POWER SUPPLY CONTROLLER FOR LOAD OF REPRODUCING DEVICE, SPECIALLY, FIXED UNIT

摘要

PROBLEM TO BE SOLVED: To perform immediate switching and to greatly reduce the contamination of a main power source which causes a flicker by varying a phase angle at which a switching signal is generated around a set point. SOLUTION: A control circuit calculates electric power which should be supplied to a fixed unit at respective points of time according to specific environmental conditions. The electric power corresponds to a phase cutoff at time t0 . Then the phase cutoff is not made at the time t0 and changed to time tcut . Variation of tcut around t0 is made within a range determined by a swing window and determined by the maximum allowable deviation of t0 from the value of t3 . The tcut crosses the inside of the swing window in steps together with an index (n) and one step is set as to each half cycle so that the index (n) is increased or decreased by only 1 in each half cycle. In each step, the tcut is increased or decreased by td and the position of the tcut to the t0 is determined by the index (n) indicating the number of steps of the tcut to td as a distance from the t0 at each point of time.