GB2064263A - Microphone unit - Google Patents
Microphone unit Download PDFInfo
- Publication number
- GB2064263A GB2064263A GB7941508A GB7941508A GB2064263A GB 2064263 A GB2064263 A GB 2064263A GB 7941508 A GB7941508 A GB 7941508A GB 7941508 A GB7941508 A GB 7941508A GB 2064263 A GB2064263 A GB 2064263A
- Authority
- GB
- United Kingdom
- Prior art keywords
- microphone
- foam
- microphone unit
- open cell
- plastics
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000006260 foam Substances 0.000 claims abstract description 28
- 239000004033 plastic Substances 0.000 claims abstract description 16
- 229920003023 plastic Polymers 0.000 claims abstract description 16
- 230000004888 barrier function Effects 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 7
- -1 polyethylene Polymers 0.000 claims abstract description 5
- 239000004698 Polyethylene Substances 0.000 claims abstract description 4
- 229920000573 polyethylene Polymers 0.000 claims abstract description 4
- 239000004820 Pressure-sensitive adhesive Substances 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000001746 injection moulding Methods 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000003522 acrylic cement Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000006261 foam material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/222—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only for microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/08—Mouthpieces; Microphones; Attachments therefor
- H04R1/083—Special constructions of mouthpieces
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/01—Electrostatic transducers characterised by the use of electrets
- H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones
Abstract
A microphone unit for a telephone handset includes a moisture barrier (7) between a cover plate (9) and an electret microphone (3). A sealed cavity is formed by the moisture barrier (7), an annular foam member (6), a first member (4) and the electret microphone (3). In order to equalise the air pressure between the atmosphere and the inside of the cavity the annular foam member (6) is constructed from an open cell plastics material, a suitable material being an open cell polyethylene foam. <IMAGE>
Description
SPECIFICATION
Microphone unit
The invention relates to a microphone unit for a telephone handset including a plastics film moisture barrier between a perforated cover plate and the microphone element in which the moisture barrier is carried by a plastics foam ring sandwiched between the cover plate and the microphone element or a member carrying the microphone element.
In such a microphone unit a sealed cavity may be formed between the moisture barrier and the microphone element and in such a case it is necessary to provide means for equalising the air pressure between the inside and the outside of the sealed cavity. It is known to provide a channel between the inside and outside of the cavity by cutting a groove in the plastics foam ring to allow air to pass between the inside and outside of the cavity. This procedure has the disadvantage that an additional manufacturing step, that of cutting the groove, is required which inevitably adds to the cost of the unit.
It is an object of the invention to provide an alternative means for equalising the pressure between the inside and outside of a cavity in a microphone unit.
The invention provides a microphone unit as described in the first paragraph characterised in that the plastics foam ring is formed from an open cell material so that air is allowed to pass into or out of a cavity formed between the film and the microphone element through the cells of the plastics foam.
By using an open cell plastics foam air is enable to leak into or out of the cavity through the structure of the foam and no further manufacturing step is required.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded cross-sectional elevation of a microphone unit for a telephone handset according to the invention,
Figure 2 is a cross-sectional elevation of a microphone unit assembled from the elements shown in Figure 1,
Figure 3 is a plan view of the plastics foam member used in the microphone unit shown in
Figure 2, and
Figure 4 is a cross-section on line A-A of the plastics foam member shown in Figure 3.
As shown in Figure 1 the microphone unit comprises a case 1, a printed circuit board 2 carrying an amplifier circuit, an electret microphone unit 3, a first member 4, a disc shaped plug member 5, a first annular foam
member 6, a circular melinex diaphragm 7, a second annular foam member 8, and a cover 9.
The case 1 is circular in plan and is formed as a polypropylene injection moulding. The case 1 carries two terminals, one of which is shown at 11, and has a shoulder 12 against which the printed circuit board 2 locates.
The printed circuit board has a central circular aperture in which the first member 4 locates with a shoulder 41 abutting against the surface of the printed circuit board. The electret microphone 3 is located in a circular recess 42 in the member 4 and thus when assembled projects through the printed circuit board 2 towards the base of the case 1. Three leads 21 which are attached to the printed circuit board 2 at one end are soldered to terminals on the electret microphone 3. The first member 4 has a further circular recess 43 aligned with the recess 42 and separated from it by a web 44 which is provided with a central aperture 45.
The plug member 5 is a force fit in the recess 43 and has a circular recess 51 and a central aperture 52. The web 44 and a plug 5 form opposed walls of a cavity consisting of the volume of the recess 51.
The annular foam members 6 and 8 are formed from an open cell polyethylene plastics foam and are provided with a pressure sensitive adhesive on each face so that when the microphone unit is
assembled the melinex diaphragm is sandwiched between the foam members 6 and 8 which are in turn sandwiched between the cover 9 and a flange 46 on the first member 4. The cover 9 is formed by injection moulding, has a number of apertures 91 through which sound waves pass and snap fits over a shoulder 13 on the case 1.
Figures 3 and 4 show the annular foam member on an enlarged scale. Two opposed faces 61 and 62 of the foam are provided with a pressure sensitive adhesive. The foam is of an open cell material and may be, for example, a polyethylene foam. The pressure sensitive adhesive on faces 61 and 62 may be an acrylic adhesive.
Figure 2 shows the assembled microphone unit and as can be seen from this figure the path for sound waves to the electret microphone unit 3 is through a series of cavities and apertures.
Apertures 91 in the cover 9 lead to a cavity 201 formed between the cover 9 and the melinex diaphragm 7. Sound pressure waves will cause the disc 7 to vibrate and thus transmit the pressure variations to a further cavity 202 formed between the diaphragm 7 the flange 46 on the first member 4 and an outer face 53 of the disc shaped member 5. These pressure variations are transmitted through the aperture 52 in the member 5 into the cavity 51 and through the aperture 45 to the electret microphone 3. This arrangement of cavities, diaphragm and apertures forms an acoustic filter which is tuned to provide a response which falls rapidly above about 3.5 KHz.
This characteristic is useful in telephone communications as it reduces the requirements for further filtering of the audio signal to restrict it to the available bandwidth. The use of an open cell foam for the annular member 6 allows pressure equalisation between the cavity 202 and the atmosphere through the cell structure of the foam.
By this means the provision of a separate pressure equalising channel is rendered unnecessary thus saving an additional manufacturing step.
It would be possible to use other open cell plastics foam materials for the member 6 the actual material chosen may depend on the environment in which the unit is to be used and the cost or availability of specific materials. The member 6 may be attached to the member 4 and/or the cover 9 by means other than a pressure sensitive adhesive, for example by being trapped between co-operating members.
Claims (4)
1. A microphone unit for a telephone handset including a plastics film moisture barrier between a perforated cover plate and the microphone element in which the moisture barrier is carried by a plastics foam ring sandwiched between the cover plate and the microphone element or a member carrying the microphone element, characterised in that the plastics foam ring is formed from an open cell material so that air is allowed to pass into or out of a cavity formed between the film and the microphone element through the cells of the plastics foam.
2. A microphone unit as claimed in Claim 1 in which the plastics foam is an open cell polyethylene foam.
3. A microphone unit as claimed in Claim 1 or
Claim 2 in which the foam is attached to the cover and microphone element or carrying member by a pressure sensitive adhesive.
4. A microphone unit substantially as described herein with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7941508A GB2064263B (en) | 1979-11-30 | 1979-11-30 | Microphone unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7941508A GB2064263B (en) | 1979-11-30 | 1979-11-30 | Microphone unit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2064263A true GB2064263A (en) | 1981-06-10 |
| GB2064263B GB2064263B (en) | 1983-08-03 |
Family
ID=10509545
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7941508A Expired GB2064263B (en) | 1979-11-30 | 1979-11-30 | Microphone unit |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2064263B (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0132039A2 (en) * | 1983-06-09 | 1985-01-23 | Robert Bacon Pepper | Moisture resistant cover for an electroacoustic transducer |
| EP0154256A2 (en) * | 1984-03-08 | 1985-09-11 | Polaroid Corporation | Ultrasonic transducer for use in a corrosive/abrasive environment |
| US4581490A (en) * | 1983-12-22 | 1986-04-08 | Richard Genender | Wall telephone assembly |
| US4920564A (en) * | 1987-11-19 | 1990-04-24 | British Telecommunications Public Company Limited | Moisture barrier assembly |
| US5574794A (en) * | 1995-01-19 | 1996-11-12 | Earmark, Inc. | Microphone assembly for adhesive attachment to a vibratory surface |
| US5802198A (en) * | 1997-02-25 | 1998-09-01 | Northrop Grumman Corporation | Hermetically sealed condenser microphone |
| EP0918426A1 (en) * | 1997-11-21 | 1999-05-26 | Electrowatt Technology Innovation AG | Out-door telephone handset construction |
| US6744900B1 (en) * | 1999-09-14 | 2004-06-01 | Mitel Knowledge Corporation | Complex acoustic path and gasket for use with microphones |
| US6978033B2 (en) * | 2001-02-20 | 2005-12-20 | Mitel Networks Corporation | Microphone gasket with integrated acoustic resistance |
| EP1912479A2 (en) * | 2006-10-10 | 2008-04-16 | BSE Co., Ltd. | An apparatus and a method of producing for microphone assembly |
| WO2015056443A1 (en) * | 2013-10-15 | 2015-04-23 | パナソニックＩｐマネジメント株式会社 | Microphone |
-
1979
- 1979-11-30 GB GB7941508A patent/GB2064263B/en not_active Expired
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0132039A2 (en) * | 1983-06-09 | 1985-01-23 | Robert Bacon Pepper | Moisture resistant cover for an electroacoustic transducer |
| EP0132039A3 (en) * | 1983-06-09 | 1986-07-23 | Robert Bacon Pepper | Moisture resistant cover for an electroacoustic transducer |
| US4581490A (en) * | 1983-12-22 | 1986-04-08 | Richard Genender | Wall telephone assembly |
| EP0154256A2 (en) * | 1984-03-08 | 1985-09-11 | Polaroid Corporation | Ultrasonic transducer for use in a corrosive/abrasive environment |
| EP0154256A3 (en) * | 1984-03-08 | 1986-07-30 | Polaroid Corporation | Ultrasonic transducer for use in a corrosive/abrasive environment |
| US4920564A (en) * | 1987-11-19 | 1990-04-24 | British Telecommunications Public Company Limited | Moisture barrier assembly |
| US5574794A (en) * | 1995-01-19 | 1996-11-12 | Earmark, Inc. | Microphone assembly for adhesive attachment to a vibratory surface |
| US5802198A (en) * | 1997-02-25 | 1998-09-01 | Northrop Grumman Corporation | Hermetically sealed condenser microphone |
| EP0918426A1 (en) * | 1997-11-21 | 1999-05-26 | Electrowatt Technology Innovation AG | Out-door telephone handset construction |
| US6744900B1 (en) * | 1999-09-14 | 2004-06-01 | Mitel Knowledge Corporation | Complex acoustic path and gasket for use with microphones |
| US6978033B2 (en) * | 2001-02-20 | 2005-12-20 | Mitel Networks Corporation | Microphone gasket with integrated acoustic resistance |
| US7035420B2 (en) | 2001-02-20 | 2006-04-25 | Mitel Knowledge Corporation | Microphone gasket with integrated acoustic resistance |
| EP1912479A2 (en) * | 2006-10-10 | 2008-04-16 | BSE Co., Ltd. | An apparatus and a method of producing for microphone assembly |
| EP1912479A3 (en) * | 2006-10-10 | 2010-06-02 | BSE Co., Ltd. | An apparatus and a method of producing for microphone assembly |
| WO2015056443A1 (en) * | 2013-10-15 | 2015-04-23 | パナソニックＩｐマネジメント株式会社 | Microphone |
| US10154340B2 (en) | 2013-10-15 | 2018-12-11 | Panasonic Intellectual Property Management Co., Ltd. | Microphone |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2064263B (en) | 1983-08-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4281222A (en) | Miniaturized unidirectional electret microphone | |
| KR920010408B1 (en) | Transmitter assembly for a telephone handset | |
| US4456796A (en) | Unidirectional electret microphone | |
| US5703957A (en) | Directional microphone assembly | |
| EP0906684B1 (en) | Communications terminal having a single transducer for handset and handsfree receive functionality | |
| US5226076A (en) | Directional microphone assembly | |
| DK2416589T3 (en) | Electroacoustic transducer and transducer device | |
| KR100636473B1 (en) | An electroacoustic communications unit | |
| US7019955B2 (en) | MEMS digital-to-acoustic transducer with error cancellation | |
| US4037064A (en) | Stereo microphone apparatus | |
| US4117275A (en) | Non-directional electret microphone with an air passage to balance pressures on opposite sides of the diaphragm | |
| GB2064263A (en) | Microphone unit | |
| GB2200814A (en) | Background noise cancelling microphone | |
| JPH04217199A (en) | Directional microphone assembly | |
| GB2064265A (en) | Microphone unit | |
| US20050190942A1 (en) | Microphone gasket with integrated acoustic resistance | |
| US4506759A (en) | Loudspeaker enclosure arrangement for voice communication terminals | |
| US4041251A (en) | Hearing aid to be worn behind the ear of the user and provided with a pressure-gradient microphone | |
| JPH0946403A (en) | Water-proof structure for sounder | |
| AU722074B2 (en) | Sound capturing method and device | |
| CA1050655A (en) | Microphone apparatus | |
| EP0129320B1 (en) | Loudspeaker enclosure arrangement for voice communication terminals | |
| CN209806086U (en) | Sound production device module and terminal equipment | |
| JPH0125013Y2 (en) | ||
| EP0222813B1 (en) | Improvements in or relating to microphones |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |