JP2002351243A - Fixing device and image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To alleviate the temperature rise in the non-sheet-passing portion without hindering productivity and without increasing costs or complicating the structure. Provided are a fixing device and an image forming apparatus which prevent instability of paper feeding, jam, and the like due to a difference in outer diameter, and have high thermal efficiency. SOLUTION: A high thermal conductive rubber composite layer 20 is provided on a pressing member 2.
4 are formed integrally so that the thermal conductivity of the high thermal conductive rubber composite layer 204 has anisotropy, and the heat flow in the direction intersecting the recording material conveyance direction is larger than the heat flow in other directions. To
Either anisotropic heat flow on the surface of the pressing member, or a high thermal conductive rubber composite layer is integrally formed on the pressing member,
Furthermore, a heat insulating cover is separately provided outside the pressure member, and the heat flow in the direction intersecting the recording material conveyance direction is made larger than the heat flow in the other direction by the heat insulating cover. Causes anisotropy in the heat flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as an electrophotographic copying apparatus and an electrostatic information recording apparatus, and a fixing device provided therein.

Here, as an image forming apparatus, for example,
Copiers, laser beam printers, facsimile machines, microfilm reader printers, etc. are included.

[0003] The fixing device uses an electrofax sheet, an electrostatic recording sheet, a transfer material sheet, a toner made of a resin which is heat-soluble by an appropriate image forming process means of electrophotography, electrostatic recording, and magnetic recording. A permanent fixed image is formed on the surface of a recording material, such as a printing paper, carrying a visible image (unfixed developer image) corresponding to the target image information, formed directly or indirectly (transferred) on the surface of the recording material. It can be utilized as an image fixing device for performing a heat fixing process.

[0004]

2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus, an unfixed developer image (unfixed toner image) is fixed on a recording material by heating and pressing an unfixed toner image on the recording material. Heat roller system
For example, there is a film fixing method as described in JP-A-313182 and JP-A-2-1577878.

In these fixing devices, a fixing member such as a cylindrical fixing roller or a fixing film rotatably provided around a heater, which is a fixed heating device, and a pressing roller pressed against the fixing member. The recording material is sandwiched and conveyed between the recording material and the pressing member, and the unfixed toner image on the recording material is heated and pressed to fix the toner image.

On the other hand, with respect to the problems of power saving and shortening of the wait time, which have attracted attention in recent years, in these fixing devices, a method of shortening a warm-up time by thinning a fixing roller or the above-mentioned film fixing method has been proposed. We take measures such as.

However, when such a method is used,
When small-size recording paper is continuously passed, a problem caused by a so-called non-paper-passing portion temperature increase occurring at the end portions of the fixing roller and the pressure roller becomes a serious problem.

As a problem of the temperature rise of the non-sheet passing portion, wrinkles and offset of the fixing roller and an image defect due to the wrinkle and the offset, and the temperature rise of the non-sheet passing portion of the pressure roller cause a non-sheet passing portion on the surface of the pressure roller. The high-temperature portion at the end in the longitudinal direction thermally expands, causing a difference in the outer diameter of the pressure roller itself, causing various problems such as instability of paper feeding and jamming.

Therefore, conventionally, in order to prevent the temperature of the fixing roller (or the fixing film) from rising in the non-passing portion when the small-size paper is fed, a plurality of fixing rollers (or fixing films) are provided inside the fixing roller according to the size of the feeding paper. The arranged heaters were switched and used.

[0010] However, switching between a plurality of heaters according to the size of the paper to be fed and using the heaters increases the cost, complicates the control, or does not sufficiently cope with all the sizes. Have difficulty. Also, this method
It is effective in raising the temperature of the fixing roller or the end of the fixing film, which is a non-sheet passing portion, but may not be enough to prevent the end of the pressing roller from raising the temperature.

Therefore, there has been proposed a method in which a member having good heat conductivity is brought into contact with a fixing roller or a pressure roller as a cleaning member to reduce the temperature rise in the non-sheet passing portion, that is, in the edge portion.

As a measure for preventing the temperature from rising in the non-sheet passing area, a method of lowering the temperature control temperature depending on the size, a method of lowering the temperature after copying a certain number of copies, and the like have been proposed.
It has also been proposed to increase the copying interval when a small-sized sheet is detected.

[0013]

However, the above-mentioned prior art has the following problems.

It is not desirable to increase the copying interval or printing interval when the size is small, since this will reduce productivity.

The method of contacting a fixing roller or a pressure roller with a roller having good thermal conductivity as a cleaning roller has problems in that the structure is complicated and an arrangement space is required. Further, when a roller having good heat conductivity is brought into contact with the pressure roller, there is also a problem that the heat transfer from the pressure roller side is increased, so that the fixing property is slightly impaired.

Accordingly, an object of the present invention is to alleviate the temperature rise in the non-sheet-passing portion without hindering productivity and without increasing the cost or complicating the structure.
It is an object of the present invention to provide a fixing device and an image forming apparatus which prevent instability of paper feeding due to a difference in outer diameter of a pressing member, jam, and the like, and have high thermal efficiency.

[0017]

The above object is achieved by a fixing device and an image forming apparatus according to the present invention. In summary, a first aspect of the present invention includes a pressing member and a fixing member provided with a heating unit, and presses a recording material carrying an unfixed developer image onto the pressing member and the pressing member. In a fixing device, the fixing device heats and fixes the unfixed developer image on a recording material by nipping and conveying the nip portion with the fixing member interlocking, a high thermal conductive rubber composite layer is integrally formed on the pressing member. The pressure member so that the thermal conductivity of the high thermal conductive rubber composite layer has anisotropy and the flow of heat in the direction intersecting the recording material conveyance direction is larger than the flow of heat in the other direction. Provided is a fixing device that causes anisotropy in heat flow on a surface.

According to a second aspect of the present invention, a recording material having a pressing member and a fixing member provided with a heating means is held while pressing a recording material carrying an unfixed developer image against the pressing member. In a fixing device, the fixing device heats and fixes the unfixed developer image on a recording material by nipping and conveying the nip portion with a nip portion with the interlocking fixing member.
Forming a high thermal conductive rubber composite layer integrally with the pressing member,
Further, a separate heat-insulating cover is provided outside the pressing member, and the heat-insulating cover makes the heat flow in the direction intersecting the recording material conveying direction larger than the heat flow in the other direction. Provided is a fixing device that generates anisotropy in heat flow on the surface of a pressure member.

According to a third aspect of the present invention, an unfixed developer image is formed on a recording material by external information, and the image forming apparatus includes a pressing member and a fixing member provided with a heating unit. An image forming apparatus that heats and fixes the unfixed developer image on a recording material by nipping and conveying a recording material carrying A high thermal conductive rubber composite layer is integrally formed on the pressing member, the thermal conductivity of the high thermal conductive rubber composite layer has anisotropy, and heat flow in a direction intersecting the recording material conveyance direction is reduced. Provided is an image forming apparatus that generates anisotropy in the heat flow on the surface of the pressing member so that the heat flow is larger than the heat flow in the other direction.

According to a fourth aspect of the present invention, there is provided an unfixed developer image formed on a recording material by external information, comprising a pressing member and a fixing member provided with a heating means. An image forming apparatus that heats and fixes the unfixed developer image on a recording material by nipping and conveying a recording material carrying A high thermal conductive rubber composite layer is integrally formed on the pressing member, and a separate heat-insulating cover is provided outside the pressing member, and the heat-insulating cover allows heat in a direction intersecting the recording material conveying direction. An image forming apparatus, wherein an anisotropy is generated in the heat flow on the surface of the pressure member so that the flow of heat is larger than the flow of heat in the other direction.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fixing device and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 In this embodiment, the present invention
This is embodied in an image forming apparatus having a heat fixing device 106 shown in the schematic configuration diagram of FIG.

FIG. 12 shows, for example, the configuration of an electrophotographic copying machine as an image forming apparatus. A charging roller 102, a developing device 103, and a transfer device 104 are provided around a photoreceptor 101. In the vicinity of the transfer device 104, the transport unit 10
5 is provided, and a fixing device 106 is provided downstream of the transport unit 105.

Accordingly, when the recording material is fed from a paper feeding cassette (not shown) and the leading end of the recording material is recognized in the image forming apparatus, an image is formed on the photosensitive drum 101 in synchronization with the recognition. A charging roller 102 is provided on the photosensitive drum 101.
Thus, uniform charging is performed. Thereafter, a latent image is formed on the photosensitive drum 101 in synchronization with the conveyance of the recording paper by image exposure L which is image information from the laser optical system 100, and a developer (toner) is formed on the latent image by the developing device 103. ) Selectively forms a visible image as an unfixed developer image (toner image). The recording material on which the toner image of the photoconductor 101 has been transferred at the position of the transfer device 104 is sent to the fixing device 106 via the transport unit 105, and passes through the fixing device 106, so that the toner image is heated on the recording material. Be established.

The toner and paper dust remaining on the photosensitive drum 101 are removed by the cleaner 107.

The configuration of the image forming apparatus is shown in FIG.
The present invention can be applied not only to the above-described one but also to a color image forming apparatus having a plurality of photoconductors and developing devices, for example. The image forming apparatus can be applied to an image forming apparatus such as an electrophotographic copying apparatus and an electrostatic information recording apparatus, for example, a copying machine, a laser beam printer, a facsimile, a micro film reader printer, and the like.

Next, an example of the fixing device of the present invention embodied as the fixing device 106 in the image forming apparatus of FIG. 12 will be described in detail. 2 and 3 show the fixing device A of the present embodiment.

FIG. 2 is a plan view of the fixing device A as viewed from the lateral direction. As described above, the fixing device A includes the fixing roller 1 as a fixing member having the heater H as a heating unit,
And a pressure roller 2 as a pressure member. The fixing roller 1 and the pressure roller 2 are rotatable, and press-contact to form a nip portion N. The recording material on which the unfixed toner image is formed is nipped and transported at the nip portion N to record the toner image. Heat and fix on the material.

More specifically, the fixing roller 1 of the fixing device A is formed of an iron core of about 0.5 to 1 t or 0.8 to 2.5 t.
To about AL core metal, heat resistance, abrasion resistance, fluororesin excellent in mold release, PTFE, PFA, FEP, or a mixture of these fluororesins was mixed with an abrasion-resistant filler or a resistance adjuster This is a thin-walled roller formed by coating a fluororesin paint to a thickness of 15 to 40 μm or covering the above-mentioned cored bar with these fluororesins. Fixing roller 1
As shown in FIGS. 2 and 3, a heater H for heating the fixing roller 1 is supported at both ends by members (not shown).

The pressure roller 2 is provided between the fixing roller 1 and the nip N
And pressurizes the recording material nipped and conveyed by the nip N. As shown in FIG. 1B, the pressure roller 2 has a thick elastic layer 203 (3 to 3) around a cored bar 201.
(About 6 mm).

FIG. 3 is a plan view of the fixing device A in the longitudinal direction. At both ends of the fixing roller 1, heat-resistant heat-insulating sliding bearings 5 that rotatably support the roller 1 are provided. The bearing 5 may be a bearing in which a heat insulating bush is interposed between the bearing 5 and the fixing roller 1. A heat-insulating gear 6 for driving the fixing roller 1 is further outside the bearing 5.
Is provided on at least one end, and the fixing roller 1 is rotated at a predetermined speed by a driving unit (not shown). Bearing 5
Is fixed by a side plate 7 supporting this, and a top plate 8 provided in the longitudinal direction above the fixing roller 1 connects the side plates 7 at both ends. A temperature detecting element 9 and a safety device 10 are attached to the top plate 8 to detect the temperature of the fixing roller 1. In accordance with the temperature detected by the temperature detecting element 9, the heater H is controlled to maintain the fixing roller 1 at a predetermined temperature, and the unfixed toner image on the recording material is fixed at the fixing temperature. The control method and the like can be controlled based on a known method,
The description is omitted because it is not characteristic of the fixing device of the present invention.

The pressure roller 2 is rotatably supported at both ends by bearings (or bearings) 11 similarly to the fixing roller 1. The bearing 11 is supported by a pressing side plate 12 which is provided inside the extension of the fixing roller side plate 7 on the side of the pressing roller 2, and the shaft 13 supports the pressing side plate 12 and the fixing roller side plate 7. . As can be better understood with reference to FIG. 2 as well, a pressure spring 14 is provided on the opposite side of the shaft 13 to lift the pressure side plate 12 and press the pressure roller 2 against the fixing roller 1. I have.

The structure of the pressure roller 2, which is a characteristic part of the present invention, will be described with reference to the cross-sectional view of the pressure roller 2 shown in FIG. The pressure roller 2 has an elastic layer 203 having excellent rubber elasticity at high temperature on an iron core 201.
, And a high thermal conductive layer 204 is further provided thereon, and a highly releasable layer 205 is formed on the outermost layer.

The core 201 is made of an inexpensive and sufficiently strong metal material such as iron and steel, and is plated as needed. When the pressure roller 2 is pressed against the fixing roller 1, An appropriate outer shape is provided so that bending does not occur due to the pressing force. Also, both ends in the longitudinal direction of the cored bar 201 have a smaller diameter 202 so that the frictional force during rotation is reduced.

The elastic layer 203 has a heat insulating property, heat resistance and
Silicone rubber or fluorine rubber is often used to function as an elastic layer, but silicone rubber foam sponge is preferably selected. Silicone rubber foam sponge is generally obtained by adding a vulcanizing agent and various foaming agents to a silicone rubber composition containing an organopolysiloxane, a reinforcing filler, a bulking agent, a heat-resistant agent, and vulcanizing and foaming in a heating furnace. The silicone rubber foam sponge having desired performance can be obtained by appropriately setting these manufacturing conditions. When a normal silicone rubber foam sponge is used as a roller, if it is too thick, the compression set of the silicone rubber foam sponge and the outer shape change due to thermal expansion increase. And if it is thin, it will not be possible to take the desired heat insulation and nip,
For rollers with an outer diameter of about 25 mm to 50 mm, 3 mm to 6 mm
A sponge layer thickness of about mm is appropriate.

In the present embodiment, the pressure roller 2 using an anisotropic high thermal conductive rubber composite is used for the high thermal conductive layer 204 directly under the thin release layer 205 on the outermost layer. The heat flow in the longitudinal direction of the roller was improved, and the temperature rise of the fixing roller 1 and the pressure roller in the non-sheet passing portion, that is, the temperature rise in the end portion was suppressed.

FIG. 1A is a partial longitudinal sectional view showing a part of one side of the axis of the pressure roller 2. As shown in FIG. 1, the high thermal conductive layer 204 is used to improve thermal conductivity.
As shown in (a), an anisotropic high thermal conductive rubber composite is used for the high thermal conductive layer 204. This anisotropic high thermal conductive rubber composite has a high thermal conductive fiber 20 of 60 to 1200 W / m · K.
Since 4a is contained in an amount of 1 to 70 wt%, the thermal conductivity is good, and the thermal conductivity is 50 to 1000 W / m · K. When the thermal conductivity is 50 W / m · K or more, the temperature rise at the end can be sufficiently suppressed. The higher the thermal conductivity is, the better, but it is difficult to produce a material with 1000 W / m · K or more at present.

Further, the thermal conductivity of the high thermal conductive fiber 204a shows anisotropy as a single substance, and the thermal conductivity measured in the fiber axis direction is 100% of the thermal conductivity measured in the other direction.
Times to 1000 times or more. This high heat conductive fiber 204a
By applying the anisotropic high-thermal-conductivity rubber composite obtained by aligning in one direction to the pressure-roller high-thermal-conductivity layer 204, the heat causes the pressure roller cylinder 2 to move in the longitudinal direction, that is, at the end portion. The flow in the direction to eliminate the temperature, the flow in the cylinder radial direction, that is, the flow in the circumferential surface direction of the pressure roller 2, the inside of the cylinder, and the outside of the cylinder can be suppressed, and the heat efficiency of the fixing becomes good, and the high fixing property is maintained. it can. Note that, as shown in FIG. 1A, the anisotropic high heat conductive rubber
a is provided such that the fiber axis direction is parallel to the longitudinal direction of the pressure roller 2. Further, a release layer 205 having a release agent applied thereon was formed thin.

The high thermal conductive layer 204 will be further described. As disclosed in JP-A-11-302545, the use of pitch-based graphitized carbon fiber as the high thermal conductive fiber 204a has very good thermal conductivity, and
A highly anisotropic rubber composite can be produced. In this example, a silicone rubber composite containing pitch-based graphitized carbon fibers 204a having a thermal conductivity of 600 W / m · K and containing 15% to 45% by volume was prepared and used.

This silicone rubber composite is applied to a pressure roller 2
When forming the high thermal conductive layer 204, it is important that the pitch-based graphitized carbon fibers 204a are aligned so as to be parallel to the longitudinal direction of the roller 2, that is, perpendicular to the cylindrical cross section. In the present embodiment, the anisotropic high thermal conductive silicone rubber composite layer 204 was formed to a thickness of 1 mm.

4 pitch-graphitized carbon fibers 204a
In the case of the silicone rubber composite layer 204 containing 5%,
The thermal conductivity in the fiber axis direction is 260 W / m · K, and 0.2 W / m · K in the fiber radial direction, and the directional ratio is 13 W / m · K.
00. In the case of a silicone rubber composite containing 15%, the thermal conductivity in the fiber axis direction is 107 W / m · K and 0.1 in the fiber radial direction (a direction intuitive to the fiber axis direction).
9 W / m · K, and its directional ratio is 563.

Therefore, the high thermal conductive layer 204 has a difference in directional ratio of 500 to 1500 represented by (thermal conductivity in a direction parallel to the fiber axis direction) / (thermal conductivity in a direction perpendicular to the fiber axis direction). Created to have anisotropy. If the direction ratio is less than 500, heat flows from the nip to the entire surface of the pressure roller, and heat radiation from the pressure roller increases, resulting in a fixing device that is contrary to energy saving, and the fixing performance is impaired. Become. Also, it is difficult to manufacture a product larger than 1500.

Here, the fiber axis direction is aligned with the longitudinal direction of the pressure roller 2, that is, the direction intersecting the conveying direction of the recording material conveyed by the fixing device. Therefore, in the pressure roller 2, the thermal conductivity of the high thermal conductive layer 204 shows a high thermal conductivity in a direction intersecting the recording material conveyance direction, and the other direction is a circle of the pressure roller 2. It shows lower thermal conductivity in the circumferential direction and in the radial direction.

Therefore, the heat can easily flow in the longitudinal direction of the pressure roller 2, so that the temperature rise at the end of the pressure roller can be avoided. Can be prevented, and no fixing failure occurs.

In addition, since the heat conductivity of the pressure roller 2 itself is increased, it is not necessary to provide a roller or the like having good heat conductivity around the pressure roller 2, thereby preventing the structure of the image forming apparatus from becoming complicated and increasing the cost. Can be.

Next, in order to explain the present invention in more detail,
A case where the fixing device A is incorporated in an image forming apparatus will be described using an experimental example.

EXPERIMENTAL EXAMPLE 1 As an image forming apparatus, an A4 size copy was printed at 30 minutes per minute.
We used a copier that can take out sheets. At this time, a fixing device B having the same configuration as that described with reference to FIGS. 2 and 3 except that a pressure roller 2 ′ having a conventional configuration as described below is attached as the fixing device, and a first embodiment will be described. Pressure roller 2 of FIG.
Was prepared.

Fixing Device B The outer diameter of the fixing roller 1 is 32 mm, the core metal is the outer diameter of 2 mm for AL, and the surface layer of the fixing roller 1 is a fluororesin PTFE25.
μm clothing, paper width of fixing roller 1 320 mm, heater wattage 900 W, peripheral speed of fixing roller 1 is 180 mm /
s, pressure roller 2 'outer diameter 30mm, pressure roller 2' core diameter 18mm, silicone rubber sponge thickness 6mm, pressure roller 2 'surface layer tube PFA 50µm Fixing device A fixing roller 1 outer diameter 32mm, core metal is AL 2mm,
The surface layer of the fixing roller 1 is coated with a fluororesin PTFE 25 μm, the paper width of the fixing roller 1 is 320 mm, the heater wattage is 900 W, the peripheral speed of the fixing roller 1 is 180 mm / s, the outer diameter of the pressure roller 2 is 30 mm, and the core diameter of the pressure roller 2 is 18 m.
m, silicone rubber sponge thickness 5mm, high thermal conductive layer 1m
m, pressure roller 2 surface layer tube PFA 50 μm The manufacturing procedure of the pressure roller 2 used in the fixing device A is in accordance with the following (1) to (5).

(1) The pitch-based graphitized carbon fiber 204a is cut into a predetermined length into a cylindrical mold for forming a predetermined tube shape, and the fiber axis direction intersects the recording material conveyance direction, that is, Arrange them so that they are parallel to the longitudinal direction of the tube.

(2) A silicone rubber base material is poured into the mixture, and the mixture is cured, so that the anisotropic high heat conductive silicone rubber composite is formed into a tube shape to prepare a silicone tube to be the high heat conductive layer 204.

(3) This anisotropic high heat conductive silicone tube is prepared to have a predetermined thickness (1 mm), and an adhesive is applied to the inside of the tube.
Insert the sponge roller into which is inserted.

(4) The inner surface of the tube is subjected to an inner surface treatment for enhancing the adhesive strength by a known method, and a PFA tube serving as a release layer 205 coated with an adhesive is fitted to the outside of the tube.

(5) Finally, it is manufactured by heat bonding.

The fixing devices A and B were mounted on a copying machine capable of producing 30 sheets of A4 size copy per minute, and the temperature rise of the non-sheet passing portion was examined.

Here, the temperature detecting element 9 for detecting the fixing temperature of the fixing roller 1 is provided in a region where recording paper of any size passes in the longitudinal direction of the fixing roller 1. In FIG. 4, it is located at a position B near the left end in the longitudinal end portion of the region.

FIG. 4 is a diagram showing the positional relationship between the temperature measuring points A to F, the recording paper, and the fixing roller 1 in the longitudinal direction when viewed from above in this experimental example. The temperature detecting element 9 is, as shown in FIG.
4, the components other than the fixing roller 1, the recording paper, and the temperature detecting element 9 are omitted in FIG.

As shown in FIG. 4, the recording paper used in this experimental example is passed so that the end of the recording paper is located on the front side (left side in FIG. 4) of the paper passing area of the fixing roller 1. This is a corner registration type based on the front side of the image forming apparatus. The pressure roller 2 is located at a position overlapping the fixing roller 1.

The temperature distribution was measured by setting a plurality of points evenly in the longitudinal direction of the fixing devices A and B from the front side to the back side of the image forming apparatus, and contacting each of the points with a thermocouple. Here, each point measured is shown in FIG.
From the front side to the back side of the image forming apparatus, A,
The fixing roller 1 is positioned at positions indicated by B, C, D, E, and F.
Is installed on the surface other than the nip portion N with the pressure roller 2 on the same straight line in the longitudinal direction. Since the temperature detecting element 9 is located in the vicinity of B, the point A is located closer to the front than the temperature detecting element 9.

FIG. 5 shows points A to A in the longitudinal direction of the roller 1 when 200 sheets of B5R size are continuously copied.
An example of the temperature distribution of F is shown. The horizontal axis indicates the position of each point by the length from the longitudinal end of the fixing roller 1. As shown here, as a result of the temperature measurement at each point, the temperature at the point E at the far end, which is the non-sheet passing area, was the highest among the points.

FIG. 6 shows the temperature transition at the point E when 0 to 200 sheets are passed. The mark ● indicates the result of the fixing device B as a conventional example when B5R is sent at a copy speed of 30 sheets per minute. As shown in FIG. 6, when the number of sheets reaches 150 or more, the temperature at point E exceeds 240 ° C. On the other hand, the results when the fixing device A according to the embodiment of the present invention is used are shown by □.
Indicated by the mark. As shown here, the temperature at the point E dropped significantly as compared with the fixing device B. From the above results, by using the pressure roller using the anisotropic high thermal conductive rubber composite for the high thermal conductive layer, the flow of heat in the longitudinal direction of the roller is improved, and the temperature rise in the non-paper passing portion can be suppressed. In addition, there was no problem in the results of the fixing test.

The temperature distribution of the pressure roller 2 itself is smaller than that of the fixing roller 1, so that the temperature rise of the non-sheet passing portion is
Further, since it is smaller than that of the fixing roller 1, the pressure roller 2
Due to the temperature rise of the non-sheet passing portion, the difference in the outer diameter of the pressure roller 2 itself caused by the thermal expansion of the high temperature portion of the non-sheet passing portion is reduced, and the paper feeding is stabilized.

In this embodiment, the pitch-based graphitized carbon fiber made of a fibrous high heat conductive material is used. However, the present invention is not limited to this, and a strip-shaped graphite sheet may be used. In addition, a composite of silicone rubber and a fibrous material in which a metal fiber or a metal fiber is subjected to a surface treatment and whose fiber axis direction is aligned in a direction intersecting the conveying direction of the recording material may be similarly used. It is possible.

Example 2 In Example 1, the use of high-thermal-conductivity fibers having a uniform orientation as the high-thermal-conductivity layer ensures good heat conduction only in the longitudinal direction of the roller (the direction perpendicular to the cylindrical cross section). However, in addition, weave fibers of copper, aluminum, or alloys of these into a cloth, put a cylinder with this cloth, inject silicone rubber, and use this as a high thermal conductive layer silicone rubber composite Method, or make a cylinder with a cloth made of thin resin fiber (for example, non-woven cloth), put a material in which this cylinder is metal-plated with copper or aluminum, inject silicone rubber, and mix high thermal conductive silicone rubber There are ways to make the body.

The high thermal conductive silicone rubber composite containing such a fibrous material has a thermal conductivity of 0.2 when a carbon particle or the like is added as a filler to a conventional silicone rubber.
Heat conduction is very good compared with １1 W / m · K,
A thermal conductivity of 00 W / m · K can be realized.

However, in the case of such a configuration in which heat is transmitted two-dimensionally, not only the flow of heat is improved only in the direction (longitudinal direction) perpendicular to the circular cross section of the roller cylinder, but also in the circumferential direction of the roller. Also makes it easier for heat to flow. as a result,
Even when the fixing roller 1 is stopped during standby or the like, heat is conducted from the nip portion N along the circumferential direction of the pressure roller 2, flows below the pressure roller 1, and radiates heat from the pressure roller 2. Becomes large.

Therefore, in this embodiment, even when such a high thermal conductive layer having a uniform thermal conductivity in the layer is used, anisotropy is added to the heat flow on the surface of the pressure roller 2. The pressure roller 2 is provided with a heat insulating cover, and the fixing roller 1 contacts N
Only the pressure roller 2 is exposed.

FIG. 7 is a plan view of the fixing device C in the lateral direction, and FIG. 8 is a plan view of the fixing device C in the longitudinal direction. The configuration other than the configuration related to the pressure roller 2 is the same as that of the fixing device A of the first embodiment, and a detailed description thereof will be omitted.

The pressure roller 2 provided in the fixing device C of this embodiment is a partial cross-sectional view in the longitudinal direction showing a part of one side with respect to the axis of FIG. As shown in the cross-sectional view in the direction, an elastic layer 203 having excellent rubber elasticity at a high temperature is coated on the metal cores 201 and 202, and a high thermal conductive layer 206 is further provided thereon.

The high thermal conductive layer 206 is a high thermal conductive rubber composite layer and contains a fibrous material formed by knitting metal fibers. In this embodiment, as the metal fiber, a copper fiber having a good heat conductivity of 50 μm to 500 μm is used. The pressure roller 2 having the high thermal conductive layer 206 was manufactured by a method according to the following (1) to (6). (1) A cylindrical product having a predetermined outer diameter is produced by weaving copper fibers of 50 μm to 500 μm. (2) The metal surface of the cylindrical object is treated in order to improve the adhesion between the silicone rubber and the metal. (3) Next, in the same manner as in the method of manufacturing the high heat conductive layer 204 described in the first embodiment, it is placed in a cylindrical mold, and a silicone rubber base material is poured into the mold and cured to form a tube. This becomes the high thermal conductive layer 206. (4) The tube formed in (3) is adjusted to have a predetermined thickness, and an adhesive is applied to the inside of the tube. (5) Then, the core metal 20 is attached to the elastic layer 203 which is a sponge.
The sponge roller into which (1) is inserted is fitted into the tube of (4), subjected to an inner surface treatment for increasing the bonding strength by a known method, and becomes a release layer 205 coated with an adhesive on the outside of the tube of (4). Fit PFA tube. (6) Finally, (5) is heat-bonded to produce a pressure roller 2.

In the fixing device C, the above (1) to (1)
The pressure roller 2 having the high thermal conductive layer 206 of FIG. 11 manufactured by the method described in (6) is used.
The fixing device C is covered with a cylindrical heat-insulating cover 15 as shown in a plan view from the short side direction of FIG. 7 and a plan view from the long side direction in FIG. The central shaft 16 of the pressure roller, which is the core metal 202 of the pressure roller, is located above the center position of the cylindrical section of the cylindrical cover 15. An opening K is provided above the cover 15, and an upper portion of the pressure roller 2 projects upward from the opening K, and comes into contact with the fixing roller 1 so that the nip N
Is formed. Both ends of the cylindrical cover 15 are closed by a pressure roller bearing 11 and a side plate (cap) 17 for fixing the cover 15, and the positions of the pressure roller 2 and the cylindrical cover 15 are fixed by the cap 17. Have been. That is, this allows the pressing roller 2 and the cover 1
5 is formed as a unit. Then, the exposed portion of the pressure roller 2 is limited to a narrow upper region, and heat radiation from the roller 2 is reduced.

As can be understood from FIG. 10 as well, the cap 17 of the cylindrical heat-insulating cover 15 has a detent pin 18. The pressing side plate 12 has a detent opening 19, and the pin 18 is arranged to pass through the opening 19 so that the cylindrical cover 15 rotates in conjunction with the rotation of the pressing roller 2. Has been prevented.

The cylindrical cover 15 will be further described. As shown in FIG. 9, the cylindrical cover has a cylindrical reflector 152 having an opening at a nip portion N with the fixing roller 1;
The elastic layer 151 is provided around the periphery.

The heat insulating layer 151 is made of compressed glass fiber (thickness 3).
-5 mm), inside which is formed a reflector 152 made of polyimide resin (100 μm to 500 μm) with metal plating inside the cylinder.

For the side plates 17 at both ends shown in FIGS. 8 and 10, a heat-resistant reinforced resin (a material in which a reinforcing material is added to PPS or PBT) is used as a material in order to maintain mechanical strength. The side plate 17 can be inserted into the heat-insulating cover cylinder 15 in the form of a cap, and can be assembled after the pressure roller 2 is inserted into the cylindrical cover 15.

When a fixing device C having a configuration in which a cover 15 was attached to the produced pressure roller 2 was used, heat could be satisfactorily flowed in the longitudinal direction of the roller 2.
The heat flow was suppressed in the circumferential direction and the radial direction by heat insulation with the heat insulating cover 15.

Therefore, in the case of a high heat conductive rubber composite in which the high heat conductive layer on the surface of the pressing member is not sufficiently anisotropic as in the pressure roller 2 of the fixing device C of this embodiment, heat radiation is suppressed. By using a casing integrated with the pressure roller, heat radiation can be easily suppressed.

If the heat insulating cover 15 covers the peripheral surface of the pressure roller 2 other than the nip portion N with the fixing roller 1 by 60% or more, heat radiation can be suppressed, and the cover 15 is located in the nip portion N area. 90% covering area to prevent intrusion
The following is preferable, but the cover 15 is
The area that covers the peripheral surface of the pressure roller 2 is not limited to this as long as heat radiation from the peripheral surface of the pressure roller 2 can be suppressed.

In this embodiment, the fibrous material of the two-dimensionally woven metal fiber is used as the high thermal conductive rubber composite layer, but the fibrous material contained in the high thermal conductive rubber composite layer is It is preferable that the thermal conductivity is not less than 50 W / m · K, and the material and shape are not limited.

In the first and second embodiments, the case where the fixing member is a thin fixing roller has been described. However, the present invention is not limited to a fixing device having a fixing roller, but may be applied to a pressure roller of a film fixing device. It goes without saying that it is possible to apply.

[0080]

As described above, in the fixing device and the image forming apparatus of the present invention, the high thermal conductive rubber composite layer is formed integrally with the pressing member, and the thermal conductivity of the high thermal conductive rubber composite layer is reduced. Having anisotropy, so that the heat flow in the direction intersecting the recording material transport direction is greater than the heat flow in the other direction, or to cause anisotropy in the heat flow on the pressing member surface, Or, a high thermal conductive rubber composite layer is integrally formed on the pressing member, and further,
A heat insulating cover is separately provided outside the pressing member, and the heat of the surface of the pressing member is changed by the heat insulating cover so that the heat flow in the direction intersecting the recording material conveyance direction is larger than the heat flow in the other direction. Flow, anisotropy is generated, so that a pressurized member having high thermal conductivity in the longitudinal direction but low thermal conductivity in other directions can be realized, thereby increasing costs and complicating the structure. In addition, the temperature rise of the non-sheet passing portion at the end of the fixing member and the pressing member is moderated, thereby preventing wrinkles and offset of the fixing member and instability of paper feeding and jam due to a difference in outer diameter of the pressing member. In addition, heat efficiency is good, and heat is hardly dissipated in directions other than the longitudinal direction. Therefore, there is an effect that the fixing property is not deteriorated and the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a partial sectional view in the longitudinal direction (FIG. 1A) and a sectional view in the lateral direction (FIG. 1B) showing an example of a pressure roller according to the present invention.

FIG. 2 is a plan view illustrating a fixing device according to an embodiment of the present invention, as viewed from a lateral direction.

FIG. 3 is a plan view from the longitudinal direction showing an example of the fixing device of the present invention.

FIG. 4 is an explanatory diagram illustrating a positional relationship between a fixing roller, a recording sheet, and a temperature measurement point in Experimental Example 1.

FIG. 5 is a graph showing a temperature distribution of a fixing roller of a conventional fixing device B.

FIG. 6 is a graph comparing a non-sheet passing portion temperature rise of the fixing device A of the present invention and a fixing device B of the related art.

FIG. 7 is a plan view of another example of the fixing device of the present invention, as viewed from a lateral direction.

FIG. 8 is a plan view from the longitudinal direction showing another example of the fixing device of the present invention.

FIG. 9 is a cross-sectional view of the heat insulating cover of the pressure roller according to the present invention.

FIG. 10 is a sectional view of a longitudinal end portion of the pressure roller and the heat insulating cover according to the present invention.

FIG. 11 is a partial sectional view in the longitudinal direction (FIG. 11 (a)) and a sectional view in the short direction (FIG. 11 (b)) showing another example of the pressure roller according to the present invention.

FIG. 12 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 fixing roller (fixing member) 2 pressure roller (pressure member) 7 fixing device side plate 8 fixing device top plate 9 temperature detecting element 11 pressure roller bearing 12 pressure roller pressing plate 13 pressure plate shaft 14 pressure spring 15 heat insulation Cover 17 Insulating cover side plate 18 Insulating cover surrounding pin 19 Pressing plate opening 151 Insulating cover insulating layer 152 Insulating cover reflecting plate 201 Pressing roller core 202 Pressing roller core 203 Pressing roller elastic layer 204 Pressing roller high heat conductive layer (High thermal conductive rubber composite layer) 205 Pressure roller release layer 206 Pressure roller high thermal conductive layer (High thermal conductive rubber composite layer) K Thermal insulation cover opening

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05B 3/00 335 H05B 3/00 335 F term (Reference) 2H033 AA02 AA09 AA15 BA05 BA11 BA12 BB01 BB29 BB30 BE03 3J103 AA02 AA12 BA01 BA41 FA01 FA14 FA18 GA02 GA57 GA58 HA12 HA20 HA47 HA52 HA60 3K058 AA13 BA18 DA26

Claims (30)

[Claims] And a fixing member provided with a heating unit, wherein the fixing member is configured to interlock with a recording material carrying an unfixed developer image while pressing the recording material against the pressing member. In a fixing device for nipping and transporting the unfixed developer image on a recording material by nipping and conveying the nip portion, a high thermal conductive rubber composite layer is integrally formed on the pressing member,
The surface of the pressing member so that the thermal conductivity of the high thermal conductive rubber composite layer has anisotropy, and the heat flow in the direction intersecting the recording material conveyance direction is larger than the heat flow in other directions. A fixing device for generating anisotropy in the heat flow of the fixing device. 2. The fixing device according to claim 1, wherein the high thermal conductive rubber composite layer has a thermal conductivity of 50 W / m · K or more. 3. The fixing device according to claim 1, wherein the high thermal conductive rubber composite layer contains a fibrous material. 4. The high thermal conductive rubber composite layer contains the fibrous material in a state where the fibrous material is oriented in one direction, and the fiber axis direction of the fibrous material is a direction intersecting the recording material conveying direction. 4. The fixing device according to claim 3, wherein the fixing device is configured as follows. 5. The anisotropy of the thermal conductivity of the high thermal conductive rubber composite layer is expressed by (thermal thermal conductivity in a direction parallel to the axial direction of the fibrous material) in the high thermal conductive rubber composite layer. 5. The fixing device according to claim 4, wherein a directional ratio represented by a thermal conductivity in a direction perpendicular to the axial direction of the fibrous material is 500 to 1,000. 6. 6. The high thermal conductive rubber composite layer is formed of a silicone rubber composite containing, as the fibrous material, 15 to 45% by volume of pitch-based graphitized carbon fibers. The fixing device according to claim 3. 7. The fibrous material is any fiber selected from inorganic fibers such as carbon fibers; metal fibers such as copper, aluminum, or alloys thereof; or metal plating such as copper or aluminum. The fixing member according to claim 3, wherein the fixing member is a fibrous material, and the high thermal conductive rubber composite layer is formed of silicone rubber containing the fibrous material. apparatus. 8. A fixing member having a pressing member and a fixing member provided with a heating means, wherein the fixing member interlocks with a recording material carrying an unfixed developer image while being pressed against the pressing member. In a fixing device for nipping and transporting the unfixed developer image on a recording material by nipping and conveying the nip portion, a high thermal conductive rubber composite layer is integrally formed on the pressing member,
Further, a separate heat-insulating cover is provided outside the pressing member, and the heat-insulating cover makes the heat flow in the direction intersecting the recording material conveying direction larger than the heat flow in the other direction. A fixing device for generating anisotropy in heat flow on the surface of a pressure member. 9. The fixing device according to claim 8, wherein the high thermal conductive rubber composite layer has a thermal conductivity of 50 W / m · K or more. 10. The heat insulating cover has an opening at a nip portion of the pressure member with the fixing member, and covers a peripheral surface of the pressure member other than the nip portion. 8 or 9 fixing device. 11. The heat-insulating cover, wherein:
60% to 90% of the peripheral surface other than the nip portion with the fixing member
The fixing device according to claim 10, wherein the fixing device is covered. 12. The fixing device according to claim 8, wherein the pressure member and the heat insulating cover are integrated to form a unit. 13. The fixing device according to claim 8, wherein the high thermal conductive rubber composite layer contains a fibrous material. 14. The fibrous material is any fiber selected from inorganic fibers such as carbon fibers; metal fibers such as copper, aluminum, or alloys thereof; or metal plating such as copper or aluminum. The fixing device according to claim 13, wherein the fixing member is a fibrous material, and the high thermal conductive rubber composite layer is formed of silicone rubber containing the fibrous material. 15. The fixing device according to claim 1, wherein the fixing member is formed in a roller shape or a film shape, and the pressing member is formed in a roller shape. apparatus. 16. A recording material that forms an unfixed developer image on a recording material based on external information, has a pressing member, and a fixing member provided with a heating unit, and carries the unfixed developer image. To
In an image forming apparatus which nips and conveys the unfixed developer image onto a recording material by nipping and transporting the nip portion between the pressing member and the fixing member which is interlocked with the pressing member while being in contact therewith, Forming the conductive rubber composite layer integrally,
The surface of the pressing member so that the thermal conductivity of the high thermal conductive rubber composite layer has anisotropy, and the heat flow in the direction intersecting the recording material conveyance direction is larger than the heat flow in other directions. An image forming apparatus, wherein an anisotropy is generated in the heat flow. 17. The high thermal conductive rubber composite layer has a thermal conductivity of 50 W / m · K or more.
6. The image forming apparatus of item 6. 18. The high thermal conductive rubber composite layer contains a fibrous material.
Image forming apparatus. 19. The high thermal conductive rubber composite layer contains the fibrous material in a state oriented in one direction, and a fiber axis direction of the fibrous material is a direction intersecting a recording material conveying direction. 19. The image forming apparatus according to claim 18, wherein the image forming apparatus is configured as follows. 20. The heat conductivity anisotropy of the high thermal conductive rubber composite layer is calculated by: (thermal conductivity in a direction parallel to the fiber material fiber axis direction) in the high thermal conductive rubber composite layer.
(Thermal conductivity in the direction perpendicular to the fiber axis direction of the fibrous material)
20. The image forming apparatus according to claim 19, wherein a direction ratio is represented by: 21. The high thermal conductive rubber composite layer is formed of a silicone rubber composite containing, as the fibrous material, pitch-based graphitized carbon fibers in a volume content of 15 to 45%. The image forming apparatus according to claim 18, wherein: 22. The fibrous material may be any fiber selected from inorganic fibers such as carbon fibers; metal fibers such as copper, aluminum, or alloys thereof; or metal plating such as copper or aluminum. The image according to any one of claims 18 to 20, wherein the image is a fibrous material subjected to the following, and the high thermal conductive rubber composite layer is formed of silicone rubber containing the fibrous material. Forming equipment. 23. A recording material which forms an unfixed developer image on a recording material based on external information, has a pressing member, and a fixing member provided with a heating unit, and carries the unfixed developer image. To
In an image forming apparatus which nips and conveys the unfixed developer image onto a recording material by nipping and transporting the nip portion between the pressing member and the fixing member which is interlocked with the pressing member while being in contact therewith, Forming the conductive rubber composite layer integrally,
Further, a separate heat-insulating cover is provided outside the pressing member, and the heat-insulating cover makes the heat flow in the direction intersecting the recording material conveying direction larger than the heat flow in the other direction. An image forming apparatus, wherein an anisotropy is generated in a heat flow on a surface of a pressure member. 24. The high thermal conductive rubber composite layer having a thermal conductivity of 50 W / m · K or more.
3 is an image forming apparatus. 25. The heat-insulating cover has an opening at a nip portion between the pressure member and the fixing member, and covers a peripheral surface of the pressure member other than the nip portion. 23 or 24. 26. The heat insulating cover, wherein:
60% to 90% of the peripheral surface other than the nip portion with the fixing member
The image forming apparatus according to claim 25, wherein the image forming apparatus covers the image forming apparatus. 27. The image forming apparatus according to claim 23, wherein the pressure member and the heat insulating cover are integrated to form a unit. 28. The image forming apparatus according to claim 23, wherein the high thermal conductive rubber composite layer contains a fibrous material. 29. The fibrous material is any fiber selected from inorganic fibers such as carbon fibers; metal fibers such as copper, aluminum, or alloys thereof; or metal plating such as copper or aluminum. 29. The image forming apparatus according to claim 28, wherein the fibrous material is subjected to the following, and the high thermal conductive rubber composite layer is formed of silicone rubber containing the fibrous material. 30. The image according to claim 16, wherein the fixing member is formed in a roller shape or a film shape, and the pressing member is formed in a roller shape. Forming equipment.