JP3478697B2 - Heat fixing device - Google Patents

Description

Detailed Description of the Invention

[0001] The present invention relates to an image to be electrophotographic system printer or a copying machine using such, or a facsimile, etc. and
The present invention relates to a heat fixing device that heats and fixes unfixed toner formed and carried on a recording material in a forming device .

[0002]

2. Description of the Related Art Conventionally, as a fixing device for fixing an unfixed image on a recording material in an image forming apparatus such as a printer, a copying machine or a facsimile using an electrophotographic method, a contact heating method having good heat efficiency and safety. Is widely known, and in recent years, from the viewpoint of energy saving promotion, a film heating type fixing device that heats through a film with a small heat capacity is attracting attention as a method with high heat transfer efficiency and quick device startup. And is disclosed in Japanese Patent Laid-Open No. 63-
No. 313182, Japanese Patent Laid-Open No. 2-157878.
JP-A-4-44075-44083 and JP-A-4-2049.
It is proposed in Japanese Unexamined Patent Publication No. 80-204984.

The film heating type fixing device has a structure in which a film is conveyed between a pressure roller and a pressure roller while applying tension by using a conveyance roller for exclusive use of film conveyance and a driven roller. There is a structure in which the pressure roller is driven by the conveying force, and the former has an advantage that the conveying property of the film can be enhanced, and the latter has an advantage that the constitution can be simplified and a low-cost fixing device can be realized.

As a concrete example, the latter pressure roller drive type film fixing device is shown in FIG. In the figure, recording material 1
The image formed by the toner 2 formed on the upper surface of the pressure roller 3 is made of heat-resistant rubber, and the total pressure of the pressure roller 3 is 4 to 4
The pressure is applied to about 15 kgf, and the friction roller causes the pressure roller 3 to rotate and is conveyed to a nip portion with a cylindrical fixing film 4 which is rotated and conveyed along a heater holder 10 which also serves as a film guide member. Heater 5
It is heated and pressurized by. Heater 5 as heating means
Is formed with a pattern of a heating element 8 on a heater substrate 6 made of a heat-resistant insulating material such as ceramic, and the surface is made of a heat-resistant glass 9
The temperature detection element 7 is disposed on the back surface of the heater substrate 6, and the temperature of the fixing device is controlled by detecting the temperature of the back surface of the substrate.

FIG. 16 is a front view of the heating element forming surface of the heater 5, and the heating element 8 is formed in one strip shape.
The material of the heating element 8 is silver palladium (Ag / Pd), R
The heater substrate 6 is an energization generator such as uO ₂ or Ta ₂ N.
Heat is generated by energization from the energizing electrode 11 formed on the surface of the.

The fixing film 4 has a thickness of 1 in order to reduce the heat capacity and improve the quick start property.
PTFE or PF having heat resistance, release property and durability of 00 μm or less, more preferably 40 μm or less and 20 μm or more
A, PPS single layer film or polyimide, polyamide imide, PEEK, PES film surface PTF
It is a composite layer film in which E, PFA and EEP are coated as a release layer.

As described above, various image forming apparatuses such as printers using the above fixing device do not require preheating during standby due to high heating efficiency and rising speed.
It has many advantages such as elimination of waiting time, and it is expected to be introduced to small-sized low-speed machines and to large-sized machines and high-speed machines in the future.

[0008] However, conventionally, when the fixing device is adapted to cope with various sizes of paper at a high speed while accommodating paper of various sizes, a common problem has been called a non-sheet passing portion temperature rise. This is because the temperature of the fixing nip portion in the area where the recording material does not pass (non-sheet passing portion) rises excessively when a small-sized recording material having a small width in the longitudinal direction of the fixing device is continuously passed, and If the temperature exceeds the heat resistant temperature of the member, the fixing device will be damaged by thermal deformation, or the local expansion of the pressure roller will result in uneven fixing in the longitudinal direction when the next size recording material is passed. This causes wrinkles due to uneven conveyance of the recording material.

Conventionally, this problem has been dealt with by reducing the fixing speed and the throughput only when a small-sized recording material is passed, but for this reason, the printing speed is reduced for a small-sized recording material. I had to allow the speedup to be suppressed.

Even in a film heating type fixing device, the above-mentioned temperature rise in the non-sheet passing portion is a serious problem, and since a film is used in particular, the pressure roller in the non-sheet passing portion expands to cause the non-sheet passing portion. There was also a problem peculiar to the film heating method that the film transporting force of the portion was higher than that of the sheet passing portion, and the film was unevenly transported in the longitudinal direction, and the film was damaged.

To alleviate this problem, a method of evenly releasing stress in the left and right with respect to the center side of the sheet passing standard is used. As an example, FIG. 17A shows a film heating method of the central sheet passing standard type. It shows a case where a small-sized recording material 1'having a width sufficiently narrower than the width of the heater is continuously passed through the fixing device. As shown in FIG. 17B, the temperature distribution in the longitudinal direction of the heater substrate 6 at this time is such that the temperature Tf originally required for fixing is replenished while replenishing the amount of heat that is successively taken by the recording material that is continuously fed. Since the energization of the heater is controlled so as to maintain it at XA, the non-sheet passing portion XB is gradually accumulated and increased to easily reach the excess temperature To which exceeds the fixing temperature Tf.

When an attempt is made to increase the printing speed, the amount of heat taken by the recording material per unit time in the paper passing portion XA increases, and as a result of this, the amount of electricity supplied to the heating element rises, resulting in excess of the non-paper passing portion XB. The temperature To also rises to a higher temperature, which eventually exceeds the heat resistant temperature of the peripheral members and causes thermal deformation of the members.

Further, in order to accelerate the speed, it is necessary to widen the width of the heating element to increase the amount of heat supplied, and at the same time, the width of the heater substrate is also widened. As a problem, as shown in the temperature distribution around the nip portion of the heater holder of FIG. 18B corresponding to the sectional configuration diagram of FIG. Occur. This is because this fixing method is because the heater 5 and the heater holder 10 are fixedly arranged around the fixing nip portion, and it is considered that the generation mechanism is as follows.

First, the ambient temperature distribution due to the heat generated from the heating element 8 in the central portion of the nip shows the central position y in the stopped state.
The thin solid line C in FIG.
_Although it tries to create a temperature distribution with a normal distribution like the curve of ₁ , the heat generated in the central part of the nip when the continuous paper feeding is performed, the film 4 and the recording material 1, which are conveyed from the upstream side to the downstream side, are heated. By the pressure roller 3 and the like (mainly a pressure roller having a large heat capacity), heat is taken by these members invading at a low temperature before fixing on the upstream side of the heater substrate 6, and the temperature of the upstream side of the heater substrate becomes higher than the fixing temperature Tf. It doesn't heat up,
On the downstream side of the nip portion, heat is supplied from the heater 5 to raise the temperature, so that the amount of heat taken by each member from the heater substrate 6 decreases, the temperature on the downstream side becomes relatively high, and the thick portion in FIG. A temperature distribution is generated on the heater substrate as shown by the curve of solid line C ₂ . When this heat accumulation increases, the substrate downstream side y
The temperature of No. 2 rises to an excessive temperature Ta higher than the fixing temperature Tf, and even in the sheet passing area, the temperature rises to the fixing temperature Tf or higher, and heat is propagated to the heater holder 10 and finally fixed once. Further, the toner is further heated by the temperature of the downstream side end portion 10a of the heater holder 10 which has become high in temperature when exiting the nip, which causes a phenomenon in which the toner melts and adheres to the fixing film side (referred to as high temperature offset). Even if the heater holder does not heat up to this level, the temperature rise in the non-sheet-passing area when a small-sized recording material passes through the fixing device tends to rise to a higher temperature. The occurrence of this phenomenon makes it more difficult to increase the speed of the film heating type fixing device.

In addition to the above-mentioned problems, another problem that makes it difficult to increase the speed of a film heating type fixing device is an increase in flicker that occurs when electricity is applied to a heating element. The film heating method has a smaller heat capacity than other methods and uses a heat source with a relatively low resistance, so on the contrary, the amount of inrush current supplied to the heater at the start of fixing tends to increase, and this influences the same power source. It gives flicker noise to other electric devices connected to the supply network. Since it is necessary to increase the energizing current to the heater in order to realize high-speed fixing, this phenomenon also becomes remarkable.

[0016]

The problem to be solved by the present invention is to have a heating means and a heat resistant film which is set to be slidable while being in contact with the heating means. Forming apparatus having a fixing device for adhering an unfixed image on the non-heating material permanently by passing through a heating region together with the heat resistant film while closely adhering to the surface of the heat-resistant film opposite to the side where the heating means is arranged. In the above, an excessive temperature rise at the downstream end of the heating means and the heating means supporting member with respect to the passage direction of the non-heated material, which occurs with the increase in the fixing speed, and a small-sized material to be heated are passed. This is because an excessive rise in temperature of the non-sheet-passing portion and an increase in the amount of rush current that is required to start fixing and an increase in flicker noise are caused.

Therefore, an object of the present invention is to solve the above-mentioned problems and realize a high fixing speed in a film heating type fixing device without causing an abnormal temperature rise around the fixing device or an increase in electrical noise. High-speed and energy-saving heating
To provide a dressing device .

[0018]

The above object of the present invention relates to the present invention.
This is achieved with a heat fixing device . In summary, the present invention is
A heater having a heater substrate having heating elements are formed, the heat
Heater holder for holding the heater and the periphery of the heater holder
A heat-resistant film that rotates while its inner surface is in contact with the heater, and a material to be heated is the heat-resistant film described above.
In a heat fixing device for permanently fixing an unfixed image on the material to be heated by passing through a heating region together with the heat resistant film while closely contacting with a surface on the opposite side of the heater arrangement side ,
The heater surface opposite to the heat-resistant film rubbing surface and the heater
Of the end portion on the downstream side in the passage direction of the heated material between the heater holders
Only opposite to the heat resistant film rubbing surface of the heater.
Contact both the surface and the heater holder and
The heating and fixing device is characterized by having a good thermal conductive member that suppresses a temperature rise at the downstream end of the heater holder in the passage direction of the material to be heated.

[0019]

[0020] The good heat conductive member is preferably disposed so as not to overlap with the patterned portions of the heating element across the heater. In front of the good heat conductive member
It is preferable to provide the second good heat conductive member at a position corresponding to the non-passage area of the material to be heated in the heater longitudinal direction . The good heat conductive member is preferably a ceramic material or an aluminum plate.

[0021]

[0022]

According to another aspect of the present invention, the heating element is
A heater having a formed heater substrate and the heater
The heater holder to hold and the inner surface around the heater holder
A heat-resistant film that rotates while contacting the heater,
And has a heater to be placed on the heat-resistant film.
With the heat-resistant film while making close contact with the surface on the opposite side of the table
Together with the heating area, unfixed on the heated material
In a heat fixing device for permanently fixing an image, the heater
Is the amount of heat generated in the non-passage area of the small-sized material
First heating element higher than the calorific value of
The heat generation amount of the passage area of the second is higher than that of the non-passage area
And a second heating element, wherein the first heating element
It must be installed upstream of the heating element in the moving direction of the material to be heated.
A heat fixing device is provided.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The heat fixing device according to the present invention will be described below in more detail with reference to the drawings. The same members as those described above are designated by the same reference numerals.

Example 1 Example 1 according to the present invention will be described below with reference to FIGS. First, the overall configuration of the image forming apparatus of this embodiment will be described with reference to FIG.

In FIG. 3, the photosensitive drum 21 is rotationally driven in the direction of the arrow, and the surface thereof is first uniformly charged by the charging roller 22 as a charging device. Next, scanning exposure is performed by the laser beam 23 whose ON / OFF is controlled according to the image information, and an electrostatic latent image is formed. This electrostatic latent image is developed and visualized by the developing device 24. As a developing method, a jumping developing method, a two-component developing method, FE
The ED development method or the like is used, and image exposure and reversal development are often used in combination.

The visualized toner image is transferred from the photosensitive drum 1 onto the recording material 1 conveyed at a predetermined timing by a transfer roller 25 as a transfer device. At this time, the recording material P is nipped and conveyed by the photosensitive drum 1 and the transfer roller 25 with a constant pressing force. The recording material 1 to which the toner image is transferred is conveyed to the fixing device 26 and fixed as a permanent image. On the other hand, the transfer residual toner on the photosensitive drum 1 is removed from the surface of the photosensitive drum 21 by the cleaning device 27.

As shown in FIG. 1 (A), the fixing device of this embodiment has substantially the same structure as the conventional fixing device shown in FIG. 15 and FIG. 18 (A). That is, in FIG. 1, the fixing device includes a pressure roller 3 made of heat-resistant rubber, and a cylindrical fixing film 4 that is rotated and conveyed along with a heater holder 10 that also functions as a film guide member as the pressure roller 3 rotates. The image formed by the toner 2 formed on the recording material 1 is heated and pressed by the heater 5 serving as a heating unit through the fixing film 4 at the nip portion between the pressure roller 3 and the fixing film 4.

In the heater 5, a heating element 8 is patterned on a heater substrate 6 made of a heat-resistant insulating material such as ceramics,
The surface of the heater substrate 6 is protected by heat resistant glass 9.
A temperature detecting element 7 is arranged on the back surface of the substrate, and the temperature of the fixing device is controlled by detecting the temperature of the back surface of the substrate.

In the heater 5 of this embodiment, a ceramic plate 12 made of the same material as that of the heater substrate 6 is inserted between the heater substrate 6 and the heater holder (heating means supporting member) 10 in close contact with each other. Cage and ceramic plate 1
The other surface of 2 is made to face this space and the ceramic plate 12
Is configured to promote the dissipation of heat from the surface of the. More specifically, one surface of the ceramic plate 12 is closely fixed to the surface of the heater substrate 6 opposite to the heating body 8 along the longitudinal direction of the heater substrate 6, and the other surface is fixed to the heater holder 1.
It is in contact with 0.

By using the above configuration, the heat capacity is increased only on the downstream side of the heater substrate 6, so that the temperature increase on the downstream side of the heater substrate 6 and the heater holder 10 does not occur even if the fixing process is repeated at the same fixing temperature as the conventional one. Suppressed, fig 1
As shown by the thick solid line C ₃ in FIG.
The maximum value of the temperature of a (y2) falls to a temperature near the fixing temperature Tf, which is sufficiently lower than the conventional peak temperature Ta shown by the broken line C ₂ , and it is not necessary to improve the heat resistance of the heater holder 10, and the fixing is performed as in the conventional case. No high-temperature offset occurs at the rear end of the nip.

Further, in the present configuration, the end temperature of FIG. 2B is the same as that of the conventional case even if the temperature of the non-sheet passing portion XB is increased when the small size paper 1'is passed as shown in FIG. 2A. Is sufficiently lower than the over temperature To of the peripheral member, the temperature can be easily lowered to the allowable temperature Ts within the heat resistant temperature range of the peripheral member, and the difference from the fixing temperature Tf of the central portion XA, which is the paper passing portion, is eased. High-speed fixing can be realized without adversely affecting the recording material 1 by the fixing film 4 and the material to be heated due to the expansion of the pressure roller 3 of the paper portion XB.

In the above structure, if the set position of the ceramic plate 12 to be added to the back surface of the heater substrate 6 is overlapped with the back surface of the area where the heating element 8 is formed on the front surface of the heater substrate 6, the heating element 8 being fixed is fixed. Since the heat is also taken away, there is a danger of causing fixing failure. Therefore, by providing a width d of at least 0.5 mm or more, and more preferably 1 mm or more between the position corresponding to the back surface of the rear end of the area where the heating element 8 is formed and the tip of the additional ceramic plate 12, it is possible to prevent fixing failure. It is possible to suppress the temperature rise on the downstream side end portions of the heater substrate 6 and the heater holder 10.

Example 2 Next, a second embodiment will be described with reference to FIGS.

The fixing device of the present embodiment has a structure similar to that of the fixing device of the embodiment 1 shown in FIG.
As shown in FIG. 5A, a ceramic plate 12 made of the same material as the heater substrate 6 is closely attached between the heater substrate 6 and the heater holder 10, and further only at the position of the non-sheet passing portion XB. A ceramic plate 12 'for the non-sheet passing portion was attached.

With this configuration, the temperature rise on the downstream side of the heater substrate 6 and the heater holder 10 is suppressed similarly to the first embodiment, and the downstream end portion y2 of the downstream side end portion y2 is shown as shown by the thick solid line C ₄ in FIG. 4 (B). The maximum temperature drops to a temperature near the fixing temperature Tf, which is sufficiently lower than the conventional peak temperature Ta shown by the broken line C ₂ , and it is not necessary to increase the heat resistance of the heater holder 10.
There is no occurrence of high temperature offset at the rear end of the fixing nip as in the conventional case.

Further, in the present configuration, as shown in FIG.
The end temperature of (B) can be lowered to the allowable temperature Ts' lower than the allowable temperature Ts of the first embodiment, and the difference from the fixing temperature Tf of the central part is significantly eased, so that the continuous operation is continued for a long time. Even when the paper is passed, high-speed fixing can be realized without adversely affecting the film or the paper due to the expansion of the pressure roller in the non-paper-passing portion.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. 6 and 7.

As shown in FIG. 6 (A), the fixing device of the present embodiment has a substantially similar structure, and an aluminum plate is used between the heater substrate 6 and the heater holder 10 instead of the ceramic material of the first embodiment. The plates 12 "are inserted in close contact with each other, and the remaining surface of the aluminum plate 12" is set to face the air gap so as to promote heat dissipation from the surface of the aluminum plate 12 ". .

By using the above configuration, the temperature rise on the downstream side of the heater substrate 6 and the heater holder 10 is suppressed as in the first and second embodiments, and the thick solid line C in FIG. 6B is used.
_As shown in ₅ , the maximum value of the temperature at the downstream end y2 is the broken line C.
_The temperature is lowered to near the fixing temperature Tf sufficiently lower than the conventional peak temperature Ta shown by ₂ , and it is not necessary to improve the heat resistance of the heater holder 10 and the high temperature offset does not occur at the rear end of the fixing nip unlike the conventional case.

Further, in this structure, as shown in FIG. 7 (A), the inserted aluminum plate 12 ″ has a high thermal conductivity even with respect to the temperature rise in the non-sheet passing portion when the small size sheet 1 is passed. Heater board 8
Since the temperature distribution in the longitudinal direction generated in Fig. 7 is efficiently dispersed, the end temperature in Fig. 7 (B) is sufficiently lower than the conventional excess temperature To and can be lowered to the allowable temperature Ts "within the heat resistant temperature range of the peripheral members. Since it becomes easier and the difference from Tf in the central portion is greatly eased, the fixing film 4 and the paper 1 are not adversely affected by the expansion of the pressure roller 3 in the non-paper passing portion even if the paper is continuously fed for a long time. High-speed fixing can be realized without any occurrence.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In the above embodiment, the heating source is one, for example 80
In contrast to the 0W output heater, that is, the heating element,
In this embodiment, as shown in FIG.
In order to increase the heat generation amount of the area XB corresponding to the non-sheet passing portion, the heating element 13 on the upstream side with respect to the sheet passing direction has the same line width in order to increase the amount of heat generated. The heating element 14 on the downstream side has a plurality of non-sheet-passing portion high-temperature heat generating portions 13a that are folded back. The center high temperature heat generating portion 14a having a folded shape is provided.

As shown in FIG. 8B, the temperature distribution in the longitudinal direction when the heating elements 13 and 14 are continuously energized is as shown in FIG. 8B.
Since the temperature does not reach f and the low temperature part t1 is further low, it is not possible to supply the required amount of heat during the fixing process by each of them alone, but both are operated at the same time, or they are sufficiently faster than the sheet passing speed. The heat generation amount is adjusted so that the fixing temperature can be maintained by switching to and operating.

Further, as shown in FIGS. 9A and 9B, the temperature distribution in the sheet passing direction of the heat generating element is such that the temperature on the upstream side is low and the temperature on the downstream side is low in the region of the central portion XA. On the contrary, in the area of the non-sheet passing portion XB, the temperature on the upstream side is high and the temperature on the downstream side is low, but the maximum value of the high temperature portion T1 is one 800 W heating element in each area. The value is sufficiently lower than the maximum value when used.

By using the above construction, even if the fixing process is repeated at the same fixing temperature as the conventional one, heat is unilaterally accumulated on the downstream side by dispersing the heat generation center on the upstream side and the downstream side of the fixing nip portion. This is alleviated, and the temperature rise on the downstream side of the heater substrate and the heater holder can be suppressed by selecting the heating element on the downstream side of the non-sheet passing portion even when the temperature of the non-sheet passing portion rises.

Further, in this configuration, it is possible to greatly improve the temperature rise in the non-sheet-passing portion when a small-sized sheet is passed by controlling the operation ratio of each heating element. Figure 10
(A), (B), and (C) show examples of energization control method for each heating element in each case of startup of the fixing device of this configuration, fixing of normal size paper, and fixing of small size paper. However, in the actual control of the film heating type fixing device, since the heat capacity is small, the load fluctuation at the time of control becomes large, and detailed control by multi-step power control is required, but the details here are the main purpose. Since it does not exist, only the basic concept will be described, and a conceptual comparison will be made based on the ratio of ON / OFF time.

First, in FIG. 10A, two heating elements 13 and 14 are operated almost at the same time in order to heat the cooled fixing device in the state where the apparatus is completely stopped to the target temperature in the shortest time. The control state of each heating element at the time of turning on the power of 800 W is shown. The fact that the rising and falling timings of the heating elements 13 and 14 when turned on and off are different is a measure for preventing the occurrence of large flicker noise due to a sudden load change when operating at exactly the same time. Despite having almost no effect on the start-up time of the fuser, the inrush current can be halved compared to the conventional one-heater type start-up, so the effect on other devices connected to the same power source is significant. Be improved.

Next, FIG. 10 (B) shows a control method for fixing a normal full-size paper. Usually, an output of about 600 W is required for fixing this size, so
It is not necessary to operate the heating element of the book, but since fixing is poor on only one side, it is necessary to incorporate a heating period with two and a heating period for only one side, while for uniform heating in the longitudinal direction. For this reason, it is necessary to operate the two heating elements evenly within a fixed period. Therefore, in FIG. 10 (B), the two heating elements are not turned on / off at the same time, and a control is performed in which the two heating elements are alternately and evenly repeated while providing a period for heating with the two heating elements. At this time, the length of the period in which the two heating elements 13 and 14 are operated uniformly varies depending on the fixing speed, and within 1 second, a good image with sufficient fixing unevenness can be obtained even at the fixing speed of about 100 mm / second. be able to.

Further, FIG. 10C shows an example of control for preventing the temperature rise of the non-sheet passing portion when fixing the small size paper. In this case, almost no heating to the non-sheet passing portion is performed. Control is performed to extremely reduce the operating rate of the non-sheet passing portion high temperature heating element 13 so as to eliminate it. The effect of suppressing the temperature rise of the non-sheet passing portion at this time is great because the heating elements are dispersed upstream and downstream to suppress the temperature rise on the downstream side as described above and the heating amount of the non-sheet passing portion is suppressed. It has various effects and enables high-speed fixing even for small size paper.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. 11 and 12.

In the present embodiment, as means for providing two heating elements 15 and 16 of 400 W output with a heat generation amount distribution in the longitudinal direction, one high resistance heating element region and a low resistance heating element region are provided in the longitudinal direction of one and the same strip heating element. A composite resistance heating element in which a resistance heating element area is formed is used. The heating element 15 on the upstream side has a high resistance heating area 15a in the non-paper passing portion, and the heating element 16 on the downstream side has a low resistance heating area in the non-paper passing portion. 16a, the operation and control method thereof are the same as in the fourth embodiment, and the description of FIGS. 11B, 12A, and 12B related thereto is omitted.

In this embodiment, since it is not necessary to form a complicated heating element pattern shape on the heater substrate and it can be realized with a relatively narrow width by selecting the resistance value, the fixing nip portion can be shortened to reduce the size of the apparatus. Can be promoted.

As a means for forming the high resistance heating element region and the low resistance heating element region in the longitudinal direction of the same heating element, masking and multiple printing are performed in the screen printing step of the heating element to perform heating in the longitudinal direction. There are a method of forming a film thickness distribution, a method of multiple printing of heating element materials having different resistance values, and the like.

Embodiment 6 Next, Embodiment 6 of the present invention will be described with reference to FIGS. 13 and 14.

In this embodiment, a pattern in which the width of the strip is changed in the longitudinal direction of one identical strip-shaped heating element is formed as a means for providing two heating elements of 400 W output with a heating value distribution in the longitudinal direction. By doing so, the current density is increased in the narrow region to increase the amount of heat generation, and the current density is decreased in the wide region to expand the heat dissipation area. This has the effect of releasing more of the heat accumulated in the heater substrate to the opposing member side.

At this time, the central low temperature heat generating portion 17a of the upstream heat generating element 17 and the non-sheet passing portion low temperature heat generating portion 18a of the downstream heat generating element 18 are combined, and the operation and control method thereof are the same as those of the embodiment. Same as 2.

This embodiment is suitable for the case where a relatively high calorific value is not required, and the pattern formation can be realized easily and accurately without complicating the screen printing process of the heating element.

In each of the above embodiments, the shape of the heating element is shown by changing the boundary between the central portion and the non-sheet passing portion extremely for simplification of the drawing, but in the actual heating element shape It is a matter of course that the upstream and downstream heat generating elements are devised so as to prevent the extreme change in the fixing property at the boundary by gradually changing the boundary.

Further, in each of the above-mentioned embodiments, the configuration based on the central sheet feeding is used, but it is needless to say that the same measure can be taken with the configuration based on the one side sheet feeding and the same effect can be obtained.

[0061]

As is apparent from the above description, according to the present invention, a heater having a heater substrate on which a heating element is formed is provided.
Heater holder for holding the heater and the heater holder
Heat resistance that the inner surface rotates while contacting with the heater
Heat-resistant film.
Heat-resistant film while closely adhering to the surface opposite the data placement side
And the unfixed image on the material to be heated by passing through the heating area.
In a heat fixing device that permanently fixes the
Between the surface opposite the rubbing surface of the thermal film and the heater holder,
Only on the downstream end of the heating material in the passage direction, the heat-resistant
Make sure that it touches both the surface opposite the rubbing surface of the film and the heater holder.
End of the heater and heater holder in the passage direction of the material to be heated
To have a good thermal conductive member that suppresses the temperature rise of the parts
Prevents fixing defects due to unnecessary increase in heat capacity of the heater.
It is possible to prevent excessive temperature rise on the downstream side while stopping. Also, the heat
The heat generation amount in the non-passage area of the small-sized heated material
First heating element higher than the heating value of the area and small size to be heated
The heating value of the material passing area is higher than that of the non-passing area.
Two heating elements, wherein the first heating element is the second heating element.
It is provided upstream of the heating element in the moving direction of the material to be heated.
As a result, the temperature rise in the non-passage area of the heated material
However, even if the heat generation amount in the non-passage area of the heated material is high
Since the heating element is arranged on the upstream side in the moving direction of the heated material,
To reduce the peak temperature of the temperature rise in the non-passage area of the heated material
You can

[Brief description of drawings]

FIG. 1 is a sectional view (A) of the fixing device in a sheet passing direction and a temperature distribution diagram (B) of a fixing peripheral member in a sheet passing direction.

FIG. 2 is a front view (A) of a fixing heater and a longitudinal temperature distribution diagram (B) of a fixing peripheral member when a small-sized sheet is passed in Example 1.

FIG. 3 is a schematic configuration diagram of an image forming apparatus in which the present invention is implemented.

FIG. 4 is a sectional view (A) of a fixing device in a sheet passing direction and a temperature distribution diagram (B) of a fixing peripheral member in a sheet passing direction.

FIG. 5 is a front view (A) of a fixing heater and a longitudinal temperature distribution diagram (B) of a fixing peripheral member when a small-sized sheet is passed in Example 2.

FIG. 6 is a cross-sectional view (A) of the fixing device in the sheet passing direction and a temperature distribution diagram (B) of the fixing peripheral member in the sheet passing direction.

FIG. 7 is a front view (A) of a fixing heater and a temperature distribution diagram (B) in the longitudinal direction of a fixing peripheral member when a small-sized sheet is passed in Example 3.

FIG. 8 is a front view (A) of a fixing heater according to a fourth exemplary embodiment and a temperature distribution diagram (B) in a longitudinal direction of a heating element.

FIG. 9 is a temperature distribution diagram of the central heating element in the sheet passing direction (A) and a temperature distribution diagram of the non-sheet passing element heating element in the sheet feeding direction of Example 4 (B).
Is.

FIG. 10 is a conceptual diagram (A) of a start-up control signal of a fixing heater, a conceptual diagram (B) of a full-size sheet-passing control signal, and a conceptual diagram (C) of a small-size sheet-passing control signal in Example 4. .

11A is a front view of a fixing heater according to the fifth exemplary embodiment, and FIG. 11B is a temperature distribution diagram in a longitudinal direction of a heating element.

FIG. 12 is a temperature distribution diagram of the heating element in the central portion in the sheet feeding direction (A) and a temperature distribution diagram of the heating element in the sheet non-passing portion in the sheet feeding direction in Example 5 (B).
Is.

FIG. 13A is a front view of a fixing heater according to a sixth exemplary embodiment, and FIG. 13B is a temperature distribution diagram in a longitudinal direction of a heating element.

FIG. 14 is a temperature distribution diagram of the central heating element in the sheet passing direction (A) and a non-sheet passing portion heating element in the sheet passing direction (B) of Example 6;
Is.

FIG. 15 is a cross-sectional view of a conventional fixing device in the sheet passing direction.

16 is a front view of a fixing heater of the fixing device shown in FIG.

FIG. 17 is a front view (A) of a fixing heater of a conventional example when a small-size sheet is passed, and a longitudinal temperature distribution diagram (B) of a fixing peripheral member.

FIG. 18 is an enlarged cross-sectional view of the fixing device in the sheet feeding direction of the conventional example (A), and a temperature distribution diagram of the fixing peripheral members in the sheet feeding direction (B).
Is.

[Explanation of symbols]

1 recording material (material to be heated) 2 toner image 3 pressure roller 4 heat resistant film 5 heater (heating means) 6 heater substrate (heat resistant insulating material) 8 heating element 9 heat resistant glass 10 heater holder (heating means supporting member) 12 Ceramic plate (heat resistant insulating substrate)

(72) Inventor Yozo Hotta 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahiko Suzuki, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-2-157884 (JP, A) JP-A-4-180076 (JP, A) JP-A-5-181375 (JP, A) JP-A-5-289555 (JP, A) Kaihei 6-282188 (JP, A) JP-A-7-5791 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (5)

(57) [Claims] 1. A heater substrate having a heating element formed thereon.
A heater ; a heater holder for holding the heater;
Rotates while contacting the inner surface of said heater around Tahoruda
And a heat-resistant film , which is passed through a heating region together with the heat-resistant film while closely adhering the material to be heated to the surface of the heat-resistant film on the side opposite to the heater disposition side, on the material to be heated. In a heat fixing device for permanently fixing an unfixed image, a surface of the heater opposite to a surface of the heat resistant film and a front surface of the heater.
The downstream end of the heated material in the passage direction between the heater holders
The heat-resistant film rubbing surface of the heater
The heater is in contact with both the opposite surface and the heater holder.
Heat fixing apparatus characterized by having a good heat conductive member to suppress the temperature rise in the passing direction downstream end of the heated material of the heater holder with. Wherein said good heat conductive member, heat fixing instrumentation of claim 1, characterized in that it is arranged so as not to overlap with the patterned portions of the heating element across the heater
Place 3. The longitudinal direction of the heater of the good thermal conductive member
Heating constant of claim 2, characterized in that a second good heat conductive member in a position corresponding to the non-passage region of the material to be heated in a countercurrent
Wearing device . Wherein said good heat conductive member also claim 2, characterized in that a ceramic material or aluminum plate
3 is a heat fixing device . 5. A heater substrate having a heating element formed thereon.
A heater; a heater holder for holding the heater;
Rotating around the holder while the inner surface is in contact with the heater
And a heat resistant film that
Do not let it adhere to the surface of the film opposite to the side where the heater is placed.
And heat-resistant film together with the heat-resistant film,
A heat fixing device for permanently fixing an unfixed image on a heated material.
In the above, the heater is the amount of heat generated in the non-passage area of the small size material to be heated.
Is smaller than the first heating element whose heat generation is higher than that of the passage area
The heating value of the heating material in the passing area is
A second heating element which is higher than the first heating element,
Provided upstream of the second heating element in the moving direction of the material to be heated.
A heat fixing device characterized in that