Shunt calibration for electronic pressure switches

• US 20060191346A1
• Filed: 01/26/2006
• Published: 08/31/2006
• Est. Priority Date: 10/02/2003
• Status: Abandoned Application

• Current Assignee: Kulite Semiconductor Products Inc
• Original Assignee: Kulite Semiconductor Products Inc
• Inventors: Kurtz, Anthony D., Landmann, Wolf S.
• Application Number:
  US11/341,398
• Publication Number:
  US 20060191346A1
• Time in Patent Office: Days
• US Class Current: 73/700
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect

Abstract

An electronic switch of the type uses a piezoresistive Wheatstone bridge configuration to sense pressure. The output of the Wheatstone bridge is applied to an electronic control circuit which contains a comparator. The comparator monitors the output of the bridge and if the output voltage of the bridge exceeds a predetermined value, as indicated by the comparator, a switch is closed to illuminate a lamp indicating to the operator that the pressure has been exceeded. One terminal of a resistor is connected to an output of the bridge. The other terminal of the resistor is coupled to a switch which when operated, causes the resistor to be connected in parallel with one of the arms of the bridge, thereby producing an imbalance of the bridge. This imbalance, due to the shunting of the arm of the bridge by the resistor, causes the electronic control circuit to recognize an excessive pressure, whereby the electronics control circuit generates an output signal which causes the electronic switch to close, thereby illuminating the lamp.

Claims

1-12. -12. (canceled)

13. A monitoring system comprising:

a resistive bridge for providing an output indicative of a sensed condition;

an indicator being electrically coupled to said bridge and for providing an indication when the sensed condition satisfies a threshold condition; and

,

a switch for selectively shunting an electrical impedance into said bridge;

wherein, said impedance is of a magnitude to cause said bridge output to be indicative of the sensed condition satisfying the threshold condition, regardless of said sensed condition, when shunted into said bridge by said switch.

14. The system of claim 13, wherein said resistive bridge comprises a pressure sensitive piezoresistive Wheatsone bridge.

15. The system of claim 14, wherein said threshold condition corresponds to a threshold pressure value.

16. An electronic switch apparatus, comprising:

a resistive network for providing a voltage indicative of a pressure applied thereto;

a circuit coupled to said resistive network for receiving said voltage indicative of the applied pressure and providing an indication when the received voltage exceeds a predetermined value indicative of an alarm condition, and,

a switch for selectively shunting an impedance into said resistive network to bias said voltage indicative of the applied pressure to cause said control circuit to provide said indication regardless of whether said applied pressure exceeds said predetermined value.