| 摘要 |
A light source is responsive to an input electrical signal to increase or decrease its output depending upon whether the input electrical signal corresponds to a higher light output level than the source is currently providing or a lower light output level than the source is currently providing, respectively. The output control comprises a light detector for monitoring the light output and for producing a signal related thereto, a voltage source for establishing a maximum desired light output, a voltage source for establishing a minimum desired light output, and a window comparator for comparing the detected signal to the maximum and minimum desired light outputs. The light detector and voltage sources are coupled to the window comparator. A binary counter selectively generates a periodic signal. An OR gate couples the window comparator to the binary counter. A D/A converter and light source driver couple the binary counter to the light source. The binary counter provides the periodic signal as the input electrical signal to the light source in response to the window comparator determining that the light detector signal is not related to a light output between the maximum desired light output and the minimum desired light output. |
