US1854812A - Telephone receiver - Google Patents

Telephone receiver Download PDF

Info

Publication number
US1854812A
US1854812A US505825A US50582530A US1854812A US 1854812 A US1854812 A US 1854812A US 505825 A US505825 A US 505825A US 50582530 A US50582530 A US 50582530A US 1854812 A US1854812 A US 1854812A
Authority
US
United States
Prior art keywords
diaphragm
earpiece
sound
casing
telephone receiver
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
US505825A
Inventor
John C Steinberg
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.)
AT&T Corp
Original Assignee
Bell Telephone 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 Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US505825A priority Critical patent/US1854812A/en
Application granted granted Critical
Publication of US1854812A publication Critical patent/US1854812A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01HMEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H3/00Measuring characteristics of vibrations by using a detector in a fluid
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S181/00Acoustics
    • Y10S181/40Wave coupling

Definitions

  • An object of this invention is to measure noise in a simple and novel manner. Another object. of this invention is to conduct noise and other vibrations to the ear of an observer and thereat to combine the vibrations,
  • the path of the noise or other vibrations being through the earpiece of the receiver.
  • a further object is to combine at the ear of an observer sound wavesfrom. different sources, the paths for the sound waves being distinct and separate but terminating in close proximity.
  • the path for the noise is through a chamber in the earpiece which is concentric preferably to that of the diaphragm tone sound path at the center of the earpiece, a sound translating diaphragm being positioned in the chamher and adapted to be actuated by a listening or sounding stick.
  • a preferred embodiment of this invention takes the form of a telephone receiver provided with an earpiece adapted to be secured to the receiver casing and having a plane surface portion in spaced relation to the means securing it to the casing. To the outer peripheralportion of the plane surface portion is secured a ring member having a recess therein within which the periphery of a sound translating diaphragm is secured,
  • a sounding or listening stick one extremity of which is adapted to be placed against a source of noise disturbances, is attached at its other extremity to the diaphragm.
  • Fig. 1 is a side view of one embodiment of this invention. partially in section;
  • Fig. 2 is an exploded view of the embodiment of this invention shown in Fig. 1;
  • Fig. 3 is a side view partially in section of a modification of the embodiment of this invention shown in Fig. 1;
  • Fig. 4 is a plan view of the,embodiment of this invention shown in Figs. 1 and 2.
  • the telephone receiver to which this invention is applicable I comprises generally a casing 1 housing a permanent magnet (not shown), a pair of pole pieces 2, 2 and a diaphragm 3 disposed in attractable relation to said pole pieces.
  • This diaphragm is held in position on the casing l by a clamping ring 4 having, preferably, a plane surface 5 and an interiorly threaded aperture 6.
  • the receiver earpiece 7 comprises an earpiece portion 8 adapted to be placed adjacent the ear of an observer or user of the telephone receiver and having a concave front or upper surface 9 and a plane rear surface 10.
  • the portion 8 has a central opening 11 irregular in contour for a purpose hereinafter to be disclosed.
  • Extending into the opening 11 is an annular member 12 provided with a cylindrical portion 13, having a centrally disposed passage 14 and an'externally threaded flange or disc portion 15 adapted to engage with the interiorly threaded aperture 6 of the clamping ring i.
  • the upper extremity 16 of the cylindrical portion 13 is tapered to engage with the reversely tapered portion 17 of surface 10 about the opening 11 whereby a plurality of openings 18 in spaced relation to the passage 14 are formed, the irregularity in contour of the opening 11 being such, preferably, thatthese openings 18 are arcuately shaped.
  • the member 12 is attached to the earpiece portion 8 preferably by screws 19 (one only being shown) extending'through the drillings 20 in the disc portion 15 and threading into tapped bushings 21 in the projections 22 which maintain'the member 12 in proper space relation to the earpiece portion f ll shown) to the peripheral portion of the rear surface 10 is an annular member 24 from which a portion has been removed and which provides a seat for the periphery of 21.
  • diaphragm 25 which may be of metal or of wood and having a central opening 26.
  • the screws 23 extend through openings 27 in said annular member and the periphery of the diaphragm 25 and thread into tapped drillings 28 in the earpiece portion 8.
  • the earpiece 7 When assembled and in engagement with the telephone receiver, the earpiece 7 cooperates with the casing 1 of said receiver to form a sound chamber 31 within which is disposed the diaphragm 25, the chamber having outlets therefrom comprising the arcuately shaped openings 18.
  • vibrations from a vibrating body may be picked up by placing the capped end of the listening or sounding stick thereagainst, conducted to the diaphragm 25 in the chamber 31 setting the diaphragm and confined air therein into vibration-to translate the vibrations picked up which, as sound waves, pass out through the openings 18 to the ear of the observer who si multaneously listens to a tone produced by the vibration of the receiver diaphragm 3, said tone reaching the ear through a central sound path provided by the passage 14.
  • This diaphragm tone may be obtained by connecting the telephone receiver in a circuit such as is disclosed in U. S. Patent 1,673,037, issued June 12, 1928 to D. G.
  • the intensity of the tone may be varied by the operator until the noise sounds picked up just mask the diaphragm tone.
  • the position of the sounding-stick on the vibrating body the nature and distribution of the vibrations may be completely studied.
  • FIG. 3 themodification of the embodiment of this invention shown il'l Figs. 1 and 2 differs therefromih that the earpiece portion 8 is'formed with'an annular peripheral flange portion 32 and the clamping ring 4 is provided with a flange portion 33 providing an annular seat 34 for the diaphragm 25 which is here held between the flanges ofthe earpiece and the clamping ring.
  • the earpiece portion 8 is'formed with'an annular peripheral flange portion 32 and the clamping ring 4 is provided with a flange portion 33 providing an annular seat 34 for the diaphragm 25 which is here held between the flanges ofthe earpiece and the clamping ring.
  • flange portions 32 and 33 are suitably grooved at that point where the listening or sounding stick is attached to the diaphragm 25.
  • the invention described herein is capable of a variety of uses, for instance, in certain mechanical systems where there are moving parts, the noise may be such as to cause considerable annoyance to either the user or the people in proximity thereto. This is particularly true in the higher class automobiles ing, an earpiece, a plurality of diap where noiselessness of operation is a very desirable characteristic and one of the problems which automotive engineers are continually striving to, solve. Engine noises, bearing noises, body noises and the like may be studied and measured utilizing this invention and the information acquired used to correct undesirable noise or vibration conditions.
  • this invention is applicable to the study of noises or of other sounds or vibrations originating in mechanical devices but it is apparent that, with slight modifications, it may be 'used in studying noises or vibrations of the human body, for instance, in the region of the heart and of the lungs. It is to'be understood, therefore, that although this invention has been disclosed with reference to what are believed to be preferred embodiments there- .of, it is to be construed as limited bytheapways therein, and a plurality of sound transla-ting diaphragms, one of said diaphragms being 'located within said earpiece and another exterior to said earpiece, the sound waves translated by said diaphragms having passage through the passageways in said earplece.
  • a telephone receiver comprising :1 casing, an earpiece, a plurality of diap' ragms, said earpiece having a sound passageway leadingfrom each diaphragm, electromagnetic means for actuating one of said diaphagms, and mechanical means for actuating another of said diaphragms.
  • a telephone receiver comprising a casing, an earpiece, means for securin said C88. ing and said earpiece together, an a plurality ofsound translating diaphragms, one of which is located in said earpiece and another of which is located between said securing means and the casing.
  • a telephone receiver comprising a casragms, one of said diaphragms being located in said earpiece and another associated with said casing, mechanical means for actuating said one diaphragm, and electromagnetic means for actuating another of said-diaphragms.
  • a telephone receiver comprising'a casing, an earpiece having a pluralit of sound wave passageways therein, a plura ity of diaphragms, one of said diaphragms being positioned in said earpiece, means for vibrating said one diaphragm, a second of said diaphragms being positioned between said earpiece and casing, and means in said casing tc actuate said second diaphragm, the sounc' waves translated by each ofsaid diaphragm: passing-through separate paths.
  • a telephone receiver comprising a cas ing, an earpiece having a plurality of soum wave passageways whose outlets are in prox imity,'a plurality of diaphragms, the sound Waves translated by any one of said dia- 1 phragms passing through one only of said.
  • a telephone receiver comprising a casing, an earpiece having aplurality of sound wave passageways, the outlets of which are 7 in proximity, two diaphragms, one of said diaphragms being positioned in said earpiece, mechanical means to actuate said one diaphragm, the other diaphragm being supported by said casing, and means for electrically actuating said diaphragm.
  • a telephone receiver having a casing, a. diaphragm, a clamping ring for holding said diaphragm in place on said casing, means for actuating said diaphragm, an earpiece having a central sound path leading from said diaphragm, a second diaphragm, said second diaphragm being located in said earpiece, means for actuating said second diaphragm, said earpiece having a sound wave passageway therein leading from said second diaphragm and having its outlet in proximity to the outlet of said central sound path.
  • a telephone receiver comprising a casing, a diaphragm, an earpiece having a sound path at its center, means for securing said earpiece to said casin said earpiece and said means providing an annular chamber concentric with said sound path, said chamber being provided with an outlet in proximity to the outlet of said sound path,
  • said means comprising a listening stick and a second diaphragm, said listening stick at one extremity to be placed against a vibrating body, the sound vibrations in which are to be examined, and attached at 1ts other extremity to said second diaphragm which is positioned in said chamber.
  • a telephone receiver a casing, a diaphragm, means for actuating said diaphragm, an earpiece having a sound path leading from said diaphra means to secure said earpiece to said casing, saidearpiece and a said means forming a sound chamber having an outlet in proximity to the outlet of said sound path, a second diaphragm positioned 1n said sound chamber, and means to actuate said second diaphragm.
  • an earpiece having a sound path leadmg from said diaphragm, means to secure said earpiece to said casing, said earpiece and said means forming a sound chamber having an outlet in proximity to the outlet of said sound path a second diaphragm positioned in said sound chamber, and means to actuate said second diaphragm,
  • phragm Ina telephone receiver, phragm, electrical means diaphragm, leading from said diaphragm, means for securing said earpiece to said casing, said means and said earpiece forming a sound chamber, said chamber having an outlet opening therefrom adjacent the outlet of said sound path, a diaphragm in said sound chamber, and mechanical means to actuate said last mentioned diaphragm.
  • a casing a dia- P path leading from said diaphragm, means for securing said earpiece to said casing, said earpiece having a flat surface in spaced relation to said means, an annular member secured to said surface at its peripheral portion, and with said earpiece and said first means forming a sound chamber having an outlet in proximity to the outlet from said central sound path, a second diaphragm, said second diaphragm supported in said chamber by said annular member, and a listening stick attached at one extremity to said second diaphragm.

Description

April 1932. J. c. STEINBERG 1,854,812
TELEPHONE RECEIVER Filed Dec. 31, 1930 FIG. .3 25 J 8 INVENTOR y J. CSTE/NBERG ATTORNEY as sound waves, with sound waves produced Patented Apr. 19, 1932 JOHN C. STEINBEBG, 0F SPARTA, NEW JERSEY, ASSIGNOR TO BELL TELEPHONE LAB- ORATORIES, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE RECEIVER Application filed December 31, 1930. Serial No. 505,825.
for use in connection with apparatus formeasuring noise.
An object of this invention is to measure noise in a simple and novel manner. Another object. of this invention is to conduct noise and other vibrations to the ear of an observer and thereat to combine the vibrations,
by a telephone receiver, the path of the noise or other vibrations being through the earpiece of the receiver.
A further object is to combine at the ear of an observer sound wavesfrom. different sources, the paths for the sound waves being distinct and separate but terminating in close proximity.
According to this invention, the noise, the
intensity of which is to be measured, and certain diaphragm tones are received simultaneously in the ear of the observer from respective paths in the receiver earpiece' The path for the noise is through a chamber in the earpiece which is concentric preferably to that of the diaphragm tone sound path at the center of the earpiece, a sound translating diaphragm being positioned in the chamher and adapted to be actuated by a listening or sounding stick.
A preferred embodiment of this invention takes the form of a telephone receiver provided with an earpiece adapted to be secured to the receiver casing and having a plane surface portion in spaced relation to the means securing it to the casing. To the outer peripheralportion of the plane surface portion is secured a ring member having a recess therein within which the periphery of a sound translating diaphragm is secured,
the diaphragm being thereby supported in av sound chamber formed by the earpiece, ring and securing means. A sounding or listening stick, one extremity of which is adapted to be placed against a source of noise disturbances, is attached at its other extremity to the diaphragm.
A more complete understanding of this invention will be obtained from the following detailed description and by reference to the appended drawings, wherein: V
Fig. 1 isa side view of one embodiment of this invention. partially in section;
Fig. 2 is an exploded view of the embodiment of this invention shown in Fig. 1;
Fig. 3 is a side view partially in section of a modification of the embodiment of this invention shown in Fig. 1; and
Fig. 4 is a plan view of the,embodiment of this invention shown in Figs. 1 and 2.
Referring now to the drawings and more particularly to Figs. 1 and 2, the telephone receiver to which this invention is applicable I comprises generally a casing 1 housing a permanent magnet (not shown), a pair of pole pieces 2, 2 and a diaphragm 3 disposed in attractable relation to said pole pieces. This diaphragm is held in position on the casing l by a clamping ring 4 having, preferably, a plane surface 5 and an interiorly threaded aperture 6. The receiver earpiece 7 comprises an earpiece portion 8 adapted to be placed adjacent the ear of an observer or user of the telephone receiver and having a concave front or upper surface 9 and a plane rear surface 10.
The portion 8 has a central opening 11 irregular in contour for a purpose hereinafter to be disclosed. Extending into the opening 11 is an annular member 12 provided with a cylindrical portion 13, having a centrally disposed passage 14 and an'externally threaded flange or disc portion 15 adapted to engage with the interiorly threaded aperture 6 of the clamping ring i. The upper extremity 16 of the cylindrical portion 13 is tapered to engage with the reversely tapered portion 17 of surface 10 about the opening 11 whereby a plurality of openings 18 in spaced relation to the passage 14 are formed, the irregularity in contour of the opening 11 being such, preferably, thatthese openings 18 are arcuately shaped. The member 12 is attached to the earpiece portion 8 preferably by screws 19 (one only being shown) extending'through the drillings 20 in the disc portion 15 and threading into tapped bushings 21 in the projections 22 which maintain'the member 12 in proper space relation to the earpiece portion f ll shown) to the peripheral portion of the rear surface 10 is an annular member 24 from which a portion has been removed and which provides a seat for the periphery of 21. diaphragm 25, which may be of metal or of wood and having a central opening 26. The screws 23 extend through openings 27 in said annular member and the periphery of the diaphragm 25 and thread into tapped drillings 28 in the earpiece portion 8. Attached to the diaphragm is a listening or sounding stick 29 of metal or of wood projecting through the cut away portion of the annular member 24: and whose free extremity, adapted to be placed against a source of noise vibrations, may be provided with a metal cap 30.. When assembled and in engagement with the telephone receiver, the earpiece 7 cooperates with the casing 1 of said receiver to form a sound chamber 31 within which is disposed the diaphragm 25, the chamber having outlets therefrom comprising the arcuately shaped openings 18. It will be apparent that vibrations from a vibrating body may be picked up by placing the capped end of the listening or sounding stick thereagainst, conducted to the diaphragm 25 in the chamber 31 setting the diaphragm and confined air therein into vibration-to translate the vibrations picked up which, as sound waves, pass out through the openings 18 to the ear of the observer who si multaneously listens to a tone produced by the vibration of the receiver diaphragm 3, said tone reaching the ear through a central sound path provided by the passage 14.. This diaphragm tone may be obtained by connecting the telephone receiver in a circuit such as is disclosed in U. S. Patent 1,673,037, issued June 12, 1928 to D. G. Blattner, and, in accordance with the teachings of that patent, the intensity of the tone may be varied by the operator until the noise sounds picked up just mask the diaphragm tone. By varyingthe position of the sounding-stick on the vibrating body the nature and distribution of the vibrations may be completely studied.
Referring to Fig. 3 themodification of the embodiment of this invention shown il'l Figs. 1 and 2 differs therefromih that the earpiece portion 8 is'formed with'an annular peripheral flange portion 32 and the clamping ring 4 is provided with a flange portion 33 providing an annular seat 34 for the diaphragm 25 which is here held between the flanges ofthe earpiece and the clamping ring. The
flange portions 32 and 33 are suitably grooved at that point where the listening or sounding stick is attached to the diaphragm 25.
The invention described herein is capable of a variety of uses, for instance, in certain mechanical systems where there are moving parts, the noise may be such as to cause considerable annoyance to either the user or the people in proximity thereto. This is particularly true in the higher class automobiles ing, an earpiece, a plurality of diap where noiselessness of operation is a very desirable characteristic and one of the problems which automotive engineers are continually striving to, solve. Engine noises, bearing noises, body noises and the like may be studied and measured utilizing this invention and the information acquired used to correct undesirable noise or vibration conditions. Not only is this invention applicable to the study of noises or of other sounds or vibrations originating in mechanical devices but it is apparent that, with slight modifications, it may be 'used in studying noises or vibrations of the human body, for instance, in the region of the heart and of the lungs. It is to'be understood, therefore, that although this invention has been disclosed with reference to what are believed to be preferred embodiments there- .of, it is to be construed as limited bytheapways therein, and a plurality of sound transla-ting diaphragms, one of said diaphragms being 'located within said earpiece and another exterior to said earpiece, the sound waves translated by said diaphragms having passage through the passageways in said earplece.
2. A telephone receiver comprising :1 casing, an earpiece, a plurality of diap' ragms, said earpiece having a sound passageway leadingfrom each diaphragm, electromagnetic means for actuating one of said diaphagms, and mechanical means for actuating another of said diaphragms.
3. A telephone receiver comprising a casing, an earpiece, means for securin said C88. ing and said earpiece together, an a plurality ofsound translating diaphragms, one of which is located in said earpiece and another of which is located between said securing means and the casing.
4. A telephone receiver comprising a casragms, one of said diaphragms being located in said earpiece and another associated with said casing, mechanical means for actuating said one diaphragm, and electromagnetic means for actuating another of said-diaphragms.
5. A telephone receiver comprising'a casing, an earpiece having a pluralit of sound wave passageways therein, a plura ity of diaphragms, one of said diaphragms being positioned in said earpiece, means for vibrating said one diaphragm, a second of said diaphragms being positioned between said earpiece and casing, and means in said casing tc actuate said second diaphragm, the sounc' waves translated by each ofsaid diaphragm: passing-through separate paths.
6. A telephone receiver comprising a cas ing, an earpiece having a plurality of soum wave passageways whose outlets are in prox imity,'a plurality of diaphragms, the sound Waves translated by any one of said dia- 1 phragms passing through one only of said.
sound passageways, and means for actuating each of said diaphragms, one diaphragm being positioned in said earpiece and another diaphragm supported by said casing.
7. A telephone receiver comprising a casing, an earpiece having aplurality of sound wave passageways, the outlets of which are 7 in proximity, two diaphragms, one of said diaphragms being positioned in said earpiece, mechanical means to actuate said one diaphragm, the other diaphragm being supported by said casing, and means for electrically actuating said diaphragm.
8. A telephone receiver having a casing, a. diaphragm, a clamping ring for holding said diaphragm in place on said casing, means for actuating said diaphragm, an earpiece having a central sound path leading from said diaphragm, a second diaphragm, said second diaphragm being located in said earpiece, means for actuating said second diaphragm, said earpiece having a sound wave passageway therein leading from said second diaphragm and having its outlet in proximity to the outlet of said central sound path.
9. In combination, a telephone receiver comprising a casing, a diaphragm, an earpiece having a sound path at its center, means for securing said earpiece to said casin said earpiece and said means providing an annular chamber concentric with said sound path, said chamber being provided with an outlet in proximity to the outlet of said sound path,
' into said chamber,
and means for conducting sound vibrations said means comprising a listening stick and a second diaphragm, said listening stick at one extremity to be placed against a vibrating body, the sound vibrations in which are to be examined, and attached at 1ts other extremity to said second diaphragm which is positioned in said chamber.
10. In a telephone receiver, a casing, a diaphragm, means for actuating said diaphragm, an earpiece having a sound path leading from said diaphra means to secure said earpiece to said casing, saidearpiece and a said means forming a sound chamber having an outlet in proximity to the outlet of said sound path, a second diaphragm positioned 1n said sound chamber, and means to actuate said second diaphragm.
11. In a telephone receiver, a casing, a diaphragm, means for actuating said dia hragm,
an earpiece having a sound path leadmg from said diaphragm, means to secure said earpiece to said casing, said earpiece and said means forming a sound chamber having an outlet in proximity to the outlet of said sound path a second diaphragm positioned in said sound chamber, and means to actuate said second diaphragm,
said means'comprising a vibration conducting member to be placed in contact with a vibrating body.
12. Ina telephone receiver, phragm, electrical means diaphragm, leading from said diaphragm, means for securing said earpiece to said casing, said means and said earpiece forming a sound chamber, said chamber having an outlet opening therefrom adjacent the outlet of said sound path, a diaphragm in said sound chamber, and mechanical means to actuate said last mentioned diaphragm.
13. In a telephone receiver, a casing, a dia- P path leading from said diaphragm, means for securing said earpiece to said casing, said earpiece having a flat surface in spaced relation to said means, an annular member secured to said surface at its peripheral portion, and with said earpiece and said first means forming a sound chamber having an outlet in proximity to the outlet from said central sound path, a second diaphragm, said second diaphragm supported in said chamber by said annular member, and a listening stick attached at one extremity to said second diaphragm.
- In witness whereof,'I hereunto subscribe my name this 23rd day of December, 1930.
- JOHN C. STEIN BERG.
a casing, a diafor actuating said an earpiece having a sound path
US505825A 1930-12-31 1930-12-31 Telephone receiver Expired - Lifetime US1854812A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US505825A US1854812A (en) 1930-12-31 1930-12-31 Telephone receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US505825A US1854812A (en) 1930-12-31 1930-12-31 Telephone receiver

Publications (1)

Publication Number Publication Date
US1854812A true US1854812A (en) 1932-04-19

Family

ID=24011999

Family Applications (1)

Application Number Title Priority Date Filing Date
US505825A Expired - Lifetime US1854812A (en) 1930-12-31 1930-12-31 Telephone receiver

Country Status (1)

Country Link
US (1) US1854812A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2493734A (en) * 1945-05-23 1950-01-03 Sonotone Corp Magnetic insert earphone insertable in the ear of the user
US20090302042A1 (en) * 2008-06-10 2009-12-10 Lou Henry Baking tray

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2493734A (en) * 1945-05-23 1950-01-03 Sonotone Corp Magnetic insert earphone insertable in the ear of the user
US20090302042A1 (en) * 2008-06-10 2009-12-10 Lou Henry Baking tray
US7770751B2 (en) 2008-06-10 2010-08-10 Focus Products Group, Llc Baking tray
US20100313769A1 (en) * 2008-06-10 2010-12-16 Lou Henry Baking tray
USRE43839E1 (en) 2008-06-10 2012-12-04 Fpg, Llc Baking tray

Similar Documents

Publication Publication Date Title
US2122587A (en) Acoustic device
GB382268A (en) Improvements in sound translating devices, particularly loud-speakers and telephone or like transmitters
US2574591A (en) Mute structure for musical instruments
GB1011871A (en) Microphone
US1755636A (en) Loud-speaker
US2350010A (en) Microphone
US1854812A (en) Telephone receiver
US1766473A (en) Electrodynamic device
GB241277A (en) Improvements relating to diaphragms for acoustic instruments
US2537253A (en) Electrodynamic telephone receiver
US1951531A (en) Sound-translating device
US1743194A (en) Radio loud-speaker
US1356156A (en) Telephonic receiver
US2544536A (en) Microphone
US2790032A (en) Contact microphone
US1854802A (en) Telephone receiver
US1768903A (en) Sound-producing device
US1928669A (en) Transmitter
US2520714A (en) Electrodynamic hand microphone of the pressure gradient type
US1733013A (en) Sound-reproducing device
US1623561A (en) Acoustic horn
US1366607A (en) Telephone-receiver
US1876306A (en) Diaphragm for sound recording and reproducing devices
US707441A (en) Telephone-receiver.
US3024323A (en) Inverted loud speaker