Multiple level miniature electromechanical accelerometer switch

• US 4,855,544 A
• Filed: 09/01/1988
• Issued: 08/08/1989
• Est. Priority Date: 09/01/1988
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Glenn, Max C.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US07/239,482
• Time in Patent Office: 341 Days
• Field of Search: 200/61.45 R, 200/61.48, 200/61.49, 200/61.51, 200/61.52, 200/61.53, 200/266, 200/267, 200/268, 200/269, 200/181, 307/118, 307/121, 310/329-332, 357/40, 357/58, 357/7, 357/15
• US Class Current: 200/61.45R
• 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
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002

Abstract

An accelerometer switch which has cantilever beams carrying integral end masses formed in a silicon die which is sandwiched between a contact plate and a support plate. Each beam provides switching at a different threshold acceleration level. The fixed contact face of the contact plate is configured with a relief space to permit accelerometer switch operation even though the input acceleration is off-normal and there is twisting of the accelerometer beam.

Claims

1. An accelerometer switch, comprising:

a contact plate;

a backplate;

an accelerometer die formed from a single piece of semiconductor material, said accelerometer die sandwiched between said contact plate and said backplate, said accelerometer die having a plurality of cantilever beams, each said cantilever beam having a fixed end and a free end, each said free end carrying an integral end mass, each said cantilever beam further having a first contact face;

a first electrical contact located on said first face;

a second contact face located on said contact plate and spaced from said first contact face, said second face having a raised portion located to be complementary to said first electrical contact; and

a second electrical contact located on said raised portion such that a threshold acceleration normal to said first contact face will cause bending of said cantilever beam thereby carrying said first electrical contact into engagement with said second electrical contact;

said raised portion allowing said first contact to engage said second contact when said first contact face is tilted due to an offnormal acceleration.

2. The switch of claim 1 including electrical connecting means between said first contact and a switch terminal associated with said first contact.

3. The switch of claim 2 including electrical connecting means between said second contact and a common switch terminal.

4. The switch of claim 3, further comprising:

a pedestal located on said backplate directly below each said end mass for biasing each said first contact more closely toward engagement with each said second contact.