Circuit arrangement for driving a current-controlled component

Claim 1

A circuit arrangement for driving a current-controlled light-emitting element to emit pulses of light in intervals corresponding to input signal pulses, comprising: a direct current power source; a transistor having an emitter, base and collector and a main current path between the emitter and collector, the resistance of such main current path being controllable from a relatively high to a relatively low value by a signal applied to the base of the transistor; a constant current source arranged in series with said light-emitting element and the main current path of the transistor, such series arrangement being connected to said direct current power source; a capacitor in parallel with the series combination of said light-emitting element and the main current path of said transistor; and means for coupling input signal pulses to the base of said transistor to control the resistance of the main current path thereof, such resistance decreasing from its high to its low value during each such pulse; whereby during each input signal pulse said current source and said capacitor supply current to said light-emitting element, causing it to emit a pulse of light, and during each interval between signal pulses said current source supplies charging current to said capacitor.