| 摘要 |
<p>A lighting control apparatus (dimmer) responsive to an electrical demand signal to control the portion of the voltage cycle during which voltage is supplied to one or more discharge lamps from AC voltage source, using a pulse enable circuit to provide pulsing of the firing circuit appropriate for discharge lamps. The apparatus comprises a shaping circuit responsive to a demand signal, a timing circuit, a pulse enable circuit, a single pulse per half-cycle firing means, and a solid state switching means. The pulse enable circuit prevents activation of the firing means when the solid state switching means is in a conductive state (firing pulses based on the voltage cycle could otherwise occur before the lagging current of the previous halt has fallen to zero). This combines the advantages of low power consumption of single pulse firing circuits with a reliability of firing of discharge lamps obtained heretofore only in multiple pulse firing circuits.</p> |
