US3567995A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current stabilizer circuit for thermionic electron emission device
Assignee: Automation Industries Inc
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Filing: 1968-08-12
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Granted: 1971-03-02
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Expires: 1988-08-12
Abstract
Abstract A current stabilizer circuit for a thermionic electron emission device is described in which the cathode heating winding of a power supply transformer is connected to the high-voltage winding through a heating current control circuit. The control circuit senses changes in the emission current of an X-ray tube or other electron emission device having a thermionic cathode, and produces a control signal which is applied to a variable impedance means connected in series with the cathode filament to vary the heating current in order to maintain such emission current substantially constant. The control circuit may operate by series regulation or by pulse duration modulation of the cathode heating current to change the average heating current and temperature of the cathode and thereby vary its electron emission in order to stabilize the emission current in spite of changes in the power supply voltage which tend to vary such emission current.
Inventors
- 👤 Peter O Lauritzen
- 👤 Cormack E Boucher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:37
CPC Classifications
H; H05; H05G; H05G1/00; H05G1/08; H05G1/26; H05G1/30; H05G1/34
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
328 words
A current stabilizer circuit for an electron emission device having a thermionic cathode, comprising: transformer means including a high-voltage winding having one end connected for applying a high voltage to said cathode to cause emission current to flow in said device, and a heating winding for supplying heating current to said cathode, said heating winding being provided as a secondary winding on the same transformer core as said high-voltage winding; control circuit means connected between said one end of said high-voltage winding and said heating winding for producing a control signal proportional to variations of current in the high-voltage winding corresponding to changes in said emission current; variable-impedance means connected to said heating winding and said control circuit means for varying said heating current in response to said control signal, said variable-impedance means causing the heating current to vary in an opposite manner to the changes in said emission current to compensate for said changes in order to stabilize said emission current and maintain it substantially constant; said control circuit means including a source of substantially constant reference current, comparator means for subtracting said reference current and the current in said high voltage winding to produce a difference current from which the control means derives the control signal, an amplifier having its input connected to the output of the comparator means, and filter means including a shunt capacitor connected across the input of said amplifier for changing the AC difference current to a slowly varying DC input level; and said amplifier also being connected at its input to the heating winding through an AC coupling capacitor and rectifier means to apply pulses of one polarity to the input of said amplifier which switch the amplifier between conduction and nonconduction when the amplitude of said pulses exceeds the DC input level and cause said amplifier to produce corresponding output pulses whose widths are modulated by changes in the value of said DC input level to provide said control signal.
Claim 2
Dependent Claim
328 words
A current stabilizer circuit for an electron emission device having a thermionic cathode, comprising: transformer means including a high-voltage winding having one end connected for applying a high voltage to said cathode to cause emission current to flow in said device, and a heating winding for supplying heating current to said cathode, said heating winding being provided as a secondary winding on the same transformer core as said high-voltage winding; control circuit means connected between said one end of said high-voltage winding and said heating winding for producing a control signal proportional to variations of current in the high-voltage winding corresponding to changes in said emission current; variable-impedance means connected to said heating winding and said control circuit means for varying said heating current in response to said control signal, said variable-impedance means causing the heating current to vary in an opposite manner to the changes in said emission current to compensate for said changes in order to stabilize said emission current and maintain it substantially constant; said control circuit means including a source of substantially constant reference current, comparator means for subtracting said reference current and the current in said high voltage winding to produce a difference current from which the control means derives the control signal, an amplifier having its input connected to the output of the comparator means, and filter means including a shunt capacitor connected across the input of said amplifier for changing the AC difference current to a slowly varying DC input level; and said amplifier also being connected at its input to the heating winding through an AC coupling capacitor and rectifier means to apply pulses of one polarity to the input of said amplifier which switch the amplifier between conduction and nonconduction when the amplitude of said pulses exceeds the DC input level and cause said amplifier to produce corresponding output pulses whose widths are modulated by changes in the value of said DC input level to provide said control signal.
Claim 3
Dependent Claim
54 words
A circuit in accordance with claim 1 in which the pulse duration modulated control signal is applied to the base electrode of a transistor having its emitter-to-collector circuit in series with the heating winding, for switching such transistor on and off to vary the amount of average heating current flowing through the cathode filament.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |