Vacuum Fluorescent Display Brightness Controller
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
A technique is described which reduces the variation of each character brightness in vacuum fluorescent display (VFD). The concept is to control anode current (grid to anode current) in proportion to the number of the selected dots so as to obtain characters of uniform brightness that does not depend on VFD assembly process quality. Up to this time, appropriate materials were selected and the following assembly factors were controlled to uniform the brightness of VFD unit: 1) Diameter of filament 2) Uniformity of tension for each filament 3) Uniformity of distance between filament and grid In a VFD unit, brightness of one dot is decided by a quantity of photon from phosphor, which strongly depends on the quantity and energy of the electrons that hit its phosphor.