| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve reliability and performance in an LED driving circuit employed as a light source of a backlight of a liquid crystal display. <P>SOLUTION: For example, 40 LEDs are equally divided into four, and they connected ten pieces by ten pieces in series so as to form first to fourth series circuits 21-24. The first to fourth series circuits 21-24 are connected with a constant-current circuit 10 in parallel, and the constant-current circuit 10 is controlled so that a current flowing in the first series driving circuit 21 may be constant in quantity. Then, a current mirror circuit is connected to the first to fourth series circuits 21-24, so that the same currents can be applied to the first to fourth series circuits 21-24. Furthermore, a voltage drop circuit 11 is provided so that a specified voltage drop Vd may occur in the first series driving circuit 21. Thus, a variation in the forward voltage drop of an LED can be eliminated, and the current mirror circuit can be appropriately operated as a result. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
