US2166326A - Method of damping vibratory members - Google Patents

Method of damping vibratory members Download PDF

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Publication number
US2166326A
US2166326A US87205A US8720536A US2166326A US 2166326 A US2166326 A US 2166326A US 87205 A US87205 A US 87205A US 8720536 A US8720536 A US 8720536A US 2166326 A US2166326 A US 2166326A
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US
United States
Prior art keywords
lead
damping
reed
coating
spring
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
US87205A
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English (en)
Inventor
Robert R Riesz
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 US87205A priority Critical patent/US2166326A/en
Priority to GB16279/37A priority patent/GB493160A/en
Priority to FR823556D priority patent/FR823556A/fr
Application granted granted Critical
Publication of US2166326A publication Critical patent/US2166326A/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
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 

Definitions

  • This invention relates to a method of damp ing vibratory members and more particularly to a method of mechanically damping such members by means of a deposition of lead thereon.
  • the object of the present invention is to provide a means for controlling the damping of various vibratory members.
  • Another object of the invention is to provide a means for reducing troublesome noise radiating from various parts of moving machinery or other apparatus.
  • Fig. 1 shows a partial cross-sectional view of a telephone receiver to the diaphragm of which lead coating has been applied;
  • Fig. 2 is a diagram illustrating the effectiveness of the lead coating in damping out excessive vibration of the diaphragm of a telephone receiver
  • Fig. 3 shows a vibratory reed with lead coatings applied thereto for the most efficient damping effect
  • Fig. 4 is a diagram illustrating the damping effect obtained in connection with a reed of the character disclosed in Fig. 3;
  • Fig. 5 shows the application of the invention to the springs of a relay.
  • Lead is unique among the metals in that its coefficient of internal friction is very high com- '10 pared to other metals while its Youngs modulus is quite low. This property is shown in the following table, in which several metals commonly used for vibratory members have been listed.
  • lead is in a class different from other common metals not only with respect to its elastic constants but with respect 25 to its density.
  • lead may be described as a material of moderately high density, low Youngs modulus and very high coefficient of internal friction.
  • Fig. 1 discloses a partial sectional view of a telephonev receiver to the diaphragm of which a lead coating has been applied.
  • the receiver shell is shown at I, the upper end of which is threaded to receive the receiver cap 2.
  • Clamped between the end of the shell and cap is a diaphragm 3 which is positioned just above the pole-pieces 4 of an electromagnet.
  • the outer edge of the upper surface of the diaphragm is coated with a ring of lead or other material having high dissipation, low elastic constants and high density.
  • the ring 'of lead should have a width equal to approximately half of the radius of the diaphragm and a thickness equal to approximately half of the thickness of the diaphragm.
  • the response curves of telephone receivers usually have small pronounced peaks in the voice frequency range due to the resonance of the diaphragm. For example, there is a sharp peak in the curve at frequencies between 800 and 1000 cycles due to the first normal mode of vibration of the diaphragm and a smaller peak at frequencies between 2700 and 3000 cycles due to the second normal mode of vibration of the diaphragm. This is illustrated by the full line curve shown in Fig, 2.
  • the high peak at the lower frequencies is undesirable since it makes the receiver too efiicient in a narrow frequency range and the lower peak at the higher frequencies is of little use since it is too high in frequency to merge with the low frequency range of the receiver to extend the useful frequency band.
  • the application of the lead ring to the diaphragm as previously described damps the low frequency peak but leaves its frequency almost unchanged and moves the low frequency peak to a lower frequency so that it will merge with the
  • the lead coating is indicated at 8 as applied to both faces. of the reed.' Mathematical calculations indicate that the damping effect of the lead coatings is a maximum for a given thickness of lead when the reed is coated, for one-half of its length extending from the clamped end. This is due to the fact that when lead is applied near the clamped end'a large amount of dissipation is introduced and very little mass is added, while if the lead is applied at the free end of the reed little dissipation is obtained but a large mass is added.
  • thedamping effect first rises, passes through a maximum and then decreases.
  • the resonant frequency of the reed so treated changes in a similar manner, the frequency for the reed covered with lead being lower than that when there is no leadapplied.
  • the resonant frequency is equal to that when no lead has been applied to the reed. This then furnishes a convenient methfrequency, obtained experimentally with a steel reed when both faces of the reed are lead coated to various distances from the clamped end.
  • Fig. 5 the invention is illustrated as applied to the springs of a relay, the core and winding of the relay being omitted in order to clarify thedisclosure.
  • the armature ii is secured by reed hinges M to the member l3 which with the spring pileup is clamped to the bracket M by the screws 05.
  • the armature at its free end is provided with a stud iii of insulating materialv which passes freely through an opening in the lower spring it into engagement with the middle spring 88.
  • the lower and upper springs l1 and B9 are supported near their free ends in the usual manner in the proper position with respect to the center spring It by the outer spoolhead incated at 20.
  • this spring does not function as a true reed and the most effective damping of this spring is attained by coating that portion of the spring which has the maximum potential energy, or approximately the outer half 75 of the spring extending back from its contacts to its clamped end.
  • the invention also embraces other substances having similar characteristics.
  • a rigid support a reed spring clamped at one end to said support, and means for mechanically damping said spring comprising a coating of lead applied to both surfaces of said spring between its clamped and free 2 ends, the free end of said spring being uncoated.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Vibration Prevention Devices (AREA)
  • Percussion Or Vibration Massage (AREA)
US87205A 1936-06-25 1936-06-25 Method of damping vibratory members Expired - Lifetime US2166326A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US87205A US2166326A (en) 1936-06-25 1936-06-25 Method of damping vibratory members
GB16279/37A GB493160A (en) 1936-06-25 1937-06-11 Improvements in or relating to mechanically damped vibratory members
FR823556D FR823556A (fr) 1936-06-25 1937-06-24 éléments vibrants

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US87205A US2166326A (en) 1936-06-25 1936-06-25 Method of damping vibratory members

Publications (1)

Publication Number Publication Date
US2166326A true US2166326A (en) 1939-07-18

Family

ID=22203722

Family Applications (1)

Application Number Title Priority Date Filing Date
US87205A Expired - Lifetime US2166326A (en) 1936-06-25 1936-06-25 Method of damping vibratory members

Country Status (3)

Country Link
US (1) US2166326A (fr)
FR (1) FR823556A (fr)
GB (1) GB493160A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2488608A (en) * 1941-10-09 1949-11-22 Rca Corp Signal translating apparatus and supporting means therefor
US2499210A (en) * 1946-12-31 1950-02-28 Rca Corp Film drive filter
US2689105A (en) * 1950-07-08 1954-09-14 Gen Electric Resilient mount
US2745508A (en) * 1952-09-11 1956-05-15 Dictograph Products Co Inc Microphone support
US2952827A (en) * 1956-11-13 1960-09-13 Edcliff Instr Electric contact
US3060282A (en) * 1957-07-26 1962-10-23 Baldwin Piano Co Electroacoustic transducer
DE976256C (de) * 1954-07-21 1963-05-30 Philips Nv Piezoelektrische Kristallplatte mit Daempfungsschicht
US3093710A (en) * 1959-07-06 1963-06-11 Gulton Ind Inc Piezoelectric electromechanical transducer

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2488608A (en) * 1941-10-09 1949-11-22 Rca Corp Signal translating apparatus and supporting means therefor
US2499210A (en) * 1946-12-31 1950-02-28 Rca Corp Film drive filter
US2689105A (en) * 1950-07-08 1954-09-14 Gen Electric Resilient mount
US2745508A (en) * 1952-09-11 1956-05-15 Dictograph Products Co Inc Microphone support
DE976256C (de) * 1954-07-21 1963-05-30 Philips Nv Piezoelektrische Kristallplatte mit Daempfungsschicht
US2952827A (en) * 1956-11-13 1960-09-13 Edcliff Instr Electric contact
US3060282A (en) * 1957-07-26 1962-10-23 Baldwin Piano Co Electroacoustic transducer
US3093710A (en) * 1959-07-06 1963-06-11 Gulton Ind Inc Piezoelectric electromechanical transducer

Also Published As

Publication number Publication date
GB493160A (en) 1938-10-04
FR823556A (fr) 1938-01-22

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