JPH01226300

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DESCRIPTION JPH01226300
[0001]
A. Industrial Field of Application The present invention relates to acoustic transducers that
convert electrical signals to sound. SUMMARY OF THE INVENTION The present invention
provides an acoustic transducer comprising a temperature dependent gas adsorbent, a heater
device for controlling the temperature of the gas adsorbent, and heater control means. In this
acoustic transducer, the temperature of the gas adsorbent is controlled according to the input
signal supplied to the heater control means, whereby adsorption and release of the gas by the
gas adsorbent are performed according to the input signal. Since the density of the gas density
around the gas adsorbent, which is generated by this adsorption and release, propagates as a
sound wave, good low-range regeneration can be performed regardless of the small
configuration. C0 Prior Art Conventionally, a so-called speaker device is known as an acoustic
transducer for converting an electrical signal into sound, which comprises an electromagnetic
driving means and a diaphragm driven by the electromagnetic driving means. In such an acoustic
transducer, the electromagnetic drive means includes, for example, a voice coil to which the
electric signal is supplied, a magnet for forming a magnetic field around the voice coil, and coke.
The voice coil generates a magnetic field in response to the electric signal, and is vibrated by the
action of the magnetic field and the magnetic field formed by the magnet or the like. When the
diaphragm is vibrated by transmitting the vibration of the voice coil to the diaphragm, rough
density occurs in the air density around the diaphragm. The density of this air density propagates
as a sound wave and becomes sound. By the way, in general, in an acoustic transducer, between
the volume of air excluded by the operation of the acoustic transducer and the sound pressure
level of the sound generated by the acoustic transducer. There is a certain relationship. And, in
the acoustic transducer comprising the diaphragm as described above, the volume of the air to be
removed has a fixed relationship with the amplitude of the diaphragm and the frequency of the
sound generated by the acoustic transducer. Therefore, a constant relationship is established
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between the sound pressure level and the amplitude and the frequency. That is, when trying to
obtain a constant sound pressure level regardless of the frequency, the amplitude of the
diaphragm is inversely proportional to the square of the frequency. Therefore, when performing
so-called low frequency reproduction, it is necessary to increase the amplitude of the diaphragm.
Thus, the low frequency side of the acoustic frequency that this acoustic transducer can generate
is limited by the maximum amount of amplitude of the diaphragm. Here, considering the size of
the diaphragm, when a predetermined sound pressure level is obtained at a predetermined
frequency, the amplitude of the diaphragm is inversely proportional to the area of the
diaphragm.
That is, if the area of the diaphragm is increased, the sound pressure level in the low range can
be secured with a smaller amplitude. However, when the diaphragm is enlarged in this manner, it
is necessary to make the so-called enclosure large in order to prevent the sound pressure
generated on the back side of the diaphragm from propagating to the front side. When the
enclosure is a so-called sealed type, if the acoustic frequency of the generated sound becomes
low due to the influence of the elastic force of the air inside the sealed enclosure (so-called air
channel 2) The level drops. In order to keep the influence of the air inside the enclosure on the
sound pressure level in the low region low, it is necessary to make the enclosure larger and
increase its internal volume. As described above, when it is intended to satisfactorily generate
low-frequency sound, there is a problem that the size of the diaphragm, the enclosure, etc. is
increased, and the entire acoustic transducer is enlarged. Then, this invention is proposed in view
of the above-mentioned situation, Comprising: It aims at providing the acoustic converter which
can perform favorable low-pass reproduction ¦ regeneration, without enlarging an apparatus
structure. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and
achieve the above object, an acoustic transducer according to the present invention comprises: a
gas adsorbent in which the amount of gas to be adsorbed changes according to a temperature
change; A heater device for heating the adsorbent and a heater control means for controlling the
heater device in accordance with an input signal are provided. In the acoustic transducer
according to the present invention, the temperature of the gas adsorber is controlled according
to the input signal supplied to the heater control means, whereby adsorption and release of gas
by the gas adsorber are input signals. In response, the density of the gas density around the gas
adsorbent generated by this adsorption and release propagates as a sound wave. G. Examples
Hereinafter, specific examples of the present invention will be described with reference to the
drawings. The acoustic transducer according to the present invention, as shown in FIG. 1, has a
heater device 2 with a gas adsorber 1 deposited on one surface, and a heater control means 3 for
controlling the temperature of the heater device 2. The gas adsorbent 1 is an alloy (so-called gas
storage alloy) having a predetermined composition. As such an alloy, ZEOLUM (trade name;
manufactured by Toyo Soda ■) as one that adsorbs nitrogen gas, HY-3 TOP (trade name;
manufactured by Showa Denko KK) etc. as one that adsorbs hydrogen gas, etc. Are known. When
the gas adsorbent 1 adsorbs a gas (gas), the reaction between the gas adsorbent 1 and the gas is
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an exothermic reaction, and conversely, the reaction when the gas adsorbent 1 releases the gas is
endothermic. It is a reaction.
Therefore, the amount of gas adsorbed by the gas adsorbent 1 is a predetermined amount
according to the temperature of the gas adsorbent 1 and the pressure around it. That is, in the
gas adsorbent for nitrogen, as shown in FIG. 2A, the pressure around the gas adsorbent and the
amount of nitrogen gas to be adsorbed are in a substantially proportional relationship, and the
higher the pressure, the more the adsorption. The quantity will increase. Further, due to the
temperature change of the gas adsorbent, as shown by (a), (b) and (c) in FIG. 2A, the adsorption
amount increases as the temperature is lower at the same atmospheric pressure. In addition, in
the case of a hydrogen gas adsorbent, as shown in FIG. 2B, when the pressure (hydrogen
pressure) around the gas adsorbent becomes higher, adsorption occurs when a predetermined
pressure is reached. The amount of hydrogen gas produced is rapidly increased. The
predetermined pressure at which the amount of adsorption sharply increases is (α), (β) in FIG.
2B. As indicated by (γ), the temperature changes according to the temperature of the gas
adsorbent, and the lower the temperature is, the lower the predetermined pressure is, and the
adsorption amount at an equal pressure is increased. Then, the amount of gas adsorbed or
released by the gas adsorbent 1 is about IW% 3% to 3W% with respect to the weight of the gas
adsorbent 1. That is, in 100 g of the gas adsorber 1, about 1 g to 3 g of gas can be adsorbed or
released. When this gas is hydrogen gas, 1 g to 3 g of gas occupies a volume of about 22A to
67β in a standard state. The heater device 2 is a device incorporating a predetermined heat
generating means, and has a flat plate-like heating portion 2a heated by the heat generating
means. And, the above-mentioned gas adsorbent 1 in the form of powder, for example, is
attached to the heating portion 2a. The gas adsorbent 1 in the heating unit 2a may be covered
and supported by, for example, a thin film made of a material having excellent thermal
conductivity, such as a porous copper plating film. Further, since the heater device 2 has a
calorific value sufficiently exceeding the specific heat of the gas adsorbent 1, the gas adsorbent 1
can be efficiently heated in a very short time. The gas adsorbent 1 causes an endothermic
reaction when it is heated, and as shown in FIG. 2A and FIG. 2B, the amount of gas to be
adsorbed decreases and releases the gas. Then, when the heating unit 2a is stopped from being
heated, the gas adsorbent 1 has a good thermal conductivity of the material supporting the gas
adsorbent 1, so that the surrounding area can be very short. It is cooled to the same temperature
as the temperature (room temperature).
When cooled, the gas adsorbent 1 causes an exothermic reaction, and the amount of gas to be
adsorbed increases to adsorb the gas. The heater control means 3 is configured to control the
heater device 2 in response to an input signal which is an input electric signal. That is, when the
input signal is higher (+) than the predetermined voltage level, the heater device 2 is controlled
to raise the temperature of the heating unit 2a. Conversely, when the input is smaller than the
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predetermined voltage level (-), the heater W2 is controlled to cool the heating unit 2a. The input
signal may be input to the heater control unit via the low pass filter 4. When the gas adsorbent 1
is for hydrogen gas, the gas adsorbent 1 is covered with a gas barrier film 5 made of a flexible
thin film such as a thin film made of polyvinyl resin, for example. The inside covered with the gas
barrier film 5 is filled with pure hydrogen gas. The pressure inside the inside covered by the gas
barrier film is detected by the pressure sensor 6 and the heater control means 2 is controlled
based on this detection signal to make the inside the same pressure as the pressure outside the
gas barrier film 5. To be That is, the reference state of the amount of adsorption of hydrogen gas
by the gas adsorbent 1 when the input signal is not supplied is changed to the predetermined
state. When the gas adsorbent 1 is for nitrogen gas, the gas barrier film 5 is not necessarily
required. In the acoustic transducer according to the present invention configured as described
above, when an input signal is supplied to the heater control means 3, the heater control means
3 generates the heater device 2 based on the supplied input signal. It controls and controls the
temperature of the said gas adsorbent 1 via the said heating part 2a. At this time, the
temperature of the gas adsorbent 1 is previously made sufficiently higher than the ambient
temperature (room temperature). This is to allow the gas adsorbent 1 to be rapidly cooled when
the heating of the gas adsorbent 1 by the heater device 2 is interrupted. By controlling the
temperature of the gas adsorbent 1 as described above, the adsorption amount of the gas by the
gas adsorbent 1 changes in response to the temperature change, that is, in response to the input
signal. The input signal is, for example, a signal corresponding to an acoustic wave of about 20
tlz to about 20, 00 OII z, and a signal whose voltage changes at the frequency.
Therefore, -F, the heater device 2 is also controlled at the above frequency, but is controlled
especially corresponding to the low frequency component. This is due to the characteristics such
as the specific heat of the heating unit 2a. Further, the input signal supplied to the heater control
means 3 may be a signal obtained by extracting + J which is a frequency component conforming
to the characteristics of the heater device 2 by the low pass filter 4. As the amount of gas
adsorbed by the gas adsorber 1 changes corresponding to the particularly low frequency
component of the input signal, the density of air pressure is generated around the gas adsorber
1, and this density is the sound wave To propagate. In this case, it is not always necessary to
repeat adsorption and release of all the amount of gas that can be adsorbed by the gas adsorbent
1 described above. That is, if a sufficient amount of the gas adsorber is provided, the gas
adsorbable by the gas adsorber occupies a large volume as described above (for example, 221 to
67A 'for 100 g of the gas adsorber for hydrogen gas). Therefore, a small amount of gas (for
example, about 0.1%) relative to the amount of gas that can be adsorbed can generate sufficient
sound by performing adsorption and release. A small amount of gas H with respect to the
amount of gas that can be adsorbed, the effect of the invention As described above, in the
acoustic converter according to the present invention, the gas adsorber according to the input
signal supplied to the heater control means The temperature is controlled so that adsorption and
release of the gas by the gas adsorber are performed in response to the input signal. Due to the
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adsorption and release of the gas by such a gas adsorber, a gas density denseness occurs around
the gas adsorber, and the gas density denseness propagates as a sound wave. Therefore, in the
acoustic converter according to the present invention, the sound pressure level does not decrease
even when the low frequency sound is generated. In addition, so-called super bass reproduction
is also possible. That is, the present invention provides an acoustic transducer which can perform
good low-pass reproduction in a small-sized apparatus configuration.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a schematic view showing the structure of an acoustic transducer according to the
present invention, and FIG. 2A is a view showing the characteristics of a gas adsorbent for
nitrogen which is an example of the gas adsorbent used for the acoustic transducer. FIG. 2B is a
view showing the characteristics of a gas adsorber for hydrogen which is another example of the
gas adsorber used in the acoustic transducer.
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