| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To suppress heat generation of a driver IC for driving a heat-generating element. <P>SOLUTION: A plurality of element arrays L1-Ln in which a plurality of LEDs 26 are connected in series are each driven by a driver IC 28. The driver IC 28 is provided with a plurality of constant current driving channels Ch, and the driving channels Ch are each allocated to each of the element arrays L1-Ln. A protective transistor Q for protecting the driver IC 28 is provided between the driver IC 28 and each of the element arrays L1-Ln. In the protective transistor Q, a predetermined voltage Vreg is applied to its base terminal to make an output voltage of an emitter terminal constant, irrespective of a voltage to be applied to a collector terminal. A difference voltage between a forward voltage VFL of the element array L and a driving voltage Vd is applied to the collector terminal, and even if its value is large, since the protective transistor Q limits an input voltage into the driver IC 28, heat generation of the driver IC can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
