KR100629688B1 - Unidirectional condenser microphone - Google Patents

Abstract

The present invention relates to a front sound unidirectional microphone, which employs a high-density PTFE filter of several hundred microns so that the rear sound is attenuated so that the sensitivity difference between the front sound and the back sound is sufficiently secured and the overall dimension thereof can be thinned.

According to a preferred embodiment, a plurality of rear sound inlet holes are formed on the bottom surface of which a FET for detecting a voice signal is disposed, and a plurality of front sound through holes on one surface are formed in an outwardly expanding shape on the annular indentation part. A sieve, a backplate via a PTFE filter and a spacer disposed inside the metal ring inside the metallic case body and disposed below the cap-shaped metallic connector defining a resonance space and functioning as an acoustic resistor to have directivity. And a diaphragm disposed to maintain a constant distance from the diaphragm so as to vibrate in response to the sound passing through the PTFE filter and the sound passing through the front sound through hole so that a change in distance (gap) from the back plate is detected. It comprises a nonwoven fabric affixed on one side outer side of a case body.

Description

Front sound unidirectional microphone {UNIDIRECTIONAL CONDENSER MICROPHONE}

1 is a view for explaining the outline of a general directional condenser microphone;

2 is an electrical equivalent circuit diagram of the directional condenser microphone shown in FIG. 1;

3 is a frequency response characteristic diagram of a unidirectional condenser microphone;

4 is a frequency response response characteristic of a unidirectional capacitor;

5A is a view showing an example in which the microphone is configured in the structure of a back electret type front sound unidirectional microphone according to a preferred embodiment of the present invention;

Figure 5b is a view showing an example in which the microphone is configured of a structure of a foil electret type front sound monodirectional microphone according to the present invention,

Figure 5c is a view showing an example in which the microphone is configured in the structure of a front electret type front sound unidirectional microphone according to the present invention,

6 is a view showing the structure of a metallic case body constituting the front sound unidirectional microphone according to the present invention,

7 is a view for explaining a ring-shaped metal ring member constituting the front sound monodirectional microphone according to the present invention.

* Description of the symbols for the main parts of the drawings *

10,50: metallic case body, 12,68: diaphragm,

14, 64: back plate, 18: ring-shaped connector,

22,56: FET, 24,52: PCB,

26: sintered filter, 60: cap-shaped metallic connector,

62: PTFE filter, 74: nonwoven fabric.

The present invention relates to a front sound unidirectional microphone, and more particularly, to a front sound unidirectional microphone having a structure in which a directional characteristic is maximized by employing a PTFE filter so as to optimize the sensitivity difference between the front sound and the back sound with a single direction.

As is well known, a microphone is essential for converting the sound into an electrical signal in an audio device that receives and post-processes a sound from an external source or a communication device (especially a mobile communication terminal) for exchanging sound. do.

1 is a view for explaining the outline of a general directional condenser microphone.

In the figure, the metallic case body indicated by 10 is usually made of aluminum to seal / compress the components of the corresponding microphone to prevent foreign substances from entering the outside and to function as a protective cap to prevent external electrical noise from entering. Done.

Diaphram on the front surface indicated by 12 is usually manufactured by vacuum deposition of Ni on PET or PPS film, and changes the distance (gap) caused by vibration by sound waves from the outside while keeping a small distance from the back plate described later. The action is caused to be induced by a change in electrical capacitance.

A polar ring, denoted by 12a, is manufactured by, for example, punching a SUS304 metal panel into a press mold and employed to support the diaphragm 12.

The back plate indicated by 14 is manufactured by pressing a panel in which a FEP film is adhered to a SUS plate with a press mold so that a plurality of sound wave inlet holes 14a are formed on the upper surface thereof, and is usually charged at a high voltage of several KV to serve as a bipolar plate. The charging potential determines the sensitivity of the corresponding microphone and the phenomenon is referred to as an 'electret'.

The spacer labeled 16 is disposed between the diaphragm 12 and the back plate 14 to serve as a gap body that maintains a constant gap therebetween, and serves as an electrical insulator. It is produced by punching into a press mold.

In addition, a ring-shaped connector indicated by 18 is employed to electrically connect the gate of the field effect transistor (FET) to be described later and the back plate 14, the ring-shaped connector 18 is usually brass It is prepared by pressing and then plating with gold.

The bipolar holder (IR ring) denoted as 20 is assembled with the back plate 12 and the ring-shaped connector 18 to act as a mechanical support and an insulator. Preferably, the bipolar holder 20 is made of ABS. Is produced by injection molding.

The FET denoted by 22 serves as an impedance converter which transmits the signal of the change to the amplifier (not shown) of the rear end as a result of the change in the capacitance of the diaphragm 12 as the change in the impedance.

The PCB marked 24 is formed with a number of back through holes 24a, which serve as the rear cover and output terminals of the corresponding directional condenser microphones, and the PCB 24 is in contact, pin and solder type depending on the application. It is composed.

The sintered filter indicated by 26 acts as a resistance to the sound, and attenuates the sound passing through the rear sound passing hole 24a of the PCB 24 so that the corresponding directional condenser microphone has a directing characteristic.

Here, the front filter of the directional condenser microphone shown in Figure 1 is generally formed of a nonwoven fabric in order to prevent the infiltration of dust or foreign matter inside.

2 shows an electrical equivalent circuit for the directional condenser microphone of the above-described configuration.

Referring to FIG. 3 and FIG. 4, when the microphone illustrated in FIG. 1 is unidirectional, the front sound 30 passes through the front filter and the sound wave inlet 10a of the metallic case body 10 is illustrated. It is introduced through the) to vibrate the diaphragm 12.

The diaphragm 12 vibrates in response to sound waves. When the vibration causes a change in distance (gap) between the back plate 14 and the change in capacitance with respect to the distance change, the FET 22 The electrical signal corresponding to the sound wave is transmitted to the control unit.

On the other hand, the rear sound 32 passes through the rear sound passing hole 24a of the PCB 24 and then directly attenuates through the sintered filter 26 as the acoustic wave resistor, and the attenuated sound wave is attenuated by the diaphragm. It will vibrate (12).

Accordingly, the rear reflection sound has a smaller level than the front sound, and thus has omnidirectional omnidirectional characteristics. Such a monodirectional microphone has a frequency response characteristic according to frequency shown in FIG. 4.

By the way, in the case of the unidirectional microphone, the front surface is set such that the rear sound 32 passes through the sintering filter 26 via the rear sound passing hole 24a of the PCB 24. The difference in sensitivity between the sound 30 and the back sound 32 is not sufficiently ensured, making it difficult to obtain an optimal single-directional effect.

In addition, the sintered filter 26 in the metallic case body 10 is manufactured by resin sintering, and a certain thickness is required for sufficient attenuation of the front sound 30 and the rear sound 32. This not only affects the miniaturization of the overall dimension but also has a high possibility of generating a difference in orientation characteristics depending on the degree of sintering in manufacturing the sintering filter 26.

Accordingly, the present invention has been made in view of the above-described circumstances of the prior art, and its first object is to sinter resin by applying a high-density PTFE filter having a fine thickness (hundreds of microns) as an acoustic resistor on the outer surface of the metallic case in the case of a single orientation. Compared to the case of employing a filter, it is possible to increase the sensitivity difference between the rear sound and the front sound, and to provide miniaturization of overall dimensions, thereby providing a front sound unidirectional microphone designed to reduce manufacturing labor and cost.

A second object of the present invention is to form a sound wave inlet for inflow of the rear sound on one surface of the output terminal PCB mounted with the FET and the cap-shaped connector therein so as to conduct a conductive connection with the gate which is the input terminal of the back plate and the FET. The inside of the shape connector is bonded to the outside of the PTFE filter to attenuate the rear sound transmitted to the diaphragm, and the metallic case body is formed with a front sound passing hole for passing the front sound, and by placing the PTFE filter between the back plate and the inside of the metallic connector. Resonance space is secured so that the output level is sufficiently compensated, and the nonwoven width filter is adhered to one side of the metallic case body to prevent the inflow of foreign matters, thereby providing a front sound unidirectional microphone having directivity to the front sound.

In order to achieve the above object, according to a preferred embodiment of the present invention, a plurality of rear sound inlet holes are formed and a bottom surface of which a FET for detecting a voice signal is disposed, and a plurality of front sound through holes on one surface are annular. The metallic case body formed in the outward expansion shape in the pressing portion, the cap-shaped metallic connector disposed inside the metal ring inside the metallic case body and defining a resonance space below, and disposed inside the metallic connector to have directivity characteristics. PTFE filter, which functions as an acoustic resistor, is arranged to maintain a constant distance from the back plate through a spacer, and vibrates in response to the sound passing through the PTFE filter and the sound passing through the front sound passing hole. Diaphragm to detect change in distance (gap) with respect to the outer surface of one surface of the metallic case body Yi unidirectional microphone is provided consisting of the front sound including fabric.

Preferably, the sound passing through the PTFE filter is a rear sound passing through the rear sound passing hole, and the rear sound is attenuated by the PTFE filter so that the level becomes smaller than the front sound passing through the front sound inlet hole. The front sound is unidirectional.

The back plate is charged with charge and connected to the gate of the FET, and the diaphragm on which the diaphragm is mounted is in electrical contact with the metallic case body to form an electric circuit, and the corresponding microphone has a back electret type.

In addition, the back plate is connected to the gate of the FET, and electric charges are accumulated in the diaphragm to form an electric circuit electrically connected to the metallic case body, and the corresponding microphone has a foil electret type.

According to another embodiment of the present invention, a plurality of rear sound inlet holes are formed and a bottom surface thereof has a PCB on which a FET for detecting a voice signal is disposed, and a plurality of front sound through holes on one surface thereof are formed in an outwardly expanding shape in an annular indentation portion. A metallic case body having a charge filled on one surface thereof, a cap-shaped metallic connector disposed inside the metal ring inside the metallic case body and having a resonance space defined below, and disposed inside the metallic connector on the rear surface of the metallic case body PTFE filter as an acoustic resistor for attenuating the sound passing through the sound inlet hole, the sound passing through the PTFE filter and the sound passing through the front sound passing hole disposed to maintain a constant distance from one surface of the metallic case body through a spacer A diaphragm for vibrating in response to detecting a change in distance (gap), and a portion attached to an outer side of one surface of the metallic case body Yi unidirectional microphone is provided consisting of the front sound including fabric.

The diaphragm in which the diaphragm is mounted is connected to the gate of the FET, and the corresponding microphone is configured as a front electret type.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

Figure 5a shows a configuration in which the microphone according to a preferred embodiment of the present invention is formed into a structure of a back- electret unidirectional microphone.

That is, referring to Figure 5a, the PCB 52 having the output terminal function disposed inside the metallic case body 50 is formed with a plurality of rear sound inlet holes (52a) for the passage of the rear sound (54), The FET 56 is disposed on the bottom of the PCB 52.

In addition, a metallic ring 58 is disposed inside the metallic case body 50, and a cap-shaped metallic connector 60 is disposed inside the metallic ring 58, and inside the metallic connector 60. Hundreds of microns of high density PTFE filter 62 functioning as an acoustic resistor is disposed, and by employing the cap-shaped metallic connector 60, a resonance space for sufficiently correcting the output level of the corresponding microphone is secured at the lower side thereof. A unidirectional microphone having directivity to the front sound is provided.

Here, the cap-shaped metallic connector 60 shown in FIG. 6 is formed in an open structure except for a support portion for seating the PTFE filter 62 on one surface thereof.

In addition, a back plate 64 filled with charge is disposed below the cap-shaped metallic connector 60, and the plate 64 is provided with a plurality of sound wave passing holes 64a.

The diaphragm 68 is disposed below the back plate 64 via a spacer 66 so as to maintain a constant distance with respect to the back plate 64, and the diaphragm support ring 70 is provided below the diaphragm 68. ) Is placed.

Preferably, one surface of the metallic case body 50 is formed with a front sound inlet hole 50a for the introduction of the front sound 72, referring to Figure 7 the front sound inlet hole 50a is a corresponding metallic case After pressing the outer side of one surface of the sieve 50 in an annular shape, it is formed into a shape that is outwardly expanded to the pressed portion, thereby improving the sensitivity of the corresponding microphone.

In addition, one surface of the metallic case body 50 is provided with a nonwoven fabric 74 to block the inflow of foreign matter.

Therefore, in the back electret type front sound directing microphone having the above-described structure, the front sound 72 passes through the nonwoven fabric 74 and the front sound inlet hole 50a of the metallic case body 50, and thus the diaphragm 68. The vibration of the diaphragm 68 causes the distance (gap) change generated between the back plate 64 and the back plate 64 to be transmitted to the FET 56 to be obtained as an electric signal.

On the other hand, the back sound 54 is passed through the PTFE filter 62 through the back sound inlet hole 52a of the PCB 52, the back sound 54 is the PTFE filter 62 After being attenuated at, the diaphragm 68 is transmitted to the diaphragm 68 through the sound wave passage 64a of the back plate 64, but the diaphragm 54 is attenuated by the PTFE filter 62. (68) will not be vibrated sufficiently.

Thus, the rear sound 54 is significantly reduced in level compared to the front sound 70, so that the corresponding microphone is sufficiently guaranteed the front sound unidirectional effect.

Figure 5b is a view showing a structure in which the microphone is composed of a foil electret-type front tone unidirectional microphone according to the present invention, in the case of the foil electret-type front tone unidirectional microphone shown in the figure the cap-shaped metallic connector 60 As the PTFE filter 62 is disposed as an acoustic resistor inside the, and the resonance space is secured by the metallic connector 60, the unidirectionality of the front sound is sufficiently ensured.

5C is a diagram illustrating a structure in which the microphone according to the present invention is constituted by a front electret-type front tone unidirectional microphone.

Referring to the drawings, the front electret-type front tone unidirectional microphone has a structure in which the back plate is excluded while the electric charge is charged to the bottom surface of the metallic case body 50 in the structure shown in FIG. 5A. to be.

In addition, a sufficient resonance space is secured to the lower side of the cap-shaped metallic connector 60 in which the PTFE filter 62 serving as the acoustic resistor 62 is disposed inside, so that the output level of the corresponding microphone is sufficiently corrected.

That is, even in the case of the front electret type front tone unidirectional microphone illustrated in FIG. 5C, the rear sound 54 passes through the back sound inlet hole 52a of the PCB 52 and is attenuated by the PTFE filter 81. It is transmitted to the diaphragm 68 in a state.

On the other hand, the front sound 72 passes through the nonwoven fabric 72 and then is transmitted to the diaphragm 68 via the front sound inlet hole 50a of the metallic case body 50.

Therefore, the back sound 54 attenuated by the PTFE filter 62 is reduced in level compared to the front sound 72, so that the corresponding microphone has a significant improvement in the front sound single direction effect.

On the other hand, the present invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the technical gist and gist of the invention.

As described above, according to the front-facing monodirectional microphone according to the present invention, it is possible to manufacture a compact size compared to the case of using a resin sintered filter by disposing a high-density PTFE filter of several hundred microns as an acoustic resistor inside the cap-shaped metallic connector. In addition, the sensitivity difference between the front sound and the back sound is sufficiently ensured that the single-directional effect is remarkably improved.

In addition, according to the present invention, as a sufficient resonance space is secured to the lower side of the metallic connector, a good correction of the output level of the corresponding microphone is possible.

Claims (6)

A plurality of rear sound inlet holes are formed, and on the bottom thereof, a FET for detecting a voice signal is disposed, and a PCB for internal arrangement of a metallic case body having an output terminal function; The metallic case body formed with a plurality of front sound through holes on one surface in the form of outward expansion in the annular indentation portion, A cap-shaped metallic connector disposed inside the metal ring in the metallic case body and defining a resonance space at a lower side thereof; A PTFE filter disposed inside the metallic connector and functioning as an acoustic resistor to have directivity characteristics; It is arranged to maintain a constant distance from the back plate via a spacer to vibrate in response to the sound passing through the PTFE filter and the sound passing through the front sound passing hole to detect a change in distance (gap) for the vibration from the back plate. Diaphragm made possible, The front sound unidirectional microphone, characterized in that it comprises a nonwoven fabric attached to the outer side of the metallic case body. According to claim 1, wherein the sound passing through the PTFE filter is a rear sound passing through the rear sound passing hole, the rear sound is attenuated by the PTFE filter is a level compared to the front sound passing through the front sound inlet hole. Frontal unidirectional microphone, characterized in that smaller. delete delete A plurality of rear sound inlet holes are formed, and on the bottom thereof, a FET for detecting a voice signal is disposed, and a PCB for internal arrangement of a metallic case body having an output terminal function; The metallic casing body in which a plurality of front through holes are formed in an outward expansion shape in an annular indentation portion on one surface thereof, and charges are charged on one surface thereof. A cap-shaped metallic connector disposed inside the metallic ring in the metallic case body and defining a resonance space under the metallic case, A PTFE filter disposed as an acoustic resistor disposed inside the metallic connector to attenuate the sound passing through the rear sound inlet; The diaphragm is arranged to maintain a constant distance from one surface of the metallic case body via a spacer to vibrate in response to the sound passing through the PTFE filter and the sound passing through the front sound passing hole to detect a change in distance (gap). , The front sound unidirectional microphone, characterized in that it comprises a nonwoven fabric attached to the outer side of the metallic case body. 6. The front sound unidirectional microphone according to claim 5, wherein the diaphragm on which the diaphragm is mounted is connected to the gate of the FET, and the corresponding microphone is a front electret type.

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