Claims
- 1. A flame ionization sensor comprising:means for sensing resistance of the flame ionization sensor; and means for supplying increasing voltage to the sensor in response to an increase in the resistance.
- 2. The flame ionization sensor of claim 1 further comprising:means for stepping up a line voltage.
- 3. A flame ionization sensor comprising:a controllable switch for controlling power to the flame ionization sensor; means for routing a line voltage to the controllable switch; a resistance sensor in series with the flame ionization sensor; and means for increasing a duty cycle of the controllable switch in response to increased resistance across the flame ionization sensor.
- 4. A flame ionization sensor comprising:means for routing a line voltage to the flame ionization sensor; means for stepping up a line voltage to the flame ionization sensor; a controllable switch between the line voltage and the flame ionization sensor; means for sensing resistance across the flame ionization sensor; and means for supplying increased voltage to the flame ionization sensor in response to increased resistance across the flame ionization sensor.
- 5. The flame ionization sensor of claim 4 further comprising:the means for stepping up a line voltage being a transformer.
- 6. The flame ionization sensor of claim 5 further comprising:the controllable switch being a semiconductor switch.
- 7. The flame ionization sensor of claim 6 further comprising:the controllable switch being a field effect transistor.
- 8. The flame ionization sensor of claim 6 further comprising:the means for sensing resistance further including a sensing resistor in series with t he flame ionization sensor.
- 9. The flame ionization sensor of claim 8 further comprising:the means for sensing resistance further including a large common mode amplifier in parallel with the sensing resistor.
- 10. The flame ionization sensor of claim 9 further comprising:the means for sensing resistance further including a low pass filter in series with an output of the large common mode amplifier.
- 11. The flame ionization sensor of claim 10 further comprising:the means for sensing resistance further including a linear amplifier with a constant current reference in series with an output of the low pass filter.
- 12. The flame ionization sensor of claim 11 further comprising:the means for supplying increased voltage further including a timing circuit.
- 13. The flame ionization sensor of claim 12 further comprising:the timing circuit including a zero crossing detector and a sawtooth wave generator attached to an output of the transformer.
- 14. The flame ionization sensor of claim 12 further comprising:a voltage-to-pulse width converter using an output of the timing circuit as a trigger input and using an output of the linear amplifier as a control signal and outputting a duty cycle signal to the controllable switch.
- 15. The flame ionization sensor of claim 14 further comprising:a switch driver in series between the voltage-to-pulse width converter and the controllable switch.
- 16. The flame ionization sensor of claim 5 further comprising:the transformer having an output for providing a DC power supply to the means for sensing and the means for supplying increased voltage.
- 17. A method of operating an flame ionization sensor comprising:running the flame ionization sensor at a first voltage; monitoring resistance across the flame ionization sensor; and supplying the flame ionization sensor with a voltage above the first voltage in response to increased resistance across the flame ionization sensor.
- 18. The method of claim 17 wherein the step of supplying the flame ionization sensor with a voltage above the first voltage includes increasing the duty cycle of a switch which controls power to the flame ionization sensor.
Parent Case Info
This application claims benefit of Ser. No. 60/181,005, filed Feb. 8, 2000.
US Referenced Citations (14)
Provisional Applications (1)
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Number |
Date |
Country |
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60/181005 |
Feb 2000 |
US |