Patent ID: 6965357

Claim:
A light-emitting element drive circuit, comprising: a first drive current generation circuit for outputting a threshold current of a light-emitting element to a light-emitting element as a bias current and a second drive current generation circuit for outputting to the light-emitting element a light-emitting current that causes the light-emitting element to emit light with a predetermined optical output based on a data signal, the light-emitting element drive circuit further comprising: a sensing light-receiving element for receiving light from the light-emitting element and outputting a sense signal that corresponds to the optical output thereof; a timing signal generation circuit for outputting a first timing signal when a pre-determined threshold current arrival time has elapsed during extinction, based on the data signal; a first sampling circuit for sampling the sense signal in response to the first sampling signal, and outputting the sampled sense signal as a first sense signal; and a first adjustment circuit for detecting a change in the threshold current based on the first sense signal, and causing the first drive current generation circuit to generate a bias current that corresponds to the threshold current of the light-emitting element after the change.