WO2006028331A1

WO2006028331A1 - Ultra-small sized condenser microphone case and ultra-small sized condenser microphone assembly

Info

Publication number: WO2006028331A1
Application number: PCT/KR2005/002738
Authority: WO
Inventors: Gap-Ryul Jung; Gi Il Kim; Eun Soo Ko
Original assignee: Cosmosound Technology Co., Ltd.
Priority date: 2004-09-07
Filing date: 2005-08-19
Publication date: 2006-03-16
Also published as: KR100627795B1; KR20060022517A

Abstract

Disclosed are an ultra small-sized condenser microphone case defining an inner space consisting of a side wall and a bottom part, and an ultra small-sized condenser microphone assembly using the case. According to the invention, an insulating layer is formed on a selected region of an inner surface of the side wall and an inner surface of the bottom part is selectively exposed with not being covered by the insulating layer.

Description

ULTRA-SMALLSIZEDCONDENSERMICROPHONECASE ANDULTRA-SMALLSIZEDCONDENSERMICROPHONE

ASSEMBLY

Technical Field

[1] The invention relates to an ultra-small sized condenser microphone case and an ultra-small sized condenser microphone assembly, and more particularly to an ultra- small sized condenser microphone case and an ultra-small sized condenser microphone assembly capable of remarkably improving mass productivity and quality of a product to be finally completed, through a structural improvement of an insulating layer capable of substituting an insulating base ring.

Background Art

[2] In recent years, as technologies of information communication devices such as cellular phone, telephone and the like and sound wave devices such as AMP have been rapidly developed, it is also increased needs of customers for an improvement of com¬ munication quality of a microphone.

[3] As shown in Fig. 1, a condenser microphone assembly 10 according to the prior art comprises a cylindrical case 1 having a sound wave inlet Ia formed thereto, a diaphragm assembly 11, a spacer ring 4, a dielectric plate 5, a conductive base ring 6, a printed circuit board (PCB) 9 and an insulating base ring 7. The diaphragm assembly 11 consists of a polar ring 2 and a diaphragm 3. The PCB 11 is provided with an electronic circuit for an electrical signal processing, for example a transistor 8, a capacitor 8a and the like.

[4] As shown in Fig. 2, the conductive base ring 6 electrically connects the dielectric plate 5 and the PCB 9. When there occurs a current signal change as a gap between the diaphragm 3 of the diaphragm plate 11 and the dielectric plate 5 is varied, the conductive base ring delivers the corresponding current signal change to the electronic circuit of the PCB 9. The insulating base ring 7 covers edges of the conductive base ring 6 and the dielectric plate 5, so that it interrupts the conductive ring 6 and the dielectric plate 5 electrically connected to the PCB 9 to electrically come in contact with an inner wall of the case 1. In this case, the polar ring 2 having no electrical connection relation with the PCB 9 has a structure of being physically (electrically) in contact with the case 1 and thus maintains a stable electric circuit state.

[5] An example of the condenser microphone assembly according to the prior art is specifically disclosed in a Korean Patent Registration No. 349200.

[6] In the mean time, the diaphragm assembly 11 and the dielectric plate 5 correspond to plates, respectively, and positions thereof may be flexibly changed in the case according to the situation and necessity. In addition, in case of the example as shown in Figs. 1 and 2, a contact structure of the polar ring and the case is as such. In other words, when the positions of the dielectric plate and the diaphargm assembly are changed each other, an element having an electrical connection relation with the PCB is the polar ring and the dielectric plate contacts the case.

[7] With the condenser microphone assembly as described above, the insulating base ring covers the elements electrically connected to the PCB (for example, the conductive base ring and the dielectric plate, in case of the example shown in Figs. 1 and 2), so that it electrically isolates the elements from the inner wall of the case and thus maintains the electrical stability.

[8] However, when the insulating base ring of the prior art isolates the elements electrically connected to the PCB, such as the conductive base ring, the dielectric plate and the like, from the inner wall of the case, it causes problems that it inevitably occupies an internal space of the product and increases a defective proportion during the assembling process. Accordingly, particularly, like a microphone assembly mounted in a portable terminal and the like, the smaller a size thereof, the more needs of a structure capable of substituting the insulating base ring.

[9] A Korean Patent Publication No. 2002-87361 entitled with "Electric acoustic case whose inside is insulated" discloses an insulating layer capable of replacing an insulating base ring of the prior art.

[10] As shown in Fig. 3, the electric acoustic case comprises a case 21 having an acoustic hole 21a formed thereto, a film 25 positioned in the case 21, a spacer ring 23 for fixing the film 25, a film ring 24 serving as an electrode, an acoustic friction axis 22 having a porous material 28, an electric part printed section 26 and an electrode 29.

[11] Since an insulating Teflon layer 27 substituting an existing insulating base ring is coated in the case 21, the parts can be electrically insulated from the case 21.

[12] However, the above prior art has following disadvantages.

[13] Referring to Figs. 1 and 2 again, in the example of the prior microphone assembly, the polar ring 2 of the polar plates (corresponding to the spacer ring/film ring shown in Fig. 3), which is not contacted to the PCB, is physically (electrically) contacted to the case 1, thereby maintaining the stable electric circuit.

[14] However, if the polar ring 2 is not physically (electrically) contacted to the case 1 and thus the electric circuit becomes unstable, it may be caused serious problems that a performance (sensitivity) of a microphone assembly to be finally completed is con¬ siderably decreased or the assembly is not operated at all.

[15] Regarding this, in the case of using the prior insulating layer shown in Fig. 3, since the insulating Teflon layer 27 having a thickness is provided between the spacer ring/ film ring 23, 24 (corresponding to the polar ring shown in Figs. 1 and 2) and the case 21, the spacer ring/film ring 23, 24 cannot be inevitably contacted to the case 21 physically (electrically).

[16] Accordingly, since the prior art using the insulating layer has serious disadvantages and is very unstable, it is difficult to embody a normal microphone assembly through the prior art using the insulating layer.

Disclosure of Invention Technical Problem

[17] Accordingly, the invention has been made to solve the above problems. An object of the invention is to selectively position an insulating layer capable of substituting an insulating base ring to an inner wall of a case. At this time, the insulating layer is limitedly positioned to an inner surface of a bottom part of the case to induce a selective exposure of the inner surface of the case bottom part (entire exposure or partial exposure), thereby allowing a polar plate mounted in the case (diaphragm assembly or dielectric plate), e.g., a polar ring of the diaphragm assembly to be physically (electrically) contacted to a bottom surface of the case reliably, even under state that the insulating layer is positioned to the case inner wall. Further, due to the reliable physical (electrical) contact, the polar plate (e.g., polar ring of the diaphragm assembly) can maintain a stable electric circuit.

[18] Another object of the invention is to stably embody an insulating structure of the case inner wall and a physical (electrical) contact structure between the inner surface of the case bottom part and the polar plate (for example, polar ring of the diaphragm assembly) at the same time through the selective positioning of the insulating layer and thus to allow the insulating base ring to be omitted without additional problems, thereby further miniaturizing the microphone through the elimination of the insulating base ring and omitting an assembling process of the insulating base ring having much defective proportions to increase a productivity of the microphone. Technical Solution

[19] In order to accomplish the above objects, there is provided an ultra-small sized condenser microphone case defining a inner space consisting of a side wall and a bottom part, wherein an insulating layer is formed on a selected region of an inner surface of the side wall and an inner surface of the bottom part is selectively exposed with not being covered by the insulating layer.

[20] According to an embodiment of the invention, the insulating layer may be formed to cover the entire inner surface of the side wall.

[21] According to an embodiment of the invention, the insulating layer may be formed to partially cover the inner surface of the side wall. [22] According to an embodiment of the invention, only a selected region of the inner surface of the bottom part may be exposed with not being covered by the insulating layer and a remaining region thereof may be covered by the insulating layer.

[23] According to an embodiment of the invention, the insulating layer may be one of a fluorinated ethylene propylene (FEP) film, a polyethyleneterephthalate (PET) film, a polyphenylenesulfide (PPS) film and an insulating plated layer.

[24] According to another embodiment of the invention, there is provided an ultra-small sized condenser microphone case defining a inner space consisting of a side wall and a bottom part, wherein a diaphragm, a polar ring, a dielectric plate, a conductive base ring or phase delay device and a PCB are sequentially mounted in the inner space, an edge of the side wall is bent to the PCB to seal the diaphragm, the polar ring, the dielectric plate, the conductive base ring or phase delay device and the PCB mounted in the inner space, an insulating layer is formed on a selected region of an inner surface of the side wall so as to insulate the dielectric plate and the conductive base ring or the phase delay device from the inner surface of the side wall, and an inner surface of the bottom part is selectively exposed with not being covered by the insulating layer so that the polar ring is physically (electrically) contacted to the inner surface of the bottom part.

[25] According to an embodiment of the invention, when the edge of the side wall is bent to the PCB, an inner surface of the edge of the side wall may be not formed with the insulating layer so that it is physically (electrically) contacted to the PCB.

[26] According to an embodiment of the invention, the inner surface of the side wall of the case may be formed with the insulating layer on a region corresponding to the dielectric plate and the conductive base ring or phase delay device.

[27] According to an embodiment of the invention, only an inner surface of the bottom part to which the polar ring is contacted may be exposed with not being covered by the insulating layer.

[28] In order to accomplish the above objects, there is provided an ultra-small sized condenser microphone assembly comprising a case defining a inner space consisting of a side wall and a bottom part; a diaphragm mounted in the case and vibrating by a sound wave inputted in the case; a polar ring mounted in the case and fixing the diaphragm; a dielectric plate mounted in the case and maintaining a gap between the diaphragm and the dielectric plate; a conductive base ring mounted in the case and supporting the dielectric plate or a phase delay device mounted in the case, supporting the dielectric plate and reproducing only a sound wave of a predetermined direction inputted in the case while interrupting a sound wave of another direction; and a PCB mounted in the case and electrically contacting one of the conductive base ring and the phase delay device, wherein an insulating layer capable of electrically insulating the dielectric plate and the conductive base ring or phase delay device from the case is formed on a selected region of the inner surface of the side wall of the case, and an inner surface of the bottom part is exposed with not being covered by the insulating layer so that the polar ring is able to physically (electrically) come in contact with the case.

Advantageous Effects

[29] According to the invention, the insulating layer capable of substituting an insulating base ring is selectively positioned to the inner wall of the case. At this time, a selective exposure (entire exposure or selective exposure), which partially or entirely excludes the formation of the insulating layer on an inner surface of a sound wave inlet of the case, i.e., an inner surface of the bottom part of the case, is induced, so that the polar plate mounted in the case (for example, a polar ring of the diaphragm assembly) can be physically (electrically) contacted to the inner surface of the bottom part of the case reliably, even under state that the insulating layer is positioned in the case, and due to the physical (electrical) contact, an electric circuit state of the polar plate (e.g., polar ring of the diaphragm assembly) can be stabilized.

[30] Further, according to the invention, it is possible to stably embody an insulating structure of the case inner wall and a electrical contact structure between the polar plate (for example, polar ring of the diaphragm assembly) and the case at the same time, through the selective positioning of the insulating layer. Accordingly, a removal of the insulating base ring is accomplished without additional problems, so that a man¬ ufacturer can further miniaturize the microphone through the elimination of the insulating base ring and omit an assembling process of the insulating base ring having much defective proportions to increase a productivity of the microphone. Brief Description of the Drawings

[31] FIG. 1 is a schematic exploded perspective view of a condenser microphone assembly having an insulating base ring according to the prior art;

[32] FIG. 2 is a sectional view schematically showing a condenser microphone assembly having parts of FIG. 1 connected thereto;

[33] FIG. 3 is a sectional view schematically showing an example of an electric acoustic case whose inside is insulated according to the prior art;

[34] FIG. 4 is a perspective view schematically showing an ultra-small sized condenser microphone case according to a first embodiment of the invention;

[35] FIG. 5 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a first embodiment of the invention;

[36] FIG. 6 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a second embodiment of the invention; [37] FlG. 7 is a perspective view schematically showing an ultra-small sized condenser microphone case according to a third embodiment of the invention; [38] FlG. 8 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a third embodiment of the invention; [39] FlG. 9 is a perspective view schematically showing an ultra-small sized condenser microphone case according to a fourth embodiment of the invention; [40] FlG. 10 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a fourth embodiment of the invention; [41] FlG. 11 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a fifth embodiment of the invention; [42] FlG. 12 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a sixth embodiment of the invention; [43] FlG. 13 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a seventh embodiment of the invention; [44] FlG. 14 is a sectional view schematically showing an ultra-small sized condenser microphone case according to a eighth embodiment of the invention; [45] FlG. 15 is a schematic exploded perspective view of an ultra-small sized condenser microphone assembly according to an embodiment of the invention; [46] FlG. 16 is a sectional view schematically showing an ultra-small sized condenser microphone assembly having parts of FlG. 15 connected thereto; [47] FlG. 17 is a sectional view schematically showing an ultra-small sized condenser microphone assembly using the ultra-small sized condenser microphone case according to the fifth embodiment (refer to FlG. 11) of the invention; [48] FlG. 18 is a sectional view schematically showing an ultra-small sized condenser microphone assembly using the ultra-small sized condenser microphone case according to the sixth embodiment (refer to FlG. 12) of the invention; [49] FlG. 19 is a schematic exploded perspective view of an ultra-small sized condenser microphone assembly having a phase delay device according to an embodiment of the invention; [50] FlG. 20 is a sectional view schematically showing an ultra-small sized condenser microphone assembly having parts of FlG. 19 connected thereto; [51] FlG. 21 is a sectional view schematically showing an ultra-small sized condenser microphone assembly having a phase delay device and using the ultra-small sized condenser microphone case according to the fifth embodiment (refer to FIGS. 11 and

17) of the invention; and [52] FlG. 22 is a sectional view schematically showing an ultra-small sized condenser microphone assembly having a phase delay device and using the ultra-small sized condenser microphone case according to the sixth embodiment (refer to FIGS. 12 and 18) of the invention.

Best Mode for Carrying Out the Invention

[53] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following descriptions of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

[54] As shown in Figs. 4 and 5, an ultra-small sized condenser microphone case 101 according to an embodiment of the invention comprises a bottom part 101c having a sound wave inlet 101a and a side wall 101d bent from both sides of the bottom part 101c. The bottom part 101c and the side wall 101d naturally define a cylindrical inner space S, for example.

[55] A variety of condenser microphone parts for forming a final condenser microphone assembly are sequentially stacked in the inner space S of the case 101 according to their inherent characteristics. At this time, it is needless to say that kinds and po¬ sitioning of the condenser microphone parts may be variously changed according to the situation and necessity.

[56] According to a first embodiment of the invention, as shown in Figs. 4 and 5, an insulating layer 200 capable of substituting an insulating base ring is positioned only on an inner surface of the side wall 101d of the case 101. In this case, as the insulating layer 200, a fluorinated ethylenepropylene (FEP) film, a polyethylenterephthalate (PET) film, a polyphenylenesulfide (PPS) film or an insulating plated layer may be flexibly selected according to the situation and necessity.

[57] When the insulating layer 200 is positioned, the condenser microphone parts positioned in the case 101 can naturally avoid an electrical contact with the case, without an insulating base ring which is the prior insualting part, since the insulating layer 200 performs a function thereof. Further, since the insulating base ring occupying a relatively large space in the entire structure is omitted, the microphone can be further miniaturized. In addition, an assembling process of the insulating base ring having much defective proportions is also omitted, so that a productivity of the condenser microphone can be also remarkably increased.

[58] In the mean time, the insulating layer 200 is formed only on the inner surface of the side wall 101d of the case 101 and is not formed on an inner surface of the bottom part 101c of the case 101, so that the entire inner surface of the bottom part 101c is naturally exposed.

[59] Like this, under state that the insulating layer 200 is formed only on the inner surface of the side wall 101d of the case 101 and is not formed on the inner surface of the bottom part 101c of the case 101 and thus the inner surface of the bottom part 101c is exposed, a polar plate (for example, diaphragm assembly or dielectric plate) can ex¬ tensively contact the inner surface of the bottom part 101c of the case 101 and thus form a sufficient physical (electrical) contact surface with the case 101.

[60] Further, when the polar plate naturally forms a physical (electrical) contact surface with the inner surface of the bottom part 101c of the case 101, the polar plate (diaphragm assembly or dielectric plate) can normally maintain a stable circuit state.

[61] Contrary to the prior art that the insulating layer is formed on the entire inner surface of the case thus the polar plate (diaphragm assembly or dielectric plate) is not inevitably contacted to the case physically (electrically) and a stable circuit state cannot be maintained, thereby causing serious problems, according to the invention, the insulating layer is selectively positioned on the inner surface of the case, so that it is possible to stably embody an insulating structure of the case side wall and a physical (electrical) contact structure between the polar plate (diaphragm assembly or dielectric plate) and the case 101 at the same time.

[62] In the mean time, an edge 101b of the case 101 is bent toward an inside thereof, thereby forming a structure of sealing the condenser microphone parts positioned in the case 101. At this time, the edge forms a structure electrically connected to a specific part of the condenser microphone, e.g., a negative (-) circuit portion of a PCB. Under such situation, if the insulating layer 200 is formed to the edge 101b of the case as the side wall 101d, there may occur an unexpected problem that the edge 101b cannot be electrically connected to the negative (-) circuit portion of the PCB due to the insulating layer 200.

[63] Accordingly, according to a second embodiment of the invention, in considering of the structural (electrical) characteristic of the edge 101b, as shown in Fig. 6, an inner surface of the edge 101b is not formed with the insulating layer 200 and thus se¬ lectively exposed, so that the edge 101b of the case 101 can normally form an electrical connection relationship required for the edge, irregardless of the formation of the insulating layer 200.

[64] Further, based on the technical spirit of the invention as described above, the insulating layer 200 can be variously modified accoriding to the situation.

[65] For example, as shown in Figs. 7 and 8, according to a third embodiment of the invention, the insulating layer 200 is selectively formed only on a portion of the side wall 101d corresponding to parts that are required to be electrically insulated among the condenser microphone parts, with a marginal surface YSl being remained.

[66] In this case, contrary to the first and second embodiments, there may occur a situation that some parts are inevitably contacted to the side wall 101d of the case 101 via the marginal surface YSl. However, since the parts do not cause particular electrical problems even though they are contacted to the side wall 101d of the case 101, it is possible to normally maintain an insulating environment of the side wall 101d of the case 101 in the third embodiment.

[67] As shown in Figs. 9 and 10, in a fourth embodiment of the invention, the insulating layer 200 is remained on the inner surface of the bottom part 101c of the case 101 according to the situation, except for a region in which the polar plate (diaphragm assembly or dielectric plate) is formed (i.e., only a marginal surface YS2 cor¬ responding to the polar plate is selectively exposed).

[68] Needless to say, also in the fourth embodiment, since it is possible to normally form a sufficient physical-electrical contact surface with the case 101 via the marginal surface YS2, an electric circuit state of the polar plate can be stably maintained.

[69] As shown in Fig. 11, according to a fifth embodiment of the invention, the insulating layer 200 may cover only a portion of the inner surface of the side wall 101d of the case 101 with the edge 101b and the marginal surface YSl being exposed.

[70] As shown in Fig. 12, according to a sixth embodiment of the invention, the insulating layer 200 may selectively cover a portion of the inner surface of the side wall 101d of the case 101 with the edge 101b being exposed and at the same time se¬ lectively cover only a portion of the inner surface of the bottom part 101c with the marginal surface YS2 being exposed.

[71] As shown in Fig. 13, according to a seventh embodiment of the invention, the insulating layer 200 may selectively cover a portion of the inner surface of the side wall 101d of the case 101 with the marginal surface YSl being exposed and at the same time selectively cover only a portion of the inner surface of the bottom part 101c with the marginal surface YS2 being exposed.

[72] As shown in Fig. 14, according to a eighth embodiment of the invention, the insulating layer 200 may selectively cover a portion of the inner surface of the side wall 101d of the case 101 with the edge 101b and the marginal surface YSl being exposed and at the same time selectively cover only a portion of the inner surface of the bottom part 101c with the marginal surface YS2 being exposed.

[73] Hereinafter, an ultra-small sized condenser microphone assembly adopting the condenser microphone case according to each of the embodiments will be specifically described.

[74] As shown in Figs. 15 and 16, an ultra-small sized condenser microphone assembly

30 according to an embodiment of the invention comprises a case 31 having a sound wave inlet 31a and a cylindrical inner space therein, a diaphragm assembly 37, a spacer ring 34, a dielectric plate 35, a conductive base ring 36 and a PCB 39 that are se¬ quentially mounted in the case 31. Needless to say, in the above structure, it is possible to flexibly change positions of the diaphragm assembly or dielectric plate constituting a polar plate each other according to the situation and necessity.

[75] The case 31 consists of a side wall 3 Id and a bottom part 31c, and the diaphragm assembly 37 consists of a diaphragm 33 and a polar ring 32 surrounding an edge of the diaphragm 33 and fixing-supporting the diaphragm 33. The PCB 39 is provided with an electronic circuit for an electrical signal processing, for example, a transistor 38, a capacitor 38a and the like. In the mean time, the edge 31b of the case 31 is bent to the PCB 39 to stably seal the diaphragm 33, the polar ring 32, the dielectric plate 35, the conductive base ring 36 and the PCB 39 mounted in the case. The conductive base ring 36 serves to electrically connect the dielectric plate 35 and the PCB 39.

[76] In the ultra-small sized microphone assembly of the invention, as described above, an inner surface of the side wall 3 Id of the case 31 is formed with an insulating layer 41 for electrically insulating the dielectric plate 35 and the conductive base ring 36 from the case 31, and an inner surface of the bottom part 31c of the case 31 is not formed with the insulating layer. As described above, the FET film PET film, PPS film or insulating plated layer may be used as the insulating layer 41.

[77] According to the ultra-small sized microphone assembly of the invention, the dielectric plate 35 and the conductive base ring 36 can naturally avoid an electrical contact with the case 31 without an insulating base ring which is the prior insulating part, since the insulating layer 200 performs a function thereof. Thereby, the assembly 30 to be finally completed can avoid the problem that potentials of the dielectric plate and the conductive base ring are dropped to that of the case due to an electrical contact of the dielectric plate and the conductive base ring with the case, without the insulating base ring. Further, since the insulating base ring occupying a relatively large space in the entire assembly structure is omitted, the microphone can be further miniaturized. In addition, an assembling process of the insulating base ring having much defective proportions is also omitted, so that a productivity of the condenser microphone can be also remarkably increased, as described above.

[78] In particular, according to the invention, since the insulating layer 41 is formed only on the selected region of the side wall 3 Id of the case 31 and is not formed on the bottom part 31c of the case 31 and thus the inner surface of the bottom part 31c is naturally exposed, a surface of a polar plate (for example, polar ring of the diaphragm assembly or dielectric plate) facing to the case 31 can extensively contact the inner surface of the bottom part 3 Ic of the case 31. As a result of that, the polar plate can form a sufficient physical-electrical contact surface with the case 31 and thus normally maintain a stable circuit state.

[79] Like this, in the ultra-small sized microphone assembly according to the invention, the insulating layer 41 is selectively positioned, so that an insulating structure of the side wall 3 Id of the case 31 and a physical (electrical) contact structure between the polar ring 32 and the case can be stably embodied at the same time.

[80] A method of mounting the above constituting elements in the inner space of the case 31 to manufacture an ultra-small sized microphone assembly is as follows.

[81] First, the diaphragm assembly 37, i.e., the polar ring 32 having fixed the diaphragm

33 is mounted in the inner space of the case 31 having the insulating layer 41 se¬ lectively applied only on the side wall 3 Id except the bottom surface 31c.

[82] Subsequently, the spacer ring 34 is put on the polar ring 32 and then the disc-shaped dielectric plate 35 is put on a periphery of the spacer ring 34. At this time, the dielectric plate 35 can maintain a gap between the diaphragm 33 and the dielectric plate via the spacer ring 34.

[83] Like this, when all the diaphragm assembly 37, the spacer ring 34, the dielectric plate 35 and the like are mounted in the case 31, the conductive base ring 36 is put on the dielectric plate 35, the PCB 39 is put on a periphery of the conductive base ring 36 and then the edge 3 Ib of the case 31 is bent to the PCB 39 to seal the inner space of the case 31, thereby completing a final ultra-small sized condenser microphone assembly 30 of the invention.

[84] In the completed ultra-small sized condenser microphone assembly 30 of the invention, since the inner surface of the bottom part 31c of the case 31 is naturally exposed with not being covered by the insulating layer 41, the polar ring can form an extensive physical-electrical contact surface CS with the case 31, under state that the edge 31b of the case 31 is bent to seal the inner space in the case 31. Thereby, the completed ultra-small sized condenser microphone assembly 30 can normally maintain an acoustic quality of a predetermined level or more.

[85] In addition, as described above, the edge 31b of the case 31 is bent to the PCB 39 to form a structure of electrically contacting a particular circuit portion of the PCB 39, e.g., a negative (-) circuit portion. In this case, since the edge 31b cannot be electrically contacted to the negative (-) circuit portion due to the insulating layer 41, an inner surface of the edge 31b is not formed with the insulating layer 41 so that the edge 31b of the case 31 can normally an electrical connection relationship required for the edge, irregardless of the formation of the insulating layer 41.

[86] Further, as described above, according to the invention, the insulating layer may be variously modified.

[87] As shown in Fig. 17 (refer to Fig. 11 according to the fifth embodiment of the invention), the insulating layer 41 may be selectively formed only on the side wall 3 Id corresponding to the dielectric plate 35 and the conductive base ring 36.

[88] Needless to say, in this case, although there may occur that the diaphragm 32, the spacer ring 33, the PCB 39 and the like may contact the side wall 31d of the case 31, since the diaphragm 32, the spacer ring 33, the PCB 39 and the like does not generally cause particular electrical problems even though they comes in contact with the side wall 3 Id of the case 31, it is possible to normally maintain an insulating environment of the side wall 3 Id of the case 31. Also in this case, since the insulating layer 41 is not formed on the bottom part 31c of the case 31, the polar ring 32 can normally maintain a sufficient physical-electrical contact surface CS with the case 31.

[89] As shown in Fig. 18 (refer to Fig. 12 according to the sixth embodiment of the invention), it is possible to leave the insulating layer 41 on the inner surface of the remaining bottom part 31c of the case 31, except a region in which the polar ring 32 is formed (i.e., only the bottom surface corresponding to the polar ring can be selectively exposed). Also in this case, since the polar ring 32 can normally form a sufficient physical-electrical contact surface CS with the case 31, it can stably maintain an electric circuit state.

[90] In the mean time, the selective positioning of the insulating layer 41 constituting the technical spirit of the invention can be effectively applied to the invention as disclosed in a Korean Patent Publication No. 2003-95776 entitled with "Uni-directional ultra- small sized condenser microphone assembly and method of manufacturing the same, and unitary phase delay device assembled to the same".

[91] As shown in Figs. 19 and 20, an ultra-small sized condenser microphone assembly

60 having a phase delay device according to an embodiment of the invention comprises a case 61 having a sound wave inlet 61a and a cylindrical inner space therein, a diaphragm assembly 67, a spacer ring 64, a dielectric plate 65, a phase delay device 66 and a PCB 69 having a series of sound wave inlets 69a formed therein, which are sequentially mounted in the inner space of the case 61. Of course, with the structure, it is possible to flexibly change positions of the diaphragm assembly or dielectric plate constituting polar plates each other according to the situation. Detailed structures and manufacturing processes of the case 61, a diaphragm 63 and a polar ring 62 of the diaphragm assembly 67, the spacer ring 64, the dielectric plate 65 and the PCB 69 provided with a transistor 65 and a capacitor 68a are same as the above de¬ scriptions.

[92] In Figs. 19 and 20, in particular, the phase delay device 66 is provided. The phase delay device 66 forms a cylindrical shape having a closed side and serves to support the dielectric plate 65, to reproduce only a sound wave of a predetermined direction inputted through the case 61 and to interrupt a sound wave of another direction. In manufacturing the microphone assembly having the phase delay device 66, under state that all the diaphragm assembly 67, the spacer ring 64, the dielectric plate 65 and the like are mounted in the case 61, the phase delay device 66 is positioned on the dielectric plate 65, the PCB 69 is put on the closed surface of the phase delay device 66, and the edge 61b of the case 61 is bent to the PCB 69 to seal the inner space of the case 61.

[93] Also in the ultra-small sized microphone assembly having the phase delay device

66, an inner surface of the case 61 is formed with an insulating layer 71, preferably FEP film, PET film, PPS film or insulating plated layer for electrically insulating the dielectric plate 65 and the phase delay device 66 from the case 61. In addition, the insulating layer 71 is not formed on an inner surface of the bottom part 61c of the case 61, so that the inner surface of the bottom part 61c is naturally exposed.

[94] According to the above structure, as described above, the polar ring 62 can form a sufficient physical-electrical contact surface CS with the case 61, so that a stable electric circuit state can be normally maintained. In addition, the dielectric plate 65 and the phase delay device 66 can be electrically insulated from the case 61 without the prior insulating base ring, since the insulating layer 71 performs a function thereof. Thereby, the assembly to be finally completed can avoid the problem that potentials of the dielectric plate and the phase delay device are dropped to that of the case due to an electrical contact of the dielectric plate and the phase delay device with the case, without the insulating base ring. Further, the microphone can be further miniaturized since the insulating base ring is excluded. In addition, an assembling process is simplified, so that a defective proportion is decreased and a productivity is increased.

[95] In Fig. 21, it is shown that the insulating layer 71 is selectively formed only on the side wall corresponding to the dielectric plate 65 and the phase delay device 66. As the case of Fig. 17, in the example shown of Fig. 21, the insulating environment of the side wall 61d of the case 61 is also normally maintained.

[96] In Fig. 22, it is shown that the insulating layer 71 is left on the inner surface of the remaining bottom part 61c of the case 61, except a region in which the polar ring 62 is formed (i.e., only the inner surface of the bottom part corresponding to the polar ring is selectively exposed). Also in this case, as the case of Fig. 18, since the polar ring 62 can normally form a sufficient physical-electrical contact surface CS with the case 61, it can stably maintain an electric circuit state. Industrial Applicability

[97] According to the invention, there is provided an ultra-small sized condenser microphone case and an ultra-small sized condenser microphone assembly capable of remarkably improving mass-productivity and quality of a product to be finally completed, through a structural improvement of the insulating layer capable of sub¬ stituting the insulating base ring. The invention exhibits generally useful effects in a variety of information communication devices and sound wave devices requiring a microphone.

Claims

[1] An ultra-small sized condenser microphone case defining a inner space consisting of a side wall and a bottom part, wherein an insulating layer is formed on a selected region of an inner surface of the side wall and an inner surface of the bottom part is selectively exposed with not being covered by the insulating layer.

[2] The microphone case according to claim 1, wherein the insulating layer is formed to cover the entire inner surface of the side wall.

[3] The microphone case according to claim 1, wherein the insulating layer is formed to partially cover the inner surface of the side wall.

[4] The microphone case according to claim 1, wherein only a selected region of the inner surface of the bottom part is exposed with not being covered by the insulating layer and a remaining region thereof is covered by the insulating layer.

[5] The microphone case according to claim 1, wherein the insulating layer is one of a fluorinated ethylene propylene (FEP) film, a poly ethylene terephthalate (PET) film, a poly phenylene sulfide (PPS) film and an insulating plated layer.

[6] An ultra-small sized condenser microphone case defining a inner space consisting of a side wall and a bottom part, wherein a diaphragm, a polar ring, a dielectric plate, a conductive base ring or phase delay device and a PCB are sequentially mounted in the inner space, an edge of the side wall is bent to the PCB to seal the diaphragm, the polar ring, the dielectric plate, the conductive base ring or phase delay device and the PCB mounted in the inner space, wherein an insulating layer is formed on a selected region of an inner surface of the side wall so as to insulate the dielectric plate and the conductive base ring or the phase delay device from the inner surface of the side wall, and wherein an inner surface of the bottom part is selectively exposed with not being covered by the insulating layer so that the polar ring is physically (electrically) contacted to the inner surface of the bottom part.

[7] The microphone case according to claim 6, wherein when the edge of the side wall is bent to the PCB, an inner surface of the edge of the side wall is not formed with the insulating layer so that it is physically (electrically) contacted to the PCB.

[8] The microphone case according to claim 6, wherein the inner surface of the side wall of the case is formed with the insulating layer on a region corresponding to the dielectric plate and the conductive base ring or phase delay device.

[9] The microphone case according to claim 6, wherein only an inner surface of the bottom part to which the polar ring is contacted is exposed with not being covered by the insulating layer. [10] An ultra-small sized condenser microphone assembly comprising: a case defining a inner space consisting of a side wall and a bottom part; a diaphragm mounted in the case and vibrating by a sound wave inputted in the case; a polar ring mounted in the case and fixing the diaphragm; a dielectric plate mounted in the case and maintaining a gap between the diaphragm and the dielectric plate; a conductive base ring mounted in the case and supporting the dielectric plate or a phase delay device mounted in the case, supporting the dielectric plate and re¬ producing only a sound wave of a predetermined direction inputted in the case while interrupting a sound wave of another direction; and a PCB mounted in the case and electrically contacting one of the cnductive base ring and the phase delay device, wherein an insulating layer capable of electrically insulating the dielectric plate and the conductive base ring or phase delay device from the case is formed on a selected region of the inner surface of the side wall of the case, and wherein an inner surface of the bottom part is exposed with not being covered by the insulating layer so that the polar ring is able to physically (electrically) come in contact with the case.