EP0066027A1 - Membran, insbesondere für einen elektroakustischen Wandler - Google Patents

Membran, insbesondere für einen elektroakustischen Wandler Download PDF

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Publication number
EP0066027A1
EP0066027A1 EP81400870A EP81400870A EP0066027A1 EP 0066027 A1 EP0066027 A1 EP 0066027A1 EP 81400870 A EP81400870 A EP 81400870A EP 81400870 A EP81400870 A EP 81400870A EP 0066027 A1 EP0066027 A1 EP 0066027A1
Authority
EP
European Patent Office
Prior art keywords
membrane
loudspeaker
methyl
motor
elastomer
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.)
Withdrawn
Application number
EP81400870A
Other languages
English (en)
French (fr)
Inventor
Philippe Lesage
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.)
Audax Industries SA
Original Assignee
Audax Industries SA
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 Audax Industries SA filed Critical Audax Industries SA
Publication of EP0066027A1 publication Critical patent/EP0066027A1/de
Withdrawn legal-status Critical Current

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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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2307/00—Details of diaphragms or cones for electromechanical transducers, their suspension or their manufacture covered by H04R7/00 or H04R31/003, not provided for in any of its subgroups
    • H04R2307/029—Diaphragms comprising fibres

Definitions

  • the present invention relates to the nature of the material used in the membranes of electro-acoustic transducers. It relates particularly to transducers such as a voice coil type speaker, in which the membrane is coupled with an electromechanical transducer.
  • the membranes of electro-acoustic transducers are for the most part made of paper pulp agglomerated by a binder whose solvent, such as water, is evaporated either under hot pressure (membranes called pressed) or slowly in air (membranes say dried).
  • the speed C m of the vibratory waves propagating in the material of the membrane and responsible for the sound emission does not exceed 200 m / s.
  • the internal damping of the vibratory waves in the material also called linear weakening, is low and leads to a mechanical overvoltage factor Q of between 15 and 30.
  • the defects found on pulp membranes, or on those made of another material having a Q of the order of 20 to 30, come from the specific resonances of the membrane material, the amplitude of which is proportional to the Q of the material.
  • a membrane may be made of polypropylene, or by extension, of materials based on polypropylene, or even, more generally, of any material for which the mechanical overvoltage factor Q, the Young's modulus and the density f satisfy the following inequalities:
  • a polypropylene membrane in a loudspeaker makes it particularly efficient, and we thus obtain sound reproduction qualities further improved compared to those of the Bextrene + Plastiflex membrane, due to the fact that the Young's modulus E is higher in polypropylene.
  • the electro-acoustic efficiency of a such speaker is also improved. It is thus possible to produce a loudspeaker provided with a polypropylene membrane which has an additional efficiency of the order of 6 dB compared to a Bextrene + Plastiflex membrane.
  • polypropylene has very poor mechanical resistance when it is brought to a temperature above 60 ° C.
  • the present invention therefore aims to provide an electro-acoustic transducer membrane for which in particular the parameters, such as the Young's modulus, the speed of the vibratory waves and the mechanical overvoltage factor, are more optimized than for known materials. cited above.
  • an electro-acoustic or acousto-electric transducer membrane is characterized in that all or part of the material of which it is made is the methyl pentene polymer of formula: with low proportion of elastomer.
  • This elastomer is preferably of the EPDM type copolymer type.
  • the good mechanical resistance of the membrane material according to the invention allows it to be used without problem on power loudspeakers whose driving coil can be brought to a relatively high temperature.
  • the low value of the mechanical overvoltage factor Q due to the excellence of the internal damping of the material, ensures the sound reproduction of an electro-acoustic transducer equipped with a TPX membrane with great neutrality by the fact that the amplitude of deformation of the natural modes of this membrane is reduced.
  • the drag of the loudspeaker according to the invention is also reduced to a great extent.
  • a speaker specialized in the reproduction of low frequencies. It comprises a membrane 1 which is frustoconical with a straight generator, as illustrated, or with a generator along a conic such as a hyperbola or parabola, or even generator in exponential, even even arbitrary.
  • the membrane 1 according to the invention is made of a material composed all or part of a methyl pentene polymer, or of a methyl pentene copolymer containing a small proportion of elastomer.
  • the term "material” according to the invention "a material as defined above or in claim 1.
  • the small base of the membrane 1 is terminated by a cylindrical section 10, of short length, which is suitably glued to the front of the cylindrical support or mandrel 20 of the voice coil 21 of the electro-mechanical motor 2. This bonding does not require particularly a special glue
  • the rear part of the support 2 supports the turns of the coil 21 housed in the middle of the air gap 22 of the magnetic circuit of the motor 2.
  • the magnetic circuit consists of a pole piece before discord 23 resting on a permanent magnet annular 24, itself placed on a magnetized plate 25.
  • the core 26 of the magnetic circuit is partly coaxial with the pole piece 23 and the magnet 24 and is / internal to the support 20 of the voice coil 21.
  • the frustoconical frame or bowl 3 of the loudspeaker rests coaxially on the pole piece 23.
  • Two or more end and intermediate suspensions can connect the membrane 1 to the frame 3 to center the latter. They can be of "material according to the invention".
  • the external 11 and internal 12 suspensions are only shown in FIG. 1.
  • the external suspension 11 connects the upper front end of the membrane to the chassis 3.
  • the internal suspension 12 connects the small rear cylindrical section 10 of the membrane 1 to the small base of the chassis 3. These latter connections are made by bonding.
  • a dust cover dome 13 closes the front opening of the motor 2, that is to say the front of the support 20 of the coil 21.
  • This dust cover dome 13 can also be made of "material according to the invention”.
  • Fig. 2 shows a speaker specialized in the reproduction of medium and high frequencies. It comprises a membrane 4 of "material according to the invention" which is in the form of a hemispherical dome. In general, this dome of revolution can be of rectilinear, circular, analogous to a conical or any other generator. The rear portion of the membrane is terminated by a small cylinder 40 which is glued around the front of the support 50 of the voice coil 51 of the motor 5 of the loudspeaker. In a similar manner to the motor 2 described above, the motor 5 according to FIG.
  • the 2 also comprises a pole piece 53 surrounding the coil 51, an annular permanent magnet 54 resting on a magnetized plate 55 and a core 56 coaxial with the magnet 54 and forming an air gap 52 with the pole piece 53.
  • the coil 51 is immersed centrally in the air gap 52.
  • the perforated front part of the chassis 6 of the loudspeaker rests on the pole piece 53 by means of an annular spacer 60.
  • the membrane 4 is centered above the spacer 60 by means of an annular suspension 41 in "material according to the invention".
  • the inner and outer peripheral edges of the suspension 41 are respectively glued to the cylindrical rear section 40 of the membrane 5 and braced and clamped between the frame 6 and the spacer 60.
  • Under the membrane 4 and above the core 56 is provided a felt acoustic 43, also domed.
  • Fig. 3 shows a loudspeaker having a diaphragm 7 in the form of a dihedral, and of "material according to the invention".
  • This loudspeaker operates in a very wide frequency band covering, in general, the entire audible frequency band. It is of the type disclosed in French patent application No. PV. 78 - 32 386 filed Nov. 16, 1978, on behalf of the present plaintiff.
  • the membrane 7 is tensioned under a high tensile preload and is rigid or flexible before assembly.
  • the two front ends 81 of the two rectangular or square flat surfaces forming the dihedral are rigidly fixed to a rectangular or square front frame 90 of the chassis of the loudspeaker.
  • the open dihedral front part of the membrane 7 can be developed along rectilinear generators, of exponentials, analogous to a portioryconic, or indeed any. In order not to overload Fig. 3, the chassis has only been shown in part.
  • the flat rear surface 70 shown in rectangular form, is made of "material according to the invention".
  • This rear surface 70 is coplanar with the vertical plane of symmetry X I X of the dihedral, extends towards the rear the edge 73 of the dihedral and is symmetrically embedded in the air gap 82 of the motor 8, here with a symmetrical structure.
  • the rear edge 700 of the surface 70 is connected to a rear upright 91 of the chassis by means of a wavy suspension, initially rigid or elastic, 72 which is substantially coplanar with the plane X'X.
  • the suspension 91 can also be made of "material according to the invention".
  • An adjustment device - not shown - allows the suspension 72 to be anchored to the chassis in order to move the membrane 7 and suspension 72 assembly longitudinally and, consequently, to adjust the tensile preload of the membrane 2.
  • two rigid or initially elastic suspensions can be provided to connect the two ends 81 of the dihedral front part to the front frame 90, by means of the adjustment device, and the rear edge 700 can be fixed rigidly and directly to the rear upright 91.
  • the motor 8 of the loudspeaker shown in FIG. 3 comprises a movable assembly consisting of a flat coil 81, rectangularly spiraled, obtained by screen printing or by winding and bonding of a wire of rectangular section on the faces of the rear surface 70 of the membrane 7.
  • the conductive tapes 810 forming the long sides of the turns of the coil 81 are the only generators of an induction in the magnetic circuit of the motor 8. They are perpendicular to the direction of the small displacements of the membrane 7 and centered in the two air gaps 82 magnetized opposite the motor 8.
  • the ends of the internal and external turns of the coil are welded to two supply wires 811 of the coil 81.
  • the conductive strips 812 forming the short sides of the turns of the coil 81 are parallel to the movement of the coil between the air gaps 82 and simply serve as a current return.
  • the fixed part of the motor 8 - half of which is shown in FIG. 3 - comprises for example two parallelepiped magnets 84 which are arranged symmetrically on either side of the plane X'X and which are braced by two pairs of flat pole pieces 83.
  • the large conductive tapes 810 of the coil 81 are inserted centrally in the two air gaps 82 formed by the four pole pieces 83.
  • the whole of the fixed part dj motor 8 is fixed inside a double frame rectangular central 92 of the speaker chassis.
  • the "displacements" of the coil 81 are very small and require “displacements” of the diaphragm 7 belonging to the field of macro-deformations so that the diaphragm 7 is the seat of mainly transverse shocks directly generating an acoustic pressure in the air with a virtual absence of displacement of the membrane 7.
  • an electrodynamic microphone of the voice coil type can comprise a membrane made of "material according to the invention".
  • the motor and diaphragm are similar to those of the dome diaphragm speaker as shown in Fig. 2.
  • the suspension of the microphone diaphragm intended to center the diaphragm relative to the axis of symmetry of the microphone motor can also be formed. into a "material according to the invention”.
  • Table A mentioned above in the present description is given below.
  • the first four lines relate to materials constituting known membranes and the last line to the methyl pentene polymer defined under the registered trademark "TPX".
  • the values noted in Table A correspond to typical average values and are subject to variation, especially with regard to paper pulp.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
EP81400870A 1979-12-05 1981-05-29 Membran, insbesondere für einen elektroakustischen Wandler Withdrawn EP0066027A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7929886A FR2471113A1 (fr) 1979-12-05 1979-12-05 Membrane notamment pour transducteur electro-acoustique

Publications (1)

Publication Number Publication Date
EP0066027A1 true EP0066027A1 (de) 1982-12-08

Family

ID=9232421

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81400870A Withdrawn EP0066027A1 (de) 1979-12-05 1981-05-29 Membran, insbesondere für einen elektroakustischen Wandler

Country Status (2)

Country Link
EP (1) EP0066027A1 (de)
FR (1) FR2471113A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4760295A (en) * 1985-04-17 1988-07-26 Geoquip Security Systems Ltd. Vibration-sensitive transducer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2522912B1 (fr) * 1982-03-03 1986-08-14 Audax Suspension peripherique en elastomere de la membrane d'un transducteur electro-acoustique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1095303A (de) *
FR2345048A1 (fr) * 1976-03-19 1977-10-14 Harwood Hugh Membrane de transducteur electro-acoustique
JPS5345226A (en) * 1976-10-04 1978-04-22 Matsushita Electric Ind Co Ltd Acoustic vibrating plate
WO1980001128A1 (fr) * 1978-11-16 1980-05-29 Audax Transducteur electro-acoustique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1095303A (de) *
FR2345048A1 (fr) * 1976-03-19 1977-10-14 Harwood Hugh Membrane de transducteur electro-acoustique
JPS5345226A (en) * 1976-10-04 1978-04-22 Matsushita Electric Ind Co Ltd Acoustic vibrating plate
WO1980001128A1 (fr) * 1978-11-16 1980-05-29 Audax Transducteur electro-acoustique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENTS ABSTACTS OF JAPAN, Vol. 2, No. 79, 23 Juin 1978, page 3352 E 78 & JP-A-53 045 226 (Matsushita Denki Sangyo K.K.) 22-04-1978 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4760295A (en) * 1985-04-17 1988-07-26 Geoquip Security Systems Ltd. Vibration-sensitive transducer

Also Published As

Publication number Publication date
FR2471113B1 (de) 1982-10-08
FR2471113A1 (fr) 1981-06-12

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19821223

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Effective date: 19840822

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Inventor name: LESAGE, PHILIPPE