JP2001222173A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film heating type heating device where the moving or rotational resistance of film is reduced, and to obtain an image heating and fixing device where the irregularity of a toner image caused by the slip of material to be recorded and the film is prevented, material to be heated is prevented from being curled just after passing through a nip part, the material to be heated is made to smoothly advance in the nip part so as to prevent the material to be heated from being jammed or wrinkled, the heat insulating property of a heating body is enhanced and the heat energy is efficiently imparted to the material to be heated. SOLUTION: In this heating device provided with a heating body 20, a heating body holding member 21, and the film 22 sliding on the member 21, and a pressure member 23 forming a nip N with the heating body through the film, and the material to be heated P is held and carried in the nip, and heated by heat from the heating body through the film. The heating body has structure provided with a resistance layer energized to generate heat through an insulating layer on a metallic base plate, and the end of at least either the most-upstream side edge or the most-downstream side edge in a film moving direction is bent 20r to a side opposite the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating element, a heating element holding member for fixing and holding the heating element, a film sliding on the heating element, and forming a nip with the heating element via the film. And a pressurizing member, wherein the material to be heated is sandwiched and conveyed by the nip, and the material to be heated is heated by heat from the heating body via the film. .

[0002]

2. Description of the Related Art A heating apparatus of the above-described film heating type is disclosed in JP-A-63-313182 and JP-A-1-21-2.
JP-A-63679 / JP-A-2-15778 / JP-A-4-44075-44083 / JP-A-4-2
No. 04980-204984, and the like.
For example, an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile heats and fixes an image, that is, an appropriate image forming process means such as electrophotography, electrostatic recording, and magnetic recording. A fixing device (image heating device) that heats and fixes an unfixed toner image of image information formed and supported on a surface of paper, an electrofax sheet, an electrostatic recording sheet, or the like by an indirect (transfer) method or a direct method as a permanent fixed image ).

[0003] As the heating element, a heating element having a low heat capacity with a rapid temperature rise, for example, a ceramic substrate having an insulating property and a good thermal conductivity,
Generally, a so-called ceramic heater having a resistive layer, which is provided on the surface of the substrate and generates heat by energization, as a basic component has been used. Since the film is heat resistant, a thin film and a low heat capacity material can be used, the temperature of the heating body rises in a short time, and there is no need to supply power to the heating body during standby, and the recording as a material to be heated can be performed. Even if the material is passed immediately, the heating member can be sufficiently heated to a predetermined temperature until the recording material reaches the fixing portion, and is much more remarkable than a heat roller type heat fixing device. It is possible to shorten the wait time (quick start property: operate on demand) and save power. Further, the present invention has an advantage that the temperature inside the apparatus such as an image forming apparatus can be reduced, and is effective.

FIG. 11A is a schematic cross-sectional view of a main part of an example of a film heating type heating device (heating fixing device).
(B) is an enlarged model diagram of a fixing nip portion. The apparatus of this embodiment is a pressure roller drive type / tensionless type apparatus disclosed in Japanese Patent Application Laid-Open No. 4-44075-44083.

[0005] Reference numeral 20A denotes a ceramic heater as a heating element. 20a is alumina (A) as a heater substrate.
l ₂ O ₃₎ plate or aluminum nitride (AlN) or the like of the ceramic substrate, 20b is to form provided on the surface of the ceramic substrate, the resistance layer pattern for generating heat by energization, 20p is covered a resistive layer pattern on the surface of the ceramic substrate A heat-resistant glass layer as a surface protective layer formed and provided together. The ceramic heater 20A is heated and controlled at a predetermined temperature by a current supply circuit (not shown) to the resistance layer pattern 20b and a temperature control system.

Reference numeral 21 denotes a heater holding member (hereinafter, referred to as a heater holder), which is a member having rigidity and heat resistance having a substantially semicircular trough-shaped cross section. The ceramic heater 20A is fixedly supported by being fitted with a heater surface side (resistance layer pattern forming surface side) outside in a groove 21a provided on the lower surface side of the heater holder 21 along the member length. Heater holder 21 is ceramic heater 20A
And also serves as a transport guide for the next fixing film 22.

Reference numeral 22 denotes a heat-resistant and thin film (hereinafter, referred to as a fixing film) in a cylindrical or endless belt shape, which is loosely fitted to the heater holder 21 including the ceramic heater 20A.

Reference numeral 23 denotes an elastic pressure roller as a pressure member, which has a predetermined pressing force against elasticity by sandwiching the fixing film 22 with respect to the ceramic heater 20A supported on the lower surface side of the heater holder 21. A heating nip portion (hereinafter, referred to as a fixing nip portion) N having a predetermined width is formed by pressing.

The elastic pressure roller 23 is rotationally driven at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow by a driving system M, and a feeding force is applied to the fixing film 22 at the fixing nip portion N by the rotational force of the elastic pressure roller 23. The fixing film 22 works so that the inner surface thereof closely slides on the lower surface of the ceramic heater 20A in the fixing nip portion N while the heater holder 21 is in contact therewith.
Is rotated and driven at a predetermined peripheral speed in the clockwise direction indicated by the arrow.

In a state in which the elastic pressure roller 23 is rotationally driven to move and move the fixing film 22, and the ceramic heater 20A is heated and controlled to a predetermined temperature.
The fixing nip N is guided by the entrance side guide member 13.
When the recording material P on which the unfixed toner image Ta as the material to be heated is formed and supported between the fixing film 22 and the elastic pressure roller 23 is introduced with the image carrying surface side being the fixing film 22 side, the recording is performed. The material P is brought into close contact with the outer surface of the fixing film 22 at the fixing nip portion N, and is conveyed while nipping the fixing nip portion N together with the fixing film 22.

In the fixing nip portion N, the recording material P
The unfixed toner image Ta is heated via the fixing film 22 by the ceramic heater 20A, and the unfixed toner image Ta is heated and fixed on the surface of the recording material P, and the fixed image Tc
Becomes The portion of the recording material that has passed through the fixing nip N is separated from the outer surface of the fixing film 22 and conveyed while being guided by the exit side guide member 29.

A heat insulating space 21d is provided between the back side of the ceramic heater 20A (the side opposite to the surface in contact with the fixing film) and the heater holder surface, and the contact area between the ceramic heater 20A and the heater holder 21 is provided. , The heat insulation between the ceramic heater 20A and the heater holder 21 is further increased.

The ceramic substrate 20a of the ceramic heater 20A is usually cut out from a large flat ceramic substrate by a cutting device using a laser beam, a diamond cutter, or the like, so as to be used as a ceramic heater. Therefore, the edge of the ridge line of the ceramic substrate 20a is angular, and there are knurls and burrs.
If the inner surface of the film contacts and slides, the inner surface of the film is easily worn or damaged. So ceramic heater 20A
In order to prevent wear and damage of the fixing film 22 due to the inner surface of the fixing film coming into contact with the ceramic substrate edges e and e on the upstream and downstream sides of the fixing film moving direction, the ceramic heater 20 of the heater holder 21
In the fixing film moving direction, the portions 21b and 21c corresponding to the immediately upstream portion and the immediately upstream portion, respectively, protrude toward the fixing film 21 side from the fixing film sliding surface of the heater 20 to form protrusions 21b and 21c. The inner surface of the film 22 is held in a state of being floated in a non-contact manner from the edge portions e.e of the ceramic substrate.

[0014]

(1) In order to prevent the inner surface of the fixing film from coming into contact with the edge portions e.e of the ceramic substrate, the protrusions 21b. On the other hand, the presence of the fixing film 21c causes the fixing film 22 to largely deviate from the circular orbit, so that the fixing film 22 runs on a meandering orbit near the fixing nip portion N. For this reason, the rotational resistance of the fixing film 22 is increased by the amount that the traveling locus of the fixing film 22 deviates greatly from the perfect circular shape.

While the recording material P is passing through the fixing nip N, the fixing film 22 is driven by the friction between the recording material P and the fixing film 22. When a small recording material passes through the fixing nip portion N, a slip occurs between the recording material P and the fixing film 22, and there is a problem that the toner image on the recording material P is disturbed.

Further, even when the recording material having a low coefficient of friction is passed through the recording material P containing a large amount of water, steam is generated from the recording material by heating the fixing device. In addition, a slip may occur between the pressure roller 23 and the recording material P, or between the recording material P and the fixing film 22, and the image may be disturbed or a conveyance failure of the recording material may occur.

(2) In the conventional fixing device, the recording material P immediately after passing through the fixing nip N is guided downward by the heater downstream side projection 21c of the heater holder 21 so that the recording material P is guided downward. P is curled and conveyed in a direction in which the printing surface side is convex, and there is also a problem that the curl of the recording material P discharged out of the apparatus, in particular, the curling in which the printing surface side is convex remains. This tendency was particularly remarkable at the leading end of the recording material P.

(3) The protrusion 21b on the upstream side of the heater of the heater holder 21 tends to narrow the introduction portion E at the entrance of the fixing nip, and the fixing nip N
There was also a problem that the approach to the road was not smooth. In particular,
The above tendency is remarkable for the recording material P having a curled leading edge, which may cause paper jams and paper wrinkles.

(4) Insulating space 21d is provided in the heater holder 21 to reduce the contact area between the ceramic heater 20A and the heater holder 21 to further enhance the heat insulating property of the ceramic heater 20A.
Even if the fixing position of the ceramic heater 20A is slightly shifted to the downstream side in the moving direction of the fixing film and fixed, it is necessary to prevent the ceramic heater 20A from falling into the space 21d.
There is a limit in reducing the contact area between the heater holder 21 and the heater. Actually, if the heater width is B in consideration of the dimensional accuracy and thermal expansion of parts, the width of the space 21d is B
It was necessary to make it smaller by about 2 mm.

The present invention solves the above problems (1) to (4) for a film heating type heating apparatus.

That is, the first object is to reduce the movement or rotation resistance of the film and to prevent the toner image from being disturbed due to the slip between the recording material and the film in the image heating and fixing apparatus.

A second object is to prevent the material to be heated from curling immediately after passing through the nip.

A third object is to widen the heated material introduction portion at the entrance of the nip so that the material to be heated can enter the nip more smoothly and prevent jamming of the heated material (paper jam) and wrinkling of the heated material. It is to be.

A fourth object of the present invention is to increase the heat insulating property of the heating element and to efficiently apply heat energy to the material to be heated by reducing the contact area between the heating element and the heating element holding member.

[0025]

According to the present invention, there is provided a heating apparatus and an image forming apparatus having the following constitutions.

(1) A heating member, a heating member holding member for fixing and holding the heating member, a film sliding on the heating member, and a pressing member forming a nip with the heating member via the film. In a heating device in which a material to be heated is nipped and conveyed in the nip, and the material to be heated is heated by heat from the heating body via the film, the heating body includes an insulating layer on a metal substrate. Having a structure in which a resistance layer that generates heat by energization is provided, and at least one end of the most upstream edge and the most downstream edge in the film moving direction is bent to the opposite side to the film. And a heating device.

(2) In the heating element holding member, a portion of the heating element immediately downstream of the heating element in the transport direction of the material to be heated does not protrude from the film-side surface of the heating element toward the film. A heating device according to claim 1.

(3) In the heating element holding member, a portion of the heating element immediately upstream of the heating element in the transport direction of the material to be heated does not project from the film-side surface of the heating element toward the film. A heating device according to claim 1.

(4) Both ends of the most upstream edge and the most downstream edge in the film moving direction of the heating element are bent to the opposite side to the film, and the heating element of the heating element holding member is (1) characterized in that the surface for holding is flat and a space is provided between the heating element and the heating element holding member.
The heating device according to any one of (1) to (3).

(5) The heating device according to any one of (1) to (4), wherein the film has an endless belt shape.

(6) The heating device according to any one of (1) to (5), wherein the film is moved and driven by rotation of the pressing member.

(7) The heating apparatus according to any one of (1) to (5), wherein the material to be heated is a recording material carrying an image.

(8) In an image forming apparatus having an image forming means for forming and carrying an image on a recording material and a fixing means for heating and fixing the image on the recording material, the fixing means may be any of (1) to (6). An image forming apparatus, which is the heating apparatus according to any one of the above.

<Operation> a) The heating element has a structure in which a resistance layer which generates heat by energization is provided on a metal substrate via an insulating layer, and the most upstream side edge and the most downstream side edge in the film moving direction. Has a structure in which at least one end is bent to the opposite side of the film, so that even if the film and the corner of the heating body come into contact, the corner of the heating body is rounded. It is possible to smoothly slide to a corner having a corner.

Therefore, it is not necessary to provide the heating element upstream projection and the heating element downstream projection on the heating element holding member in order to prevent the contact between the heating element edge and the film, and the film is more nearly circular. The film can be rotated along the locus, and the movement or rotation resistance of the film can be reduced. As a result, in the image heating and fixing apparatus, it is possible to prevent the toner image from being disturbed due to the slip between the recording material and the film.

B) In the heating member holding member, the film is formed such that the portion immediately downstream of the heating member in the direction of transport of the material to be heated does not protrude from the film side surface of the heating member toward the film side. Since the material to be heated is also conveyed in parallel with the nip, the material to be heated is also conveyed in parallel with the nip, and curling of the material to be heated immediately after passing through the nip can be prevented. In the image heating fixing device, the tendency of the recording material to curl in the convex direction on the printing surface is reduced.

C) The heating element holding member has a structure in which the immediately upstream portion of the heating element in the transport direction of the heating element does not protrude from the film side surface of the heating element toward the film side. Since the portion to be heated can be made wider and the nip portion of the material to be heated enters more smoothly, the probability of problems such as jamming of the material to be heated and wrinkling of the material to be heated is reduced.

D) Both ends of the most upstream side edge and the most downstream side edge of the heating element in the film moving direction are bent to the opposite side to the film, and the surface of the heating element holding member for holding the heating element is The contact area is sufficiently small because the heating element and the heating element holding member are in contact with each other by the thickness of the heating element, because the heating element and the heating element holding member are in contact with each other by a flat surface and a space provided between the heating element and the heating element holding member. In addition, since the escape of heat from the heating element to the heating element holding member is suppressed to a small extent, thermal energy can be efficiently supplied to the film and the material to be heated. Further, since it is not necessary to provide the space 21d between the heating element and the heating element holding member as shown in the conventional fixing device for heat insulation of the heating element, the heating element is disposed on the upstream side and the downstream side in the film moving direction. Even if the heating element is fixed at a position shifted from the heating element, a situation in which the heating element falls into the space 21d between the heating element and the heating element holding member does not occur.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIGS. 1 to 6) (1) Example of Image Forming Apparatus FIG. 1 shows a schematic configuration of an example of an image forming apparatus. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process.

An electrophotographic photosensitive member (hereinafter, referred to as a drum) 10 is driven to rotate clockwise as indicated by an arrow in response to an image formation start signal, and the surface of the rotating drum 10 is brought to a predetermined polarity and potential by a charger (not shown). Charged.

A laser beam L modulated in accordance with a time-series electric digital pixel signal of image information is output from a laser scanner 8 to the charged surface of the drum 10, and scanning exposure is performed via a mirror 9. By doing
An electrostatic latent image corresponding to the image information of the scanning exposure is sequentially formed on the surface of the drum 10. The latent image is then developed.
Is visualized as a toner image.

On the other hand, the recording material P in the paper feed cassette 1 is fed by the paper feed roller 7, and the U-turn guides 4-a, 4-a
The sheet is conveyed to the pair of registration rollers 5-a and 5-b through the sheet conveying path formed by -b. Then, the recording material P
Is transported between the transport guides 6-a and 6-b in synchronization with the rotation of the drum 10 by the pair of registration rollers 5-a and 5-b, and is transferred between the drum 10 and the transfer roller 12 which is in pressure contact with the drum 10. It is fed to the configured transfer unit. Then, the toner image Ta on the drum 1 side is sequentially transferred to the recording material P side.

The recording material P that has passed through the transfer section is separated from the surface of the drum 10 and introduced into the fixing device F along the guide 13, where the unfixed toner image Ta is heated and fixed to become a fixed image Tc.

Thereafter, the guide 29 and the conveying roller pair 33-
a, 33-b, and between the guides 34-a and 34-b, and is output as an image formed product (print) on the paper discharge tray 34 by the paper discharge roller pair 35-a, 35-b.

In the paper feed cassette 1, reference numeral 3 denotes a vertically swinging middle bottom plate, and reference numeral 2 denotes a spring member which pushes up and urges the middle bottom plate.

(2) Fixing Device F The fixing device F is a film heating type heating device according to the present invention. 2 is a cross-sectional model view of a main part, FIG. 3 is an exploded perspective view of the main part with a partial cutaway, and FIG. 4 is an enlarged model view of a fixing nip portion.

This film heating type fixing device F is a tension roller type device using a pressure roller driving system using a cylindrical fixing film 22, similarly to the fixing device shown in FIG. The same reference numerals are given to constituent members and portions common to the fixing device described above, and the description will not be repeated.

The heater 20 as a heating element is not a ceramic heater, but has a structure in which a resistance layer that generates heat by energization is provided on a metal substrate via an insulating layer, and the most upstream side edge and the most downstream side in the film moving direction. The metal substrate heater has a structure in which both ends of the side edge are bent to the opposite side to the film. The metal substrate heater 20 will be described later.

The heater holder 21 as a heater support member is made of a liquid crystal polymer, phenol resin, PPS, PEE.
It is a member having a substantially semicircular gutter-shaped cross section formed by K or the like,
A metal substrate heater 20 is fitted and supported in a groove 21a provided along the length of the holder on the lower surface of the heater holder 21.

The fixing film 22 is a cylindrical film material, and is loosely fitted to a heater holder 21 supporting the metal substrate heater 20. In this example, a fixing film in which a polyimide film having excellent thermal conductivity, heat resistance, and mold release properties is coated with a fluororesin is used.

The fixing film 22 is a member having a small heat capacity.
Polyimide, polyamide imide, PEEK, PES, PPS, PFA, with heat resistance and thermoplasticity with the following thickness
Films such as PTFE and FEP. In addition, a film having sufficient strength to form a long-life heat fixing device and having excellent durability and a thickness of 20 μm or more is required. Therefore, the thickness of the fixing film 22 is 20 μm
More than 100 μm is optimal. Further, in order to prevent offset and ensure the separability of the recording material P, the surface layer of the fixing film 22 is a mixture of a heat-resistant resin having good releasability, such as PFA, PTFE, FEP, or silicone resin, or coated alone. It is.

The elastic pressure roller 23 as a pressure member is
It consists of a metal core and an elastic layer formed by foaming heat-resistant rubber such as silicone rubber or fluorine rubber or silicone rubber on the outside thereof. PFA, PTFE, outside the elastic layer
A release layer such as FEP may be formed.

In order to rotate the fixing film 22 with low torque and smoothly by driving the elastic pressure roller 23, it is necessary to reduce the frictional resistance between the metal substrate heater 20 and the heater holder 21 and the fixing film 22. is there. Therefore, a small amount of a lubricant such as heat-resistant grease is interposed between the metal substrate heater 20 and the heater holder 21 and the fixing film 22.

(3) Metal substrate heater 20 FIG. 5 is an enlarged cross-sectional model view of the metal substrate heater 20, FIG.
3A and 3B are a partially cutaway plan view on the front side of the heater 20 and a plan view on the back side thereof.

The metal substrate heater 20 of this example uses a metal substrate obtained by press-forming a metal plate into a U-shape in cross section as the heater substrate 20m. The substrate surface on the bent leg sides 20r and 20r side of the metal substrate 20m is the back surface, and the substrate surface on the opposite side is the front surface.
0n is provided on the insulating layer 20n, a resistance layer 20b that generates heat by energization, and first and second conductive path patterns 20c.
20f, first and second electrode portion patterns 20d and 20e,
This is a structure provided with a surface protection layer 20p.

More specifically, a stainless (SUS) material having a thickness of 0.3 mm was used as the material of the metal substrate 20m. Two bent portions 20s, 20s with a U-shaped cross section
Of the corner R is 0.5 mm in radius and the metal substrate 20 m
Is 270mm long, 7mm wide and 2mm high
mm.

An insulating layer 20n coated with heat-resistant glass having a high insulating property is provided on the front side of the metal substrate 20m, and the electrically conductive metal substrate 20m, the resistance layer 20b, the first and second conductive paths are provided. The patterns 20c and 20f and the first and second electrode portion patterns 20d and 20e are electrically insulated.
Here, the thickness of the glass insulating layer 20n is 50 μm,
After the glass paste was printed by screen printing or the like, the glass paste was formed by firing.

The resistance layer 20b is formed on the insulating layer 20n along the length of the substrate. For example, an electric resistance material paste (resistive paste) such as silver palladium (Ag / Pb) or Ta ₂ N is applied to a thickness of, for example, 10 μm and a width of 10 μm. 1-3 mm
Is formed by coating and firing on a narrow band-shaped pattern by screen printing.

The first conductive path pattern 20 c is
On n, it is formed in a narrow band shape substantially in parallel with the above-mentioned resistance layer pattern. The first and second two electrode portion patterns 20d and 20e are formed on the metal substrate 20 on the insulating layer 20n.
a is formed side by side on the surface on the one end side in the longitudinal direction.

The first conductive path pattern 20c is extended at one end and is electrically connected to the first electrode pattern 20d in a series. In addition, one end of the resistive layer pattern 20b and the second electrode portion pattern 20e are electrically connected via the second conductive path pattern 20f. Resistive layer pattern 2
The other end of the first conductive path pattern 20c is electrically connected to the other end of the first conductive path pattern 20c.

Accordingly, the first electrode section pattern 20d → the first conductive path pattern 20c → the resistive layer pattern 20b → the second conductive path pattern 20f → the second electrode section pattern 20
e constitutes a series of electric paths (AC electric supply paths for the resistive layer pattern 20b, hereinafter referred to as AC lines).

The first and second electrode portion patterns 20d
.20e, first and second conductive path patterns 20c and 20f
Are formed by pattern-coating and baking a conductive material paste such as Ag by screen printing or the like.

The surface protective layer 20p has a thickness of, for example, 10 μm.
It is a heat-resistant glass layer of a degree. Except for the first and second electrode part patterns 20d and 20e, the surface on which the resistance layer pattern 20b and the first and second conductive path patterns 20c and 20f are formed is covered with this protective layer 20p. Pattern 20b, first and second conductive path patterns 20c
f is covered with this protective layer 20p and protected from abrasion and the like.

The metal substrate heater 20 has its front surface exposed downward, and is fitted and supported in a groove 21 a provided along the length on the lower surface of the heater holder 21.

A power supply connector 52 on the power supply circuit side is mounted on the end side of the metal substrate heater 20 on the side of the first and second electrode portion patterns 20d and 20e, and two elastic electrical contacts on the connector side are provided respectively. First and second electrode pattern 20
d. 20e is brought into an elastic contact state, whereby the AC line on the metal substrate heater 20 side and the power supply circuit (not shown) are electrically connected.

A thermistor 50 as a temperature detecting element is attached to the rear surface of the metal substrate 20m near the center of the substrate through a through hole 21e provided in the heater holder 21 so as to be in close contact with the substrate 20m by a spring (not shown). . Lead wires 51a and 51b are drawn out from the thermistor 50, and are electrically connected to a temperature control circuit (not shown) (DC line).

When power is supplied to the AC line of the metal substrate heater 20 from the power supply circuit, the resistance layer pattern 20b of the AC line generates heat over its entire length, and the entire metal substrate heater 20 rapidly rises in temperature. The temperature rise of the metal substrate heater 20 is detected by a thermistor 50 disposed on the back side of the heater, and the detected temperature information (DC current)
Is fed back from the DC line to the temperature control circuit. The temperature control circuit controls the power supply from the power supply circuit to the resistive layer pattern 20b of the AC line so that the heater temperature detected by the thermistor 50 is maintained at a predetermined substantially constant temperature (fixing temperature). That is, the metal substrate heater 20 is heated and adjusted to a predetermined fixing temperature.

Further, when the metal substrate heater 20 runs away, a temperature fuse (not shown) arranged in series with the AC line is activated, and the power supply to the heater is immediately shut off.

As described above, the heater as a heating element has a structure in which the resistance layer 20b that generates heat by energization is provided on the metal substrate 20m via the insulating layer 20n, and is located between the most upstream side edge in the film moving direction. Metal substrate heater 2 having a structure in which the end of the most downstream edge is bent to the opposite side to the film
0, the fixing film 22 and the heater 2
Even if the zero corner 20s contacts, the corner 20s is rounded, so that the fixing film 22 can smoothly slide on the rounded corner 20s. That is, unlike the ceramic heater 20A in the conventional example, even if the corner portion 20s of the metal substrate 20m slides on the inner surface of the fixing film 22, the resistance is sufficiently small. It is possible to move.

For this reason, as in the conventional apparatus using the ceramic heater 20A (FIG. 11), the heater holder 2
The fixing film 22 does not need to have the protrusions 21b and 21c.
Is a corner 20s formed by bending the end of the metal substrate 20m.
And the fixing film 22 is guided along a trajectory closer to a perfect circle (FIG. 2). As a result, the rotational resistance of the fixing film 22 can be suppressed to be lower than that of the conventional device, so that the image disturbance that may occur due to the slip between the recording material P and the fixing film 22 can be prevented.

Further, since the projection 21c on the downstream side of the heater holder 21 is no longer necessary, the fixing film 22 is also conveyed and guided in a straight line parallel to the fixing nip N even immediately downstream of the fixing nip N. Recording material P
Is also conveyed in parallel and linearly with the fixing nip N. Therefore, in the present embodiment, the tendency of the leading end of the recording material P to curl in the convex direction of the printing surface, which is a problem in the conventional apparatus, is reduced.

Further, since the protrusion 21b on the upstream side of the heater holder 21 is not required, the introduction portion E of the fixing nip portion N can be made wider, so that the recording material P can enter the nip portion more smoothly. become. Recording material P
As a result, the probability that a problem such as a paper jam or a paper wrinkle occurs can be further reduced.

The metal substrate heater 20 is connected to the metal substrate 2.
The bent leg sides 20r and 20r are in contact with the heater holder 21 at the thick portions of the bent leg sides 20r and 20r, and the bent leg sides 20r and 20r are provided between the back surface of the metal substrate heater 20 and the heater holder 21.
Serves as a spacer to form a heat insulating space, so that the contact area between the metal substrate heater 20 and the heater holder is small,
Since the escape of heat to the recording medium P is suppressed to a small value, heat energy can be efficiently supplied to the fixing film 22 and the recording material P side. Since there is no need to provide a space 21d between the ceramic heater 20A and the heater holder 21 as shown in the conventional apparatus for heat insulation of the heater, even if the heater 20 is fixed at a position shifted upstream and downstream. The situation where the heater 20 falls into the space 21d between the heater 20 and the heater holder 21 does not occur.

Second Embodiment (FIG. 7) In the first embodiment, the metal substrate 20 of the metal substrate heater 20 is used.
Although the end of m is bent at a substantially right angle, the cross section has a substantially U-shape. However, the cross section may be bent at an obtuse angle as shown in FIG. 7A and at an acute angle as shown in FIG. There is a similar effect.

The same effect can be obtained if the angle R is larger than about 0.3 mm.

<Embodiment 3> (FIG. 8) As shown in FIG.
Even if the end portion of the heater film 21 on the downstream side in the moving direction of the fixing film is bent to form an arc shape at the corner and the projection portion on the downstream side of the heater holder 21 is eliminated, the disturbance of the image is prevented and the recording is performed. There is an effect of improving curling in the convex direction of the printing surface at the leading end of the material P.

Embodiment 4 (FIG. 9) As shown in FIG. 9, the metal substrate 2 of the metal substrate heater 20
By bending only the end on the upstream side of the fixing film moving direction of 0 m to form an arc shape at the corner, even if the protrusion on the upstream side of the heater holder 21 is eliminated, disturbance of the image is prevented, and paper jams and wrinkles are prevented. There is an improvement effect on the problem.

<Embodiment 5> (FIG. 10) The heating device of the film heating system is not limited to the pressure roller driving system and the tensionless type as in the above-described embodiment. (A), (b), and (c) of FIG. 10 show other examples of the configuration of the film heating type heating device.

FIG. 7A shows a structure in which the metal substrate heater 20 supported by the heater holder 21 and the driving roller 24 are used.
An endless belt-shaped fixing film 22 is suspended between members, and the driving film 24 rotates the fixing film 22. The pressure roller 23 is a driven rotation roller.

(B) shows a metal substrate heater 20 supported by a heater holder 21 and a driving roller 24
And an endless belt-shaped fixing film 22 is stretched between three members of a tension roller 25 so that the driving roller 24
And the fixing film 22 is driven to rotate. The pressure roller 23 is a driven rotation roller.

(C) uses a rolled long end film as the fixing film 22, and feeds the metal film heater 20 supported on the heater holder 21 from the payout shaft 26 side to the pressure roller. In this configuration, the vehicle travels at a predetermined speed toward the winding shaft 27 via a nip portion with the take-up shaft 23. The pressure roller 23 is a driven rotation roller.

<Others> 1) The example in which a stainless steel material is used as the metal material of the metal substrate 20m as the heater substrate has been described. However, other than stainless steel, a metal material having good malleability and ductility is used. Can also obtain the effect of the present invention.

2) The example in which the metal substrate 20m is formed by bending a metal plate has been described. However, if the surface in contact with the fixing film has a smooth and substantially circular arc shape, processing such as sintering, casting, and forging is performed. The same effect can be obtained by using a metal substrate formed by the method.

3) Resistive layer pattern 2 that generates heat when energized
The number and pattern of 0b are not limited to those of the embodiment, but may be arbitrary. When a plurality of heat generating layers are used, the resistance value per unit length, the material, the width, the thickness, and the like can be different.

4) The metal substrate heater 20 of the embodiment is configured such that the resistance layer pattern 20b which generates heat when energized is
Insulating layer 20n on the front side of 0m (the side facing the fixing film)
An example is shown in which the insulating layer 20 is formed on the back side of the metal substrate 20m (the side opposite to the side facing the fixing film).
A structure formed through n may be used.

5) The heating device of the present invention is not only a heating and fixing device of the embodiment, but also an image heating device for heating a recording material carrying an image to improve its surface properties (such as gloss). It can be widely used as an image heating device for heating, a heating device for drying or heat laminating a sheet.

[0087]

As described above, according to the present invention, with respect to the film heating type heating device, the movement or rotation resistance of the film is reduced, and in the image heating fixing device, the slip between the recording material and the film is reduced. It is possible to prevent the resulting toner image from being disturbed. Curling of the material to be heated immediately after passing through the nip can be prevented. The heated material introduction portion at the entrance of the nip portion is widened so that the heated material can enter the nip more smoothly, and a heated material jam (paper jam) and a heated material wrinkle can be prevented. Reduce the contact area between the heating element and the heating element holding member, improve the heat insulation of the heating element,
Thermal energy can be efficiently applied to the material to be heated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 2 is a schematic cross-sectional view of a main part of the heat fixing device according to the first embodiment.

FIG. 3 is an exploded perspective view of the device with a partial cutaway.

FIG. 4 is an enlarged model diagram of a fixing nip portion.

FIG. 5 is an enlarged cross-sectional model diagram of a metal substrate heater.

FIG. 6A is a partially cutaway plan view of the heater front side, and FIG. 6B is a plan view of the heater back side.

FIGS. 7A and 7B are enlarged cross-sectional schematic views of a metal substrate heater according to Embodiment 2. FIG.

FIG. 8 is an enlarged model view of a fixing nip portion of a heat fixing device according to a third embodiment.

FIG. 9 is an enlarged model diagram of a fixing nip portion of a heat fixing device according to a fourth embodiment.

FIGS. 10A, 10B, and 10C are schematic diagrams of another configuration example of a film heating type heating device.

FIG. 11 is a schematic diagram of a conventional apparatus.

[Explanation of symbols]

20. Heating element (metal substrate heater), 21. Heating element holding member (heater holder), 22. Film (fixing film), 23 .. Pressure member (pressure roller), P.
-Heated material (recorded material), 20m-Metal substrate, 20n
..Insulating layer, 20b

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Shinmura 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H033 AA15 AA30 AA32 BA08 BA09 BA25 BA26 BB30 BB33 BB34 BB37 BB38 BE03 3K058 AA00 BA18 CA61 CE12 CE19 DA04 GA06 3K092 PP18 QA05 QB02 QB64 QB76 RF03 RF09 RF13 RF22 SS12 TT30 UA06 VV40

Claims (8)

[Claims] 1. A heating element, a heating element holding member for fixing and holding the heating element, a film sliding on the heating element, a pressure member forming a nip with the heating element via the film, In the heating device, wherein the material to be heated is nipped and conveyed in the nip, and the material to be heated is heated by heat from the heating body through the film, the heating body includes an insulating layer formed on a metal substrate. Having a structure in which a resistance layer that generates heat by energization is provided, and at least one end of the most upstream side edge and the most downstream side edge in the film moving direction is bent to the opposite side to the film. Heating equipment. 2. The heating element holding member according to claim 1, wherein a portion of the heating element immediately downstream of the heating element in the direction in which the material to be heated is conveyed does not project from the surface of the heating element on the film side to the film side. A heating device as described. 3. The heating element holding member according to claim 1, wherein a portion of the heating element immediately upstream of the heating element in the transport direction of the material to be heated does not project from the surface of the heating element on the film side to the film side. A heating device as described. 4. Both ends of a most upstream side edge and a most downstream side edge of the heating element in a film moving direction are bent to the opposite side to the film, and the heating element of the heating element holding member is The heating device according to any one of claims 1 to 3, wherein a surface to be held is a flat surface, and a space is provided between the heating body and the heating body holding member. 5. The heating device according to claim 1, wherein the film has an endless belt shape. 6. The apparatus according to claim 1, wherein said film is moved and driven by rotation of said pressing member.
The heating device according to any one of the above. 7. The heating apparatus according to claim 1, wherein the material to be heated is a recording material carrying an image. 8. An image forming apparatus having image forming means for forming and carrying an image on a recording material and fixing means for heating and fixing the image on the recording material, wherein the fixing means is any one of claims 1 to 6. An image forming apparatus, comprising: the heating apparatus according to claim 1.