US 3194887 A
Description (OCR text may contain errors)
July 13, 1965 J. PRESTON 3, 7
PERSONAL MICROPHONE LINE TRANSFORMER Filed Oct. 31, 1960 2 Sheets-Sheet 1 INV EN TOR. John Preston July 13, 1965 J. PRESTON 3,194,887
PERSONAL MICROPHONE LINE TRANSFORMER I Filed Oct. 31, 1960 2 Sheets-Sheet 2 1''! 1 WR V INVEN TOR. John Preston Attm'm United States Patent Ofi 3,1945%? Patented July 13, 1965 ice 3,194,887 PERSONAL MICROPHONE LINE TRANSFQRMER .lohn Preston, Trenton, N..l'., assignor to Radio Corporation of America, a corporation of Delaware Filed Oct. 31, 1960, Ser. No. 66,022 2 Claims. (Cl. 179-1) The present invention relates to microphone systems and more particularly to a system for providing a personal microphone.
Personal microphones have become popular for use by television performers, since they do not interfere with the performers movement during a television program. Presently available personal microphones which have the quality of sound pick-up desired in television broadcast applications are normally worn suspended around the neck of the performer and are readily visible to the audience. A still smaller, lighter personal microphone is desirable which can be attached to the clothing of the performer, as for example to his necktie, and is essentially unobtrusive. A problem resides in providing personal microphones having the size, weight and the quality of sound pick-up which are needed for television broad cast applications.
It is, therefore, an object of the present invention to provide an improved microphone system which is small and light in weight, which has high quality sound pick-up characteristics, and which is adapted to be worn by a performer.
It is a further object of the present invention to provide an improved, pressure type, dynamic microphone which is small in size and light in weight and which is adapted to be clipped directly to the clothing of a person using the microphone.
It is a still further object of the present invention to provide an improved microphone as above set forth which is of such size as to be unobtrusive and practically inconspicuous when worn by a user.
It is a still further object of the present invention to provide an improved microphone system wherein noise pick-up is counteracted.
It is another object of the present invention to provide an improved microphone system employing a microphone of the dynamic type smaller than those of the like type that have been heretofore available with comparable quality of sound pick-up.
Briefly described, a microphone system in accordance with the invention includes a microphone of the pressure responsive type having a vibrating system including a voice coil disposed to vibrate in a magnetic field in response to sound pressure. The vibrating system and means for generating the magnetic field are of extremely small size and are enclosed in a case which may have a clip or otherwise clothing gripping or other engageable element attached thereto. A cable including wires which are connected to the voice coil extends from the case. The microphone may be clipped to the clothing of a performer, as, for example, to his necktie, and is of such a small size and weight as not to disturb the arrangement of the performers clothing or freedom of movement. The cable is connected to plug means including a transformer as an integral part thereof. This transformer part is interchangeable with other similar transformer parts to provide a plurality of impedance transformations. A cable from the plug means extends to an amplifier or other broadcast studio sound equipment.
Because of the construction of the microphone and the provision of plug means which includes the interchangeable transformer part, the microphone itself is of an extremely small size and weight so that the performer can clip the microphone readily to his necktie, shirt or other article of clothing. This eliminates the need to: suspending the microphone about the performers neck. The extremely small size of the case, including the microphone vibrating system, also permits the elimination of a cavity behind the vibrating system which is normally occupied by a transformer in known personal microphones. Accordingly, the compliance behind the diaphram which is due to the mass of air in the case is reduced and the frequency response of the microphone extends into the range of high audio frequencies (e.g., from 8,000 to 15,000 c.p.s.). The quality of sound pick-up of the microphone system provided by the invention is therefore adequate for broadcast applications.
The invention itself, both as to its organization and method of operation, as well as additional objects and advantages thereof, will become more readily apparent from a reading of the following description in connection with accompanying drawings, in which:
FIGURE 1 is a pictorial view showing a microphone system provided by the invention in use by a performer during a broadcast program;
FIGURE 2 is a sectional view of a pressure type dynamic microphone in accordance with the invention;
FIGURE 3 is a sectional view showing a plug means which is used in a microphone system provided by the invention; and
FIGURE 4 is a schematic diagram showing the manner in which noise pick-up is reduced in the microphone system provided by the invention.
Referring to FIG. 1, there is shown a broadcast studio in which a performer 10 is broadcasting a program. A control room 12 is located adjacent the studio. This control room 12 contains broadcast audio equipment including studio consoles 14. The consoles include audio amplifiers and preamplifiers. An outlet 16 is provided in the wall of the control room 12. This outlet 16 is connected to the input of the audio amplifiers in the consoles 14. i
The microphone system provided by the invention includes a pressure type dynamic microphone 18 which has a clip or the like 20 attached to the case thereof. The microphone 18 is clipped to the necktie 24 of the performer 10 in a manner similar to a conventionl necktie clip. The microphone is of such small size and weight as not to disturb the set of the performers necktie 24, Alternatively, the microphone 18 may be clipped to the clothing of the performer, as, for example, to his lapel 26. The case 22 of the microphone 1'8 and the clip 20 may be painted in a color to match or blend with the clothing of the performer. Since the microphone 18 is of small size and is attached to the clothing of the performer, it is unobtrusive. The microphone 18 is connected by means of a microphone cable 28 to plug means 30. This plug means 30 includes a male plug 32 which is attached to the end of the cable 28 and a case 34 having female and male plugs 36 and 38 located, respectively, at opposite ends thereof. The case 34 also contains a transformer for the purpose of matching the output impedance of the microphone 18 to the input impedance of the amplifiers in the consoles 14 of the control room. The case is interchangeable with other similar cases by disconnecting the plugs 36 and 38 on one case and connecting the plugs 36 and 38 on the other.
The outlet 16 has a receptacle to which a cable 40 is attached. One end of the cable 40 is connected to a female plug 42 which is shown connected to the male plug 38 of the plug means 3 0.
Plug means 30, including cases containing different transformers, may be included in the interchangeable microphone system. Each transformer is capable of providing a different impedance match. Accordingly, the
output impedance of the microphone 18 can be matched to the input impedance of amplifiers in studio consoles which have different input impedances. Different broadcast stations and networks use amplifier systems having different input impedances. Thus, differentmicrophone system output impedances are required. For example, the three major broadcasting networks in the United States require microphone system output impedances of 30 ohms, 156 ohms, and 250 ohms, respectively. The output impedance of the microphone 1?; alone may be 30 ohms. In the event that the microphone is used in a broadcast station requiring a 39 ohm output impedance,
the male plug 32 of the plug means may be inserted directly into the female plug 42 thereof and the case 34 including the transformer may be disconnected. The plug means 3%) includes different cases 34 with transformers having different turns ratios between the windings thereof which can be used when a 150 ohm or 250 ohm output impedance is reduired. The male and female plugs 32 and 42 of the cables 28 and ltl may be readily connected to and disconnected from the female plugs 36 and male plugs 38 at opposite ends of the different transformer cases 34.
The entire plug means 3% may be of very small size. It is desirably inserted into the coat pocket of the clothing worn by the performer. Alternatively, it may be placed on the floor of the studio.
It will be observed from FIG. 1 that the sound spoken by the performer it) travels along a path substantially such as indicated by the dashed lines-44 to the aperturedcover 46 of the case 22 of the microphone 18. This sound is picked up by the microphone and translated into electrical signals which pass through the cables 28 and 4'8 and the transformer in the transformer case 34 to the amplifiers in the studio consoles 14.
A major source of noise in personal microphone systems is attributable to the movement of the performer. In known microphone systems wherein the microphone is suspended from the neck of the performer, his movements cause the microphone and cable to rub against his clothing. This rubbing generates undesirable noises which are picked up by the microphone.
The manner in which noise is generated when the performer moves about is illustrated in FIG. 4. Here, the case 4-8 of a microphone which is suspended from the neck of the performer is shown. This microphone is normally in contact with a surface 54} of the clothing worn by the performer. When the performer moves about, the case 48 rubs against the surface 54 since the microphone swings on the chain or lavalliere which suspends it from the neck of the performer. This rubbing generates sound which is conducted (1) by way of the case 48 of the microphone, and (2) by way of the air to the diaphgram of the microphone. The dashed lines 510 show the direction of transmission, by way of the case 48, of the noise caused .by rubbing of the case 48 system 5 -iwhich are mounted in the microphone case 22. The microphone case 22 is generally cup-shaped and may be constructed of aluminum or other non-magnetic material. The clip Ztl is secured to the case 22 by soldering, welding or in any other suitable manner. The clip 2% may be a necktie clip, as shown in FIG. 1. Alternatively, the clip 21} may be a spring clip of the type used on fountain pens, or in lieu of the clip, a reversely bent hook or pin may be used to mount the microphone on the clothing. Accordingly, the microphone 18 may be clipped in the vest pocket or otherwise to the clothing of the performer as though it were a fountain pen.
The case 22 is terminated by an apertured case cover 46 (FIG. 2) through which the sound spoken by the performer enters the case 22 and exerts pressure upon the vibrating system 54.
The magnetic structure 52 includes acup-shaped yoke 56 having along its outer surface a longitudinal groove 58 which extends generally parallel of the axis of the yoke as. A cylindrical magnet 69 is disposed in the yoke 56. A pole cap 62 of soft magnetic material is disposed on the magnet se. The magnetic end pole caps are held to the yoke 56 by means ofa screw 64 having an axial bore. The yoke has a flange 66 which engages an internal lip 68 on the case 22s A ring 70 of magnetic material provides the top plate of the magnetic structure 52 and defines an air gap with the pole cap 62. A felt washer T2 is disposed between the polecap 62 and the ring 70 and is held in place by means of apertured rings 74. A terminal block 76 is secured to the base of the yoke 56. It will be noted that the yoke 5'6 and terminal block 76 occupy ahncst the entire volume of the case 22, the air space in the case being limited.
The vibrating system 54 includes a diaphragm 78, its suspension 80, and a voice coil 82. The suspension is mounted on a ring 84 which is disposed on top of the yoke 56. The cover 46 engages the top of the suspension and clamps the vibrating system 54 and magnetic structure 52 to the case 22. The wire of the voice coil 82 is brought to terminals 76a on the terminal block 76 through the groove 58 in the yoke 56 and through a cooperating groove in the ring 84. These grooves are relatively shallow and do not affect the mechanical strength of the structure.
against the surface 50 of the clothing. The dashed lines 7 5101 show the direction of transmission of this noise through the air. 7
It is a feature of the present invention to minimize the generation of noise caused by rubbing of the microphone case against the clothing of the performer. Since the microphone is of small size and weight, it is clipped to the clothing of the performer. Accordingly, the microphone moves with the clothing and therefore movement of the case relative to the clothing, which might cause rubbing and noise, is reduced. Movement of the cable 23 is also minimized since this cable 28 maybe short because the plug means 39, to which the cable 28 is connected, can be inserted in the coat pocket of the performer together with any excess length of cable. Thus,
noise generated by the rubbing of the cable 28-against the performers clothingis also reduced. 7
Referring to FIG. 2, it will be observed that the microphone 18 includes a magnetic structure 52 and a vibrating The cable '28 extends into the case 22 through the bottom thereof as viewed in FIG. 2. A sleeve 86 may be formed in the bottom of the case 22 for firmly holding the cable 28. The wires from the cable 2 8 are connected to the terminals 76a. The microphone unit as a whole is very small. For example, the case 22 may be one inch length along its longitudinal axis and three-quarters inch in diameter. The case is occupied almost entirely by the magnetic structure 52, and the volume confined in back of the diagram 78 is relatively small as compared with the corresponding volume in conventional microphones, even those of the personal type. The compliance of the vibrating system due .to the mass of air in the space behind the diaphragm is therefore very low. Accordingly, the frequency of resonance of the vibrating system is quite high. Thisresonance is clamped by the felt Washer 72. Thus, theresponse of the microphone is regular and extends into the high frequency audio range. The quality of sound pick-up is therefore adequate for broadcast use of the microphone.
The plug means 363 is shown in detail in FIG. 3. The plug means includes the male plug 32 to which the cable 28 is connected and the female plug 52 to which the cable 46 isconnected. This male plug 32 and this female plug 42 may be of known design. The case 34 of the plug means includes three interconnected, hollow, cylindrical shells 9t 92 and 94. The female plug 36 is disposed in an end shell and the male plug 38 is disposed in the opposite end shell 94. These plugs 36 and 38 may also be of known construction and will therefore not be described in detail herein. A transformer 96 is disposed in the shell 92, This transformer 96 includes a closed E-shaped core structure around the center leg of which primary and secondary windings are located. The primary windings are connected to the female plug 36. The secondary windings are connected to the male plug 38. The external surface of the core structure of the transformer 96 may be coated with insulating material so that the terminals of the plugs 36 and 38 are not short circuited or otherwise interconnected.
It will be apparent that the male plug 32 may be inserted directly into the female plug 42 and the transformer unit of the plug means eliminated if the output impedance of the microphone matches the input impedance of the amplifier used by the broadcast studio. In the event that an impedance transformation is required, a different transformer case 34 and its associated female and male plugs 36 and 33 may be used, as explained above.
From the foregoing description, it will be apparent that there has been provided an improved dynamic microphone and microphone system. The microphone is extremely small in size and weight and may be Worn on the clothing of a performer as a personal microphone with a minimum of noise generation and a minimum of conspicuousness. The microphone also provides broadcast quality sound pick-up. The microphone system is also essentially universally adaptable for use in different broadcast studios despite diiferent input impedances of the studio amplifiers thereof. While only one embodiment of the microphone and microphone system provided by the invention has been described, variations in the microphone and in the microphone system, all within the scope of the invention, will become apparent to one skilled in the art. Accordingly, the foregoing should be taken as illustrative and not in any limiting sense.
What is claimed is:
1. In a signal translating system, the combination of a microphone for converting acoustical vibrations into electrical signals capable of being amplified by amplifying means remote from said microphone, a first cable connected to said microphone for providing a partial output path for said signals, a second cable connectable to the input of said amplifying means and also providing a partial output path for said signals, and selectively interchangeable transformer means spaced from both said microphone and said amplifying means for connecting said cables to each other whereby to complete the output path from microphone and provide a coupling from said microphone to said amplifying means, said transformer means including a casing having a plurality of detachably connected shells including a pair of end shells at opposite ends thereof and an intermediate shell, a pair of coupling members, one in each of said end shells, and a transformer in said intermediate shell having windings respectively connectable to said coupling members when said end shells and said intermediate shells are in connected relation, said first cable being detachably conuectable to one of said coupling members and said second cable being detachably connectable to the other of said coupling members, and said transformer being separable from said coupling members upon separation of said end shells and said intermediate shell to thereby enable ready replacement of said transformer at will.
2. A microphone system which comprises a microphone adapted to be worn by a performer and including a case having a clip attached thereto, said case being attachable to the clothing of a user by means of said clip, plug means including a transformer unit comprising a casing having a pair of end shells and an intermediate shell detachably connected to said end shells, a transformer within said intermediate shell interchangeable Within said plug means upon separation of said end and intermediate shells from each other for providing different impedance transformations, said transformer unit having a first male plug and a first female plug respectively within said end shells at opposite ends thereof, said plug means also including a second male plug and a second female plug connectable, respectively, to said first female plug and said first male plug of an individual one of said transformer units, an amplifier, a cable connected to said microphone and having one of said second plugs of said plug means at one end thereof, and a second cable connected to the input of said amplifier at one end thereof and having the other of said second plugs at the opposite end thereof.
References Cited by the Examiner UNITED STATES PATENTS 1,574,064 2/26 Chamberlain 336-107 1,696,897 1/29 Aiken 179-1 1,741,265 12/29 Wappler 336-107 1,991,221 2/35 Kingsford 179-1155 2,176,732 10/39 Faber 179-1 2,552,800 5/51 Lybarger 179-115 2,611,042 9/52 De Naploi 179-178 2,728,818 12/55 Mackey et al 336-142 X 2,862,069 11/58 Marchand et a1 -e 179-1155 2,929,877 3/60 Irick 179-1 3,029,307 4/62 Baxt 179-1 X 3,052,758 9/62 Berry 179-1 OTHER REFERENCES The Radio-Electronic Master, 21st Edition, United Catalog Publishers, Inc., New York, NY. Copyright 1956, pages D-3, D-ll, and F-24.
Audio Engineering Society Journal, Vol. 5, No. 2, April 1957, pages 83-85.
Electronic Technician, page 55, June 1959.
ROBERT H. ROSE, Primary Examiner.
WILLIAM C. COOPER, L. MILLER ANDRUS,