Abstract: In a drive device for driving an ultrasonic transmitter, a drive signal generating unit generates a drive signal for driving the ultrasonic transmitter, based on a base signal having a plurality of unit frequency signals arranged in a time series, corresponding to respective codes forming a code sequence. When a first unit frequency signal and a second unit frequency signal chronologically adjacent to it are switched in a discontinuously switching state that is different from a continuously switching state where the first and second unit frequency signals are switched such that a target frequency for a transmission frequency changes continuously at a substantially constant rate, the drive signal generating unit shifts the frequency in at least a switching portion immediately after start of the second unit frequency signal, in a same direction as a direction of frequency change from the first unit frequency signal to the second unit frequency signal.

Abstract: An ultrasonic transducer includes a transducer case and an ultrasonic element. The transducer case is formed into a bottomed, cylindrical shape having a side plate portion and a bottom plate portion that seals one end side of the side plate portion in an axial direction to configure a diaphragm. The ultrasonic element is fixedly supported to the bottom plate portion to face an interior space surrounded by the side plate portion and the bottom plate portion. The ultrasonic element is arranged in a position being offset in an in-plane direction orthogonal to the axial direction relative to a center position of the diaphragm in the in-plane direction to be capable of generating a first transmission wave having first directivity characteristics and a second transmission wave having second directivity characteristics that are directivity characteristics differing from the first directivity characteristics and in which sound pressure in the axial direction is decreased.

Abstract: An ultrasonic sensor includes an adhesion sensor detecting adhesion of a foreign substance to a first surface of a bottom of a microphone housing. The adhesion sensor includes: a plurality of variable capacitances defined between a plurality of sensor electrodes disposed on the first surface of the bottom, each of the variable capacitances having a capacitance value which changes in response to adhesion of a foreign substance to the first surface; and an adhesion detection unit configured to measure an individual capacitance value which is a capacitance value of each of the variable capacitances and a total capacitance value which is a total of capacitance values of all the variable capacitances to determine, based on the individual capacitance value and the total capacitance value, whether a foreign substance adheres to the first surface, and, when it is determined that a foreign substance adheres, specify a type of the foreign sub stance.

Abstract: In a drive device for driving an ultrasonic transmitter, a drive signal generating unit generates a drive signal for driving the ultrasonic transmitter, based on a base signal having a plurality of unit frequency signals arranged in a time series, corresponding to respective codes forming a code sequence. When a first unit frequency signal and a second unit frequency signal chronologically adjacent to it are switched in a discontinuously switching state that is different from a continuously switching state where the first and second unit frequency signals are switched such that a target frequency for a transmission frequency changes continuously at a substantially constant rate, the drive signal generating unit shifts the frequency in at least a switching portion immediately after start of the second unit frequency signal, in a same direction as a direction of frequency change from the first unit frequency signal to the second unit frequency signal.

Abstract: An ultrasonic sensor comprises: an ultrasonic element that converts between an electric signal and ultrasonic vibration; and an element housing case having a bottomed tubular shape and housing the ultrasonic element therein. The element housing case includes a side plate portion having a tubular shape surrounding a directivity central axis, and a bottom plate portion that closes one end of the side plate portion in an axial direction parallel to the directivity central axis. The ultrasonic element is attached to the bottom plate portion. A part of the bottom plate portion inside an outline of the ultrasonic element when viewed along the directivity central axis includes a space formed due to a part of the part inside the outline being separated from the ultrasonic element.