# US 11,445,304 B2 · Ultrasonic sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,445,304 B2 - Document ID: US11445304B2 - Status: Granted - Kind: B2 - Application number: 16/837,258 - Filed: 2020-04-01 - Published: 2020-10-08 - Granted: 2022-09-13 - Earliest claimed: 2019-04-05 - Assignees: Denso Corporation - Applicants: Denso Corporation - Inventors: Tatsuya Kamiya; Itaru Ishii; Tomoki Tanemura; Takashi Aoki; Tetsuya Katoh - Web page: https://patentgrep.com/patent/US11445304B2 ## CPC - B06B 1/0651: {of circular shape} - H04R 17/02: Microphones - B81B 7/0041: {maintaining a controlled atmosphere with techniques not provided for in B81B7/0038} - B81B 7/0061: {suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound} - G01H 11/08: using piezoelectric devices - G01N 29/12: by measuring frequency or resonance of acoustic waves {(measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00)} - G01S 7/521: Constructional features - G01S 15/931: of land vehicles - G10K 9/122: using piezoelectric driving means {(G10K9/121 takes precedence)} - H04R 19/005: {using semiconductor materials} - H04R 19/04: Microphones (H04R19/01 takes precedence) - B06B 1/0666: {used as a diaphragm} - B81B 2201/0257: Microphones or microspeakers - B81B 2201/0271: Resonators; ultrasonic resonators - G01S 2015/938: {in the bumper area} - H04R 2499/13: Acoustic transducers and sound field adaptation in vehicles - 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) - 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) - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - 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 ## Abstract An ultrasonic sensor includes: an element storage case including a case-side diaphragm having a thickness direction along a directional axis; and an ultrasonic element accommodated in the element storage case and spaced apart from the case-side diaphragm. The ultrasonic element includes an element-side diaphragm having the thickness direction along the directional axis and provided by a thin part of a semiconductor substrate. The semiconductor substrate is arranged to provide a closed space between the case-side diaphragm and the element-side diaphragm. The semiconductor substrate is fixed and supported by the element-storage case. ## Claims ### Claim 1 An ultrasonic sensor comprising: an element storage case including at least one case-side diaphragm that is a vibration plate having a thickness direction along a directional axis; and at least one ultrasonic element accommodated in the element storage case and spaced apart from the case-side diaphragm, wherein: the ultrasonic element includes an element-side diaphragm that is a vibration film having the thickness direction along the directional axis and provided by a thin part of a semiconductor substrate having the thickness direction along the directional axis; the semiconductor substrate is arranged to provide at least one closed space as a resonant space between the case-side diaphragm and the element-side diaphragm; and the semiconductor substrate is fixed and supported by the element-storage case, wherein: a resonant frequency of the ultrasonic element is defined as a first resonant frequency; a resonant frequency of the closed space is defined as a second resonant frequency; a resonant frequency of the case-side diaphragm is defined as a third resonant frequency; the first to third resonant frequencies are substantially equal to each other; wherein: a maximum difference among a difference between the first resonant frequency and the second resonant frequency, a difference between the second resonant frequency and the third resonant frequency and a difference between the first resonant frequency and the third resonant frequency is defined as Δfr; a bandwidth of a widest resonance band among a resonance band of the ultrasonic element, a resonance band of the closed space and a resonance band of the case-side diaphragm is defined as BW; and an equation of Δfr≤BW is satisfied. ### Claim 2 (depends on 1) The ultrasonic sensor according to claim 1, wherein: the element storage case includes a side plate having a cylinder shape surrounding the directional axis, and an outer base plate that liquid-tightly seals one end of the side plate; the case-side diaphragm is provided by a thin part of the outer base plate arranged at a center of the outer base plate in an on-plane direction intersecting the directional axis; and the semiconductor substrate is fixed and supported by a case-side thick part of the outer base plate disposed in a periphery of the case-side diaphragm. ### Claim 3 (depends on 2) The ultrasonic sensor according to claim 2, further comprising: a support substrate having the thickness direction along the directional axis and arranged between the outer base plate and the semiconductor substrate, wherein: the support substrate is connected to the case-side thick part of the outer base plate, and is fixed to the element storage case; the semiconductor substrate is connected to the support substrate, and is fixed to the support substrate; the support substrate has a communication hole that is a through hole penetrating the support substrate to communicate with a gap between the case-side diaphragm and the support substrate; and the gap and the communication hole provide the closed space. ### Claim 4 (depends on 3) The semiconductor sensor according to claim 3, wherein: the semiconductor substrate includes an element-side recessed part that is a concavity arranged at a position corresponding to the element-side diaphragm in the on-plane direction to be surrounded by an element-side thick part of the ultrasonic element adjacent to the element-side diaphragm in the on-plane direction; the semiconductor substrate is connected to the support substrate, and the element-side recessed part is adjacent to and communicates with the communication hole; and an element-side hollow part that is a space inside the element-side recessed part, the gap, and the communication hole provide the closed space. ### Claim 5 (depends on 2) The ultrasonic sensor according to claim 2, wherein: the semiconductor substrate includes an element-side recessed part that is a concavity arranged at a position corresponding to the element-side diaphragm in the on-plane direction to be surrounded by an element-side thick part of the ultrasonic element adjacent to the element-side diaphragm in the on-plane direction; the semiconductor substrate is connected to the case-side thick part of the outer base plate, and the element-side recessed part is adjacent to and communicates with the gap, the semiconductor substrate is accommodated in the element storage case; and an element-side hollow part that is a space inside the element-side recessed part and the gap provide the closed space. ### Claim 6 (depends on 1) The ultrasonic sensor according to claim 1, wherein: the closed space has a cross-sectional area orthogonal to the directional axis; and the cross-sectional area varies along a directional-axis direction parallel to the directional axis. ### Claim 7 (depends on 1) The ultrasonic sensor according to claim 1, further comprising: a damper accommodated in the closed space. ### Claim 8 (depends on 1) The ultrasonic sensor according to claim 1, wherein: the at least one case-side diaphragm includes a plurality of case-side diaphragms arrayed in an on-plane direction intersecting the directional axis, the at least one ultrasonic element includes a plurality of ultrasonic elements arrayed in an on-plane direction intersecting the directional axis, or the at least one closed space includes a plurality of closed spaces arrayed in an on-plane direction intersecting the directional axis. ### Claim 9 (depends on 8) The ultrasonic sensor according to claim 8, further comprising: a diaphragm separation member arranged between adjacent case-side diaphragms, wherein: the diaphragm separation member restricts propagation of a vibration between the adjacent case-side diaphragms when the at least one case-side diaphragm includes the plurality of case-side diaphragms arrayed in an on-plane direction intersecting the directional axis. ### Claim 10 (depends on 8) The ultrasonic sensor according to claim 8, wherein: in a case where the at least one case-side diaphragm includes a plurality of case-side diaphragms arrayed in an on-plane direction intersecting the directional axis, each of the plurality of case-side diaphragms have different resonant frequencies; in a case where the at least one ultrasonic element includes a plurality of ultrasonic elements arrayed in an on-plane direction intersecting the directional axis, each of the plurality of ultrasonic elements have different resonant frequencies; and in a case where the at least one closed space includes a plurality of closed spaces arrayed in an on-plane direction intersecting the directional axis, each of the plurality of closed spaces have different resonant frequencies. ### Claim 11 (depends on 1) The ultrasonic sensor according to claim 1, further comprising: a volume adjustment part for adjusting a volume of the closed space, wherein: the volume adjustment part is a projection, a tapered part, or a recessed part arranged to face the closed space at a position different from a diaphragm back surface (43c) that is an internal surface of the case-side diaphragm facing the closed space. ### Claim 12 (depends on 1) The ultrasonic sensor according to claim 1, further comprising: a slit arranged at one end of the element storage case on a side of the case-side diaphragm in a directional-axis direction parallel to the directional axis. ### Claim 13 (depends on 12) The ultrasonic sensor according to claim 12, wherein: the slit is air-tightly and liquid-tightly sealed by a sealant. ### Claim 14 (depends on 1) The ultrasonic sensor according to claim 1, further comprising: a moisture absorbent accommodated in the element storage case. ### Claim 15 (depends on 1) The ultrasonic sensor according to claim 1, wherein: the element storage case includes a substrate back space arranged on a side opposite to the closed space with sandwiching the semiconductor substrate between the substrate back space and the closed space, and an air vent opening for communicating the substrate back space and a case back space outside the element storage case with each other; the air vent opening is liquid-tightly sealed to restrict a liquid from passing through the air vent opening; and air passes through the air vent opening. ### Claim 16 (depends on 1) The ultrasonic sensor according to claim 1, further comprising: a frequency changer that changes a vibrational frequency of the ultrasonic element, the closed space, or the case-side diaphragm according to an operational environment temperature of the ultrasonic sensor. ### Claim 17 (depends on 1) The ultrasonic sensor according to claim 1, wherein: a resonant frequency of each of the ultrasonic element, the closed space, and the case-side diaphragm is disposed in a range between 30 kHz and 100 kH. ### Claim 18 (depends on 1) The ultrasonic sensor according to claim 1, wherein: the case-side diaphragm has an external surface defined as a bare surface intersecting the directional axis; the bare surface is exposed to an external space of a vehicle through a through hole of an outer plate of a vehicle body when the ultrasonic sensor is mounted in the vehicle body of the vehicle; and the case-side diaphragm has a thickness of 0.5 mm or more.