| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a brightness adjusting apparatus for a light emitting element which can set high resolution brightness with low brightness while keeping high brightness, and can be inexpensively manufactured. <P>SOLUTION: The brightness adjusting apparatus for a light emitting element includes a first transistor Tr1 for turning on/off the operation of a LED 50, pulse width modulation circuits (20 and 12) each controlling the on/off-state of the first transistor Tr1 by pulse width modulation, and current value control circuits (12 and Tr2) each switching a current value flowing in the LED 50 between a low current value and a high current value higher than the low value when the transistor Tr1 is turned on. While the current value flowing in the LED 50 is controlled to be the high current value, high brightness can be obtained by setting a duty ratio to 100% by the pulse width modulation circuits. On the other hand, while the current value flowing in the LED 50 is controlled to be the low current value, many duty ratios can be specified in a low brightness range by changing the duty ratio in a range of 0-100%, thereby improving a brightness resolution. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
