Patent ID: 7242156

Claim:
A pulse drive method for one or more light-emitting semiconductor devices having a plurality of light-emitting elements emitting light at different wavelengths, the light-emitting semiconductor device pulse drive method comprising: first lit steps in which at least a portion of the light-emitting elements of any of the emitted wavelengths is or are made to light as a result of being driven at one or more drive settings for each emitted wavelength, at least one optical output from the lit light-emitting element or elements is detected, and at least one of the light-emitting element drive setting or settings is adjusted based on at least one of the detected light-emitting element optical output or outputs; and unlit steps in which the light-emitting elements of all of the emitted wavelengths are unlit for prescribed unlit time, the length of which does not depend on the light-emitting element drive setting or settings; wherein the first lit steps are carried out in repeated fashion by switching at least a portion of the driven light-emitting element or elements one after another so as to cause at least a portion of the light-emitting elements to sequentially light in pulsed fashion in the order of emitted wavelength such that the plurality of light-emitting elements having different wavelengths are allowed to light up at different timings from each other; and at least one iteration of the unlit steps respectively intervenes between each pair of successive iterations of the first lit steps carried out in repeated fashion, such that the light-emitting elements of different wavelengths are not lit at the same time.