JP2003208049A - Heat fixing device and image forming apparatus using the same - Google Patents

Abstract

(57) [Problem] To reduce the temperature rise in the non-sheet-passing portion of the heating roller during continuous sheet feeding, secure the time required for heating and melting the toner necessary for increasing the fixing speed, and achieve high-speed fixing. And a heat fixing device. SOLUTION: A heating means 1 for heating while conveying an image carrier 24 to which an unfixed toner image 25 is transferred, and a pressurizing means 2 for pressing the image carrier 24 toward the heating means side,
In a heating and fixing device for fixing the toner image 25 on the image carrier 24 by heating and pressing, the width of the heating area of the heating means 1 is longer than the width of the image carrier 24, It is characterized in that a heat radiating means 3 is provided which comes into contact with a non-contact portion not in contact with the image carrier 24 and absorbs heat of the non-contact portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine and the like, which uses electrophotography, and more particularly to a heat fixing device for the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a heat fixing device used in a color printer or a color copying machine has two rollers each having a heater inside and a surface coated with an elastic layer, that is, a heating roller and a heating roller. A roller fixing method in which a nip portion is formed by a pressure roller, and a sheet on which an unfixed toner image is formed is nipped and conveyed while being fixed, and one of a heating roller and a pressure roller is used as a belt and one roller is used. A belt fixing method has been widely adopted in which a part of a belt is wound around and a nip portion for melting toner is formed.

[0003]

However, in order to increase the printing speed, both types have the following two problems, and it is difficult to reduce the size. One is the problem of out-of-plane deformation of the sheet due to the temperature rise of the non-sheet passing portion of the heating roller during continuous sheet passing. When a heater is built in as a heating source, the length of the heater is generally set to be 5 to 10 mm longer than the width of the paper in order to equalize the temperature distribution in the longitudinal direction of the roller during standby in consideration of heat radiation from the roller end. . For this reason, in the non-sheet passing portion of the roller in the continuous sheet passing, heat is not taken away by the sheet passing, so that the temperature becomes higher than that in the central sheet passing portion. The amount of temperature rise in the non-sheet passing portion increases as the sheet speed increases. This is because the amount of heat generated by the heater increases as the speed of paper passing increases. As a result, due to the difference in thermal expansion amount due to the temperature rise of the non-sheet passing portion, the outer diameter becomes uneven at the central portion and the end portion of the heating roller, which causes the problem that the paper has wavy out-of-plane deformation. is there.

To solve this problem, two heaters are provided inside the roller, one for heat generation at the center of the roller (paper passing portion) and one for heat generation only at the end portion (non-paper passing portion). There are methods for controlling the amount of heat generated, but since this method increases the size of the apparatus, it is used only for large-sized printers and copiers, which hinders downsizing of the fixing device.

The second problem is that of securing the time for heating and melting the toner, which is necessary for increasing the printing speed. That is, in order to increase the fixing speed, it is necessary to secure the heating and melting time of the toner, and for that purpose, how to enlarge the contact portion in contact with the toner becomes a problem.
The roller fixing method and the belt fixing method have the following problems.

In order to increase the contact portion in the roller fixing method, there is a method of decreasing the hardness of the heat resistant rubber which is the elastic layer of each roller or increasing the roller diameter. But,
When the hardness of the rubber is reduced, the wear resistance of the rubber itself is reduced and the compression set is increased, resulting in a reduction in the life of the roller itself. If the diameter of the roller is increased, not only the size of the apparatus is increased but also the heat capacity of the roller itself is increased, which causes an increase in warm-up time and an increase in power consumption. Therefore, there is a limit in improving the life of the fixing device and reducing the size thereof.

On the other hand, in the case of the belt fixing method, the nip portion for melting the toner is secured by winding a part of the belt around one roller.
When the amount of winding the belt around the roller is increased, the paper curls at the nip portion. In particular, with thin paper having a basis weight of 65 g / m ² or less, curling causes the paper to jam around the heating roller due to curling. Therefore, it is easier to secure the nip portion than the roller fixing method, but as in the roller method, it is necessary to increase the heating roller diameter in order to increase the speed, and there is a limit to downsizing.

As described above, in the conventional roller fixing system and belt fixing system, the out-of-plane deformation of the paper occurs as the speed increases, and there is a problem in downsizing of the apparatus.

An object of the present invention is to solve the above drawbacks of the prior art and to provide a compact and high-speed fixing device and an image forming apparatus using the same.

[0010]

In order to achieve the above-mentioned object, the present invention provides a heating means such as a heating roller for heating an image carrier such as a sheet on which an unfixed toner image is transferred while conveying the same, and a heating means such as the image. The present invention is intended for a heat fixing device that includes a pressure unit such as a pressure belt that applies pressure to the heating unit side to fix the toner image on the image carrier by heating and pressure.

In the first means of the present invention, the heating area width of the heating means is longer than the maximum lateral width of the image carrier to be used, and the non-contact portion of the heating means which is not in contact with the image carrier. It is characterized in that a heat radiating means for contacting with and absorbing the heat of the non-contact portion is provided.

The second means of the present invention is preheating for preheating the image carrier on which the unfixed toner image has been transferred, upstream of the nip portion between the heating means and the pressure means in the image carrier conveying direction. A member is arranged, and the heating region width of the heating means is longer than the maximum lateral width of the image carrier to be used, and a part of the preheating member is present in the non-contact part of the heating means that does not contact the image carrier. It is characterized in that the toner image and the image carrier before contact are preheated by the contact and absorption of heat from the non-contact portion.

The third means of the present invention is preheating for preheating the image carrier on which the unfixed toner image has been transferred, upstream of the nip portion between the heating means and the pressure means in the image carrier conveying direction. A member is arranged, and a part of the preheating member comes into contact with the pressing means, absorbs heat of the pressing means, and preheats the toner image before fixing and the image carrier by the heat. To do.

A fourth means of the present invention is preheating for preheating the image carrier on which the unfixed toner image has been transferred, upstream of the nip portion of the heating means and the pressure means in the image carrier conveying direction. A member is arranged, and the heating region width of the heating means is longer than the maximum lateral width of the image carrier to be used, and a part of the preheating member is present in the non-contact part of the heating means that does not contact the image carrier. In contact with each other, the pressurizing means also has a heat source, and the other part of the preheating member comes into contact with the pressurizing means, absorbs the heat of the non-contact portion and the pressurizing means, and absorbs the heat. It is characterized in that the toner image before fixing and the image carrier are preheated.

A fifth means of the present invention is the fourth means, further comprising a contacting / disconnecting means for contacting / separating a part of the preheating member in contact with the non-contact portion with respect to the non-contact portion. , A part of the preheating member is separated from the non-contact part by the separating / connecting means, and the preheating member is heated by the heat from the pressurizing means side,
At the time of continuous fixing, a part of the preheating member is brought into contact with the non-contact part by the separating / contacting means, and the preheating member is heated by the heat from the non-contact part of the pressurizing means and the heating means. It is characterized by that.

A sixth means of the present invention is any one of the second means, the fourth means and the fifth means, wherein the heating means is in contact with the image carrier at substantially the central portion in the axial direction of the heating means. There is a side contact portion, the non-contact portion is provided on both sides of the heating means side contact portion, and a part of the preheating member comes into contact with the non-contact portions on both sides thereof, respectively. .

According to a seventh aspect of the present invention, in any one of the second to sixth means, the preheating member has a tunnel shape, and the image carrier passes through the inside of the preheating member. It is characterized by that.

According to an eighth aspect of the present invention, in any one of the second to seventh means, a radiation fin is provided on a surface of the preheating member facing the image carrier. It is a thing.

According to a ninth aspect of the present invention, in any one of the second to eighth aspects, a black coating film is formed on the surface of the preheating member facing the image carrier. It is a feature.

The tenth means of the present invention is characterized in that, in any one of the second means to the ninth means, the preheating temperature by the preheating member is equal to or higher than the glass transition point of the toner.

According to an eleventh means of the present invention, in the image forming apparatus, the heat fixing device according to any one of the first means to the tenth means is used as a transfer device and an image carrier discharge on a conveying path of the image carrier. It is characterized in that it is provided between the devices.

[0022]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fixing device according to the first embodiment, FIG. 2 is a schematic configuration diagram of an electrophotographic device using the fixing device, and FIG. 3 is a perspective view of a preheating member used in the fixing device.

First, the outline of the electrophotographic apparatus according to the present invention will be described with reference to FIG. As shown in the figure, a drum-shaped intermediate transfer device 11 is arranged in the substantial center of the electrophotographic apparatus, and a belt-shaped photosensitive device 12 and transfer device 1 are provided around the drum-shaped intermediate transfer device 11.
3, sheet peeling means 14, intermediate transfer device cleaning means 15 and the like are arranged.

A charger 16, a photoconductor cleaning means 17, an afterimage removing means 18 and the like are arranged around the photosensitive device 12. Developing device 19K containing toner of four different colors
(Black), 19Y (yellow), 19M (magenta),
19C (cyan) is overlapped and disposed below the exposure means 20, and below the exposure means 20, a paper holding means 21 on which paper (image carrier) 24 is stacked and a paper supply device 22. The fixing device 10 and the paper discharge device 23 are arranged above the electrophotographic apparatus.

In this structure, the charger 16 uniformly charges the surface of the photosensitive device 12. Next, exposure is performed in dot units by the exposure means 20 based on the information of the image and characters by a personal computer, an image scanner, etc.
An electrostatic latent image is formed on the surface of the.

Thereafter, the electrostatic latent image is formed on the developing devices 19K and 19K.
The toner is supplied by any one of Y, 19M, and 19C and is developed, so that the toner is visualized as a toner image and is conveyed to the first transfer position T1. At the first transfer position T1, the toner image is transferred onto the surface of the intermediate transfer device 11 due to the potential difference between the photosensitive device 12 and the intermediate transfer device 11 supplied from a power source (not shown).

After passing the first transfer position T1, the potential of the surface of the photosensitive device 12 is dropped below a certain level by light irradiation by the afterimage removing means 18, and the electrostatic latent image is erased. Further, the photoconductor cleaning means 17 removes the toner left untransferred at the first transfer position T1 and prepares for the formation of the next toner image.

By repeating the above steps a required number of times, toner images of respective colors are formed on the surface of the intermediate transfer device 11 in an overlapping manner. Thereafter, the toner image is transferred to the second transfer position T2 by the transfer device 13 and the paper supply device 22 by the paper holding unit 2.
It is collectively transferred to the paper (image carrier) 24 supplied from the sheet 1. The paper 24 to which the toner image is transferred is the paper peeling means 1
4 is peeled off from the intermediate transfer device 11, and the fixing device 10
The toner image is fixed on the paper and is conveyed to the paper discharge device 23.
Is discharged in.

As shown in FIG. 1, the fixing device 10 comprises a heating roller 1, a pressure belt 2, a preheating member 3, a peeling means 4, a driving roller 6, a driven roller 7 and the like.

The heating roller 1 is an elastic roller in which a pipe-shaped core metal having an outer diameter of 40 mm is coated with silicone rubber having a thickness of 200 μm and JIS hardness of 30 degrees, and its surface has a releasability from toner. In order to secure it, PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) with a thickness of 30 μm is coated. Further, a heater 5 such as a halogen lamp heater is built in, and the heat melts the toner. The PFA has a high continuous use heat resistance temperature of 260 ° C. and is commercially available, for example, under the trade name SMT manufactured by Gunze Co., Ltd.

Although the heat generation length of the heater 5 will be described later, in order to make the temperature of the paper passing portion uniform, the heater 5 is made longer than the width of the paper, and the heat generation amount of the non-paper passing portion is made larger than that of the paper passing portion. This is because, in addition to the bearings (not shown), a gear group for rotationally driving is attached to both ends of the heating roller 1, and during standby, the temperature of the shaft end portion is lower than that of the center portion due to heat absorption and heat dissipation by the bearings and gear group. Is also reduced.

The pressure belt 2 is a seamless polyimide belt having a thickness of 50 μm and an inner diameter of 30 mm, and its surface is coated with PFA having a thickness of 30 μm to ensure releasability from toner. The pressure belt 2 is suspended by a driving roller 6 whose surface is coated with a silicone rubber having a thickness of 5 mm and a driven roller 7 having a heater 8 such as a halogen lamp heater built therein, and contacts the heating roller 1 at a winding angle θ. However, the nip portion h for heating and melting the toner image 25 is secured.

The peeling claw 4 is made of a heat-resistant synthetic resin or the like and comes into contact with or close to the peripheral surface of the heating roller 1 and forcibly peels the sheet 24 with the toner melted at the nip portion h from the heating roller 1. is there.

A preheating member 3 is installed on the upstream side of the nip portion h in the sheet conveying direction. As shown in FIG. 3, the preheating member 3 includes a first half case 3a, a second half case 3b, and a contact plate 3c, and has a box-shaped tunnel shape having openings on both side surfaces.

On the first half case 3a, contact plates 3c are provided rotatably on both ends of the heating roller 1 so as to come into contact with and separate from non-sheet passing portions (non-contact portions) of the heating roller 1. The contact plate 3c absorbs the heat of the non-paper passing portion of the heating roller 1 during continuous paper feeding to reduce the temperature rise of the non-paper passing portion, and the heat is applied to the first half case 3a and the second half case 3b. Since it has the function of preheating the paper 24, it is preferable that the material has good thermal conductivity and a small heat capacity.

Since the contact plate 3c is in sliding contact with the heating roller 1, it is necessary that the friction coefficient is small. In this embodiment, phosphor bronze having a thickness of 0.8 mm is used, and the surface thereof is coated with a fluororesin such as PTFE (polytetrafluoroethylene). The coating material on the surface may be PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) or a polyol vulcanized fluororubber or a polyamine vulcanized fluororubber layer.

As shown in FIG. 1, a part of the second half case 3b is in constant contact with the driven roller 7 via the pressure belt 2 and is heated by the heat of the heater 8 to drive the second half case 3b. The portion in contact with the roller 7 is coated with a fluororesin such as PTFE to ensure slidability.

The first half case 3a and the second half case 3b are made of metal such as aluminum or stainless steel in order to retain heat. In order to improve heat radiation to the paper 24 and the toner image 25, a plurality of rib-shaped heat radiation fins 3e are provided inside the preheating member 3 through which the paper 24 passes, and a blackish coating film 3f is formed. Has been done.

As shown in FIG. 1, the toner image 25 on the paper 24 is
The surface not formed with is transported while contacting or approaching the inner surface of the second half case 3b. In this way, the radiant heat from the second half case 3b is satisfactorily transferred and the paper 24 is smoothly introduced into the nip portion h.

As shown in FIG. 1, the spring 26 and the eccentric cam 2
A contact plate 3 that comes into contact with and separates from the non-sheet passing portion of the heating roller 1 by 7.
c is provided in the first half case 3a, and the second half case 3
b is in contact with the peripheral surface of the driven roller 7 via the pressure belt 2. The preheating member 3 forms a preheating space 28 by utilizing the radiant heat of the heating roller 1 and the driven roller 7, guides the paper 24 on which the unfixed toner image 25 is placed to the nip portion h, and The paper 24 and the toner image 25 are preheated by radiant heat.

In the standby state where printing is not performed, the eccentric cam 27 shown in FIG. 1 rotates about 90 degrees, the contact plate 3c is separated from the heating roller 1 by the pulling force of the spring 26, and the preheating member 3 moves to the first position. It is heated by the heat of the heater 8 inside the driven roller 7 via the two half cases 3b. As a result, the ambient temperature of the preheating space 28 formed by the first half case 3a and the second half case 3b is about 10 to 30 ° C., preferably about 2 ° C., higher than the glass transition temperature of the toner.
It is about 70 ° C to 90 ° C, which is about 0 to 30 ° C higher.
Therefore, after the toner image 25 is preheated in the preheating space 28,
Since the nip portion h of the heating roller 1 further receives heat, even if the nip portion h formed by the heating roller 1 and the pressure belt 2 is small, it is sufficiently melted and fixed on the paper 24.

If the temperature of the preheating space 28 does not exceed 10 ° C. above the glass transition point of the toner, the preheating effect is insufficient, and if it exceeds 30 ° C. above the glass transition point, the toner softens, which is not preferable.

On the other hand, during continuous sheet feeding, the first half case 3
The contact plate 3c attached to a comes into contact with the non-sheet passing portion of the heating roller 1 by the rotation of the cam 27, absorbs the heat and transfers it to the first half case 3a and the second half case 3b. As a result, the temperature rise of the non-sheet passing portion of the heating roller 1 is prevented, while the heat of the preheating member 3 is taken away by the sheet 24 by the continuous sheet passing to prevent the temperature drop of the preheating member 3 (preheating space 28). There is. Therefore, the temperature of the heating roller 1 and the preheating space 28 can be kept constant at the same level as during normal standby even during continuous sheet passing, and high-speed fixing is realized.

In the present embodiment, the contact plate 3c which comes into contact with and separates from the heating roller 1 is provided in the first half case, and the second half case 3b which comes into contact with the pressure belt 2 does not move and always contacts the entire surface of the pressure belt 2. Although the first half case 3a is always in contact with the non-sheet passing portion of the heating roller 1k, the contact plate 3c may be provided in the second half case 3b so as to come in contact with the pressure belt 2 on the contrary. . Also, the contact plate 3c
May be provided so as to always contact the entire surface of the heating roller 1 or the pressure belt 2 including a non-sheet passing portion.

The function of the preheating member 3 will be specifically described with reference to FIGS. 4 and 5. FIG. 4 is a schematic sectional view of the heating roller and its internal heater, and FIG. 5 is a surface temperature distribution diagram of the heating roller.

As shown in FIG. 4, a driving gear 30 for rotational driving, a connecting gear 31,
Bearings 32 and the like are attached. Therefore, in order to make the temperature of the sheet passing portion L1 of the heating roller 1 in the standby state uniform, the heater 5 is considered in consideration of the heat absorption amount and the heat radiation amount thereof.
It is necessary to increase the amount of heat generated at both end portions H2 of the sheet passing portion equivalent to H1.

In the case of an electrophotographic apparatus in which sheets 24 up to A4 size can be used, the sheet passing portion L1 of the heating roller 1 is 2
10 mm, and the non-sheet passing portions L2 provided on both sides are 10 mm.
40 mm is suitable.

Therefore, in the present invention, the heat generation length of the non-sheet passing portion H2 of the heater 5 is made longer than that of the non-sheet passing portion L2 of the heating roller 1, while the heat generation in the non-sheet passing portion H2 of the heater 5 is performed. The amount itself is set to be 15% to 30% larger than the sheet passing portion H1.

In the present invention, (sheet-passing portion L1) + (non-sheet-passing portion L2 × 2) of the heating roller 1 is the heating region width of the heating means, and the sheet-passing portion L1 of the heating roller 1 is the contact portion on the heating means side. The non-paper passing portion L2 of the heating roller 1 becomes a non-contact portion, and the paper passing portion L1 of the heating roller 1 (contact portion on the heating means side) matches the maximum width of the paper (image carrier) used.

FIG. 5 is a surface temperature distribution diagram of the heating roller. The horizontal axis shows the axial position of the heating roller, and the vertical axis shows the surface temperature of the heating roller. The curve A in the figure is the temperature distribution during the conventional continuous sheet feeding without using the preheating member, the curves B and C are the cases where the preheating member of the present invention is used, the curve B is during the continuous sheet feeding, and the curve C is the standby state. The temperature distribution over time is shown.

As shown in the figure, in each of the curves A, B, and C, the temperature of the paper passing portion L1 of the heating roller is almost constant at 150 ° C., but in the case of continuous paper feeding, the temperature of the non-paper passing portion L2. In contrast to the conventional example (curve A) of about 180 ° C., in the present embodiment, the temperature drops to 165 ° C. as shown by the curve B.

Looking at the behavior of the paper during continuous paper feeding,
In the conventional example, since the temperature difference between the paper passing portion and the non-paper passing portion is large as the temperature of the paper non-passing portion L2 rises, out-of-plane deformation of the paper such as corrugation occurs and the image at the edge of the paper is disturbed. In this embodiment, the paper is ejected stably and there is no image defect.

In the case of this embodiment, the surface temperature of the paper passing portion L1 of the heating roller 1 is about 150 ° C., and the non-paper passing portion L of the heating roller 1 is L.
The temperature of 2 is about 165 ° C, the fixing temperature of the nip h is about 130 ° C,
The temperature of the preheating space 28 is about 80 to 90 ° C.

FIG. 6 is a perspective view of the preheating member according to the second embodiment. This preheating member 3 is different from the preheating member 3 of the first embodiment shown in FIG. 3 in that the contact plate 3d that can be brought into contact with and separated from the sheet passing portion L1 of the heating roller 1 is provided at the center of the upper portion of the first half case 3a. Is the point attached. Although not shown, the contact / separation operation of the contact plate 3d is performed by the cooperation of a spring and a cam, like the contact plate 3c shown in FIG.

In the standby state, the contact plate 3d is in contact with the sheet passing portion of the heating roller 1, and transfers the heat of the sheet passing portion to the first half case 3a and the second half case 3b, and at the same time, the contact plate 3c. Is transmitted to the non-sheet passing portion of the heating roller 1. That is, in the standby state, the non-sheet passing portion of the heating roller 1 is heated by the preheating member 3 heated by the heater 8 inside the driven roller in addition to the heater 5 inside the heating roller, and thus the end of the heating roller 1 is heated. It is possible to prevent the temperature of the part from decreasing.

On the other hand, during continuous sheet feeding, the contact plate 3d is separated from the heating roller 1, and the contact plate 3d functions as a radiation fin to radiate the heat of the preheating member 3. As a result, the heat of the non-sheet passing portion of the heating roller 1 is radiated from the contact plate 3d through the contact plate 3c of the preheating member 3, so that the temperature rise of the non-sheet passing portion of the heating roller 1 can be reduced.

FIG. 7 is a schematic structural diagram of a roller fixing type heat fixing device according to the third embodiment. Elastic layer 3 on the peripheral surface
3, a heating roller 35 having a heater 34 incorporated therein and a pressure roller 38 having an elastic layer 36 provided on the peripheral surface thereof and incorporating a heater 37 are provided as a pair. The sheet 24 on which the unfixed toner image 25 is placed passes through the preheating member 3 to preheat the sheet 24 and the toner image 25, and then passes between the heating roller 35 and the pressure roller 38 to fix the sheet. Well done. Since the structure and function of the preheating member 3 are the same as those in the above-described embodiment, duplicated description will be omitted.

In the above-described embodiment, the contact plate is separated / contacted by using the spring 26 and the eccentric cam 27. However, the contact plate may be separated / contacted by using the elastic contact plate and cam. .

Although the rib-shaped heat radiation fins 3e are provided on the inner surface of the preheating member 3 in the above-described embodiment, it is also possible to provide other heat radiation fins having a corrugated plate shape or a pin shape.

In the above-mentioned embodiment, the case where the contact plates 3c and 3d have a flat shape has been described, but a contact plate which is curved in an arc shape so as to fit the peripheral surfaces of the heating rollers 1 and 35 and has a larger contact area is used. You can also

[0061]

According to the present invention, the temperature rise of the non-sheet passing portion of the heating roller due to continuous sheet passing can be suppressed and the time for melting the toner can be secured, so that a small fixing device capable of high-speed fixing and An image forming apparatus can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an electrophotographic apparatus using the fixing device.

FIG. 3 is a perspective view of a preheating member according to the first embodiment.

FIG. 4 is a sectional view of a heating roller according to the first embodiment.

FIG. 5 is a surface temperature distribution diagram of a heating roller.

FIG. 6 is a perspective view of a preheating member according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a fixing device according to a third exemplary embodiment of the present invention.

[Explanation of symbols]

1,35 heating roller 2 pressure belt 3 Preheating member 3a 1st half case 3b Second half case 3c, 3d contact plate 3e Radiation fin 3f coating film 4 peeling nail 5 heater 6 drive roller 7 Driven roller 8 heater 10 Fixing device 13 Transfer device 23 Paper (image carrier) ejector 24 sheets (image carrier) 25 toner image 26 spring 27 cams 30 drive gear 31 connected gear 32 bearings 33,36 elastic layer 34, 37 heater 38 Pressure roller h Nip part L1 heating roller sheet passing section (heating section side contact section) L2 heating roller non-sheet passing area (non-contact area) H1 heater sheet passing section H2 heater non-sheet passing part

Continued front page    (72) Inventor Tetsuji Takekoshi             1-1-1 Higashitaga-cho, Hitachi City, Ibaraki Prefecture             Ceremony Company Hitachi Ltd. Electric Appliance Division (72) Inventor Katsuyoshi Onose             1-1-1 Higashitaga-cho, Hitachi City, Ibaraki Prefecture             Ceremony Company Hitachi Ltd. Electric Appliance Division (72) Inventor Masaru Nakano             502 Kintatemachi, Tsuchiura City, Ibaraki Japan             Tate Seisakusho Mechanical Research Center F-term (reference) 2H033 AA03 AA20 BA01 BA25 BA26                       BA27 BA29 BB18 BB21 BB38                 3K058 AA03 AA13 BA18 DA26 GA03                       GA06

Claims (11)

[Claims] 1. A heating means for heating an image carrier on which an unfixed toner image has been transferred while being conveyed, and a pressure means for pressurizing the image carrier to the heating means side. In a heat fixing device for fixing an image on an image carrier, the heating region width of the heating means is longer than the maximum lateral width of the image carrier to be used, and the heating means does not come into contact with the image carrier of the heating means. A heat-fixing device, characterized in that a heat-dissipating means is provided which comes into contact with the portion and absorbs heat from the non-contact portion. 2. A heating means for heating an image carrier on which an unfixed toner image is transferred while being conveyed, and a pressure means for pressurizing the image carrier to the heating means side. In a heat fixing device for fixing an image on an image carrier, the image carrier on which the unfixed toner image is transferred is preheated upstream of the nip portion between the heating unit and the pressure unit in the image carrier conveying direction. The heating area width of the heating means is longer than the maximum lateral width of the image carrier to be used, and one of the preheating members is provided in a non-contact portion of the heating means that is not in contact with the image carrier. A heating and fixing device characterized in that a toner portion and a non-contact portion absorb heat from the non-contact portion to preheat the toner image before fixing and the image carrier. 3. A toner comprising heating means for heating an image carrier on which an unfixed toner image is transferred while being conveyed, and pressurizing means for pressing the image carrier to the heating means side. In a heat fixing device for fixing an image on an image carrier, the pressing unit also has a heat source, and the unfixed toner is provided on the upstream side of the nip portion between the heating unit and the pressing unit in the image carrier conveying direction. A preheating member for preheating the image carrier on which the image is transferred is arranged, and a part of the preheating member comes into contact with the pressing means, absorbs the heat of the pressing means, and the heat causes the toner before fixing. A heating and fixing device characterized by preheating an image and an image carrier. 4. A heating means for heating an image carrier on which an unfixed toner image is transferred while being conveyed, and a pressure means for pressing the image carrier to the heating means side. In a heat fixing device for fixing an image on an image carrier, the image carrier on which the unfixed toner image is transferred is preheated upstream of the nip portion between the heating unit and the pressure unit in the image carrier conveying direction. The heating area width of the heating means is longer than the maximum lateral width of the image carrier to be used, and one of the preheating members is provided in a non-contact portion of the heating means that is not in contact with the image carrier. Parts contact each other, the pressurizing means also has a heat source, and the other part of the preheating member contacts the pressurizing means to absorb the heat of the non-contact part and the pressurizing means, respectively. Characterized by preheating the toner image and image carrier before fixing with heat Thermal fixing device. 5. The heat fixing device according to claim 4,
A separation / contact means is provided for separating / contacting a part of the preheating member that comes into contact with the non-contact portion with respect to the non-contact portion, and during standby, a part of the preheating member is separated from the non-contact portion by the separation / contact means. The preheating member is heated by the heat from the pressurizing unit side, and at the time of continuous fixing, a part of the preheating member is brought into contact with the non-contact portion by the separating / contacting unit so that the pressurizing unit and the heating unit are not in contact with each other. A heating and fixing device, characterized in that it is configured to heat the preheating member with heat from the section. 6. The heating and fixing device according to claim 2, claim 4, or claim 5, wherein a heating-unit-side contact portion that comes into contact with the image bearing member is provided substantially at the center of the heating unit in the axial direction. The heating and fixing device is characterized in that the non-contact portions are provided on both sides of the heating-unit-side contact portion, and the non-contact portions on both sides respectively contact a part of the preheating member. 7. The heating and fixing device according to claim 2, wherein the preheating member has a tunnel shape, and the image carrier passes inside the preheating member. A heat-fixing device characterized in that 8. The heating and fixing device according to claim 2, wherein a heat radiation fin is provided on a surface of the preheating member facing the image carrier. 9. The heating and fixing device according to claim 2, wherein a black coating film is formed on a surface of the preheating member facing the image carrier. Fixing device. 10. The heat fixing device according to claim 2, wherein the preheating temperature of the preheating member is equal to or higher than the glass transition point of the toner. 11. An image forming apparatus comprising the heat fixing device according to claim 1 provided between a transfer device and an image carrier discharging device on a conveyance path of the image carrier. apparatus.