JP2002174976A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device equipped with a releasing agent coating roller capable of restraining the coating amount of a releasing agent in the initial stage at the time of oil coating operation by the roller to a level that failure such as oil staining is not caused and increasing the coating amount of the releasing agent in a stable state at the time of oil coating operation by the roller to a level that failure such as offset is not caused, thereby preventing image noise from being produced. SOLUTION: This fixing device is equipped with a rotating member 34 for heat and pressure-fixing a toner image held on a sheet 10, and the releasing agent coating roller 50 holding the releasing agent for preventing offset to be applied to the member 34 inside. Then, the roller 50 is equipped with a releasing agent holding layer 56 provided on the surface of a core bar 55 and holding the releasing agent, a surface layer 57 provided on the surface side of the holding layer 56, and a middle layer 58 disposed between the holding layer 56 and the surface layer 57 and whose releasing agent holding ability is set to be larger than that of the holding layer 56 and of the surface layer 57.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device provided in an image forming apparatus such as an electrophotographic printer or a copying machine, and more particularly to a fixing device for fixing an image to a rotating member for heat and pressure fixing. The present invention relates to a fixing device having a mechanism for applying a release agent.

[0002]

2. Description of the Related Art Printers using an electrophotographic process,
2. Description of the Related Art An image forming apparatus such as a copying machine includes a fixing device for fixing an unfixed toner image held on a sheet as a recording medium. There are various fixing systems,
Generally, a pressure heating fixing method is widely used. The fixing device based on the pressure heating fixing system includes a belt system, a heat roller system, and the like depending on the specific form of the rotating member. For example, Japanese Patent Application Laid-Open No.
318001.

A fixing device using a pressure heating fixing method has a configuration in which a surface holding a toner among both surfaces of a sheet directly contacts a surface of a rotating member such as a fixing belt or a fixing roller. Is easily transferred to the rotating member side. For this reason, a so-called offset phenomenon occurs in which the toner fused to the rotating member is transferred again to the rear end of the sheet and soils the sheet, or is again transferred to the next conveyed sheet and soils the sheet. There is a disadvantage that it is easy. In order to prevent the occurrence of the offset phenomenon, the fixing device using the pressure heating fixing method has a mechanism for applying a releasing agent for improving the releasability between the rotating member and the toner to the rotating member. As the release agent, silicone oil (hereinafter, also simply referred to as "oil") is used.

[0004] Some conventional oil applying mechanisms include an oil applying roller for applying the oil held inside to a rotating member. The oil application roller includes a cylindrical body having a plurality of small holes formed on an outer peripheral surface thereof, and a porous elastic body such as a sponge covering the outer peripheral surface of the cylindrical body. It is provided. Then, the oil application roller is driven to rotate with the rotation of the rotating member, and the oil sealed and held inside the cylindrical body is applied to the surface of the rotating member through the porous elastic body.

[0005]

In the oil applying roller having the conventional structure, the amount of oil applied per sheet is not constant from the initial stage of the oil applying operation of the roller to a stable state, and the amount of oil applied during the oil applying operation of the roller is not constant. Many early in the
Steady state tends to be less. For this reason,
In a stable state during the oil application operation of the roller, there is a possibility that the amount of oil applied per sheet becomes small and offset occurs. On the other hand, simply raising the lower limit of the oil application amount in order to prevent offset in a stable state during the oil application operation of the roller increases the oil application amount in the initial stage of the oil application operation of the roller, and causes oil stains and the like. There is a possibility that image noise such as cloudiness of the image may occur. Here, it is conceivable to provide a blade for removing excess oil applied to a rotating member such as a belt so as to be able to freely contact and separate from the rotating member, but the provision of the movable blade complicates the configuration of the fixing device. However, there is a disadvantage that the control for moving the movable blade into and out of pressure is complicated.

The above publication (Japanese Patent Laid-Open No. 6-3180)
No. 01), the sheet holding the unfixed toner is conveyed so as to face the fixing belt, so that the unfixed toner on the sheet is transferred to the fixing belt and the pressure roller. Before reaching the nip portion where the nip is pressed, the nip is preheated to some extent by radiant heat from the fixing belt. Therefore, in the belt-type fixing device, the temperature at the nip portion of the fixing belt can be set lower than that in the roller fixing method, and as a result, the amount of oil applied can be reduced to about one tenth of the roller fixing method. It has been confirmed that there is.

To take advantage of such a belt-type fixing device, for example, Japanese Patent Application Laid-Open No. H11-13378.
As disclosed in No. 4, having a multilayer structure including at least an oil holding layer provided on the surface side of the core metal of the oil application roller and holding oil, and a surface layer provided on the surface of the oil holding layer, There is known an apparatus in which the oil holding capacity decreases from the oil holding layer toward the surface layer. By using the oil applying roller having the conventional structure, the oil application is surely prevented from being excessively applied at the initial stage of the oil application, but the oil applying operation becomes stable in, for example, about 1500 sheets in the structure. At this point, the oil supply is insufficient, only a very small amount of oil is applied, and the effect of preventing offset by applying oil is not substantially achieved.

The present invention has been made to meet such a demand, and the amount of the release agent applied at the initial stage of the oil application operation of the roller can be suppressed to a level that does not cause problems such as oil stains. A fixing device that includes a release agent application roller that can increase the amount of release agent application in a stable state during the oil application operation of the roller to a level that does not cause a problem such as offset, thereby preventing image noise from occurring. The purpose is to provide.

[0009]

Means for Solving the Problems The above-mentioned problems are solved,
According to one aspect of the present invention, a fixing device according to the present invention includes a rotating member for fixing a toner image held on a sheet by heat and pressure, and an offset applied to the rotating member. A release agent applying roller having a release agent holding roller therein, wherein the release agent applying roller is provided on a surface of a cored bar and holds a release agent. And a surface layer provided on the surface side of the release agent holding layer, and disposed between the release agent holding layer and the surface layer, and the release agent holding ability from the release agent holding layer and the surface layer And an intermediate layer that is set large.

According to a second aspect of the present invention, the fixing device is characterized in that the intermediate layer is disposed so as to directly contact the inner peripheral surface of the surface layer. .

According to a third aspect of the present invention, in the fixing device, the intermediate layer is disposed so as to be in direct contact with the outer peripheral surface of the release agent holding layer. Features.

According to a fourth aspect of the present invention, the amount of the release agent applied to the rotating member by the release agent application roller is set to be equal to or larger than the A4 size sheet.
It is characterized in that it is set within the range of 0.5 to 2.0 mg per sheet.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. << Overall Structure of Printer According to Embodiment >> FIG. 1 is a schematic configuration diagram showing an electrophotographic full-color printer incorporating a fixing device according to the present invention.

The printer 11 shown in FIG. 1 includes a photosensitive drum 12 as an image carrier and a laser generator 14, and is provided around the photosensitive drum 12 rotating in the direction of the arrow. Charging device 13 for charging the outer peripheral surface of
A developing device having first to fourth developing devices 15, 16, 17, 18, a transfer belt 19, a cleaning device (not shown) for removing residual toner on the photosensitive drum 12, And an in-machine temperature detection sensor TS for detecting a temperature. The laser generator 14 drives and modulates the semiconductor laser according to the level of an image signal sent from a computer (not shown) or the like. The laser light is applied to the photosensitive drum 12 at a position between the charging device 13 and the developing device via a polygon mirror (not shown), an f-θ lens, a return mirror, and the like. The electrostatic latent image formed on the photosensitive drum 12 by the irradiation of the laser beam is visualized as a yellow toner image by the first developing device 15. This yellow toner image is held on the transfer belt 19 that rotates in the direction of the arrow. The next electrostatic latent image formed on the photosensitive drum 12 is
, And is visualized as a magenta toner image. This magenta toner image is superimposed on the yellow toner image on the transfer belt 19. Similarly, the electrostatic latent image formed next on the photosensitive drum 12 is visualized as a cyan toner image by the third developing unit 17, and this cyan toner image is formed on the toner image on the transfer belt 19. , A full-color toner image is created. The fourth developing device 18
Contains black toner, and when monochrome printing is designated, the electrostatic latent image on the photosensitive drum 12 is visualized by the fourth developing device 18.

On the other hand, a sheet cassette 20 detachably attached to the printer main body has a plurality of sheets 1.
0 are stored in a stacked state. The sheet 10 is separated and fed one by one by a sheet feeding roller 21, and is conveyed toward a transfer area 23 by a timing roller 22 at a timing with a toner image. In the transfer area 23, the full-color toner image on the transfer belt 19 is transferred to the sheet 10. The sheet 10 after the transfer is separated from the transfer belt 19,
5 transported. The unfixed toner transferred onto the sheet 10 is melted and fixed in the fixing device 24, and the sheet 10 on which the toner is fixed is discharged to a sheet discharge tray 26. The fixing device 24 of this embodiment is of a belt type, and the configuration thereof will be described later.

When the transfer to the sheet 10 is completed, the residual toner is removed from the photosensitive drum 12 by the cleaning device, and the residual charge is removed by the eraser. After that, the photosensitive drum 12 is charged again by the charging device 13 and receives a latent image by the laser beam, so that the developing devices 15 to
18 is developed.

A plurality of sensors S1, S2, S3 for detecting the sheet 10 are arranged on the sheet transport path.
The control timing of each member provided in the printer is determined based on the signals obtained by detecting the leading edge and / or the trailing edge of the sheet 10 in steps S1, S2, and S3.

{Overall Structure of Fixing Device} FIG. 2 is a sectional view showing the belt-type fixing device shown in FIG. The fixing device 24 includes a driving roller 31 provided rotatably in the direction of arrow a and a halogen heater lamp 32 as a heat source.
And a fixing belt 3 running between the driving roller 31 and the heating roller 33.
4, a pressure roller 35 that presses against the drive roller 31 via the fixing belt 34, and an oil application unit 36 that applies a release agent for preventing offset to the outer peripheral surface of the fixing belt 34. At least one of the pair of rollers 31 and 33 (the heating roller 33 in the illustrated example) of the pair of rollers 31 and 33 around which the fixing belt 34 is wound is prevented from skew or meandering of the belt during running of the fixing belt 34. The fixing member 80 is attached to the fixing belt 3.
4 stabilizes the running. The fixing belt 34
Corresponds to a rotating member for fixing the toner held on the sheet 10 by heat and pressure. As the release agent, silicone oil is used.

The fixing belt 34 is a thin, preferably seamless belt, and has a belt base made of carbon steel, stainless steel, nickel, a heat-resistant resin, or the like. This is an endless belt coated with a silicone rubber having good affinity and having a heat-resistant release layer having good release properties and heat resistance to the toner. Belt substrate thickness is about 40μ
m, the thickness of the rubber coating is about 200 μm. Note that a tetrafluoroethylene resin may be used as the heat-resistant release layer of the fixing belt 34.

The drive roller 31 has a drive gear (not shown) fixed at one end thereof, and is driven to rotate in the direction of arrow a by a drive source such as a motor (not shown) connected to the drive gear. The drive roller 31 contacts the back surface of the fixing belt 34 and moves the fixing belt 34 in the direction of arrow b. To reliably move the fixing belt 34, the outer peripheral surface of the driving roller 31 is coated with a material having a large coefficient of friction (for example, silicone rubber) so that no slip occurs with the fixing belt 34. In order to secure a predetermined amount of nip width, it is more preferable that the material for coating the outer peripheral surface of the drive roller 31 is a material having relatively low hardness (for example, silicone sponge).

The heating roller 33 is a hollow metal roller, and the halogen heater lamp 32 is disposed on the center axis. As a heat source, a resistance heating element, an electromagnetic induction heating device, or the like may be used. Further, from the viewpoint of efficiently supplying heat to the fixing belt 34, the heating roller 33 is preferably formed of a material having high thermal conductivity such as aluminum or copper.

The pressure roller 35 is a roller in which the outer circumference of a metal pipe is coated with silicone rubber or Teflon (registered trademark), and the spring force of a spring 37 is applied to drive the drive roller 31 via the fixing belt 34. Is pressed against. With the rotation of the driving roller 31, the fixing belt 34
Is moved in the direction of arrow b, the pressure roller 35 is driven to rotate in the direction of arrow c by friction between the pressure roller 35 and the fixing belt 34. The relationship between the surface hardness of the drive roller 31 and the surface hardness of the pressure roller 35 is set to “surface hardness of the pressure roller 35 ≧ surface hardness of the drive roller 31”. The reason for such a relationship is as follows. In other words, in order to smoothly discharge the toner-fixed sheet 10 from the nip 38 between the pressure roller 35 and the fixing belt 34, the sheet 10 may be fed in a direction away from the periphery of the drive roller 31 or flat. This is because the pressure roller 35 may be pressed against the drive roller 31 via the fixing belt 34 in such a manner that the pressure roller 35 slightly bites into the drive roller 31.

A guide plate 39 is provided below the fixing belt 34 so as to guide the sheet 10 holding the unfixed toner to the nip 38 without touching the fixing belt 34. A discharge guide 40 is provided downstream of the nip 38.

A first temperature sensor TH1 for detecting the temperature of the heating roller 33 is disposed inside the fixing belt 34, and a second temperature sensor TH2 for detecting the temperature of the pressing roller 35 is It is arranged adjacent to 35. The first and second temperature sensors TH1 and TH2 are composed of, for example, thermistors, and contact the surfaces of the rollers 33 and 35 to detect the roller surface temperature. The first temperature sensor TH1 is held by a support 41 positioned with respect to the rotation axis of the heating roller 33, and a relative positional relationship with the heating roller 33, that is, a contact state is kept constant.

In the printer 11 of the present embodiment, the surface temperature of the pressure roller 35 having no heat source is detected by the second temperature sensor TH2, and the temperature of the halogen heater lamp 32 is determined based on the surface temperature of the pressure roller 35. The control temperature is determined and the timing of starting printing is controlled. Further, in order to adjust the temperature of the halogen heater lamp 32 to the determined control temperature, the surface temperature of the heating roller 33 is detected by the first temperature sensor TH1, and the temperature of the halogen heater lamp 3 is adjusted.
The on / off control of the power supply to 2 is performed. As a safety mechanism when the temperature of the halogen heater lamp 32 becomes abnormally high, a thermostat may be provided on the support 41 to cut off the power supply to the halogen heater lamp 32 when the temperature of the halogen heater lamp 32 becomes abnormally high.

The first temperature sensor T is attached to a portion of the outer peripheral surface of the fixing belt 34 which is in contact with the heating roller 33.
A configuration in which H1 is brought into contact is also conceivable. In such a configuration,
Since the temperature of the outer peripheral surface of the fixing belt 34 in direct contact with the toner is directly measured, accurate temperature adjustment can be performed with certainty. On the other hand, the surface of the fixing belt 34 is scraped by the contact with the first temperature sensor TH1. It will be scratched. If the outer peripheral surface of the fixing belt 34 is damaged, image noise such as oil streaks occurs, which causes a problem that the image quality is deteriorated and the durability life of the belt is shortened. Therefore, in the present embodiment, a configuration is employed in which the first temperature sensor TH1 is brought into contact with the heating roller 33. Further, with the adoption of this configuration, the outer periphery of the heating roller 33 is coated with a material having a low coefficient of friction (for example, a fluorine resin). Further, when the first temperature sensor TH1 is arranged at a position inside the fixing belt 34, there is an advantage that the first temperature sensor TH1 is not affected by an air flow formed around the fixing belt 34.

The oil application unit 36 is disposed above the fixing belt 34 and includes an oil application roller 50 that holds oil applied to the fixing belt 34 therein.
An oil transfer roller 51 that contacts the surface of the oil application roller 50 and applies the oil supplied from the oil application roller 50 to the outer peripheral surface of the fixing belt 34; Cleaning roller 52 for removing adhering paper dust and toner
And a holder 53 that rotatably supports these rollers 50, 51, 52. Oil transfer roller 51
Means that the fixing belt 34 is moved from the driving roller 31 to the heating roller 3
3 in the region moving toward the fixing belt 34.
To apply an appropriate tension to the fixing belt 34. Thereby, the traveling of the fixing belt 34 is stabilized, and the oil application from the oil transfer roller 51 to the fixing belt 34 is also stabilized.

As will be described in detail later, the oil application roller 50 includes an oil holding layer 56 provided on the surface of the cored bar 55 for holding oil, a surface layer 57 provided on the surface side of the oil holding layer 56, and the oil holding layer 56. The oil holding layer 56 and the surface layer 5 are disposed between the holding layer 56 and the surface layer 57.
Intermediate layer 58 whose oil holding capacity is set larger than that of No. 7
And a multilayer structure including: Oil transfer roller 5
A cleaning roller 5 is formed by coating a core metal with silicone rubber having a good affinity for silicone oil.
No. 2 is formed by coating felt or the like on a metal core. The surface of the oil transfer roller 51 is made rougher than the surface of the fixing belt 34 to adhere dirt from the fixing belt 34, while the cleaning roller 5
The surface of the oil transfer roller 51 has a lower releasability than the surface of the oil transfer roller 51 in order to adhere dirt from the oil transfer roller 51.

The oil application unit 36 is detachably attached to the frame 42 of the fixing device 24. When the oil held in the oil application roller 50 is used up, the used oil application unit 36 is removed from the frame. Then, a new oil application unit 36 is attached to the frame 42. Note that a cleaning pad may be brought into contact with the surface of the oil transfer roller 51 instead of the cleaning roller 52. Further, the oil application roller 50 may be brought into direct pressure contact with the fixing belt 34.

The operation of the fixing device 24 will be outlined. When the motor is driven, the drive roller 31 rotates in the direction of arrow a, and the fixing belt 34 runs in the direction of arrow b. Fixing belt 34
As the vehicle travels, the heating roller 33 is driven to rotate in the direction of arrow d, and the pressure roller 35 is driven to rotate in the direction of arrow c. After the oil is applied at a position upstream of the pressure roller 33, the traveling fixing belt 34
Is heated to a predetermined temperature by the heat from the halogen heater lamp 32 in the contact area (the heating area 43), and travels further above the guide plate 39 to the nip 38 between the pressure roller 35.

On the other hand, the sheet 10 holding the unfixed toner 44 on the side contacting the fixing belt 34 is conveyed toward the nip 38 while being guided by the guide plate 39 in the direction of arrow e. At this time, the sheet 10 and the unfixed toner 44 are fixed to the fixing belt 3 facing each other at a predetermined interval.
Heated (preheated) by the heat of No. 4. This preheating softens the unfixed toner 44 on the sheet 10 in advance.

The sheet 10 is further conveyed to the nip 3
8, the sheet 10 is sufficiently heated by the heat of the contacting fixing belt 34,
5 and the drive roller 31 are pressed against each other.
It is conveyed while being pinched by the nip portion 38. Thus, the unfixed toner 44 on the sheet 10 is sufficiently heated and melted, and is further pressurized and fixed on the sheet 10. The transfer or offset of the toner to the fixing belt 34 is controlled by oil applied to the surface of the fixing belt 34.

The sheet 10 that has passed through the nip 38 is naturally separated from the fixing belt 34, and is discharged from the sheet discharge tray 26 (FIG. 1).
). Further, heat is replenished from the halogen heater lamp 32 to the fixing belt 34 from which heat has been removed by contact with the sheet 10 under a predetermined temperature control.

In the fixing device 24, since the heating of the fixing belt 34 is performed after the oil application, the fixing belt 3 is heated.
The temperature of No. 4 is stable, and the fixing of the toner is favorably performed. Further, since the oil transfer roller 51 applies tension to the fixing belt 34, running unevenness (belt unevenness) of the fixing belt 34 is controlled, and as a result, the fixing belt 34 is smoothly combined with the action of the non-stop member 80. It runs stably and extends the life of the belt.

Further, dirt due to paper dust, toner and the like on the fixing belt 34 adheres to the cleaning roller 52 from the oil transfer roller 51 which is in contact with the fixing belt 34.
Adhesion to the oil application roller 50 is reduced. Thereby, the oil is uniformly and stably supplied from the oil application roller 50 to the oil transfer roller 51, and as a result,
Oil can be uniformly and stably applied to the fixing belt 34 from the oil transfer roller 51. Therefore, the fixing belt 34 can be cleaned while reliably preventing the offset, so that a high-quality fixed image can be obtained.

{Configuration of Oil Application Roller 50} Next, the configuration of the oil application roller 50 will be described in detail. FIG.
FIG. 4 is a perspective view showing the oil application roller 50, and FIG.

As shown in FIG.
Are disposed on the surface of the cored bar 55 for holding oil, a surface layer 57 provided on the surface side of the oil holding layer 56, and disposed between the oil holding layer 56 and the surface layer 57. The oil holding layer 56 and the surface layer 5
Intermediate layer 58 whose oil holding capacity is set larger than that of No. 7
And a multilayer structure including: As the core metal 55,
For example, an aluminum roller having an outer shape of 10 mm is used. The oil holding layer 56 is formed, for example, by winding an aromatic aramid fiber around the cored bar 55 so as to have a thickness of 4 mm. The middle layer 58 is made of, for example, 0.5 mm Japanese paper.
It is formed by being wound around the surface side of the oil holding layer 56 so as to have a thickness of. The surface layer 57 is formed, for example, by winding an aromatic aramid fiber around the surface of the intermediate layer 58 so as to have a thickness of 0.5 mm.

The oil application roller 50 is manufactured as follows. First, the end of the aromatic aramid fiber is adhered to the surface of the core metal 55 via a double-sided tape or the like, and then wound around the core metal 55 until a predetermined thickness is reached. Thus, the formation of the oil holding layer 56 is completed. Next, the end of the Japanese paper is adhered to the surface of the oil holding layer 56 via an adhesive or the like, and then wound around the oil holding layer 56 until the thickness becomes a predetermined thickness.
This completes the formation of the intermediate layer 58. Next, the end of the aromatic aramid fiber is connected to the intermediate layer 5 with an adhesive or the like.
8 and then wound around the intermediate layer 58 until the thickness becomes a predetermined thickness. Thereby, the formation of the surface layer 57 is completed. The entire oil application roller 50 is immersed in the application oil filled in the oil tank, and is left in this state for a predetermined time. The oil will form over the surface layer 5 over time.
7 penetrates into the intermediate layer 58 and the oil holding layer 56, eventually reaching an equilibrium state, and the production of the oil application roller 50 is completed.

In particular, the oil application roller 50 of the present embodiment
In this case, the “oil holding capacity” of the middle layer 58 is larger than that of the oil holding layer 56, and
The material forming each of the layers 56, 57, 58 is selected so that 8 is larger. In this specification, “oil holding capacity” is defined as the weight of oil that can be held per unit volume of a sample. Hereinafter, a method for measuring the oil holding capacity will be described.

FIGS. 5A to 5C are views for explaining a method of measuring the oil holding capacity. As shown in FIG. 5 (A), a core metal 60 having an outer diameter d = 10 mm is provided with a sample thickness of 3 mm.
The sample 61 is wound until the outer diameter becomes D = 16 mm. The axial length of the sample 61 is a known predetermined dimension. When the winding is completed, the initial weight is measured as shown in FIG. Next, as shown in FIG. 6B, the core metal 60 around which the sample 61 is wound is completely immersed in the application oil filled in the oil tank 62, and the application oil is permeated for one week. The application oil is 100 cSt of silicone oil. Thereafter, the core metal 60 around which the sample 61 is wound is placed in the oil tank 62.
Then, while holding at 150 ° C.-5 hr in a thermostat, the weight after dipping is measured as shown in FIG. Then, the weight change before and after the oil dip is divided by the volume of the sample 61 to obtain the oil holding capacity.

Table 1 shows the measurement results of the oil holding capacity of various samples 61. In this table, the heat resistant temperature, the basis weight or the basis weight of the sample 61 are also shown. The larger the oil holding capacity of the sample 61, the more oil can be held in the sample 61.

[0042]

[Table 1]

{Explanation of Each Example} Hereinafter, various examples in which the material of each layer of the oil application roll shown in FIG. 4 is changed will be described with reference to Table 2. The initial value of the oil application amount in the oil application operation in Table 2 is the average of the oil application amount per sheet from the first sheet to the 100th sheet of A4 size. The stable state at this time is the average of the amount of oil applied per sheet from the 100th sheet to the 1500th sheet of A4 size sheets.

[0044]

[Table 2]

Example 1 The oil application roller in Example 1 in Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
No. 1 aromatic aramid fiber (1), and the material NO. No. 2 in Table 1 was added to the aromatic aramid fiber (2) of No. 2 and the intermediate layer disposed between the oil retaining layer and the surface layer. 5 Japanese paper (1). In the oil application roller of the first embodiment, problems such as oil contamination do not occur in the initial stage of the oil application operation of the roller, and no problems such as offset occur in the stable state of the roller during the oil application operation. The evaluation result was good (（).

Example 2 The oil application roller in Example 2 in Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
No. 7 in Japanese paper (3), and the material No. 2
No. 3 in Table 1 was added to the aromatic aramid fiber (2) of No. 1 and the intermediate layer disposed between the oil retaining layer and the surface layer. 3 rock wool + aramid fiber. In the oil application roller according to the second embodiment, problems such as oil contamination do not occur at the initial stage of the oil application operation of the roller.
In addition, there was no problem such as offset in the stable state during the oil application operation of the roller, and the evaluation result was good (）).

Example 3 The oil application roller in Example 3 of Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
Aramid fiber (1) of No. 1 and the material No. No. 6 in Table 1 and the intermediate layer disposed between the oil retaining layer and the surface layer, 3 rock wool + aramid fiber. In the oil application roller according to the third embodiment, problems such as oil contamination do not occur at the initial stage of the oil application operation of the roller, and
No problems such as offset occurred in the stable state during the oil application operation of the roller, and the evaluation result was good (○).

Example 4 The oil application roller of Example 4 in Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
No. 7 in Japanese paper (3), and the material No. 2
No. 3 in Table 1 was added to the aromatic aramid fiber (2) of No. 1 and the intermediate layer disposed between the oil retaining layer and the surface layer. 4 and a glass fiber + aramid fiber. In the oil application roller according to the fourth embodiment, problems such as oil contamination do not occur in the initial stage of the oil application operation of the roller, and no problems such as offset occur in the stable state of the roller during the oil application operation. The evaluation result was good (（).

Example 5 The oil application roller of Example 5 in Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
Aramid fiber (1) of No. 1 and the material No. No. 6 in Table 1 and the intermediate layer disposed between the oil retaining layer and the surface layer, 4 glass fiber + aramid fiber. Example 5
In the case of the oil application roller, there is no problem such as oil contamination at the initial stage of the oil application operation of the roller, and no problem such as offset occurs in the stable state of the oil application operation of the roller. It was good (O).

Example 6 The oil application roller of Example 6 in Table 2 was used to apply the material No. in Table 1 to the oil holding layer.
No. 5 of Japanese paper (1) and the material No. 8
In the porous PTFE of No. 1 and the intermediate layer disposed between the oil retaining layer and the surface layer. 3 rock wool + aramid fiber. In the oil application roller according to the sixth embodiment, problems such as oil contamination do not occur in the initial stage of the oil application operation of the roller, and no problems such as offset occur in the stable state of the roller during the oil application operation. The evaluation result was good (（).

<< Explanation of Comparative Examples >> Next, in order to compare with the above-mentioned Examples 1 to 6, a conventional publication (JP-A-11-1337) was used.
No. 84), a comparative test was performed based on the oil application roller structure. Hereinafter, various comparative examples in which the material and the like of each layer of the oil application roll shown in FIG. 4 are changed will be described.

Comparative Example 1 The oil application roller of Comparative Example 1 in Table 2 uses the material N in Table 1 on the oil holding layer.
O. 4 and the glass fiber + aramid fiber of No. 4 and the material No. No. 2 in Table 1 was added to the aramid fiber of No. 2 and the intermediate layer disposed between the oil retaining layer and the surface layer.
2 aramid fibers. Comparative Example 1
In the case of the oil application roller, there was no problem such as oil contamination at the initial stage of the oil application operation of the roller,
Since only a very small amount of oil was applied in a stable state during the oil application operation of the roller, offset occurred, and the evaluation result was poor (x).

Comparative Example 2 The oil application roller in Comparative Example 2 in Table 2 was used in the oil holding layer to apply the material No. in Table 1 to the oil holding layer.
No. 4 in Table 1 and the glass fiber + aramid fiber of No. 4 in the surface layer. No. 2 in Table 1 was added to the aramid fiber of No. 2 and the intermediate layer disposed between the oil retaining layer and the surface layer. 3 rock wool + aramid fiber. In the oil application roller of Comparative Example 2, no trouble such as oil contamination occurred at the initial stage of the oil application operation of the roller, but only a very small amount of oil application was obtained in a stable state during the oil application operation of the roller. Since this was not achieved, an offset occurred, and the evaluation result was poor (x).

Comparative Example 3 The oil application roller of Comparative Example 3 in Table 2 has the oil holding layer in which the material No. 1 in Table 1 is used.
No. 4 in Table 1 and the glass fiber + aramid fiber of No. 4 in the surface layer. No. 6 in Table 1 and the intermediate layer disposed between the oil retaining layer and the surface layer, 2 aramid fibers (2). Comparative Example 3
In the case of the oil application roller, there was no problem such as oil contamination at the initial stage of the oil application operation of the roller,
Since only a very small amount of oil was applied in a stable state during the oil application operation of the roller, offset occurred, and the evaluation result was poor (x).

In Examples 1 to 6, the oil holding capacity of the intermediate layer provided between the oil holding layer and the surface layer is larger than the oil holding capacity of the oil holding layer, and The intermediate layer disposed between them was an oil application roller in which the oil holding capacity of the intermediate layer was larger than the oil holding capacity of the surface layer, and all the evaluation results in the examples were good.

In Comparative Examples 1 to 3, the oil holding capacity of the surface layer was smaller than the oil holding capacity of the intermediate layer disposed between the oil holding layer and the surface layer, and the oil holding capacity of the surface layer was oil. The oil application roller was smaller than the oil holding capacity of the holding layer, and all the evaluation results in the comparative example were poor.

Therefore, the oil application roller 5 of the present embodiment is
In the case of 0, the oil holding capacity of the intermediate layer 58 provided between the oil holding layer 56 and the surface layer 57 is larger than the oil holding capacity of the oil holding layer 56 and the gap between the oil holding layer 56 and the surface layer 57 is larger. The combination of the materials forming the layers 56, 57, 58 was selected such that the oil holding capacity of the intermediate layer 58 provided in the first layer was larger than the oil holding capacity of the surface layer 57. Further, the thickness of the oil holding layer 56 was selected to be larger than the thickness of the intermediate layer 58, and the thickness of the oil holding layer 56 was set to be larger than the thickness of the surface layer 57 so as to increase the amount of oil.

In the oil application roller 50 having such a configuration,
During the oil application operation, first, oil transfer from the surface layer 57 to the oil transfer roller 51 occurs. Next, in order to maintain the oil holding amount of the surface layer 57 and the oil holding amount of the intermediate layer 58 by reducing the oil amount of the surface layer 57, the oil transfer from the intermediate layer 58 to the surface layer 57 occurs. Similarly, as the amount of oil in the intermediate layer 58 decreases, the amount of oil retained in the intermediate layer 58 and the amount of oil retained in the oil retaining layer 56 are maintained, so that oil transfer from the oil retaining layer 56 to the intermediate layer 58 occurs. As a result, the amount of oil applied in the initial stage of the oil application operation of the roller can be suppressed to a level at which troubles such as oil contamination do not occur, and the amount of oil applied in a stable state during the oil application operation of the roller is offset. It was possible to maintain the level at which no problems occurred, and it was possible to reliably prevent the occurrence of image noise over the entire period of the oil application operation.

According to the first to sixth embodiments, no problem such as oil contamination occurs at the initial stage of the oil application operation of the roller, and no problem such as offset occurs in the stable state of the roller during the oil application operation. It was found that the amount of application was 0.5 to 2 mg per A4 size sheet.

It is needless to say that the present invention is not limited to the configuration of the above-described embodiment, but can be variously modified without departing from the gist of the present invention. For example, in the above-described embodiment, the release agent application roller has been described as having a three-layer structure including a release agent holding layer, an intermediate layer, and a surface layer, but is not limited to such a configuration. Needless to say, a multilayer structure of four or more layers including at least these three layers may be employed.

In the above-described embodiment, the release agent holding layer 56 is described to have a layer thickness of 4 mm.
The present invention is not limited to such numerical values,
Needless to say, it is applied in the range of 20 mm.

Similarly, in the above-described embodiment, the thickness of the surface layer 57 has been described to be 0.5 mm. However, the present invention is not limited to such a numerical value.
It goes without saying that it is applied in the range of 5 to 2.0 mm.

Similarly, in the above-described embodiment, the thickness of the intermediate layer 58 has been described to be 0.5 mm.
The present invention is not limited to such numerical values.
Needless to say, it is applied in the range of 1 to 2.0 mm.

[Effects of the Invention] As described above, according to the present invention, the amount of the release agent applied at the initial stage of oil application can be suppressed to a level that does not cause problems such as oil stains, and the oil application can be suppressed. A release agent application roller capable of increasing the release agent application amount in a stable operation state to a level at which a problem such as offset does not occur is provided,
It is possible to provide a fixing device that prevents generation of image noise.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an electrophotographic full-color printer incorporating a fixing device according to the present invention.

FIG. 2 is a sectional view showing the belt-type fixing device shown in FIG.

FIG. 3 is a perspective view showing an oil application roller.

FIG. 4 is a sectional view showing the oil application roller.

FIGS. 5A to 5C are diagrams for explaining a method of measuring an oil holding capacity.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 sheet 31 drive roller 33 heating roller 34 fixing belt (rotating member) 35 pressure roller 36 oil applying unit 44 unfixed toner 50 oil applying roller (release agent applying roller) 51 oil transfer Roller 52 Cleaning roller 53 Holder 55 Core metal 56 Oil holding layer (release agent holding layer) 57 Surface layer 58 Middle layer

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H033 AA09 AA39 BA43 BA46 CA26 3J103 AA02 AA15 AA33 AA51 EA07 EA09 EA20 FA05 FA07 FA18 FA22 GA02 GA52 GA57 GA58 HA03 HA04 HA05 HA15 HA19 HA37 HA41 HA60 4F040 AA05 CB02 CB02

Claims (4)

[Claims] A rotating member for fixing the toner image held on the sheet by heat and pressure, and a release agent applying roller holding therein a releasing agent for preventing offset applied to the rotating member. In the fixing device provided, the release agent application roller includes a release agent holding layer provided on a surface of a cored bar and holding a release agent; and a surface layer provided on a surface side of the release agent holding layer. A fixing device provided between the release agent holding layer and the surface layer, and an intermediate layer having a release agent holding ability set to be larger than the release agent holding layer and the surface layer. 2. The fixing device according to claim 1, wherein the intermediate layer is disposed so as to directly contact an inner peripheral surface of the surface layer. 3. The fixing device according to claim 1, wherein the intermediate layer is disposed in a state of directly contacting an outer peripheral surface of the release agent holding layer. 4. The amount of the release agent applied to the rotating member by the release agent application roller is set within a range of 0.5 to 2.0 mg per A4 size sheet. Claims 1 to 3
The fixing device according to claim 1.