Image forming apparatus incorporating fixing device

1. An image forming apparatus comprising:

a fixing device to fix a toner image onto a recording medium,

the fixing device including:

an endless, fixing rotator rotatable in a given direction of rotation and formed into a loop;

a heater to heat the fixing rotator;

a pressure pad disposed inside the loop formed by the fixing rotator; and

a pressure rotator disposed opposite the pressure pad via the fixing rotator to press the fixing rotator against the pressure pad to form a fixing nip between the fixing rotator and the pressure rotator, through which the recording medium bearing the toner image is conveyed;

a voltmeter to measure an input voltage from an external source; and

a controller operatively connected to the fixing device and the voltmeter,

the controller controlling a heating operation of the heater and a fixing operation of the fixing device to fix the toner image onto the recording medium, based on the input voltage measured by the voltmeter,

wherein the fixing device further comprises a temperature detector to detect a temperature of the fixing rotator,

wherein, if the input voltage measured by the voltmeter is lower than a predetermined voltage for determining whether operation of the image forming apparatus can be executed, the temperature detector detects the temperature of the fixing rotator after the heater executes a predetermined heating operation to heat the fixing rotator,

wherein the controller determines whether the temperature of the fixing rotator detected by the temperature detector is equal to or higher than a predetermined target fixing temperature allowing a normal fixing operation,

wherein, if the controller determines that the temperature of the fixing rotator detected by the temperature detector is equal to or higher than the predetermined target fixing temperature, the image forming operation starts, and

wherein, if the controller determines that the temperature of the fixing rotator detected by the temperature detector is lower than the predetermined target fixing temperature, the image forming apparatus is restarted.

2. The image forming apparatus according to claim 1 , wherein the endless, fixing rotator is an endless belt.

3. The image forming apparatus according to claim 1 , wherein the pressure rotator is a pressure roller.

4. The image forming apparatus according to claim 1 , wherein the fixing device further comprises a thermal storage between the pressure pad and the fixing rotator,

wherein the pressure pad includes a base, and

wherein the thermal storage has a larger thermal capacity than a thermal capacity of the base of the pressure pad.

5. The image forming apparatus according to claim 4 , wherein, if the input voltage measured by the voltmeter is lower than a predetermined reference voltage, the image forming operation starts after the thermal storage stores heat from the heater.

6. The image forming apparatus according to claim 1 , wherein the heater heats the fixing rotator by radiation, and

wherein the fixing device further comprises:

a temperature detector to detect a temperature of the fixing rotator;

a shield to shield the fixing rotator from the radiation from the heater; and

a driver to move the shield to change a shielding area of the shield.

7. The image forming apparatus according to claim 6 , wherein the heater is a halogen heater.

8. The image forming apparatus according to claim 1 , wherein, if the input voltage measured by the voltmeter is lower than a predetermined reference voltage, the recording medium and a following recording medium are conveyed at an increased interval during a continuous image forming operation, compared to when a normal voltage equal to or higher than the predetermined reference voltage is input.

9. The image forming apparatus according to claim 8 , wherein, if the input voltage measured by the voltmeter is lower than the predetermined reference voltage and if a predetermined productivity recovery requirement is satisfied after the continuous image forming operation starts, conveying the recording medium and the following recording medium at the increased interval, a spatial interval between the recording medium and the following recording medium is returned to a regular spatial interval at which the recording medium and the following recording medium are conveyed when the normal voltage is input.

10. The image forming apparatus according to claim 1 , wherein the controller identifies a level of the input voltage measured by the voltmeter among predetermined voltage levels, and

wherein the controller determines whether to execute the image forming operation and the fixing operation or restart the image forming apparatus based on the level thus identified.

11. The image forming apparatus according to claim 1 , wherein, if the input voltage measured by the voltmeter is lower than a predetermined voltage for identifying malfunction further lower than the predetermined voltage for determining whether operation of the image forming apparatus can be executed, the controller halts operation of the image forming apparatus while indicating that the input voltage is too low.

12. The image forming apparatus according to claim 11 , wherein if the input voltage measured by the voltmeter is lower than a predetermined voltage for identifying malfunction further lower than the predetermined voltage for determining whether operation of the image forming apparatus can be executed the heater does not execute the heating operation and the controller does not restart the image forming apparatus.