Abstract: An ultrasonic sensor including a case having a bottom portion, and a piezoelectric element that is bonded to an inner surface of the bottom portion and performs bending vibration together with the bottom portion. The piezoelectric element includes a piezoelectric layer having a transmission region and a reception region, a common electrode, a transmission electrode opposing the common electrode with the transmission region interposed therebetween, and a reception electrode opposing the common electrode with the reception region interposed therebetween. The transmission region and the reception region are formed at positions adjacent to each other.

Abstract: An ultrasonic sensor including a case having a bottom portion, and a piezoelectric element that is bonded to an inner surface of the bottom portion and performs bending vibration together with the bottom portion. The piezoelectric element includes a piezoelectric layer having a transmission region and a reception region, a common electrode, a transmission electrode opposing the common electrode with the transmission region interposed therebetween, and a reception electrode opposing the common electrode with the reception region interposed therebetween. The transmission region and the reception region are formed at positions adjacent to each other.

Abstract: A tuning fork-type vibrator includes a tuning fork-type vibrating body including a base and legs. The tuning fork-type vibrating body includes two piezoelectric substrates, an intermediate electrode, surface electrodes and an entire-surface electrode that are laminated together. The surface electrodes are separated by separating portions extending from the base to each of the legs. The widths of the separating portions at a point of connection to the circuit board are wider than those of the separating portions at other points. The separating portions are formed by dividing an electrode provided on the entire surface of a piezoelectric substrate in the vibrating body with a dicer or by laser radiation or etching.

Abstract: A tuning fork-type vibrator includes a tuning fork-type vibrating body including a base and legs. The tuning fork-type vibrating body includes two piezoelectric substrates, an intermediate electrode, surface electrodes and an entire-surface electrode that are laminated together. The surface electrodes are separated by separating portions extending from the base to each of the legs. The widths of the separating portions at a point of connection to the circuit board are wider than those of the separating portions at other points. The separating portions are formed by dividing an electrode provided on the entire surface of a piezoelectric substrate in the vibrating body with a dicer or by laser radiation or etching.

Abstract: An acceleration sensor includes a detection element having a plurality of piezoelectric ceramic layers laminated together and a pair of retaining members that retain an end portion of the detection element in a longitudinal direction thereof at two principal surfaces of the end portion. The detection element includes electrodes between the ceramic layers and on principal surfaces. The detection element obtains a voltage or a charge generated in the detection element in response to an application of acceleration from the principal-surface electrodes and the interlayer electrodes. The piezoelectric ceramic layers are not polarized in areas between the principal-surface electrodes and the interlayer electrodes within a retaining area in which the detection element is retained by the retaining members.

Abstract: An acceleration sensor outputs a signal in accordance with acceleration. A differentiator outputs a differential signal of the output signal. A comparator inverts the state of an output when the differential signal goes beyond a threshold. A monostable multivibrator maintains the state-inverted signal of the output for a predetermined period of time. An integrator integrates the acceleration detection signal. A comparator inverts the state of an output signal when an integrated signal goes beyond a threshold. A fall determination processor outputs a signal out indicating that a fall has been detected in a situation in which, when the output of the monostable multivibrator is active, the state of the output of the comparator is inverted.

Abstract: An acceleration sensor includes a detection element having a plurality of piezoelectric ceramic layers laminated together and a pair of retaining members that retain an end portion of the detection element in a longitudinal direction thereof at two principal surfaces of the end portion. The detection element includes electrodes between the ceramic layers and on principal surfaces. The detection element obtains a voltage or a charge generated in the detection element in response to an application of acceleration from the principal-surface electrodes and the interlayer electrodes. The piezoelectric ceramic layers are not polarized in areas between the principal-surface electrodes and the interlayer electrodes within a retaining area in which the detection element is retained by the retaining members.

Abstract: An acceleration sensor in which a difference in resonance characteristics between two resonators can be easily adjusted even when casing components are already attached to an acceleration-sensor element includes a bimorph acceleration-sensor element having first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. Opposite sides of the acceleration-sensor element with respect to the application direction of acceleration are respectively covered with a pair of casing components.

Abstract: An acceleration sensor outputs a signal in accordance with acceleration. A differentiator outputs a differential signal of the output signal. A comparator inverts the state of an output when the differential signal goes beyond a threshold. A monostable multivibrator maintains the state-inverted signal of the output for a predetermined period of time. An integrator integrates the acceleration detection signal. A comparator inverts the state of an output signal when an integrated signal goes beyond a threshold. A fall determination processor outputs a signal out indicating that a fall has been detected in a situation in which, when the output of the monostable multivibrator is active, the state of the output of the comparator is inverted.

Abstract: A compact, highly sensitive acceleration sensor that is not affected by factors other than acceleration, such as a change in temperature, includes a bimorph acceleration-sensor element including first and second resonators and attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane N1 in response to the acceleration, the central bending plane N1 being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: A compact, high-sensitivity acceleration sensor that is prevented from being affected by factors other than acceleration, such as a change in temperature, has a bimorph acceleration-sensor element including first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end of the acceleration-sensor element is fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane in response to the acceleration, the central bending plane being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: A compact, high-sensitivity acceleration sensor that is prevented from being affected by factors other than acceleration, such as a change in temperature, has a bimorph acceleration-sensor element including first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end of the acceleration-sensor element is fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane in response to the acceleration, the central bending plane being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: A compact, highly sensitive acceleration sensor that is not affected by factors other than acceleration, such as a change in temperature, includes a bimorph acceleration-sensor element including first and second resonators and attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane N1 in response to the acceleration, the central bending plane N1 being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: An acceleration sensor in which a difference in resonance characteristics between two resonators can be easily adjusted even when casing components are already attached to an acceleration-sensor element includes a bimorph acceleration-sensor element having first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. Opposite sides of the acceleration-sensor element with respect to the application direction of acceleration are respectively covered with a pair of casing components.

Abstract: An acceleration sensor includes a piezoelectric element and a support member for supporting the piezoelectric element at both longitudinal ends thereof. The piezoelectric element includes a laminate having a plurality of piezoelectric layers. An intermediate piezoelectric layer is a dummy layer which generates no charge when acceleration is applied thereto. Each of the two outer piezoelectric layers includes four longitudinally aligned regions separated at two borders and one central border where stress is inverted when the acceleration is applied. The two outer piezoelectric layers are polarized in the direction of thickness of the piezoelectric element such that cells adjacent to each other in the longitudinal direction of the piezoelectric elements have opposite polarization directions and such that cells aligned with each other in the direction of thickness have the same polarization.

Abstract: An acceleration sensor includes a piezoelectric element and a support member for supporting the piezoelectric element at both longitudinal ends thereof. The piezoelectric element includes a laminate of at least two piezoelectric layers. Each of the at least two piezoelectric layers includes three longitudinally aligned regions separated at two borders where stress is inverted in the longitudinal direction of the piezoelectric element when acceleration is applied. Cells, each formed of a respective region, are polarized in the same direction of thickness in each of the two external piezoelectric layers. Electrodes are arranged so that the three cells in the one piezoelectric layer are serially connected, the three cells in the other piezoelectric layer are serially connected, and then the three serially connected cells in the one piezoelectric layer and the three serially connected cells in the other piezoelectric layer are connected in parallel.

Abstract: An acceleration sensor including a bimorph type acceleration detection element including a pair of surface acoustic wave resonators laminated to each other with the back surface of one resonator bonded to the back surface the other resonator. Each resonator includes a piezoelectric substrate and a pair of IDT electrodes which are arranged on the front surface of the piezoelectric substrate. The acceleration detection element is supported at the end thereof so that the acceleration detection element is deflected in the direction of thickness under acceleration. Acceleration is detected by detecting a difference between frequency changes of the two surface acoustic wave resonators or a difference between impedance changes of the two surface acoustic wave resonators, which takes place under acceleration.

Abstract: An acceleration sensor includes a first resonator and a second resonator which resonate at independent frequencies and each of which includes a piezoelectric body and electrodes arranged on both main surfaces thereof, and a first base plate and a second base plate. A first unimorph type acceleration detection element includes the first resonator bonded to one surface of the first base plate, and a second unimorph type acceleration detection element includes the second resonator bonded to one surface of the second base plate. Each of the first and second unimorph type acceleration detection elements is fixed at one longitudinal end thereof or opposed longitudinal ends thereof such that the first resonator and the second resonator are diametrically opposed to each other or are arranged to face each other to allow the first resonator and the second resonator to independently deflect in response to the application of acceleration.

Abstract: An acceleration sensor includes a sensing element and a pair of supporting members for supporting the sensing element at one end in the longitudinal direction thereof. The sensing element includes four laminated piezoelectric layers, and electrodes are provided at the center in the thickness direction of the sensing element, between a pair of first layers and a pair of second layers, and on the outer surfaces of the pair of second layers. Cells formed by the first and second layers at each side of the center in the thickness direction are electrically connected in parallel. The pair of first layers preferably have substantially the same thickness and the pair of second layers preferably have substantially the same thickness, and the ratio of the thickness T1 of each first layer to the total thickness T2 of each first and second layer is about 62% to about 76%.

Abstract: A piezoelectric type acceleration sensor which is small in size and has a high charge sensitivity and large static capacitance includes a piezoelectric element having a laminate of more than three piezoelectric layers. Electrodes are provided between the piezoelectric layers and the top and bottom surfaces of the laminate. The piezoelectric element is supported at opposed ends. Adjacent ones of the piezoelectric layers are polarized so that charge having the same polarity is accumulated at the electrode interposed the adjacent ones.