JPS62150278A - Fixing device - Google Patents

Abstract

PURPOSE:To change more than approximately 90% of input energy into heat so as to improve the fixing efficiency of a fixing device, by constituting at least one of a pair of rotating bodies of a radiating member which houses a heat source and radiates infrared rays of >=2mum in wavelength from its surface and providing a reflecting member in the vicinity of this rotating body. CONSTITUTION:A heated roller main body 131 radiates far infrared rays of >=2mum in wavelength from its surface. Since this heat roller 13 radiates about 60% of heat energy as the far infrared rays, a reflecting plate 18 covering the heat roller 13 is provided above the roller 13 so as to reflect the far infrared rays efficiently. The inner surface of the reflecting plate 18 being faced to the roller 13 is finished to a mirror surface and the plate 18 is provided with an opening section 18a on its side A, through which transfer paper P advances. Because of the opening section 18a provided to the reflecting plate 18, the toner on the transfer paper P is preheated to some extent by the far infrared rays reflected by the reflecting plate 18 before the transfer paper P advances to the pressure-contacting section of the roller pair. Therefore, the fixing property of a toner image can be improved further.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a fixing device used in a recording device such as an electrophotographic device, an electrostatic recording device, or a printer. The present invention relates to a fixing device that fixes an object to be fixed onto a recording material by passing it through the recording material.

(Background Art) Conventionally, in an electrophotographic device, an object to be fixed on a recording material,
For example, various types of fixing devices have been devised for fixing a single layer of toner onto a recording material, such as fixing devices employing standard methods such as heat fixing, solvent fixing, and pressure fixing. Among these, the fixed fixing method widely used for -j throwing is a heating fixing method, and fixing devices that employ this method include, for example, a chamber fixed fixing device,
Heat roller fixing devices, flash fixing devices, and the like are known. However, in the chamber fixing device,
The recording material carrying the toner image is heated in a non-contact manner using a red-hot sheathed heater to melt the toner made of resin and fix it on the recording material, which requires a large amount of energy.
Furthermore, when the recording material jams, there is a drawback that the recording material may catch fire due to heating. In addition, flash fixing devices require large capacitors to instantaneously apply high voltage to the flash lamp to cause it to emit light.
This has the disadvantage that it increases the size of the device and requires time to charge the capacitor, making it difficult to increase the speed. For this reason, the fixing devices in current electrophotographic devices include a fixing roller that has an internal heat source and directly contacts the recording material carrying the toner image to fix the toner image on the recording material. The mainstream is a heating roller fixing device that has a pressure roller that comes into pressure contact with a fixing roller. However, in this heated roller fixing device, a fixing roller whose surface is coated with Teflon (trade name) or the like on the surface of a cylinder made of steel or aluminum is heated from the inside to about 150 to 200 degrees Celsius using a halogen lamp heater, etc. Since the toner image is fixed by passing the recording material between the fixed fixing roller and the pressure roller that is in pressure contact with the fixing roller, the efficiency of the energy used for fixing is low. In other words, the thermal efficiency of the halogen lamp heater that is the heat source is that the infrared radiation that can be extracted as heat is approximately 80%.
This heat is as low as ~85%, and furthermore, heat escape from one end of the cylinder occurs because this heat is transferred to the steel or aluminum cylinder.

For this reason, it has been considered to provide heat insulating means to the ends of the rollers. Adequate insulation complicates the equipment and increases costs. Therefore, the heat that can actually be used for fixing is less than 70% of the total, resulting in low energy efficiency. Furthermore, in the heating roller fixing device described above, in order to obtain the temperature required by the fixing roller (approximately 150 to 200 degrees Celsius), the temperature of the halogen lamp heater itself must be extremely high (approximately 2000 degrees Celsius); If the control circuit or the like fails, the halogen lamp heater will abnormally rise in temperature, causing the temperature around the fixing device to rise abnormally, which ultimately has a serious effect on the entire device.

(Object of the Invention) The present invention was made in view of the above-mentioned conventional example, and an object of the present invention is to provide a novel fixing device which is highly efficient and highly safe with less loss of thermal energy.

(Summary of the Invention) That is, the present invention provides a fixing device that fixes an object to be fixed on a recording material by passing the recording material between a pair of rotating bodies that are in pressure contact with each other. One of the rotating bodies has a radiating member that has heat particles inside and emits infrared rays with a wavelength of 2 μm or more from the surface, and by providing a reflecting member near the rotating body, the radiating member emits infrared rays with a wavelength of 2 μm or more. It is characterized by reflecting infrared rays and irradiating the recording 714 with the reflected infrared rays.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Second
The figure shows an electrophotographic copying apparatus to which the fixing device of the present invention is applied. When a copy button (not shown) is pressed, the photosensitive drum 1 starts rotating in the direction of the arrow, and the document table 2 on which the document to be copied is placed moves to the home position. The photosensitive drum 1 is uniformly charged by the charger 3 as it rotates.

On the other hand, the document table 2 starts moving from the Baum position as the photoreceptor tram 1 rotates. The original on the original platen 2 is illuminated by an original illumination lamp 4, and a light image of the original is sequentially exposed to the uniformly charged photoreceptor drum 1 at an exposure position 6 via a lens system 5. As a result, an electrostatic latent image is formed on the photoreceptor drum 1. Then, this electrostatic latent image is developed into a toner image by a developing device 7, and the toner image is transferred to a transfer paper P as a recording material, which is fed by a paper feed roller 8 and a registration roller 9 in synchronization with the leading edge of the toner image. is transferred by the transfer charger 10.

The transfer paper P onto which the toner image has been transferred is further transferred to a conveyance roller 1.
1.12 and reaches the fixing device F of the present invention.

The transfer paper P is pinched and conveyed by a rotating pair of a heat roller 13 that emits far infrared rays and a pressure roller 14 that is pressed against the heat roller 13 . At this time, the far infrared rays emitted from the heat roller 13 are reflected by the reflection plate 18, and the far infrared rays are irradiated onto the transfer paper P just before being conveyed while being held between the heat roller 13 and the pressure roller 14. Due to this irradiation with far-edge infrared rays, the temperature of the toner on the transfer paper P increases or a portion thereof melts. Thereafter, the transfer paper P is guided to the pressure contact portion between the heat roller 13 and the pressure roller 14, and the toner image is transferred to the transfer paper P.
will be established. After fixing, the transfer paper P is discharged onto the tray 16 by the discharge roller 15, and a copy image is obtained.

Note that residual toner is removed from the photoreceptor drum 1 onto which the toner image has been transferred by a cleaner 17, and the photoreceptor tram 1 is prepared for the next image formation.

Next, the above-described fixing device of the present invention will be described in more detail with reference to FIGS. 1A, 1B, and 3A and 3B.

1A and 1B show a heat roller 13 that emits far infrared rays. The heat roller 13 is made of betalite ((Li20-Na20) ・A12 o3 ・8
A mixture of SiO2) and clay was made into a kneaded clay, extruded into a cylindrical shape, and bisque fired at 800°C.
A roller body 131 is coated with a coating consisting of 28% zinc oxide and 6.8% aluminum hydroxide and fired. Inside the roller body 131, a highly heat-resistant support such as a quartz tube is coated with a nichrome wire or the like. It has a heat generating source 132 consisting of a resistance wire wound spirally or a resistance wire coated with a heat-resistant ceramic and rolled up into a cylinder and fired, and the roller end is made of ceramic or the like. Insulating member 13 made of
Covered by 3. The heat roller body 131 is rotatably supported by the frame of the fixing device F via a ball bearing (not shown), etc., and the heat generation source 132 is positioned on the central axis within the roller body 131. In addition, it is fixed to the frame of the fixing device F via a heat insulating insulator 134. Note that 135 is a lead wire for supplying power to the heat generating source 132.

Heat generation source 132 provided inside the heat roller main body 131
However, when the main switch (not shown) of the copying apparatus is turned on and electricity is turned on, the heat generating source 132 quickly heats up and emits far-infrared rays. The emitted far-infrared rays are absorbed from the inner wall surface of the roller body 131 and heat the roller body 131. Then, the heated roller main body +31 emits far infrared rays with a wavelength of 2 μm or more from the roller surface. The toner is melted by heat conduction from the far-infrared roller main body 131.

Regarding the heat roller 13, in order to prevent the toner from being offset on the surface of the roller during melting, a high male type resin such as Teflon is coated as a surface layer with a thickness of 5 to 20 μm.
It is also possible to use a film formed to a thickness of about 100 ml. The roller base 131 of the heat roller 13 is made of ceramic as described above, or is made of a thin metal roller whose inner surface is treated with black after coating with a far-infrared emitting substance such as the above-mentioned medicine.
It may also be baked. However, when the heat roller itself is made of heat-insulating ceramic, heat escape from the roller end to the outside is prevented even when a bearing such as a metal member is used to directly contact the roller end. Therefore, energy loss can be reduced compared to when a thin metal roller is used.

Furthermore, the constituent materials of the heat roller include ceramics sintered by adding metals or metal oxides to cordierite (porcelain with a composition of MgO5i02-AlI3o3), 40 to 80% by weight of manganese dioxide, and cobalt oxide. Sintered body of a mixture of 10 to 20% by weight, 20 to 40% by weight of iron oxide, and 10 to 20% of copper oxide, Y2 o3 ° La2
03, Zr with rare earth element components such as CeO2 dissolved in solid solution
O2 ceramic or the like may be used as the roller body itself, or the above material may be formed on the surface of the metal roller.

Here, in order to efficiently heat the heat roller body and emit far infrared rays efficiently, it is necessary to heat the resistance wire such as nichrome wire without making it red-hot, specifically about 700~
It is preferable to maintain the temperature at 800°C. This is because when the resistance wire becomes red hot, it emits light that is not converted into thermal energy with a wavelength of 1 μm or less, which not only reduces the efficiency of generating Joule heat for human power, but also deteriorates the heat absorption efficiency of the ceramic heat roller. This is because you end up doing it. In addition, when using a non-red-hot resistance wire, the heat conversion efficiency is 9
It was 0% or more.

Figure 3A shows the relationship between the wavelength of the far infrared rays emitted from the heat generating source 132 mentioned above and the emissivity (ratio of the intensity of thermal radiation of the heating element to the intensity of thermal radiation of a black body at the same temperature). be. (
Note that this is when the temperature of the heat source 132 is approximately 500°C. ) As shown, the heat source 132 has a wavelength of 2 μm.
The emissivity rises rapidly from the point P, and at the maximum value P, the emissivity exceeds 0.7, showing a heat conversion rate of 80% or more. Furthermore, when the wavelength becomes 5 μm or more, the emissivity decreases to 1. It shows radiation characteristics approaching .

Therefore, considering that the light absorption properties of resins are generally in the long wavelength region of approximately 5 μm or more, this method is particularly effective when fixing objects that are mainly composed of resins, such as toner. .

Further, FIG. 3B shows the relationship between the wavelength and relative radiation intensity of far infrared rays emitted from the heat generating source 132 described above. Here, the relative radiant intensity is calculated by converting other wavelengths, with the radiant intensity of the heat rays having the maximum absolute radiation temperature n1 degrees in the entire wavelength range of the heat rays emitted from the heating source 132 as 100%. Embodiment E of the present invention shows a heat generating source 132
This is when the temperature is 500°C. As you can see from the figure, halogen heater H has a high heat source temperature (approximately 2000℃)
The maximum relative radiation intensity is around 1 μm, and the energy is used as visible light, indicating a decrease in thermal efficiency. This trend shows that even in a black body, which is an ideal heat source, the higher the temperature increases according to the Wien displacement side, the more the radiation temperature shifts toward the visible side, and the thermal efficiency decreases. That is, having the maximum value P of the relative radiation intensity/intensity in a wavelength range of 2 μm or more as in Example E is very effective in terms of thermal efficiency. Note that Wien's displacement law is expressed as λmT=b, where T is the absolute temperature, λm is the wavelength at which the radiation intensity is maximum, and b is a constant.

FIG. 4 shows a state in which the heat roller 13 as described above is incorporated into a fixing device. A pressure roller 14 is pressed against the heat roller 13 by a pressure means (not shown). The pressure roller 14 is an aluminum cylinder coated with RTV silicone rubber. The surface temperature of the heat roller 13 is detected by a temperature sensor 17, and based on the detection result, a temperature control circuit (not shown) controls the current supplied to a heat generation source 132 provided inside the heat roller 13. . Thereby, the roller itself is maintained at a predetermined temperature. Furthermore, since the heat roller 13 emits about 60% of its thermal energy as far infrared rays, a reflecting plate 18 is provided to cover the heat roller 13 as shown in the figure to avoid reflecting this far infrared rays.

The inner surface of the reflecting plate 18 facing the roller is processed to have a mirror surface. The reflective plate 18 has an opening 1 on the entrance side A of the transfer paper P.
8a. As described above, since the reflective plate 18 is provided with the opening 18a, the toner on the transfer paper P is transferred to the reflective plate 18 before the transfer paper P enters the pressure contact portion of the pair of rollers.
The far infrared rays reflected by the rays heat the surface to some extent in advance. Therefore, the fixability of the toner image can be further improved.

In FIG. 4, 19 is a guide for guiding the transfer paper to the pressure contact portion of the pair of rollers, 20 is a discharge guide for guiding the transfer paper after fixing, and 21 is for preventing the transfer paper from wrapping around the heat roller 13. The release claw 22 is a heat insulating member provided on the outside of the reflecting plate 18. The material of the reflector plate 18 may be metal such as aluminum, glass, or gold.

Materials on which metals such as silver, platinum, and aluminum are vapor-deposited can also be used. Furthermore, the human locaid 19 has a reflector 1
It is preferable to be made of a heat-resistant resin or the like that absorbs far infrared rays reflected by 8. This is because when the artificial guide is heated, the transfer paper conveyed along the artificial guide is heated from the back side, increasing the fixing efficiency.

FIG. 5, FIG. 6, and FIG. 7 show other embodiments of the reflector. In FIG. 5, the shape of the reflection plate is a part of an ellipse, and the heat roller 13 and the reflection plate 23 are respectively arranged so that the center of the roller is located at the focal point F1 of the ellipse. With this arrangement, the far infrared rays radiated from the heat roller 13 and reflected by the reflection plate 23 are concentrated at the focal point F2, so that the toner image on the transfer paper P is generated before entering the pressure contact portion of the pair of rollers. It is heated to some extent beforehand. Therefore, the fixability of the toner image is improved.

Further, in FIG. 6, the shape of the reflecting plate 24 is a parabola, and the reflecting plate 24 is arranged so that the axial center of the heat roller 13 is located at the focal point of the parabola. This also allows the same effect as in FIG. 5 to be obtained. Incidentally, in the state shown in FIG. 6, the reflecting plate 24 may be slightly tilted toward the transfer paper ejection side.

Furthermore, compared to FIGS. 5 and 6, FIG. 7 shows an example of a reflector that more efficiently irradiates far-infrared rays to the transfer paper just before it is conveyed while being held between the pressure contact portion of the pair of rollers. It is something. That is, the shape of the reflecting plate 25 of this embodiment is a part of an ellipse as shown in FIG.
1, and furthermore, the ellipse is set so that the other focal point F2 of the ellipse is located on the entrance side of the transfer paper P with respect to the central axis of the pressure roller 14. , a reflecting plate 25 is provided. According to this, the amount of far infrared rays radiated from the heat roller 13 and reflected by the reflection plate 25 can be increased on the transfer paper entry side with respect to the roller pair rather than on the transfer paper discharge side.

Note that in FIGS. 5, 6, and 7, T represents an unfixed toner image on the transfer paper P.

(Effects of the Invention) As explained above, according to the present invention, one of the pair of rotating bodies is configured with a radiating member that has a heat source inside and emits infrared rays with a wavelength of 2 μm or more from the surface. It became possible to convert approximately 90% or more of the input energy into heat, improving thermal efficiency. Furthermore, in the present invention, the infrared rays emitted from the radiation member are reflected by the reflection member to the unfixed matter on the recording material before being fixed.

By irradiating the infrared rays, it became possible to increase the fixing efficiency. Further, since the temperature of both the rotating body and the heat source is maintained at 180° C. to 300° C., there is no possibility that the recording material will be burnt in the event of a jam.

[Brief Description of the Drawings] Figure 1A is a perspective view of a heat roller showing an embodiment of the fixing device of the present invention, Figure 1B is a sectional view showing the inside of the heat roller, and Figure 2 is a figure to which the fixing device of the present invention can be applied. FIG. 3A is a graph showing the relationship between the wavelength and emissivity of far infrared rays emitted from a heat source provided inside the heat roller, and FIG. 3B is a graph showing the relative radiation intensity of the heat source. FIG. 4 is a schematic sectional view showing an embodiment of the fixing device of the present invention, and FIGS. 5, 6, and 7 are explanatory diagrams showing other embodiments of the reflecting plate. . 13------Heat roller 14---One pressure roller 17---One temperature sensor 18.23, 24.25---One reflection plate' 131
--- Heat roller main body 132 --- Heat source 133 -- Gosho heating member 134 -- Gosho thermal insulator 135 --- Leet wire F --- Fixing device

Claims (4)

[Claims] (1) In a fixing device that fixes an object to be fixed on a recording material by passing the recording material between a pair of rotating bodies that are in pressure contact with each other, at least one of the rotating bodies has a heat source inside. and a radiating member that emits infrared rays with a wavelength of 2 μm or more from the surface, and by providing a reflecting member near this rotating body, the infrared rays radiated from the radiating member can be reflected and irradiated onto the recording material. Features a fixing device. (2) With respect to the pair of rotating bodies, the reflecting member is provided so that the amount of infrared rays reflected is greater on the recording material entry side than on the recording material discharge side. The fixing device according to scope 1. (3) The radiation member has a wavelength of 2 μm by being heated.
Claim 1, characterized in that infrared rays are emitted whose radiation intensity has one or more maximum values in the above region, and the emissivity of the infrared rays at the wavelength of the maximum value is 0.7 or more. Or the fixing device according to item 2. (4) The fixing device according to any one of claims 1 to 3, wherein the radiation member is made of a ceramic material.