Power supply circuit for driving a light emitting element.

摘要

(Purpose> Improved are design conditions for the parts relative to a step-up circuit for causing an emission of light of a distance measuring light emitting element. (Construction> Provided is a step-up circuit for outputting a step-up voltage from one terminal of a step-up capacitor. Provided also is a step-up voltage level changeover circuit for applying a higher step-up voltage higher than normal every time when the distance measuring light emitting element connected to the step-up capacitor emits the light than the step-up voltage in the normal state. (Advantages> The number of parts is reduced by eliminating the capcitor for the light emission; a space is reduced by using the capacitor having a small capacity; the soldering steps are automated; and the costs for assembly are ameliorated owing to the automation.