Abstract: A control unit for a printing apparatus has a plurality of heat sources, each heat source being operable at an individual power level. The control unit is configured to control the power supplied to the heat sources such that, at each instant, the sum of the delivered individual power levels is less than or equal to a maximum allowable power. The control unit is also configured to control the power delivered to the heat sources on the basis of sequential cycles and for each cycle, to receive for each heat source a requested power pulse duration, to schedule within the cycle instants at which power is to be delivered to the heat sources, based on the individual power levels and requested pulse durations and to deliver the power according to the scheduled instants within the cycle.

Abstract: A control unit for a printing apparatus has a plurality of heat sources, each heat source being operable at an individual power level. The control unit is configured to control the power supplied to the heat sources such that, at each instant, the sum of the delivered individual power levels is less than or equal to a maximum allowable power. The control unit is also configured to control the power delivered to the heat sources on the basis of sequential cycles and for each cycle, to receive for each heat source a requested power pulse duration, to schedule within the cycle instants at which power is to be delivered to the heat sources, based on the individual power levels and requested pulse durations and to deliver the power according to the scheduled instants within the cycle.

Abstract: An apparatus for controlling the power supplied from an AC power supply to an ohmic load, includes a switch for connecting the load to the AC power supply, a controller for providing a control signal to the switch, and a rectifier bridge having an input and an output. The input is adapted for connection to the AC power supply and the output is connected to a series connection of a first inductor, the load and the switch. The controller provides a control signal with a frequency which is at least 500 times higher than the frequency of the AC power supply. The switch is switched on and off by the control signal. The controller comprises a control element for varying the duty cycle of the control signal.

Abstract: An apparatus for controlling the power supplied from an AC power supply to an ohmic load, includes a switch for connecting the load to the AC power supply, a controller for providing a control signal to the switch, and a rectifier bridge having an input and an output. The input is adapted for connection to the AC power supply and the output is connected to a series connection of a first inductor, the load and the switch. The controller provides a control signal with a frequency which is at least 500 times higher than the frequency of the AC power supply. The switch is switched on and off by the control signal. The controller comprises a control element for varying the duty cycle of the control signal.