JPH01226300A - Sound converter - Google Patents

Abstract

PURPOSE:To realize the favorable reproduction of a low band without making device constitution large-sized by controlling the temperature of gas adsorbent according to an input signal to be supplied to a heater controlling means. CONSTITUTION:When the input signal is larger (+) than a prescribed voltage level, the temperature of a heating part 2a is raised by controlling a heater device 2, and on the contrary, when it is smaller (-), the heating part 2a is cooled. A heater controlling means 3 controls the heater device 2 according to the input signal to be supplied, and controls the temperature of the gas adsorbent 1 through the heating part 2a. Thus, the adsorption quantity of gas by the gas adsorbent 1 changes correspondingly to the input signal. Owing to a fact that the quantity of the gas the adsorbent 1 adsorbs changes as corresponding especially to the low band component of the input signal, the rarefaction and the condensation of air pressure is caused around this gas adsorbent 1, and this rarefaction and this condensation are propagated as a sound wave.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an acoustic transducer for converting electrical signals into sound.

B1 Summary of the Invention The present invention provides an acoustic transducer comprising a temperature-dependent gas adsorbent, a heater device and heater control means for controlling the temperature of the gas adsorbent. In this acoustic transducer, the temperature of the gas adsorbent is controlled according to the input signal supplied to the heater control means, so that the gas adsorbent adsorbs and releases gas according to the input signal. Since the density of the gas around the gas adsorbent caused by this adsorption and release is propagated as sound waves, good low frequency reproduction can be performed despite the compact configuration.

C0 Conventional technology Conventionally, as an acoustic transducer that converts an electric signal into sound,
A so-called speaker device is known that includes an electromagnetic drive means and a diaphragm driven by the electromagnetic drive means.

In such an acoustic transducer, the electromagnetic driving means includes, for example, a voice coil to which the electric signal is supplied;
It consists of a magnet and a cork that create a magnetic field around the voice coil. The voice coil generates a magnetic field in response to the electric signal, and is caused to vibrate by the action of this magnetic field and a magnetic field formed by the magnet or the like. When the vibration of the voice coil is transmitted to the diaphragm to cause the diaphragm to vibrate, the air density around the diaphragm becomes uneven. This density of air propagates as sound waves, resulting in sound.

D9 Problems to be Solved by the Invention Generally, in an acoustic transducer, there is a difference between the volume of air removed 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.

In the above-mentioned acoustic transducer including a diaphragm, the volume of the displaced air has a certain relationship with the amplitude of the diaphragm and the frequency of the sound generated by the acoustic transducer. Therefore, a certain relationship is established between the sound pressure level, 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. Therefore, the low frequency side of the sound that can be generated by this acoustic transducer is limited by the maximum amplitude of the diaphragm.

Now, considering the size of the diaphragm, in order to obtain a predetermined sound pressure level at a predetermined frequency, the amplitude of the diaphragm is inversely proportional to the area of the diaphragm. That is, by increasing the area of the diaphragm, a sound pressure level in the low range can be secured with a smaller amplitude. However, when the diaphragm is made larger in this way, it is necessary to make a so-called enclosure larger in order to prevent the sound pressure generated on the back side of the diaphragm from propagating to the front side. In addition, when this enclosure is a so-called sealed type, due to the influence of the elastic force of the air inside this closed type enclosure (so-called air 2), when the frequency of the sound generated becomes low, the sound pressure increases. Level decreases. In order to suppress the influence of the air inside such an enclosure on the sound pressure level in the low range, it is necessary to make the enclosure larger and increase its internal volume.

As described above, when attempting to generate low-frequency sound in a good manner, the diaphragm, enclosure, etc. become larger, and the entire acoustic transducer becomes larger.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and an object of the present invention is to provide an acoustic transducer that can perform good low frequency reproduction without increasing the size of the device configuration.

80 Means for Solving the Problems In order to solve the above problems and achieve the above objects, an acoustic transducer according to the present invention includes a gas adsorbent whose amount of gas to adsorb changes according to temperature changes, and a gas adsorbent that changes the amount of gas adsorbed according to temperature changes. It is characterized by comprising a heater device that heats the adsorbent, and a heater control means that controls the heater device according to an input signal.

F0 action In the acoustic transducer according to the present invention, the temperature of the gas adsorbent is controlled in accordance with the input signal supplied to the heater control means, so that the adsorption and release of gas by the gas adsorbent is controlled according to the input signal. The density of the gas around the gas adsorbent caused by this adsorption and release propagates as sound waves.

G. Examples Specific examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the acoustic transducer according to the present invention includes a heater device 2 on which a gas adsorbent 1 is attached, 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. Examples of such alloys include ZEOLUM (trade name; manufactured by Toyo Soda ■) that adsorbs nitrogen gas, and HY-3TOP (trade name; manufactured by Showa Denko ■) that adsorbs hydrogen gas. Are known.

When this gas adsorbent 1 adsorbs gas,
The reaction between the gas adsorbent 1 and the gas is an exothermic reaction, and conversely, the reaction when the gas adsorbent 1 releases gas is an endothermic reaction. Therefore, the amount of gas adsorbed by this gas adsorbent 1 is a predetermined amount depending on the temperature of this gas adsorbent 1 and the surrounding atmospheric pressure.

In other words, in a gas adsorbent for nitrogen, as shown in Figure 2A, there is a nearly proportional relationship between the atmospheric pressure around the gas adsorbent and the amount of nitrogen gas adsorbed, and the higher the atmospheric pressure, the more nitrogen gas is adsorbed. The quantity will be large. Also, due to the temperature change of this gas adsorbent, (a), (b), (c) are shown in Fig. 2A.
As shown in , at equal atmospheric pressure, the lower the temperature, the greater the amount of adsorption.

In addition, in a gas adsorbent for hydrogen, as shown in Figure 2B, as the atmospheric pressure (hydrogen pressure) around the gas adsorbent increases, the adsorption occurs when a certain predetermined atmospheric pressure is reached. The amount of hydrogen gas consumed increases rapidly. The predetermined atmospheric pressure at which this adsorption amount rapidly increases is shown in Figure 2B (α
), (β).

As shown by (γ), it changes depending on the temperature of the gas adsorbent, and the lower the temperature, the lower the predetermined atmospheric pressure becomes, and the amount of adsorption increases at the same atmospheric pressure.

The amount of gas adsorbed or released by this gas adsorbent 1 is about IW↑% to 3W% based on the weight of this gas adsorbent 1. That is, in the gas adsorbent 1 of 100 g, it is possible to adsorb or release about 1 g to 3 g of gas. When the 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 that incorporates a predetermined heat generating means, and has a flat heating section 2a that is heated by the heat generating means. The gas adsorbent 1, which is in the form of a powder, for example, is adhered to the heating portion 2a.

The gas adsorbent 1 in the heating section 2a is preferably covered and supported by a thin film made of a material with excellent thermal conductivity, such as a porous copper-plated film.

Furthermore, since the heater device 2 is configured to have a calorific value that sufficiently exceeds the specific heat of the gas adsorbent 1,
The gas adsorbent 1 can be efficiently heated in a very short time. When the gas adsorbent 1 is heated, it causes an endothermic reaction, and as shown in FIGS. 2A and 2B, the amount of gas adsorbed decreases and the gas is released. When heating of the heating section 2a is stopped, the gas adsorbent 1 will be able to absorb the surrounding air in a very short time because the material that supports the gas adsorbent 1 has good thermal conductivity. It is cooled to a temperature similar to the temperature (room temperature). When the gas adsorbent 1 is cooled, it causes an exothermic reaction and increases the amount of gas it adsorbs.

The heater control means 3 is configured to control the heater device 2 in response to an input signal that is an input electric signal. That is, when the input signal is higher than a predetermined voltage level (+), the heater device 2 is controlled to increase the temperature of the heating section 2a. Conversely, when the input voltage is lower than the predetermined voltage level (-), the heater device W2 is controlled so that the heating section 2a is cooled. Note that 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. The interior covered with this gas barrier film 5 is filled with pure hydrogen gas. The pressure sensor 6 detects the atmospheric pressure inside the gas barrier film, and the heater control means 2 is controlled based on this detection signal, so that the internal pressure is equal to that of the outside of the gas barrier film 5. I will make it happen. That is, the reference state of the amount of hydrogen gas adsorbed by the gas adsorbent 1 when the input signal is not supplied is changed to the predetermined state. Note that when the gas adsorbent 1 is for nitrogen gas, the gas barrier film 5 does not necessarily need to be provided.

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 controls the heater device 2 based on the supplied input signal, and controls the temperature of the gas adsorbent 1 via the heating section 2a. At this time, the temperature of the gas adsorbent 1 is set in advance to be sufficiently higher than the environmental temperature (room temperature). This is to ensure that the gas adsorbent 1 is quickly 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 amount of gas adsorbed by the gas adsorbent 1 changes in response to temperature changes, that is, in response to the input signal. The above input signal is, for example, 20 tlz to 20 tlz.
, 0OOIIz, and its voltage changes at the above frequency. therefore,
-F, the heater device 2 is also controlled at the above frequency, but it is controlled particularly in response to low frequency components. This is due to characteristics such as specific heat of the heating section 2a. Further, the input signal supplied to the heater control means 3 by the low-pass filter 4 may be a signal obtained by extracting a frequency component +J that matches the characteristics of the heater device 2.

As the amount of gas adsorbed by the gas adsorbent 1 changes in response to particularly the low-frequency component of the input signal, a density of atmospheric pressure occurs around the gas adsorbent 1, and this density causes an acoustic wave. propagate as.

In this case, it is not necessarily necessary that all of the amount of gas that can be adsorbed by the gas adsorbent 1 described above is repeatedly adsorbed and released. That is, if a sufficient amount of gas adsorbent is provided, the gas that can be adsorbed by this gas adsorbent occupies a large volume (for example, 221 to 67 g for 100 g of gas adsorbent for hydrogen gas).
A') Therefore, by adsorbing and releasing a small amount (for example, about 0.1%) of the adsorbable gas, sufficient sound can be generated. Effects of the Invention As described above, in the acoustic transducer according to the present invention, the amount of gas H is small compared to the amount of gas that can be adsorbed. The temperature is controlled so that the gas adsorbent adsorbs and releases gas in response to the input signal.

Such adsorption and release of gas by the gas adsorbent causes a difference in gas density around the gas adsorbent, and this difference in gas density propagates as a sound wave.

Therefore, in the acoustic transducer according to the present invention, the sound pressure level does not decrease even when low frequency sound is generated. It is also possible to reproduce so-called ultra-low frequencies.

That is, the present invention provides an acoustic transducer that can reproduce good low frequencies with a compact device configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an acoustic transducer according to the present invention, and FIG. 2A is a diagram showing the characteristics of a gas adsorbent for nitrogen, which is an example of a gas adsorbent used in the acoustic transducer. FIG. 2B is a diagram showing the characteristics of a gas adsorbent for hydrogen, which is another example of the gas adsorbent used in the acoustic transducer. 1... Gas adsorbent 2... Heater device 3... Heater control means

Claims (1)

[Scope of Claims] A gas adsorbent whose amount of adsorbed gas changes according to temperature changes, a heater device which heats the gas adsorbent, and a heater control means which controls the heater device according to an input signal. An acoustic transducer equipped with