| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a lighting circuit of light emitting diodes capable of selectively lighting two light emitting diodes at a predetermined luminance by one switching element without affection of characteristics of the switching element, and a control method thereof. <P>SOLUTION: A positive supply voltage is applied to a power line 6. Applying a high signal to an input terminal 4 allows the transistor Q1 of the switching element to be in an on-state, and a current flows only in a light emitting diode L2 and only the light emitting diode L2 is lighted. Applying a low signal to the input terminal 4 allows the transistor Q1 to be in an off-state, a current flows the light emitting diodes L1, L2. Since resistances R1, R2 is determined so that the current flowing in the light emitting diode L2 is sufficiently small, only the light emitting diode L1 is lighted. Also, the light emitting diodes L1, L2 are serially connected so as to be free of the influence of the characteristics of the transistor Q1. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
