Angular rate sensor

An angular rate sensor comprising:

• an exciting unit for providing a vibrator with vibration;
• a means for detecting a signal of a vibration level of said vibrator;
• a first detection means for detecting a Coriolis' force generated responsive to an angular rate;
• a second detection means for detecting a signal of reverse polarity to that of said first detection means;
• a driving circuit for taking a signal from said means of detecting vibration level as an input, and outputting a signal to said exciting unit;
• a first detection circuit wherein detected signals are being input from said first detection means;
• and
• a second detection circuit wherein detected signals are being input from said second detection means, wherein an abnormal condition of said angular rate sensor being detectable from outputs of said first and second detection means,
• wherein said driving circuit comprises:
• a first amplifier for taking as an input an electric charge generated in said means of detecting vibration level;
• a rectifier for rectifying an output voltage of said first amplifier;
• a smoothing circuit for smoothing an output voltage of said rectifier;
• a variable gain amplifier for taking as an input an output voltage of said first amplifier, wherein an amplification factor varies according to an output voltage of said smoothing circuit;
• a second amplifier for amplifying an output voltage of said variable gain amplifier;
• and
• a third amplifier for producing an output of a phase reverse to said second amplifier, and
• further wherein said first detection circuit and said second detection circuit respectively comprise:
• a fourth amplifier and a fifth amplifier for taking as input electric charges produced in said first detection means and said second detection means, and outputting voltages proportional to amounts of these input electric charges;
• a first phase detector and a second phase detector for carrying out phase detection with a timing signal in the output signal of said first amplifier, after shifting phases of the output voltages of said fourth amplifier and said fifth amplifier respectively by 90 degrees, or
• another first phase detector and another second phase detector for carrying out phase detection of the output voltages of said fourth amplifier and said fifth amplifier respectively with a timing signal derived by shifting a phase of the output signal of said first amplifier by 90 degrees;
• a first low pass filter and a second low pass filter for smoothing output signals of said first phase detector and said second phase detector respectively;
• and
• a first adjustment means and a second adjustment means for DC-amplifying output voltages of said first low pass filter and said second low pass filter, said first and second adjustment means having functions of amplification factor adjustment, offset adjustment and temperature adjustment for the offset.