JP2019045709A - Fixing device and image forming apparatus - Google Patents

Abstract

To prevent, when heating of a heating member with a heat source is started, a reduction in temperature at both ends of a contact member compared with that of a center part, compared with a case where a member receiving heat from a heat source has a constant thickness.SOLUTION: A fixing device comprises: a fixing belt that is in contact with a recording material to be conveyed; a heat source 413 that includes a heating layer 413E extending in a width direction intersecting the conveyance direction of the recording material and has a facing surface 413A facing the fixing belt and an opposite surface 413B; and a heat supply member 415 that extends in the width direction and is arranged to be in contact with the opposite surface 413B of the heat source 413, has a smaller thickness at both ends in the width direction than the thickness in a center part in the width direction, and supplies heat of a portion of the heat source 413 having a higher temperature to a portion having a lower temperature.SELECTED DRAWING: Figure 5

Description

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

  Patent Document 1 discloses a heating device including a belt, a heating body fixedly supported on the inner side of the belt, a pressure member that forms a nip with the heating body, and a high thermal conductivity member in contact with the heating body. .

JP 2003-257592 A

In a fixing device that fixes an image on a recording material to the recording material, for example, a contact member that contacts the recording material is heated using a heating source, and the heated contact member is brought into contact with the recording material.
In such a fixing device, for example, when fixing an image on a recording material having a small width, heat from a heating source is not consumed in the non-sheet passing area at both ends, and the contact member is compared with the sheet passing area. The temperature of the battery may rise excessively. In order to suppress this, for example, a member that receives heat from the heating source may be provided in contact with the heating source.

When a member for receiving heat from the heating source is provided in the fixing device, the heat transferred from the heating source to the member is supplied from the high temperature portion to the low temperature portion and diffused to the outside of the member. Heat diffusion tends to occur particularly at both ends of a member that receives heat from a heating source. For this reason, when the thickness of the member that receives heat from the heating source is constant, for example, when starting up the heating of the contact member by the heating source, the temperature at both ends of the contact member is compared with the center portion. May occur.
In the present invention, compared to the case where the thickness of the member receiving heat from the heating source is constant, the temperature at both ends of the contact member is lower than that in the central portion when heating of the heating member by the heating source is started. It aims at suppressing becoming.

The invention according to claim 1 includes a contact member that contacts the recording material to be conveyed, and a heat generating portion that extends in the width direction intersecting the recording material conveyance direction, and has a facing surface and an opposite surface that face the contact member. The heating source is arranged so as to extend in the width direction and contact the opposite surface of the heating source, and the thickness of both end portions in the width direction is smaller than the thickness of the center portion in the width direction, And a heat supply member that supplies heat from a portion having a high temperature to a portion having a low temperature.
According to a second aspect of the present invention, the heating source further includes a support substrate that has a lower thermal conductivity than the heat supply member, extends in the width direction, supports the heat generating unit, and contacts the heat supply member. The fixing device according to claim 1, wherein a thickness of the support substrate is equal at both end portions and a central portion in the width direction.
According to a third aspect of the present invention, the heat supply member has a length along the width direction that is longer than the heat generating portion, and a thickness of a region facing both ends of the heat generating portion in the width direction is the width direction. The fixing device according to claim 1, wherein the fixing device is thinner than a central portion of the fixing device.
According to a fourth aspect of the present invention, the heat supply member includes a first heat supply plate disposed in contact with the opposite surface of the heating source so as to face the entire region in the width direction of the heat generating portion, and the first heat supply plate. The fixing device according to claim 1, further comprising: a second heat supply plate that is stacked at a center portion in the width direction of the heat supply plate and has a shorter length in the width direction than the first heat supply plate. It is.
The invention according to claim 5 is characterized in that the first heat supply plate and the second heat supply plate of the heat supply member are laminated via a viscous liquid having thermal conductivity. The fixing device according to (1).
The invention according to claim 6 is the fixing device according to claim 1, wherein the heat supply member continuously decreases in thickness toward the both end portions in the width direction.
In the invention according to claim 7, in the heat supply member, the length along the width direction is longer than the heat generating portion, and the thickness of the region facing the both end portions in the width direction of the heat generating portion is continuous. The fixing device according to claim 6, wherein the fixing device is thin.
In the invention according to claim 8, the recording material having a different length in the width direction is conveyed to the contact member, and the heat supply member is a maximum in which the recording material having the longest length in the width direction is conveyed. 2. The fixing device according to claim 1, wherein a thickness of a region facing both ends of the conveyance region in the width direction is thin.
The invention according to claim 9 is that the heat supply member has a thickness at both end portions in the width direction that is smaller than a minimum conveyance area in which the recording material having the shortest length in the width direction is conveyed. The fixing device according to claim 8, wherein the fixing device is a fixing device.
The invention according to claim 10 is the fixing device according to claim 9, wherein the heat supply member has a constant thickness at least in a region facing the minimum conveyance region.
The invention according to claim 11 further includes a pressurizing member that pressurizes a recording material that is disposed in contact with the contact member and passes between the contact member, and the heating source and the heat supply member include the contact member. The fixing device according to claim 1, wherein the fixing device is provided at a position facing the pressure member.
According to a twelfth aspect of the present invention, there is provided a contact member that contacts the recording material to be conveyed, a heat generating portion extending in the width direction intersecting the recording material conveyance direction, and a plate-like shape having the same thickness in the width direction. And a support substrate that supports the heat generating portion, a heating source having an opposing surface and an opposite surface facing the contact member, and a material having a higher thermal conductivity than the support substrate, the width direction And a heat conduction member disposed in contact with the opposite surface of the heating source and having a heat capacity at both ends in the width direction that is smaller than that of the center portion in the width direction.
The invention according to claim 13 includes an image forming unit that forms an image on a recording material, and a fixing device that fixes an image formed on the recording material by the image forming unit to the recording material, and the fixing device includes: An image forming apparatus comprising the fixing device according to claim 1.

According to the first aspect of the present invention, when the heating member is heated by the heating source, the temperature at both ends of the contact member is in the middle compared to the case where the thickness of the member receiving the heat from the heating source is constant. It can suppress that it becomes low compared with a part.
According to the invention which concerns on Claim 2, compared with the case where the thickness of a support substrate differs in the both ends and center part of the width direction, it can suppress that the structure of a heating source becomes complicated.
According to the invention which concerns on Claim 3, compared with the case where the thickness of the area | region which opposes the both ends of the heat-emitting part in a heat supply member is not thin, the temperature rise in a non-sheet passing area | region can be suppressed. .
According to the invention which concerns on Claim 4, compared with the case where a heat supply member is comprised with a single member, the heat capacity in a heat supply member can be adjusted easily.
According to the invention which concerns on Claim 5, compared with the case where a 1st heat supply plate and a 2nd heat supply plate are laminated | stacked directly, there is no air between the 1st heat supply plate and the 2nd heat supply plate. It is suppressed that a clearance gap arises and heat conductivity falls.
According to the invention which concerns on Claim 6, compared with the case where the thickness of the both ends of the width direction is not continuously thinning, the temperature distribution of the contact member at the time of starting the heating of the heating member by a heating source is smooth. Can be.
According to the invention which concerns on Claim 7, compared with the case where the thickness of the area | region which opposes the both ends of a heat generating part is not thinning continuously, the heating of the heating member by a heating source is started. The temperature distribution can be smoothed.
According to the invention which concerns on Claim 8, compared with the case where the thickness of the area | region which opposes the both ends of the width direction of a largest conveyance area | region in the heat supply member is not thin, heating of the heating member by a heating source was started. In this case, it is possible to suppress a temperature drop at both ends of the maximum conveyance area.
According to the ninth aspect of the present invention, the temperature increase in the non-sheet passing region can be further suppressed as compared with the case where the thickness on the central portion side in the width direction is thinner than the minimum conveyance region.
According to the tenth aspect of the present invention, uneven fixing can be suppressed as compared with a case where the thickness of the region facing the minimum conveyance region of the heat supply member is not constant.
According to the eleventh aspect of the present invention, even when heat is conducted to the pressure member through the contact member, the temperature at both ends of the contact member is set to the center when heating of the heating member by the heating source is started. It can suppress that it becomes low compared with a part.
According to the twelfth aspect of the present invention, when the heating member starts to be heated by the heating source, the temperature at both ends of the contact member is in the middle compared to the case where the thickness of the member receiving the heat from the heating source is constant. It can suppress that it becomes low compared with a part.
According to the thirteenth aspect of the present invention, when the heating member is heated by the heating source, the temperatures at both ends of the contact member are in the middle compared to the case where the thickness of the member receiving the heat from the heating source is constant. It can suppress that it becomes low compared with a part.

1 is an overall configuration diagram of an image forming apparatus. (A), (B), and (C) are diagrams illustrating the configuration of the fixing device. 2 is a diagram illustrating a configuration of a fixing device. FIG. FIG. 6 is a diagram illustrating a configuration of a fixing device of a comparative example and a temperature distribution of a fixing belt. It is the figure which showed the structure of the heating source and heat supply member of this embodiment. FIG. 6 is a view showing a temperature distribution of the fixing belt of the present embodiment. It is the figure which showed the structure of the heating source of Embodiment 2, and a heat supply member. It is the figure which showed the structure of the heating source of Embodiment 3, and a heat supply member. It is the figure which showed the structure of the heat supply member of Embodiment 4.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
(Embodiment 1)
FIG. 1 is an overall configuration diagram of the image forming apparatus 1.
The image forming apparatus 1 is a so-called tandem color printer.
The image forming apparatus 1 includes an image forming unit 10 as an example of an image forming unit. The image forming unit 10 forms an image on a sheet P that is an example of a recording material based on the image data of each color.

The image forming apparatus 1 is provided with a control unit 30 and an image processing unit 35.
The control unit 30 controls each functional unit provided in the image forming apparatus 1.
The image processing unit 35 performs image processing on image data from the personal computer (PC) 3, the image reading device 4, and the like.

The image forming unit 10 is provided with four image forming units 11Y, 11M, 11C, and 11K (hereinafter collectively referred to simply as “image forming unit 11”) arranged in parallel at a predetermined interval. ing.
Each image forming unit 11 has the same configuration except for toner stored in a developing device 15 (described later). Each image forming unit 11 forms yellow (Y), magenta (M), cyan (C), and black (K) toner images (images).

Each of the image forming units 11 is provided with a photosensitive drum 12, a charger 200 that charges the photosensitive drum 12, and an LED print head (LPH) 300 that exposes the photosensitive drum 12.
The photosensitive drum 12 is charged by the charger 200. Further, the photosensitive drum 12 is exposed by the LPH 300, and an electrostatic latent image is formed on the photosensitive drum 12.
Further, each image forming unit 11 is provided with a developing device 15 for developing the electrostatic latent image formed on the photosensitive drum 12 and a cleaner (not shown) for cleaning the surface of the photosensitive drum 12.

The image forming unit 10 also sequentially transfers the color toner images formed on the photosensitive drum 12 to the intermediate transfer belt 20 and the intermediate transfer belt 20 to which the color toner images formed on the photosensitive drum 12 are transferred. A primary transfer roll 21 (primary transfer) is provided.
The image forming unit 10 also includes a secondary transfer roll 22 that collectively transfers (secondary transfer) the toner image transferred onto the intermediate transfer belt 20 to the paper P, and the toner image transferred onto the paper P. There is provided a fixing device 40 for fixing the toner to the surface.

The fixing device 40 is provided with a fixing belt module 41 having a heating source and a pressure roll 46.
The fixing belt module 41 is disposed on the left side of the sheet conveyance path R1 in the drawing. The pressure roll 46 is disposed on the right side of the sheet conveyance path R1 in the drawing. Further, a pressure roll 46 is pressed against the fixing belt module 41.

The fixing belt module 41 includes a film-like fixing belt 411 that contacts the paper P.
The fixing belt 411 as an example of the contact member includes, for example, a release layer that is positioned on the outermost layer and that contacts the paper P, an elastic layer that is positioned on the inner side of the release layer, and a base layer that supports the elastic layer. It consists of.
Further, the fixing belt 411 is formed in an endless shape, and circulates and moves in the counterclockwise direction in the drawing. Further, a lubricant for lubrication is applied to the inner peripheral surface 411A of the fixing belt 411, and sliding resistance between a heating source and the like, which will be described later, and the fixing belt 411 is reduced. Examples of the lubricant include liquid oils such as silicone oil and fluorine oil, grease obtained by mixing a solid substance and liquid, and combinations of these.

The fixing belt 411 contacts the paper P conveyed from below in the drawing. A portion of the fixing belt 411 that contacts the paper P moves together with the paper P. Further, the fixing belt 411 sandwiches the paper P together with the pressure roll 46 and pressurizes and heats the paper P.
Further, the fixing belt module 41 is provided with a heating source (described later) for heating the fixing belt 411 inside the fixing belt 411.

A pressure roll 46 as an example of a pressure member is disposed on the right side of the sheet conveyance path R1 in the drawing. The pressure roll 46 is pressed against the outer peripheral surface 411B of the fixing belt 411 and pressurizes the paper P passing between the fixing belt 411 and the pressure roll 46 (paper P passing through the paper transport path R1).
Further, the pressure roll 46 is rotated in the clockwise direction in the figure by a motor (not shown). When the pressure roll 46 rotates in the clockwise direction, the fixing belt 411 receives a driving force from the pressure roll 46 and rotates in the counterclockwise direction.

In the image forming apparatus 1, the image processing unit 35 performs image processing on the image data from the PC 3 or the image reading device 4, and the image data subjected to the image processing is supplied to each image forming unit 11.
For example, in the black (K) color image forming unit 11K, the photosensitive drum 12 is charged by the charger 200 while rotating in the direction of arrow A, and light is emitted based on the image data transmitted from the image processing unit 35. The exposure is performed by the LPH 300.

As a result, an electrostatic latent image related to a black (K) image is formed on the photosensitive drum 12. The electrostatic latent image formed on the photosensitive drum 12 is developed by the developing device 15, and a black (K) toner image is formed on the photosensitive drum 12.
Similarly, in the image forming units 11Y, 11M, and 11C, yellow (Y), magenta (M), and cyan (C) toner images are formed.

The respective color toner images formed by the respective image forming units 11 are sequentially electrostatically attracted by the primary transfer roll 21 onto the intermediate transfer belt 20 moving in the direction of arrow B, and the respective color toners are transferred onto the intermediate transfer belt 20. A superimposed toner image is formed.
The toner image formed on the intermediate transfer belt 20 is conveyed to a location (secondary transfer portion T) where the secondary transfer roll 22 is positioned as the intermediate transfer belt 20 moves. The paper P is supplied from the paper storage unit 1B to the secondary transfer unit T in accordance with the timing at which the toner image is conveyed to the secondary transfer unit T.

In the secondary transfer portion T, the toner image on the intermediate transfer belt 20 is electrostatically transferred collectively to the conveyed paper P by the transfer electric field formed by the secondary transfer roll 22.
Thereafter, the sheet P on which the toner image is electrostatically transferred is peeled off from the intermediate transfer belt 20 and conveyed to the fixing device 40.

In the fixing device 40, the paper P is sandwiched between the fixing belt module 41 and the pressure roll 46. Specifically, the paper P is sandwiched between the fixing belt 411 that is circulatingly moved in the counterclockwise direction and the pressure roll 46 that is rotated in the clockwise direction.
As a result, the paper P is pressurized and heated, and the toner image on the paper P is fixed to the paper P. Then, the sheet P after the fixing is completed is conveyed to the sheet stacking unit 1E by the discharge roll 500.

2A, 2 </ b> B, 2 </ b> C, and 3 are diagrams illustrating the configuration of the fixing device 40. 2A is a cross-sectional view of the fixing device 40, FIG. 2B is an enlarged view of the fixing device 40 shown in FIG. 2A, and FIG. 2C is a heating source described later. 4 is a diagram illustrating the configuration of 413. FIG. FIG. 3 is a perspective view of a heat source 413 and a heat supply member 415, which will be described later, as seen from the III direction in FIG.
As shown in FIG. 2A, the fixing device 40 is provided with a fixing belt module 41 and a pressure roll 46.
The fixing belt module 41 is provided with a fixing belt 411 used for fixing the toner image onto the paper P. The fixing belt 411 is pressed against the surface of the paper P on which the toner image is formed.

A pressure roll 46 as an example of a pressure member is pressed against the outer peripheral surface 411 </ b> B of the fixing belt 411 and presses the paper P passing between the fixing belt 411 and the pressure roll 46.
Specifically, the pressure roll 46 is disposed so as to be in contact with the outer peripheral surface 411B of the fixing belt 411, and a nip portion N that is a region through which the paper P passes while being pressed is formed between the pressure belt 46 and the fixing belt 411. To do.
In the present embodiment, the paper P is heated and pressurized while the paper passes through the nip portion N, and the toner image is fixed to the paper P.

As shown in FIG. 2B, a heating source 413 for heating the fixing belt 411 is provided inside the fixing belt 411.
The heat source 413 is formed in a plate shape and is provided along the moving direction and the width direction of the fixing belt 411. Further, the heat source 413 has a facing surface 413A that faces (contacts) the fixing belt 411, and a facing surface 413B that is located on the opposite side of the facing surface 413A. The heat source 413 has two side surfaces 413C that connect the opposing surface 413A and the opposite surface 413B.
In the present embodiment, heat is supplied from the heating source 413 to the fixing belt 411, and the fixing belt 411 is heated. In the present embodiment, the pressure roll 46 is pressed against the facing surface 413 </ b> A of the heating source 413 via the fixing belt 411.

As shown in FIG. 2C, the heat source 413 is formed on a plate-like base layer 413D and the surface of the base layer 413D (the surface on the fixing belt 411 side) and extends along a direction orthogonal to the paper surface of FIG. A heat generation layer 413E as an example of the heat generation unit is provided.
The base layer 413D as an example of the support substrate has a structure in which an insulating layer made of glass or the like is laminated on a base material made of SUS, alumina, or the like. The thickness of the base layer 413D is constant over the width direction of the fixing belt 411. In other words, the thickness of the base layer 413D is equal at both ends and the center in the width direction of the fixing belt 411. In addition, the heat capacity of the base layer 413D is equal at both ends and the center in the width direction of the fixing belt 411.

  Further, the heat source 413 has an insulating property and includes a protective layer 413F that covers the heat generating layer 413E. The protective layer 413F is formed of, for example, a glass fired body.

As shown in FIG. 3, the heat generating layer 413E is provided along the longitudinal direction of the heating source 413 (the width direction of the fixing belt 411).
The heat generating layer 413E is formed so that the length along the width direction of the fixing belt 411 is shorter than the heat source 413. Thereby, non-heat-generating regions 413G where the heat-generating layer 413E is not provided are formed at both ends in the longitudinal direction of the heat source 413.
Further, the heat generating layer 413E has a length (DE; see FIG. 5 described later) along the width direction of the fixing belt 411, and the maximum width of the sheet P conveyed to the nip portion N (see FIG. 2A). Is longer than the maximum sheet passing area Fa (an example of the maximum transport area; see FIG. 5 described later).

Further, as shown in FIGS. 2A and 2B, a support member 414 that supports the heat source 413 is provided on the inner side of the fixing belt 411 and on the opposite surface 413 </ b> B side of the heat source 413. .
Further, a heat supply member 415 is provided between the opposite surface 413 </ b> B of the heating source 413 and the support member 414.

The heat supply member 415 is an example of a heat supply member or a heat conduction member, is disposed in contact with the opposite surface 413B of the heating source 413, and receives heat from the heating source 413. In the description of the present embodiment, the contact arrangement means that the heat supply member 415 is laminated directly on the opposite surface 413B of the heating source 413, for example, via grease having thermal conductivity. Also includes form.
Further, as shown in FIG. 3, the heat supply member 415 is formed in a long shape and extends in a direction perpendicular to the belt moving direction which is the moving direction of the fixing belt 411. In other words, the heat supply member 415 is installed so as to extend in the width direction of the fixing belt 411.
The shape of the heat supply member 415 of this embodiment will be described in detail later.

The heat supply member 415 supplies the heat of the portion of the heating source 413 where the temperature is high to the portion of the heating source 413 where the temperature is low.
When the width of the sheet P on which the fixing process is performed is small, the temperature of both ends in the longitudinal direction of the heating source 413 (the portion of the heating source 413 that does not contact the sheet P; the non-sheet passing region) rises. The temperature of the part increases. In such a case, temperature unevenness occurs in the heat source 413 and the fixing belt 411, and there is a possibility that fixing unevenness may occur during the fixing process of the paper P having a large width.
When the heat supply member 415 is provided, the heat of the portion of the heating source 413 where the temperature is high is supplied to the portion of the heating source 413 where the temperature is low, and the temperature unevenness of the heating source 413 and the fixing belt 411 is uneven. Reduced.

When the heat supply member 415 that receives heat from the heat source 413 is provided in the fixing device 40, the heat that has moved from the heat source 413 to the heat supply member 415 is supplied from a portion having a high temperature to a portion having a low temperature. At the same time, it is diffused outside the heat supply member 415. When the heat supply member 415 has an elongated shape, heat diffusion is likely to occur particularly at both ends in the longitudinal direction of the heat supply member 415 (the width direction of the fixing belt 411). For this reason, when the thickness of the heat supply member 415 is constant over the longitudinal direction, for example, when the power source of the heating source 413 is turned on and heating of the fixing belt 411 is started by the heating source 413, There may be a phenomenon in which the temperatures at both ends of the source 413 and the fixing belt 411 are lower than those at the center.
In particular, when the configuration in which the heating source 413 and the heat supply member 415 are opposed to the pressure roll 46 via the fixing belt 411, the heat from the heating source 413 is conducted to the pressure roll 46 via the fixing belt 411. To do. For this reason, when the heat source 413 is started, the temperatures at both ends of the heat source 413 and the fixing belt 411 are likely to be lowered.
In the present embodiment, the thickness of the heat supply member 415 is the thickness in the direction intersecting the width direction and the moving direction of the fixing belt 411, and the thickness in the stacking direction of the heat supply member 415 with respect to the heating source 413. means.

  FIG. 4 is a diagram illustrating the configuration of the fixing device 40 (see FIG. 2A) of the comparative example and the temperature distribution of the fixing belt 411 (see FIG. 2A). Here, as a configuration of the fixing device 40, a view in which the heating source 413 and the heat supply member 415 are viewed from the moving direction of the fixing belt 411 is illustrated. Further, as the temperature distribution of the fixing belt 411, the temperature distribution along the width direction of the fixing belt 411 when the heating source 413 is started is shown.

The fixing device 40 of this comparative example includes a heating source 413 and a heat supply member 415 that receives heat from the heating source 413. The heat supply member 415 of the comparative example has a constant thickness over the width direction of the fixing belt 411. In other words, in the heat supply member 415 of the comparative example, the thickness of the heat supply member 415 is equal at both ends and the center in the width direction of the fixing belt 411. Further, the heat supply member 415 of the comparative example has a constant thickness, so that the heat capacities are equal at both ends and the center in the width direction of the fixing belt 411.
In this comparative example, the heat supply member 415 reduces the temperature unevenness of the heating source 413 and the fixing belt 411 when the fixing process is performed on the sheet P having a large width after the fixing process is performed on the sheet P having a small width. .

  On the other hand, in the fixing device 40 of this comparative example, as shown in FIG. 4, the temperature at both ends in the width direction of the fixing belt 411 is compared with the center in the width direction when the heating source 413 is started. Lower. That is, as described above, in the long heat supply member 415, heat diffusion is likely to occur at both ends as compared with the central portion. For this reason, when the thickness and heat capacity of the heat supply member 415 are constant over the width direction, the temperature of the fixing belt 411 at both ends in the width direction where heat diffusion is likely to occur when the heating source 413 is started up. Becomes lower.

On the other hand, in the present embodiment, the thickness of the heat supply member 415 is varied in the width direction of the fixing belt 411, thereby suppressing a temperature drop at both ends in the width direction of the fixing belt 411.
FIG. 5 is a diagram illustrating the configuration of the heating source 413 and the heat supply member 415 of the present embodiment. Here, the heat source 413 and the heat supply member 415 are viewed from the moving direction of the fixing belt 411.
Hereinafter, the configuration of the heat supply member 415 of the present embodiment will be described with reference to FIG. 5 and FIG. 3 described above.

The heat supply member 415 of the present embodiment is configured by two plate-like members having different lengths along the width direction of the fixing belt 411. That is, the heat supply member 415 includes a first heat supply plate 415A stacked on the opposite surface 413B of the heating source 413, and a fixing belt compared to the first heat supply plate 415A stacked on the first heat supply plate 415A. 411 has a second heat supply plate 415B having a short length along the width direction. In the heat supply member 415, grease 415C as an example of a viscous liquid having thermal conductivity is applied between the first heat supply plate 415A and the second heat supply plate 415B.
In the following description, the width direction of the fixing belt 411 may be simply referred to as “width direction”.

  Here, in this example, the first heat supply plate 415A and the second heat supply plate 415B are not bonded to each other, and supported by the support member 414 (see FIG. 2B), the grease 415C is Are in close contact with each other. Similarly, the first heat supply plate 415 </ b> A and the opposite surface 413 </ b> B of the heating source 413 are not bonded to each other but are in close contact with each other by being supported by the support member 414. In addition, although illustration is omitted, in order to improve the adhesion between the first heat supply plate 415A and the opposite surface 413B of the heating source 413, between the first heat supply plate 415A and the opposite surface 413B of the heating source 413, A viscous liquid such as grease having high thermal conductivity may be applied.

  The first heat supply plate 415A and the second heat supply plate 415B are made of a metal material having high thermal conductivity such as aluminum or copper. In this example, the first heat supply plate 415A and the second heat supply plate 415B are made of the same material.

The first heat supply plate 415A and the second heat supply plate 415B are formed to extend in the width direction of the fixing belt 411. Further, both the first heat supply plate 415 </ b> A and the second heat supply plate 415 </ b> B have a rectangular shape having a long diameter in the width direction of the fixing belt 411.
In this example, the first heat supply plate 415A and the second heat supply plate 415B have the same thickness. Further, in this example, the lengths of the first heat supply plate 415A and the second heat supply plate 415B along the moving direction of the fixing belt 411 are formed to be equal to the length along the moving direction of the heating source 413. .

As described above, the first heat supply plate 415A is stacked on the opposite surface 413B of the heating source 413 directly or via a viscous liquid having high thermal conductivity.
As shown in FIG. 5, the length DA of the first heat supply plate 415A in the width direction is formed longer than the length DE of the heat source 413 in the width direction of the heat generating layer 413E. The length DA of the first heat supply plate 415A in the width direction is shorter than the length of the base layer 413D in the heating source 413 in the width direction. Then, both end portions in the width direction of the first heat supply plate 415A are opposed to both end portions in the width direction of the heat generation layer 413E and the non-heat generation region 413G in the heating source 413.

Further, as described above, the second heat supply plate 415B is stacked on the first heat supply plate 415A via the grease 415C. In this example, the second heat supply plate 415B is stacked at the center in the width direction of the first heat supply plate 415A.
The length DB in the width direction of the second heat supply plate 415B is shorter than the length DA of the first heat supply plate 415A. The length DB in the width direction of the second heat supply plate 415B is an example of the minimum sheet passing area Fb (an example of the minimum conveying area) that is the minimum width of the sheet P conveyed to the nip portion N (see FIG. 2A). ) And shorter than the maximum sheet passing area Fa which is the maximum width of the sheet P conveyed to the nip portion N.

  In the heat supply member 415 of the present embodiment, the first heat supply plate 415A and the second heat supply plate 415B are stacked via the highly heat conductive grease 415C, so that the first heat supply plate 415A and the second heat supply plate 415B are stacked. It is suppressed that a gap is generated between the heat supply plate 415B and the thermal conductivity is lowered. As a result, heat is quickly transferred between the first heat supply plate 415A and the second heat supply plate 415B. The first heat supply plate 415 </ b> A and the second heat supply plate 415 </ b> B cooperate to supply the heat of the portion of the heating source 413 where the temperature is high to the portion of the heating source 413 where the temperature is low. .

In the heat supply member 415 of the present embodiment, the length DB of the second heat supply plate 415B is formed shorter than the length of the first heat supply plate 415A, so that the first heat supply plate 415A in the width direction is formed. Regions where the second heat supply plate 415B is not stacked are formed at both ends.
When viewed as the heat supply member 415 as a whole, the thickness of both end portions in the width direction of the heat supply member 415 (thickness of the first heat supply plate 415A) is equal to the thickness of the central portion in the width direction (first heat supply plate 415A and It is thinner than the total thickness of the second heat supply plate 415B. In addition, in the heat supply member 415 of the present embodiment, the heat capacity at both end portions in the width direction is smaller than that in the center portion in the width direction because the thickness has the above relationship.
In the present embodiment, the both ends of the heat supply member 415 in the width direction mean regions that are located at both ends of the heat supply member 415 in the width direction and have a predetermined length in the width direction. Similarly, the center portion of the heat supply member 415 in the width direction means a region located at the center of the heat supply member 415 in the width direction and having a predetermined length in the width direction.

FIG. 6 is a diagram showing the temperature distribution of the fixing belt 411 of the present embodiment. Here, as the temperature distribution of the fixing belt 411, the temperature distribution along the width direction of the fixing belt 411 when the heating source 413 is started up is shown.
In the present embodiment, the heat capacity of both end portions in the width direction of the heat supply member 415 is lower than that in the center portion in the width direction, so that the fixing of the comparative example shown in FIG. Compared with the device 40, the amount of heat conducted from the heating source 413 to the heat supply member 415 is reduced at both ends in the width direction. As a result, the amount of heat supplied from the heating source 413 to the fixing belt 411 is increased at both ends in the width direction as compared with the fixing device 40 of the comparative example shown in FIG. And as shown in FIG. 6, the temperature fall in the both ends in the width direction of the fixing belt 411 is suppressed.

Further, in the present embodiment, by using two members, the first heat supply plate 415A and the second heat supply plate 415B, the thickness in the width direction of the heat supply member 415 is made different between the central portion and both end portions. ing. Thereby, for example, compared with the case where the heat supply member 415 is manufactured by cutting one metal plate or the like, the heat supply member 415 having a different thickness or heat capacity in the width direction can be easily manufactured.
For example, the heat capacity of the heat supply member 415 can be easily adjusted by changing the thickness of the first heat supply plate 415A or the second heat supply plate 415B, the length in the width direction, and the like.

  Here, as described above, the length DA of the first heat supply plate 415A in the width direction is longer than the length DE of the heat source 413 in the width direction of the heat generating layer 413E. That is, the heat supply member 415 faces the heat generation layer 413E of the heating source 413 over the entire region in the width direction. Accordingly, for example, heat generated at both ends of the heat generating layer 413E can be supplied to the low temperature portion by the heat supply member 415 during the fixing process of the paper P having a small width. Then, for example, the heating in the non-sheet passing region during the fixing process of the paper P having a small width as compared with the case where the length DA in the width direction of the first heat supply plate 415A is shorter than the length DE of the heat generating layer 413E. The temperature rise of the source 413 is suppressed.

  Further, as described above, the length DB in the width direction of the second heat supply plate 415B is longer than the minimum sheet passing area Fb. In the heat supply member 415, a thick region (a region where the first heat supply plate 415A and the second heat supply plate 415B are stacked) is disposed so as to straddle both ends of the minimum sheet passing region Fb. The This makes it easier for the heat source 413 to supply the heat of the non-sheet passing area to the low temperature portion during the fixing process of the minimum width paper P that is likely to cause a temperature increase in the non-sheet passing area. As a result, the temperature unevenness of the heating source 413 and the fixing belt 411 is suppressed as compared with the case where the length DB of the second heat supply plate 415B is shorter than the minimum sheet passing area Fb.

  Furthermore, the length DB in the width direction of the second heat supply plate 415B is shorter than the maximum sheet passing area Fa. In the heat supply member 415, the thin region (the region where the second heat supply plate 415B is not stacked) is disposed so as to straddle both ends of the maximum sheet passing region Fa. Thereby, compared with the case where the length DB of the second heat supply plate 415B is longer than the maximum sheet passing area Fa, the temperature drop at both ends of the maximum sheet passing area Fa when the heating source 413 is started up. Is suppressed.

  Furthermore, in the present embodiment, the thicknesses of the first heat supply plate 415A and the second heat supply plate 415B are constant along the width direction. In addition, the thickness of the region of the heat supply member 415 that faces the minimum sheet passing region Fb is constant along the width direction. Thereby, for example, compared to the case where the thickness of the region facing the minimum sheet passing region Fb in the heat supply member 415 varies in the width direction, the fixing process for the sheet P having a small width is performed on the sheet P. The unevenness of the supplied heat is suppressed.

  In this example, the heat supply member 415 is configured by two plate-shaped members (first heat supply plate 415A and second heat supply plate 415B), but three or more members may be used. That is, by laminating three or more plate-like members having different lengths in the width direction, the thickness of the heat supply member 415 is gradually reduced from the center portion in the width direction toward both ends. Can do.

Here, as a method for suppressing a decrease in temperature at both ends in the width direction that occurs when the heating source 413 is started up, the thickness of the heat supply member 415 is different in the width direction as in the present embodiment. In addition to the above, for example, a method of varying the thickness of the heat source 413 itself in the width direction can be mentioned. More specifically, there is a method in which the thickness of the base layer 413D of the heat source 413 is varied in the width direction. However, if the thickness of the heat source 413 is varied in the width direction, the heat generation efficiency by the heat source 413 may fluctuate in the width direction, which may cause uneven temperature in the fixing belt 411 during the fixing process. Further, as described above, since the heat source 413 includes the base layer 413D, the heat generating layer 413E, and the protective layer 413F, when the thickness is varied in the width direction, the configuration tends to be more complicated.
On the other hand, in this embodiment, the thickness of the heat supply member 415 arranged in contact with the heating source 413 is varied in the width direction, so that the heating source 413 can be started with a simpler configuration. It is possible to suppress a decrease in temperature at both ends in the width direction.

(Embodiment 2)
Subsequently, Embodiment 2 of the present invention will be described. FIG. 7 is a diagram illustrating the configuration of the heat source 413 and the heat supply member 415 according to the second embodiment. FIG. 7 illustrates the heat source 413 and the heat supply member 415 as viewed from the moving direction of the fixing belt 411 (see FIG. 2A).
In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted here.

Unlike the heat supply member 415 according to the first embodiment, the heat supply member 415 according to the second embodiment includes a single plate-like member.
As shown in FIG. 7, the heat supply member 415 according to the second embodiment is adjacent to the thick portion 415 </ b> D having a predetermined thickness located in the center portion in the width direction, and both end portions in the width direction of the thick portion 415 </ b> D. A thin portion 415E having a smaller thickness than the thick portion 415D is provided. In this example, the thickness of the thick part 415D is twice the thickness of the thin part 415E.
And in the heat supply member 415 of Embodiment 2, the heat capacity of the thin part 415E located in the both ends of the width direction is low compared with the thick part 415D located in the center part of the width direction.

As shown in FIG. 7, the length DA in the width direction of the heat supply member 415 of the present embodiment is formed to be longer than the length DE in the width direction of the heat generating layer 413E in the heating source 413. The length DA of the heat supply member 415 in the width direction is shorter than the length of the base layer 413D in the heating source 413 in the width direction.
The length DB of the thick portion 414D of the heat supply member 415 is longer than the minimum sheet passing area Fb and shorter than the maximum sheet passing area Fa.

  Also in this embodiment, as in the first embodiment, the heat capacity of the thin portions 415E located at both ends in the width direction of the heat supply member 415 is lower than that of the thick portions 415D located in the center in the width direction. When the heating source 413 is started up, the amount of heat conducted from the heating source 413 to the heat supply member 415 decreases at both ends in the width direction. As a result, the amount of heat supplied from the heating source 413 to the fixing belt 411 is increased at both ends in the width direction as compared with the fixing device 40 of the comparative example shown in FIG. And the temperature fall in the both ends in the width direction of the fixing belt 411 is suppressed.

The heat supply member 415 of the present embodiment including the thick part 415D and the thin part 415E can be obtained, for example, by cutting a metal plate.
Here, when the heat supply member 415 is configured by a plurality of members as in the first embodiment, when the adhesion between the plurality of members decreases, heat conduction between the plurality of members may be hindered. In this case, it may be difficult to supply the heat of the high temperature part to the low temperature part.

  On the other hand, in the present embodiment, the heat supply member 415 is configured by a single member, so that heat conduction is more efficient in the heat supply member 415 than, for example, when the heat supply member 415 is configured by a plurality of members. Done. Thereby, after the fixing process of the paper P having a small width, the temperature unevenness of the heating source 413 and the fixing belt 411 is further suppressed during the fixing process of the paper P having a large width.

(Embodiment 3)
Subsequently, Embodiment 3 of the present invention will be described. FIG. 8 is a diagram illustrating the configuration of the heat source 413 and the heat supply member 415 according to the third embodiment. FIG. 8 illustrates the heat source 413 and the heat supply member 415 as viewed from the moving direction of the fixing belt 411 (see FIG. 2A).
In the following description, the same reference numerals are used for the same configurations as those in the first and second embodiments, and the detailed description thereof is omitted here.

Similarly to the heat supply member 415 of the second embodiment, the heat supply member 415 of the third embodiment is composed of a single plate-like member.
As shown in FIG. 8, the heat supply member 415 according to the third embodiment is adjacent to the thick portion 415 </ b> D having a predetermined thickness located at the center portion in the width direction, and both end portions in the width direction of the thick portion 415 </ b> D. A thin portion 415F having a smaller thickness than the thick portion 415D is provided. In the heat supply member 415 of the third embodiment, the shape of the thin portion 415F is different from the thin portion 415E (see FIG. 7) in the heat supply member 415 of the second embodiment.

That is, in the heat supply member 415 of the third embodiment, the thin portion 415F is formed so that the thickness continuously decreases from the side adjacent to the thick portion 415D toward both end portions in the width direction. In other words, the thickness of the thin portion 415F gradually decreases from the central portion in the width direction toward both ends in the width direction.
In addition, in the heat supply member 415 of the third embodiment, the thin portion 415F is opposed to both end portions in the width direction of the heat generating layer 413E of the heating source 413. Thereby, as for the heat supply member 415, the thickness of the area | region which opposes the both ends of the width direction in the heat generating layer 413E is thin continuously.

Since the heat supply member 415 of the third embodiment has the above shape, the heat capacity of the heat supply member 415 is suppressed from changing rapidly at the boundary between the thick portion 415D and the thin portion 415F.
Further, in the heat supply member 415, as described above, heat diffusion tends to occur at both ends in the width direction, and the temperature tends to decrease when the heating source 413 is started up. Therefore, the heat supply member 415 according to the third embodiment has a shape corresponding to the likelihood of heat diffusion by forming the thin portion 415F so that the thickness continuously decreases toward both ends in the width direction. Will have. Thereby, when the heat source 413 is started up, temperature drop at both ends in the width direction of the heat source 413 and the fixing belt 411 is suppressed. Then, for example, when the heating source 413 is started up, the temperature distribution of the fixing belt 411 can be made smoother in the width direction than in the case of using the heat supply member 415 of the second embodiment.

(Embodiment 4)
Subsequently, Embodiment 4 of the present invention will be described. FIG. 9 is a view showing the configuration of the heat supply member 415 of the fourth embodiment, and is a perspective view of the heat supply member 415 as viewed from the side facing the heating source 413 (see FIG. 2B). It is.
In the heat supply member 415 according to the first to third embodiments, the thickness of both end portions in the width direction extends over the entire region in the moving direction of the fixing belt 411 (see FIG. 2A) as compared with the central portion in the width direction. However, the shape of the heat supply member 415 is not limited to this. That is, in the heat supply member 415, a region having a smaller thickness than the central portion in the width direction is formed in at least a part of both end portions in the width direction, and the heat capacity at both end portions in the width direction is the central portion in the width direction. What is necessary is just to have a shape which becomes small compared with.

  As shown in FIG. 9, the heat supply member 415 of the fourth embodiment has groove portions 415 </ b> H formed by notching members constituting the heat supply member 415 in the thickness direction at both ends in the width direction. doing. In the heat supply member 415, the thickness of the region where the groove 415H is formed is thinner than the region where the groove 415H is not formed. In addition, the groove part 415H is formed in a part of movement direction among the both ends of the heat supply member 415.

And the heat supply member 415 of Embodiment 4 has the groove part 415H formed in the both ends of the width direction, and the heat capacity in the both ends of the width direction is small compared with the center part of the width direction. Thereby, when the heat source 413 is started up, temperature drop at both ends in the width direction of the heat source 413 and the fixing belt 411 is suppressed.
In the heat supply member 415 of the fourth embodiment, the groove 415H is formed in a partial region in the movement direction at both ends in the width direction, so that the thickness of the entire region in the movement direction is reduced at both ends in the width direction. Compared with the case where it has, the fall of the intensity | strength in the both ends of the width direction is suppressed.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 40 ... Fixing device, 41 ... Fixing belt module, 46 ... Pressure roll, 411 ... Fixing belt, 413 ... Heat source, 413E ... Heat generating layer, 415 ... Heat supply member, 415A ... first heat supply plate, 415B ... second heat supply plate

Claims (13)

A contact member that contacts the recording material being conveyed;
A heating source including a heat generating portion extending in a width direction intersecting a recording material conveyance direction, and having a facing surface and an opposite surface facing the contact member;
A portion that extends in the width direction and is in contact with the opposite surface of the heat source, where the thickness at both ends in the width direction is thinner than the thickness at the center in the width direction, and the temperature of the heat source is high And a heat supply member for supplying the heat to a portion having a low temperature. The heat source further includes a support substrate that has a lower thermal conductivity than the heat supply member, extends in the width direction, supports the heat generating unit, and contacts the heat supply member.
2. The fixing device according to claim 1, wherein the thickness of the support substrate is the same at both end portions and the center portion in the width direction.   The heat supply member has a length along the width direction that is longer than that of the heat generating portion, and a thickness of a region facing both ends of the heat generation portion in the width direction is thinner than a center portion in the width direction. The fixing device according to claim 1, wherein the fixing device is configured as follows.   The heat supply member includes a first heat supply plate disposed in contact with the opposite surface of the heating source so as to face the entire region in the width direction of the heat generating portion, and the width direction of the first heat supply plate. The fixing device according to claim 1, further comprising: a second heat supply plate that is stacked at a central portion and has a shorter length in the width direction than the first heat supply plate.   The fixing device according to claim 4, wherein the first heat supply plate and the second heat supply plate of the heat supply member are stacked via a viscous liquid having thermal conductivity.   The fixing device according to claim 1, wherein the heat supply member has a thickness that is continuously reduced toward both ends in the width direction.   The heat supply member has a longer length along the width direction than the heat generating portion, and a thickness of a region facing both ends of the heat generating portion in the width direction is continuously reduced. The fixing device according to claim 6. A recording material having a different length in the width direction is conveyed to the contact member,
2. The heat supply member according to claim 1, wherein a thickness of a region facing both ends in the width direction of a maximum conveyance region in which the recording material having the longest length in the width direction is conveyed is thin. The fixing device according to 1.   9. The heat supply member according to claim 8, wherein the thickness of both end portions in the width direction is thinner than the minimum conveyance area in which the recording material having the shortest length in the width direction is conveyed. Fixing device.   The fixing device according to claim 9, wherein the heat supply member has a constant thickness at least in a region facing the minimum conveyance region. A pressure member that is disposed in contact with the contact member and pressurizes the recording material passing between the contact member;
The fixing device according to claim 1, wherein the heat source and the heat supply member are provided at positions facing the pressure member via the contact member. A contact member that contacts the recording material being conveyed;
A heat generating portion extending in a width direction intersecting the recording material conveyance direction; and a support substrate having a plate-like shape having the same thickness in the width direction and supporting the heat generating portion, and faces the contact member. A heating source having an opposing surface and an opposing surface;
It is made of a material having a higher thermal conductivity than the support substrate, extends in the width direction and is arranged in contact with the opposite surface of the heating source, and the heat capacity at both ends in the width direction is compared with the center portion in the width direction. And a small heat conducting member.   An image forming means for forming an image on a recording material, and a fixing device for fixing an image formed on the recording material by the image forming means to the recording material, wherein the fixing device is any one of claims 1 to 12. An image forming apparatus comprising the fixing device described in 1.

Images