JP2001356624A - Image heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image heating device and an image forming device capable of always uniformly holding nip width, realizing image heating without irregularity and being manufactured at low cost. SOLUTION: This image forming device is provided with a heating means, film, and a pressure member forming a nip with the heating means via the film, and recording material carrying an image is held and carried by the nip and the image on the recording material is heated by heat from the heating means via the film. The base material of the heating means is constituted of a hollow metallic member, and an insulating layer, an energizing heating element and an insulating layer are formed on the metallic base plate. A nip line in the width direction of the recording material is not bent and the nip width is uniform, so that image heating in the width direction of the recording material is performed without causing irregularity. The number of parts is reduced, the manufacture and the assembly of the device are easily performed, and the fluctuation of the nip width based on the dispersion of the dimensional accuracy of the parts is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for heating and fixing a developer image in a copying machine, a printer, and a facsimile, and a heating device for heating a recording material carrying an image to improve surface properties such as gloss. The present invention relates to an image heating apparatus such as a heating apparatus to be assumed, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art A film fixing method is disclosed in JP-A-63-313.
182 and JP-A-2-1577878. This is a device that heats and fixes an image in an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, that is, an image forming process such as electrophotography, electrostatic recording, and magnetic recording. It is used as a fixing device for heating and fixing an unfixed developer image corresponding to target image information formed on a recording material by a direct method or a transfer method.

FIG. 8 shows a typical fixing device of this type. The fixing device includes a heating unit 53 and a heating unit 53.
Endless film 58 loosely fitted in
Support member 55 supporting film 3 and fitted with film 58
And a pressure member 59 rotatably held by the apparatus main body, having a surface which is arranged to face the heating means 53, comes into contact with the heating means 53 via the film 58, and has a surface which is deformed to form the nip N. I have it. For fixing, the recording material P carrying the toner image introduced between the pressure member 59 and the film 58 is conveyed by the pressure member 59 and the film 58 while being pressed against the heating means 53 at the nip N, This is performed by heating the toner image by the heating means 53 to melt the toner and fix it on the recording material P.

The pressure bonding between the heating means 53 and the pressure member 59 is performed as follows.
Both ends of the support member of the unit consisting of the heating means 53, the film 58 and the support member 55 are floated and supported on the apparatus main body, and the unit is moved toward the pressing member 59 by a spring or the like, and the heating means 53 is pressed against the pressing member 59. It is made by that. Since the support member 55 receives a pressing force at an end portion in the front-rear direction of the drawing of the drawing, the support member 55 includes a film guide 54, a stay 52, and a guide member. It is assembled by fitting a guide member into the end.

[0005] As shown in FIGS. 8 and 9, the stay 22 keeps the nip line in a non-deflected state Nl and has a nip width W.
N-1 is kept uniform in the width direction of the recording material so that the nip line is bent like N2 so that the nip widths WN-1 and WN-2 do not become uneven in the width direction of the recording material. .
Also, if the stay 22, the heating element 13, and the film guide 14 have dimensional accuracy defects, the nip width is not uniform over the entire width of the recording material, and the heat from the heating means is dissipated in the width direction of the recording material. As the fixing properties of the toner in the width direction cannot be made uniform, the dimensional accuracy of all the components is strictly controlled, and the heating means forms a uniform nip width with the pressure roller via the film. ing.

[0006]

However, in such a device, since the number of components is large, variations in the dimensions of each component lead to variations in the nip width and the pressing force, resulting in poor fixing performance. It becomes uneven in the recording paper width direction. Even if this can be solved by making the dimensional accuracy of each part strict, the production cost increases significantly in mass production because of the large number of parts.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image heating apparatus and an image forming apparatus capable of not only performing uniform image heating while keeping the nip width uniform and also performing manufacturing at low cost. It is in.

[0008]

To achieve the above object, an image heating apparatus and an image forming apparatus according to the present invention comprise a heating means, a film sliding on the heating means, and a nip between the heating means and the film via the film. A recording material carrying the image at the nip is nipped and conveyed, and the image on the recording material is heated by heat from the heating means via the film. It is formed by using a metal as a material, providing an insulating layer on the metal substrate, and providing an electric heating element on the insulating layer, and has a hollow cross-sectional shape of the base material.

In these apparatuses of the present invention, a member for supporting the heating means can be formed on the base material, so that the number of parts can be reduced and the apparatus can be manufactured at low cost. Variations in the nip width and pressure due to variations in dimensional accuracy of parts are eliminated, and uniform image heating can be performed. Furthermore, since the base material is made of a hollow metal member and has high bending rigidity and a function as a strength member, the nip line in the width direction of the recording material does not bend, the nip width becomes uniform, and the width direction of the recording material becomes uniform. Can be performed without unevenness. As a material of the base material, for example, an iron-based metal or alloy represented by stainless steel can be used.

In the apparatus of the present invention, the apparatus further includes a guide member provided on the outer periphery of the heating means for regulating an end of the film. An engagement portion with the guide member may be provided, whereby the rigidity of the heating means is further enhanced, a uniform nip width is easily obtained, and better image heating is ensured.

Further, the substrate may have a depression having a depth corresponding to the thickness of the insulating layer and the current-carrying heating element over the entire area of the current-carrying heating element pattern support surface, whereby the film can be formed. No longer hits the edge of the heating means,
As the life of the film increases, the frictional resistance between the heating means side surface of the film and the heating means decreases, in other words, the slip of the recording material decreases, and the image heating in the recording material feeding direction becomes more uniform. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image heating apparatus and an image forming apparatus according to the present invention will be described below with reference to FIGS. An image forming apparatus described as an embodiment is a laser beam printer, and an image heating device is configured as a fixing device in the image heating device.

(First Embodiment) In a laser beam printer, as shown in FIG. 1, for example, a process cartridge 31 including a photosensitive drum 6, a developing device, a cleaning device, etc. Device 3
2, a developing device having a developing roller 5, a tray 2 for stacking and storing the recording material P, a roller 3 for feeding the recording material P from the tray 2, and a photosensitive drum 6 for feeding the recording material P sent from the roller 3.
Roller 4, a conveying mechanism including a guide, etc., a device 33 according to the present invention for heating and fixing a toner image as a developer image carried by the recording material P, and a recording material P on which the image is fixed. A mechanism 34 for discharging from the upper part or the rear part of the housing is incorporated.

Printing is started when the laser oscillation device 32 writes an image on the photosensitive drum 6 with image information and the like output from a personal computer or the like.
When the image is written on the photosensitive drum 6, a toner image is formed on the photosensitive drum 6. At the same time, roller 3
The recording material P is pulled out from the sheet, sent out toward the roller 4, conveyed to the photosensitive drum 6 by the roller 4, and charged by the transfer roller 5. The toner image on the photosensitive drum is transferred onto a recording material P, and the recording material P is conveyed toward a fixing device 33, where it is heated and fixed.
The recording material P on which the image is fixed is sent out to the upper part of the housing as a print 10a after being reversed by the carrying-out mechanism 34, or is discharged as it is from the rear part of the housing as a print 10b.

The fixing device 33 includes a heating means 3, a film 9, and a pressure member 8, as shown in FIG.

The heating means 3 comprises a base material 25, an insulating layer 12, an electric heating element 13, and a surface coat layer 14.

The substrate 25 is formed of a hollow metal member having both ends opened, for example, a stainless steel pipe having a circular cross section. At both ends of the base material, engagement portions 25a into which guide members to be described later are fitted are provided. These engaging portions 25
“a” is formed by cutting off a part of both ends of the pipe from the axial direction and the direction perpendicular thereto.

The energizing heating element 13 comprises a resistance heating element.
It is formed by printing on the surface of the insulating layer 12 made of heat-resistant glass formed on the lower peripheral surface of the base material 25, and is covered by the surface coat layer 14 made of heat-resistant glass. The insulating layer 12 has a length substantially corresponding to a region between one end of the base material 25 and the opposite engaging portion 25a as shown by a two-dot chain line in FIG. The coat layer 14 is formed by the two engaging portions 25.
a having a length corresponding to the distance between the electrodes 15 and 16 of the current-carrying heating element 13 in an exposed region of the insulating layer 12.
Are formed.

The film 9 is endless and has substantially the same length as the current-carrying heating element 13 of the heating means 3 or the surface coat layer 14 as an insulating layer. In order to reduce the heat capacity and improve the quick start property, the film 9 has a total thickness of 100 μm or less, preferably 50 μm or less and 30 μm or more, and is a PTFE resin having heat resistance, release property, strength, durability, and the like. Monolayer film such as PFA resin, or composite layer film in which the surface of a film such as polyimide resin, polyamideimide resin, PEEK resin, PES resin, PPS resin is coated with PTFE resin, PFA resin, FEP resin, etc. as a release layer Or a metal tube having a seam using a metal foil or a seamless metal tube. The diameter of the film 9 is larger than that of the heating means 3 and therefore
The film 9 is loosely fitted to the heating means 3.

The guide member 24 forms a part of the base material of the heating means, and has a flange portion and a spring receiving portion. The flange portion has a disk shape having a diameter larger than the diameter of the base material 25 of the heating means 3, the spring receiving portion has a substantially semi-cylindrical shape, and a groove 24c extending from the end to the flange portion at the lower portion of the cylindrical wall. Is provided. The internal space 24a of the spring receiving portion is a space having a semicircular cross section that fits with the engaging portion 25a of the heating means base material 25, and the flange portion has a semicircular shape corresponding to the cross sectional shape of the engaging portion 25a. Hole 24b
Is provided. For attachment, the hole 24b in the flange portion of the guide member 24 is engaged with the engaging portion 25a of the base material 25.
This is done by snapping in. When fitted, the guide member 24 strengthens the rigidity of the base material 25 and the guide member 2
The flange portion 4 contacts the surface of the engaging portion 25a perpendicular to the axial direction, guides the end surface of the film 9, and prevents the film 9 from coming off.

The pressing member 8 is in the form of a roller or a roll, and includes a shaft 8a and an elastic layer 8b made of rubber having good releasability such as silicone rubber.

In order to assemble the laser beam printer shown in FIG. 1, the shaft 8a of the pressing member 8 is held by a bearing provided on a frame of the laser beam printer, and the shaft 8a
a is connected to the shaft of the main motor 7 of the laser beam printer via a gear train, and the guide members 24 at both ends of the assembly comprising the film 9 and the heating means 3 are perpendicular to the guides on the frame of the laser beam printer. Movably and by means of a coil spring 23 arranged between the frame and a spring seat on the guide member 24,
The entire assembly is pushed down toward the pressing member 8 with a total pressure F of 4 to ²⁰ kgf / cm ² .
When assembled, the heating means 3 presses the film 9 and the pressing member 8 straight together with the flat lower surface 14e of the film guide 14, as shown in FIG. 2, and deforms them to form a nip N.

At this time, a member that supports the heating means 3 and receives the pressing force F, that is, the base member 25 is made of a hollow metal member, has a large bending strength, and the guide member 24
5, the nip line in the width direction of the recording material does not bend, but becomes a straight line without bending, and the nip width in this direction becomes uniform. In addition, the member for fixing and supporting the heating means 3 is a base material 25 constituting the heating means 3.
And the guide member 24, and the number of components is smaller than that of a conventional device of this type. Therefore, there is no variation in the nip width due to variation in component accuracy. The assembly can be performed easily because the number of components is small, and the assembly can be performed at low cost in combination with the low component cost.

The electrical connection of the heating means 3 is made by fitting the socket 12 into the guide member 24, as shown in FIG. The socket 11 has a substantially U shape, and has a socket member 11a incorporated therein. The socket member 11a is provided with contacts, and these contacts are connected to a power supply 21 by wires 19. The guide member 24 is mounted on the groove 2 of the guide member 24.
4c as a guide, the upper and lower sides of the heating means base material 25
By fitting it into the end of the When the socket is fitted, the contacts of the socket 12 are connected to the electrodes 15,
Touch 16. The temperature detecting element 4 is attached to a surface of the substrate 25 opposite to the surface on which the energizing heating element 13 is located with an insulating layer interposed therebetween, such as a thermistor. The temperature detecting element 4 is connected to a control device 22 of the laser beam printer together with a thermoswitch for preventing a runaway temperature rise due to a failure or the like.

In FIG. 1, printing is started by rotating the photosensitive drum 6 by the main motor 7 and uniformly charging the photosensitive drum 6 to a predetermined polarity and a predetermined voltage by the charging roller 5. The exposed surface of the charged photosensitive drum 6 is subjected to image exposure based on the image information by the exposure device 32, and the charge of the exposed portion is removed, so that an electrostatic latent image is formed on the surface of the photosensitive drum 6. This electrostatic latent image is developed by a developing device. The development is performed by applying a developing bias to the developing roller 5 to attach toner as a developer to the electrostatic latent image on the photosensitive drum, and developing or visualizing the electrostatic latent image as a toner image. Done. The toner image is transferred to a recording material P such as paper by the developing device 5. The recording material P is loaded in the cassette 2, is pulled out of the cassette 2 by the roller 3, is conveyed by the roller 4, and is conveyed to the transfer nip between the photosensitive drum 6 and the developing device via the top sensor. You. At this time, the recording material P
Is detected by the top sensor, and is synchronized with the toner image on the photosensitive drum 6. A transfer bias is applied to the developing roller 5, whereby the toner image on the photosensitive drum is transferred to a predetermined position on the recording material P. The recording material P having the unfixed image carried on the surface by the transfer is conveyed to a fixing device 33 according to the present invention along a conveyance guide, where the unfixed toner image is heated and pressed, and is fixed on the recording material P. Is done. The recording material P after the fixing of the toner image is
Is sent out to the tray. On the other hand, on the photosensitive drum 6 after the transfer of the toner image, the toner remaining on the surface without being transferred to the recording material P is removed by a cleaning blade of a cleaning device, and is used for the next image formation. Image formation is performed one after another by repeating these operations.

As shown in FIG. 2, the fixing is performed by introducing and passing a recording material P on which a toner image is formed and carried between a film 9 forming a nip N and a pressing member 8, as shown in FIG. The heating is performed by heating the surface of the toner image carrier of the recording material P by the electric heating element 13 to apply thermal energy to the unfixed image, softening and melting the toner, and attaching the toner to the recording material P.

At this time, the nip N is, as described above,
Since the width WN is uniform, the nip line N1 is a straight line without bending, and the nip width is uniform, the heating is uniform in the width direction and the feeding direction, and the heating is performed in both the width direction and the feeding direction of the recording material. Able to fix evenly.

(Second Embodiment) This fixing device is different from the device described with reference to FIGS.
03 is different only in configuration.

As shown in FIGS. 6 and 7, the heating means 103 includes a base 125, an electric heating element 113 formed on the base 125 with an insulating layer 112 interposed therebetween, and an electric heating element 11.
3 has a surface coat layer 114 formed thereon.

The substrate 125 is formed of a hollow metal member having both ends opened, for example, a stainless steel pipe having a circular cross section.

The electric heating element 113 is a resistance heating element, and is formed on the insulating layer 112 formed on the lower surface of the base 125. The insulating layer 112 has one end located on the right side in FIG. 7 leaving a length related to the entire length of the guide member 111, the opposite end on the left side in FIG. 7 extending to the end of the base material 125, and further having a length L. Only to the inner surface of the substrate 125. The current-carrying heating element 113 has one end located on the right side corresponding to the end of the insulating layer 112 and the other end located on the left side formed on the insulating layer except for a length related to the entire length of the guide member 111. . Electrodes 115 and 116 are energized heating elements 113
Are drawn out from the right end on the extension region of the insulating layer on the inner surface of the base material 125.

The guide member 124 is a hollow member having both ends opened. This guide member 124 is
5 is provided with a groove 124c having a width corresponding to the heating means 103 on the lower side, and has a substantially C-shaped cross section. The guide member inserted into the opposite end of the base 125 has the same configuration. The attachment to the base material 125 is performed by aligning the heating means 103 with the groove 124c and fitting the heating means 103 into the base material 125 with the ends thereof aligned. Although not shown, a rotation stopper for the guide member 124 is provided between the guide member 124 and the base 125.

The heating means 103 loosely fits the film 9 on the base material 125, fits the guide member 124 at both ends of the base material 125 as a guide for the edge of the film 9, and together with the pressing member 8, for example, as shown in FIG. The laser beam printer shown in FIG.

Incorporation into a laser beam printer is as follows:
The shaft 8a of the pressing member 8 is held by a bearing on the frame of the laser beam printer, and the shaft 8a is connected to the shaft of the main motor 7 of the laser beam printer via a gear train. Guide members 124 at both ends of the assembly
Is vertically movable to a guide provided on a frame of the laser beam printer, and the base material 125 is pressed with a total pressure F by the coil spring 23 disposed between the frame and a spring seat provided on the guide member 124. This is done by pressing down on the member 8. The pressing member 8 has one end in contact with the end of the energizing heating element 113 and the surface coat layer 114, that is, the line S in FIG. 7, and the other end in the insulating layer 112, the energizing heating element 113 and the surface. Coat layer 114
Near the opposite end of the

When assembled, the heating means 103 pushes the film 9 and the pressing member 8 straight and deforms them to form a nip. Also at this time, the heating means 10
Since the base member 125 that supports the pressure member 3 and receives the pressing force F is made of a metal hollow member, has a large bending strength, and is stiffened by the guide member 124, the nip line along the longitudinal direction of the pressing member 8 is reduced. It does not bend and becomes a straight line without bending, and the nip width in the feed direction of the recording material P becomes uniform. The members supporting the heating means 103 are only the base member 125 and the guide member 124 constituting the heating means 103, and the number of parts is much smaller than that of the conventional apparatus of this type, and the assembling accuracy depends on the variation in the parts accuracy. Hardly affected.

The connection between the electric heating element 113 and the power supply is made by fitting the socket 111 into the base material 125. The socket 111 is also made of a substantially L-shaped member, but the contacts are arranged on the inner surface of the upper side. The mounting is performed by heating means 103 substrate 25 so that an extended insulating layer at the end of substrate 125 is sandwiched between the upper side and the lower side.
By pushing it into the end. When the terminal 111a is inserted, the terminal 111a of the socket 111 is turned on.
, And is connected to a power supply 22 via a cable 19. The temperature detecting element 4 made of a thermistor or the like is attached to the surface of the base 125 opposite to the surface on which the current-carrying heating element 113 is located with an insulating layer interposed therebetween, and is connected to a control device of the laser beam printer.

As in the first embodiment, printing is performed by pulling out the recording material from the tray, transferring the toner image on the photosensitive drum, and fixing the image by heating with this fixing device. The fixing is performed by rotating the pressing member 8 and frictionally driving the film 8. The film 8 is guided by guide members 124 and rotates between these guide members. Recording material P on which toner image is formed and supported
Is introduced and passed between the film 9 forming the nip and the pressing member 8, and the surface of the toner image carrier of the recording material P is heated by the electric heating element 113 via the film 9, and the thermal energy is reduced. Applied to unfixed images. As a result, the toner is softened and melted, and adheres to the recording material P.
At this time, as described above, since the nip line is formed of a straight line with no bending and the nip width is uniform, the heating is uniform in the width direction and the feeding direction, and the recording material in the width direction and the feeding direction. Can be established evenly on both sides.

In this fixing device, the base material 125
Is formed of a hollow member having the same diameter, but the both end regions of the guide member 124 are smaller in diameter than the central region located therebetween, and the outer diameter of the guide member 124 is The film 8 is formed so as to be larger than the diameter of the central region of the base member 125 and the base member 125 and the guide member 12.
For example, it may be possible to prevent the user from sneaking into the gap with the device 4.

(Third Embodiment) This fixing device also differs from the device described with reference to FIGS. 2 to 5 only in the configuration of the heating means.

The heating means 203 has a substrate 225 as shown in FIG. The base material 225 is formed of a stainless steel pipe having a circular cross section. However, in the lower part, a part of the outer peripheral surface is formed in a plane, and a depression 225b is formed in the parallel plane part. The formation is performed, for example, by drawing. The depression 225b is formed in the insulating layer 2
12, the heating means 203 has a depth corresponding to the thickness t of the heating element 213 and the surface coat layer 214, and a width and a length corresponding to the entire length and the entire width of the heating means 203.

The insulating layer 212 is formed on the bottom surface of the recess 225b, and the current-carrying heating element 213 made of a resistance heating element is
12, and the surface coat layer 214 is formed on the electric heating element 212. Surface coat layer 2
The outer surface of 14 is flush with the surface of the parallel plane portion of the substrate 225.

As with the fixing device described with reference to FIGS. 2 to 5, this heating means also cuts a part of the base material 225 at both ends of the base material 225 from the axial direction and the direction perpendicular thereto. And an end member having a space to be engaged with these engaging portions. The assembling is performed by loosely fitting the film 9 to the base material 225 and fitting guide members to both ends of the base material 225.

Incorporation into a laser beam printer is as follows:
The shaft 8a of the pressing member 8 is held by a bearing provided on the frame of the laser beam printer. The shaft 8a is connected to the shaft of the main motor of the laser beam printer via a gear train.
The guide members at both ends of the assembly consisting only of 3 are mounted so as to be vertically movable to the guides on the frame of the laser beam printer, and by a coil spring arranged between the frame and the spring seat on the guide member, This is performed by pushing down the base material 225 toward the pressing member 8. When assembled, the heating means 3 pushes the film 9 and the pressure member 8 straight and deforms them to form a flat nip. Also at this time, since the base member 225 receiving the pressing force F is made of a metal hollow member, has a large bending strength, and the rigidity is enhanced by the guide member, the nip line along the longitudinal direction of the pressing member 8 is bent. First, the straight line has no deflection, the nip width in the feed direction of the recording material P becomes uniform, and the number of components is much smaller than that of a conventional device of this type. I do not receive.

The connection between the heating means 203 and the power supply is made in the same manner as in the fixing device described with reference to FIGS. The contact is made by contacting the contact point with the electrode.

Printing is performed by pulling out the recording material from the tray, transferring the toner image on the photosensitive drum, and fixing the image by heating with this fixing device. For fixing, a recording material P carrying a toner image as a developer image is introduced and passed between the film 9 forming the nip N and the pressure member 8, and recording is performed via the film 9. This is performed by heating the surface of the toner image carrier of the material P by an electric heating element of the heating means 203, applying thermal energy to the unfixed image, softening and melting the toner, and attaching the toner to the recording material P. At this time, the nip N is, as described above,
Since the nip line is formed of a straight line without bending and has a uniform width, the heating becomes uniform in the width direction and the feeding direction of the recording material P, and the fixing can be performed uniformly in the width direction and the feeding direction of the recording material P. . In addition, since there is no edge in the area of the substrate 225 where the inner peripheral surface of the film 8 contacts,
The frictional resistance between the heating means side surface of the film 8 and the heating means is reduced, the slip of the recording material P is reduced, and the image heating in the feeding direction of the recording material P can be performed uniformly. And since the inner peripheral surface of the film 8 is not damaged, the above-mentioned performance can be stably maintained for a long time.

In the above-described embodiment, the substrates 25, 125, and 225 are made of pipes having a circular cross section, but may be pipes having a square cross section, and may be drawn pipes or welded pipes.

[0047]

As described above, according to the present invention,
It is possible to obtain an image heating apparatus and an image forming apparatus in which the nip width is always kept uniform, the image heating can be performed without unevenness, the nip width does not fluctuate due to the variation in component accuracy, and the manufacturing can be performed at low cost. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a cross section of a configuration of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a cross section of a configuration of an embodiment of a fixing device as an image heating device of the present invention incorporated in the image forming apparatus of FIG. 1;

FIG. 3 is an exploded perspective view of the fixing device shown in FIG.

FIG. 4 is an explanatory view showing a cross section of the configuration of another embodiment of the fixing device as the image heating device of the present invention incorporated in the image forming apparatus of FIG. 1;

FIG. 5 is an exploded perspective view of the fixing device shown in FIG.

FIG. 6 is an explanatory view showing a cross section of the configuration of still another embodiment of a fixing device as an image heating device of the present invention incorporated in the image forming apparatus of FIG. 1;

FIG. 7 is an explanatory diagram showing a cross section of a configuration of a conventional fixing device.

FIG. 8 is a diagram illustrating a state of a nip line in a conventional fixing device.

FIG. 9 is a view for explaining a state of a nip width in a conventional fixing device.

[Explanation of symbols]

 3, 103, 203 ... heating means 8 ... film 12, 112, 212 ... insulating layer 13, 113, 213 ... energizing heating element 14, 114, 214 ... insulating layer 25, 125, 225 ... base material P ... recording material

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinwa Adachi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term within Canon Inc. (reference) 2H033 AA06 AA31 BA26 BE03 3K058 AA86 BA18 CE13 CE19 DA04 GA06 3K092 PP18 QA01 QB76 RF09 RF12 RF22 VV22 VV40

Claims (13)

[Claims] 1. A heating device, a film sliding on the heating device, and a pressure member forming a nip with the heating device via the film, wherein a recording material carrying an image in the nip is nipped and conveyed, In an image heating apparatus in which an image on a recording material is heated by heat from a heating unit via a film, the heating unit uses a metal as a base material, provides an insulating layer on the metal substrate, and supplies an electric heating element to the insulating layer. An image heating apparatus, which is formed by providing a substrate, and wherein the cross-sectional shape of the base material is hollow. 2. The image heating apparatus according to claim 1, wherein
Including a guide member that regulates an end of the film provided on the outer periphery of the heating means, the hollow metal base has a notch at the end, a squeezing part, and an engagement part with the guide member by bending or the like. Image heating device. 3. The image heating apparatus according to claim 1, wherein the hollow metal base has a depth corresponding to the thickness of the insulating layer and the current-carrying heating element over the entire area of the current-carrying element pattern support surface. An image heating device having a depression having 4. An image forming apparatus comprising the image heating device according to claim 1. 5. An apparatus main body, a heating means fixed at a position to the apparatus main body, an endless film loosely fitted to the heating means, and arranged facing the heating means, and contacting the heating means via the film. A pressurizing member rotatably held by the apparatus main body, the pressurizing member having a surface that deforms to form a nip, and a recording material that carries a toner image introduced between the pressurizing member and the film. In an image heating apparatus in which a toner image is heated by a heating unit while the toner image is melted and fixed on a recording material while being conveyed by a pressing member and a film while being pressed against a heating unit by a nip, the heating unit is made of metal. And a current-carrying heating element provided on the base material with an insulating layer interposed therebetween, wherein the base material comprises a hollow member, and the position of the heating means is fixed by supporting the member on the apparatus body. Being done An image heating device. 6. The image heating apparatus according to claim 5, wherein
An image heating apparatus comprising a guide member having a base material attached to both ends, and the guide member is supported by an apparatus main body. 7. The image heating apparatus according to claim 5, wherein
An image heating apparatus comprising a guide member having a base material attached to both ends thereof, wherein the guide member is supported by the apparatus body in a floating manner and is pressed toward a pressing member to form the nip. 8. The image heating apparatus according to claim 5, wherein
A base member is attached to the end, and a guide member having a flange portion having a larger diameter than the film and a holder portion having a smaller diameter than the base material is provided, and the base material has both ends in an axial direction and a direction perpendicular thereto. The guide member has a groove which fits into the shaft portion of the engaging portion by contacting the flange with a portion of the engaging portion located in a direction perpendicular to the axial direction. Image heating device. 9. The image heating apparatus according to claim 8, wherein
An image heating apparatus, wherein the heating means includes an electrode in a portion of the guide member located inside the holder, and the holder portion includes a housing space for a socket having a terminal in contact with the electrode. 10. The image heating apparatus according to claim 5, wherein the base material has a larger diameter than the film, and a hollow guide member having a hole having a diameter related to the base material is fitted at both ends, and the guide is provided. An image heating apparatus in which a member is floatingly supported by an apparatus main body and pressed against a pressing member to form the nip. 11. The image heating apparatus according to claim 10, wherein the heating means has an electrode at an end of the substrate, and a guide member has a groove for positioning a socket having a terminal for contacting the electrode outside the substrate. An image heating device provided in a region where the device is located. 12. The image heating apparatus according to claim 5, wherein the substrate has a depression for engaging a heating means on a surface on which the nip is formed, and the depression is an insulating layer. And an image heating device having a depth corresponding to the thickness of the electric heating element. 13. The image heating apparatus according to claim 5, wherein the substrate has a circular cross section.