| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To more efficiently change the luminance of a liquid crystal backlight in a light-emitting element drive circuit and a cellular phone including the light-emitting element drive circuit. <P>SOLUTION: The light-emitting element drive circuit is provided with: a voltage step-up circuit section 20 for supplying a step-up voltage to one terminal of a backlight 62; a step-up comparator 22 for comparing the voltage of the other terminal of the backlight 62 with a predetermined reference voltage value and outputting a result of comparison as a feedback signal for the step-up voltage to the step-up circuit section 20; an LED driver section 40 connected to the other terminal of the backlight 62 and driven on a current; an acquiring means for acquiring a PWM signal which is generated on the basis of the contents of a video signal and varies the luminance of the light-emitting element; and an LPF section 30 for outputting a time-averaged signal of the acquired PWM signal as a control signal of the LED driver section 40. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
