Array sensor electronics

• US 20050068044A1
• Filed: 10/24/2002
• Published: 03/31/2005
• Est. Priority Date: 10/24/2001
• Status: Active Grant

• Current Assignee: Pressure Profile Systems Inc. (PPS U.K. Limited)
• Original Assignee: Pressure Profile Systems Inc. (PPS U.K. Limited)
• Inventors: Peine, William, Son, Jae S., Pratico, Robert
• Granted Patent: US 7,378,856 B2
• Time in Patent Office: Days
• US Class Current: 324/658
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/037 Measuring oesophageal pressure
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

Circuits and methods for detecting and amplifying sensor and sensor array (102, 104) output signals are presented. According to some aspects, a nonlinear feedback loop containing a sensor element provides a nonlinear transformation that compensates for a corresponding nonlinear response of the sensor element thereby providing a linearized final output signal. In other aspects, idle sensors are coupled to a reference on non-idle sensor elements. Other aspects include sensor and amplification circuits which operate without traditional filtering or switching elements, such that a higher throughput is achieved and no settling time is required due to traditional transients, thus allowing for faster scanning of larger sensor arrays. Some embodiments of the present invention are directed to variable gap capacitive sensor arrays and the signal processing electronics.

Claims

1. A sensor system, comprising:

a sensor array having a plurality of sensor elements;

at least one sensor element of the sensor array, having addressable connections designating the sensor element, that senses a stimulus; and

an amplifier, disposed in a feedback arrangement around the sensor element, the amplifier receiving an input signal corresponding to an output of the sensor element and providing an output signal that drives the sensor element.

2. The system of claim 1, wherein the sensor element comprises a capacitive sensor element and the sensor array comprises a capacitive sensor array.

3. The system of claim 1, wherein the stimulus alters a distance of separation between a first conductive strip and a second conductive strip.

4. The system of claim 1, wherein the stimulus is any of a force, a weight, a pressure, a displacement and an acceleration.

5. The system of claim 1, further comprising an amplitude detector which receives an output signal from the amplifier.

6. The system of claim 1, further comprising a nonlinear transformer which transforms a nonlinear output of the amplifier into a corresponding substantially-linear signal representing the stimulus.

7. The system of claim 6, wherein the nonlinear transformer is a feedback loop comprising the sensor element.

8. The system of claim 1, wherein the amplifier'"'"'s output signal is one of a plurality of signals which drive the sensor element.

9. The system of claim 1, wherein the filtering circuit is a digitally-controlled integrator.

10. The system of claim 1, wherein the sensor element has an individually-controlled gain and an individually-controlled offset.

11. The system of claim 1, wherein a tunable filter element is coupled to the sensor element and wherein the tunable filter element is placed in physical proximity to the sensor elements to provide common mode rejection to environmental effects.

12. The system of claim 1, further comprising a tunable filter, coupled to an oscillator having an oscillator signal, which shifts a phase of the oscillator signal to provide a phase-shifted signal and a summing circuit which sums the amplifier output with the phase-shifted signal to substantially cancel out oscillator bias in a portion of the sensor system.

13. The system of claim 1, further comprising a path from the sensor element to a common potential which is selectably coupled to the sensor element.

14. The system of claim 1, wherein the sensor element is selectably coupled to a ground potential when the sensor element is not being driven or sampled.

15. The system of claim 1 wherein the sensor element is coupled to an electrical line which is individually shielded from electromagnetic effects.

16. The system of claim 1, further coupled to at least one other sensor system such that the system of claim 1 and the at least one other sensor system cover a combined region of interest having a greater area than an area covered by the system of claim 1 or an area covered by the at least one other sensor system.

17. A method for measuring a stimulus on a sensor array, comprising:

sensing the stimulus using at least one sensor element of the sensor array;

generating a sensor element output signal corresponding to the sensed stimulus;

amplifying the sensor element output signal to generate an amplified signal representative of the physical property; and

feeding back the amplified signal to drive the sensor element.

18. The method of claim 17, further comprising providing an oscillating signal to drive the sensor element, shifting a phase of the oscillating signal to provide a phase-shifted signal and summing the sensor element output and the phase-shifted signal to substantially cancel out oscillator bias in a portion of the sensor system.

19. A method for linearizing a non-linear sensor response, comprising:

sensing a stimulus using a sensor element;

generating a sensor output signal corresponding to the stimulus;

feeding back the sensor output signal to an input of the sensor through a non-linear transformer feedback loop corresponding to the non-linear sensor response.

20. The method of claim 19, further comprising amplifying the sensor output signal using an amplifier disposed in the feedback loop.

21. The method of claim 19, wherein the non-linear sensor response is a non-linear response to a pressure applied to a capacitive sensor element.

22. A method for reducing parasitic capacitance in a capacitive sensor array, comprising selectively coupling at least one sensor element in the sensor array to a common potential during a time period in which the sensor element is idle.

23. The method of claim 22, wherein the common potential is a ground potential.

24. The method of claim 22, wherein the parasitic capacitance is a capacitance between the sensor array and ground.

25. The method of claim 22, wherein the parasitic capacitance is a capacitance between an array driving circuit and ground.