JPH0376458B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for an image forming apparatus using an image forming method such as electrophotography or electrostatic recording.

A conventional fixing device includes a fixing roller that is heated by heat from a heat source, a pressure roller that is in pressure contact with the heating roller, and the like. However, a large amount of heat from the fixing load is lost through air conduction, which increases the temperature inside the image forming apparatus and requires extra heating source output.

JP-A-50-160039 discloses a configuration in which a reflective plate made of aluminum with good heat reflection and heat conduction is fixed around the fixing roller, and radiant heat from a heat source is supplied to the surface of the fixing roller. Disclosed. Further, in the same publication, a heat insulating material is provided on the outside of the reflector, separate from the reflector, and a cover 7 is provided in a fixed state in close contact with the heat insulator.

Since this device provides a heating source between the reflection plate and the fixing roller, heating efficiency is improved.

However, the reflector is provided solely for the purpose of reflecting heat. Therefore, although the heating efficiency is improved, the temperature of the surface of the fixing roller is not improved much.

On the other hand, the fixing roller and pressure roller side come into contact with supporting materials such as paper and visible images such as toner images.
Good thermal conductivity and good mold releasability are required, and the surface material is limited. As examples of the material, elastic materials such as silicone rubber and resins such as tetrafluoroethylene are often used.

However, this type of material is particularly susceptible to damage to thin supports such as paper in the event of a paper jam (so-called jam).

Such a paper jam occurs when a cover member such as the above-mentioned reflector plate is present on the circumferential surface of the fixing roller or the pressure roller, and the paper jam enters between the reflector plate and the roller. In other words, a supporting material such as paper enters between the reflecting plate and the fixing roller, and the supporting material is bent at that portion and overlaps to apply strong pressure to the surface of the fixing roller and the reflecting plate. Due to this pressure, the fixing roller and the pressure roller may be damaged or cut at sharp points such as the edges and bends of the supporting material. Furthermore, the reflective surface of the reflector may be damaged, which may disturb the heat reflection characteristics of the reflector, resulting in an unfavorable temperature distribution on the surface of the fixing roller.

Therefore, if this paper jam occurs around the rotating body having the cover member, the rotating body will be damaged by a slight pressure.

The present invention has been made in view of the above-mentioned problems, and aims to provide a highly durable fixing device that can ensure safety even against sudden failures. .

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram of an embodiment of the present invention. This figure shows a device in which a toner image T formed by electrophotography is fixed onto plain paper P by a heat fixing device.

1 is a heating roller having a heating heater 3 such as a halogen heater inside, and a driving motor (not shown).
It rotates in the direction of the arrow in response to the driving force from. 2 is a pressure roller with a built-in heater 3' for low heating;
It comes into pressure contact with the heating roller 1 and rotates slidingly.

This heating roller 1 has a heat-resistant mold release resin layer such as tetrafluoroethylene resin provided on the outer peripheral surface of a hollow roller core made of metal such as aluminum, stainless steel, or copper to a thickness of 20 to 80 μm.

The pressure roller 2 is rotatably supported by bearings 15, 15'. This roller 2 is brought into pressure contact with the heating roller 1 by a known pressure means at least during fixing, and is made of silicone rubber on the outer peripheral surface of a metal roller core.
It has a relatively thick layer of elastic material such as fluorosilicone rubber or fluorosilicone rubber. One purpose of this configuration is to secure a pressure contact area d with the heating roller.

A temperature sensing element 4 such as a thermistor or thermocouple is disposed in contact with the outer peripheral surface of the heating roller 1, and its detection signal is guided to a known control means (not shown) to control the temperature of the outer peripheral surface of the heating roller 1. The toner image melting temperature is maintained (by controlling the output of the heater 3 or the applied voltage, etc.).

6 is a cleaning member for removing foreign matter such as offset toner and paper powder adhering to the surface of the heating roller from the roller surface. A cleaning web ₆₁ made of a heat-resistant nonwoven fabric such as ) is used. The cleaning web 6 ₁ is brought into contact with the heating roller by an elastic extrusion roller 6 ₃ . Moreover, this web ₆₁ is given a drive (not shown)
The take-up roller 6 ₅ moves the cleaning web 6 2 from the supply roller 6 ₂ little by little to change its contact position, so that a new surface of the cleaning web 6 ₁ always comes into contact with the heating roller. This web 6 ₁ moves on the roller 6 ₄ interposed after the pressing roller 6 ₃ , is reversed toward the supply roller 6 ₂ , and is wound around the winding roller 6 ₅ with the front and back sides reversed. Also, during cleaning web 6 ₁ ,
If it is impregnated with an offset prevention liquid such as dimethyl silicone oil, the cleaning effect can be further enhanced.

Reference numeral 7 denotes a curved reflection plate having heat reflection properties, which is provided close to the periphery of the heating roller 1 and along the entire length of the heating roller 1. Further, the reflecting plate 7 has a width so as to cover the space between the position of the pressing roller 6 ₃ on the circumferential surface of the heating roller 1 and the entrance opening for the paper P. 8 is a thick cover for preventing heat radiation, and is provided in close contact with the entire convex surface of the reflector plate 7;
This prevents unnecessary heat radiation from the reflecting plate 7. 16
is a casing member on the upper side of the fixing device, which surrounds the cleaning member 6, the reflection plate 7, the cover 8, and the temperature sensing element 4.

On the other hand, on the pressure roller 2 side, a reflection plate 9 similar to the reflection plate 7 and a cover 10 similar to the cover 8 are provided so as to cover most of the circumferential surface of the pressure roller 2, respectively.

Reference numeral 27 denotes stoppers provided above both end regions of the heating roller 1. The stopper 27 is positioned so that the center of curvature of the reflector 7 and the cover 8 is the center of the heating roller _1. Hold. It is preferable that this distance l ₁ be larger than the thickness of the paper used and 10 mm or less from the standpoint of improving reflection efficiency.

On the other hand, the reflector 7 and the cover 8 are integrated, but are further rotatably supported about a rotation fulcrum 29, and are normally in stable contact with the stopper 27 due to their own weight.

Reference numeral 28 denotes stoppers provided below both end regions of the pressure roller 1. The stopper 28 is positioned so that the center of the curvature of the reflector 9 and the cover 10 is the center of the pressure roller 1, and the stopper 28 is located at a distance l ₂ between the reflector 9 and the pressure roller 2. hold. This distance l ₂ is similar to the distance l ₁ . Further, the reflection plate 9 and the cover 10 have a rotation fulcrum 24 at one end in the direction of the circumferential surface of the pressure roller, and a spring 2 latched to a fixing pin 23 ₁ at the other end.
One end of 3 is engaged. Due to this spring 23, the inner surface of the reflection plate 9 is brought into contact with the spherical surface of the stopper 28 with a predetermined pressure (light pressure).

By providing these reflective plates 7, 9 and covers 8, 10, it is possible to reduce wasteful heat from the surfaces of the heating roller and pressure roller, and to improve the temperature measurement performance of the temperature sensing element 4. can be stabilized. Furthermore, temperature control for the set temperature of the heating roller 1 can be stabilized and power consumption can be reduced.

22 is a guide plate that guides the paper P toward the heating roller 1 side;
It is provided close to the heating roller 1 so as to be located between one end of each of the reflecting plates 7 and 9. The plain paper P having the unfixed toner image T passes through the guide plate 22, is conveyed while being held between the heating and pressing rollers 1 and 2, and is heated by the surface temperature of the rollers 1 and 2. The toner image T is fixed, and then the paper is ejected from the apparatus while being held between paper ejection rollers 20 and 21. In order to reliably separate the plain paper P from the heating roller, a plurality of separating claws 5 are provided along the roller axis direction and in contact with the roller surface on the discharge port side of the heating roller.

Further, a separation claw ₅₁ is provided on the discharge port side of the pressure roller 2 so as to be in contact with the surface of the roller 2. The separation claw 5 is held by a support plate 18 that is spaced from the casing member 16, and the separation claw ₅₁ is also held by a support plate ₁₈₁ that is spaced from the casing member 17 on the lower side of the fixing device. The casing member 17 is spaced apart from the reflector 9 and cover 10 of the pressure roller 2 and is provided so as to cover them.

The reflective plates 7 and 9 are preferably made of a metal with a glossy surface, such as an aluminum plate with a polished surface, a copper plate, or an iron plate with a surface treatment such as Cr plating. The shape of the reflecting plates 7 and 9 is preferably one having a curvature concentric with the circumferential surface of the roller, and the thickness thereof is preferably relatively thin.

The covers 8 and 10 include glass wool,
Preferably, the material is made of rock wool, ceramic fiber, or a foam such as phenol foam or epoxy foam, or a composite material.

FIG. 2 shows a case where plain paper P is jammed on the pressure roller side.

When excessive pressure is applied between the pressure roller 2 and the reflection plate 9 due to a paper jam, the reflection plate 9 moves downward around the pivot point 24 (the gap between the pressure roller 2 and the reflection plate 9 The distance l ₂ ′ is greater than l ₂ )
To reduce the pressure applied to a pressure roller and a reflecting member. Therefore, damage to the pressure roller 2 and the reflection plate 9 can be prevented.

In the case of a paper jam on the heating roller side, damage is also prevented in the same way as above. When the paper enters between the heating roller and the reflecting plate 7, the reflecting plate 7, which rests on the stopper 12 due to its own weight, rotates about the pivot point 11 due to the presence of the paper. Therefore, the pressure applied to the heating roller 1 and the reflecting plate 7 can be reduced, and damage to the heating roller 1 and the reflecting plate 7 can be prevented.

Although the above embodiment shows a rotational movement about the rotational supports 24 and 29, it is not necessarily a rotational movement, and the reflection plate can be oscillated or movable, so that it can absorb pressure when an unreasonable external force is applied. Any item that can be moved in the direction of mitigation or that can be evacuated may be used.

Furthermore, when a paper jam is cleared, the reflective member is retracted from the roller surface while the paper is taken out, making the operation easy and ensuring safety. Further, when the paper jam is cleared and the paper is removed, the reflectors 7 and 9 are held at predetermined positions again by the spacers 27 and 28.

Therefore, the roller surface and the reflective member are not damaged by the pressure generated by the paper jam, and their properties can be maintained over a long period of time, and the reliability of the fixing device with good fixing performance can be increased.

FIG. 3 is an explanatory diagram of the cross section taken along the line X-X' in FIG. 1. Although the fixing device described below is particularly preferable for carrying out the present invention,
The present invention is not interpreted as being limited to these, but can be applied to various devices, various members, etc.

In the figure, 11 and 11' are heat-resistant sleeves fitted onto the rotating shaft ₁₁ of the heating roller 1, respectively.
They are in contact with bearings 12 and 12' mounted on frames 13 and 13' of the fixing device, respectively.
Heat-resistant gears 14 and 14' are fitted onto the rotating shaft ₁₁ of the heating roller 1, and transmit the driving force from the driving source M. This heat-resistant gear 14' meshes with another drive transmission gear 25, and rotates together with the heating roller 1 in response to driving force. The heat-resistant gear 14 includes
Gear 26 ₁ of manual knob 26 is engaged.

The heat-resistant sleeves 11, 11' further have heat-insulating properties and prevent heat loss from the heating roller 1-resistant portion. Therefore, heat transfer from the rotating shaft ₁₁ to the bearings 12, 12' and the frames 13, 13' is significantly reduced or almost eliminated. Furthermore, since the heat-resistant gears 14, 14' also have heat-insulating properties, the heating roller 1 can be connected to the gears 14, 1
4' to other drive transmission members such as gears.

Generally, the heat-resistant gears 14, 14' are often provided with a number of other drive transmission members in conjunction with each other. Therefore, conventional heat losses are predominant in such drive systems. In contrast, in the embodiments described above, heat loss to the drive system can be reduced or eliminated, so thermal efficiency can be greatly improved and power consumption can be reduced. In addition, in the above embodiment, the heat-resistant sleeves 11, 11' are used in addition to the heat-resistant gears 14, 14', so the frame 1
It is possible to prevent deformation of the rollers 3 and 13' due to heat and heat loss from the roller ends, and further improve thermal efficiency.

The heat-resistant sleeves 11, 11' are as follows:
polyimide, polyamideimide, polyamide,
It is preferable to use a heat-insulating material such as PPS (polyphenylene sulfide), PBT (polybutylene terephthalate) resin, or phenol resin, or a heat-insulating material made of this type of mixed material. . The gears 14 and 14' are made of a heat-resistant material with good heat insulation properties, such as polyimide, polyamide-imide, PPS, modified phenol, and tetrafluoroethylene with a filler added. preferable.

As mentioned above, the heating roller 1 is thermally isolated from the machine body and the frames 13, 13' by the heat-resistant sleeves 11, 11' and the heat-resistant gears 14, 14', and the heat is transmitted through these. , the heat loss will be very small.

Although the above embodiments and specific examples have been described with respect to a heating roller and a pressure roller, the present invention can be applied to members involved in recording material conveyance and fixing. From another point of view, the present invention is also applicable to image carriers such as photoreceptors that have a heat source.

Although the above embodiments have been described with reference to an internally heated fixing roller, the present invention can also be applied to a fixing roller having an external heating means or a member heated by conductive heat.

The above embodiment is a preferable example in which a heat-insulating sleeve is provided between the bearing and the heating roller in the part that rotatably supports the heating roller. It may be a sliding bearing, or a member or frame having heat-insulating properties may be used near the bearing.

The above-mentioned embodiments can be applied as long as supporting means having heat-insulating or heat-insulating properties are provided on members involved in fixing. More preferably, it is preferable to provide a heat-insulating support means near a heat-releasing part such as around the roller shaft or the roller itself.

In addition, in the above embodiment, the gear attached to the heating roller has a heat shielding property, but in the present invention, a connection system member or a drive system member of a member involved in fixing, such as a heating roller, has a heat shielding property. If it is, it is included. Further, it is particularly preferable to provide the fixing device near the member involved in fixing or on the member itself (not shown, but will become clear from this description).

Further, since the sleeve gear is constantly in contact with other members, it is preferable that the sleeve gear has wear resistance.

The other configurations according to this embodiment described above are necessary to enhance the original effects of cover members such as reflectors and heat insulating members because they can ensure effective use of heat.

By movably or rotatably supporting the reflector and cover as in the above embodiments, it is possible to easily remove jammed or wrapped support materials from rotating bodies such as heating and pressure rollers during jamming.

In the above embodiment, the reflector and cover are rotatable around one end of the cover, but the center of rotation (or movement) is located at the center of the reflector and cover, and is configured to be folded in two. It is also preferable that the rotation center is located at a location where the pressure during jamming can be easily absorbed, and it is more preferable that the center of rotation be located on the side of the support material inlet before the fixing process with respect to the entire fixing device.

By providing the heat reflecting member in two parts for the roller in this way, the presence of the support material during jamming can be easily known, and the support material can be taken out even more easily. Furthermore, since the rotation center axis is provided as a common axis for each of the divided heat reflecting members, the amount of movement of the heat reflecting members can be reduced, and the device can be made more compact.

The configuration of this embodiment can be applied not only to the heating roller but also to a cover member that is close to the circumferential surface of a pressure roller used in a pressure fixing device. The above embodiments are particularly effective when the heated rotating body is maintained in a thermally floating state, but are also effective when the covering member is placed close to the rotating body for the purpose of increasing thermal efficiency.

Furthermore, in each of the above embodiments, a combination of a (thermal) reflecting plate (member) or a cover for a reflecting plate has been described, but it is also possible to provide only a cover for preventing heat radiation around a rotating body such as a fixing roller (or belt). The present invention is applicable.

As is clear from the above description, in the present invention, since a movable or swingable covering member is provided on the conveying member, durability can be improved without damaging the covering member or the conveying member due to accidents such as clogging.
Furthermore, the operability of paper removal in the event of a paper jam has also become better.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of the paper jam in Fig. 1, and Fig. 3 is an explanatory diagram of an embodiment of the present invention.
It is an explanatory view of a −X′ cross section. 1 is a heating roller, 2 is a pressure roller, 3 and 3' are heaters, 4 is a temperature sensing element, 6 is a cleaning member,
7, 9 are reflectors, 8, 10 are covers, 11, 1
1' is a heat-resistant sleeve, 12, 12', 15, 1
5' is the bearing, 13, 13' is the frame, 14, 1
4' is a heat-resistant gear, 23 is a spring, 24 and 29 are pivot points, and 27 and 28 are spacers.

Claims (1)

[Scope of Claims] 1. A fixing device including a rotating pair, at least one of which is heated by a heat source, and a reflective member that covers at least a portion of the rotating body, wherein the reflective member is configured to prevent the recording material from clogging when the recording material becomes clogged. A fixing device characterized in that it is swingably supported so that it can be moved by pressure. 2. The fixing device according to claim 1, wherein the surface of the reflective member is a metal having a glossy surface.