JP4995692B2 - Unidirectional condenser microphone unit - Google Patents

Description

  The present invention relates to a unidirectional condenser microphone unit capable of providing a function equivalent to that of the rear acoustic terminal hole without providing the rear acoustic terminal hole on the printed circuit board.

Usually, the unidirectional condenser microphone unit is formed so that a sound wave from a specific sound source can be taken not only from the front of the diaphragm but also from a rear sound path formed behind. In addition, an acoustic resistance material is disposed in the rear sound passage to adjust the sound pressure and volume velocity of the sound wave. In this case, as shown in Patent Document 1 below, the sound wave from the rear passes through the rear acoustic terminal hole provided on the printed circuit board that seals the opening surface of the unit case when it is caulked. Is generally introduced. Further, as the acoustic resistance material, in addition to a nonwoven fabric or mesh having a sheet shape, a sponge having a certain thickness is generally used.
JP 2006-74149 A

  FIG. 3 is an explanatory view showing a conventional example of a unidirectional condenser microphone unit different from the above-mentioned Patent Document 1, in which (a) is a longitudinal sectional view and (b) is shown in (a). Plan views of printed circuit boards are shown.

  According to the figure, the unidirectional condenser microphone unit includes a unit case 1 having a front acoustic terminal hole 1a on one side and an opening 1b on the other side and having a bottomed cylindrical shape, and a printed circuit board 9. And at least a built-in unit 2 composed of a plurality of members arranged at predetermined positions in the unit case 1.

  In this case, the built-in unit 2 includes a diaphragm unit 3 in which a diaphragm 3b is stretched inside a support ring 3a facing the front acoustic terminal hole 1a, and a diaphragm 3b via a spacer 4. The back electrode plate 5 that is oppositely disposed, the insulating sleeve 6 that is disposed between the peripheral end surface 5a of the back electrode plate 5 and the inner peripheral surface of the unit case 1, and the vibration plate 3b are not opposed to each other. The air chamber cup 7 arranged to secure the air chamber A on the back side of the air chamber, the conductive sleeve 8 arranged in contact with and supported on the back side of the air chamber cup 7, and the impedance converter 9 a are connected to the conductive sleeve 6. And a printed circuit board 9 that is mounted on the side surface and sealed in the opening 1 b of the unit case 1.

  The built-in unit 2 is generated inside the unit case 1 after the constituent members are arranged in a predetermined procedure and then crimped with the opening 1b facing inward to press the printed circuit board 9 side. It is stored and held stably under pressure.

  In this case, the printed circuit board 9 is caulked and fixed by the caulking portion 1 c and sealed on the opening 1 b side of the unit case 1. Note that an input side pattern layer 9c is formed on the surface of the printed circuit board 9 on which the impedance converter 9a is mounted, as shown in FIG. Yes.

  In addition, the unidirectional condenser microphone unit shown in FIG. 3 is provided on the back electrode plate 5 by introducing sound waves that enter through the rear acoustic terminal holes 9 b provided on the printed circuit board 9 into the air chamber A. Unidirectionality is obtained by providing a structure for reaching the back surface of the diaphragm 3b through the through hole 5b.

  Incidentally, in the unidirectional microphone unit shown in FIG. 3, a printed circuit board 9 having a plurality of rear acoustic terminal holes 9b is used as a constituent member. For this reason, external electrical noise that is electrostatically coupled to the fixed pole connected to the impedance converter 9a enters the unit case 1 from the rear acoustic terminal hole 9b, and generates hum noise. In addition, there is a problem in that an unnecessary object such as a solder ball enters the unit case 1 through the rear acoustic terminal hole 9a. Naturally, as a countermeasure against these, although it is effective to reduce the hole size of the rear acoustic terminal hole 9b itself, there is a problem that the directional frequency response is deteriorated.

  Further, in the case of the unidirectional microphone unit shown in FIG. 3, there is an acoustic mass such as the air chamber A secured by the air chamber cup 7, and as a result, parasitic resonance is generated and the directional frequency response is deteriorated. There was also a problem of end.

  In view of the above-described problems of the prior art, the present invention provides hum noise and parasitic by providing a sound path that can exhibit the same function as the rear acoustic terminal hole without providing the rear acoustic terminal hole on the printed circuit board. In addition to stabilizing the directional frequency response by avoiding the occurrence of resonance, an object of the present invention is to provide a unidirectional condenser microphone unit that prevents unwanted objects such as solder balls from entering the unit case.

  The present invention has been made to achieve the above object, and has a unit case having a bottomed cylindrical shape having a front acoustic terminal hole and a sealing side surface when the unit case side is caulked. The side surface has a plurality of ground side pattern layers extending radially from the vicinity of the center to the periphery, and the other side surface is located in the vicinity of the substrate leaving surface from the vicinity of the center to the periphery. Including a printed circuit board provided with a plurality of input side pattern layers each extending radially and a conductive sleeve in conductive contact with the input side pattern layer side of the printed circuit board. And at least a predetermined built-in unit, and when the printed circuit board with a plain washer interposed at the peripheral edge of the one side surface is caulked and sealed, it is placed on a portion other than the plain washer and the ground side pattern layer. The formed first gap portion on one side surface and the second gap portion on the other side surface formed between the conductive sleeve and the base material exposed surface are formed in a peripheral edge portion of the printed circuit board. The most important feature is that a function as a rear acoustic terminal is imparted to a sound path composed of a thin air layer communicated through one or more cutouts.

  In this case, the acoustic resistance generated by the sound path can be adjusted depending on the size of the inner diameter of the plain washer and the thickness of the ground side conductor pattern layer and the input side pattern layer. .

  According to the first aspect of the invention, from the printed circuit board side, the sound wave can be taken into the unit case under the acoustic resistance generated by the sound path formed of a thin air layer formed in place of the rear acoustic terminal hole. Therefore, it is possible to effectively prevent the occurrence of hum noise by preventing the intrusion of external electrical noise, and it is also possible to prevent an unnecessary object such as a solder ball from entering the unit case.

  In addition, since there is no air chamber or acoustic mass that generates parasitic resonance in the unit case, it is possible to obtain good directional frequency characteristics.

  According to the invention of claim 2, the adjustment of the acoustic resistance generated by the sound path is performed by changing the inner diameter of the plain washer or changing the layer thickness of the ground side conductor pattern layer and the input side pattern layer. Therefore, it can be finely adjusted to obtain a preferable acoustic resistance value.

  FIG. 1 is an explanatory view of an example of the present invention, in which (a) shows a longitudinal sectional view and (b) shows a bottom view corresponding to (a). FIG. 2 is an explanatory view showing the positional relationship between a notch portion and a print pattern in an example of a printed circuit board constituting the present invention, and (a) of FIG. As shown in b), one side surface serving as a sealing surface is shown, and FIG.

  According to these drawings, a unidirectional microphone unit (hereinafter abbreviated as “microphone unit”) 11 includes a bottomed cylindrical unit case 12 and a built-in unit 22 accommodated in the unit case 12. It consists of

  Among these, the unit case 12 formed using a conductive metal such as aluminum has a front acoustic terminal hole 13a in the bottom surface portion 13, and curls the open end portion of the opening portion 14 inward. A caulking portion 15 as shown in 1 (a) can be formed.

  On the other hand, the built-in unit 22 is opposed to the diaphragm unit 23 formed by extending the diaphragm 23b on the inner side of the support ring 23a facing the front acoustic terminal hole 13a, and the diaphragm 23b via the spacer 24. The back electrode plate 25 disposed, the insulating sleeve 26 disposed between the peripheral end surface 25 a of the back electrode plate 25 and the inner peripheral surface 16 of the unit case 11, and the conductive material disposed inside the insulating sleeve 26. A sleeve 27, a printed circuit board 33 disposed in the unit case 12 with the opposing peripheral edge abuttingly supported by the insulating sleeve 26, and the printed circuit board 33 and the caulking portion 15 are interposed. And a flat washer 28 made of a conductive material.

  Of these, the printed circuit board 33 does not include a rear acoustic terminal hole, and five cutout portions 34 are formed on the peripheral edge 33a side so as to be bent at equal intervals.

  Further, as shown in FIG. 2 (a), the side surface 35, which becomes the sealing surface when the printed circuit board 33 is caulked on the unit case 12 side, has a peripheral edge 33a from an annular pattern layer 36 provided near the center thereof. Five relatively wide ground side pattern layers 37 extending radially are formed.

  Further, on the other side surface 45 of the printed circuit board 33, an annular pattern layer 46 is provided in the vicinity of the center surrounding the impedance converter 45a, leaving a base material exposed surface 49 from the annular pattern layer 46 to the peripheral edge 48 thereof. Five relatively narrow input side pattern layers 47 extending radially in the vicinity thereof are formed, and each of the input side pattern layers 47 is formed on the side of the conductive sleeve 27 constituting the built-in unit 22. Conductive contact will be made.

  For this reason, when the printed circuit board 33 is caulked and sealed, the flat washer 28 interposed in the peripheral portion 38 of the one side surface 35 and the ground side pattern layer 37 are brought into conductive contact with each other. As a result, the thickness of the ground side pattern layer 37 is increased. The first gap portion 39 is formed in the peripheral edge portion 38 without the ground side pattern layer 37.

  Further, when the printed circuit board 33 is caulked and sealed, the input side pattern layer 47 on the other side surface 45 and the conductive sleeve 27 are in conductive contact with each other, but an input is made between the peripheral portion 48 and the substrate exposed surface 49. The second gap 50 corresponding to the thickness of the side pattern layer 47 is formed.

  Moreover, since the printed circuit board 33 includes the notch 34 on the peripheral edge 33a side, the first gap 39 and the second gap 50 can be communicated with each other via the notch 34. That is, as a result of the first gap portion 39 and the second gap portion 50 being communicated with each other via the notch portion 34, a sound path 61 composed of a thin air layer can be secured, and the rear acoustic terminal is connected to the sound path 61. As a result, the function can be demonstrated.

  Next, the operation and effect of the present invention having the above-described configuration will be described based on the example shown in FIGS. 1 and 2. The built-in unit 22 is accommodated in the unit case 12 according to a predetermined procedure. The printed circuit board 33 accommodated last is disposed so as to seal the opening 14 side of the unit case 12, and the flat washer 28 is placed on the peripheral edge 38 on the one side surface 35 side, and the opening is opened on the flat washer 28. The caulking part 15 is formed by caulking with the part 14 side inward.

  When the caulking portion 15 is formed by caulking the opening portion 14 side of the unit case 12 in this way, the printed circuit board 33 is pressed inward via the plain washer 28, as shown in FIG. In addition, other built-in units 22 other than the flat washer 28 and the printed circuit board 33 are also stably housed and held in the unit case 11 under the internal pressure generated at that time.

  In this case, the printed circuit board 33 includes notches 34 on the peripheral edge 33a side, and also includes ground side pattern layers 37 arranged radially so as to reach the peripheral edge 33a on one side surface 35 which is the sealing surface. And the input side pattern layer 47 arranged radially so as to leave the substrate exposed surface 49 on the other side surface 45 on the back side.

  Therefore, when the entire built-in unit 22 is housed and held in the unit case 12 via the caulking portion 15, the flat washer 28 and the ground side pattern interposed in the peripheral portion 38 of the one side surface 35 of the printed circuit board 33. As a result of the conductive contact with the layer 37, the first gap portion 39 corresponding to the thickness of the ground side pattern layer 37 is formed in the peripheral portion 38 without the ground side wide pattern layer 37.

  Further, when the printed circuit board 33 is caulked and sealed, the input side narrow pattern layer 47 on the other side surface 45 and the conductive sleeve 27 are in conductive contact with each other, but between the substrate exposed surface 49 of the peripheral edge 48. As a result, the second gap 50 corresponding to the thickness of the input side pattern layer 47 is formed.

  In addition, since the notch 34 is formed on the peripheral edge 33a side of the printed circuit board 33, the printed circuit board 33 is formed of a thin air layer in which the first gap 39 and the second gap 50 are communicated with each other through the notch 34. A sound path 61 is formed.

  Therefore, the sound path 61 can exhibit a function as a rear acoustic terminal for introducing sound waves from the outside into the unit case 12 and also has an acoustic resistance function due to the thin air layer. It can be combined.

  Therefore, according to the present invention, the microphone unit 11 can be formed using the printed circuit board 33 that does not have the rear acoustic terminal hole, and hum noise that external electrical noise enters from the rear acoustic terminal hole. Can be cut off, and it is also possible to effectively prevent unwanted materials such as solder balls and dust from entering the unit case 12.

  Moreover, since the microphone unit 11 can be formed without the presence of the air chamber A and the acoustic mass as shown in FIG. 3, a good directional frequency response can be obtained without causing parasitic resonance.

  Further, the microphone unit 11 can increase or decrease the inner diameter of the flat washer 28, or adjust the thickness of the ground pattern layer 37 and the input pattern layer 47 to reduce the acoustic resistance function of the sound path 61. It can also be formed by adjusting to an optimum one according to the above.

  The above is the description of the present invention based on the illustrated example, and the specific configuration is not limited thereto. For example, the number of notches 34 provided in the printed circuit board 33 and the size of the notch surface can be set as desired. The number of arrangements of the ground side pattern layer 37 and the input side pattern layer 47 can be appropriately determined as desired. Further, in the illustrated example, an example is shown in which the width of the ground side pattern layer 37 is formed wider than the width of the input side pattern layer 47 from the viewpoint of enhancing the shielding effect. You can also.

It is explanatory drawing about an example of this invention, (a) is a longitudinal cross-sectional view, (b) shows the bottom view corresponding to (a), respectively. It is explanatory drawing which shows the positional relationship of the notch part and printed pattern in an example of the printed circuit board which comprises this invention, (a) of them is like FIG.1 (b), when it crimps and is fixed. (B) shows the other side surface located in the other side which becomes the one side side used as a sealing side surface, respectively. It is explanatory drawing which shows the prior art example of a unidirectional condenser microphone unit, Among them, (a) shows a longitudinal cross-sectional view, (b) shows the top view of the printed circuit board shown by (a), respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Unidirectional condenser microphone unit 12 Unit case 13 Bottom surface part 13a Front acoustic terminal hole 14 Opening part 15 Caulking part 16 Inner peripheral surface 22 Built-in unit 23 Diaphragm unit 23a Support ring 23b Diaphragm 24 Spacer 25 Back electrode plate 25a Peripheral end face 26 Insulating sleeve 27 Conductive sleeve 28 Plain washer 33 Printed circuit board 33a Perimeter 34 Notch 35 One side 36 Ring pattern layer 37 Ground side pattern layer 38 Perimeter 39 First gap 45 Other side 45a Impedance converter 46 Ring pattern layer 47 Input side pattern layer 48 Peripheral part 49 Substrate exposed surface 50 Second gap 61 Sound path

Claims (2)

A unit case that has a front acoustic terminal hole and has a bottomed cylindrical shape, and a side surface that becomes the sealing side surface when caulking the unit case side, extends radially from the vicinity of the center to the periphery A plurality of ground side pattern layers formed on the other side, and a plurality of input side pattern layers radially extending from the vicinity of the center to the peripheral position on the other side, leaving the substrate exposed surface at the periphery. Each of the printed circuit boards and a predetermined built-in unit accommodated in the unit case including a conductive sleeve in conductive contact with the input side pattern layer side of the printed circuit board,
The first gap portion on the one side surface formed in a portion other than the plain washer and the ground side pattern layer when the printed board having a plain washer interposed in the peripheral portion of the one side surface is caulked and sealed; A thin film in which the second gap portion on the other side surface formed between the conductive sleeve and the substrate exposed surface is communicated via one or more notches formed in the peripheral edge of the printed circuit board. A unidirectional condenser microphone unit characterized in that a function as a rear acoustic terminal is given to a sound path composed of an air layer.   The single adjustment according to claim 1, wherein the adjustment of the acoustic resistance generated by the sound path is made dependent on the size of the inner diameter of the plain washer and the thickness of the ground side pattern layer and the input side pattern layer. Directional condenser microphone unit.

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