Denso Corporation

Nippon Soken, Inc.

Takaaki Kawai

Yasuyuki Okuda

Makiko Sugiura

Junji Hayakawa

Mitsuyasu Matsuura

Takahiko Yoshida

Toshiki Isogai

Hisanaga Matsuoka

Akinobu Umemura

Tetsuo Fujii

Hirofumi Higuchi

Minoru Murata

Teruo Oda

Tetsuo Yoshioka

Norio Kitao

Takayuki Ishikawa

Kenji Fukumura

Hirokazu Ito

An ultrasonic sensor includes a transmitting device, a receiving device, and a circuit device. The circuit device determines that the receiving device receives an ultrasonic wave reflected from an object, when an output voltage of the receiving device is equal to or greater than a first threshold. The circuit device includes a humidity detection section configured to detect an ambient humidity of the transmitting and receiving devices and a threshold adjustment section configured to calculate, based on the detected ambient humidity, a sound pressure of the ultrasonic wave that is received by the receiving device after propagating over a round-trip distance between the ultrasonic sensor and the object. The threshold adjustment section reduces the first threshold, when the output voltage corresponding to the calculated sound pressure is less than a second threshold that is greater the first threshold.

Ultrasonic sensor

A concentration sensor device includes a sensor unit, a substrate, and a sedimentation limit unit. The sensor unit detects a concentration of a specific component contained in liquid. The substrate has a face to which the sensor unit is arranged. The sedimentation limit unit is integrally arranged with the sensor unit or arranged at an upstream side of the sensor unit in a flowing direction of the liquid. The sedimentation limit unit is configured to prevent sedimentation of a foreign object on the sensor unit. The sedimentation limit unit includes a piezoelectric element to vibrate when electricity is supplied so as to promote the foreign object to be separated from the sensor unit. The substrate has a recess recessed in a thickness direction of the substrate.

Concentration sensor device and concentration detecting method

An ultrasonic sensor includes a transmitting device, receiving devices arranged in an array, and a circuit device. One receiving device is configured as a reference receiving device. The circuit device includes a reference signal generator and first and second synchronous detectors. The reference signal generator generates a reference signal by using a received signal of the reference receiving device. The first synchronous detector performs synchronous detection of a received signal of one of the receiving devices based on the reference signal to detect a distance to an object. The second synchronous detector performs synchronous detection of received signals of the receiving devices except the reference receiving device based on the reference signal to detect a direction of the object.

Ultrasonic sensor with piezoelectric elements and acoustic matching members

A substrate forming a sensor element is connected to a non-inverting input terminal of an operational amplifier, and a common voltage is applied thereto from a reference voltage supply circuit to fix them to the same potential. Thus, the impedances of the non-inverting input terminal and of the inverting input terminal of the operational amplifier are matched with respect to the power source. Therefore, noise superposed on a power source line can be greatly decreased by noise-removing characteristics determined by CMRR characteristics of the operational amplifier. As a result, a capacitive-type acceleration sensor exhibits sensor characteristics of frequency noise suppressing effect.

Capacitive-type physical quantity sensor

An output signal cutting-off circuit includes a first switching element, a driving circuit and a voltage-drop-signal generating circuit. When a voltage to be monitored becomes lower than a threshold voltage, a voltage-drop-signal is generated and supplied to the driving circuit. The driving circuit turns on the first switching element based on the voltage-drop-signal to thereby cut off an output signal voltage by bringing it to a ground potential. When the voltage-drop-signal disappears, the first switching element is turned off to bring the output signal to a normal state. Preferably, a second switching element for charging a capacitor and a third switching element for discharging the capacitor are used in the driving circuit. In this case, the first switching element is turned on or off based on a voltage of the capacitor.

Circuit for cutting-off output signal

A physical quantity (e.g., acceleration) sensing unit is provided. In this unit, a capacitive sensor has first and second fixed electrodes and a physical-quantity-sensitive movable electrode disposed between the first and second fixed electrodes. An adjusting circuit first adjusts a first bias voltage applied between the first fixed electrode and the movable electrode and a second voltage applied between the movable electrode and the second fixed electrode so that the movable electrode is brought into contact with either the first or second fixed electrode. The adjusting circuit then adjusts the first and second bias voltages to return the movable electrode to its original position. A detecting circuit detects an output on a capacitance relationship among the first and second fixed electrodes and the movable electrode. The output is subjected to determination of whether or not the output is out of order, when tested.

Method and unit for sensing physical quantity using capacitive sensor

In a capacitive physical quantity sensor, a C-V converter converts a variation in a capacitance between a movable electrode and a fixed electrode into a voltage to output the converted voltage in a first operating mode. The C-V converter also outputs a constant voltage in a second operating mode. An amplifier amplifies the converted voltage to output a first voltage, and amplifies the constant voltage to output a second voltage. A first sample and hold circuit operates in the first operating mode to sample and hold the first voltage. A second sample and hold circuit operates in the second operating mode to sample and hold the second voltage. A first differential amplifier obtains a difference voltage between the first voltage held by the first sample and hold circuit and the second voltage held by the second sample and hold circuit.

Growing community of inventors

Obu, Japan

Takaaki Kawai