# US 8,570,837 B2 · Multilayer backing absorber for ultrasonic transducer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,837 B2 - Document ID: US8570837B2 - Status: Granted - Kind: B2 - Application number: 12/330,316 - Filed: 2008-12-08 - Published: 2009-06-11 - Granted: 2013-10-29 - Earliest claimed: 2007-12-06 - Assignees: Measurement Specialties, Inc. - Applicants: Minoru Toda; Mitchell L. Thompson - Inventors: Minoru Toda; Mitchell L. Thompson - Web page: https://patentgrep.com/patent/US8570837B2 ## CPC - B06B 1/06: operating with piezoelectric effect or with electrostriction (piezoelectric or electrostrictive devices per se H10N30/00) - G10K 11/002: {Devices for damping, suppressing, obstructing or conducting sound in acoustic devices (G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002)} - Y10T 156/10: Methods of surface bonding and/or assembly therefor - Y10T 428/24132: including grain, strips, or filamentary elements in different layers or components parallel - Y10T 428/3154: Of fluorinated addition polymer from unsaturated monomers - B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R) - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A multilayer backing absorber for use with an ultrasonic transducer comprises an elemental multilayer having at least one metal layer and at least one adhesive layer, wherein the backing absorber is adapted to be coupled to a vibrating layer of the ultrasonic transducer. ## Claims ### Claim 1 A backing absorber for use with an ultrasonic transducer, comprising: a first elemental multilayer having at least one homogeneous metal layer and at least one adhesive layer; and a second elemental multilayer having at least one homogeneous metal layer and at least one adhesive layer, wherein one of said at least one homogeneous metal layer and said at least one adhesive layer of said second multilayer is bonded to the other of said at least one homogeneous metal layer and said at least one adhesive layer of said first multilayer, wherein a planar surface of said backing absorber is adapted to be coupled to a corresponding planar surface of a vibrating layer of said ultrasonic transducer, wherein said plurality of elemental multilayers are effective to dampen ultrasonic signals emitted by said vibrating layer when said backing absorber is coupled to said vibrating layer, and wherein each elemental multilayer further includes a polymer layer. ### Claim 2 (depends on 1) The backing absorber of claim 1, wherein the backing absorber further comprises at least a third elemental multilayer having at least one homogeneous metal layer and at least one adhesive layer. ### Claim 3 (depends on 2) The backing absorber of claim 2, wherein each of said at least one homogeneous metal layers is deposited on a corresponding one of said polymer layers to form a periodic grating of metal strips wherein the direction and period of the grating is the same for each elemental layer. ### Claim 4 (depends on 2) The backing absorber of claim 2, wherein each of said at least one homogeneous metal layers is deposited on a corresponding one of said polymer layers to form a periodic grating of metal strips wherein the direction or period of the grating is different for each elemental layer. ### Claim 5 (depends on 4) The backing absorber of claim 4, wherein said direction of said grating is positioned at a 90 degree angle relative to the direction of the grating of each adjacent multilayer. ### Claim 6 (depends on 2) The backing absorber of claim 2, wherein each of said at least one homogeneous metal layers is partially deposited on a selected area of a corresponding one of said polymer layers to form a boundary grading for reflecting backwards waves in such a way as to increase effective attenuation. ### Claim 7 (depends on 1) The backing absorber of claim 1, wherein the vibrating layer comprises one of a monolithic PZT plate, a 1-3 PZT composite, and a 2-2 PZT composite. ### Claim 8 (depends on 3) The backing absorber of claim 3, wherein the vibrating layer comprises a 2-2 PZT composite having a plurality of elongated bars of PZT material and wherein the direction of the elongated metal area of the grating is perpendicular to said PZT bars. ### Claim 9 A method of making a backing absorber for an ultrasonic transducer, comprising: forming a first multilayer element by coupling a first homogeneous metal layer to a first adhesive layer; forming a second multilayer element by coupling a second homogeneous metal layer to a second adhesive layer; and coupling at least one of said second homogeneous metal layer and said second adhesive layer to the other of said first homogeneous metal layer and said first adhesive layer, wherein a planar surface of said first multilayer element is configured to be coupled to a corresponding planar surface of a vibrating layer of said ultrasonic transducer for absorbing ultrasonic waves, wherein said forming further comprises first coupling a first and a second polymer layer to said first and second homogeneous metal layers, respectively. ### Claim 10 (depends on 9) The method of claim 9 further comprising: forming an additional multilayer element by coupling a third homogeneous metal layer to a third adhesive layer; and bonding said additional multilayer element to said first multilayer element. ### Claim 11 (depends on 10) The method of claim 10 further comprising: repeating said forming of said additional multilayers and said bonding of said additional multilayer elements until a predetermined acoustic absorption value has been reached. ### Claim 12 (depends on 11) The method of claim 11, wherein said forming further comprises depositing said homogeneous metal layer on a polymer layer to form a periodic grating of metal strips wherein the direction and period of the grating is the same for each elemental multilayer. ### Claim 13 (depends on 11) The method of claim 11, wherein said forming further comprises depositing said homogeneous metal layer on a polymer layer to form a periodic grating of metal strips wherein the direction or period of the grating is different for each elemental multilayer. ### Claim 14 (depends on 13) The method of claim 13, wherein said direction of said grating is positioned at a 90 degree angle relative to the direction of the grating of each adjacent multilayer. ### Claim 15 (depends on 10) The method of claim 10, wherein said forming further comprises partially depositing said homogeneous metal layer on a selected area of each of said at least one polymer layers to form a boundary grading for reflecting waves in such a way as to increase effective attenuation. ### Claim 16 An ultrasonic transducer assembly, comprising: a vibrating layer for generating ultrasonic waves; and a backing absorber coupled to said vibrating layer for absorbing said ultrasonic waves, said backing absorber having a plurality of elemental multilayers, each elemental multilayer including: a homogeneous metal layer, a polymer layer, and an adhesive layer. ### Claim 17 (depends on 16) The ultrasonic transducer assembly of claim 16, wherein the vibrating layer comprises one of a monolithic PZT plate, a 1-3 PZT composite, and a 2-2 PZT composite. ### Claim 18 A method of making an ultrasonic transducer assembly, comprising: providing a vibrating layer for generating acoustic ultrasonic waves; forming a plurality of multilayer elements wherein each multilayer element is formed by depositing a homogeneous metal layer on a polymer layer; bonding said plurality of multilayer elements to one another by use of a plurality of adhesive layers to form a backing absorber; and bonding a planar surface of said backing absorber to a corresponding backplane of said vibrating layer to absorb said acoustic ultrasonic waves.