JPS58159564A - Fixation device - Google Patents

Abstract

PURPOSE:To secure safety and to improve durability, by providing covers for covering part of the circumferential surface of a rotating body which conveys a recording material in a fixation device slidably and closely to the rotating body, and preventing the rotating body from damaging in case of paper jamming. CONSTITUTION:Normal paper P having an unfixed toner image T passes by a guide plate 22 and is conveyed while clamped between both heat and pressure rolls 1 and 2 to fix the image by heating by the surface temperature of the rolls 1 and 2. Between the heat roll 1 and pressure roll 2, the covers 8 and 10 specified by stoppers 27 and 28 so that they are held at distances l1 and l2 are supported rotatably around fulcrums 29 and 24 of rotation and, for example, if large pressure due to paper jamming is applied to between the pressure roll 2 and a reflecting plate 9 on the internal surface of the cover 10, the cover 10 moves down around the fulcrum 24 of rotation to prevent the pressure roll 2 and reflecting plate 9 from damaging.

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 heated by heat from a heating source, a pressure roller, etc. that presses against the heating roller. However, a large amount of heat from the fixing roller is lost through air conduction, which increases the temperature inside the image forming apparatus.
Also, extra heating source output was required.

Japanese Unexamined Patent Publication No. 50-160039 discloses a configuration in which a reflective plate made of aluminum with good heat reflection and heat conduction is fixedly provided around the fixing roller to supply radiant heat from a heat source to the surface of the fixing roller. ing. 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 has a heating source between the reflector and the fixing roller, the 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, so they are required to have good thermal conductivity and good release properties, so the surface materials are limited. It will be done. 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 support materials such as paper when paper jams occur.

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 cover member enters between the reflector plate and the roller. In other words, a support material such as paper enters between the reflection plate and the fixing roller,
The supporting material bends at that point, forming a pattern and applying 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 edges or bent portions of the support 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 a paper jam occurs around the rotary body having the cover member, the rotary 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.

A heating roller 1 has a heating heater 3 such as a halogen heater inside, and rotates in the direction of the arrow in response to driving force from a drive motor (not shown).

Reference numeral 2 denotes a pressure roller having a built-in heater 3' for low heating, which is brought into pressure contact with the heating roller 21 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 on a bearing 15.15'. This roller 2 is pressed against the heating roller 1 by a known pressure means at least during fixing, and has a relatively thick layer of elastic material such as silicone rubber, fluorosilicone rubber, or fluorosilicone rubber on the outer peripheral surface of a metal roller core. . 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 21, 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 Nomex cleaning member for removing foreign matter such as offset toner and paper dust attached to the heating roller surface from the roller surface.

Cleaning web 6 made of heat-resistant nonwoven fabric such as Himeron
1 is used. The cleaning web 61 is brought into contact with the heating roller by an elastic pressing row 263. Additionally, this web 61 is given a drive (not shown).
The take-up roller 65 moves the cleaning web 61 from the supply roller 62 little by little to change its contact position, so that a new surface of the cleaning web 61 always contacts the heating roller. This web 61 moves on rollers 64 that are interposed after the pressing row 263, is reversed toward the supply roller 6z side, and is moved onto the winding roller 65.
It is wound up with the front and back reversed. If the cleaning web 61 is still impregnated with an anti-offset liquid such as 1-dimethyl silicone oil, the cleaning effect can be further enhanced.

7 is a curved reflector having heat reflection properties, and heating roller 1
It is provided near the periphery of the heating roller 1 over the entire longitudinal direction 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 63 on the circumferential surface of the heating roller 1 and the entrance opening for the paper P. Reference numeral 8 denotes a thick cover for preventing heat radiation, which is provided in close contact with the entire convex surface of the reflecting plate 7 to prevent wasteful radiation of heat from the reflecting plate 7. 16 is a casing member on the upper side of the fixing device, which includes a cleaning member 6, a reflector plate 7. Cover 8. W& warm element 4 are surrounded.

On the other hand, a reflecting plate 9 similar to the reflecting plate 7 is also provided on the pressure row 22 side.
A cover 10 similar to the cover 8 is provided to cover most of the surface of the pressure roller 2.

Reference numeral 27 denotes stoppers provided above both end regions of the heating row 21. The stopper 27 is positioned so that the center of the curvature of the reflector 7 and the cover 8 is the center of the heating roller 1, and the stopper 27 maintains the distance KL between the reflector 7 and the heating roller 1. do. This distance 21 is larger than the thickness of the filter paper used, and is preferably 10 wm or less from the standpoint of improving reflection efficiency.

On the other hand, although the reflector 7 and the cover 8 are integrated,
These 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.
A distance Q2 between the pressure roller 2 and the pressure roller 2 is maintained. This distance 22
is the distance! It is similar to l. Further, the reflection plate 9 and the cover 10 have a rotation fulcrum 2 at one end in the circumferential direction of the pressure roller.
4, and one end of a spring phantom secured to the fixing pin 231 is engaged with the other end. This spring 23 applies a predetermined pressure of 1 pressure to the inner surface of the reflection plate 9 against the spherical surface of the stopper 28 .

(light pressure).

By providing the reflector 7.9 and the cover 8.10, it is possible to reduce the heat wasted from the surfaces of the heating roller and the pressure roller, and to stabilize the temperature measurement performance of the temperature sensing element 4. can be converted into 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, and a reflection plate 7
The heating roller 1 is provided close to the heating roller 1 so as to be located between one end of the reflecting plate 9 and the reflecting plate 9.

Plain paper P having an unfixed toner image T is placed on this guide plate 2.
The toner image T is fixed by the applied heat due to the surface temperature of the rows 21 and 2, and then the toner image T is transferred to the device while being held between the paper discharge rollers 20 and 21. Expelled outside. In order to reliably separate the plain paper P from the heating roller, a plurality of separation claws 5 are provided along the roller axis direction and in contact with the roller surface on the heating roller discharge port side.

Also, a separating claw 51 is provided on the discharge port side of the pressure roller 2.
is placed in contact with the surface of the 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. Casing member 1
7 is spaced apart from the reflecting plate 9 and cover 10 of the pressure roller 2, and is provided so as to cover these.

The reflecting plate 7.9 is preferably made of a metal with a glossy surface, such as aluminum with a polished surface, a steel plate with a surface treatment such as chromium plating, or the like. Further, 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 above-mentioned cover 8.10 may be made of glass wool, rock wool, ceramic fiber or phenolic foam,
It is preferable to use a foam such as epoxy 7 ohm or a composite structure.

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

Due to paper jamming, excessive pressure I (applied to the force between the pressure row 22 and the reflection plate 9 causes the reflection plate 9 to move towards the pivot point 24).
centering on , the pressure applied to the pressure roller and the reflection member is reduced (the distance 12' between the pressure roller 2 and the reflection plate 9 becomes 2). 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 loaf 1 and the reflecting plate 7 can be reduced, and damage to the heating roller and the reflecting plate 7 can be prevented.

Although the above embodiment shows rotational movement around the rotational fulcrums 24 and 29, it does not necessarily have to be rotational movement, and the reflection plate
It may be of any type as long as it is swingable or movable, and that it can move in a direction to reduce pressure or retreat when an excessive external force is applied.

Further, when clearing a paper jam, the reflective member can be removed from the surface of the row 2 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 reflective plate 7.9 is again held at a predetermined position by the spacers 27, 28.

Therefore, the roller surface and the reflective member are not damaged by the pressure generated by the paper jam, and their characteristics can be maintained for 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 xx' cross section in FIG. 1. Although the fixing device described below is particularly preferred in carrying out the present invention, the present invention is not limited to these and can be applied to various devices and various members. .

In the figure, 11 and 11' are the rotating shafts 1 of the heating roller 1, respectively.
1 and the bearings 12.1 respectively mounted on the frame 13.13' of the fixing device.
2' respectively. 14. 14' is a heat-resistant gear, and is the rotating shaft 1 of the heating roller 1! The drive force from the drive source M is transmitted to the drive source M. This heat-resistant gear 14' meshes with another drive transmission gear 25, and rotates together with the heating row 21 in response to the driving force.

A gear 261 of a manual knob 26 is meshed with the heat-resistant gear 14.

The heat-resistant sleeve 11,11' further has heat-insulating properties and prevents heat loss from the heating roller 1-resistant portion. Therefore, heat transfer from the rotating shaft 11 to the bearings 12, 12' and the frame 13, 13' is greatly reduced and almost eliminated. Furthermore, since the heat-resistant gear 14.14' also has heat-insulating properties, heat is not dissipated from the heating roller 1 to other drive transmission members such as gears via the gear 14.14'.

Generally, the heat-resistant gear 14, 14' is often provided with a number of other drive transmission members so as to be interlocked therewith. Conventional heat losses are therefore 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. or,
In the above embodiment, the heat-resistant sleeve 11.11' is used in addition to the heat-resistant gear 14.14', so that the frame body 13°1
3' due to heat and heat loss from the roller ends can be prevented, and thermal efficiency can be further improved.

The heat-resistant sleeve 11.11' may be a heat-insulating material made of polyimide, polyamide-imide, polyamide, pps (polyphenylene sulfide), PBT (polybutylene terephthalate) resin, phenol resin, etc., or a mixture of such materials. It is preferable to use a material made of a heat-insulating material. Also, the above gear 14.14
'As polyimide, polyamideimide.

It is preferable to use a heat-resistant material with good heat shielding properties, such as pps, modified phenol, or tetrafluoroethylene with a filler added.

As mentioned above, the heating roller 1 includes a heat-resistant sleeve 11.
1r and the heat-resistant gears 14, 14' are thermally isolated from the machine body and the frame 13, 13', and the heat loss transmitted through these is extremely small.

The above embodiments and specific examples are explained as heating rollers.

Although the pressure roller has been described, the present invention can also 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 embodiment describes an internally heated type fixing row 2, the present invention can also be applied to a device having an external heating means or a member heated by conductive heat.

In the above embodiment, a bearing and a heating roller are used for the part that rotatably supports the heating roller, but it is also possible to use a sliding bearing in which the bearing itself has a heat-insulating property, or a heat-insulating part near the bearing. It is also possible to use a member or a frame that has properties.

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 at a location close to a heat-releasing portion, 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. Furthermore, a device provided near the member involved in fixing or itself (not shown),
(which becomes clear from this number) is particularly preferable.

Furthermore, since the sleeve and gear are constantly in contact with other members, it is preferable that they have 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.

As in the above embodiment, by movably or rotatably supporting the reflector and cover, heating can be achieved in the event of a jam.

Support materials that are clogged or wrapped around can be easily removed from a rotating body such as a pressure roller.

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 or cover and is configured to be folded in two. (See Figure 4).

Further, the center of rotation is preferably located at a location that can easily absorb the pressure in the event of a jam, and it is more preferred 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.

The configuration shown in FIG. 4 will be briefly explained.

Heat reflecting members 7a and 7b are provided around the heating row 21 containing the heater 3 in the axial direction so as to cover the peripheral surface of the roller, and around the pressing row 22 in the axial direction. Heat reflecting members 9a and 9b are provided close to and covering the circumferential surface of the roller.

The heat reflecting members 7a and 7b are supported rotatably about a common rotation center axis 29a, and spacers 27a and 2
7b (fixed and supported by a stationary part of the device: not shown)
They are separated from the surface of the heating/row 21 by a predetermined gap d, respectively. The spacers 27a and 27b are located outside the area through which the largest size paper passes in the axial direction of the heating roller, and are in contact with both ends of the heat reflecting members 7a and 7b in the axial direction. Also, heat reflecting members 7a, 7
In this state, b is arranged concentrically with the roller surface with respect to the center of the heating roller. The heat reflecting members 7a and 7b have such weight that they can be easily escaped upward by the introduction of a supporting material such as paper, and are normally in contact with the spacers 27a and 27b, respectively, due to their own weight.

The heat reflecting members 9a and 9b are each rotatably supported about a common rotation center axis 29a. In the state shown in the figure, the members 9a + 9b are held in a concentric relationship with the roller surface (gap d/) with respect to the center of the pressure roller.

The holding means is the heat reflecting member 9a at a predetermined pressure or higher.

It is sufficient that the roller 9b is configured to be able to move further away from the roller surface from the position of the gap d' when the roller 9b is pressed. An example of this is shown in FIG. 23a
, 23b is a cam rotatable at a predetermined position, and its curved surface having a normal curvature r is in contact with the heat reflecting member 9a + 9b to maintain the above-mentioned gap d'.

The cams 23a and 23b have one end fixed to a fixed part provided above, and the other end to the cam 23a.

A force corresponding to the predetermined pressure is applied upward by springs 231a and 231b, which are respectively fixed to 23b.

PI and pg are stoppers, and heat reflecting members 9a and 9b
cam 2 so that it is no closer to the roller surface than the gap d'
3a and 23b are prevented from rotating. P3. P4 is a stopper having an elastic body on its surface, and includes a heat reflecting member 9a,
When the cam 9b is jammed, the cam 23a receives a force exceeding a predetermined pressure.
, 23b, the heat reflecting member 9a.

Determine the maximum opening amount of 9b.

Since the heat reflecting member is divided into two parts and provided on the roller in this way, the presence of the support material can be easily detected in the event of a jam, and the support material can be taken out even more easily. Further, since the rotation center axis is provided as a common axis for each of the divided heat reflecting members, the moving door of the heat reflecting member can be made smaller, and the apparatus can be made more compact.

The configuration of this embodiment can be applied not only to the heating roller but also to a concave member 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 kept in a thermally floating state, but are also effective when the cover member is brought close to the body for the purpose of increasing thermal efficiency.

Furthermore, in each of the above embodiments, a (thermal) reflecting plate (member) or a combination of a reflecting plate and a cover was explained, 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 was also improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the paper jam in Fig. 1, Fig. 3 is an explanatory diagram of the XX cross section of Fig. 1, and Fig. 4 is an explanatory diagram of the paper jam in Fig. 1. FIG. 6 is an explanatory diagram of another embodiment of the invention. ■ is a heating roller, 2 is a pressure roller, 3.3' is a heater,
4 is a temperature sensing element, 6 is a cleaning member, 7.9 is a reflector, 8.10 is a cover, n and tr are heat resistant sleeves, 12
．． 12', 15.15' are bearings, 13.13'
is a frame body, 14.14' is a heat-resistant gear, 23 is a spring, 24
．． 29 is a rotation fulcrum, 27.28 is a spacer.

Claims (1)

[Claims] A fixing device that fixes an unfixed image onto a recording material includes a rotating body that conveys the recording material, a member that covers at least a portion of the circumferential surface of the rotating body and is close to the rotating body, and a member that swingably supports the member. A fixing device comprising means.