Sinusoidal discharge for EL lamp
A driver for powering an EL lamp includes a boost circuit for converting low voltage DC to high voltage DC and an inverter for converting direct current to alternating current. The driver also includes at least one transistor for discharging,the EL lamp and a generator for producing a ramp voltage that is coupled to the base of the transistor. The ramp voltage causes the discharge current through the EL lamp to be sinusoidal, without harmonics. The discharge current does not cause the EL lamp to produce sound.
1 . A driver for powering an EL lamp, said driver including a boost circuit for converting low voltage DC to high voltage DC and an inverter for converting direct current to alternating current, characterized in that the driver further includes at least one transistor for discharging the EL lamp and a ramp generator coupled to the transistor for controlling the conductivity of the transistor.
2 . The driver as set forth in claim 1 wherein the ramp generator produces a linear ramp.
3 . The driver as set forth in claim 2 wherein the ramp generator produces a linearly increasing voltage.
4 . The driver as set forth in claim 1 wherein the ramp generator produces a nonlinear ramp.
5 . The driver as set forth in claim 1 wherein the inverter includes an H-bridge output.
6 . The driver as set forth in claim 5 wherein said at least one transistor is part of the H-bridge output.
7 . The driver as set forth in claim 1 wherein said driver includes a combined boost circuit and inverter and has a single ended output coupled to said at least one transistor.