Inertia force sensor
View Patent ↗When detecting an angular rate in a detecting element ( 1 ), when an angular rate occurs, it is detected on the basis of a first sum by adding output values issued from upper electrode of second sensing electrode part ( 19 b ) and upper electrode of fourth sensing electrode part ( 20 b ) both in positive polarity, a second sum by adding output values issued from upper electrode of first sensing electrode part ( 19 a ) and upper electrode of third sensing electrode part ( 20 a ) both in negative polarity, a third sum by adding output values issued from lower electrode of first sensing electrode part ( 19 a ) and lower electrode of third sensing electrode part ( 20 a ) both in positive polarity, and a fourth sum by adding output values issued from lower electrode of second sensing electrode part ( 19 b ) and lower electrode of fourth sensing electrode part ( 20 b ) both in negative polarity. In this configuration, the inertial force sensor enhanced in detection sensitivity is presented.
1. An inertial force sensor comprising:
a detecting element having a plurality of sensing parts being disposed on an elastic element for sensing the strain of the elastic element, and
detecting circuit parts connected to the sensing parts for detecting the inertial force applied to the elastic element,
wherein the sensing parts have sensing electrode parts each composed of an upper electrode and a lower electrode together with an intervening piezoelectric element, and
the detecting circuit part detects the inertial force applied to the elastic element on the basis of the sum of two output values issued from the upper electrode or lower electrode of the two sensing electrode parts.
2. The inertial force sensor of claim 1 , wherein the sum of the two output values is obtained by addition of two output currents issued from the upper electrode or lower electrode of the two sensing electrode parts mutually in positive polarity or mutually in negative polarity.
3. The inertial force sensor of claim 1 , further comprising:
a driving part disposed on the elastic element for driving and vibrating the elastic element,
wherein the driving part has a driving electrode part composed of an upper electrode and a lower electrode together with an intervening piezoelectric element, and
the detecting circuit part detects the inertial force applied to the elastic element on the basis of the sum of two output values issued from the upper electrode or lower electrode of the two sensing electrode parts, and the sum of the output value issued from the upper electrode or lower electrode of the driving electrode part.
4. The inertial force sensor of claim 3 , wherein the sum of the output values is obtained by addition of output currents issued from the upper electrode or lower electrode of the sensing electrode parts both in positive polarity or both in negative polarity, or from the upper electrode or lower electrode of the driving electrode part.
5. The inertial force sensor of claim 1 , wherein the elastic element has a plurality of second arms, one second arm provided with a first sensing part and other second arm with a second sensing part,
the first sensing part and the second sensing part are individually provided with two sensing electrode parts, and of the four sensing electrode parts, on the basis of:
the sum of adding output values issued from two upper electrodes both in positive polarity,
the sum of adding output values issued from two upper electrodes both in negative polarity,
the sum of adding output values issued from two lower electrodes both in positive polarity, and
the sum of adding output values issued from two lower electrodes both in negative polarity,
the inertial force applied to the elastic element is detected.
6. The inertial force sensor of claim 1 , wherein the elastic element has a plurality of second arms, one second arm provided with a first sensing part and other second arm with a second sensing part,
the first sensing part and the second sensing part are individually provided with two sensing electrode parts, and of the two sensing electrode parts of the first sensing part, on the basis of the sum of adding output values issued from upper electrode and lower electrode both in positive polarity of the first sensing part, the sum of adding output values issued from upper electrode and lower electrode both in negative polarity of the first sensing part, and of the two sensing electrode parts of the second sensing part, on the basis of the sum of adding output values issued from upper electrode and lower electrode both in positive polarity of the second sensing part, and the sum of adding output values issued from upper electrode and lower electrode both in negative polarity of the second sensing part,
the inertial force applied to the elastic element is detected.
7. The inertial force sensor of claim 5 or 6 , wherein the second arms are arranged in two parallel rows, and the first sensing part is provided in one second arm, and the second sensing part is provided in other second arm.
8. The inertial force sensor of claim 3 , wherein the second arms are arranged in two parallel rows on the elastic element, the first sensing part is provided in one second arm, the second sensing part is provided in other second arm, a common support part is provided in the second arms, and relating to the support part of one second arm and other second arm, other second arm is disposed at the opposite side, and further the driving part is provided in other second arm.