Patent ID: 7391406

Claim:
A light emission control circuit comprising: a booster circuit for boosting a voltage of a constant-voltage source so as to drive a plurality of light-emitting elements corresponding to respective colors; variable current circuits for driving the plurality of light-emitting elements; switch elements for establishing or shutting connection between the light-emitting elements and the variable current circuits; a first control unit for controlling the capability of said variable current circuits to drive the plurality of light-emitting elements; a second control unit for turning on and off said switch elements according to pulse width modulation; and an additional driving circuit which 1) feeds a driving current to the plurality of light-emitting elements when operating the plurality of light-emitting elements as an electronic flash light, 2) connects a variable power source to the light-emitting elements via a switch for electronic flash light, a transistor and a differential amplifier, 3) connects a resistor to the source terminal of the transistor and the non-inverting input terminal of the differential amplifier, and 4) uses the variable power source to set a driving current for electronic flash light, wherein said first control unit adjusts luminance, responsive to an external instruction from a controller, produced by the entirety of the plurality of light-emitting elements, by controlling driving currents of the variable current circuits so that the ratio of the currents driving the plurality of light-emitting elements remains unchanged; and said second control unit adjusts tone of color, responsive to an external instruction from the controller, produced by the entirety of the plurality of light-emitting elements, by independently controlling the duty ratio of pulse signals from the switch elements.