| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an inexpensive constant-current pulse-width-control driving circuit for light emitting diodes wherein the number of the components of its constant-current driving circuit is cut down, and the variations are reduced as generated between the currents of its respective light-emitting-diode modules. <P>SOLUTION: The collector of a first transistor 6-1 is connected with a plurality of light emitting diodes 3-1 connected in series with each other. N-pieces of light-emitting diode modules 13-1 connecting its emitter with a first resistor 4-1 are connected in parallel with a power supply 1. A series circuit comprising a second resistor 11 and a Zener diode 12 is connected with the power supply 1, a second transistor 10 is connected in parallel with the Zener diode 12, and a pulse generating circuit 9 is connected with the power supply 1. The output of the pulse generating circuit 9 is connected with the base of the second transistor 10, and the connecting point of the second resistor 11 with the Zener diode 12 is connected with the bases of the first transistors 6-1 of the respective light-emitting diode modules 13-1. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
