Control and method for a capacitive sensor system

• US 20080088323A1
• Filed: 10/16/2006
• Published: 04/17/2008
• Est. Priority Date: 10/16/2006
• Status: Abandoned Application

• Current Assignee: Emerson Electric Company
• Original Assignee: Emerson Electric Company
• Inventors: Williams, Douglas A., Vornsand, Steven J.
• Application Number:
  US11/581,796
• Publication Number:
  US 20080088323A1
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

A control and method for an e-field sensor touch switch system includes an output having a first output voltage based on a static capacitance sensed by an e-field sensor and a gain module that generates a final output voltage based on amplifying a difference between an offset voltage and the first output voltage.

Claims

1. An e-field sensor touch switch control system comprising:

an output having a first output voltage based on a static capacitance sensed by an e-field sensor; and

a gain module that generates a final output voltage based on amplifying a difference between an offset voltage and said first output voltage.

2. The control system of claim 1 further comprising an offset module that adjusts said offset voltage based on said final output voltage and a reference voltage.

3. The control system of claim 1 wherein said gain module transmits said final output voltage to a microcontroller module, said microcontroller module generates a digital response based on said final output voltage.

4. The control system of claim 3 wherein said offset module receives a digital-to-analog signal (Sd/a) corresponding to said digital response.

5. The control system of claim 3 wherein said microcontroller module generates a digital-to-analog voltage signal based on said digital response.

6. The control system of claim 5 wherein said microcontroller module generates said digital-to-analog voltage signal using one of a discrete binary resistor method, a resistor ladder network, and pulse width modulation.

7. The control system of claim 3 further comprising an e-field module that communicates with said e-field sensor and generates said first output voltage.

8. The control system of claim 7 wherein said first output voltage is further based on an input capacitance and said microcontroller module controls the appliance based on said first output voltage.

9. The control system of claim 7 further comprising an e-field input line that detects a second static capacitance and indicates that said e-field sensor module is operational based on said second static capacitance.

10. The control system of claim 8 wherein further comprising a first reference e-field sensor having a fixed capacitance and a second reference e-field sensor having a capacitance substantially higher than a sum of said static capacitance and said input capacitance, said microcontroller module detects a fault based on at least one of said first reference e-field sensor and said second reference e-field sensor.

11. The control system of claim 7 wherein said e-field module selects said e-field sensor among a plurality of e-field sensors based on a selection signal generated by said microcontroller module.

12. A control method for an e-field sensor touch switch system comprising:

generating a first output voltage based on a static capacitance sensed by an e-field sensor; and

generating a final output voltage based on amplifying a difference between an offset voltage and said first output voltage.

13. The control method of claim 12 further comprising adjusting said offset voltage based on said final output voltage and a reference voltage.

14. The control method of claim 12 further comprising generating a digital response based on said final output voltage.

15. The control method of claim 14 further comprising generating a digital-to-analog voltage signal based on said digital response.

16. The control method of claim 15 further comprising generating said digital-to-analog voltage signal using one of a discrete binary resistor method, a resistor ladder network, and pulse width modulation.

17. The control method of claim 12 further comprising generating a first output voltage further based on an input capacitance, and a microcontroller module controls the appliance based on said first output voltage.

18. The control method of claim 17 further comprising communicating that an e-field module is operational by detecting a second static capacitance on an e-field input line.

19. The control method of claim 17 further comprising detecting a fault based on at least one of a first reference e-field sensor having a fixed capacitance and a second reference e-field sensor having a capacitance substantially higher than a sum of said static capacitance and said input capacitance.

20. The control method of claim 18 further comprising selecting said e-field sensor among a plurality of e-field sensors based on a selection signal generated by said microcontroller module.

21. A control system for an e-field sensor touch switch system comprising:

at least one e-field sensor that senses capacitance;

a control module that selectively generates an offset voltage for said at least one e-field sensor based on said capacitance; and

an output having a final voltage based on said offset voltage and a first output voltage, wherein said control module controls the appliance based on said final voltage.