JPH07253731A - Heating device and image forming device - Google Patents

Abstract

PURPOSE:To restrain a temperature rise phenomenon at a paper non-passing part with the simple constitution of a means and to eliminate trouble caused by the temperature rise at the paper non-passing part by providing a heat radiating mechanism in a pressuring member. CONSTITUTION:A film pressuring roller 4 functioning as a rotating body for driving film 2 is constituted of a core shaft 4a made of iron or stainless steel and a roller part 4b consisting of a heat resistant rubber elastic body excellent in releasing property such as silicone rubber, which is externally provided on the shaft 4a. The heat radiating member 20 is connected to an end on the opposite side (anti-reference side) to the side of a one-side reference carrying base A of the core bar 4a of the roller 4. In such a case, aluminum excellent in heat conductivity is used for the member 20 in order to enhance a heat radiating effect. By providing the member 20, the heat accumulated at the paper non- passing part (c) when a small-size material to be recorded consecutively passes is conducted to the member 20 from the core bar 4a and diffused from the member 20. Therefore, a temperature difference between a paper passing part (b) and the paper non-passing part (c) is reduced and the temperature rise at the paper non-passing part is restrained.

Description

Detailed Description of the Invention

[0001]

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

More specifically, a heating device for introducing a member to be heated between a heating member and a pressure member to apply the heat energy of the heating member to the member to be heated, or a fixedly supported heating member is heat resistant. The pressure member is contacted via the film, and a member to be heated is introduced between the heat resistant film and the pressure member in the pressure contact nip portion and moved by moving the pressure contact nip portion together with the heat resistant film. The present invention relates to a heating device that applies heat energy of a pressure member to a member to be heated via a heat resistant film.

Further, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an image formed and carried by an appropriate image forming process means on a recording material such as a transfer material, a photosensitive paper or an electrostatic recording paper. To fix the image and modify the surface properties such as gloss,
The present invention relates to an image heating apparatus that performs hypothetical wear or the like, or an image forming apparatus including the image heating apparatus.

[0004]

2. Description of the Related Art For convenience, an image forming apparatus (image output apparatus) such as a copying machine, a printer, a facsimile, etc., which uses electrophotography, is used.
Image (toner image) formed and carried on the recording material in
An image heating and fixing device (image heating device) that heats and fixes the image on the surface of the recording material will be described as an example.

Conventionally, a heat roller type apparatus has been widely used as an image heating and fixing apparatus. This device is basically composed of a metal roller (heat roller) as a heating member having a heater inside, and a pressure roller having elasticity as a pressure member in pressure contact with the roller. The recording material is introduced into the section (fixing nip portion) and is nip-conveyed and passed between the pair of rollers, so that the toner image is heated and pressed by the heat of the heat roller and the pressure of the pair of rollers to form the recording material. It is to fix it.

On the other hand, the applicant of the present invention previously disclosed in Japanese Patent Laid-Open No. 63-313.
No. 182 / JP-A-2-157878, a thin heat-resistant film, and a heating member (hereinafter referred to as a heater) fixedly supported on one side of the film,
A film heating type heating device or an image heating device, which is arranged on the other surface side so as to face the heater and is composed of a pressure member for adhering a recording material to be image-fixed to the heater through a film. A fixing device was proposed.

The fixing operation in such a film heating type fixing device is carried out by passing the recording material together with the film to a fixing nip portion formed by pressing a heater and a pressing member with the film interposed therebetween. This is performed by heating the surface of the recording material on which the visible image is carried with a heater through a film to apply thermal energy to the unfixed toner image to soften and melt the toner.

Since such a film heating type fixing device can use a heater having a low heat capacity, the wait time can be shortened (quick start) as compared with the heat roller type device. Further, since the quick start can be performed, it is not necessary to preheat the heater at the time of non-printing operation, and power saving can be achieved in a comprehensive sense.

Further, the applicant of the present invention, regarding such a film heating type fixing device, when an endless belt-shaped film is used as a film, by suspending and driving the film with a margin, the heater in the process of rotating the film is heated. We have proposed an improved device that reduces the shift force along the length to simplify the film shift control means, and also reduces the drive torque to simplify the device, reduce the size, and reduce the cost. (Tensionless type,
JP-A-4-44075-44083, JP-A-4-440
Nos. 204980 to 204984).

[0010]

In the fixing device of the heating roller system or the fixing device of the film heating system as the heating device as described above, the heating roller or the heater as the heating member detects the temperature by the temperature detecting means such as a thermistor. The temperature is controlled to a predetermined temperature by supplying electricity so that the detected temperature is controlled to be constant.

In this case, a thermistor as a temperature detecting means is arranged at a heat roller portion or a heater portion where a recording material of any size, large or small, which can be used for passing paper through the apparatus, becomes a paper passing portion, and the heat The temperature of the roller portion or the heater portion is detected and fed back to the energization control circuit. That is, the energization of the heat roller and the heater is controlled so that the temperature of the sheet passing portion is maintained at a predetermined fixed fixing temperature based on the detected temperature of the sheet passing portion.

However, in a device having such a temperature control structure, a recording medium having a size smaller than a recording material of a maximum size, for example, B4 size or A3 size, which can be used for passing through the device, for example, B is used.
When a small size recording material such as 5 size paper or envelopes / postcards is continuously passed through the device, the non-sheet passing portion of the heat roller or the heater (the effective heat generation full length area of the heat roller or the heater and the small size passed sheet). The area (different from the size width of the recording material) generates heat with a predetermined amount of heat generation per unit length as in the portion corresponding to the paper passing portion, although heat is not consumed for heating the recording material, so that heat is stored. This causes a so-called non-sheet passing portion temperature rising phenomenon in which the temperature rises above the sheet passing portion.

Due to the temperature rise in the non-sheet passing portion, the pressure roller as a pressure member facing the heat roller and the heater in pressure contact has a temperature difference between the sheet passing portion corresponding portion and the non-sheet passing portion corresponding portion. Occurs. In particular, in the case of a so-called one-sided reference conveying system in which the paper passing of the recording material is introduced near the left end side or the right end side in the longitudinal direction of the heat roller or the heater, a portion corresponding to the paper passing portion of the pressure roller. In some cases, the temperature difference between the portion corresponding to the non-sheet passing portion is about 115 deg (° C.).

Such a temperature rise in the non-sheet-passing portion is caused when the next large-sized recording material is introduced and passed, and the portion corresponding to the non-sheet-passing portion during continuous feeding of the small-sized recording material is overheated. It causes uneven fixing.

Excessive temperature rise in the non-sheet passing portion due to continuous feeding of a small size recording material for a long time is caused by a heat roller, a heater, a pressure roller, other parts and a film heating type apparatus. Causes heat loss in the film, resulting in deterioration of durability.

In the film heating type apparatus, when the small-sized recording material is continuously fed, the film is twisted due to the temperature rise in the non-sheet feeding area. In the worst case, the film is twisted and the apparatus is It will be damaged. The occurrence of such film twist is remarkable in the above-mentioned tensionless type device.

The main factors that cause the film to be twisted are the difference in thermal expansion between the diameters of the portion corresponding to the paper passing portion and the portion not corresponding to the paper passing portion of the pressure roller, and the temperature dependence of the strength against the twist of the film (film thickness). Etc.), temperature characteristics of the film surface (inner surface) (change in friction coefficient with temperature, etc.), and all of these factors have temperature dependence.

The difference in thermal expansion between the diameter of the portion corresponding to the sheet passing portion and the portion corresponding to the non-sheet passing portion of the pressure roller is 100 deg.
The difference in outer diameter change is about 600 μm, which causes a difference in peripheral speed between the two parts, which causes film twist, and by increasing the film thickness, the strength against film twist due to temperature rise in the non-sheet passing area is increased. It is also known by the study of the present inventors that the number increases. Further, it has been found that lowering the temperature of the pressure roller or the temperature of the film at the portion corresponding to the non-sheet passing portion has a remarkable effect in preventing the occurrence of twist of the film.

As a solution to the temperature rise in the non-sheet passing portion, a method of providing a plurality of heating patterns of the heater and energizing only the paper passing area in accordance with the size of the non-recording material to be passed (Japanese Patent Laid-Open No. 3-1444)
No. 77, etc.), but there is a problem that the control method of the device becomes complicated and the cost increases.

Further, it is possible to lower the temperature of the non-sheet passing portion by increasing the heat conductivity in the longitudinal direction of the pressure member to improve the flow of heat from the non-sheet passing portion to the sheet passing portion. In the past, there has been no concrete specification of how much thermal conductivity is required as the performance of.

Therefore, the object of the present invention is to solve the above-mentioned problems due to the temperature rise in the non-sheet passing portion by making it possible to suppress the temperature rise phenomenon in the non-sheet passing portion in this type of heating device with a simple means structure. And

[0022]

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

(1) In a heating device for introducing a member to be heated between the heating member and the pressure member to apply the heat energy of the heating member to the member to be heated, a heat dissipation mechanism is provided in the pressure member. A heating device characterized by the above.

(2) A pressure member is brought into contact with a fixedly supported heating member through a heat resistant film, and a member to be heated is introduced between the heat resistant film and the pressure member in the pressure contact nip portion to heat the member. In a heating device for applying the heat energy of a pressure member to a heated member via a heat resistant film by moving the pressure contact nip portion together with a heat-resistant film, a heat dissipation mechanism is provided in the pressure member. And heating device.

(3) When the cross-sectional area of the pressing member is a and the heat radiation area outside the end of the heated member of the maximum size that can pass through the apparatus is b, the relationship of b ≧ 5.0a is obtained. The heating device according to (1) or (2), characterized in that

(4) The heating device according to (1) or (2), characterized in that the heat dissipation mechanism is cooled from the outside.

(5) The heating device according to (1) or (2), wherein the heat dissipation mechanism functions via the bearing of the pressing member.

(6) When the maximum size heatable member that can pass the paper is introduced into the apparatus to apply the heat energy, the heat radiation mechanism does not function. The heating device according to (1) or (2), wherein the heat dissipation mechanism functions only when energy is applied.

(7) The heating according to (1) or (2), characterized in that a member made of a material having a thermal conductivity of 0.04 cal / cm · sec · deg or more is used as the heat dissipation member used in the heat dissipation mechanism. apparatus.

(8) In a heating device for introducing a member to be heated between the pressing member and a pressing member having a rubber elastic layer in pressure contact with the member to apply thermal energy of the heating member to the member to be heated, The thermal conductivity of the rubber elastic layer of the pressing member is 2
0.9 × 10 ^-10 cal / cm · sec at 5 ° C
A heating device having a degree of deg or more and a hardness of 35 ° or less according to JIS-A.

(9) A pressure member having a rubber elastic layer is brought into pressure contact with a fixedly supported heating member via a heat resistant film, and a member to be heated is provided between the heat resistant film and the pressure member in the pressure contact nip portion. In the heating device for applying the heat energy of the heating member to the heated member through the heat resistant film by moving the pressure contact nip portion together with the heat resistant film, the rubber elastic layer of the pressure member is Thermal conductivity is
0.9 × 10 ^-3 cal / cm · sec at 25 ° C
A heating device having a degree of deg or more and a hardness of 35 ° or less according to JIS-A.

(10) The pressing member has a core inside, and the thermal conductivity of the core is 5.0 × 10 ⁻¹ ca at 25 ° C.
It is 1 / cm * sec * deg or more, The heating device as described in (8) or (9) characterized by the above-mentioned.

(11) The heating device according to (8) or (9), wherein the rubber elastic layer of the pressing member has different thermal conductivity in the direction orthogonal to the direction in which the member to be heated is conveyed.

(12) The rubber elastic layer of the pressing member is characterized in that its end has a lower thermal conductivity than other parts (8).
Alternatively, the heating device according to (9).

(13) Any one of (1) to (12), wherein the member to be heated is a recording material carrying an image and is an image heating device for heating the image of the recording material. The heating device according to.

(14) The image forming means for forming an image on the recording material, and the heating device according to any one of (1) to (12) are used to heat the image on the recording material from the image forming means side. An image forming apparatus provided as an image heating device for processing.

[0037]

By providing the heat radiating mechanism on the pressing member, the heat of the non-sheet passing portion is positively radiated and the temperature rise phenomenon of the non-sheet passing portion is suppressed.

When the heat radiating mechanism is cooled from the outside, or the cross-sectional area of the pressurizing member is a and the heat radiating area outside the end of the heated member of the maximum size that can be introduced into the apparatus is b, then b ≧ 5 .0a is obtained, or the heat radiation mechanism functions via the bearing of the pressure member, or the heat conductivity of the heat radiation member used in the heat radiation mechanism is 0.04c.
By using a member having a material of al / cm · sec · deg or more, the heat dissipation effect is improved, and the temperature rise phenomenon of the non-sheet passing portion is more effectively suppressed.

When the maximum size heatable member that can pass the paper is introduced into the apparatus to apply the heat energy, the heat radiation mechanism does not function, and the heat size smaller than that is introduced to apply the heat energy. When the maximum size member to be heated is passed through, the heat dissipation mechanism functions only to prevent unnecessary heating failure due to the temperature decrease of the pressure member, and it is also possible to reduce the size. The heat dissipation mechanism functions during the passage of the heated member to suppress the temperature rise of the non-sheet passing portion.

The pressing member is a pressing member having a rubber elastic layer, and the rubber elastic layer has a thermal conductivity of 0.9 × 10 ⁻¹⁰ cal / cm · sec · deg or more at 25 ° C. and a hardness. By setting JIS-A to 35 ° or less,
It is possible to improve the movement of heat in the longitudinal direction of the pressure member and to secure a predetermined pressure contact nip portion due to the rubber elasticity of the pressure member between the heating member and the temperature rise of the non-sheet passing portion. .

The thermal conductivity of the core of the pressing member should be 5.0 × 10 ⁻¹ cal / cm · sec · deg or more at 25 ° C., or the rubber elastic layer of the pressing member should have its thermal conductivity By making the heating member different in the direction orthogonal to the conveying direction, or by making the rubber elastic layer of the pressing member have a lower thermal conductivity at its end portion than the other portions, The heat transfer can be improved and the temperature rise in the non-sheet passing portion can be suppressed more effectively.

[0042]

【Example】

<Example 1> (Figs. 1 to 5) (1) Example of image forming apparatus Fig. 1 shows a schematic configuration of an example of the image forming apparatus. The image forming apparatus of this embodiment is a reciprocating platen type, a rotary drum type, a transfer type, and a process cartridge attaching / detaching type electrophotographic copying apparatus.

Reference numeral 100 denotes an apparatus casing, 101 denotes a reciprocating type document placing table made of a transparent plate member such as a glass plate disposed on an upper surface plate 102 of the apparatus casing.
The upper part is driven to reciprocate to the right a and the left a'in the drawing at a predetermined speed.

Reference numeral G denotes an original, which is placed on the upper surface of the original placing table 101 according to a predetermined placing standard with the image surface side to be copied facing downward, and by placing the original pressure plate 103 on the original and pressing it. Set.

Reference numeral 104 denotes a slit opening serving as a document illuminating section which is opened on the surface of the machine top plate 102 with the direction perpendicular to the reciprocating direction of the document placing table 101 (direction perpendicular to the paper surface) as the length.

The downward image surface of the document G placed and set on the document placing table 101 sequentially moves the slit openings 104 from the right side to the left side in the forward movement process of the document placing table 101 to the right a. The light L of the lamp 105 is passed through the slit opening 104 and the transparent original placing table 101 to be illuminated and scanned in the passing process, and the original surface reflected light of the illumination scanning light is reflected by the image element array 106 by the photosensitive drum. Image formation exposure is performed on the 107th surface.

The photosensitive drum 107 is coated with a photosensitive layer such as a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer, and is rotated in a clockwise direction indicated by an arrow b at a predetermined peripheral speed around a central support shaft 108. During the rotation process, the charging device 109 receives a uniform positive or negative charging process, and the uniformly charged surface is subjected to the image formation exposure (slit exposure) of the original image, so that the surface of the photosensitive drum 107 is formed. An electrostatic latent image corresponding to the image-exposed original image is sequentially formed.

This electrostatic latent image is sequentially visualized by a developing device 110 with toner made of resin or the like that is softened and melted by heating, and the toner image as the visualized image is provided with a transfer discharger 111 as a transfer portion. It moves to the part.

Reference numeral S denotes a cassette in which transfer material sheets P as recording materials are stacked and housed, the sheets in the cassette are fed out and fed one by one by the rotation of the feeding roller 112, and then the drum is moved by the registration rollers 113. When the leading edge of the toner image forming portion on 107 reaches the portion of the transfer discharger 111, the leading edge of the transfer material sheet P also arrives at the position between the transfer discharger 111 and the photosensitive drum 107 so that they both coincide with each other. It is returned and is synchronously fed.

Then, the toner images on the side of the photosensitive drum 107 are sequentially transferred by the transfer discharger 111 onto the surface of the fed sheet.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the photosensitive drum 107 by a separating means (not shown), and is guided to the image heating device (heat fixing device) 50 by the conveying device 114 to be carried. The unfixed toner image that has been subjected to heat fixing is discharged as an image formed product (copy) onto the discharge tray 117 through the discharge roller 116.

The surface of the photosensitive drum 107 after the image transfer is subjected to removal of adhered contaminants such as toner remaining after transfer by the cleaning device 118, and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion 120 in the apparatus main body 100.
In the case of the present example, the apparatus main body 10 including the four process devices of the photosensitive drum 107 as an image bearing member, the charging device 109, the developing device 110, and the cleaning device 118 together.
It is detachable and replaceable with respect to 0.

(2) Image Heating Device 50 FIGS. 2 and 3 are a horizontal cross-sectional model view and a vertical cross-sectional model view showing a schematic configuration of the image heating device 50. The image heating apparatus 50 of this example is disclosed in JP-A-4-44075 to 44083 and 4-20.
This is a tensionless type film heating type image heating apparatus disclosed in Japanese Patent Nos. 4980 to 204984.

In this type of device, at least part of the circumference of the film is always tension-free (a state in which no tension is applied), and the traveling movement of the film is obtained from the rotational driving force of the pressing member. Even with the same film heating type device, the control / mechanism for driving / running the film is simplified and the driving torque is simpler than that of the tension type in which tension is constantly applied all around the film to move the film in tension. Has the advantage that it can be significantly reduced.

Reference numeral 1 denotes a horizontally long stay made of heat-resistant resin, which serves as an inner surface guide member of an endless heat-resistant film (fixing film) 2 described below.

The endless heat resistant film 2 is fitted on the stay 1 including the heater 6 as a heating member. The inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heater 6 are larger than those of the film 2 by, for example, 3 mm.
The outer circumference of the stay 1 is loosely fitted to the stay 1 including the above.

The film 2 has a total thickness of 100 in order to reduce the heat capacity and improve the quick start property.
A single layer of PTFE, PFA, FEP, etc. with heat resistance, releasability, strength, durability, etc., or PTFE, PFA, FEP, etc. on the outer peripheral surface of polyimide, polyamide imide, PEEK, PES, PPS etc. A composite layer film coated with can be used. In this embodiment, a polyimide film having a total thickness of 60 μm in which PTFE is coated on the outer peripheral surface is used.

The heater 6 is a substrate 6a made of alumina or the like.
Along the length of the center of the surface of, for example, Ag / Pd
An electric resistance material (heating element) 6b such as (silver-palladium) is applied to the thickness of about 10 μm and a width of 1 to 3 mm by screen printing or the like, and glass, a fluororesin or the like is coated thereon as a protective layer 7.

Reference numeral 4 denotes a film pressure roller as a rotating body for driving the film 2 by forming the fixing nip portion N by sandwiching the film 2 with the heater 6, and a core shaft 4a of iron, stainless steel or the like, This shaft is composed of a roller portion 4b made of a heat-resistant rubber elastic body having a good mold release property such as silicon rubber, and the end portion of the cored bar 4a is driven in the counterclockwise direction by the drive means. Driven. When the pressure roller 4 is rotationally driven, the endless heat resistant film 2 is also rotationally driven in the clockwise direction shown by the arrow.

The pressure roller 4 of this example has a core metal 4a having an outer diameter of 10 mm, a silicone rubber layer having a length of 220 mm and a thickness of about 3 mm, which is coated with fluorine latex (GLS manufactured by Daikin).
213 mixed with FEP at 10 ωt%) 30 μm
Of the roller portion 4b having a hardness of 50 ° (Asker C hardness) which is coated and fired, and both ends of the core metal 4a are freely rotatably thrust to the device frame 17 through the bearings 15 and 16 as shown in FIG. The movement of the pressure roller 4 is prevented and held, and the power is transmitted from a drive means (not shown) to the drive gear 18 fixed to one end of the cored bar 4a to cause the pressure roller 4 to move in a predetermined direction at a predetermined peripheral speed. It is driven to rotate.

When the endless heat-resistant film 2 is not driven, most of the remaining portion, except for the portion sandwiched by the nip N between the heater 6 and the pressure roller 4, is tension-free. .

When the pressure roller 4 is rotationally driven, a moving force is applied to the film 2 at the nip portion N by a frictional force with the rotary pressure roller 4, and the film 2 has a speed substantially equal to the rotational peripheral speed of the pressure roller 4. The back surface of the film is driven to rotate clockwise while sliding on the heater 6 surface (= protective layer 7 surface). When the film is driven, the nip portion N and the nip portion N are
Tension is applied to the film only on the upstream side in the film moving direction and between the nip portion and the film inner surface guide portion near the nip portion.

In the state where the film drive and the heating layer 6b of the heater 6 are energized as described above, the recording material P carrying the unfixed toner T has the rotating film 2 at the nip portion N.
When the recording material P is introduced between the rotary pressing roller 4 and the rotary pressing roller 4 upward, the recording material P passes through the nip portion N together with the film 2 and is in contact with the back surface of the film at the nip portion N. The thermal energy of the heater 6 is applied to the recording material P via the film 2, and the toner image T is thermally fixed by the pressing force in the nip portion N.

In the heater 6, when a voltage is applied (power supply) across the longitudinal ends of the heating element layer 6b, the heating element layer 6b generates heat, the substrate 6a is heated, and the heater 6 having a low heat capacity.
The whole temperature rises and the temperature rises rapidly.

To control the temperature of the heater 6, the output of the thermistor 5 provided on the heater 6 is A / D converted and taken into the CPU 10, and based on this information, the triac 11 energizes the heating element layer 6b of the heater 6 AC. The voltage is controlled by controlling the power supplied to the heater by controlling the phase and wave number. 12
Is an AC power supply.

The apparatus of this embodiment is an apparatus configured to introduce the recording material P by the one-side reference conveyance system, and in FIG. 3, A is the one-side reference conveyance base line. The recording material of various sizes, small and large, has a side end portion on one side along the base line A.
Introduced into the interior.

The position of the thermistor 5 is always in the vicinity of the conveyance reference part so as to detect the temperature of the recording material sheet passing part in order to secure a stable fixing property, and the detected temperature of the thermistor 5 is lower than a predetermined set temperature. By controlling energization so that the heater 6 rises in temperature and, if it is high, the heater 6 is lowered in temperature, the heater 6 is adjusted to a constant temperature during fixing.

Reference numeral 13 is a main control circuit of the image forming apparatus,
The fixing operation is continuously executed during continuous printing by a plurality of image forming commands (print commands). In addition, the power supply to the heater 6 is turned off during the standby for waiting the print command, and the power supply to the heater 6 is started after the print command is issued by turning on the main switch.

(3) Heat Dissipation Mechanism In FIG. 3, 20 is a heat dissipation member connected to the end of the core metal 4a of the pressure roller 4 on the side opposite to the one side reference transport base line A side (hereinafter referred to as the anti-reference side). Is.

The heat dissipating member 20 in the apparatus of this embodiment is made of aluminum having good heat conductivity in order to enhance the heat dissipating effect. The shape is a disk with a wall thickness of 5 mm and a diameter of 30 mm.

Due to the presence of the heat radiating member 20, the heat to be stored in the non-paper passing portion c during continuous paper feeding of the small size recording material is conducted from the core metal 4a to the heat radiating member 20 so that the heat radiating member 20. The temperature difference between the sheet passing portion b and the sheet non-passing portion c is reduced and the temperature rise of the sheet non-passing portion is suppressed.

Concretely, the device of this embodiment provided with the heat dissipation member 20 as described above, and the heat dissipation member 2 from the device of this embodiment.
Measurement of the temperature rise of the pressure roller 4 at the time of continuous feeding of the small-sized recording material in both of the devices with 0 removed, and the film 2
Experiments were carried out on the twist of.

That is, the temperature of the heater 6 is controlled to 155 ° C., and an envelope (width 105 mm × length 241) is set as the recording material P.
mm) was continuously passed at a process speed of 11.4π mm / sec and a sheet interval of 296 mm, the temperature transitions of the paper passing portion b and the non-paper passing portion c of the pressure roller 4 were measured. The temperature was measured by pressing a thermocouple under the pressure roller with a pad.
The measurement point is 11m from the standard transport base line A on the paper passing side.
At m, the non-sheet passing side is 207 mm.

The results are shown in FIG. (A) is the result of the device of this embodiment equipped with the heat dissipation member 20, and (B) is
Is the result of the device with the heat dissipation member 20 removed.

In the apparatus of this embodiment equipped with the heat radiating member 20, the temperature difference ΔT between the paper passing portion b and the non-paper passing portion c of the pressure roller 4 is ΔT at the 40th continuous sheet passing as shown in (A). = 107de
It was g, and the twist of the film 2 did not occur.

On the other hand, in the device without the heat dissipation member 20,
As shown in (B), ΔT = 115 deg at the 40th sheet passing. In the experiment, if ΔT ≧ 110 deg, film 2
Wrinkles begin to appear on the surface and twist occurs.

That is, in the apparatus of this embodiment, the temperature rise in the non-sheet passing portion is suppressed. In the apparatus of this embodiment equipped with the heat dissipation member 20, the temperature rise of the non-sheet passing portion c is reduced because the recording material does not take heat energy during continuous feeding of the small recording material. The thermal energy accumulated in the pressure roller portion on the section side is transmitted to the heat dissipation member 20 through the core metal 4a,
This is because heat is dissipated. This is because the heat dissipation area is increased by attaching the heat dissipation member 20.

When the cross-sectional area of the pressure roller 4 is a and the heat radiation surface area outside the end of the maximum size recording material on the opposite reference side is b, the heat radiation surface area b in this embodiment is b = 13.3a. .

In FIG. 5, the heat radiation cross section b is b = 2.6a, 3.
6a, 8.6a, 13.3a pressure roller temperature difference is plotted, from this figure, b ≧ 5.0a as a condition to satisfy the pressure roller temperature difference 110 deg that does not cause film twist can get.

In this embodiment, aluminum was used as the material of the heat dissipation member 20, but the better the heat dissipation member is, the greater the effect is, and the heat conductivity is 0.04 cal / cm.
If it is at least sec · deg (° C.), it is effective in reducing the pressure roller temperature difference ΔT.

Although the shape of the heat radiating member 20 is a disk shape in this embodiment, it goes without saying that a fin shape or the like is effective as long as the heat radiating area can be increased.

As described above, the apparatus of this embodiment is composed of the pressure roller 4
By disposing the heat dissipation mechanism 20 on the core metal 4a, the heat dissipation mechanism 20 dissipates the heat of the non-paper passing part c of the pressure roller 4 when the temperature of the non-paper passing part is increased by the continuous passing of the small-sized recording material. Let
It has the effect of reducing the temperature gradient between the paper passing portion b and the non-paper passing portion c, that is, the effect of suppressing the temperature increase of the non-paper passing portion, prevents the occurrence of film twist, and raises the temperature of the non-paper passing portion and It is possible to prevent the fixing failure, the paper passing failure, and the heat loss of the device such as the film due to the twist of the film.

<Embodiment 2> (FIGS. 6 and 7) In this embodiment, the external cooling device 2 for further positively cooling the heat dissipation member 20 of the device of the embodiment 1 as shown in FIG.
1 is provided to enhance the heat dissipation effect. As a result, the temperature rise in the non-sheet passing portion can be further reduced.

In this embodiment, an electric fan is used as the external cooling device 21, and the heat radiating member 20 is cooled by air. The cross section of the air passage 22 for air-cooling the heat dissipation member 20 is 10 mm x 5
The rectangle is 0 mm, and the electric fan 21 is attached.

Under the same conditions as in the experiment conducted in Example 1 using the heating device having the above-mentioned configuration, the temperature rise of the pressure roller 4 and
An experiment was conducted on the twist of the film 2.

As can be seen from the result of FIG. 7, the number of continuous sheets of the envelope is 40, the temperature difference ΔT between the sheet passing portion b and the non-sheet passing portion c of the pressure roller 4 is ΔT = 97 deg, and the fixing is performed. The twist of the film 2 did not occur.

The reason why ΔT was smaller than that in Example 1 is that
This is because the amount of heat dissipated from one heat dissipating member 20 is increased by cooling the heat dissipating member 20 with air.

In this embodiment, the heat radiating member 20 is always air-cooled. However, when the maximum size recording material is passed, it is not air cooled, but only when the small size recording material is passed. It can also be controlled.

<Embodiment 3> In this embodiment, the pressure roller bearing 15 on the anti-reference side is made of a material having high thermal conductivity in place of the heat dissipating member 20 in the apparatus of Embodiment 1, so that pressure is applied. The thermal energy accumulated in the non-sheet passing portion c of the roller 4 is released to the heating device frame 17 or the main body frame (not shown) via the bearing 15.

As a result, it is not necessary to dispose the heat dissipation member 20 newly, so that it is possible to manufacture at low cost.
In this embodiment, the bearing 15 is made of ceramic (alumina) having high thermal conductivity.

Under the same conditions as in the experiment conducted in Example 1 using the heating device having the above-mentioned structure, the temperature rise of the pressure roller 4 and
As a result of an experiment on the twist of the fixing film,
Experimental results almost similar to those of Example 1 were obtained.

The heating device of this embodiment can reduce the temperature rise of the non-sheet passing portion when passing a small-sized recording material, prevent the fixing film 2 from being twisted, and prevent the fixing film 2 from being twisted. It is possible to prevent paper feeding failure and damage to the heating device that causes the fixing film to be twisted. Also, the device frame 17
Alternatively, since the main body frame also serves as a heat dissipation member, there is an advantage that it can be manufactured at low cost without increasing the number of parts.

<Embodiment 4> (FIG. 8) In this embodiment, the maximum size recording material is obtained by attaching the heat radiating member 20 to the end of the pressure roller core metal 4a on the side opposite to the reference side in the apparatus of the first embodiment. In order to prevent fixing failure due to an unnecessary temperature decrease on the anti-reference side of the pressure roller during paper passing, the heat radiating member 20 is brought into contact with the core metal 4a only when the small size recording material is passed, and the maximum size recording is performed. When the material is passed, it is arranged so as not to contact the core metal 4a.

In the experiment, when the maximum size recording material is passed with the heat radiating member 20 attached to the end of the pressure roller core metal 4a on the side opposite to the reference side, the heat radiating member 20 radiates heat to the pressure roller. It was confirmed that the temperature on the side opposite to the reference surface of No. 4 became lower than the temperature on the reference side, and fixing failure occurred on the side opposite to the reference side.

In this embodiment, as shown in FIG. 8, the heat radiating member 20 is moved by the moving means 2 with respect to the end portion of the pressure roller core metal 4a opposite to the reference side.
3 is used as a movable member that can be brought into and out of contact with the recording medium P, and the size of the recording medium P introduced into the apparatus 50 is detected by the recording medium size sensor 25. When it is detected that the size is small, the regulator 2
4, the moving means 23 and the heat radiating member 20 are connected to the pressure roller core metal 4a.
When the maximum size is detected, the heat dissipation member 20 is kept in non-contact with the pressure roller core metal 4a.

Regarding the temperature rise of the pressure roller and the twisting of the fixing film during the continuous feeding of a small size recording material (envelope) under the same conditions as the experiment conducted in Example 1 by using the heating device having the above-mentioned constitution As a result of conducting the experiment of Example 1,
Similar experimental results were obtained. Further, as a result of air-cooling the heat dissipation member 20 by the same method as in Example 2, the same experimental result as in Example 2 was obtained.

In the heating apparatus of this embodiment, when the maximum size recording material is passed, the pressure roller core metal 4a and the heat radiating member 20 are kept in non-contact with each other and the heat radiating member 20 is placed on the anti-reference side. It is possible to prevent the fixing roller from twisting without causing the fixing failure on the non-reference side of the pressure roller 4 due to the arrangement, and to reduce the temperature rise of the non-sheet passing portion when passing the small size recording material. In addition, it is possible to prevent fixing failure due to twisting of the fixing film, paper feeding failure, and breakage of the heating device in which the fixing film is broken.

<Embodiment 5> (FIG. 9) In this embodiment, as in the case of Embodiment 4, the heat dissipation member 20 is attached to the end of the pressure roller core metal 4a on the side opposite to the reference side so that the maximum size recording material can be passed. In order to prevent improper fixing due to unnecessary temperature drop on the non-reference side of the pressure roller at the time of paper, the thermal expansion of the core metal 4a is used to raise the heat dissipation member 20 so that the non-paper passage portion rises when a small size recording material is passed. The core metal 4a is brought into contact with the core metal 4a only when heated, and is kept out of contact with the core metal 4a when the maximum size recording material is passed.

In the heating device of this embodiment, as shown in FIG. 9, the heat radiating member 20 is arranged in non-contact with the core metal 4a. The spacing α between the core metal 4a and the heat dissipation member 20 is about 0.4 mm,
The core metal 4a and the heat dissipation member 20 are arranged so as to come into contact with each other due to thermal expansion of the core metal 4a when the core metal temperature reaches about 120 ° C.

Regarding the temperature rise of the pressure roller and the twisting of the fixing film at the time of continuously passing a small-sized recording material (envelope) under the same conditions as the experiment conducted in Example 1 by using the heating device having the above-mentioned constitution As a result of conducting the experiment of Example 1,
Similar experimental results were obtained. Further, as a result of air-cooling the heat dissipation member 20 by the same method as in Example 2, the same experimental result as in Example 2 was obtained.

In the heating apparatus of this embodiment, when the maximum size recording material is passed, the pressure roller core metal 4a and the heat radiating member 20 are kept in non-contact with each other and the heat radiating member 20 is placed on the anti-reference side. The fixing roller 4 does not cause fixing failure on the anti-reference side of the pressure roller 4 due to the disposition, and the temperature rise of the non-sheet passing portion can be reduced when recording a small size recording material. Fixing failure due to film twist, paper passing failure,
It is possible to prevent the heating device from being damaged when the fixing film is broken.

<Embodiment 6> In this embodiment, the thermal conductivity of the elastic layer 4b of the pressure roller 4 is about 0.6 × 10 ⁻³ cal / cm · sec.
Although the silicone rubber was deg, the one whose thermal conductivity was raised to 10 × 10 ⁻³ cal / cm · sec · deg was used.

That is, according to the study by the present inventors, in order to expect the minimum necessary effect for increasing the temperature of the non-sheet passing portion, the thermal conductivity of the silicone rubber is 0.9 × 10 ⁻³ cal / cm · sec.
-It has been found that it is preferable to set it to deg or more.

As a method of increasing the thermal conductivity of silicone rubber, it is considered to disperse particles having good thermal conductivity in silicone rubber, and examples thereof include alumina, aluminum nitride, and quartz. Then, magnesium oxide is dispersed.

By the way, the more the filler is added, the higher the thermal conductivity of the silicone rubber becomes, but at the same time, the hardness of the rubber also becomes higher, so that it becomes difficult to secure the nip portion N as a heating device. This is not preferable because it causes a decrease in fixing ability. Therefore, it is necessary to suppress the hardness of the rubber to a certain value or more, and in the study by the present inventors, it was concluded that JIS-A should be 35 ° or less at the maximum. In this embodiment, 28 ° rubber is used.

By using a pressure roller in which the rubber has a high thermal conductivity in the longitudinal direction of the roller as in this embodiment, it is possible to increase the temperature rise in the non-sheet passing area when a small size recording material is continuously fed. Since the flow of heat from the non-sheet passing portion c of the pressure roller 4 to the sheet passing portion b is improved, it is possible to obtain the effect of leveling the temperature unevenness in the longitudinal direction of the pressure roller.

In the apparatus of the first embodiment, the pressure roller 4 having the increased thermal conductivity of the present embodiment is used as the pressure roller 4 (the heat radiating member 20 is not provided), and the small size is obtained under the same conditions as the first embodiment. As a result of an experiment conducted on the temperature rise of the pressure roller and the twisting of the fixing film during the continuous passage of the recording material (envelope), the final reaching temperature of the non-sheet passing portion c of the pressure roller 4 is 208 ° C. Temperature difference ΔT between the paper passing portion c and the paper passing portion b
Was ΔT = 103 ° C., which satisfied the heat resistant temperature of the pressure roller and did not twist the film.

As described above, in this embodiment, the thermal conductivity of the silicone rubber layer 4b of the pressure roller 4 is 0.9 × 10 ⁻³ ca.
By setting the rubber hardness to 1 / cm · sec · deg or more and the rubber hardness to 35 ° or less, it is possible to suppress the excessive temperature rise of the non-sheet passing portion c, and
We were able to secure the fixability above the required minimum.

<Embodiment 7> In the pressure roller of the heating apparatus of this embodiment, the silicone rubber forming the roller elastic layer 4b has a thermal conductivity of 0.9 × 10 ⁻³ cal / cm · sec · de.
1.0 × 10 ^-3 cal / cm · sec · de over g
g, rubber hardness is set to 28 ° of 35 ° or less according to JIS-A,
In order to further improve the thermal conductivity in the longitudinal direction, the roller core metal 4a has a thermal conductivity of 5.0 × 10 ⁻¹ cal / cm · se.
c · deg Al 6063 alloy is used. The other configuration of the heating device is the same as that of the sixth embodiment.

Conventionally, stainless steel has been widely used for the core metal 4a of the pressure roller 4, but this is selected from the viewpoint of strength and price, and the thermal conductivity of the roller is not taken into consideration. There wasn't. However, in the experiments conducted by the present inventors, the use of a core bar 4a having a high thermal conductivity has a dramatic effect in reducing the temperature unevenness of the roller 4 when the temperature of the non-sheet passing portion is raised. The thermal conductivity of gold 4a is 5.0
It was concluded that it is necessary to have a density of x10 ^-1 cal / cm · sec · deg or more.

In this embodiment, aluminum is used for the core metal 4a, but there is no particular problem in strength. Also core metal 4
As the material of a, a high thermal conductivity substance such as duralumin copper, gold, silver or the like may be used.

When an experiment for raising the temperature of the non-sheet passing portion was conducted with the heating device using the roller 4 of this embodiment, the highest temperature reached in the non-sheet passing portion of the pressure roller was 196 ° C. The temperature difference between the parts was ΔT = 92 ° C., and higher effects could be obtained as compared with Example 6.

<Embodiment 8> (FIG. 10) As shown in FIG. 10, the pressure roller 4 of the heating device according to this embodiment includes both end portions 4A and 4A of the roller 4 and the other portion 4 thereof.
In B, the thermal conductivity of the elastic layer 4b is different. Here, the end portions 4A and 4A are portions corresponding to non-image portions when the recording material is passed.

The elastic layer 4b is entirely made of, for example, silicone rubber, and the portion 4B has a thermal conductivity of 1.0 × 10 ⁻³ cal / cm · sec · de.
Thermal conductivity of the parts 4A and 4A is 0.6 × 10 ⁻³ cal / cm · sec · de.
g.

The heat conduction of the silicone rubber can be controlled by adding a filler to the silicone rubber. However, in the roller of this embodiment, if the amount of the filler is different between the portion 4B and the portions 4A and 4A in the integral silicone rubber, it is different. By doing so, the thermal conductivity is made lower than the others. That is, the thermal conductivity of the portions 4A and 4A can be reduced by reducing the amount of good thermal conductive particles dispersed in the end portions 4A and 4A as compared with the other portions.
I changed it to B. This can also be done by changing the type of filler.

As for the structure of the roller, the elastic layer 4b may be formed of integral rubber as described above, but the portion 4B
After forming the parts 4A and 4A as separate members and the part 4B as a roller on the core metal 4a first, the parts 4A and 4A are formed from both ends.
You may put in A. Further, in this case, the parts 4B and the parts 4A and 4A may be made of completely different materials.

When a roller having a high thermal conductivity is used as the silicone rubber of the rollers as in the sixth and seventh embodiments, the heat escape from the end of the roller is larger than that of a roller having a low thermal conductivity, and the nip is high. Since the temperature in the portion N is extremely low at the edge portion, defective fixing occurs at the edge portion of the image. However, as in the present embodiment, the thermal conductivity of the pressure roller is low at the end portions 4A and 4A and is high at the other portions 4B, so that the temperature gradient of the pressure roller with respect to the temperature rise of the non-sheet passing portion. Can be reduced, and the heat radiation amount at the end can be reduced.

<Others> FIGS. 11 to 13 show other examples of the configuration of the film heating type heating device.

In FIG. 11, the first film suspending roller 31, the second film suspending roller (tension roller) 32, and the heater 6 are provided in parallel with each other by three members 31.3.
An endless belt-shaped heat resistant film 2 is stretched between the two and six, and the pressure roller 4 is arranged by sandwiching the film 2 against the heater 6 and placing the heat resistant film 2 into the first film. The suspension roller 31 or the pressure roller 4 is rotatably conveyed as a film driving roller. When the first film suspension roller 31 is used as a driving roller, the pressure roller 10 is driven to rotate. Reference numeral 8 is a heat-resistant heat-resistant heater holder.

In FIG. 12, the heat-resistant film 2 in the form of a dress belt is suspended and stretched between the heater 6 and the two members 6 and 33 of the film suspension roller 33, and the film 2 is sandwiched between the pressure roller and the pressure roller. 4 is arranged in pressure contact with the heater 6, and the heat-resistant film 2 is attached to the film suspension roller 33 or the pressure roller 4
Is used as a film driving roller to be rotationally conveyed. When the film suspension roller 33 is used as a driving roller, the pressure roller 10 is driven to rotate.

The heat-resistant film 2 shown in FIG. 13 is not an endless belt-shaped one but a roll-wound long end film which is used as a feeding shaft 34.
From the side to the take-up shaft 35 side via the heater 6, the pressure roller 4 is pressed against the heater 6 with the film 2 interposed therebetween, and the film 2 is run and conveyed to the take-up shaft 35 side. . The pressure roller 10 may be a film driving roller.

The present invention can be applied to any of the devices shown in FIGS. 11 to 13 to obtain the same effects as those of the first to eighth embodiments.

The above is the film heating type heating device or the image forming apparatus equipped with the heating device as an image heating device. However, the present invention is also applicable to a heating roller type heating device and an image forming device equipped with the heating device. Apply the temperature rise to the non-sheet passing area,
The problem caused by the temperature rise can be reduced and solved.

[0125]

As described above, according to the present invention, the heating device for introducing the member to be heated between the heating member and the pressing member to apply the thermal energy of the heating member to the member to be heated is not provided. The temperature rise phenomenon of the sheet passing portion can be suppressed by a simple means configuration, the above-mentioned problems caused by the temperature rise of the non-sheet passing portion can be solved, and the intended purpose is well achieved.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view showing the schematic configuration of the image heating device (image heating fixing device) used.

[Fig. 3] Vertical section model

FIG. 4A is a graph showing the number of sheets of recording material passed by the heating apparatus of Example 1 and a temperature rise transition graph of the sheet passing portion and the sheet non-passing portion of the pressure roller, and FIG. 4B is for the apparatus of the comparative example. Same graph

FIG. 5 is a correlation graph of the heat radiation surface area of the pressure roller and the temperature difference ΔT of the pressure roller.

FIG. 6 is a schematic vertical sectional view of the image heating apparatus according to the second embodiment.

FIG. 7 is a graph showing the transition of the number of recording materials passed through the apparatus and the temperature rise transitions of the pressure roller between the paper passing portion and the non-paper passing portion.

FIG. 8 is a schematic vertical sectional view of the image heating apparatus according to the fourth embodiment.

FIG. 9 is a schematic vertical sectional view of an image heating apparatus according to a fifth embodiment.

FIG. 10 is an explanatory diagram of a structure of a pressure roller of the image heating apparatus according to the eighth embodiment.

FIG. 11 is a schematic view of another configuration example of a film heating type heating device (No. 1).

FIG. 12 is a schematic view of another configuration example of the film heating type heating device (Part 2).

FIG. 13 is a schematic view of another configuration example of the film heating type heating device (No. 3).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stay (film inner surface guide member) 2 Fixing film 4 Pressure roller (pressure member) 4a Pressure roller core metal 4b Heat resistant cutting layer 5 Thermistor 6 Heater (heating member) 6a Heater substrate 6b Heating element layer 7 Protective layer 10 CPU 11 TRIAC 15/16 Pressure roller bearing 17 Device frame 18 Pressure roller drive gear 20 Heat dissipation member 21 Electric fan 22 Air passage 25 Paper size detection sensor

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoji Tomoyuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuo Kishino 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non non corporation

Claims (14)

[Claims] 1. A heating device for introducing a member to be heated between a heating member and a pressure member to apply heat energy of the heating member to the member to be heated, wherein a heat dissipation mechanism is provided in the pressure member. A heating device characterized by. 2. A heat-resistant member, wherein a pressure member is brought into contact with a fixedly supported heating member via a heat-resistant film, and a member to be heated is introduced between the heat-resistant film and the pressure member in the pressure contact nip portion. In a heating device for applying the heat energy of a pressure member to a member to be heated through a heat resistant film by moving the pressure contact nip portion together with the film, a heat dissipation mechanism is provided in the pressure member. Heating device. 3. The relation of b ≧ 5.0a is obtained, where a is the cross-sectional area of the pressing member and b is the heat radiation area outside the end of the heated member of the maximum size that can be passed through the apparatus. The heating device according to claim 1 or 2, characterized in that. 4. The heating device according to claim 1, wherein the heat radiation mechanism is cooled from the outside. 5. The heating device according to claim 1 or 2, wherein the heat dissipation mechanism functions via a bearing of the pressing member. 6. The heat radiating mechanism does not function when heat energy is applied by introducing a maximum size heated member into the apparatus, and heat energy is increased by introducing a size smaller heated member. The heating device according to claim 1 or 2, wherein the heat dissipation mechanism functions only when the heat is applied. 7. The heating device according to claim 1, wherein a member made of a material having a thermal conductivity of 0.04 cal / cm · sec · deg or more is used as the heat dissipation member used in the heat dissipation mechanism. 8. A heating device for introducing a member to be heated between a pressing member and a pressing member having a rubber elastic layer in pressure contact with the pressing member to apply thermal energy of the heating member to the heating member, The thermal conductivity of the rubber elastic layer of the pressure member is 25 ° C.
At 0.9 × 10 ^-10 cal / cm · sec · de
A heating device having a hardness of g or more and a hardness of 35 ° or less according to JIS-A. 9. A pressure member having a rubber elastic layer is brought into pressure contact with a fixedly supported heating member via a heat resistant film, and a member to be heated is provided between the heat resistant film and the pressure member in the pressure contact nip portion. In the heating device for introducing the heat energy of the heating member to the heated member through the heat resistant film by moving the pressure contact nip portion together with the heat resistant film, the heat of the rubber elastic layer of the pressure member is applied. Conductivity is 25 ℃
At 0.9 × 10 ^-3 cal / cm · sec · deg
Above, and the hardness is 35 degrees or less according to JIS-A. 10. The pressing member has a core inside, and the thermal conductivity of the core is 5.0 × 10 ⁻¹ cal / 25 ° C. at 25 ° C.
The heating device according to claim 8 or 9, wherein the heating device is at least cm · sec · deg. 11. The heating device according to claim 8, wherein the rubber elastic layer of the pressing member has different thermal conductivities in a direction orthogonal to the direction in which the member to be heated is conveyed. 12. The heating device according to claim 8, wherein the rubber elastic layer of the pressing member has a lower thermal conductivity at its end portion than at other portions. 13. The image heating apparatus according to claim 1, wherein the member to be heated is a recording material having an image carried thereon, and the image heating device heat-processes the image of the recording material. Heating device. 14. An image forming means for forming an image on a recording material, and the heating device according to claim 1 for heating the image on the recording material from the image forming means side. An image forming apparatus provided as an image heating device.