JP2011095306A5 - - Google Patents

Description

As a fixing device mounted on an electrophotographic copying machine, a printer, or the like, an external heating type fixing device is known. This external heating type fixing device includes a heating body such as a heater, a fixing roller heated by the heating body, and a pressure roller that forms a nip portion together with the fixing roller. The recording material carrying the unfixed toner image is heated while being nipped and conveyed by the nip portion with the toner image carrying surface facing the fixing roller, whereby the toner image on the recording material is heated and fixed on the recording material. As an external heating type fixing device, a contact type in which a heating body is brought into contact with the outer peripheral surface (surface) of the fixing roller, a non-contact type in which the surface of the fixing roller is heated without bringing the heating body into contact with the surface of the fixing roller, and It is divided roughly into. Since the contact-type external heating type fixing device transmits heat by bringing a heating source such as a ceramic heater into contact with the surface of the fixing roller, the heat propagation efficiency is higher than that of a non-contact type external heating type fixing device. The contact-type external heating type fixing device includes a sliding contact type fixing device that slides a heating body on the surface of the fixing roller, and a cylindrical rotating member that rotates while contacting the heating body (hereinafter, heating heating body). And a rotary contact type fixing device that transfers the heat of the heating body to the fixing roller. In the rotary contact type fixing device, the heating rotating member also rotates with the rotation of the fixing roller. Therefore, the surface of the fixing roller is less likely to be damaged than the sliding contact type fixing device, and the frictional force is small, so that the driving torque can be suppressed. There is an advantage that you can. Patent Document 1 discloses a fixing device of this type.

In the above rotating contact type fixing device, since the surface of the fixing roller comes into contact with the toner image on the recording material such as paper, a small amount of foreign matter such as paper dust or toner adheres to the surface of the fixing roller. it is desired to make the foreign matter adheres not transferred to the heating rotating body. An object of the present invention is to provide a fixing apparatus capable of reducing the transition to the heating rotating body foreign substances adhering to the fixing roller surface.

The present invention can provide a fixing apparatus capable of reducing the transfer of the heating rotating body surface of the foreign matter adhering to the fixing roller surface.

Configuration of the fixing device according to the present invention for achieving the above object, a heating rotator having no rubber layer, have a rubber layer to form a heating contact portion in contact with the pre-Symbol heating rotary member a fixing roller, the contact with the fixing roller and provided with a backup member for forming a two-up section, said two Tsu recording material heated preparative toner image while feeding transportable recording material carrying the toner image-flop unit the fixing device for constant wear, microhardness of the surface of the fixing roller and less than 50 degrees.

Configuration of Fixing Device: In the following description, with respect to the fixing device and members constituting the fixing device, the longitudinal direction is a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The short side direction is a direction parallel to the recording material conveyance direction on the surface of the recording material. The length is a dimension in the longitudinal direction. The width is a dimension in the short direction. FIG. 1A is a schematic cross-sectional view illustrating the configuration of the fixing device according to the first embodiment. FIG. 1B is an enlarged cross-sectional view of the heating nip portion and its vicinity of the fixing device shown in FIG. This fixing device is an external heating type fixing device, and in particular, is a rotary contact type fixing device in which a heating film rotating while being in contact with a heater is brought into contact with the surface of the fixing roller. This rotary contact type fixing device has an advantage that the time required to start energization of the heater and to raise the temperature to a fixing possible temperature (fixing temperature) is short (start-up time is shortened). Further, since only the outer peripheral surface of the fixing roller is heated, there is an advantage that power consumption is low (low power consumption). The fixing device 100 shown in the first embodiment includes a fixing roller 110, a pressure roller 111 as a backup member, a heating film 120 as a heating rotating body that does not have a rubber layer, a heater 115 as a heating body, and the like. have. In the fixing roller 110, the outer peripheral surface (front surface) of the fixing roller 110 is in contact with the outer peripheral surface (front surface) of the pressure roller 111, and forms a fixing nip portion (nip portion) N1 together with the pressure roller 111. The fixing roller 110 forms a heating nip portion (heating pressure contact portion) N2 by sandwiching the heating film 120 between the surface of the fixing roller 110 and the heater 115 on the opposite side of the pressure roller 111. Below, the structure of each member is demonstrated in detail.

Structure of heating film: The heating film 120 needs heat resistance in order to receive the heat of the heater 113, and also needs strength because it moves in contact with the heater 113. The heating film 120 is a cylindrical thin film having flexibility and heat resistance, and a release layer 127 is formed on the outer peripheral surface of an endless film base layer (hereinafter referred to as a base layer) 126. is there. As a material for the base layer 126, a metal such as SUS (Stainless Used Steel) or a heat resistant resin such as polyimide may be used. Since metal is stronger than resin, it can be thinned and has high thermal conductivity, so that heat from the heater 113 is easily transmitted to the fixing roller 110. Since resin has a lower specific gravity than metal, there is an advantage that the heat capacity is small and the resin is easily heated. In addition, the resin can be molded at low cost because a thin film can be formed by coating. In Example 1, as the material of the base layer 126, a material obtained by adding a carbon-based heat conductive filler to polyimide resin to improve the heat conductivity was used. The thinner the base layer 126 is, the easier it is to transfer the heat of the heater 113 to the surface of the fixing roller 110. However, since the strength of the base layer 126 is reduced, the thickness is preferably about 20 μm to 100 μm. In Example 1, the thickness of the base layer 126 was 60 μm. A PFA release layer 127 is provided on the outer peripheral surface of the base layer 126 in order to reduce contamination on the outer peripheral surface of the base layer 126. As a material for the release layer 127, as in the release layer 123 of the pressure roller 111, a fluororesin such as PTFE or FEP may be used in addition to PFA. The thickness of the release layer 127 of the heating film 120 is preferably about 1 μm to 20 μm because the heat from the heater 113 is more easily transmitted to the surface of the fixing roller 110 as the thickness becomes thinner. In Example 1, the thickness of the release layer 127 was 10 μm.

Configuration of Fixing Roller: The fixing roller 110 has an elongated iron cored bar 117, and is the same as the elastic rubber layer 122 of the pressure roller 111 on the outer peripheral surface of the cored bar 117 other than the support shafts at both ends in the longitudinal direction. An elastic rubber layer (rubber layer) 116 of foamed rubber is formed. When the heat capacity of the elastic rubber layer 116 is large and the heat conductivity is high, the fixing roller 110 absorbs the heat received by the surface of the fixing roller from the heater 113 through the heating film 120 in the heating nip portion N2. It is easy to increase the surface temperature of the fixing roller. That is, the elastic rubber layer 116 can shorten the rise time of the surface temperature of the fixing roller 110 when the heat capacity is as low as possible, the thermal conductivity is low, and the heat insulation effect is high. The elastic rubber layer 116 is the same as the elastic rubber layer 122 of the pressure roller 111, has a low heat capacity (specific gravity: about 0.75 to 0.85), and has a low thermal conductivity (thermal conductivity: 0. 0. 11 to 0.16 W / m · K) A single-layer elastic rubber layer. Therefore, the rise time of the surface temperature of the fixing roller 110 can be shortened by using the elastic rubber layer 116. If the outer diameter of the fixing roller 110 is smaller, the heat capacity can be suppressed. However, if the outer diameter is too small, the widths of the heating nip portion N2 and the fixing nip portion N1 are narrowed, and thus an appropriate diameter is required. In the first embodiment, the outer diameter of the fixing roller 110 is 20 mm. Regarding the thickness of the elastic rubber layer 116, if it is too thin, heat is released to the metal core 117, so that an appropriate thickness is required. In Example 1, the thickness of the elastic rubber layer 116 was 4 mm. A PFA release layer 118 made of a fluorine-based material is formed on the outer side (outer peripheral surface) of the elastic rubber layer 116.

[Example 5] While in the fixing device shown in Embodiments 1 to 3 has been described an example using a heating film 120 as a heating rotary member, a rotatable heating roller of the heating rotating body cylindrical not limited thereto There may be. FIG. 4B is a schematic cross-sectional view illustrating the configuration of the fixing device according to the fifth embodiment. The heating roller 140 has a rigid roller body 141 and a release layer 142. The roller body 141 is formed in a cylindrical shape from a predetermined metal material or resin material having heat resistance and thermal conductivity. A PFA release layer 142 is provided on the outer peripheral surface excluding the support shafts at both ends in the longitudinal direction of the roller main body 141 in order to reduce contamination on the outer peripheral surface of the roller main body 141. The heating roller 140 has support shafts at both ends in the longitudinal direction of the roller body 141 rotatably supported by an apparatus frame (not shown) via a bearing (not shown), and the bearing is supported by a pressure spring 114 in the downward direction A1. Is being pressurized. As a result, the outer peripheral surface (surface) of the heating roller 140 is brought into contact with the surface of the fixing roller 110 in a pressurized state, and the elastic rubber layer 116 of the fixing roller 110 is elastically deformed. A heating nip portion N2 having a predetermined width is formed on the surface. The heating roller 140 rotates in the direction of the arrow following the rotation of the fixing roller 110 and is heated by a halogen lamp 143 serving as a heating body provided in the roller body 141. Also in the fixing device 100 according to the fifth exemplary embodiment, if the micro hardness of the surface of the fixing roller 110 is set to less than 50 degrees, the contamination on the surface of the heating roller 140 can be reduced.

Claims (6)

A heating rotator having no rubber layer, have a rubber layer, and the fixing roller to form a heating contact portion in contact with the pre-Symbol heating rotary member, to form a contact with the fixing roller nips unit A backup member;
In the provided fixing device for Fixing the recording material heated preparative toner image while feeding transportable recording material carrying the toner image by the two-up unit,
The fixing device is characterized in that the micro hardness of the surface of the fixing roller is less than 50 degrees . The fixing device according to claim 1, wherein the fixing roller includes a plurality of the rubber layers, and the outermost rubber layer has a JIS-A hardness of less than 70 degrees . The fixing device according to claim 1, wherein the fixing roller has a release layer formed of a fluororesin as a surface layer, and the thickness of the release layer is 30 μm or less . The fixing device according to claim 3 , wherein the release layer is formed by spray coating . 2. The heating rotator is a cylindrical film having a base layer made of metal or resin and a release layer formed outside the base layer and made of a fluororesin. The fixing device according to claim 4 . The fixing device according to claim 5, further comprising a heater in contact with an inner surface of the film, wherein the heater forms the heating pressure contact portion together with the fixing roller via the film .