# US 10,502,542 B2 · Piezoelectric element and piezoelectric sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,542 B2 - Document ID: US10502542B2 - Status: Granted - Kind: B2 - Application number: 15/673,444 - Filed: 2017-08-10 - Published: 2017-12-21 - Granted: 2019-12-10 - Earliest claimed: 2015-02-18 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Yuya Genmei - Web page: https://patentgrep.com/patent/US10502542B2 ## CPC - G01B 7/16: for measuring the deformation in a solid, e.g. by resistance strain gauge - G01L 1/16: using properties of piezoelectric devices - H10N 30/302: {Sensors} - H10N 30/8554: {Lead-zirconium titanate [PZT] based} - H10N 30/87: Electrodes or interconnections, e.g. leads or terminals - H10N 30/871: {Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes} - H10N 30/872: {Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices} - H10N 30/883: {Additional insulation means preventing electrical, physical or chemical damage, e.g. protective coatings} - H10N 30/02: Forming enclosures or casings - H10N 30/053: by integrally sintering piezoelectric or electrostrictive bodies and electrodes - H10N 30/06: Forming electrodes or interconnections, e.g. leads or terminals - H10N 30/073: by fusion of metals or by adhesives - H10N 30/097: by sintering - H10N 35/01: Manufacture or treatment - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A piezoelectric element includes a laminate including first and second piezoelectric layers with respective polarization directions in a thickness direction and an elastic layer provided between the first piezoelectric layer and the second piezoelectric layer, first and second terminal electrodes that are provided on an external surface of the laminate, a first detection electrode provided on a positive polar surface of the first piezoelectric layer, a second detection electrode provided on a negative polar surface of the first piezoelectric layer, a third detection electrode provided on a positive polar surface of the second piezoelectric layer, and a fourth detection electrode provided on a negative polar surface of the second piezoelectric layer. The first detection electrode and the fourth detection electrode are connected to the first terminal electrode. The second detection electrode and the third detection electrode are connected to the second terminal electrode. ## Claims ### Claim 1 A piezoelectric element comprising: a laminate including a first piezoelectric layer and a second piezoelectric layer with respective polarization directions in a thickness direction and an elastic layer provided between the first piezoelectric layer and the second piezoelectric layer; a first terminal electrode and a second terminal electrode which are provided on an external surface of the laminate; a first detection electrode provided on a positive polar surface of the first piezoelectric layer; a second detection electrode provided on a negative polar surface of the first piezoelectric layer; a third detection electrode provided on a positive polar surface of the second piezoelectric layer; and a fourth detection electrode provided on a negative polar surface of the second piezoelectric layer; wherein the first detection electrode and the fourth detection electrode are connected to the first terminal electrode; the second detection electrode and the third detection electrode are connected to the second terminal electrode; and a Young's modulus of the elastic layer is lower than a Young's modulus of each of the first piezoelectric layer and the second piezoelectric layer. ### Claim 2 (depends on 1) The piezoelectric element according to claim 1, wherein the first piezoelectric layer and the second piezoelectric layer have a same polarization direction. ### Claim 3 (depends on 1) The piezoelectric element according to claim 1, wherein the elastic layer is provided between the first piezoelectric layer and the second piezoelectric layer and near end surfaces in a length direction; and an adhesive layer is provided between the first piezoelectric layer and the second piezoelectric layer and in a center portion in the length direction. ### Claim 4 (depends on 1) The piezoelectric element according to claim 1, wherein the first, second, third, and fourth detection electrodes are exposed on portions of end surfaces and side surfaces of the laminate; and the first and second terminal electrodes are provided on portions of the end surfaces and the side surfaces of the laminate. ### Claim 5 (depends on 1) The piezoelectric element according to claim 1, wherein the first terminal electrode is connected to at least one of the first and fourth detection electrodes in a center portion of a first side surface of the laminate in the length direction; and the second terminal electrode is connected to at least one of the second and third detection electrodes in a center portion of a second side surface of the laminate in the length direction. ### Claim 6 (depends on 1) The piezoelectric element according to claim 1, wherein the laminate further includes a first exterior body disposed on the first piezoelectric layer and a second exterior body disposed on the second piezoelectric layer. ### Claim 7 (depends on 1) The piezoelectric element according to claim 1, wherein each of the first piezoelectric layer and the second piezoelectric layer is made of lead zirconate titanate. ### Claim 8 (depends on 1) The piezoelectric element according to claim 1, wherein the elastic layer is made of a urethane resin or a silicone resin. ### Claim 9 (depends on 1) The piezoelectric element according to claim 1, wherein the elastic layer is provided across an entire surface between the first piezoelectric layer and the second piezoelectric layer. ### Claim 10 (depends on 1) A piezoelectric sensor comprising: the piezoelectric element according to claim 1; and a deformation detection target object on which the piezoelectric element is disposed. ### Claim 11 (depends on 10) The piezoelectric sensor according to claim 10, wherein the second piezoelectric layer is provided closer to the target object than the first piezoelectric layer; and deformation of the target object is detected based on a difference in a degree of expansion between the first piezoelectric layer and the second piezoelectric layer which is generated by the elastic layer. ### Claim 12 (depends on 10) The piezoelectric sensor according to claim 10, wherein the piezoelectric element is connected to the target object via a joint; and the joint is located below a height position at which the first piezoelectric layer is provided on end surfaces of the piezoelectric element. ### Claim 13 (depends on 10) The piezoelectric sensor according to claim 10, wherein the first piezoelectric layer and the second piezoelectric layer have a same polarization direction. ### Claim 14 (depends on 10) The piezoelectric sensor according to claim 10, wherein the elastic layer is provided between the first piezoelectric layer and the second piezoelectric layer and near end surfaces in a length direction; and an adhesive layer is provided between the first piezoelectric layer and the second piezoelectric layer and in a center portion in the length direction. ### Claim 15 (depends on 10) The piezoelectric sensor according to claim 10, wherein the first, second, third, and fourth detection electrodes are exposed on portions of end surfaces and side surfaces of the laminate; and the first and second terminal electrodes are provided on portions of the end surfaces and the side surfaces of the laminate. ### Claim 16 (depends on 10) The piezoelectric sensor according to claim 10, wherein the first terminal electrode is connected to at least one of the first and fourth detection electrodes in a center portion of a first side surface of the laminate in the length direction; and the second terminal electrode is connected to at least one of the second and third detection electrodes in a center portion of a second side surface of the laminate in the length direction. ### Claim 17 (depends on 10) The piezoelectric sensor according to claim 10, wherein the laminate further includes a first exterior body disposed on the first piezoelectric layer and a second exterior body disposed on the second piezoelectric layer. ### Claim 18 (depends on 10) The piezoelectric sensor according to claim 10, wherein each of the first piezoelectric layer and the second piezoelectric layer is made of lead zirconate titanate. ### Claim 19 (depends on 10) The piezoelectric sensor according to claim 10, wherein the elastic layer is made of a urethane resin or a silicone resin. ### Claim 20 (depends on 10) The piezoelectric sensor according to claim 10, wherein the elastic layer is provided across an entire surface between the first piezoelectric layer and the second piezoelectric layer.