A field emission display includes a discrete storage capacitor coupled between a row line and a reference potential. The display also includes a discharge circuit coupled between a transmission line tap and the storage capacitor. The discharge circuit receives a pulsed image signal from the transmission line and transfers charge from the transmission line to the storage capacitor. In one embodiment, the discharge circuit includes a pair of opposed zener diodes. In response to a brief negative-going input pulse on the transmission line, the capacitor is discharged through the diodes. Then, the diodes recover and capacitor and row line are isolated from the tap. A selected line of an extraction grid is activated to cause an emitter set coupled to the row line to emit electrons. The emitted electrons are replaced by electrons from the capacitor. The capacitor has sufficient capacitance to supply electrons over an expected refresh interval of the row line. Therefore, the voltage of the capacitor remains substantially constant over the refresh interval. Because the capacitor can be charged quickly, the input pulse can be short relative to the refresh interval.
A field emission display having an improved operational life. In one embodiment of the present invention, the field emission display comprises a plurality of row lines, a plurality of column lines, and a plurality of electron emissive elements disposed at intersections of the plurality of row lines and column lines, a column driver circuit, and a row driver circuit. The column driver circuit is coupled to drive column voltage signals over the plurality of column lines; and, the row driver circuit is coupled to activate and deactivate the plurality of row lines with row voltage signals. Significantly, according to the present invention, operational life of the field emission display is substantially extended when the electron emissive elements are intermittently reverse-biased by the column voltage signals and the row voltage signals. In another embodiment, the row driver circuit is responsive to a SLEEP signal. The row driver circuit, upon receiving the SLEEP signal, drives a sleep-mode voltage over the row lines to reverse-bias the electron emissive elements.
A printed circuit board has a dielectric constant different from the dielectric constant of free space, with at least two microstrip lines routed adjacent to one another on a surface of the printed circuit board. A dielectric coating is applied to at least one of the at least two microstrip lines such that the dielectric constant of the dielectric coating differs from the dielectric constant of free space. In a further embodiment, the dielectric coating comprises a material having a dielectric constant approximately equal to the dielectric constant of the printed circuit board.
A printed circuit board has a dielectric constant different from the dielectric constant of free space, with at least two microstrip lines routed adjacent to one another on a surface of the printed circuit board. A dielectric coating is applied to at least one of the at least two microstrip lines such that the dielectric constant of the dielectric coating differs from the dielectric constant of free space. In a further embodiment, the dielectric coating comprises a material having a dielectric constant approximately equal to the dielectric constant of the printed circuit board.
