JP2007052142A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device whose component cost and assembly cost are comparatively low and where a separating function by a separation auxiliary member is efficiently secured even when various components are thermally deformed, and an image forming apparatus. <P>SOLUTION: The fixing device is equipped with: a fixing member 21 melting a toner image T; a pressure member 24 forming a nip part by press-contacting with the fixing member 21; the separation auxiliary member 38 opposed to the fixing member 21 while leaving space in between in order to separate a recording medium P fed from the nip part and attracted to the fixing member 21 from the fixing member 21; and a varying means 39 varying and deciding the gap between the separation auxiliary member 38 and the fixing member 21 in accordance with the temperature variation of the fixing member 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and a fixing device installed therein.

  2. Description of the Related Art Conventionally, in a fixing device installed in an image forming apparatus such as a copying machine, in order to prevent the recording medium sent from the nip portion from being attracted and wound around the fixing member, A technique for installing a separation assisting member so as to face each other with a gap is known (for example, see Patent Document 1).

In Patent Document 1, etc., the fixing device includes a fixing roller as a fixing member, a pressure roller as a pressure member that presses against the fixing roller to form a nip portion, and a separation auxiliary member that faces the fixing roller on the outlet side As a separation plate (separation plate).
Then, a toner image (image) is transferred onto the surface of the recording medium that moves along the conveyance path of the image forming apparatus at the image forming unit. Thereafter, the recording medium carrying the unfixed image further moves along the conveyance path and reaches the fixing device. The recording medium that has reached the fixing device is fed between the fixing roller and the pressure roller (a nip portion), and the toner image is fixed by the heat received from the fixing roller and the pressure received from both rollers. The The recording medium on which the toner image is fixed is delivered from the nip portion and then discharged to the outside of the image forming apparatus.

In such a fixing device, even when the recording medium is attracted to the fixing roller when being sent out from the nip portion, the separation plate mechanically separates the recording medium from the fixing roller and fixes it. Guide to the transport path after the process. The separation plate is for suppressing a problem that the recording medium after the fixing process is wound around the fixing roller.
Since such a separation plate is disposed with a minute gap with respect to the fixing roller, a separation claw that directly contacts the fixing roller and promotes separation of the recording medium (for example, Patent Document 2). It is known that the problem of damaging the surface of the fixing roller is suppressed.

  On the other hand, Patent Document 2 discloses a technique for forming a separation claw that contacts the fixing roller with a shape memory alloy. Specifically, the separation claw is formed of a shape memory alloy so that the separation claw contacts the fixing roller only when the fixing roller is at a predetermined temperature or higher. This technique is intended to reduce damage to the surface of the fixing roller by reducing the frequency with which the separation claw contacts the fixing roller.

JP 2003-202767 A Japanese Unexamined Patent Publication No. Sho 63-314582

  In the conventional fixing device described above, in order to ensure the separation function by the separation plate, it is necessary to dispose the separation plate with high accuracy with a small gap from the fixing roller. Therefore, it is necessary to increase the component accuracy and assembly accuracy of various components related to the gap of the separation plate, and the device has a high component cost and assembly cost.

  Further, since the fixing device is used at a high temperature, various parts related to the gap between the separation plates are thermally deformed, and it is difficult to secure a fine gap with high accuracy between the fixing roller and the separation plate.

  Such a problem is not limited to a heat roller type fixing device, but is common to other types of fixing devices such as an electromagnetic induction heating method. Such a problem is not limited to a fixing device using a fixing roller as a fixing member, but is common to a fixing device using a fixing belt as a fixing member.

  On the other hand, the technique of Patent Document 2 and the like is intended to reduce the frequency with which the separation claw comes into contact with the fixing roller by forming the separation claw with a shape memory alloy. It does not solve the problem.

  The present invention has been made to solve the above-described problems. The parts cost and the assembling cost are relatively low, and the separation function by the separation assisting member is provided even when various parts are thermally deformed. An object of the present invention is to provide a fixing device and an image forming apparatus that can be efficiently secured.

  According to a first aspect of the present invention, there is provided a fixing device for fixing a toner image onto a recording medium, wherein a fixing member for melting the toner image is pressed against the fixing member to form a nip portion. A pressure member, a separation auxiliary member facing the fixing member with a gap in order to separate the recording medium fed from the nip portion and adsorbed to the fixing member from the fixing member, the separation auxiliary member, and the Variable means for variably determining the gap with the fixing member according to the temperature fluctuation of the fixing member.

  The fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the variable means is a spacer disposed at both ends in the width direction of the separation assisting member and abutting against the fixing member. The spacer is made of a shape memory fiber.

  According to a third aspect of the present invention, in the fixing device according to the second aspect, the separation assisting member and the fixing member are arranged even when the spacer does not receive heat from the fixing member. This gap is configured to be larger than zero.

  The fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, wherein the variable means sets the temperature of the fixing member in accordance with the type of the recording medium. The gap between the separation assisting member and the fixing member is varied.

  The fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the variable means is configured to fix the fixing when the weighing of the recording medium is a predetermined value or less. The temperature of the member is lowered to narrow the gap between the separation assisting member and the fixing member.

  The fixing device according to a sixth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the variable means is configured such that the thickness of the recording medium is not more than a predetermined value. The temperature of the fixing member is lowered to narrow the gap between the separation assisting member and the fixing member.

  The fixing device according to a seventh aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the variable means is configured such that the waist strength of the recording medium is not more than a predetermined value. In addition, the temperature of the fixing member is lowered to narrow the gap between the separation assisting member and the fixing member.

  The fixing device according to an eighth aspect of the present invention is the fixing device according to any one of the first to seventh aspects, wherein the variable means is in accordance with the form of the toner image fixed on the recording medium. The gap between the separation assisting member and the fixing member is varied by changing the temperature of the fixing member.

  The fixing device according to a ninth aspect of the present invention is the fixing device according to any one of the first to eighth aspects, wherein the variable means has a toner adhesion amount of a toner image fixed on the recording medium. When the temperature exceeds a predetermined value, the temperature of the fixing member is decreased to narrow the gap between the separation assisting member and the fixing member.

  An image forming apparatus according to a tenth aspect of the present invention includes the fixing device according to any one of the first to ninth aspects.

  In the present invention, since the gap between the separation assisting member and the fixing member is variably determined according to the temperature fluctuation of the fixing member, the parts cost and the assembly cost are relatively low, and various parts are heated. It is possible to provide a fixing device and an image forming apparatus in which the separation function by the separation assisting member is efficiently ensured even when deformation occurs.

Embodiment.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a copying machine as an image forming apparatus, 2 an original reading unit that optically reads image information of an original D, and 3 an exposure light L based on image information read by the original reading unit 2. Is exposed to the photosensitive drum 5, 4 is an image forming unit for forming a toner image (image) on the photosensitive drum 5, and 7 is a toner image formed on the photosensitive drum 5 on the recording medium P. A transfer unit 10 for transferring, a document transport unit for transporting the set document D to the document reading unit 2, 12 to 14 a paper feed unit storing a recording medium P such as transfer paper, and 20 on the recording medium P A fixing device for fixing an unfixed image, 21 is a fixing roller as a fixing member installed in the fixing device 20, and 24 is a pressure roller as a pressing member installed in the fixing device 20.

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus will be described.
First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the conveyance roller of the document conveyance unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). Then, exposure light L such as laser light based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in the drawing, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed.
Thereafter, the image formed on the photosensitive drum 5 is transferred by the transfer unit 7 onto the recording medium P conveyed by the registration roller.

On the other hand, the recording medium P conveyed to the transfer unit 7 operates as follows.
First, one of the plurality of paper feeding units 12, 13, and 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the uppermost paper feeding unit 12 is selected). To do.)
Then, the uppermost sheet of the recording medium P stored in the paper feeding unit 12 is transported toward the position of the transport path K.

  Thereafter, the recording medium P passes through the conveyance path K and reaches the position of the registration roller. Then, the recording medium P that has reached the position of the registration roller is conveyed toward the transfer unit 7 at the same timing in order to align with the image formed on the photosensitive drum 5.

After the transfer process, the recording medium P passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The recording medium P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 24, and the image is fixed by the heat received from the fixing roller 21 and the pressure received from both rollers 21, 24. The The recording medium P on which the image is fixed is delivered from between the fixing roller 21 and the pressure roller 24 and then discharged from the image forming apparatus main body 1.
Thus, a series of image forming processes is completed.

Next, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail with reference to FIGS.
As shown in FIG. 2, the fixing device 20 mainly includes a fixing roller 21, a pressure roller 24, a separation plate 38 (separation assisting member), a thermistor 37, and the like.

  Here, the fixing roller 21 as a fixing member includes a thin cylindrical body (an outer diameter is 35 mm) that rotates in the direction of an arrow in FIG. 2 and a heater 22 fixed inside the cylindrical body. Composed. The surface of the cylindrical body of the fixing roller 21 is processed with a fluororesin so as to ensure releasability (peelability) from the toner T (toner image). The heater 22 of the fixing roller 21 is a rod-shaped heater having a heating wire inside, and both ends thereof are fixed to the side plate of the fixing device 20. Then, the cylindrical body is heated by the heater 22 whose output is controlled by the power supply unit 40 of the apparatus main body 1, and heat is applied to the toner image T on the recording medium P from the surface of the cylindrical body. The output control of the heater 22 is performed based on the detection result of the roller surface temperature by the thermistor 37 that contacts the surface of the fixing roller 21. Further, the temperature of the fixing roller 21 (fixing set temperature) can be set to a desired temperature by such output control of the heater 22.

  The pressure roller 24 as a pressure member mainly includes a cored bar and a plurality of elastic layers formed on the outer peripheral surface of the cored bar via an adhesive layer. The elastic body layer of the pressure roller 24 has a layer thickness of 1 to 10 mm, and a material such as fluorine rubber, silicone rubber, or foamable silicone rubber is used. A thin release layer having a layer thickness of 300 μm or less (preferably 40 μm or less) is provided on the surface layer of the elastic layer. As the material of the release layer, a single layer film of heat-resistant resin such as polyimide, polyetherimide, PES (polyether sulfide), PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), or a film having a thickness of 20 μm The composite layer film etc. which gave the release coat layer which added the electrically conductive material to fluororesins, such as PTFE (tetrafluoroethylene resin) and PFA, in the surface layer side of 10-30 micrometers can be used. The pressure roller 24 configured in this manner is excellent in elasticity, heat resistance, releasability, and durability.

The pressure roller 24 is in pressure contact with the fixing roller 21 by a pressure mechanism (not shown). In this way, a desired nip portion is formed between the pressure roller 24 and the fixing roller 21.
Further, guide plates 35 for guiding the conveyance of the recording medium P are disposed on the entrance side and the exit side of the contact portion (a nip portion) between the fixing roller 21 and the pressure roller 24, respectively. . The guide plate 35 is fixed to the side plate of the fixing device 20.

As shown in FIG. 2, a separation plate 38 as a separation assisting member is disposed at a position facing the outer peripheral surface of the fixing roller 21 and in the vicinity of the exit side of the nip portion. The separation plate 38 is made of a stainless material having a thickness of 0.3 mm, and extends in accordance with the length of the fixing roller 21 in the width direction (the direction perpendicular to the paper surface of FIG. 2).
Spacers 39 are respectively installed at both ends in the width direction (outside the sheet passing area of the recording medium P) at the leading end of the separation plate 38. The spacer 39 is made of a shape memory fiber and is disposed so as to contact the fixing roller 21.

The separation plate 38 is urged toward the fixing roller 21 via a spacer 39 by an urging member (not shown). Thus, a gap (a minute gap) corresponding to the thickness of the spacer 39 is formed between the separation plate 38 and the fixing roller 21 (see the gaps G1 and G2 in FIG. 3).
With such a configuration, even when the recording medium P is attracted to the fixing roller 21 when being sent out from the nip portion, the separation plate 38 mechanically separates the recording medium P from the fixing roller. This leads to the conveyance path after the fixing process. In other words, the separating plate 38 prevents the recording medium P after the fixing process from being wound around the fixing roller 21 along the rotation of the fixing roller 21 without damaging the surface of the fixing roller 21.

Here, the shape memory fiber used as the material of the spacer 39 is a material that expands and increases its hardness when its temperature rises. Further, in the present embodiment, the spacer 39 is set so that a desired thickness (degree of expansion) is ensured at a minimum at a target temperature (for example, 165 ° C.).
Since the spacer 39 is in contact with the fixing roller 21 and directly receives heat from the fixing roller 21, the gap between the separation plate 38 and the fixing roller 21 is set according to the temperature fluctuation (fixing set temperature) of the fixing roller 21. It functions as a variable means that is variably determined.

As a result, it is possible to reliably form the gap between the separation plates 38 with high accuracy and to change the gap between the separation plates 38 according to the fixing set temperature of the fixing roller 21. In the present embodiment, the temperature of the fixing roller 21 (fixing set temperature) is varied according to the type of the recording medium P, and the gap between the separation plate 38 and the fixing roller 21 is varied.
Specifically, when the recording medium P is thin paper, the fixing set temperature of the fixing roller 21 is lower than the normal temperature (the target temperature described above, for example, 165 ° C.). To lower. As a result, as shown in FIG. 3A, the spacer 39 is changed to a desired thickness, and a desired minute gap G1 in the separation plate 38 is formed. That is, the gap of the separation plate 38 changes from the state shown in FIG. 3B (gap G2) to the state shown in FIG. 3A (gap G1) as the thickness of the spacer 39 changes due to the temperature fluctuation of the fixing roller 21. (G2> G1).

This is intended to ensure that the separation plate 38 functions only when there is a possibility of the recording medium P being wound around the fixing roller 21 and is based on the experimental results shown in FIG. is there.
FIG. 4 shows a fixing device 20 (image forming apparatus) according to the present embodiment. The recording medium P is weighed (paper weighed) at 55 g / m ² (thin paper) and 105 g / m ² (thick ordinary). When the fixing set temperature of the fixing roller 21 and the gap between the separation plates 38 are integrally changed, the winding of the recording medium P around the fixing roller 21 and the offset on the output image are changed. The presence or absence is confirmed. In FIG. 4, “◯” indicates a good state where no wrapping around the fixing roller 21 and no offset (hot offset and cold offset) occur. The upper limit of the toner adhesion amount of the toner image formed on the recording medium P was 11 g / m ² .

  As shown in FIG. 4, winding around the fixing roller 21 is likely to occur when thin paper is used as the recording medium P. Even in this case, the gap between the separation plates 38 is 0.45 mm (fixing set temperature is 175 ° C.). ) Winding can be prevented by setting the following. However, when the set fixing temperature is 155 ° C. or less (the gap between the separation plates 38 is 0.25 mm), a cold offset occurs. From these results, when thin paper is used, cold offset does not occur and winding around the fixing roller 21 is surely suppressed, so that the gap of the separation plate 38 is about 0.65 mm and the fixing set temperature is 165. It turns out that it is preferable to set it as about degreeC.

On the other hand, when the recording medium P having a weight of 105 g / m ² is used, even if the gap between the separation plates 38 is increased, the winding around the fixing roller 21 does not occur, but the fixing setting temperature is 165 ° C. or lower. Then, a cold offset occurs. From these results, when plain paper is used, in order to reliably suppress cold offset, it is set to a temperature (for example, 180 ° C.) higher than the fixing set temperature when using thin paper. Is preferable.

  Based on the above results, in the present embodiment, when the recording medium P is thin paper, the fixing set temperature of the fixing roller 21 is lowered to a temperature lower than the normal temperature. That is, the minute gap of the separation plate 38 is set with high accuracy only when there is a possibility of being caught in the fixing roller 21. Thereby, the margin of the separation function by the separation plate 38 can be efficiently improved by the spacer 39 functioning as the variable means, regardless of the component accuracy and assembly accuracy of various components.

The fixing set temperature of the fixing roller 21 is lowered to a temperature lower than the normal temperature when it is determined that the weight, thickness, and waist strength of the recording medium P are below a predetermined value. Can do.
Further, the spacer 39 as the variable means is set so that the gap between the separation plate 38 and the fixing roller 21 is larger than zero even when there is no heat reception from the fixing roller 21. Thereby, even when power is not supplied to the fixing device 20, it is possible to prevent a problem that the separation plate 38 contacts the fixing roller 21 and damages the surface thereof.

The fixing device 20 configured as described above operates as follows.
First, when the power switch (not shown) of the apparatus main body 1 is not turned on, there is no heat reception from the fixing roller 21 to the spacer 39, and the spacer 39 has a minimum thickness. The gap between the separation plates 38 is further smaller than the gap G1 in FIG.

When the power switch of the apparatus main body 1 is turned on, power is supplied to the heater 22 and rotation driving of the fixing roller 21 and the pressure roller 24 in the direction of the arrow in FIG. At this time, heat reception from the fixing roller 21 to the spacer 39 is started, the thickness and hardness of the spacer 39 are increased, and the gap of the separation plate 38 is set to a desired size.
Thereafter, the recording medium P is fed from the paper feeding units 12 to 14, and an unfixed image is carried on the recording medium P by the image forming unit 4. The recording medium P carrying the unfixed image T is conveyed in the direction of the arrow Y10 in FIG. 2 and fed into the nip portion between the fixing roller 21 and the pressure roller 24 that are in a pressure contact state. Then, the toner image T is fixed on the surface of the recording medium P by the heating by the fixing roller 21 and the pressing force of the fixing roller 21 and the pressure roller 24. Thereafter, the recording medium P sent out from the nip portion by the rotating fixing roller 21 and the pressure roller 24 is conveyed in the direction of the arrow Y11.

  Specifically, when it is determined that the recording medium P is a thin paper based on user input information or the like, the fixing set temperature of the fixing roller 21 is set to 165 ° C., and the separation plate 38 corresponding thereto. Is set to G1 (the state shown in FIG. 3A). At this time, the recording medium P delivered from the nip portion interferes with the minute gap G1 of the separation plate 38 even if the recording medium P is attracted to the fixing roller 21, as indicated by a broken line arrow Y11 in FIG. Thus, it is mechanically separated from the fixing roller 21.

  On the other hand, when it is determined that the recording medium P is not thin paper based on user input information or the like, the fixing set temperature of the fixing roller 21 is set to 180 ° C. The gap is set to G2 (the state shown in FIG. 3B). At this time, the recording medium P sent out from the nip portion is not attracted to the fixing roller 21 (without interfering with the separation plate 38) as shown by a broken line arrow Y11 in FIG. Will be sent out.

  As described above, in the present embodiment, since the gap between the separation plate 38 and the fixing roller 21 is variably determined according to the temperature fluctuation of the fixing roller 21, the component cost and the assembly cost are determined. However, the separation function by the separation plate 38 can be efficiently ensured even if various parts are thermally deformed.

  In the present embodiment, the fixing set temperature is varied according to the type of the recording medium P (in the case of thin paper) to form the minute gap of the separation plate 38, but the toner fixed on the recording medium P It is also possible to form a minute gap in the separation plate 38 by changing the fixing set temperature according to the image form. Specifically, when the toner adhesion amount of the toner image fixed on the recording medium P is equal to or larger than a predetermined value (when the toner adhesion amount is large and winding around the fixing roller 21 is likely to occur), the fixing set temperature. The separation function of the separation plate 38 can be efficiently ensured by reducing the height of the separation plate 38 and forming a minute gap in the separation plate 38. The same control can also be performed when the toner image is relatively concentrated on the leading edge of the recording medium P (when the leading edge of the recording medium P is likely to wrap around the fixing roller 21). . In these cases, the same effect as in the present embodiment can be obtained.

In the present embodiment, the present invention is applied to a heat roller type fixing device, but the present invention can naturally be applied to another type of fixing device such as an electromagnetic induction heating method. In this case, the same effect as that of the present embodiment can be obtained.
Furthermore, in the present embodiment, the present invention is applied to a fixing device using a fixing roller as a fixing member, but the present invention is naturally applied to a fixing device using a fixing belt as a fixing member. Can do. In this case, the same effect as that of the present embodiment can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a fixing device installed in the image forming apparatus of FIG. 1. FIG. 3 is a schematic diagram illustrating a state of a separation plate in the fixing device of FIG. 2. It is a table | surface figure which shows an experimental result.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20 fixing device,
21 fixing roller (fixing member),
22 heaters,
24 pressure roller (pressure member),
38 Separation plate (separation assisting member),
39 Spacer (variable means),
40 Power supply, P recording medium, G1, G2 gap.

Claims (10)

A fixing device for fixing a toner image on a recording medium,
A fixing member for melting the toner image;
A pressure member that presses against the fixing member to form a nip portion;
A separation assisting member facing the fixing member with a gap in order to separate the recording medium sent from the nip portion and adsorbed to the fixing member from the fixing member;
Variable means for variably determining a gap between the separation assisting member and the fixing member according to a temperature variation of the fixing member;
A fixing device comprising: The variable means is a spacer disposed at both ends in the width direction of the separation assisting member and abutting on the fixing member,
The fixing device according to claim 1, wherein the spacer is made of a shape memory fiber. The fixing device according to claim 2, wherein the spacer is configured such that a gap between the separation assisting member and the fixing member is larger than zero even when heat is not received from the fixing member. apparatus. 4. The variable unit according to claim 1, wherein the variable unit varies the temperature of the fixing member according to the type of the recording medium to vary the gap between the separation assisting member and the fixing member. A fixing device according to claim 1. The variable means reduces the temperature of the fixing member to narrow the gap between the separation assisting member and the fixing member when the weighing of the recording medium is a predetermined value or less. Item 5. The fixing device according to Item 4. The variable means reduces the temperature of the fixing member to narrow a gap between the separation assisting member and the fixing member when the thickness of the recording medium is a predetermined value or less. The fixing device according to claim 4. The variable means reduces the temperature of the fixing member to narrow a gap between the separation assisting member and the fixing member when the stiffness of the recording medium is a predetermined value or less. The fixing device according to claim 1. The variable means varies the gap between the separation assisting member and the fixing member by varying the temperature of the fixing member in accordance with the form of the toner image fixed on the recording medium. The fixing device according to claim 7. The variable means reduces the temperature of the fixing member to narrow the gap between the separation assisting member and the fixing member when the toner adhesion amount of the toner image fixed on the recording medium is a predetermined value or more. The fixing device according to claim 1, wherein the fixing device is characterized in that: An image forming apparatus comprising the fixing device according to claim 1.

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