Inertial force sensor including a sense element, a drive circuit, a sigma-delta modulator and a signal processing circuit
View Patent ↗The present invention particularly relates to an inertial force sensor used in various electronic equipment, for example, used for altitude control, navigation, or the like, of a mobile body such as an aircraft, an automobile, a robot, a watercraft and a vehicle in which the detection accuracy is enhanced. Therefore, a sense circuit constituting the inertial force sensor includes a sigma-delta modulator converting a sense signal output from a sense electrode into a one-bit digital signal, and a signal processing circuit (i) comparing a monitor signal output from a monitor electrode with predetermined reference amplitude information, (ii) carrying out operation processing of the one-bit digital signal based on this comparison information, and (iii) adjusting an output level of the output signal.
1. An inertial force sensor comprising:
a sense element including a drive electrode, a sense electrode and a monitor electrode, the monitor electrode outputting a monitor signal corresponding to an oscillation of the sense element;
a drive circuit for driving the sense element at a predetermined driving frequency; and
a sense circuit for electrically processing a signal output from the sense electrode,
wherein the sense circuit includes:
a sigma-delta modulator for converting the signal output from the sense electrode into a one-bit digital signal; and
a signal processing circuit for comparing the monitor signal with predetermined reference amplitude information, carrying out operation processing of the one-bit digital signal based on a result of the comparing, and adjusting an output level of the signal output from the sense electrode.
2. An inertial force sensor comprising:
a sense element including a drive electrode, a sense electrode and a monitor electrode;
a drive circuit for detecting a monitor signal output from the monitor electrode and forming a drive signal with respect to the drive electrode; and
a sense circuit for electrically processing a sense signal output from the sense electrode,
wherein the drive circuit:
sigma-delta converts the monitor signal output from the monitor electrode into a one-bit digital signal so as to generate amplitude information;
compares the amplitude information with predetermined reference amplitude information so as to generate comparison information;
carries out operation processing of the monitor signal based on the generated comparison information so as to convert the monitor signal into a multi-bit signal;
converts the multi-bit signal into a predetermined output form of a signal; and
outputs the predetermined output form of the signal to the drive electrode, and
wherein the operation processing of the monitor signal includes operating a rectangular wave signal formed from the monitor signal with the comparison information.
3. The inertial force sensor of claim 2 , wherein the multi-bit signal is converted into a one-bit digital signal by sigma-delta conversion, and the one-bit digital signal converted from the multi-bit signal is output to the drive electrode.
4. The inertial force sensor according to claim 1 , wherein the signal processing circuit filters the one-bit digital signal after carrying out the operation processing of the one-bit digital signal, the one-bit digital signal being filtered based on the comparison information.
5. The inertial force sensor according to claim 1 , wherein the signal processing circuit filters the one-bit digital signal after the one-bit digital signal is substituted with a value decided from the result of the comparing.
6. An inertial force sensor comprising:
a sense element including a drive electrode, a sense electrode and a monitor electrode, the monitor electrode outputting a monitor signal corresponding to an oscillation of the sense element;
a drive circuit for detecting the monitor signal and forming a drive signal with respect to the drive electrode; and
a sense circuit for electrically processing a sense signal output from the sense electrode,
wherein the drive circuit:
sigma-delta converts the monitor signal output from the monitor electrode into a one-bit digital signal and generates a digital value and amplitude information of the monitor signal;
compares the amplitude information with predetermined reference amplitude information so as to generate comparison information;
carries out operation processing of the one-bit digital signal based on the generated comparison information so as to convert the one-bit digital signal into a multi-bit drive signal;
converts the multi-bit drive signal into a predetermined output signal; and
outputs the predetermined output signal to the drive electrode.