JPH08305189A - Heating device and image forming device - Google Patents

Abstract

PURPOSE: To exactly control the temp. of a nip part by exactly detecting the temp. of a nip part by the temp. detection member without burdening the device structural member much than required in the heating device of a film heating type. CONSTITUTION: The nip part N is provided with a first nip width part N1 having the nip width required for heating a member to be heated in the nip part length direction orthogonal to the moving direction of the heat resistance film, and a second nip width part N2 wider than the first nip width part N1, and the temp. detection member is arranged on the surface side opposite to the heat resistance film contact sliding surface side of the heating body part corresponding to the position of the second nip width part N2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film heating type heating device, that is, a nip portion is formed by sandwiching a heat-resistant film and pressing a fixed heating element and a pressure roller against each other to form a nip portion. Move the heat-resistant film while sliding it in close contact with the surface of the heating element, introduce the material to be heated between the heat-resistant film and the pressure roller in the nip part, and nip the nip part together with the heat-resistant film to heat it. The present invention relates to a heating device that applies heat from the body to a material to be heated via a heat resistant film.

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

[0003]

2. Description of the Related Art A heating device of the film heating type as described above is disclosed in JP-A-63-313182 and JP-A-1-2.
It is disclosed in Japanese Patent Laid-Open No. 63679 / Japanese Patent Laid-Open No. 2-157878 / Japanese Patent Laid-Open No. 4-44075-44083.

The apparatus is, for example, an image heating and fixing device in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, etc., that is, it is heated and meltable by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording. Corresponding to the target image information formed by a direct method or an indirect (transfer) method on the surface of the recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) using toner made of resin, etc. The unfixed toner image can be utilized as a means for performing heat fixing processing as a permanently fixed image on the surface of the recording material carrying the image.

Since such a film heating type heating device can use a low-heat-capacity heating element that quickly heats up or a thin heat-resistant film material, it saves power and shortens the wait time (quick start property). ) Is possible, the temperature rise inside the image forming apparatus such as the image forming apparatus can be reduced, and the like.

As a heating element having a low heat capacity, generally, a heat-resistant and insulating ceramic substrate and a heating resistor formed on the substrate by means of printing, firing or the like are used as a basic constitution, and the heating resistor is provided with an electric power. A so-called ceramic heater that supplies heat to generate heat is used. The heating body is configured as a horizontally long member having a length in a direction orthogonal to the moving direction of the heat resistant film, and is fixedly held by a horizontally long frame made of a heat resistant material as a holder.

The pressure roller is a heat-resistant elastic roller,
By arranging in parallel to the longitudinal direction of the heating element and applying a pressing spring force by a pressure spring to both longitudinal ends of the heating element holding frame or both ends of the pressing roller, the heating element and the pressing roller are heat-resistant. The heat-resistant film is sandwiched between the heat-resistant films and pressed against each other against the elasticity of the pressure roller to form a nip portion having a required width with the length in a direction orthogonal to the moving direction of the heat-resistant film.

The temperature of the nip portion for heat-treating the material to be heated is set to the side opposite to the heat-resistant film contact sliding surface side (heater front surface side) of the heating body in the nip portion (heater rear surface side). A temperature detecting member such as a thermistor is arranged to detect the temperature, and the temperature control system including the temperature detecting member controls the electric power supplied to the heating body based on the detected temperature information so that a predetermined operating temperature state is maintained. Is controlled by temperature control.

[0009]

[Problems to be Solved by the Invention] In the film heating type heating device as described above, the mutual pressure contact force between the heating element and the pressure roller is such that the heat-resistant film is sandwiched between the two and the direction perpendicular to the moving direction of the heat-resistant film is the longitudinal direction. It is desirable to set it to a small value as long as a nip portion having a width sufficient to heat-process the material to be heated is formed along the above. Excessive pressure contact force overloads the components of the device such as the bearing of the pressure roller and the heating element holding frame to cause problems in durability, etc., or the strength of the device components to cope with it. It is necessary to raise the design criteria for materials, materials, etc., which causes a cost increase.

[0010]. On the other hand, in order to accurately control the temperature of the nip portion that heat-processes the material to be heated as required, the temperature of the nip portion is set on the side opposite to the heating body surface side of the nip portion as described above. It is necessary to accurately detect the temperature with a temperature detecting member such as a thermistor arranged on the back side of the body, but the temperature in the nip portion depends not only on the temperature of the heating body but also on the temperature of the pressure roller. Therefore, if the width of the nip part is small, the temperature detection member cannot detect the temperature of the nip part including the temperature of the pressure roller part, and only the temperature of the heating element is detected. Since a higher temperature is detected, and as a result, the temperature of the nip portion is controlled to be low, the accuracy of nip portion temperature control deteriorates, and problems such as defective fixing occur in the image heating and fixing device.

However, in most cases, the width of the nip portion required for accurately controlling the temperature of the nip portion needs to be wider than the width of the nip portion sufficient to heat the material to be heated as required. To do. Increasing the mutual pressure contact force between the heating body and the pressure roller in order to secure such a wide nip portion imposes a large load on the device constituent members such as the bearing of the pressure roller and the heating body holding frame body. It will be.

Therefore, a first object of the present invention is to provide a heating device configuration which satisfies the requirements contradictory to the above without excessively loading the device components.

A second object of the present invention is to provide a heating device structure in which the pressure balance of the nip portion is stabilized.

[0014]

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

(1) A heat-resistant film is sandwiched and a fixed heating body and a pressure roller are brought into pressure contact with each other to form a nip portion, and the heat-resistant film is moved in the nip portion while closely sliding on the surface of the heating body. Then, the material to be heated is introduced between the heat-resistant film in the nip portion and the pressure roller, and the nip portion is nipped and conveyed together with the heat-resistant film to transfer the heat of the heating element through the heat-resistant film to the material to be heated. In the heating device applied to the first nip width portion, the nip portion has a first nip width portion having a nip width necessary for heating the material to be heated in the longitudinal direction of the nip portion orthogonal to the moving direction of the heat resistant film, Has a second nip width portion wider than the nip width portion of the heating body portion of the heating element portion corresponding to the position of the second nip width portion, which is opposite to the heat resistant film contact sliding surface side. The temperature detection member is placed on Heating and wherein the are.

(2) A heat-resistant film is sandwiched so that a first nip width portion having a nip width required for heating a material to be heated is formed, and a fixed heating element and a pressure roller are brought into pressure contact with each other. In this state, a part of the nip portion along the longitudinal direction is provided with a means for locally strengthening the pressure contact force along the longitudinal length of the nip portion so that the second nip width portion is wide. The heating device according to 1).

(3) The heating body is held by the frame body, and the metal stay presses the frame body so that the heating body and the pressure roller are pressed against each other with the heat-resistant film sandwiched therebetween, and are covered along the longitudinal direction of the nip portion. A first nip width portion having a nip width necessary for heating the heating material is formed, and both end portions in the longitudinal direction of the nip portion of the frame body,
With respect to the wall thickness formed by the difference between the surface pressed by the metal stay and the heating body holding surface, the wall thickness on one end side is formed to be thicker than the wall thickness on the other end side. The heating device according to (1) or (2), wherein the contact pressure of the nip portion on the side is locally strengthened to form a wide second nip width portion.

(4) The heating body is held by the frame body, and the heating body and the pressure roller are pressed against each other with the heat resistant film sandwiched therebetween, and the nip width required for heating the material to be heated along the longitudinal direction of the nip portion. By forming the first nip width portion having the above and the protruding portion being provided on the heating body holding surface of the frame body, the pressure contact force of the nip portion corresponding to the protruding portion is locally strengthened and widened. The heating device according to (1) or (2), characterized in that a second nip width portion is formed.

(5) The heating body is held by the frame body, and the metal stay presses the frame body so that the heating body and the pressure roller are pressed against each other with the heat-resistant film sandwiched therebetween, and are covered along the longitudinal direction of the nip portion. The first nip width portion having the nip width required for heating the heating material is formed, and the protrusion is provided on the frame pressing surface of the metal stay, so that the pressure contact force of the nip portion corresponding to the protrusion is formed. Is locally strengthened to form a wide second nip width portion (1) or (2)
The heating device according to.

(6) The heating body is held by the frame body, and the heating body and the pressure roller are pressed against each other with the heat resistant film sandwiched therebetween, and the nip width required for heating the material to be heated along the longitudinal direction of the nip portion. And a heat-resistant tape member is sandwiched between the frame body and the heating body so that the pressure contact force of the nip portion corresponding to the tape member is locally applied. The heating device according to (1) or (2), characterized in that a wide second nip width portion is formed by being strengthened.

(7) The heating body is held by the frame body, and the metal stay presses the frame body so that the heating body and the pressure roller are pressed against each other with the heat resistant film sandwiched therebetween, and are covered along the longitudinal direction of the nip portion. A first nip width portion having a nip width necessary for heating the heating material is formed, and a heat-resistant tape member is sandwiched and interposed between the metal stay and the frame body, which corresponds to the tape member. The heating device according to (1) or (2), characterized in that the pressure contact force of the nip portion is locally strengthened to form a wide second nip width portion.

(8) A heat-resistant film is sandwiched and a fixed heating body and a pressure roller are brought into pressure contact with each other to form a nip portion, and the heat-resistant film is moved while closely sliding on the heating body surface at the nip portion. Then, the material to be heated is introduced between the heat-resistant film in the nip portion and the pressure roller, and the nip portion is nipped and conveyed together with the heat-resistant film to transfer the heat of the heating element through the heat-resistant film to the material to be heated. In the heating device for applying to the heating device, the heating body is held by the frame body, the metal stay presses the frame body, and the heating body and the pressure roller are pressed against each other with the heat-resistant film sandwiched therebetween to form a nip portion. A heating device in which the body is warped in a direction in which the surface pressed by the metal stay in the non-pressurized state is convex toward the pressure roller.

(9) The material to be heated is a recording material carrying an image, and the apparatus is an image heating device for heating the image of the recording material (1) to (8). The heating device according to any one of 1.

(10) Any one of (1) to (8) as an image forming means 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. An image forming apparatus comprising the heating device according to any one of the above.

[0025]

[Action]

1) That is, the form of the nip part formed by sandwiching the heat resistant film and pressing the fixed heating body and the pressure roller against each other is changed in the longitudinal direction of the nip part orthogonal to the moving direction of the heat resistant film. A first nip width portion having a nip width necessary for heating the material, and a second nip width portion wider than the first nip width portion,
It is necessary to form a nip part of such a shape by arranging a temperature detecting member on the side of the heating element part that corresponds to the position of the nip width part of In practice, the mutual pressure contact force between the heating element and the pressure roller may be set to be small enough to form a nip portion having a required width for heating the material to be heated. By placing the temperature detection member on the side opposite to the heat-resistant film contact sliding surface side of the heating body portion corresponding to the position of the second wide nip width portion without applying a load more than necessary, The temperature of the nip portion can be accurately detected by the temperature detecting member, and the temperature of the nip portion can be accurately controlled.

The nip width of the second nip width portion is preferably 1.1 times or more the minimum nip width of the first nip width portion.

2) The second nip width portion, which is wider than the first nip width portion having the nip width required for heating the material to be heated, and which is used to position the temperature detecting member, is provided with a heating body and a pressure member. By providing means for locally strengthening the pressure contact force along the length of the nip portion with the roller, the overall pressure contact force applied to the apparatus can be formed and provided without substantially increasing it more than necessary. Specifically, the following means configurations a) to e) can be adopted.

A) A heating body is held by a frame body, and the frame body is pressed by a metal stay, and the heating body and the pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween, and are covered along the longitudinal direction of the nip portion. A first nip width portion having a nip width required for heating the heating material is formed, and is formed by a difference between a surface pressed by the metal stay and a heating body holding surface at both ends of the frame body in the longitudinal direction of the nip portion. Regarding the wall thickness, by forming the wall thickness on one end side to be thicker than the wall thickness on the other end side, the pressure contact force of the nip portion on the one end side is locally strengthened to increase the width of the second wide portion. To form the nip width part of the.

B) A heating body is held by a frame body, and the heating body and the pressure roller are pressed against each other with a heat resistant film sandwiched therebetween, and a nip width required for heating the material to be heated along the longitudinal direction of the nip portion. Forming a first nip width portion having
Protrusions are provided on the heating body holding surface of the frame body, and the pressure contact force of the nip portion corresponding to the protrusions is locally strengthened to form a wide second nip width portion.

C) The heating body is held by the frame body, and the frame body is pressed by the metal stay to press the heating body and the pressure roller together with the heat-resistant film sandwiched therebetween to press the heating body and the pressure roller together along the longitudinal direction of the nip portion. A first nip width portion having a nip width necessary for heating the heating material is formed, and a protrusion is provided on the frame body pressing surface of the metal stay so that the pressure contact force of the nip portion corresponding to the protrusion is locally applied. To form a wide second nip width portion.

D) The heating body is held by a frame body, and the heating body and the pressure roller are pressed against each other with a heat resistant film sandwiched therebetween, and the nip width required for heating the material to be heated along the longitudinal direction of the nip portion. Forming a first nip width portion having
By sandwiching and interposing a heat-resistant tape member between the frame body and the heating body, the pressure contact force of the nip portion corresponding to the tape member is locally strengthened to form a wide second nip width portion. .

E) The heating body is held on the frame body, and the frame body is pressed by the metal stay to sandwich the heat-resistant film with the heating body and the pressure roller so that they are pressed against each other, and the heating body and the pressure roller are pressed along the longitudinal direction of the nip portion. By forming a first nip width portion having a nip width necessary for heating the heating material and interposing a heat-resistant tape member between the metal stay and the frame body, the first nip width portion can be accommodated. The pressure contact force of the nip portion is locally strengthened to form a wide second nip width portion.

3) The heating body is held by the frame body, and the frame body is pressed by a metal stay, and the heating body and the pressure roller are sandwiched by the heat resistant film and pressed against each other to form a nip portion. In the non-pressurized state, the surface pressed by the metal stay is warped in the direction in which it is convex toward the pressure roller, and the frame body is pressed by the metal stay against the rigidity of the frame body. When the warp is eliminated and the frame and the metal stay are brought into close contact with each other without any gap, the heating body and the pressure roller are sandwiched by the heat-resistant film and pressed against each other to form the nip portion, thereby forming the pressure balance of the nip portion. Is stable, and in the image heating and fixing device, defective fixing due to instability of the pressure balance and wrinkles of paper (recording material) are prevented.

[0034]

【Example】

<Example 1> (Figs. 1 to 5) (1) Overall configuration of heating device (Figs. 1 and 2) Fig. 1 is a side view showing a schematic configuration of a heating device 11 of the present embodiment, and Fig. 2 is an exploded view. It is a perspective view. The heating device 11 of this example is disclosed in JP-A-4-44075-44083 and 4-204.
This is a so-called tensionless type device disclosed in Japanese Patent Laid-Open No. 980-204984, and is used as an image heating fixing device in an image forming apparatus such as a copying machine or an LBP.

In FIGS. 1 and 2, 1 is a heating body (hereinafter referred to as a heater), 2 is a frame body (hereinafter referred to as a heater holder) holding the heater 1, and 3 is a cylindrical heat-resistant film ( Hereinafter, referred to as a fixing film), 4 is a pressure roller, and 5 is a metal stay.

The heater 1 according to the present embodiment is a horizontally long thin plate-shaped ceramic substrate (for example, alumina, aluminum nitride, etc., having a thickness of 1 mm, a width of 10 mm, and a length of 240 mm, which is a heat-resistant and electrically insulating good heat conductor. ) And a heating resistor formed on the surface of the substrate along the length of the substrate (for example, Ag / P).
b, was applied to a strip-like pattern of RuO _2, Ta ₂ N width 1 to 3 mm · thickness of several tens by screen printing or the like electric resistance material such as [mu] m, baked those formed) to the basic structure It is a ceramic heater, and heat is rapidly generated and temperature rises by supplying power to the heating resistor, and the temperature is controlled and controlled by a temperature control system to a predetermined fixing temperature. The heater 1 is fitted into a groove formed along the length of the lower surface of the heater holder 2 along the length thereof, and is adhered and held by a heat resistant adhesive. The details of the ceramic heater itself are known in the above-mentioned publications and the like, and therefore the description thereof is omitted.

The heater holder 2 is a horizontally long gutter-shaped member having a substantially semicircular cross section, and also serves as a rotation guide member for the cylindrical film 3 to be fitted onto the heater holder 2. For example, it is a heat resistant member made of a thermosetting resin. . Reference numeral 2d designates arc ribs for guiding the inner surface of the film, which are provided on the outer surfaces of the front and rear arc walls of the heater holder 2 at substantially equal intervals along the length of the outer surface. Two
Reference numeral e denotes two reinforcing convex ribs which are provided in parallel on the inner bottom surface 2a of the heater holder 2 along the length of the bottom surface thereof at intervals.

The metal stay 5 is a laterally long rigid member having a substantially inverted U-shaped cross section and is fitted inside the heater holder 2. The lower U-shaped front and rear lower sides 5a, 5a of the heater holder 2 are the same. It contacts the inner bottom surface 2a.

The cylindrical fixing film 3 is, for example, a polyimide (PI) film whose surface is coated with a fluororesin such as PTFE having good toner releasability. In this cylindrical fixing film 3, a metal stay 5 is fitted inside a heater holder 2 that holds a heater 1 on the lower surface, and is loosely fitted around the outer circumference of the heater holder 2 and the metal stay 5. This heater 1, heater holder 2, metal stay 5,
The assembly of the cylindrical fixing film 3 is hereinafter referred to as a heater unit.

The pressure roller 4 includes a core metal 4b and the core metal 4b.
An elastic roller composed of a heat-resistant rubber roller portion 4a made of silicon rubber or the like and provided concentrically with the above. In the apparatus of this example, the pressure roller 4 is disposed between the apparatus side plates (not shown) with the shaft portions at both ends rotatably supporting the bearings.

The above-mentioned heater units 1, 2, 5, and 3 are placed on the upper side of the pressure roller 4 in parallel with the pressure roller 4 with the heater side facing downward. By compressing the pressure springs 6 and 6 between the spring receiving lugs 5c and 5c and the stationary spring receivers 9 and 9 on the device side plate side, both ends of the metal stay 5 in the direction of the pressure roller respectively. A predetermined pressing force F (spring load) is applied.

Pressing force F applied to both ends of the metal stay 5.
As a result, the inner bottom surface 2a (metal stay contact surface) of the heater holder 2 has front and rear lower sides 5 of the inverted U-shape of the metal stay 5.
The pressure is applied between the heater 1 and the pressure roller 4 which are pressed by a.5a and face each other with the fixing film 3 interposed therebetween, and the rubber roller portion 4a of the pressure roller 4 is pressed against elasticity. The fixing film 3 is sandwiched between the heater 1 and the pressure roller 4 to form a pressure contact nip portion N (hereinafter, referred to as a fixing nip portion) having a predetermined width. In this way, by incorporating the metal stay 5 in the heater holder 2 and applying pressure to the metal stay 5, the unit on the heater holder side is reinforced. In order to evenly transfer the load applied to the metal stay 5 to the nip portion, the metal stay contact surface 2a of the heater holder 2 and
It is desirable that the contact surfaces of the heaters of the metal stays be straight so that they match with each other without gaps.

A gear 7 is attached to the shaft end on one side of the pressure roller 4.
(FIG. 2) is provided, and the driving force is transmitted from a drive motor (not shown) to the gear 7, and the pressure roller 4 is rotationally driven counterclockwise at a predetermined peripheral speed. The rotational force acts on the film 3 due to the frictional force in the nip portion between the roller 4 and the outer surface of the film 3 due to the rotational driving of the pressure roller 4,
The film 3 is rotationally driven around the outside of the heater holder 2 and the metal stay 5 in the clockwise direction of the arrow while sliding in contact with the lower surface of the heater 1. By providing the arc ribs 2d for guiding the inner surface of the film on the outer surfaces of the front and rear arc walls of the heater holder 2, the sliding resistance between the film inner surface and the outer surfaces of the front and rear arc walls of the heater holder 2 is increased. Becomes smaller. Further, in order to reduce the sliding resistance between the inner surface of the film 3 and the lower surface of the heater with which the film 3 contacts and slides at the nip portion N, it is preferable to interpose a lubricant such as heat resistant grease between them.

The heater 1 rapidly rises in heat by being supplied with electric power from an energization system (not shown), and heats the fixing nip portion N.
Is heated. The temperature of the nip portion N is the fixing film contact sliding surface side (heater surface side) of the heater 1 of the nip portion N.
A thermistor 8 (FIG. 2) as a temperature detecting member is arranged on the side opposite to the surface (the back side of the heater) for detection, and based on the detected temperature information, a temperature control system (not shown) including the thermistor 8 controls the heater 1 Is controlled to control the temperature so that a predetermined fixing temperature state is maintained. In the case of the apparatus of this embodiment, the recording material P is introduced into the fixing nip portion N on the basis of one-sided conveyance. In FIG. 2, O is the one-sided conveyance reference line. The thermistor 8 is arranged on the back surface of the heater corresponding to the vicinity of the end of the fixing nip portion on the one-sided conveyance reference line O side. More precisely, it is arranged on the back surface of the heater, which is separated from the position of the one-sided conveyance reference line O by about 10 mm.

Then, the film 3 is rotated by the rotation of the pressure roller 4, and the fixing nip portion N is heated to a predetermined fixing temperature by the energization of the heater 4 and the temperature is adjusted to a predetermined fixing temperature. A recording material P as a material to be heated having an unfixed toner image T between the N rotary pressing roller 4 and the rotating film 3 is introduced with the toner image bearing surface side thereof being the film 3 side. The heat of the heater 4 is applied to the sheet through the film 3 by being nipped and conveyed together with the fixing nip portion N, and the toner image T is heated and fixed on the sheet surface. The sheet P passing through the fixing nip portion N is separated from the film 3 surface and conveyed.

In the apparatus 11 of the present embodiment, when the film 3 is driven to rotate, only the fixing nip portion N and the film portion in the contact portion area between the outer surface portion of the heater holder and the film upstream of the nip portion N in the film rotation direction. The tension acts on the film, and the tension does not act on most of the remaining film. Therefore, when the film 3 is rotationally driven, the lateral displacement force along the length of the heater holder 2 is small, and the lateral displacement regulation means of the film 3 or the lateral displacement control means can be simplified. For example, the deviation control means of the film 3 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 size and cost of the apparatus. (2) Concerning the Form of the Fixing Nip Part N (FIGS. 3 to 5) As described above, the nip width of the fixing nip part N is from the viewpoint that an unnecessary load is not applied to the component members of the apparatus.
It is preferable to set the temperature of the recording material as a material to be heated close to the minimum necessary for favorably performing the image heat fixing, while the temperature of the nip portion N is a temperature detecting member arranged on the back surface of the heater 1. In order to increase the temperature control accuracy of the nip portion N by accurately detecting the temperature with the thermistor 8 as the fixing nip portion N,
The nip width of is preferably wider than the above nip width.

In the apparatus of this embodiment, in order to make the above-mentioned contradictory matters compatible with each other, as shown in FIGS. 3 and 4, in particular, as shown in the plan view model of the nip portion of FIG. The first nip width portion N1 having the nip width W1 required for image heating and fixing of the recording material is formed along the longitudinal direction of the nip portion by the pressure F · F at both ends of the nip portion of the heater holder 2 One end side with respect to the wall thickness of the two ends in the direction, which is defined by the difference between the surface 2a pressed by the metal stay 5 and the heater holding surface 2b (the end side on the one-sided transport reference side)
Is formed thicker than the thickness d2 on the other end side (the end side opposite to the one-side transport reference side), the pressure contact force of the nip portion on the one end side is locally applied. The second nip width portion N2 having a wide width W2 is formed by strengthening it.

In this embodiment, the nip width W1 of the first nip width portion N1 is set to 3.5 mm, and the nip width W2 of the second nip width portion N2 is set to 3.85 mm or more. Then, the thermistor 8 as a temperature detecting member is arranged on the back surface of the heater corresponding to the position of the wide second nip width portion N2.

The mutual relationship between the heater 1 and the pressure roller 4 necessary for forming the nip portion N having the first nip width portion N1 and the second nip width portion N2 wider than the first nip width portion N1. The pressure contact force is actually the first nip width portion N1 having the nip width W1 required for image heating fixing of the recording material.
By setting the thermistor 8 on the back surface of the heater corresponding to the position of the wide second nip width portion N2, it is possible to make the setting as small as necessary to form the above. , The temperature of the nip portion N can be accurately detected by the thermistor 8, and the nip portion N can be detected.
It is possible to accurately control the temperature of.

FIG. 3 is a partially cutaway exploded front view of the heater 1, the heater holder 2, and the metal stay 5 in the unloaded state.
FIG. 4 (a) shows the heater units 1, 2, 5 in the pressurized state.
3 is a partially cutaway front view of the pressure roller 4, (b) is a right side view of the pressure roller, (c) is a plan view of the nip portion N,
(D) And (e) is a figure which shows the bending amount e1 * e2 of the pressure roller rubber part 2a in the 1st nip width part N1 and the 2nd nip width part N2 wider than it, respectively.

The heater holder 2 has two important aspects regarding pressurization. One is a metal stay surface 2a (the inner bottom surface of the heater holder) against which the metal stay 5 presses the heater holder, 1
One is the heater surface 2b that holds the heater.

The nip width in the longitudinal direction of the nip portion N is determined by the shape of the heater surface 2b which is incorporated in the fixing device and is under a load. If the shape of the heater surface 2b under this load is such that the metal stay surface 2a follows the metal stay 5, the meat shown by the hatched portion in FIG. 3 which is the difference between the heater surface 2b of the heater holder and the metal stay surface 2a. It can be determined by the thickness shape. Conventionally, this thick-walled shape has a clean arc-shaped crown shape that is convex downward in consideration of the bending of the pressure roller and the bending of the upper unit including the metal stay and the heater holder.

In the image forming apparatus (not shown) in which the fixing device of the present embodiment is one of the elements, the one-sided conveyance reference for determining the attitude of the recording material P by bringing the recording material P close to the reference surface installed on the gear 7 side. Therefore, the thermistor 8 is about 10 m from the one-sided conveyance reference line O on the gear 7 side so that it can correspond to a recording material having a short width.
It is in the m position. Therefore, in the present embodiment, the thickness d1 of the heater holder on the thermistor side is compared with the thickness d2 on the opposite side so that the nip width is increased by the end portion on the thermistor 8 side.
0.01 to 0.1 like the shaded portion in FIGS. 3 and 4A.
The thickness is 0 mm.

In the heater holder 2 of this embodiment, the lower part of the thermistor digs into the pressure roller 4 side as seen from the shaded portion of FIG. 4 (a) when the heater surface under load is compared with the conventional heater holder. Therefore, as shown in (c), the thermistor portion in the longitudinal direction of the nip portion N has a larger nip width than other portions. This (c) is the nip width when a spring force (6 to 8 Kgf) is applied.

FIG. 5 shows one end side (one-side conveyance) with respect to the wall thicknesses d1 and d2 formed by the difference between the surface 2a pressed by the metal stay 5 and the heater holding surface 2b at both ends in the longitudinal direction of the nip portion of the heater holder 2. The wall thickness d1 on the reference side end side and the wall thickness d2 on the other end side (the end side on the opposite side to the one-side transport reference side) are the same, and are formed in this case. The nip portion N has a width W1 over the entire longitudinal length as shown in (c).
It will be almost straight form. That is, the heater holding surface 2b of the heater holder 2 has a neat arcuate crown shape so that the bending of the pressure roller 4 and the bending of the heater holder itself are offset so that the lower side is convex toward the pressure roller. . As a result, the pressure in the nip is evenly applied over the length. The nip width formed by the collapse of the pressure roller is also substantially straight in the longitudinal direction as shown in FIG.

The heater holder 2 shown in FIGS.
The warpage and flexure of the metal stay 5 and the metal stay 5 under no load or under pressure are exaggerated for clarity. The same applies to the drawings in the following embodiments.

<Embodiment 2> (FIGS. 6 to 8) In this embodiment, the heater 1 and the pressure roller 4 are pressed against each other with the fixing film 3 sandwiched therebetween, and an image of the recording material is formed along the longitudinal direction of the nip portion. A first nip width portion N1 having a nip width necessary for heat fixing is formed, a protrusion 2c is provided on the heater holding surface 2b of the heater holder 2, and the pressure contact force of the nip portion corresponding to the protrusion 2c is locally applied. To form a wide second nip width portion N2, and a thermistor 8 as a temperature detecting member is arranged at the heater back surface portion corresponding to the position of the wide second nip width portion N2.

The fixing device of the present embodiment is of a type in which the recording material P is introduced into the device on the basis of the center conveyance, and therefore the fixing device shown in FIG.
As shown in (a) of FIG. 3, a protrusion 2 c (protrusion thickness, 0.01 mm) is formed at a substantially central portion of the heater holding surface 2 b of the heater holder 2 in the longitudinal direction.
.About.0.1 mm) is provided to form a wide second nip width portion N2 at a substantially central portion in the longitudinal direction of the nip portion N as shown in (b), and the position of the wide second nip width portion N2 is formed. The thermistor 8 is arranged on the back surface of the heater corresponding to.

The mutual relationship between the heater 1 and the pressure roller 4 necessary to form the nip portion N having the first nip width portion N1 and the second nip width portion N2 wider than the first nip width portion N1. The pressure contact force is actually the first nip width portion N1 having the nip width W1 required for image heating fixing of the recording material.
By setting the thermistor 8 on the back surface of the heater corresponding to the position of the wide second nip width portion N2, it is possible to make the setting as small as necessary to form the above. , The temperature of the nip portion N can be accurately detected by the thermistor 8, and the nip portion N can be detected.
It is possible to accurately control the temperature of.

Further, as shown in FIG. 7, even if the thermistor 8 is not located at the center in the longitudinal direction of the heater 1, if the above-mentioned protrusion 2c is provided on the heater holding surface 2b of the heater holder 2 at the position where the thermistor 8 is present, the above-mentioned projection 2c is provided. It goes without saying that such effects can be obtained.

Further, the heater holding surface 2b of the heater holder 2
Even if the protrusion 5b is provided at the thermistor-corresponding position portion of the metal stay 5 as shown in FIG. 8 without providing the protrusion, the same effect can be obtained.

Further, even in the fixing device having a structure in which the heater holder 2 is directly pressed without the metal stay 5, the same effect can be obtained by providing the heater holder portion at the position corresponding to the thermistor.

<Embodiment 3> (FIGS. 9 and 10) In this embodiment, the heater 1 and the pressure roller 4 are pressed against each other with the fixing film 3 sandwiched therebetween to form an image of the recording material along the longitudinal direction of the nip portion. The first nip width portion N1 having a nip width required for heat fixing is formed, and the heat-resistant tape member 10 is sandwiched between the heater holder 2 and the heater 1 so as to intervene to correspond to the tape member 10. The pressure contact force of the nip portion is locally strengthened to form a wide second nip width portion, and the thermistor 8 as a temperature detecting member is provided on the heater back surface portion corresponding to the position of the wide second nip width portion N2.
Was placed.

The fixing device of the present embodiment is of a type in which the recording material P is introduced into the device on the basis of the center conveyance, and therefore, FIG.
As described above, at a substantially central portion in the longitudinal direction of the heater holding surface 2b of the heater holder 2, a heat-resistant thickness of 0.03 to 0.1 mm such as a polyimide tape or a PTFE tape is provided between the heater holding surface 2b and the heater 1. The second nip width portion N2 is formed by sandwiching the tape member 10 of
The thermistor 8 is arranged on the heater rear surface portion corresponding to the position of the wide second nip width portion N2.

The heater surface 2b of the heater holder 2 of this embodiment.
Irrespective of the position of the thermistor 8, has a beautiful arc-shaped crown shape.

As a result, the same heater holder can be used for fixing devices having different thermistor 8 positions, and the heater holder can be used.

Further, as shown in FIG. 10, the heat resistant tape 10
The same effect can be obtained by sandwiching between the heater holder 2 and the metal stay 5.

Also in the case of this embodiment, the same operational effects as those of the first and second embodiments are obtained.

<Embodiment 4> (FIGS. 11 to 14) In this embodiment, the heater 1 is held by the heater holder 2, and the heater holder is pressed by the metal stay 5 to fix the heater 1 and the pressure roller 4 to the fixing film. The nip portion N is formed by sandwiching 3 and pressing them, and the surface 2a pressed by the metal stay 5 in the non-pressurized state of the heater holder 2 is warped in the direction of being convex toward the pressure roller side. The heater holder 2 is pressed by the metal stay 5 against the rigidity of the heater holder 2 to eliminate the warp and the heater holder 2 and the metal stay 5 are brought into close contact with each other without a gap, and the heater 1 and the pressure roller 4 are fixed. By forming the nip portion N by sandwiching the film 3 and pressing the film 3, it is possible to stabilize the pressure balance of the nip portion N and to prevent fixing failure and paper (recording material) wrinkles due to instability of the pressure balance. It has been prevented.

That is, the metal stay surface 2a of the heater holder 2 of the present embodiment, which is in contact with the metal stay 5, has a pressure roller side of about 0.3 mm as shown in FIG. Is warped.

Therefore, the metal stay 5 is attached to the heater holder 2.
When assembled, the heater holder contact surface 5 of the metal stay 5
Since a is straight, the ends contact each other, and there is a gap of about 0.3 mm at the center. When pressure is applied to this, the rigidity of the heater holder 2 is small.
As with the metal stay 5, there is no gap.

Originally, the metal stay surface 2a of the heater holder 2
Is desirable to be straight, but it is extremely difficult to form this surface into a straight shape, and when it is attempted to form a straight surface, the surface will have an S-shape or a W shape as shown in FIGS.
It tends to be shaped. In such a case, as shown in FIG. 13, when assembling the metal stay 5 to the heater holder 2, an inclination may occur, or a gap between the metal stay 5 and the heater holder 2 may remain, and the pressure below the thermistor that is originally required may be reduced. It may not be possible to secure the pressure, or pressure loss may occur in a part of the longitudinal direction.

Therefore, in this embodiment, the metal holder surface 2a of the heater holder 2 is previously formed at the time of forming the heater holder 2.
By intentionally deflecting by 0.3 mm, it was possible to prevent the S-shaped and W-shaped shapes of FIGS. 12A and 12B from occurring.

If the metal stay surface 2a is deflected in the direction opposite to that of this embodiment as shown in FIG. 14A, there is a possibility that the metal stay surface 2a may be inclined to either side as shown in FIG. 14B. There is a possibility that even if pressure is applied as it is, a gap is left open at either end. In the fixing unit in such a state, not only the end portion is not pressed but also the pressure balance is unstable, so that the fixing unit may vibrate up and down, which causes wrinkling of the paper.

If the warp direction is such that it is convex toward the pressure roller side as in this embodiment, it will be stable without tilting since it hits both ends of the metal stay 5 heater holder 2 during assembly. a)). Even if pressure is applied as it is, the metal stay 5 can maintain a stable posture and can follow the metal stay 5 without any gap between the metal stay 5 and the heater holder 2 as shown in FIG.

<Embodiment 5> (FIG. 15) FIGS. 15 (a) to 15 (c) show another example of the configuration of a film heating type heating device.

In the case of (a), the endless belt-shaped film 3 is suspended and stretched between the heater 1 held by the heater holder 2, the driving roller 41 and the driven roller (tension roller) 42. The drive roller 41 drives the film 3 to rotate. Heater holder 2
The nip portion N is formed with the film 3 sandwiched between the heater 1 and the pressure roller 4 by pressing with a pressure means with or without the metal stay 5.

In the case of (b), the endless belt-shaped film 3 is suspended and stretched between the two members, the heater 1 held by the heater holder 2 and the driving roller 41, and the driving roller 41 is rotationally driven. Is. A nip portion N is formed by sandwiching the film 3 between the heater 1 and the pressure roller 4 by pressing the heater holder 2 with or without the metal stay 5 by the pressing means.

In the case of (c), the film 3 is not an endless belt-shaped one, but a long end film wound in a roll is used.
The heater 1 held by the heater holder 2 is configured to run at a predetermined speed toward the winding shaft 45 via the lower surface of the heater 1. A nip portion N is formed by sandwiching the film 3 between the heater 1 and the pressure roller 4 by pressing the heater holder 2 with or without the metal stay 5 by the pressing means.

It is needless to say that the present invention is also applied to the film heating type heating device of such a form to obtain the same actions and effects as those of the first to fourth embodiments.

In the present invention, the heating element 1 is not limited to the ceramic heater as in the embodiment.

The heater holder 2 side may be fixedly arranged, and the pressure roller 4 side may sandwich the film 3 by a pressure means and press it against the heater 1 to form a required nip portion N.

The film heating type heating devices of Examples 1 to 5 are not only image heating and fixing devices, but also, for example, heating a recording material carrying an image to modify the surface properties (such as gloss). It can be widely used as a heating device for materials to be heated, such as a heating device, a hypothetical fixing device, a device for heating, drying, and laminating a sheet-shaped material while conveying it.

Sixth Embodiment (FIG. 16) FIG. 16 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of this example is a copying machine or printer using a transfer type electrophotographic process.

Reference numeral 31 is a rotary drum type electrophotographic photosensitive member, which is rotationally driven in the clockwise direction of the arrow at a predetermined process speed (peripheral speed).

Reference numeral 32 is a contact charging roller as a photosensitive member charging means, to which a predetermined charging bias is applied, and the surface of the rotating photosensitive member 31 is uniformly charged to a predetermined polarity and potential by the charging roller 32. It

Exposure of the target image information 33 is performed on the charged surface of the rotary photoconductor 31 by an image information exposure means (not shown) such as a slit image forming exposure means for a document image and a laser beam scanning exposure means. As a result, an electrostatic latent image corresponding to the target image information is formed on the surface of the rotating photoconductor 31.

The latent image is developed as a toner image by the toner developing device 34.

The toner image is transferred from a paper feed unit (not shown) to a transfer unit, which is a pressure contact nip between the rotating photoconductor 31 and the transfer roller 35 to which a predetermined transfer bias is applied. The image is transferred onto the transfer material P as the recording material conveyed at the timing.

The transfer material P which has passed the transfer portion and has received the transfer of the toner image is separated from the surface of the rotary photosensitive member 31.
The unheated toner image is heated and fixed by being conveyed to the film heating type heating device 11 as the image heating and fixing device of FIG. 1 and output as a copy or a print.

After the transfer of the toner image onto the transfer material P, the surface of the rotary photosensitive member 31 is cleaned by the cleaning device 36 to remove residual adhering substances such as transfer residual toner, and is repeatedly used for image formation.

[0092]

As described above, according to the present invention, in the film heating type heating device, the nip width of the nip portion is
From the viewpoint of not overloading the component parts of the device, it is preferable to set the temperature close to the minimum necessary to perform the heat treatment of the material to be heated well, on the other hand. In order to accurately detect temperature with the temperature detection member provided on the back of the heating element and increase the temperature control accuracy of the nip part,
It is preferable to set the nip width of the nip portion wider than the above-mentioned nip width. By satisfying the contradictory matters, it is possible to keep the temperature of the nip portion by the temperature detection member without applying an unnecessarily large load to the device constituent members. It is possible to accurately detect the temperature of the nip portion and control the temperature of the nip portion accurately.

It is possible to stabilize the pressure balance of the nip portion and prevent the fixing failure and the wrinkle of paper (recording material) due to the instability of the pressure balance in the image heating and fixing device. did it.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a heating device according to a first embodiment.

FIG. 2 is an exploded perspective view

FIG. 3 is an exploded front view of the heater, the heater holder, and the metal stay in which there is no load

4A is a partially cutaway front view of a heater unit and a pressure roller in a pressure state, FIG. 4B is a right side view of the pressure roller, and FIG. 4C is a plan view of a nip portion. (D) and (e) are figures which show the bending amount of the pressure roller rubber part in a 1st nip width part and a 2nd nip width part wider than it, respectively.

FIG. 5A is a partially cutaway front view of the heater unit and the pressure roller in a pressure state in the case where the both ends of the heater holder have the same thickness, and FIG. 5B is the right side of the pressure roller. Plan view, (c) is a plane model view of the nip part

FIG. 6A is an exploded front view of a heater, a heater holder, and a metal stay in a partially cutaway state of the apparatus according to the second embodiment, and FIG. 6B is a plan model view of a nip portion.

FIG. 7 is an exploded front view of a heater, a heater holder, and a metal stay in a partially cutaway state in a no-load state in another apparatus configuration form.

FIG. 8 is an exploded front view of a heater, a heater holder, and a metal stay in a partially cutaway state in a no-load state in still another device configuration form.

FIG. 9 is an exploded front view of a heater, a heater holder, and a metal stay in a partially cutaway state of the apparatus according to the third embodiment in an unloaded state.

FIG. 10 is an exploded front view of the heater, the heater holder, and the metal stay in a partially cutaway state in a no-load state in another configuration of the apparatus.

11A is an exploded front view of a heater, a heater holder, and a metal stay in a partially cutaway state of the apparatus according to the fourth embodiment in a no-load state, and FIG. 11B is a heater unit and a pressure roller in a pressurized state. Front view with partial cutout

12A and 12B are explanatory views of defective heater holders.

FIG. 13 is an explanatory diagram of pressurization failure due to a defective heater holder.

14 (a) and 14 (b) are explanatory views of defective heater holders and defective pressurization resulting therefrom.

15 (a) to 15 (c) are other examples of the configuration of a film heating type heating device.

FIG. 16 is a schematic configuration diagram of an example of an image forming apparatus.

[Explanation of symbols]

11 Film heating type heating device (image heating and fixing device) 1 Heating body (ceramic heater) 2 Heating body holding frame body (heater holder) 3 Heat resistant film (fixing film) 4 Pressure roller 5 Metal stay 6 Pressure spring 7 Drive Gear 8 Temperature detection member (thermistor) N Nip part (fixing nip part) N1 First nip width part N2 Second nip width part

Claims (10)

[Claims] 1. A nip portion is formed by sandwiching a heat-resistant film and bringing a fixed heating body and a pressure roller into pressure contact with each other.
In the nip portion, the heat resistant film is moved while closely sliding on the surface of the heating body, and a material to be heated is introduced between the heat resistant film in the nip portion and the pressure roller to sandwich the nip portion together with the heat resistant film. In a heating device which conveys and applies heat of a heating body to a material to be heated through a heat resistant film, the nip portion is for heating a material to be heated with respect to a longitudinal direction of the nip portion orthogonal to the moving direction of the heat resistant film. A first nip width portion having a required nip width, and a second nip width portion wider than the first nip width portion,
A heating device in which a temperature detecting member is arranged on a surface side of the heating element portion corresponding to the position of the second nip width portion, which is opposite to the heat resistant film contact sliding surface side. 2. A fixed heating element and a pressure roller are brought into pressure contact with each other by sandwiching a heat resistant film so as to form a first nip width portion having a nip width necessary for heating a material to be heated. In the state, there is provided a means for locally strengthening the pressure contact force along the longitudinal direction of the nip portion so that the portion along the longitudinal direction of the nip portion becomes the wide second nip width portion. The heating device according to 1. 3. A heating body is held by a frame body, a metal stay presses the frame body, and the heating body and a pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween to be heated along the longitudinal direction of the nip portion. A first nip width portion having a nip width required for heating the material is formed, and a wall thickness of a difference between a surface pressed by the metal stay and a heating body holding surface at both ends of the frame body in the longitudinal direction of the nip portion. With regard to the above, since the thickness on one end side is formed thicker than the thickness on the other end side, the pressure contact force of the nip portion on the one end side is locally strengthened and wide The heating device according to claim 1 or 2, wherein two nip width portions are formed. 4. The heating body is held by a frame body, and the heating body and the pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween so that the nip width required for heating the material to be heated is set along the longitudinal direction of the nip portion. Since the first nip width portion of the nip portion is formed and the protruding portion is provided on the heating body holding surface of the frame body, the pressure contact force of the nip portion corresponding to the protruding portion is locally strengthened and widened. The heating device according to claim 1 or 2, wherein two nip width portions are formed. 5. A heating body is held by a frame body, a metal stay presses the frame body, and the heating body and a pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween to be heated along the longitudinal direction of the nip portion. Since the first nip width portion having a nip width necessary for heating the material is formed and the protrusion portion is provided on the frame pressing surface of the metal stay, the pressure contact force of the nip portion corresponding to the protrusion portion is increased. 3. A second nip width portion that is locally strengthened and has a wide width is formed.
The heating device according to. 6. The heating body is held by a frame body, and the heating body and the pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween, so that a nip width required for heating the material to be heated is provided along the longitudinal direction of the nip portion. Since the first nip width portion having the heat-resistant tape member is interposed between the frame body and the heating body, the pressure contact force of the nip portion corresponding to the tape member is locally applied. The heating device according to claim 1 or 2, characterized in that a strengthened and wide second nip width portion is formed. 7. A heating body is held by a frame body, a metal stay presses the frame body, and the heating body and a pressure roller are pressed against each other with a heat-resistant film sandwiched therebetween to be heated along the longitudinal direction of the nip portion. A first nip width portion having a nip width necessary for heating the material is formed, and a heat-resistant tape member is sandwiched and interposed between the metal stay and the frame body, thereby corresponding to the tape member. The heating device according to claim 1 or 2, wherein the pressure contact force of the nip portion is locally strengthened to form a wide second nip width portion. 8. A nip portion is formed by sandwiching a heat-resistant film and bringing a fixed heating body and a pressure roller into pressure contact with each other.
In the nip part, the heat resistant film is moved while closely sliding on the surface of the heating body, and the material to be heated is introduced between the heat resistant film in the nip part and the pressure roller to sandwich the nip part together with the heat resistant film. In a heating device that conveys heat of a heating body to a material to be heated through a heat-resistant film, the heating body is held by a frame body, and a metal stay presses the frame body to form a heating body and a pressure roller. Is press-contacted with a heat-resistant film sandwiched therebetween to form a nip portion, and the frame body is warped in a direction in which a surface pressed by the metal stay in a non-pressurized state is convex toward the pressure roller side. Heating device. 9. The image heating apparatus according to claim 1, wherein the heated material is a recording material carrying an image, and the apparatus is an image heating apparatus for heating the image of the recording material. The heating device according to any one of claims. 10. An image forming 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 device side, as claimed in any one of claims 1 to 8. An image forming apparatus having the heating device according to the first aspect.