| 摘要 |
PURPOSE:To light a lamp without fail as well as to shorten the warm-up time to the shortest possible extent, by adding the capacity of a charging condenser in a full-wave voltage doubler rectification circuit so as to make the said capacity in advance of lighting larger than that in case of after-lighting, while opening the circuit of an added condenser at such phase as the currency comes to zero. CONSTITUTION:A control unit 20 is provided with an input part 20a, a phase detecting part 20b, a logical operation part 20c and an output part 20d. A contact TS1 opens or closes the power supply of a microwave discharge light source unit with a signal out of the control unit 20. A timer TM is disposed at the secondary side of the contact TS1 and transmits the signal to the input part 20a. Likewise, a contact TS2 makes a condenser (C) 3 connect in series with a charging condenser C2 in a full-wave voltage doubler rectification circuit by a signal out of the control unit 20. Doing like this, in time of a power circuit into a light source unit, an externally operating switch 21 is operated whereby a discharge lamp is surely lighted by the microwave output of a magnetron 1 and furthermore warm-up time can be shortened. In addition, when the magnetron 1 is set in operation beyond the rating, its operating time is short enough and the contact TS2 is opened with a zero current by means of the phase detecting part 20b, so that service life can be increased. |
