JPH057397A - Electrostatic type converter - Google Patents

Abstract

PURPOSE: To prevent the trouble between a diaphragm and a counter electrode, namely dew condensation in an insulating section or to prevent it from becoming conductive, at least. CONSTITUTION: An electric insulating member 3 has, as a whole or at least partially, at least 1/3 of the volume heat capacity and at least 10<-2> time the heat conductivity compared to at least the counter electrode 2 and a casing 6 enveloping a converter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic converter including a diaphragm, a counter electrode, and an electric insulating member arranged between them.

[0002]

2. Description of the Prior Art Electrostatic transducers of the above type belong to the prior art and are known from the specialist literature. A description of such a transducer is given, for example, in "Funkschau", published in August 1971, under the title "Technical and acoustic advances in the construction of condenser-microphone-capsule".
It is described in the 15th special edition of the magazine.

All electrostatic converters known to date have a high surface resistance of the insulating material inside the converter when condensation of condensed water forms on the surface when the relative humidity of the air is 100%. It has the drawback of breaking. In this case, the locally formed conductive section causes a "sound" noise, which increases noise and, in some cases, causes a complete electrical failure of the electrostatic transducer. Only after a long recovery time is complete reuse possible. These phenomena, which are very serious obstacles caused by the formation of condensed water during operation, are uncomfortable, especially when the electrostatic transducer provided in the microphone is actually used, Suppressing these phenomena requires complex and time-consuming means, such as climatic matching of the microphones used to their surrounding climate.

[0004]

SUMMARY OF THE INVENTION The object of the invention is to prevent condensation in the problematic insulation section between the diaphragm and the counter electrode, or at least to prevent the formation of an insulation section which is electrically conductive. The purpose is to completely eliminate the above-mentioned drawbacks.

[0005]

Starting from the prior art, the problem is solved by the invention according to the characterizing part of claim 1, in which the electrically insulating member is wholly or at least partly as a counter electrode. , Having a volumetric heat capacity that is at least 1/3 smaller and a thermal conductivity that is at least 10 ⁻² times smaller than the casing surrounding the transducer.

[0006]

The ideal of the present invention is that the formation of dew condensation water on the surface of an object upon reaching the dew point is as fast as possible near the surface of the object in a dew condensation climate, relative humidity of the air. Is based on reaching a temperature that has not reached 100%. For this reason, the heat capacity and the thermal conductivity of the object must be significantly smaller than the heat capacity and the thermal conductivity of the objects that surround the object. The conductivity should be significantly less than the heat capacity and thermal conductivity of the other components. In the ideal case, dew condensation water is formed in the entire insulation section except the insulation surface, thereby maintaining the high resistance characteristic of the insulation.

Due to the very small heat capacity of the insulator, the heat exchange between the insulator and the moist air provides a temperature compensation as quickly as possible, whereas, even if the temperature difference is large. The very low thermal conductivity of the insulator ensures that the amount of heat dissipation is as minimal as possible. The condition that the heat capacity must be as low as possible is usually
This can be achieved by having the smallest possible mass of the insulation, which in practice is achieved by a sheet-like, diaphragm-like embodiment. Very low thermal conductivity is achieved by a special choice of insulating material, eg about 3.
Polyvinyl chloride having a specific thermal conductivity of 10 ⁻⁵ kcal / msec · deg is suitable. In addition to this, the idea of the invention is reflected in the embodiment of the structure corresponding to this idea of the insulating section and the part forming it.

In one advantageous embodiment of the invention,
The electrically insulating ring-shaped member as a whole forms an electrically insulating member between the diaphragm and the counter electrode, and the volume heat capacity of the counter electrode is smaller than the volume heat capacity of the counter electrode by 1/3 and the heat conduction is reduced. The rate is 10 ^-2 times smaller.

Even if the moist air entering the inside of the electrostatic converter reaches the dew point where condensed water is condensed on the surface of the object due to pressure and temperature, the insulating member formed as a ring-shaped member. Does not condense on the surface of, because the dew condensation of moisture is not promoted due to the above conditions for the properties of these parts. Since the insulating member has a smaller heat capacity than the other parts of the electrostatic converter, the insulating member is short enough to prevent the formation of dew condensation on the insulating member due to heat exchange with the air adjacent to the insulating member. The temperature of the adjacent air is reached in time.

In one advantageous embodiment of the invention,
The electrical insulating member is a disk made of an insulating material, the disk has a ring-shaped groove, and the disk forms a counter electrode as a metal deposition film except for a ring-shaped edge region including the groove, and the groove is formed. Is bridged by a ring made of an insulating sheet, the volumetric heat capacity of the ring is at least 1/3 smaller than the volumetric heat capacity of the disk supporting the insulating ring, and the thermal conductivity is at least 10 ^-2. Twice as small. The advantage of this embodiment of the invention is that known embodiments of electrostatic transducers can be used, by inserting a ring of insulating sheet according to the invention of a conventional electrostatic transducer. Imperfections can be eliminated immediately.

In another preferred embodiment of the invention, an electrically insulating member is provided with a brim between the counter electrode, which is formed in the shape of a dome, and the retaining ring, which stretches the diaphragm edge. It is formed as a ring, the collar-shaped rising insulating part is provided in the retaining ring, and the volumetric heat capacity of the insulating part is
Compared to the volumetric heat capacity of the transducer part that surrounds itself,
At least 1/3 smaller and has a thermal conductivity of at least 1
0 ^-2 times smaller. The embodiment according to the invention of the collar-shaped insulating part interrupts the insulating surface which has become conductive due to the condensation located between the counter electrode and the diaphragm over a relatively long section, which leads to the disadvantages mentioned at the outset. It will no longer appear.

Finally, in another advantageous embodiment of the present invention, the insulating member between the counter electrode and the conductive casing is formed as a truncated cone-shaped insulator forming body having a cylindrical portion, The volumetric heat capacity of the formed body is at least 1/3 smaller than that of the casing and the counter electrode,
The thermal conductivity is at least 10 ^-2 times smaller. Such electrostatic transducers, which have a casing that can be used as a conductor and in most cases the diaphragm is in conductive connection with the casing, provide a special insulating member between the casing and the transducer. Required, because the casing will always form condensed water on its surface when the dew point is reached. The present embodiment of the insulating member prevents the formation of a conductive moisture bridge between the casing and the conductive portion of the electrostatic transducer, which allows the insulating member to remain fully effective. To do. As a result, the above-mentioned type of operation failure does not occur.

[0013]

The present invention will be described in detail with reference to the drawings based on the embodiments.

An electrostatic transducer essentially consisting of a diaphragm 1, a counter electrode 2 and an electrically insulating member 3 arranged between them is shown in FIG. The diaphragm 1 has a conductive metal film 4 on the surface facing the outside, and the metal film 4 is conductively connected to a conductive casing 6 at an edge 5 thereof. The important point is that when the dew point is reached, the surfaces 7a and 7i of the electrically insulating member 3, which are highlighted by dashed lines, do not condense due to the moist air surrounding these surfaces, so that the insulation Member 3
That is, the surface has a high insulating property with respect to other parts of the electrostatic converter that are wet with dew condensation water. Due to the very small heat capacity and thermal conductivity of the insulation member 3 according to the invention with respect to the rest of the converter, condensation water deposits on the surface of the insulation member 3 even when the relative humidity is 100%. Guaranteed to never happen. This ensures that the electrostatic transducer operates without problems even at the highest humidity of the air. Reference numbers 8 and 9
Shows an electric terminal of the electrostatic converter which is drawn out to the outside. However, FIG. 1 shows an embodiment of the insulating member 3 which is ring-shaped as a whole, and the end of the insulating member 3 is formed in the shape of a stepped portion 10, whereby the counter electrode 2 and the diaphragm 1 are formed. The required spacing between is maintained. Normally this distance is 20μ depending on the particular configuration of the electrostatic transducer.
m to 60 μm. In this case, the important point is to form the entire insulation section in such a way that if condensation forms in the region of this very low step 10, it does not impair the high resistance of the entire insulation section. For example, other areas of the insulation section may be realized particularly long.

FIG. 2 shows one advantageous embodiment of the invention. The counter electrode 11, which is formed as a disk of ceramic material, has a ring-shaped groove 13 in its edge region 12. In the present invention, the groove 13 is bridged by a ring-shaped insulating sheet 14, and the insulating ring is bonded to the counter electrode 11 at its inner edge and outer edge. For acoustic reasons, a support member for the bottom part of the groove 13 which is not shown in the drawing and has the shape of a nodular ridge, a groove-shaped recess or a trough-shaped recess carved in the insulating sheet 14 is provided. It may be necessary.

In the embodiment shown in FIG. 3, a dashed line is shown between the counter electrode 15 formed in a dome shape and the retaining ring 17 stretching the diaphragm end 16. , An insulating surface 18 of a ring 19 in the form of a collar ring located between them. An insulating portion 20 that stands up in a collar shape is provided on the bottom surface of the ring 19 of the brim ring shape.
The arrangement and properties according to the invention of the invention interrupt the electrically conductive part of the surface 18 forming the insulating member in the event of condensation of moisture, thereby retaining the required high resistance insulation.

Finally, FIG. 4 shows a use example in which the insulating member between the counter electrode 21 and the conductive casing 22 is formed as a truncated cone-shaped forming body 23 having a cylindrical portion. A simple insulating film, which is arranged only in the edge region 24, is not sufficient to guarantee a sufficient insulation during condensation, because the insulating film is so thin that condensation on both sides at its edges. This is because it is unavoidable that water bridges. The desired result can be obtained only by forming the insulating sheet according to the present invention and adding the conditions of the present invention thereto.

[Brief description of drawings]

1 is a cross-sectional view of one principle embodiment of the present invention.

FIG. 2 is a cross-sectional view of one embodiment having an insulating ring bridging a groove.

FIG. 3 is a cross-sectional view of an embodiment having an insulating section having a collar-shaped rising portion.

FIG. 4 is a cross-sectional view of an embodiment in which an insulating member is arranged between the casing and the electrostatic converter.

[Explanation of symbols]

1 diaphragm 2 Counter electrode 3 Insulation member 4 metal film 5 edge 6 casing 7a, 7i Insulation member surface 10 steps 11 Counter electrode 12 Edge area 13 groove 15 Counter electrode 16 diaphragm edge 17 retaining ring 18 insulating surface 19 ring 20 insulation 21 Counter electrode 22 casing 23 Formed bodies 24 Edge area

Claims (5)

[Claims] 1. An electrostatic transducer comprising a diaphragm, a counter electrode, and an electrically insulating member disposed therebetween, wherein the electrically insulating member is wholly, or at least partially, the counter electrode and the converter. Electrostatic converter having a volumetric heat capacity that is at least 1/3 smaller and a thermal conductivity that is at least 10 ^-2 times smaller than the casing (6, 22) enclosing the container. . 2. The electrically insulating ring-shaped member (3) as a whole forms an electrically insulating member between the diaphragm (1) and the counter electrode (2), and the volume heat capacity of the counter electrode (2) is The electrostatic converter according to claim 1, characterized in that it is at least 1/3 smaller than the volumetric heat capacity of the counter electrode and at least 10 ^-2 times smaller in thermal conductivity (Fig. 1). 3. The electrically insulating member is a disk (11) made of an insulating material, and the disk (11) has a ring-shaped groove (1).
3), the disk (11) forms a counter electrode as a metal deposition film except for a ring-shaped edge region (12) including a groove, and the groove is bridged by an insulating ring (14). The volumetric heat capacity of the ring (14) is
4. The thermal conductivity is at least 1/3 smaller and the thermal conductivity is at least 10 ^-2 times smaller than the volumetric heat capacity of the disc (11) supporting 4) (FIG. 2).
The electrostatic converter according to. 4. An electrically insulating member is provided with a brim ring (19) between a counter electrode (15) formed in a dome shape and a retaining ring (17) stretching a diaphragm edge (16). ), A collar-shaped insulating part (20) is provided in the retaining ring (17), and the volumetric heat capacity of the insulating part (20) is the volume of the transducer part surrounding the insulating part (20). An electrostatic converter according to claim 2, characterized in that it is at least 1/3 smaller and has a thermal conductivity at least 10 ^-2 times smaller than the heat capacity (Fig. 3). 5. The insulating member (23) between the counter electrode (21) and the conductive casing (22) is formed as a truncated cone-shaped insulating forming body having a cylindrical portion, and the volume heat capacity of the forming body. The casing (22) and the counter electrode (21)
2. The electrostatic converter according to claim 1, wherein the volumetric heat capacity is at least 1/3 smaller and the thermal conductivity is at least 10 ^-2 times smaller (FIG. 4).