Angular velocity sensor

• US 10,132,631 B2
• Filed: 04/17/2015
• Issued: 11/20/2018
• Est. Priority Date: 04/23/2014
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sakai, Minekazu, Yoshida, Naoki, Sugimoto, Kiyomasa
• Primary Examiner(s): Kwok, Helen C
• Application Number:
  US15/123,756
• Publication Number:
  US 20170016724A1
• Time in Patent Office: 1,313 Days
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5614 Signal processing
• CPC Class Codes: G01C 19/5621 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5628 Manufacturing; Trimming; Mounting; Housings
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams
• CPC Class Codes: H03H 9/21 Crystal tuning forks
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals

Abstract

An angular velocity sensor includes a first substrate having first and second surfaces, a vibrating member disposed on the first substrate and including a drive piece capable of vibrating along the first substrate, a second substrate disposed on the first surface side, a first drive piece control electrode, a first drive piece auxiliary electrode, and a first drive piece control circuit applying a voltage to the first drive piece auxiliary electrode. The first drive piece control circuit adjusts, based on the capacitance generated between the first drive piece control electrode and the first drive piece auxiliary electrode, the voltage to be applied to the first drive piece auxiliary electrode to maintain a constant distance between the first drive piece control electrode and the first drive piece auxiliary electrode.

Claims

1. An angular velocity sensor comprising:

a first substrate including a first surface and a second surface, the second surface being disposed opposite to the first surface;

a vibrating member disposed on the first substrate and including a drive piece, wherein the drive piece is capable of vibrating in a plane direction of the first substrate, and the vibrating member detects an angular velocity applied to a plane of the first substrate during a vibration of the drive piece;

a second substrate disposed on a side of the first surface of the first substrate;

a first drive piece control electrode disposed on a portion of the drive piece close to the second substrate;

a first drive piece auxiliary electrode disposed on a portion of the second substrate facing a displaceable region of the first drive piece control electrode disposed on the drive piece, wherein a first auxiliary region of the first drive piece auxiliary electrode is disposed opposing an entire first control region of the displaceable region of the first drive piece control electrode, and wherein a capacitance is generated between the first drive piece auxiliary electrode and the first drive piece control electrode; and

a first drive piece control circuit applying a voltage to the first drive piece auxiliary electrode,

wherein the first drive piece control circuit adjusts, based on the capacitance generated between the first drive piece control electrode and the first drive piece auxiliary electrode, the voltage to be applied to the first drive piece auxiliary electrode so that a distance between the first drive piece control electrode and the first drive piece auxiliary electrode is maintained to be constant over the entire first control region of the displaceable region of the first drive piece control electrode.

2. The angular velocity sensor according to claim 1, further comprising:

a third substrate disposed on a side of the second surface of the first substrate;

a second drive piece control electrode disposed on a portion of the drive piece close to the third substrate;

a second drive piece auxiliary electrode disposed on a portion of the third substrate facing the displaceable region of the second drive piece control electrode disposed on the drive piece, wherein a second auxiliary region of the second drive piece auxiliary electrode is disposed opposing an entire second control region of the displaceable region of the second drive piece control electrode, and wherein a capacitance is generated between the second drive piece auxiliary electrode and the second drive piece control electrode; and

a second drive piece control circuit applying a voltage to the second drive piece auxiliary electrode,

wherein the second drive piece control circuit adjusts, based on the capacitance generated between the second drive piece control electrode and the second drive piece auxiliary electrode, the voltage to be applied to the second drive piece auxiliary electrode so that a distance between the second drive piece control electrode and the second drive piece auxiliary electrode is maintained to be constant over the entire second control region of the displaceable region of the second drive piece control electrode.

3. The angular velocity sensor according to claim 1, wherein

the drive piece is referred to as a first drive piece,

the vibrating member further includes:

a second drive piece;

a detection piece disposed between the first drive piece and the second drive piece; and

a base portion holding the first drive piece, the second drive piece, and the detection piece,

the angular velocity sensor further comprises;

a first detection piece control electrode disposed on a portion of the detection piece close to the second substrate;

a first detection piece auxiliary electrode disposed on a portion of the second substrate facing a displaceable region of the first detection piece control electrode disposed on the detection piece and wherein a first auxiliary region of the first detection piece auxiliary electrode is disposed opposing an entire first control region of the displaceable region of the first detection piece control electrode, and wherein a capacitance is generated between the first detection piece auxiliary electrode and the first detection piece control electrode; and

a first detection piece control circuit applying a voltage to the first detection piece auxiliary electrode, and

the first detection piece control circuit adjusts, based on the capacitance generated between the first detection piece control electrode and the first detection piece auxiliary electrode, the voltage to be applied to the first detection piece auxiliary electrode so that a distance between the first detection piece control electrode and the first detection piece auxiliary electrode is maintained to be constant over the entire first control region of the displaceable region of the first detection piece control electrode.

4. The angular velocity sensor according to claim 2, wherein

the drive piece is referred to as a first drive piece,

the vibrating member further includes:

a second drive piece;

a detection piece disposed between the first drive piece and the second drive piece; and

a base portion holding the first drive piece, the second drive piece, and the detection piece,

the angular velocity sensor further comprises;

a first detection piece control electrode disposed on a portion of the detection piece close to the second substrate;

a second detection piece control electrode disposed on a portion of the detection piece close to the third substrate;

a first detection piece auxiliary electrode disposed on a portion of the second substrate facing a displaceable region of the first detection piece control electrode disposed on the detection piece and wherein a first auxiliary region of the first detection piece auxiliary electrode is disposed opposing an entire first control region of the displaceable region of the first detection piece control electrode, and wherein a first capacitance is generated between the first detection piece auxiliary electrode and the first detection piece control electrode;

a second detection piece auxiliary electrode disposed on a portion of the third substrate facing the displaceable region of the second detection piece control electrode disposed on the detection piece and wherein a second auxiliary region of the second detection piece auxiliary electrode is disposed opposing an entire second control region of the displaceable region of the second detection piece control electrode, and wherein a second capacitance is generated between the second detection piece auxiliary electrode and the second detection piece control electrode;

a first detection piece control circuit applying a voltage to the first detection piece auxiliary electrode; and

a second detection piece control circuit applying a voltage to the second detection piece auxiliary electrode,

the first detection piece control circuit adjusts, based on the capacitance generated between the first detection piece control electrode and the first detection piece auxiliary electrode, the voltage to be applied to the first detection piece auxiliary electrode so that a distance between the first detection piece control electrode and the first detection piece auxiliary electrode is maintained to be constant over the entire first control region of the displaceable region of the first detection piece control electrode, and

the second detection piece control circuit adjusts, based on the capacitance generated between the second detection piece control electrode and the second detection piece auxiliary electrode, the voltage to be applied to the second detection piece auxiliary electrode so that a distance between the second detection piece control electrode and the second detection piece auxiliary electrode is maintained to be constant over the entire second control region of the displaceable region of the second detection piece control electrode.

5. The angular velocity sensor according to claim 1, wherein

the vibrating member further includes:

a driving movable electrode as the drive piece; and

a detection movable electrode, and

the first substrate further includes;

a driving fixed electrode disposed on the first substrate to face the driving movable electrode, and an electrostatic force is generated between the driving fixed electrode and the driving movable electrode to vibrate the vibrating member; and

a detection fixed electrode disposed on the first substrate to face the detection movable electrode.