| 摘要 |
PURPOSE:To suppress unnecessary power consumption during preheating by dividing the primary winding of a DC-DC converter transformer into two parts, and switching their polarities between normal operation and preheating operation. CONSTITUTION:In preheating operation, a polarity inversion switch 25 is placed at the side B and a current flowing through primary winding 3b flows in the opposite direction to that during normal operation to produce magnetic flux as shown by a broken line X3. In this case, this magnetic flux is in the opposite direction to magnetic flux that primary winding 3a produces, so those pieces of magnetic flux cancel each other to induce no voltage across secondary winding 9, and a circuit connected to the secondary winding is not powered up. Heater winding 4 and the secondary winding 14 of a stabilized power source, however, are wound around the same left leg 26a with the primary winding 3a, so the same voltage as that in the normal operation is developed. Thus, only necessary irreducible parts are powered up during the preheating operation to improve the efficiency. |
