JP6766237B2 - Image heating device - Google Patents

Description

The present invention relates to an image heating device suitable for use as a fixing device mounted on an image forming device such as a copying machine such as an electrophotographic system or a laser beam printer.

The image heating device includes a fixing device that heats and fixes an unfixed toner image formed on a recording material (paper, etc.) to the recording material, a toner image that is assumed to be attached to the recording material, or a toner image that has been heat-fixed once again. Examples thereof include an image quality modifier that improves glossiness by heating and pressurizing. Hereinafter, the fixing device will be described.

As the fixing device, devices such as a thermal roller method and a film (belt) heating method have been conventionally known.

The film heating type fixing device (Patent Document 1) includes a heating heater having a resistance heating element on a ceramic substrate, a fixing film that is heated and rotated while in contact with the heating heater, and a heating heater and a nip portion via the fixing film. It has a pressure roller or the like that forms a film. The recording material (hereinafter referred to as paper) that supports the unfixed toner image is heated while being sandwiched and conveyed by the nip portion, whereby the toner image is fixed on the paper.

In a color image forming apparatus that superimposes toner images of a plurality of colors, a rubber layer may be provided on the fixing film in order to further mix the toner and improve the fixing image quality. In many monochrome image forming devices, a rubber layer is not provided in order to reduce the heat capacity of the fixing film as much as possible and accelerate the temperature rise. As the material of the fixing film, a metal material such as SUS having high strength and high thermal conductivity, a heat-resistant resin such as PI having a small heat capacity and good moldability, and the like are used.

In any case, the film heating type fixing device uses a film having a smaller heat capacity as the fixing member than the thermal roller of the thermal roller type fixing device, so that the time required to raise the fixing member to a predetermined temperature is shortened. be able to. In addition, since the rise time is short, it is not necessary to keep the fixing member warm during standby, and power consumption can be suppressed as low as possible.

A schematic diagram of a general heating heater used in a film heating type fixing device is shown in FIG. 15 (a). This figure shows the surface of a heater having resistance heating elements 201 and 202 that come into contact with the fixing film and heat the fixing film. The heating heater 200 often has a configuration in which two parallel resistance heating elements 201 and 202 are provided in series on a substrate 207 made of elongated ceramics via a conductor 203. Conductive electrodes 204 and 205 are provided at the ends of the resistance heating elements 201 and 202, respectively, and heat is generated by energizing the resistance heating elements 201 and 202 from the electrode portions 204 and 205, respectively.

Since the heating heater 200 is brought into contact with the inner surface of the fixing film having a small heat capacity to directly heat the fixing film, the fixing film and the pressure roller are uniformly and quickly raised in temperature in the longitudinal direction. However, when paper (small size paper) having a width relatively narrow with respect to the longitudinal width of the resistance heating elements 201 and 202 is continuously passed, the pressurizing roller 200 is not passed through the fixing film. The temperature of the paper area becomes higher than that of the paper passing area.

FIG. 15B shows the temperature distribution in the longitudinal direction of the pressurizing roller when a small-sized paper is passed through the paper. If small-sized paper is continuously passed through, the temperature of the pressurizing roller in the non-passing area rises. Therefore, the pressurizing roller is heated at intervals so as not to exceed the heat resistant temperature of the pressurizing roller. It is controlled to level the temperature of the paper. Therefore, one of the problems in the film heating type fixing device is that the productivity of small size paper is lowered.

In order to increase the productivity of this small size paper, as shown in FIG. 15 (c), the heat conductive member 208 is provided on the surface (back surface of the substrate) opposite to the surface of the resistance heating elements 201 and 202 of the substrate 207. It may have a configuration (Patent Document 2).

The back surface of the heater substrate 207 may be provided with a silver paste having a thermal conductivity higher than that of the heater substrate as the heat conductive member 208, or may come into contact with an aluminum plate or the like. Although the aluminum plate has a lower thermal conductivity than silver, it has a relatively high thermal conductivity among metals and has the advantage of being inexpensive to install. By providing such a heat conductive member 208 on the back surface of the heater, the heat in the non-passing region when the small size paper is passed can be equalized in the longitudinal direction of the heater, and the productivity of the small size paper is improved. It becomes possible.

However, when the heat conductive member 208 is provided in the heater 200 in this way, the heat conductive member 208 is deformed due to the difference between the thermal expansion amount of the heater 200 (heater substrate 207) and the thermal expansion amount of the heat conductive member 208. Sometimes.

When the heater 200 repeats heating and cooling (heat cycle), it repeatedly expands and contracts in a state where there is a difference in thermal expansion, so that stress is repeatedly applied to the heat conductive member, and heat conduction of weak materials such as aluminum plates. It may be deformed when used for the member 208.

If the heat conductive member 208 is deformed, the adhesion to the heater 200 is lowered, and the temperature leveling effect of the heat conductive member 208 may be lowered. In order to prevent the deformation of the heat conductive member 208 due to this heat cycle, it is conceivable that the deformation due to the heat cycle as described above can be suppressed by using the heat conductive member 208 divided into a plurality of members in the longitudinal direction of the heater. By dividing the size of the heat conductive member 208 into a plurality of members to shorten the width of one member and reducing the amount of expansion of one member, the stress applied to the heat conductive member 208 due to the heat cycle is relaxed, and the heat conductive member The deformation of 208 can be suppressed.

JP-A-04-044075 JP-A-11-260533

However, in the configuration in which the heat conductive member 208 is divided into a plurality of members in the longitudinal direction and provided on the back surface of the heater 200 as described above, the following events may occur.

FIG. 16A shows a schematic view of a configuration in which the heat conductive member 208 is divided into two at the central portion of the longitudinal portion. Q is the first region where the heat conductive member 208 is in contact with the back surface of the heater. S is a mutual separation portion of the divided heat conductive members 208. This separation portion S is a second region where the heat conductive member 208 is not in contact with the back surface of the heater. In this case, temperature unevenness in the longitudinal direction may occur in the fixing film in the first region Q and the second region S, and image defects such as gloss unevenness may occur in the fixed image. This gloss unevenness is particularly remarkable when the heat conductive member 208 is started up from a cold state (cold state).

FIG. 16B shows a diagram showing the temperature unevenness of the fixing film when the fixing device using the heater 200 having the heat conductive member divided configuration of FIG. 16A is started up from the cold state.
As shown in this figure, in the longitudinal direction of the heater, the heater portion corresponding to the second region S does not take heat to the heat conductive member 280, so that the heater portion corresponding to the first region Q is used. However, the temperature becomes high. Therefore, the temperature of the fixing film portion and the pressure roller portion corresponding to the second region S of the heater 200 also becomes high. Then, in the fixed image, the gloss of the portion corresponding to the second region S is increased, and the image may have gloss streaks in the vertical direction (paper transport direction).

When the heat conductive member 208 is sufficiently warmed (hot state), the heat of the heater 200 is unlikely to escape to the heat conductive member 208, so that an image of uneven gloss due to temperature unevenness in the longitudinal direction is unlikely to occur. Further, even when a fixing film provided with a rubber layer used in a color image forming apparatus as described above is used, the temperature unevenness in the longitudinal direction is alleviated by the heat capacity of the rubber layer, so that this gloss unevenness image is relatively unlikely to occur. No.

It has been found that when a fixing film having a small heat capacity, which is generally used in a monochrome image forming apparatus, is used, temperature unevenness in the longitudinal direction is likely to occur when starting up from a cold state, so that this glossy uneven image is likely to occur. ing.

In order to suppress the temperature unevenness in the longitudinal direction that occurs when starting up from this cold state, it is conceivable to adopt a configuration that suppresses the amount of heat generated by the resistance heating element portion corresponding to the second region S of the heater 200. Be done. With this configuration, uneven gloss in the cold state can be suppressed.

However, when the heat conductive member 208 becomes sufficiently warm and hot, the amount of heat generated in the portion of the heater 200 corresponding to the second region S becomes insufficient. Therefore, on the contrary, in the fixed image, the gloss of the portion corresponding to the second region S may be lowered, resulting in an image having gloss streaks in the vertical direction.

Therefore, an object of the present invention is to solve the above-mentioned problems in a film heating type image heating device. That is, the introduction of a recording material having a width smaller than the maximum width size of the recording material that can be used in the device suppresses the temperature rise of the non-passing portion to improve the productivity, and the image defect of gloss unevenness from the cold state to the hot state. It is to provide an image heating apparatus which does not generate.

A typical configuration of the image heating device according to the present invention for achieving the above object is
A heating member having an elongated substrate and a resistance heating element formed on the substrate along the longitudinal direction to generate heat by energization.
An endless belt whose inner peripheral surface slides on the first surface of the heating member, which is rotatable around the heating member,
A heat conductive member having a higher thermal conductivity than the substrate, which is in contact with the second surface of the heating member.
A guide member that supports the rotation of the endless belt by coming into contact with the endless belt.
A nip portion forming member that contacts the outer peripheral surface of the endless belt to form a nip portion ,
The a, an image heating apparatus for heating while nipping and conveying the recording material bearing the images,
In the direction orthogonal to the transport direction of the recording material in the transport path surface of the recording material, the heat conductive member and the heating member are within the region of the passage region of the recording material having the maximum width size that can be transported by the image heating device. The first region in contact is wider than the second region in which the heat conductive member is not in contact.
The convex portion of the guide member, which protrudes upstream in the transport direction of the recording material and is in contact with the endless belt, is provided at a position corresponding to the second region.

According to the present invention, the temperature rise of the non-passing portion due to the introduction of the recording material having a width smaller than the maximum width size recording material that can be used in the apparatus is suppressed to improve the productivity, and the gloss is increased from the cold state to the hot state. It is possible to provide an image heating device that does not cause uneven image defects.
It can be suppressed.

FIG. 5 is a schematic cross-sectional view of a main part of the fixing device according to the first embodiment. It is also a front schematic view of the main part. (A) is a schematic front view of the main part in a vertical section, and (b) is a schematic view of a part of the main part notched. It is a disassembled perspective schematic diagram of a film unit. It is a block diagram of a heater. (A) is a schematic cross-sectional view of a main part of the fixing device in the second embodiment, and (b) is a schematic perspective view of a heater holder. It is a block diagram which shows the structure of the fixing device in Example 2. FIG. It is explanatory drawing of another structure of the fixing device in Example 2. FIG. It is a configuration explanatory view of the fixing device when the heat conduction member is divided into three. It is explanatory drawing of another structure of the fixing device. It is explanatory drawing of the other structure of the fixing device. It is explanatory drawing of the other structure of the fixing device. It is explanatory drawing of the other structure of the fixing device. It is the schematic of the image forming apparatus example. It is explanatory drawing of a general heater. It is explanatory drawing of the temperature unevenness in the longitudinal direction of a fixing film when the heat conductive member is divided.

[Example 1]
First, the main body configuration of the image forming apparatus in the first embodiment will be described, and then the image heating apparatus (fixing apparatus) according to the present invention will be described in detail.

(Explanation of an example of an image forming apparatus)
FIG. 14 is a schematic view of the image forming apparatus 50 in the first embodiment. The image forming apparatus 50 is a monochrome printer using a transfer type electrophotographic process. Reference numeral 1 denotes a drum-type electrophotographic photosensitive member (hereinafter referred to as a drum) as an image carrier, which is rotationally driven at a predetermined peripheral speed (process speed) in the clockwise direction of arrow R1. A charger 2, an exposure device 3, a developing device 5, a transfer roller 10, and a photosensitive drum cleaner 16 are arranged around the drum 1 in order along the drum rotation direction as electrophotographic process means acting on the drum 1. Has been done.

In this example, the peripheral surface of the rotating drum 1 is uniformly charged to a predetermined potential of negative polarity by the charger 2. An image exposure is performed on the charged surface by the exposure apparatus 3. In this example, the exposure device 3 is a laser scanner, and the laser beam L modulated according to the electrical image information input from the external host device 500 (FIG. 2) such as a personal computer to the control unit (control circuit unit) 400 is emitted. The output is performed to scan and expose the charged surface of the drum 1. As a result, an electrostatic latent image corresponding to the exposure pattern is formed on the surface of the drum 1 (the surface potential of the exposed portion of the surface of the drum 1 rises).

The electrostatic latent image is developed as a toner image by the developer 5 containing black toner.
In this example, the toner is negatively charged, and the negative toner adheres only to the electrostatic latent image portion on the drum 1, and a toner image is formed on the drum 1.

On the other hand, the paper P is separately fed from the cassette 7 in which the sheet-shaped recording material (hereinafter referred to as paper) P is loaded and accommodated by the paper feed roller 4 at a predetermined control timing. The recording material P is not limited to paper. A sheet material other than paper, such as a resin sheet or coated paper, or a composite sheet material with paper may be used. The width or width size of the paper P is a dimension on the paper surface in a direction orthogonal to the paper transport direction (recording material transport direction). Further, the maximum width size paper that can be conveyed (usable) by the image forming apparatus or the fixing device is referred to as a large size paper, and the paper having a width smaller than this large size paper is referred to as a small size paper.

The paper P fed from the cassette 7 is conveyed by the transfer roller 6 to the transfer nip portion N, which is the contact nip portion between the drum 1 and the transfer roller 10, and is sandwiched and conveyed by the transfer nip portion N. While the paper P passes through the transfer nip portion N, a positive polarity transfer bias having a polarity opposite to that of the toner is applied to the transfer roller 10 from a power source (not shown). As a result, the toner image on the drum 1 side is sequentially transferred to the surface of the paper P at the transfer nip portion N.

The paper P that has passed through the transfer nip portion N is separated from the drum surface, transported to the fixing device 100, and subjected to the heat fixing treatment of the toner image. The paper P that has passed through the fixing device 100 is discharged to the discharge tray 9 on the upper surface of the printer by the paper discharge roller 8 as an image forming material. Further, the drum 1 after the paper is separated (after transfer) is made into a cleaning surface by removing the transfer residual toner on the surface by the photosensitive drum cleaner 16 having an elastic blade, and is repeatedly subjected to image formation.

(Overview of fixing device)
The fixing device 100 of this embodiment is a film (belt) heating type image heating device for the purpose of shortening the start-up time and reducing power consumption. FIG. 1 is a schematic cross-sectional view of a main part of the fixing device 100 in this embodiment. FIG. 2 is a front schematic view of a main part of the fixing device 100 as viewed from the direction of arrow A1 (paper transport direction) in FIG. FIG. 3A is a schematic front view of the vertical section, and FIG. 3B is a schematic view of a part of the main part of the fixing device 100 as viewed from the direction of arrow A2 in FIG. 1 (the fixing film 112 is cut out). There is). FIG. 4 is an exploded perspective schematic view of the film unit 101.

Here, in the fixing device 100, the front side is the side on which the paper P is introduced. The back side is the opposite side. The left and right are the left (one end side) and the right (the other end side) when the fixing device 100 is viewed from the front side. The upstream side and the downstream side are the upstream side and the downstream side with respect to the paper transport direction A1. The drawings are schematic views of the fixing device 100 or its constituent members, and do not correspond to the actual dimensions of the constituent members described in the specification in proportion to each other.

The fixing device 100 in this embodiment has a film unit 101 that is long in the left-right direction and includes a tubular fixing film 112 having flexibility as an endless belt. Further, it is provided with a pressure roller 110 which is arranged substantially parallel to the film unit 101 and has elasticity as a rotating body which comes into contact with the outer surface (outer peripheral surface) of the fixing film 112 to form a nip portion No.

The film unit 101 includes the fixing film 112, a heating heater 113 as a heating member, a heater holder 130 for holding the heating heater 113, a stay 120 for supporting the heater holder 130, left and right flange members 150L, 150R, and the like.

The heating heater 113 is a ceramic heater having an elongated substrate 207 (FIG. 5) and two parallel resistance heating elements 201 and 202 formed on the substrate along the longitudinal direction to generate heat by energization, and is a resistance heating element 201. , 202 is energized to raise the temperature sharply. The heating heater 113 is fitted and held in a groove hole 130a formed along the length of the heater holder 130 with the surface side (first surface) having the resistance heating elements 201 and 202 facing outward. ..

The heater holder 130 is preferably made of a material having a low heat capacity so as not to take heat from the heater 113. In this embodiment, a glass balloon is put in a liquid crystal polymer (LCP) which is a heat resistant resin to suppress the thermal conductivity and the heat capacity. I used the one. The heater holder 130 is supported by an iron stay 120 from the side opposite to the heater 113 in order to give strength. The fixing film 112 is loosely fitted between the left and right flange members 150L and 150R with respect to the assembly of the heating heater 113, the heater holder 130, and the stay 120.

The left and right flange members 150L and 150R are symmetrically shaped bodies made of heat-resistant and electrically insulating resin, and are fitted and fixed at predetermined positions on the left end portion and the right end portion of the stay 120, respectively. The left and right flange members 150L and 150R each have a flange portion 150a as a first regulating portion for receiving the end portion of the fixing film. In addition, each has an inner surface guide portion 150b as a second regulating portion that is internally fitted to the left and right end portions of the fixing film 112. The film inner surface contact shape of the inner surface guide portion 150b in the film rotation direction is substantially a semicircular shape.

Both ends of the core metal 117 of the pressure roller 110 are rotatably held between the left and right side plates of the apparatus chassis (not shown) via bearing members. The film unit 101 is arranged substantially in parallel with the heating heater 113 facing the pressurizing roller 110.

Then, the pressure springs 103L and 103R are between the left and right ends of the stay 120 protruding outward from the left and right flange members 150L and 150R and the left and right fixed spring receiving members 102L and 102R on the device chassis side, respectively. Has been reduced. Due to the contraction reaction force of this spring, the stay 120 is pressed and urged with a predetermined pressing force in the direction toward the pressure roller 110.

Due to this pressing force, the surface (first surface) of the heater 113 held by the heater holder 130 and a part of the surface of the heater holder 130 pressurize the pressurizing roller 110 with the fixing film 112 sandwiched between them. It is pressure-welded against the elasticity of the elastic layer 116 of the roller 110.

As a result, the surface side of the heating heater 113 comes into contact with the inner surface of the fixing film 112, and forms an inner surface nip Ni that heats the fixing film 112 from the inner surface. Then, the pressurizing roller 110 is pressed against the heating heater 113 so as to sandwich the fixing film 112, and a fixing nip having a predetermined width in the paper transport direction A1 is provided between the outer surface of the fixing film 112 and the pressurizing roller 110. (Nip portion) No is formed.

The pressurizing roller 110 receives the driving force of the motor (rotating means) M controlled by the control unit 400 via a power transmission mechanism (not shown) and is rotationally driven at a predetermined speed in the counterclockwise direction of arrow R2 in FIG. Will be done. In this embodiment, the pressure roller 110 rotates at a surface moving speed of 200 mm / sec.

Along with the rotational drive of the pressurizing roller 110, the fixing film 112 moves around the assembly of the heating heater 113, the heater holder 130, and the stay 120 while the inner peripheral surface of the fixing film 112 touches and slides on the surface of the heating heater at the fixing nip No. It rotates clockwise. In order to facilitate the rotation of the fixing film 112, a lubricant (grease) may be interposed between the surfaces of the heater 113 and the heater holder 130 and the inner surface of the fixing film 112.

The flange members 150a of the left and right flange members 150L and 150R each regulate the offset movement in the left-right direction (width direction) accompanying the rotation of the fixing film 112 by receiving the end portion of the fixing film 112. Further, each of the inner surface guide portions 150b supports both ends of the fixing film 112 from the inner surface of the fixing film to support the rotation of the fixing film 112 (rotational trajectory determination).

As will be described later, the heating heater 113 is rapidly heated by the heat generated by the energization of the resistance heating elements 201 and 202, and is raised to a predetermined temperature to control the temperature. Then, in a state where the pressurizing roller 110 is rotationally driven and the heater 113 is raised to a predetermined temperature to control the temperature, the paper P on which the unfixed toner image T is formed in the image forming portion is set to the fixing nip No. , The image surface is introduced so as to face the fixing film 112.

Then, the paper P is sandwiched and conveyed by the fixing nip No., and is heated and pressurized by the heat of the fixing film 112 heated by the heating heater 113 and the nip pressure at the fixing nip No, and the unfixed toner image T is fixed on the paper P. Is established as.

X is a paper passing area for large size paper. In the apparatus of this embodiment, the paper of various width sizes is passed by the so-called center reference transport centered on the paper width. O is the central reference line (virtual line). Xa is a paper passing area (paper passing portion: passing portion) of small size paper. Xb is a non-passing region (non-passing portion: non-passing portion) which is a difference region ((X-Xa) / 2) from the passing region of the large-sized paper that occurs when the small-sized paper is passed. .. Both ends of the fixing film 112 are regulated by the flange members 150L and 150R of the flange members 150a from the inner surface of the flange portion to the outside of the paper passing region X, respectively.

(Pressurized roller)
The pressure roller 110 in this embodiment has an outer diameter of φ20 mm, and an elastic layer 116 (foam rubber) having a thickness of 4 mm is formed by foaming silicone rubber on an iron core metal 117 having a diameter of 12 mm. When the pressure roller 110 has a large heat capacity and a large thermal conductivity, the heat on the surface of the pressure roller is easily absorbed into the inside, and the surface temperature is unlikely to rise. That is, a material having as low a heat capacity as possible, a low thermal conductivity, and a high heat insulating effect can shorten the rise time of the surface temperature of the pressurized roller.

The thermal conductivity of the foamed rubber obtained by foaming the silicone rubber is 0.11 to 0.16 W / m · K, which is lower than that of the solid rubber of about 0.25 to 0.29 W / m · K. Further, the specific gravity related to the heat capacity is about 1.05 to 1.30 for solid rubber, while it is about 0.45 to 0.85 for foam rubber, which is also a low heat capacity. Therefore, this foam rubber can shorten the rise time of the pressure roller surface temperature.

The smaller the outer diameter of the pressurizing roller 110, the more the heat capacity can be suppressed. However, if it is too small, the width of the fixing nip No. becomes narrow, so an appropriate diameter is required. In this embodiment, the outer diameter is set to φ20 mm. .. Regarding the wall thickness of the elastic layer 116, if it is too thin, heat escapes to the metal core metal 117, so that an appropriate thickness is required. In this embodiment, the thickness of the elastic layer 116 is set to 4 mm.

On the elastic layer 116, a release layer 118 made of perfluoroalkoxy resin (PFA) is formed as a release layer of toner. The release layer 118 may be a tube coated or a surface coated with a paint, similarly to the release layer 127 described later of the fixing film 112, but in this embodiment, a tube having excellent durability was used. As the material of the release layer 118, in addition to PFA, fluororesin such as PTFE and FEP, fluororubber and silicone rubber having good releasability may be used.

As the surface hardness of the pressure roller 110 is lower, the width of the fixing nip No. can be obtained with a lighter pressure, but if it is too low, the durability is lowered. Therefore, in this embodiment, the Asker-C hardness (4.9 N load) is used. , 40 °.

(Fixing film)
The fixing film 112 in this embodiment is a heat-resistant member having its own elasticity and flexibility having a thin, substantially cylindrical shape with an outer diameter of φ20 mm in a free state where it is not deformed by applying an external force. It has a multi-layer structure in the thickness direction. The layer structure of the fixing film 112 includes a base layer 126 for maintaining the strength of the film and a release layer 127 for reducing dirt adhesion to the surface.

The material of the base layer 126 needs to have heat resistance because it receives the heat of the heating heater 113, and also needs to have strength because it slides on the heating heater 113. Therefore, it is preferable to use a metal such as SUS (Stainless Steel: stainless steel) or nickel, or a heat-resistant resin such as polyimide. Since metal is stronger than resin, it can be thinned, and because it has high thermal conductivity, it is easy to transfer the heat of the heater 113 to the surface of the fixing film.

Since resin has a lower specific gravity than metal, it has the advantage of having a small heat capacity and being easily warmed. In addition, the resin can be molded at low cost because a thin film can be molded by coating molding. In this example, a polyimide resin was used as the material of the base layer 126 of the fixing film 112, and a carbon-based filler was added to improve the thermal conductivity and strength. The thinner the base layer 126, the easier it is to transfer the heat of the heater 113 to the surface of the fixing film, but the strength decreases, so it is preferably about 15 μm to 100 μm, and in this example, it is set to 50 μm.

As the material of the release layer 127 of the fixing film 112, it is preferable to use a fluororesin such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-hexafluoropropylene resin (FEP). In this example, PFA having excellent mold releasability and heat resistance was used among the fluororesins.

The release layer 127 may be coated with a tube, but may be coated with a paint on the surface. In this embodiment, the release layer 127 is molded with a coat excellent in thin-wall molding. The thinner the release layer 127, the easier it is to transfer the heat of the heater 113 to the surface of the fixing film 112, but if it is too thin, the durability is lowered. Therefore, it is preferably about 5 μm to 30 μm, and in this example, it is set to 10 μm.

(Heater)
The heating heater 113 of this embodiment is a general heater used in a film heating type heating device, and uses a resistance heating element provided in series on a ceramic substrate.

FIG. 5A is a schematic view of the surface side (first surface) of the heater 113 of this embodiment (schematic view of the heater 113 seen from the direction of arrow A3 in FIG. 1). (B) of the figure is a schematic view of the back surface side (second surface) (schematic view of the heater 113 seen from the direction of arrow A2 in FIG. 1). (C) of the figure is an enlarged cross-sectional schematic view along the line cc in (b).

The heating heater 113 uses an elongated alumina plate having a width Wb = 270 mm in the longitudinal direction, a width Wh = 6 mm in the paper transport direction A1, and a thickness H = 1 mm as the substrate 207. Then, 10 μm of Ag / Pd (silver-palladium) parallel resistance heating elements 201 and 202 of Ag / Pd (silver-palladium) are coated on the surface of the substrate 207 by screen printing by screen printing, and glass is coated on the heating element protective layer 209 as a heating element protective layer 209. The one covered with a thickness of 50 μm was used.

In this embodiment, the maximum width size paper (large size paper) that can be conveyed by the apparatus is a letter size width of 216 mm. Therefore, in this embodiment, the width of the paper passing area X of the large size paper is the letter size width 216 mm. The width W of the two parallel resistance heating elements 201 and 202 in the longitudinal direction is 218 mm, which is 1 mm longer on each side than the letter size width 216 mm so that the letter size width 216 mm can be sufficiently heated.

The resistance heating elements 201 and 202 on the substrate 207 are respectively provided in series at the other end side via the conductor 203, and are covered with the heating element protective layer 209. Conductive electrodes 204 and 205 are provided at one end of the resistance heating elements 201 and 202, respectively. A power feeding unit 401 is connected to the electrodes 204 and 205 via a connector (not shown).

When the electrodes 204 and 205 are energized from the power feeding unit 401, the resistance heating elements 201 and 202 generate heat over the entire length width W. As a result, the heater length region portion corresponding to the total length width W of the resistance heating elements 201 and 202 including the paper passing region X of the large-sized paper is steeply heated.

On the back surface of the heating heater 113 (the back surface of the substrate 207), a temperature detecting element 115 for detecting the temperature of the ceramic substrate 207 that has been heated according to the heat generated by the resistance heating elements 201 and 202 is arranged.

The temperature detection element 115 detects the substrate temperature of the heater portion, which is the paper passing region for paper of any width. In this example, the temperature detection element 115 is inserted into the back surface of the substrate 207 of the heater 113 held in the holder 130 from the hole 130b (FIG. 4) provided in the holder 130 and is provided on the back surface of the substrate. The contact is made via the heat conductive member 140 described later. That is, the temperature detecting element 115 detects the temperature of the heating heater 113 via the heat conductive member 140.

A detection signal regarding the temperature of the heater 113 is input from the temperature detection element 115 to the control unit 400. The control unit 400 sends a detection signal regarding the temperature of the heater 113 input from the temperature detection element 115 from the power supply unit 401 to the resistance heating elements 201 and 202 of the heater 113 so as to be maintained at a signal corresponding to a predetermined fixing temperature. Appropriately control the amount of current (electric power). That is, the temperature of the heater 113 is adjusted to a predetermined fixing temperature.

(Heat conductive member)
On the back surface of the heater 113 of this embodiment (the back surface of the substrate 207), a heat conductive member 140 for equalizing the temperature along the length of the heater 113 is provided along the length. As for the material of the heat conductive member 140, the higher the thermal conductivity than the material of the substrate 207 of the heater 113, the higher the effect of leveling the temperature of the fixing members such as the heating heater 113, the fixing film 112, and the pressure roller 110. .. As described above, the heat conductive member 140 may be provided by applying a silver paste having high thermal conductivity, or may be brought into contact with a metal plate such as a graphite sheet or an aluminum plate.

When a sheet or a metal plate is used as the heat conductive member 140, there is an advantage that the heat capacity of the heat conductive member 140 can be easily adjusted by the thickness thereof. In this embodiment, an aluminum plate, which has relatively high thermal conductivity among metals and can be installed at low cost, is used as the thermal conductive member 140. The thicker the heat conductive member 140, the higher the effect of leveling the temperature. Therefore, the productivity of the paper fixing process in the case of continuously passing small size paper is improved.

However, since the heat capacity becomes large, the rise time of the heater 113 becomes slow. Therefore, it is necessary to adjust the material and thickness of the heat conductive member 140 by balancing the productivity of the paper P and the rise time of the heater 113. For the heat conductive member 140 of this embodiment, an aluminum plate having a thickness of 0.5 mm and a short width of 6 mm, which is the same as the width Wh of the heater 113, was used.

Further, since the coefficient of thermal expansion differs between the alumina which is the substrate 207 of the heater 113 and the aluminum of the heat conductive member 140, the heat conductive member 140 may be deformed when the heat cycle of heating and cooling is repeated. Therefore, the heat conductive member 140 of this embodiment is divided into two at the central portion in the longitudinal direction.

As for the longitudinal division of the heat conductive member 140, as the number of divisions increases, the longitudinal width of one of the heat conductive members 140 becomes smaller, so that the thermal expansion becomes smaller and the deformation due to the heat cycle becomes difficult. However, as the number of divisions increases, the effect of leveling heat in the longitudinal direction of the heater 113 becomes smaller. In particular, in order to equalize the temperature of the non-passing portion Xb (FIG. 2) when small-sized paper is continuously passed as described above in the longitudinal direction of the heater, a heat conductive member is formed on the non-passing portion Xb and the passing portion Xa. It is necessary to straddle 140. As shown in FIG. 5B, the heat conductive member 140 of this embodiment has a configuration in which it is divided into two at the central portion of the longitudinal portion.

As shown in FIG. 5B, the heat conductive member 140 is divided into two at the central portion in the longitudinal direction, separated by a division distance Y. The division distance Y may be separated as long as it does not come into contact when the divided heat conductive member 140 thermally expands, and in this embodiment, the division distance Y is set to 5 mm.

The longer the width of the heat conductive member 140 in the longitudinal direction, the higher the effect of equalizing the heat in the longitudinal direction. However, when the large size paper is passed through, the heat at the edges is easily dissipated, so that the large size paper is used. The fixability of the widthwise end of the paper may decrease. Therefore, in this embodiment, the width (positions of the left and right ends) of the heat conductive member 140 in the longitudinal direction is set to be the same as the longitudinal width W of the resistance heating elements 210 and 202 of the heating heater 113.

As shown in FIG. 1, the heating heater 113 and the heat conductive member 140 are fitted and held in the groove holes 130a provided in the heater holder 130.

Here, in the direction orthogonal to the transport direction A1 of the paper P in the transport path surface of the paper P, the heat conductive member 140 comes into contact with the heater 113 within the region of the paper passing region (passing region) X of the large-sized paper. Let the region Q be the first region Q. Further, the divided and separated region in which the heat conductive member 140 is not in contact with the heater 113 is defined as the second region S. The first region Q is wider than the second region S.

(Contact member of fixing film)
Next, the contact member of the endless belt (fixing film), which is a feature of the present invention, will be described. The fixing device 100 of this embodiment is provided with a contact member 190 that comes into contact with the inner surface of the fixing film 112. Assuming that the region where the contact member 190 is in contact with the fixing film 112 is the third region K, the contact member 190 is arranged at a position corresponding to the second region S in the heater 113 in the circumferential direction of the fixing film 112. ing. The third region K includes at least the second region S, and in this embodiment, the width Z of the third region K is substantially the same as the width Y of the second region S.

As shown in FIGS. 3A and 3B, the heat conductive member 140 is divided into two at the central portion in the longitudinal direction separated by a division distance Y (width of the second region S). .. In the circumferential direction of the fixing film 112, the contact member 190 in contact with the inner surface of the fixing film 112 is located at a position corresponding to the second region S in which the heat conductive member 140 is divided and the heater 113 and the heat conductive member 140 are not in contact with each other. It has a provided configuration.

The contact member 190 of this embodiment uses a heat-resistant resin LCP made of the same material as the heater holder 130, is provided on the upper portion of the iron stay 120, and is configured to always contact and slide with the inner surface of the rotating fixing film 112. ing.

In a configuration in which the heat conductive member 140 is divided in the longitudinal direction but does not have the contact member 190 as described above, when the heater 113 is started from the cold state of the fixing device, the heat conductive member 140 comes into contact with the back surface of the heater. The second region S, which is not used, becomes hot. Therefore, temperature unevenness in the width direction (longitudinal direction) occurred in the fixing film 112 (FIG. 16).

However, in the configuration of the first embodiment, the contact member 190 that comes into contact with the inner surface of the fixing film 112 is provided at a position corresponding to the second region S in the circumferential direction of the fixing film 112. Therefore, the contact member 190 lowers the temperature of the fixing film 112 that becomes hot at the position corresponding to the second region S, and the temperature unevenness of the fixing film 112 in the longitudinal direction can be reduced.

Further, in the configuration of this embodiment, since the temperature of the contact member 190 of the fixing film 112 also rises when the fixing device 100 becomes hot, the heat of the fixing film 112 even if the contact member 190 is in contact with the inner surface of the fixing film 112. It becomes difficult to take away. Therefore, temperature unevenness of the fixing film 112 is unlikely to occur even in a hot state. In the configuration of this embodiment, temperature unevenness in the longitudinal direction of the fixing film 112 and the pressure roller 110 is unlikely to occur from the cold state to the hot state of the fixing device 100.

That is, in the configuration in which the heat conductive member 140 is divided and provided in the heating heater 113, the contact member 190 is brought into contact with the fixing film portion corresponding to the second region S of the heating heater 113 in the circumferential direction of the fixing film 112. As a result, it is possible to suppress the occurrence of temperature unevenness of the fixing film 112 and the pressure roller 110 from the cold state to the hot state of the apparatus.

(Confirmation of effect)
Here, the presence or absence of gloss unevenness due to temperature unevenness in the longitudinal direction was compared between the configuration of the first embodiment having the contact member 190 and the comparative example configuration without the contact member 190.

As comparative example configurations, the following configurations 1) and 2) were also compared. 1) A configuration without a contact member 190, 2) A configuration without a contact member 190, and a configuration in which the amount of heat generated by the resistance heating element of the heating heater portion corresponding to the second region S is suppressed.

As a printed image, if a uniform pattern is printed on the entire surface, uneven gloss is likely to be seen, and particularly if a solid image with a large amount of toner is printed, uneven gloss is likely to occur. The heating heater 113 is started from the cold state where the fixing device 100 is cold, and 50 sheets each of a solid image on the entire surface and a halftone image on the entire surface having a printing rate of 50% are alternately printed, and gloss unevenness occurs in a total of 100 images. I confirmed the existence.

Table 1 shows the comparison results in which the case where the gloss unevenness occurred in the portion corresponding to the second region S of the heater 113 in the fixed image was evaluated as x, and the case where the gloss unevenness did not occur was evaluated as ◯.

When the normal heater of Comparative Example configuration 1) is used, when the heat conductive member 140 is not warmed as described above, the portion corresponding to the first region Q of the heater 113 is the heat of the heater 113. Escapes to the heat conductive member 140. Therefore, the temperature becomes uneven in the portion of the heater 113 corresponding to the second region S.

Therefore, gloss unevenness occurred even in the solid image and the halftone image having a low printing rate on the 1st to 5th sheets. However, when the number of printed sheets increases and the heat conductive member 140 becomes warm and hot, heat does not escape from the heat conductive member 140 to the heater 113 in the first region Q, and the occurrence of gloss unevenness disappears.

Further, in the configuration in which the calorific value of the resistance heating element in the portion corresponding to the second region S of the comparative example configuration 2) is suppressed, there is no temperature unevenness in the longitudinal direction and no gloss unevenness occurs in the cold state. However, when the number of printed sheets increases and the heat conductive member 140 becomes warm and hot, the amount of heat generated in the second region S becomes insufficient and uneven gloss occurs.

On the other hand, in the configuration of the first embodiment, the occurrence of gloss unevenness due to temperature unevenness in the longitudinal direction from the cold state to the hot state was not confirmed even in the solid image.

As in the configuration of the first embodiment, the contact member 190 that comes into contact with the inner surface of the fixing film 112 is provided at a position corresponding to the second region S of the heating heater 112 in the circumferential direction of the fixing film 112. As a result, temperature unevenness between the fixing film 112 and the pressure roller 110 can be suppressed regardless of how warm the fixing device 100 is, and image defects due to gloss unevenness can be suppressed.

In the configuration of the first embodiment, the heat-resistant resin LCP is used as the material of the contact member 190, but the present invention is not limited to this.

The amount of heat absorbed by the contact member 190 may be adjusted by its shape, thermal conductivity, or the like in accordance with the temperature rise in the second region S of the heater 113. For example, when the input power of the heater 113 is large and the temperature of the second region S of the heater 113 rises very quickly, it is preferable to use the contact member 190 that makes it easy to take away the heat of the fixing film portion corresponding to the second region S. .. For example, heat may be easily taken from the fixing film 112 by improving the surface property of the contact member 190 or increasing the contact pressure with the fixing film 112.

Further, the material of the contact member 190 may be adjusted by using a material having high thermal conductivity so as to easily take heat from the fixing film portion to which the contact member 190 is in contact and to increase the heat capacity.

For example, the material of the contact member 190 is made of the same metal as the heat conductive member 140 (aluminum in this embodiment), and the temperature rise of the fixing film portion corresponding to the first region Q and the second region S of the heater 113 is set. match. As a result, the temperature unevenness of the fixing film 112 may be adjusted to be uniform.

A plurality of contact members 190 may be provided in the circumferential direction of the fixing film 112, or the contact members 190 may be enlarged to increase the contact area so that heat can be easily taken away.

In this way, heat is transferred from the fixing film 112 according to the contact state and shape of the contact member 190, the material (thermal conductivity and heat capacity), etc., in accordance with the temperature rise of the fixing film portion corresponding to the second region S of the heater 113. Optimize the amount to escape. Thereby, it is preferable to adjust so as to eliminate the temperature unevenness in the longitudinal direction of the fixing film 112.

[Example 2]
A second embodiment will be described below. In the second embodiment, a support member (guide member) that contacts the inner surface of the fixing film 112 and supports the rotation of the fixing film 112 from the inner surface is positioned in the circumferential direction of the fixing film 112 corresponding to the second region S of the heater 113. Arrange in line with. That is, the above support member also functions as a contact member. As a result, temperature unevenness in the width direction (longitudinal direction) of the fixing film 112 is suppressed, and the occurrence of gloss unevenness is suppressed. This will be described below.

In the second embodiment, the image forming apparatus for forming the unfixed toner image is the same as that in the first embodiment, and the description thereof will be omitted. Further, also in the fixing device 100, the basic configuration is the same film heating type image heating device as in the first embodiment, and the same members are indicated by the same reference numerals and the description thereof will be omitted.

FIG. 6A shows a schematic cross-sectional view of the fixing device 100 of the second embodiment. FIG. 3B shows a schematic perspective view of the heater holder 130. A schematic view of the fixing device 100 seen from the direction of the middle arrow A1 in FIG. 6A is shown in FIG. 7A. A schematic view of the fixing device 100 viewed from the direction of the middle arrow A2 in FIG. 6A is shown in FIG. 7B. In FIG. 7, the fixing film 112, the heater 113, and the heat conductive member 140 are shown by watermarks so that the positional relationship between the support member of the fixing film 112 and the heat conductive member 140 can be easily understood.

In the heater holder 130, an upstream support member 131 that supports the rotation of the fixing film 112 from the upstream side in the transport direction of the paper P and a downstream support member 132 that supports the rotation of the paper P from the downstream side are spaced along the length of the heater holder 130. There are a plurality of them. As the heater holder 130, the support members 131 and 132 were molded integrally with the holding portion for holding the heating heater 113 and the heat conductive member 140.

In this embodiment, the upstream support member 131 and the downstream support member 132 are provided at five locations along the length of the heater holder 130 in the paper passing region X. Then, each of the support members 131 and 132 is configured to rotate support (rotation guide) of the fixing film 112 by contacting the inner surface of the fixing film 112. The contact portion of each of the support members 131 and 132 with respect to the fixing film 112 is the third region (convex portion) K, respectively.

Then, among the five locations in the longitudinal direction of the support members 131 and 132, the support members 131 and 132 in the longitudinal center portion coincide with the positions corresponding to the second region S of the heater 113 in the circumferential direction of the fixing film 112. It has a configured structure. That is, the support members 131 and 132 at the central portion of the longitudinal portion also function as contact members corresponding to the second region S. As a result, temperature unevenness in the width direction (longitudinal direction) of the fixing film 112 is suppressed, and the occurrence of gloss unevenness is suppressed.

On the other hand, the support members 131 and 132 other than the longitudinal central portion support the fixing film 112 from the inner surface in the fixing film region corresponding to the first region Q of the heating heater 113.
When the fixing film 112 is supported by contacting from the inner surface of the fixing film 112, the temperature of the fixing film 112 basically drops at the point where the support member contacts.

However, when the fixing film 112 is supported from the inner surface in the fixing film region corresponding to the first region Q of the heater 113, the temperature is leveled by the heat conductive member 140. Therefore, the temperature drop of the support portion of the fixing film 112 is alleviated, and temperature unevenness in the longitudinal direction of the fixing member such as the fixing film 112 and the pressure roller 110 is unlikely to occur.

In the first embodiment described above, the rotational support of the fixing film 112 is supported from the inner surface by the inner surface guide portions 150b of the left and right flange members 150L and 150R at both ends of the fixing film. On the other hand, in the second embodiment, the paper passing area X is also supported by the support members 131 and 132. By supporting the inner surface of the fixing film 112 even in the paper passing region X, the rotation of the fixing film 112 becomes more stable.

As described above, the fixing film 112 rotates by receiving power from the pressurizing roller 110 at the fixing nip No. Therefore, the fixing film 112 rotates with reference to the position of the fixing nip No. The position of the heating heater 113 that determines the position of the fixing nip No. is determined by the heater holder 130. Therefore, by integrating the support members 131 and 132 that support the rotation of the fixing film 112 with the holding portion of the heating heater 113, there is an advantage that the position of the rotation trajectory of the fixing film 112 can be easily determined.

As described above, in the configuration in which the heat conductive member 140 is divided in the longitudinal direction, when the heating heater 113 is started from the cold state of the fixing device 100 as it is, the second region S of the heating heater 113 becomes hot. The temperature unevenness of the fixing film 112 was generated.

However, in the configuration of the second embodiment, the support members 131 and 132 of the fixing film 112 are arranged at positions corresponding to the second region S of the heater 113 in the circumferential direction of the fixing film 112. It is possible to reduce the temperature of the fixing film 112, which becomes hot in the portion corresponding to the second region S, and reduce the temperature unevenness of the fixing film 112 in the longitudinal direction.

Similar to the first embodiment, also in the configuration of the second embodiment, the temperature of the support members 131 and 132 of the fixing film 112 rises in the hot state, so that the heat of the fixing film 112 even if it is in contact with the inner surface of the fixing film 112. It becomes difficult to take away. Therefore, temperature unevenness of the fixing film 112 is unlikely to occur even in a hot state. Therefore, in the configuration of the second embodiment, temperature unevenness in the longitudinal direction of the fixing film and the pressure roller is unlikely to occur from the cold state to the hot state.

In the configuration of the second embodiment, the presence or absence of gloss unevenness was confirmed in the same manner as in the first embodiment, but the occurrence of gloss unevenness due to the temperature unevenness in the longitudinal direction from the cold state to the hot state was also confirmed in the solid image. Was not done.

The configuration of the second embodiment described above describes a configuration in which the fixing film portion corresponding to the first region Q of the heater 113 is supported from the inner surface by the support members 131 and 132. However, if temperature unevenness occurs due to the support members 131 and 132 in the fixing film portion corresponding to the first region Q, the support members 131 and 132 may not be brought into contact with each other in the fixing film portion corresponding to the first region Q. good.

That is, in the second region S, the support members 131 and 132 are in contact with the fixing film 112 as contact members, but in the first image region Q, the support members 131 and 132 may not be in contact with the fixing film 112.

In order to shorten the start-up time of the fixing device 100, the heat capacity of the heat conductive member 140 may be reduced. For example, when the thickness of the aluminum plate is reduced, when a silver paste having high heat conductivity is applied thinly, a thin graphite sheet or the like may be used. When the heat capacity of the heat conductive member 140 is small as described above, the heat leveling effect of the heat conductive member 140 in the longitudinal direction of the heater 113 becomes low.

Therefore, even in the fixing film portion corresponding to the first region Q, if the fixing film is supported from the inner surface by the support members 131 and 132, temperature unevenness may occur. In such a case, for example, as shown in FIG. 8, the support members 131 and 132 of the fixing film 112 are brought into contact with the inner surface of the fixing film 112 only with the support members 131 and 132 corresponding to the second region S of the heater 113. Make the configuration to let. Then, the support member 163 corresponding to the first region Q may be configured so as not to come into contact with the fixing film 112 in the normal rotation.

Further, for the same purpose as described above, the contact area of the support members (contact members) 131 and 132 in the third region K with the fixing film 112 is wider than the contact area with the support members 131 and 132 in the first region Q. It may be configured to do so.

Further, the contact pressure of the support members 131 and 132 in the third region K with the fixing film 112 may be made higher than the contact pressure of the support members 131 and 132 with the fixing film 112 in the first region Q. good.

Further, the thermal conductivity of the support members 131 and 132 in the third region K may be configured to be higher than the thermal conductivity of the support members 131 and 132 in the first region Q.

[Other Examples]
1) In the first and second embodiments, the heat conductive member 140 is divided into two at the central portion in the longitudinal direction in order to prevent deformation, but the structure is not limited to this. For example, as shown in FIG. 9A, even in the configuration in which the heat conductive member 140 is divided into three, the support members 131 and 132 that support the inner surface portion of the fixing film corresponding to the second region S of the heater 113 coincide with each other. Provide to let. As a result, temperature unevenness in the longitudinal direction of the fixing film 112 can be suppressed, and gloss unevenness can be suppressed.

As described above, if the heat capacity of the heat conductive member 140 is reduced in order to shorten the start-up time of the fixing device 100 and the gloss becomes uneven, as shown in FIG. 9B. Can be handled. That is, if the inner surface of the fixing film 112 is supported by the support members 131 and 132 only at the portion corresponding to the second region S of the heater 113, the occurrence of uneven gloss can be suppressed.

2) Further, in the first and second embodiments, the contact members 190 and the support members 142 and 162 that contact and slide with the inner surface of the fixing film in the fixing film portion corresponding to the second region S of the heater 113 have been described. , The configuration is not limited to this. For example, a rotating rotary contact member 220 as shown in FIG. 10 may be provided.

The rotary contact member 220 is arranged at an upper position of the stay 120 in the circumferential direction of the fixing film 112 so as to correspond to the second region S in the heater 113. Then, it comes into contact with the inner surface of the rotating fixing film 112 and rotates in the direction of arrow R4. By making the contact member 220 in contact with the fixing film 112 a rotating member in this way, not only can the rotational torque of the fixing film 112 be suppressed, but also wear and scratches on the inner surface of the fixing film 112 can be suppressed. ..

3) Further, in the examples described so far, the contact member and the support member that come into contact with the inner surface of the fixing film at the portion where the heat conductive member does not contact the back surface of the heater have been described, but the fixing film is not limited to this. A contact member that comes into contact with the outer surface may be provided.

FIG. 11 shows an example in which the separation claw 230 for separating the paper P from the fixing film 112 is brought into contact with the outer surface of the fixing film 112 when the paper P is about to be wrapped around the fixing film 112. Then, the separation claw 230 is arranged so as to coincide with the position corresponding to the second region S in the heater 113 in the circumferential direction of the fixing film 112. That is, the separation claw 230 also functions as a contact member. As a result, temperature unevenness in the width direction (longitudinal direction) of the fixing film 122 is suppressed, and the occurrence of gloss unevenness is suppressed.

If the contact member that comes into contact with the outer surface of the fixing film 112 is installed so as to coincide with the position corresponding to the second region S in the heating heater 113 in the circumferential direction of the fixing film 112, the contact member is not limited to this separation claw, as described above. Similar effects can be obtained.

4) Further, in the first and second embodiments, the fixing device for the monochrome image forming device has been described with the same configuration, but the present invention is not limited to this configuration. For example, the present invention may be applied to a structure using a film having a rubber layer as the fixing film 112 often used in a color image forming apparatus, or a fixing device using a solid rubber as the rubber layer of the pressure roller 110.

In the color image forming apparatus as described above, since the fixing film 112 and the pressure roller 110 have a large heat capacity, temperature unevenness in the longitudinal direction can be easily alleviated. However, since the toner images of a plurality of colors are superimposed, the amount of toner applied is larger than that of a monochrome image, and gloss unevenness due to temperature unevenness is likely to occur.

5) Further, since glossy paper is used as the paper P and high glossiness is required, uneven glossiness may be easily seen. In such a color image forming apparatus, the case where the heat conductive member 140 is divided and used on the back surface of the heater can be dealt with as described above. That is, gloss unevenness due to temperature unevenness can be suppressed by bringing the contact member into contact with the fixing film in the circumferential direction of the fixing film 112 so as to coincide with the position corresponding to the second region S in the heater 113.

6) Further, the configuration described above has described a fixing device for fixing the toner image T on the paper P with the fixing nip No. formed by the fixing film 112 and the pressure roller 110. Even if the present invention is applied to an external heating type fixing device as shown in FIG. 12, uneven gloss can be suppressed.

In this external heating type fixing device 100, the heating heater 113 is enclosed in the fixing film 112, pressed against the outer surface of the fixing roller 300, and the surface of the fixing roller 300 is heated by the heating nip N2. The fixing nip N1 formed by pressure-contacting the fixing roller 300 with the pressure roller 301 as a nip portion forming member is configured to fix the toner image T on the paper P.

Even in such a configuration, when the heat conductive member 140 is separately provided on the back surface of the heater 113, the configuration is the same as in the first and second embodiments. That is, a contact member 190 or the like that comes into contact with the fixing film is arranged so as to coincide with the position corresponding to the second region S in the heating heater 113 in the circumferential direction of the fixing film 112. As a result, the temperature unevenness in the longitudinal direction can be alleviated, and the same effect as described above can be obtained.

7) Further, the configuration described above describes a configuration in which the heating heater 113 heats the fixing film 112 at a nip portion formed so as to face the pressurizing roller 110 or the fixing roller 300, but the present invention is not limited to this.

As shown in FIG. 13, the heating nip N3 formed on the inner surface of the heating heater 113 and the fixing film 112 is provided at a place different from the outer surface of the fixing film 112 and the fixing nip N4 formed by the pressurizing roller 110. But it's okay. 104 and 105 are a sliding plate as a backup member and a holding member thereof, which are arranged inside the fixing film 112 and face the pressure roller 110 with the fixing film 112 interposed therebetween.

Even in such a configuration, when the heat conductive member 140 is separately provided on the back surface of the heater 113, the configuration is the same as in the first and second embodiments. That is, a contact member 190 or the like that comes into contact with the fixing film is arranged so as to coincide with the position corresponding to the second region S in the heating heater 113 in the circumferential direction of the fixing film 112. As a result, the temperature unevenness in the longitudinal direction can be alleviated, and the same effect as described above can be obtained.

8) In the image heating device, in addition to the fixing device that fixes the unfixed toner image T as a fixed image, the toner image assumed to be attached to the recording material or the toner image that has been heat-fixed once is heated and pressed again to have glossiness. It also includes an image quality modifier for improving the image quality.

9) In the apparatus of FIG. 12, the pressurizing roller 301 as the nip portion forming member may be a non-rotating member such as a horizontally long pad-shaped member having a smaller surface friction coefficient than the fixing roller 300 and the paper P. The paper P introduced into the fixing nip N1 slides on the back surface (non-image forming surface side) of the nip forming member in the form of a non-rotating member with a small friction coefficient, while the rotational transport force of the fixing roller 300. The fixing nip N1 is sandwiched and conveyed at.

9) In the image forming apparatus, the image forming section that forms the toner image on the paper P is not limited to the electrophotographic image forming section of the transfer method of the embodiment. For example, it may be an electrophotographic image forming unit in which a photosensitive paper is used as the paper P and a toner image is directly formed on the photosensitive paper. Further, it may be a transfer type electrostatic recording image forming unit or a magnetic recording image forming unit using an electrostatic recording dielectric or a magnetic recording magnetic material as the image carrier. Further, it may be an electrostatic recording image forming unit or a magnetic recording image forming unit which directly forms a toner image on the electrostatic recording paper or the magnetic recording paper as a recording material.

100 ... Image heating device, 113 ... Heating member, 207 ... Substrate, 201, 202 ... Resistance heating element, 112 ... Endless belt, 140 ... Heat conduction member, 190 ... Contact member, No ... Nip part, 118 ... rotating body, P ... recording material, T ... image, A1 ... recording material transport direction, X ... maximum width size recording material passing area, Q ... first area, S・ ・ First area, K ・ ・ Third area

Claims (9)

A heating member having an elongated substrate and a resistance heating element formed on the substrate along the longitudinal direction to generate heat by energization.
An endless belt whose inner peripheral surface slides with the first surface of the heating member, which is rotatable around the heating member.
A heat conductive member having a higher thermal conductivity than the substrate, which is in contact with the second surface of the heating member.
A guide member that supports the rotation of the endless belt by coming into contact with the endless belt.
A nip portion forming member that contacts the outer peripheral surface of the endless belt to form a nip portion ,
The a, an image heating apparatus for heating while nipping and conveying the recording material bearing the images,
In the direction orthogonal to the transport direction of the recording material in the transport path surface of the recording material, the heat conductive member and the heating member are within the region of the passage region of the recording material having the maximum width size that can be transported by the image heating device. The first region in contact is wider than the second region in which the heat conductive member is not in contact.
Image heating characterized in that the convex portion of the guide member, which protrudes upstream in the transport direction of the recording material and is in contact with the endless belt, is provided at a position corresponding to the second region. apparatus. The image heating device according to claim 1, wherein the recording material is sandwiched and conveyed by the nip portion. The image heating device according to claim 1 or 2 , wherein the nip portion forming member is a rotating body. The image heating device according to any one of claims 1 to 3 , wherein the convex portion comes into contact with the inner surface of the endless belt. The image heating device according to any one of claims 1 to 4 , wherein the width of the convex portion is substantially the same as the width of the second region in the longitudinal direction of the substrate . Contact pressure between the endless belt of the guide member in the second region, according to claim 1, wherein the higher than the contact pressure between the endless belt of the guide member in said first region The image heating device according to any one item. The image heating apparatus according to any one of claims 1 to 5 , wherein the thermal conductivity of the guide member in the second region is higher than the thermal conductivity of the guide member in the first region. .. The image heating device according to any one of claims 1 to 5 , wherein in the first region, the guide member does not come into contact with the endless belt. The image heating device according to any one of claims 1 to 8, wherein the convex portion projects in a direction orthogonal to the transport direction and the longitudinal direction of the substrate.