# US 11,910,719 B2 · Piezoelectric film > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,910,719 B2 - Document ID: US11910719B2 - Status: Granted - Kind: B2 - Application number: 17/553,804 - Filed: 2021-12-17 - Published: 2022-04-07 - Granted: 2024-02-20 - Earliest claimed: 2019-06-28 - Assignees: FUJIFILM Corporation - Applicants: FUJIFILM Corporation - Inventors: Shingo Fujikata - Web page: https://patentgrep.com/patent/US11910719B2 ## CPC - H04R 17/005: {using a piezoelectric polymer} - H10N 30/852: {Composite materials, e.g. having 1-3 or 2-2 type connectivity} - H04R 17/00: Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) - 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) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract Provided is a piezoelectric film capable of realizing a piezoelectric speaker in which a high sound pressure is obtained, a sufficient sound pressure characteristic is obtained in a wide frequency band, and generation of a chattering sound particularly in a low sound can be suppressed. The piezoelectric film is a piezoelectric film including a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material, and electrode layers which are laminated on both surfaces of the polymer-based piezoelectric composite material, in which a variation coefficient of a destructive force of a laminate having the polymer-based piezoelectric composite material and the electrode layers in a plane direction is 0.25 or less. ## Claims ### Claim 1 A piezoelectric film comprising: a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material; and electrode layers which are laminated on both surfaces of the polymer-based piezoelectric composite material, wherein a variation coefficient of a destructive force of a laminate having the polymer-based piezoelectric composite material and the electrode layers in a plane direction is 0.25 or less. ### Claim 2 (depends on 1) The piezoelectric film according to claim 1, wherein an average value of the destructive force of the laminate is 3 N or greater. ### Claim 3 (depends on 1) The piezoelectric film according to claim 1, further comprising: a protective layer laminated on a surface of at least one electrode layer. ### Claim 4 (depends on 3) The piezoelectric film according to claim 3, wherein the protective layer is laminated on surfaces of the electrode layers. ### Claim 5 (depends on 1) The piezoelectric film according to claim 1, wherein the polymer material contains a cyanoethyl group. ### Claim 6 (depends on 5) The piezoelectric film according to claim 5, wherein the polymer material is cyanoethylated polyvinyl alcohol. ### Claim 7 (depends on 1) The piezoelectric film according to claim 1, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure. ### Claim 8 (depends on 2) The piezoelectric film according to claim 2, further comprising: a protective layer laminated on a surface of at least one electrode layer. ### Claim 9 (depends on 8) The piezoelectric film according to claim 8, wherein the protective layer is laminated on surfaces of the electrode layers. ### Claim 10 (depends on 2) The piezoelectric film according to claim 2, wherein the polymer material contains a cyanoethyl group. ### Claim 11 (depends on 10) The piezoelectric film according to claim 10, wherein the polymer material is cyanoethylated polyvinyl alcohol. ### Claim 12 (depends on 2) The piezoelectric film according to claim 2, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure. ### Claim 13 (depends on 3) The piezoelectric film according to claim 3, wherein the polymer material contains a cyanoethyl group. ### Claim 14 (depends on 13) The piezoelectric film according to claim 13, wherein the polymer material is cyanoethylated polyvinyl alcohol. ### Claim 15 (depends on 3) The piezoelectric film according to claim 3, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure. ### Claim 16 (depends on 4) The piezoelectric film according to claim 4, wherein the polymer material contains a cyanoethyl group. ### Claim 17 (depends on 16) The piezoelectric film according to claim 16, wherein the polymer material is cyanoethylated polyvinyl alcohol. ### Claim 18 (depends on 4) The piezoelectric film according to claim 4, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure. ### Claim 19 (depends on 5) The piezoelectric film according to claim 5, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure. ### Claim 20 (depends on 6) The piezoelectric film according to claim 6, wherein the piezoelectric particles consist of ceramic particles having a perovskite-type or wurtzite-type crystal structure.