Digital flexure beam accelerometer and method

• US 5,526,688 A
• Filed: 04/26/1994
• Issued: 06/18/1996
• Est. Priority Date: 10/12/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Sampsell, Jeffrey B., Boysel, Robert M.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Oda, Christine K.
• Application Number:
  US08/233,838
• Time in Patent Office: 784 Days
• Field of Search: 200/61.45 R, 200/61.48, 200/61.49, 200/61.51, 200/61.53, 73/651, 73/517 R, 73/652
• US Class Current: 73/514.38
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass

Abstract

An accelerative force may be measured using a plurality of deflection elements (102), each deflection element (102) comprising an inertial mass (104), and at least one hinge (104) supporting the inertial mass (104) in a normal position. Application of a force to inertial mass (104) will result in the deflection of the inertial mass (104) in a first direction out of the normal position. The movement of the inertial mass (104) from the normal position stores energy in the hinges (108) which tends to move the inertial mass (104) in a second direction back to its normal position. Either the mass of the inertial mass (104), or the compliance of the hinges (108) is varied from one deflection element (102) in the array to another so that the force applied to the inertial masses (104) by simultaneous acceleration of the deflection elements (102) deflects some of the inertial masses (104). A detection means (112) senses if inertial masses (104) have deflected and produces an output representative of the applied force.

Claims

1. A structure for detecting acceleration comprising the following:

a substrate;

readout circuitry formed in said substrate;

an electrical contact formed on said substrate and in communication with said readout circuitry;

a shield plane on said substrate surrounding said electrical contact;

at least one support structure formed on said substrate;

a first layer of metal supported by said at least one support structure, said first layer of metal forming hinges; and

an inertial mass supported by said hinges, said inertial mass formed from a second layer of metal and located opposite said substrate from said electrical contact, wherein when said structure is subjected to an acceleration said inertial mass is deflected toward said substrate until said inertial mass contacts said electrical contact, said contact between said inertial mass and said electrical contact detected by said readout circuitry.

2. The structure of claim 1, wherein said substrate is silicon.

3. The structure of claim 1, wherein said readout circuitry is CMOS.

4. The structure of claim 1, where in said contact is aluminum alloy.

5. The structure of claim 1, wherein said at least one support structure is an aluminum post.

6. The structure of claim 1, wherein said at least one support structure is a photoresist.

7. The structure of claim 1 wherein said thin metal is an aluminum alloy.

8. The structure of claim 1 wherein said thin metal is a tungsten alloy.

9. The structure of claim 1 wherein said thick metal is a tungsten alloy.