Image forming apparatus including heating rotating member
An image forming apparatus which is capable of shifting to a standby state in which a heating rotating member is maintained at a first temperature during non-image forming, and to a sleep state in which a heater is turned off during non-image forming. The heater turns on before a predetermined time period elapses from when the image forming apparatus shifts to the sleep state such that the heating rotating member is maintained at a second temperature, which is equal to or less than the first temperature when the predetermined time period elapses from when the image forming apparatus shifts to the sleep state.
1 . An image forming apparatus comprising;
an image forming portion that forms a toner image on the recording material;
a fixing device that thermally fixes the toner image formed on the recording material, the fixing device comprises:
a heating rotating member having a heater and heated by the heater;
a pressure rotating member that forms a nip by contacting the heating rotating member, the pressure rotating member fixing the toner image onto the recording material together with the heating member;
a temperature detecting portion for detecting the temperature of the heating rotating member; and
a control portion for controlling the heater based on the detection results of the temperature detecting portion;
wherein the control portion is configured to execute a:
(i) a first mode, executed for a first predetermined time during a non-image forming period from the end of an image forming job until the next image forming job is input, maintaining the temperature of the heating rotating member at a first predetermined temperature while rotating the heating rotary member;
(ii) a second mode, executed for a second predetermined time during the non-image forming period after the first mode is executed, which stops rotation of the heating rotating member and turns off power to the heater from the end of the first mode until the second predetermined time elapses; and
(iii) a third mode, executed after executing the second mode, the third mode comprising: a first period during which power supply of the heater is controlled while rotating the heating rotating member to maintain its temperature at a second predetermined temperature lower than the first predetermined temperature; and a second period following the first period, the second period being a period during which power to the heater is stopped based on the detection result of the temperature detecting portion while the rotation of the heating rotary member is stopped, until the temperature of the heating rotary member drops to a temperature lower than the second predetermined temperature.
2 . The image forming apparatus according to claim 1 ,
wherein the control portion changes a duration of the second predetermined time based on the detection result of the temperature detecting portion at an end of the first mode.
3 . The image forming apparatus according to claim 1 ,
wherein when the detection result of the temperature detecting portion at the end of the first mode is a first temperature, the second predetermined time is a first time, and
wherein when the detection result of the temperature detecting portion at the end of the first mode is a second temperature, which is greater than the first temperature, the second predetermined time becomes a second time, which is greater than the first time.
4 . The image forming apparatus according to claim 1 ,
wherein the temperature detecting portion does not detect a temperature of the heating rotating member in the second mode.
5 . The image forming apparatus according to claim 1 , further comprising
a second temperature detecting portion which detects a temperature outside the image forming apparatus,
wherein the control portion corrects the second predetermined time based on the temperature detected by the second temperature detecting portion.
6 . The image forming apparatus according to claim 1 ,
wherein the temperature of the heating rotary member while the recording material is passing through the nip section is higher than the first predetermined temperature.
7 . The image forming apparatus according to claim 1 ,
further comprising an operation portion with which a user can operate a setting of the image forming apparatus,
wherein in the first mode, it is possible to transition to the second mode based on an instruction from the operation unit.
8 . The image forming apparatus according to claim 1 ,
wherein during execution of the first mode, the second mode and the third mode, the heating rotary member and the pressure rotating member are separated.
9 . The image forming apparatus according to claim 1 ,
wherein in the second mode, the control portion turns off the power supplied to the fixing device, placing it in a sleep state where heating operations by the fixing device, drive operations, and temperature detection by the temperature detecting means are not performed.