Murata Manufacturing Co., Ltd.

Asahi Kasei Microdevices Corporation

Yoshitaka Kato

Akira Mori

Makoto Narita

Ville-Pekka Rytkönen

Yoshihiko Koizumi

Tomoyasu Hasegawa

Kaneo Yaji

Akira Konno

Satoshi Ichihara

The present invention relates to capacitive micromechanical accelerometers, and in particular to acceleration sensors with movable rotors which may rotate out of a substrate plane when the accelerometer undergoes movement with an acceleration component perpendicular to the substrate plane. The capacitive micromechanical accelerometer includes additional damping springs to reduce unwanted movement of the rotor in the substrate plane, thereby reducing the parasitic capacitance that results from motion of the rotor in the substrate plane. The damping springs are vertically recessed with respect to other components of the accelerometer in order to minimise the effect of the damping springs on movement of the rotor out of the substrate plane.

Capacitive micromechanical accelerometer

A sensor structure and a method for operating a vibrating sensor of angular velocity comprising a rotor mass and two linearly moving masses is disclosed. The sensor structure and method comprises a rotor mass, two linearly moving masses, and two T-shaped levers each coupled with the two linearly moving masses and to the rotor mass. The T-shaped levers enable the rotor mass and the two linearly moving masses to be excited into an anti-phase primary mode, where the direction of angular momentum of the rotor mass is opposite to the direction of angular momenta of the linearly moving masses. Angular momenta of the rotor mass and the linearly moving masses cancel each other to a high extent, so that the total sum of angular momentum of the structure is very small. Nominal frequency of the anti-phase primary mode is distinctively low as compared to nominal frequencies of other possible primary modes, such as a parallel phase primary mode.

Vibrating micro-mechanical sensor of angular velocity

A sensor element, for detecting angular velocity about a detection axis perpendicular to a plane of the sensor element, comprises two primary masses and two Coriolis masses, and two sensing cells. Two coupling levers are each coupled to the two primary masses by first springs and to one of the two Coriolis masses by second springs. The coupling levers enable the primary masses and Coriolis masses to be excited into a combined primary motion in the plane of the planar sensor element. In the primary motion, a direction of angular momenta of linear primary oscillation motions of the primary masses and angular momenta of rotational primary motions of the coupling levers with respect to the geometrical centroid of the sensor element is opposite to the direction of the angular momenta of linear primary oscillation motions of the Coriolis masses with respect to the geometrical centroid of the sensor element.

Micro-mechanical sensor element of angular velocity

An inertia force sensor that shortens a time from power activation until inertia force can be detected includes an oscillator, an oscillation circuit unit, and a detection circuit unit. The oscillation circuit unit functions as a closed loop self oscillation circuit with the oscillator as a resonant element, and includes a CV conversion circuit converting a monitor signal based on electrostatic capacitance according to an oscillating state of oscillator into a monitor signal based on a voltage corresponding to an amount in change of the electrostatic capacitance, and an automatic gain control circuit controlling gain based on the monitor signal converted at the CV conversion circuit to generate a driving signal, and supplying the driving signal to the oscillator. The CV conversion circuit includes an amplifier that amplifies a monitor signal with an amplification factor for a predetermined period after power activation.

Oscillation type inertia force sensor

An oscillation type inertia force sensor includes an oscillator, an oscillation circuit unit, and a detection circuit unit. The oscillation circuit unit functions as a self oscillation circuit of a closed loop with the oscillator as a resonant element, and includes an AGC circuit. The AGC circuit includes a VGA circuit, a comparison circuit comparing a predetermined reference voltage with a voltage of the monitor signal to output a control signal based on the compared result, and a pulse width modulation circuit modulating the control signal to a pulse width modulation signal. Based on the pulse width modulation signal, the driving signal is modulated with the output of the VGA circuit switched between an ON state and OFF state to control the degree of the amplification factor of the VGA circuit.

An external-force detecting apparatus includes at least one drive line connecting the corresponding drive electrodes to a driving unit and at least one monitor line connecting the corresponding monitor electrodes to the driving unit. The driving unit outputs a drive signal to the at least one of the drive electrodes through the at least one of the drive lines to drive an oscillator and performs automatic gain control to the level of the drive signal based on the oscillation state of the oscillator acquired from the at least one of the monitor electrodes through the at least one of the monitor lines. The external-force detecting apparatus further includes a switching circuit arranged to switch between connection and disconnection of an electric path between the oscillator and the driving unit via at least one of the drive lines or the multiple monitor lines.

External-force detecting apparatus and method of detecting line break

An angular velocity measuring device includes an angular having a mounting surface on which a velocity detection element, element-side drive electrodes and element-side detection electrodes are provided and a ground electrode is disposed between the drive electrodes and the detection electrodes. On the top surface of a multilayer substrate, substrate-side drive electrodes and substrate-side detection electrodes are provided and a ground electrode is disposed between the drive electrodes and the detection electrodes. The electrodes of the angular velocity detection element are connected to the electrodes of the multilayer substrate and the two ground electrodes are arranged to face each other. Furthermore, on the top surface of the multilayer substrate, drive wirings connected to the drive electrodes are provided and, inside the multilayer substrate, detection wirings connected to the detection electrodes are provided. Ground wirings sandwiching the detection wirings in the thickness direction are disposed in the multilayer substrate.

Angular velocity measuring device

A vibrating sensor device is disposed on the obverse or reverse surface of a substrate. A signal processing circuit is disposed on the other surface of the substrate. First and second detecting wiring patterns, through which detection signals generated based on a vibration of a vibrator of the vibrating sensor device caused by a Coriolis force pass, extend from the vibrating sensor device in opposite directions. First and second driving wiring patterns for respectively allowing first and second driving signals, which are 180 degrees out of phase with each other, to pass therethrough extend from the vibrating sensor device in opposite directions. The above-described wiring patterns are disposed so that the capacitances between the adjacent wiring patterns become substantially equal to each other.

Growing community of inventors

Nagaokakyo, Japan

Yoshitaka Kato