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US 7,730,785 B2Granted
Ultrasonic sensor and manufacture method of the same
AssigneeDenso Corporation
InventorsHiroyuki Wado, Makiko Sugiura
Life of this patent
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Abstract
An ultrasonic sensor is provided with a substrate unit where a thin-walled portion is arranged and a piezoelectric oscillator which is formed at the substrate unit. The piezoelectric oscillator includes two electrodes and a piezoelectric film positioned between the two electrodes. The thin-walled portion and the piezoelectric oscillator construct a membrane structure which will resonate at a predetermined frequency.
Claims42
An ultrasonic sensor, comprising:
- a substrate unit including a thin-walled portion which is arranged at a part thereof and has a smaller thickness than other part thereof;
- a piezoelectric oscillator which includes two detection electrodes and a piezoelectric film positioned between the detection electrodes in a thickness direction of the substrate unit, the piezoelectric oscillator and the thin-walled portion constructing a membrane structure;
- and
- an adjustment electrode unit for applying a predetermined voltage to the thin-walled portion, wherein
- the membrane structure is provided with a negative electrostatic spring effect due to the predetermined voltage.
2 more elements
An ultrasonic sensor, comprising:
- a substrate unit including a thin-walled portion which is arranged at a part thereof and has a smaller thickness than other part thereof;
- and
- a piezoelectric oscillator which includes two electrodes and a piezoelectric film positioned between the two electrodes, the piezoelectric oscillator being arranged at the thin-walled portion, wherein:
- the thin-walled portion and the piezoelectric oscillator construct a membrane structure which has a predetermined resonance frequency;
- the membrane structure is adjusted so that an internal stress of the membrane structure when the piezoelectric oscillator does not vibrate is a tensile stress or substantial zero on the whole;
- and
- the thin-walled portion includes a concave portion, which is arranged at a part of the thin-walled portion and has a smaller thickness than other part thereof.
4 more elements
An ultrasonic sensor comprising:
- a substrate unit including a thin-walled portion which is arranged at a part thereof and has a smaller thickness than other part thereof;
- and
- a piezoelectric oscillator which includes two electrodes and a piezoelectric film positioned between the two electrodes, the piezoelectric oscillator being arranged at the thin-walled portion, wherein:
- the thin-walled portion and the piezoelectric oscillator construct a membrane structure which has a predetermined resonance frequency;
- an internal stress of the membrane structure in a state where the piezoelectric oscillator does not vibrate is a tensile stress or substantial zero on the whole;
- and
- the membrane structure has a compressive stress region, in which an internal stress is a compressive stress in a surface direction of the substrate unit when the piezoelectric oscillator does not vibrate.
4 more elements
Dependencies are inferred from the claim text.