US2491390A - Electronic transducer - Google Patents

Electronic transducer Download PDF

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Publication number
US2491390A
US2491390A US706967A US70696746A US2491390A US 2491390 A US2491390 A US 2491390A US 706967 A US706967 A US 706967A US 70696746 A US70696746 A US 70696746A US 2491390 A US2491390 A US 2491390A
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US
United States
Prior art keywords
diaphragm
bar
electrode
mass
mechanical
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
US706967A
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English (en)
Inventor
Harry F Olson
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
Priority to NL71653D priority Critical patent/NL71653C/xx
Priority to FR954725D priority patent/FR954725A/fr
Application filed by RCA Corp filed Critical RCA Corp
Priority to US706967A priority patent/US2491390A/en
Priority to GB28496/47A priority patent/GB647152A/en
Application granted granted Critical
Publication of US2491390A publication Critical patent/US2491390A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J21/00—Vacuum tubes
    • H01J21/02—Tubes with a single discharge path
    • H01J21/06—Tubes with a single discharge path having electrostatic control means only
    • H01J21/08—Tubes with a single discharge path having electrostatic control means only with movable electrode or electrodes

Definitions

  • This invention relates to electronic transducers, and more particularly to a transducer suitable for reproduction of sound from a phonograph record.
  • the primary object of my present invention is to provide an improved electronic transducer of the type under consideration in which the driving link or rod between the source of the driving force and the movable or vibratile electrode will have a small mechanical mass reactance.
  • Another object of my present invention is to provide an improved electronic transducer which can be replaced easily without requiring the service of one with technical training.
  • a further object of my-present invention is to provide an improved electronic transducer which will not be affected by temperature or humidity changes.
  • Still another object of my present invention is to provide an improved electronic transducer as above set forth which will have an electrical impedance that renders it particularly suitable for use as an electric pick-up device for phonographs in contrast to the relatively high impedance which characterizes so-called crystal pick-ups and the low impedance of so-called magnetic pick-ups from the standpoints of transmission and electrical noise pick-up.
  • the transducer consists, essentially, of an evacuated vessel, such as a metal tube envelope, one wall of which, such as the base, is constituted by a thin, metallic diaphragm.
  • the tube may be a diode, in which case the plate or anode is arranged to be the movable electrode, or it may be a triode, a pentode or any other suitable type of multi-electrode tube, in which case the grid may constitute the movable electrode.
  • the movable electrode is mounted on the aforesaid diaphragm which constitutes a flexible support therefor.
  • an actuating link which, in the case of a phonograph pick-up, may carry or be coupled to a phonograph needle, or in the case of a microphone, may be coupled to a suitable vibratory diaphragm adapted to be set in vibration by sound waves impinging thereon.
  • control electrode The movable electrode, whether the anode of a diode or the grid of a triode or the like, will be referred to hereinafter as the control electrode.
  • This control electrode should preferably extend in a direction generally parallel to that of the cathode or electron emitting electrode.
  • the control electrode may be of various cross sections'as will appear more fully hereinafter, but I have found from my investigations that a control electrode fundamental vibrating system for transferring which is tapered, and preferably conical, with its a base end secured to the diaphragm wall of the envelope or shell provides best results.
  • Figure 2 is a wiring diagram showing the elec-' trical analogue of the mechanical network of Figure 1,
  • Figure 3- is a curve showing the response fre quency characteristic of the form of my invention shown in Figure 1 when the vibratory bar or rod is stiff and its mechanical resistance is small, the solid line curve showing the characteristic without damping, and the dotted line curve showing thezcharacteristic with damping,
  • Figure 4 is a similar curve in which all the elements of the vibrating system are effective in the'response range, the mechanical resistances of the various parts of the system being small,
  • Figure 5 is a side elevation, partly in section of one form of pick-up device for use with phonograph records in accordance with my present invention
  • Figure 6 is a sectional view of one form of microphone in accordance with my present invention.
  • Figures 7cr-I2a,inelusive, are graphic viewsv of cantilever bars of various configurations showing the various forms: in which the control electrode of mypresent invention may be made,
  • Figures lb-+121 are end views thereof as seen from the right of each of Figures la-12a,
  • Figure 13 is a graph showing the. deflection of a conical and a cylindrical control electrode such as illustrated in Figures 7a,. 'lb, and. 12a, 1212,
  • Figures 14 and 16 are side elevations, partly in section, of other forms of phonograph pick-up devices according to my present invention.
  • Figure 15 is a. wiring diagram showing the electrical analogue of the vibratory systems of Figures 14 and 16, I,
  • Figure 17 is a sectional view of another form of microphone in accordance. with my present. invention.
  • Figure 18 1s awiring diagram showing the electrical analogue. of the mechanical network of the vibratory system of the microphone of Figure 1'7.
  • an evacuated. vessel comprising a metallic shell! having an opening in the wall structure which is closed by'a thin, flexible, metallic diaphragm. 3.
  • a cathode 5 which may be heated by a filament 1,. and. an anode 9a. which is constituted by the inner portion of an elongated rod or bar 9 which extends through and is secured toa flexible diaphragm 3, the rod 9 having a portion 9b which is external to thevessell.
  • M is apparent, therefore, that since the bar or rod 9-is anchored at the diaphragm 3,, its inner portion (that 15,. thew;- wares impinging thereon.
  • the response frequency characteristic of an electronic transducer such as shown in Figure 1 and in which the bar 9 has a very high stiffness is shown by the solid line curve of Figure 3.
  • the effect of the compliances c1 and cs. are negligible in the frequency range under consideration.
  • the ratio of the amplitude to the force is independent of the frequency below the resonant frequency.
  • a transducer of the type shown in Figure 1 in which all the elements of thevibrating system are effective in the selected response range is shown by the. solid line curve of Figure 4.
  • the sharp peaks in the response range are undesirable and must be damped in transducers used in the reproduction of sound.
  • the mechanical system outside the shell I may be damped, if desired, by the application of damping material to the rod portion 92) and also to the diaphragm 3, as will be described more fully hereinafter with. reference to Figure 5.
  • the rod 91 may be made of hollow tubing with damping material within it.
  • the response frequency characteristics will appear as shown by the dotted line curves of Figures 3 and 4 when damping is applied. In the latter case, .the. mechanical resistances are relatively large.
  • FIG 5 there is shown a pick-up device utilizing the features of my invention discussed above.
  • the metallic shell or vessel I is secured to a pick-arm arm I! and the rod portion to is provided at its free, outer end with a needle [3 for cooperation with a phonograph record I5.
  • a block of damping material ll such as rubber or Viscalo'id', is interposed between the rod portion 96 and the arm H, and the strip or pad of similar damping material 9 is applied to the diaphragm 3'.
  • FIG 6- there is shown a microphone utilizing an electronic transducer as above described.
  • This microphone has a casing 21 within which the shell or vessel 1 is supported by means of a supporting block 23.
  • has an opening 25: therein; over which is mounted an acoustic diaphragm 21"for vibration in response to sound The diaphragm 21.
  • the rod or bar 9, including its anode portion 9a is of cylindrical form.
  • the anode portion 9a of the bar 9 constitutes a cantilever bar with respect to the diaphragm 3 on which it is supported.
  • the resonant frequency of a wedge shaped bar vibrating in a direction parallel to the two parallel sides of the wedge, as illustrated in Figures 10a and 10b, is given by the equation
  • the mass referred to the free, inner end of the anode portion 9a of the bar is termed the effective mass.
  • the effective mass of a cylindrical bar 9a with the base as a fulcrum is the total mass of the bar.
  • the effective mass of a conical bar with the base as a fulcrum is The effective mass of a conical bar with the base as a fulcrum is 1/10 the total mass of the bar.
  • theeeffective mass of the conical bar is V the effective massofa cylindricalbar.
  • the advantage of makingthe rod portion 9 conical will be readily-apparent.
  • Other tapered bars, such as those of Figures 9a, 10aand 11a also'offer a marked advantage over the cylindrical bar of Figure 7a and the rectangular bar of Figure 8a.
  • the conical bar or rod of Figure 12a provides best results.
  • my invention j permits arranging the envelope l of the transducer horizontally (that is, with theaxisof the diaphragm .3 horizontally) and this inturn, permits a reduction 'in the vertical dimensionsof the pick-up'arm II.
  • rs and 03 represent, respectively, the mass, the mechanical resistance and the compliance of the diaphragm -3; and 1124 and 'rrrepresent, respectively, the mass'ofthe pick-up arm I land the resistance at the pivot 3 I.
  • FIG 17 there isashown another form of microphone employing-atransducer in accordance with my present invention.
  • the microphone of Figure 1'7 is generally similar to that shown in Figure .6 except thatathe'case" 2 I is here provided with a second opening 31 in its front wall adjacent the opening 25 and with an inwardly-directed tube 39 leading from the-opening '31.
  • the opening 31 and tube 39 provide a small port or vent which introduces an additional degree of freedom and makes it possible "to accentuate the response at the low frequency portion of the selected frequency range, and at the same time to obtain a sharp,;low:frequency--cut-ofl.
  • Figure 18 shows an electric wiring diagram which is the analogue of the mechanical system of the microphone of Figure 17.
  • the two driving forces F1 and F2 are equal and opposite in phase.
  • the addition of this network introduces a phase shift of such magnitude that both F1 and F2 contribute in driving the mechanical system.
  • An electronic microphone of this type is an exitremely simple device. It consists of the electronic transducer, a sound wave responsive diahragm, and the case. For this reason, the cost should be very low.
  • a microphone of this type would be suitable for sound reinforcing systems, public address systems, call and paging systems, outside broadcast pick-up, amateur radio, home recording, and many other uses. Because of its low cost and its high output, an electronic microphone Of this sort is advantageous for general sound applications, particularly since a microphone of this sort can be made to have the same sensitivity as the carbon microphone but without the disadvantages of high distortion, carbon packing and variation of response with orientation inherent in the carbon microphone, while at the same time possessing the good articulation characteristic of dynamic or magnetic microphones.
  • An electronic transducer comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, and a plurality of electrodes therein one of which is fixed and is adapted to emit electrons and another of which joins and is mounted on said diaphragm and extends therefrom in a direction generally parallel to said one electrode in spaced relation thereto, said other electrode being of tapered configuration in the direction of extension from the diaphragm and being movable toward and away from said one electrode upon flexure of said diaphragm.
  • An electronic transducer comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, and a plurality of elec trodes therein one of which is adapted to emit electrons and another of which is of tapered configuration .and is mounted on said diaphragm at its largest cross section, said other electrode extending in a direction generally parallel to that of said one electrode in spaced relation thereto and being movable toward and away from said one electrode upon flexure of said diaphragm.
  • An electronic transducer comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, and a plurality of electrodes therein one of which is adapted to emit electrons and another of which is mounted on said diaphragm for movement toward and away from said one electrode upon flexure of said diaphragm to thereby control the flow of electrons toward itself, said other electrode comprising a conical member extending in a direction generally parallel to that of said one electrode in spaced relation thereto.
  • An electronic transducer comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, and a plurality of electrodes therein one of which is adapted to emit electrons and another of which is mounted on said diaphragm for movement toward and away from said one electrode upon flexure of said diaphragm to thereby control the flow of electrons toward itself, said other electrode comprising a conical member extending in a direction generally parallel to that of said one electrode in spaced relation thereto and being connected to said diaphragm at its base.
  • An electronic transducer characterized in that said other electrode is of gradually converging taper in a direction away from said diaphragm.
  • An electronic transducer according to claim 2 characterized in that said other electrode comprises a wedge-shaped member.
  • An electronic transducer characterized in that said other electrode extends through said diaphragm, and characterized by the addition of means coupled to the portion of said other electrode which is external to said vessel for imparting vibrations to said other electrode upon application of forces to said means.
  • An electronic transducer comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, a first electrode therein adapted to emit electrons, at second electrode therein of tapered configuration secured at its base to said diaphragm and extending inwardly z ceaawm I i? from: said diaphragmz generally in?
  • a thin flexible diaphragm-providing-c10 sure means 'sealing'jsaidopening
  • a tapered'cont'ro'l electrode fiXedatdt'sbase-tb 'saiddiaphragmand extending 2? inwardly: therefrom: 1m spaced: relatien to: said catne'de element?
  • sald' control electrode having-am extenswm element secured to said diaphragm ex;- te'r'n'allyfofz'said-lsh'ell for imparting movement toa, said control el ectrodei with respect to; the fused electrode in response to an applied force of.. a magnitude to flex said diaphragm, said control electrode and extension thereof having a rela'-- tively low; momentofinertia 1 about the: connect tion with the diaphragm: and, at relatively small REFERENCES GIT-ED fol-lowing; references-2* aver of: record?- im the files of: patent-3 UNITED STATES? PATENTS Number Name Date:

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
US706967A 1946-10-31 1946-10-31 Electronic transducer Expired - Lifetime US2491390A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL71653D NL71653C (en, 2012) 1946-10-31
FR954725D FR954725A (en, 2012) 1946-10-31
US706967A US2491390A (en) 1946-10-31 1946-10-31 Electronic transducer
GB28496/47A GB647152A (en) 1946-10-31 1947-10-24 Improvements in electronic transducers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US706967A US2491390A (en) 1946-10-31 1946-10-31 Electronic transducer

Publications (1)

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US2491390A true US2491390A (en) 1949-12-13

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US706967A Expired - Lifetime US2491390A (en) 1946-10-31 1946-10-31 Electronic transducer

Country Status (4)

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US (1) US2491390A (en, 2012)
FR (1) FR954725A (en, 2012)
GB (1) GB647152A (en, 2012)
NL (1) NL71653C (en, 2012)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2666200A (en) * 1950-11-30 1954-01-12 Rca Corp Electronic transducer tube
US2680779A (en) * 1949-05-06 1954-06-08 Rca Corp Communication compensation system for atmospheric pressure variation
US2809520A (en) * 1954-03-01 1957-10-15 Jr Joseph D Richard Fluid velocity measuring apparatus
US2974274A (en) * 1955-12-13 1961-03-07 Lindberg Secondary-emission cathode-ray tube and engine analyzer employing the same
US2983790A (en) * 1953-04-30 1961-05-09 Rca Corp Electronic sound absorber

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2142857A (en) * 1935-05-24 1939-01-03 Gen Electric Vacuum tube
US2165981A (en) * 1936-08-27 1939-07-11 Julian E Sampson Electronic phonograph pick-up

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2142857A (en) * 1935-05-24 1939-01-03 Gen Electric Vacuum tube
US2165981A (en) * 1936-08-27 1939-07-11 Julian E Sampson Electronic phonograph pick-up

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2680779A (en) * 1949-05-06 1954-06-08 Rca Corp Communication compensation system for atmospheric pressure variation
US2666200A (en) * 1950-11-30 1954-01-12 Rca Corp Electronic transducer tube
US2983790A (en) * 1953-04-30 1961-05-09 Rca Corp Electronic sound absorber
US2809520A (en) * 1954-03-01 1957-10-15 Jr Joseph D Richard Fluid velocity measuring apparatus
US2974274A (en) * 1955-12-13 1961-03-07 Lindberg Secondary-emission cathode-ray tube and engine analyzer employing the same

Also Published As

Publication number Publication date
NL71653C (en, 2012)
FR954725A (en, 2012) 1950-01-05
GB647152A (en) 1950-12-06

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