Patent ID: 6208091
Filing Date: 2001-03-27
Classification: H01J

Abstract:
A display device comprising: a plane cathode; a permanent magnet; a two dimensional array of rows and columns of channels extending between opposite poles of the magnet for receiving electrons from the cathode; a screen having a plurality of phosphor pixels each corresponding to a different channel and each facing the side of the magnet remote from the cathode; grid electrode means disposed between the cathode and the magnet; anode means disposed between the screen and the magnet; address means for supplying control signals to the grid electrode means to control the flow of electrons from the cathode through each channel to the corresponding pixel; an anode grid electrode drive circuit for supplying anode drive signals to the anode means for accelerating electrons in an electron beam current through the channels; a plurality of selectively actuable conductive strips situated between said cathode and said grid electrode means and corresponding to the columns of channels, each conductive strip corresponding to a different sub-set of the columns of channels for sampling a portion of the electron beam current from the cathode to the pixels through a respective channel; a grid voltage generator for generating a control voltage on the grid electrode means for controlling electron beam current flowing from the cathode to the anode, and feedback means connected to the grid voltage generator for varying the control voltage in response to a sampled current detected from the conductive strip to maintain a desired electron beam current.