JP4320234B2 - Fixing apparatus and image forming apparatus having the fixing apparatus - Google Patents

Description

  The present invention relates to a substantially cylindrical fixing belt having flexibility, a heating means for directly heating the fixing belt with a radiant heat source, and a fixing member disposed in the fixing belt via the fixing belt. In particular, the present invention relates to a pressure member that forms a toner image, a fixing device that performs fixing by passing a recording medium carrying an unfixed toner image in the nip, and an image forming apparatus having the fixing device.

  2. Description of the Related Art Conventionally, it is well known to use a fixing device of the above type in an image forming apparatus configured as an electronic copying machine, a printer, a facsimile, or a multifunction machine having at least two of these functions. This type of fixing device has a fixing member composed of a fixing roller heated by a heat source and driven to rotate, and a pressure member composed of a pressure roller that rotates in pressure contact with the fixing roller. A heat roller type is generally used in which a recording medium is passed through a nip to be formed and toner is heat-pressed. At this time, a halogen heater using a halogen lamp has generally been used as a heat source for the fixing roller.

  In recent years, due to increasing environmental regulations and environmental protection awareness, in various image forming apparatuses, when not in use, the energization to the fixing heater is cut off and energized only when necessary to reduce power consumption. In such an energy-saving image forming apparatus, the surface temperature of the fixing roller needs to reach the set temperature immediately during printing. In the conventional heating method using a halogen heater, the heat capacity of the fixing roller is reduced by reducing the thickness of the fixing roller base to 1 mm or less, and the fixing roller can be quickly raised to a set temperature. ing.

  However, when the fixing roller is formed of a rigid body, the contact surface at the time of fixing does not follow the unevenness on the recording medium, so that close contact cannot be made and there is a problem of image quality deterioration such as minute gloss unevenness. Even if the image deterioration does not cause a problem in a monochrome machine, it appears particularly conspicuous in a color machine. Therefore, in order to improve the image quality of a color machine, it is essential to give elasticity to the fixing surface. Therefore, in a color machine, both a fixing roller and a pressure roller have an elastic layer (mainly silicone rubber), and a fixing device that heats from the inside by a halogen heater installed in the roller is the mainstream.

  However, with such a roller fixing method, the heat capacity becomes enormous, and the heat transfer from the inside of the roller to the surface layer is poor, so the start-up is significantly slow and preheating must always be performed during standby, saving energy. Do not become a type of image forming apparatus.

Therefore, in recent years, a fixing method that is not a roller method using an elastic layer has been studied also in a color machine.
JP 2001-142350 A Japanese Patent Laid-Open No. 2002-148983

  For example, according to Patent Document 1, unfixed toner on a sheet that is endlessly stretched between a heating roller and a fixing roller, receives heat transfer from a heat generating unit, and passes through a rolling contact portion of the fixing roller and the pressure roller. A fixing belt that heats the fixing belt, a temperature measuring means that measures the temperature of the fixing belt, and a control device that controls the heat generation state of the heat generating means based on the measurement result of the temperature measuring means. In the fixing device for fixing the unfixed toner on the sheet by passing the carried sheet along the rolling contact portion in one direction, the temperature measuring means includes a non-contact sensor, and the non-contact sensor There has been proposed a fixing device that is disposed to face a flat portion and measures the temperature of the substantially flat portion.

  However, in the fixing device disclosed in Patent Document 1, the belt temperature measuring means and the heating roller incorporating the heater are arranged at different positions. In such a configuration, when the belt slip occurs, the belt temperature becomes non-uniform, or when a rotation abnormality such as non-rotation occurs, a belt burnout accident occurs.

  According to Patent Document 2, the rise time is fast, but there is a problem that it is difficult to control the film temperature stably because the film temperature is not directly detected.

  The present invention solves the above-described conventional problems, and provides a fixing device and an image forming apparatus having the fixing device that can simultaneously achieve, for example, high-speed startup for 10 seconds or less and prevention of occurrence of burning and burning. It is aimed.

To solve the above problems, the present invention includes a substantially cylindrical fixing belt having flexibility, a fixing member disposed fixing the belt, the press nip through the fixing belt and the fixing member a pressure member for forming, and a heating means for heating directly from within the radiant heat source the fixing belt, the fixing device that performs fixing by passing the recording medium bearing the unfixed toner image to said nip, said A reflection member provided between a radiant heat source and the fixing member; and a heat insulating member provided between a side edge of the reflection member and an inner peripheral surface of the fixing belt facing the side edge; Proposed is a fixing device in which the heat insulating member also serves as a guide for guiding rotation of the fixing belt by sliding contact with an inner peripheral surface of the fixing belt.

In the fixing device according to the aspect of the invention , it is preferable that the heat insulating member is provided in a non-sheet passing region in a side edge of the reflecting member facing the inner peripheral surface of the fixing belt .
Further, in the fixing device of the present invention, the side edge of the reflecting member is formed by bending the reflecting member, and the heat insulating member is provided between the side edge and the inner peripheral surface of the fixing belt . Is preferred.

Furthermore, in the fixing device of the present invention, a temperature detecting member for detecting the temperature of the fixing belt is provided, the temperature detecting member is a region where the fixing belt is directly heated by the radiant heat source, and the fixing belt is provided. It is preferable that the fixing belt is disposed in a non-contact manner at a position facing the radiant heat source .

Furthermore, in the fixing device of the present invention, when the reflection member is provided between the temperature detection member and the radiant heat source, the temperature detection member and the radiant heat source face each other via the fixing belt. Thus, it is preferable to provide a notch at the corresponding part of the reflecting member .

Furthermore, in the fixing device of the present invention, it is preferable that the fixing belt is substantially sealed by being guided by a belt guide member at both ends of the substantially cylindrical axial direction .

  Furthermore, in the fixing device of the present invention, it is preferable that the fixing belt is composed of two or more layers including a base material layer, and at least one layer of the fixing belt is subjected to a light leakage prevention process.

Furthermore, in the fixing device of the present invention, it is preferable that the light leakage prevention process is performed so that at least one layer of the fixing belt is processed to be substantially black.
Furthermore, in the fixing device of the present invention, it is preferable that the fixing member is an elastic pressing member.

Furthermore, in the fixing device of the present invention, it is preferable that the fixing member is a rotatable elastic roller.
Furthermore, in the fixing device of the present invention, it is preferable that the pressure member is a roller having a heat insulating structure having a large rigidity, and the fixing belt is driven to rotate by driving the roller.

  Furthermore, in the fixing device of the present invention, the fixing device has temperature control means for controlling the fixing belt so as to maintain a predetermined temperature, and at least a first set temperature in a fixable region and a set temperature at which fixing is possible. One or both of the second set temperature in the hot offset occurrence region higher than that and the third set temperature in the cold offset occurrence region lower than the set temperature capable of fixing are set, and the temperature detection member When the second or third set temperature is detected, it is preferable that the temperature control means determine that the temperature is abnormal and perform at least one of warning display and print operation stop.

  Furthermore, in the fixing device according to the present invention, when the fourth set temperature is in an abnormally high temperature generation region higher than the second set temperature and the temperature detecting member detects the fourth set temperature, It is preferable to stop the operation.

According to the present invention, since the heat insulating member is provided between the side edge of the reflecting member and the inner peripheral surface of the fixing belt, heat loss can be suppressed even if the reflecting member and the inner peripheral surface of the fixing belt are in sliding contact with each other. Since the heat insulating member also serves as a guide for guiding the rotation of the fixing belt, the fixing belt can be stably rotated.

Embodiments of the present invention will be described below with reference to the drawings. First, an example of the image forming apparatus according to the present invention will be clarified.
FIG. 1 is a schematic view showing a color copying machine as an example of an image forming apparatus. The image forming apparatus shown here includes an image forming unit 1 that forms a toner image on a recording medium, and a fixing device 2 that fixes the toner image on the recording medium.

  The image forming means 1 shown in FIG. 1 has first to fourth image carriers 3C, 3M, 3Y, 3BK configured as drum-shaped photosensitive members, and a yellow toner image is formed on each of the image carriers. A magenta toner image, a cyan toner image, and a black toner image are formed. An intermediate transfer belt 4 is disposed to face the first to fourth image carriers 3Y to 3BK. The intermediate transfer belt 4 is wound around rollers 5 and 6, and one of the rollers is driven (not shown). By being rotationally driven by the means, the vehicle is driven in the direction of arrow A.

  Since the operation of forming the toner image on each of the first to fourth image carriers 3C, 3M, 3Y, and 3BK is substantially the same, the toner image is applied to the first image carrier 3C. Only the structure to be formed will be described. The image carrier 3C is rotationally driven in the clockwise direction in FIG. 1, and at this time, the surface of the image carrier is uniformly charged to a predetermined polarity by the charging roller 8. Then, the charged surface is irradiated with a light-modulated laser beam L emitted from the laser writing unit 9. As a result, an electrostatic latent image is formed on the image carrier 3C, and the electrostatic latent image is visualized as a cyan toner image by the developing device 10. A transfer roller 11 is disposed at a position substantially opposite to the image carrier 3C with the intermediate transfer belt 4 interposed therebetween, and a voltage having a polarity opposite to the charging polarity of the toner on the image carrier 3C is applied to the transfer roller 11. As a result, the cyan toner image on the image carrier 3C is transferred onto the intermediate transfer belt 4. The transfer residual toner that is not transferred to the intermediate transfer belt 4 and remains on the image carrier 3C is removed by the cleaning device 12.

  In exactly the same manner, a magenta toner image, a yellow toner image, and a black toner image are respectively formed on the second to fourth image carriers 3M, 3Y, and 3BK, and these toner images are transferred with a cyan toner image. The images are sequentially superimposed and transferred onto the intermediate transfer belt 4.

  On the other hand, a recording medium P made of, for example, transfer paper, a resin sheet, a resin film, or the like is fed from a paper feeding unit 13 provided below the image forming unit 1, and the recording medium P is indicated by an arrow B as shown in FIG. Then, it is fed toward the roller 6 of the intermediate transfer belt 4. A secondary transfer roller 14 is disposed at a position substantially opposite to the roller 6 with the intermediate transfer belt 4 interposed therebetween, and the recording medium P is fed between the intermediate transfer belt 4 and the secondary transfer roller 14. A voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 14, whereby the superimposed toner image on the intermediate transfer belt 4 is transferred onto the recording medium P. The transfer residual toner that is not transferred to the recording medium P and remains on the intermediate transfer belt 4 is removed by the intermediate transfer belt cleaning device 7.

The recording medium P carrying the four-color unfixed toner images in this way is sent to the fixing device 2, and at this time, the toner image is fixed on the recording medium P.
The fixing device 2 according to the present embodiment has a configuration capable of instantaneous start-up and quick start (10 seconds or less), and is pressed against the fixing belt 21 and the fixing belt 21 as shown in FIG. It has a basic configuration of a pressure roller 22 and a heating unit that directly heats the fixing belt 21 by radiant heating.

  The fixing belt 21 and the pressure roller 22 form a nip when a fixing member 23 provided in a loop of the fixing belt 21 is pressed against the pressure roller 22 via the fixing belt 21. The fixing member 23 is configured by sequentially supporting a heat insulating member 31 and a heat-resistant elastic member 32 on a support member 30 supported by a fixing side plate 35 (shown in FIG. 3) and covering with a protective member 33. Metal materials such as stainless steel and aluminum are generally used. The support member 30 may be made of carbon fiber reinforced metal or the like as a special material. Carbon fiber reinforced metal includes, for example, fiber reinforced metal, and its features include a specific gravity of 2.2 to 2.5 (light weight equivalent to aluminum), a bending amount of about 1 / 2.5 of iron, and heat. Conductivity is 180 to 500 w / mk (good thermal conductivity higher than aluminum in the fiber direction, and heat insulation in the direction perpendicular to the fiber direction).

  Further, the fixing belt 21 does not deform (dent phenomenon) even if any member comes into contact with the belt, and the belt has sufficient rigidity to maintain a substantially cylindrical shape. The base material constituting the fixing belt 21 is nickel. These are metal materials such as stainless steel and heat-resistant resin materials such as polyamideimide and polyimide. When the base material of the fixing belt 21 is a heat-resistant resin material such as a polyimide material, the diameter of the cylindrical shape is 30 to 60 mm, preferably 30 to 50 mm, and the thickness is 50 μm to 120 μm, preferably 50 μm to 100 μm. It is desirable to be in range. The fixing belt 21 of this example includes at least a base material (50-100 μm polyimide or 10-50 μm Ni, SUS, etc.), an intermediate layer (a heat-resistant elastic member 50-300 μm Si rubber or fluororubber), and a surface layer. It is a belt having three layers (release member Si rubber or 10-30 μm fluorine resin). The fixing belt 21 having three or more layers is indispensable for color high image quality.

  In the fixing device 2 configured as described above, the pressure roller 22 is driven to rotate counterclockwise in FIG. 2, and the fixing belt 21 is rotated in the clockwise direction following the rotation of the pressure roller 22. Then, the recording medium P carrying the unfixed toner image is fed into the nip between the fixing belt 21 and the pressure roller 22 so that the unfixed toner image is fixed on the recording medium P as a permanent image by heat and pressure.

  In the fixing device 2 shown in FIG. 2, a halogen heater 24 as the heating unit is provided inside the fixing belt 21, and the fixing belt 21 is directly heated by a radiant heat source composed of the halogen heater 24. In addition, since the image forming apparatus is configured not to preheat the fixing device 2 but to instantaneously start up the fixing belt 21 during recording, it is required to maximize the heating efficiency of the halogen heater 24.

  In accordance with such a requirement, a reflection member 25 made of metal or a heat insulating resin having a metal deposited on the reflection surface is provided between the halogen heater 24 and the fixing member 23. As the reflecting member 25, it is preferable to use a reflecting member having a reflectance of 90% or more in order to increase the heating efficiency.

  The reflection member 25 increases thermal efficiency due to reflection, blocks radiation and convective heat transfer to the fixing member 23, and reduces wasteful heat supply to the fixing member 23. When the reflecting member 25 is disposed inside the fixing belt 21, the fixing belt 21 may be in sliding contact with the end of the reflecting member 25, and at this time, the fixing belt 21 loses heat. Therefore, in order to reduce such heat loss, as shown in FIGS. 2 and 4, heat insulation members 26 made of felt, foamed silicone, heat resistant resin, etc. are provided on both side edges of the reflection member 25, so that the fixing belt 21 is provided. The heat loss when the reflecting member 25 is touched is minimized. Further, as shown in FIG. 5, when the reflecting member 25 has a length straddling the paper passing area and the non-paper passing area, the heat insulating member 26 is provided so as to protrude outward only in the non-paper passing area. The heat insulating member 26 is in contact with and guides the fixing belt 21 in the non-sheet passing region. However, since the reflecting member 25 is drawn inward in the sheet passing region, the heat insulating member 26 is not touched.

Furthermore, in order to increase the heating efficiency of the halogen heater 24, it is effective if the internal space of the fixing belt 21 is substantially sealed because the internal heat can be prevented from escaping.
Therefore, as shown in FIG. 3, belt guide members 36 are provided at both ends of the belt, which is a non-sheet passing region of the fixing belt 21. As shown in FIG. The belt guide member 36 includes a flange portion 36a having a diameter larger than the diameter of the fixing belt 21 and a guide tube 36b that is fixed to the flange portion 36a and enters the belt, and both ends of the fixing belt 21 are obstructed in rotation. Heating efficiency can be improved by suppressing heat escape and light leakage by closing the cover. Further, the belt guide member 36 also has an effect of guiding the belt rotation while maintaining the cylindrical shape of the fixing belt 21.

  Further, in order to increase the heating efficiency of the halogen heater 24, the fixing belt 21 must be set to a thin and low heat quantity and set so that the light from the halogen heater 24 does not leak from the fixing belt 21. However, according to the experiments of the present inventor, the fixing belt 21 is composed of three layers, which are a polyimide base layer 21a having a thickness of 100 μm, an intermediate layer 21b having a thickness of 200 μm, and a PFA surface layer 21c having a thickness of 30 μm. When configured, light leakage from the internal halogen heater was confirmed. Such light leakage is because polyimide is translucent, PFA is transparent, and although the intermediate layer 21b is provided with silicone rubber, it is so thin as 200 μm that light passes through the pores in the rubber layer. is there.

  Therefore, at least one of the three layers is subjected to black processing as light leakage prevention means on the fixing belt 21. When the halogen heater 24 is arranged inside the fixing belt 21, the intermediate elastic layer 21b as shown in FIG. 6A or the base material layer 21a as shown in FIG. When a halogen heater 24 as a heating means is disposed outside the fixing belt 21, which will be described later, the surface release layer 21c as shown in FIG. 7A or the intermediate elastic layer 21b as shown in FIG. 7B. Black processing. In FIG. 6 and FIG. 7, the black-treated layer is shown in black.

  As described above, it has been found that blackening at least one of the layers constituting the fixing belt 21 has a significant reduction effect of about 50% in start-up time. This is presumably due to the fact that the black light treatment reduces the light transmittance and increases the heat absorption rate of black.

  Furthermore, in order to increase the heating efficiency of the halogen heater 24, it is also effective to suppress the heat of the fixing belt 21 from escaping to the pressure roller 22. Accordingly, as shown in FIG. 8, the pressure roller 22 has a structure in which a hollow fiber, a hollow particle, or the like is provided in the heat insulating layer 22b that is a silicone rubber foam or a silicone layer to increase the air content and increase the air heat insulating effect. Is adopted. Further, since the pressure roller 22 is used as a belt driving roller for driving the fixing belt 21, a roller having high rigidity must be used. In addition, the roller with high rigidity here is a thing of 80 degree | times or more in Asuka C hardness. Moreover, in FIG. 8, the code | symbol 22a is a metal core and 22c is a mold release layer.

  The pressure roller 22 having such a structure, that is, a structure in which hollow fibers, hollow particles, and the like are provided in the heat insulating layer 22b, which is a silicone layer, has a large roller surface hardness (80 degrees or more in Asuka C hardness) and a small compression set. It can be used as a belt drive roller.

  In this way, the fixing device 2 is designed to maximize the heating efficiency of the halogen heater 24 to enable quick start (10 seconds or less). However, a non-rotating accident occurs in the fixing belt 21. If this happens, the belt will overheat instantaneously, causing burnout and fire.

  Therefore, in the fixing device 2 of the present embodiment, a temperature detection member 40 that is not in contact with the belt is provided in a region where the halogen heater 24 directly heats the fixing belt 21. And as the temperature detection member 40, the well-known infrared detection method of good thermal responsiveness is employ | adopted. Further, the region in which the halogen heater 24 in which the temperature detecting member 40 is disposed directly heats the fixing belt 21 is a region facing the halogen heater 24 and the fixing belt 21 in the example shown in FIG. This is the region where the temperature rises most when it occurs.

  By the way, when the temperature detection member 40 has to be disposed at a position facing the end of the reflection member 25 for some reason, the reflection member 25 exists between the temperature detection member 40 and the halogen heater 24, and the halogen The temperature detection member 40 is not disposed in a region where the heater 24 directly heats the fixing belt 21. Therefore, the reflection member 25 is provided with a notch 25a at a portion that blocks the temperature detection member 40 and the halogen heater 24 as shown in FIG. If comprised in this way, the temperature detection member 40 will have the same effect as what was installed in the area | region directly heated facing the halogen heater 24. FIG.

  By configuring in this way, the temperature of the portion directly heated by the halogen heater 24 is detected. Therefore, even if a belt non-rotation accident occurs, the excessive temperature rise can be detected immediately, and accordingly Safe control can be performed. The temperature control including the safety control adopted by the fixing device 2 will be described later.

  The fixing device 2 shown in FIG. 10 is a modified example. In this example, the fixing device shown in FIG. 2 is that a halogen heater 24 as a heating source is provided outside the fixing belt 21 and a temperature detection member 40 is provided inside the halogen heater 24. 2 and different. In addition, the same code | symbol is attached | subjected to the member same as the member shown in FIG.

  As shown in FIGS. 2 and 11, the heat-resistant elastic member 32 is formed in a non-roller shape having a rectangular cross section, so that the fixing member 23 can form a wide fixing nip at a low pressure. Therefore, it can be applied to increase the speed of the image forming apparatus, and is effective for instantaneous start-up of low-temperature fixing.

  Further, in order to suppress the occurrence of the non-rotation accident itself, the fixing belt 21 travels reliably by the rotation of the pressure roller 22. Therefore, the heat-resistant elastic member 32 of the fixing member 23 is formed in a rotatable roller shape as shown in FIGS. 12 and 13 so that the fixing belt 21 sandwiched between the fixing member 23 and the pressure roller 22 can be smoothly and It is possible to travel reliably.

Next, temperature control of the fixing device 2 will be described with reference to FIG.
The temperature control circuit 42 includes at least a first set temperature T1 in a region where the fixing belt 21 can be fixed, a second set temperature T2 in a hot offset generation region higher than a set temperature where fixing can be performed, and a set temperature where fixing is possible. The temperature of the third set temperature T3 in the cold offset occurrence region lower than that is set, and the comparison circuit 41 compares the temperature of the temperature detection member 40 with the first to third set temperatures T1 to T3. When the temperature of the second set temperature T2 or the third set temperature T3 is detected, it is determined that there is an abnormality, a heater OFF signal is output, and the halogen heater 24 is turned off via the switching element 43. At the same time, an operation stop signal is output to the conveyance control means 44 to stop conveyance of the recording medium P and to stop the printing operation. By controlling in this way, the printing operation is stopped even when a hot offset or a cold offset occurs, so that printing of an abnormal image can be minimized. Further, a warning is displayed at the same time, and for example, a service man call is displayed on an operation panel (not shown).

  Further, when the fourth set temperature T4 in the abnormally high temperature generation region higher than the second set temperature is provided and the temperature detection member 40 detects the fourth set temperature T4, the heater is turned off and the printing operation is performed. To stop. In addition, since the belt heating rate is extremely fast in a high-speed startup (less than 10 seconds) device such as the fixing device 2, means for preventing belt burnout and ignition by a safety device using a thermal fuse or thermostat is a safety standard. Needless to say, it is desirable that at least the soft detection means as described above is provided in order to avoid belt burnout. In this case, it is desirable that the fourth set temperature T4 is 220 ° C. or higher and 260 ° C. or lower as a temperature at which the belt can be used again without damaging the belt.

  The temperature detection member 40 is advantageously an infrared detection member, but may be a thermistor detection or the like. Further, the temperature detection member 40 detects a temperature at an abnormally high temperature and cuts off the power supply to the heat source. The present invention can be applied to a thermo SW and a thermal fuse used as a safety measure such as so-called burnout ignition prevention.

1 is a schematic explanatory diagram of an image forming apparatus showing an embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating an example of a fixing device according to the present invention. FIG. 3 is a cross-sectional explanatory view showing a side part structure of the fixing device. It is a perspective view which shows an example of a reflection member. It is a perspective view which shows the modification of a reflection member. (A), (b) is a fragmentary sectional view which shows an example of a fixing belt. (A), (b) is a fragmentary sectional view which shows the other example of a fixing belt. It is sectional explanatory drawing which shows an example of a pressure roller. It is a perspective view which shows the other example of a reflection member. FIG. 10 is an explanatory diagram illustrating a modified example of the fixing device. It is explanatory drawing of a fixing member. It is explanatory drawing which shows the modification of a fixing member. It is explanatory drawing which shows the modification of a fixing member. It is a block diagram which shows a temperature control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming means 2 Fixing device 21 Fixing roller 22 Pressure roller 24 Halogen heater (heating means)
40 Temperature detection member

Claims (14)

A substantially cylindrical fixing belt having flexibility, a fixing member disposed fixing the belt, and the pressure member to form a press nip through the fixing belt and the fixing member, the fixing belt A heating device that directly heats from the inside by a radiant heat source, and a fixing device that performs fixing by passing a recording medium carrying an unfixed toner image in the nip;
A reflecting member provided between the radiant heat source and the fixing member; and a heat insulating member provided between a side edge of the reflecting member and an inner peripheral surface of the fixing belt facing the side edge. ,
The fixing device, wherein the heat insulating member also serves as a guide for guiding rotation of the fixing belt by sliding contact with an inner peripheral surface of the fixing belt. The fixing device according to claim 1, wherein the heat insulating member is provided in a non-sheet-passing region in a side edge of the reflecting member that faces the inner peripheral surface of the fixing belt. The side edge of the reflection member is formed by bending the reflection member, and the heat insulating member is provided between the side edge and the inner peripheral surface of the fixing belt. The fixing device described. A temperature detecting member for detecting the temperature of the fixing belt, wherein the temperature detecting member is in a region where the fixing belt is directly heated by the radiant heat source, and at a position facing the radiant heat source via the fixing belt; The fixing device according to claim 1, wherein the fixing device is disposed in a non-contact manner with the fixing belt.   When the reflection member is provided between the temperature detection member and the radiant heat source, the temperature detection member and the radiant heat source are disposed at corresponding portions of the reflection member so as to face each other via the fixing belt. The fixing device according to claim 1, wherein a notch is provided.   6. The fixing device according to claim 1, wherein the fixing belt is substantially sealed by being guided by a belt guide member at both ends of the substantially cylindrical axial direction.   2. The fixing device according to claim 1, wherein the fixing belt includes two or more layers including a base material layer, and at least one layer of the fixing belt is subjected to a light leakage prevention process. The fixing device according to claim 7 , wherein the light leakage prevention process is to process at least one layer of the fixing belt substantially black.   2. The fixing device according to claim 1, wherein the fixing member is an elastic pressing member.   2. The fixing device according to claim 1, wherein the fixing member is a rotatable elastic roller.   2. The fixing device according to claim 1, wherein the pressure member is a roller having a heat insulating structure with high rigidity, and the fixing belt is driven to rotate by driving the roller.   Temperature control means for controlling the fixing belt to maintain a predetermined temperature; at least a first set temperature in a fixable region and a second in a hot offset occurrence region higher than the fixable set temperature; One or both of the third set temperature and the third set temperature in the cold offset generation region lower than the set temperature and the fixable set temperature are set, and the temperature detecting member detects the second or third set temperature. 2. The fixing device according to claim 1, wherein the temperature control unit determines that the temperature is abnormal and performs at least one of a warning display and a print operation stop process.   The printing apparatus has a fourth set temperature in an abnormally high temperature generation region higher than the second set temperature, and the printing operation is stopped when the temperature detection member detects the fourth set temperature. Item 13. The fixing device according to Item 1 or 12.   An image forming apparatus comprising the fixing device according to claim 1.

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