JP2003131517A - Method for controlling fixing device, fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of controlling a fixing device by which desired fixation properties can be stably maintained over a long period of time and stabilized fixation properties are obtained irrespective of the changes or variations of fixing process conditions, the variation of operating environment, etc., and to provide the fixing device and an image forming apparatus provided with this fixing device. SOLUTION: In the method of controlling the fixing device of a belt fixing system, the temperature of a pressure roller is detected, at least the temperature (a) of a objective heating roller is calculated on the basis of the detected temperature (b) of a pressing roller, load nip time (c), pseudo nip time (d), and load nip specific pressure (e), and the operating state of the heating source of the heating roller is controlled on the basis of the temperature (a) of the objective heating roller. The fixing device has a controller which implements the control method. The image forming apparatus is provided with the fixing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device control method, a fixing device, and an image forming apparatus.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, a heat and pressure type fixing device is widely used to fix an unfixed toner image formed on a recording material such as transfer paper. Among the heating and pressurizing type fixing devices, as a fixing device that can obtain relatively stable fixing properties,
For example, a heating roller having a heating source composed of a heater lamp inside, a supporting roller arranged so as to extend in parallel with the heating roller, a heating roller, and a fixing belt wound around the supporting roller, A belt fixing method is known, which comprises a pressure roller arranged so that a nip portion is formed between the supporting roller and the heating roller by pressing the fixing roller through the fixing belt. There is. In the fixing device using the belt fixing method, the pressure roller is configured such that an elastic layer made of, for example, silicone rubber is formed on the surface of a core metal made of metal such as aluminum.

In such a fixing device, for example,
A temperature detecting means for detecting the temperature of the pressure roller is arranged, and the target heating roller temperature at which the desired fixing process is to be performed,
The temperature at the nip portion is set to a predetermined temperature state by setting on the basis of the temperature information detected by the pressure roller obtained by the temperature detecting means, and by turning on / off the lighting state of the heater lamp in the heating roller by an appropriate control mechanism. It is controlled to be maintained at.

However, in the control method in which the target heating roller temperature is set only on the basis of the pressure roller detection temperature information, the hardness of the elastic body forming the coating layer in the pressure roller decreases due to long-term use. , If the nip width or nip surface pressure fluctuates, or if the operating environment of the fixing device such as ambient temperature and humidity changes,
There is a problem that the desired fixability cannot be maintained stably, and as a result, the glossiness of the formed image varies. Further, when the fixing process conditions such as the moving speed of the fixing belt and the fixing load are changed, the same fixing property as before the change cannot be maintained, and therefore,
An image having a certain gloss cannot be reliably formed regardless of the fixing process conditions.

[0005]

The present invention has been made based on the above circumstances, and its purpose is to:
(EN) A method of controlling a fixing device capable of stably maintaining desired fixability for a long period of time and obtaining stable fixability regardless of changes or fluctuations in fixing process conditions and changes in operating environment. Especially. Another object of the present invention is to be able to maintain desired fixability stably over a long period of time, and to obtain stable fixability regardless of changes or fluctuations in fixing process conditions and changes in operating environment. It is to provide a fixing device. Still another object of the present invention is to be able to maintain desired fixability stably over a long period of time, and to obtain stable fixability regardless of changes or fluctuations in fixing process conditions and changes in operating environment. Therefore, it is an object of the present invention to provide an image forming apparatus capable of surely forming an image having a uniform glossiness.

[0006]

According to a control method of a fixing device of the present invention, at least one heating roller having a heating source is provided so as to extend in parallel with the heating roller.
Nip portion between the individual support rollers, the heating roller and the fixing belt hung over the supporting roller, and the fixing roller or the heating roller by pressing the fixing belt via the fixing belt. A method of controlling a fixing device comprising a pressure roller arranged to form a pressure roller, the method comprising the steps of: (a) detecting the temperature of the pressure roller; Pressure roller detection temperature (b), load nip time (c) calculated by the following equation (1), pseudo nip time (d) calculated by the following equation (2), and the following equation (3)
The step (b) of calculating the target heating roller temperature (a) based on the load nip surface pressure (e) calculated by the step (b), and the target heating roller temperature (a) obtained by the step (b)
And (c) controlling the operating state of the heating source in the heating roller based on the above.

[0007]

[Equation 3] Formula (1) Load nip time (c) = L1 / V Formula (2) Pseudo nip time (d) = L2 / V Formula (3) Load nip surface pressure (e) = P / (L1 × W)

[Where L1 is the width in the moving direction of the fixing belt on the surface of the portion of the fixing belt that is nipped by the supporting roller or the heating roller and the pressure roller, and L2 is only the pressure roller of the fixing belt. The width in the moving direction of the fixing belt on the surface of the portion in contact with
V is the moving speed of the fixing belt, W is the width in the direction orthogonal to the moving direction of the fixing belt on the surface of the portion of the fixing belt sandwiched by the support roller or the heating roller and the pressure roller, and P is The load applied to the portion of the fixing belt sandwiched by the support roller or the heating roller and the pressure roller is shown. ]

In the control method of the fixing device of the present invention,
In the step (b), it is preferable to calculate the target heating roller temperature (a) that satisfies the following expression (4).

[0010]

[Equation 4] Formula (4) A x target heating roll temperature (a) + B x pressure roller detection temperature (b)             + C x load nip time (c) + D x pseudo nip time (d)             + E × Load nip surface pressure (e) + F = 0 [However, A, B, C, D, E and F are all constants. ]

In the control method of the fixing device of the present invention, the ambient temperature and humidity are detected, and the constant in the above equation (4) may be changed according to the detected ambient temperature and humidity. preferable. Further, at least the value of L1 in the above formula (1) and the above formula (3) and the value of L2 in the above formula (2) are measured, and the load nip time (c) and the pseudo nip are measured based on these measured values. It is preferable that the time (d) and the load nip surface pressure (e) are calculated.

In the fixing device of the present invention, a heating roller having a heating source, at least one supporting roller provided so as to extend in parallel with the heating roller, and the heating roller and the supporting roller. The passed fixing belt, a pressure roller arranged so that a nip portion is formed between the fixing belt and the supporting roller or the heating roller through the fixing belt, and the pressure roller. In a fixing device comprising a pressure roller temperature detecting means for detecting a temperature of a pressure roller and a control mechanism for controlling an operating state of a heating source in the heating roller, the control mechanism includes the pressure roller temperature detecting means. Pressure roller detection temperature (b) obtained by the above equation, load nip time (c) calculated by the above equation (1), and pseudo nip calculated by the above equation (2) The target heating roller temperature (a) is set based on the interval (d) and the load nip surface pressure (e) calculated by the above equation (3), and heating is performed based on the target heating roller temperature (a). It is characterized by controlling the operating state of the heating source in the roller.

In the fixing device of the present invention, it is preferable that the control mechanism sets the target heating roller temperature (a) by the equation (4). The control mechanism has an operating environment detecting means for detecting ambient temperature and humidity, and the control mechanism changes the constant in the formula (4) according to the ambient temperature and humidity obtained by the operating environment detecting means. It is preferable to have a function. Further, the control mechanism can externally input at least the value of L1 in the above formula (1) and the above formula (3) and the value of L2 in the above formula (2), and the input value of L1 and L2. It is preferable to have a function of calculating the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e) based on the value of.

An image forming apparatus of the present invention is characterized by including the above-mentioned fixing device.

[0015]

According to the present invention, the target heating roller temperature (a)
Is optimum according to the pressure roller detection temperature (b) actually detected in consideration of the fixing process condition including the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e). Since the temperature is set to a proper temperature state, the fixing process thereafter can be executed in a state where the temperature of the nip portion is controlled to the optimum temperature state. Therefore,
Even if the fixing process conditions such as the nip width fluctuate with time, the target heating roller temperature (a) is changed according to the fluctuation amount.
By setting, the desired fixability can be maintained stably over a long period of time, and stable fixability can be obtained regardless of changes in the fixing process conditions and changes in the operating environment.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. <First Embodiment> FIG. 1 is an explanatory view showing the outline of the configuration of a color image forming apparatus according to the first embodiment of the present invention, and FIG. 2 is a fixing process in the color image forming apparatus shown in FIG. It is explanatory drawing which shows the outline of a structure inside an apparatus. In this color image forming apparatus, four toner image forming units 10Y, 10M, 10C and 10K for forming toner images of yellow toner, magenta toner, cyan toner and black toner are arranged in this order. There is. Toner image forming unit 10Y,
In each of 10M, 10C, and 10K, an image carrier 12 made of a rotary drum type photoconductor is provided, and the image carrier 12 is provided in the outer peripheral surface region of the image carrier 12 along the rotation direction thereof. A charging unit 11 including a charging roller for charging, an exposing unit 15 that scans a laser in accordance with document image information to form an electrostatic charge image on the image carrier 12, and the electrostatic charge image is a yellow toner, a magenta toner, and a toner image, respectively. Developing devices 13Y, 13M, 13C for visualizing with cyan toner and black toner to form a toner image,
13K are arranged in this order, and in order to remove the toner remaining on the outer peripheral surface of the image carrier 12 that has passed primary transfer mechanisms 31Y, 31M, 31C and 31K described later, a cleaning blade 14 Is provided and configured.

These toner image forming units 10Y, 1
In relation to 0M, 10C and 10K, an intermediate transfer member 24 composed of an endless belt movable along an endless track by a roller group including a driving roller 21, a tension roller 22 and a plurality of supporting rollers 23 is provided. There is. Then, the toner image forming units 10Y, 10M, 10C, 1
Developing devices 13Y, 13 for the image carrier 12 at each of 0K
Transfer rollers for pressing the intermediate transfer body 24 between the image carrier 12 and the image carrier 12 are arranged at positions downstream of the M, 13C, and 13K, whereby the primary transfer mechanisms 31Y, 31M, and 3 are provided.
1C and 31K are configured.

Primary transfer mechanism 31Y, 31M, 31C, 3
In each of 1K, an appropriate transfer potential is applied to the transfer roller, and by the action, the toner image forming unit 1
Developing device 13Y in 0Y, 10M, 10C, 10K,
The original toner image formed on each image carrier 12 by 13M, 13C, and 13K is electrostatically attracted and transferred to the surface of the intermediate transfer member 24 to be fixed, whereby the primary toner image of the original toner image is transferred. Transfer is performed.

A secondary transfer roller 32 that presses the belt of the intermediate transfer body 24 is provided in a part of the moving path of the intermediate transfer body 24.
A and a backup roller 32B are provided,
An appropriate transfer potential is applied to the secondary transfer roller 32A, and by its action, the transfer toner image on the intermediate transfer body 24 is transferred to a recording medium (not shown) that is conveyed in synchronization with the secondary transfer. The mechanism 32 is configured. In the secondary transfer mechanism 32, the secondary transfer toner image is formed on the recording medium according to the same principle as the primary transfer mechanism 31 described above. In addition, the intermediate transfer member cleaning blade 25
It is arranged at a lateral position of the drive roller 21.

In the above, it is possible to operate all four toner image forming units 10Y, 10M, 10C and 10K, or it is possible to operate any one of the toner image forming units 10Y, 10M, 10C and 10K.
When operating 10M, 10C and 10K, the original toner image formed on each image carrier 12 is transferred to the intermediate transfer member 24.
By performing the primary transfer in the state of sequentially overlapping with,
A full-color toner image is formed.

A fixing device 40 is provided downstream of the secondary transfer mechanism 32. As shown in FIG. 2, the fixing device 40 internally includes a halogen heater lamp 4 as a heating source.
A heating roller 41 having two, a supporting roller 43 provided so as to extend in parallel with the heating roller 41, an endless fixing belt 44 wound around the heating roller 41 and the supporting roller 43, and the fixing belt 44. A pressure roller 45 having a halogen heater lamp 46 as a heating source is provided so that a nip portion N is formed between the support roller 43 and the fixing belt 44 by pressing the support roller 43 through the pressure roller 45. It becomes. The nip portion N is the fixing belt 44.
Has a load nip region N1 formed by being nipped by the support roller 43 and the pressure roller 45, and a pseudo nip region N2 formed by the fixing belt 44 contacting only the pressure roller 45, In this example, the pseudo nip region N2 is formed on the upstream side of the load nip region N1. Further, the fixing device 40 is provided with a heating roller temperature detecting means 47 for detecting the temperature of the heating roller 41 in a state of abutting on or in close proximity to the surface of the heating roller 41, and the temperature of the pressure roller 45. The pressure roller temperature detecting means 48 for detecting the temperature is provided in the state of being in contact with or close to the surface of the pressure roller 45. The fixing device 40 is provided with a control mechanism (not shown) that controls the lighting states of the halogen heater lamp 42 of the heating roller 41 and the halogen heater lamp 46 of the pressure roller 45.

The heating roller 41 is formed of a metal cylindrical body extending in the width direction of the recording material to be conveyed. The outer diameter of the heating roller 41 is, for example, 30 to 80 mm, preferably 40 to 50 mm. The wall thickness of the cylindrical body forming the heating roller 41 is, for example, 1 to 5 mm, preferably 2 to 3 mm. The metal forming the cylindrical body forming the heating roller 41 is not particularly limited and various ones can be used, and specific examples thereof include metals such as aluminum, iron and copper or alloys thereof. it can.

The supporting roller 43 is made of a metal cored bar 43.
A and an elastic layer 43B formed on the surface of the cored bar 43A
It is composed of and. The metal forming the cored bar 43A is not particularly limited, but examples thereof include metals such as iron, aluminum and copper, and alloys thereof. The elastic body forming the elastic layer 43B is not particularly limited, and various soft rubbers such as urethane rubber and silicone rubber and sponge rubber can be exemplified. The thickness of the elastic layer 43B is, for example, 1 to
It is set to 10 mm, preferably 1 to 5 mm.

As the fixing belt 44, an endless belt base material having a coating layer formed on the surface thereof with an elastic layer interposed therebetween can be preferably used. A metal material such as nickel or a resin material such as polyimide can be used as a material forming the belt base material. The thickness of the belt base material is, for example, 40 to 40 when it is made of a metal material.
When the resin material is 60 μm, for example, 5
It is 0 to 90 μm. As a material for forming the elastic layer,
For example, silicone rubber or the like can be used. Moreover, the thickness of the elastic layer is, for example, 150 to 250 μm. Examples of the material forming the coating layer include polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (P
Fluororesin such as FA) can be used. Moreover, the thickness of the coating layer is, for example, 30 to 50 μm.

The pressure roller 45 is made of a metal cored bar 45.
A and an elastic layer 45B formed on the surface of the core metal 45A
And a coating layer 45C formed on the surface of the elastic layer 45B
It is composed of and. The metal constituting the core metal 45A is not particularly limited, but examples thereof include metals such as iron, aluminum, copper, and alloys thereof. The elastic body forming the elastic layer 45B is not particularly limited, and various soft rubbers such as urethane rubber and silicone rubber and sponge rubber can be exemplified. The thickness of the elastic layer 45B is, for example, 1 to
It is set to 10 mm, preferably 2 to 5 mm. The coating layer 45C is made of, for example, a fluororesin, and its specific example is polytetrafluoroethylene (PTF).
E), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and the like. The Asker C hardness of the pressure roller 45 is 3
The angle is 5 to 70 °, preferably 40 to 55 °.
Here, the Asker C hardness is a value measured under a load condition of 500 g.

The control mechanism comprises a pressure roller temperature detecting means 48.
The pressure roller detection temperature (b) obtained by the above equation, the load nip time (c) calculated by the following equation (1), the pseudo nip time (d) calculated by the following equation (2), and the following equation (3) ) Has a function of setting the target heating roller temperature (a) based on the load nip surface pressure (e), and specifically, the target heating roller temperature (a) is calculated by the following equation (4). Is calculated.

[0027]

[Equation 5] Formula (1) Load nip time (c) = L1 / V Formula (2) Pseudo nip time (d) = L2 / V Formula (3) Load nip surface pressure (e) = P / (L1 × W) Formula (4) A x target heating roll temperature (a) + B x pressure roller detection temperature (b)             + C x load nip time (c) + D x pseudo nip time (d)             + E × Load nip surface pressure (e) + F = 0

In the above formulas (1) to (3), L1
Is the width in the moving direction of the fixing belt 44 on the surface (that is, the load nip area N1) of the portion of the fixing belt 44 that is nipped by the support roller 43 and the pressure roller 45, and L2 is the pressing force of the fixing belt 44. The width in the moving direction of the fixing belt 44 on the surface of the portion in contact with only the pressure roller 45 (that is, the pseudo nip region N2) is shown.
Further, V indicates the moving speed of the fixing belt 44, and W indicates
A width in a direction orthogonal to the moving direction of the fixing belt 44 in the load nip region N1 of the fixing belt 44 is shown as P
Indicates a load (that is, a nip load) applied to a portion of the fixing belt 44 that is pinched by the support roller 43 and the pressure roller 45.

In the above formula (4), A, B,
C, D, E and F are all constants and can be set as follows. First, the fixing process is performed by changing the heating roller temperature, the pressure roller temperature, the load nip time, the pseudo nip time, and the load nip surface pressure for a large number of recording materials on which an unfixed toner image is formed.
A solid image is formed on the recording material, and then the glossiness of the obtained solid image is measured. Here, "glossiness" means J
75 degree specular gloss G _s (7
5 °), which can be measured with a gloss meter “VGS-1D” manufactured by Nippon Denshoku Industries Co., Ltd., for example. Then, the above fixing process condition data (heating roller temperature,
The pressure roller temperature, the load nip time, the pseudo nip time, and the load nip surface pressure) are used as explanatory variables, and the multiple regression analysis is performed while using the gloss data of the obtained fixed image as an objective variable.
The constants A, B, C, D, E and F are calculated by setting the glossiness required for the fixed image as the reference glossiness.

In such a control mechanism, the temperature state of the heating roller 41 is controlled as follows. First, when the power switch of the image forming apparatus is turned on, a halogen heater lamp 42 of the heating roller 41 and a halogen heater lamp 46 of the pressure roller 45 are turned on by a heater lamp lighting control mechanism (not shown), and the heating roller 41 is turned on. And warm-up control is performed to raise the temperature of the pressure roller 45 until it reaches a predetermined set temperature. Here, the set temperature of the heating roller 41 is a temperature at which the fixing process can be executed, unlike the target heating roller temperature (a) set for actually performing the fixing process. And
When the heating roller 41 and the pressure roller 45 reach a predetermined set temperature, the target heating roller temperature (a) is calculated by the above equation (4), whereby the lighting state of the halogen heater lamp 42 in the heating roller 41 is It is controlled based on the set target heating roller temperature (a), while
The halogen heater lamp 46 in the pressure roller 45 is controlled based on a predetermined set temperature.

To be more specific, the control device previously sets the constants A, B, C, D, E and F in the above equation (4) in accordance with the type of recording material used and the operating environment. While being set, the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e) are input.
Then, as shown in FIG. 3, the pressure roller temperature detecting means 4
The temperature detection of the outer peripheral surface of the pressure roller 45 by 8 is started, and the obtained pressure roller detection temperature (b) is read into the control mechanism [step (a)]. Further, in this step (a), the temperature of the outer peripheral surface of the heating roller 41 is detected by the heating roller temperature detecting means 47 in synchronization with the temperature detection of the pressure roller 45. Next, referring to the values of the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e), which have been input in advance, the constants A, B, C, D,
The target heating roller temperature (a) is calculated by the equation (4) in which E and F are set [step (b)]. After that, the heating roller temperature detected by the heating roller temperature detecting means 47 (a
1) is read by the control mechanism, and the determination unit compares the target heating roller temperature (a) and the heating roller detection temperature (a1) with each other. Then, the heating roller detection temperature (a
When 1) is higher than the target heating roller temperature (a), the input to the halogen heater lamp 42 is reduced or stopped, and in other cases, the halogen heater lamp 42 is maintained in the lighting state [step (c)]. On the other hand, the pressure roller detection temperature (b) detected by the pressure roller temperature detection means 48 is compared with the set temperature of the pressure roller 45, and the pressure roller detected temperature (b) is higher than the set temperature of the pressure roller 45. At times, the input to the halogen heater lamp 46 is reduced or stopped, and at other times, the halogen heater lamp 46 is maintained in a lighting state.

The above operation is repeated, and the halogen heater lamp 42 and the halogen heater lamp 46 are performed.
By controlling the lighting state of, the fixing process is performed in a state where the nip portion N is controlled to an appropriate temperature state according to the type of recording material actually used, the operating environment, and the like.

In the above, when the preferable fixing process conditions are shown, the load nip width (width L1 in the moving direction of the fixing belt 44 in the load nip region N1) is 5 to 12 mm,
The pseudo nip width (width L1 in the moving direction of the fixing belt 44 in the pseudo nip region N2) is 0 to 15 mm, the moving speed of the fixing belt 44 is 180 to 250 mm / sec, the load nip time is 20 to 67 msec, and the pseudo nip time is 0. ~
84 msec, nip load P is 400 to 800 N, area of load nip region N1 is 17 to 41 cm ² , load nip surface pressure is 98 to 470 kPa, set temperature of heating roller 41 is 180 to 230 ° C., set temperature of pressure roller 45. Is 12
It is 0 to 170 ° C. By setting such conditions, the fixing process can be performed in a state where the nip portion N is surely controlled to an appropriate temperature state.

Thus, according to the above-mentioned image forming apparatus, in the fixing device 40, the target heating roller temperature (a) satisfies the fixing process condition including the fixing nip time (c) and the fixing nip surface pressure (d). In consideration of this, an optimum temperature state corresponding to the pressure roller detection temperature (b) actually detected, that is, for example, occurs when the type of recording material used, the setting of the image forming operation, or the change of the operating environment. Since the fluctuation of the target heating roller temperature (a) to be set is set to the temperature state in which the fluctuation is compensated, the subsequent fixing process can be executed in a state in which the fixing nip portion N is controlled to the optimum temperature state, and As a result, a stable fixing property can always be obtained, and as a result, an image having a uniform glossiness can be reliably formed. Further, since the target heating roller temperature (a) is set based on the pressure roller detection temperature (b), even if the temperature of the pressure roller 45 changes minutely,
It is possible to accurately set the target heating roller temperature (a).

In the present invention, at least the function of inputting at least the value of L1 in the above formulas (1) and (3) and the value of L2 in the above formula (2) to the control mechanism in the fixing device, and the input. Value of L1 and L
By adding the function of calculating the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e) based on the value of 2, at least the above formula (1) and the above formula (3) ) Value of L1 (load nip width) and the value of L2 (pseudo nip width) in the above equation (2),
L1 and L obtained by actual measurement for each predetermined number of fixing processes
Based on these measured values, the load nip time (c), the pseudo nip time (d), and the load nip surface pressure (e) are calculated based on these measured values. Based on the calculated new load nip time (c), pseudo nip time (d) and load nip surface pressure (e),
The target heating roller temperature (a) can be set by the equation (4).

More specifically, as shown in FIG.
First, L1 (load nip width) and L2 (pseudo nip width) in an actual situation are measured, and a series of command operations performed at the time of starting the image forming operation are input to the control mechanism with actual measured values of L1 and L2. In the calculation unit of the control mechanism, the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e) are calculated by the formulas (1) to (3), and these are recorded in the recording unit. I will let you. Then, the pressure roller detection temperature (b) obtained by the pressure roller temperature detection means 48 is read into the control mechanism and recorded in the recording section of the control mechanism, the load nip time (c) based on the actual measurement value, and the pseudo. With reference to the nip time (d) and the load nip surface pressure (e), the target heating roller temperature (a) is calculated by the equation (4). In the above, L1 (load nip width) and L2 (pseudo nip width) can be measured as follows, for example. For example, a recording material having a fixed solid image formed on the entire surface with black toner is prepared.
This recording material is supplied to the fixing device which has completed warming up, and the fixing solid image formed on the recording material is moved while the fixing belt is in contact with the fixing belt over the entire load nip area and pseudo nip area. Stop. In this state, it is held for 10 to 15 seconds, for example, and then the recording material is discharged from the fixing device to the outside by a method similar to the jam processing. By performing such an operation, the fixed solid image formed on the recording material has a portion in contact with the fixing belt in the load nip area, a portion in contact with the fixing belt in the pseudo nip area, and other portions. Since these have different glossinesses, these portions can be identified. Then, by measuring the width of the portion in contact with the fixing belt in the load nip area in the fixed solid image and the width of the portion in contact with the fixing belt in the pseudo nip area, L1 (load nip width) and L2 (pseudo nip width) are measured. The measured value of (width) is obtained. Also,
By recording the program of the above operation in the control unit of the image forming apparatus, L1 (load nip width) and L2
(Pseudo nip width) can be easily measured.

According to the control method as described above, the target heating roller temperature (a) becomes the load nip time (c), the pseudo nip time (d) and the load nip surface pressure (e) obtained in the actual situation. Therefore, even when the fixing process conditions such as the load nip width and the pseudo nip width vary with time, the fixing process is optimized in accordance with the actual operating condition of the temperature of the nip portion N. It can be carried out in a state where the temperature is controlled to a stable temperature, and therefore, stable fixing property can be always obtained for a long period of time.

Further, in the present invention, the target heating is performed by changing the constants A to F in the formula (4) according to the ambient temperature and humidity and changing the constants A to F by the new formula (4). The roller temperature (a) can be set. Specifically, the operating environment is changed by changing the ambient temperature and humidity within a predetermined temperature range and humidity range, and the constants A, B, C, D, E, and F of the equation (4) in each operating environment are calculated. The constants A, B, C, D, E, and F for each operating environment are calculated and recorded in advance in the recording unit of the control mechanism. Then, the operating environment detecting means detects the ambient temperature and humidity, and according to the obtained ambient temperature and humidity, selects and changes the corresponding constant from among the stored constants for each operating environment, The target heating roller temperature (a) is calculated by the equation (4) in which the constant is changed. According to the control method as described above, the constant of the formula (4) is changed according to the actual operating environment, so that even if the operating environment changes, the fixing process is performed with the temperature of the nip portion N It can be executed in a state in which the temperature is controlled to an optimum temperature state according to the actual operating environment, and therefore, stable fixing performance can be obtained for a long period of time regardless of the operating environment.

The above-described method for controlling the fixing device in the image forming apparatus has a target heating roller temperature calculating step for calculating the target heating roller temperature (a) by the above equation (4). Instead of the temperature calculation step, a specific individual target heating roller temperature (a) corresponding to the detected pressure roller detection temperature (b) is calculated in advance by the above formula (4) and recorded, It is possible to have a step of directly selecting the target heating roller temperature (a) from the pressure roller detection temperature information obtained by the pressure roller temperature detection means 48. In this case, it is not necessary to calculate the target heating roller temperature (a) using the above equation (4), so that the setting of the target heating roller temperature can be simplified, and accordingly, the heating roller 41 The temperature can be controlled very easily. Moreover, since the selected target heating roller temperature (a) is calculated in advance by the equation (4), the temperature state of the heating roller 41 can be controlled with high reliability.

<Second Embodiment> FIG. 5 is an explanatory sectional view showing the outline of the internal structure of a fixing device in an image fixing device according to a second embodiment of the present invention. The apparatus has the same configuration as the image fixing apparatus according to the first embodiment except the fixing apparatus.

The fixing device 50 has a heating roller 51 having a halogen heater lamp 52 as a heating source therein, a first supporting roller 53A provided separately from the heating roller 51 so as to extend in parallel with the heating roller 51, and a heating roller 51. And the first
Second supporting roller 53B provided separately from each other so as to extend in parallel with each of the supporting rollers 53A and the heating roller 5.
1, first support roller 53A and second support roller 5
The endless fixing belt 54 hung around 3B and the heating roller 51 are pressed through the fixing belt 54 to form a nip portion N between the fixing belt 54 and the fixing belt 54. A pressure roller 55 having a halogen heater lamp 56 as a heating source is provided inside.
In the nip portion N, the load belt nip region N1 formed by the fixing belt 54 being pressed by the heating roller 51 and the pressure roller 55, and the fixing belt 54 being pressed by the pressure roller 55.
Pseudo nip region N formed by contacting only
2 and in this example, the pseudo nip region N2 is formed on the downstream side of the load nip region N1. The first support roller 53A connects the fixing belt 54 to the pressure roller 55.
Has a function as a separation roller for separating the fixing belt 54 and a function as a tension roller for applying a constant tension to the fixing belt 54, and by moving the first support roller 53A, the pseudo nip width and the fixing are fixed. Belt 5
The tension applied to 4 can be adjusted. Further, the fixing device 50 is provided with a heating roller temperature detecting means 57 for detecting the temperature of the heating roller 51 in a state of abutting on or close to the surface of the heating roller 51, and the temperature of the pressure roller 55. The pressure roller temperature detecting means 58 for detecting the temperature is provided in a state of being in contact with or close to the surface of the pressure roller 55. Then, in the fixing device 50,
A control mechanism (not shown) for controlling the lighting state of the halogen heater lamp 52 of the heating roller 51 and the halogen heater lamp 56 of the pressure roller 55 is provided.

Each of the first supporting roller 53A and the second supporting roller 53B is formed of a metal cylindrical body extending in the width direction of the recording material to be conveyed. The metal forming the cylindrical body forming the first support roller 53A and the second support roller 53B is not particularly limited, and various metals can be used, and specific examples thereof include aluminum, iron, copper and the like. The metals or alloys thereof can be mentioned. The heating roller 51, the fixing belt 54 and the pressure roller 55 are basically the heating roller 41, the fixing belt 44 and the pressure roller 45 in the first embodiment.
It has the same configuration as.

The control mechanism uses the pressure roller temperature detecting means 58.
The pressure roller detection temperature (b) obtained by the above equation, the load nip time (c) calculated by the following equation (1), the pseudo nip time (d) calculated by the following equation (2), and the following equation (3) ) Has a function of setting the target heating roller temperature (a) based on the load nip surface pressure (e), and specifically, the target heating roller temperature (a) is calculated by the following equation (4). Is calculated.

[0044]

[Equation 6] Formula (1) Load nip time (c) = L1 / V Formula (2) Pseudo nip time (d) = L2 / V Formula (3) Load nip surface pressure (e) = P / (L1 × W) Formula (4) A x target heating roll temperature (a) + B x pressure roller detection temperature (b)             + C x load nip time (c) + D x pseudo nip time (d)             + E × Load nip surface pressure (e) + F = 0

In the above equations (1) to (3), L1
Indicates the width in the moving direction of the fixing belt 54 on the surface (that is, the load nip region N1) of the portion of the fixing belt 54 that is nipped by the heating roller 51 and the pressure roller 55, and L2 indicates the width of the fixing belt 54. The width in the moving direction of the fixing belt 54 on the surface of the portion in contact with only the pressure roller 55 (that is, the pseudo nip region N2) is shown.
Further, V indicates the moving speed of the fixing belt 54, and W indicates
The width in the direction orthogonal to the moving direction of the fixing belt 54 in the load nip area N1 of the fixing belt 54 is shown as P
Indicates a load (that is, a nip load) applied to a portion of the fixing belt 54 that is pinched by the heating roller 51 and the pressure roller 55. Further, in the above formula (4),
A, B, C, D, E and F are all constants,
These constants can be set in the same manner as in the above-described first embodiment.

In this control mechanism, the temperature state of the heating roller 51 is controlled in the same manner as in the first embodiment described above. Thus, according to the above image forming apparatus, in the fixing device 50, the target heating roller temperature (a) is set in consideration of the fixing process condition including the fixing nip time (c) and the fixing nip surface pressure (d). , An optimum temperature state according to the pressure roller detection temperature (b) actually detected, that is, target heating that should occur, for example, with the type of recording material used, the setting of the image forming operation, or the change of the operating environment. Since the temperature state in which the fluctuation of the roller temperature (a) is compensated is set, the subsequent fixing process can be executed in a state in which the fixing nip portion N is controlled to the optimum temperature state, and thus is always stable. It is possible to obtain the fixability. Further, since the target heating roller temperature (a) is set based on the pressure roller detection temperature (b), the target heating roller temperature (a) can be accurately measured even if the temperature of the pressure roller 55 is minute. The temperature can be set.

In the above control mechanism, at least the value of L1 (load nip width) in the above equations (1) and (3) and the value of L2 (pseudo nip width) in the above equation (2) are set to predetermined values. The load nip time (c) and the pseudo nip time (d) are calculated by the equations (1) to (3) based on the measured values of L1 and L2 obtained by actually measuring each fixing process. ) And the load nip surface pressure (e) are calculated, and based on the calculated new load nip time (c), pseudo nip time (d) and load nip surface pressure (e), the target heating is performed by the formula (4). The roller temperature (a) can be set. Further, the constants A to F in the formula (4) are changed according to the ambient temperature and humidity, and the target heating roller temperature (a) is set by the new formula (4) in which the constants A to F are changed. be able to. Further, instead of the target heating roller temperature calculating step of calculating the target heating roller temperature (a) by the above formula (4), a specific individual target heating roller corresponding to the detected pressure roller detection temperature (b) is obtained. The temperature (a) is calculated in advance by the above formula (4) and recorded, and the pressure roller temperature detecting means 58 is used.
It is possible to have a step of directly selecting the target heating roller temperature (a) from the pressure roller detection temperature information obtained by.

[0048]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. <Embodiment 1> According to the configuration shown in FIG. 2, a fixing device (40) was manufactured by using the following components, and the fixing device (4
0) was used to fabricate the image forming apparatus shown in FIG. Heating roller (41): an aluminum cylindrical body (outer diameter = 50 mm, equipped with a halogen heater lamp (42) in the center thereof.
Support roller (43): core metal (43A) made of iron (STKM) cylinder (outer diameter = 21 mm, wall thickness = 3 mm, total width = 340 mm) A product having a 2 mm thick silicone rubber layer (43B) formed on the surface (outer diameter = 25 m)
m), fixing belt (44): endless belt base made of nickel (width = 330 mm, total length = 70 mm, thickness = 40 μm)
m) surface with a silicone rubber layer (thickness = 150 μm)
A coating layer (thickness = 30 μm) made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is formed via a pressure roller (45): a halogen heater lamp (46) in the center. Equipped aluminum cylinder (outer diameter = 46 mm,
Core metal (45 with wall thickness = 2 mm, full width = 340 mm)
On the surface of A), a silicone rubber layer (45 mm in thickness of 2 mm
B) and a coating layer (45C) made of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) formed (outer diameter = 50 mm, Asker C hardness = 50 ° under load condition 500 g)

A styrene-acrylic polymerized toner was used as a toner for forming a toner image, and A4 size coated paper was used as a recording material. The temperature was 20 ° C. and the relative humidity was 5
In a 0% environment, the setting values of the heating roller temperature, the pressure roller temperature, the load nip time, the pseudo nip time, and the load nip surface pressure are changed to form an image, thereby forming a 40 mm × 40 mm sheet on the coated paper. A rectangular solid image (toner adhesion amount: 1.0 mg / cm ² ) was formed, and the glossiness of the solid image obtained by the VGS-1D gloss meter made by Nippon Denshoku Industries Co., Ltd. [75 ° Specular gloss G _s (75 °)]
Was measured. Next, the above fixing process condition data (heating roller temperature, pressure roller temperature, load nip time,
Pseudo nip time and load nip surface pressure) are used as explanatory variables, and multiple regression analysis is performed using the obtained glossiness data of the solid image as an objective variable, and the reference glossiness is set to 20 °. ) Constants A, B, C, D, E
And F were calculated. As a result, the constant A is 0.0247.
1, the constant B is 0.01121, the constant C is 0.2444,
The constant D was 0.02501, the constant E was 0.0202, and the constant F was -11.1.

Then, the initial set temperature of the heating roller (41) is 205 ° C. and the set temperature of the pressure roller (45) is 150.
C., load nip width (L1) is 5.8 mm, pseudo nip width (L2) is 11 mm, moving speed (V) of fixing belt (44) is 220 mm / sec, load nip area (L1 ×
W) is 19.7 cm ² , nip load (P) is 460 N,
The load nip time (c) is 27 msec, the pseudo nip time (d) is 50 msec, and the load nip surface pressure (e) is 234.
The pressure is set to kPa, a styrene-acrylic polymerized toner is used as a toner for forming a toner image, A4 size coated paper is used as a recording material, and 40 mm × in an environment of a temperature of 20 ° C. and a relative humidity of 50%. A 40 mm rectangular solid image (toner adhesion amount: 1.0 mg / cm ² ) was formed, and a total of 1,000 actual shooting tests were performed. During this live-copy test, the target heating roller temperature (a) corresponding to the pressure roller detection temperature (b) obtained by the pressure roller temperature detecting means is calculated by the above equation (4), and the target heating roller temperature is calculated. Based on (a), the heating roller (4
The lighting state of the halogen heater lamp (42) in 1) was controlled. Then, the glossiness [75 degree specular glossiness G _s (75 °)] of the obtained image is measured by the gloss meter “VGS-1D” manufactured by Nippon Denshoku Industries Co., Ltd. every 10 times of actual photographing. As a result, it was confirmed that the glossiness can be matched within the range of ± 2 ° with respect to the reference glossiness, and the desired fixing property can be stably obtained.

<Example 2> The image prepared in Example 1
Using the image forming device, the initial setting temperature of the heating roller (41)
To 200 ° C, and the set temperature of the pressure roller (45) to 150
℃, load nip time (c) set value is 30 msec, pseudo
Set the similar nip time (d) to 55 msec and load nips.
Since the set value of the contact surface pressure (e) was changed to 220 kPa,
Outside, a live-action test was conducted in the same manner as in Example 1 and obtained.
Gloss of the image [75 degree specular gloss G _s(75 °)]
When measured, within ± 2 ° of the standard gloss
If the fixing process conditions are changed,
Even if it is the case, the desired fixability can be stably obtained.
confirmed.

<Embodiment 3> According to the structure shown in FIG. 5, a fixing device (50) is manufactured by using the following components, and an image forming apparatus is manufactured by using the fixing device in the same manner as in the embodiment 1. did. Heating roller (51): Iron (STKM) cylindrical body (outer diameter = 5) equipped with a halogen heater lamp (52) in the center.
0 mm, wall thickness = 3 mm, total width = 340 mm), first support roller (53A): iron (STKM) cylinder (outer diameter = 20 mm, wall thickness = 2 mm, total width = 340 m)
m), the second supporting roller (53B): a cylindrical body made of iron (STKM) (outer diameter = 20 mm, wall thickness = 2 mm, total width = 340 m).
fixing belt (54): endless belt base material made of polyimide (width = 330 mm, total circumference length = 70 mm, thickness = 70 μm)
m) surface with a silicone rubber layer (thickness = 150 μm)
A coating layer (thickness = 30 μm) made of polytetrafluoroethylene (PTFE) is formed via a pressure roller (55): an aluminum cylinder (outer diameter = 64 m)
m, wall thickness = 3 mm, total width = 340 mm) on the surface of a core metal (55 A) having a thickness of 3 mm, a silicone rubber layer (55 B) and a coating layer made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). (55C) formed (outer diameter = 70 m
m, Asker C hardness = 40 ° under load condition 500g)

A styrene-acrylic polymerized toner is used as a toner for forming a toner image, A4 size coated paper is used as a recording material, and the temperature is 20 ° C. and the relative humidity is 5
In a 0% environment, the setting values of the heating roller temperature, the pressure roller temperature, the load nip time, the pseudo nip time, and the load nip surface pressure are changed to form an image, thereby forming a 40 mm × 40 mm sheet on the coated paper. A rectangular solid image (toner adhesion amount: 1.0 mg / cm ² ) was formed, and the glossiness of the solid image obtained by the VGS-1D gloss meter made by Nippon Denshoku Industries Co., Ltd. [75 ° Specular gloss G _s (75 °)]
Was measured. Next, the above fixing process condition data (heating roller temperature, pressure roller temperature, load nip time,
Pseudo nip time and load nip surface pressure) are used as explanatory variables, and multiple regression analysis is performed using the obtained glossiness data of the solid image as an objective variable, and the reference glossiness is set to 20 °. ) Constants A, B, C, D, E
And F were calculated. As a result, the constant A is 0.0297.
6, constant B is 0.00192, constant C is 0.3893
1, constant D is 0.02473, constant E is 0.0038
5 and the constant F were -9.747.

Then, the initial set temperature of the heating roller (51) is 210 ° C. and the set temperature of the pressure roller (55) is 150.
C., the load nip width (L1) is 9.6 mm, the pseudo nip width (L2) is 15 mm, the moving speed (V) of the fixing belt (54) is 220 mm / sec, the load nip area (L1 ×).
W) is 32.6 cm ² , nip load (P) is 657 N,
Load nip time (c) is 44 msec, pseudo nip time (d) is 63 msec, load nip surface pressure (e) is 202
The pressure is set to kPa, a styrene-acrylic polymerized toner is used as a toner for forming a toner image, A4 size coated paper is used as a recording material, and 40 mm × in an environment of a temperature of 20 ° C. and a relative humidity of 50%. A 40 mm rectangular solid image (toner adhesion amount: 1.0 mg / cm ² ) was formed, and a total of 1,000 actual shooting tests were performed. During this live-copy test, the target heating roller temperature (a) corresponding to the pressure roller detection temperature (b) obtained by the pressure roller temperature detecting means is calculated by the above equation (4), and the target heating roller temperature is calculated. Based on (a), the heating roller (5
The lighting state of the halogen heater lamp (52) of 1) was controlled. Then, the glossiness [75 degree specular glossiness G _s (75 °)] of the obtained image is measured by the gloss meter “VGS-1D” manufactured by Nippon Denshoku Industries Co., Ltd. every 10 times of actual photographing. As a result, it was confirmed that the glossiness can be matched within the range of ± 2 ° with respect to the reference glossiness, and the desired fixing property can be stably obtained.

<Example 4> The image prepared in Example 2
Using the image forming device, the initial setting temperature of the heating roller (51)
205 ℃, the temperature of the pressure roller (55) is set to 150
℃, load nip time (c) set value is 46msec, pseudo
Set the similar nip time (d) to 73 msec and load
Since the set value of the contact pressure (e) has been changed to 216 kPa,
Outside, a live-action test was conducted in the same manner as in Example 1 and obtained.
Gloss of the image [75 degree specular gloss G _s(75 °)]
When measured, within ± 2 ° of the standard gloss
If the fixing process conditions are changed,
Even if it is the case, the desired fixability can be stably obtained.
confirmed.

[0056]

According to the control method of the fixing device of the present invention,
The target heating roller temperature is set to the optimum temperature state according to the pressure roller detection temperature actually detected in consideration of the fixing process condition including the load nip time, the pseudo nip time, and the fixing nip surface pressure. The fixing process thereafter can be performed in a state where the temperature of the nip portion is controlled to the optimum temperature state. Therefore, the desired fixability can be maintained stably over a long period of time, and stable fixability can be obtained regardless of changes or fluctuations in the fixing process conditions and changes in the operating environment.

According to the fixing device of the present invention, since the method as described above is executed, the desired fixing property can be maintained stably for a long period of time, and the fixing process condition is changed or fluctuated and the operation is performed. Stable fixability can be obtained regardless of changes in the environment.

According to the image forming apparatus of the present invention, since the fixing device described above is provided, the desired fixing property can be stably maintained for a long period of time, and the fixing process condition is changed or fluctuated and the operation is performed. Stable fixability is obtained regardless of changes in the environment, and thus an image having a uniform glossiness can be reliably formed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an outline of an internal configuration of a fixing device in the image forming apparatus shown in FIG.

FIG. 3 is a flowchart showing a control system in an example of the control method of the present invention.

FIG. 4 is a flowchart showing a control system in another example of the control method of the present invention.

FIG. 5 is an explanatory diagram showing an outline of an internal configuration of a fixing device in an image forming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

10Y, 10M, 10C, 10K Toner image forming unit 11 Charging unit 12 Image carrier 13Y, 13M, 13C, 13K Developing device 14 Cleaning blade 15 Exposure means 21 Drive roller 22 Tension roller 23 Support roller 24 Intermediate transfer body 25 Intermediate transfer body Cleaning blades 31Y, 31M, 31C, 31K Primary transfer mechanism 32 Secondary transfer mechanism 32A Secondary transfer roller 32B Backup roller 40 Fixing device 41 Heating roller 42 Halogen heater lamp 43 Supporting roller 43A Core metal 43B Elastic layer 44 Fixing belt 45 Addition Pressure roller 45A Core metal 45B Elastic layer 45C Covering layer 46 Halogen heater lamp 47 Heating roller temperature detecting means 48 Pressure roller temperature detecting means 50 Fixing device 51 Heating roller 52 Halogen heater lamp 53A First supporting roller 53B Second Support Roller 54 Fixing Belt 55 Pressure Roller 55A Core Bar 55B Elastic Layer 55C Covering Layer 56 Halogen Heater Lamp 57 Heating Roller Temperature Detecting Means 58 Pressure Roller Temperature Detecting Means N Nip Part N1 Load Nip Area N2 Pseudo Nip Area

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junichi Hamada             2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock             In the company F-term (reference) 2H033 AA03 AA06 AA32 BA02 BA09                       BA11 BA30 BB01 BB28 BB33                       BB34 BE03 CA04 CA08 CA11                       CA12 CA30 CA39                 3K058 AA51 BA18 CA12 CA22 CB02                       CB09 DA02

Claims (9)

[Claims] 1. A heating roller having a heating source, at least one support roller provided in parallel with the heating roller and spaced apart from each other, and the heating roller and a fixing belt stretched around the supporting roller. And a pressure roller arranged so as to form a nip portion with the fixing belt by pressing the supporting roller or the heating roller via the fixing belt. A step (a) of detecting the temperature of the pressure roller, and at least a pressure roller detection temperature (b) obtained in the step (a), and a load calculated by the following formula (1): Based on the nip time (c), the pseudo nip time (d) calculated by the following equation (2), and the load nip surface pressure (e) calculated by the following equation (3), the target heating load A step (b) of calculating the temperature (a) and a step (c) of controlling the operating state of the heating source in the heating roller based on the target heating roller temperature (a) obtained in the step (b). A method for controlling a fixing device, comprising: Formula (1) Load nip time (c) = L1 / V Formula (2) Pseudo nip time (d) = L2 / V Formula (3) Load nip surface pressure (e) = P / (L1 × W (However, L1 is the width in the moving direction of the fixing belt on the surface of the portion of the fixing belt that is nipped by the supporting roller or the heating roller and the pressure roller, and L2 is in contact with only the pressure roller of the fixing belt. The width in the moving direction of the fixing belt on the surface of the portion, V is the moving speed of the fixing belt, and W is the fixing belt on the surface of the portion of the fixing belt which is nipped by the supporting roller or the heating roller and the pressure roller. The width P in the direction orthogonal to the moving direction of P is a load applied to a portion of the fixing belt sandwiched by the support roller or the heating roller and the pressure roller. ] 2. The method of controlling a fixing device according to claim 1, wherein in step (b), a target heating roller temperature (a) that satisfies the following equation (4) is calculated. Equation (4) A x target heating roll temperature (a) + B x pressure roller detection temperature (b) + C x load nip time (c) + D x pseudo nip time (d) + E x load nip surface pressure ( e) + F = 0 [where A, B, C, D, E and F are all constants. ] 3. The fixing device according to claim 2, wherein ambient temperature and humidity are detected, and the constant in formula (4) is changed according to the detected ambient temperature and humidity. Control method. 4. At least the value of L1 in formula (1) and formula (3) and the value of L2 in formula (2) are measured,
4. The load nip time (c), the pseudo nip time (d), and the load nip surface pressure (e) are calculated based on these measured values. Control method of fixing device of the present invention. 5. A heating roller having a heating source, at least one supporting roller provided in parallel with the heating roller and spaced apart from each other, and the heating roller and a fixing belt stretched around the supporting roller. And a pressure roller arranged to press the support roller or the heating roller via the fixing belt to form a nip portion with the fixing belt, and to detect the temperature of the pressure roller. In a fixing device comprising a pressure roller temperature detection means and a control mechanism for controlling an operating state of a heating source in the heating roller, the control mechanism includes a pressure roller detection obtained by the pressure roller temperature detection means. The temperature (b), the load nip time (c) calculated by the formula (1) described in claim 1, and the pseudo nip time (c) calculated by the formula (2) described in claim 1. ), And a target heating roller temperature (a) based on the load nip surface pressure (e) calculated by the equation (3) according to claim 1, and based on the target heating roller temperature (a). A fixing device for controlling an operating state of a heating source in a heating roller. 6. The control mechanism is the formula (4) according to claim 2.
The fixing device according to claim 5, wherein the target heating roller temperature (a) is set by the following. 7. An operating environment detecting means for detecting ambient temperature and humidity is provided, and the control mechanism changes a constant in the equation (4) according to the ambient temperature and humidity obtained by the operating environment detecting means. The fixing device according to claim 6, which has a function to perform. 8. The control mechanism comprises at least the value of L1 in equations (1) and (3) and L2 in equation (2).
Can be input from the outside, and based on the input L1 value and L2 value, the load nip time (c),
The fixing device according to any one of claims 5 to 7, which has a function of calculating the pseudo nip time (d) and the load nip surface pressure (e). 9. An image forming apparatus comprising the fixing device according to any one of claims 5 to 8.