JPH11219052A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device by which the stable traveling performance of a belt is secured without changing the driving torque of the belt with time and an image having high quality is stably obtained. SOLUTION: This device possesses a fixing roll 10 having a heating source 14, an endless belt 20, and a pressing member 30 arranged in a non-rotating state at the inside of the endlless belt 20, and a nip 16 is formed by pressing the pressing member 30 to the fixing roll 10 through the endless belt 20. Also, a lubricant supplying member 40 to hold lubricant is provided on the inner peripheral surface of the endless belt 20. The lubricant supplying member 40 is desirably constituted of a holding member consisting of felt or the like and lubricant transmitting quantity regulating film obtained by drawing and molding a fluorinated resin and having many holes.

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 an image information recording apparatus using an electrophotographic method such as an electrophotographic copying machine, a printer, a facsimile, etc., by contact heating and fixing an unfixed toner image on a recording material. The present invention relates to a fixing device having an endless belt for fixing, which is used for a so-called heat fixing device.

[0002]

2. Description of the Related Art Conventionally, for example, as in a fixing device 1 shown in FIG. 9, a nip portion between a pair of heated heat fixing rolls 10 and a pressure roll 40 which are rotatably held by bearings and pressed against each other. A heat and pressure fixing roll type, which heats and fixes by passing a recording medium carrying an unfixed toner image through the fixing roller 16, is mainly used.

In the heat fixing roll 10, an elastic layer 12 made of silicone rubber or the like is formed on the outer peripheral surface of a core 11 made of hollow aluminum, and a release layer 13 is formed on the outer surface of the elastic layer 12. A heating source 14 is provided in the core 11, and a temperature-sensitive element 15 is in contact with the surface of the heating fixing roll 10. In the pressure roll 40, an elastic layer 42 such as silicone rubber is formed on the outer surface of a metal core 41.

In such a conventional heat-pressing roll type fixing system, the elastic layer 12 of one or both of the heat fixing roll 10 and the pressure roll 40 is used.
Since the nip region 16 is formed by deforming the nip portion 42, the following problem arises. That is, in order to form a nip having a certain width or more, the elastic layer 12 of one or both of the heat fixing roll 10 and the pressure roll 40,
42 must be relatively thick and the pressing force between these rolls must be high. This leads to an increase in the thickness of the elastic layer 12 and the core 11 of the heat fixing roll 10 and an increase in heat capacity of the heat fixing roll 10. In other words, there is a problem that the time required for raising the temperature of the heat fixing roll 10 from room temperature to a temperature at which fixing can be performed (hereinafter, referred to as “warm-up time”) becomes long.

On the other hand, in order to solve the above-mentioned drawbacks, the present inventor has proposed a fixing method in which a nip is formed using a fixed pressure member 30 and an endless belt 20 as shown in FIGS. (Japanese Unexamined Patent Publication No. Hei 8-262903).
No.). There is also a fixing method in which a nip is formed using a fixed heating element and an endless belt.

[0006]

However, the fixing system in which the endless belt as described above slides on a fixed pressure member or a heating element has the following problems. That is: 1. If the coefficient of friction between the endless belt and the fixed member is large, the torque for driving the endless belt increases.
Therefore, the stress acting on the fixing roll for driving the endless belt, that is, the driving torque also increases. As a result, the stress acting on the gear receiving portion of the thin fixing roll core is increased, and the gear and the core are damaged. Naturally, the load on the drive motor also increases. 2. If the frictional force between the endless belt and the fixing member is not negligible compared to the driving force of the belt by the fixing roll, slip occurs between the driving fixing roll and the endless belt. When the recording medium holding the unfixed toner image is passed through the nip portion under the condition where the slip occurs, the slip causes an image shift in the unfixed toner image on the recording medium. 3. The frictional force can be reduced by interposing a lubricant such as grease between the endless belt and the fixing member. However, the grease wraps around and adheres to the fixing roll, deteriorating the releasability of the toner. 4. As described in Japanese Patent Application Laid-Open No. Hei 8-262903, the torque for driving the belt is initially reduced by interposing silicone oil as a lubricant between the endless belt and the fixing member. Can be reduced. However, when the belt is driven for a long time, the lubricant is depleted or deteriorates with time due to heat and pressure, so that the frictional force increases with time and the driving torque of the belt further increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to secure stable running performance of an endless belt without changing the driving torque of the endless belt with the passage of time. An object of the present invention is to provide a fixing device capable of stably obtaining an image.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on the fixing device to achieve the above object, and as a result, have completed the present invention. That is, <1> a rotatable fixing member having a heat source, an endless belt, and a pressing member arranged in a non-rotating state inside the endless belt, and the pressing member is provided via the endless belt. Is pressed against the fixing member to form a nip, and the recording sheet is passed between the fixing member of the nip and the endless belt to fix an unfixed toner image on the recording sheet. A fixing device having a lubricant supply unit for holding a lubricant on an inner peripheral surface of a belt. <2> The fixing device according to <1> U, wherein the lubricant supply mechanism includes a lubricant supply member disposed so as to be in contact with an inner peripheral surface of the endless belt. <3> The fixing device according to <2>, wherein the lubricant supply member has a porous lubricant permeation regulating film on a contact surface side with the inner peripheral surface of the endless belt. <4> The lubricant supply member according to any one of <1> to <3>, wherein the lubricant supply member is disposed so as to come into contact with the inner peripheral surface of the endless belt at a position near the nip portion. It is a fixing device. <5> The lubricant supply member according to any one of <1> to <3>, wherein the lubricant supply member is disposed so as to come into contact with the inner peripheral surface of the endless belt in a vertically lower vicinity position. It is a fixing device. <6> The lubricant supply member, wherein a lubricant supply amount near an axial center of the endless belt is larger than a lubricant supply amount near an end of the endless belt. A fixing device according to any one of <1> to <5>. <7> The fixing device according to <1>, wherein a lubricant supply unit is provided in the pressing member.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fixing device according to the present invention includes a fixing roll, a pressing member (also referred to as a pressing pad), and an endless belt provided with a lubricating release layer on a surface that slides in contact with the pressing member. At least a lubricant supply means for holding a lubricant on the inner peripheral surface of the endless belt is provided, and other means appropriately selected as necessary, for example, a release agent (oil or the like) supply means to the heat fixing roll May be provided.

FIG. 1 is a schematic sectional configuration diagram showing a preferred embodiment of the fixing device of the present invention, and FIG. 2 is a schematic perspective configuration diagram of FIG. The fixing device includes a heat fixing roll 10, a thin-film endless belt 20, and a pressing member (press pad) 30. The endless belt 20 is pressed against the fixing roll 10 by a pressing pad 30 disposed inside the endless belt 20, and a nip portion 16 through which a recording sheet can pass is formed between the fixing roll 10 and the endless belt 20.

The pressing pad 30 includes a support 31, an elastic body 32 disposed on the support 31, a low friction film 22 stretched on a contact surface of the elastic body 32 with the endless belt 20, 20 comprises a belt running guide 34 provided to rotate smoothly.

A low friction film 33 is provided on the surface of the elastic body 32.
Are arranged, and on the surface of the belt traveling guide 34,
A rib is provided in the belt rotation direction to reduce the contact area with the inner peripheral surface of the endless belt 20. Both ends of the belt travel guide 34 are provided with flange-shaped members (not shown) for restricting the shift of the endless belt 20. The support 31 has a function of fixing the elastic body 32, and the support 31 is a thin-film endless belt 2.
The fixing roller 10 is pressed by a compression coil spring (not shown) through the fixing roller 10.

The surface of the lubricant supply member 40 is arranged on the belt running guide 34 so as to be able to contact the inner peripheral surface of the endless belt 20. The lubricant supply member 40 includes a lubricant holding member 41 and a lubricant permeation amount regulating film 41,
It is provided near the entrance of the nip portion 16.

The shape, structure, size and the like of the fixing roll 10 are not particularly limited, and may be appropriately selected from those known per se according to the purpose. The fixing roll 10 generally has a cylindrical core 1.
1, an elastic layer 12 and a release layer 13 formed on the surface thereof, and a heating source 14 is provided inside the core.

The material of the core 11 is not particularly limited as long as it is a material having excellent mechanical strength and good heat conductivity. Examples of the material include metals and alloys such as aluminum, SUS, iron, copper, and brass. Ceramics, FRM and the like can be mentioned.

The material of the elastic layer 12 can be appropriately selected from those known as the elastic layer, and examples thereof include silicone rubber and fluorine rubber. In the present invention, among these materials, silicone rubber is preferred because of its low surface tension and excellent elasticity and thermal stability. As the silicone rubber, for example, RTV
Silicone rubber, HTV silicone rubber, and the like;
Specifically, polydimethyl silicone rubber (MQ), methyl phenyl silicone rubber (PMQ), methyl vinyl silicone rubber (VMQ), fluorosilicone rubber (FVMQ) and the like can be mentioned. The thickness of the elastic layer 12 is usually 3 mm or less, preferably 0.5 mm or less.
１．５1.5 mm.

The method for forming the elastic layer 12 on the surface of the core 11 is not particularly limited, and for example, a known coating method or the like can be employed. Examples of the coating method include kneader coating, bar coating, curtain coating, spin coating, and dip coating. In the present invention, dip coating can be suitably used among them.

In the present invention, a release layer 13 may be formed on the surface of the elastic layer 12. Release layer 13
Is advantageous in that the offset of the toner image can be suitably prevented, and the image fixing device can be operated in a stable state. The material of the release layer 13 is not particularly limited as long as it shows an appropriate release property to the toner image. For example, fluorine rubber, silicone rubber,
Fluororesin and the like can be mentioned. Among them, fluororubber is preferred.

Examples of the fluorine rubber include vinylidene fluoride rubber, fluorosilicone rubber, tetrafluoroethylene / propylene rubber, fluorophosphazene rubber, and tetrafluoroethylene-perfluorovinyl ether (perfluoro) rubber. Rubber and the like. The thickness of the release layer 13 is usually 5 to 10
0 μm, preferably 10 to 30 μm. The method for forming the release layer 13 on the surface of the core 11 is not particularly limited, and examples thereof include the above-described coating method. In the present invention, dip coating can be suitably used among them.

The release layer 13 may be supplied with a release agent such as silicone oil or fluorine oil. The release agent supply means is not particularly limited as long as it has a function of supplying the release agent to the surface of the fixing roll 10, and can be appropriately selected from known ones according to the purpose.

The heating source 14 is not particularly limited as long as it has a shape and structure that can be accommodated inside the core 11, and can be appropriately selected according to the purpose. Examples thereof include a halogen heater. Can be The heating source 14
The surface temperature of the heating and fixing roll 10 heated by, for example, can be measured by a temperature-sensitive element 15 provided on the heating and fixing roll, and the temperature can be controlled to be constant by control means.

The temperature sensing element 15 is not particularly limited, and includes, for example, a thermistor and a temperature sensor. The control means is not particularly limited, and includes, for example, a temperature controller and a computer.

The shape and size of the endless belt 20 are not particularly limited, and can be appropriately selected from those known per se according to the purpose. As the endless belt 20, a belt formed in a band shape and endless is generally used. The structure of the endless belt 20 may be a single layer structure, but the figure shows a multilayer structure. In the case of the endless belt 20 having the multilayer structure, it is preferable that the endless belt 20 has a lubricating release layer 22 on a surface of the base material layer 21 that contacts the pressing pad 30. Base layer 2 of endless belt 20
Examples of the material 1 include polymers such as thermosetting polyimide, thermoplastic polyimide, polyamide, and polyamideimide, and metal belts such as stainless steel, nickel, and copper. Among these, thermosetting polyimides are preferred because of their excellent heat resistance, abrasion resistance, chemical resistance and the like.

The lubricating release layer 22 may be made of a fluororesin, rubber, silicon compound, or the like. For example, the fluororesin may be a perfluoroalkoxy fluororesin (PF).
A), polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polyethylene / tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), Examples thereof include vinyl fluoride (PVF). As fluororubber,
Examples thereof include vinylidene fluoride rubber, tetrafluoroethylene-propylene rubber, fluorophosphazene rubber, and tetrafluoroethylene-perfluorovinyl ether rubber. Examples of the silicon compound include silicone rubbers such as polydimethylsilicone rubber, methylvinylsilicone rubber, methylphenylsilicone rubber, and fluorosilicone rubber. Particularly preferred are silane compounds, silicone resins, and modified compounds having a reactive group in the molecule. A lubricating release layer formed using a composition containing at least two or more selected from the group consisting of silicone oils is preferred.

The shape, structure, size and the like of the pressing pad 30 are not particularly limited, and can be appropriately selected according to the purpose. For example, the pressing pad may have a structure composed of a single member or a structure composed of a plurality of members having different functions. In the present invention, it is preferable that the surface of the pressing pad is covered with a sheet formed by knitting fibers and impregnated with a fluororesin. In this case, the pressing pad is advantageous in that it is excellent in releasability and durability, and can stably heat and fix an image for a long period of time while preventing offset. The fibers include, for example, glass fibers and carbon fibers, among which glass fibers are preferable in terms of abrasion resistance.

The material of the elastic body 32 includes, for example, silicone rubber, fluorine rubber and the like. Examples of the low friction film 33 include a fluororesin sheet such as a Teflon resin and a glass fiber sheet impregnated with a fluororesin.

The pressing pad 30 is provided on the endless belt 20.
, The fixing roller 10 is pressed with a constant load by an urging member (not shown) such as a compression coil spring. In other words, the pressing pad 30 is pressed by the urging member such as a compression coil spring through the endless belt 20 with a constant load against the heat fixing roll 10. When the motor which is the driving source of the fixing roll 10 is driven, the fixing roll 10 is rotationally driven. The thin-film endless belt 20 rotates at a constant speed according to the rotation of the fixing roll 10.

In the present invention, a lubricant may be applied between the surface of the pressing pad 30 and the inner surface of the endless belt 20. For example, silicone oil, fluorine oil, grease and the like are used. This lubricant is applied to the inner surface of the belt.
And may adhere to the fixing roll
Those having releasability are desirable. Further, in consideration of safety issues, silicone oil is preferable to fluorine oil.

As the silicone oil, for example,
Examples include dimethyl silicone oil, amino-modified silicone oil, carboxy-modified silicone oil, silanol-modified silicone oil, and sulfonic acid-modified silicone oil. Among these, an amino-modified silicone oil is preferable because the starting torque and the driving torque of the image fixing device can be effectively maintained in desired low ranges, and the handleability is excellent. Although the lubricant is not consumed, if used for a long period of time, it may sneak as described above, so that the lubricant gradually decreases and eventually becomes depleted. At this time, the torque increases. Therefore, the present invention includes the lubricant supply member 40 that holds and supplies the lubricant corresponding to the life of the fixing device so that the lubricant is not depleted.

The lubricant holding member 41 of the lubricant supply member 40 preferably has a large number of continuous pores, and has heat resistance at a fixing temperature and an appropriate elastic modulus. For example, felt, sponge, etc. No. The lubricant supply amount regulating film 42 of the lubricant supply member 40 is also provided.
A resin having a large number of continuous pores and having heat resistance at a fixing temperature and a small friction coefficient, for example, a resin or the like having heat resistance and a small friction coefficient is preferably stretch-formed, and is preferably a fluororesin. Is stretch-formed.

The lubricant holding member 41 is impregnated with a lubricant.
Is in contact with almost the entire area of the endless belt in the axial direction. When the endless belt 20 rotates, the lubricant is supplied to the entire inner peripheral surface of the endless belt 20. The lubricant supply does not need to be large, so
The contact pressure of the lubricant supply member 40 with respect to the endless belt 20 is small, and it is sufficient that the lubricant supply member 40 makes a slight contact.

It is important that a small amount of the lubricant is continuously supplied to the inner peripheral surface of the endless belt 20 for a long time. The amount of the lubricant to be supplied to the inner peripheral surface of the endless belt 20 is controlled by changing the porosity of the porous lubricant permeation control film 42 to thereby control the amount of the lubricant permeated through the lubricant permeation control film 42. It is done by doing.

The position of the lubricant supply member 40 is as follows.
The vicinity of the nip portion 16 on the inner peripheral surface of the endless belt 20 is preferable. The reason for this is that the endless belt 20 is in a state in which no tension acts, so that when the lubricant supply member 40 is pressed against the endless belt 20 at a position other than the nip portion 16, the endless belt 20 is easily deformed. On the other hand, tension is applied to the belt before and after the rotation of the nip portion 16 due to the nip load and the belt rigidity. Therefore, the above-described deformation can be eliminated by bringing the lubricant supply member 40 into contact with the endless belt 20 in this portion.

In the lubricant supply member 40, it is desirable that the amount of lubricant supplied near the axial center of the endless belt 20 be greater than the amount of lubricant supplied near the axial end of the endless belt 20. This is because the contact width of the lubricant supply member 40 near the center of the endless belt 20 is wider than the end, or the contact pressure of the lubricant supply member 40 near the center is stronger than the end. It is possible by doing. The supply amount is increased by making the contact width at the center of the lubricant supply member 40 wider than at the end. This affects wrinkles during rotation of the endless belt 20. If the belt speed at the center is higher than the end speed, wrinkling of the belt does not occur, but if the belt speed at the center is lower than the end speed, wrinkles are likely to occur on the belt. Therefore, the supply amount of the lubricant is set to be larger at the central portion than at the end portions, so that the central portion of the belt can easily travel and wrinkles are prevented.

The lubricant supply member 40 is attached to the outer surface of the belt running guide 34,
0 is in weak contact with the inner peripheral surface. Lubricant supply member 40
Are arranged near the nip entrance. On the entrance side of the nip portion, the rotation of the endless belt 20 exerts a force for pressing the belt against the traveling guide. Therefore, by providing the lubricant supply member 40 here, the belt can be pressed without escaping. Further, the lubricant supply member 4
0 is preferably attached near the vertically lower part of the belt travel guide 34. In this case, it is possible to prevent oil accumulation in the belt when left for a long time. In order to satisfy both conditions, it is desirable to dispose a fixing device in which the nip entrance side is vertically downward.

In the fixing device of the present invention, the fixing roll 10 is rotatably disposed. The endless belt 20 is disposed so as to be able to run while a part of the outer peripheral surface thereof is in contact with the fixing roll. The pressing pad 30
It is arranged inside the endless belt 20, and between the endless belt 20 and the fixing roll 10,
The endless belt 2 is formed so that a nip portion 16 through which a recording sheet holding an unfixed toner image can pass is formed.
0, the fixing roll 10 is pressed. A lubricant, for example, a silicone oil is interposed between the pressing pad 30 and the endless belt 20.

Therefore, when the fixing roller 10 is driven to rotate, the endless belt 20 is also rotated following the rotation of the fixing roller 10. At this time, the fixing roll 10
Nip 1 formed between the belt and the endless belt 20
When there is a recording sheet holding an unfixed toner image at the entrance of No. 6, the recording sheet is taken into the nip 16 and passes through the nip 16. In the nip portion 16, the fixing roll 10 and the endless belt 20 pressed toward the fixing roll 10 by the pressing pad 30 form
The recording sheet is pressed and heated. as a result,
The toner image on the recording sheet is heat-fixed on the recording sheet.

At this time, when a release agent is applied between the toner image and the fixing roll 10, defects such as offset due to the adhesion of the toner image and the fixing roll 10 do not occur. On the other hand, since silicone oil as a lubricant is interposed between the endless belt 20 and the pressing member 30, there is no problem such as slippage between the rotation of the fixing roll 10 and the rotation of the endless belt 20, Smooth rotation drive is ensured, and smooth heat fixing of an image can be repeatedly performed.

In the fixing device shown in FIGS. 1 and 2, the fixing roll 10 is disposed above the endless belt 20, and the recording sheet moves substantially horizontally. In the case of a fixing device in which the endless belt 20 and the fixing roll 10 are arranged in a substantially horizontal direction and the recording sheet moves substantially vertically as shown in FIG.
The lubricant supply member 40 can be arranged in the vicinity of the nip portion 16 or in the vicinity of the inner circumferential surface of the endless belt 20 as shown in the figure, vertically below.

Further, in the above-described embodiment, the pressing pad 30 and the lubricant supply member 40 are provided separately, but the pressing pad 30 itself may have a lubricant supplying means. In this case, for example, the pressing pad 3
The elastic body 32 is formed of a heat-resistant porous body such as fluororubber having a predetermined hardness, and a fluororesin film is stretch-formed on the surface of the porous body to form a lubricant permeation regulating film. Made of a material having an elastic modulus of
2 may hold a lubricant. In the case of this fixing device, there is an advantage that the device can be simplified.

Further, the fixing device of the present invention is effective for a fixing device having a member that slides in contact with an endless belt, and presses a fixed heating element against a pressure roll via an endless belt. The fixing method in which the nip is formed is also effective in the fixing method in which the heating element and the endless belt are in contact and slide.

[0042]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Embodiment 1 In the fixing device shown in FIGS.
Is a silicone HTV rubber (rubber hardness: 45 degrees: JIS-A) as an elastic layer 12 on the outer surface of a cylindrical iron core 11 having an outer diameter of 30 mm, a thickness of 0.35 mm, and a length of 360 mm.
Was coated to a thickness of 500 μm, and the surface of the elastic layer 12 was dip-coated with fluoro rubber as a release layer 13 so as to have a thickness of 30 μm to finish the mirror surface. Inside the core 11, a 600-w halogen lamp 14 is used as a heating source.
And the surface temperature of the fixing roll 10 is
The temperature was controlled at 150 ° C. by a temperature sensor of the temperature-sensitive element 15 arranged in contact with the surface of No. 0 and a temperature controller (not shown). In addition, a viscosity of 300 as a release agent
The amino-modified silicone oil of CS was uniformly supplied to the surface of the release layer 13 of the fixing roll 10 by an oil supply system (not shown).

The endless belt 20 has a circumference of 94 mm,
A thermosetting polyimide having a thickness of 75 μm and a length of 320 mm was used as the base material 21, and the outer peripheral surface of the base material 21 was coated with a perfluoroalkoxy fluororesin (PFA) to a thickness of 30 μm to form a release layer 22. The elastic body 32 has a width of 1
0 mm, a thickness of 5 mm, and a length of 320 mm are silicone rubber, and the low friction film 33 disposed on the surface thereof is:
It is a glass fiber sheet impregnated with Teflon resin. Further, the heat-fixing roll 10 is moved by a compression coil spring (not shown) through a thin-film endless belt 20.
It is pressed with a load of 0 kg.

Endless belt 20 to fixing roll 10
Is about 40 °, and at this time, the nip 1
The width of 6 was about 10 mm. The driving force from the motor was transmitted to the fixing roll 10, and the fixing roll 10 and the endless belt 20 were rotated at a speed of 160 mm / sec. The surface of the pressing pad 30 is covered with a glass fiber sheet (FGF-400-4) impregnated with Teflon manufactured by Chuko Kasei Kogyo Co., Ltd. as a low friction sheet 33.

Between the surface of the pressing pad 30 and the inner surface of the endless belt 20, an amino-modified silicone oil (viscosity at room temperature: 300 CS) is interposed as a lubricant. In the first embodiment, since the lubricant used is the same oil as the release agent supplied to the heat fixing roll 10,
Even if the release agent and the lubricant are mixed, the problem of poor release does not occur.

Here, the lubricant supply member 40 is provided with a lubricant holding member.
Holding member 41 and a transmission amount regulating film 42,
The material 41 has a width of 10 mm at the center and 7 mm at the end, and a thickness of 5 m.
m, amino-modified to felt with length of 300mm as lubricant
5cm silicone oil ^ThreeImpregnated. Transmission amount
The regulating film 42 is formed by stretching a fluororesin film.
(Goretex GT sheet)
30 μm, porosity is 40-50%.

The fixing roller 10 and the endless belt 20 are continuously driven without bringing the lubricant supply member into contact with the inner surface of the endless belt 20 (the sliding surface with the pressure pad).
The driving torque was measured. FIG. 4 shows the results. In FIG. 4, the solid line indicates the case where the fixing roll is heated to 150 ° C., and the broken line indicates the case where the room temperature is 25 ° C. In these figures, the driving torque has a certain correlation with the dynamic friction coefficient, that is, the driving torque has a correlation of 1 kg · cm = dynamic friction force (coefficient) 0.022. It can be considered to mean the sliding resistance between the inner surface of the belt 20 and the surface of the low friction sheet 33 in the pressing pad 30. In the initial stage (time 0 hour), the torque at 150 ° C / 25 ° C is 3.1kg · cm / 4.6 each.
What was kg · cm increased to 4.2kg · cm / 7.8kg · cm by operating for about 80 hours. In the confirmation after the operation, there was almost no amino-modified oil at the interface between the endless belt 20 and the pressing pad 30. It can be said that the torque increases due to the depletion of the lubricant. On the other hand, when the lubricant supply member 40 is attached and the lubricant is supplied to the inner peripheral surface of the belt, even after being operated for 80 hours as shown in FIG. 5, the weight becomes 3.6 kg · cm / 5.2 kg · cm. Has been improved.

In the first embodiment, the amino-modified silicone oil as a release agent is supplied to the surface of the fixing roll 10 in order to improve the toner releasability. When the amount of the silicone oil increases, the frictional force between the fixing roll 10 and the outer peripheral surface of the endless belt 20 decreases, and the slip easily occurs.
Here, the relationship between the amount of the amino-modified silicone oil as a release agent applied to the surface of the fixing roll 10 and the speed of the endless belt when the torque was changed was investigated, and the results as shown in FIG. was gotten. The heat fixing roll 10 was rotated at a speed of 160 mm / s. A region where a slip starts to occur between the fixing roll 10 and the endless belt 20 is indicated by a thick line.

In Example 1, the temperature of the fixing roll was
The driving torque at 150 ° C is 3.1 to 3.6 kg
cm, and the amount of the amino-modified silicone oil as a release agent is 1 to 5 μ1 / A4, so that the endless belt 20 does not slip at 150 ° C. Therefore, no image shift occurs during the fixing operation.

Example 2 Example 2 was carried out in the same manner as in Example 1 except that the following points were changed. That is, in Example 1, the inner surface of the endless belt 20 (the sliding surface with the pressure pad)
A lubricating release layer made of a silicon compound was formed. As the silane compound, 20 parts of tetraisocyanate silane, 2 parts of silicone resin (YSR3022: manufactured by Toshiba Silicone Co., Ltd.),
As a modified silicone oil, 18 parts of an amino-modified silicone oil (TSF4702: manufactured by Toshiba Silicone Co., Ltd.) was stirred and mixed with 300 parts of ethyl acetate to obtain a coating liquid. This was dip-coated on an endless belt previously subjected to a primer treatment on the inside of the endless belt, air-dried, and then heat-treated in an oven at 120 ° C. for 3 minutes to provide a lubricating release layer. By forming the lubricating release layer, the driving torque can be reduced even if there is no lubricant supply component as shown in FIG.
It is greatly reduced as compared to. However, it tends to increase over time. By providing a lubricant supply member to this, the increase with time is almost eliminated as shown in FIG.

[0051]

According to the present invention, the above-mentioned problems in the prior art can be solved, and stable running performance of the belt can be ensured without lowering the releasability of the fixing roll, and high quality can be obtained. And an image fixing device capable of stably obtaining the image of (1). That is, the starting torque and the driving torque of the fixing roll caused by the frictional force between the inner peripheral surface of the endless belt and the pressing member can be effectively reduced, and the load is applied to the core of the fixing roll, especially the gear portion. The stress can be effectively reduced, and breakage of the core can be prevented. Further, since the torque of the motor itself can be reduced, the operation cost can be reduced. Further, by reducing the frictional force between the inner peripheral surface of the endless belt and the pressing member, the slip of the endless belt does not occur, and even when the recording sheet holding the unfixed toner image is passed through the nip portion, the image is not removed. The image can be fixed smoothly without causing displacement or disturbance.

[Brief description of the drawings]

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

FIG. 2 is a schematic perspective configuration diagram of FIG.

FIG. 3 is a schematic sectional configuration view showing another preferred embodiment of the fixing device of the present invention.

FIG. 4 is a graph showing a relationship between a fixing roll torque and a rotation time at a predetermined temperature when a lubricant supply member does not contact an endless belt.

FIG. 5 is a graph showing a relationship between a fixing roll torque and a rotation time at a predetermined temperature when a lubricant supply member is in contact with an endless belt.

FIG. 6 is a graph showing the relationship between the torque of the fixing roller and the amount of amino-modified silicone oil, with respect to the slip of the endless belt when the fixing roller is rotated at a constant speed.

FIG. 7 is a graph showing the relationship between the rotation time and the torque of the fixing roll at a predetermined temperature when a lubricant release layer is formed on the inner peripheral surface of the endless belt and the lubricant supply member is not in contact with the endless belt. It is.

FIG. 8 is a graph showing the relationship between the torque of the fixing roll and the rotation time at a predetermined temperature when a lubricant release layer is formed on the inner peripheral surface of the endless belt and the lubricant supply member is in contact with the endless belt. It is.

FIG. 9 is a schematic sectional configuration diagram showing an example of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixing roll 11 Core 12 Elastic layer 13 Release layer 14 Heat source 16 Nip part 20 Endless belt 21 Base layer 22 Lubricant release layer 30 Pressing member (press pad) 31 Support body 32 Elastic body 33 Low friction film 40 Lubricant supply member 41 Lubricant holding member 42 Lubricant permeation regulating film

Claims (7)

[Claims] An endless belt having a heat source, a rotatable fixing member having a heat source, and a pressing member disposed in a non-rotating state inside the endless belt, wherein the pressing member is provided via the endless belt. A nip by pressing the fixing member against the fixing member, and fixing the unfixed toner image on the recording sheet by passing the recording sheet between the fixing member of the nip and the endless belt. A fixing device comprising: a lubricant supply unit for holding a lubricant on an inner peripheral surface of a belt. 2. The fixing device according to claim 1, wherein said lubricant supply means comprises a lubricant supply member disposed so as to be in contact with an inner peripheral surface of said endless belt. 3. The fixing device according to claim 2, wherein the lubricant supply member has a porous lubricant permeation regulating film on a contact surface side with the inner peripheral surface of the endless belt. 4. The endless belt according to claim 2, wherein the lubricant supply member is arranged so as to come into contact with the inner peripheral surface of the endless belt at a position near the nip portion.
3. The fixing device according to claim 1. 5. The lubricant supply member according to claim 2, wherein the lubricant supply member is disposed so as to come into contact with the inner peripheral surface of the endless belt near a position vertically below the inner peripheral surface.
3. The fixing device according to claim 1. 6. The lubricant supply member according to claim 1, wherein a lubricant supply amount near an axial center of the endless belt is larger than a lubricant supply amount near an axial end of the endless belt. The fixing device according to any one of claims 2 to 5, wherein 7. The fixing device according to claim 1, wherein the lubricant supply unit is provided in the pressure member.