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JPWO2013160975

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DESCRIPTION JPWO2013160975
PROBLEM TO BE SOLVED: To reduce power consumption in a parametric speaker using
ultrasonic waves as a carrier wave, and to make it difficult for a vibrating element to be damaged
even if it receives an impact due to a drop or the like. A plurality of magnetostrictive elements 2
made of ferrite or the like are arranged in a matrix on the top surface of a circuit board 1. A voice
coil 3 is disposed around each magnetostrictive element 2. Then, when current flows in the voice
coil 3, the magnetostrictive element 2 itself expands and contracts in the central axis direction
(height direction), whereby the ultrasonic wave (carrier wave) is emitted from the
magnetostrictive element 2 into the air. In this case, since the magnetostrictive element 2 made
of ferrite or the like is used, power consumption can be reduced as compared with the case
where a piezoelectric vibrator is used, and the magnetostrictive element 2 is It can be made hard
to break. [Selected figure] Figure 1
スピーカ
[0001]
The present invention relates to a speaker.
[0002]
Among conventional loudspeakers, there is a so-called parametric loudspeaker using an
ultrasonic wave as a carrier wave (see, for example, Patent Document 1).
04-05-2019
1
In the loudspeaker described in Patent Document 1, a plurality of piezoelectric vibrators each
having a piezoelectric element are arranged in a matrix, and the ultrasonic waves (carrier waves)
modulated from the respective piezoelectric vibrators are radiated into the air, and the radiated
Ultrasonic waves are subjected to a non-linear phenomenon of air to generate demodulated
audible sounds.
[0003]
JP 2012-29102 A
[0004]
However, in the above-described conventional speaker, since the piezoelectric vibrator is used as
a generation source of the ultrasonic wave, the consumption of current increases under certain
conditions to be described later due to the characteristics of the piezoelectric element of the
piezoelectric vibrator. There is a problem that power consumption increases.
Further, when a ceramic material which is a brittle material is used as the piezoelectric element,
there is a problem that the piezoelectric element may be damaged when it receives an impact due
to a drop or the like.
[0005]
Therefore, it is an object of the present invention to provide a speaker that can reduce power
consumption under certain conditions, and can make it difficult for the vibrating element to be
damaged even if it receives an impact due to dropping or the like. .
[0006]
A speaker according to the present invention comprises a circuit board, a plurality of
magnetostrictive elements disposed on the circuit board, and a voice coil disposed around each
of the plurality of magnetostrictive elements. It is a thing.
[0007]
According to the present invention, power consumption under certain conditions can be reduced,
and the magnetostrictive element, which is a vibrating element, can be less likely to be damaged
even if it receives an impact due to dropping or the like.
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2
[0008]
The perspective view of the principal part of the speaker as one embodiment of this invention.
[0009]
FIG. 1 is a perspective view of the main part of a speaker according to an embodiment of the
present invention.
The speaker comprises a circuit board 1.
The lower surfaces of a plurality of cylindrical magnetostrictive elements 2 made of ferrite or the
like are fixed to a plurality of locations on the upper surface of the circuit board 1 with an
adhesive (not shown).
That is, the magnetostrictive element 2 is provided on the circuit board 1 so that the central axis
thereof is perpendicular to the circuit board 1.
[0010]
The magnetostrictive elements 2 are, for example, arranged in a 4 × 4 matrix.
Further, as an example, the outer diameter of the magnetostrictive element 2 is about 10 mm. A
voice coil 3 is disposed around each magnetostrictive element 2. The lower portion of each voice
coil 3 is fixed to the upper surface of the circuit board 1 via an adhesive (not shown).
[0011]
In this speaker, when current flows through the voice coil 3, the magnetostrictive element 2 itself
expands and contracts in the central axis direction (height direction). When the magnetostrictive
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3
element 2 itself expands and contracts in the central axis direction, an ultrasonic wave in a band
of a frequency of 20 kHz or more is generated. Then, when the modulated ultrasonic wave
(carrier wave) from the magnetostrictive element 2 is radiated into the air, the radiated ultrasonic
wave is subjected to the non-linear phenomenon of air, thereby generating a demodulated
audible sound.
[0012]
In this speaker, since the magnetostrictive element 2 made of ferrite or the like is used, the
magnetostrictive element 2 is superior to a piezoelectric vibrator using a ceramic material which
is a brittle material as a piezoelectric element even if it receives an impact due to dropping or the
like. It can be made hard to break. Further, in this speaker, since the magnetostrictive element 2
itself vibrates, a dedicated diaphragm is not necessary, and the size and thickness can be reduced
accordingly.
[0013]
Here, the directivity of the parametric speaker is determined by the linearity of the carrier wave
(ultrasound). In the case of a piezoelectric vibrator having a piezoelectric element, the directivity
becomes sharper as it shifts to a high frequency band, but on the other hand, the impedance
decreases due to the characteristics of the piezoelectric element, and the consumption of current
increases. , Power consumption increases. On the other hand, in this speaker, since the
magnetostrictive element 2 made of ferrite or the like is used, the impedance does not change
even if it is shifted to a high frequency band, and therefore the consumption of current does not
increase. Power consumption can be reduced as compared with the case of the piezoelectric
vibrator having.
[0014]
In addition, with this speaker, directivity can be easily controlled. That is, since the
magnetostrictive element 2 has a fundamental resonant frequency, the directivity can be easily
adjusted by adjusting the fundamental resonant frequencies of the plurality of magnetostrictive
elements 2 arranged in a matrix and arbitrarily changing the magnetostrictive element 2 to be
driven. Can be controlled. As a result, it is possible to easily adjust the directivity in accordance
with the use environment of the user.
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[0015]
As a method of adjusting the fundamental resonance frequency of the magnetostrictive element
2, since the thickness (height), the outer shape, and the like of the magnetostrictive element 2
can be mentioned as a determining factor of the fundamental resonance frequency, these may be
adjusted appropriately. For example, when the thickness of the magnetostrictive element 2 is
reduced, the fundamental resonance frequency is reduced. Further, when the outer diameter of
the magnetostrictive element 2 is increased, the fundamental resonance frequency is reduced.
[0016]
Further, in this speaker, when a plurality of ultrasonic waves having different frequencies are
emitted from the plurality of magnetostrictive elements 2, the band of the audible sound is
expanded by the interference of the ultrasonic waves of different frequencies, and the sound
pressure is amplified. High sound quality can be achieved.
[0017]
Hereinafter, aspects of the present invention will be collectively described as a supplementary
note.
[0018]
(Supplementary Note 1) The invention of Supplementary Note 1 includes a circuit board, a
plurality of magnetostrictive elements disposed on the circuit board, and a voice coil disposed
around each of the plurality of magnetostrictive elements. It is a speaker to be characterized.
[0019]
(Supplementary Note 2) In the invention according to Supplementary Note 2, in the invention
according to Supplementary Note 1, the magnetostrictive element has a cylindrical shape, and is
provided on the circuit board so that the central axis thereof is perpendicular to the circuit board.
It is a speaker characterized by being.
[0020]
(Supplementary Note 3) The invention according to supplementary note 3 is the speaker
according to supplementary note 1 or 2, wherein the magnetostrictive elements are arranged in a
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matrix.
[0021]
(Supplementary Note 4) The invention of Supplementary Note 4 relates to the speaker according
to any one of supplementary notes 1 to 3, wherein the respective fundamental resonance
frequencies of the plurality of magnetostrictive elements are different from each other.
[0022]
1 circuit board 2 magnetostrictive element 3 voice coil
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