JPH08339131A - Heating device and image forming device - Google Patents

Abstract

PURPOSE: To maintain the nearly uniform distribution of a nip width and press- contact force in the longitudinal direction of a press-contact nip part by arrang ing a reinforcing member for preventing the deflection of a heating member support, caused by pressure. in the longitudinal direction of the heating member support. CONSTITUTION: A rigid reinforcing member (stay) 39 is arranged in the longitudinal direction of a heater holder 34 as the heating member support, in its inside bottom part. The reinforcing member 39 is a channel member having a nearly inverted U-shaped cross-section and both longitudinal side edge parts of the opening part facing downward are bent over the entire length, to face inward each other and obtain a hook-like cross-section. The hook-like bent parts 39a are fitted and engaged with hook-like groove parts 34a formed to provide in the longitudinal direction of the heater holder 34 in its inside bottom part, from one end side of the holder 34 and slid to the inside of the holder 34, to be actually integrally arranged with the holder 34 in its longitudinal direction, in the inside bottom part of the holder 34. Since the rigid reinforcing member 39 exists, the heater holder 34 is hardly deflected by the pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device and an image forming apparatus.

More specifically, a heat-resistant film is sandwiched between a heating member and a pressure member, which are fixedly supported by a support, and pressure-contacted to the heat-resistant film. The present invention relates to a heating device for introducing a member to be heated and moving the pressure contact nip portion together with the heat resistant film to apply the heat energy of the heating member to the member to be heated via the heat resistant film.

The present invention also relates to an image forming apparatus provided with the heating device as an image heating device for heating an image on a recording material.

[0004]

2. Description of the Related Art For example, printers, copying machines, recording devices,
In an image forming apparatus such as a facsimile, a recording material (transfer material, electrostatic recording paper, electro-photographic paper Form and carry an unfixed image corresponding to the desired image information on fax paper, printing paper, printing paper, etc.
This is heat-treated to heat-fix the unfixed image on the recording material to obtain an image-formed product, or to presumably attach the image,
A heat roller type heating device has been widely used as an image heating device for modifying the surface properties such as gloss of an image formed product.

Recently, a film heating type heating device has been proposed and put into practical use (Japanese Patent Laid-Open No. 63-313).
No. 182, Japanese Patent Application Laid-Open No. 1-263679, Japanese Patent Application Laid-Open No. 2-157878, and Japanese Patent Application Laid-Open Nos. 4-44075-44.
No. 083 / JP-A-4-204980-204984
Issue).

(A) Heat Roller Type Heating Device FIG. 10 is a schematic diagram of an example of a heat roller type image heating device.

That is, a metal heat roller 21 having a heat source H such as a halogen heater therein and whose temperature is controlled and controlled at a predetermined fixing temperature, and an elastic pressure roller 2 which is pressed against the metal heat roller 21.
2, a pair of rollers 21 and 22 are rotated to rotate the pair of rollers 21 and 22 to form a pressure contact nip portion (fixing nip portion) N.
By supplying the recording material P as a heated member from the image forming means A to the fixing nip N and passing it through, the recording by the heat of the heat roller 21 and the pressing force of the fixing nip N is performed. The unfixed image T on the material P is fixed to the recording material.

In the image forming means A, 2 is an electrophotographic rotary photosensitive drum as an image bearing member, and a toner image T of desired image information is formed on its peripheral surface by a known image forming process device (not shown). The toner images are sequentially transferred onto the surface of the recording material P introduced into the pressure contact nip portion (transfer nip portion) n between the photosensitive drum 2 and the transfer roller 6 and conveyed to the fixing portion of the image heating device. .

In this heat roller type image heating apparatus, since the heat capacity of the heat roller 21 is large, it takes a very long time (wait time, warming time) to raise the surface of the heat roller 21 to a predetermined fixing temperature. I needed it. Therefore, in order to execute the image output operation promptly,
Even when the apparatus is not used, the temperature of the surface of the heat roller must be controlled to a certain temperature, and there is a problem that power consumption increases.

(B) Film heating type heating device As described above, in this heating device, the heat-resistant film is sandwiched between the heating member and the pressing member, which are fixedly supported by the support, and pressure-contacted. , Introducing a member to be heated between the heat resistant film and the pressure member in the pressure contact nip portion and moving the pressure contact nip portion together with the heat resistant film to transfer the heat energy of the heating member through the heat resistant film. It is a heating device for applying the unfixed toner image to the member to be heated, and can be utilized as an image heating and fixing device for heating and fixing the unfixed toner image as a permanently fixed image on the surface of the recording material carrying the image. Further, for example, it can be widely used as an apparatus for heating a recording material carrying an image to modify the surface properties such as gloss, a hypothetical adhesion processing apparatus, and an apparatus for heating a sheet-shaped heating material.

Since such a film heating type heating device can use a heating member having a low heat capacity or a thin heat-resistant film that quickly heats up, the temperature of the heating member rises in a short time, and it is It is no longer necessary to electrically heat the heating member, and in the image heating apparatus, even if the recording material as the heated member is immediately passed, the heating member is set to the predetermined position by the time the recording material reaches the fixing portion. It has the advantages of being able to raise the temperature to a sufficient temperature, saving power and shortening the wait time (quick startability), and lowering the temperature rise inside the machine such as the image forming apparatus. Have and be effective.

FIG. 8 shows a schematic diagram of the essential part of an example of a film heating type heating device (image heating device).

Reference numeral 33 denotes a ceramic heater as a heating member having a structure described later, which is a horizontally long member having its longitudinal direction perpendicular to the drawing (hereinafter referred to as a heater). 34 is a heat-resistant heater holder as a heating member support,
It is a laterally elongated member having a longitudinal direction perpendicular to the drawing. The heater 33 is fixedly supported on the lower surface side of the heater holder 34 via a heat resistant adhesive. 35 is a heat resistant (fixing) film (hereinafter abbreviated as film). Reference numeral 36 is a heat-resistant pressure roller having a rubber elastic layer having a good releasability such as silicon rubber as a pressure member.

The heater 33 and the pressure roller 36 are connected to the film 3
5 are sandwiched and pressed together. Specifically, the longitudinal ends of the heater holder 34, which has the heater 33 fixedly supported on the lower surface side, are applied with pressure springs or the like to the pressure roller 36 whose both end shafts are rotatably fixedly supported by bearings. By pressing each in the direction of the pressure roller 36 by the pressure means, the heater 33
The film 35 is sandwiched between the lower surface and the upper surface of the pressure roller 36 to be pressed against the elasticity of the roller. N is film 3
5 is a pressure contact nip portion (fixing nip portion) formed between the heater 33 and the pressure roller 36 with 5 interposed therebetween.

The film 35 generally has a total thickness of 100 μm.
m or less, preferably 40 μm or less, which is a thin film excellent in heat resistance, releasability, durability, etc., such as PI (polyimide), polyetherimide, endless belt-shaped film or cylindrical film, or rolled film. A long end film, which is held in close contact with the lower surface of the heater 33 in the pressure contact nip portion N by using a film driving means (not shown) or a pressure roller 36 as a driving member while sliding on the lower surface of the heater. It is rotated, rotated or driven at a predetermined speed in the direction indicated by the arrow.

As will be described later, the heater 33 rapidly raises the temperature due to the heat generated by the energization heat generating resistor 33b when it is energized.

The film 35 in the pressure contact nip portion N and the pressure roller are brought into close contact with the lower surface of the heater 33 by sliding the film 35 and the heating member 33 is heated to a predetermined temperature by energizing the heating resistor 33b. The recording material P to be image-fixed as a member to be heated is introduced between the recording material 36 and the film 36, and the pressure contact nip portion N is nipped and conveyed together with the film 35.
Heater substrate 33 heated by the heat generated by the resistor and the heat generated by the resistor.
The heat of a is applied to the recording material P via the film 35, and the unfixed visible image T on the recording material P is heated and fixed on the surface of the recording material P. The recording material P passing through the pressure nip portion N is separated from the surface of the film 35 and conveyed.

FIG. 9 is a plan view of a ceramic heater 33, which serves as a heating member, with an intermediate portion omitted and partially cut away. The heater 33 is an elongated ceramic substrate 33a having heat resistance, insulation, and good thermal conductivity, whose longitudinal direction is perpendicular to the transport direction a of the film 35, and a substantially central portion in the lateral direction on the surface side of the substrate. An electric heating resistor 33b formed in a linear or strip shape along the longitudinal direction of the substrate, and power feeding electrodes 33c, 33c made of Ag or the like formed by screen printing on both longitudinal ends of the electric heating resistor. An overcoat layer (surface protection layer) 33d made of heat-resistant glass, fluororesin, or the like, which covers and protects the heater surface on which an electric heating resistor is formed, and a temperature detecting element 33e such as a thermistor, which is provided on the back side of the substrate and detects the heater temperature. It is a horizontally long heater with a low heat capacity as a whole.

The heater substrate 33a has, for example, a length of 240.
mm, width 10 mm, thickness 1 mm, ceramic base material such as alumina having heat resistance, electrical insulation and low heat capacity.

The energization heating resistor 33b is made of, for example, an electric resistance material paste (resistive paste) such as silver palladium (Ag / Pb) .Ta ₂ N having a thickness of 10 to 20 μm.
It is formed by applying a thin strip having a width of 1 to 3 mm along the longitudinal direction of the ceramic substrate surface by screen printing or the like and firing. Glass or a fluororesin is coated on it as a protective layer 33d.

The heater 33 is composed of an electric heating resistor 33b.
Heater holder 3 with the front side facing downward
4 is fixed and supported, and the current is generated by heating the energization heating resistor 33b over the entire length by supplying power between the electrodes 33c and 33c at both ends, and the temperature is raised.
3e is detected, the detected temperature is fed back to a temperature control circuit (not shown), and the energization of the energization heating resistor 33b is controlled so that the temperature of the heater 33 is maintained at a predetermined fixing temperature.

The present invention particularly relates to improvement of the film heating type heating device of the above (b).

[0023]

[Problems to be solved by the invention]

a) In the film heating type heating device as described above, the pressure contact nip portion N formed by sandwiching the heat resistant film 35 between the heater 33 as a heating member and the pressure roller 36 as a pressure member is In order to secure sufficient heating performance / fixing performance and stable film / heated member transport performance, it must have a predetermined sufficient nip width / pressure contact force. It is desirable to have a substantially uniform distribution along the length.

However, as described above, in order to form the pressure contact nip portion N, both ends in the longitudinal direction of the heater holder 34 as a heating member support body in which the heater 33 is fixedly supported by the stationary pressure roller 36. Are pressed in the direction of the pressure roller 36 by a pressure means such as a pressure spring to sandwich the film 35 between the lower surface of the heater 33 and the upper surface of the pressure roller 36 against the roller elasticity. The nip along the length of the pressure contact nip portion N due to the bowing of the heater holder 34 in the direction in which the center portion of the heater floats away from the pressure roller 36 due to the pressing force applied to the both ends of the heater holder 34. The width and pressure contact force is the pressure contact nip N
Both longitudinal ends-large, central part-small distribution form.

When the pressure applied to both longitudinal ends of the heater holder 34 is increased, the difference in the nip width between the longitudinal ends of the pressure contact nip N and the central portion and the difference in the pressure contact force become large. The fixing property of the toner to the recording material P is lowered in a portion corresponding to the longitudinal center portion of the pressure contact nip portion N, and the film 35 or the recording material P is disposed between the longitudinal center portion and the end portion of the pressure contact nip portion N. There is a difference in the conveyance speed of the recording medium P, and the film 35 and the recording material P are wrinkled.

In order to suppress this phenomenon, the heater holder 3
There is also a method of attaching a crown to 4 to correct the amount of deflection,
The continuous use of the heating device causes the heater holder to undergo creep deformation, which makes it impossible to maintain an appropriate crown shape.

Further, by slightly setting the pressure force applied to both longitudinal end portions of the heater holder 34, the difference in nip width / pressure contact force between both end sides along the length of the pressure contact nip portion N and the central portion can be reduced. If the nip width is insufficient and the pressure contact force is insufficient, the heating performance and the fixing performance are deteriorated, and the transport stability of the film 35 and the recording material P is deteriorated.

From the above, in the conventional device,
The pressurizing force applied to both longitudinal end portions of the heater holder 34 does not cause the heater holder 34 to bend more than allowable, and undesirably deteriorates the heating performance and fixing performance due to insufficient width and insufficient pressure contact force of the entire nip, and the film 35 and the object to be covered. At a relatively low pressure level within a range that does not cause deterioration of the conveyance stability of the recording material P,
And it was set within the narrow pressing force range. Specifically, the pressure applied to both longitudinal ends of the heater holder 34 was set to about 1 to 1.5 kg on one side.

B) A small size recording material which is narrower than a recording material as a heated member having a maximum paper passage width that can be used for paper feeding to the apparatus and heat-treated, for example, the maximum paper passing width is A4 size. When a B5 size or 100 mm wide envelope is passed through the heating device, a non-sheet passing region of about 40 mm to 110 mm is formed in the effective heating length region of the pressure contact nip portion N.

Since heat is not taken by the recording material in the non-paper passing area, the temperature gradually rises (the temperature of the non-paper passing portion) when the paper is continuously passed, and the area of the paper non-passing area is gradually increased. Temperature difference is 100d
It will be over eg. When such a temperature rise of the non-sheet passing portion occurs, the following problems occur.

[0031] The pressure roller 36 becomes hot and the rubber material is deteriorated.

[0032] Due to the temperature difference between the portion of the pressure roller 36 corresponding to the paper passing area and the portion corresponding to the non-paper passing area, the thermal expansion of both pressure roller portions becomes non-uniform, and the roller outer diameter difference in the axial direction is reduced. As a result, a difference occurs in the feed amount of the film 35. In particular, in a sheet-passing type apparatus that transports the recording material P with one side end as a reference, the film may be twisted and damaged if a difference in the feed amount occurs in the film width direction.

.. After passing a small size recording material, both the film part and the pressure roller part of the non-paper passing part are at high temperature. Hot offset occurs in an over-melted state.

Therefore, an object of the present invention is to solve the above problems a) and b) of the film heating type heating device.

That is, in order to secure sufficient heating performance / fixing performance and stable film / heated member transport performance, the pressure contact nip portion formed between the heating member and the pressure member by sandwiching the heat-resistant film. It is possible to have a necessary and sufficient predetermined nip width and pressure contact force, and to make the nip width and pressure contact force have a substantially uniform distribution along the length of the pressure contact nip portion.

Further, it is possible to prevent or alleviate the temperature rising phenomenon of the non-sheet passing portion and solve the problems (1) to (3) due to the temperature rising phenomenon of the non-sheet passing portion.

[0037]

The present invention is a heating device and an image forming apparatus characterized by the following configurations.

(1) A heat-resistant film is sandwiched between a heating member and a pressure member, which are fixedly supported by a support, and pressure-contacted to each other. In a heating device for introducing a member to be heated into the heating member and moving the pressure contact nip portion together with the heat resistant film, the heat energy of the heating member is applied to the member to be heated through the heat resistant film. The heating device is characterized in that a reinforcing member for preventing pressure deflection of the heating member support is arranged over the length of the heating device.

(2) The heating device according to the above (1), wherein the reinforcing member of the heating member support has high thermal conductivity.

(3) The heating member is a recording material carrying an image, and is an image heating device for heating the image of the recording material. (1) or (2) Heating device.

(4) The image forming means for forming an image on the recording material and the heating device described in (1) or (2) above are used to heat the image on the recording material from the image forming means side. An image forming apparatus provided as an image heating device.

[0042]

The heat-resistant film is sandwiched between the heating member support and the heating member by pressing the heating member support by arranging a reinforcing member having high rigidity to prevent the heating member support from bending under pressure. In order to form a pressure contact nip portion with the member,
Even if a high pressure is applied to both ends of the heating member support, it is possible to substantially prevent bowed bending deformation with respect to the length of the heating member support, or to make the degree of bending deformation extremely small. You can

Therefore, it is necessary to apply a high pressure to both ends of the heating member support to secure sufficient heating performance / fixing performance and stable film / heated member transport performance in the pressure contact nip portion. A sufficient predetermined nip width and pressure contact force can be obtained, and the nip width and pressure contact force can be made to be substantially evenly distributed along the length of the pressure contact nip portion, so that a device with good performance can be configured.

Further, by making the above-mentioned reinforcing member provided on the heating member support member have high thermal conductivity, the heat of the heating member portion of the non-sheet passing portion temperature rising portion corresponds to the heating member portion. It is quickly transmitted to the high heat conductive reinforcing member through the support portion, diffused to the reinforcing member and radiated, or heat is transferred to the reinforcing member paper passing area portion side with a thermal gradient, and Excessive temperature rise of the heating member portion, the heat resistant film portion, and the pressing member portion can be suppressed. That is, the temperature rise of the non-sheet passing portion can be effectively reduced.

[0045]

【Example】

<Embodiment 1> (FIGS. 1 to 3) FIG. 1 is a schematic diagram of an image heating apparatus (image heating and fixing apparatus) 11 as a film heating type heating apparatus according to the present invention. The device of this example is a so-called tensionless type film heating system device disclosed in JP-A-4-44075 to 44083, JP-A-4-204980 to 204984, and the like, and a cylindrical heat-resistant film 35. At least a part of the circumference of the film is tension-free (state in which no tension is applied), and the film is rotatably driven by the rotation driving force of a pressure roller 36 as a pressure rotator. is there.

Heater holder 34 as a heating member support
Is a gutter-shaped member having a substantially semi-circular cross-section that also serves as a film inner surface guiding member. A ceramic heater 33 as a heating member is fitted in a groove formed along the length on the outer lower surface of the heater holder 34 to provide heat resistance. It is fixed with an adhesive and supported.

The ceramic heater 33 has, for example, the same structure as that shown in FIG. 9 and therefore will not be described again.

Reference numeral 39 denotes a rigid reinforcing member (stay) arranged on the inner bottom surface of the heater holder 34 serving as the heating member support member along the length of the holder.

The reinforcing member 39 of this example is a channel member having a substantially inverted U-shaped cross section, and both longitudinal edges of the downward opening are bent inward toward each other over the entire length to form a key shape in the cross section. The key-shaped bent portion 39a.3
9a is fitted and engaged with key groove portions 34a, 34a formed on the inner bottom surface of the heater holder 34 over the length of the holder from one end of the holder 34 and slidably moved to the inside of the holder 34. Is substantially integrally formed with the holder 34 on the inner bottom surface of the holder over the length of the holder. Due to the presence of the rigidity reinforcing member 39, the heater holder 34 is less likely to bend under pressure.

The cylindrical film 35 is fitted onto the heater holder 34 including the ceramic heater 33 and the reinforcing member 39. A heater holder 3 including the inner circumferential length of the cylindrical film 35, the ceramic heater 33, and the reinforcing member 39.
The outer peripheral length of the film 35 is larger than that of the film 35 by, for example, about 3 mm.
3. The heater holder 34 including the reinforcing member 39 is loosely fitted to the heater holder 34 with a sufficient circumferential length. The upper surface portion of the reinforcing member 39 is arranged in the vicinity of the inner surface of the film 35 so as to come into contact with or lightly contact with it. In this example, they were contacted.

The heater holder 34 is arranged above the stationary supporting pressure roller 36, and both ends of the holder 38 in the longitudinal direction are each pressed by a pressure spring (not shown) at 3.25 kg on each side.
The pressing roller 36 is pressed with a pressing force of
The lower surface (front surface) of 3 is sandwiched with the film 35 and is pressed against the upper surface of the pressure roller 36 against roller elasticity.

The pressure roller 36 as a pressure rotator comprises a metal core 36a and an elastic layer 36 of heat resistant rubber such as silicone rubber.
b and the surface coating layer 36c, the bearing is held rotatably by a bearing means (not shown). The pressure roller 36 is rotationally driven counterclockwise as indicated by an arrow by the rotational driving force transmitted by the driving means M via a power transmission system (not shown).

The rotation of the pressure roller 36 causes a frictional force between the roller 36 and the outer surface of the film 35 to cause the film 3 to move.
5, the rotational force acts directly on the recording material 5 (when the recording material P is introduced into the pressure contact nip portion N, the rotational force indirectly acts on the film 35 via the recording material P), The heater 33 is rotationally driven in the clockwise direction a indicated by an arrow while sliding in pressure contact with the lower surface of the heater 33. Gutter-shaped heater holder 34 having a substantially semi-circular cross section
Also functions as a film inner surface guide member, and the film 3
5. Rotate 5 easily. Inner surface of film 35 and heater 3
In order to reduce the sliding resistance with the lower surface of No. 3, it is preferable to interpose a small amount of lubricant such as heat resistant grease between them.

Then, an unfixed image to be fixed on the image, which is to be fixed, based on the pressing of the copy button of the copying machine such as a copying machine or the print command signal, or the image conveyed from the image forming means (not shown) to the fixing device 11. The pressure roller 36 is started to rotate based on a signal when the front end of the recording material P supporting the agent image T is detected by a sensor (not shown) arranged on the front side of the fixing device. Heat-up of the heater 33 is started.

The film 35 is rotated by the rotation of the pressure roller 36.
In the state where the rotational peripheral speed of the heater is stabilized and the temperature of the heater 33 rises to a predetermined value, the film 35 and the pressure roller 36 in the pressure contact nip portion N formed by the heater 33 and the pressure roller 36 with the film 35 interposed therebetween. The recording material P to be image-fixed as a material to be heated is introduced between
The heat of the heater 33 is applied to the recording material P via the film 35 by being nipped and conveyed together with the pressure contact nip portion N, and the unfixed visible image T on the recording material P is heated on the surface of the recording material P. It is fixed. The recording material P passing through the pressure nip portion N is separated from the surface of the film 35 and conveyed.

In the tensionless type film heating type apparatus of this embodiment, when the film is driven to rotate, the pressure contact nip portion N, the outer surface portion of the heater holder 34 upstream of the pressure contact nip portion N in the film rotation direction, and the film 35. The tension acts only on the film portion in the contact area B with the upper surface of the reinforcing member 39 and the film 35,
Tension does not act on most of the rest of the film.

Therefore, the shift force of the film 35 along the length of the heater holder 34 is small when the film is rotationally driven, and the shift control means for the film 35 or the film shift control means can be simplified. For example, the deviation control means of the film 35 can be a simple one such as a flange member that receives the film end portion, and the film deviation control means can be omitted to reduce the cost and size of the apparatus.

A. Fixing Film 35 The fixing film 35 as a heat resistant film has a total film thickness of about 100 μm in order to reduce the heat capacity and improve the quick start property, and the heat resistance, releasability, strength, durability, etc. Single layer of PTFE, PFA, FEP, etc., or polyimide, polyamide, PEEK, P
PTFE, PFA, FEP on the outer peripheral surface of ES, PPS, etc.
A composite layer film coated with etc. can be used. In this example, the outer peripheral surface of the polyimide film was coated with PTFE, and the layer thickness was 60 μm.

B. Heater Holder 34 The heater holder 34 as a heating member support body adiabatically supports the ceramic heater 33 as a heating member, and
It also serves as a guide member for the inner surface of the fixing film 35. This heater holder 34 is made of PPS, PAI, PI, PEE.
PPS is used in this embodiment, which is made of a high heat resistant resin such as K or liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass, or the like.

C. Pressure Roller 36 The pressure roller 36 includes a cored bar 36a having an outer diameter of 10 mm, a silicone rubber layer 36b having a length of 220 mm and a thickness of about 3 mm, and a surface layer 36c of Fluoro latex coat (GLS213 manufactured by Daikin Co., with 10 wt. % Mixed)
Hardness of 50 ° (As
kerC hardness roller part.

D. Heater holder reinforcing member 39: The reinforcing member 39 is a rigid member arranged longitudinally in the heater holder 34 as a heating member support as described above, and is deformed or creeped by pressing the heater holder 34 against the pressure roller 36. prevent.

As described above, the both ends of the heater holder 34 are pressed by the springs or the like to be pressed against the pressing roller 36, but since the reinforcing member 39 is inside, the deformation due to the spring pressing is suppressed. Further, even when an arbitrary crown is attached to the heater supporting surface of the heater holder 34, it is possible to suppress a change in the crown amount due to creep deformation of the heater holder 34 during spring pressure or heat generation of the heater.

By providing the reinforcing member 39 with high thermal conductivity, the heat of the heater portion in the non-sheet-passing portion temperature rising portion is quickly transferred to the high thermal conductive reinforcing member 39 via the heater holder portion corresponding to the portion. To the reinforcing member 39, and is dissipated into the reinforcing member 39 to dissipate heat, or heat is transferred to the reinforcing member paper passing area portion side with a thermal gradient, and the heating member portion, the heat resistant film portion and the pressing member portion in the non-paper passing portion area Excessive temperature rise is suppressed and the temperature gradient is reduced. That is, the temperature rise of the non-sheet passing portion can be effectively reduced.

By arranging the upper surface of the reinforcing member 39 so as to be in contact with or lightly contact with the inner surface of the film 35, the heat of the film 35 is also conducted to the reinforcing member 39 in that part as well. It serves to reduce the temperature gradient of 35.

When small-sized paper is continuously passed through the apparatus of this structure, the temperature rise of the temperature of the film 35 in the non-sheet-passing portion can be suppressed lower than that of the conventional one by the presence of the reinforcing member 39. At this time, the heat absorbed by the reinforcing member 39 in the non-sheet passing portion of the film 35 flows to the portion of the reinforcing member 39 which hits the sheet passing portion of the film 35, and this heat is reversed.
Since the paper-passing portion is heated, the temperature difference between the non-paper-passing portion and the paper-passing portion of the film 35 is further reduced. That is, the reinforcing member 3
9 also has the effect of smoothing the temperature gradient between the non-sheet passing portion and the sheet passing portion of the film 35.

Here, the cooling effect provided on the film 35 and the effect of reducing the temperature gradient accompanying it also act on the pressure roller 36, and in the apparatus having the structure in which the pressure roller 36 is also used as the drive roller as in this example. Thus, it is possible to suppress the occurrence of twisting due to the difference in the feed amount of the film in the longitudinal direction of the pressure roller 36, which has been a problem in the past. Further, deterioration of the rubber material used for the pressure roller 36 due to heat can be suppressed.

The reinforcing member 39 uses a metal having high thermal conductivity in order to absorb the heat of the film 35. In addition, the Young's modulus is 1.0 kg in order to prevent the deformation of the heater holder 34.
It is preferable to use a metal of not less than / cm ² . Specifically, various iron materials, stainless steel, nickel, copper and the like can be used. Further, in order to maintain rigidity over the length, it is preferable that the second moment of area of the reinforcing member 39 is 1000 mm ⁴ . The product of Young's modulus and second moment of area is 0.1 kg
It may be cm ² or more, but use of a metal having a low Young's modulus is not preferable in terms of cost and weight.

In this embodiment, the reinforcing member 39 is 1.0 mm.
A thick stainless steel material was used to form a channel member structure having a substantially inverted U-shaped cross section as shown in FIG. 1, and a second moment of area was set to about 1600 mm ⁴ .

By using the above-described heating device of the present embodiment as an image heating and fixing device of an image forming apparatus, toner fixability to paper as a recording material, film vs pressure roller nip measurement, and pressure roller The temperature rise measurement and the twist test of the film were performed. The temperature of the heater 33 is 1
The temperature was controlled at 60 ° C.

1) Fixability The fixability was evaluated by rubbing the image after toner fixing with sillbon paper.

In this example, the fixability was good, and there was no change in the fixability from the initial stage to 10,000 sheets.

2) Film vs. Pressure Roller Nip Measurement The width of the nip portion N was measured by pulling out a solid black image for 10 seconds between the heated film-pressure roller nip and pulling it out.

The initial nip width of this embodiment was about 4 mm, and there was almost no difference between the central portion and the end portion. Also, after 10,000 sheets were durable, there was almost no change from the initial stage.

3) Measurement of temperature rise of pressure roller and twist of film FIG. 2 shows a sheet passing portion when an envelope (width 105 × length 241 mm) is continuously fed at a process speed of 24 mm / sec and a sheet gap of 150 mm. The temperature of the pressure roller and the pressure roller temperature of the non-sheet passing portion are measured by thermography (thermo tracer, manufactured by Niden Sanei Co., Ltd.).

As can be seen from this figure, the temperature difference between the paper-passing portion and the non-paper-passing portion of the pressure roller is 70 d for continuous sheet feeding of 30 sheets or more.
It was EG, and twisting of the film did not occur even after 100 sheets were continuously fed.

(Comparative Example) In the case where the reinforcing member 39 is not provided, if the pressure applied to both ends of the heater holder 34 is large, the pressure deflection of the heater holder 34 becomes large.

In the apparatus according to the first embodiment described above, the pressure applied to both longitudinal ends of the heater holder 34 is 3.25K on one side.
In the heater holder 34, the reinforcing member 39 is not changed.
If the heater is not provided, the pressure deflection of the heater holder 34 is large. Therefore, the nip width along the length of the nip portion is 2 m at the central portion.
There was a difference of about 4 mm in m and the end portion of 6 mm, resulting in a non-uniform distribution.

As a result, the fixing property was poor at the center of the image from the initial stage, and the pressure roller 36 became dirty as the durability was advanced, and paper as a recording material was wound around the pressure roller.

FIG. 3 shows the measurement results of the temperature of the pressure roller in the paper passing portion and the temperature of the pressure roller in the non-paper passing portion of this apparatus.
Shown in The temperature difference between the paper passing portion and the non-paper passing portion of the pressure roller is about 60 deg for 10 continuous sheets and about 100 deg for 20 sheets.
The number of sheets was about 110 deg. According to the study by the present inventor, the temperature difference between the paper passing portion and the non-paper passing portion of the pressure roller 36 is about 1 or less.
It has been found that when the film thickness is 00 deg or more, the film 35 is likely to be twisted or wrinkled.

Therefore, in the case where the reinforcing member 39 is not provided, as described above, the pressure applied to both longitudinal end portions of the heater holder 34 is set to be a light weight of about 1 to 1.5 kg on one side, so that the length of the press contact nip portion N becomes longer. The difference between the nip width and the pressure contact force between both end sides along the center is made small, but in this case, the heating performance and the fixing performance are deteriorated due to the overall insufficient nip width and the pressure contact force, and the film 35 or Recording material P
Therefore, the transport stability of the sheet will be deteriorated.

<Embodiment 2> In the apparatus of Embodiment 1 described above, the pressure applied to both ends of the heater holder 34 in which the reinforcing member 39 is arranged is increased by increasing the spring pressure from 3.25 kg on one side to 7 kg on one side. The same test was conducted to evaluate the fixability and the film vs. pressure roller nip.

In this embodiment, the reinforcing member 39 is arranged so that its upper surface portion is in non-contact with the inner surface of the film 35 with a clearance of about 1 mm.

Fixability: The fixability was good as in Example 1, and there was no change in the fixability from the initial stage to 10,000 sheets.

Film vs. pressure roller nip: The width of the nip portion N was 5 mm at the end portion and 3.5 mm at the central portion, and the difference in the nip width was about 1.5 mm larger than that in Example 1, but the durability of 10,000 sheets was obtained. It didn't change when I went.

Thus, the reinforcing member 3 is attached to the heater holder 34.
By arranging 9, the high pressure is applied to both ends of the heater holder without any hindrance, and the pressure contact nip portion N secures sufficient heating performance / fixing performance and stable film / heated member transport performance. The necessary and sufficient predetermined nip width and pressure contact force can be obtained, and the nip width and pressure contact force can be made to be substantially evenly distributed along the length of the pressure contact nip portion, and a device with good performance can be configured. .

<Third Embodiment> (FIG. 4) FIG. 4 is a schematic configuration diagram of an example of an image forming apparatus using the heating device of the first or second embodiment as the image heating and fixing device 11. The image forming apparatus of this example is a laser beam printer using an electrophotographic process.

Reference numeral 1 is an apparatus casing, and 2 is an electrophotographic photosensitive drum as an image bearing member, which is rotationally driven in a clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed).

During the rotation process of the photosensitive drum 2, the charging roller 3 uniformly performs a primary charging process to a predetermined polarity and potential.
Laser light L output from the laser scanning exposure device (laser beam scanner) 4 on the charged surface and modulated in accordance with the time-series electric digital pixel signal of the target image information.
Then, the electrostatic latent image corresponding to the desired image information is formed on the peripheral surface of the drum by scanning exposure.

The latent image is developed as a toner image by the developing device 5, and the toner image reaches the transfer nip portion n between the photosensitive drum 2 and the transfer roller 6.

On the other hand, the sheet feeding cassette 7 is fed by the sheet feeding roller 7.
The recording material P inside is fed by one side with one side reference conveyance, passes through the sheet path 9 and at a predetermined timing at the transfer nip portion n.
The toner image on the side of the photosensitive drum 2 is transferred to the surface of the recording material P by applying an electric field having a polarity opposite to that of the toner from the back surface of the recording material P by the transfer roller 6.

Upon receiving the transfer of the toner image, the transfer nip portion n
The recording material P that has passed through the sheet is separated from the surface of the photosensitive drum 2 and guided to the conveyance guide 10 and enters the fixing device 11, where it passes through the fixing nip portion N to undergo the heat fixing of the toner image as described above, and the sheet is transferred. It is discharged to the outside of the device through the path 12.

The surface of the photosensitive drum 2 after the toner image is transferred onto the transfer material P is cleaned by the cleaning device 13 and is repeatedly used for image formation.

<Embodiment 4> (FIGS. 5 to 7) FIGS. 5 to 7 show other structural examples of the film heating type heating device.

In FIG. 5, the first film suspension roller 31, the second film suspension roller 32, and the ceramic heater as a heating member fixedly supported on the lower surface of the heater holder 34 as a heating member support. An endless belt-shaped heat-resistant film 35 is suspended and stretched between three members 31, 32, and 33 that are substantially parallel to each other with 33, and the heater 33 and the pressure roller 36 are pressed and pressure-contacted with the film 35 sandwiched therebetween. The heat-resistant film 35 is used as the first film suspension roller 31 or the pressure roller 36 is used as a film driving roller to be rotationally conveyed a.

In FIG. 6, an endless belt-shaped heat-resistant film 35 is suspended and stretched between the heater 33 fixedly supported on the lower surface of the heater holder 34 and the two members 31 and 33 of one film suspension roller 31. Then, the heater 33 and the pressure roller 36 are pressed against each other with the film 35 sandwiched therebetween, and the heat-resistant film 35 is rotatably conveyed a as the film suspension roller 31 or the pressure roller 36 as the film drive roller. is there.

The heat-resistant film 35 shown in FIG. 7 is not an endless belt-shaped one but a long end film wound in a roll and is used as a feeding shaft 41.
From the side through the heater 33 fixedly supported on the lower surface of the heater holder 34 to the winding shaft 42 side, and the heater 33 and the pressure roller 36 are pressed against each other with the film 35 sandwiched therebetween to wind the film 35. It is configured to travel and convey to the shaft 42 side.

In any of the devices shown in FIGS. 5 to 7, a reinforcing member 39 is provided on the upper surface of the heater holder 34 on the side opposite to the heater 33 side, the reinforcing member 39 having rigidity over its length and also having high thermal conductivity. The heater holder 34 is arranged so as to prevent pressure deflection of the heater holder 34, and both ends of the heater holder 34 in the longitudinal direction are pressed with a predetermined pressing force by pressing means such as pressurizing springs so that the lower surface of the heater 33 is pressed. Film 3
5 is pressed against the upper surface of the pressure roller 36 against the elasticity of the roller to form a pressure nip portion N with a predetermined sufficient nip width and pressure contact force, and their distribution along the length of the nip portion is substantially uniform. It has been formed.

The reinforcing member 39 of the apparatus of FIG. 6 is a substantially inverted V-shaped channel member in cross section, and the reinforcing member 39 of the apparatus of FIG. 7 is a substantially H-shaped channel member in cross section. The reinforcing member 39 has a rigidity or a rigid structure capable of substantially preventing pressure deflection of the heater holder 34 when a predetermined pressing force is applied to both longitudinal ends of the heater holder 34 and the pressure roller 36 is pressed against the pressure roller 36. Is. If necessary, the reinforcing member 39 may be provided with a radiation fin 39b like the reinforcing member 39 of FIG.

The reinforcing member 39 may be firmly adhered to the heater holder 34 serving as a heating member support with a strong heat-resistant adhesive to be integrated, or may be integrated with an appropriate stopper, or may be molded. The legs may be embedded and integrated with each other, or may be integrally molded with the heater holder 34 to be provided.

[0100]

As described above, according to the present invention, in the film heating type heating device, the heating member support has a high rigidity for preventing pressure deflection of the heating member support along its length. By disposing the reinforcing member, a high pressure is applied to both ends of the heating member support in order to sandwich the heat resistant film and form the pressure contact nip portion between the heating member and the pressure member. , Bow bending deformation with respect to the length of the heating member support can be substantially prevented, or the degree of bending deformation can be made extremely small, and therefore, with respect to both ends of the heating member support. Applying a high pressure, the pressure contact nip part has sufficient heating performance and fixing performance,
It is possible to obtain a predetermined nip width and pressure contact force necessary and sufficient to secure stable film / heated member transport performance, and to make the nip width and pressure contact force substantially evenly distributed along the length of the pressure contact nip portion. It is possible to construct a device with good performance.

Further, by making the above-mentioned reinforcing member arranged on the heating member support member have high thermal conductivity, the heat of the heating member portion of the non-sheet passing portion temperature rising portion corresponds to the heating member portion. It is quickly transmitted to the high heat conductive reinforcing member through the support portion, diffused to the reinforcing member and radiated, or heat is transferred to the reinforcing member paper passing area portion side with a thermal gradient, and Excessive temperature rise of the heating member portion, the heat resistant film portion, and the pressing member portion can be suppressed. That is, the temperature rise of the non-sheet passing portion can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a heating device (image heating and fixing device) according to a first embodiment.

FIG. 2 is a graph of temperature rise between a paper passing portion and a non-paper passing portion of a pressure roller.

FIG. 3 is a graph of temperature rise between a paper passing portion and a non-paper passing portion of a pressure roller in a device of a comparative example.

FIG. 4 is a schematic configuration diagram of an image forming apparatus according to a third embodiment.

FIG. 5 shows another example of the configuration of the film heating type heating device (No. 1).

FIG. 6 shows another example of the configuration of a film heating type heating device (No. 2).

FIG. 7 is another configuration example of the film heating type heating device (No. 3).

FIG. 8 is a schematic configuration diagram of a main part of a conventional film heating type heating device.

FIG. 9 is a plan view of a ceramic heater as a heating member with some cutouts and intermediate portions omitted.

FIG. 10 is a schematic configuration diagram of a heating device of a heating roller type.

[Explanation of symbols]

33 ceramic heater as a heating member 34 heater holder as a heating member support 39 reinforcing member of a heater holder as a heating member support 35 heat resistant film 36 pressure roller as a pressure member P recording material as a heated member

Claims (4)

[Claims] 1. A heating member and a pressure member, which are fixedly supported by a support, are heat-pressed by sandwiching a heat-resistant film between them, and the heat-resistant film and the pressure member at the pressure-contact nip portion. In a heating device which introduces a member to be heated and moves the pressure contact nip portion together with the heat resistant film to impart the heat energy of the heating member to the member to be heated through the heat resistant film, A heating device, wherein a reinforcing member for preventing pressure deflection of the heating member support is arranged over the length. 2. The heating device according to claim 1, wherein the reinforcing member of the heating member support has high thermal conductivity. 3. The heating according to claim 1, wherein the member to be heated is a recording material carrying an image and is an image heating device for heating the image of the recording material. apparatus. 4. An image heating device for forming an image on a recording material, and an image heating device for heating an image on the recording material from the image forming means side, the heating device according to claim 1 or 2. An image forming apparatus characterized by being provided as.