US3594758A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drive circuitry for display tubes
Assignee: Unisys Corp
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Filing: 1968-04-25
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Granted: 1971-07-20
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Expires: 1988-04-25
Abstract
Abstract Apparatus for limiting the current, applied to the anodes of a data display system of the type comprising data display tubes having a single anode and a plurality of cathodes, to a constant level when the display tubes are energized as described. The emitter-collector terminals of a current control transistor are connected between an anode voltage source and the anodes of each of the display tubes. The base terminals of the transistors are connected to a voltage limiting zener diode which is biased by the anode voltage source. The zener diode limits the voltage which can be applied to the base of each transistor thereby limiting the current that can flow through each transistor. The base terminals of the transistors are also connected to a control system which controls when a particular anode transistor is to conduct current.
Inventors
- 👤 Julius Gluck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:55
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/04; G09G3/06; G09G3/10; H; H03; H03K; H03K21/00; H03K21/08
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
167 words
In a data display system that comprises a plurality of data display tubes, each data display tube having at least one selectively energizable anode and a plurality of selectively energizable cathodes, an apparatus for limiting the currenT applied to the selectively energized anodes to a constant level when the anodes are energized, said apparatus comprising: a plurality of current control transistors, each of said current control transistors having its emitter-collector terminals connected between an anode potential source and an anode of one of said plurality of data display tubes, the base of each of said current control transistors connected so as to be selectively energizable by a control voltage and thereby control the selective energization of the anodes of said plurality of data display tubes; and, a single voltage limiting diode connected to the bases of all of said plurality of current control transistors to limit the level of the control voltage applied to the bases of said plurality of current control transistors to a constant level.
Claim 2
Dependent Claim
167 words
In a data display system that comprises a plurality of data display tubes, each data display tube having at least one selectively energizable anode and a plurality of selectively energizable cathodes, an apparatus for limiting the currenT applied to the selectively energized anodes to a constant level when the anodes are energized, said apparatus comprising: a plurality of current control transistors, each of said current control transistors having its emitter-collector terminals connected between an anode potential source and an anode of one of said plurality of data display tubes, the base of each of said current control transistors connected so as to be selectively energizable by a control voltage and thereby control the selective energization of the anodes of said plurality of data display tubes; and, a single voltage limiting diode connected to the bases of all of said plurality of current control transistors to limit the level of the control voltage applied to the bases of said plurality of current control transistors to a constant level.
Claim 3
Dependent Claim
15 words
Apparatus as claimed in claim 1 wherein said voltage limiting diode is a zener diode.
Claim 4
Dependent Claim
22 words
Apparatus as claimed in claim 2 wherein said current control transistors are PNP transistors having their collectors directly connected to said anodes.
Claim 5
Dependent Claim
49 words
Apparatus as claimed in claim 3 including a plurality of diodes, one of said plurality of diodes being connected between said zener diode and the base of each of said plurality of PNP transistors; and including a further diode connected between said anode potential source and said zener diode.
Claim 6
Dependent Claim
103 words
Apparatus as claimed in claim 4 including a plurality of series connected resistor-capacitor circuits, one of said circuits being connected to each of said plurality of PNP transistors so that the outer end of the resistor is connected to the emitter of the associated PNP transistor, the junction between the resistor and capacitor is connected to the base of the associated PNP transistor and the outer end of the capacitor is connected to the control voltage that selectively energizes the associated PNP transistor; and including a further resistor connected between said anode potential source and the emitters of all of said PNP transistors.
Claim 7
Dependent Claim
22 words
Apparatus as claimed in claim 1 wherein said current control transistors are PNP transistors having their collectors directly connected to said anodes.
Claim 8
Dependent Claim
52 words
Apparatus as claimed in claim 1 including a plurality of diodes, one of said plurality of diodes being connected between said voltage limiting diode and the base of each of said plurality of current control transistors; and including a further diode connected between said anode potential source and said voltage limiting diode.
Claim 9
Dependent Claim
121 words
Apparatus as claimed in claim 1 including a plurality of series connected resistor-capacitor circuits, one of said circuits being connected to each of said plurality of current control transistors so that the outer end of the resistor is connected to the emitter of the associated current control transistor, the junction between the resistor and capacitor is connected to the base of the associated current control transistor and the outer end of the capacitor is connected to the control voltage that selectively energizes the associated current control transistor; and including a further resistor connected between said anode potential source and the emitters of all of said current control transistors, the collectors of said current control transistors being directly connected to said anodes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-19 | 1975-01-18 | 1975-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-19 | 1979-01-18 | 1979-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-19 | 1983-01-18 | 1983-07-20 | $7700.00 | Window Closed / Lapsed |