| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent trouble caused by an abnormal driving current in an LED or a driving circuit by preventing the driving current exceeding a rated current from being inputted to the LED for a width wider than the prescribed width. <P>SOLUTION: An image acquiring device includes: the LED 51; the driving circuit 52 for inputting a driving pulse signal from a driving pulse generator 41, and supplying the driving current exceeding the rated current in continuous turning-on to the LED 51 during only a period when the driving pulse signal indicates ON; and a protecting circuit 53 arranged between the driving pulse generator 41 and the driving circuit 52. When the width of the pulse of the driving pulse signal to be inputted from the driving pulse generator 41 is longer than a predetermined limit pulse width, the protecting circuit 53 limits the pulse width to the limit pulse width so as to output the driving pulse signal to the driving circuit 52. Consequently, the input of the driving current to the LED 51 by the width wider than the limit pulse width is prevented so as to prevent the trouble caused by the abnormal driving current in the LED 51 or the driving circuit 52. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
