Patent ID: 8836743

Claim:
A drive device configured to drive a plurality of three-terminal light emitting elements each 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 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 having a first conductive type and a second MOS transistor having a second conductive type different from that of the first MOS transistor, the first MOS transistor and the second MOS transistor being complementarily connected to each other, 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 well region having the second conductive type and formed at a substrate; a source region having the first conductive type and formed at the well region; a drain region having the first conductive type and formed at the well region; a source terminal formed at the source region and connected to a second power supply having a potential different from the potential of the first power supply; a drain terminal formed at the drain region and connected to the second terminals of the plurality of three-terminal light emitting elements connected in common; a gate terminal configured to control the conduction state between the source terminal and the drain terminal based on the drive signal; and a channel formation region, which is a region wherein a channel is to be formed, and which is formed between the source region and the drain region, the channel formation region having an impurity having the second conductive type injected therein such that an output equivalent resistance value of the drive circuit is higher than an absolute value of a maximum value of negative resistance determined by a turn-on characteristic of the 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.