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Angular velocity sensor

  • US 6,298,723 B1
  • Filed: 02/15/2000
  • Issued: 10/09/2001
  • Est. Priority Date: 04/04/1995
  • Status: Expired due to Term
First Claim
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1. An angular velocity sensor formed from crystal material having crystal axes, said crystal axes including an electrical axis, a mechanical axis, and an optical axis,said angular velocity sensor comprising four parallel oscillating arms and a first and second support member for commonly holding the four parallel oscillating arms at both ends of each of the four parallel oscillating arms, said angular velocity sensor configured such that a base of said annular velocity sensor extending along a width of said angular velocity sensor is positioned on said electrical axis, a direction along a length of said angular velocity sensor forms an angle θ

  • with said mechanical axis and a direction along a depth of said angular velocity sensor forms the same angle θ

    with said optical axis, two of said four oscillating arms defining a driving side tuning fork and the other two of said four oscillating arms defining a detecting side tuning fork, wherein each of the two oscillating arms of the detecting side tuning fork being cut in a middle portion of a respective oscillating arm such that each of said two oscillating arms of said detecting side tuning fork comprises a first and a second oscillating arm, said first oscillating arm of each of said two oscillating arms of said detecting side tuning fork extending from said first support member and said second oscillating arm of each of said two oscillating arms of said detecting side tuning fork extending from said second support member, each of said first and second oscillating arms of each of said two oscillating arms of said detecting side tuning fork being positioned either outside or inside of said two oscillating arms of said driving side tuning fork, said angular velocity sensor further comprising driving electrodes positioned on face and back surfaces or side surfaces of the driving side tuning fork and detecting electrodes positioned on face and back surfaces or side surfaces of the detecting side tuning fork such that applying an alternating-current power to the driving electrodes in either or both oscillating arms of the driving side tuning fork generates and maintains a width direction flexural oscillation in mutually reverse phases on the driving side tuning fork, wherein when an angular velocity vector rotating and acting on the entire angular velocity sensor is applied from outside, said angular velocity sensor detects an electric charge generated in the detecting electrodes by a thickness direction flexural oscillation in mutually reverse phases on the detecting side tuning fork induced from a driving force of a thickness direction component of Coriolis force acting in an oscillating portion in the width direction of the driving side tuning fork or detecting side tuning fork, thereby obtaining an electrical signal in proportion to an input angular velocity.

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