JP3695343B2 - Fixing apparatus and fixing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device and a fixing method 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, there is known a fixing device including a release plate that contacts a recording material discharged from a nip portion and separates the recording material from a rotating body. For example, Japanese Patent Application Laid-Open No. 53-81241 discloses a fixing device including a peeling plate (non-contact type peeling plate) disposed with a predetermined clearance with respect to a rotating body.
[0003]
[Problems to be solved by the invention]
However, in the case of the conventional fixing device, when the recording material is peeled off from the rotating body by the peeling plate, the peeling plate touches the toner image immediately after fixing on the recording material. There is a risk of inviting.
[0004]
Further, in the case of a non-contact type release plate, in order to improve the release performance, it is required to make the clearance between the side edge of the release plate on the rotating body side and the rotating body as small as possible. However, for that purpose, it is necessary to assemble the peeling plate to the rotating body with very high accuracy, which is extremely difficult.
[0005]
The present invention has been made paying attention to the problems existing in the prior art as described above. The objective is to reduce the contact pressure between the recording material and the peeling plate when the recording material is peeled from the rotating body by the peeling plate, thereby suppressing the occurrence of image defects due to the contact between the two. A fixing device and a fixing method using an identification fixing device capable of exhibiting good peeling performance even if the clearance between the side edge of the peeling plate on the rotating body side and the rotating body is large. There is.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes a first rotating body and a second rotating body that forms a nip portion between the first rotating body and the first rotating body. In a fixing device that pinches and conveys a recording material at a nip portion and fixes an unfixed toner image on the recording material, the recording material comes into contact with the recording material discharged from the nip portion and is peeled from the first rotating body. Air is blown from the clearance between the first rotating body and the first rotating body side edge of the peeling plate to the recording plate discharged from the nip portion and the first rotating body. A blowing means for assisting the peeling of the recording material from the rotating body, and a flow path of the air sent by the blowing means, between the side edge on the first rotating body side of the peeling plate and the first rotating body. and a regulating means for regulating the direction toward the clearance, said regulating means, said first Rotary body, the release plate, the first arranged so as to cover the rotating body has been being covered, and that it is constituted by a sealing member is interposed between the cover and the first rotating body Is the gist.
[0008]
According to a second aspect of the invention, in the fixing device according to claim 1, and summarized in that said blowing means sends out warm air.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect , the air blowing unit causes the air to be stronger against the recording material at the central portion than the axial end portions of the first rotating body. The gist is to spray.
[0009]
According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the first rotating body has a heating source, and the blowing unit is the first rotating body. The gist is to send the air above the vertical direction.
[0010]
According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the recording material is sandwiched between the first rotating body side and the second rotating body. The gist is that the atmosphere on the second rotating body side has a negative pressure compared to the atmosphere on the first rotating body side.
[0011]
According to a sixth aspect of the present invention, there is provided a fixing method using the fixing device according to any one of the first to fifth aspects, wherein the timing of the operation of the air blowing means is determined by the recording material at the nip portion. The gist is to synchronize with the passing timing.
[0012]
The invention described in claim 7 is the fixing method using the fixing device as claimed in any one of claims 5, during warm-up, the blowing means, a first rotating body The gist is to cause the first rotating body to function as a heating means by blowing hot air against the first rotating body.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first 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.
[0014]
In an electrophotographic image forming apparatus, as each unit for performing an electrophotographic process, a charging device that uniformly charges a photosensitive member, and a photosensitive member charged by the charging device is selectively exposed to an original image. An exposure device that forms a latent image on the photosensitive member, a developing device that forms a toner image from the latent image, and a transfer device that transfers the toner image onto a sheet (recording material). 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.
[0015]
FIG. 1A and FIG. 2 are schematic configuration diagrams showing a fixing device in the present embodiment. As shown in these drawings, the fixing device includes a fixing roller 11 as a first rotating body incorporating a halogen lamp 11a as a heating source, and a pressure roller 12 as a second rotating body. Yes. 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 both the rollers 11 and 12.
[0016]
The fixing roller 11 is rotationally driven in the direction of arrow A shown in FIG. 1A by a driving means (not shown), and the pressure roller 12 is rotated by being driven by the fixing roller 11. Therefore, when the paper P is conveyed from a transfer device (not shown) to the fixing device and fed between the fixing roller 11 and the pressure roller 12, the paper P is nipped by the nip portion 13 and is in the direction of arrow B shown in FIG. It is designed to be conveyed.
[0017]
In the vicinity of the fixing roller 11, a peeling plate 14 for peeling the paper P discharged from the nip portion 13 from the fixing roller 11 is provided. The peeling plate 14 has a flat plate shape and is disposed along the axial direction of the fixing roller 11 at a position downstream of the nip portion 13 in the rotation direction of the fixing roller 11, that is, substantially parallel to the central axis of the fixing roller 11. . The peeling plate 14 is a so-called non-contact type that does not contact the surface of the fixing roller 11, and a clearance having a predetermined width is provided between the side edge of the fixing roller 11 and the fixing roller 11. (See FIG. 1 (b)). The release plate 14 is attached to a cover 15 described later and supported and fixed at the predetermined position.
[0018]
A cover 15 is provided above the fixing roller 11 so as to cover the roller 11, and a blower chamber 16 is defined by the fixing roller 11, the peeling plate 14, and the cover 15. The blower chamber 16 is largely divided into a space 16a on the upstream side in the paper transport direction and a space 16b on the downstream side in the paper transport direction at an intermediate portion in the paper transport direction. However, both the spaces 16a and 16b communicate with each other via the communication portion 16c.
[0019]
The space 16 a is positioned vertically above the fixing roller 11, and air filling the space 16 a is heated by radiant heat from the fixing roller 11.
[0020]
On the other hand, a blower fan 17 as a blower is disposed in the space 16b. The blower fan 17 sends the air in the space 16 a toward the clearance between the fixing roller 11 and the side edge of the peeling plate 14 on the fixing roller 11 side. A heater 18 is disposed downstream of the blowing fan 17 in the blowing direction as a heating source for heating the air sent from the blowing fan 17. For this reason, the air sent from the ventilation fan 17 can be made into warm air by operating the ventilation fan 17 and the heater 18 simultaneously. Further, on the downstream side of the blowing fan 17 in the blowing direction, a gap between the fixing roller 11 and the cover 15 is closed by seal members 19a and 19b interposed therebetween. For this reason, there is no possibility that the air sent from the blower fan 17 leaks out of the blower chamber 16 through the gap between the fixing roller 11 and the cover 15.
[0021]
In the case of the present embodiment, the restricting means for restricting the flow path of the air sent from the blower fan 17 in the direction toward the clearance between the side edge of the peeling plate 14 on the fixing roller 11 side and the fixing roller 11 is as follows. The fixing roller 11, the peeling plate 14, the cover 15, and seal members 19 a and 19 b are configured.
[0022]
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 sent between the fixing roller 11 and the pressure roller 12. The unfixed toner image on the paper P is fixed and fixed by being sandwiched by the nip portion 13 and being pressurized and heated. After the fixing process, 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 when the side edge on the fixing roller 11 side contacts.
[0023]
When the blower fan 17 operates during the peeling, air is blown against the paper P from the clearance between the fixing roller 11 side edge of the peeling plate 14 and the fixing roller 11 as shown in FIG. It is done. As a result, the force in the direction away from the fixing roller 11 acts on the paper P to assist (promote) the separation of the paper P from the fixing roller 11, and at the same time, the force in the direction away from the separation plate 14 And the contact pressure between the peeling plate 14 and the paper P is reduced.
[0024]
The effects obtained by this embodiment will be described below.
According to the present embodiment, when the paper P is peeled from the fixing roller 11 by the peeling plate 14, the clearance between the fixing roller 11 and the side edge of the peeling plate 14 on the fixing roller 11 side is fixed with respect to the paper P. By blowing air, the contact pressure between the peeling plate 14 and the paper P at the time of peeling can be reduced. Therefore, the occurrence of image defects due to the contact between the peeling plate 14 and the paper P can be suppressed.
[0025]
According to the present embodiment, the air sent from the blower fan 17 assists (promotes) the separation of the paper P from the fixing roller 11, so the side edge of the peeling plate 14 on the fixing roller 11 side and the fixing roller 11. Even if the clearance between the two is large, good peeling performance can be exhibited. And since the high assembly | attachment precision is not required, the assembly | attachment of the peeling plate 14 is easy.
[0026]
Japanese Utility Model Laid-Open No. 62-164364 and Japanese Utility Model Laid-Open No. 3-67362 disclose a fixing device in which air is blown and peeled off on a sheet wound around a fixing roller. However, in these fixing devices, it is necessary to accurately position the tip of the blowing nozzle so that the air blowing direction is the tangential direction of the fixing roller. On the other hand, according to this embodiment, the clearance between the side edge of the peeling plate 14 on the fixing roller 11 side and the fixing roller 11 corresponds to the tip of the blowing nozzle in the above publication. At least a part of the blown air always flows along the fixing roller 11. Therefore, air can be always blown in the tangential direction of the fixing roller 11 with respect to the paper P wound around the fixing roller 11 without strict positioning of the peeling plate 14 and the blower fan 17.
[0027]
Further, in the fixing device disclosed in the above publication, air blown from the blowing nozzle may flow backward into the gap between the blowing nozzle and the fixing roller, and the paper may be caught up. Since there is no part corresponding to, there is no such fear.
[0028]
According to this embodiment, the flow path of the air sent from the blower fan 17 is the fixing roller 11 side of the peeling plate 14 by the fixing roller 11, the peeling plate 14, the cover 15, and the seal members 19a and 19b. It is regulated in the direction toward the clearance between the edge and the fixing roller 11. Therefore, the air sent from the blower fan 17 can be efficiently blown against the paper P discharged from the nip portion 13.
[0029]
-According to this embodiment, the air sent from the ventilation fan 17 can be heated with the heater 18, and can be made into warm air. Therefore, heat loss of the fixing roller 11 and the peeling plate 14 when the air sent from the blower fan 17 is touched can be suppressed.
[0030]
According to the present embodiment, since the air sent from the blower fan 17 is the air in the space 16a heated by the radiant heat from the fixing roller 11, the heater 18 that heats the air sent from the blower fan 17 The burden can be reduced. In addition, since the space 16 a is positioned vertically above the fixing roller 11, the heat energy radiated from the fixing roller 11 can be effectively used for suppressing heat loss of the fixing roller 11 and the peeling plate 14. .
[0031]
(Second Embodiment)
Next, a second embodiment embodying the present invention will be described. In the following embodiments, the same or corresponding components as those in the first embodiment will be denoted by the same reference numerals, a description thereof will be partially omitted, and different configurations will be mainly described.
[0032]
FIG. 4 is a schematic configuration diagram illustrating an image forming apparatus including the fixing device of the present embodiment. As shown in the figure, in addition to the fixing device 20, the image forming apparatus includes a photosensitive member 21, a charging device 22, an exposure device 23, a developing device 24, and a transfer device, as in the image forming device of the first embodiment. In addition to the apparatus 25, a cleaning device 26 that removes and collects toner remaining on the photoconductor 21 after the transfer process, a paper feeding unit 27 that supplies the paper P to the transfer device 25, and a paper P after the fixing process. A paper discharge unit 28 for discharging the image forming apparatus to the outside is provided. In addition, an exhaust fan 29 that exhausts air inside the image forming apparatus to the outside is provided on the upper side surface of the image forming apparatus.
[0033]
The fixing device 20 is provided in the vicinity of the exhaust fan 29. The fixing device 20 is configured such that the pressure roller 12 is positioned on the exhaust fan 29 side with the paper P passing through the identification fixing device 20 interposed therebetween.
[0034]
FIG. 3 is a schematic configuration diagram showing the fixing device in the present embodiment. As shown in the figure, in this embodiment, the cover 15, the blower fan 17, the heater 18 and the like in the first embodiment are omitted. The release plate 14 is attached to the support member 30 and supported and fixed at a predetermined position.
[0035]
Next, the operation of the fixing device configured as described above will be described.
When the exhaust fan 29 is operated at the time of peeling and the air in the image forming apparatus is discharged to the outside, as shown in FIG. 5, the sheet P is removed from the atmosphere near the side edge of the peeling plate 14 on the fixing roller 11 side. The atmosphere on the pressure roller 12 side (lower side in FIG. 5) has a negative pressure compared to the atmosphere on the fixing roller 11 side (upper side in FIG. 5) sandwiched therebetween. As a result, as in the first embodiment, the force in the direction away from the fixing roller 11 acts on the paper P to assist (promote) the peeling of the paper P from the fixing roller 11 and at the same time, the peeling plate. The force in the direction away from 14 acts on the paper P, and the contact pressure between the peeling plate 14 and the paper P is reduced.
[0036]
The effects obtained by this embodiment will be described below.
According to this embodiment, when the paper P is peeled from the fixing roller 11 by the peeling plate 14, the atmosphere on the pressure roller 12 side is negative compared to the atmosphere on the fixing roller 11 side with the paper P interposed therebetween. By setting the pressure, the contact pressure between the peeling plate 14 and the paper P at the time of peeling can be reduced. Therefore, the occurrence of image defects due to the contact between the peeling plate 14 and the paper P can be suppressed.
[0037]
According to the present embodiment, the separation of the sheet P from the fixing roller 11 is assisted (promoted) by the pressure difference caused by the operation of the exhaust fan 29, and therefore, the side edge of the peeling plate 14 on the fixing roller 11 side and the fixing roller 11. Even if the clearance between the two is large, good peeling performance can be exhibited.
[0038]
In addition, the said embodiment can also be changed and comprised as follows.
In the first embodiment, the strength of the air blown against the paper P, such as blowing air against the paper P more strongly at the center than the both ends in the axial direction of the fixing roller 11. May be non-uniform in the axial direction of the fixing roller 11. When air is blown more strongly against the paper P at the center than the both ends of the fixing roller 11 in the axial direction, the paper P adhering at the center in the axial direction of the fixing roller 11 is effectively peeled off. Can be made. Usually, the paper P discharged from the nip portion 13 tends to adhere to the fixing roller 11 at the same central portion as compared to both axial end portions of the fixing roller 11. By effectively separating the adhering paper P, it is possible to effectively prevent the paper P from being wound around the fixing roller 11.
[0039]
For example, the following two methods may be used as a method for blowing air more strongly on the paper P at the central portion than at both axial ends of the fixing roller 11. First, as shown in FIG. 6, the peeling plate 14 is curved so that the central portion in the width direction (axial direction of the fixing roller 11) is convex on the side opposite to the fixing roller 11 side. The clearance between the fixing roller 11 side edge of the peeling plate 14 and the fixing roller 11 is a method in which the central portion is made larger than both axial ends of the fixing roller 11. In the second method, a plurality of blower fans 17 are arranged in the axial direction of the fixing roller 11, and the blower fan 17 that faces the central portion of the fixing roller 11 is opposed to the blower fan 17 that faces both ends of the fixing roller 11 in the axial direction. This is a method of blowing air more strongly.
[0040]
The operation timing of the blower fan 17 may be synchronized with the timing when the paper P passes through the nip portion 13. More specifically, as shown in FIG. 7, the operation of the blower fan 17 is started when the secondary transfer roller separating clutch is turned off, and the blower is blown when the signal from the paper discharge sensor is turned off. The operation of the fan 17 is stopped. In this way, useless operation of the blower fan 17 can be eliminated.
[0041]
The timing of the operation of the heater 18 may be synchronized with the timing at which the paper P passes through the nip portion 13, similarly to the blower fan 17. In this way, useless operation of the heater 18 can be eliminated.
[0042]
The blower fan 17 and the heater 18 of the first embodiment may be operated during warm-up as shown in FIG. 8 so as to function as heating means for warming the fixing roller 11 and the peeling plate 14. In this way, the time required for warm-up can be shortened.
[0043]
In the first embodiment, the heater 18 may be omitted. Since the air sent from the blower fan 17 is the air in the space 16 a that is heated by the radiant heat from the fixing roller 11, hot air is sent from the blower fan 17 without the heater 18. Therefore, also in this case, heat loss of the fixing roller 11 and the peeling plate 14 can be suppressed to some extent.
[0044]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
According to the first aspect of the present invention, by reducing the contact pressure between the recording material and the peeling plate when the recording material is peeled from the rotating body by the peeling plate, an image defect caused by the contact between the two. Can be suppressed. In addition, even if the clearance between the side edge of the peeling plate on the rotating body side and the rotating body is large, good peeling performance can be exhibited.
[0045]
Furthermore , the air sent out by the blowing means can be efficiently blown against the recording material discharged from the nip portion.
[0046]
According to the invention described in claim 2 , in addition to the effect of the invention described in claim 1 , heat loss of the first rotating body can be suppressed.
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 effectively peel off the recording material adhering to the central portion in the axial direction of the first rotating body.
[0047]
According to the invention described in claim 4 , in addition to the effect of the invention described in any one of claims 1 to 3 , the thermal energy radiated from the first rotating body is changed to the first rotating body. It can be effectively used to suppress heat loss.
[0048]
According to invention of Claim 6 , the useless operation | movement of a ventilation means can be eliminated.
According to the seventh aspect of the invention, the time required for warm-up can be shortened.
[Brief description of the drawings]
FIG. 1A is a partially cutaway side view schematically showing a fixing device according to a first embodiment, and FIG. 1B is a cross-sectional view of a main part showing a contact portion between a peeling plate and a sheet at the time of peeling.
FIG. 2 is a perspective view schematically showing the fixing device.
FIG. 3 is a partially broken side view schematically showing a fixing device according to a second embodiment.
FIG. 4 is a schematic configuration diagram illustrating an image forming apparatus including the fixing device according to the embodiment.
FIG. 5 is a cross-sectional view of an essential part showing a contact portion between a peeling plate and a paper during peeling.
FIG. 6 is a cross-sectional view of a main part schematically illustrating a fixing device according to another embodiment.
FIG. 7 is a timing chart showing the operation of the blower fan during the fixing process.
FIG. 8 is a timing chart showing the operation of the blower fan and heater during warm-up.
[Explanation of symbols]
P sheet 11 fixing roller 11a as first rotating body halogen lamp 12 as heating source pressure roller 13 as second rotating body nip portion 14 peeling plate 15 cover 17 constituting restricting means blowing fan as blowing means 19a, 19b Sealing member constituting the regulating means

Claims (7)

An unfixed toner on the recording material by including a first rotating body and a second rotating body that forms a nip portion between the first rotating body and sandwiching and conveying the recording material at the nip portion; In a fixing device for fixing an image,
A peeling plate for contacting the recording material discharged from the nip portion and peeling the recording material from the first rotating body;
Recording is performed from the first rotating body by blowing air from the clearance between the first rotating body side edge of the peeling plate and the first rotating body to the recording material discharged from the nip portion. Air blowing means for assisting in peeling of the material ;
Restriction means for restricting the flow path of the air sent out by the blowing means in a direction toward the clearance between the side edge of the peeling plate on the first rotating body side and the first rotating body. The restricting means includes the first rotating body, the peeling plate, a cover disposed so as to cover the first rotating body, and a gap between the first rotating body and the cover. A fixing device comprising an interposed seal member . The fixing device according to claim 1, wherein the blower sends out warm air . 3. The air according to claim 1, wherein the air is blown more strongly against the recording material at the central portion than the both ends in the axial direction of the first rotating body by the blowing means. Fixing device. The said 1st rotary body has a heat source, and the said ventilation means sends out the air of the vertically upper direction of a 1st rotary body, The Claim 1 characterized by the above-mentioned. Fixing device. When the recording material is sandwiched between the first rotating body side and the second rotating body, the atmosphere on the second rotating body side has a negative pressure compared to the atmosphere on the first rotating body side. the fixing device as claimed in any one of claims 4, characterized by being configured such that. 6. A fixing method using the fixing device according to claim 1, wherein the operation timing of the blowing unit is synchronized with the timing at which the recording material passes through the nip portion. A fixing method characterized by the above. 6. A fixing method using the fixing device according to claim 1, wherein during the warm-up, the blowing unit is configured to blow warm air against the first rotating body. A fixing method, which functions as a heating unit for heating the first rotating body .

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