Abstract: An activation control apparatus includes a voltage fluctuation obtainer to obtain voltage fluctuation amplitude of an external power source at a given voltage, the voltage fluctuation caused when activating an apparatus using the external power source; a voltage fluctuation detector to detect the voltage fluctuation of the external power source at the given voltage; an activation controller to determine whether the voltage fluctuation amplitude obtained by the voltage fluctuation obtainer at the given voltage of the external power source, detected by the voltage fluctuation detector, is within a preset allowable voltage fluctuation range, and to control activation of the apparatus using the external power source based on a result of the voltage fluctuation determination made by the activation controller.

Abstract: A heater control device includes a temperature detector that detects a temperature of a heated object heated by a heater; an alternating-current power supply for applying an alternating current voltage to the heater; a turn-on ratio decision unit that determines a turn-on ratio of the heater based on the temperature and a target temperature; a turn-on pattern decision unit that determines a partial turn-on pattern, as the turn-on pattern of the heater, which is a pattern of a turn-on ratio higher than the determined turn-on ratio in terms of a control-period, and to which a partial turn-on instead of a full turn-on is allocated on a half-wavelength basis of the alternating current voltage within the control period based on the turn-on ratio of the heater; and a turn-on controller that controls turn-on of the heater based on the determined turn-on pattern.

Abstract: A heating unit is heated by supply of an alternate-current power. A heating control unit executes a phase control to supply the alternate-current power to the heating unit for an ON-width in at least a half-wave period of the alternate-current power. A storing unit stores therein parameters for calculating the ON width. The heating control unit calculates the ON width based on the parameters stored in the storing unit and executes the phase control using a calculated ON width.

Abstract: A heater controller performs on/off control of a plurality of heaters and includes a storage unit that stores therein a plurality of pattern sets. Each of the pattern sets includes a plurality of heater-on/off patterns for respectively controlling the heaters. The heater controller calculates a reference value representing an average of values of electric power supplied to the heater controller over a predetermined period of time; calculates, for each of the pattern sets, an output power value to be supplied to the heaters when the heaters are turned-on according to the heater-on/off patterns included in the pattern set; calculates, for each of the pattern sets, a difference between the reference value and the output power value; selects, from the pattern sets, one pattern set having a smallest difference; and performs on/off control of the heaters according to the heater-on/off patterns included in the pattern set thus selected.

Abstract: An image forming apparatus includes a halogen heater in a fixing unit; an AC source applying an alternating voltage to the halogen heater; a half-wave control unit that performs the heater half-wave control to control the halogen heater on the half-wavelength basis, according to a heater-on/off pattern set for each control cycle having a predetermined length; a heater-off-time measuring unit that measures heater-off period of time; a phase-control-execution determining unit that determines, based on the measured heater-off period of time, whether the heater phase control is to be performed on the alternating voltage, the phase control being performed by shifting phase of the alternating voltage; and a phase control unit that performs, when the phase control is determined to be performed, the phase control only for a period of time depending on the measured heater-off period of time after switch-on of the heater and before execution of the half-wave control.

Abstract: A heater controller performs on/off control of a plurality of heaters and includes a storage unit that stores therein a plurality of pattern sets. Each of the pattern sets includes a plurality of heater-on/off patterns for respectively controlling the heaters. The heater controller calculates a reference value representing an average of values of electric power supplied to the heater controller over a predetermined period of time; calculates, for each of the pattern sets, an output power value to be supplied to the heaters when the heaters are turned-on according to the heater-on/off patterns included in the pattern set; calculates, for each of the pattern sets, a difference between the reference value and the output power value; selects, from the pattern sets, one pattern set having a smallest difference; and performs on/off control of the heaters according to the heater-on/off patterns included in the pattern set thus selected.

Abstract: A heater control device includes a temperature detector that detects a temperature of a heated object heated by a heater; an alternating-current power supply for applying an alternating current voltage to the heater; a turn-on ratio decision unit that determines a turn-on ratio of the heater based on the temperature and a target temperature; a turn-on pattern decision unit that determines a partial turn-on pattern, as the turn-on pattern of the heater, which is a pattern of a turn-on ratio higher than the determined turn-on ratio in terms of a control-period, and to which a partial turn-on instead of a full turn-on is allocated on a half-wavelength basis of the alternating current voltage within the control period based on the turn-on ratio of the heater; and a turn-on controller that controls turn-on of the heater based on the determined turn-on pattern.

Abstract: An image forming apparatus includes a halogen heater in a fixing unit; an AC source applying an alternating voltage to the halogen heater; a half-wave control unit that performs the heater half-wave control to control the halogen heater on the half-wavelength basis, according to a heater-on/off pattern set for each control cycle having a predetermined length; a heater-off-time measuring unit that measures heater-off period of time; a phase-control-execution determining unit that determines, based on the measured heater-off period of time, whether the heater phase control is to be performed on the alternating voltage, the phase control being performed by shifting phase of the alternating voltage; and a phase control unit that performs, when the phase control is determined to be performed, the phase control only for a period of time depending on the measured heater-off period of time after switch-on of the heater and before execution of the half-wave control.

Abstract: A heating unit is heated by supply of an alternate-current power. A heating control unit executes a phase control to supply the alternate-current power to the heating unit for an ON-width in at least a half-wave period of the alternate-current power. A storing unit stores therein parameters for calculating the ON width. The heating control unit calculates the ON width based on the parameters stored in the storing unit and executes the phase control using a calculated ON width.