JP2020126211A - Fixing device and image forming apparatus - Google Patents

Abstract

To ensure a wide range where heat can be directly applied to a fixing member to improve heat energy efficiency.SOLUTION: A fixing device comprises: a cylindrical fixing member 21; an opposing member 22 that is arranged to be opposite to an outer peripheral surface of the fixing member 21; a heating member 23 that is arranged inside the fixing member 21; a nip forming member 24 that is arranged inside the fixing member 21 and sandwiches the fixing member 21 with the opposing member 22 to form a nip part N; and structures 25, 26 that have opposing surfaces 250, 260 on a cross section intersecting with a width direction of the fixing member 21, inside the fixing member 21, at an upstream side and a downstream side in a recording medium conveyance direction with the heating member 23 interposed therebetween. In the structures 25, 26, an interval between the opposing surfaces 250, 260 is increased from a side facing the nip part N toward the opposite side thereto.SELECTED DRAWING: Figure 7

Description

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

In an electrophotographic image forming apparatus such as a copying machine or a printer, a recording medium such as a sheet on which an unfixed image is formed is conveyed between members (nip portions) such as rollers and belts that face each other to form a recording medium. 2. Description of the Related Art A fixing device is known which applies heat to a toner to fix an unfixed image.

As a fixing device of this type, for example, in JP-A-2009-93141 below, a nip forming unit that forms a nip portion inside a belt unit, or a nip forming unit and a belt unit are heated. A fixing device in which a heating unit, a support unit that supports the nip forming unit, and the like are arranged is disclosed.

By the way, in order to improve the thermal efficiency of the fixing device to improve the fixing property and reduce the energy consumption, it is necessary to secure a wide range in which the heat generated from the heating member can be directly applied to the fixing member such as the belt unit. desirable.

However, in a structure in which various structures such as a nip forming member and a supporting member supporting the nip forming member are arranged inside the fixing member formed in a tubular shape, in addition to the heating member, Since heat is shielded by surrounding structures, the range in which heat can be directly applied from the heating member to the fixing member is limited. In particular, in a small-sized fixing device using a fixing member having a small diameter, the distance between the heating member and the structures arranged around the heating member is narrowed, so that it is possible to secure a range in which heat can be directly applied to the fixing member. The situation is becoming increasingly difficult.

In order to solve the above problems, the present invention provides a tubular fixing member, a facing member arranged to face the outer peripheral surface of the fixing member, a heating member arranged inside the fixing member, and A nip forming member that is arranged inside the fixing member and forms a nip portion with the facing member sandwiching the fixing member, and a cross section that intersects the width direction of the fixing member, inside the fixing member, A fixing device comprising: a structure having facing surfaces on the upstream side and the downstream side in the recording medium conveyance direction with a heating member interposed therebetween, wherein the structure extends from the nip side toward the opposite side. It is characterized in that the interval between the facing surfaces is increased.

According to the present invention, the distance between the facing surfaces of the structure disposed inside the fixing member increases from the nip portion side to the opposite side, so that the fixing member can be efficiently heated. It is possible to improve the thermal efficiency.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 4 is a side sectional view of the fixing device. FIG. 3 is a perspective sectional view of the fixing device. FIG. 3 is a front cross-sectional view of the fixing device. It is a perspective view of a belt support member. It is a perspective view which shows the modification of a belt support member. FIG. 4 is a side sectional view of the fixing device. It is a figure which shows the modification of a stay. It is a figure which shows the other modification of a stay. It is a perspective view which shows the structure by the side of the end part of the stay supported by the side plate. It is a perspective view which shows the modification of a stay. FIG. 6 is a side sectional view of a fixing device according to a second embodiment of the present invention. FIG. 6 is a side sectional view of a fixing device according to a third exemplary embodiment of the present invention. FIG. 6 is a side sectional view of a fixing device according to a fourth exemplary embodiment of the present invention. It is a side sectional view of a fixing device concerning a 5th embodiment of the present invention. It is a perspective view which shows the example which formed the through-hole in an elliptical shape. It is a figure which compares and shows a rectangular through-hole and an elliptical through-hole. FIG. 16 is a cross-sectional view of the stay, the reflecting member, and the halogen heater seen from above or below in FIG. 15. It is a perspective view of a stay concerning a 6th embodiment of the present invention. It is a top view of the nip formation member concerning a 7th embodiment of the present invention. It is an end perspective view of a nip formation member concerning a 7th embodiment of the present invention. It is a figure for explaining operation of the nip formation member concerning a 7th embodiment of the present invention. It is a figure which shows the example which changed the inclination angle of the inclined surface. It is a figure which shows the example which inclined the recessed part with respect to the belt rotation direction. FIG. 3 is a diagram illustrating an example of a fixing device that conveys a sheet in a vertical direction. FIG. 6 is a side sectional view of a fixing device according to a first comparative example. FIG. 6 is a side sectional view of a fixing device according to a second comparative example.

Hereinafter, the present invention will be described with reference to the accompanying drawings. In each of the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as far as possible to distinguish them from each other. Omit it.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. First, the overall configuration and operation of the image forming apparatus will be described with reference to FIG.

The image forming apparatus 1 shown in FIG. 1 is an electrophotographic monochrome laser printer. In addition to the printer, the present invention may be a copying machine, a facsimile, or a multifunction machine having any two or three functions of these. The color image forming apparatus is not limited to the monochrome image forming apparatus.

As shown in FIG. 1, in the image forming apparatus 1, an image forming unit 2 that forms an image, a recording medium supply unit 3 that supplies a sheet P as a recording medium, and an image is transferred to the supplied sheet P. A transfer unit 4, a fixing device 5 that fixes the image transferred onto the paper P, and a discharge unit 6 that discharges the paper P on which the image has been fixed are provided.

The image forming unit 2 is a drum-shaped photoconductor 7, a charging roller 8 as a charging unit that charges the surface of the photoconductor 7, and a latent image forming unit that exposes the surface of the photoconductor 7 to form a latent image. Exposure device 9, a developing roller 10 as a developing unit that supplies toner (developer) to the surface of the photoconductor 7 to make a latent image visible, and a cleaning unit that cleans the surface of the photoconductor 7. And a blade 11.

When an instruction to start the printing operation is given, in the image forming unit 2, the photoconductor 7 starts rotating, and the charging roller 8 charges the surface of the photoconductor 7 to a uniform high potential. Next, the exposure device 9 exposes the surface of the photoconductor 7 based on the image information of the document read by the document reading device or the print information instructed to print from the terminal, so that the potential of the exposed portion decreases. As a result, an electrostatic latent image is formed. Then, toner is supplied from the developing roller 10 to this electrostatic latent image, and a toner image is formed on the photoconductor 7.

The toner image formed on the photoconductor 7 is transferred to the paper P at the transfer nip between the transfer roller 15 arranged in the transfer unit 4 and the photoconductor 7. The paper P is supplied from the recording medium supply unit 3. In the recording medium supply unit 3, the paper P accommodated in the paper feed cassette 12 is fed by the paper feed roller 13 one by one. The fed paper P is conveyed to the transfer nip by the timing roller pair 14 in time with the toner image on the photoconductor 7. Then, the toner image on the photoconductor 7 is transferred to the paper P at the transfer nip. Further, after the transfer of the toner image, the toner remaining on the photoconductor 7 is removed by the cleaning blade 11.

The sheet P on which the toner image is transferred is conveyed to the fixing device 5. Then, in the fixing device 5, the toner image is fixed on the paper P by being heated and pressed when the paper P passes between the fixing belt 21 and the pressure roller 22. After that, the paper P is conveyed to the discharge unit 6 and discharged to the outside of the apparatus by the paper discharge roller pair 16, and a series of printing operations is completed.

Next, the configuration of the fixing device according to the first exemplary embodiment of the present invention will be described in detail with reference to FIGS.

2 is a side sectional view of the fixing device, FIG. 3 is a perspective sectional view of the fixing device, and FIG. 4 is a front sectional view of the fixing device. 5 is a perspective view of a belt support member that supports the fixing belt, and FIG. 6 is a perspective view showing a modified example of the belt support member.

As shown in FIG. 2, the fixing device 5 includes a fixing belt 21, a pressure roller 22, a halogen heater 23, a nip forming member 24, a stay 25, a reflecting member 26, a guide member 27, and a temperature sensor. 28 is provided.

The fixing belt 21 is a cylindrical fixing member that fixes the unfixed image T on the paper P, and is arranged on the unfixed image carrying surface side of the paper P. In the present embodiment, the fixing belt 21 is made of a metal material such as nickel or SUS, or a base material on the inner peripheral side formed of a resin material such as polyimide, PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer), An endless belt (including a film) including a release layer on the outer peripheral side formed of PTFE (polytetrafluoroethylene) or the like. In addition, an elastic layer formed of a rubber material such as silicone rubber, foamed silicone rubber, or fluororubber may be interposed between the base material and the release layer. If the thickness of this elastic layer is set to about 100 μm, when the unfixed image (unfixed toner) is crushed and fixed, the elastic deformation of the elastic layer can absorb minute irregularities on the belt surface, resulting in uneven gloss. Can be avoided. Further, in this embodiment, from the viewpoint of reducing the heat capacity of the fixing belt 21, a thin belt having a small diameter is adopted as the fixing belt 21. Specifically, the thickness of each of the base material and the release layer constituting the fixing belt 21 is set in the range of 20 to 50 μm and 10 to 50 μm, and the thickness of the entire fixing belt 21 is set to 1 mm or less. doing. Further, when the fixing belt 21 has an elastic layer, the thickness of the elastic layer may be set to 100 to 300 μm. In order to further reduce the heat capacity, the thickness of the fixing belt 21 as a whole is preferably 0.2 mm or less, more preferably 0.16 mm or less. Further, in the present embodiment, the diameter of the fixing belt 21 is set to 20 to 40 mm. The diameter of the fixing belt 21 is preferably 30 mm or less.

The pressure roller 22 is a facing member arranged to face the outer peripheral surface of the fixing belt 21. In the present embodiment, the pressure roller 22 includes a cored bar, an elastic layer made of foamable silicone rubber or fluororubber provided on the surface of the cored bar, and PFA or PTFE provided on the surface of the elastic layer. And a release layer. Further, although the pressure roller 22 is a solid roller in the present embodiment, it may be a hollow roller. In the case of a hollow roller, a heating member such as a halogen heater can be arranged inside the pressure roller 22. The elastic layer of the pressure roller 22 may be solid rubber. However, when a heating member is not arranged inside, it is desirable to use sponge rubber for the elastic layer to enhance the heat insulating property of the pressure roller 22. As a result, the heat of the fixing belt 21 is less likely to be taken by the pressure roller 22, and the thermal efficiency of the fixing belt 21 is improved.

Further, the pressure roller 22 is configured to be rotationally driven in a direction indicated by an arrow A in FIG. 2 by a driving source provided in the main body of the image forming apparatus. On the other hand, the fixing belt 21 is driven and rotated by the rotation of the pressure roller 22, which is accompanied by the rotation of the pressure roller 22. When the sheet P on which the unfixed image T is transferred is conveyed between the fixing belt 21 and the pressure roller 22 (nip portion N), the sheet P is conveyed by the rotating fixing belt 21 and the pressure roller 22. Pass through the nip portion N. At this time, the unfixed image T is fixed on the paper P by applying heat and pressure to the paper P.

Further, the pressure roller 22 and the fixing belt 21 are configured to approach and separate from each other. In the unlikely event that the paper is jammed in the nip portion N, the pressure roller 22 and the fixing belt 21 are separated from each other and the nip portion N is opened, so that maintenance work such as jam processing of the jammed paper can be performed. Is. The pressure roller 22 and the fixing belt 21 may be configured such that one of them is moved toward and away from the other, or both of them may be moved toward and away from each other.

The halogen heater 23 is a heating member that is disposed inside the fixing belt 21 and emits infrared light to heat the fixing belt 21 and the nip forming member 24 by radiant heat. Instead of the halogen heater 23, a carbon heater, a ceramic heater, or the like can be used as the heating member.

The nip forming member 24 forms the nip portion N by sandwiching the fixing belt 21 with the pressure roller 22. Specifically, the nip forming member 24 is arranged inside the fixing belt 21 in a longitudinal shape across the belt width direction, and has a flat plate-like nip forming portion 24 a that contacts the inner peripheral surface of the fixing belt 21, and a nip forming member. It has a pair of bent portions 24b that are bent from both ends of the portion 24a in the belt rotation direction B to the side opposite to the pressure roller 22 side. The pressure roller 22 is pressed toward the nip forming member 24 by a pressure unit such as a spring, so that the pressure roller 22 and the fixing belt 21 come into contact with each other, and a nip portion N is formed therebetween.

The nip forming surface 24 c of the nip forming portion 24 on the fixing belt 21 side is in direct contact with the inner peripheral surface of the fixing belt 21. Therefore, when the fixing belt 21 rotates, the fixing belt 21 slides on the nip forming surface 24c. In order to improve wear resistance and slidability of the nip forming surface 24c, an alumite treatment or a fluororesin-based material may be applied to the nip forming surface 24c. Further, in order to secure the slidability over time, a lubricant such as fluorine grease may be applied to the nip forming surface 24c. In the present embodiment, the nip forming surface 24c has a flat surface shape, but it may have a concave shape or another shape. For example, when the nip forming surface 24c has a concave shape that is recessed toward the side opposite to the pressure roller 22 side, the outlet of the nip portion N is closer to the pressure roller 22 and the separation of the sheet from the fixing belt 21 is reduced. improves.

The nip forming member 24 is made of a material having a thermal conductivity higher than that of the stay 25. For example, the material of the nip forming member 24 is preferably copper (thermal conductivity: 398 W/mk), aluminum (thermal conductivity: 236 W/mk), or the like. As described above, since the nip forming member 24 is formed of a material having a high thermal conductivity, the radiant heat from the halogen heater 23 is absorbed by the nip forming member 24 and efficiently transmitted to the fixing belt 21. For example, by setting the thickness of the nip forming member 24 to 1 mm or less, the heat transfer time from the nip forming member 24 to the fixing belt 21 can be shortened, and the rising speed of the fixing device 5 can be increased. On the contrary, when the thickness of the nip forming member 24 is set to be larger than 1 mm and 5 mm or less, the heat storage property of the nip forming member 24 can be enhanced.

The stay 25 is a support member that supports the nip forming member 24 against the pressure of the pressure roller 22. In this embodiment, a pair of flat plate-shaped stays 25 are arranged on both sides of the halogen heater 23. Similar to the nip forming member 24, each stay 25 is arranged inside the fixing belt 21 in a longitudinal shape across the belt width direction, and contacts both end sides of the nip forming member 24 in the belt rotation direction B, so that the nip is formed. It supports the forming member 24. As described above, since the nip forming member 24 is supported by each stay 25, the bending of the nip forming member 24 in the pressurizing direction is suppressed, and the nip portion N having a uniform width over the longitudinal direction is obtained. .. The stay 25 is preferably formed of an iron-based metal material such as SUS or SECC in order to ensure its rigidity. The thickness of the stay 25 is preferably 2 mm or less, more preferably 1.2 to 1.6 mm.

The reflecting member 26 is disposed inside the fixing belt 21 so as to face the halogen heater 23, and radiant heat (infrared light) emitted from the halogen heater 23 is provided inside the fixing belt 21 on the nip forming member 24 side and above. It reflects on the peripheral surface. In the present embodiment, the pair of reflecting members 26 are arranged on both sides of the halogen heater 23, like the stay 25. Each reflecting member 26 has a reflecting portion 26a formed in a convex curved shape and a pair of bent portions 26b provided at both ends of the reflecting portion 26a. Each bent portion 26b is engaged with each of the end surface 25a of the stay 25 on the nip N side and the end surface 25b on the opposite side. As a result, the reflecting member 26 is supported by the stay 25.

The reflecting portion 26a is formed in a convex curved shape so as to project most at a position facing the halogen heater 23 or in the vicinity thereof. Therefore, the infrared light radiated to the reflecting portion 26a is reflected by the reflecting portion 26a so as to be divided into the upper side and the lower side in FIG. The infrared light reflected upward is applied to the fixing belt 21 through the upper opening formed between the stays 25 and the reflecting members 26. On the other hand, the infrared light reflected downward is applied to the nip forming member 24 through the lower opening formed between the stays 25 and the reflecting members 26. Further, a part of the infrared light emitted from the halogen heater 23 is not reflected by the reflecting portion 26a and passes through the upper and lower openings formed between the stay 25 and the reflecting member 26 to form the fixing belt 21 or the nip. The member 24 is directly irradiated. In this way, since the infrared light emitted from the halogen heater 23 is reflected by the reflection member 26 and applied to the fixing belt 21 or the nip forming member 24, or is directly irradiated, the fixing belt 21 and the nip forming member 24 are irradiated with the infrared light. The forming member 24 is effectively heated by the reflected light and the direct irradiation light.

Further, since the infrared light is distributed to the upper side and the lower side in FIG. 2 by the reflecting member 26, the number of times the infrared light is reflected between the reflecting members 26 can be reduced, and the thermal energy of the infrared light by repeating the reflection can be reduced. Can be suppressed. Further, since it is possible to prevent the reflecting member 26 itself from being heated, even if the halogen heater 23 is continuously used for a long period of time, it is possible to avoid a decrease in reflectance due to the reflecting member 26 becoming hot and discolored, and high heating. It is possible to maintain efficiency.

Further, since the reflecting member 26 is interposed between the halogen heater 23 and the stay 25, it also has a function of blocking the irradiation of infrared light from the halogen heater 23 to the stay 25. As a result, wasteful consumption of heat energy due to heating of the stay 25 is suppressed. Further, in this embodiment, since the reflecting portion 26a is formed in a convex curved surface, an air layer (gap) is present between the stay 25 and the reflecting portion 26a, and the heat insulating effect of this air layer causes Heat transfer to the stay 25 is further suppressed.

The surface of the reflecting member 26, especially on the side of the halogen heater 23, is mirror-finished or surface-treated to increase the reflectance. In the present embodiment, the reflectance is measured using a spectrophotometer (UVH-IR spectrophotometer UH4150 manufactured by Hitachi High-Tech Science Co., Ltd.), and the incident angle at the time of measurement is 5°. Generally, the halogen heater has a different color temperature depending on the application, but a heater having a color temperature of about 2500 K is used for heating the fixing device. The reflectance of the reflecting member 26 is preferably 70% or more with respect to the wavelength of the halogen heater 23 having high emission intensity, specifically, the wavelength of 900 to 1600 nm, and more preferably the wavelength of 1000 to 1300 nm.

Further, the stay 25 may have the functions of reflecting and insulating the reflecting member 26. For example, the stay 25 can also be configured to have the function of the reflecting member 26 by performing heat insulation treatment or mirror surface treatment on the inner surface of the stay 25 (the surface on the halogen heater 23 side). In this case, the reflecting member 26 separate from the stay 25 can be omitted. Further, the reflectance of the stay 25 when the stay 25 is mirror-finished is preferably the same as that of the reflecting member 26.

The guide member 27 contacts the inner peripheral surface of the rotating fixing belt 21 and guides the fixing belt 21. In the present embodiment, the guide member 27 is provided on both the upstream side and the downstream side of the nip portion N in the belt rotation direction B. The guide member 27 has a mounting portion 27 a fixed to the stay 25 and the like, and a curved guide portion 27 b that comes into contact with the inner peripheral surface of the fixing belt 21. As shown in FIG. 3, a plurality of ribs (projections) 27c are provided on the surface (guide surface) of the guide portion 27b on the fixing belt 21 side at equal intervals in the belt width direction. By the fixing belt 21 being guided along the guide surface having the plurality of ribs 27c, the fixing belt 21 can smoothly rotate without being greatly deformed.

The temperature sensor 28 is arranged to face the outer peripheral surface of the fixing belt 21, and detects the temperature of the fixing belt 21. In the present embodiment, the temperature sensors 28 are arranged at two positions on the fixing belt 21, that is, the center portion in the belt width direction and the one end portion side. The surface temperature of the fixing belt 21 is detected by the temperature sensor 28, and the output of the halogen heater 23 is controlled based on the detection result, so that the temperature of the fixing belt 21 is controlled to a desired temperature (fixing temperature). To be done. Further, the temperature sensor 28 may be a contact type or a non-contact type. As the temperature sensor 28, a known temperature sensor such as a thermopile, a thermostat, a thermistor, or an NC sensor can be applied.

As shown in FIG. 4, cylindrical belt support members 30 are inserted into both ends of the fixing belt 21. As described above, since the belt supporting members 30 are inserted into both ends of the fixing belt 21, the fixing belt 21 basically has no tension in the circumferential direction with respect to the fixing belt 21 when it is not rotating. It is supported by the so-called free belt system.

As shown in FIGS. 3 to 5, the belt supporting member 30 is fixed inside the fixing belt 21 by contacting with a C-shaped supporting portion 30 a that supports the fixing belt 21 and an end surface of the fixing belt 21. And a flange-shaped restricting portion 30b that restricts the movement (deviation) of the belt 21 in the width direction. Further, the support portion 30a may have a tubular shape that is continuous over the entire circumference, as in the example shown in FIG. Each belt support member 30 is fixed to a pair of side plates 31 (see FIG. 4), which are frame members constituting the fixing device 5. Further, the belt supporting member 30 is provided with an opening 30c (see FIG. 5), and both ends of the halogen heater 23 and the stay 25 are supported by the side plates 31 through the opening 30c. The halogen heater 23 and the stay 25 may be supported by the belt support member 30.

As described above, in the present embodiment, both the nip forming member 24 and the fixing belt 21 are heated by the infrared light directly emitted from the halogen heater 23 and the infrared light reflected by the reflecting member 26. Accordingly, in the nip portion N, heat generated by heating the nip forming member 24 and the fixing belt 20 is applied from both, so that the nip portion N can be efficiently heated.

By the way, in the fixing device 5 having such a configuration, as a measure for further improving the thermal efficiency, for example, the height of the structure such as the stay 25 and the reflecting member 26 (the height from the nip forming member 24) is lowered to fix the fixing device 5. It is conceivable to widen the range where the infrared light is directly irradiated to the belt 21 (direct heating area). However, if the height of the stay 25 is reduced, the rigidity of the stay 25 against the pressure applied from the pressure roller 22 is reduced, so that the deflection of the nip forming member 24 is increased and the nip portion N having a uniform width and a uniform pressure is obtained. May be difficult to obtain. Therefore, it does not mean that the heights of the stay 25 and the reflection member 26 and the like may be simply lowered.

Therefore, in the fixing device 5 according to the embodiment of the present invention, in order to secure the rigidity of the stay 25 and to secure a wide direct heating area of the fixing belt 21, the following configuration is adopted.

That is, as shown in FIG. 7, in the present embodiment, in order to secure a wide direct heating region of the fixing belt 21, the stays 25 and the reflecting members 26 are arranged on the side opposite to the nip portion N side (upper side in the figure). ) Toward each other so that the respective intervals gradually increase. That is, the interval between the facing surfaces 250 arranged on the upstream and downstream sides of the stay 25 in the paper transport direction with the halogen heater 23 interposed therebetween, and with the reflection member 26 sandwiching the halogen heater 23 in the upstream direction of the paper transport direction. The distance between the facing surfaces 260 arranged on the downstream side increases toward the side opposite to the nip portion N. As a result, in the cross section that intersects the width direction of the fixing belt 21 shown in FIG. 7, the width β from the upper end surface 25b of one stay 25 in the figure to the upper end surface 25b of the other stay 25 in the figure is one stay 25. The width [alpha] from the lower end surface 25a of FIG. 25 to the lower end surface 25a of the other stay 25 is larger (α<β). Further, the same relationship as this holds for the pair of reflecting members 26.

As described above, in the fixing device 5 according to the embodiment of the present invention, the stays 25 and the reflecting members 26 are arranged so as to be inclined to each other, and the intervals between the stays 25 and the reflecting members 26 increase toward the upper side in FIG. 7. By doing so, the width W1 of the opening between the stays 25 and the reflection member 26 on the upper side in the drawing becomes larger than that in the example in which the pair of stays 25 are arranged in parallel with each other as shown in FIG. 26 (W1 >W3). This makes it possible to secure a wide range (direct heating region) where the halogen heater 23 directly irradiates the fixing belt 21 with infrared light, thereby improving the thermal efficiency of the fixing belt 21. Further, since the direct heating area of the fixing belt 21 is widened, the thermal responsiveness of the fixing belt 21 to the lighting control (heat generation control) of the halogen heater 23 can be improved.

In addition, in the fixing device 5 according to the embodiment of the present invention, the intervals between the stays 25 and the reflecting members 26 are set to increase toward the upper side in FIG. The width W2 of the lower opening of FIG. 7 between the reflecting members 26 becomes smaller than that in the example shown in FIG. 26 (W2<W4). Therefore, in the fixing device 5 according to the embodiment of the present invention, as shown in FIG. 7, the width γ of the nip forming member 24 in the sheet passing direction (recording medium passing direction) can be reduced. The width γ of the nip forming member 24 in the sheet passing direction is the width from the upstream end to the downstream end of the nip forming member 24 in the sheet passing direction. Since the width γ of the nip forming member 24 in the sheet passing direction can be reduced in this manner, the nip forming member 24 is less likely to bend, and the rigidity of the nip forming member 24 with respect to the pressure applied from the pressure roller 22 is increased, so that the nip forming member 24 is uniform. The width and the pressure nip portion N can be obtained. Further, since the width γ of the nip forming member 24 in the sheet passing direction is reduced, the fixing device 5 can be downsized.

The lower end surface 25a of each stay 25 in FIG. 7 needs to be arranged within a range narrower than the width γ of the nip forming member 24 in the sheet passing direction in order to support the nip forming member 24. That is, in the cross section that intersects the width direction of the fixing belt 21 shown in FIG. 7, the width α from the lower end surface 25 a of the one stay 25 to the lower end surface 25 a of the other stay 25 is the paper feed direction of the nip forming member 24. Is set smaller than the width γ of. Therefore, in the present embodiment, the width α from one lower end surface 25a to the other lower end surface 25a, the width β from one upper end surface 25b to the other upper end surface 25b, and the sheet passing direction of the nip forming member 24. Width γ is set to have a relationship of α<γ<β. Note that this relationship is similarly established between the nip forming member 24 and each reflecting member 26.

Further, in the fixing device 5 according to the embodiment of the present invention, each stay 25 extends linearly from the lower end surface 25a of FIG. 7 toward the upper end surface 25b, so that a cross section L-shaped as shown in FIG. It becomes easier to secure a large height H1 of the stay 25 (H1>H2) as compared with the stay 25 of the mold. That is, in the case of the example shown in FIG. 27, since the stay 25 is formed in an L-shaped cross section, the width G2 of the contact portion of the stay 25 with respect to the nip forming member 24 is increased, and the nip forming member 24 is illustrated. In the fixing belt 21, it is difficult to secure the height H2 of the stay 25 because the fixing belt 21 has a circular shape that is slightly crushed in the vertical direction. On the other hand, in the case of the embodiment of the present invention shown in FIG. 7, the linear stays 25 are arranged so as to be inclined with respect to each other, so that the width G1 at which the stay 25 contacts the nip forming member 24 is reduced. Since it is possible to suppress the spread of the nip forming member 24 in the left-right direction in the drawing, it becomes easy to secure the height H1 of the stay 25.

As described above, in the fixing device 5 according to the embodiment of the present invention, the height H1 of the stay 25 is sufficiently high by adopting the layout in which the pair of linearly formed stays 25 are arranged to be inclined with respect to each other. It is possible to secure a large direct heating area of the fixing belt 21 while ensuring the above. That is, according to the present invention, by effectively disposing the stay 25 in the limited space inside the fixing belt 21, it is possible to realize both improvement of thermal efficiency and securing of rigidity of the stay 25. As a result, it is possible to provide a fixing device that is small in size but excellent in fixing property and energy saving property.

Further, in the fixing device 5 according to the embodiment of the present invention, unlike the example having the stay 25 having an L-shaped cross section as shown in FIG. 27, the contact width G1 of the stay 25 with the nip forming member 24 is reduced. Therefore, it is possible to secure a wide width W2 of the opening on the nip N side (W2>W5). Therefore, the direct heating area of the nip forming member 24 is also widened, and the thermal efficiency is further improved.

Further, since the stay 25 is linear, it is not necessary to bend the stay 25, so that the manufacturing cost can be reduced. When the stay 25 is bent, the thickness of the stay 25 cannot be increased so much (for example, it is difficult to secure a thickness of 3 mm or more). However, in the present embodiment, the stay 25 is not formed. Since the bending process does not have to be performed, the thickness of the stay 25 can be increased and the rigidity can be improved.

Further, since the stay 25 is linear, the shape of the reflecting member 26 arranged along the stay 25 can be simplified. This makes it possible to irradiate the fixing belt 21 or the nip forming member 24 with infrared light with a small number of reflections, and the attenuation of infrared light due to reflection is suppressed, so that heating can be performed effectively. Further, since the reflecting members 26 are obliquely arranged, the heating efficiency (reflected light rate) is improved. That is, the reflection member 26 is not arranged in the direction parallel to or perpendicular to the nip forming member 24, but is arranged so as to be inclined with respect to the nip forming member 24. It is possible to reduce the amount of infrared light reflected toward, and improve the heating efficiency (reflected light rate).

The shape of the stay 25 does not necessarily have to be linear. The pair of stays 25 may be formed in a slightly curved shape as long as they are inclined with respect to each other from the nip portion N side toward the opposite side so that the distance therebetween becomes larger. For example, as in the example shown in FIG. 8, the stay 25 may have a curved shape that follows the curvature of the reflecting member 26. Further, as in the example shown in FIG. 9, the stay 25 may have a shape in which a plurality of linear portions 251 and 252 having different angles are combined.

Further, the lower end surface 25a of each stay 25 in FIG. 7 is preferably arranged in parallel with the nip forming member 24 in order to stably support the nip forming member 24. That is, by arranging the lower end surface 25a of each stay 25 in parallel with the nip forming member 24, the contact area between the stay 25 and the nip forming member 24 increases, and the posture of the nip forming member 24 can be stabilized.

Further, it is desirable that the lower end surface 25a of each stay 25 is arranged perpendicularly to the pressing direction E (see FIG. 7) of the pressing roller 22. By doing so, the pressing force of the pressure roller 22 can be reliably received by the lower end surface 25a of each stay 25, and the deformation of the nip forming member 24 can be highly suppressed. The "pressurizing direction E of the pressure roller 22" referred to in the present invention is the main direction of the pressure applied to the nip forming member 24 from the pressure roller 22, and specifically, shown in FIG. It is defined as a direction parallel to a straight line K passing through the center M of the nip portion N in the width direction (or the center of the fixing belt 21) and the center O of the pressure roller 22 in a cross section intersecting the width direction of the fixing belt 21.

As shown in FIG. 10, each stay 25 is positioned by being inserted into the hole 32 provided in the side plate 31. In this case, the pressing force of the pressure roller 22 acts on each stay 25 from the lower side to the upper side in FIG. 10, so that the pressing force is mainly received by the upper surface 32 a of the hole 32 in the figure. Therefore, it is desirable that the surface 32a of the hole portion 32 that receives a pressing force and the upper end surface 25b of the stay 25 that is in contact with the surface 32a be arranged in parallel with each other. By doing so, it is possible to secure a large contact area between them, and the side plate 31 can stably support the stay 25.

Further, by arranging the surface 32a of the hole portion 32 that receives the pressing force and the upper end surface 25b of the stay 25 that comes into contact with the surface 32a perpendicularly to the pressing direction E of the pressing roller 22, the pressing roller 22 Since the side plate 31 can reliably receive the pressing force of, the deformation of the stay 25 can be suppressed. Further, if the upper end surface 25b of the stay 25 is made parallel to the nip forming member 24, it becomes easy to manage the dimensions of these.

Further, the pair of stays 25 are arranged such that the distance between them becomes wider in the pressing direction E of the pressing roller 22, so that the nip forming member 24 can be stably supported. That is, since the distance between the support points of each stay 25 is wider on the downstream side than on the upstream side in the pressing direction E, the nip forming member 24 is stably supported without wobbling.

The stay 25 is not limited to the case where the stay 25 is continuously formed with the same cross-sectional shape over the entire longitudinal direction thereof, but as in the example shown in FIG. It may be formed in a shape having a notch. In this case, the upper end surfaces 25b1 and 25b2 of the stays 25 having different heights with the stepped portion as a boundary do not necessarily have to be parallel end surfaces, and the upper end surface 25b1 to be inserted into the hole 32 of the side plate 31 has a low height. Other than the end surface 25b1 (the upper end surface 25b2 having a high height), the end surface may be the cut end surface of the plate material. Further, the stay 25 may be configured to be inserted and positioned in a hole provided in the belt supporting member 30 instead of being inserted and positioned in the hole 26 of the side plate 31.

Hereinafter, an embodiment different from the above-described embodiment (first embodiment) will be described. The different parts will be mainly described, and the other parts are basically the same as those in the above-described embodiment, and thus the description thereof will be omitted.

FIG. 12 is a side sectional view of the fixing device according to the second embodiment of the present invention.

In the above-described embodiment, only one halogen heater 23 is provided, whereas in the second embodiment shown in FIG. 12, two halogen heaters 23 are provided side by side in the vertical direction. As described above, by providing the two halogen heaters 23, the heating range and the use can be divided for each halogen heater 23. For example, one of the two halogen heaters 23 is a heater that heats the central portion side in the belt width direction, and the other is a heater that heats the end portion side in the belt width direction so that the heating ranges are different. You can The upper halogen heater 23 in FIG. 12 may be used mainly for directly heating the fixing belt 21, and the lower halogen heater 23 may be mainly used for heating the nip forming member 24.

FIG. 13 is a side sectional view of a fixing device according to the third embodiment of the present invention.

In the above-described embodiment, the stay 25 and the reflecting member 26 are in direct contact with each other at their end portions, whereas in the third embodiment shown in FIG. 13, the stay 25 and the reflecting member 26 are in contact with each other. A low thermal conductive member 33 having a lower thermal conductivity than the stay 25 and the reflective member 26 is interposed therebetween. That is, the stay 25 and the reflecting member 26 are in indirect contact with each other via the low thermal conductive member 33. In this way, since the stay 25 and the reflecting member 26 are in contact with each other via the low heat conductive member 33, heat transfer from the reflecting member 26 to the stay 25 is suppressed, and wasteful consumption of heat energy is further reduced. become able to.

FIG. 14 is a side sectional view of a fixing device according to the fourth embodiment of the present invention.

In the above-described embodiment, the pair of stays 25 are arranged in line symmetry with respect to the straight line U (see FIG. 7) passing through the center Q of the halogen heater 23 and the center O of the pressure roller 22. On the other hand, in the fourth embodiment shown in FIG. 14, the pair of stays 25 are arranged non-axisymmetrically to each other. Specifically, in FIG. 14, the stay 25 on the left side (nip outlet side) is arranged to be inclined with respect to the nip forming member 24, while the stay 25 on the right side (nip inlet side) is formed with a nip. It is arranged so as to be substantially orthogonal to the member 24. Further, the right side stay 25 in FIG. 14 has a length in the vertical direction in the figure (the length from the end surface 25a on the nip portion N side to the end surface 25b on the opposite side) than the stay 25 on the left side in FIG. It is formed short. The end surface here means at least the end surface in the area through which the sheet passes.

Even in the configuration including the pair of stays 25 arranged non-axisymmetrically, the stays 25 are arranged so that the distance between the stays 25 increases toward the upper side (the side opposite to the nip portion N) in FIG. By being arranged so as to be inclined, it is possible to obtain the same effect as that of the above-described embodiment.

FIG. 15 is a side sectional view of a fixing device according to the fifth embodiment of the present invention.

In the fifth embodiment shown in FIG. 15, through-holes 25c and 26c are provided in portions of each stay 25 and each reflecting member 26 near the halogen heater 23, and infrared rays from the halogen heater 23 pass through these through-holes 25c and 26c. The fixing belt 21 is directly irradiated with light. In the embodiment having no such through holes 25c and 26c (for example, the embodiment shown in FIG. 7), when a part of the light emitted from the halogen heater 23 is reflected at a position near the halogen heater 23, The reflected light is applied to the halogen heater 23 without being applied to the fixing belt 21 and the nip forming member 24. Alternatively, even if the fixing belt 21 or the nip forming member 24 is irradiated with infrared light due to a large number of reflections, thermal energy is attenuated, and thus heating efficiency is reduced. As described above, in the embodiment having no through holes 25c and 26c, some infrared light may not be effectively utilized as energy for heating the fixing belt 21 or the nip forming member 24. On the other hand, in the fifth embodiment shown in FIG. 15, since the through holes 25c and 26c are provided in the portions of the stays 25 and the reflecting members 26 near the halogen heater 23, respectively, the through holes 25c and 26c are formed. Infrared light can be directly radiated to the fixing belt 21 through the through, and the thermal efficiency can be improved.

Further, as shown in FIG. 15, the diameter (width) d1 of the through hole 25c of the stay 25 is preferably set larger than the diameter (width) d2 of the through hole 26c of the reflecting member 26. Since the infrared light emitted from the halogen heater 23 tends to spread as the distance from the halogen heater 23 increases, if the diameter d1 of the through hole 25c of the stay 25 is the same as or smaller than the diameter d2 of the through hole 26c of the reflecting member 26, Part of the infrared light that has passed through the through hole 26c of the reflecting member 26 hits the edge of the through hole 25c of the stay 25 and is blocked. Therefore, as shown in FIG. 15, by making the diameter d1 of the through hole 25c of the stay 25 larger than the diameter d2 of the through hole 26c of the reflecting member 26, the infrared light to the edge of the through hole 25c of the stay 25 can be reduced. Irradiation can be avoided. As a result, it is possible to increase the amount of infrared light directly applied to the fixing belt 21 and reduce wasteful consumption of heat energy to the stay 25.

Further, as in the example shown in FIG. 16, the shapes of the through holes 25c and 26c may be elliptical. In this case, it is desirable that each of the through holes 25c and 26c be formed to be long in a direction intersecting the pressing direction E of the pressing roller 22. By doing so, the section modulus of the stay 25 and the reflecting member 26 in the pressing direction E can be secured, and the strength can be easily maintained.

Further, as shown in the example on the left side of FIG. 17, the through holes 25c and 26c may be formed in a rectangular shape. However, when it is attempted to secure the same opening width as the elliptical through holes 25c and 26c in the rectangular through holes 25c and 26c, in particular, the through holes 25c and 26c are formed at the end portions in the longitudinal direction of the through holes 25c and 26c. Since the opening width in the pressurizing direction E becomes large (h1>h2), it is preferable to have an elliptical shape rather than a rectangular shape in order to secure the opening width to some extent and also to secure the strength.

FIG. 18 is a cross-sectional view of the stay 25, the reflecting member 26, and the halogen heater 23 seen from above or below in FIG.

In the example shown in FIG. 18, the through holes 25c and 26c arranged on opposite sides of the halogen heater 23 are provided at positions displaced from each other in the belt width direction (the vertical direction in the drawing). As described above, in FIG. 18, the right through holes 25c and 26c and the left through holes 25c and 26c are provided so as to be displaced from each other, so that the infrared light is irradiated through the through holes 25c and 26c on one side. It is possible to prevent the area where the infrared light is irradiated through the through holes 25c and 26c on the other side from overlapping with each other in the belt width direction. As a result, the area where the infrared light is not directly irradiated to the fixing belt 21 can be eliminated or reduced in the belt width direction, and the fixing belt 21 can be heated almost uniformly, and It becomes possible to prevent defective fixing due to unevenness.

FIG. 19 is a perspective view of a stay according to the sixth embodiment of the present invention.

The pair of stays 25 may be integrally configured as in the sixth embodiment shown in FIG. In the example shown in FIG. 19, the stay 25 includes a pair of side wall portions 41 that are arranged to be inclined with each other, and a bottom wall portion 42 that connects both longitudinal end portions of each side wall portion 41. In this way, by integrally forming the pair of stays 25, it is not necessary to separately position and assemble the two stays 25, and the assembling property and the maintainability are improved. Further, in the example shown in FIG. 19, an opening 40 is formed between the bottom wall portion 42 on the one end side and the bottom wall portion 42 on the other end side. The fixing belt 21 is directly irradiated with infrared light. The width Y of the opening 40 is preferably set larger than the maximum sheet passing width Wmax. The "maximum sheet passing width (maximum recording medium passage width)" in the present specification means that the sheet passes ideally when the sheet (recording medium) is not displaced and skewed. It means the width area.

20 to 22 are views showing the nip forming member 24 according to the seventh embodiment of the present invention.

As shown in FIG. 20, in the seventh embodiment of the present invention, the halogen heater side light receiving surface 24d of the nip forming member 24 (nip forming portion 24a) has a plurality of inclined surfaces 24e inclined with respect to the light receiving surface 24d. It is provided. The inclined surfaces 24e are provided on both end sides in the longitudinal direction of the nip forming member 24 and outside the maximum sheet passing width Wmax.

Each inclined surface 24e is inclined so as to face the center side in the belt width direction (the arrow J direction in FIGS. 20 and 21). In this way, since each inclined surface 24e is inclined so as to face the center side in the belt width direction, the infrared light R emitted from the halogen heater 23 is directed in the belt width direction by the inclined surface 24e as shown in FIG. It is reflected toward the center. Then, the reflected light is further reflected by the reflecting member 26, so that the reflected light is applied to a region inside the maximum sheet passing width Wmax.

As described above, according to the configuration of the seventh embodiment, a part of the infrared light (radiant heat) radiated to the outside of the maximum paper-passing width Wmax is reflected by the inclined surface 24e, so that the inside of the maximum paper-passing width Wmax is reduced. It can be used as heat energy for heating a region, and heat energy efficiency can be improved. In particular, when the heat generating portion (heat generation length) 23a of the halogen heater 23 is formed longer than the maximum paper passing width Wmax (see FIG. 22) like the fixing device 5 according to the present embodiment, the maximum paper passing width Wmax is Since the amount of infrared light radiated on the outside increases, a part of the infrared light is reflected toward the center side in the belt width direction by the inclined surface 24e and positively used as heat energy for heating the inside of the maximum sheet passing width Wmax. , Improvement of thermal energy efficiency can be expected.

Further, by reflecting the infrared light by the inclined surface 24e, the amount of heat absorbed by the nip forming member 24 is reduced in the area outside the maximum sheet passing width Wmax. As a result, it is possible to suppress an excessive temperature rise outside the maximum sheet passing width Wmax, such as during continuous sheet passing, and reduce the risk of failure of the fixing device. Further, it is not necessary to take measures such as decreasing the printing speed when the temperature rises, and it is possible to improve the productivity (fixing speed).

Further, in the present embodiment, as shown in FIG. 20, the light-receiving surface 24d on the inner side of the maximum sheet passing width Wmax in the nip forming member 24 is painted black so that the heat absorption rate inside the maximum sheet passing width Wmax is increased. Is improving. On the other hand, in the area outside the maximum sheet passing width Wmax, the light receiving surface 24d and the inclined surface 24e are not painted black, and the reflectance is increased.

Further, fine particles (black paint) are applied to the light receiving surface 24d inside the maximum paper passing width Wmax in the nip forming member 24 by a coating method such as spraying, and the light receiving surface 24d is inside the outside of the maximum paper passing width Wmax. The surface roughness may be increased. In this case as well, the heat absorption rate of the light receiving surface 24d on the inner side of the outer side of the maximum sheet passing width Wmax is improved, so that the thermal energy efficiency is improved. The surface roughness Ra of the light receiving surface 24d inside the maximum paper passing width Wmax is preferably 0.5 or more.

The inclined surface 24e can be formed separately from the nip forming member 24, but from the viewpoint of manufacturing cost, it is desirable that the inclined surface 24e be integrally formed with the nip forming member 24. In the present embodiment, the inclined surface 24e is integrally formed by drawing with a press. When the inclined surface 24e is formed by drawing, it is desirable that the drawing depth Z (the height of the inclined surface 24e shown in FIG. 22) be about 0.5 mm to 2 mm.

Further, by making the drawing depth Z constant and changing the drawing length L (the length of the inclined surface 24e in the belt width direction shown in FIG. 22), the inclination angle θ of the inclined surface 24e can be increased. Can be adjusted appropriately. For example, as in the example shown in FIG. 23, the inclination angle θ1 of the inclined surface 24e arranged on the outer side in the belt width direction (left side in the figure) is set to the inclined surface θe arranged on the inner side in the belt width direction (right side in the figure). By making it larger than the inclination angle θ2 of 24e, it is possible to increase the reflection angle of the inclined surface 24e arranged on the outer side in the belt width direction, so that the infrared light R on the outer side can reach the area inside the maximum paper passing width W. It becomes easy to reflect toward.

When the inclined surface 24e is formed by drawing, the recess 24f is formed on the surface (nip forming surface 24c) on the back side of the surface on which the inclined surface 24e is formed, as shown in FIG. 22 or FIG. A lubricant such as grease may be stored in the recess 24f thus formed. In that case, since the lubricant is held in the recess 24f, the lubricant can be interposed between the nip forming member 24 and the fixing belt 21 for a long period of time, and the nip forming member 24 and the fixing belt can be fixed. It is possible to extend the life of the belt 21 and extend the maintenance cycle.

Further, as in the example shown in FIG. 24, the recess 24f may be inclined such that its longitudinal direction faces the belt width direction central portion side toward the downstream side in the belt rotation direction B. In this case, as the fixing belt 21 rotates, the lubricant stored in the concave portion 24f moves in the direction of arrow D in FIG. 24 along the longitudinal direction of the concave portion 24f, so that the lubricant is centered in the belt width direction. Will be able to actively supply to the side. Further, since the outflow of the lubricant to the outer side in the belt width direction can be suppressed, the lubricant can be interposed between the nip forming member 24 and the fixing belt 21 for a long period of time.

Further, as shown in FIG. 20, when a plurality of inclined surfaces 24e are provided so as to be close to each other, it is desirable that a flat surface 24g in which the inclined surface 24e is not formed is provided between the inclined surfaces 24e. By doing so, the flat surface 24h is also formed between the recesses 24f on the back side of the inclined surface 24e (see FIG. 22), and thus the fixing belt 21 can be supported by the flat surface 24h. As a result, it is possible to suppress the deformation of the fixing belt 21 at the location where the recess 24f is provided, and to prevent damage such as buckling damage (kink) of the fixing belt 21.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

In the above-described embodiment, the pair of stays 25 are arranged on both sides of the halogen heater 23, but the halogen heater 23 is arranged at a position projecting upward in FIG. Good. That is, according to the present invention, if the pair of stays 25 are arranged on both sides of the straight line U (see FIG. 7) passing through the center Q of the halogen heater 23 and the center O of the pressure roller 22, the pair of stays 25 is arranged. It is also applicable to a configuration in which 25 is not arranged at a position sandwiching the halogen heater 23. The present invention is also applicable to a fixing device that does not include the reflecting member 26. That is, in the present invention, the two structures that are inclined with respect to each other such that the distance therebetween increases from the nip portion side to the opposite side, both the stay 25 and the reflecting member 26, or Any one of these or members other than the stay 25 and the reflecting member 26 may be used.

Further, the fixing device according to the present invention is not limited to the fixing device 5 that horizontally conveys a sheet as shown in FIG. The installation direction of the fixing device 5 can be appropriately changed. For example, the present invention can be applied to the fixing device 5 that vertically conveys a sheet as shown in FIG.

1 Image Forming Device 2 Image Forming Section 5 Fixing Device 21 Fixing Belt (Fixing Member)
22 Pressure roller (opposing member)
23 Halogen heater (heating member)
24 Nip Forming Member 25 Stay (Supporting Member)
26 Reflective member 31 Side plate (frame member)
250 Opposing surface 260 Opposing surface M Center in the width direction of the nip portion N Nip portion P Paper (recording medium)
O Center of the pressure roller Q Center of the halogen heater α Width from the lower end surface of one stay to the lower end surface of the other stay β Width from the upper end surface of one stay to the upper end surface of the other stay γ Nip forming member width

JP, 2009-93141, A

Claims (11)

A tubular fixing member,
A facing member arranged to face the outer peripheral surface of the fixing member,
A heating member disposed inside the fixing member,
A nip forming member disposed inside the fixing member and forming a nip portion with the fixing member sandwiched between the fixing member and the facing member;
In a cross section that intersects the width direction of the fixing member, inside the fixing member, a structure having facing surfaces on the upstream side and the downstream side in the recording medium conveyance direction with the heating member interposed therebetween,
A fixing device comprising:
The fixing device is characterized in that in the structure, the distance between the facing surfaces increases from the nip portion side toward the opposite side. The fixing device according to claim 1, wherein a distance between the facing surfaces gradually increases. Two of the structures are provided on the upstream side and the downstream side in the recording medium conveyance direction with the heating member interposed therebetween.
The two structures contact a surface of the nip forming member opposite to the nip side,
In a cross section that intersects the width direction of the fixing member, the width from the end surface on the nip portion side of one of the structures to the end surface on the nip portion side of the other structure is α, and one of the structures is When the width from the end surface on the side opposite to the nip portion side to the end surface on the side opposite to the nip portion side of the other structure is β, and the width of the nip forming member is γ, these widths α, The fixing device according to claim 1, wherein β and γ satisfy a relationship of α<γ<β. A frame member for supporting the structure,
An end surface of the structure, which is in contact with the frame member or a member fixed to the frame member, on the side opposite to the nip portion side is perpendicular to the direction of the pressing force that the nip forming member receives from the facing member side. The fixing device according to any one of claims 1 to 3, which is disposed in the. Two of the structures are provided on the upstream side and the downstream side in the recording medium conveyance direction with the heating member interposed therebetween.
The fixing device according to any one of claims 1 to 4, wherein lengths from an end surface on the nip portion side of the two structures to an end surface on the opposite side are different from each other. The structure on the nip entrance side where the recording medium enters the nip portion is closer to the nip end side than the structure on the nip outlet side where the recording medium is discharged from the nip portion. The fixing device according to claim 5, wherein the fixing device has a short length up to the end surface on the opposite side. 7. The end surface of the structure, which comes into contact with the nip forming member, is arranged perpendicularly to the direction of the pressing force that the nip forming member receives from the facing member side. Fixing device. The fixing device according to claim 1, wherein the structure is a support member that supports the nip forming member. The fixing device according to claim 1, wherein the structure includes a support member that supports the nip forming member, and a reflecting member that reflects heat generated from the heating member. The fixing device according to any one of claims 1 to 9, wherein the structure extends linearly from the nip portion side toward the opposite side. An image forming unit for forming an image on a recording medium,
A fixing device for fixing the image formed by the image forming unit to the recording medium;
In an image forming apparatus including
An image forming apparatus comprising the fixing device according to claim 1 as the fixing device.

Images