JP2018146707A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnormal noise caused by stick slip phenomenon in a sliding part between a fixing sleeve and a base member, with a simple configuration.SOLUTION: A fixing apparatus 20 includes: a fixing sleeve 21 having both ends held in sliding contact with a holding unit 50 so as to circulate; a halogen heater 70 as a heat source heating the fixing sleeve 21; a nip forming member 80 as a base member in contact with an inner periphery of the fixing sleeve 21; a pressure roller 22, as a pressure member, which is arranged opposite the fixing sleeve 21 to form a nip part N with the nip forming member 80 in contact with the fixing sleeve 21, and rotated in the contact state to rotate the fixing sleeve 21; and seal sections 91, 92 with labyrinth structure arranged at both ends of the fixing sleeve 21.SELECTED DRAWING: Figure 2B

Description

The present invention relates to a fixing device and an image forming apparatus. More specifically, the present invention relates to a fixing device provided with a labyrinth seal portion at both ends of a fixing sleeve 21 and an image forming apparatus equipped with the fixing device.

In recent years, there has been a strong demand for energy saving and high speed for image forming apparatuses such as printers, copiers, and facsimiles. For example, a fixing device and an image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2007-334205 are known to meet this requirement.

As shown in FIG. 6, the fixing device includes a pipe-shaped metal heat conductor 200 disposed in an endless belt 100, and the metal heat conductor 200 guides the circumferential movement of the endless belt 100. . A heating source 300 such as a halogen heater is disposed in the metal heat conductor 200, and the endless belt 100 is heated by the heating source 300.

A pressure roller 400 is disposed so as to be able to contact the metal heat conductor 200 via the endless belt 100, and a nip portion N is formed between the pressure roller 400 and the metal heat conductor 200. When the pressure roller 400 is rotationally driven by a motor, the endless belt 100 rotates in a manner that rotates with the rotation.

Since the entire endless belt 100 is heated, the first print time from the heating standby time can be shortened, and the shortage of heat at the time of high-speed rotation can be solved. However, a direct heating type fixing device that directly heats the endless belt without using the metal heat conductor 200 has been widespread for further energy saving and first print time.

In the direct heating type fixing device, it is known that abnormal noise is generated in the sliding portion between the fixing sleeve 21 and the nip forming member 80 due to vibration caused by a stick-slip phenomenon. This is because the adhesion between the inner peripheral surface of the fixing sleeve 21 and the nip forming member 80 is improved when the thickness of the lubricant applied to the sliding portion is thin or the viscosity is high, and the fixing sleeve 21 is the pressure roller. This is because the low frequency chatter sound is generated due to the inability to follow the rotation.

The abnormal noise is likely to occur particularly in the case of high temperature and low linear velocity. As countermeasures, for example, as shown in Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-040420) and Patent Document 3 (Japanese Patent Application Laid-Open No. 2006-073012), Control is performed such as increasing the line speed or changing the linear velocity in accordance with the number of sheets to be passed.

However, if the linear velocity is detected and controlled in real time, the cost is increased by installing a linear velocity detection sensor and a new control program. In addition, it is indispensable to accurately predict the state of friction over time in a control that increases the linear speed in several stages, but the state of friction over time naturally varies due to variations in each fixing unit and variations in the usage environment. Therefore, it is not always easy to stabilize the fixing quality.

SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to suppress the diffusion of abnormal noise caused by the stick-slip phenomenon at the sliding portion between the fixing sleeve and the base member with a simple configuration.

In order to solve the above-described problems, a fixing device according to the present invention includes a fixing sleeve that is slidably held at both ends by a pair of holding portions disposed in the axial direction, and a heating source that heats the fixing sleeve. A base member that is in contact with the inner peripheral surface of the fixing sleeve between the pair of holding portions, and is disposed opposite to the fixing sleeve and is in contact with the fixing sleeve between the base member and the base member. A pressurizing member that forms a nip portion and is driven to rotate in the contact state to rotate the fixing sleeve, and a seal portion having a labyrinth structure disposed at both ends of the fixing sleeve. It is characterized by that.
It is characterized by that.

According to the present invention, by disposing a seal portion having a labyrinth structure at both ends of the fixing sleeve, it is possible to reduce air leakage from the inside of the fixing sleeve and to suppress the diffusion of noise due to the stick-slip phenomenon. it can.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a fixing device according to an embodiment of the present invention. 1 is a schematic longitudinal sectional view of a fixing device according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a situation where abnormal noise is generated by sliding of the fixing sleeve. FIG. 3 is a schematic longitudinal sectional view showing a seal portion of a labyrinth structure at a heater end of the fixing device according to the embodiment of the present invention. It is a schematic longitudinal cross-sectional view which shows the edge part structure of the conventional fixing device. It is a disassembled perspective view of the nip formation member which winds a fluorine-type fiber sheet. It is a perspective view of the base pad which wound the fluorine-type fiber sheet. It is a schematic sectional view of a conventional fixing device.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings for explaining the embodiments of the present invention, constituent elements such as members and components having the same function or shape are described once by giving the same reference numerals as much as possible. Then, the explanation is omitted.

(Image forming device)
First, an overall configuration and operation of an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. An image forming apparatus 1 shown in FIG. 1 is a tandem color laser printer. In the center of the apparatus main body, four image forming units 4Y, 4M, 4C, and 4K are provided. Each of the image forming units 4Y, 4M, 4C, and 4K contains developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. The configuration is the same except that.

Specifically, each of the image forming units 4Y, 4M, 4C, and 4K has a drum-shaped photoconductor 5 as a latent image carrier, a charging device 6 that charges the surface of the photoconductor 5, and a surface of the photoconductor 5. A developing device 7 for supplying toner and a cleaning device 8 for cleaning the surface of the photoreceptor 5 are provided. In FIG. 1, only the photoconductor 5, the charging device 6, the developing device 7, and the cleaning device 8 included in the black image forming unit 4 </ b> K are denoted by reference numerals. In the other image forming units 4 </ b> Y, 4 </ b> M, and 4 </ b> C, The reference numerals are omitted.

Under the image forming units 4Y, 4M, 4C, and 4K, an exposure device 9 that exposes the surface of the photoreceptor 5 is disposed. The exposure device 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoconductor 5 with laser light based on image data.

A transfer device 3 is disposed above the image forming units 4Y, 4M, 4C, and 4K. The transfer device 3 includes an intermediate transfer belt 30 as a transfer member, four primary transfer rollers 31 as primary transfer means, a secondary transfer roller 36 as secondary transfer means, a secondary transfer backup roller 32, and a cleaning device. A backup roller 33, a tension roller 34, and a belt cleaning device 35 are provided.

The intermediate transfer belt 30 is an endless belt and is stretched by a secondary transfer backup roller 32, a cleaning backup roller 33, and a tension roller 34. Here, when the secondary transfer backup roller 32 is driven to rotate, the intermediate transfer belt 30 runs (rotates) in the direction indicated by the arrow in the figure.

Each of the four primary transfer rollers 31 sandwiches the intermediate transfer belt 30 with each photoconductor 5 to form a primary transfer nip. Each primary transfer roller 31 is connected to a power source, and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to each primary transfer roller 31.

The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Similarly to the primary transfer roller 31, a power source is connected to the secondary transfer roller 36 so that a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the secondary transfer roller 36. It has become.

The belt cleaning device 35 includes a cleaning brush and a cleaning blade disposed so as to contact the intermediate transfer belt 30. The waste toner transfer hose extending from the belt cleaning device 35 is connected to the entrance of the waste toner container.

A bottle container 2 is provided in the upper part of the printer main body, and four toner bottles 2Y, 2M, 2C, and 2K containing replenishing toner are detachably attached to the bottle container 2. Replenishment paths are provided between the toner bottles 2Y, 2M, 2C, and 2K and the developing devices 7, and the toner bottles 2Y, 2M, 2C, and 2K are connected to the developing devices 7 through the replenishment paths. The toner is replenished.

On the other hand, at the lower part of the printer main body, a paper feed tray 10 that stores paper P as a recording medium, a paper feed roller 11 that carries the paper P out of the paper feed tray 10, and the like are provided. Here, the recording medium includes thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet and the like in addition to plain paper. A manual paper feed mechanism may be provided.

In the printer main body, a transport path R is provided for discharging the paper P from the paper feed tray 10 through the secondary transfer nip to the outside of the apparatus. In the transport path R, a pair of registration rollers 12 serving as transport means for transporting the paper P to the secondary transfer nip is disposed upstream of the position of the secondary transfer roller 36 in the paper transport direction.

Further, a fixing device 20 for fixing the unfixed image transferred onto the paper P is disposed downstream of the position of the secondary transfer roller 36 in the paper transport direction. Further, a pair of paper discharge rollers 13 for discharging the paper to the outside of the apparatus is provided downstream of the fixing device 20 in the paper conveyance direction of the conveyance path R. A discharge tray 14 for stocking sheets discharged outside the apparatus is provided on the upper surface of the printer main body.

(Basic printer operation)
Next, a basic operation of the printer according to the present embodiment will be described with reference to FIG. When the image forming operation is started, the respective photoconductors 5 in the respective image forming units 4Y, 4M, 4C, and 4K are rotationally driven clockwise by the driving device, and the surface of each photoconductor 5 is predetermined by the charging device 6. It is uniformly charged to the polarity.

The surface of each charged photoconductor 5 is irradiated with laser light from the exposure device 9 to form an electrostatic latent image on the surface of each photoconductor 5. At this time, the image information to be exposed on each photoconductor 5 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. In this way, toner is supplied to each electrostatic latent image formed on each photoconductor 5 by each developing device 7, whereby the electrostatic latent image is visualized (visualized) as a toner image. .

When the image forming operation is started, the secondary transfer backup roller 32 is driven to rotate counterclockwise in the figure, and the intermediate transfer belt 30 is caused to run in the direction indicated by the arrow in the figure. Then, a constant voltage or a constant current controlled voltage having a polarity opposite to the charging polarity of the toner is applied to each primary transfer roller 31. As a result, a transfer electric field is formed in the primary transfer nip between each primary transfer roller 31 and each photoconductor 5.

Thereafter, when each color toner image on the photoconductor 5 reaches the primary transfer nip as each photoconductor 5 rotates, the toner image on each photoconductor 5 is generated by the transfer electric field formed in the primary transfer nip. Are sequentially superimposed and transferred onto the intermediate transfer belt 30. Thus, a full color toner image is carried on the surface of the intermediate transfer belt 30. Further, the toner on each photoconductor 5 that could not be transferred to the intermediate transfer belt 30 is removed by the cleaning device 8. Thereafter, the surface of each photoconductor 5 is neutralized by the static eliminator, and the surface potential is initialized.

In the lower part of the image forming apparatus, the paper feed roller 11 starts to rotate, and the paper P is sent out from the paper feed tray 10 to the transport path R. The sheet P sent to the transport path R is timed by the registration roller 12 and sent to the secondary transfer nip between the secondary transfer roller 36 and the secondary transfer backup roller 32. At this time, a transfer voltage having a polarity opposite to the toner charge polarity of the toner image on the intermediate transfer belt 30 is applied to the secondary transfer roller 36, thereby forming a transfer electric field in the secondary transfer nip.

Thereafter, when the toner image on the intermediate transfer belt 30 reaches the secondary transfer nip as the intermediate transfer belt 30 rotates, the transfer electric field formed in the secondary transfer nip causes a transfer on the intermediate transfer belt 30. The toner images are transferred onto the paper P all at once. At this time, the residual toner on the intermediate transfer belt 30 that could not be transferred onto the paper P is removed by the belt cleaning device 35, and the removed toner is conveyed to a waste toner container and collected.

Thereafter, the paper P is conveyed to the fixing device 20, and the toner image on the paper P is fixed to the paper P by the fixing device 20. Then, the paper P is discharged out of the apparatus by the paper discharge roller 13 and stocked on the paper discharge tray 14.

The above description is an image forming operation when a full-color image is formed on a sheet. A single color image can be formed using any one of the four image forming units 4Y, 4M, 4C, and 4K. Two or three image forming units can be used to form a two-color or three-color image.

(Fixing device)
Next, the configuration of the fixing device 20 will be described with reference to FIGS. 2A to 5B. The fixing device 20 includes a fixing sleeve 21 as a rotatable fixing rotator, and a pressure roller 22 as a pressure member provided to face the fixing sleeve 21. Both end portions 21a of the fixing sleeve 21 are slidably held so as to be able to turn around by a pair of holding portions 50 arranged in a pair facing each other in the axial direction. The holding portion 50 is formed integrally with the mounting plate 42, and the mounting plate 42 is fixed to side plates 40 fixedly arranged on both sides of the fixing device 20 by bolts 41.

(Fixing sleeve)
Inside the fixing sleeve 21, a halogen heater 70 is disposed in the axial direction as a heating source for heating the fixing sleeve 21. Further, closer to the pressure roller 22 side than the halogen heater 70, a nip forming member 80 as a base member is disposed in the axial direction.

Between the halogen heater 70 and the nip forming member 80, a stay 25 as a support member that supports the nip forming member 80, and a reflecting member 26 that reflects light emitted from the halogen heater 70 to the inner peripheral surface of the fixing sleeve 21. Is arranged. Further, at both ends in the axial direction of the fixing sleeve 21, as will be described later with reference to FIGS. 2B and 4A, seal portions 91 and 92 having a labyrinth structure according to the embodiment of the present invention are disposed.

The temperature of the fixing sleeve 21 is detected by a thermopile 27 as a degree detecting means, and the temperature of the pressure roller 22 is detected by a thermistor 29 as a temperature detecting means. In addition, a separation member 28 that separates the sheet from the fixing sleeve 21 and a pressure unit that pressurizes the pressure roller 22 to the fixing sleeve 21 are provided.

The fixing sleeve 21 is composed of a thin and flexible endless belt member (including a film). In FIG. 2A, a state before the pressure roller 22 is brought into contact with the fixing sleeve 21 is indicated by a broken line.

Specifically, the fixing sleeve 21 can be a metal belt made of nickel, SUS, or the like. Alternatively, an inner peripheral side substrate formed of a resin material such as polyimide (PI) and an outer peripheral side formed of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) The release belt can be used as a resin belt.

The release layer is for preventing toner adhesion. An elastic layer formed of a rubber material such as silicone rubber, foamable silicone rubber, or fluorine rubber may be interposed between the base material and the release layer.

When the fixing sleeve 21 does not have an elastic layer such as silicone rubber, the heat capacity is reduced and the fixing property is improved. However, on the other hand, when the unfixed toner is crushed and fixed, minute irregularities on the surface of the belt are transferred to the image, which may cause uneven gloss in the solid portion of the image.

In order to prevent this, it is desirable to provide an elastic layer having a thickness of 100 μm or more. By providing an elastic layer having a thickness of 100 μm or more, minute irregularities can be absorbed by elastic deformation of the elastic layer, and occurrence of uneven gloss can be avoided.

(Pressure roller)
The pressure roller 22 includes a cored bar 22a, an elastic layer 22b made of foamable silicone rubber, silicone rubber, or fluorine rubber provided on the surface of the cored bar 22a, and a PFA provided on the surface of the elastic layer 22b. Alternatively, it is constituted by a release layer 22c made of PTFE or the like. The pressure roller 22 is pressed toward the fixing sleeve 21 by the pressing means and is in contact with the nip forming member 80 via the fixing sleeve 21.

Where the pressure roller 22 and the fixing sleeve 21 are in pressure contact, the elastic layer 22b of the pressure roller 22 is crushed to form a nip portion N having a predetermined width. In FIG. 2A, the shape of the nip portion N is flat, but may be a concave shape or other shapes. When the nip has a concave shape, the discharge direction of the leading end of the recording paper is closer to the pressure roller 22 and the separability is improved, so that jamming is suppressed.

The pressure roller 22 is configured to be rotationally driven via a gear from a drive source such as a motor provided in the printer main body. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing sleeve 21 at the nip portion N, and the fixing sleeve 21 is driven to rotate.

The cored bar 22a of the pressure roller 22 can be configured with either a hollow pipe or a solid rod. In the case where the cored bar 22a of the pressure roller 22 is configured by a hollow pipe, a heating source such as a halogen heater can be disposed therein.

The elastic layer 22b may be solid rubber, but if there is no heat source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing sleeve 21 is less likely to be taken away. Further, the fixing rotator and the counter rotator are not limited to being brought into pressure contact with each other, and may be configured to simply contact each other without applying pressure.

(Halogen heater)
Both end portions 70 a of the halogen heater 70 are fixed to the side plate 40 of the fixing device 20. The halogen heater 70 is configured to generate heat by being output controlled by a power supply unit provided in the printer body, and the output control is performed based on the detection result of the surface temperature of the fixing sleeve 21 by the thermopile 27. .

By such output control of the halogen heater 70, the temperature of the fixing sleeve 21 (fixing temperature) can be set to a desired temperature. The heating source for heating the fixing sleeve 21 may be a heating element other than the halogen heater.

(Nip forming member)
The nip forming member 80 includes a base pad 81 and a sliding sheet (low friction sheet) 82 provided on the surface of the base pad 81 as shown in FIGS. 5A and 5B. The base pad 81 is continuously disposed in the longitudinal direction over the axial direction of the fixing sleeve 21 or the axial direction of the pressure roller 22, and receives the pressure from the pressure roller 22 to change the shape of the nip portion N. decide.

The back side of the base pad 81 is fixedly supported by the stay 25. The front surface of the base pad 81 is strongly pressed by the pressure roller 22, but the nip forming member 80 is prevented from being bent by the support force of the stay 25. Thereby, a uniform nip width is obtained over the axial direction of the pressure roller 22.

In order to satisfy the function of preventing the nip forming member 80 from bending, the stay 25 is desirably formed of a metal material having high mechanical strength such as stainless steel or iron. The base pad 81 is also preferably made of a material that is hard to some extent in order to ensure strength. As a material of the base pad 81, resin such as liquid crystal polymer (LCP), metal, ceramic, or the like can be used.

The base pad 81 is made of a heat resistant member having a heat resistant temperature of 200 ° C. or higher. This prevents the nip forming member 80 from being deformed by heat in the toner fixing temperature region, and ensures a stable state of the nip portion N to stabilize the output image quality. For the base pad 81, polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether ether ketone (PEEK), etc. It is possible to use a heat resistant resin.

The sliding sheet 82 only needs to be disposed on the pressing surface of the base pad 81 facing the fixing sleeve 21. As a result, when the fixing sleeve 21 rotates, the fixing sleeve 21 slides with respect to the low friction sheet, whereby the driving torque generated in the fixing sleeve 21 is reduced, and the load due to the frictional force on the fixing sleeve 21 is reduced. The It is also possible to adopt a configuration without the sliding sheet 82.

(Reflective member)
The reflection member 26 is disposed between the stay 25 and the halogen heater 70. Examples of the material of the reflecting member 26 include aluminum and stainless steel. By arranging the reflection member 26 in this way, the light emitted from the halogen heater 70 toward the stay 25 is reflected to the fixing sleeve 21.

Thereby, it is possible to prevent the stay 25 from being heated unnecessarily due to radiant heat from the halogen heater 70, to increase the amount of light irradiated to the fixing sleeve 21, and to enable efficient heating of the fixing sleeve 21. Become. Note that the same effect can be obtained if the surface of the stay 25 is heat-insulated or mirror-finished instead of having the reflecting member 26.

The fixing device 20 according to the present embodiment is devised in various configurations in order to further improve energy saving and first print time. More specifically, the fixing sleeve 21 can be directly heated by the halogen heater 70 at a place other than the nip portion N (direct heating method). In this embodiment, in FIG. 2A, nothing is interposed between the halogen heater 70 and the left fixing sleeve 21, and radiant heat from the halogen heater 70 is directly applied to the fixing sleeve 21 at that portion.

The fixing sleeve 21 is thin and has a small diameter in order to reduce its heat capacity. Specifically, the thicknesses of the base material, the elastic layer, and the release layer constituting the fixing sleeve 21 are set in a range of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm, and the total thickness is set. It is set to 1 mm or less.

The diameter of the fixing sleeve 21 is set to 20 to 40 mm. In order to further reduce the heat capacity, the thickness of the entire fixing sleeve 21 is preferably 0.2 mm or less, and more preferably 0.16 mm or less. The diameter of the fixing sleeve 21 is preferably 30 mm or less.

In the present embodiment, the diameter of the pressure roller 22 is set to 20 to 40 mm so as to be equal to the diameter of the fixing sleeve 21. However, it goes without saying that the diameters of the fixing sleeve 21 and the pressure roller 22 are not limited to this configuration.

For example, the fixing sleeve 21 may be formed so that the diameter thereof is smaller than the diameter of the pressure roller 22. In that case, since the curvature of the fixing sleeve 21 at the nip portion N is smaller than the curvature of the pressure roller 22, the recording medium P discharged from the nip portion N is easily separated from the fixing sleeve 21.

As described above, when the diameter of the fixing sleeve 21 is reduced, the space inside the fixing sleeve 21 is reduced. By accommodating 70, the stay 25 and the halogen heater 70 can be arranged even in a small space.

In the present embodiment, the nip forming member 80 is formed as compact as possible in order to arrange the stay 25 as large as possible in a small space. Specifically, the width of the base pad 81 in the sheet conveyance direction is formed to be smaller than the width of the stay 25 in the sheet conveyance direction.

(Basic operation of fixing device)
With the above-described configuration, it is possible to realize a fixing device that can be warmed up quickly. The basic operation of the fixing device 20 according to the present embodiment will be described below with reference to FIGS. 2A and 2B. When the power switch of the printer main body is turned on, power is supplied to the halogen heater 70 and the pressure roller 22 starts to rotate clockwise in FIG. 2A. As a result, the fixing sleeve 21 is driven to rotate counterclockwise in FIG. 2A by the frictional force received from the pressure roller 22.

Thereafter, the sheet P carrying the unfixed toner image T in the image forming process described above is conveyed in the direction of the arrow A1 in FIG. 22 is fed into the nip portion N. Then, the toner image T is fixed on the surface of the paper P by heat from the fixing sleeve 21 heated by the halogen heater 70 and pressure applied between the fixing sleeve 21 and the pressure roller 22.

The paper P on which the toner image T is fixed is carried out from the nip portion N in the direction of arrow A2 in FIG. At this time, the paper P is separated from the fixing sleeve 21 by the leading edge of the paper P coming into contact with the leading edge of the separation member 28. Thereafter, the separated paper P is discharged out of the apparatus by the paper discharge roller 13 and stocked on the paper discharge tray as described above.

(First embodiment of seal part)
FIG. 2B is a longitudinal sectional view showing the first embodiment of the first seal portion 91 having a labyrinth structure. The first seal portion 91 is disposed in a holding portion 50 that holds the both end portions 21a of the fixing sleeve 21 so as to be slidable.

The labyrinth structure is a path in which a fluid flow path is complicated for the purpose of reducing fluid leakage. Since the flow path is bent, the resistance of the fluid flow is increased, the pressure loss of the fluid is increased, and the leakage amount can be reduced. The labyrinth structure is used in fluid flow paths such as air and oil in various fields.

The first seal portion 91 includes an outer flange portion 50a of the holding portion 50, an inner flange portion 50b, and an annular groove portion 50c having a predetermined depth formed between the inner and outer flange portions. Both end portions 21a of the fixing sleeve 21 are inserted into the groove portion 50c with a predetermined length.

When the both end portions 21a of the fixing sleeve 21 are inserted and supported in the groove portion 50c as described above, when the air in the fixing sleeve 21 tries to go outside, the inner peripheral surface of the both end portions 21a of the fixing sleeve 21 and the groove portion 50c. The inner edge portion 50c1 of the fixing sleeve 21 enters the gap between the inner edge portion 50c1 and flows to the innermost portion of the groove portion 50c, and then turns back in the opposite direction from the innermost portion. You have to go outside through the gap between 50c2.

Since air must flow through such a long flow path, air leakage from the inside of the fixing sleeve 21 is reduced. The abnormal noise due to the stick-slip phenomenon is generated when the inner peripheral surface of the fixing sleeve 21 vibrates at a portion sliding with the base pad 81 of the nip forming member 80 as shown in FIG.

The vibration of the air due to the vibration is transmitted to the outside as sound. By providing the first seal portion 91 having a labyrinth structure, air leakage from the inside of the fixing sleeve 21 can be reduced, and the diffusion of abnormal noise can be suppressed.

Since both end portions 21a of the fixing sleeve 21 have a certain amount of gap between the holding portion 50 in the axial direction and the radial direction, either the left or the right in the axial direction when the fixing sleeve 21 moves around in FIG. 2B. It tends to be eccentric. Therefore, when the fixing sleeve 21 is decentered in this way, the sealing on one side is maintained, but a gap may be formed on the opposite side.

If the first seal portions 91 having a labyrinth structure are provided at both ends of the fixing sleeve 21 as in the embodiment of the present invention, the end portion 21a of the fixing sleeve 21 is provided even when the fixing sleeve 21 is eccentric to the maximum extent. There are always overlapping portions (outer flange 50a and inner flange 50b) with a predetermined length. Therefore, even if the fixing sleeve 21 is eccentric as much as possible, it is possible to ensure the sealing property of the fixing sleeve 21 by the labyrinth structure and prevent the noise from being diffused.

Further, by improving the hermeticity of the fixing sleeve 21 with the first seal portion 91 having the labyrinth structure, the halogen heater 70 can be kept warm, and the power consumption of the halogen heater 70 can be reduced. The fixing device 20 is in a condition that volatile substances generated from the lubricant are likely to be scattered when the temperature is high, but the first seal portion 91 having a labyrinth structure is used as a pressing surface of the nip forming member 80 inside the fixing sleeve 21. It is also effective in preventing the silicone oil component of the lubricant used from flowing out.

(Second Embodiment of Seal Part)
FIG. 4A shows a second embodiment of the labyrinth structure seal portion (seal portion 92). In the second embodiment, attention is paid to a gap between both end portions 70a of the halogen heater 70 in the conventional fixing device. That is, in the conventional fixing device, as shown in FIG. 4B, both end portions 70a of the halogen heater 70 are supported on the side plate 40 via the ceramic insulator 71 and the support plate (support plate 42 in FIG. 2A).

The insulator 71 is for insulating and protecting the side plate 40 from the current flowing through the halogen heater 70, and is fixed to both end portions 70 a of the halogen heater 70. In the conventional fixing device, a relatively large gap is formed on the outer peripheral side of the insulator 71 (gap 65 shown in FIG. 2A).

For this reason, when an abnormal noise is generated due to a stick-slip phenomenon at the sliding portion of the fixing sleeve 21 and the nip forming member 80, the abnormal noise leaks to the outside through the gap 65 and becomes noise. Further, the high temperature inside the fixing sleeve 21 escapes from the gap 65 to the outside, so that the power consumption of the halogen heater 70 is wasted.

Further, volatile substances generated from the lubricant applied to the nip forming member 80 leaked out of the gap 65 to generate ultra fine particles (UFP). Since UFP pollutes the indoor environment, it is necessary to prevent its scattering.

Therefore, since the shape of the insulator 71 is arbitrary as long as it has an insulating function, the seal portion 92 is formed by attaching a step shape as shown in FIG. 4A to the insulator 71. In other words, the positioning block 60 is arranged outside the insulator 71, and the inner periphery of the positioning block 60 is shaped to match the step shape of the insulator 71. The positioning block 60 is fixed to the side plate 40 with a bolt or the like.

In the assembly process of the fixing device 20 of the second embodiment shown in FIG. 4A, when the halogen heater 70 is inserted into the fixing sleeve 21, the lever 71 of the one end portion 70a of the halogen heater 70 is abutted against the positioning block 60 in the axial direction. . Thereby, the axial positioning of the halogen heater 70 can be performed easily and accurately.

A fluid passage 61 is formed in a crank shape between the inner peripheral shape of the positioning block 60 and the outer peripheral shape of the insulator 71 as shown in FIG. 4A. Therefore, the sound and air in the fixing sleeve 21 cannot travel linearly in the axial direction as shown in FIG. 4B, and the traveling direction is blocked by the crank-shaped step 61a of the fluid passage 61 as shown in FIG. 4A. The first seal portion 91 of the first embodiment and the second seal portion 92 of the second embodiment described above can be used independently, but both the seal portions 91 and 92 are used. Thus, the sealing property of the fixing sleeve 21 can be further improved.

(About nip forming members)
As shown in FIGS. 5A and 5B, a sliding sheet 82 made of a fluorine-based resin fiber having good slidability is attached to the base pad 81 of the nip forming member 80, so that the inner peripheral surface of the fixing sleeve 21 and The sliding load during the period can be reduced. Fluorine-based resin, which is a sheet-like resin fiber material, has excellent friction and wear characteristics, and includes PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and ETFE (tetrafluoroethylene).・ Ethylene copolymer) has been commercialized in a fibrous form. The sliding sheet 82 formed of these resin fibers can easily infiltrate the lubricant and has a high effect of preventing the lubricant from flowing out. The sliding sheet 82 can be used by being attached to the base pad 81 by the method shown in FIGS. 5A and 5B, for example.

FIG. 5A is an exploded perspective view of the nip forming member 80. The sliding sheet 82 is wound around the base pad 81 in the direction of the arrow shown in the figure, and the holes 82 a and 82 b formed at both ends of the sliding sheet 82 are hooked on the convex portion 81 b of the base pad 81. Then, the presser fitting 83 is mounted on the convex portion 81 b, and the presser fitting 83 is fixed to the base pad 81 with a screw 85. Then, both end portions 81 a of the base pad 81 are screwed to both end portions of the stay 25 via the mounting bracket 84.

The sliding sheet 82 composed of sheet-like fibers has a different thread area on the surface depending on the weaving method from the back surface. The plain weave has the same area ratio on the surface of the warp and weft, but the twill or satin weave has more surface area on the surface than the weft.

When two or more kinds of fibers are knitted, the area of the fluorine-based resin is increased in the portion serving as the friction surface, and the area of the resin having a high strength or a high oil content is increased in the portion serving as the back surface. By doing so, the frictional wear characteristics of the sheet-like fiber 82 can be improved and a high-strength sheet can be obtained. “Toyoflon” (registered trademark) manufactured by Toray is a resin sheet in which two fibers of PTFE and PPS are woven, and has an effect of suppressing an increase in torque over time.

Further, instead of the sliding sheet 82, it is possible to reduce the friction load on the pressing surface by applying a ceramic or fluorine coating material to the pressing surface of the base pad 81 of the nip forming member 80. Examples of the coating material include fluorine-based PTFE and PFA, and these coating materials are suitable for improving the slidability of the base pad 81 because they have low reactivity with other materials and high heat resistance.

Ceramic coating materials are harder and harder to wear than fluorine coating materials, and ceramic coating materials are effective when it is desired to avoid an increase in the viscosity of the lubricant due to coating scraping. In addition, fluorine-based coating materials have better adhesion to metals than resins. For example, if the heat resistance of the resin is insufficient or if you want to increase the heat transfer in the axial direction, it is made of metal such as SUS. The base pad 81 may be coated with a fluorine-based coating material.

(About lubricant)
Fluorine-based fibers or coating materials with good slidability should be used by immersing a lubricant as a countermeasure against slidability in the high-temperature environment in the vicinity of the halogen heater 70 (measure to suppress increase in friction load). It is effective. As such a lubricant, fluorine grease or silicone oil having a high heat resistance temperature is suitable.

Fluorine grease is a lubricant in which a thickener is dispersed in a fluorine oil as a base oil to form a gel. Since the viscosity is higher than that of oil, it is effective as a countermeasure against spills from sliding parts. Examples of the fluorine grease include NOK Kluber-made varielta ("BARRIERTA" is a registered trademark), Knox lube ("NOXLUB" is a registered trademark), and the like.

Fluorine grease has a characteristic that viscosity torque increases due to its high viscosity. When speed fluctuations are required with high accuracy, such as slipping of the fixing sleeve 21, silicone oil having a high heat resistance and low viscosity is used, as with fluorine grease. And KF-968-100CS made by Shin-Etsu Silicone (registered trademark) is used.

The present invention has been specifically described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims. Needless to say. For example, the image forming apparatus is not limited to the tandem color printer described above, and may be a copying machine or a facsimile machine instead of a printer.

Moreover, it may replace with the pressure roller 22 as a pressure member, and may be the structure which combined the pressure belt or the pressure belt and the pressure roller. Further, the labyrinth structure of the first seal portion 91 and the second seal portion 92 is not limited to the illustrated example, and any labyrinth structure that improves the sealing performance of the fixing sleeve 21 can be employed.

1: Image forming device 2: Bottle housing portions 2Y, 2M, 2C, 2K: Toner bottle 3: Transfer device 4Y, 4M, 4C, 4K: Image forming portion 5: Photoconductor 6: Charging device 7: Developing device 8: Cleaning Device 9: Exposure device 10: Paper feed tray 11: Paper feed roller 12: Registration roller 13: Paper discharge roller 14: Paper discharge tray 20: Fixing device 21: Fixing sleeve 21a: Both ends 22 of the fixing sleeve 22: Pressure roller 22a : Core 22b: Elastic layer 22c: Release layer 25: Stay 26: Reflective member 27: Thermopile 28: Separating member 29: Thermistor 30: Intermediate transfer belt 31: Primary transfer roller 32: Secondary transfer backup roller 33: Cleaning backup Roller 34: Tension roller 35: Belt cleaning device 36: Secondary transfer roller 37: Guide plate 40: Side plate 4 : Mounting plate 41: Bolt 43: Support plate 50: Holding portion 50 a: Outer flange portion 50 b: Inner flange portion 50 c: Annular groove portion 50 c 1: Inner edge portion 50 c 2: Outer edge portion 60: Block 61: Fluid passage 61 a: Crank-shaped step 65: Clearance 70: Halogen heater 70a: Both ends of halogen heater 71: Insulator 80: Nip forming member (base member) 81: Base pad 82: Sliding sheet 91: First seal portion 92: Second seal portion 100 : Endless belt 200: metal heat conductor 200: heat resistant temperature 300: heating source 400: pressure roller N: nip part P: recording medium (paper)

JP 2007-334205 A JP 2008-040420 A Japanese Patent Application Laid-Open No. 2006-077302

Claims (9)

A fixing sleeve in which both ends are held in sliding contact with each other by a pair of holding portions disposed in the axial direction;
A heating source for heating the fixing sleeve;
A base member in contact with the inner peripheral surface of the fixing sleeve between the pair of holding portions;
A nip portion is formed between the fixing member and the base member in contact with the fixing sleeve, and the fixing sleeve is driven to rotate by being driven to rotate in the contact state. A pressure member (roller or belt);
A seal portion having a labyrinth structure disposed at both ends of the fixing sleeve;
A fixing device.   The fixing device according to claim 1, wherein the seal portion is disposed between the holding portion and both end portions of the fixing sleeve.   The fixing device according to claim 1, wherein the seal portions are disposed at both ends of the heater as the heating source disposed in the axial direction inside the fixing sleeve.   4. The fixing device according to claim 1, wherein a low friction material is disposed on a pressing surface of the base member that is in contact with an inner peripheral surface of the fixing sleeve.   The fixing device according to claim 4, wherein the low friction material is a fluorine resin fiber.   The fixing device according to claim 4, wherein the low friction material is a ceramic or fluorine coating material.   The fixing device according to claim 1, wherein a lubricant is applied to the base member.   The fixing device according to claim 7, wherein the lubricant is silicone oil or fluorine grease. An image forming apparatus equipped with the fixing device according to claim 1.

Images