JP4815918B2 - Fixing apparatus, image forming apparatus, and fixing apparatus driving method - Google Patents

Description

  The present invention relates to a fixing device mounted on an image forming apparatus.

  An image forming apparatus such as a copying machine includes a fixing device for fixing an unfixed image on a sheet by heating and pressing. This fixing device is provided with a fixing roller, a pressure roller pressed against the fixing roller, a heater for heating the fixing roller, a temperature sensor for detecting the surface temperature of both rollers, and the like. Based on the signal, the surface temperature of the fixing roller is maintained at a predetermined fixing temperature (for example, 190 ° C.). As the pressure roller rotates, heat is transmitted from the fixing roller, and the surface of the pressure roller is kept at a predetermined temperature (for example, 120 ° C.) or higher during the fixing operation.

When the image forming apparatus is in a standby state in which it waits until a job is received without executing the image forming process, the fixing roller and the pressure roller of the fixing apparatus are stopped. At this time, since the heat from the fixing roller is difficult to be transmitted to the pressure roller, the temperature gradually decreases.
Therefore, when the surface temperature of the pressure roller is lower than a predetermined temperature when the image forming apparatus shifts from the standby state to the image forming operation, both rollers are rotated to transfer heat from the fixing roller to the pressure roller. Thus, control is performed to set each of the fixing roller and the pressure roller to a predetermined temperature.
JP-A-7-160133

However, in the current image forming apparatus, it takes time for the fixing roller and the pressure roller to rise to their respective predetermined temperatures, and the time until the transition from the standby state to the image forming operation is completed, the so-called first print time. There is a long-standing problem.
The present invention has been made in view of the above points, and provides a fixing device, an image forming apparatus, and a control method capable of shortening the time from the standby state to the image forming operation to completion. The purpose is to do.

  Accordingly, a fixing device according to the present invention is a fixing device mounted on an image forming apparatus, and includes a heating unit, a heating rotating member heated by the heating unit, and a pressure rotating member pressed against the heating rotating member. And a temperature detecting means for detecting the surface temperature of the pressure rotating member, a driving means for rotationally driving the heating rotating member and the pressure rotating member, and a time point when the image forming apparatus shifts from the standby state to the image forming operation. And determining means for determining the rotation speeds of the heating rotating member and the pressure rotating member based on the temperature detected by the temperature detecting means.

The inventors have determined that the time required for each of the heating rotary member and the pressure rotary member to reach a predetermined temperature depends on the surface temperature of the pressure rotary member and the rotational speed of both rotary members at the time of transition to the image forming operation. I found out.
In the above configuration, the rotation speed is determined to be an appropriate value based on the surface temperature of the pressure rotation member, and the heating rotation member and the pressure rotation member are driven to rotate at the rotation speed. It is possible to reduce the time required for each to reach a predetermined temperature, thereby reducing the time from the standby state to the completion of the image forming operation.

In addition, the driving unit is configured so that, after the image forming operation of the image forming apparatus is started, until the heating rotating member reaches a first predetermined temperature and the pressurizing rotating member reaches a second predetermined temperature. The heating rotary member and the pressure rotary member are driven to rotate at the determined rotational speed, and after the heating rotary member reaches a first predetermined temperature and the pressure rotary member reaches a second predetermined temperature, It is desirable that the heating rotary member and the pressure rotary member are rotationally driven at a rotational speed of 2 mm.

As described above, until the fixing state is reached, the heating rotation member and the pressure rotation member are rotationally driven at the rotation speed determined by the determination unit, so that the fixing can be quickly performed and the fixing is possible. After reaching a stable state, a smooth fixing operation can be performed by switching to a predetermined rotational speed at the time of fixing.
Here, the determining unit is configured to perform a first predetermined operation when the heating rotating member is deprived of heat by the pressure rotating member in accordance with rotation after the image forming apparatus is shifted from the standby state to the image forming operation. The time required for the temperature to fall from the temperature to recover again to the first predetermined temperature, and the pressure rotating member receives heat from the heating rotating member as it rotates, and from the standby state temperature to the second predetermined temperature. It is desirable to determine the rotation speed at which the time required for raising the temperature to the same is equal.

By setting such a rotation speed, the time required for the heating rotary member and the pressure rotary member to reach a predetermined temperature can be minimized, and the transition from the standby state to the image forming operation is completed. Can be shortened.
Further, when the detected temperature detected by the temperature detecting means is taken on the horizontal axis and the rotational speed determined by the determining means is taken on the vertical axis, the graph showing the relationship between the detected temperature and the rotational speed is lowered to the right. It is desirable.

It has been found by the present inventors that when the detected temperature and the rotation speed are in such a relationship, the time required for the heating rotary member and the pressure rotary member to reach a predetermined temperature can be shortened.
An image forming apparatus according to the present invention includes any one of the fixing devices described above. Accordingly, it is possible to provide an image forming apparatus capable of shortening the time from the standby state to the image forming operation until the completion.

  A fixing device driving method according to the present invention is a fixing device driving method for driving a fixing device including a heating rotating member heated by a heating unit and a pressure rotating member pressed against the heating rotating member, wherein the fixing device driving method includes: A temperature detecting step for detecting a surface temperature of the pressure rotating member at a time when the apparatus shifts from the standby state to an image forming operation, and the heating rotating member and the pressure rotating based on the temperature detected in the temperature detecting step. A determining step for determining a rotation speed of the member; and a driving step for rotating the heating rotation member and the pressure rotation member at the rotation speed determined in the determination step. Thereby, it is possible to shorten the time from the standby state to the completion of the image forming operation.

Hereinafter, a fixing device, an image forming apparatus, and a fixing device driving method according to the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of the entire image forming apparatus according to the present embodiment.
As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 10, a paper feeding unit 20, a fixing unit 30, and a control unit 40, and is configured to be able to form an image on a recording sheet S. .

The sheet feeding unit 20 includes a sheet feeding cassette 21, a feeding roller 22, a timing roller pair 23, and the like. The sheet S accommodated in the sheet feeding cassette 21 is fed out one by one by the sheet feeding roller 21, and a sheet conveyance path (broken line) ) Along the timing roller pair 23 to the transfer position P.
The image forming unit 10 uniformly charges the photosensitive drum 11, and exposes the charged surface of the photosensitive drum 11 by scanning with a laser beam emitted from a laser diode (not shown) inside the printer head 12. After forming the electrostatic latent image on the body drum 11 and developing the formed electrostatic latent image to form a toner image, the toner image is transferred to the sheet S from the paper feeding unit 20 at the transfer position P. The image is transferred by the electrostatic action of the roller 13.

FIG. 2 is a schematic diagram illustrating the configuration of the fixing unit 30. The fixing unit 30 includes a fixing roller 31, a fixing belt 32, a heater 33 disposed inside the fixing roller 30, a pressure roller 34, temperature sensors 35 and 37, and a pad 36.
The fixing belt 32 is hung on the fixing roller 31 and the pad 36, and rotates as the fixing roller 31 rotates in the direction A in the drawing.

The pressure roller 34 is brought into pressure contact with the portion of the fixing belt 32 hung on the pad 36 to form a nip portion. The temperature sensor 35 detects the surface temperature of the pressure roller 34, and the temperature sensor 37 detects the surface temperature of the fixing roller 31.
Although not shown, the fixing unit 30 includes a drive unit 38 (see FIG. 3) that rotates the fixing roller 31 in the direction A in the drawing and the pressure roller 34 in the direction B in the drawing.

FIG. 3 is a block diagram illustrating a configuration of the control unit 40.
As shown in the figure, the control unit 40 includes a CPU 41, a RAM 42, a ROM 43, and a rotation speed data storage unit 44 as main components.
The ROM 43 stores various programs such as a program related to an image forming operation in the image forming unit 10.

The CPU 41 reads a necessary program from the ROM 43 and controls the operations of the image forming unit 10, the paper feeding unit 20, and the fixing unit 30 in an integrated manner to execute a smooth image forming operation.
The RAM 42 is used as a work area when the CPU 101 executes a control program.
The rotation speed data storage unit 44 stores data relating to an appropriate rotation speed with respect to the surface temperature of the pressure roller 34.

The control unit 40 executes an image forming operation, receives a detection signal from the temperature sensor 37, monitors the temperature of the fixing roller 31, and maintains the temperature of the fixing roller 31 at a predetermined fixing temperature. The power supply amount to the heater 33 is controlled. Although details will be described later, the control unit 40 receives a detection signal from the temperature sensor 35 and, based on the received information, according to the data stored in the rotational speed data storage unit 44 and the fixing roller 31 and The rotational speed of the pressure roller 34 is determined.
(Operation)
Next, the operation of the fixing unit 30 will be described. When the image forming apparatus 1 is turned on, a so-called warm-up operation is performed. In the warm-up operation, the fixing roller 31, the fixing belt 32, and the pressure roller 34 are rotationally driven by the driving unit 38. The fixing belt 32 is heated to 190 ° C. by the heating by the heater 33. The pressure roller 34 is heated to 120 ° C. due to the transition of heat from the fixing roller 31 as it rotates.

  When the image forming apparatus 1 receives a print job in this state, an image forming operation is executed. In the image forming operation, the image forming unit 10 forms a toner image, transfers the toner image to the sheet S, and the toner image (unfixed image) is transferred to the pressure contact portion between the fixing belt 32 and the pressure roller 34. The toner image T is fixed by heating and pressurizing through the sheet S, and the sheet S is discharged onto the discharge tray 26 via the discharge roller pair 25.

  After the image forming operation is completed, the image forming apparatus 1 enters a standby state until the next job is received. In the standby state, the rotation of the fixing roller 31 and the pressure roller 34 of the fixing unit 30 is stopped. The fixing roller 31 is controlled to maintain a fixing temperature (190 ° C. in this example) by heating by the heater 33. Since the pressure roller 34 is rotated as described above, the heat of the fixing roller 31 is received via the fixing belt 32 and is kept at a predetermined temperature (120 ° C. in this example), so that the rotation is stopped. In the standby state, the transition of heat from the fixing roller 31 to the pressure roller 34 decreases, so that the surface temperature of the pressure roller 34 gradually decreases.

Next, an operation when the image forming apparatus 1 receives a new job and starts an image forming operation when the image forming apparatus 1 is in a standby state will be described.
FIG. 4 is a flowchart illustrating control of the fixing unit 30 when the image forming apparatus 1 in the standby state starts an image forming operation.
When the image forming apparatus 1 shifts from the standby state to the image forming operation (step S101: Yes), the surface temperature of the pressure roller 34 at this time is detected by the temperature sensor 35 (step S102). Then, based on the detected surface temperature of the pressure roller 34, the rotational speeds of the fixing roller 31 and the pressure roller 34 are determined (step S103). Specifically, the rotational speed is determined from the graph shown in FIG.

FIG. 5 is a graph showing the relationship between the temperature of the pressure roller 34 and the rotational speed when shifting to the image forming operation. The vertical axis of the graph represents the rotational speed [mm / s] of the roller, and the horizontal axis represents the surface temperature [° C.] of the pressure roller 34 during the transition to the image forming operation.
The graph shown in FIG. 5 is expressed by Equation 1 where x [° C.] is the surface temperature of the pressure roller and y [mm / s] is the rotation speed at the time of shifting to the image forming operation.

y = −1.25x + 200 (Formula 1)
Data related to Equation 1 is stored in the rotation speed data storage unit 44, and the CPU 41 uses Equation 1 to determine the rotation speed based on the temperature of the pressure roller 34 during the transition to the image forming operation.
Here, an experiment conducted to obtain the graph shown in FIG. 5 will be described. When the surface temperature of the pressure roller is a specific temperature at the start of the image forming operation, the inventors collect data with different rotational speeds, and when the rotational driving is performed at which rotational speed, the fixing belt An experiment was conducted to determine whether the pressure roller reached the predetermined temperature in the shortest time.

FIG. 6 shows data of an experiment performed to obtain the graph shown in FIG. 5, and is data when the temperature of the pressure roller is 50 ° C. at the start of the image forming operation.
In the following, an image forming operation is started from a standby state, and the fixing roller 31 is deprived of heat by the pressure roller 34 as it rotates, so that the temperature drops from the fixing temperature (190 ° C. in this example). The time required to return to the fixing temperature is t1, and the pressure roller 34 receives heat from the fixing roller 31 as it rotates, and the temperature is raised from the standby state temperature to a predetermined temperature (120 ° C. in this example). Let t2 be the time required for.

In FIG. 6, the data is obtained when the rotational speed is increased from (a) to (b) and (c).
In the example shown in FIG. 6A, since the rotation speed is slow and the amount of heat per unit time transmitted from the fixing roller 31 to the pressure roller 34 is small, the time t1 required for the fixing roller 31 to recover to the fixing temperature. Is shortened, but the time t2 until the pressure roller 34 is heated to a predetermined temperature is lengthened.

At this time, both the fixing roller 31 and the pressure roller 34 reach a predetermined temperature, and the time t when the fixing operation can be started is t = t2≈28 seconds.
In the example shown in FIG. 6C, since the rotation speed is high and the amount of heat per unit time transmitted from the fixing roller 31 to the pressure roller 34 is large, the time until the pressure roller 34 rises to a predetermined temperature. Although t2 becomes shorter, time t1 required for the fixing roller 31 to recover to the fixing temperature becomes longer.

At this time, the time t required for both the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature and start the fixing operation is t = t1≈20 seconds.
In the example shown in FIG. 6B, the rotation speed is such that the time t1 required for the fixing roller 31 to recover to the fixing temperature is equal to the time t2 until the pressure roller 34 rises to a predetermined temperature. is doing.

At this time, the time t required for both the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature and start the fixing operation is t = t1 = t2≈17 seconds.
As described above, when the rotation speed of the pressure roller 34 is changed and the time t required for both the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature and start the fixing operation is measured, t1 is obtained. It was found that the time t was the shortest when the rotation was performed at a rotation speed of t2.

  In the above, the case where the temperature of the pressure roller at the time of shifting to the image forming operation is 50 ° C. was examined. The time t required for both the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature and start the fixing operation is the shortest when t1 = t2 as in FIG. 6B. Turned out to be.

Therefore, the inventors have determined the rotation speed R at which t1 = t2 when the temperature of the pressure roller during the image forming operation transition is 40 ° C. to 120 ° C.
And the graph as shown in FIG. 5 was obtained by plotting the rotational speed R in each calculated | required temperature. Note that the relationship between the temperature of the pressure roller and the rotational speed at the time of transition to the image forming operation varies depending on the specifications of the fixing unit 30. When the relationship between the temperature of the pressure roller and the rotation speed at the time of transition to the image forming operation is represented in a graph, it may be a straight line with a downward slope as shown in FIG. In some cases.

As described above, the present inventors have found that the time required for each of the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature depends on the surface temperature and the rotation speed of the pressure roller 34 when the image forming operation is shifted. I found out.
As a result of diligent research by the present inventors, the rotation speed is controlled so as to satisfy the relationship shown in FIG. 5 until the fixing roller 31 and the pressure roller 34 reach a predetermined fixing temperature. It was derived that the time required can be minimized.

  Returning to FIG. 4, when the rotation speed is determined in step S103, the drive unit 38 rotates the fixing roller 31 and the pressure roller 34 at the determined rotation speed until the temperature reaches a predetermined temperature (step S104). When the fixing roller 31 and the pressure roller 34 are each heated to a predetermined temperature (step S105), the sheet S on which the toner image (unfixed image) is transferred to the pressure contact portion between the fixing belt 32 and the pressure roller 34 is transferred. A fixing operation for passing the toner image and fixing the toner image by heating and pressing is executed (step S106). It should be noted that the rotation speed of the fixing roller 31 and the pressure roller 34 when executing the fixing operation can be switched to an optimal rotation speed, so that a smooth fixing operation can be performed.

FIG. 7 is a graph showing the effect of the fixing device according to the present embodiment. The vertical axis of the graph represents the time [seconds] required for both the fixing roller 31 and the pressure roller 34 to reach a predetermined temperature, and the horizontal axis represents the surface temperature of the pressure roller 34 during the transition to the image forming operation. [° C].
In the embodiment, the rotation speed is changed based on the surface temperature of the pressure roller at the time of shifting to the image forming operation. In Comparative Examples 1 to 3, regardless of the surface temperature of the pressure roller at the time of shifting to the image forming operation, It is always rotating at a constant rotation speed. That is, the rotation speed is 50 mm / s in Comparative Example 1, the rotation speed is 100 mm / s in Comparative Example 2, and the rotation speed is 150 mm / s in Comparative Example 3.

From FIG. 7, as compared with Comparative Examples 1 to 3, the fixing roller 31 and the pressure roller are kept at a predetermined temperature in the example regardless of the temperature of the pressure roller at the time of shifting to the image forming operation. It turns out that the time to become short.
As described above, the fixing roller 31 and the pressure roller 34 are each set to a predetermined temperature by determining the rotation speed based on the temperature of the pressure roller 34 at the time of transition from the standby state to the image forming operation. It is possible to shorten the time required until the transition from the standby state to the image forming operation and completion.

  The present invention is not limited to the above-described fixing device and image forming apparatus, and may be a method for driving the fixing unit and a program for executing the method by a computer. The program according to the present invention includes, for example, a magnetic disk such as a magnetic tape and a flexible disk, an optical recording medium such as a DVD-ROM, DVD-RAM, CD-ROM, CD-R, MO, and PD, and a flash memory recording medium. It can be recorded on various computer-readable recording media, and may be produced, transferred, etc. in the form of the recording medium, wired and wireless various networks including the Internet in the form of programs, In some cases, the data is transmitted and supplied via broadcasting, telecommunication lines, satellite communications, or the like.

  Further, the program of the present invention does not need to include all modules for causing the computer to execute the processing described above. For example, a separate information processing apparatus such as a communication program or a program included in an operating system (OS) The computer may execute each process of the present invention using various general-purpose programs that can be installed in the computer. Therefore, it is not always necessary to record all the modules on the recording medium, and it is not always necessary to transmit all the modules. Further, there are cases where predetermined processing can be executed using dedicated hardware.

<Modification>
As described above, the present invention has been described based on the embodiments. However, the content of the present invention is not limited to the specific examples shown in the above-described embodiments. For example, the following modifications are possible. Can think.
(1) In the above description, when the rotational speed is determined based on the temperature of the pressure roller at the time of transition to the image forming operation, the graph relationship as shown in FIG. 5 is used, but the present invention is not limited to this. FIG. 8 is a table showing the relationship between the temperature of the pressure roller 34 and the rotation speed when shifting to the image forming operation. As shown in FIG. 8, when the temperature of the pressure roller 34 at the time of transition to the image forming operation is less than 50 ° C., the rotation speed is 150 mm / s, and when it is 50 ° C. or more and less than 100 ° C., 100 mm / s, 100 ° C. or more. In some cases, the rotational speed may be determined such as 50 mm / s, and control may be performed to switch the rotational speed in several steps based on the temperature of the pressure roller 34 during the transition to the image forming operation.

  (2) In the above case, when the rotation of the fixing roller 31 and the pressure roller 34 is stopped and the fixing roller 34 is maintained at the fixing temperature, the standby state is set, and the image forming operation is shifted from the standby state. Although the configuration for adjusting the rotation speed is described above, the image forming operation is started from the state where the rotation of the fixing roller 31 and the pressure roller 34 is stopped and the fixing roller 31 is maintained at a temperature lower than the fixing temperature for the purpose of power saving. The concept of the present invention can also be applied to the case of shifting to (1).

(3) In the above description, the drive unit 38 has been described as being configured to rotate both the fixing roller 31 and the pressure roller 34. For example, the drive unit 38 rotates only the pressure roller 34. Thus, the fixing roller 31 may be driven.
(4) In the above description, the fixing device includes the fixing roller 31, the fixing belt 32, and the pressure roller 34 as shown in FIG. 2, but is not limited thereto. For example, the configuration of the fixing device may be as shown in FIG. FIG. 9 is a schematic diagram illustrating a modification of the fixing device.

FIG. 9A shows an example of a type of fixing device in which a fixing roller 51 having a heater 52 inside and a pressure roller 54 are pressed to form a nip portion.
FIG. 9B shows a fixing belt 61 heated by an IH heater 62, a pressure roller 65 that is pressed against the fixing belt 61 to form a nip portion, and an exterior that has a heater 68 and heats the pressure roller 65. This is an example of a fixing device having a heating roller 67.

FIG. 9C shows an example of a fixing device in which the fixing belt 71 is heated by the sheet heater 72. Grease is applied to the surface of the pad 74, and an internal belt 73 is externally fitted. The fixing belt 71 is hung on the sheet heater 72 and the internal belt 73 and forms a nip portion in pressure contact with the pressure roller 75.
In addition, what is indicated by the drawing numbers 53, 55, 63, 66, 69, and 76 are all temperature sensors.

  In any of the above-described modifications of the fixing device, the pressure roller is a fixing device in which the temperature rises mainly due to thermal transition from the fixing roller or the fixing belt. In such a fixing device, it is effective to apply the present invention. Further, it is effective to apply the present invention to a fixing device having a configuration in which the heat capacity of the pressure roller is larger than that of the fixing roller and the fixing belt.

  The present invention can provide a fixing device and an image forming apparatus that can shorten the time from the standby state to the completion of the image forming operation, and thus the industrial utility value thereof is extremely high.

1 is a diagram illustrating a schematic configuration of an entire image forming apparatus according to an exemplary embodiment. 2 is a schematic diagram illustrating a configuration of a fixing unit 30. FIG. 3 is a block diagram illustrating a configuration of a control unit 40. FIG. 4 is a flowchart illustrating control of the fixing unit 30 when the image forming apparatus 1 in a standby state starts an image forming operation. It is a graph which shows the relationship between the temperature of the pressure roller 34 at the time of image forming operation transfer, and a rotational speed. FIG. 6 shows data of an experiment performed to obtain the graph shown in FIG. 5 and is data when the temperature of the pressure roller is 50 ° C. at the start of the image forming operation. 5 is a graph showing the effect of the fixing device according to the present embodiment. 4 is a table showing the relationship between the temperature of the pressure roller 34 and the rotation speed when shifting to the image forming operation. FIG. 10 is a schematic diagram illustrating a modification of the fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image forming part 20 Paper feeding part 30 Fixing part 31 Fixing roller 32 Fixing belt 33 Heater 34 Pressure roller 35, 37 Temperature sensor 36 Pad 38 Drive part 40 Control part 44 Rotation speed data storage part

Claims (6)

A fixing device mounted on an image forming apparatus,
Heating means;
A heating rotating member heated by the heating means;
A pressure rotating member that is in pressure contact with the heating rotating member;
Temperature measuring means for detecting the surface temperature of the pressure rotating member;
Drive means for rotationally driving the heating rotary member and the pressure rotary member;
Determining means for determining the rotation speeds of the heating rotating member and the pressure rotating member based on the temperature detected by the temperature detecting means when the image forming apparatus shifts from the standby state to the image forming operation. A fixing device characterized by. The driving means includes
After the image forming operation of the image forming apparatus is started, the heating rotation member is at a first predetermined temperature and the pressure rotation member is at a second predetermined temperature. Rotating and driving the heating rotary member and the pressure rotary member,
After the heating rotating member reaches a first predetermined temperature and the pressure rotating member reaches a second predetermined temperature, the heating rotating member and the pressure rotating member are driven to rotate at a predetermined rotation speed. The fixing device according to claim 1. The determining means includes
After the image forming apparatus shifts from the standby state to the image forming operation, the heating rotating member is deprived of heat by the pressurizing rotating member as it rotates, and the temperature drops from the first predetermined temperature again. Time required for recovering to the first predetermined temperature and time required for the pressurizing rotating member to receive heat from the heating rotating member along with the rotation and raise the temperature from the standby state temperature to the second predetermined temperature. The fixing device according to claim 1, wherein the rotation speed is determined to be equal to each other. When the detected temperature detected by the temperature detecting means is taken on the horizontal axis and the rotational speed determined by the determining means is taken on the vertical axis, the graph showing the relationship between the detected temperature and the rotational speed is lowered to the right. The fixing device according to claim 1, wherein the fixing device is characterized in that:   An image forming apparatus comprising the fixing device according to claim 1. A fixing device driving method for driving a fixing device comprising a heating rotating member heated by a heating means and a pressure rotating member pressed against the heating rotating member,
At the time when the image forming apparatus shifts from the standby state to the image forming operation, a temperature detecting step for detecting the surface temperature of the pressure rotating member;
A determination step for determining a rotation speed of the heating rotary member and the pressure rotary member based on the temperature detected in the temperature detection step;
And a driving step of rotating the heating rotary member and the pressure rotary member at the rotational speed determined in the determining step.

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