Image forming apparatus and control program for image forming apparatus

1. An image forming apparatus comprising:

a fixer including a halogen heater; and

a hardware processor that controls power supplied to the halogen heater,

wherein the hardware processor switches, according to a state of the fixer, a control state for controlling the power supplied to the halogen heater between a first control state in which a lower limit of an amount of power per cycle of the power supplied to the halogen heater is set to a first value and a second control state in which the lower limit of the amount of power per cycle of the power supplied to the halogen heater is set to a second value lower than the first value, and

wherein life of the halogen heater when an amount of power per cycle of the power supplied to the halogen heater is set to the second value is 80% or less of the life of the halogen heater when the amount of power per cycle of the power supplied to the halogen heater is set to the first value.

2. The image forming apparatus according to claim 1 , wherein:

the hardware processor controls the power supplied to the halogen heater by controlling a duty cycle being a ratio of time to supply power to time of one cycle, and

the first control state is a state in which a lower limit of the duty cycle is set to a first duty cycle lower limit, and the second control state is a state in which the lower limit of the duty cycle is set to a second duty cycle lower limit lower than the first duty cycle lower limit.

3. The image forming apparatus according to claim 2 , wherein the hardware processor controls the power supplied to the halogen heater by pulse width modulation (PWM) control that changes a duty ratio of a pulse wave to perform modulation.

4. The image forming apparatus according to claim 1 , wherein the hardware processor controls the power supplied to the halogen heater in the second control state during a predetermined time just before a first sheet to be printed in a print job executed by the image forming apparatus enters the fixer.

5. The image forming apparatus according to claim 1 , wherein the hardware processor controls the power supplied to the halogen heater in the second control state when a target controlled temperature of the fixer is equal to or higher than a predetermined temperature.

6. The image forming apparatus according to claim 1 , wherein the hardware processor switches the control state for controlling the power supplied to the halogen heater between the first control state and the second control state according to an extent of wear of the halogen heater.

7. The image forming apparatus according to claim 6 , wherein the hardware processor comprises:

a wear calculator that calculates the extent of wear of the halogen heater based on a time during which the power supplied to the halogen heater is controlled in the first control state and a time during which the power supplied to the halogen heater is controlled in the second control state; and

a wear controller that controls the power supplied to the halogen heater in the second control state when the extent of wear of the halogen heater calculated by the wear calculator is less than the extent of wear of the halogen heater predicted from the number of sheets printed by the image forming apparatus.

8. The image forming apparatus according to claim 7 , wherein the wear controller controls the power supplied to the halogen heater in the first control state when the extent of wear of the halogen heater calculated by the wear calculator is greater than the extent of wear of the halogen heater predicted from the number of sheets printed by the image forming apparatus.

9. The image forming apparatus according to claim 6 , wherein the hardware processor comprises:

a fixing calculator that calculates an extent of wear of the fixer;

a wear calculator that calculates the extent of wear of the halogen heater based on a time during which the power supplied to the halogen heater is controlled in the first control state and a time during which the power supplied to the halogen heater is controlled in the second control state; and

a comparison controller that controls the power supplied to the halogen heater by comparing the extent of wear of the fixer calculated by the fixing calculator with the extent of wear of the halogen heater calculated by the wear calculator.

10. The image forming apparatus according to claim 6 , further comprising a fixing condition changer that, when the hardware processor controls the power supplied to the halogen heater in the second control state, lowers a target controlled temperature of the fixer and delays a timing at which a sheet enters the fixer compared with when the hardware processor controls the power supplied to the halogen heater in the first control state.

11. A non-transitory recording medium storing a computer readable control program for an image forming apparatus comprising a fixer including a halogen heater, the computer readable control program causing a computer to perform controlling power supplied to the halogen heater,

wherein in the controlling, a control state for controlling power supplied to the halogen heater is switched, according to a state of the fixer, between a first control state in which a lower limit of an amount of power per cycle of the power supplied to the halogen heater is set to a first value and a second control state in which the lower limit of the amount of power per cycle of the power supplied to the halogen heater is set to a second value lower than the first value, and

wherein life of the halogen heater when an amount of power per cycle of the power supplied to the halogen heater is set to the second value is 80% or less of the life of the halogen heater when the amount of power per cycle of the power supplied to the halogen heater is set to the first value.