| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED drive which offers a high general-purpose function, and is capable of low power consumption driving. SOLUTION: A constant current is supplied to a resistance variable unit connected to an output voltage variable power supply to cause a reference current generating unit to control an output voltage from the output voltage variable power supply. An LED emitter is composed of a plurality of LED arrays consisting of more than one LED elements connected in series which are supplied with power from the output voltage variable power supply, and each LED array is connected to one end of an active element. A control current causes the same current as the constant current to flow through a control electrode of the active element, and is supplied from the reference current generating unit to the control electrode of each active element in a current mirror unit which supplies a current to each LED array. A terminal voltage of one of the plurality of LED arrays is detected, and an LED number determining unit so controls a resistance value of the resistance variable unit as to adjust an output voltage from the output voltage variable power supply to a voltage necessary for light emission from the LED array whose terminal voltage has been detected. COPYRIGHT: (C)2007,JPO&INPIT
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