JP3685082B2 - Fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device in an electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as this type of fixing device, a fixing device that includes a peeling member that peels a recording material discharged from a nip portion from a rotating body is known. In this fixing device, the peeling member is disposed close to the rotating body at a position downstream of the nip portion in the rotation direction of the rotating body. Then, when the peeling member comes into contact with the recording material discharged from the nip portion, the recording material is peeled from the rotating body.
[0003]
[Problems to be solved by the invention]
However, in the case of the conventional fixing device, since there is no means for quickly heating the peeling member, the peeling member may not be sufficiently warmed immediately after warm-up. When the fixing device is operated in this state, the toner is rapidly cooled and solidified before the toner is smoothed by its own viscoelastic force because the peeling member touches the toner image immediately after fixing on the recording material at the time of peeling. As a result, the image may be inferior in gloss.
[0004]
The present invention has been made paying attention to the problems existing in the prior art as described above. The object is to provide a fixing device that can quickly warm the peeling member.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes a first rotating body having a heating source and a second rotating body that forms a nip portion between the first rotating body and the first rotating body. A fixing device for fixing the unfixed toner image on the recording material by sandwiching and conveying the recording material at the nip portion,
A thin plate-shaped peeling member that contacts the recording material discharged from the nip portion and separates the recording material from the first rotating body is provided , and is opposite to the side edge of the peeling member that contacts the recording material. the side edges of the side, formed so as to extend in the separated state with respect to the first rotary member to accumulate heat radiated to vertically above the first rotary member from the first rotary member The summary is as follows.
[0006]
According to a second aspect of the present invention, in the fixing device according to the first aspect, the heat capacity of the peeling member is smaller than the heat capacity of the first rotating body.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect, a part of the peeling member is opposed to a non-sheet passing region in the first rotating body. To do.
[0007]
According to a fourth aspect of the present invention, in the fixing device according to the third aspect, a part of the heating source is arranged in a non-sheet passing region in the first rotating body.
According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, when the first rotating body is not rotated, the heating source is the first rotating body. The gist is to be located closer to the peeling member than the central axis.
According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the peeling member is moved from the side edge on the first rotating body side to the first rotating body. The gist of the present invention is to further have a folded portion extending along the line.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a fixing device in an electrophotographic image forming apparatus will be described with reference to the drawings.
[0009]
An electrophotographic image forming apparatus includes, as units for executing an electrophotographic process, an exposure apparatus that forms a latent image based on an original image on a photoconductor, a developing apparatus that forms a toner image from the latent image, and the above A transfer device for transferring the toner image onto a sheet (recording material) is provided. The fixing device is disposed downstream of these devices, and performs a fixing process for fixing the unfixed toner image transferred onto the paper by the transfer device on the paper, and also serves as a paper transport function.
[0010]
1 and 2 are schematic configuration diagrams illustrating a fixing device according to the present exemplary embodiment. As shown in these drawings, the fixing device includes a fixing roller 11 as a first rotating body and a pressure roller 12 as a second rotating body. The fixing roller 11 and the pressure roller 12 are arranged substantially in parallel, and are in contact with each other with a predetermined pressing force by an urging means (not shown). A nip portion 13 is formed between the fixing roller 11 and the pressure roller 12 by the contact surfaces of the rollers 11 and 12.
[0011]
The fixing roller 11 is rotationally driven in the direction of arrow A shown in FIG. 1 by a driving unit (not shown), and the pressure roller 12 is rotated by being driven by the fixing roller 11. For this reason, the paper P conveyed from the transfer device (not shown) to the fixing device and fed between the fixing roller 11 and the pressure roller 12 is nipped by the nip portion 13 and conveyed in the direction of arrow B shown in FIG.
[0012]
As shown in FIG. 1, the fixing roller 11 incorporates a halogen lamp 11a as a heating source, and the fixing roller 11 is heated to a predetermined temperature by the halogen lamp 11a. The halogen lamp 11 a is disposed at a position slightly deviated from the central axis of the fixing roller 11, and is positioned close to the peeling member 14 when the fixing roller 11 is not rotated. As shown in FIG. 3, the halogen lamp 11 a extends not only to the sheet passing area in the fixing roller 11 but also to the outside, that is, the non-sheet passing area.
[0013]
Next, the peeling member 14 for peeling the paper P discharged from the nip portion 13 from the fixing roller 11 will be described. As shown in FIGS. 1 and 2, the peeling member 14 is disposed close to the fixing roller 11 at a position downstream of the nip portion 13 in the rotation direction of the fixing roller 11, and is supported and fixed by a support member (not shown). The peeling member 14 has a thin plate shape and has a smaller heat capacity than the fixing roller 11. Further, the peeling member 14 is a so-called contact type in which one side edge (lower end edge) contacts the surface of the fixing roller 11. The other side edge (upper edge) of the peeling member 14 extends vertically above the fixing roller 11, so that a part of the peeling member 14 is positioned vertically above the fixing roller 11.
[0014]
Further, the peeling member 14 is arranged along the axial direction of the fixing roller 11 and extends not only to the sheet passing area in the fixing roller 11 but also to the outside thereof, that is, the portion corresponding to the non-sheet passing area as shown in FIG. I'm out. Accordingly, both ends of the peeling member 14 in the width direction (the axial direction of the fixing roller 11) are always opposed to the non-sheet passing region in the fixing roller 11.
[0015]
The peeling member 14 is formed of a material having high thermal conductivity, that is, a material having a small heat capacity. More specifically, the peeling member 14 is formed of a material having higher thermal conductivity than silicone rubber and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) constituting the surface layer of the fixing roller 11. Specific examples of the material having high thermal conductivity include copper, aluminum, nickel, iron, and stainless steel.
[0016]
Next, the operation of the fixing device configured as described above will be described.
The paper P conveyed from the transfer device (not shown) to the fixing device is fed between the fixing roller 11 and the pressure roller 12 and is sandwiched between the nip portion 13, and pressure and heat are applied to the paper P at the nip portion 13. As a result, the unfixed toner image on the paper P is fixed and fixed.
[0017]
After the fixing process at the nip portion 13, when the paper P adheres to the fixing roller 11 by the melted toner and is discharged from the nip portion 13 so as to be wound around the roller 11, The sheet P is peeled from the fixing roller 11 by contacting the end of the peeling member 14 on the fixing roller 11 side.
[0018]
During the warm-up, the fixing roller 11 stops at a position where the halogen lamp 11a is closer to the peeling member 14 than the central axis of the fixing roller 11, and the halogen lamp 11a is energized in this state.
[0019]
The temperature of the peeling member 14 during the fixing operation is preferably higher than the melting point of the toner on the paper P. In particular, when the toner is an oilless toner, it is higher than the melting point of the wax component used in the toner. High temperatures are preferred. Since the oilless toner contains many wax components having a lower melting point and higher crystallinity than the binder resin, if the temperature of the peeling member 14 is set higher than the melting point of the wax component, the wax component can be selectively used at the time of peeling. Crystallization can be prevented, and an image with high color development and excellent light transmittance can be obtained. Further, when a “special OHP sheet” having an image receiving layer made of a thermoplastic resin such as polyester is used as a recording material, a temperature higher than the melting point of the thermoplastic resin constituting the image receiving layer is preferable. Since the image receiving layer of the “special OHP sheet” uses a resin having a melting point lower than that of the binder resin of the toner, if the temperature of the peeling member 14 is set higher than the melting point of the resin constituting the image receiving layer, The solidification of the image receiving layer can be prevented.
[0020]
The effects obtained by this embodiment will be described below.
Since a part of the peeling member 14 is disposed vertically above the fixing roller 11, the radiant heat from the fixing roller 11 is efficiently absorbed by the peeling member 14. For this reason, the peeling member 14 can be warmed quickly, and a good gloss image can be obtained even immediately after warm-up.
[0021]
According to the present embodiment, since the peeling member 14 is a thin plate and has a small heat capacity, the peeling member 14 can be warmed more quickly by the radiant heat from the fixing roller 11.
[0022]
Normally, the fixing roller 11 is deprived of heat in the sheet passing area by the sheet P passing through the nip portion 13, and therefore the temperature of the sheet passing area tends to decrease particularly during continuous printing. The temperature may also drop. However, according to the present embodiment, both ends of the peeling member 14 in the width direction (the axial direction of the fixing roller 11) are opposed to the non-sheet passing region of the fixing roller 11, and the temperature can be lowered during continuous printing. The peeling member 14 can efficiently absorb the radiant heat from the non-sheet passing region. For this reason, it can suppress that the temperature of the peeling member 14 falls in the case of continuous printing. In addition, since the halogen lamp 11a extends to the non-sheet passing region, the effect can be further improved.
[0023]
The halogen lamp 11a is disposed at a position slightly deviated from the central axis of the fixing roller 11, and is positioned close to the peeling member 14 when the fixing roller 11 is not rotated. For this reason, the peeling member 14 can be heated more quickly when the fixing roller 11 is not rotating, for example, when warming up.
[0024]
Since the peeling member 14 is a so-called contact type that contacts the surface of the fixing roller 11, it is heated by the fixing roller 11 not only by radiant heat but also by heat conduction at the contact point. Therefore, the peeling member 14 can be warmed more rapidly.
[0025]
In addition, the said embodiment can also be changed and comprised as follows.
In the above embodiment, a part of the peeling member 14 is positioned vertically above the fixing roller 11. However, as illustrated in FIG. 4, the entire peeling member 14 is positioned vertically above the fixing roller 11. The configuration may be changed. In such a configuration, since the radiant heat from the surface of the fixing roller 11 is absorbed by the entire peeling member 14, the peeling member 14 can be warmed more quickly.
[0026]
In order to more efficiently absorb the radiant heat from the fixing roller 11 by the peeling member 14, the radiant heat from the fixing roller 11 is absorbed in the vicinity of the surface of the fixing roller 11 at a portion other than the side edge on the fixing roller 11 side. The member may be formed integrally with the peeling member 14. For example, as shown in FIG. 5, the side edge of the peeling member 14 on the fixing roller 11 side may be folded back to the fixing roller 11 side, and the folded portion 14 a may be close to the surface of the fixing roller 11. In this case, since the radiant heat from the fixing roller 11 can be absorbed more efficiently, the peeling member 14 can be heated more quickly.
[0027]
-The surface of the peeling member 14 may be colored black. If comprised in this way, the radiant heat from the fixing roller 11 can be absorbed more efficiently.
In place of the contact-type peeling member 14 of the above-described embodiment, a so-called non-contact type peeling member that does not contact the surface of the fixing roller 11 may be used.
[0028]
-It may replace with the plate-shaped peeling member 14 (peeling board) of the said embodiment, and may use a peeling nail | claw.
Next, the technical idea that can be grasped from the embodiment will be described below.
[0029]
A first rotating body having a heating source and a second rotating body that forms a nip portion between the first rotating body, and the recording material is sandwiched and conveyed by the nip portion; In the fixing device for fixing the unfixed toner image on the upper side, the fixing device includes a peeling member that comes into contact with the recording material discharged from the nip portion and separates the recording material from the first rotating body. The fixing device, wherein the heating source is located closer to the peeling member than the central axis of the first rotating body when not rotating. If comprised in this way, the heating of the peeling member at the time of non-rotation of the 1st rotary body, for example at the time of warm-up, can be performed more rapidly.
[0030]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
According to invention of Claim 1, a peeling member can be warmed rapidly.
[0031]
According to invention of Claim 2, in addition to the effect of invention of Claim 1, a peeling member can be warmed more rapidly.
According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, it is possible to suppress the temperature of the peeling member from being lowered during continuous printing.
[0032]
According to the invention described in claim 4, in addition to the effect of the invention described in claim 3, a temperature drop during continuous printing can be further suppressed.
According to the invention described in claim 5, in addition to the effects of the invention described in any one of claims 1 to 4, when the first rotating body does not rotate, for example, the peeling member during warm-up, Heating can be performed more quickly.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a fixing device according to an embodiment.
FIG. 2 is a perspective view showing the fixing device.
FIG. 3 is a plan view showing the fixing device.
FIG. 4 is a cross-sectional view showing a fixing device according to another embodiment.
FIG. 5 is a cross-sectional view illustrating a fixing device according to another embodiment.
[Explanation of symbols]
P sheet 11 fixing roller 12 as first rotating body pressure roller 13 as second rotating body nip portion 14 peeling member

Claims (6)

A first rotator having a heating source and a second rotator that forms a nip portion between the first rotator and the recording material being sandwiched and conveyed by the nip portion; In a fixing device for fixing an unfixed toner image of
A thin plate-shaped peeling member that contacts the recording material discharged from the nip portion and separates the recording material from the first rotating body is provided , and is opposite to the side edge of the peeling member that contacts the recording material. the side edges of the side, formed so as to extend in the separated state with respect to the first rotary member to accumulate heat radiated to vertically above the first rotary member from the first rotary member A fixing device characterized by that.   The fixing device according to claim 1, wherein a heat capacity of the peeling member is smaller than a heat capacity of the first rotating body.   The fixing device according to claim 1, wherein a part of the peeling member is opposed to a non-sheet passing region in the first rotating body.   The fixing device according to claim 3, wherein a part of the heating source is disposed in a non-sheet passing region in the first rotating body.   5. The apparatus according to claim 1, wherein, when the first rotating body is not rotating, the heating source is located closer to the peeling member than the central axis of the first rotating body. 6. The fixing device described.   The said peeling member further has a folding | returning part extended so that the said 1st rotary body might be followed from the side edge by the side of the said 1st rotary body, The any one of Claims 1-5 characterized by the above-mentioned. The fixing device according to Item.

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