US 3306990 A
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Feb. 28, 1967 BAKER STRUCTURE FOR MINIATURE RECEIVER AND TRANSMITTER R. H. WALKER 3,306,990 MICROPHONE AND SP Filed Jan. 13, 1964 I 36 J I 2 I I 30 2 1 i I 2 22 g II "I I I W;
United States Patent 3,306,990 MICROPHONE AND SPEAKER STRUCTURE FOR MINIATURE RECEIVER AND TRANSMITTER Robert H. Walker, Morton Grove, Ill., assignor to Motorola, Inc., Franklin Park, Ill., a corporation of Illinois Filed Jan. 13, 1964, Ser. No. 337,348 2 Claims. (Cl. 179-102) This invention relates in general to portable electronic apparatus, and in particular to a transistorized miniature radio transmitter and receiver device.
Miniaturized electronic apparatus has come into prominent usage in recent years, particularly in transistorized radio devices of the type of'carrying on the person and operated from a self-contained battery power source. The use of transistors makes it possible to provide a compact light weight transmitter and receiver powered by batteries, because of the small size and reduced operating power requirements of the transistor.
In a miniaturized hand held transmitter and receiver, the microphone and speaker must be separated from each other acoustically and electrically and must also be mounted on the unit so that they are easily used by the operator. Because of the small size of a hand held transmitter and receiver, the space available for mounting the speaker and microphone is limited. It is also desirable, in order that the unit may be easily used, that the speaker and microphone receive and transmit sound from the same location on the housing.
Accordingly, it is an object of this invention to provide an improved, compact microphone and loudspeaker structure for a miniature transistorized hand held receiver and transmitter wherein the microphone and speaker do not interfere with each other.
Another object is to provide a microphone and a speaker so positioned in a housing that the sound transmitted -by the speaker and received by the microphone enters and leaves the housing by the same opening therein.
A feature of this invention is the provision of a miniature hand held transistorized transmitter and receiver with a microphone located concentrically with respect to the speaker and positioned between the cone of the speaker and the housing of the transmitter and receiver unit, with the microphone being magnetically and acoustically shielded from the speaker.
Another feature of the invention is the provision of a miniature hand held transmitter and receiver in which the speaker and microphone are sealed to prevent moisture from entering the transmitter and receiver housing through the opening of the speaker and the microphone.
The invention is illustrated in the drawings, wherein:
FIG. 1 is a perspective view of a miniature hand held battery powered transmitter and receiver;
FIG. 2 is a cross-sectional view of the transmitter and receiver shown in FIG. 1;
FIG. 3 is another view showing the mounting of the speaker and microphone; and
FIG. 4 is an enlarged cross sectional view illustrating the mounting of the speaker and microphone in the mini-ature transmitter and receiver shown in FIG. 1.
In practicing this invention a miniaturized battery powered radio transmitting and receiving device is provided which includes a plastic housing containing the electric circuit components mounted on printed wiring boards. A speaker and microphone are concentrically mounted so that the operator can receive and transmit through one opening in the case. The microphone is mounted between the cone of the speaker and the housing. A metal covering is provided to secure the microphone within the housing, and to shield the microphone from the speaker magnet. Seals are provided to prevent the entrance of moisture into the housing.
receiver printed wiring Referring to the drawings; FIG. 1 is a perspective view of a miniature hand held transistorized transmitter and receiver 20, contained in a plastic housing 21. Located on one end of housing 21, are the volume and on-oif control 25, squelch control 26, frequency selection switch 27, and a telescopic antenna 24. A push-to-talk switch 23 is located on one side of housing 21. A grill 22 is provided behind which are located the speaker and the microphone.
FIG. 2 is a cross-sectional view of a miniature transmitter and receiver of FIG. 1 showing the location of the components inside the unit. Battery 34 is located in the battery compartment 42 at the bottom of the unit. The board 29 and transmitter printed wiring board 30 are held in position in plastic housing 21 between cover 31 and ledges 35. Speaker 33 is mounted to grill 22.
An enlarged view of the speaker and microphone mounting structure is shown in FIG. 3, and a cross-sectional view of FIG. 3 is shown in FIG. 4. Molded into grill 22 is an annular ridge 36 for speaker 33 and a rectangular ridge 28 for microphone 43. Rectangular ridge 28 for microphone 43 is concentrically located with respect to annular ridge 36 between speaker cone 40 and grill 22. Microphone 43 is surrounded by resilient material 45 and 47 which isolates the same acoustically from grill 22 and rectangular ridge 28. Microphone 43 includes a magnetic structure and a coil which generates electrical signals in response to sound waves, and the signals are coupled to transmitter wiring board 30 by wire cable 56. A metal cover 46 is held in place by screws 51 inserted into rectangular ridge 28. Screws 51 force cover 46 against resilient material 45 compressing it to secure microphone 43 within rectangular ridge 28. Gaskets 50 and 52 are provided to seal the rectangular ridge 28 and cover 46 to prevent the entrance of moisture through grill 22. Metal cover 46 also provides a magnetic shield to prevent interaction between the magnetic structure of microphone 43 and magnet 41 of speaker 33.
The edge 37 of speaker 33 is secured within annular ridge 36 by dogs 55 which are forced against the edge 37 by screws 54 inserted in threaded holes 48. As shown in FIG. 3 there are three holes 48 located in annular ridge 36 each of which is used to secure a dog 55 to fasten speaker 33 within annular ridge 3-6. Gasket 38, positioned between grill 22 and edge 37 of speaker 33 acts as a seal to prevent the entrance of moisture around the edges of the speaker.
In operating the miniature transmitter and receiver, it is grasped by the lower portion of case 39 and a finger is used to operate push-to-talk switch 23. When receiving, the operator places grill 22 near his car so that any sound from the speaker can be clearly heard. In transmitting, switch 23 is depressed and the operator speaks into grill 22. The sound from the speakers voice is picked up by microphone 43 and coupled to the transmitter portion of the unit.
Thus a structure has been shown for mounting a speaker and microphone in a miniature hand held transmitter and receiver so that the sound enters and leaves from the same opening in the transmitter and receiver housing. The speaker and microphone are isolated from each other acoustically and magnetically and the mounting is sealed to prevent the entrance of moisture into the housing.
What I claim is:
1. Apparatus for translating sound into electrical signals and for translating electrical signals into sound including in combination, housing means having an apertured wall, a speaker including a cone and a magnet mounted within said housing means with said cone positioned adjacent said wall, a microphone having a magnetic structure mounted on said wall between said speaker cone and said wall, resilient material means spacing one surface of said microphone from said wall and substantially surrounding the remaining surfaces of said microphone, and a cover plate of magnetic material support ing said microphone and fastened to said wall, said cover plate cooperating with said resilient material means and said microphone to mechanically support said microphone, to acoustically insulate said microphone from said speaker and said housing and to shield said magnetlc structure of said microphone from said magnet of said speaker.
2. Apparatus for translating sound into electrical signals and for translating electrical signals into sound including in combination, housing means having a wall containing an opening therein, said Wall having an annular ridge enclosing and opening and a rectangular ridge enclosing a portion of said opening, a speaker including a cone and a magnet mounted within said housing means, the edge of said speaker being located within said annular ridge, means cooperating with said annular ridge :and said edge of said speaker to fasten said speaker to said wall, a microphone mounted partially within said rectangular ridge and between said speaker cone and said housing wall, first gasket means positioned between the edge of said speaker and said annular ridge, said speaker and said microphone being so mounted with respet to said opening that sound generated by said speaker may freely leave said housing means and that sound outside said housing means may freely enter and actuate said micro- 3 phone, one surface of said microphone being spaced apart from said wall by first resilient material means, second resilient material means substantially. surrounding the remaining surfaces of said microphone and spacing the same apart from said rectangular ridge, said first and second resilient material means acting to acoustically isolate said housing means from said microphone, a cover plate of magnetic material fastened to said rectangular ridge, said cover plate cooperating with said microphone to shield said magnetic structure of said microphone from the magnetic field of said magnet, and further acting to compress said first and second resilient material means against said microphone to secure said microphone mechanically within said rectangular ridge, second gasket means positioned between said cover plate and said rectangular ridge, said first and second gasket means and said, first resilient material means acting to produce a seal for said housing means to prevent moisture from entering the circuit portion of the housing.
References Cited by the Examiner UNITED STATES PATENTS 1,196,562 8/1916 Lynch 179-102 1,201,060 10/1916 Kurman 179-102 1,460,034 8/1921 Murray 179-102 1,772,198 8/1930 Andersson 179-l02 2,485,405 10/1949 Olney et a1. 179-102 3,132,300 5/1964 Lefevre 325-16 JOHN W. CALDWELL, Examiner.