JPH10260599A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent temperature fall at the end of a heating body and also to prevent the damage of a heater by making an energizing heating element oppositely press-contact with a pressure member all over the area in a longitudinal direction and making the calorific value of the heating body larger at the end than at a central part. SOLUTION: The length in the longitudinal direction of a pressure roller 9 is longer than that of the heating element 3, so that the heating element 3 does not project to the outside from the end of the roller 9. Namely, the heating element 3 of the heater 1 is opposed to the roller 9 in all the area. The width of the heating element 3 is narrowed at the end. By energizing the electrode for energizing 11 of the heater 1, the heating element 3 generates heat, and the calorific value of each part of the heating element 3 is proportioned to RI<2> at such a time. Therefore, high resistance parts B at both ends in the longitudinal direction generates much more heat than a low resistance part A at the central part in the longitudinal direction. Thus, temperature distribution in the longitudinal direction in an overheat nip formed by the heater 1 and the roller 9 is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating element having a base and an electric heating element provided thereon, a heating device having a pressing member which is brought into pressure contact with the heating element, and an image forming method on the recording material. The present invention relates to an image forming apparatus provided as an image heating means for performing a heat treatment on the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as a heating apparatus of a recording material for heating and fixing an image, a heat roller type apparatus has been frequently used. However, the heat roller method has large power consumption,
Large temperature rise inside the machine, long waiting time after power on,
And so on. Therefore, as a method for solving these problems, a heating device of a film heating type has recently been proposed and put into practical use (Japanese Patent Laid-Open No. 63-313182,
See JP-A-2-1577878.

FIG. 1 shows an example of such a film heating apparatus.
It is shown in FIG. A thin heat-resistant film 5 (or sheet);
A moving drive means 6 for the fixing film 5, a heater 1 which is fixedly supported and arranged on one side of the film 5 with the film 5 in the middle, and a heater 1 on the other side which faces the heater 1. A pressurizing member 9 that is disposed and closely contacts the visible image bearing surface of the recording material P to be image-fixed to the heater 1 via the film 5; 9, the recording material P to be fixed is conveyed and introduced at a speed substantially the same as that of the recording material P to be fixed in the forward direction. The supporting surface is heated by the heater 1 via the film 5 to apply thermal energy to the visible image (unfixed toner image) T to soften and melt, and then separate the recording material P from the film 5 after passing through the fixing unit. Basically separate at points It is the thermal equipment.

In such a film heating method, a heating element having a very small heat capacity and a rapid temperature rise can be used, and the time required for the heater to reach a predetermined heating temperature can be greatly reduced. In addition, since the temperature can be easily raised to a high temperature even from a normal temperature, there is no need to perform standby temperature control when the apparatus is in a standby state during non-printing, which contributes to power saving.

FIG. 12 shows a plan view of an example of such a heater having a low heat capacity heating element.

The heater 1 is a heater base 2 having a longitudinal direction extending in the width direction of the fixing film 5 (perpendicular to the running direction of the fixing film 5), and having a heating element 3, a surface layer 10, and a current-carrying electrode 11. It is configured.

[0007]

However, in the above-mentioned conventional heating device, the heat capacity of the heating element is small, so the effect of heat radiation is large, and the temperature is reduced at the longitudinal end of the heating element having a large amount of heat radiation. For this reason, the temperature distribution in the longitudinal direction in the heating nip has a mountain shape in which the temperature at both ends is low and the center is high as shown in FIG. Here, the central portion is the A region where the temperature distribution is substantially constant at a predetermined temperature,
The end portion is a region B lower than a predetermined temperature.

When the material to be heated is heated in such a state, the heating of the end becomes insufficient. For example, when the material is used as an image fixing device, the fixing property of the end is remarkably deteriorated.
In some cases, it may not settle at all. Further, if the temperature of the heating element is increased to secure the fixing property at the end, the amount of heating at the center becomes too large, and a problem such as high-temperature offset occurs at the center.

As a means for solving this problem, the length of the heating device in the longitudinal direction is increased so that the area A having a constant temperature distribution is longer than the maximum sheet passing width of the material to be heated. Is performed only in the region A, but this is not preferable because the apparatus becomes large.

Further, the length of the heating element and the heating element in the longitudinal direction is made longer than that of the pressure roller, and the end of the heating element is not opposed to the pressure roller. There is a method of eliminating the above and making the temperature of this part higher than others. In this method, since the temperature of the non-pressed roller non-facing portion, which is the heated material non-sheet passing area, becomes higher, the heat radiation from the end of the heated material paper passing area and the heating from the pressure roller non-facing portion are offset. , The same temperature as the central part.

However, when the above method is used, a temperature difference is generated between a portion where the heating element protrudes from the pressure roller and a portion facing the pressure roller, and the protruding portion is considerably large. Because of the high temperature, the heating element was sometimes damaged by thermal stress at the boundary corresponding to the end of the pressure roller.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating device that prevents a temperature drop at an end of a heating body and does not cause breakage of a heater, and an image forming apparatus provided with the heating device.

[0013]

[Means for Solving the Problems]

[1]: In a heating device having a heating element having a base provided with an energizing heating element and a pressing member which is in pressure contact with the heating element, the energizing heating element faces the pressing member over the entire area in the longitudinal direction. A heating device which is pressed and has a heating value of the heating element larger at an end portion than at a center portion.

[2]: a heating element having an electric heating element provided on a base, a support member for fixing and supporting the heating element, a film sliding on the heating element, and the heating element sandwiching the film. A pressurizing member that presses and presses and conveys the material to be heated between the film and the pressurizing member, and applies heat from the heating body to the material to be heated via the film to heat the material. In the heating apparatus for processing, the energizing heating element is pressed against the pressing member over the entire region in the longitudinal direction, and the calorific value of the heating element is larger at an end portion than at a central portion.

[3] The heating device according to [1] or [2], wherein the resistance of the current-carrying heating element per unit length in the longitudinal direction of the end portion is larger than that of the central portion.

[4]: In a heating device having a heating element having a base provided with an electric heating element, an insulating holder for insulatingly supporting the heating element, and a pressurizing member for pressing against the heating element, A heating device characterized in that the heat insulating effect of the holder is enhanced at the ends rather than at the center.

[5] The heating device according to [4], wherein the heat insulating holder has an improved heat insulating effect at an end portion from a central portion in a region facing the pressure roller in the longitudinal direction.

[6]: a heating element having an electric heating element provided on a base, a heat insulating holder for insulatingly supporting the heating element, a film sliding on the heating element, and the heating element sandwiching the film. A pressurizing member that presses and presses and conveys the material to be heated between the film and the pressurizing member, and applies heat from the heating body to the material to be heated via the film to heat the material. In the heating device for processing, the heat insulating holder has an enhanced heat insulating effect at an end portion from a central portion in a region facing the pressing roller in a longitudinal direction thereof.

[7] The heating device according to [4], [5] or [6], wherein the heat insulating holder is provided with a gap between the heat insulating member and the heating element to enhance the heat insulating effect. .

[8] In an image forming apparatus having an image forming means for forming a developer image on a recording material, and an image heating means for heating the developer image, An image forming apparatus comprising the heating device according to any one of [1] to [7].

<Operation> That is, the heating element and the pressure member are brought into opposing pressure contact over the entire length thereof to increase the amount of heat generated at the end in the longitudinal direction of the heating element or to enhance the heat insulating property at the end. The temperature outside the pressure member does not rise excessively, and the heating element does not break due to the temperature difference between the portion facing the pressure member and the outside portion of the pressure member. And
Since the influence of heat radiation toward the edge is suppressed, a uniform temperature distribution can be obtained over the entire area of the paper passing.

Therefore, in the image forming apparatus provided with the heating device as the image heating means, it is possible to eliminate the difference in the fixing property between the central portion and the end portion, and to prevent defective fixing and high-temperature offset. .

[0023]

[Embodiment of the present invention]

<First Embodiment> 1. First Embodiment FIG. 1 shows a first embodiment of the invention according to the present application,
The heating element and the pressing member of the apparatus of the present example and the dimensional relationship in the longitudinal direction are shown. The basic configuration of the heating device is the same as that in FIG. 11, and a detailed description thereof will be omitted in this embodiment.

Reference numeral 1 denotes a heater corresponding to a linear heating element having an electric heating element provided on a base, and is wound around an endless belt around a moving driving means 6 and a driven roller 7 shown in FIG. It is arranged inside the fixing film 5.

The heater 1 is pressed against a rotatable pressure roller 9 via a fixing film 5.

Then, the fixing film 5 is rotated and driven by the driving of the moving driving means 6 so that the recording material P is transferred to the fixing film 5.
The film is passed along a joint portion corresponding to a nip portion between the recording material P and the pressure roller 9, and the unfixed image on the recording material P is heated and fixed by heat from the heater 1 given in the passage process. I have.

The heater support 8 insulates the heater 1 with respect to the entire heating device, for example, PPS (polyphenylene sulfide), PAI (polyamide imide), PI
(Polyimide), PEEK (polyetheretherketone), high-heat-resistant resins such as liquid crystal polymers, and composite materials of these resins with ceramics, metals, glasses, and the like. The heater substrate 2 has heat resistance, insulation, low heat capacity,
It is a member with high thermal conductivity, for example, a thickness of 1 mm and a width of 1
It is an alumina substrate having a length of 6 mm and a length of 340 mm.

The energizing heating element 3 is, for example, formed of Ag / Pd (silver palladium)
An electric resistance material such as Ta ₂ N is about 10 μm in thickness and 1 to 3 in width.
mm in a narrow band shape by screen printing or the like. A glass layer is provided thereon as a surface layer 10 for the purpose of insulation and protection. Further, PFA / PTFE is further added thereon to reduce the rubbing friction with the fixing film 5.
Etc. may be coated.

The temperature detecting elements 4a and 4b are arranged in contact with the upper surface of the heater substrate 2, that is, on the surface opposite to the side on which the energizing heating element 3 is formed, at intervals along the longitudinal direction of the heater substrate 2. A thermostat for temperature control and a thermofuse (or thermoswitch, etc.) for safety measures.

At both ends of the current-carrying heating element 3, current-carrying electrodes 11 are provided. One of the current-carrying electrodes 11 is connected to a temperature detecting element 4b via a power supply (not shown), and the power-supply section detects a temperature. The element 4a is connected via an energization control circuit (not shown), and the other energization electrode 11 is connected to the temperature detection element 4b.

2. In the present embodiment, as shown in FIG. 1, the length of the pressing roller 9 in the longitudinal direction is longer than the heating element 3, and the heating element 3 is connected to the pressing roller 9. Do not protrude outward from the end of the. That is, the heating element 3 of the heater 1 is in pressure contact with the pressure roller 9 in the entire area.

If the length of the heating element 3 is not equal to or longer than the maximum image area, it is difficult to obtain good fixability over the entire image area. is there.

The heater substrate 2 is longer than the pressure roller 9 because the heater substrate 2 has the current-carrying electrodes 11 outside the heating element 3.

The heating element 3 having the longitudinal dimension configuration as described above
At the end, the width of the heating element is reduced at the end to increase the resistance per unit length in the longitudinal direction. When the power supply electrode 11 of the heater 1 is energized, the heating element 3 generates heat. At this time, the amount of heat generated by each part of the heating element is proportional to RI ² .

Therefore, the high resistance portions B at both ends in the longitudinal direction
Generates a larger amount of heat than the low resistance portion A at the center in the longitudinal direction. This compensates for the escape of heat from the end,
The temperature distribution in the longitudinal direction in the heating nip N formed by the heater 1 and the pressure roller 9 can be made uniform.

FIG. 2 shows an outline of the temperature distribution of the heating nip N during the operation of the heating device. In the figure, the dotted line shows the case of the conventional configuration in which the heat generation amount is made uniform over the entire longitudinal area, and the solid line shows the configuration of this example.

As is apparent from this figure, in the heating device of the present embodiment, the temperature distribution in the longitudinal direction of the nip portion is substantially uniform, and even when the image is fixed, not only the fixing failure at the end but also the fixing unevenness is not caused. Not at all.

Further, since the heating element 3 of the heater 1 is completely pressed against the pressure roller 9, there is no place where the temperature of the heater 1 rises excessively, and the heater 1 does not crack due to thermal stress.

Although the resistance per unit length is changed according to the width of the heating element 3 in the present embodiment, it can be changed according to the thickness of the heating element 3.

<Second Embodiment> In this embodiment, the positional relationship such as the longitudinal dimension of the pressure roller 9 and the heater 1 is the same as that of the first embodiment. The resistance value is varied by changing the compounding ratio of the materials.

FIG. 3 shows a schematic configuration of the heater 1 of this embodiment. In the present embodiment, the width of the heating element 3 itself is uniform in the longitudinal direction, but since the mixing ratio of silver palladium is different between the central portion A and the end portion B, the end portion B has higher resistance than the central portion A. is there.
Therefore, the amount of heat generated at the end portion B is large as in the first embodiment,
This compensates for the escape of heat from the ends, so that the temperature distribution in the heating nip is uniform. At the same time, since the heating element 3 is configured not to protrude outside the pressure roller 9, damage due to excessive heating of the heater 1 does not occur.

In this embodiment, the width of the heating element 3 is made uniform. However, by combining Embodiments 1 and 2, the composition ratio of the materials and the material are changed, and the width of the heating element 3 is also changed. A configuration in which a required heat value is obtained by changing the resistance value per length may be adopted.

<Third Embodiment> In this embodiment, similarly to the first embodiment, the heating element 3 of the heater 1 is pressed against the pressure roller 9 over the entire area, and FIG.
As shown in (2), the shape of the end of the heating element 3 is meandered without changing the width of the heating element 3 (without changing the resistance partially), thereby generating heat per unit length with respect to the heater base 2. Increase body area. By taking such a pattern of the heating element 3, the amount of heat generated at the end portion B can be made larger than that at the central portion A, and the escape of heat from the heater end portion can be compensated. Over the temperature distribution became uniform.

Therefore, according to this embodiment, uniform and good fixability can be obtained over the entire image width. In addition, according to the present embodiment, the amount of heat generated at the end B can be freely controlled by changing the pattern of the heating element 3, so that the degree of freedom in design increases.

Since the heating element 3 is formed by screen printing or the like, a free-form element can be produced at almost the same cost as a linear element.

According to the experiments conducted by the present inventors, in a heater using a heating element having a normal straight shape and a length substantially equal to the maximum sheet passing width, the end is compared with the position of the temperature control temperature detecting element on the non-heating surface. The temperature began to drop from about 3 cm from the end, and at the end of the heating element 3, the temperature dropped by 30 degrees or more, whereas the meandering portion 3 a was moved from the end by about 2.5 cm.
In this example device using a heater provided from the place of cm,
The temperature drop at the end of the heating element was about 10
deg.

In the present embodiment, this can be made substantially uniform by increasing the area of the heating element 3 at the end portion, but if the temperature at the end portion is increased to that extent, a small-size recording material can be obtained. Is set to be about 10 deg., Because the temperature of the non-sheet passing portion when the sheet is continuously passed becomes so-called a non-sheet passing portion temperature rise. If the temperature drop at the end is within 10 deg, pressure is applied from both ends of the center axis of the pressure roller 9 so that the pressing force at both ends is slightly higher than the center and is compensated for over the entire image width. Uniform and good fixability can be obtained.

<Fourth Embodiment> In this embodiment, in a fixing device using the same device as in the above-described third embodiment, the heating element 1 has the form shown in FIG. In this figure, 3 and 3a and 3b are resistance heating elements as in the above embodiment, and C is a conductor.

In this embodiment, the heating element 3 has a uniform resistance in the longitudinal direction, and the heating elements 3a and 3b provided at the end B and connected in parallel with the heating element 3 correspond to the heat radiation at the end of the apparatus. The resistance is such that heat is generated.

With this configuration, when power is supplied to the electrode 11, the normal heating element 3 and the heating elements 3a and 3b connected by the conductor C generate heat. Could be increased.

Therefore, according to the present embodiment, good fixability can be obtained over the entire image width.

Further, by changing the material ratio of the heating elements 3, 3a, 3b, there is an advantage that the amount of heat generated at the end can be more finely adjusted, and the heating elements 3, 3a, 3b can be formed only in a linear shape.

<Fifth Embodiment> In this embodiment, the heat-generating portion of the heater 1 has a pressure roller 9 over its entire length.
The heat generation amount in the longitudinal direction of the heater 1 does not differ between the end portion and the center portion, is kept constant over the entire heat generating portion, and the recesses 12 are formed at both ends of the heat insulating holder 8 for insulating and supporting the heater 1. This is an example in which the heat insulating effect is enhanced by providing a hologram. Note that the other configuration is substantially the same as that of the first embodiment, and a description thereof will not be repeated.

FIG. 7 shows a heater, a heat insulating holder,
FIG. 4 is a dimensional relation diagram of a pressing roller in a longitudinal direction. The configuration of the heater 1 is the same as that of the conventional one shown in FIG. 11, and the resistance value is substantially uniform over the length.

The length of the heating element 3 of the heater 1 is equal to the maximum image width. The length of the pressure roller 9 is the heater substrate 2
Although it is shorter, it is longer than the heating element 3 and is opposed to the heating element 3 so as to cover the entire length of the heating element 3.

The heat-insulating holder 8 has a length from a position 2 to 3 mm outside the end of the resistance heating element to about 20 to 50 mm at which a temperature drop due to heat radiation at the end is expected. The recess 12 has a width of about 2.0 to 5.0 mm and a depth of about 1.0 to 3.0 mm, which is wider than the width.

Due to the depression 12, a gap exists between the heater substrate 2 and the heat insulating holder 8 at the longitudinal end B of the heater.

As a result, the heat insulating effect of the heat insulating holder 8 is larger at the end B than at the center A, and the heat radiation from both ends of the heater 1 to the heat insulating holder 8 is smaller than at the other parts, so that the end B at the surface of the body to be heated. Is reduced.

According to experiments by the inventors, when a stay (a heat-insulating holder 8) having no depression is used as shown in FIG.
At the end of the image area of the object to be heated, 30 deg. In some cases, the temperature drop was 10 deg. In the experiment using the stay provided with the depression 12. Within. Thus, the temperature drop at the end in the longitudinal direction is 10 deg. Within this range, the pressure is applied from both ends of the central axis of the pressure roller 9 so that the pressing force at both ends is slightly higher than that at the center, so that the uniformity and good fixability can be obtained over the entire image width. .

Further, since the outer end of the recess 12 is substantially the same as or outside the end of the resistance heating element, heat that escapes outward from the end of the heating element can be effectively prevented.

Therefore, by configuring as described above,
The effect of the present invention works more effectively with small depressions. Further, by making the length of the heater substrate 2 longer than the outside of the recess, there is an advantage that the mounting becomes easy and the mechanical strength becomes easy.

Also, the heating element 3 of the heater 1 receives the contact of the pressure roller 9 over the entire longitudinal area, and there is no portion where the temperature rises excessively, so that the heater 1 does not break.

In this embodiment, the heater 1 at the heater end is used.
A gap is provided between the heat-insulating holder 8 and the heat-insulating holder 8.
), The heat insulation effect between the central part and the end part may be different.

<Example of Image Forming Apparatus> FIG. 9 is a schematic structural view of an example of the image forming apparatus. The image forming apparatus of this embodiment is a copying machine or a printer using a transfer type electrophotographic process.

Reference numeral 31 denotes a rotating drum type electrophotographic photosensitive member which is rotated at a predetermined process speed (peripheral speed) in a clockwise direction indicated by an arrow.

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

Exposure 33 of the target image information is performed on the charged surface of the rotating photoreceptor 31 by an image information exposing unit (not shown) such as a slit image exposing unit of a document image and a laser beam scanning exposing unit. Thus, 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 by the toner developing device 34 as a toner image.

The toner image is transferred from a paper feed unit (not shown) to a transfer unit, which is a press-contact nip portion between the rotary photoreceptor 31 and a transfer roller 35 which is brought into contact with the transfer roller 35 and to which a predetermined transfer bias is applied. It is transferred onto the recording material (transfer paper) P conveyed at the timing.

The recording material P having received the transfer of the toner image after passing through the transfer section is separated from the surface of the rotating photoreceptor 31 and is conveyed to, for example, the heating device R of the film heating type shown in the first to fourth embodiments. After being introduced, the unfixed toner image undergoes heat fixing processing, and is output as a copy or a print.

After the transfer of the toner image to the recording material P, the surface of the rotary photoreceptor 31 is cleaned by the cleaning device 36 after removal of residual deposits such as untransferred toner, and is repeatedly used for image formation.

<Others> In the present invention, the heating device is not only a device for heating and fixing an image, but also, for example, a device for modifying a surface property (such as polishing) by heating a recording material carrying an image, a device for performing a temporary deposition process, and a sheet-shaped device. It can be widely used as a heating device for a material to be heated, such as a device for heating, drying and laminating while conveying a material.

[0073] (A) and (b) of FIG. 10 are schematic diagrams each showing another example of the configuration of the film-type heating device.

In the case of (a), an endless belt-shaped fixing film 5 is suspended between two members, a heater 1 supported by a heat insulating member 8 and a driving roller 6, and the film 5 is sandwiched. A pressure roller (driven roller) 9 is pressed against the heater 1 to form a nip portion, and the film 5 is conveyed by the rotation of the driving roller 6.

In the case of (b), the cylindrical fixing film 5 is loosely fitted outside the film guide member 13 holding the heater 1 via the heat insulating member 8, and the fixing film 5 is attached to the heater 1. Is pressed by a pressure roller 9, and the pressure roller 9 is driven to rotate so that the cylindrical fixing film 5 is driven to rotate while the inner surface thereof is in close contact with the heater 1 surface (press roller driving type, Tensionless type).

[0076]

As described above, according to the present invention, there is provided a heating device having a heating element provided with a current-carrying heating element on a base and a pressing member which is directly or indirectly opposed to and pressed against the heating element. The heating element is opposed to the pressing member over the entire length in the longitudinal direction of the heating element, and the amount of heat generated by the heating element is made larger at the end than at the center, thereby preventing a temperature drop due to escape of heat at the end of the heating element. However, it is possible to provide a heating device that does not cause breakage of the heating body.

Further, according to the present invention, a heating device in which a heating element provided with an energizing heating element provided on a base is insulated and supported by an insulating holder, and a pressing member is directly or indirectly brought into pressure contact with the heating element. In this configuration, the heat-generating body is opposed to the pressure member over the entire length in the longitudinal direction, and the heat-insulating effect of the heat-insulating holder is enhanced at the end from the center, thereby preventing a temperature drop due to escape of heat at the end of the heat-generating body. However, it is possible to provide a heating device that does not cause breakage of the heating body.

[Brief description of the drawings]

FIG. 1 is a diagram showing a dimensional positional relationship between a heater and a pressure roller according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a temperature distribution of a heating nip according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a heater according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a heater according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a temperature distribution of a heating nip according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a heater according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a dimensional positional relationship between a heater and a pressure roller according to a fifth embodiment of the present invention.

FIG. 8 is a diagram illustrating a temperature distribution of a heating nip according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a schematic configuration of an image forming apparatus of the present invention.

FIG. 10 is a schematic view of another configuration example of the present invention.

FIG. 11 is a diagram showing a conventional heating device.

FIG. 12 is a diagram showing a conventional heater.

FIG. 13 is a diagram showing a temperature distribution of a conventional heating nip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heater 2 Substrate 3 Heating element 4 Temperature detecting element 5 Film 6 Moving drive means 8 Heater support (insulated holder) 9 Pressurizing member 10 Surface layer 11 Current-carrying electrode 12 Depression

Claims (8)

[Claims] 1. A heating apparatus comprising: a heating element having a base provided with an electric heating element; and a pressurizing member which is in pressure contact with the heating element, wherein the electric heating element is connected to the pressing member over the entire region in the longitudinal direction. A heating device, wherein the heating unit is opposed to each other and the amount of heat generated by the heating element is larger at an end portion than at a center portion. 2. A heating element having a base provided with an electric heating element, a support member for fixing and supporting the heating element, a film sliding on the heating element, and being pressed against the heating element with the film interposed therebetween. Pressurizing member, and sandwiches and conveys the material to be heated between the film and the pressing member, and applies heat from the heating body to the material to be heated through the film to perform a heat treatment. In the heating device, the energizing heating element is opposed to and pressed against the pressing member over the entire region in the longitudinal direction, and the calorific value of the heating element is larger at an end portion than at a central portion. 3. The heating device according to claim 1, wherein the current-carrying heating element has a greater resistance per unit length in a longitudinal direction of an end portion than in a central portion. 4. A heating apparatus comprising: a heating element having a base provided with an electric heating element; a heat insulating holder for thermally insulating the heating element; and a pressurizing member facing and pressure-contacting the heating element. A heating device characterized in that the heat insulation effect is enhanced at the ends from the center. 5. The heating device according to claim 4, wherein the heat insulating holder has a higher heat insulating effect at an end portion than at a central portion in a region facing the pressure roller in the longitudinal direction. 6. A heating element having a base provided with an electric heating element, a heat insulating holder for thermally insulating the heating element, a film sliding on the heating element, and being pressed against the heating element with the film interposed therebetween. Pressurizing member, and sandwiches and conveys the material to be heated between the film and the pressurizing member, and applies heat from the heating body to the material to be heated through the film to perform heat treatment. In the heating device, the heat insulating holder has an improved heat insulating effect at an end portion of a region facing the pressure roller in a longitudinal direction than at a central portion. 7. The heating apparatus according to claim 4, wherein the heat insulation holder has a heat insulating effect by providing a gap between the heat insulation holder and the heating element. 8. An image forming apparatus comprising: an image forming unit for forming a developer image on a recording material; and an image heating unit for heating the developer image, wherein the image heating unit is used as the image heating unit. An image forming apparatus comprising the heating device according to any one of claims 1 to 7.