JP2023172866A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that prevents deterioration of a reflecting member, effectively uses heat transferred from a heat source to the reflecting member and a support member, and can reduce power consumption.SOLUTION: A fixing device comprises: an endless fixing member 21 that has flexibility; a slide member that slides with an inner periphery of the fixing member; a pressing member 22 that is in contact with an outer peripheral surface of the fixing member; a nip forming member 24 that is arranged inside the fixing member, and is in contact with the pressing member with the fixing member and the slide member therebetween to form a nip part; a support member 25 that supports the nip forming member; a heat source 23 that is arranged inside the fixing member and heats the fixing member; and a reflecting member 28 that reflects radiation heat from the heat source. The nip forming member has thermal conductivity of 10 W/mK or more.SELECTED DRAWING: Figure 2

Description

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

In an image forming apparatus, an unfixed toner image is transferred to a recording medium, and this recording medium is conveyed to a fixing device, and the unfixed toner image on the recording medium is fixed to the recording medium by heat and pressure. In recent years, market demands for energy saving and speeding up of image forming apparatuses have become stronger. If productivity is improved by increasing speed, the amount of heat from the heat source will also increase accordingly.

Patent Document 1 discloses a fixing device that uses a heat transfer auxiliary member that slides on the inner circumferential surface of a fixing belt and transfers heat in its longitudinal direction, and a nip forming member that is made of a heat-resistant resin mixed with a hollow filler. has been done. In Patent Document 1, by providing a nip forming member using a resin that is difficult to conduct heat, the thermal conductivity of the nip forming member is reduced, the amount of heat transferred to the nip forming member that does not contribute to fixing is reduced, and the amount of heat transferred to the nip forming member that does not contribute to fixing is reduced. It is said that it can reduce power consumption.

In Patent Document 1, a reflective member is used, and by using the reflective member, heat from a heat source to another member (for example, a support member that supports a nip forming member) can be reflected to the fixing member, thereby reducing energy consumption. It is said that this can be suppressed.

However, when using a nip forming member that is difficult to conduct heat as in Patent Document 1, the nip forming member becomes a heat conducting wall, making it difficult for the heat from the heat source to move from the reflecting member and the supporting member. For this reason, the reflective member and the support member become high in temperature, and the reflective member is likely to deteriorate. There is also a need for a mechanism that can reduce power consumption by effectively utilizing the heat transmitted from the heat source to the reflective member and support member.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fixing device that can prevent deterioration of the reflective member, effectively utilize the heat transmitted from the heat source to the reflective member and the support member, and reduce power consumption.

In order to solve the above problems, the fixing device of the present invention includes a flexible endless fixing member, a sliding member that slides on the inner circumference of the fixing member, and a sliding member that contacts the outer circumferential surface of the fixing member. a pressure member in contact with the member; a nip forming member disposed inside the fixing member that contacts the pressure member via the fixing member and the sliding member to form a nip portion; and supporting the nip forming member. a support member that is disposed inside the fixing member, a heat source that heats the fixing member, and a reflective member that reflects radiant heat from the heat source, and the nip forming member has a thermal conductivity of 10 W/mK. The present invention is characterized by the following.

According to the present invention, it is possible to provide a fixing device that can prevent deterioration of the reflective member, effectively utilize the heat transmitted from the heat source to the reflective member and the support member, and reduce power consumption.

1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. 1 is a schematic diagram showing an example of a fixing device according to the present invention. FIG. 2 is a schematic diagram showing an example of a fixing device that is not included in the present invention. 1 is a schematic diagram showing an example of a fixing device included in the present invention. FIGS. 3A to 4C are schematic diagrams illustrating an example of a nip forming member. FIGS. It is a perspective schematic diagram (a) and a plane schematic diagram (b) which show another example of a nip formation member. It is a perspective schematic diagram (a) and a side schematic diagram (b) which show another example of a nip formation member. They are a perspective schematic diagram (a), a side schematic diagram (b), and cross-sectional schematic diagrams (c) and (d) showing other examples of the nip forming member. FIG. 7 is a schematic diagram of main parts showing another example of the fixing device according to the present invention. FIG. 3 is a schematic diagram showing another example of the fixing device according to the present invention.

Hereinafter, a fixing device and an image forming apparatus according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and may be modified within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. These are also included within the scope of the present invention as long as they exhibit the functions and effects of the present invention.

The fixing device of the present invention includes: a flexible endless fixing member; a sliding member that slides on an inner circumference of the fixing member; a pressure member that comes into contact with an outer circumferential surface of the fixing member; a nip forming member that is disposed inside the member and contacts the pressure member via the fixing member and the sliding member to form a nip portion; a support member that supports the nip forming member; and the fixing member. a heat source that heats the fixing member, and a reflective member that reflects radiant heat from the heat source, and the nip forming member has a thermal conductivity of 10 W/mK or more. .

FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus according to this embodiment.
The image forming apparatus of this example is capable of forming a color image, and four image forming units 4 are provided side by side along the extending direction of the intermediate transfer belt 30. The four image forming units 4 have the same configuration except that they accommodate different color developers of yellow (Y), cyan (C), magenta (M), and black (K) corresponding to the color separation components of a color image. It becomes.

The image forming section 4 includes, for example, a latent image carrier, a charging device, a developing device, a cleaning device, and the like. For example, a drum-shaped photoreceptor is used as the latent image carrier. The surface of the photoreceptor is exposed by an exposure device. The charging device charges the surface of the photoreceptor. The developing device supplies toner to the surface of the photoreceptor. The cleaning device cleans the surface of the photoreceptor.

Although not particularly limited, for example, a document is read by the reading device 100, and image data is obtained. Exposure is performed based on the image data, and a latent image (also referred to as an electrostatic latent image) is formed on the photoreceptor. Development is performed by the developing device, and a toner image is formed on the photoreceptor.

The toner image formed on the photoreceptor is transferred to the intermediate transfer belt 30 by a transfer means. The toner image transferred to the intermediate transfer belt 30 is transferred onto a recording medium (also referred to as a recording material) by a transfer roller 36.

The recording medium is fed by a paper feed roller 11 from a paper feed tray 10, for example, and is conveyed by a registration roller 12. Recording media include, in addition to plain paper, cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, and the like. Furthermore, as is well known, a manual paper feeding mechanism may be provided.

The recording medium onto which the toner image has been transferred is conveyed to a fixing device 20. The fixing device 20 fixes the toner image (which may also be referred to as an unfixed image) transferred to the recording medium. The recording medium that has been fixed is discharged to the paper discharge tray 14. Images may be formed on both sides of the recording medium if necessary.

FIG. 2 is a schematic diagram showing the fixing device 20 of this embodiment.
The fixing device 20 of this embodiment includes, for example, a fixing belt 21, a belt support member 27, a sliding sheet 26, a pressure roller 22, a nip forming member 24, a stay 25, a heater 23, and a reflector 28.

The fixing belt 21 is an example of a fixing member, and is a flexible endless belt. The fixing belt 21 is supported by a belt support member 27 and is rotatable. The direction of the rotation axis of the fixing belt 21 is perpendicular to the paper surface, and is also referred to as the axial direction. The fixing belt 21 is heated by radiant heat from a heater 23 as a heat source disposed inside the fixing belt 21 (inside the loop).

The fixing belt 21 includes, for example, an inner base material made of a metal material such as nickel or SUS, or a resin material such as polyimide, and a base material made of PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer) or PTFE ( It is composed of a release layer on the outer peripheral side made of polytetrafluoroethylene (polytetrafluoroethylene) or the like. An elastic layer made of a rubber material such as silicone rubber, foamable silicone rubber, or fluororubber may be interposed between the base material and the release layer. If the thickness of this elastic layer is about 100 μm, the elastic deformation of the elastic layer when crushing and fixing unfixed toner can absorb minute irregularities on the belt surface, thereby avoiding the occurrence of uneven gloss.

The fixing belt 21 is preferably set to have an overall thickness of 1 mm or less and a diameter of 20 to 40 mm. In this case, a low heat capacity can be achieved. The thickness of each of the base material, elastic layer, and release layer constituting the fixing belt 21 can be changed as appropriate, but is set, for example, in the range of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm. It is preferable. In order to further reduce the heat capacity, the entire thickness of the fixing belt 21 is preferably 0.2 mm or less, more preferably 0.16 mm or less, and the diameter is 30 mm. The following is desirable.

The belt support member 27 supports the fixing belt 21 at both ends of the fixing belt 21, for example. The belt support member 27 may also be referred to as a belt holding member or the like. For example, a side plate flange can be used as the belt support member 27.

The sliding sheet 26 is an example of a sliding member, and is arranged to slide on the inner circumference of the fixing belt 21. Further, as shown in the figure, it is arranged at a position in contact with the nip forming member 24. The shape of the sliding sheet 26 is not particularly limited, and may be a U-shape as shown in the illustrated cross section, or may have another shape.

The sliding sheet 26 can be selected as appropriate, and for example, a low-friction sheet made of a low-friction material can be used. Moreover, as the sliding sheet 26, a sheet formed from fibers such as PTFE, etc., can be used, for example.

Pressure roller 22 is an example of a pressure member, and comes into contact with the outer peripheral surface of fixing belt 21 . The pressure roller 22 includes, for example, a core metal, an elastic layer made of foamable silicone rubber, fluororubber, etc. provided on the surface of the core metal, and a mold release material made of PFA, PTFE, etc. provided on the surface of the elastic layer. It can be composed of layers. For example, the pressure roller 22 is pressed against the fixing belt 21 by a spring of the pressure means, and at the location where it comes into pressure contact with the fixing belt 21, the elastic layer of the pressure roller 22 is crushed, thereby forming a fixing nip N of a predetermined width. be done. Note that the fixing nip N may also be referred to as a nip portion N or the like.

The pressure roller 22 is configured to be rotationally driven by a drive source such as a motor provided in the main body of the image forming apparatus, for example. When the pressure roller 22 is driven to rotate, its driving force is transmitted to the fixing belt 21 at the fixing nip N, and the fixing belt 21 is driven to rotate. The fixing belt 21 rotates while being pinched by the fixing nip N, and is guided by side plate flanges arranged at both ends outside the fixing nip N and runs.

In this embodiment, the pressure roller 22 is a solid roller, but it may be a hollow roller. In that case, a heat source such as a halogen heater may be provided inside the pressure roller 22. The elastic layer may be made of solid rubber, but if there is no heat source inside the pressure roller, sponge rubber may be used. Sponge rubber is more desirable because it has better heat insulation and makes it difficult for the fixing belt 21 to lose heat.

The nip forming member 24 is disposed inside the fixing belt 21 and comes into contact with the pressure roller 22 via the fixing belt 21 and the sliding sheet 26 to form a nip portion N. Detailed examples of the shape, material, etc. of the nip forming member 24 will be described later.

The stay 25 is an example of a support member and supports the nip forming member 24.

The heater 23 is an example of a heat source, is disposed inside the fixing belt 21, and heats the fixing belt 21. The heater 23 heats the fixing belt 21 using, for example, radiant heat. As the heat source, for example, a halogen heater can be used, and in addition, an induction heating device, a resistance heating element, a carbon heater, etc. may be used. As illustrated, there may be multiple heat sources.

The reflector 28 is an example of a reflective member, and reflects the radiant heat of the heater 23. By using the reflector 28, the efficiency of heating the fixing belt 21 by the heater 23 can be increased. Further, by using the reflector 28, it is possible to suppress energy consumption due to heating of the stay 25 by radiant heat from the heater 23.

As the recording medium P passes through the nip portion N, the unfixed image 32 on the recording medium P is fixed onto the recording medium P. The white arrow in the figure schematically indicates the conveyance direction of the recording medium P.

In this embodiment, the thermal conductivity of the nip forming member 24 is 10 W/mK or more. Thereby, the heat of the reflector 28 can be easily transferred to the fixing belt 21, and damage to the reflector 28 can be suppressed. In addition, by setting the thermal conductivity of the nip forming member 24 to 10 W/mK or more, the heat from the heat source can be easily transmitted to the nip part N, and the heat from the heat source can also be effectively used in the nip part N, resulting in consumption. Power can be reduced.

A detailed example of the nip forming member of this embodiment will be described using FIGS. 3A and 3B.
FIG. 3A is a comparative example not included in the present invention, and is a schematic diagram of a fixing device using a nip forming member 24a having a thermal conductivity of less than 10 W/mK. The nip forming member 24a in this comparative example uses a material with low thermal conductivity. The black arrows in the figure schematically indicate heat transfer paths.

As shown in the figure, heat from the heater 23 is transmitted to the reflector 28, and heat from the reflector 28 is transmitted to the stay 25. In this comparative example, since the nip forming member 24a having low thermal conductivity is used, the heat transmitted to the stay 25 cannot or is difficult to transfer to the nip forming member 24a. Therefore, the reflector 28 and the stay 25 become high in temperature, and the reflector 28 tends to deteriorate. Deterioration of the reflector 28 may lead to damage. Further, the heat transmitted to the reflector 28 and the stay 25 is not effectively utilized, and power consumption cannot be reduced.

FIG. 3B is a schematic diagram of the fixing device 20 of this embodiment, and is the same diagram as FIG. 2. In this embodiment, a material with high thermal conductivity is used for the nip forming member 24, and the thermal conductivity of the nip forming member 24 is 10 W/mK or more. Therefore, the heat transmitted from the heater 23 to the stay 25 via the reflector 28 can be transferred to the nip forming member 24. Thereby, the temperature of the reflector 28 can be prevented from rising excessively, and deterioration and damage of the reflector 28 can be suppressed. Furthermore, in this embodiment, the heat transferred to the nip forming member 24 is transferred to the nip portion N, so that the heat transferred to the nip forming member 24 can be effectively utilized in the nip portion N, thereby reducing power consumption. I can do it.

Considering the case where heat is transferred from the nip forming member 24 to the nip portion N via the sliding sheet 26, the sliding sheet 26 is preferably made of a material with excellent heat resistance.

The material for the nip forming member 24 can be appropriately selected and used as long as it can make the thermal conductivity of the nip forming member 24 10 W/mK or more. As the material of the nip forming member 24, it is preferable to use a metal material, and it is preferable that the nip forming member 24 is made of a metal material. In this case, it becomes easier to increase the thermal conductivity of the nip forming member 24 to 10 W/mK or more.

The metal material can be selected as appropriate, and is preferably a steel plate such as SECC material (electrogalvanized steel plate) or aluminum. When SECC material or aluminum is used, there is also the advantage that it is easy to process.

It is preferable that the nip forming member 24 consists of one plate member (which may also be simply referred to as a plate). In this case, the heat from the reflector 28 and the stay 25 can be easily transferred to the nip portion N. Moreover, it is more preferable that the nip forming member 24 is made of a single metal plate member (which may also be referred to as a sheet metal or the like).

The shape of the nip forming member 24 can be selected as appropriate. As shown in FIG. 2, the nip forming member 24 has the shape of a plate member bent twice in a cross section perpendicular to the axial direction of the fixing belt 21, and has two ends facing in the same direction. is preferred. In other words, this shape can be said to be a U-shape. In the case of such a shape, machining is easy and machining accuracy can be improved.

FIG. 4 shows an example of the nip forming member 24. FIG. 4 is a diagram showing a cross section of the fixing belt 21 perpendicular to the axial direction. The nip forming member 24 shown here has a thermal conductivity of 10 W/mK or more. Note that FIG. 4 is a diagram showing a cross section perpendicular to the axial direction of the fixing belt 21, and the axial direction of the fixing belt 21 is sometimes referred to as the longitudinal direction of the nip forming member 24. Further, the longitudinal direction of the nip forming member 24 may be simply referred to as the longitudinal direction.

Although the nip forming member 24 shown in FIG. 4(a) has thermal conductivity that satisfies the requirements of this embodiment, it is not a single plate member. Aluminum die-casting is an example of a metal with high thermal conductivity, but if the nip forming member 24 shown in FIG. 4(a) is manufactured using aluminum die-casting, the processing cost will increase. Further, when the nip forming member 24 having such a shape is manufactured using a mold, the accuracy in molding becomes low.

The nip forming member 24 shown in FIG. 4(b) is an example of a case where it is made of one sheet metal. In this example, all that is required is bending it into a U-shape, which increases precision and reduces manufacturing costs. This nip forming member 24 has the shape of a plate member bent twice, with two ends facing in the same direction.

When forming the nip forming member 24 by bending a plate member, the bent corner may have an angled shape such that two straight lines intersect, for example, as shown in FIG. 4(b). , Usually, a bending radius is easily formed as shown in FIG. 4(c). When forming the U-shaped nip forming member 24 by bending the plate member, it is preferable to have a bending radius, and in this case, the rotation of the fixing belt 21 can be made less likely to be inhibited.

Further, when forming the U-shaped nip forming member 24 by bending the plate member, it is preferable that the following B>A is satisfied. That is, in a cross section perpendicular to the axial direction (longitudinal direction) of the fixing belt 21, the nip forming member 24 has a length A on the nip portion N side, and extends from one end to the other in a shape where the plate member is bent twice. When the distance to the end of is B, it is preferable that B>A. The length A may also be referred to as the length of the straight portion of the nip forming member 24 on the nip portion N side.

When the nip forming member 24 is formed by bending a plate member and the nip forming member 24 has a bending radius, B>A is satisfied to make it difficult for the nip forming member 24 to interfere with the rotation of the fixing belt 21. This makes it possible to prevent the rotation of the fixing belt 21 from being affected. Furthermore, in this case, the support from the stay 25 is stable. When forming the plate member into a U-shape to form the nip forming member 24, if B>A is not satisfied (B≦A), it becomes difficult for the stay 25 to support the nip forming member 24.

An example of a perspective view of the nip forming member 24 is shown in FIG. 5(a). Further, FIG. 5(b) shows a plan view of FIG. 5(a) when viewed from inside the fixing belt 21. As shown in FIG. The example shown in FIG. 5 is an example of a nip forming member 24 made by bending one sheet metal twice.

As shown in the figure, the nip forming member 24 of this example has a plurality of convex portions (for example, convex portions 24x, 24y, 24z). In other words, it can be said that a plurality of gaps are provided in the portion where the plate member is bent. In addition, it can also be said to have a shape in which a plurality of convex portions are bent one by one. For example, when the bending heights C1, C2, and C3 become small, it is preferable to use a configuration in which each wire is bent one by one as shown in the figure, because it is easier to obtain precision in processing.
This is for the sake of

FIG. 6(a) shows another example of a perspective view of the nip forming member 24. Further, FIG. 6(b) shows a side view of the nip forming member 24 in FIG. 6(a). The example shown in FIG. 6 is also an example of a nip forming member 24 made by bending one sheet metal twice.

Also in the example shown in FIG. 6, the nip forming member 24 has a plurality of convex portions (for example, convex portions 24x, 24y, 24z). In this example, in the axial direction of the fixing belt 21 (the longitudinal direction of the nip forming member), the plurality of convex portions are highest at the center in the axial direction and become lower toward the ends in the axial direction. For example, the height of the protrusion 24z on the center side in the longitudinal direction is c3, which is higher than other protrusions, and the height of the protrusion 24x on the end side in the longitudinal direction is c1, which is higher than other protrusions. It's getting lower. In the illustrated example, the relationship is c1<c2<c3.

In FIG. 6, only one side in the longitudinal direction is illustrated, and illustration of the other side is omitted. Similarly, on the other side, the height is highest at the center in the axial direction and becomes lower toward the ends in the axial direction. In other words, the height of the U-shape of the nip forming member 24 produced by bending it into a U-shape is high at the center and decreasing toward the ends.

The stay in this example is held at the ends, and the center side is not equipped with a holding mechanism. As a result, the force received from the nip portion is held at the ends and supported, but the center cannot receive the force, so the center portion of the stay 25 becomes easily bent. As in this example, in the plurality of convex portions, the center in the axial direction is the highest and it becomes lower toward the end in the axial direction, so that the nip portion N can be stably formed even if the stay 25 is bent. be able to.

In addition, even if a convex part is not formed on the two end sides of the part where the plate member is bent twice, the height of the bent part is highest at the center in the axial direction, and the height at the end in the axial direction is the highest. It is preferable that the height decreases towards the end.

FIG. 7 shows another example of the nip forming member 24. FIG. 7(a) is a perspective view of the nip forming member 24 of this example. As shown in the figure, also in this example, the nip forming member 24 has a plurality of convex portions (convex portions) convex in the direction opposite to the nip portion N on the two end sides of the portion where the plate member is bent twice. For example, it has convex portions 24x, 24y, 24z). FIG. 7(b) is a side view of the nip forming member 24 in FIG. 7(a). FIG. 7(c) is a sectional view of a portion c in FIG. 7(a), and FIG. 7(d) is a sectional view of a portion d in FIG. 7(a).

In this example, when the surface of the nip forming member 24 when viewed from the direction in which the recording medium P enters the nip portion N is taken as a side surface, the plurality of convex portions are as follows when viewed from the side surface: The roots of adjacent convex parts are connected. Note that the broken line in FIG. 7(b) schematically indicates the height of the unbent portion of the plate member. Since the roots of adjacent convex portions are connected, the portion where the convex portions are connected is higher than the broken line portion. Further, as shown in FIG. 7D, since the roots of adjacent convex portions are connected, the cross section of the portion d is convex in the direction opposite to the nip portion N. Note that the side surface referred to here can also be said to be a surface when viewed from a direction along a direction perpendicular to the axial direction of the fixing belt 21.

For example, in the case of the nip forming member 24 shown in FIG. 5, it is necessary to bend each convex portion one by one to form a U-shape, which not only requires manufacturing time but also makes it difficult to achieve accuracy. In addition, since the roots of adjacent convex portions are not connected, it becomes easy to bend due to the force generated when forming the nip portion N. Further, due to the nip forming member 24 being bent, it may not be possible to form the desired nip portion N in some cases.

On the other hand, as in this example, since the roots of adjacent convex portions are connected, the strength increases against the force generated when forming the nip portion N, and it is possible to suppress the nip forming member 24 from bending. . Further, in this example, since only one bending is required, there is an advantage that accuracy is improved compared to bending the convex portions one by one.

In addition, when trying to create a shape with connected roots as shown in Figure 7 using conventionally used resins with low thermal conductivity, shrinkage occurs when molding because there are many parts with different thicknesses. Resulting in. For this reason, the precision of the tip of the U-shaped bend becomes low. On the other hand, also in this example, it is preferable to make the nip forming member 24 from a metal material, and by making the nip forming member 24 having the shape shown in FIG. 7 from a metal material, the accuracy of the tip of the U-shaped bend is improved. can be done.

Note that the example shown in FIG. 7 satisfies B>A, and is a preferable configuration from this point of view. Also, in the example shown in FIG. 7, as shown in FIG. 6, in the axial direction of the fixing belt 21, the plurality of convex portions are highest at the center in the axial direction and become lower toward the ends in the axial direction. It is more preferable to be present.

FIG. 8 shows an example of the relationship between the nip forming member 24 and the nip portion N. In this embodiment, in the cross section perpendicular to the axial direction of the fixing belt 21, the nip forming member 24 has a length on the side of the nip portion N as A, and a nip width of the nip portion N as C, and A>C. It is preferable that there be. In this case, the nip stability of the nip portion N can be improved.
Note that, similarly to the above, the length A may be referred to as the length of the straight portion of the nip forming member 24 on the nip portion N side.

In order to achieve A>C in this way, for example, the shape of the nip forming member 24, the layer structure of the pressure roller 22, the pressing force of the pressure roller 22, etc. are appropriately selected, although there are no particular restrictions.

FIG. 9 shows another example of the fixing device 20 of this embodiment.
In the fixing device 20, if the temperature of the reflector 28 has not completely decreased, it may be preferable to further dissipate heat. In such a case, it is preferable to additionally use the sheet metal member 29. As shown in the figure, the sheet metal member 29 in this example is provided at a position not in contact with the stay 25 but in contact with the nip forming member 24, and on the opposite side to the nip portion N. Further, it is preferable that the thermal conductivity of the sheet metal member 29 is higher than that of the nip forming member 24, and this is done in this example.

By using such a sheet metal member 29, the nip forming member 24 and the sheet metal member 29 can be configured to be integrated, increasing the heat capacity of the nip forming member and allowing further heat dissipation. Thereby, the temperature of the reflector 28 can be suppressed from increasing, and deterioration and damage of the reflector 28 can be further suppressed.

The number of sheet metal members 29 may be one or more than one. By using one sheet metal member 29 whose thermal conductivity is higher than that of the nip forming member 24, the above effect can be obtained. By further adding the sheet metal member 29 whose thermal conductivity is higher than that of the nip forming member 24, it becomes easier to dissipate heat. On the other hand, there may be cases where the heat dissipation becomes large and the temperature drops too much. In this case, by adding one more sheet metal member whose thermal conductivity is lower than that of the nip forming member 24, it is possible to suppress heat radiation from the nip forming member 24.

Aspects of the present invention are, for example, as follows.
<1> A flexible endless fixing member, a sliding member that slides on the inner circumference of the fixing member, a pressure member that comes into contact with the outer circumferential surface of the fixing member, and a a nip forming member that is disposed and contacts the pressure member via the fixing member and the sliding member to form a nip portion; a support member that supports the nip forming member; and a support member disposed inside the fixing member. A fixing device comprising: a heat source that heats the fixing member; and a reflective member that reflects radiant heat from the heat source, and wherein the nip forming member has a thermal conductivity of 10 W/mK or more.
<2> The fixing device according to <1>, wherein the nip forming member is made of a metal material.
<3> The fixing device according to <1> or <2>, wherein the nip forming member is made of one plate member.
<4> The nip forming member is characterized in that, in a cross section perpendicular to the axial direction of the fixing member, the plate member is bent twice, and the two ends thereof are oriented in the same direction. The fixing device according to <3>.
<5> The nip forming member is characterized in that it has a plurality of convex portions that are convex in a direction opposite to the nip portion on two end sides of a portion where the plate member is bent twice. The fixing device according to <3> or <4>.
<6> The fixing device according to <5>, wherein the plurality of convex portions are highest at the center in the axial direction and become lower toward the ends in the axial direction in the axial direction of the fixing member. Device.
<7> When the surface of the nip forming member is viewed from the direction in which the recording medium enters the nip portion and the surface of the nip forming member is a side surface, the plurality of convex portions are adjacent to each other when viewed from the side surface. The fixing device according to <5> or <6>, wherein the bases of the convex portions are connected.
<8> The nip forming member has a length A on the nip side in a cross section perpendicular to the axial direction of the fixing member, and has a length A from one end to the other end in a shape where the plate member is bent twice. The fixing device according to any one of <4> to <7>, wherein B>A, where B is the distance.
<9> The nip forming member is configured such that in a cross section perpendicular to the axial direction of the fixing member, A>C, where A is the length on the nip part side and C is the nip width of the nip part. The fixing device according to any one of <4> to <8>.
<10> The fixing device according to any one of <1> to <9>, wherein the reflecting member has a portion in contact with the supporting member.
<11> A sheet metal member is provided at a position that is not in contact with the support member and is in contact with the nip forming member, and is on the opposite side of the nip portion, and the thermal conductivity of the sheet metal member is The fixing device according to any one of <1> to <10>, wherein the fixing device has a thermal conductivity higher than that of the nip forming member.
An image forming apparatus comprising the fixing device according to any one of <1> to <11>.

20 Fixing device 21 Fixing belt 22 Pressure roller 23 Heater 24 Nip forming member 25 Stay 26 Sliding sheet 27 Belt supporting member 28 Reflector 29 Sheet metal member 32 Unfixed image

JP 2017-116922 Publication

Claims (12)

a flexible endless fixing member;
a sliding member that slides on the inner periphery of the fixing member;
a pressure member that comes into contact with the outer peripheral surface of the fixing member;
a nip forming member that is disposed inside the fixing member and contacts the pressure member via the fixing member and the sliding member to form a nip portion;
a support member that supports the nip forming member;
a heat source disposed inside the fixing member and heating the fixing member;
a reflective member that reflects radiant heat from the heat source;
A fixing device characterized in that the nip forming member has a thermal conductivity of 10 W/mK or more. The fixing device according to claim 1, wherein the nip forming member is made of a metal material. The fixing device according to claim 1, wherein the nip forming member is made of one plate member. 3. The nip forming member has a shape obtained by bending a plate member twice in a cross section perpendicular to the axial direction of the fixing member, and has two ends facing in the same direction. The fixing device described in . 4. The nip forming member has a plurality of convex portions on two end sides of a portion where the plate member is bent twice, the convex portions being convex in a direction opposite to the nip portion. The fixing device described in . 6. The fixing device according to claim 5, wherein the plurality of convex portions are highest in the axial center of the fixing member and become lower toward the axial ends. When the surface of the nip forming member when viewed from the direction in which the recording medium enters the nip portion is a side surface,
6. The fixing device according to claim 5, wherein the plurality of protrusions are such that roots of adjacent protrusions are connected when looking at the side surface. In the cross section perpendicular to the axial direction of the fixing member, the nip forming member has a length on the nip side as A, and the distance from one end to the other end when the plate member is bent twice. 5. The fixing device according to claim 4, wherein when B, B>A. The nip forming member is characterized in that in a cross section perpendicular to the axial direction of the fixing member, A>C, where A is the length on the nip part side and C is the nip width of the nip part. The fixing device according to claim 4. The fixing device according to claim 1, wherein the reflective member has a portion in contact with the support member. having a sheet metal member at a position not in contact with the support member and in contact with the nip forming member, and on the opposite side of the nip portion;
The fixing device according to claim 1, wherein the thermal conductivity of the sheet metal member is greater than or equal to the thermal conductivity of the nip forming member. An image forming apparatus comprising the fixing device according to claim 1.

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