JPH11231704A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device with which high releasing performance can be provided and the degradation of a fixing roll caused by the frictional wearing or crease generation of a releasing layer is reduced. SOLUTION: Concerning this device 10, a fixing roll 12 is composed of a cylindrical body 16, a heat resistant elastic body layer 18 wound around the outer periphery of the cylindrical body, and a fluororesin tube 20 around the outer periphery of the heat resistant elastic body layer 18. A pressure impressing member 14 has a support 24 and a conveyer belt 28 and inside a supporting box 32, a heat resistant rubber body 34 and a pressed body 36 are attached. By pushing the tube 20 and the heat resistant elastic body resin layer 18 radially inward, distortion W toward the inside in the diameter direction is generated on the fluororesin tube 20 so that the releasing performance of the fixing roll 12 can be improved and picture quality can be improved. The length of the pressed body 36 in lengthwise direction is made longer than the length of the tube 20 in axial direction, and the wearing and crease generation of the tube 20 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly, to a fixing device for fixing a toner image to a transfer material by nipping and conveying a transfer material onto which an unfixed toner image has been transferred.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, for example, a copying machine using an electrophotographic process, a solvent fixing method is used as a method for fixing an unfixed toner image transferred onto a recording material such as paper. A pressure fixing method, a heat fixing method, a heat pressure fixing method, and the like are known.

[0003] Among these fixing methods, a fixing device employing a heat and pressure fixing method will be described.

FIG. 8 shows a heat roll type fixing device which is one of the heat and pressure fixing methods. This fixing device 7
0, a heating roller 72 and a pressure roller 74 are provided, and the heating roller 72 includes a cylindrical core metal 76 and a core metal 7.
6 and a release layer 79 made of a heat-resistant resin layer or a heat-resistant rubber layer that covers the outer periphery of the metal core 76. On the other hand, the pressure roller 7
Reference numeral 4 denotes a cylindrical core 80, a heat-resistant elastic layer 82 and a heater 84 formed on the outer periphery of the core 80. The pressure roller 74 is pressed against the heating roller 72, and pinches and conveys the sheet P on which an unfixed toner image is formed between the heating roller 72 and the pressure roller 74. As a result, the unfixed toner T is melted and then permeated into the paper P to be fixed.

[0005] As described above, in the fixing device of the heating and pressurizing system, the toner T is melted by heat and is further pressed and fixed on the paper P, so that the thermal efficiency is higher than that of the hot air fixing system or the oven fixing system. Widely used.

On the other hand, when the toner can be fixed only by pressing it against the paper P without being melted by heat, the fixing is performed by a method (pressurizing method) in which the heaters 78 and 84 having the above-described configuration are omitted. The device is configured. In this pressurizing method, there is no need to heat the toner, so that the power consumption is low.

The release layer 79 is coated with a heat-resistant resin, a heat-resistant rubber, or the like in order to separate the fixed toner T from the heating roller 72. Generally, polytetrafluoroethylene (hereinafter, PTFE)
And fluorine-based heat-resistant resins represented by perfluoroalkyl vinyl ether copolymer resin (hereinafter, PFA) and propylene tetrafluoroethylene hexafluoropropylene copolymer resin (hereinafter, FEP) are more suitable for silicone rubber and fluorine rubber. Release agent (so-called release oil) rather than heat-resistant rubber represented by
It is known that high releasability can be obtained without using a heat-resistant resin, and therefore, a heat-resistant resin is used in a black-and-white copying machine.

However, when the metallic core metal 76 is coated with a fluorine-based heat-resistant resin as the release layer 79, the material of the fluorine-based heat-resistant resin itself is hard, and the minute adhesiveness with the toner is low. Fine density unevenness sometimes occurs in a so-called solid portion of a fixed image. On the other hand, when the metal core 76 is coated with the heat-resistant rubber, the rubber expands due to the softness of the heat-resistant rubber itself and firmly adheres to the toner. Therefore, it is possible to obtain excellent image quality without density unevenness.

Further, as described in, for example, Japanese Patent Application Laid-Open No. 5-150679, it is known that when a heat-resistant rubber is coated, the rubber has high peeling performance due to distortion of the rubber. The term “distortion” refers to local inward elastic deformation that appears on the surface of the fixing roll when the fixing roll is pressed by a pressing unit such as a pressure roll. Quantitatively,
When nipping and transporting the paper using the heated heating roll, the transport length of the paper per rotation of the heating roll is M _W ,
When the transport length of the paper per rotation of the heating roll is M _N when the paper is nipped and transported by using a heating roll having no distortion, the distortion rate ε is as follows: ε = (M _W / M _N − 1) Defined by 100%.

In general, the length of the sheet fed by one rotation of the fixing roll in which the distortion is generated is longer than the length of the sheet sent in one rotation of the fixing roll in which the distortion is not generated.

The fixing roll disclosed in Japanese Patent Application Laid-Open No. HEI 5-150679 has an RTV silicone rubber on the
V silicone rubber is arranged and configured, and the RTV silicone rubber on the top layer itself is also extensible,
Distortion is easy to occur. However, the RTV silicone rubber is not very high in releasability, and has a high friction coefficient of itself and is easily worn, so that it was necessary to separately provide a release agent applying means.

Therefore, it is conceivable that if the surface of the heat-resistant rubber is coated with a fluororesin having a high release performance, the release performance will be even higher and there is no need to prepare a special release agent applying means. .

Regarding this point, Japanese Patent Application Laid-Open No. 61-2237 discloses
6, as disclosed in JP-A-61-248731, etc.
By using a roll obtained by applying and baking a fluororesin dispersion on the surface of a heat-resistant rubber, high release performance and excellent image quality can be easily obtained. However, since the thickness of the applied and fired film is at most about 2 to 3 μm, there is a possibility that the release layer (particularly, the edge of the paper) may be worn when the paper is passed.

Therefore, Japanese Patent Application Laid-Open Nos. 57-89785, 53-144747, 7-349, and 4-4
These problems can be solved by coating the surface of a heat-resistant rubber with a so-called fluororesin tube manufactured in advance as disclosed in 2183 and the like.

However, since the thickness of a general fluororesin tube is about 50 to 100 μm, the tube itself is hard, and it is difficult to sufficiently generate the above-mentioned distortion to obtain high mold release properties. . Further, no attention has been paid to improving the releasability and improving the image quality by generating a strain by coating the fluorine resin tube on the upper layer of the elastic body so far.

[0016]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a fixing device in which deterioration of a fixing roll due to frictional abrasion and wrinkling of a releasing layer is reduced while obtaining high releasing performance and excellent image quality. That is the task.

[0017]

According to the first aspect of the present invention, an elastic member formed in a cylindrical or columnar shape and elastically deformable at least radially inward is formed on the outer periphery of the elastic member in a cylindrical shape. A transfer roll in which an unfixed toner image is transferred between a fixing roll having a fluorine-based resin layer having a thickness in the radial direction of 10 μm to 40 μm and a fixing roll disposed opposite to the fixing roll; Pressing means for nipping and conveying the material to fix the toner image on the transfer material, and pressing the fixing roll radially inward to generate distortion of 0.1% or more in the fixing roll; Wherein both ends in the axial direction of the fluorine-based resin layer are respectively located outside both ends in the width direction of the transfer material, and both ends in the width direction of the pressurizing unit are respectively larger than both ends in the axial direction of the fluorine-based resin layer. Located outside It is characterized by being.

Accordingly, the transfer material to which the unfixed toner image is transferred is fixed by being pressed against the transfer material while being nipped and conveyed between the fixing roll and the pressing means. At this time, a heating unit such as a heater may be provided in the fixing roll or the pressing unit, and the toner may be melted and fixed on the transfer material.

The pressing means presses the fixing roll radially inward. Since the fluorine-based resin layer covering the outer periphery of the elastic member constituting the fixing roll has a thickness of 10 μm to 40 μm, it can be deformed radially inward by pressure from a pressure unit. Accordingly, the elastic member is elastically deformed radially inward by the pressure from the pressurizing means, and the fluorine-based resin layer is distorted. Due to this distortion, the releasing performance of the fixing roll is improved, and the transfer material after fixing is easily separated from the fixing roll. In addition, since the adhesion with the unfixed toner image is increased due to the distortion, a high-quality image without gloss unevenness can be obtained. Fluorine resin layer is 10 μm
Since it has the above thickness, the image quality does not deteriorate due to wear and the durability of the fluorine-based resin layer is also improved.

Since both ends in the width direction of the pressurizing means are located outside the both ends in the axial direction of the fluororesin layer, the fluororesin layer is uniformly pressurized by the pressurizing means over the entire area in the axial direction. The distortion rate becomes substantially constant in the axial direction. For this reason, partial wrinkles do not occur on the fixing roll.

Further, since both ends in the axial direction of the fluororesin layer are located outside both ends in the width direction of the transfer material, the toner image can be fixed to the transfer material over the entire width of the transfer material in the width direction.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressurizing means is formed to be endless and deformable at least outward, and is disposed to face the fixing roll. A transport belt, and a support member that supports the transport belt in a circulating manner while being in contact with the fixing roll, and partially deforms the transport belt outward to generate the distortion in the fixing roll. It is characterized by.

Accordingly, the support member partially deforms the transport belt, and the deformed portion presses the fixing roll radially inward. Thereby, local distortion is generated in the fixing roll, and the peeling performance of the fixing roll can be improved.

According to a third aspect of the present invention, in the second aspect of the present invention, both ends in the width direction of the conveyor belt are located outside both ends in the width direction of the support member. .

Thus, exposure of the pressurizing means from the conveyor belt can be prevented, so that abrasion of the fluororesin layer due to rubbing can be prevented, and the fixing performance of the fixing roll can be maintained.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the transfer material nipped and conveyed between the fixing roll and the pressing means has a maximum width in the width direction. When the distortion rate of the fixing roll at the portion having is ε _RO , and the distortion rate at the approximate center in the axial direction of the fixing roll is ε _RI ,
It is characterized in that 0.5 ≦ ε _RO / ε _RI ≦ 1.0.

By setting the ratio of ε _RO to ε _{RI in} this manner, when the transfer material is nipped and conveyed between the fixing roll and the pressing means to fix the toner image on the transfer material, No wrinkles occur.

Further, since the distortion at both ends in the width direction of the transfer material is smaller than that at the substantially central portion in the width direction of the transfer material, the fixing roll near the position corresponding to the both ends in the width direction of the transfer material is provided. Can be reduced, and the durability of the fixing roll can be improved.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Configuration of Fixing Device) FIGS. 1 and 2
1 shows a fixing device 10 according to an embodiment of the present invention. The fixing device 10 includes a fixing roll 12 formed in a cylindrical shape, and a pressure applying member 14 that is disposed to face the fixing roll 12 and sandwiches and conveys the sheet P between the fixing roll 12 and the fixing roll 12. It is configured.

The toner T is transferred to the sheet P by a transfer unit (not shown) without fixing. When the sheet P is nipped and conveyed between the fixing roll 12 and the pressure applying member 14,
The unfixed toner T on the sheet P is fixed.

The fixing roll 12 includes a cylindrical body 16 having a predetermined length in the axial direction, a cylindrical heat-resistant elastic layer 18 wound around the outer periphery of the cylindrical body 16, and a heat-resistant elastic layer 18.
Tube 2 as a fluororesin layer wound around the outer periphery of
And 0. Furthermore, a halogen lamp 22 is provided inside the cylindrical body 16 as a heating source, and the surface of the fixing roll 12 is heated. The surface temperature of the fixing roll 12 is detected by a temperature sensor (not shown), and is maintained at a predetermined temperature by a temperature controller (not shown).

The fixing roll 12 according to the present embodiment is
Can function as a heat fixing roll by heating the surface thereof, but can also function as a pressure roll without heating the surface of the fixing roll 12.

As a material forming the cylindrical body 16, iron, stainless steel, aluminum, or the like having excellent thermal conductivity is generally used, but other metals may be used.

As the material of the heat-resistant elastic layer 18, fluorine rubber and silicone rubber can be used. In the case of a heat fixing roll, the thickness of the heat-resistant elastic layer is 100 μm to 2 mm.
Is preferred. This is because the thickness of the heat-resistant elastic layer 18 is 10
When the thickness is less than 0 μm, the effect of preventing the recording paper from being wrapped is low because distortion W described later is unlikely to occur. This is because the time it takes to reach it becomes longer.

When the fixing roll 12 is used as a heat fixing roll, the hardness of the heat-resistant elastic layer 18 is determined according to JIS.
When measured in accordance with K6301, it is preferably 20 degrees to 60 degrees. The hardness of the heat-resistant elastic layer 18 is 2
If it is less than 0 degree, the pressure applied to the recording paper P becomes small and the image quality cannot be improved, and if it exceeds 60 degrees, distortion hardly occurs and the effect of preventing the recording paper from being wrapped cannot be obtained. That's why.

When a pressure roll is used as the pressure applying member 14, the hardness of the heat-resistant elastic layer depends on the heat resistance of the fixing roll 12 in order to obtain the distortion of the heat-resistant elastic layer 18 of the fixing roll 12. The hardness is equal to or higher than the hardness of the elastic layer 18.

When a tube is used as the uppermost layer of the pressure roll, the thickness of the tube can be set to an arbitrary value, for example, 30 to 50 μm.
In the case where the pressure roll includes a heat-resistant elastic layer having good releasability as the uppermost layer, examples of a material used for such a heat-resistant elastic layer include fluorine rubber and silicone rubber.

The tube 20 is made of a fluorine-based heat resistant material represented by polytetrafluoroethylene (PTFE), perfluoroalkyl vinyl ether copolymer resin (PFA), and ethylene tetrafluoride hexafluoropropylene copolymer resin (FEP). Resin is conceivable. Among these, PFA is preferred from the viewpoint of heat resistance and workability. In addition, in order to improve the adhesion to the heat-resistant elastic layer, the inner surface of the tube may be subjected to a primer treatment or the like by etching.

When the fixing roll 12 is used as a heat fixing roll, the thickness (radial thickness) of the tube 20 is 5 μm.
m to 40 μm. If the thickness of the tube is less than 5 μm, the life of the heat fixing roll is shortened due to easy wear, and if it exceeds 40 μm, the surface of the heat fixing roll becomes hard and the image quality cannot be improved. Tube 2
More preferably, the thickness of 0 is 10 μm to 20 μm.

On the other hand, the pressure applying member 14 is formed in a substantially cylindrical cross section, and is mounted on a housing (not shown) so that the axial direction is horizontal.
And an endless transport belt 28 wound around the outer periphery of the belt. At the upper part of the support 24, a mounting hole 30 for communicating the inside and the outside of the support 24 is formed.

A support box 32 having an open upper surface is mounted in the mounting hole 30. In the support box 32, a heat-resistant rubber body 34, and a pressure body 36 disposed downstream of the heat-resistant rubber body 34 in the transport direction of the paper P (left side in FIG. 1),
Has been fixed.

The heat-resistant rubber body 34 is pressed against the fixing roll 12 to form an arc surface 34A. Further, the pressing body 36 is formed with a convex portion 36A that protrudes toward the fixing roll 12 from the arc surface 34A at a predetermined height and has a predetermined radius of curvature smaller than the arc surface 34A. A friction reducing member 38 is adhered to the arcuate surface 34A and the distal end of the pressing body 36, so that friction between the transport belt 28 and the heat-resistant rubber body 34 and the pressing body 36 is reduced.

The transport belt 28 circulates around the outer periphery of the support 24 through a gap formed between the friction reducing member 38 and the outer periphery of the fixing roll 12. Therefore, the transport belt 28
Is concave inward along the arc surface 34A, and furthermore, the convex portion 36A
The contact area of the conveyor belt 28 with the fixing roll 12 is increased because the fixing belt 12 is in contact with the fixing roll 12 while being curved outward.

The pressing body 36 presses the fixing roll 12 by the convex portion 36A. As a result, the tube 20 of the fixing roll 12 and the heat-resistant elastic resin layer 18
Is pushed radially inward, and a radially inward distortion W occurs in the tube 20. As described later, the release performance of the fixing roll 12 is improved by the distortion W.

As shown in FIG. 2, the length and position of the tube 20 in the axial direction are determined so that both ends in the axial direction of the tube 20 are located outside both ends in the width direction of the paper P. As a result, the toner of the unfixed toner image can be fixed over the entire area of the sheet P in the width direction (in FIG. 2, for convenience of illustration, the tube 20 of the fixing roll 12 and the pressing member 36 of the pressure applying member 14). And only the sheet P).

Further, the longitudinal direction of the pressure body 36 (the tube 2
Both ends are located outside both ends of the tube 20 in the axial direction. As a result, the pressurizing body 36 comes into contact with and pressurizes the entire area of the tube 20 in the axial direction, so that the tube 20 is not locally strongly pressurized. Thereby, wrinkles are not generated in the tube 20.

Further, both ends in the width direction of the conveyor belt 28 are
The fixing roll 12 is shorter than both ends of the pressing body 36 in the longitudinal direction.
Since the length of the tube 20 is longer than that of the tube 20, it is possible to prevent the fluorinated resin layer constituting the tube 20 from being worn out by rubbing and to maintain the fixing performance of the fixing roll 12.

[0048]

EXAMPLES The present invention will be described in more detail with reference to Examples. (Examples 1 to 9, Comparative Examples 1 to 4) The fixing roll 12 and the pressure applying member 14 were configured as follows.

A cylindrical aluminum core having an outer diameter of 25 mm and a thickness of 1.5 mm is used as the cylindrical body 16 of the fixing roll 12, and a 3 mm-thick HTV (high-temperature Vulcanized)
Silicone rubber layer (hardness 30 according to JIS K6301)
And a 10 μm-thick PFA resin tube whose inner surface was subjected to a primer treatment by etching as a tube 20 on the silicone rubber layer to form a heat fixing roll. The length of the tube 20 in the axial direction was substantially equal to the length of the heat-resistant elastic layer 18 in the axial direction.

The halogen lamp 22 used was a lamp of 650 W, and the surface temperature of the fixing roll 12 was maintained at 150 ° C.

The support 24 of the pressure applying member 14 has an axial length of 350 mm,
A substantially cylindrical body made of a 5 mm heat-resistant resin, for example, polycarbonate, is used as the transport belt 28 and has a circumferential length of 90 m.
m, a polyimide belt having a wall thickness of 90 μm, and LTV silicone rubber having a hardness of 40 degrees (JIS K6301) were used as the heat-resistant rubber body 34. Further, the width of the conveyor belt 28 is made longer than the length of the heat-resistant rubber body 34 in the longitudinal direction (the axial direction of the fixing roll 12), and both ends of the conveyor belt 28 in the width direction are separated from both ends of the heat-resistant rubber body 34 in the longitudinal direction. Also located outside.

As the friction reducing member 38, a sliding member fired by impregnating a glass fiber with a fluororesin was used.

The radius of curvature of the upper end of the pressure body 36 (the portion where the fixing roll 12 is pressed) was 4 mm.

<Relationship between strain and releasability> In order to evaluate the relationship between strain and releasability, first, the relationship between load and self-stripping performance was determined as follows.

In the fixing device 10, the fixing roll 12 is moved so that the conveying speed of the sheet P becomes 160 mm / sec.
Rotate clockwise, and in this state, 3.0 mg / cm
^The sheet P on which the unfixed color toner image having the surface density of ² is formed over the entire surface of the sheet is passed through a nip area between the fixing roller 12 and the pressure applying member 14 to determine whether the recording sheet is not wound around the fixing roller 12 (self-storage). Whether ripping is possible) was observed.

The fixing roll 12 is moved by the pressure applying member 14.
The above procedure was repeated while changing the load applied to the sheet and the basis weight (mass per unit area) of the paper P. Table 1 shows the results. In Table 1 and Table 2 described below,
"A" indicates that the recording paper was inserted so that the fibers of the recording paper were parallel to the axial direction of the heat fixing roll, and "B" indicates that the fibers of the recording paper were perpendicular to the axial direction of the heat fixing roll. Indicates that the recording paper has been inserted.

[0057]

[Table 1]

As can be seen from Table 1, usually,
“A” has a weaker stiffness of the recording sheet than “B”, so that self-stripping tends to be more difficult.

As shown in Table 1, the self-stripping is improved when the load applied by the pressure applying member 14 is 10 kg.
It can be seen that self-stripping is possible irrespective of the grammage and the feed direction of. In particular, it can be seen that as the load by the pressure body 36 increases, self-stripping can be performed even on paper having a small basis weight (thin paper thickness).

Next, by using the fixing device 10 described above, the fixing roll 12 measures the conveying length M _W of the paper sheet P conveyed at the time of one revolution in computing the the measured value and the fixing roll 12 The distortion rate ε was determined from the outer peripheral length M _N (that is, the transport length of the paper P transported when the fixing roll 12 free of distortion is rotated once). The strain rate ε is defined by ε = ( _MW / _MN− 1) × 100 (%).

The above procedure was repeated while changing the load of the pressure applying member 14 by the pressing body 36. The paper P used had a basis weight of 65 g / m ² . The results are shown in FIGS.

FIGS. 3 and 4 show that the surface of the fixing roll 12 is distorted, and the distortion rate of the surface of the fixing roll 12 is increased as the load is increased.

Further, it can be seen from FIG. 4 that when the load is 10 kg, the distortion is 0.1%, and when the load is 30 kg, the distortion is 0.3%. Therefore, by comparing FIG. 4 with Table 1, it can be seen that a sufficient peeling performance can be obtained if the strain is 0.3% or more.

In Japanese Patent Application Laid-Open No. 5-150679, if the distortion is 0.5% or more, the peeling performance is improved. In contrast, in the fixing device 10 of the present invention, the peeling performance is improved. ing. This is the fixing device 1 of the present invention.
0 causes the pressure body 36 having a small radius of curvature (4 mm) to bite into the fixing roll 12, and the paper P is discharged so as to bend to the non-image surface side opposite to the image surface. In addition, the so-called rigidity of the paper P can be used as well as the peeling performance due to only the distortion of the fixing roll 12 (the radius of curvature is larger than the distortion due to the pressing body 36), and the nip is formed by pressing the rolls together. This is because it becomes harder to wind up than the thing.

It is also considered that the diameter of the fixing roll 12 itself is smaller than that of the fixing roll described in Japanese Patent Application Laid-Open No. 5-150679, so that the curvature of the sheet P becomes large and the sheet becomes difficult to wind. Can be

(Comparative Examples 5 to 16) The relationship between the load and the self-tripping property was examined under the same conditions as described above except that the fixing roll 12 was replaced with a hard roll.

The term "hard roll" as used herein refers to a roll that does not substantially deform in the radial direction. More specifically, it is a cylindrical aluminum core having an outer diameter of 25 mm and a thickness of 2.5 mm. A hard roll around which a 10 mm thick Teflon (trade name) was wound around was used. Further, instead of the heat-resistant rubber body 34 of the pressure applying member 14, a hardness 20
An HTV silicone rubber having a degree (JIS K6301) was used. Table 2 shows the results.

[0068]

[Table 2]

As shown in Table 2, self-stripping was not possible at all loads. This is probably because the fixing roll is a hard roll and has no elastic layer, so that no distortion occurs.

<Relationship between distortion and micro gloss>
Regarding the image quality of the fixed image obtained by the above operation, micro gloss, which is an evaluation item of the image quality, was examined.
Micro-gloss means that fine unevenness of gloss (gloss) occurs in a solid portion. When this micro gloss is generated, the heat-resistant elastic layer 18 is used to fix the fixing roll 12.
Even if the self-tripping performance is improved by improving the distortion, the image quality of the image is inferior. Therefore, the problem of the present invention of obtaining excellent image quality cannot be solved.

Here, the fluororesin tube 2 which is considered to have the greatest influence on the microgloss is used.
The solid image was fixed by changing the thickness of the fixing roll 12 and the hardness of the rubber (heat-resistant elastic layer) constituting the fixing roll 12, and the degree of generation of microgloss was visually evaluated.

For reference, a conventional hard roll, which is known to generate microgloss significantly, is used in place of a fixing roll, and the same evaluation is performed on a fixed image obtained by using the same. went.

The same hard rolls as those used in Comparative Examples 5 to 16 were used. Table 3 shows the results.

[0074]

[Table 3]

As shown in Table 3, if the hardness of the rubber (heat-resistant elastic layer 18) constituting the fixing roll 12 is increased, microgloss is easily generated, and the tube 2
It can be seen that even if the thickness of 0 is increased, it is likely to occur.
Further, when the thickness of the tube 20 is greater than 40 μm, the fixing roll 12 approximates a hard roll, so that the hardness of the rubber (heat-resistant elastic layer 18) constituting the fixing roll 12 is reduced. It can be seen that micro-gross is generated even if this occurs.

From the above, the thickness of the tube 20 is 40 μm.
The following is appropriate, preferably 30 μm or less, more preferably 20 μm or less.

<Relationship between Tube Thickness and Durability> By the way, when the thickness of the fluororesin-based tube 20 is reduced, long-term reliability is concerned, that is, when the paper P is inserted. Wear deterioration due to friction becomes a problem.

Therefore, in order to examine the relationship between the thickness of the tube 20 and the durability of the fixing roll 12, two fixing rolls 12 having the thickness of the tube 20 of 10 μm were mounted on an A Color 935 manufactured by Fuji Xerox Co., Ltd. X-Ray's L-paper A4 blank paper is inserted at a fixing temperature of 150 ° C.
The degree of wear deterioration was visually observed. At this time, the distortion rate of the fixing roll was set such that the distortion rate ε _RI at the approximate center of the paper insertion portion was fixed to 0.5% at which sufficient peeling performance could be secured.
Generally, the life of the fixing roll is about 100,000 sheets, and this is used as a guide.

As a result, when the thickness of the tube 20 is 5 μm, abrasion becomes remarkable, and when about 90,000 sheets are passed, the HTV silicone rubber constituting the heat-resistant elastic layer 18 is partially exposed. did. Therefore, when the thickness of the tube 20 is 5 μm or less, it cannot be said that the tube 20 is sufficient in terms of long-term reliability.

Next, both ends of the conveyor belt 28 and the pressing body 36
Was changed, and the durability of the tube 20 was examined.

That is, in the above-described test, the width of the transport belt 28 was made longer than the length of the heat-resistant rubber body 34 in the longitudinal direction (the axial direction of the fixing roll 12), and both ends of the transport belt 28 in the width direction were heat-resistant. The width of the conveyor belt 28 was made shorter than the length of the heat-resistant rubber body 34 for comparison. The same test was conducted with both ends in the width direction of the heat-resistant rubber body 34 positioned inside both ends in the longitudinal direction.

As a result, the tubes 20 at the contact portions of both ends of the fixing roll 12 with the heat-resistant rubber body 34 are
Were worn when about 1,000 sheets were inserted, and the underlying heat-resistant elastic layer 18 was exposed. For this reason, the axial length of the tube 20 is made longer than the axial length of the heat-resistant elastic layer 18 so that both axial ends of the tube 20 are located outside of the axial ends of the heat-resistant elastic layer 18. Thereby, the durability of the tube 20 can be improved.

<Wear of tube at end of paper in width direction>
By the way, in the above-mentioned test, the wear deterioration of the fluororesin constituting the tube 20 is most remarkably observed in the insertion portion where the width direction end of the paper P is inserted and in the vicinity of the insertion portion. In the area, no abrasion was observed.

This is because the paper is generally manufactured to a predetermined size by cutting, and the fibers of the paper P are exposed at the end (cut) of the paper P. . That is, when the paper P is nipped and conveyed between the fixing roll 12 and the pressure applying member 14 and the fixing roll 12 is distorted, the cut surface of the fibers of the paper P is formed on the surface of the fixing roll 12 (that is, the surface of the tube 20). Is locally rubbed, or a step between the paper insertion portion and the non-insertion portion is generated between the fixing roll 12 and the pressure applying member 14 by the thickness of the paper P, and the fixing roll is It is considered that the shear force acts.

In consideration of the actual use situation, the widthwise end of the sheet P is often located at the same portion of the fixing roll 12 in the axial direction. For example, when the paper P is pinched and conveyed so that the paper P has the same length in the axial direction of the fixing roll 12 (for example, when the A4 paper and the A3 paper are made to coincide with the axial direction of the fixing roll 12 and the like. The long side is A
Since the length of the A4 paper is so-called horizontal and the length of the A3 paper is vertical because the length is the same as the short side of the three papers, the fixing roll can be used regardless of whether the paper is A4 paper or A3 paper. The same applies to the long side of the B5 sheet and the short side of the B4 sheet, in which the widthwise end of the sheet P is located at the same portion in the axial direction of No. 12).

Therefore, when the sheet P is nipped and transported,
If the distortion rate of the fixing roll 12 is reduced in the portion where the edge of the sheet P is located, particularly in the portion where the edge of the sheet P is frequently located, the cut ends of the fibers of the sheet P rub against the surface of the fixing roll 12. It is conceivable that the abrasion of the fluorine resin constituting the tube 20 is reduced as a result.

Therefore, the pressure applied by the pressure body 36 of the pressure applying member 14 is made lower in the portion where the end of the sheet P is inserted in the axial direction of the fixing roll 12 and in the vicinity thereof than in other portions. The above-described paper insertion test was performed, and the wear of the fixing roll 12 was compared and examined.

At this time, the thickness of the tube 20 of the fixing roll 12 used was 10 μm. This is because, among the thicknesses of the fixing roll 12 that can be used practically, it is considered that the thickness is most remarkable in which the result of the test appears. The heat-resistant elastic layer 18 of the fixing roll 12 was fixed at a hardness of 40 degrees and a thickness of 0.7 mm. Then, the distortion rate ε _RI at the approximate center of the portion where the paper P is inserted is fixed at 0.5%, and the distortion rate ε _RO at the width direction end of the portion where the paper P is inserted and the vicinity thereof is determined. The abrasion of the fixing roll 12 was compared and examined by changing it.

The above change in the strain rate ε _RO can be easily realized by changing the shape of the pressure applying member 14. More specifically, it can be realized by changing the shape of at least one of the heat-resistant rubber body 34 and the pressure body 36. FIG. 5 shows the results. In FIG. 5, the distortion ratio refers to (ε _RO / ε _RI ). Therefore, FIG. 5 shows the relationship between the distortion ratio and the amount of wear of the fixing roll 12.

As can be seen from FIG. 5, the smaller the distortion ratio, the smaller the amount of wear. From this, it is considered that the reliability can be improved by reducing the ratio of the distortion rates.

<Wrinkling of Tube> However, when the ratio of the distortion rate is 0.4 or less, as shown in Table 4, the paper P
Roll 1 on the surface of the tube 20 in the widthwise end region of
The generation of fine wrinkles parallel to the second axis was confirmed when the number of inserted sheets was 40,000.

[0092]

[Table 4]

This is thought to be due to the following reason. That is, the pressure applied to the fixing roll 12 differs depending on the position in the axial direction near the axial end of the sheet P. For this reason, the tube 20 and the heat-resistant elastic layer 18 are
When the fixing roll 12 rotates or starts rotating, the fixing roll 12 expands differently along the circumferential direction in accordance with the position in the axial direction. As a result, it is considered that this occurs because the tube 20 extends beyond the so-called yield point and undergoes plastic deformation. Since the mechanical properties of the fixing roll 12 at the wrinkled portion are extremely weakened, the wrinkling portion is torn by the rubbing caused by the rotation of the fixing roll 12, and as a result, the fixing roll 12 is separated. Mold performance will be degraded.

Thus, a test was conducted to see how the degree of wrinkling of the tube 20 differs depending on the difference in hardness of the heat-resistant elastic layer 18 of the fixing roll 12. The conditions were as follows: the thickness of the tube 20 was 10 μm, the thickness of the heat-resistant elastic layer 18 was 0.7 mm, and the hardness was 10 degrees.
The same test as above was performed up to 50,000 sheets. Table 5 shows the results.

[0095]

[Table 5]

As can be seen from Table 5, the number of sheets of paper P inserted when the tube 20 has wrinkles differs from that in the test shown in Table 4. When the distortion ratio is less than 0.5, wrinkles are generated in the same manner.

Further, the thickness of the tube 20 and the tube 2
The thickness of the tube 20 was changed to 40 μm and the hardness of the heat-resistant elastic
A similar test was performed with 0 ° and 0.7 mm thickness. Table 6 shows the results.

[0098]

[Table 6]

As can be seen from Tables 5 and 6, tube 2
It can be seen that wrinkles occur depending on the ratio of the strain rates, regardless of the thickness of 0.

<Wrinkling of Paper> Next, the wrinkles (paper wrinkles) may be generated on the paper P by changing the distortion rate of the fixing roll 12. Specifically, the thickness of the tube 20, the hardness and the thickness of the heat-resistant elastic layer 18 are set to the same conditions, the ratio of the distortion rate of the fixing roll 12 is changed, and the S-paper A3 manufactured by Fuji Xerox Co., Ltd. 100 sheets were inserted in the vertical feed, and the number of sheets P inserted when wrinkles occurred at this time was observed. This is shown in Tables 4 and 5,
Also shown in Table 6. From this, it can be seen that if the ratio of the distortion rates is less than 0.5, the frequency of occurrence of wrinkles on the paper P sharply increases.

Up to this point, the ratio of the strain rate is ε _RO / ε _RI ≦ 1.
We have been examining the case. Therefore, the same test was performed in the case of ε _RO / ε _RI > 1, which was the opposite, and the paper P
The relationship between the number of inserted sheets and the amount of wear of the fixing roll 12 at the portion where the widthwise end of the sheet P abuts was examined. This is shown in FIG. At this time, the fixing condition was such that the thickness of the tube 20 was 10 μm, the elastic layer hardness of the fixing roll was 40 degrees, and the thickness was 0.7 mm. Also, the strain rate ε _RI is fixed at 0.5%,
_The amount of abrasion of the fixing roll 12 was examined by changing _RO .

As can be seen from FIG. 6, the distortion ratio is 1.
When the value is larger than 2, wrinkling of the tube 20 is not remarkable (see Table 7), but it can be seen that the abrasion of the tube 20 at the portion where the end in the width direction of the sheet P abuts becomes remarkable.

Further, the paper P was subjected to a wrinkle generation test. The results are shown in Table 7.

[0104]

[Table 7]

According to this, it can be seen that no paper wrinkles are observed even if the distortion ratio is greater than 1.

From these results, it can be seen that the degree of wrinkling is governed only by the ratio of the strain rate irrespective of the hardness and thickness of the heat-resistant elastic layer 18 or the thickness of the tube 20.
It is considered that the ratio of the strain rate is suitably 0.5 ≦ ε _RO / ε _RI ≦ 1.2, and preferably 0.5 ≦ ε _RO / ε _RI ≦ 1.0.

<Wrinkling of Tube and Wrinkling of Paper at a Strain Rate of 5%> Until now, a study was performed in the case where the strain rate at the center of the paper P in the width direction was relatively small, 0.5%. Have been. Then, when this is set to about 5%, the tube 2
The wear amount of 0, the wrinkles of the tube 20 and the degree of wrinkles of the paper P were examined. The conditions were such that the thickness of the tube 20 was 10 μm, the hardness of the heat-resistant elastic layer 18 was 10 degrees, and the thickness was 3 mm. The results are shown in FIG.

[0108]

[Table 8]

As can be seen from the graph, the distortion ratio deteriorates when the distortion ratio is less than 0.5, almost in the situation shown in FIG. 5 and Table 4. That is, even if the distortion rate is increased, the wrinkles of the tube 20 and the wrinkles of the paper P are governed by the ratio of the distortion rates.

Accordingly, the ratio of the strain rate is suitably 0.5 ≦ ε _RO / ε _RI ≦ 1.2, and from the viewpoint of reducing the amount of wear of the tube 20, preferably 0.5 ≦ ε _RO. It is considered that / ε _RI ≦ 1.0 is good.

<Positional relationship between the axial end of the tube and the longitudinal end of the pressurizing body> Next, the positions of both ends of the tube 20 in the axial direction and the longitudinal ends of the pressurizing body 36 were changed. Then, the tube 20 and the paper P were tested for wrinkles.

That is, in all of the above tests, as shown in FIG. 2, the longitudinal length L _PR of the pressurizing body 36 is longer than the axial length L _{R of the} tube 20, and the axial length of the tube 20 is is L _R is greater than L _PA the width of the paper P state, that is, _{L PR ≧ L R ≧ L PA} , moreover, the axial ends of the tube 20 is positioned outward from the widthwise end of the paper P, The test was performed in a state where both ends in the longitudinal direction of the pressurizing body 36 were located outside both ends in the axial direction of the tube 20. Therefore, the axial length L _{R of} the tube 20 is longer than the length L _{PR of the} pressing body 36 in the longitudinal direction,
In addition, the length L _{PR of the} pressing body 36 in the longitudinal direction is equal to the width of the paper P.
Longer state than _PA, that is, _{L R ≧ L PR ≧ L PA} , moreover, the axial ends of the tube 20 is positioned outward from the widthwise end of the paper P, the axial ends of the tube 20 is pressing body A similar test was performed in a state in which the outermost 36 was located outside both ends in the longitudinal direction. Table 9 shows the results.

[0113]

[Table 9]

As can be seen from Table 9, it was confirmed that wrinkles were generated in the tube 20 at the portion where the end of the pressurizing member 36 was in contact with the tube 20 irrespective of the ratio of the distortion rates.
This is because, unlike the portion where the widthwise end of the paper P of the fixing roll 12 is inserted, the distortion ratio becomes extremely small in the vicinity of the portion where the end of the pressurizing member 36 abuts. It is considered that wrinkles occur on the surface 20.

[0115]

According to the first aspect of the present invention, an elastic member formed in a cylindrical or columnar shape and capable of being elastically deformed at least radially inward, and a cylindrical member formed in a cylindrical shape on the outer periphery of the elastic member. A fixing roll including a fluorine-based resin layer having a thickness of 10 μm to 40 μm, and a transfer material to which an unfixed toner image is transferred between the fixing roll and a fixing roll disposed opposite to the fixing roll. Pressurizing means for fixing the toner image onto the transfer material and generating a distortion of 0.1% or more in the fixing roll by pressing the fixing roll radially inward, Both ends in the axial direction of the fluororesin layer are located outside the both ends in the width direction of the transfer material, and both ends in the width direction of the pressing unit are located outside the both ends in the axial direction of the fluororesin layer. So high Releasability and excellent image quality can be obtained. The deterioration of the fixing roll can be reduced without abrasion of the fluororesin layer or wrinkling of the fluororesin layer.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressing means is formed to be endless and deformable at least outward, and is disposed to face the fixing roll. A transport belt, and a support member that supports the transport belt in a circulable manner in contact with the fixing roll and partially deforms the transport belt outward to generate the distortion in the fixing roll. , Causing local distortion of the fixing roll by the support member,
The release performance of the fixing roll can be improved.

According to a third aspect of the present invention, in the second aspect of the present invention, since both ends in the width direction of the conveyor belt are located outside both ends in the width direction of the support member, respectively, Prevent wear by layer rubbing,
The fixing performance of the fixing roll can be maintained.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the transfer material nipped and conveyed between the fixing roll and the pressing means has a maximum width in the width direction. When the distortion rate of the fixing roll at the portion having is ε _RO , and the distortion rate at the approximate center in the axial direction of the fixing roll is ε _RI ,
Since 0.5 ≦ ε _RO / ε _RI ≦ 1.0, the transfer material does not wrinkle, and the durability of the fixing roll can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of a fixing device according to the embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a load of a pressing body and a distortion rate of a fixing roll in the fixing device according to one embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a load of a pressing body and a distortion rate of a fixing roll in the fixing device according to the embodiment of the present invention;
It is the graph which expanded a part of.

FIG. 5 shows a fixing device according to an embodiment of the present invention, in which the thickness of the tube is 10 μm and the heat-resistant elastic layer has a hardness of 40.
7 is a graph showing the relationship between the number of inserted papers and the amount of wear of the tube when the thickness and the thickness are 0.7 mm for each distortion ratio.

FIG. 6 shows a fixing device according to an embodiment of the present invention, in which a tube has a thickness of 10 μm and a heat-resistant elastic layer has a hardness of 40.
7 is a graph showing the relationship between the number of inserted papers and the amount of wear of the tube when the thickness and the thickness are 0.7 mm for each distortion ratio.

FIG. 7 shows a fixing device according to an embodiment of the present invention in which the thickness of the tube is 10 μm and the heat-resistant elastic layer has a hardness of 10 mm.
6 is a graph showing the relationship between the number of inserted sheets and the amount of wear of the tube when the thickness and the thickness are 3 mm for each distortion ratio.

FIG. 8 is a cross-sectional view illustrating a schematic configuration of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixing apparatus 12 Fixing roll 14 Pressure applying member (pressurizing means) 18 Heat resistant elastic layer (elastic member) 20 Tube (fluorine resin layer) 24 Supporter (supporting member) 28 Conveyor belt 36 Pressurizer

Claims (4)

[Claims] 1. An elastic member formed in a cylindrical or cylindrical shape and elastically deformable at least radially inward, and fluorine formed in a cylindrical shape on the outer periphery of the elastic member and having a radial thickness of 10 μm to 40 μm. A fixing roll provided with a base resin layer, and a transfer material on which an unfixed toner image is transferred between the fixing roll and the fixing roll disposed opposite to the fixing roll, and conveys the toner image to the transfer material. Pressurizing means for causing the fixing roll to generate 0.1% or more distortion by pressing the fixing roll inward in the radial direction and fixing both ends of the fluororesin layer in the axial direction. Are respectively located outside both ends in the width direction of the transfer material, and both ends in the width direction of the pressing unit are respectively located outside both ends in the axial direction of the fluorine-based resin layer. . 2. A conveying belt formed in an endless manner and capable of being deformed at least outwardly, and arranged in a manner facing the fixing roll, wherein the pressing unit is in contact with the fixing belt. 2. The fixing device according to claim 1, further comprising: a support member that circulates the support belt and partially deforms the transport belt outward to generate the distortion in the fixing roll. 3. 3. The fixing device according to claim 2, wherein both ends in the width direction of the transport belt are located outside both ends in the width direction of the support member. 4. The distortion rate of the fixing roll at the portion where the transfer material nipped and conveyed between the fixing roll and the pressing means has the maximum width in the width direction is ε _RO , when the strain rate was _{ε RI, 0.5 ≦ ε RO /} ε RI ≦ 1.
The fixing device according to claim 1, wherein the fixing device is set to zero.