Angular velocity signal detection circuit and angular velocity signal detection method

• US 8,297,120 B2
• Filed: 08/28/2008
• Issued: 10/30/2012
• Est. Priority Date: 08/31/2007
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Shoji, Kohei, Fuchikami, Takaaki
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US12/674,992
• Publication Number:
  US 20110107836A1
• Time in Patent Office: 1,524 Days
• Field of Search: 735/040.2, 735/10, 735/041.2, 735/140.2
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/00 Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects

Abstract

An angular velocity signal detection circuit includes: a first current-voltage conversion circuit that converts, into a voltage, a current outputted from a first detection electrode of a gyroscope, and amplifies the voltage, thereby outputs a first conversion signal; a second current-voltage conversion circuit that converts, into a voltage, a current outputted from a second detection electrode of the gyroscope, and amplifies the voltage, thereby outputs a second conversion signal; an arithmetic operation unit that performs arithmetic operations by using the first conversion signal and the second conversion signal, and outputs a first processing signal and a second processing signal; and a third difference arithmetic operation circuit that amplifies a difference between the first processing signal and the second processing signal.

Claims

1. An angular velocity signal detection circuit comprising:

a first current-voltage conversion circuit configured to convert a current outputted from a first detection electrode of a gyroscope into a first voltage, and to amplify the first voltage, to thereby output a first conversion signal;

a second current-voltage conversion circuit configured to convert a current outputted from a second detection electrode of the gyroscope into a second voltage, and to amplify the second voltage, to thereby output a second conversion signal;

an arithmetic operation unit configured to perform arithmetic operations by using the first conversion signal and the second conversion signal, and to output a first processing signal and a second processing signal; and

a difference arithmetic operation circuit configured to amplify a difference between the first processing signal and the second processing signal, to thereby output a signal indicative of angular velocity.

2. The angular velocity signal detection circuit of claim 1, wherein the arithmetic operation unit comprises:

an adding circuit configured to add the second conversion signal to the first conversion signal, and generate a reference signal;

a first difference arithmetic operation circuit configured to generate a first difference signal by a difference arithmetic operation between the first conversion signal and the reference signal, and output the first difference signal as the first processing signal; and

a second difference arithmetic operation circuit configured to generate a second difference signal by a difference arithmetic operation between the second conversion signal and the reference signal, and output the second difference signal as the second processing signal.

3. The angular velocity signal detection circuit of claim 2, further comprising:

a phase shift circuit configured to generate a timing signal for synchronous detection from the reference signal;

a synchronous detection circuit configured to synchronize an alternating current signal outputted from the difference arithmetic operation circuit with the timing signal, and convert the alternating current signal into a direct current signal; and

a direct current amplifier circuit configured to amplify the direct current signal outputted from the synchronous detection circuit.

4. The angular velocity signal detection circuit of claim 1, further comprising a drive circuit connected to a drive electrode of the gyroscope.

5. The angular velocity signal detection circuit of claim 1, wherein the arithmetic operation unit comprises:

a first amplifier-limiter circuit configured to amplify the first conversion signal up to before saturation of the first conversion signal, to thereby generate a first amplification signal, and output the first amplification signal as the first processing signal; and

a second amplifier-limiter circuit configured to amplify the second conversion signal up to before saturation of the second conversion signal, to thereby generate a second amplification signal, and output the second amplification signal as the second processing signal.

6. The angular velocity signal detection circuit of claim 5, further comprising:

a first phase adjustment circuit arranged between the first current-voltage conversion circuit and the first amplifier-limiter circuit, the first phase adjustment circuit adjusting a shift between a phase of the first detection signal outputted from the first detection electrode and a phase of the second detection signal outputted from the second detection electrode; and

a second phase adjustment circuit arranged between the second current-voltage conversion circuit and the second amplifier-limiter circuit, the second phase adjustment circuit adjusting a shift between the phase of the first detection signal and the phase of the second detection signal.

7. An angular velocity signal detection method comprising:

converting a current outputted from a first detection electrode of a gyroscope into a first voltage, and amplifying the first voltage, thereby generating a first conversion signal;

converting a current outputted from a second detection electrode of the gyroscope into a second voltage, and amplifying the second voltage, thereby generating a second conversion signal;

performing arithmetic operations by using the first conversion signal and the second conversion signal, and generating a first processing signal and a second processing signal; and

amplifying a difference between the first processing signal and the second processing signal, thereby generating an output signal indicative of angular velocity.

8. The angular velocity signal detection method of claim 7, wherein performing the arithmetic operations by using the first conversion signal and the second conversion signal comprises:

adding the first conversion signal and the second conversion signal to each other, and generating a reference signal;

generating a first difference signal by a difference arithmetic operation between the first conversion signal and the reference signal, and outputting the first difference signal as the first processing signal; and

generating a second difference signal by a difference arithmetic operation between the second conversion signal and the reference signal, and outputting the second difference signal as the second processing signal.

9. The angular velocity signal detection method of claim 7, wherein performing the arithmetic operations by using the first conversion signal and the second conversion signal comprises:

amplifying the first conversion signal up to before saturation of the first conversion signal, thereby generating a first amplification signal, and outputting the first amplification signal as the first processing signal; and

amplifying the second conversion signal up to before saturation of the second conversion signal, thereby generating a second amplification signal, and outputting the second amplification signal as the second processing signal.