Composite sensor

• US 5,894,091 A
• Filed: 05/13/1997
• Issued: 04/13/1999
• Est. Priority Date: 05/30/1996
• Status: Expired due to Fees

• Current Assignee: Sensata Technologies Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kubota, Tomoyuki
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US08/855,411
• Time in Patent Office: 700 Days
• Field of Search: 73/504.04, 73/504.12, 73/504.14, 73/510, 73/514.18, 73/514.24, 73/514.32, 73/514.38, 361/280
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends

Abstract

Fixed electrodes (A through F) are formed by means of a structural layer that has been provided on fixed bodies (7₁ through 7₄) of a silicon micro-machined substrate and a movable electrode (G) is formed by a movable body attached to fixed bodies (5₁ through 5₄) by flexible members (6₁ through 6₄). Variable capacitors of the parallel plate-type are formed by the movable electrode (G) and the fixed electrodes (A through F). When the movable electrode (G) has been vibrated, the Coriolis force incident to rotation or the force incident to acceleration are added to the movable electrode (G), with a result that the charge of the various variable capacitors change. By detecting the change in charge, both angular velocity and acceleration can be obtained. By providing another variable capacitor formed by a mass portion (H) by a movable body and the substrate, acceleration components in the directions of three axes can be detected.

Claims

1. A solid state composite sensor comprising:

a stationary substrate having spaced support portions for mounting a movable electrode member,

a respective flexible arm attached to each support portion,

a movable electrode member formed generally in an X-shaped configuration having four legs, each leg attached to a respective flexible arm, the legs extending and attached to a central portion, a plurality of elongated teeth lying in a common plane which includes mutually perpendicular X and Y directions and extending outwardly from each leg, the teeth of each leg in each of the X and Y directions being in parallel relationship with one another, and

stationary electrodes having a plurality of elongated teeth lying in the common plane and interdigitated with the elongated teeth of the movable electrode in parallel relationship with adjacent teeth of the movable electrode to form therewith parallel plate-type variable capacitors responsive to movement of the movable electrode in the X and Y directional components of movement parallel to the common plane.

2. A solid state composite sensor according to claim 1 in which each leg has a longitudinal axis and the teeth extend from either side of the leg at an angle of 45 degrees from the respective axis.

3. A solid state composite sensor according to claim 1 in which the central portion forms a movable electrode forming a parallel plate-type variable capacitor with a stationary electrode formed on the stationary substrate responsive to movement of the central portion in a direction perpendicular to the common plane.

4. A solid state composite sensor according to claim 1 in which the stationary substrate and the movable and stationary electrodes are composed of monocrystalline silicon.

5. A solid state composite sensor according to claim 1 further comprising means to cyclically impress a voltage across the variable capacitors to vibrate the movable electrode and means to detect the Coriolis force added to the movable electrode by the change in charge on the variable capacitor upon rotary movement of the sensor and calculate the angular velocity of the sensor.

6. A solid state composite sensor according to claim 5 in which the variable capacitors are impressed with a voltage every half cycle of the vibration and the charge on the variable capacitors are monitored during every other half cycle when voltage is not impressed.