Field emission display having multiple brightness display modes

摘要

A field emission display includes a display screen and a cathodoluminescent coating disposed on a conductive inner surface of the display screen. An extraction grid is disposed a predetermined distance away from the inner surface and has a plurality of openings. A plurality of emitters are each aligned with a corresponding one of the openings and are arranged in sets that include at least one emitter. A plurality of emitter driver circuits are each coupled to the emitters in a corresponding one of the sets. Each of the driver circuits receives a control signal having first and second values. The drive circuits drive the emitters such that the display screen displays an image having a first brightness level when the control signal has the first value, and drives the emitters such that the display screen displays an image having a second brightness level when the control signal has the second value. The ratio of the second brightness level to the first brightness level is significantly greater than the ratio of the second value of the control signal to the first value. In one aspect of the invention, each of the driver circuits includes an impedance element that has a nonlinear current-voltage characteristic to give the described ratios.