US2532694A - Telephone transmitter having frustoconical back electrode - Google Patents

Telephone transmitter having frustoconical back electrode Download PDF

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Publication number
US2532694A
US2532694A US783324A US78332447A US2532694A US 2532694 A US2532694 A US 2532694A US 783324 A US783324 A US 783324A US 78332447 A US78332447 A US 78332447A US 2532694 A US2532694 A US 2532694A
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United States
Prior art keywords
frusto
electrode
electrodes
chamber
telephone transmitter
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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
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US783324A
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English (en)
Inventor
Herbert W Bryant
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AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
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Filing date
Publication date
Priority to NL70196D priority Critical patent/NL70196C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US783324A priority patent/US2532694A/en
Priority to GB28010/48A priority patent/GB651378A/en
Application granted granted Critical
Publication of US2532694A publication Critical patent/US2532694A/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
    • H04R21/00—Variable-resistance transducers
    • H04R21/02—Microphones
    • H04R21/021—Microphones with granular resistance material

Definitions

  • Transmitter units of the type to which this invention pertains comprise, in general, a carbon granule lled chamber bounded in part by a pair of electrodes one of which is coupled to a diaphragm to vibrate therewith in accordance with speech or other sound waves effective upon the diaphragm.
  • the operating characteristics of such units are dependent upon the resistance of the current path, through the carbon granules, between the two electrodes and the manner in which this resistance Varies in response to vibrations of the diaphragm.
  • the electrodes be relatively closely spaced. However, as the electrode spacing'is reduced, the tendency of the carbon granules to pack increases, with consequent degradation in the performance of the unit.
  • transmitter units when included in hand telephones are subject to operation in a variety of positions.
  • the gravitational forces upon the granules tend to vary the effective pressure between the'carbon granules and the electrodes with diiference in position of the unit, so that the operating characteristics of the unit may vary considerably with position in which the hand telephone is held.
  • One general object of this invention is to improve the operating characteristics of carbon granule type telephone transmitters.
  • objects of this invention are to improve the modulation in, prevent packing of the carbon granules in, and obtain improved l non-positional performance characteristics for telephone transmitter units of the carbon granule type.
  • the electrodes are provided with juxtaposed dished surfaces of such configuration that a portion of the space therebetween is restricted and the forces effective upon the carbon granules during operation of the unit are such' as to maintain the carbon in a free state.
  • the vibratile electrode has a substantially hemispherical convex surface and the other or fixed electrode has a frusto-conical concave surface coaxial with and in close proximity to the hemispherical surface.
  • a portion of the granule chamber is 2 bounded by a frusto-conical wall encompassing the hemispherical surface and in juxtaposition thereto, this wall extending from the frusto-conical electrode surface and being of greater slope than this surface, thereby to produce a restriction in the chamber adjacent the hemispherical surface.
  • Fig. l is a side View in section of a transmitter uni-t illustrative of one embodiment of this invention.
  • Fig. 2 is a View similar to Fig. 1 of a transmitter unit illustrative of another embodiment of this invention
  • Fig. 3 is a diagram showing to an enlarged scale, the configuration of the carbon granule chamber bounding elements in the unit illustrated in Fig. 1;
  • Fig. 4 is a fragmentary sectional View illustrating a modication of the transmitter unit shown in Fig. 1.
  • the transmitter unit illustrated in Fig. l comprises a circular frame or foundation member IQ, for example of metal, having an internal annular fiange Il and a lat annular seating surface i2. Seated upon the surface l2 is the peripheral portion I3 of a lightweight metallic diaphragm which includes a central, shallow frusto-conical part I@ provided with stiifening corrugations or ribs I5 and includes also an annular corrugation or trough portion i6 sufciently flexible to permit bodily,
  • the diaphragm together with a moisture resistant screen or membrane Il and a multi-apertured protective cap or cover i8, is secured to the frame or foundation member l0 by an annular band I9.
  • a metallic electrode having a short cylindrical base portion 2% and a hernispherical portion 2l, the electrode having also a flange 22 and integral tabs 23 between which the inner edge of the diaphragm part l is clamped. Also clamped between the fiange 22 and tabs 23 are a metallic spider 2t, which serves as a lead-in conductor for the electrode, and a flexible, annular, insulating closure member 25, for
  • the spider and closure member extending to the flange I and being held thereagainst by an insulating ring 26 having a frustoconical surface 29 coaxial with the vibratile electrode, and an arched surface 3U.
  • a back or fixed electrode 2'! is seated upon the ring 26 and is provided with a frusto-conical surface 28 coaxial with the hemispherical surface 2
  • the larger end of the surface 28 is coincident with the smaller end of the surface 29 and the slope of the former surface is less than that of the latter.
  • the electrodes are placed in close proximity to one another.
  • and 28 may be substantially .039 inch.
  • the gap between these surfaces is restricted at the region A and enlarges in both directions, i. e. toward regions B and C, from the region A.
  • This it has been found substantially prevents packing of the carbon granules between the electrode surfaces despite the close spacing thereof.
  • the granules are maintained in a free state and this, together with the close spacing, assures the realization of high modulation.
  • the maintenance of the good performance of the unit when, during use the maintenance of the good performance of the unit when, during use,
  • the diaphragm faces upwardly and is horizontal or substantially
  • the major portion of the current between the electrodes is directed along paths at and adjacent the region A in the gap between the electrodes. At these paths the forces, due to vibration of the diaphragm, for agitating the carbon granules are most effective, and distortion by current modulation in the transverse direction, i. e. substantially normal to the direction of diaphragm mtion, is minimized.
  • Distortion by such transverse modulation may be further reduced, as illustrated in Fig. 4, by heightening the frusto-conical insulating surface, thereby in effect blocking the major part of the current path normal to the axis of alignment of the two electrodes.
  • this is effected by an insulating insert 40, having a frusto-conical surface 4
  • the transmitter unit illustrated in Fig. 2 is similar to that shown in Fig. 1 and described hereinabove. However, a portion of the carbon granule chamber is bounded by a formed annular member 36, S-shaped in section and of flexible insulating material, such as silk. One end of this member is clamped between the electrode flange 22 and the diaphragm and the other end is fixed between the back electrode 2! and the annulus 3l. Because of the construction and configuration of the member 38 it will be appreciated that in use of the unit, forces tending to urge the granules into engagement with the vibratile electrode and toward the restricted space between the two electrodes are produced.
  • the current path between the two electrodes is of relatively small cross-section. Hence, a relatively high resistance may be obtained despite the close spacing of the electrodes.
  • a telephone transmitter comprising a xed and a vibratile electrode having juxtaposed dished surfaces one of which is convex and substantially hemispherical and the other of which is frusto-conical and has its larger end toward the hemispherical surface, means including said surfaces bounding a chamber, and comminuted resistance varying material in said chamber.
  • a telephone transmitter in accordance with claim l wherein said means comprises an insulating member having a frusto-conical surface encompassing said hemispherical surface and extending from and having its small end adjacent said rst frusto-conical surface, the slope of said second frusto-'conical surface being greater than that of said first frusto-conical surface.
  • a telephone transmitter comprising means including a pair of electrodes having juxtaposed surfaces, defining a chamber, comminuted resistance varying material in said chamber, and means for vibrating one of said electrodes, one of said surfaces being convex and domed and the other of said surfaces being frusto-conical and having its larger end nearer said one surface.
  • said chamber defining means comprises an insulating member encompassing said domed surface and having a frusto-conical surface in juxtaposition thereto and inclined in the same direction as and of greater slope than said concave surface.
  • a telephone transmitter in accordance with claim 3 wherein said chamber defining means comprises an annular flexible insulating member, substantially S-shaped in section, encompassing said do-med surface and extending from the larger end of said concave surface.
  • a telephone transmitter in accordance with claim 6 wherein said chamber bounding means comprises a frusto-:coni'cal insulating wall coaxial with, encompassing and spaced from said hemispherical surface, said wall being of greater slope than said frusto-conical surface and having its smaller end coincident with the larger end of said frusto-conical surface.
  • said chamber bounding means comp-risesy an annular flexible member of S- shaped section, coaxial with said hemispherical surface and extending between the said diaphragm and the larger end of said frusto-conical surface.
  • a telephone transmitter comprising means including a pair of electrodes and an insulating member between and spacing said electrodes, bounding a chamber, one of said electrodes having a domed portion and the other of said electrodes having a dished surface in juxtaposition to the convex face of said domed portion and having its base toward said domed portion, comminuted resistance varying material in said chamber, means for vibrating one of said e1ectrodes, and an annular insulating insert in said dishedsurface adjacent the end thereof nearest said domed portion.
  • a tele-phone transmitter comprising a first electrode having -a convex substantially hemispherical surface, a second electrode having a 85 2,225,438
  • a telephone transmitter comprising a pair of electrodes having juxtaposed surfaces, means including said surfaces bounding a chamber, comminuted resistance varying material in said chamber, and means for vibrating one of said electrodes, said surfaces being dished in the same direction and of different configurations such that the spacing between said surfaces is a minimum at an intermediate region and increases in both directions from said region.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Lasers (AREA)
  • Telephone Set Structure (AREA)
US783324A 1947-10-31 1947-10-31 Telephone transmitter having frustoconical back electrode Expired - Lifetime US2532694A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL70196D NL70196C (lv) 1947-10-31
US783324A US2532694A (en) 1947-10-31 1947-10-31 Telephone transmitter having frustoconical back electrode
GB28010/48A GB651378A (en) 1947-10-31 1948-10-28 Improvements in or relating to telephone transmitters

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US783324A US2532694A (en) 1947-10-31 1947-10-31 Telephone transmitter having frustoconical back electrode

Publications (1)

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US2532694A true US2532694A (en) 1950-12-05

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US783324A Expired - Lifetime US2532694A (en) 1947-10-31 1947-10-31 Telephone transmitter having frustoconical back electrode

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US (1) US2532694A (lv)
GB (1) GB651378A (lv)
NL (1) NL70196C (lv)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2607859A (en) * 1950-12-01 1952-08-19 Bell Telephone Labor Inc Telephone transmitter
DE1061825B (de) * 1954-02-26 1959-07-23 Hans Widmaier Kohlegriessmikrophon-Sprechkapsel
US3277247A (en) * 1961-03-02 1966-10-04 Siemens Ag Moisture-proof carbon microphone

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2042822A (en) * 1933-05-11 1936-06-02 Bell Telephone Labor Inc Telephone transmitter
US2191992A (en) * 1937-03-31 1940-02-27 Int Standard Electric Corp Telephone transmitter
US2225488A (en) * 1938-06-18 1940-12-17 Bell Telephone Labor Inc Impulse translating apparatus
US2404772A (en) * 1942-12-21 1946-07-30 Kellogg Switchboard & Supply Telephone transmitter
US2429988A (en) * 1943-12-28 1947-11-04 Bell Telephone Labor Inc Temperature compensated microphone

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2042822A (en) * 1933-05-11 1936-06-02 Bell Telephone Labor Inc Telephone transmitter
US2191992A (en) * 1937-03-31 1940-02-27 Int Standard Electric Corp Telephone transmitter
US2225488A (en) * 1938-06-18 1940-12-17 Bell Telephone Labor Inc Impulse translating apparatus
US2404772A (en) * 1942-12-21 1946-07-30 Kellogg Switchboard & Supply Telephone transmitter
US2429988A (en) * 1943-12-28 1947-11-04 Bell Telephone Labor Inc Temperature compensated microphone

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2607859A (en) * 1950-12-01 1952-08-19 Bell Telephone Labor Inc Telephone transmitter
DE1061825B (de) * 1954-02-26 1959-07-23 Hans Widmaier Kohlegriessmikrophon-Sprechkapsel
US3277247A (en) * 1961-03-02 1966-10-04 Siemens Ag Moisture-proof carbon microphone

Also Published As

Publication number Publication date
GB651378A (en) 1951-03-14
NL70196C (lv)

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