JPH0822208A - Fixing device - Google Patents

Abstract

PURPOSE:To maintain good fixability by connecting a side plate part for holding shaft parts at both ends of a heating roller with a side plate part for holding the other roller by use of non-metallic heat insulating members. CONSTITUTION:The side plate part 9 for holding the heating roller 6 is connected with the side plate part 8 for holding the pressure roller 2 by use of pins 10 and 11 and a hook 12 formed of the non-metallic heat insulating material, and a proper holding and pressing part is formed by the rollers 6 and 2. Thus, when a recording material on which an unfixed image is formed enters the nip part of the rollers 6 and 2 and passes through the nip part, the unfixed image is fixed on the recording material by heat and pressure. In this case, the pin 10 is prepared for connecting the side plates 9 and 8, and the pin 10 is not fixed especially, on the other hand, the pin 11 is fixed on the side plate part 9 so as to be engaged with the hook 12 installed on the side plate part 8. Thus, the side plate parts 9 and 8 are shielded from heat by the pins 10 and 11 and the hook 12 formed of the heat insulating member and then fixed. Thus, the temperature of the heating roller is prevented from extremely dropping even in the case of continuously copying.

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 recording device, a printer, a microreader printer, or the like, and an appropriate image forming principle such as electrophotography, electrostatic recording, magnetic recording, and image forming of a process. The unfixed image of the developer (toner), which is formed and carried by a transfer material (photosensitive paper, electrostatic recording paper, etc.) on a recording material such as a transfer material (indirect method) or a direct method, is fixed on the recording material at the means. The present invention relates to a fixing device.

[0002]

2. Description of the Related Art Conventionally, as a fixing device for an image forming apparatus such as a general electrophotographic copying machine, various fixing methods have been proposed and implemented. Among them, a roller pair is used. A heating roller fixing device (heat roll fixing method) in which at least one of the roller pair is a heating roller heated by a heat source is predominant.

In this system, in general, the roller of the roller pair, which comes into contact with the image bearing side of the recording material, is
The heating roller is heated by a heat source, and the other roller is a pressure roller arranged so as to be in pressure contact with the heating roller.

Here, the basic structure will be described with reference to FIG. In FIG. 6, 6 is a heating roller, and the heating roller 6 has a heat source 7 such as a halogen heater inside.
And a fluororesin layer 6b such as PTFE is laminated on the surface layer of the core metal 6a such as aluminum to prevent the occurrence of the offset phenomenon. Then, the shaft portions at both ends of the heating roller 6 are connected via the heat insulating bush 5 and the bearing 4,
It is held by a side plate 8 made of stainless steel or the like.

Reference numeral 2 denotes a pressure roller, and the pressure roller 2 has a core metal 2a made of aluminum or the like and an elastic layer 2b made of rubber or the like coated thereon. The shaft portions at both ends of the pressure roller 2 are also held by the side plate 8 via the bearings 3.

The above roller pair forms a pressing portion (hereinafter referred to as a nip portion) by an appropriate pressure contact force, and is rotated by being driven by a driving means (not shown). . As a result, when the recording material on which the unfixed image is formed enters the nip portion between the heating roller 6 and the pressure roller 2, the recording material is nipped and conveyed while receiving heat and pressure at the nip portion. The unfixed image is fixed on the recording material.

[0007]

However, according to the above-mentioned conventional example, when fixing an unfixed image to a recording material, excellent thermal efficiency is exhibited at the time of fixing during continuous copying of one sheet to several sheets. You can get excellent fixing performance,
In the fixing at the time of continuous copying of several tens to several hundreds of sheets, the fixing performance tends to gradually decrease as a plurality of sheets progress.
This is because the heating roller 6 is heated by the heat source 7 as needed, but when performing a continuous fixing operation, the heat is gradually deprived to the recording material side further, so that the temperature of the heating roller 6 is reduced. Is caused by a gradual decrease in the temperature, which is remarkable in a large-sized copying machine capable of making a large amount of copying in a unit time.

Further, since the fixing device is connected to the side plate 1 of the image forming apparatus such as stainless steel as shown in FIG. 6, the main body of the image forming apparatus becomes cold when the ambient temperature is low or in the morning. In this case, the heat of the heating roller 6 is taken by the side plate 8 of the fixing device and the side plate 1 of the main body of the image forming apparatus to a considerable extent, and it is found that the temperature drop of the heating roller 6 is greatly promoted. There is.

In order to improve this phenomenon, it is easiest to increase the heating amount per unit time, that is, increase the output of the heat source 7, but in reality, the power capacity of the copying machine itself is unlimited. There is a limit because it is not.

Therefore, in order to reduce the heat transfer to the recording material side as much as possible, it is possible to preheat the fixing device before the recording material enters the nip portion. As such a method, a method of arranging a heater in a cassette for storing the recording material, a method of arranging a heater in a feeding roller, or the like has been proposed. It uses electricity, not an improvement in nature.

On the other hand, a method has also been proposed in which the exhaust gas discharged from the machine and the fixing device is fed into the cassette to preheat the recording material, but the heating power to the recording material was not recognized so much.

Further, conventionally, since the shaft portions of the heating roller 6 and the pressure roller 2 are held by the integral side plate as described above, maintenance work is difficult when both rollers are clogged with recording material or the like. There was also the problem that

It is an object of the first invention of the present application to solve the above-mentioned problems and to provide a fixing device capable of preventing the heat of the heating roller from being wasted.

In addition to the above object, the second invention of the present application aims to provide a fixing device capable of further reducing the transfer of heat of the heating roller to surrounding members. .

Further, in addition to the above-mentioned object, the third invention of the present application aims to provide a fixing device which facilitates maintenance work while reducing the transfer of heat of the heating roller to surrounding members. There is.

Further, in addition to the above objects, a fourth invention of the present application aims at providing a fixing device capable of further reducing the transfer of heat of the heating roller to surrounding members. There is.

[0017]

According to the first invention of the present application, the above object is to provide a recording material in which an unfixed image is formed and carried on a pinching portion between a pair of rollers which rotate in pressure contact with each other. In a fixing device that introduces and fixes the unfixed image on the recording material surface by conveying under pressure, a side plate portion that holds the shaft portions at both ends of a heating roller having a heating source among the pair of rollers, and the other roller This is achieved by connecting at least the side plate portions of the pair of rollers with the side plate portion to be held by a non-metal heat insulating member.

According to the second invention of the present application,
In the first aspect of the invention described above, the side plate portion that holds the heating roller and the side plate portion that holds the other roller are made of a non-metallic heat insulating member on at least one side.
This is achieved by being connected by points.

Further, according to the third invention of the present application, the above-mentioned object is the side plate portion in the above-mentioned second invention,
This is achieved by being rotatably arranged around one heat insulating member.

According to the fourth invention of the present application,
The above-mentioned object is any one of the above-mentioned first invention to the above-mentioned third invention, wherein any one of the side plate portions of the pair of rollers is provided with a side plate portion on the image forming apparatus main body side and a non-metallic heat insulating member. This is achieved by joining with members.

[0021]

According to the first invention of the present application, when heating is started from the heating source for the heating roller, the temperature of the heating roller rises to a predetermined temperature. The heat tends to be taken by the side wall portions holding the recording material and the shaft portions at both ends of the heating roller, and the temperature tends to decrease.
However, since the side plate portion is connected to the side plate portion that holds the other roller by a non-metallic heat insulating member, the heat of the other roller that is taken by the side plate portions that holds the shaft portions at both ends of the heating roller is the other roller. The transmission to the side plate portion holding the is blocked, and the decrease in temperature is suppressed to a predetermined level.

According to the second invention of the present application,
In the first aspect of the invention, the side plate portion holding the heating roller and the side plate portion holding the other roller have at least one surface side joined at two points by using a non-metal heat insulating member. The heat transfer from one side plate portion to the other side plate portion is further suppressed to a lower level, and the pinching portions of the pair of rollers are reliably formed.

Further, according to the third invention of the present application, in the above-mentioned second invention, since the side plate portion is rotatably arranged around one of the heat insulating members, the side plate portion is attached to the pinching portion. Maintenance work such as removing jammed recording material becomes easy.

According to the fourth invention of the present application,
In any one of the first invention to the third invention, one of the side plate portions of the pair of rollers is connected to the side plate portion of the image forming apparatus main body side by a non-metal heat insulating member. Therefore, the heat transfer from the side plate portion on the heating roller side to the other side plate portion can be further suppressed.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 (a)
FIG. 1 is a side view showing a schematic configuration of a fixing device in the first embodiment of the present invention, and FIG. 1 (b) is a sectional view thereof. In FIG. 1, 6 is a heating roller, and the heating roller 6 is
A heat source 7 such as a halogen heater is provided inside, and a fluorine resin layer 6b such as PTFE is laminated on the surface layer of the core metal 6a such as aluminum in order to prevent the occurrence of an offset phenomenon. The shaft portions at both ends of the heating roller 6 are held by the side plate 8 made of stainless steel or the like via the heat insulating bush 5 and the bearing 4.

Reference numeral 2 denotes a pressure roller. The pressure roller 2 has a core metal 2a made of aluminum or the like and a surface layer of a core metal 2a covered with an elastic layer 2b of rubber or the like.
The shafts at both ends of are supported by bearings 3.

The side plate 9 for holding the heating roller 6 and the side plate 8 for holding the pressure roller 2 are made of PPS,
Pin 1 made of non-metallic heat insulating material such as PAI and PI
Combined with 0, 11 and hook 12, the rollers form a suitable nip.

Therefore, the recording material on which the unfixed image is formed enters the nip portion between the heating roller 6 and the pressure roller 2 and, when passing through the nip portion, is fixed on the recording material by heat and pressure.

Here, the pin 10 formed of a heat insulating member
Is not particularly fixed by a pin connecting the side plate portion 9 and the side plate portion 8, but the pin 11 formed of a heat insulating member is fixed to the side plate portion 9 and is a hook formed of a heat insulating member on the side plate portion 8 side. It is adapted to engage with 12. Therefore, the side plate portion 9 and the side plate portion 8 are pins 10 which are thermally formed of a heat insulating member,
It is blocked and fixed by 11 and a hook 12, and is configured to be rotatable around a pin 10 formed of a heat insulating member as an axis.

Next, the fixing performance of the fixing device in this embodiment as described above will be described in comparison with a conventional fixing device.
The experiment was carried out by modifying a commercially available copying machine and fixing device.
The heating roller 6 was a hard roller having a diameter of 50 mm and a core metal thickness of 7 mm, and the pressure roller 2 had a diameter of 40 mm and a rubber hardness of 30 degrees (JIS-A). Next, a halogen heater with an output of 800 (W) is used as the heat source 7, and the pins 10, 11 and the hook 12 of the heat insulating member are PA.
I type resin was used. The productivity of the copying machine used at this time was 29 (sheets / minute) in A3 size. The heating roller 6, the pressure roller 2, and the heat source 7 used in the conventional example are the same as above.

FIG. 2 shows the rate of decrease in the surface temperature of the heating roller 6 when continuously copying a commercially available recording material of A3 size.
According to this result, there was a difference of about 10 ° C. between the present example and the conventional example at the time of 500 sheets. Further, although the actual fixing performance is shown in FIG. 3, the fixing device of the present embodiment was able to obtain good results because it depends on the surface temperature of the heating roller 6.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 4A is a side view showing the schematic construction of the fixing device in the second embodiment of the present invention, and FIG. 4B is a sectional view thereof. In this embodiment, the side plate portion 9 that holds the heating roller 6 and the side plate portion 8 that holds the pressure roller 2 are made of PP.
It is characterized in that they are coupled through a non-metallic heat insulating member 13 such as S, PAI, PI.

Also in the fixing device according to the present embodiment, heat transfer from the side plate 9 to the side plate 8 is blocked, and excellent fixing performance is exhibited even when continuous copying is performed.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. In addition, the first embodiment 1
The same parts as those of the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 5A is a side view showing a schematic structure of a fixing device according to the third embodiment of the present invention, and FIG. 5B is a sectional view thereof. In this embodiment, PPS, PAI, P are provided between the fixing device and the side plate 1 of the image forming apparatus main body.
It is characterized in that they are coupled via a non-metallic heat insulating member 143 such as I.

In this embodiment, the heat transfer from the side plate portion 9 of the heating roller 6 to the side plate portion 8 is cut off, and further the heat transfer to the side plate 1 of the image forming apparatus main body is cut off. The temperature decrease of 6 can be suppressed more reliably.

[0039]

As described above, the first aspect of the present application
According to the invention, since the side plate portion that holds the shaft portion at both ends of the heating roller and the side plate portion that holds the other roller are joined by the non-metal heat insulating member, even when continuous copying is performed,
The temperature of the heating roller does not drop extremely, and good fixability can be maintained.

According to the second invention of the present application,
In the first aspect of the invention, the side plate portion holding the heating roller and the side plate portion holding the other roller have at least one surface side joined at two points by using a non-metal heat insulating member. The heat transfer from one side plate part to the other side plate part can be suppressed to a further lower level, and moreover, the pinching part of the pair of rollers can be surely formed, so that good fixing properties can be obtained during continuous copying. Can be maintained.

Further, according to the third invention of the present application, in the second invention, since the side plate portion is rotatably arranged around one of the heat insulating members, the side plate portion is attached to the pinching portion. Maintenance work such as removing a jammed recording material can be facilitated.

According to the fourth invention of the present application,
In any one of the first invention to the third invention, one of the side plate portions of the pair of rollers is connected to the side plate portion of the image forming apparatus main body side by a non-metal heat insulating member. Therefore, the heat transfer from the side plate portion on the heating roller side to the other side plate portion can be further suppressed, and the fixability at the time of continuous copying can be maintained.

[Brief description of drawings]

FIG. 1A is a sectional view showing a schematic configuration of a fixing device according to a first embodiment of the present invention, and FIG. 1B is a side view showing a schematic configuration of a fixing device according to the first embodiment of the present invention. is there.

FIG. 2 is a diagram showing changes in the surface temperature of the fixing roller when continuous copying is performed in the first embodiment of the present invention.

FIG. 3 is a diagram showing a temperature decrease rate after rubbing when continuous copying was performed in the first example of the present invention.

FIG. 4A is a sectional view showing a schematic configuration of a fixing device according to a second embodiment of the present invention, and FIG. 4B is a side view showing a schematic configuration of a fixing device according to the second embodiment of the present invention. is there.

5A is a sectional view showing a schematic configuration of a fixing device according to a third embodiment of the present invention, and FIG. 5B is a side view showing a schematic configuration of a fixing device according to the third embodiment of the present invention. is there.

FIG. 6 is a cross-sectional view showing a schematic device of a conventional fixing device.

[Explanation of symbols]

1 side plate part (side plate part of image forming apparatus main body) 2 pressure roller (the other roller of the pair of rollers) 6 heating source 7 heating roller (roller having a heat source of the pair of rollers) 8 side plate part (the other roller of the pair) Side plate part to hold 9 Side plate part (side plate part to hold shaft part of heating roller) 10, 11 Pin (heat insulating member) 12 Hook (heat insulating member) 13 Heat insulating member

Claims (4)

[Claims] 1. A fixing device which introduces a recording material on which an unfixed image is formed and carried into a nip portion between a pair of rollers which are in pressure contact with each other, and conveys the unfixed image to fix the unfixed image on the surface of the recording material. In, in the pair of rollers, at least each side plate portion of the pair of rollers of the side plate portion that holds the shaft portion at both ends of the heating roller having a heating source, and the side plate portion that holds the other roller is a non-metallic material. A fixing device characterized by being joined by a heat insulating member. 2. The side plate portion holding the heating roller and the side plate portion holding the other roller have at least one surface side,
The fixing device according to claim 1, wherein the fixing device is connected at two points by using a non-metallic heat insulating member. 3. The fixing device according to claim 2, wherein the side plate portion is rotatably arranged around one heat insulating member. 4. The non-metallic heat insulating member is used to connect any one of the side plate portions of the pair of rollers to the side plate portion on the image forming apparatus main body side. The fixing device according to any one of claims.