[go: up one dir, main page]

US2149628A - Telephone transmitter - Google Patents

Telephone transmitter Download PDF

Info

Publication number
US2149628A
US2149628A US40738A US4073835A US2149628A US 2149628 A US2149628 A US 2149628A US 40738 A US40738 A US 40738A US 4073835 A US4073835 A US 4073835A US 2149628 A US2149628 A US 2149628A
Authority
US
United States
Prior art keywords
transmitter
cell
diaphragm
electrodes
cup
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
US40738A
Other languages
English (en)
Inventor
Harold C Pye
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.)
Associated Electric Laboratories Inc
Original Assignee
Associated Electric Laboratories Inc
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 Associated Electric Laboratories Inc filed Critical Associated Electric Laboratories Inc
Priority to US40738A priority Critical patent/US2149628A/en
Priority to GB21822/36A priority patent/GB479469A/en
Priority to FR810939D priority patent/FR810939A/fr
Application granted granted Critical
Publication of US2149628A publication Critical patent/US2149628A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • FIG4A F'IGAB.
  • This invention relates-in general to telephone transmitters but more particularly to transmitters of the type employing carbon granulated material in the microphone cell and the broad object of the invention is to provide a transmitting unit particularly adapted for use in the handset type of instrument employed with the cradle type of telephone.
  • the principal object of the invention is to design a transmitter unit that will operate to transmit speech in; a. highly satisfactory manner regardless of the position-in which the unit is h d by the handset when in use.
  • a transmitter depends for its performance upon the movement of the diaphragm causing a resistance change in the microphone cell proportional to the movement. A given movement of the diaphragm will cause acertain percent change of the micro- V (i) Atransmitter unit which. is able to give" several years of normal telephone service without phone resistance. It is therefore obvious that g the higher the microphone cell resistance, the greater will be the common battery line resistance change and in a circuit the more sensitive will be the transmitter. Contrary to this, however; the higher the transmitter resistance, thehigher will be the voltage across the microphone cell. The heat generated at the points of contact of the carbon granules in the cell is proportional to the square of the voltage between them This heating causes thermal agitation of the granules and if great enough will be heard as a frying or,
  • the fidelity of transmitters can, however, be much improved by the proper balancing of the resonant frequency of the diaphragm, the acoustical chambers in front and in back of the diaphragm together with the proper amount of damping, without a sacri fice of volume efliciency
  • Electrodes have been formed as cones of various angles, hemispheres, cylinders, and many other geometrical forms, with the purpose of maintaining contact between the granules and the electrodes in all of the different positions. Other designs involve immersing the electrodes in the granules so that contact is maintained between them in all the different positions. This is the type most commonly used commercially in transmitters at the present time.
  • the movement of the diaphragm is most effective'in compressing the granules near the top of thehemisphere where the surface is most nearly at right angles to the direction of motion or compression of the granules.
  • the sides of the hemisphere are almost parallel to the direction of motion and are therefore almost inactive. This inactive portion of the cell acts as an electrical shunt resistance on the active portion of the granules.
  • FIG. 1 shows a side cross sectional view through the center of the transmitter unit
  • Fig. 2 is a rear view of the transmitter
  • Fig. 3 is an exploded perspective view of theelements comprising the microphone cell andthe diaphragm
  • Figs. 4, 4A, 4B, 40 and-4D illustrate various shaped electrodes that maybe used
  • Figs. 5 to 9 illustrate a number of graphs diagrammatically indicating performance characteristics of. the transmitter unit made according to the invention.
  • Fig.v i of The form is's'uch that it can be used interchangeably with either the handset type of transmitter unit or the rigid desk stand type.
  • housing l is cup-shaped and is arranged to support the various members and parts of .the complete transmitter unit.
  • An aluminum face plate 2 having a number of openings 3 arranged in a
  • the various shaped mouthpieces and supports which may be circular pattern for the purpose of permitting the speech waves to reach the diaphragm, is placed in the flange 6 of housing #1.
  • a thin edge 1 around the flange 6 is then spun over on the edge of face plate 2 to hold it firmly in place in the housing i.
  • the (groove 5 cut in the periphery of face plate 2 enables a sort of springing action to be applied to plate 2 when the edge d is pressed down and spun over on the face plate and a A tighter fit to be brought about.
  • the moving system comprising the diaphragm is made of extremely light material such as thin directly on the flange of diaphragm l to the inside of the housing l.
  • Behind the main diaphragm '1 lies a secondary diaphragm E9 in the shape of a conical ring having an opening in the center thereof.
  • the secondary diaphragm it has a' dome shaped cup H inserted through its opening which is provided with a flanged portion l4 resting against the edge of the opening.
  • the eyelet I2 has an opening l 3, the'purpose of which will be later on described.
  • a ring shaped electrode [5 constructed of solid shaped cupll by turning up-or spinning over the edge of the flange [4 on the electrode, thereby securely holding the electrode in its set position.
  • the moving electrode I5 is thereby rigidly fasdiaphragm Tl are clamped by the face plate '2 carbon-is fastened tothe flange I4 of the dome v tened to the diaphragm system and moves with it as a unit.
  • the moving electrode is a fixed ring shaped carbon electrode it of the same shape as the moving electrode i5.
  • This bellows may be attached by means of a coating of varnish or-other adhesive to the edges of the electrodes.
  • the paper bellows ll it provides a means so that as the moving system of the diaphragm is vibrated air is forced through the. folds of the paper bellows ll between the outside'of the microphone cell and the chamber in back of the diaphragm, thus slightly damping or controlling the vibrations of the diaphragm.
  • the resonance chamher in front of the diaphragm l and moisture proof covering 9 and behind the face plate 2 provides a further damping means for the moving v system.
  • the dome shaped member At the rear end of the dome shaped member it there is provided an opening whereby the micro- 3!? is threaded into the opening and then the head of the plug is sheared or twisted 01f, precluding the possibility thereafter of unauthorized tampering with the parts comprising the microphone cell.
  • the clamping ring 23 in addition to holding the dome shaped member l8 insulatingly clamped to the housing l directly-clamps the terminal member 27! to it.
  • the terminal member I diaphragm I and electrode 15.
  • Screw 25 trade Hi. It has the holding screw 25 threaded I serves as the attaching means for the outgoing .wire.
  • the electrical circuits for the microphone cell extend from the attaching wire on screw 25.
  • the microphone cell is purposely constructed in the form described and illustrated so that pressure due to the force of gravity on the granules at the electrode surfaces is very nearly equal for any position in which the cell is placed when in use. For the reason that the pressure is not transmitted as well in a horizontal direction between flat surfaces, the electrodes 15 and [6 have been formed as narrow rings, and the horizontal direction of pressure flow is thus made very short. To assist further in the transmission of pressure between the electrodes the'inner edge of them has been beveled at a small angle. In Fig. 4
  • the improvement in the transmitter according to the invention is quite considerable. It responds up to about 4500 cycles frequency and has a total variation in the response of only about 12.5 decibels up to that frequency, thereby providing an increased range of operation and considerable better performance.
  • the resistance of the transmitter microphone cell was measured with the handset position changed to various angles as indicated in Fig. 6.
  • the resistance limits for the transmitter are 29 to 3'7 ohms indicating a very small change of resistance compared with previous types of transmitters which vary from 30 to ohms with changes of position.
  • breathing is a periodical variation of transmitter resistance due to the expansion of air in the microphone cell and of the cell walls by the action of heat which is generated by the passage of current through the cell.
  • the so-called carbon noise is the chief limitation to current carrying capacity of a transmitter.
  • a handset transmitter will receive rather rough treatment in service, such as dropping on the cradle or on a table, moving about while in use, and placing in a horizontal position on the cradle just before being used; This all tends to make the transmitter become noisy when in use.
  • the transmitter according to the invention was designed to have a lower resistance in all positions than previous types did.
  • an artificial ageing cycle was performed by a machine that simulated the condition of removing the transmitter from the cradle and raising it to the talking position and then dropping it on the cradle, the current arcades:
  • the resistance I and noise level of the transmitter reaches a fairly constant value after about 10,000 operations.
  • the resistance and noise are less after 20,000 operations of the transmitter of the invention than older types of handset transmitters were at approximately only 1,000 operations. 20,000 ageing operations would be practically the equivalent of ten years of service with about five operations a day.
  • This graph indicates that the ageing of the transmitter carbon granules due to shock has been elimiated to a large extent by the new design.
  • the use of the anti-side-tone telephonesubstation circuit efiectively prevents howling or excessive side tone'when a handset is connectedto the line.
  • a telephone is used on a short line loop and before the called party answers the line circuit is virtually open. Under these conditions any side tone circuitis not balanced and in some casesthe handset may tend to sing or howl. Although this does not usually take place during conversation it is nevertheless annoying.
  • the transmitter of'the invention as indicated in the graph of Fig. '7 the relatively fiat responseirequency curve of the transmitter greatly reduces this tendency to howl and sing.
  • the very light moving system of the transmitter likewise reduces the mechanical couplingbetwe'en it and the receiver in the handset.
  • This transmitter can therefore be used on any type of circuit, side tone or anti-side tone without self-oscillations im-
  • the transmitter can therefore be immersed in Water for a considerable length of time without any impairment in its performance.
  • a dome-shaped cup secured'to the apex of said diaphragm, a conical ring clamped between the outer edge of said cup and said diaphragm, and an electrode secured tothe outer edge of said cup.
  • a diaphragm comprising two conical-shaped members having their peripheries incontact, a cup memberhaving its bottom secured to' the apex of one of said conical members and its edges in contact with the other'of said from a V 5 members, and an electrode secured to the edge of said cup member.
  • a microphone cell including two cup' shaped members oppositely disposed, an electrodem'ounted on the edge of each of said cup members, a flexible member conmeeting said electrodes together and enclosing said microphone cell, and a diaphragm attached to the base of one of said cup members.
  • a pairof oppo sitely disposed dome-shaped members forming a microphone cell, a flange around the edges of each of said members and an electrode supported by the flange on each of said members.
  • a diaphragm comprising a pair of oppositely disposed conical shaped members,'a dome-shaped cup member clamped at its bottom 'to one of said conical members and in engagement with the other-oi said conical members-at the periphery of the cup, a housing for said diaphragm, means in said housing for clamping said diaphragm at its periphery, said diaphragm being flexible near its clamping periphery while remaining entirely rigid point near the periphery to its center and including said cup member.
  • granulated carbon material filling said cell, and means for preventing the escape of the carbon granules from said cell while at the same time permitting current through'said granules between said electrodes.
  • a diaphragm comprising two conical members having their peripheries abutting, a microphone cell having one end attached to the apex of one of said conical members and the other end to an opening in the other conical member, and an electrode fastened to said microphone cell adjacentthe openingin said other conical member.
  • a transmitter diaphragm comprising a pair .of conical members with their peripheries in abutment and their apexes extending in opposite directions and a portion of a microphone cell formed between said apexes.
  • a transmitter diaphragm comprising a pair of conical members having their peripheries in extending away-from one another to fonna hollow. space between said members, and a portion of a microphone cell disposed in said space.
  • a pair of hemispherical shaped members having their open edges spaced opposite one another forming amicrophone cell, resistance material in said cell, means for insulating the walls of said cell from said resistance material, an electrode supported on the edges of each of said hemi-spherical members, flexible means extending between said electrodes, a diaphragm supporting one of said hencl spherical members at its base, and a rigid support for the other of said members.
  • a pair of hemlspherical shaped members arranged with their open edges spaced opposite one another and defining a microphone cell, a circular electrode supported on the edge of each of said members, resistance material in said cell, and means in sulating the cell walls of said members to confine the current flow through said resistance material and between said electrodes.
  • a microphone cell comprising a pair of cup-shaped members having their open edges facing each other and the bottoms of the cups extending in opposite directions, a ring-shaped electrode supported around the edge of each of said cup members, insulating material on the cell walls of said cup members for. confining the current flow between said electrodes, means for rigidly supporting one of said cup members, and a diaphragm for movably supporting the other cup member.
  • a microphone cell In a telephone transmitter, a microphone cell, a pair of electrodes in said cell, a diaphragm supporting one of said electrodes and movable therewith, means for rigidly supporting the other electrode, resistance material in said cell, means for confining the current flow through said cell between the electrodes and the resistance mate'rial, one end of said cell and said diaphragm having an opening therein for equalization of air pressure between the inside and outside of said. microphone cell.
  • a microphone cell filled with resistance material, a diaphragm attached to one end of said cell, said cell and said diaphragm having openings in alignment therein extending from the inside to the outside of the cell to maintain the air pressure constant within the cell when in use, said opening being of a size to prevent the escape of the resistance material from said cell.
  • a microphone cell In a telephone transmitter, a microphone cell, a diaphragm, a movable and a rigid electrode spaced apart in said cell, said movable electrode attached to said diaphragm and movable therewith under the action of sound waves impinging against said diaphragm, resistance material in said cell, an air passage extending from the inside of said cell to the side of the diaphragm receiving the sound waves, said air passage enabling the equalization of air pressure between the inside of the cell and the outside of said diaphragm to prevent the undesired movement of the movable electrode caused by the cell expansion.
  • conical diaphragm conical diaphragm, a conical protective disc, a face plate having a conical surface, said protective disc arranged between said diaphragm and said face plate so that the conical surfaces of each element are in nested formation, said conical elements having extended flat surfaces parallel to eachother forming their clamping peripheries, said face plate securely clamping said protective disc and said diaphragm to said casing at said peripheri$ in such a manner that a narrow space is provided around their adjacent conical surfaces.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Telephone Set Structure (AREA)
  • Measuring Fluid Pressure (AREA)
US40738A 1935-09-16 1935-09-16 Telephone transmitter Expired - Lifetime US2149628A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US40738A US2149628A (en) 1935-09-16 1935-09-16 Telephone transmitter
GB21822/36A GB479469A (en) 1935-09-16 1936-08-07 Improvements in or relating to microphones
FR810939D FR810939A (fr) 1935-09-16 1936-09-14 Perfectionnements aux microphones

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US40738A US2149628A (en) 1935-09-16 1935-09-16 Telephone transmitter

Publications (1)

Publication Number Publication Date
US2149628A true US2149628A (en) 1939-03-07

Family

ID=21912660

Family Applications (1)

Application Number Title Priority Date Filing Date
US40738A Expired - Lifetime US2149628A (en) 1935-09-16 1935-09-16 Telephone transmitter

Country Status (3)

Country Link
US (1) US2149628A (fr)
FR (1) FR810939A (fr)
GB (1) GB479469A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2567368A (en) * 1949-06-09 1951-09-11 Bell Telephone Labor Inc Telephone transmitter
US2572525A (en) * 1947-08-06 1951-10-23 Siemens Ag Albis Microphone with carbon electrodes
US2967914A (en) * 1955-06-02 1961-01-10 Automatic Elect Lab Telephone transmitter

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2572525A (en) * 1947-08-06 1951-10-23 Siemens Ag Albis Microphone with carbon electrodes
US2567368A (en) * 1949-06-09 1951-09-11 Bell Telephone Labor Inc Telephone transmitter
US2967914A (en) * 1955-06-02 1961-01-10 Automatic Elect Lab Telephone transmitter

Also Published As

Publication number Publication date
GB479469A (en) 1938-02-07
FR810939A (fr) 1937-04-02

Similar Documents

Publication Publication Date Title
US2042822A (en) Telephone transmitter
US2149628A (en) Telephone transmitter
US2340777A (en) Throat microphone
US1422877A (en) Acoustical aid for deaf persons
US1383700A (en) Acoustic device
US1702410A (en) Microphone
US1565581A (en) Telephone transmitter
Jones Instruments for the new telephone sets
US2257303A (en) Carbon cell
US1231095A (en) Telephone-transmitter.
US1863322A (en) Telephone pay station
US2847520A (en) Damped microphone
US1578489A (en) Microphone
US732284A (en) Telephone-transmitter.
US1297905A (en) Telephone-transmitter.
US1480218A (en) Submarine signaling
US1198345A (en) Telephone-transmitter.
US2239308A (en) Microphone amplifier
US380752A (en) Telephone-transmitter
US1588627A (en) Loud-speaking telephone
US2179733A (en) Microphone
US737345A (en) Telephone test instrument.
US1665045A (en) Telephone receiver
US252641A (en) Compound telephone
US1490750A (en) Reproducing and transmitting device