Patent ID: 7649323

Claim:
A rechargeable light-emitting device driver circuit, comprising: a voltage source; a rechargeable first battery having a nominal battery voltage connected in parallel with the voltage source; a first nonlinear current-blocking device having a reverse-breakdown voltage greater than the nominal battery voltage connected in parallel between the voltage source and the first battery for charging the first battery at the nominal battery voltage by the voltage source; a second nonlinear current-blocking device connected in series between the first nonlinear current blocking device and the first battery to prevent discharge of the first battery through the voltage source; and, a light-emitting device having a forward bias voltage approximately equal to the nominal battery voltage in series with a first switch operatively connected to logic means for controlling the first switch, the light-emitting device and first switch connected in parallel with the first battery whereby the first battery can power the light-emitting device under control of the logic means and the voltage source can recharge the first battery.