Patent ID: 8773043

Claim:
An integrated circuit for driving a group of light-emitting diodes, the group of the light-emitting diodes including at least a first light-emitting diode system constituted by one light-emitting diode or by a plurality of light-emitting diodes connected in series, and a second light-emitting diode system constituted by one light-emitting diode or by a plurality of light emitting diodes connected in series, the one light-emitting diode or the plurality of light-emitting diodes, which constitute(s) the first light-emitting diode system, having a forward voltage drop greater than that of the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the second light-emitting diode system, an anode-side end of the first light-emitting diode system and an anode-side end of the second light-emitting diode system being connected to an identical point, and the one light-emitting diode or the plurality of light-emitting diodes, which constitute(s) the first light-emitting diode system, each having an emission wavelength different from that of each of the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the second light-emitting diode system, said integrated circuit, comprising: a first constant current driving circuit for controlling a current which drives the first light-emitting diode system; and a second constant current driving circuit for controlling a current which drives the second light-emitting diode system, the first constant current driving circuit driving the first light-emitting diode system by a steady electric current, the second constant current driving circuit driving the second light-emitting diode system by an intermittent current and a regenerative current, the first constant current driving circuit being capable of controlling brightness of the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the first light-emitting diode system which is to be driven, by controlling a period during which the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the first light-emitting diode system is/are ON, the second constant current driving circuit being capable of controlling brightness of the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the second light-emitting diode system which is to be driven, by controlling a period during which the one light-emitting diode or the plurality of light-emitting diodes which constitute(s) the second light-emitting diode system is/are ON the second constant current driving circuit including an inductance and a power MOSFET, and the inductance storing energy while the power MOSFET is operating and releasing the energy while the power MOSFET is open, thereby generating the regenerative current.