Patent ID: 8848012

Claim:
A drive device configured to drive a plurality of three-terminal light emitting elements with each light emitting element comprising: a first terminal connected to a first power supply; a second terminal configured to enable drive current flow to the first terminal from the second terminal, and a first control terminal configured to control the conduction state between the first terminal and the second terminal, the first terminals of the plurality of three-terminal light emitting elements being connected in common, the second terminals of the plurality of three-terminal light emitting elements being connected in common, the drive device comprising: a drive circuit, including a first MOS transistor, and configured to drive three-terminal light emitting elements that are in conduction state among the plurality of three-terminal light emitting elements based on a received drive signal, wherein the first MOS transistor includes: a third terminal connected to a second power supply having a potential different from the potential of the first power supply; a fourth terminal connected to the second terminals of the plurality of three-terminal light emitting elements connected in common, a second control terminal configured to control the conduction state between the third terminal and the fourth terminal based on the drive signal; and a substrate terminal configured to have a potential applied thereto different from the potential of the second power supply to change a threshold voltage of the first MOS transistor, wherein an absolute value of the potential that is applied to the substrate terminal is set higher than an absolute value of the potential of the second power supply such that an equivalent output resistance value of the drive circuit is higher than a maximum value of an absolute value of negative resistance determined by a turn-on characteristic of the three-terminal light emitting elements, wherein a threshold voltage of the first MOS transistor is increased in such a manner that the first MOS transistor exhibits a constant current property.