# US 9,438,997 B2 · Diaphragm, loudspeaker using diaphragm, electronic device and mobile device using loudspeaker, and method for producing diaphragm > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,997 B2 - Document ID: US9438997B2 - Status: Granted - Kind: B2 - Application number: 14/650,324 - Filed: 2013-11-29 - Published: 2015-11-05 - Granted: 2016-09-06 - Earliest claimed: 2012-12-14 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Panasonic Intellectual Property Management Co., Ltd. - Inventors: Yohei Jin; Yoshimichi Kajihara - Web page: https://patentgrep.com/patent/US9438997B2 ## CPC - H04R 7/02: characterised by the construction - H04R 1/00: Details of transducers, {loudspeakers or microphones} - H04R 7/06: comprising a plurality of sections or layers - H04R 31/003: {for diaphragms or their outer suspension} - H04R 9/06: Loudspeakers - H04R 2307/021: Diaphragms comprising cellulose-like materials, e.g. wood, paper, linen - H04R 2307/023: Diaphragms comprising ceramic-like materials, e.g. pure ceramic, glass, boride, nitride, carbide, mica and carbon materials - H04R 2307/025: Diaphragms comprising polymeric materials - H04R 2307/027: Diaphragms comprising metallic materials - H04R 2307/029: Diaphragms comprising fibres - H04R 2499/11: Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's - H04R 2499/13: Acoustic transducers and sound field adaptation in vehicles - H04R 2499/15: Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract A diaphragm includes a paper layer and a skin layer. The paper layer includes natural fibers and synthetic fibers formed of thermoplastic resin. The paper layer is formed by mixing the natural fibers and the synthetic fibers in water, and thinly spreading a resultant mixture on a mesh. The skin layer is formed on one surface of the paper layer. Note here that the skin layer is formed of the same resin as that of the synthetic fibers. ## Claims ### Claim 1 A diaphragm comprising: a paper layer including natural fibers and synthetic fibers formed of thermoplastic resin; and a skin layer formed of a same thermoplastic resin as the thermoplastic resin of the synthetic fibers and formed on one surface of the paper layer, wherein tensile strength in a circumferential direction of the diaphragm is more than one time and 1.5 times or less as high as tensile strength in a direction from a center to an outer periphery of the diaphragm, the natural fibers have a beating degree of 200 ml or more and 700 ml or less in Canadian Standard freeness, and a length of each of the natural fibers is 0.8 mm or more and less than 3 mm. ### Claim 2 (depends on 1) The diaphragm of claim 1, wherein a part of the synthetic fibers includes a fused connecting portion unitarily connected to the skin layer. ### Claim 3 (depends on 1) The diaphragm of claim 1, wherein the skin layer is a melt of the synthetic fibers. ### Claim 4 (depends on 1) The diaphragm of claim 1, wherein orientation directions of the natural fibers and the synthetic fibers are random. ### Claim 5 (depends on 1) The diaphragm of claim 1, wherein a content of the natural fibers is 1% by weight or more and 90% by weight or less with respect to a total weight of the diaphragm. ### Claim 6 (depends on 1) The diaphragm of claim 1, wherein a density of the diaphragm is 0.25 g/cm3 or more and 1.00 g/cm3 or less. ### Claim 7 (depends on 1) The diaphragm of claim 1, wherein the natural fibers include a bamboo fiber. ### Claim 8 (depends on 7) The diaphragm of claim 7, wherein the bamboo fiber includes 0% by weight or more and 20% by weight or less of lignin with respect to a total weight of the bamboo fiber. ### Claim 9 (depends on 7) The diaphragm of claim 7, wherein the natural fibers further include 1% by weight or more and 30% by weight or less of micronized bamboo fibers with respect to the total weight of the bamboo fiber. ### Claim 10 (depends on 9) The diaphragm of claim 9, wherein a length of each of the micronized bamboo fibers is 0.1 mm or more and less than 0.8 mm. ### Claim 11 (depends on 9) The diaphragm of claim 9, wherein the micronized bamboo fibers have a beating degree of 1 ml or more and 200 ml or less in Canadian Standard freeness. ### Claim 12 (depends on 1) The diaphragm of claim 1, wherein the paper layer further includes reinforcement material. ### Claim 13 (depends on 12) The diaphragm of claim 12, wherein the reinforcement material is one or more selected from the group consisting of aramid fibers, glass fibers, carbon fibers, calcium carbonate, diatomaceous earth, talc, aluminum hydroxide, and a carbonized natural fiber. ### Claim 14 (depends on 1) The diaphragm of claim 1, wherein the resin is acrylic resin, polyester resin, or polyolefin resin. ### Claim 15 (depends on 14) The diaphragm of claim 14, wherein the polyester resin is one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polylactic acid. ### Claim 16 A loudspeaker comprising: a frame; a magnetic circuit bonded to the frame and provided with a magnetic gap; a voice coil inserted into the magnetic gap; and a diaphragm bonded to a periphery of the frame and including: a paper layer including natural fibers and synthetic fibers formed of thermoplastic resin, and a skin layer formed of a same thermoplastic resin as the thermoplastic resin of the synthetic fibers and formed on one surface of the paper layer, wherein tensile strength in a circumferential direction of the diaphragm is more than one time and 1.5 times or less as high as tensile strength in a direction from a center to an outer periphery of the diaphragm, the natural fibers have a beating degree of 200 ml or more and 700 ml or less in Canadian Standard freeness, and a length of each of the natural fibers is 0.8 mm or more and less than 3 mm. ### Claim 17 (depends on 16) The loudspeaker of claim 16, wherein the skin layer is formed in the diaphragm at a surface to which the voice coil is bonded. ### Claim 18 (depends on 16) The loudspeaker of claim 16, wherein the skin layer is formed in the diaphragm at a surface opposite to the surface to which the voice coil is bonded. ### Claim 19 (depends on 16) An electronic device comprising: the loudspeaker defined in claim 16; and an amplifier electrically connected to the loudspeaker. ### Claim 20 (depends on 16) A mobile device comprising: a body; a driver mounted to the body; and the loudspeaker defined in claim 16 and mounted to the body.