JP2005189773A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device in which a warmup period is shortened and trouble caused by curling is restrained and to provide an image forming apparatus that has the fixing device. <P>SOLUTION: A pressure roller is separated from a fixing roller (S11). Subsequently, the heater of a heat roller is turned on (S12). Next, the fixing roller is rotated when the temperature of the heat roller reaches 100°C, and then the pressure roller is brought into pressurized contact with the fixing roller (S13). Next, when humidity is less than 70% (S14: YES), the process shifts to a ready condition when the temperature of the heat roller is 195°C and the temperature of the pressure roller reaches 100°C (S15). Meanwhile, when the humidity is 70% or more (S14: NO), the process shifts to a ready condition when the temperature of the heat roller is 190°C and the temperature of the pressure roller reaches 150°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing device that heats and fixes a toner image on a recording medium, and an image forming apparatus including the same. More specifically, the present invention relates to a fixing device that performs warm-up control in consideration of environmental conditions and an image forming apparatus including the same.

  An electrophotographic image forming apparatus includes a fixing device that fixes a toner image onto a recording sheet. For example, as shown in FIG. 8, the fixing device includes a fixing roller 112 containing heaters 1 </ b> A and 1 </ b> B, and a pressure roller 113 that faces the fixing roller 112 and pressurizes the fixing roller. is there. The fixing roller 112 is heated by the heat generated by each heater. The pressure roller 113 is warmed by receiving heat from the fixing roller 112. Conventionally, such a fixing device is capable of printing when the temperature of each roller reaches a predetermined temperature after the power is turned on (hereinafter, this state is referred to as a “ready state”). Specifically, in order to ensure the fixability, the ready state is set when the temperature of the fixing roller 112 on the printing surface side is within the range of 185 ° C. to 195 ° C.

  One of the problems of such a fixing device is that curling occurs when the temperature of the pressure roller 113 on the non-printing surface side is low. This curl is caused by a difference in moisture evaporation between the front surface and the back surface of the recording paper due to a temperature difference between the fixing roller 112 and the pressure roller 113. For this reason, in the conventional fixing device, the temperature due to the pressure roller 113 reaches 150 ° C. and then shifts to the ready state, thereby suppressing a problem due to curling.

As a fixing device that pays attention to the curling problem, for example, Patent Document 1 discloses a fixing device including an auxiliary heating roller that heats a pressure roller. In this fixing device, power supply to the auxiliary heating roller is controlled according to humidity. Thereby, the temperature difference between the fixing roller and the pressure roller can be reduced, and curling is effectively prevented.
JP 2000-181277 A

  However, the conventional fixing device described above has the following problems. That is, in order to suppress curling, the printer is ready after waiting for the pressure roller on the non-printing surface side to become hot in addition to the fixing roller on the printing surface side. As a result, the warm-up time becomes longer. Also, a large amount of heat is required to raise the temperature of each roller. In particular, the pressure roller has a larger heat capacity than other members, and raising the temperature of the pressure roller itself hinders shortening of the warm-up time.

  The present invention has been made to solve the problems of the conventional fixing device and the image forming apparatus including the fixing device. That is, the problem is to provide a fixing device that shortens the warm-up time and suppresses problems caused by curling, and an image forming apparatus including the fixing device.

  In order to solve this problem, a fixing device includes a heating member and a pressure roller facing the heating member, and fixes the image on the recording medium to the recording medium. Obtained by the heating member temperature obtaining means for obtaining the pressure, the pressure roller temperature obtaining means for obtaining the temperature of the pressure roller, and the heating member temperature obtained by the heating member temperature obtaining means and the pressure roller temperature obtaining means. And a warm-up control means for enabling printing when the temperature of the pressure roller reaches the reference temperature set for each of the heating member and the pressure roller, and the warm-up control means has a humidity higher than a predetermined value. And a normal mode in a state lower than a predetermined value, and the reference temperature of the pressure roller is different for each mode.

  That is, the fixing device described above has a heating member and a pressure roller. This heating member may be a roller or a belt. Further, the temperature of the heating member is acquired by the heating member temperature acquisition means, and the temperature of the pressure roller is acquired by the pressure roller temperature acquisition means. Further, a reference temperature for enabling printing is set for each of the heating member and the pressure roller. Furthermore, the reference temperature of the pressure roller is different for the high humidity state (high humidity mode) and the low humidity state (normal mode). That is, since the influence of curling is small in a normal environment, the reference temperature of the pressure roller is set lower than that in the high humidity mode so that printing can be performed earlier. Thereby, it is possible to shorten the warm-up time as compared with the conventional fixing device. On the other hand, since the effect of curling is large in a high humidity environment, the reference temperature of the pressure roller is increased, and the pressure roller is sufficiently warmed so that printing can be performed. Thereby, the malfunction by curl can be suppressed in a high humidity environment.

  Another fixing device according to the present invention is a fixing device that includes a heating member and a pressure roller facing the heating member, and fixes the image on the recording medium to the recording medium, and acquires the temperature of the heating member. The heating member temperature acquisition means, the pressure roller temperature acquisition means for acquiring the temperature of the pressure roller, and the heating member temperature acquired by the heating member temperature acquisition means has reached the reference temperature, And a warm-up control means for enabling printing if the temperature difference from the pressure roller temperature acquired by the pressure roller temperature acquisition means is within an allowable range. It has a high-humidity mode in a high state and a normal mode in a state lower than a predetermined value, and the allowable range is different for each mode.

  That is, in the above-described fixing device, the reference temperature of the heating member that can be printed is set. Furthermore, an allowable range of the temperature difference between the heating member and the pressure roller is set. In the warm-up operation, the permissible range is different between a high humidity state (high humidity mode) and a low humidity state (normal mode). That is, since the influence of curl is small in a normal environment, the permissible range is made wider than in the high humidity mode so that printing can be performed earlier. Thereby, it is possible to shorten the warm-up time as compared with the conventional fixing device. On the other hand, since the influence of curling is large in a high humidity environment, the allowable range is narrowed, and the temperature difference between the heating roller and the pressure roller is made as small as possible to enable printing. Thereby, the malfunction by curl can be suppressed in a high humidity environment.

  The image forming apparatus according to the present invention includes a heating member positioned on the image surface side of the recording medium and a pressure roller positioned on the non-image surface side of the recording medium when fixing the image on the recording medium to the recording medium. An image forming apparatus having a fixing device comprising: a heating member temperature acquisition unit that acquires a temperature of a heating member; a pressure roller temperature acquisition unit that acquires a temperature of a pressure roller; and a heating member Printing is enabled when the temperature of the heating member acquired by the temperature acquisition unit and the temperature of the pressure roller acquired by the pressure roller temperature acquisition unit reach the reference temperatures set for the heating member and the pressure roller, respectively. The warm-up control means has a high-humidity mode when the humidity is higher than a predetermined value and a normal mode when the humidity is lower than the predetermined value. Reference temperature pressure roller is characterized by different things.

  Another image forming apparatus according to the present invention includes a heating member located on the image surface side of the recording medium and an additional member located on the non-image surface side of the recording medium when fixing the image on the recording medium to the recording medium. An image forming apparatus having a fixing device including a pressure roller, the fixing device including a heating member temperature acquisition unit that acquires the temperature of the heating member, a pressure roller temperature acquisition unit that acquires the temperature of the pressure roller, The temperature of the heating member acquired by the heating member temperature acquisition means has reached the reference temperature, and the temperature difference between the temperature of the heating member and the pressure roller acquired by the pressure roller temperature acquisition means is within an allowable range. If there is a warm-up control means that can print if there is, the warm-up control means has a high humidity mode when the humidity is higher than a predetermined value and a normal mode when the humidity is lower than the predetermined value. , Per mode Circumference is characterized by different things.

  According to the present invention, during the warm-up operation, conditions for enabling printing in a normal environment and a high humidity environment are set different. In other words, in a normal environment, priority is given to shifting to a printable state at an early stage, and if the pressure roller is heated to an appropriate temperature to ensure fixing performance, the printable state is set. On the other hand, in a high-humidity environment, priority is given to curl suppression, and the pressure roller is sufficiently warmed to be ready for printing. As a result, a fixing device that shortens the warm-up time and suppresses problems due to curling and an image forming apparatus including the fixing device are realized.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a fixing device provided in an electrophotographic laser printer.

[First embodiment]
The image forming apparatus of this embodiment is an electrophotographic laser printer, and as shown in FIG. 1, a laser oscillator 2, a polygon mirror 3, and a reflecting mirror 4 are arranged in an optical system, and a photoconductor is provided in an image processing unit. A drum 1, a charging charger 5, a developing device 6, a transfer charger 7, and a cleaning blade 8 are arranged. In addition, a paper feed roller 9, a paper discharge roller 15, a paper feed sensor 10, a paper discharge sensor 14, a fixing device 11 and the like are arranged in the transport unit.

  Next, the operation of the laser printer configured as described above will be briefly described. The photosensitive drum 1 rotates in the direction of the arrow in FIG. 1 and the surface is uniformly charged by the charging charger 5. Further, the laser light is modulated and emitted from the laser oscillator 2 based on the image signal. This laser beam is scanned in the main scanning direction by the polygon mirror 3, is reflected by the reflecting mirror 4, and enters the photosensitive drum 1. Thereby, an electrostatic latent image is formed on the photosensitive drum 1. This electrostatic latent image is developed by the developing device 6 to become a toner image. The toner image is transferred onto the recording sheet S fed by the sheet feeding roller 9 by the transfer charger 7 disposed opposite to the photosensitive drum 1. Thereafter, the recording paper S to which the toner image has been transferred is heated in the fixing device 11, and the toner image is melted and fixed on the recording paper S by the heat. After the image is fixed, the recording paper S is discharged out of the apparatus by a paper discharge roller 15. With the above operation, printing for one sheet is performed.

  Next, the configuration of the fixing device 11 provided in the laser printer of this embodiment will be described with reference to FIG. The fixing device 11 includes a heating roller 111, a fixing roller 112, a pressure roller 113, and a fixing belt 114. Further, the thermistor 116 that acquires the temperature of the surface portion of the heating roller 111 and the thermistor 117 that acquires the temperature of the surface portion of the pressure roller 117 are provided. The thermistor 116 may acquire the temperature of the fixing belt 114. In addition, the heating roller 111 incorporates a heater 1 </ b> A that heats the center in the longitudinal direction of the heating roller 111 and a heater 1 </ b> B that heats both ends. The pressure roller 113 has a built-in pressure heater 3 </ b> A that heats the entire pressure roller 113. Further, a control unit 115 that controls the voltage applied to these heaters is provided.

  The endless fixing belt 114 is provided so as to surround the heating roller 111 and the fixing roller 112. Further, the fixing roller 112 and the pressure roller 113 are rotatably supported in a state of facing each other with the fixing belt 114 interposed therebetween. In the fixing device 11, by rotating the fixing roller 112, the pressure roller 113 is also rotated following the fixing roller 112. Further, the heating roller 111 is also rotated by following the fixing roller 112. Note that instead of the fixing roller 112, the heating roller 111 may be rotated, and the other rollers may be driven by the heating roller 111 to rotate.

  The operation of the fixing device 11 configured as described above will be described. When the recording paper on which the toner image is transferred is conveyed to the fixing device 11, it passes through a nip formed by the fixing roller 112 (fixing belt 114) and the pressure roller 113. At this time, the recording paper is passed through the nip in a state where the printing surface is on the fixing roller 112 side. Then, the toner is heated and melted by the fixing roller 112 and fixed to the recording paper S. That is, it is fixed.

  Next, the warm-up operation of the fixing device 11 will be described based on the flowchart of FIG. In the fixing device 11, temperatures required for shifting to the ready state (hereinafter referred to as “reference temperature”) are set for each of the heating roller 111 and the pressure roller 113. Further, the reference temperature is set separately for a normal environment (humidity less than 70%) and a high humidity environment (humidity 70% or more).

  First, the pressure roller 113 is separated from the fixing roller 112 (S11). Here, the separation may be in a state where the pressure roller 113 is not pressing the fixing roller 112, and includes a state where the pressure roller 113 and the fixing roller 112 are simply in contact with each other. Next, each heater of the heating roller 111 is turned on (S12). Thereby, heating of the heating roller 111 is started. At this time, the target temperature of the heating roller 111 is set to 195 ° C.

  Next, when the temperature of the heating roller 111 reaches 100 ° C., the fixing roller 112 is rotated (S13). As a result, heating of the fixing roller 112 is started. Immediately thereafter, the pressure roller 113 is brought into pressure contact with the fixing roller 112. Heating of the pressure roller 113 is also started by this pressure contact. Next, it is determined whether or not the humidity is less than 70% (S14). If the humidity is less than 70% (S14: YES), the process proceeds to S15. On the other hand, when the humidity is 70% or more (S14: NO), the process proceeds to S17.

  When the humidity is less than 70% (S14: YES), when the temperature of the heating roller 111 is 195 ° C. and the temperature of the pressure roller 113 reaches 100 ° C., a transition is made to a ready state (S15). In other words, the heating roller is set to 195 ° C. and the pressure roller 113 is set to 100 ° C. as reference temperatures for shifting to the ready state. When the humidity is less than 70% (normal environment), there is almost no curling that causes a defect such as a conveyance failure. Therefore, even when the temperature difference between the pressure roller 113 on the non-printing surface side and the heating roller 111 on the printing surface side is large and the ready state is set, there is almost no problem due to curling. Each heater is turned off when the temperature of the heating roller reaches 195 ° C., but the pressure heater starts to be turned on when the heater is turned off. At this time, the target temperature of the pressure roller 113 is set to 150 ° C.

  Next, when the temperature of the pressure roller 113 reaches 130 ° C., the target temperature of the heating roller 111 is changed to 190 ° C. (S16). Thereafter, the process proceeds to S18. If printing is performed before the temperature of the pressure roller 113 reaches 130 ° C., only one sheet can be printed, and the next printing is not performed until the temperature of the pressure roller 113 reaches 130 ° C. State (hereinafter referred to as "wait state").

  On the other hand, when the humidity is 70% or more (S14: NO), when the temperature of the heating roller 111 is 190 ° C. and the temperature of the pressure roller 113 reaches 150 ° C., it shifts to the ready state (S17). That is, as the reference temperature for shifting to the ready state, the heating roller is set to 195 ° C. and the pressure roller 113 is set to 150 ° C., respectively. Each heater is turned off when the temperature of the heating roller reaches 195 ° C., and the pressure heater is turned on when the heater is turned off. Thereafter, the process proceeds to S18.

  After the process of S16 or S17, when the temperature of the pressure roller 113 reaches 150 ° C., the pressure roller 113 is separated from the fixing roller 112 (S18). Thereby, the warm-up of each roller of the fixing device 11 is completed. Thereafter, the heater is turned on preferentially, and the state shifts to a state where the temperature of each roller is maintained at the target temperature without rotation (hereinafter referred to as “standby temperature control state”) (S19). Thereby, the warm-up operation of the fixing device 11 is completed.

  Next, temperature changes of the heating roller 111 and the pressure roller 113 when the warm-up operation is performed based on the flowchart shown in FIG. 3 will be described. FIG. 4 is a graph showing temperature changes of the heating roller 111 and the pressure roller 133 in time series. First, after the warm-up operation is started, the temperature of the heating roller 111 starts to rise by turning on each heater (S12). When the temperature reaches 100 ° C., the pressure roller 113 is pressed and the temperature of the pressure roller 113 begins to rise (S13). In a normal environment (humidity of less than 70%), when the temperature of the heating roller 111 is 195 ° C. and the temperature of the pressure roller 113 reaches 100 ° C., the ready state is established. The time until this ready state was reached was approximately 80 seconds. In the conventional warm-up operation, the temperature does not shift to the ready state until the temperature of the pressure roller 113 reaches 150 ° C. That is, the time until the ready state is reached is about 160 s. Therefore, it can be seen that the warm-up time is shortened.

  On the other hand, in a high humidity environment (humidity 70% or more), the occurrence frequency of defects due to curling is high. Therefore, it is necessary to warm the pressure roller 113 sufficiently. Therefore, when the temperature of the heating roller 111 is 190 ° C. and the temperature of the pressure roller 113 reaches 150 ° C., the ready state is entered. As a result, the warm-up time is longer than that in the normal environment, but it is possible to reliably suppress a problem due to curling.

[Second form]
Hereinafter, the configuration of the fixing device 11 provided in the laser printer of the second embodiment will be described with reference to FIG. In the fixing device 11 of this embodiment, the pressure roller 113 is not provided with a pressure heater, and is heated only by heat received from the fixing belt 114. This is different from the first embodiment in which the pressure roller 113 is heated by heat received from the fixing belt 114 and heat generated from the pressure heater. Other configurations are the same as those of the first embodiment.

  Next, the warm-up operation of the fixing device 11 will be described based on the flowchart of FIG. In the warm-up operation of this embodiment, conditions for shifting to the ready state are different from those of the first embodiment. In other words, the fixing device 11 has an allowable range of temperature difference between the heating roller 111 and the pressure roller 113. Further, the allowable range is set separately for a normal environment (humidity less than 70%) and a high humidity environment (humidity 70% or more).

  First, the pressure roller 113 is separated from the fixing roller 112 (S21). Next, each heater of the heating roller 111 is turned on (S22). At this time, the target temperature of the heating roller 111 is set to 195 ° C. Next, when the temperature of the heating roller 111 reaches 100 ° C., the fixing roller 112 is rotated (S23). Thereafter, the pressure roller 113 is brought into pressure contact with the fixing roller 112. Next, it is determined whether or not the humidity is less than 70% (S24). If the humidity is less than 70% (S24: YES), the process proceeds to S25. On the other hand, when the humidity is 70% or more (S24: NO), the process proceeds to S27. The operation so far is the same as the processing content from the processing of S11 to the processing of S14 in the first embodiment.

Next, when the humidity is less than 70% (S24: YES), when the temperature of the heating roller 111 is 195 ° C. and the following equation (1) is satisfied, the state shifts to the ready state (S25).
“Heating roller temperature” − “Pressure roller temperature” ≦ 95 ° C. (1)
That is, the allowable range of the temperature difference between the heating roller 111 and the pressure roller 113 is 95 ° C. Accordingly, when the temperature of the heating roller 111 reaches 195 ° C. and the temperature of the pressure roller 113 falls within 95 ° C. between the temperature of the heating roller 111 and the temperature thereof, the ready state is entered.

  Next, when the temperature of the pressure roller 113 reaches 130 ° C., the target temperature of the heating roller 111 is changed to 190 ° C. (S26). Thereafter, the process proceeds to S28. When printing is performed before the temperature of the pressure roller 113 reaches 130 ° C., only one sheet can be printed, and thereafter, a wait state is set.

On the other hand, when the humidity is 70% or more (S24: NO), when the temperature of the heating roller 111 is 190 ° C. and the following equation (2) is satisfied, the state shifts to the ready state (S27).
“Heating roller temperature” − “Pressure roller temperature” ≦ 40 ° C. (2)
That is, the allowable range of the temperature difference between the heating roller 111 and the pressure roller 113 is 40 ° C. As a result, in the high humidity environment, the temperature difference between the heating roller 111 and the pressure roller 113 becomes smaller than that in the normal environment, and then the ready state is entered. After satisfying these conditions, the process proceeds to S28.

  After the process of S26 or S27, the pressure roller 113 is separated from the fixing roller 112 when the expression (2) is satisfied (S28). Thereby, the warm-up of each roller of the fixing device 11 is completed. Then, it shifts to the standby temperature control state. Thereby, the warm-up operation of the fixing device 11 is completed.

  Next, temperature changes in the heating roller 111 and the pressure roller 113 when the warm-up operation is performed based on the flowchart shown in FIG. 6 will be described. FIG. 7 is a graph showing temperature changes of the heating roller 111 and the pressure roller 133 in time series. First, after the warm-up operation is started, the temperature of the heating roller 111 starts to rise by turning on each heater (S22). When the temperature reaches 100 ° C., the pressure roller 113 is pressed and the temperature of the pressure roller 113 starts to rise (S23). In a normal environment (humidity less than 70%), the ready state is reached when the temperature of the heating roller 111 reaches 195 ° C. and the temperature difference between the heating roller 111 and the pressure roller 113 is within 95 ° C. . The time until this ready state was reached was approximately 90 s. In the conventional warm-up operation, the temperature does not shift to the ready state until the temperature of the pressure roller 113 reaches 150 ° C. That is, the time until the ready state is reached is about 180 s. Therefore, it can be seen that the warm-up time is shortened.

  On the other hand, in a high humidity environment (humidity 70% or more), the occurrence frequency of defects due to curling is high. For this reason, it is necessary to minimize the temperature difference from the printing surface side by sufficiently warming the pressure roller 113 on the non-printing surface side. Accordingly, when the temperature of the heating roller 111 reaches 190 ° C. and the temperature difference between the heating roller 111 and the pressure roller 113 is within 40 ° C., the ready state is established. As a result, the warm-up time is longer than that in the normal environment, but it is possible to reliably suppress a problem due to curling.

  As described above in detail, the fixing device 11 of the first and second embodiments is ready in a normal environment (with a humidity of less than 70%) and a high humidity environment (with a humidity of 70% or more) during the warm-up operation. The condition for shifting to the state is set separately. That is, since the influence of curl is small in a normal environment, the reference temperature (100 ° C.) of the pressure roller is set lower than the target temperature (150 ° C.). Therefore, the warm-up time is shorter than that of the conventional fixing device. On the other hand, since the effect of curling is large in a high humidity environment, the pressure roller is sufficiently warmed and ready. In other words, it is ready until the temperature of the pressure roller reaches the target temperature (150 ° C.). As a result, a fixing device that reduces the warm-up time in a normal environment and suppresses problems due to curling in a high-humidity environment and an image forming apparatus including the fixing device are realized.

  Note that this embodiment is merely an example and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the embodiment, the present invention is applied to a laser printer, but the present invention is not limited to this. That is, even a copying machine, scanner, FAX, word processor, or the like can be applied as long as it has a fixing device. Moreover, it is not limited to color but may be dedicated to monochrome images. Moreover, not only a tandem system but a 4-cycle system, for example, may be used.

  In the embodiment, the fixing belt 114 is heated by the heating roller 111 and the pressure roller 113 is further heated by the fixing belt 114. However, the present invention is not limited to this. For example, the fixing roller 112 may be heated as in the fixing device illustrated in FIG. 8, and the pressure roller 113 may be further heated by the fixing roller 112. In this case, it is determined whether or not to shift to the ready state based on the temperature of the fixing roller 112.

  Further, in the embodiment, it is determined whether or not to shift to the ready state depending on the temperature of the heating roller 111, but is not limited thereto. For example, the determination may be made based on the temperature of the fixing belt 114.

1 is a cross-sectional view showing a schematic configuration of a copying machine according to a first embodiment. 1 is a cross-sectional view illustrating a schematic configuration of a fixing device according to a first embodiment. 3 is a flowchart illustrating warm-up control of the fixing device according to the first embodiment. It is a graph which shows the temperature change of the heating roller concerning the warm-up of a 1st form, and a pressure roller. It is sectional drawing which shows schematic structure of the fixing device concerning a 2nd form. 6 is a flowchart showing warm-up control of a fixing device according to a second embodiment. It is a graph which shows the temperature change of the heating roller concerning the warm-up of a 2nd form, and a pressure roller. It is sectional drawing which shows schematic structure of the fixing device concerning the conventional form.

Explanation of symbols

11 Fixing device 111 Heating roller (heating member)
112 Fixing roller 113 Pressure roller (Pressure roller)
114 Fixing belt 115 Control unit (warm-up control means)
116 thermistor (heating member temperature acquisition means)
117 thermistor (pressure roller temperature acquisition means)

Claims (8)

In a fixing device comprising a heating member and a pressure roller facing the heating member, and fixing the image on the recording medium to the recording medium,
Heating member temperature acquisition means for acquiring the temperature of the heating member;
Pressure roller temperature acquisition means for acquiring the temperature of the pressure roller;
The temperature of the heating member acquired by the heating member temperature acquisition means and the temperature of the pressure roller acquired by the pressure roller temperature acquisition means are both set to the reference temperature set for each of the heating member and the pressure roller. A warm-up control means that enables printing when it reaches,
The warm-up control means has a high humidity mode when the humidity is higher than a predetermined value and a normal mode when the humidity is lower than the predetermined value, and the reference temperature of the pressure roller is different for each mode. A fixing device characterized by the above. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the reference temperature of the pressure roller set by the warm-up control means is higher in the high humidity mode than in the normal mode. In a fixing device comprising a heating member and a pressure roller facing the heating member, and fixing the image on the recording medium to the recording medium,
Heating member temperature acquisition means for acquiring the temperature of the heating member;
Pressure roller temperature acquisition means for acquiring the temperature of the pressure roller;
The temperature of the heating member acquired by the heating member temperature acquisition means has reached a reference temperature, and the temperature difference between the temperature of the heating member and the temperature of the pressure roller acquired by the pressure roller temperature acquisition means is within an allowable range. Warm-up control means that can print if within,
The warm-up control means has a high humidity mode when the humidity is higher than a predetermined value and a normal mode when the humidity is lower than the predetermined value, and the fixing range is different for each mode. apparatus. The fixing device according to claim 3,
The fixing device is characterized in that the allowable range set by the warm-up control means is narrower in the high humidity mode than in the normal mode. When fixing an image on a recording medium to the recording medium, an image forming apparatus having a fixing device including a heating member positioned on the image surface side of the recording medium and a pressure roller positioned on the non-image surface side of the recording medium In
The fixing device includes:
Heating member temperature acquisition means for acquiring the temperature of the heating member;
Pressure roller temperature acquisition means for acquiring the temperature of the pressure roller;
The temperature of the heating member acquired by the heating member temperature acquisition means and the temperature of the pressure roller acquired by the pressure roller temperature acquisition means are both set to the reference temperature set for each of the heating member and the pressure roller. A warm-up control means that enables printing when it reaches,
The warm-up control means has a high humidity mode when the humidity is higher than a predetermined value and a normal mode when the humidity is lower than the predetermined value, and the reference temperature of the pressure roller is different for each mode. An image forming apparatus. The image forming apparatus according to claim 5,
The image forming apparatus according to claim 1, wherein the reference temperature of the pressure roller set by the warm-up control means is higher in the high humidity mode than in the normal mode. When fixing an image on a recording medium to the recording medium, an image forming apparatus having a fixing device including a heating member positioned on the image surface side of the recording medium and a pressure roller positioned on the non-image surface side of the recording medium In
The fixing device includes:
Heating member temperature acquisition means for acquiring the temperature of the heating member;
Pressure roller temperature acquisition means for acquiring the temperature of the pressure roller;
The temperature of the heating member acquired by the heating member temperature acquisition means has reached a reference temperature, and the temperature difference between the temperature of the heating member and the temperature of the pressure roller acquired by the pressure roller temperature acquisition means is within an allowable range. Warm-up control means that can print if within,
The warm-up control means has a high humidity mode in a state where the humidity is higher than a predetermined value and a normal mode in a state where the humidity is lower than the predetermined value, and the allowable range is different for each mode. Forming equipment. The image forming apparatus according to claim 7,
The allowable range set by the warm-up control means is that the high humidity mode is narrower than the normal mode.

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