CONDUCTIVE BASE OF CONDENSER MICROPHONE AND CONDENSER MICROPHONE USING THE SAME

Technical Field

[1] The present invention relates to a condenser microphone, and, more particularly, to a condenser microphone for preventing deformation of parts upon a curling process. Background Art

[2] A typical condenser microphone consists of a voltage bias element which is generally made of electret, a pair of a vibration membrane and a back plate for forming a capacitor which is changed corresponding to sound pressure, and a JFET for buffering an output signal. Here, the electret condenser microphone is formed with an electret on any one of the vibration membrane and the back plate thereof, wherein an electret which is formed on the vibration membrane is called a front electret, and an electret which is formed on the back plate is called a back electret. Generally, the electret is formed by forcibly applying electric charges into an organic film.

[3] Fig. 1 is a sectional side view of a condenser microphone assembly using a conventional case. The conventional microphone assembly has a case 10 which is formed with a sound hole 10c on a bottom surface thereof. The case 10 is provided with a vibration plate 12 which is consisted of a vibration membrane 12a and a polar ring 12b, a spacer 13, an insulating base 14, a back plate 15, a conductive base 16 and a PCB 18 therein. An opened end 10b of the case 10 is curled on the PCB 18.

[4] At this time, the conductive base 16 serves not only to transfer an electric signal generated from a microphone unit (that is, the vibration/back plate electret) to a JFET, an amplifier or elements having an amplifier and an AD converter, but also to mechanically fix parts inserted into the case.

[5] Further, since the conductive base 16 is higher than the insulating base 14, the PCB

18 presses the conductive base 16 when curling the case 10.

[6] However, according to the conventional microphone, in a curling process for rolling and bending the opened end of the case 10 on the PCB 18 while pressing toward the PCB 18, there happens a problem that an acoustic characteristic is deteriorated since a force for supporting the PCB 18 through the base is poor, the PCB 18 is bent due to tolerances of parts or parts within the case is deformed. Disclosure of Invention Technical Problem

[7] Accordingly, in order to solve the above problem, an object of the present invention is to provide a condenser microphone for preventing deformation of parts by allowing

a conductive base having a broad supporting surface which is formed by a shape of 'D' to support the PCB upon a curling process. Technical Solution

[8] According to an aspect of the present invention, there is provided a condenser microphone having a conductive base. The conductive base comprises a cylindrical body which is made of an electric conductor and has both sides which are opened; and a supporting part which is made of an electric conductor and has a supporting area for broadly supporting a PCB by allowing an upper surface of the body to be projected to the outside, wherein the supporting part for supporting a surface of the PCB is enlarged compared to the body upon a curling process, thereby enlarging the supporting area to prevent the PCB from being bent.

[9] Further, according to another aspect of the present invention, there is provided a condenser microphone comprising: a case which is formed with a sound hole on a bottom surface thereof; a vibration plate which is electrically connected with the case and is vibrated according to a sound pressure inputted through the sound hole; a back plate which faces the vibration plate with a spacer interposed therebetween and has an electret which is formed by adhering a high molecular film to an external side of a metal plate; an insulating base for insulating the back plate from the case; a conductive base including a cylindrical body having both sides which are opened and a supporting part having a broad supporting area by allowing an upper surface of the body to be projected to the outside, thereby conducting the back plate and allowing the supporting part to support a PCB in a curling process; and a PCB which is mounted with circuit parts and is supported by the conductive base, thereby forming a back chamber therein together with the back plate, whereby the conductive base supports the PCB when curling an opened end of the case after inserting parts into the case. Brief Description of the Drawings

[10] The above and other objects and features of the invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[11] Fig. 1 is a sectional side view of a conventional condenser microphone assembly.

[12] Fig. 2 is a view showing to explain a spirit of the present invention;

[13] Fig. 3 is a sectional view showing a conductive base of a condenser microphone according to the present invention; and

[14] Fig. 4 is a sectional side view of a condenser microphone assembly according to the present invention. Best Mode for Carrying Out the Invention

[15] Hereinafter, preferred embodiments of the present invention will be explained in

detail with reference to the appended drawings.

[16] Fig. 2 is a view showing to explain a spirit of the present invention. A first enlarged drawing within a circle conceptually shows that a PCB 18 within a conventional condenser microphone is bent upon a curling process. Then, a second enlarged drawing within a circle conceptually shows that a PCB 114 is prevented from being bent by allowing a conductive base 112 having a shape of "D" to support the PCB 114 upon a curling process.

[17] Referring to Fig. 2, since a conventional conductive base 16 which supports the

PCB 18, as shown in the first enlarged drawing, has a linear upper end portion, an ending area for supporting the PCB 18 is narrow, whereby an end of the PCB 18 is bent inward in the curling process of folding an opened end 10b of the case and bending toward the PCB 18, and, thus, a sound quality is deteriorated due to a change of an acoustic path. However, according to the present invention, as shown in the second enlarged drawing, an upper supporting surface which contacts a surface of a PCB 114 is projected outside in a shape of "D", thereby broadly supporting the surface of PCB 114 upon curling an opened end 102b of the case, and, thus, the PCB 114 is able to be prevented from being bent.

[18] Fig. 3 is a sectional view showing a conductive base of a condenser microphone according to the present invention.

[19] The conductive base 112, as shown in Fig. 3, includes a body 112a which has a cylindrical shape having both sides which is opened, and a supporting part 112b which forms a broad flat area for supporting the PCB 114 by projecting an upper surface of the body 112a outward, thereby having a left sectional shape of "D" and a right sectional shape of "D". As such, the conductive base 112 allows the supporting part 112b for supporting the PCB 114 to be broadly expanded compared with the body 112a, thereby enlarging a supporting area and thus preventing the PCB 114 from being bent.

[20] Fig. 4 is a sectional side view of a condenser microphone assembly according to the present invention.

[21] A condenser microphone which is assembled using the inventive conductive base

112, as shown in Fig. 4, has a structure for inserting a vibration plate 104 which serves as a movable electrode by forming a polar ring 104a and a vibration membrane 104b, a spacer 106 for forming a gap, an insulating base 110 for performing insulating function against the case 102, a back plate 108 which is formed with a sound hole 108a and serves as a fixing electrode, and a conductive base 112 for providing a conductive function to the back plate 108 into a cylindrical case 102 which has an opening side and is formed with an sound hole 102 on a bottom side thereof, and then curling the opened end 102b of the case after inserting the PCB 114 which is mounted with a

JFET into the case 102.

[22] According to the condenser microphone of the present invention, if air is flown through the sound hole 102a of the case 102 into the microphone by an external sound wave, the vibration membrane 104b is vibrated by a sound pressure and then the air is flown through through-holes 108a of the back plate 108 into a back chamber which is formed between the PCB 114 and the back plate 108. At this time, if the vibration membrane 104b is vibrated by the sound pressure which is applied through the sound hole 102a, a gap between the vibration membrane 104b and the back plate 108 is changed. Then, if the gap is changed by the sound pressure, electrostatic capacity which is formed by the vibration plate 104b and the back plate 108 is changed, thereby obtaining a change of an electrical signal (that is, voltage) according to the sound wave. Then, the electrical signal is transferred to an IC, for example, JFET and so on which are mounted on the PCB 114, and then is amplified. Finally, the amplified signal is transferred through a connecting terminal (not shown) to the outside. Industrial Applicability

[23] From the foregoing, according to the condenser microphone of the present invention, there is provided the microphone for allowing the conductive base having the wide supporting surface to broadly support the portions of the PCB to be curled in the process for curling the opened end of the case, thereby preventing the PCB from being bent or preventing parts to be deformed due to a stress on the parts and thus providing a superior acoustic characteristic.

[24] While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the present invention is not limited to the disclosed embodiment, but, on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

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