POWER SAVING APPARATUS FOR A HIGH-INTENSITY DISCHARGE LAMP

摘要

A power saving apparatus (11) includes a voltage measuring circuit (23) for measuring an input voltage from an AC power source (14) and a setting circuit (24) for setting a target power to be supplied to a high-intensity discharge lamp (12). The apparatus further includes a memory circuit (25) for storing in advance waveform processing data to reduce the power estimated from the input voltage to the target power and a control circuit (26) for reading the piece of waveform data that corresponds to the measured input voltage and controlling the conduction timing of a triac (21) for power regulation on the basis of that piece of waveform data. A relay (28) is mounted on a bypass circuit (22) bypassing the triac. When a conduction detector circuit (27) detects that the discharge lamp is not in conduction, the relay closes the bypass circuit and provides the supply voltage to the discharge lamp, preventing the discharge lamp from turning off.