Lighting system with variable control current sensing ballast

Claim 1

An electronic ballast system for providing light from one or more gas discharge lamps, comprising: (a) a housing unit to mount electronic circuitry and related components; (b) electronic circuitry mounted on said housing unit, which includes: (i) means for connecting and applying a.c. power input to said circuitry; (ii) means for switching lamps on and off controlling said circuitry; (iii) rectifying circuitry to convert a.c. power input to a plurality of d.c. outputs, including one or more low voltage outputs; (iv) comparator circuitry which receives an external control signal and compares ti to feedback from the output of the device, and thereby controls the Pulse Width Modulation (PWM) circuitry; (v) said PWM circuitry which sends at least one timing signal to MOSFET gate drive circuit; (vi) said MOSFET gate driver circuit which receives said timing signal from PWM circuitry and supplies switching control to two MOSFET's; (vii) said MOSFET's which receive d.c. power from doubling rectifying circuitry and which are controlled by said MOSFET gate driver circuitry such that a high frequency voltage is output; (viii) means to create an initial delay of MOSFET switching during initial power-up to improve lamp life and effectiveness; (ix) one or more isolation transformers, with the outputs of said MOSFET's connected to the inputs of said transformers; (x) lamp sensing circuitry receiving input from rectifier to detect lamp outage, and connected to shut down circuitry; (xi) said shut down circuitry to at least partially decrease power when at lease one lamp is missing; and, (xii) one or more gas filled lamps with two unconnected electrodes connected to the output of said isolation transformers, wherein said lamps are lamps selected from the group consisting of fluorescent lamps, mercury-free lamps and lamps filled predominantly with inert gas.