Energy saving means reducing power used by lamps

Claim 1

Energy saving means for reducing power used by lamps employing means reducing power without significant reduction of apparent brightness as viewed by the normal human eye, comprising in combination, a traffic signal incandescent lamp, a switching circuit for selectively providing upon command lamp lighting power at a predetermined lighting voltage for said lamp, and a command circuit actuating said switching circuit periodically including equipment providing a normal daytime mode of operation for lighting said lamp while in use in daytime brightness at a duty cycle of less than 100% and at a frequency between 5 Hz and 30 Hz to retain some of the brightness of one lighting pulse by the human eye until the next lighting pulse occurs, thereby constituting equipment with an operating mode whereby said power is decreased for lighting the lamp without a corresponding reduction in viewed brightness wherein said power for said lamp is supplied from an alternating current power source having a frequency N of 60 Hertz, and wherein said command circuit respectively turns on and off said lamp over a duration of on and off pulses having an integral number of successive half cycles.