| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a means for selecting multivalued light amount output equivalent to duty-ratio control, while suppressing radiation electromagnetic wave to be generated by driving an infrared light emitting diode. <P>SOLUTION: The infrared light emitting diode is energized by driving a transistor for driving, which is serially connected, with the use of a DC voltage. Relation between the driving voltage of the transistor and the value of an electric current flowing in the infrared light emitting diode is previously registered in a microcomputer 20. The current value is measured through the use of a resistance 35, and the AD converter of the microcomputer 20. When the light amount outputs from the infrared light emitting diode are controlled, the microcomputer 20 determines the driving voltage, based on the registered relation between the the driving voltage and the current value. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
