Lee N Webster

US Patent:

51947820, Mar 16, 1993

Filed:

Jul 19, 1991

Appl. No.:

7/732915

Inventors:

Robert H. Richardson - Hayesville NC
Lee R. Webster - Indialantic FL

International Classification:

H05B 3702

US Classification:

315291

Abstract:

The level of brightness of rapid-start fluorescent lighting is modulated over a range from full brightness at 100% lamp power consumption to minimum brightness at near 0% lamp power consumption. Fluorescent lamp brightness is modulated by controlling the amount of time during cycles of voltage application, such as 60 hz, when current flows through the lamp. An input signal voltage in a given range, for example, from 0 to 5 volts dc, is processed to provide an output which controls the duration of current flow. A cut-off circuit prevents any line voltage from being applied to the lamp at chosen values of input voltage. The cut-off circuit contains hysteresis elements which prevents the lamp from fluttering between off and on states. Modules connected to the lamp's heater elements maintain proper heater element voltage to ensure operation of the lamp form 0% to 100% brightness.