| 摘要 |
PURPOSE:To modulate light continuously between lower limit and upper limit by setting the fixed upper limit of a light output level, and enabling only the lower limit to be altered step by step. CONSTITUTION:A high frequency conversion circuit 1 is provided for converting an output voltage from a d.c. power supply E1 to a high frequency voltage and applying it to an illumination load 2. By changing on-duty of a continuous modulated light signal continuously, an output voltage V0 of the 1st modulated light control circuit 3 is changed continuously. The lower limit value of the output voltage V0 of the 1st modulated light control circuit 3 is set to 0V and the upper limit value is set step by step by resistors R15 to R17 and switches SW1 and SW2. An output voltage V0 is applied to a mono-stable multivibrator MUL which decides the optical output level of the illumination load 2. The upper limit value of the optical output level of the illumination load 2 become constant, depending on the lower limit value of the output voltage V0, and the lower limit value is set step by step depending on the upper limit value of the output voltage V0. |
