Method and circuit for extending the range of a cold cathode discharge vacuum gauge
First Claim
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1. A cold cathode ionization gauge controller for measuring the pressure of a gas comprising:
- means for measuring the electrical resistance of a cold cathode ionization gauge in communication with the gas where said measuring means includes means for measuring the current through the gauge and means for measuring the voltage across the gauge and means for dividing the measured voltage by the measured current to obtain said electrical resistance; and
means for translating said electrical resistance to said pressure of the gas.
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Abstract
A method and circuit for measuring the pressure of a gas with a cold cathode ionization gauge by measuring the electrical resistance or conductance of the gauge to thus extend the measurement range of the gauge. Current into the gauge may be limited to a substantially constant value at pressures greater than about 10-6 Torr, for example, so that the gauge voltage varies monotonically with respect to pressure at pressures greater than 10-6 Torr.
25 Citations
39 Claims
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1. A cold cathode ionization gauge controller for measuring the pressure of a gas comprising:
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means for measuring the electrical resistance of a cold cathode ionization gauge in communication with the gas where said measuring means includes means for measuring the current through the gauge and means for measuring the voltage across the gauge and means for dividing the measured voltage by the measured current to obtain said electrical resistance; and means for translating said electrical resistance to said pressure of the gas. - View Dependent Claims (2, 3, 4, 5, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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6. A cold cathode ionization gauge controller for measuring the pressure of a gas comprising:
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means for measuring the electrical conductance of a cold cathode ionization gauge in communication with the gas where said measuring means includes means for measuring the current through the gauge and means for measuring the voltage across the gauge and means for dividing the measured current by the measured voltage to obtain said electrical conductance; and means for translating the measured parameter to said pressure of the gas. - View Dependent Claims (7, 8, 9, 10)
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30. A cold cathode ionization gauge controller for measuring the pressure of a gas comprising:
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means for measuring the electrical resistance of a cold cathode ionization gauge in communication with the gas where said measuring means includes means for measuring the current through the gauge and means for measuring the voltage across the gauge and means for dividing the measured voltage by the measured current to obtain said electrical resistance; and means for translating said electrical resistance to said pressure of the gas; where the cold cathode ionization gauge includes an anode and cathode and the controller includes a voltage source connected to the anode and a current limiting resistor disposed between the voltage source and the anode for limiting the current into the anode to a substantially constant value so that the voltage across the anode and cathode varies monotonically with respect to pressure at pressures greater than a predetermined value; and
where said measuring means includes a voltage divider connected between said anode and a reference voltage, the voltage divider including at least two resistors, the first resistor being disposed between the anode and the second resistor and the second resistor being disposed between the first resistor and the reference voltage where the value of the first resistor with respect to that of the current limiting resistor is such that the current through the voltage divider has substantially no effect on the voltage applied to the anode. - View Dependent Claims (31, 32)
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33. A method for measuring the pressure of a gas in the cold cathode ionization gauge comprising the steps of
measuring the electrical resistance of the gauge where said measuring step includes measuring the current through the gauge and measuring the voltage across the gauge and dividing the measured voltage by the measured current to obtain said electrical resistance of the gauge; - and
translating the measured parameter to said pressure of the gas. - View Dependent Claims (35, 36, 37, 38, 39)
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34. A method for measuring the pressure of a gas in a cold cathode ionization gauge comprising the steps of
measuring an electrical conductance of the gauge where said measuring step includes measuring the current through the gauge and measuring the voltage across the gauge and dividing the measured current by the measured voltage to obtain said electrical conductance of the gauge; - and
translating the measured parameter to said pressure of the gas.
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Specification