US2732908A - brittain - Google Patents

brittain Download PDF

Info

Publication number
US2732908A
US2732908A US2732908DA US2732908A US 2732908 A US2732908 A US 2732908A US 2732908D A US2732908D A US 2732908DA US 2732908 A US2732908 A US 2732908A
Authority
US
United States
Prior art keywords
diaphragm
loudspeaker
frequency
response curve
frequency response
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
Other languages
English (en)
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.)
Publication date
Application granted granted Critical
Publication of US2732908A publication Critical patent/US2732908A/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
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/12—Non-planar diaphragms or cones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/12—Non-planar diaphragms or cones
    • H04R7/122—Non-planar diaphragms or cones comprising a plurality of sections or layers

Definitions

  • This invention relates to loudspeakers having a conical diaphragm. It is to be understood that in this specification the term conical includes frustoconical and the term cone includes a frustum of a cone.
  • Such loudspeakers in general exhibit a main resonance at some frequency within the upper part of the normal frequency range of the loudspeaker. It has been found that this resonance is due to one particular mode of vibration of the diaphragm which is controlled solely by the characteristics of the diaphragm and is not affected by other parts of the loudspeaker. This may be explained in the following manner. Consider a narrow sector of the diaphragm extending from its apex to its base. This sector may be considered as being held on pivots at both ends, and if the inner end is vibrated at an appropriate frequency the sector can be made to resonate, the resonant frequency depending upon the length, mass and stiffness of the sector.
  • a conventional diaphragm in the form of a right circular cone may be considered as being composed of a number of such sectors, all identical and having the same resonant frequency in the fundamental mode, and the loudspeaker will therefore exhibit a promincnt peak in its frequency response curve at this frequency.
  • a loudspeaker has a conical diaphragm of a single material which is indented at three (and only three) places in the outer half of the diaphragm, two of the indentations being disposed close to each other and the third being disposed diametrically opposite the gap between the other two.
  • Figures 1(a) and 1(1)) are explanatory diagrams
  • Figure 2 is a sectional View of part of a 6" moving coil loudspeaker having a conical metal diaphragm
  • Figure 3 is an end elevation of the diaphragm of the loudspeaker shown in Figure 2, the view being in the direction indicated by the arrow A in Figure 2.
  • a 6" moving coil loudspeaker having a metal diaphragm in the form of a right circular cone and of conventional construction has a frequency response curve similar to that shown in Figure 1(a) of the accompanying drawings in which frequency in cycles per second is plotted as abscissa and the relative response of the loudspeaker in decibels is plotted as ordinate.
  • a very prominent peak in the frequency response curve occurs at a frequency of about 8.5 kilocycles per second.
  • the construction shown in Figures 2 and 3 of the drawings is adapted for the diaphragm of the loudspeaker.
  • the diaphragm 1 of the loudspeaker is generally in the form of a right circular metal cone having an axial length of 1%" and a conical angle of the diaphragm 1 being welded to a former 2 carrying the voice coil 3, which is mounted in a gap in the magnetic circuit 4.
  • the diaphragm 1 is distorted in the following manner from its conical form at three regions in the outer half of the diaphragm 1.
  • an incision is made through the diaphragm 1 extending along a circle which is spaced approximately /2 along the slant height of the diaphragm 1 from the outer periphery of the diaphragm 1; two of the incisions have a length of 1 7 and are spaced apart along the circle, while the third incision is disposed diametrically opposite the gap between the first two incisions and has a length of A3.
  • the free edges formed on the inner sides of the incisions are pushed out into the interior of the diaphragm 1 to form louvres 5, 6 and 7, the louvre 5 formed in the region of the short incision having a length of along the slant height of the diaphragm 1, and the louvres 6 and 7 formed in the regions of the long incisions having lengths of 1 along the slant height of the diaphragm 1.
  • This distortion has the effect of increasing the stiffness of the diaphragm 1 in the regions of the louvres 5, 6 and 7 as compared with the rest of the diaphragm 1, and thus the diaphragm 1 is composed of a number of sectors some of which have resonant frequencies in the fundamental mode which differ appreciably from the resonant frequencies in the fundamental mode of others of the sectors.
  • the louvres 5, 6 and 7 are disposed asymmetrically around the axis of the diaphragm 1, although the diaphragm 1 is bilaterally symmetrical about the diametric plane represented by the line B in Figure 3, that is the plane corresponding to the section of Figure 2.
  • the louvres 5, 6 and 7 should be made comparativelyrigid. This may be achieved by ensuring that the freeedges of the louvres 5, 6 and 7 are not in the form of simple arches, but are in the form of curves whose cur-- vatures are in opposite directions at different points along;
  • the frequency response curve shown in Figure 1(a) exhibits a dip at a frequency of about 2.5 kilocycles per second.
  • the loudspeaker is provided with a rigid plug 8 in accordance with co-pending patent application No. 312,111, filed September 29, 1952, now Patent No. 2,706,529, issued April 19, 1955, the plug 8 being secured by means of a screw 9 to the part 10 of the magnetic circuit disposed inside the former 2 so as to be disposed within the space bounded by the diaphragm 1.
  • the plug 8 is in the shape of two coaxial circular cylinders 11 and 12 joined by a right circular conical part 13. As specified in said Patent No.
  • the plug 8 should extend from the vicinity of the apex of the diaphragm 1 so as to occupy between 10% and 20% of the space bounded by the diaphragm 1, at least that portion of the plug 8 which is nearest I .3 the apex of the diaphragm '1 having a surface disposed close "to the diaphragm 1.
  • the plug 8 may be of any convenient material, for example wood, metal or one of the materials commonly known as plastics.
  • the loudspeaker has a frequency response curve similar to that shown in "Figure 1(5), and it can be seen that both the peak and the dip in .the frequency response curve have been substantially eliminated, so that the frequency response curve is substantially flat within the range of frequencies extending from 50 cycles per second to 10 kilocycles per second.
  • a loudspeaker having a conical diaphragm of some non-metallic material such as paper may be treated in a similar manner .to that described above.
  • the resonance in the mode described above is not only one which occurs within the upper part of the normal frequency range of the loudspeaker; however this resonance produces the main peak in the high frequency portions of the frequency response curve of the loudspeaker, and the use of the invention enables a considerable flattening of this portion of the frequency response curve to be effected.
  • a loudspeaker having a conical diaphragm of a single material which is indented at only three places in the outer half of the diaphragm, two of the indentations being disposed close to each other and the third being disposed diametrically opposite the gap between the other-two.
  • a loudspeaker having a conical diaphragm of a single material which is indented at only three places in the outer half of the diaphragm, two of the indentations being disposed close to .each other and the third being disposed diametrically opposite the gap between the other two, and the indentations being in the form of louvres the free edges of which are in the form of curves whose curvatures are in opposite directions at different points along their lengths.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
US2732908D 1951-12-05 brittain Expired - Lifetime US2732908A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB28558/51A GB722270A (en) 1951-12-05 1951-12-05 Improvements in or relating to loudspeakers having a conical diaphragm

Publications (1)

Publication Number Publication Date
US2732908A true US2732908A (en) 1956-01-31

Family

ID=10277516

Family Applications (1)

Application Number Title Priority Date Filing Date
US2732908D Expired - Lifetime US2732908A (en) 1951-12-05 brittain

Country Status (5)

Country Link
US (1) US2732908A (fr)
DE (1) DE940996C (fr)
FR (1) FR1067372A (fr)
GB (1) GB722270A (fr)
NL (1) NL90604C (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3009528A (en) * 1956-07-24 1961-11-21 Magneti Marelli Spa Electro-acoustical device for reproducing low pitch notes
US3742493A (en) * 1971-12-06 1973-06-26 Edwards Co Audible signal apparatus
EP2506599A3 (fr) * 2011-03-28 2014-01-22 Suzhou Sonavox Electronics Co., Ltd. Diaphragme utilisé dans un haut-parleur et haut-parleur
US10194245B1 (en) * 2017-07-28 2019-01-29 Bose Corporation Acoustic transducer with vibration damping

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1288146B (de) * 1962-10-31 1969-01-30 Siemens Ag Elektroakustischer Wandler

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1298290A (en) * 1916-05-02 1919-03-25 Thomas Chalmers Diaphragm for talking-machines.
US1743767A (en) * 1927-04-13 1930-01-14 Focht Nevin Seasholtz Sound-reproducing diaphragm
US1916223A (en) * 1932-02-12 1933-07-04 Bell Telephone Labor Inc Sound translating device
US1917309A (en) * 1931-04-10 1933-07-11 Siemens Ag Diaphragm for acoustic apparatus
US2022060A (en) * 1934-08-29 1935-11-26 Bell Telephone Labor Inc Acoustic device
US2124597A (en) * 1934-01-31 1938-07-26 Rca Corp Acoustic device
US2657758A (en) * 1949-03-31 1953-11-03 Varnet Pierre Loud-speaker

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE592373C (de) * 1931-04-10 1934-02-08 Telefunken Gmbh Grossflaechenmembran, die durch ueberdeckte Aussparungen zwischen Mitte und Rand in Zonen verschiedener Eigenschwingungszahl aufgeteilt ist
US1990409A (en) * 1932-02-19 1935-02-05 Neville Athol Ernest Acoustical diaphragm
US2115924A (en) * 1935-10-05 1938-05-03 Magnavox Co Acoustic apparatus
US2531634A (en) * 1945-01-11 1950-11-28 Athol E N Lawrance Acoustical diaphragm with stiffening means
FR928176A (fr) * 1946-05-15 1947-11-20 Membrane pour haut-parleurs dynamiques

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1298290A (en) * 1916-05-02 1919-03-25 Thomas Chalmers Diaphragm for talking-machines.
US1743767A (en) * 1927-04-13 1930-01-14 Focht Nevin Seasholtz Sound-reproducing diaphragm
US1917309A (en) * 1931-04-10 1933-07-11 Siemens Ag Diaphragm for acoustic apparatus
US1916223A (en) * 1932-02-12 1933-07-04 Bell Telephone Labor Inc Sound translating device
US2124597A (en) * 1934-01-31 1938-07-26 Rca Corp Acoustic device
US2022060A (en) * 1934-08-29 1935-11-26 Bell Telephone Labor Inc Acoustic device
US2657758A (en) * 1949-03-31 1953-11-03 Varnet Pierre Loud-speaker

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3009528A (en) * 1956-07-24 1961-11-21 Magneti Marelli Spa Electro-acoustical device for reproducing low pitch notes
US3742493A (en) * 1971-12-06 1973-06-26 Edwards Co Audible signal apparatus
EP2506599A3 (fr) * 2011-03-28 2014-01-22 Suzhou Sonavox Electronics Co., Ltd. Diaphragme utilisé dans un haut-parleur et haut-parleur
US10194245B1 (en) * 2017-07-28 2019-01-29 Bose Corporation Acoustic transducer with vibration damping
US10462572B2 (en) 2017-07-28 2019-10-29 Bose Corporation Acoustic transducer with vibration damping
US10462573B2 (en) 2017-07-28 2019-10-29 Bose Corporation Acoustic transducer with vibration damping

Also Published As

Publication number Publication date
GB722270A (en) 1955-01-19
FR1067372A (fr) 1954-06-15
NL90604C (fr)
DE940996C (de) 1956-03-29

Similar Documents

Publication Publication Date Title
US2978702A (en) Antenna polarizer having two phase shifting medium
US3073411A (en) Acoustical apparatus
US2650985A (en) Radio horn
JPS6228919B2 (fr)
US2732908A (en) brittain
US1870417A (en) Diaphragm
US1930915A (en) Acoustic device
US2355568A (en) Vibration damped panel
WO2020074955A1 (fr) Antenne cornet à double polarisation avec diagramme de rayonnement asymétrique
US3955055A (en) Dynamic loudspeaker
US3130811A (en) Loudspeaker cone suspension
US2549091A (en) Diaphragm for electroacoustic transducers
US2657758A (en) Loud-speaker
US4465160A (en) Horn speaker
US2845135A (en) Auxiliary wave propagating and directing attachment for loudspeaker diaphragms
US2706529A (en) Loudspeaker having a conical diaphragm
US2785397A (en) Annular lens antenna
US2928092A (en) Electromagnetic lens
US2734591A (en) Loudspeaker structure
US3465362A (en) Shell-type luneberg lens
US2565069A (en) Loud-speaker of the double diaphragm type
US1488565A (en) Porous damper for acoustical instruments
US1917309A (en) Diaphragm for acoustic apparatus
US2714659A (en) Broad band unidirectional antenna
US2621311A (en) Mechanical movement