Abstract:
Method for compensating for brightness variations in a field emission device (100a). In one embodiment, a method and system are described for measuring the relative brightness of rows of a field emission display (FED) device (100a), storing information representing the measured brightness into a correction table and using the correction table to provide uniform row brightness in the display by adjusting row voltages and/or row on-time periods. A special measurement process is described for providing accurate current measurements on the rows. This embodiment compensates for brightness variations of the rows, e.g., for rows near the spacer walls (30). In another embodiment, a periodic signal, e.g., a high frequency noise signal (340), is added to the row on-time pulse in order to camouflage brightness variations in the rows near the spacer walls (30). In another embodiment, the area under the row on-time pulse is adjusted to provide row-by-row brightness compensation based on correction values stored in a memory resident correction table (60). In another embodiment, the brightness of each row is measured and compiled into a data profile for the FED. The data profile is used to control cathode burn-in processes so that brightness variations are corrected by physically altering the characteristics of the emitters of the rows.
Abstract:
A circuit and method for turning-on and turning-off elements of an field emission display device to protect against emitter electrode(60) and gate electrode(50) degradation. The circuit(910) includes control logic(916) having a sequencer which in one embodiment can be realized using a state machine. Upon power-on, the control logic sends an enable signal to a high voltage power supply (912) that supplies voltage to the anode electrode (914). At this time a low voltage power supply (918) and driving circuitry (920)are disabled. Upon receiving a confirmation signal from the high voltage power supply, the control logic enables the low voltage power supply which supplies voltage to the driving circuitry (920). Upon receiving a confirmation signal from the low voltage power supply (918), or optionally after expiration of a predetermined time period, the control logic (916) then enables the driving circuitry (920) which drives the gate electrodes (50) and the emitter electrodes (60) which make up the rows and columns of the FED device. Upon power down, the control logic (916) first disables the low voltage power supply (918), then the high voltage power supply (912).
Abstract:
The intensity at which electrons emitted by a first plate structure (10) in a slat-panel display strike a second plate structure (12) for causing it to emit light is controlled so as to reduce image degradation that could otherwise arise from undesired electron-trajectory changes caused by effects such as the presence of a spacer system (14) between the plate structures. An electron-emissive region (20) in the first plate structure typically contains multiple laterally separated electron-emissive portions (201 and 202) for selectively emitting electrons. An electron-focusing system in the first plate structure has corresponding focus openings (40p1 and 40p2) through which electrons emitted by the electron-emissive portions respectively pass. Upon being struck by the so-emitted electrons, a light-emissive region (22) in the second plate structure emits light to produce at least part of a dot of the display's image.