JP2002023541A - Relase agent coating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce leakage while holding a large amount of a release agent by improving the contradicting relation between the release agent holding amount and release agent holding force of a release agent coating roller using a ceramic porous body and then embodies the small size, long life, and high reliability of a release agent coating roller. SOLUTION: The distribution density of pores 55 of the ceramic porous body of a release agent holding layer 35 is equal for the outer and inner peripheral sides on the average, but the mean diameter (d) is different. Consequently, the release agent holding amount increases on the inner peripheral side where there is no adverse effect on the leakage and decreases toward the outer peripheral side so that the leakage is prevented on the outer peripheral side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release agent applying roller for a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a printing machine. The present invention relates to a technical field of a release agent application roller of a type in which a release agent is impregnated inside using a porous body.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile apparatus, and a printing machine using a toner, a fixing device is used for fixing, that is, fixing the transferred toner to recording paper. . For example, one type of fixing device has a fixing (heating) roller and a pressure roller, and when the recording paper on which the toner is transferred passes between these rollers, the toner receives the heat and pressure to generate toner. Fixed to recording paper.

At this time, a part of the toner which should be fixed on the recording paper may be transferred to a fixing (heating) roller which is in direct contact with the recording paper. A release agent is applied to prevent such a transfer phenomenon (toner offset phenomenon) from occurring.

In order to apply a release agent to a fixing (heating) roller, on the other hand, a part of a rotating application roller is immersed and adhered to a release agent contained in a container, and on the other hand, a released mold release agent is applied. Release agent application roller of the type that applies the agent to the fixing (heating) roller, or the type in which the release agent application roller itself is impregnated with the release agent in advance and the release agent that exudes from the surface is applied Is often used.

[0005] In the latter type, not only is it possible to impregnate as much release agent as possible, but also not only does the impregnated release agent not leak out when not in use, but also it can be applied without excess or shortage when in use. Required. For the impregnated layer of the release agent, besides the one using a fiber material, for example, JP-A-8-87
A device using a ceramic porous body as disclosed in No. 193 has been developed.

In a release agent applying roller using a ceramic porous body, since the release agent is held in the pores of the ceramic porous body, the amount of the release agent that can be held in the same volume is determined by the porosity or the pore diameter. The life of the release agent applying roller can be extended as the porosity or the pore diameter is increased. However, when the porosity or the pore diameter is increased, the holding force of the release agent is reduced, and there is a problem that leakage of the release agent, that is, oil leakage easily occurs.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a release agent applying roller using a porous ceramic material, which is generally used for a release agent applying roller. It is an object of the present invention to reduce the leakage while maintaining a large amount of the release agent, and at the same time, to make the release agent application roller smaller, have a longer life, and have a higher reliability. The task is to contribute.

[0008]

The above object is achieved by the following means. That is, the release agent application roller of the first invention is a release agent application roller using a porous ceramic body for the release agent holding layer, and the ceramic is applied from the outer periphery of the release agent application roller toward the center thereof. This is one in which the release agent holding amount per unit volume of the porous body is increased.

The release agent applying roller according to a second aspect of the present invention is the roller according to the first aspect, wherein the increase in the amount of the release agent held increases with respect to the volume of the ceramic porous body. This is achieved by changing the ratio of the volume of pores contained in.

Further, in the release agent applying roller of the third invention, in the release agent application roller of the first invention, the increase of the release agent holding amount is caused by a decrease in pores of the ceramic porous body. This was done by changing the (average) diameter.

[0011]

FIG. 1 is an explanatory view schematically showing an image forming apparatus in which a release agent applying apparatus of the present invention is used.

The photoreceptor drum 1 has a photoreceptor layer on its surface and is supported so as to be rotatable around its axis (in the direction of the arrow). The photoconductor layer is made of a photoconductive material,
It is a material that becomes conductive when light is applied to this layer.
The charging device 2 is a device for charging the photoconductor layer of the photoconductor drum 1. The photoconductor layer charged by the charging device 2 moves to the front of the exposure device 3 as the photoconductor drum 1 rotates. .

When the exposure device 3 irradiates the surface of the moved photoreceptor layer with light corresponding to an image to be formed,
Since the photoreceptor layer is conductive, the electric charge moves to a conductive material such as a metal under the photoreceptor layer, and the photoreceptor layer loses the electric charge. Thus, an invisible image (latent image) is formed on the photoreceptor layer by the charged portion and the portion having lost the charge.

The photosensitive layer on which the latent image is formed further moves in the direction of the arrow, and is developed into a visible image by the developing device 4.
In this development, the toner is adsorbed by electrostatic force according to the above-described charging situation.

When the photosensitive drum 1 further rotates, the developed photosensitive layer reaches the transfer device 5, where the toner image is transferred onto the recording paper S supplied in synchronization with the photosensitive drum 1. Transfer at this time is also performed by electrostatic force.

The recording paper S to which the toner has been transferred is conveyed to a fixing device 28. The toner, which is simply electrostatically attracted, is firmly fixed (fixed) on the recording paper S by applying heat and pressure in the fixing device 28. The recording paper S on which the toner has been fixed in the fixing device 28 is separated from the photosensitive drum 1 and transported to the paper discharge tray 29.

On the other hand, the photosensitive layer from which the recording paper S has been peeled off is
It passes in front of the cleaning device 6, where the remaining toner is removed.

The above is a brief description of the image forming apparatus.
In order to describe the release agent applying roller of the present invention, a more detailed description of the entire image forming apparatus is not required, and thus no further description will be given.

FIG. 2 is an explanatory diagram for explaining the outline of the fixing device 28. As shown in FIG.

The fixing device 28 has a fixing roller 33, a pressure roller 35, and a release agent applying roller 51. The fixing roller 33 includes a heating device such as a halogen heater lamp 32 inside the cavity, and is rotationally driven in a direction of an arrow a by a driving device (not shown). The pressure roller 35 is rotatable, and is urged toward the fixing roller 33 by an urging means such as a spring 37.

The release agent application roller 51 applies a release agent such as silicone oil to the surface of the fixing roller 33.
It is rotatably supported and lightly pressed.

The recording sheet S to which the toner 49 has been transferred in the transfer device 5 is guided by a guide plate 39 between the fixing roller 33 and the pressure roller 35 in the fixing device 28, that is, to the nip 38. Fixing roller 33 at nip 38
The toner 49 is melted by the heat from the halogen heater lamp 32 and the pressure generated by the urging force of the spring 37.
It is pressed and fixed on the recording paper S. At this time, since the release agent applied by the release agent application roller 51 exists on the surface of the fixing roller 33 in the form of a thin film, the molten toner 49 is prevented from adhering to the fixing roller 33. ing.

The recording paper S on which the toner 49 has been fixed is guided (guided) by a paper ejection guide 40 and conveyed to a paper ejection tray 29.

FIG. 3 is an embodiment of a cross-sectional view of a release agent applying roller 51 using a porous ceramic body according to the present invention. The release agent application roller 51 of the present invention is provided with a release agent holding layer 53 and a release agent application layer 54 which is much thinner than the release agent holding layer 53 around a roller shaft 52 driven or driven and rotated. I have.

The release agent holding layers 53 are continuous (communicated) with each other.
The release agent is made of a porous ceramic body having innumerable pores, and the release agent is held by these pores. Also,
The release agent coating layer 54 is a layer having fine gaps made of fibrous material such as felt or other material.
The release agent that exudes from the surface by capillary action is guided to the surface. The release agent guided to the surface of the release agent application layer 54 is applied to the release agent application roller 51 by, for example, the fixing roller 3.
3 and is applied to the surface of the fixing roller 33 by rotating. Although not shown, the cylindrical end surface of the release agent holding layer 53 is sealed so that the release agent does not leak therefrom.

FIG. 4 is a graph qualitatively showing the characteristics of the release agent holding layer 53, that is, the release agent holding amount and the release agent holding force of the ceramic porous body. The release agent holding amount indicates the amount of the release agent that can be contained in a unit volume of the ceramic porous body, and the release agent holding force holds the release agent on the inner surface of the pores and externally holds the release agent. This indicates the degree of difficulty in flowing out.

The horizontal axis shows the pore ratio and the pore diameter.
The pore ratio is a ratio of the volume of all pores contained in the porous ceramic body to the unit volume of the porous ceramic body. The pore diameter is the average direct (half) diameter of all pores contained in a unit volume of the ceramic porous body.

This graph shows that the larger the pore ratio and the pore diameter of the porous ceramic material, the higher the releasing agent holding power and the more difficult it is for the releasing agent to flow to the outside, but the smaller the releasing agent holding amount. ing. That is, if the pore ratio or the pore diameter is increased in order to increase the amount of the release agent held by the release agent application roller 51, the release agent holding force is reduced and leakage is likely to occur. In the present invention, such a distribution of the release agent holding amount per unit volume in the radial direction of the release agent holding layer 53 is provided so that the release agent application roller 51 using a ceramic porous body has such a distribution. The object of the present invention is to improve the relationship between the opposing release agent holding amount and release agent holding force.

[First Embodiment] The first embodiment is a mold release agent in which the ratio of the volume of all the pores contained in the porous ceramic body constituting the release agent holding layer 53 to the volume thereof is changed. This is an example of the application roller 51.

FIG. 5 is a sectional view of a main part of the release agent holding layer 53 in the first embodiment. The direct (half) diameter of the pores 55 of the ceramic porous body is equal on average both on the outer peripheral side and on the inner peripheral side, but the distribution density is changed. That is, the pores 55 contained in the ceramic porous body with respect to the volume from the inner peripheral side toward the center.
The volume ratio has increased.

As a result, the amount of release agent retained on the inner peripheral side, which does not affect the leakage of the release agent retaining layer 53, increases, while the amount decreases on the outer peripheral side, so that leakage is prevented on the outer peripheral side. When viewed from the whole of the release agent application roller, it is possible to obtain a release agent application roller that has less leakage despite being able to hold a larger amount of release agent than conventional ones.

[Second Embodiment] The second embodiment is an example of the release agent applying roller 51 in which the average diameter of the pores 55 of the ceramic porous body constituting the release agent holding layer 53 is changed.

FIG. 6 is a sectional view of a main part of the release agent holding layer 53 in the second embodiment. The average density of the distribution density of the pores 55 of the porous ceramic body is equal both on the outer circumference side and on the inner circumference side, but the average diameter d is changed. That is, the average diameter d of the pores 55 increases from the inner peripheral side toward the center.

As a result, similarly to the first embodiment, the amount of release agent retained on the inner peripheral side, which does not affect the leakage of the release agent retaining layer 53, increases, while the amount decreases on the outer peripheral side. The leakage is prevented in When viewed from the whole of the release agent application roller, it is possible to obtain a release agent application roller that has less leakage despite being able to hold a larger amount of release agent than conventional ones.

The pores 55 shown in FIGS. 5 and 6 in each embodiment are connected to each other and are not independent bubbles. The shape is indicated by a circle, but this merely indicates the size and density of the pores. In the above description, the case where the release agent applying roller 51 applies the release agent to a roller such as the fixing roller 33 has been described as an example. However, the present invention is not limited thereto. Obviously, can also be used in a belt fixing release agent application mechanism.

[0036]

According to the present invention, in a release agent applying roller using a porous ceramic material, generally, the relationship between the opposing release agent holding amount and the release agent holding force is improved, and a large number of release agents are provided. This has the effect that leakage can be reduced while retaining the agent, and furthermore, it is possible to contribute to the downsizing, long life, and high reliability of the release agent application roller. Things.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an image forming apparatus in which a fixing device is used.

FIG. 2 is an explanatory diagram for explaining an outline of a fixing device 28.

FIG. 3 is a cross-sectional view of a release agent applying roller 51 using a ceramic porous body according to the present invention.

FIG. 4 is a graph qualitatively showing characteristics of a release agent holding amount and a release agent holding force of a ceramic porous body.

FIG. 5 is a sectional view of a main part of a release agent holding layer 53 in the first embodiment.

FIG. 6 is a sectional view of a main part of a release agent holding layer 53 in a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 charging device 3 exposure device 4 developing device 5 transfer device 6 cleaning device 28 fixing device 29 paper discharge tray 32 halogen heater lamp 33 fixing roller 35 pressure roller 37 spring 38 nip portion 39 guide plate 40 paper discharge guide 49 Toner 51 Release agent application roller 52 Roller shaft 53 Release agent holding layer 54 Release agent application layer 55 Pores d Average diameter S Recording paper

Claims (3)

[Claims] 1. A release agent applying roller using a ceramic porous body for a release agent holding layer, the release agent holding per unit volume of the ceramic porous body from the outer periphery of the release agent applying roller toward the center thereof. A release agent application roller characterized in that the amount is increased. 2. The release agent applying roller according to claim 1, wherein the increase in the release agent holding amount changes the ratio of the volume of the pores contained therein to the volume of the ceramic porous body. A release agent application roller, characterized in that the release agent application roller is made by performing the following. 3. The release agent applying roller according to claim 1, wherein the increase in the release agent holding amount is performed by changing an average diameter of pores of the ceramic porous body. A release agent applying roller characterized by the above-mentioned.