JP2024018613A - Fixing device and image forming device - Google Patents

Abstract

[Problem] Heat from a reflective member is easily transferred to a fixing member on the nip portion side via a support member, etc., and high temperature and deterioration of the reflective member can be suppressed, and temperature unevenness of the fixing member at the nip portion can be suppressed. Provide a fixing device. SOLUTION: A fixing member 106, a sliding member 110, a pressure member 107, a heat source 101, a first support member 104 that supports the sliding member, and a second support member that supports the first support member. a supporting member 103; and a reflecting member 102 that is in contact with the second supporting member and reflects heat from the heating source. The first support member is made of a material having a thermal conductivity of 10 W/mK or more. The contact surfaces between the first support member and the second support member are discontinuous in the direction of the rotation axis of the fixing member, and a plurality of contact surfaces exist. A heat insulating member having heat insulating properties is provided on at least a portion of the plurality of contact surfaces, and the first support member and the second support member are in contact with each other via the heat insulating member at the location where the heat insulating member is provided. It is characterized by [Selection diagram] Figure 2

Description

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

2. Description of the Related Art Conventionally, it is known that an electrophotographic image forming apparatus uses a fixing device having a fixing belt and a pressure member facing the fixing belt. In such a fixing device, the fixing belt and the pressure member form a nip (fixing nip), and the recording medium is passed through the nip to perform fixing.

In such a fixing device, there is a known problem that when a recording medium is passed through the nip portion, the temperature of the non-sheet passing portion increases, resulting in damage to the fixing belt. As a countermeasure against this problem, a technique has been proposed in which a member with high thermal conductivity is arranged in a region where the temperature of the non-sheet passing area increases, thereby suppressing the rise in temperature of the non-sheet passing area.

For example, in Patent Document 1, in a nip forming member composed of a plurality of layers having different thermal conductivities, at least one of the plurality of layers has a different thermal conductivity in the longitudinal direction of the fixing member. Further, the layer of the nip forming member on the side that is in contact with the stay has a thermal conductivity higher than that of the stay. According to Patent Document 1, it is possible to suppress an increase in end temperature.

Furthermore, in the prior art, it has been proposed to use a reflective member that reflects heat from a heat source provided inside the fixing belt onto the fixing belt. For example, Patent Document 2 discloses the use of a reflective member that reflects heat from a heater onto a fixing belt. Further, in Patent Document 3, an image heating device includes a cylindrical metal member fixedly installed inside a cylindrical rotating body, and a reflection member that reflects radiant heat from a heating element toward the inner surface of the metal member. is disclosed.

Although the reflective member reflects heat from the heating source, there is a problem in that the reflective member becomes hot, causing damage or deterioration. In response to this, attempts have been made to transfer the heat of the reflective member to the supporting member of the reflective member, the nip forming member, and the fixing belt to prevent the reflective member from becoming too hot and to effectively utilize the heat of the reflective member in the nip area. being done. In this case, it is considered effective to make the nip forming member from a material with high thermal conductivity.

On the other hand, in the nip section, a temperature difference occurs in the fixing belt between the paper passing section and the paper non-passing section, and the temperature of the fixing belt becomes high in the paper non-passing section, which is the end side in the width direction of the recording medium. Put it away. As described above, if the configuration is such that the heat of the reflective member is effectively used in the nip portion, the temperature at the end of the fixing belt remains high after paper passes, which causes the problem of deterioration of the fixing belt. There is a concern that abnormal fixing may occur due to uneven temperature of the fixing belt.

Therefore, the present invention makes it possible to easily transfer the heat of the reflecting member to the fixing member on the nip side through the support member, etc., suppressing high temperatures and deterioration of the reflecting member, and reducing temperature unevenness of the fixing member in the nip. It is an object of the present invention to provide a fixing device that can suppress

In order to solve the above problems, the fixing device of the present invention includes a flexible and rotatable endless fixing member;
a sliding member that slides on the inner periphery of the fixing member;
a pressure member that is provided opposite to the sliding member with the fixing member in between and forms a nip portion with the fixing member;
a heat source provided inside the fixing member and heating the fixing member;
a first support member that supports the sliding member;
a second support member that supports the first support member;
a reflective member that is in contact with the second support member and reflects heat from the heating source;
The first support member is made of a material with a thermal conductivity of 10 W/mK or more,
The contact surface between the first support member and the second support member is discontinuous in the direction of the rotation axis of the fixing member, and a plurality of contact surfaces are present,
A heat insulating member having a heat insulating property is provided on at least a portion of the plurality of contact surfaces, and the first support member and the second support member are provided with the heat insulating member at the location where the heat insulating member is provided It is characterized by contacting through a member.

According to the present invention, heat from the reflective member is easily transferred to the fixing member on the nip portion side via the support member, etc., and high temperature and deterioration of the reflective member can be suppressed, and temperature unevenness of the fixing member at the nip portion can be suppressed. It is possible to provide a fixing device that can suppress this.

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 (Comparative Example 1) 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. FIG. 7 is a schematic diagram for explaining a contact surface between a metal supporter and a stay in Comparative Example 2, which is not included in the present invention. FIG. 3 is a schematic diagram for explaining a contact surface between a metal supporter and a stay in an example included in the present invention. 1A to 1C are schematic diagrams for explaining an example of a heat insulating member included in the present invention. FIG. FIG. 3 is a schematic diagram showing another example of the fixing device according to the present invention. FIG. 8 is a schematic exploded perspective view of the example shown in FIG. 7;

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 and rotatable endless fixing member;
a sliding member that slides on the inner periphery of the fixing member;
a pressure member that is provided opposite to the sliding member with the fixing member in between and forms a nip portion with the fixing member;
a heat source provided inside the fixing member and heating the fixing member;
a first support member that supports the sliding member;
a second support member that supports the first support member;
a reflective member that is in contact with the second support member and reflects heat from the heating source;
The first support member is made of a material with a thermal conductivity of 10 W/mK or more,
The contact surface between the first support member and the second support member is discontinuous in the direction of the rotation axis of the fixing member, and a plurality of contact surfaces are present,
A heat insulating member having a heat insulating property is provided on at least a portion of the plurality of contact surfaces, and the first support member and the second support member are provided with the heat insulating member at the location where the heat insulating member is provided It is characterized by contacting through a member.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.
Here, the "image forming apparatus" in this specification includes a printer, a copying machine, a facsimile machine, a printing machine, or a multifunction machine that combines two or more of these. Furthermore, "image formation" used in the following description means not only forming images with meaning such as characters and figures, but also forming images without meaning such as patterns.

First, with reference to FIG. 1, the overall configuration and operation of an image forming apparatus according to this embodiment will be described. As illustrated, the image forming apparatus 100 according to the present embodiment includes an image forming section 200, a fixing section 300, a recording medium supply section 400, and a recording medium ejecting section 500. The image forming unit 200 forms an image on a sheet-like recording medium such as paper. The fixing unit 300 fixes the image on the recording medium. A recording medium supply section 400 supplies a recording medium to the image forming section 200. The recording medium ejection unit 500 ejects the recording medium out of the apparatus.

The image forming section 200 is provided with four process units 1Y, 1M, 1C, and 1Bk as image forming units, an exposure device 6, and a transfer device 8. The exposure device 6 forms an electrostatic latent image on the photoreceptor 2 provided in each of the process units 1Y, 1M, 1C, and 1Bk. Transfer device 8 transfers the image onto a recording medium.

Each process unit 1Y, 1M, 1C, and 1Bk has basically the same configuration except that it contains toner (developer) of different colors of yellow, magenta, cyan, and black corresponding to the color separation components of a color image. be. When describing the process units 1Y, 1M, 1C, and 1Bk without distinction, they may also be referred to as process unit 1.

Each process unit 1 includes a photoreceptor 2, a charging member 3, a developing device 4, and a cleaning member 5.
The photoreceptor 2 is an example of an image carrier, and carries an image on its surface. It may also be called an electrostatic latent image carrier. The shape is, for example, a drum.
The charging member 3 charges the surface of the photoreceptor 2.
The developing device 4 supplies toner as a developer to the surface of the photoreceptor 2 to form a toner image. The toner image formed on the photoreceptor 2 may be referred to as a visible image, a toner image, or the like.
The cleaning member 5 cleans the surface of the photoreceptor 2.

The transfer device 8 includes an intermediate transfer belt 11, a primary transfer roller 12, and a secondary transfer roller 13. The intermediate transfer belt 11 is an endless belt member, and is stretched by a plurality of support rollers. Four primary transfer rollers 12 are provided inside the intermediate transfer belt 11. Each primary transfer roller 12 contacts each photoreceptor 2 via the intermediate transfer belt 11, thereby forming a primary transfer nip between the intermediate transfer belt 11 and each photoreceptor 2. The secondary transfer roller 13 contacts the outer peripheral surface of the intermediate transfer belt 11 to form a secondary transfer nip.

The fixing unit 300 is provided with a fixing device 20 that heats and fixes the recording medium onto which the image has been transferred. The fixing device 20 includes a fixing belt 106, a pressure roller 107, and the like.
The fixing belt 106 is an example of a fixing member, and is a flexible, rotatable, endless belt. Fixing belt 106 heats the image on the recording medium.
The pressure roller 107 is an example of a pressure member, and contacts the fixing belt 106 to form a nip portion (which may also be referred to as a fixing nip or the like).
The image is fixed on the recording medium by passing the recording medium through the nip portion.

The recording medium supply section 400 is provided with a paper feed cassette 14 and a paper feed roller 15. The paper feed cassette 14 accommodates paper P as a recording medium. The paper feed roller 15 sends out the paper P from the paper feed cassette 14.

Although the recording medium will be described below as paper, the recording medium is not limited to paper. The recording medium includes not only paper, but also an OHP sheet, a cloth, a metal sheet, a plastic film, a prepreg sheet in which carbon fiber is pre-impregnated with a resin, and the like. In addition to plain paper, paper also includes cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, and the like.

The recording medium ejection section 500 is provided with a pair of paper ejection rollers 17 and a paper ejection tray 18 . A pair of paper ejection rollers 17 eject the paper P out of the image forming apparatus. The paper ejection tray 18 places the paper P ejected by the paper ejection roller 17.

Next, an example of the printing operation of the image forming apparatus 100 will be described.
When a printing operation is started in the image forming apparatus 100, the photoreceptor 2 of each process unit 1 and the intermediate transfer belt 11 of the transfer device 8 start rotating. Further, the paper feed roller 15 starts rotating, and the paper P is sent out from the paper feed cassette 14. The fed paper P comes into contact with the pair of timing rollers 16 and comes to rest, and the conveyance of the paper P is temporarily stopped until an image to be transferred to the paper P is formed.

In each process unit 1, first, the surface of the photoreceptor 2 is charged to a uniform high potential by the charging member 3. Next, the exposure device 6 exposes the surface (charged surface) of each photoreceptor 2 based on the image information of the document read by the document reading device or the print image information instructed to print from the terminal. As a result, the potential of the exposed portion decreases, and an electrostatic latent image is formed on the surface of each photoreceptor 2.

The developing device 4 supplies toner to this electrostatic latent image, and a toner image is formed on each photoreceptor 2. When the toner images formed on each photoreceptor 2 reach the primary transfer nip (the position of the primary transfer roller 12) as each photoreceptor 2 rotates, they are transferred onto the rotating intermediate transfer belt 11 so as to overlap one another. be done. In this way, a full-color toner image is formed on the intermediate transfer belt 11.

Note that a single color image may be formed using any one of the process units 1, or an image may be formed using a plurality of process units.

Further, after the toner image is transferred to the intermediate transfer belt 11, residual toner and the like on each photoreceptor 2 is removed by the cleaning member 5.

The toner image transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer nip (the position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and onto the paper P conveyed by the timing roller 16. transcribed into.

Thereafter, the paper P is conveyed to the fixing device 20. The toner image on the paper P is heated and pressed by the fixing belt 106 and the pressure roller 107, and is fixed on the paper P. Then, the paper P is conveyed to the recording medium discharge section 500 and discharged to the paper discharge tray 18 by the paper discharge roller 17. This completes the series of printing operations.

FIG. 2 is a schematic diagram showing an example of the fixing device 20 of this embodiment.
The fixing device 20 of this embodiment includes, for example, a heater 101, a reflector 102, a stay 103, a metal supporter 104, a fixing belt 106, a pressure roller 107, a belt support member 108, and a heat soaking pad 110.

The fixing belt 106 is an example of a fixing member, and is a flexible, rotatable, endless belt. An endless belt may also be referred to as a sleeve-shaped belt. Fixing belt 106 is supported by belt support member 108 and is rotatable. The direction of the rotation axis of the fixing belt 106 is perpendicular to the plane of the paper, and is also referred to as the rotation axis direction, axial direction, or the like. The fixing belt 106 is heated by radiant heat from the heater 101 as a heat source disposed inside the fixing belt 106 (inside the loop).

The fixing belt 106 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 106 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 106 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 106 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 108 supports the fixing belt 106 at both ends of the fixing belt 106, for example. Belt support member 108 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 108.

Pressure roller 107 is in contact with the outer peripheral surface of fixing belt 106 . Further, the pressure roller 107 is provided facing the soaking pad 110 with the fixing belt 106 in between, and forms a nip portion N with the fixing belt 106. The pressure roller 107 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 107 is pressed against the fixing belt 106 by a spring of the pressure means, and at the location where it comes into pressure contact with the fixing belt 106, the elastic layer of the pressure roller 107 is crushed, thereby forming a nip N with a predetermined width. be done. Note that the nip portion N may also be referred to as a fixing nip N or the like.

The pressure roller 107 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 107 is driven to rotate, the driving force is transmitted to the fixing belt 106 at the nip portion N, and the fixing belt 106 is driven to rotate. The fixing belt 106 rotates while being sandwiched in the fixing nip N, and travels outside the nip N while being guided by side plate flanges arranged at both ends.

In this embodiment, the pressure roller 107 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 107. 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 106 to lose heat.

The metal supporter 104 is an example of a first support member and supports the soaking pad 110. The metal supporter 104 is placed in contact with the stay 103.

The stay 103 is an example of a second support member and supports the metal supporter 104.

The soaking pad 110 is an example of a sliding member, and is supported in contact with the metal supporter 104. Further, although the heat soaking pad 110 in this example is arranged closer to the pressure roller 107 than the metal supporter 104, the invention is not limited thereto. For example, the heat soaking pad 110 may be wound around the metal supporter 104.

The heater 101 is an example of a heat source, is placed inside the fixing belt 106, and heats the fixing belt 106. The heater 101 heats the fixing belt 106 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 a plurality of heating sources.

As the paper P passes through the nip portion N, the unfixed image 109 on the paper P is fixed to the paper P. A white arrow in the figure schematically indicates the conveyance direction of the paper P.

The reflector 102 is an example of a reflective member, and reflects heat from the heater 101 (heat source), for example, radiant heat. The reflector 102 is provided in contact with the stay 103. By using the reflector 102, the efficiency of heating the fixing belt 106 by the heater 101 can be increased.

Further, by using the reflector 102, energy consumption due to heating of the stay 103 by heat from the heater 101 can be suppressed. It also leads to improved energy efficiency and reduced recovery time. The reflector 102 preferably has a high reflectance, for example, preferably 90% or more.

In the fixing device of this embodiment, the reflector 102 and the stay 103 (second support member) are in contact, the stay 103 and the metal supporter 104 (the first support member) are in contact, and the metal supporter 104 and the soaking pad 110 ( sliding members) are in contact with each other. Therefore, the heat of the reflector 102 has a path to be transferred to the fixing belt 106 via the stay 103, the metal supporter 104, and the soaking pad 110, and it is possible to suppress the temperature of the reflector 102 from becoming high.

However, reflector 102 does not reflect all the heat, but absorbs some of the heat. Therefore, when paper is continuously passed, the temperature of the reflector 102 becomes high, and there is a problem that the reflectance decreases due to discoloration or the like due to exceeding the heat resistance temperature of the reflector 102, and there is also a problem that the reflector 102 is damaged. The inventors conducted a study and found that by having the thermal conductivity of the metal supporter 104 of 10 W/mK or more, a heat transfer path of the reflector 102 can be secured and deterioration of the reflector 102 can be prevented.

The heat transfer path in the fixing device will be explained using diagrams.
FIG. 3A is Comparative Example 1, which is not included in the present invention, and is a schematic diagram of a fixing device using a supporter 104a having a thermal conductivity of less than 10 W/mK. The black arrows in the figure schematically indicate heat transfer paths.

As shown in the figure, heat from the heater 101 is transmitted to the reflector 102, and heat from the reflector 102 is transmitted to the stay 103. In this comparative example, since the supporter 104a with low thermal conductivity is used, the heat transmitted to the stay 103 cannot be transferred to the supporter 104a or is difficult to transfer to the supporter 104a. Therefore, the reflector 102 and the stay 103 become high temperature, and the reflector 102 tends to deteriorate. Deterioration of the reflector 102 may lead to damage. Further, the heat transmitted to the reflector 102 and the stay 103 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. The metal supporter 104 in this embodiment is made of a material with a thermal conductivity of 10 W/mK or more. Therefore, the heat transmitted from the heater 101 to the stay 103 via the reflector 102 can be transferred to the metal supporter 104. Thereby, the temperature of the reflector 102 can be prevented from rising excessively, and deterioration and damage of the reflector 102 can be suppressed. Furthermore, in this embodiment, the heat transferred to the nip forming member 24 is transferred to the nip portion N, so the heat transferred to the metal supporter 104 can be effectively utilized in the nip portion N, and power consumption can be reduced. can.

The metal supporter 104 is preferably made of a metal material. The metal material used for the metal supporter 104 can be appropriately selected, and for example, a steel plate such as SECC material (electrogalvanized steel plate) or aluminum is preferable. These are preferable from the viewpoint of heat conduction and supporting strength. When SECC material or aluminum is used, there is also the advantage that it is easy to process.

The metal supporter 104 can be formed, for example, from a single plate member made of a metal material. In this case, the heat from the reflector 102 and the stay 103 can be easily transferred to the nip portion N.

The shape of the metal supporter 104 can be selected as appropriate. As shown in FIG. 2, the metal supporter 104 has the shape of a plate member bent twice in a cross section perpendicular to the axial direction of the fixing belt 106, and has two ends facing in the same direction. preferable. In other words, this shape can be said to be a U-shape.

The contact position between the metal supporter 104 and the stay 103 is preferably at the end of the metal supporter 104 in the transport direction of the paper P, as shown in the figure. By providing the contact position at the end in the paper passing direction, the metal supporter 104 can be maintained in a stable state relative to the stay 103 in the paper passing direction. For example, being in a stable state means that it is difficult to fall down.

It is preferable that the stay 103 is made of a metal material. Examples of the material of the stay 103 include SECC. This is preferable from the viewpoint of heat conduction and support strength.

The heating pad 110 can be selected as appropriate. For example, it is preferably in the form of a sheet, in which case rotation of the fixing belt 106 can be prevented from being hindered. The material of the soaking pad 110 can be selected as appropriate, for example, a steel plate such as SECC material (electrogalvanized steel plate), stainless steel, sulfur and sulfur composite free-cutting steel material (SUM material), etc. Can be used. In addition, it is preferable to use a material with good sliding properties, such as PTFE fiber, PPS fiber, etc.

A sliding member may be provided between the fixing belt 106 and the soaking pad 110. The sliding member slides on the inner circumference of the fixing belt 106.

In the example shown in FIG. 2, the metal supporter 104 and the soaking pad 110 are in contact not only on the surface facing the pressure roller 107 but also on the side surface. Although not limited thereto, the heat of the reflector 102 can be easily transferred by the metal supporter 104 and the heat soaking pad 110 being in contact with each other on the side surfaces as well. Further, in this embodiment, the length of the soaking pad 110 is longer than the length of the metal supporter 104 in the conveyance direction of the paper P.

Note that the metal supporter 104 and the soaking pad 110 may be collectively referred to as a nip forming member.

In the present embodiment, the contact surface between the metal supporter 104 (first support member) and the stay 103 (second support member) is discontinuous in the direction of the rotation axis of the fixing belt 106, and has a plurality of contact surfaces. exists. The reason why the contact surface between the metal supporter 104 and the stay 103 is discontinuous in the rotation axis direction is to make the nip surface thickness of the metal supporter 104 and the stay 103 uniform in the rotation axis direction. .

FIG. 4 is a diagram for explaining Comparative Example 2, which is not included in the present invention. FIG. 2 is a side view (or cross-sectional view) of a main part of the fixing belt 106 along the rotational axis direction.

Note that the direction of the rotation axis of the fixing belt 106 may also be referred to as the longitudinal direction. It may also be simply referred to as the rotation axis direction. Furthermore, the X-axis and Y-axis are illustrated for explanation. The X-axis and Y-axis are made to coincide with the axes in FIGS. 2 and 3. In FIGS. 2 and 3, the Z axis is also illustrated.

In the example shown in FIG. 4, the contact surface between the metal supporter 104 and the stay 103 is discontinuous in the rotation axis direction (longitudinal direction, X-axis direction). Such a shape of the metal supporter 104 is also called a getter shape or the like. Note that in order to make the nip surface thickness uniform, the height of the getter shape is made uniform. Further, in the figure, a part of the metal supporter 104 and the stay 103 are illustrated, and illustration of other members is omitted.

In this comparative example, the metal supporter 104 is made of a material with a thermal conductivity of 10 W/mK or more. It is thought that this makes it possible to effectively utilize the heat of the reflector 102 to the nip portion N, unlike Comparative Example 1. However, after the paper P is passed, a temperature difference occurs between the paper passing section and the non-paper passing section, resulting in temperature unevenness between the end side and the center side in the direction of the rotation axis.

In the paper passing section, the temperature of the fixing belt 106 decreases as the paper P passes through. Therefore, the temperature relationship in the paper passing section is as follows:
Metal supporter 104 > fixing belt 106
becomes. As a result, in the paper passing section, heat from the reflector 102 is transmitted to the fixing belt 106 via the stay 103 and the metal supporter 104, and can be effectively utilized in the nip section N.

Note that in the above temperature relationship, the soaking pad 110 is omitted, but the above size relationship does not change even if the soaking pad 110 is taken into account, so it does not matter whether the soaking pad 110 is included or not. No problem.

On the other hand, in the paper non-passage section, the temperature of the fixing belt 106 does not drop even when the paper P passes through. Therefore, the temperature relationship in the non-paper passing area is as follows:
Metal supporter 104 < fixing belt 106
becomes. As a result, in the non-sheet passing portion, excess heat in the nip portion N flows to the metal supporter 104 and the stay 103.

Therefore, in this comparative example, temperature unevenness occurs in the fixing belt 106 between the end side and the center side in the direction of the rotation axis. This may cause problems such as the fixing belt 106 being susceptible to deterioration due to the high temperature on the end side, the heat of the reflector 102 not being able to be effectively utilized on the end side, and the possibility of a fixing abnormality occurring.

As a result of the studies conducted by the present inventors, it is believed that the reason why the problem occurs as in this comparative example is that the heat conductivity is the same in the direction of the rotation axis. The diagram shown in FIG. 4 schematically shows the degree of heat transfer from the metal supporter 104 to the stay 103 without considering the concept of time such as before and after paper passing. In this comparative example, the heat transfer indicated by the black arrows in the figure has the same degree in the direction of the rotation axis. Therefore, when the paper P is actually passed through, there will be a difference in the way heat is transmitted between the paper passing section and the non-paper passing section, resulting in temperature unevenness between the end side and the center side in the direction of the rotation axis. becomes.

In contrast, in this embodiment, in order to suppress temperature unevenness, the heat conductivity between the metal supporter 104 and the stay 103 is changed in the direction of the rotation axis. As a result, for example, it is possible to provide a configuration in which the heat of the fixing belt 106 is easily dissipated on the end side, and temperature unevenness of the fixing belt 106 can be suppressed.

In this embodiment, in order to change the heat conductivity between the metal supporter 104 and the stay 103 in the direction of the rotation axis, a heat insulating member is used at the contact surface between the metal supporter 104 and the stay 103.
In this embodiment, the following steps are performed. The contact surfaces between the metal supporter 104 (first support member) and the stay 103 (second support member) are discontinuous in the direction of the rotation axis of the fixing belt 106 (fixing member), and a plurality of contact surfaces are formed. exist. A heat insulating member having heat insulating properties is provided on at least a portion of the plurality of contact surfaces, and the metal supporter 104 and the stay 103 come into contact via the heat insulating member at the location where the heat insulating member is provided.
By doing so, the heat conductivity between the metal supporter 104 and the stay 103 can be changed in the direction of the rotation axis.

FIG. 5 is a conceptual diagram for explaining this embodiment, and is a diagram having the same positional relationship as FIG. 4. In this embodiment, the heat conductivity between the metal supporter 104 and the stay 103 is changed in the direction of the rotation axis, and the heat conductivity is lowered on the center side. By lowering the heat conductivity at the center, the heat conductivity at the ends is relatively improved. Thereby, the heat of the fixing belt 106 on the end side can be easily dissipated, and temperature unevenness of the fixing belt 106 can be suppressed.

In the example shown in FIG. 5, the heat conductivity between the metal supporter 104 and the stay 103 gradually decreases from the end toward the center, but the present invention is not limited to this. For example, it may be divided into an end side and a center side, and the heat conductivity at the end side is made larger than the heat conductivity at the center side. In addition to this, for example, a structure may be adopted in which the sheet is divided into a non-paper passing section and a paper passing section, and the heat conductivity in the non-paper passing section is made greater than the heat conductivity in the paper passing section. In addition, when simply describing heat conductivity, unless otherwise specified, it represents the heat conductivity between the metal supporter 104 and the stay 103.

The division into the end side and the center side is not particularly limited and can be changed as appropriate. The paper non-passing portion may be the end portion, and the paper passing portion may be the center, but the present invention is not limited thereto.

FIG. 6 is a diagram for explaining an example included in this embodiment. The method of changing the heat conductivity in the direction of the rotation axis can be selected as appropriate. An example of this is shown in FIGS. 6(A) to 6(C). Note that FIG. 6 is a diagram having the same positional relationship as FIG. 5.

As shown in FIG. 6, the heat insulating member is preferably selected such that the heat conductivity between the metal supporter 104 and the stay 103 is lower on the center side in the rotation axis direction of the fixing belt 106 than on the end side. Thereby, the heat of the fixing belt 106 on the end side can be easily dissipated, and temperature unevenness of the fixing belt 106 can be suppressed.

There is no particular restriction on selecting a heat insulating member so that the heat conductivity between the metal supporter 104 and the stay 103 is lower on the center side in the rotational axis direction of the fixing belt 106 than on the end side. can do. For example, any means may be used, such as the number, thickness, area, and heat conductivity of the heat insulating members.

In FIG. 6A, a heat insulating member 111 is provided on the contact surface between the metal supporter 104 and the stay 103 on the center side in the direction of the rotation axis of the fixing belt 106, and on the contact surface on the end side. A heat insulating member 111 is not provided. At the location where the heat insulating member 111 is provided, the metal supporter 104 and the stay 103 are in contact with each other via the heat insulating member 111.

By doing so, the heat conductivity schematically indicated by the black arrows in the figure is such that the heat conductivity on the center side is smaller than the heat conductivity on the end side. Thereby, the heat of the fixing belt 106 on the end side can be easily dissipated, and temperature unevenness of the fixing belt 106 can be suppressed.

The heat insulating member 111 may be any member as long as it has heat insulating properties, and can be appropriately selected without particular limitation. The heat insulating properties of the heat insulating member 111 include not only the case where heat transfer between the metal supporter 104 and the stay 103 is completely cut off, but also the case where heat transfer occurs between the metal supporter 104 and the stay 103 via the heat insulating member 111. . When the heat insulating member 111 is provided, heat transfer becomes more difficult than when the heat insulating member 111 is not provided.

The material for the heat insulating member 111 is preferably a material that has a lower thermal conductivity than either the metal supporter 104 or the stay 103. Examples include PEEK material (thermal conductivity 1.3 W/mK) and LCP material (thermal conductivity 0.44 W/mK). Among these, it is preferable to use a material having a power of 0.18 W/mK or less. An example of such a material is PI material. Further, when the heat insulating member 111 is made of a material having a lower thermal conductivity than either the metal supporter 104 or the stay 103, there is an advantage that heat transfer between the stay 103 and the metal supporter 104 can be delayed.

In FIG. 6B, different types of heat insulating members 111 and 112 are provided, and the heat insulating property of the heat insulating member 111 provided on the center side in the direction of the rotation axis of the fixing belt 106 is different from that of the heat insulating member 111 provided on the end side. This is greater than the heat insulating property of the heat insulating member 112. As a result, the black arrows at the ends are longer than the black arrows at the center.

In the illustrated example, the heat insulating properties of the heat insulating member 111 on the center side are greater than the heat insulating properties of the heat insulating members 112 on the end sides. In order to do this, for example, the materials of the heat insulating member 111 and the heat insulating member 112 are appropriately selected.

In FIG. 6C, the thickness of the heat insulating member 111 is changed, and the thickness of the heat insulating member 111 is greater on the center side in the direction of the rotation axis of the fixing belt 106 than on the end side. As the thickness of the heat insulating member 111 increases, the heat transfer between the metal supporter 104 and the stay 103 decreases. Thereby, the heat of the fixing belt 106 on the end side can be easily dissipated, and temperature unevenness of the fixing belt 106 can be suppressed.

In the example shown in FIG. 6(C), the thickness of the heat insulating member 111 gradually decreases from the end toward the center, but the present invention is not limited to this. For example, divide it into the end side and the center side,
The thickness of the heat insulating member 111 on the center side may be greater than that on the end portions. In addition to this, for example, the structure may be such that it is divided into a paper non-passing part and a paper passing part, and the thickness of the heat insulating member 111 in the paper passing part is made larger than the thickness in the paper non-passing part.

Note that FIGS. 6(A) to 6(C) may be combined as appropriate. For example, the thickness of the heat insulating members 111 and 112 may be changed in FIG. 6(B). Similarly, different types of heat insulating members may be used in FIG. 6(C). Furthermore, the areas of the contact surfaces between the metal supporter 104 and the stay 103 may be the same or different.

As described above, according to the present invention, the reflector 102 has a path through which the heat of the reflector 102 is transferred to the fixing belt 106 on the nip portion N side via the stay 103 and the metal supporter 104. It can suppress high temperatures. Further, since the heat of the reflector 102 can be effectively used in the nip portion N, there are also advantages of suppressing power consumption and saving energy. Further, since the heat conductivity between the metal supporter 104 and the stay 103 differs in the direction of the rotation axis of the fixing belt 106, temperature unevenness of the fixing belt 106 at the nip portion N can be suppressed. According to the present invention, heat from the reflective member is easily transferred to the fixing member on the nip portion side via the support member, etc., and high temperature and deterioration of the reflective member can be suppressed, and temperature unevenness of the fixing member at the nip portion can be suppressed. can be suppressed.

Here, a supplementary explanation of the present invention will be given. Here, the heat transfer in FIGS. 3B and 5 will be mainly explained.
As explained with reference to FIG. 3B, since the heat of the reflector 102 has a heat transfer path via the stay 103 and the metal supporter 104 to the fixing belt 106 on the nip N side, it is possible to prevent the reflector 102 from becoming high temperature. It can be suppressed. The movement of heat is schematically shown by the black arrows in the figure. Heat transfer as shown in FIG. 3B occurs not only when heating is performed by the heater 101 but also when the reflector 102 is at a high temperature.
On the other hand, in FIG. 5, the movement of heat mainly from the metal supporter 104 to the stay 103 is schematically shown with black arrows. The heat transfer as shown in FIG. 5 is not particularly limited, but is assumed to occur after the recording medium has passed through the nip portion N (also referred to as paper passing). After the paper passes, a difference in temperature occurs between the paper passing section and the non-paper passing section of the fixing belt 106, and the temperature decreases in the paper passing section, while the temperature does not decrease and becomes high in the non-paper passing section. Therefore, as described above, by configuring the fixing belt 106 to have a configuration in which the heat conductivity is lowered at the center side and the heat conductivity is increased at the end sides, the heat at the end sides of the fixing belt 106 can be released.

At this time, heat transfer as shown in FIG. 3B and heat transfer as shown in FIG. Heat transfer occurs from 103 to metal supporter 104 to nip portion N. In the non-sheet passing portion, heat transfer occurs (from the fixing belt 106 to the metal supporter 104 to the stay 103) as shown in FIG. Therefore, it is possible to suppress the temperature rise on the end side of the fixing belt 106.

Further, in the present invention, a heat insulating member is provided on at least a portion of the contact surface between the metal supporter 104 and the stay 103. Thereby, heat can be transferred as shown in FIG. 5, and temperature unevenness of the fixing belt 106 can be reduced. On the other hand, this heat insulating member acts to prevent heat transfer as shown in FIG. 3B. However, the metal supporter 104 receives heat from the high-temperature fixing belt 106 in the non-sheet passing portion, and the heat is transferred to the longitudinal direction of the metal supporter 104 and the stay. This heat can also be transferred to the nip portion at the paper passing portion of the metal supporter 104, and temperature unevenness of the fixing belt 106 can be suppressed.

Next, other embodiments of the present invention will be described. Description of matters similar to those in the above embodiment will be omitted.

FIG. 7 is a sectional view of the fixing device 20 of this embodiment, and FIG. 8 is an exploded perspective view of the fixing device 20 of this embodiment.
The fixing device 20 of this embodiment, like the above embodiment, includes, for example, a heater 101, a reflector 102, a stay 103, a metal supporter 104, a fixing belt 106, a pressure roller 107, a belt support member 108, and a soaking pad 110. We are prepared.

The fixing belt 106 is an endless belt having a predetermined inner diameter and a width longer than the width of the paper P. The fixing belt 106 is made of a flexible material, and includes, for example, a base layer, an elastic layer provided on the outer circumference of the base layer, and a release layer provided on the outer circumference of the elastic layer. are doing.

The base material layer is made of metal such as SUS or Ni. The elastic layer is made of silicone rubber or the like. The release layer is formed of a PFA tube or the like. Both ends of the fixing belt 106 are rotatably supported by the fixing housing.

A stay 103 passes through the lower part of the hollow portion of the fixing belt 106 . The stay 103 is a channel-shaped member that is longer than the length in the width direction X of the fixing belt 106 and has an open top surface. Both ends of the stay 103 are supported by a fixing housing. Three positioning holes 120 are formed in the bottom plate of the stay 103 at predetermined intervals in the width direction X. A reflector 102 is supported on the upper surface of the stay 103.

The heater 101 (for example, a halogen heater) has a length equivalent to the length of the fixing belt 106 along the rotation axis direction. The heater 101 is disposed above the hollow portion of the fixing belt 106 (above the stay 103), and both ends thereof are supported by the fixing housing.

The heater 101 radiates radiant heat to the inner peripheral surface of the fixing belt 106 (mainly a portion slightly narrower than the upper half circumference) to heat the fixing belt 106. Radiant heat emitted downward from the heater 101 is reflected onto the inner peripheral surface of the fixing belt 106 by the reflector 102. Heater 101 is controlled by a control section.

The pressure roller 107 has a core metal, an elastic layer provided on the outer peripheral surface of the core metal, and a mold release layer provided on the outer peripheral surface of the elastic layer. The elastic layer is made of silicone rubber or the like. The release layer is formed of a PFA tube or the like.

The pressure roller 107 is disposed below the fixing belt 106 and supported by the fixing housing. Pressure roller 107 contacts the outer peripheral surface of fixing belt 106 to form a nip portion N between pressure roller 107 and fixing belt 106 . The pressure roller 107 is connected to, for example, a motor and driven to rotate. The motor is controlled by, for example, a control unit. When the pressure roller 107 rotates counterclockwise in FIG. 8, the fixing belt 106 follows the pressure roller 107 and rotates in a clockwise direction opposite to the rotation direction of the pressure roller 107. As a result, the paper P passes through the nip portion N.

The nip forming member includes a metal supporter 104 and a soaking pad 110 wrapped around and fixed to the metal supporter 104.

The metal supporter 104 is a flat, substantially rectangular parallelepiped member that is long in the width direction X of the fixing belt 106, and is made of, for example, a metal material. On the upper surface of the metal supporter 104, a plurality (18) of protrusions 121, a plurality (7) of fixing pins 123, and a plurality (3) of positioning pins 125 are erected at predetermined positions. has been done.

The soaking pad 110 is a rectangular sheet-like member having a width equal to the width of the metal supporter 104 and a length that can be wrapped around the metal supporter 104, and is formed by knitting PTFE fibers and PPS fibers, for example. ing.

The heat equalizing pad 110 is wrapped around the metal supporter 104, and both ends thereof are overlapped on the upper surface of the metal supporter 104. A through hole 131, a fixing hole 133, and a positioning hole 135 into which the protrusion 121, fixing pin 123, and positioning pin 125 of the metal supporter 104 can fit, respectively, are formed at both ends.

The nip forming member is positioned on the stay 103 by fitting the positioning pin 125 of the metal supporter 104 into the positioning hole 120 of the stay 103.

A lubricant (oil, grease) may be applied to the soaking pad 110. In this case, the soaking pad 110 contacts the inner circumferential surface of the fixing belt 106 via a lubricant.

In this embodiment, the protrusion 121 of the metal supporter 104 and the stay 103 are in contact with each other. Therefore, also in this embodiment, the contact surface between the metal supporter 104 and the stay 103 is discontinuous in the direction of the rotation axis of the fixing belt 106, and a plurality of contact surfaces exist.

Note that although the heat insulating member is not shown in FIGS. 7 and 8, the structure may be similar to that of the above embodiment. Further, when the thickness of the heat insulating member is changed in the direction of the rotation axis, for example, the height of the protrusion 121 is also changed in the direction of the rotation axis, so that the metal supporter 104 and the stay 103 can contact each other at a uniform height.

Aspects of the present invention are, for example, as follows.
<1> A flexible and rotatable endless fixing member;
a sliding member that slides on the inner periphery of the fixing member;
a pressure member that is provided opposite to the sliding member with the fixing member in between and forms a nip portion with the fixing member;
a heat source provided inside the fixing member and heating the fixing member;
a first support member that supports the sliding member;
a second support member that supports the first support member;
a reflective member that is in contact with the second support member and reflects heat from the heating source;
The first support member is made of a material with a thermal conductivity of 10 W/mK or more,
The contact surface between the first support member and the second support member is discontinuous in the direction of the rotation axis of the fixing member, and a plurality of contact surfaces are present,
A heat insulating member having a heat insulating property is provided on at least a portion of the plurality of contact surfaces, and the first support member and the second support member have the heat insulating property A fixing device characterized by contacting through a member.
<2> The heat insulating member is selected such that the heat conductivity between the first support member and the second support member is lower on the center side in the rotation axis direction of the fixing member than on the end side. The fixing device according to feature <1>.
<3> The heat insulating member is provided on the contact surface on the center side in the direction of the rotation axis of the fixing member, and is not provided on the contact surface on the end side. <1> or <2> ＞The fixing device described in ＞.
<4> Different types of the heat insulating members are provided, and the heat insulating property of the heat insulating member provided on the center side in the direction of the rotation axis of the fixing member is equal to the heat insulating property of the heat insulating member provided on the end side. The fixing device according to any one of <1> to <3>, wherein the fixing device is larger than the above.
<5> The fixing device according to any one of <1> to <4>, wherein the thickness of the heat insulating member is greater on the center side in the rotation axis direction of the fixing member than on the end side.
<6> The fixing device according to any one of <1> to <5>, wherein the first support member is made of a metal material.
<7> The fixing device according to any one of <1> to <6>, wherein the second support member is made of a metal material.
<8> The fixing device according to any one of <1> to <7>, wherein the sliding member is sheet-shaped.
<9> An image forming apparatus comprising the fixing device according to any one of <1> to <8>.

20 Fixing device 101 Heater 102 Reflector 103 Stay 104 Metal supporter 106 Fixing belt 107 Pressure roller 108 Belt support member 109 Unfixed image 110 Soaking pad

Japanese Patent Application Publication No. 2015-111243 Japanese Patent Application Publication No. 2021-110805 Japanese Patent Application Publication No. 2016-90764

Claims (9)

a flexible and rotatable endless fixing member;
a sliding member that slides on the inner periphery of the fixing member;
a pressure member that is provided opposite to the sliding member with the fixing member in between and forms a nip portion with the fixing member;
a heat source provided inside the fixing member and heating the fixing member;
a first support member that supports the sliding member;
a second support member that supports the first support member;
a reflective member that is in contact with the second support member and reflects heat from the heating source;
The first support member is made of a material with a thermal conductivity of 10 W/mK or more,
The contact surface between the first support member and the second support member is discontinuous in the direction of the rotation axis of the fixing member, and a plurality of contact surfaces are present,
A heat insulating member having a heat insulating property is provided on at least a portion of the plurality of contact surfaces, and the first support member and the second support member are provided with the heat insulating member at the location where the heat insulating member is provided A fixing device characterized by contacting through a member. The heat insulating member is selected such that heat transfer between the first support member and the second support member is lower on the center side in the rotation axis direction of the fixing member than on the end side. The fixing device according to claim 1. The fixing device according to claim 1, wherein the heat insulating member is provided on the contact surface on the center side of the fixing member in the direction of the rotation axis, and is not provided on the contact surface on the end side. Different types of the heat insulating members are provided, and the heat insulating property of the heat insulating member provided on the center side in the direction of the rotational axis of the fixing member is greater than the heat insulating property of the heat insulating member provided on the end side. The fixing device according to claim 1, characterized in that: 2. The fixing device according to claim 1, wherein the thickness of the heat insulating member is greater on the center side in the rotational axis direction of the fixing member than on the end side. The fixing device according to claim 1, wherein the first support member is made of a metal material. The fixing device according to claim 1, wherein the second support member is made of a metal material. The fixing device according to claim 1, wherein the sliding member has a sheet shape. An image forming apparatus comprising the fixing device according to claim 1.