| 摘要 |
PURPOSE:To prevent excessive rush current into a heater transformer by providing a flip-flop to output a control signal for controlling ON-OFF of a power source supplying means which supplies power source to a transformer to which a welding means for heat welding and sealing is connected. CONSTITUTION:When a transistor 45 is turned ON, an SSR 23 of a gate circuit 14 becomes conductive between input terminals to turn ON between output terminals of the SSR 23. During a period in which a gate trigger pulse corresponding to a gate trigger signal I is output to a gate terminal of a double- directioned thyrister 1, alternating waveform J of one-cycle unit is impressed between both ends of a primary winding of a heater transformer 2 through the double-directioned thyrister 1. By this, the positive or negative direction of the alternating current waveform at the turn-ON and turn-OFF of the double- directioned thyrister 1 is always determined so as to have reversed polarity constantly. Thus, after heat welding of a resinous sheet and at a start of heating, reversed polarity can be obtained constantly, and therefore, it is prevented that an excessive rush current flows because of a quick magnetic saturation of the heater transformer 2. |
