Abstract: A sensor device includes an electrically conductive base substrate defining a first electrode kept at a reference potential, a membrane defining a second electrode that changes a position thereof in response to a change of surrounding pressure and faces the base substrate, a casing that is kept at the reference potential and is outside the membrane, a capacitance detection circuit to amplify a signal from the membrane and detect an electrostatic capacitance between electrodes at a predetermined sampling cycle, and a signal processing circuit to measure a difference ?C of electrostatic capacitance values before and after a sampling, compare the difference AC with a predetermined threshold value Cta, and when ?C?Cta, determine that a foreign object is attached to the casing. Thus, the attachment of a foreign object can be reliably detected.

Abstract: A pressure sensor device includes an electrically insulative substrate, a base electrode layer, spacer portions, a guard electrode layer, and a membrane plate. A sensing electrode portion and monitoring electrode portions are located on the membrane plate and face the substrate. In a case where the monitoring electrodes are mounted on a circuit board, the monitoring electrodes detect at least one of stress or strain occurring in or on the spacer portions.

Abstract: A vibrating gyroscope includes two input buffers each arranged to input voltage signals appearing at respective detection electrodes of one of two piezoelectric vibrators. An adding circuit adds up output voltages of the respective input buffers. An amplitude control circuit automatically controls a loop gain such that an output voltage of the adding circuit has a substantially constant amplitude. A phase-shift circuit controls the phase of a drive voltage supplied to the piezoelectric vibrators such that the piezoelectric vibrators oscillate by positive feedback. Two differential amplifier circuits each amplify a voltage difference corresponding to an angular velocity about an axis. Two synchronous detection circuits each perform detection using a synchronizing signal generated from an oscillation signal, and detect a voltage signal corresponding to the angular velocity.

Abstract: A piezoelectric vibrator of a vibration gyro vibrates in response to a drive voltage Vdrv input into a drive electrode, and when deformed by a Coriolis force, generates detection voltages Vagc, between which a potential difference corresponds to the deformation, at detection electrodes. An AGC circuit outputs a drive voltage Vdrv while performing automatic gain control so that the detection voltages Vagc have a given amplitude. A phase inversion circuit and a BTL amplifier circuit output a BTL voltage Vbtl, whose phase is opposite to the detection voltage Vagc and whose amplitude has been increased, to the detection electrodes via detection resistances. The AGC circuit reduces the detection voltages Vagc in order to prevent the drive voltage Vdrv from exceeding a design upper limit value V?drv.

Abstract: An angular velocity detection apparatus includes an angular velocity detection signal amplifier circuit which amplifies an angular velocity detection signal Vo output from an angular velocity sensor, and an offset control circuit which controls an offset so as to be a reference voltage which is output when a value of an angular velocity is 0. The angular velocity detection apparatus further includes an input switch circuit which selects the reference voltage and a discharge switch circuit which short-circuits a capacitor included in a high-pass filter in an offset control period.

Abstract: In a method of setting temperature characteristics of an angular velocity sensor, temperature characteristics of a detuning frequency are acquired. The detuning frequency is a frequency difference between an oscillation frequency of an oscillation circuit including a piezoelectric vibrator and a frequency of a voltage of the piezoelectric vibrator caused by the Coriolis force. The sensitivity to the detuning frequency is acquired. The temperature characteristics of a detection phase are acquired. The detection phase is a phase difference between a Coriolis signal phase that corresponds to a phase angle of a voltage signal and an oscillation signal phase of the oscillation circuit. The sensitivity to the detection phase is acquired. The amount of phase shift of the detection phase is determined so that the change in sensitivity caused by the change in the detuning frequency with temperature is controlled using the change in sensitivity caused by the change in the detection phase with temperature.

Abstract: A piezoelectric vibrator of a vibration gyro vibrates in response to a drive voltage Vdrv input into a drive electrode, and when deformed by a Coriolis force, generates detection voltages Vagc, between which a potential difference corresponds to the deformation, at detection electrodes. An AGC circuit outputs a drive voltage Vdrv while performing automatic gain control so that the detection voltages Vagc have a given amplitude. A phase inversion circuit and a BTL amplifier circuit output a BTL voltage Vbtl, whose phase is opposite to the detection voltage Vagc and whose amplitude has been increased, to the detection electrodes via detection resistances. The AGC circuit reduces the detection voltages Vagc in order to prevent the drive voltage Vdrv from exceeding a design upper limit value Vdrv.

Abstract: A vibrating gyroscope includes two input buffers each arranged to input voltage signals appearing at respective detection electrodes of one of two piezoelectric vibrators. An adding circuit adds up output voltages of the respective input buffers. An amplitude control circuit automatically controls a loop gain such that an output voltage of the adding circuit has a substantially constant amplitude. A phase-shift circuit controls the phase of a drive voltage supplied to the piezoelectric vibrators such that the piezoelectric vibrators oscillate by positive feedback. Two differential amplifier circuits each amplify a voltage difference corresponding to an angular velocity about an axis. Two synchronous detection circuits each perform detection using a synchronizing signal generated from an oscillation signal, and detect a voltage signal corresponding to the angular velocity.

Abstract: An angular velocity detection apparatus includes an angular velocity detection signal amplifier circuit which amplifies an angular velocity detection signal Vo output from an angular velocity sensor, and an offset control circuit which controls an offset so as to be a reference voltage which is output when a value of an angular velocity is 0. The angular velocity detection apparatus further includes an input switch circuit which selects the reference voltage and a discharge switch circuit which short-circuits a capacitor included in a high-pass filter in an offset control period.

Abstract: In a method of setting temperature characteristics of an angular velocity sensor, temperature characteristics of a detuning frequency are acquired. The detuning frequency is a frequency difference between an oscillation frequency of an oscillation circuit including a piezoelectric vibrator and a frequency of a voltage of the piezoelectric vibrator caused by the Coriolis force. The sensitivity to the detuning frequency is acquired. The temperature characteristics of a detection phase are acquired. The detection phase is a phase difference between a Coriolis signal phase that corresponds to a phase angle of a voltage signal and an oscillation signal phase of the oscillation circuit. The sensitivity to the detection phase is acquired. The amount of phase shift of the detection phase is determined so that the change in sensitivity caused by the change in the detuning frequency with temperature is controlled using the change in sensitivity caused by the change in the detection phase with temperature.

Abstract: A sound recording apparatus for equalizing a sound signal before the sound signal is recorded onto a recording medium includes an amplifier to which the sound signal is inputted and a simulated inductor circuit connected to the amplifier. The simulated inductor circuit includes a buffer whose input side is coupled to a predetermined bias, a plurality of capacitors for connecting the output side of the buffer to the amplifier, and a switch for changing an equalizing characteristic by changing over a capacitor among the plurality of capacitors.

Abstract: A sound recording apparatus for use in video tape recorders, for equalizing a sound signal before the sound signal is recorded onto a recording medium includes an operational amplifier where the sound signal is inputted to its first input terminal, a feedback resistor connected to an output terminal and a second input terminal of the operational amplifier, and a simulated inductor circuit connected to the second input terminal of the operational amplifier. The simulated inductor circuit has a buffer where a predetermined bias is provided to its input. Between an output of the buffer and the second input terminal of the operational amplifier is connected an impedance network whose circuit constant is switched by a switch which operates according to a recording speed mode of the video tape recorder. This switching changes an equalizing characteristic of the amplifier.