Patent ID: 6028871
Filing Date: 2000-02-22
Classification: H01S,H05B,Y02B

Abstract:
A driver circuit for a solid state optical emitter, the circuit comprising a current supply path and a current return path to which the optical emitter is connected, and current limit means to limit a maximum current that flows through one of the current paths, characterised in that the current limit means has a current mirror circuit comprising at least a first transistor and a second transistor, said first transistor comprising an input portion of the current mirror circuit and said second transistor comprising an output portion of the current mirror circuit, said first transistor and second transistor connected so that when a first current flows through the input portion, the second portion is predisposed to supply a second current up to a maximum which tracks the first current, such that the maximum current through the current paths is limited to be no greater than the maximum of the second current.