Claims
- 1. A method for controlling a field emission display comprising;
- sensing a voltage at a display screen for the display and providing a first signal and a second signal based on an amplitude of the voltage;
- detecting the first signal and the second signal;
- providing a fault detection circuit configured to detect a fault signal during the detecting step, the fault detection circuit comprising a peak detector;
- enabling a grid for the display with the first signal provided the fault signal is not detected; and
- discharging the grid with the second signal.
- 2. The method as claimed in claim 1 wherein the fault detection circuit comprises a comparator.
- 3. The method as claimed in claim 1 further comprising enabling the grid only if a grid supply voltage is above a level.
- 4. The method as claimed in claim 1 wherein enabling the grid is with a first transistor having a gate element enabled by the first signal.
- 5. The method as claimed in claim 1 wherein discharging the grid is with a second transistor having a gate element enabled by the second signal.
- 6. A method for controlling a field emission display comprising:
- sensing a voltage at a display screen for the display and providing a first signal and a second signal based on an amplitude of the voltage;
- detecting the first signal and the second signal;
- providing a comparator having a first input for detecting a fault signal and a second input in electrical communication with a peak detector for receiving the fault signal;
- enabling a grid for the display with the first signal provided the fault signal is not detected; and
- discharging the grid with the second signal or upon detection of the fault signal.
- 7. A method for controlling a field emission display comprising;
- sensing a voltage at a display screen for the display to provide an input signal based on an amplitude of the voltage;
- detecting the input signal using a level detector to provide an output signal;
- providing a comparator configured to detect a fault signal during the detecting step, the comparator comprising a peak detector;
- controlling current flow to the grid using a first transistor having a first gate element enabled by the output signal in a first state;
- controlling discharge of the grid with a second transistor having a second gate element enabled by the output signal in a second state; and
- discharging the grid upon detection of the fault signal.
- 8. The method as claimed in claim 7 further comprising enabling the grid only if grid supply voltage is above a level.
- 9. The method as claimed in claim 7 wherein the first state comprises a signal high and the second state comprises a signal low.
- 10. The method as claimed in claim 7 wherein detecting the input signal is performed using a logical inverter or a Schmitt trigger.
- 11. A control circuit for controlling current flow in a field emission display comprising:
- a threshold detector for receiving an input signal proportional to an anode voltage for the display and for providing a first output signal or a second output signal;
- a first transistor for controlling power to the grid, the first transistor comprising a gate element enabled by the first output signal;
- a second transistor for controlling discharge of the grid, the second transistor enabled by the second output signal; and
- a fault detection circuit adapted to discharge the grid upon detection of a sharp decrease in the anode voltage, the fault detection circuit comprising a peak detector.
- 12. The control circuit as claimed in claim 11 wherein the threshold detector comprises an element selected from the group consisting of a logical inverter and a Schmitt trigger.
- 13. The control circuit as claimed in claim 11 further comprising a level shifter for detecting a a grid supply voltage and for enabling the first transistor only if the grid supply voltage is above a level.
- 14. In a field emission display having field emitter sites, a grid for controlling electron emission from the emitter sites and a display screen for receiving electrons from the emitter sites, a control circuit for controlling current to the emitter sites, said control circuit comprising:
- a threshold detector for receiving an input signal proportional to a voltage at the display screen and for providing a first output signal or a second output signal;
- a first transistor for controlling current to the grid, the first transistor enabled by the first output signal;
- a second transistor for controlling discharge of the grid, the second transistor enabled by the second output signal; and
- a fault detection circuit for detecting a fault signal responsive to the voltage at the display screen, the fault detection circuit comprising a third transistor in series with the first transistor.
- 15. The grid control circuit as claimed in claim 14 wherein the threshold detector comprises an element selected from the group consisting of an inverter and a Schmitt trigger.
- 16. The grid control circuit as claimed in claim 14 further comprising a level shifter in electrical communication with a grid supply for receiving the output signal from the threshold detector and for providing a second output signal if a grid supply voltage is above a level.
- 17. The grid control circuit as claimed in claim 14 wherein the fault detection circuit comprises a peak detector.
- 18. In a field emission display having field emitter sites, a grid for controlling electron emission from the emitter sites and a display screen for receiving electrons from the emitter sites, a control circuit for controlling current to the emitter sites comprising:
- a threshold detector for receiving an input signal proportional to a voltage at the display screen and for providing a first output signal or a second output signal;
- a first transistor for controlling current to the grid, the first transistor enabled by the first output signal;
- a second transistor for controlling discharge of the grid, the second transistor enabled by the second output signal; and
- a third transistor for controlling discharge of the grid to ground, the third transistor enabled by a fault detection circuit.
- 19. A method for controlling a field emission display comprising:
- providing a plurality of emitter sites;
- providing a power source for the emitter sites having a source impedance;
- selecting the source impedance such that electron emission cannot occur from all of the emitter sites once;
- shorting the emitter sites together during a turn on mode of the field emission display;
- enabling the emitter sites during the turn on mode and limiting current to the emitter sites with the source impedance; and
- enabling select emitter sites during an operational mode of the field emission display to initiate electron emission from selected emitter sites.
- 20. The method as claimed in claim 19 wherein the source impedance comprises a permanent impedance.
- 21. The method as claimed in claim 19 wherein the source impedance is switchable between a first value for the turn on mode and to a second value during the operational mode.
- 22. The method as claimed in claim 21 and further comprising switching between the first value and the second value using relay or a switching device.
- 23. A method for controlling a field emission display comprising;
- providing a plurality of emitter sites;
- providing a power source in electrical communication with the emitter sites, the power source having a source impedance;
- shorting the emitter sites together during a turn on mode of the field emission display;
- enabling the emitter sites during the turn on mode;
- selecting the source impedance such that electron emission from the emitter sites during the turn on mode cannot occur; and
- disabling first select emitter sites and enabling second select emitter sites during an operational mode of the field emission display.
- 24. The method as claimed in claim 23 wherein the source impedance is switchable between a first impedance for the turn on mode and a second impedance for the operational mode.
- 25. The method as claimed in claim 24 wherein the source impedance is switchable using a relay or a switching device.
- 26. The method as claimed in claim 23 and wherein disabling and enabling the emitter sites is performed using a multiplexer.
- 27. The method as claimed in claim 23 further comprising enabling all of the emitter sites during a turn off mode of the field emission display and limiting current to the emitter sites during the turn off mode with the source impedance.
- 28. The method as claimed in claim 23 wherein the source impedance is switchable between a first impedance during the turn off mode and a second impedance for the operational mode.
- 29. A field emission display comprising:
- a plurality of field emitter sites;
- a power supply in electrical communication with the emitter sites and having a source impedance;
- a multiplexer circuit configured to short selected emitter sites together during a turn on mode of the field emission display and to enable the selected emitter sites during an operational mode of the field emission display; and
- a switching circuit in electrical communication with the power supply for switching the power supply to a first impedance during the turn on mode and to a second impedance during the operational mode, the first impedance having a value insufficient to allow emission to grid during the turn on mode.
- 30. The control circuit as claimed in claim 29 further comprising a logic circuit in electrical communication with the power supply and with the multiplexer circuit for controlling the power supply and the multiplexer circuit.
- 31. The control circuit as claimed in claim 30 wherein the switching circuit is in electrical communication with the logic circuit and is controlled by the logic circuit.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 08/509,501 filed on Jul. 28, 1995 U.S. Pat. No. 5,721,560.
Government Interests
This invention was made with Government support under contract No. DABT63-93-C-0025 awarded by Advanced Research Project Agency ("ARPA"). The government has certain rights in this invention.
US Referenced Citations (18)
Non-Patent Literature Citations (2)
Entry |
Notes on Using the Spindt-type Field Emission Cathode, Capp Spindt, SRI International, Menlo Park, CA, Oct., 1976. |
Cathey, David A. Jr., "Field Emission Displays", published in VLSI, Taiwan, May-Jun., 1995. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
509501 |
Jul 1995 |
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