequency of the modulated wave output from the oscillation device 100. In addition, the control unit 90 determines that the phase of the sound wave demodulated by the modulated wave output from the oscillation device 102 is opposite to the phase of the sound wave demodulated by the modulated wave output from the oscillation device 100. 102 is controlled.

According to the above-described configuration of the present embodiment, the sound is generated in the portion of the demodulation region 40 formed by the modulated wave output from the oscillation device 100 that overlaps the demodulation region 42 formed by the modulated wave output from the oscillation device 102. A field is not formed, and a sound field is formed in a portion of the demodulation region 40 that does not overlap the demodulation region 42. That is, a sound field is not formed by a portion near the electronic device 200 in the demodulation region 40, and a sound field is formed by a portion far from the electronic device 200.
Therefore, it is possible to provide an electronic device including an oscillation device that can perform control in the distance direction regarding the formation of a sound field.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Piezoelectric vibrator 20 Vibrating member 30 Support member 40 Demodulation area 42 Demodulation area 44 Canceling area 70 Piezoelectric body 72 Upper electrode 74 Lower electrode 90 Control part 92 Signal generation part 100 Oscillator 102 Oscillator 200 Electronic equipment

Claims (3)

A first oscillation device that outputs a modulated wave of a parametric speaker;
A second oscillator that outputs a modulated wave of a parametric speaker in the same direction as the first oscillator;
A control unit connected to the first oscillation device and the second oscillation device, and controlling the outputs of the first oscillation device and the second oscillation device independently of each other;
With
The controller is
Controlling the second oscillating device to output a modulated wave having a frequency lower than the frequency of the modulated wave output from the first oscillating device;
The second oscillator so that the phase of the sound wave demodulated by the modulated wave output from the second oscillator is opposite to the phase of the sound wave demodulated by the modulated wave output from the first oscillator Control electronic equipment. The electronic device according to claim 1,
The first oscillation device and the second oscillation device have a piezoelectric vibrator,
An electronic apparatus in which a resonance frequency of the piezoelectric vibrator included in the second oscillation device is lower than a resonance frequency of the piezoelectric vibrator included in the first oscillation device. The electronic device according to claim 1 or 2,
The electronic device is an electronic device which is a mobile terminal device.

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