US2113219A - Microphone - Google Patents

Microphone Download PDF

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Publication number
US2113219A
US2113219A US728202A US72820234A US2113219A US 2113219 A US2113219 A US 2113219A US 728202 A US728202 A US 728202A US 72820234 A US72820234 A US 72820234A US 2113219 A US2113219 A US 2113219A
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United States
Prior art keywords
ribbons
microphone
velocity
pole
directional
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.)
Expired - Lifetime
Application number
US728202A
Inventor
Harry F Olson
Massa Frank
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US728202A priority Critical patent/US2113219A/en
Priority to DER93489D priority patent/DE711382C/en
Application granted granted Critical
Publication of US2113219A publication Critical patent/US2113219A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/08Microphones

Definitions

  • This invention relates to velocity microphones, and concerns particularly a velocity microphone having a cosine directional characteristc within a predetermined frequency range.
  • One object of the invention is to provide such a microphone which will avoid the pick-up of reverberated sounds.
  • Another object of the invention is to provide a microphone of the type referred to which is capable of being manufactured to any desired frequency-directional characteristics.
  • Another object of the invention is to provide an improved type of velocity or ribbon microphone.
  • Figure 1 shows our improved microphone with the cover removed therefrom.
  • Figure 2 is an elevation of the pole-pieces and ribbons thereof.
  • Figure 3 is a top ⁇ view of the pole-pieces and ribbons with the ribbon clamps and conductors removed.
  • Figure 4 is a plot of the response of our microphone.
  • the directional characteristics of the velocity ribbon microphone are independent of the frequency. In certain types of sound motion picture sets the reverberation time is greater at the higher frequencies. Furthermore, it is also desirable in some recordings to increase the discrimination against reflected sound to obtain a more intimate effect. To accomplish these objectives requires a sharpening of the directional characteristics of the velocity microphone at the higher frequencies. It is the purpose of this invention to provide a velocity microphone employing two ribbons separated in space and which eX- hibits a cosine directional characteristic in the range below 1000 cycles and a progressively sharper characteristic above 1000 cycles.
  • the directional characteristic of the conventional velocity ribbon microphone is given by the line joining the sound source and the ribbon.
  • Figs. 1, 2 and 3 Two corrugated aluminum ribbons .0001 thick (similar to the ribbons used in the usual velocity microphone) arerseparated by a distance of 2 inches between centers as shown in these figures.
  • the magnetic structure is designed to replace the pole assembly in the usual velocity microphone.
  • the two ribbons are electrically connected, as shown in Fig. 2, in order that the eective inductance of the ribbon circuit Will be reduced to a minimum and electrical pick-up thereby pre- I vented.
  • a permanent magnet I0 is mounted upon an appropriate casing II which houses an appropriate transformer, as described in the said prior patent.
  • pole-pieces I2 and I3 of appropriate high-permeability iron which are so shaped as to provide a uniform and high magnetic iiux across the ribbons I4 and I5 which are constructed in accordance with the said prior patent.
  • a polepiece yoke generally indicated at I6 and comprising the secondary pole-pieces Il and I8 and the magnetic connecting members I9 and 2U, distributing and concentrating the magnetic flux equally between the two ribbons.
  • the ribbons are supported by, and connected to, the clamps 2
  • the insulating members preferably of Bakelite, hard rubber, or l the like, 25, 2B, 21 and 28.
  • the dimensions of the several pole-pieces determine the individual frequency characteristics of the individual ribbons.
  • the cosine frequency directional characteristic referred to is determined by the lateral spacing between the ribbons.
  • a unitary device of the class described comprising a plurality of physically independent, series connected acoustically velocity-controlled elements located at a predetermined distance from each other Within the unit, and magnetic means common to both of said elements for supplying a magnetic field for each of them.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

Description

April 5, 1938.
Fig. I
Filed May s1. 1934 H. F. OLSON ET AL lllllll MICROPHONE 2 Sheets-Sheer, 1
O O o OO O O O l I O%%%OOOOOO OOO o Oo Oo Oo O o o o o l 9 O OO oo o0 oo o 0 OOOO OOO OO Ol 00 1 OOO .OO @090% /0 INVENToR HARM* F. M50/v ATTRNEY April 5, 1938. H. F. OLSON ET 'AL MICROPHONE Filed May 51, 1934.
2 Sheets-Sheet 2 mfg. 3
Oasi/H450 M S Y RWM M im will Hf Vl B Patented Apr. 5, 1938 PATENT OFFICE MICROPHONE Harry F. Olson, Collingswood, and Frank Massa, `Oaklyn, N. J., assignors to Radio Corporation of America, a corporation of Delaware Application May 31, 1934, Serial No. 728,202
3 Claims.
This invention relates to velocity microphones, and concerns particularly a velocity microphone having a cosine directional characteristc within a predetermined frequency range.
One object of the invention is to provide such a microphone which will avoid the pick-up of reverberated sounds.
Another object of the invention is to provide a microphone of the type referred to which is capable of being manufactured to any desired frequency-directional characteristics.
Another object of the invention is to provide an improved type of velocity or ribbon microphone.
1n the drawings: y
Figure 1 shows our improved microphone with the cover removed therefrom.
Figure 2 is an elevation of the pole-pieces and ribbons thereof.
20 Figure 3 is a top` view of the pole-pieces and ribbons with the ribbon clamps and conductors removed.
Figure 4 is a plot of the response of our microphone.
The directional characteristics of the velocity ribbon microphone are independent of the frequency. In certain types of sound motion picture sets the reverberation time is greater at the higher frequencies. Furthermore, it is also desirable in some recordings to increase the discrimination against reflected sound to obtain a more intimate effect. To accomplish these objectives requires a sharpening of the directional characteristics of the velocity microphone at the higher frequencies. It is the purpose of this invention to provide a velocity microphone employing two ribbons separated in space and which eX- hibits a cosine directional characteristic in the range below 1000 cycles and a progressively sharper characteristic above 1000 cycles.
The directional characteristic of the conventional velocity ribbon microphone is given by the line joining the sound source and the ribbon.
Let us consider a velocity microphone equipped with two parallel ribbons separated by a distance 55 D. The voltage output for a source of sound in the plane passing through the ribbons and vnormal to .axis of the ribbons is given by (WD sin e=e0 cos 0 cos where 0=angle between the normal to the ribbons and the line joining the sound source and the center line of the two ribbons,
D=distance between the ribbons,
}\= wavelength =v c'=velocity of sound, and f=frequency The theoretical directional characteristics are shown in Fig. 4. The observed directional characteris'tics are also shown in Fig. 4.
The essential details of construction are shown in Figs. 1, 2 and 3, Two corrugated aluminum ribbons .0001 thick (similar to the ribbons used in the usual velocity microphone) arerseparated by a distance of 2 inches between centers as shown in these figures. The magnetic structure is designed to replace the pole assembly in the usual velocity microphone.
The two ribbons are electrically connected, as shown in Fig. 2, in order that the eective inductance of the ribbon circuit Will be reduced to a minimum and electrical pick-up thereby pre- I vented. v
The general construction and operation of the usual velocity microphone referred to above is y shown, described and claimed in the patent to Olson No. 1,885,001 issued October 25, 1932 and, except for the arrangement of pole-pieces and ribbons, the present device is constructed in the same manner.
To describe in more .detail herein the construction of our microphone:
A permanent magnet I0 is mounted upon an appropriate casing II which houses an appropriate transformer, as described in the said prior patent. Upon the poles of the magnet I0 are mounted pole-pieces I2 and I3 of appropriate high-permeability iron which are so shaped as to provide a uniform and high magnetic iiux across the ribbons I4 and I5 which are constructed in accordance with the said prior patent.
Between the said ribbons is interposed a polepiece yoke -generally indicated at I6 and comprising the secondary pole-pieces Il and I8 and the magnetic connecting members I9 and 2U, distributing and concentrating the magnetic flux equally between the two ribbons.
The ribbons are supported by, and connected to, the clamps 2|, 22, 23 and 24, which are respectively insulated from the rest of the structure by the insulating members, preferably of Bakelite, hard rubber, or l the like, 25, 2B, 21 and 28.
'Ihe several leads 3D, 3l and 32 are connected as illustrated in Fig. 2, so that the ribbons are connected in series but not in opposition.
'This double ribbon microphone as shown in Fig. l has shown a measured ux density of 1450 eausses in each air gap. This is somewhat higher than half the flux density in a corresponding velocity microphone with a single air gap. The increased magnetic efficiency results from the reduction in pole face leakage.
Frequency response measurements made along the axis passing between the ribbons and normal to the plane of the ribbons in this microphone show the same characteristic as obtained with a standard Velocity microphone. The observed directional characteristics of the microphone at various frequencies are shown on the right hand portion of Fig. 4. On the left hand portion of the same figure are shown the theoretical directional characteristics which check fairly Well with the observed curves.
As described in the said prior patent, the dimensions of the several pole-pieces determine the individual frequency characteristics of the individual ribbons. However, in the present device, the cosine frequency directional characteristic referred to is determined by the lateral spacing between the ribbons.
We do not mean to be limited in the present invention to the specific construction, characteristics, and dimensions described above as the present preferred and commercial form of our invention, as it will be apparent that Within the scope of our invention we may provide any number of ribbons in a corresponding arrangement; or We may render the individual frequency characteristics of the ribbons asymmetrical by altering the size of the bales around them so as to make the curves of Fig. 4 lop-sided; or we may place the ribbons at a different angle to each other to modify the frequency-directional characteristics.
Having now described our invention, we claim:
1. A unitary device of the class described comprising a plurality of physically independent, series connected acoustically velocity-controlled elements located at a predetermined distance from each other Within the unit, and magnetic means common to both of said elements for supplying a magnetic field for each of them.
US728202A 1934-05-31 1934-05-31 Microphone Expired - Lifetime US2113219A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US728202A US2113219A (en) 1934-05-31 1934-05-31 Microphone
DER93489D DE711382C (en) 1934-05-31 1935-06-01 Ribbon microphone

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US728202A US2113219A (en) 1934-05-31 1934-05-31 Microphone

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US2113219A true US2113219A (en) 1938-04-05

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421820A (en) * 1941-03-07 1947-06-10 Hartford Nat Bank & Trust Co Microphone
US2495809A (en) * 1945-09-06 1950-01-31 Rca Corp Signal expansion or compression
US11297423B2 (en) 2018-06-15 2022-04-05 Shure Acquisition Holdings, Inc. Endfire linear array microphone
US11297426B2 (en) 2019-08-23 2022-04-05 Shure Acquisition Holdings, Inc. One-dimensional array microphone with improved directivity
US11302347B2 (en) 2019-05-31 2022-04-12 Shure Acquisition Holdings, Inc. Low latency automixer integrated with voice and noise activity detection
US11303981B2 (en) 2019-03-21 2022-04-12 Shure Acquisition Holdings, Inc. Housings and associated design features for ceiling array microphones
US11310592B2 (en) 2015-04-30 2022-04-19 Shure Acquisition Holdings, Inc. Array microphone system and method of assembling the same
US11310596B2 (en) 2018-09-20 2022-04-19 Shure Acquisition Holdings, Inc. Adjustable lobe shape for array microphones
US11438691B2 (en) 2019-03-21 2022-09-06 Shure Acquisition Holdings, Inc. Auto focus, auto focus within regions, and auto placement of beamformed microphone lobes with inhibition functionality
US11445294B2 (en) 2019-05-23 2022-09-13 Shure Acquisition Holdings, Inc. Steerable speaker array, system, and method for the same
US11477327B2 (en) 2017-01-13 2022-10-18 Shure Acquisition Holdings, Inc. Post-mixing acoustic echo cancellation systems and methods
US11523212B2 (en) 2018-06-01 2022-12-06 Shure Acquisition Holdings, Inc. Pattern-forming microphone array
US11552611B2 (en) 2020-02-07 2023-01-10 Shure Acquisition Holdings, Inc. System and method for automatic adjustment of reference gain
US11558693B2 (en) 2019-03-21 2023-01-17 Shure Acquisition Holdings, Inc. Auto focus, auto focus within regions, and auto placement of beamformed microphone lobes with inhibition and voice activity detection functionality
US11678109B2 (en) 2015-04-30 2023-06-13 Shure Acquisition Holdings, Inc. Offset cartridge microphones
US11706562B2 (en) 2020-05-29 2023-07-18 Shure Acquisition Holdings, Inc. Transducer steering and configuration systems and methods using a local positioning system
US11785380B2 (en) 2021-01-28 2023-10-10 Shure Acquisition Holdings, Inc. Hybrid audio beamforming system
US12028678B2 (en) 2020-10-30 2024-07-02 Shure Acquisition Holdings, Inc. Proximity microphone

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421820A (en) * 1941-03-07 1947-06-10 Hartford Nat Bank & Trust Co Microphone
US2495809A (en) * 1945-09-06 1950-01-31 Rca Corp Signal expansion or compression
US11832053B2 (en) 2015-04-30 2023-11-28 Shure Acquisition Holdings, Inc. Array microphone system and method of assembling the same
US11678109B2 (en) 2015-04-30 2023-06-13 Shure Acquisition Holdings, Inc. Offset cartridge microphones
US11310592B2 (en) 2015-04-30 2022-04-19 Shure Acquisition Holdings, Inc. Array microphone system and method of assembling the same
US11477327B2 (en) 2017-01-13 2022-10-18 Shure Acquisition Holdings, Inc. Post-mixing acoustic echo cancellation systems and methods
US11800281B2 (en) 2018-06-01 2023-10-24 Shure Acquisition Holdings, Inc. Pattern-forming microphone array
US11523212B2 (en) 2018-06-01 2022-12-06 Shure Acquisition Holdings, Inc. Pattern-forming microphone array
US11770650B2 (en) 2018-06-15 2023-09-26 Shure Acquisition Holdings, Inc. Endfire linear array microphone
US11297423B2 (en) 2018-06-15 2022-04-05 Shure Acquisition Holdings, Inc. Endfire linear array microphone
US11310596B2 (en) 2018-09-20 2022-04-19 Shure Acquisition Holdings, Inc. Adjustable lobe shape for array microphones
US11778368B2 (en) 2019-03-21 2023-10-03 Shure Acquisition Holdings, Inc. Auto focus, auto focus within regions, and auto placement of beamformed microphone lobes with inhibition functionality
US11438691B2 (en) 2019-03-21 2022-09-06 Shure Acquisition Holdings, Inc. Auto focus, auto focus within regions, and auto placement of beamformed microphone lobes with inhibition functionality
US11558693B2 (en) 2019-03-21 2023-01-17 Shure Acquisition Holdings, Inc. Auto focus, auto focus within regions, and auto placement of beamformed microphone lobes with inhibition and voice activity detection functionality
US11303981B2 (en) 2019-03-21 2022-04-12 Shure Acquisition Holdings, Inc. Housings and associated design features for ceiling array microphones
US11800280B2 (en) 2019-05-23 2023-10-24 Shure Acquisition Holdings, Inc. Steerable speaker array, system and method for the same
US11445294B2 (en) 2019-05-23 2022-09-13 Shure Acquisition Holdings, Inc. Steerable speaker array, system, and method for the same
US11302347B2 (en) 2019-05-31 2022-04-12 Shure Acquisition Holdings, Inc. Low latency automixer integrated with voice and noise activity detection
US11688418B2 (en) 2019-05-31 2023-06-27 Shure Acquisition Holdings, Inc. Low latency automixer integrated with voice and noise activity detection
US11750972B2 (en) 2019-08-23 2023-09-05 Shure Acquisition Holdings, Inc. One-dimensional array microphone with improved directivity
US11297426B2 (en) 2019-08-23 2022-04-05 Shure Acquisition Holdings, Inc. One-dimensional array microphone with improved directivity
US11552611B2 (en) 2020-02-07 2023-01-10 Shure Acquisition Holdings, Inc. System and method for automatic adjustment of reference gain
US11706562B2 (en) 2020-05-29 2023-07-18 Shure Acquisition Holdings, Inc. Transducer steering and configuration systems and methods using a local positioning system
US12028678B2 (en) 2020-10-30 2024-07-02 Shure Acquisition Holdings, Inc. Proximity microphone
US11785380B2 (en) 2021-01-28 2023-10-10 Shure Acquisition Holdings, Inc. Hybrid audio beamforming system

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