Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
  • H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
  • G09G5/22—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the display of characters or indicia using display control signals derived from coded signals representing the characters or indicia, e.g. with a character-code memory
  • G09G5/222—Control of the character-code memory

Definitions

• the invention relates to films or membranes for acoustic applications which must have specific vibrational properties, in particular to membranes for electromechanical transducers capable of transforming an electric current received into sound emission (loudspeakers) or conversely a sound wave received into electric current emitted. (microphones), in particular for loudspeakers, and to the process for preparing such films or membranes.
• patent FR-A-1 445 262 which describes a method of manufacturing a loudspeaker piston consisting in molding a thermosetting resin foam to the desired shape in a cooled mold and thus causing formation in the surface of said piston, of a hard skin, airtight.
• This resin foam is a polyurethane foam obtained from commercial copolymers and a polyisocyanate acting as a foaming agent.
• US Pat. No. 3,153,463 describes a loudspeaker in which the diaphragm consists of a rigid plastic foam or a rigid expanded plastic, obtained by incorporating a small quantity of a blowing agent or foaming agent in a resinous plastic material, fuse or liquid, such as a polyurethane resin.
• GB-A-1,384,716 also describes a loudspeaker whose diaphragm is made of a foam comprising a closed cell structure which is optionally coated with an aqueous emulsion resin.
• the object of the invention is precisely to provide improved films or membranes for various acoustic applications.
• said macropolymer is chosen from the group consisting of polymers of methacrylic acid, polymers of ethyl acrylate and mixtures of these two polymers.
• said macropolymer is the product designated commercially "APPRETAN 9110" consisting of a polymer based on ethyl acrylate and methacrylic acid, in relative proportions by weight: 70/30.
• polyvinyl polymers can consist of vinyl acetate polymers and vinyl alcohol polymers and more generally by any polyvinyl polymer.
• Another macropolymer which can advantageously be used in the context of the invention is cellulose or one of its derivatives.
• the gel before drying can either be impregnated on fabrics (woven or non-woven) or wicks of natural, artificial or synthetic fibers, or constitute the binder of such fibers, with the possibility of adding fillers in each case (for example carbon, ceramic, glass, and graphite).
• the material thus obtained becomes porous once dried and can advantageously be thermoformed due to the flexibility of the dried material, once heated, and the thermal adhesion of the gel or the like dried on the fabrics or strands of fibers.
• the gelling agent is ethyl acetate and the process includes another phase of evaporation, between phases a) and b ), the dispersion to which is added, in phase b), ethyl acetate then being the dispersion prepared in phase a) and having undergone this other phase of evaporation.
• the invention also relates to a porous film or membrane with improved vibratory properties for acoustic applications, in particular a loudspeaker membrane, obtained by the above-mentioned process.
• APPRETAN 9110 is an aqueous dispersion of a mixture of macropolymers based on ethyl acrylate and methacrylic acid in relative proportions by weight 70/30, with a dry extract of 32.50%. of the blend of copolymers with respect to the dispersion.
• This aqueous dispersion is diluted in water (12% dispersion in water) and ammonia is poured therein dropwise (at 22 ° Beaumé) until a gel with a viscosity of 29 poisilles is obtained. or 29 Pa.s (290 poises) which are dried with hot air causing the evaporation of water and ammonia.
• the starting point is an aqueous dispersion containing 15% polyvinyl acetate; it is placed on a nylon canvas; the water is evaporated; and the canvas thus coated is dipped in ethyl acetate.
• a gel having the consistency of honey is obtained, which is dried with hot air to produce the evaporation of the ethyl acetate.
• Example 1 in the context of Example 1, it was found that the impregnation of cut carbon fibers, on the one hand, with the product resulting from Example 1, and, on the other hand, with the same aqueous dispersion of APPRETAN 9110 not treated with ammonia results in membranes, produced from these two materials, the masses of which for equal stiffnesses are in a ratio of the order of 1 to 3.
• Example 1 For example for a membrane 17 cm in diameter, the mass in the case of the application of Example 1 is 1.75 g, while it is of the order of 2.5 to 5 g for a membrane obtained from the starting aqueous dispersion of Example 1 not treated with ammonia or produced from the materials usually used, namely paper, polypropylene or suitable composite.
• a dispersion in water at the rate of 20% of mother liquor is prepared from a mother liquor of polyvinyl acetate (dry extract of 50%).
• a woven or non-woven fabric of nylon fibers is coated or impregnated by soaking or brushing it with the diluted dispersion thus prepared.
• the canvas is dried with hot air to evaporate the water.
• the canvas is soaked in an ethyl acetate bath or brushed with such a compound.
• the ethyl acetate is evaporated, also with hot air.
• the membrane thus obtained is particularly suitable for producing an electro-acoustic transducer membrane, in particular for a loudspeaker for the medium and acute channels.
• Ammonia is added dropwise until a gel is obtained.
• the gel thus obtained is mixed with appropriate fibers or fillers (carbon, glass, mica, kevlar, graphite) and is shaped.
• the form thus obtained is dried by means of hot air in order to evaporate the water and the ammonia.
• a bath of the same mother liquor of APPRETAN 9110 is prepared (dry extract of 32.50%) which is diluted in water at the rate of 15% and it is gelled by adding ammonia drop by drop.
• Carbon fibers are poured into the gel formed and dispersed therein in a manner homogeneous in a mixer.
• the homogenized mixture thus obtained is passed under pressure through a sieve which retains the fibers impregnated with gel, which are dried on the sieve with hot air.
• the shape thus obtained is removed from the sieve.
• this form of membrane is not waterproof, it is sealed by applying a coating, such as butyl latex, or by heat bonding a sheet of waterproof thermo-adhesive polymer, such as "LITREX S "(polyethersulfone) from PCD
• the invention is not limited to the embodiments or to the compounds indicated and specified, in particular in the examples, in particular to macropolymers, on the one hand, and to stabilizing liquids, on the other hand , or any additives, but it includes modifications and variants within the reach of ordinary skill in the art, including with regard to the means of applying the product obtained according to its destination in various uses.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Theoretical Computer Science (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Toys (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9398990

Family Applications (1)

Country Status (13)

Families Citing this family (1)

Family Cites Families (15)

• 1990
  • 1990-07-23 FR FR9009369A patent/FR2665321A1/fr active Pending
• 1991
  • 1991-07-22 EP EP91913851A patent/EP0540622B1/fr not_active Expired - Lifetime
  • 1991-07-22 AT AT91913851T patent/ATE141739T1/de not_active IP Right Cessation
  • 1991-07-22 KR KR1019930700197A patent/KR100195826B1/ko not_active Expired - Fee Related
  • 1991-07-22 JP JP3512793A patent/JP3046351B2/ja not_active Expired - Lifetime
  • 1991-07-22 DE DE69121572T patent/DE69121572T2/de not_active Expired - Fee Related
  • 1991-07-22 DK DK91913851.1T patent/DK0540622T3/da active
  • 1991-07-22 WO PCT/FR1991/000603 patent/WO1992002108A1/fr not_active Ceased
  • 1991-07-22 CA CA002087432A patent/CA2087432A1/fr not_active Abandoned
  • 1991-07-22 ES ES91913851T patent/ES2044819T3/es not_active Expired - Lifetime
  • 1991-07-22 US US07/969,801 patent/US5380960A/en not_active Expired - Fee Related
  • 1991-07-22 DE DE91913851T patent/DE540622T1/de active Pending
• 1992
  • 1992-01-11 TW TW081100162A patent/TW203658B/zh active
• 1994
  • 1994-04-29 GR GR940300018T patent/GR940300018T1/el unknown
• 1996
  • 1996-11-14 GR GR960402995T patent/GR3021624T3/el unknown

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