JP2006235144A - Fixing device - Google Patents

Abstract

There is provided a fixing device capable of satisfactorily peeling a recording paper without increasing the warm-up time and without causing the temperature of the fixing belt to become nonuniform.
A fixing belt, a heating roll included in the fixing belt, a pressure roll that pressurizes the heating roll via the fixing belt, and heating that heats the fixing belt or heating roll. In the fixing device including the means 5 and the peeling member 3 included in the fixing belt 2 and disposed downstream of the nip portion formed by the fixing belt 2 and the pressure roll 7, the peeling member 3 is the fixing belt. 2 is provided only at both ends outside the sheet passing area.
[Selection] Figure 1

Description

  The present invention relates to a fixing device used in an electrophotographic apparatus using an electrophotographic process such as a copying machine, a facsimile machine, and a printer.

  In a fixing device using a fixing belt, for example, the following has been conventionally shown in Japanese Patent Application Laid-Open No. 2003-228620 for peeling of a recording sheet after fixing.

  In FIG. 1 of Patent Document 1, a heat-resistant endless film (herein referred to as a fixing belt) 36 for fixing a toner image on a recording paper is wound around a heat roller 35 a and a roller 39, and is largely enlarged there by the roller 39. It is curved. The heat rollers 35a and 35b are in contact with each other with the fixing belt 36 therebetween, and a nip portion is formed between the fixing belt 36 and the heat roller 35b at that position. The roller 39 is configured to be urged away from the heat roller 35a by a tension spring 38.

  In such a configuration, the recording paper on which the toner image is formed is fixed on the recording paper by heat and pressure when passing through the nip portion, and the fixed recording paper is fixed by the fixing belt 36. The toner is conveyed to the position of the roller 39 and is peeled off from the fixing belt 36 at the position of the roller 39 where the fixing belt 36 is greatly curved.

Here, as a roller (hereinbelow, referred to as a peeling roll) 39 for largely curving the fixing belt 36 and peeling the recording paper, generally a cylindrical shape over the entire width of the fixing belt 36 is often used. It is done.
Japanese Patent No. 2648012 (page 3-4, Fig. 1)

  However, the peeling roll is in contact with the fixing belt while applying tension, and in particular, the peeling roll 39 of Patent Document 1 is also a roll for fixing the fixing belt, and the conventional peeling roll is used. In this configuration, a suitable strength is required, and it has a certain heat capacity.

  Therefore, when a peeling roll having such a heat capacity is brought into contact with the inner peripheral surface of the fixing belt over the entire width, the heat of the fixing belt is taken away by the peeling roll, and the temperature of the fixing belt is increased accordingly. The time (warm-up time: hereinafter referred to as WUT) becomes longer.

  Specifically, for example, when the outer diameter is φ10 mm, the wall thickness is t0.5 mm, the length is 240 mm, the material is aluminum, and the temperature rise is 150 ° C., the amount of heat required for that is about 1300 J (joule). . Therefore, when 800 W energization is performed on a heat source such as a halogen lamp in the heat roller, the WUT becomes longer by about 2 seconds when a peeling roll having such a heat capacity is used.

  In addition, it is necessary to use a release roll having a small diameter in order to improve the release capability. In that case, the release roll over the entire inner peripheral surface of the fixing belt causes non-uniform contact with the fixing belt. In addition, due to the non-uniformity of the contact, there is a problem that uneven temperature occurs in the fixing belt and uneven gloss of the copy.

  In the configuration using the fixing belt and the peeling roll, the position where the recording paper peels is not necessarily the position of the peeling roll, and there is a certain distance from the position where the recording paper is heated to the position where the recording paper is peeled off. Therefore, for example, when the toner adhesion area on the recording paper is small, the toner is easily peeled before the peeling roll.

  For this reason, if the distance from the position of the heat roller to which the recording paper is heated to the position of the peeling roll is long, the recording paper is likely to actually peel off before the peeling roll, and the glossiness of copying is increased. It cannot be controlled stably. Therefore, it is desirable to install the peeling roll as close as possible to the heat roller. However, with the peeling roll that rotates over the entire width of the inner peripheral surface of the fixing belt, and the rotating roll is close to the heat roller, there is still a suitable distance. It was necessary and had a problem that the glossiness of the copy was not always stable.

  The present invention solves the above-described conventional problems, and enables good and stable peeling of the recording paper without increasing the WUT and without causing the temperature of the fixing belt to be uneven. An object is to provide a fixing device.

  In order to achieve the above object, the present invention provides a fixing belt, a heating roll included in the fixing belt, a pressure roll that presses the heating roll through the fixing belt, and a fixing belt or a heating roll. A heating unit that heats at least one of the fixing member, and a peeling member that is included in the fixing belt and disposed downstream of the nip formed by the fixing belt and the pressure roll. It is configured to be provided only at both end portions (both end portions) outside the sheet passing area of the belt.

  As a result, while the recording paper is peeled off favorably, the sheet passing area of the fixing belt is not in direct contact with the peeling member and the heat is not taken away. It is possible to provide a fixing device in which non-uniformity does not occur.

  Further, the peeling member may have a means for slidingly guiding the fixing belt, and may be configured to be fixed and in contact with the fixing belt.

  With this configuration, the peeling member is provided only at both end portions of the fixing belt, and the fixing belt does not need to be rotated into a circular column shape by sliding the fixing belt on the arc-shaped sliding guide surface. Can be made small and can be brought closer to the heating roll. As a result, the recording paper peeling position can be brought closer to the nip portion where the toner is fixed, the instability of the position where the recording paper actually peels can be suppressed, and the degree of gloss can be suppressed.

  Further, a tension applying member included in the fixing belt and movably installed at both ends outside the sheet passing area of the fixing belt may be provided, and the tension may be applied to the fixing belt by the tension applying member.

  According to this configuration, since a stable tension can be applied to the fixing belt by moving the tension applying member, it is not necessary to move the peeling member, and a stable peeling of the recording paper can be realized by keeping the peeling position constant. Further, by providing the tension applying member only at both ends of the fixing belt, WUT does not decrease and the temperature of the fixing belt does not become uneven.

  Further, at least one of the peeling member and the tension applying member has meandering restricting means that contacts the end face of the fixing belt, and the peeling member or the tension applying member restricts the meandering of the fixing belt. It is good.

  With this configuration, the peeling member or the tension applying member also serves as a member for performing meandering restriction by means of meandering restricting means, thereby preventing meandering without any special means. Also, if a meandering restricting member is attached where the frictional force between the fixing belt and the peeling member is large, the pressing force to the fixing belt end face by the meandering restricting member is large and the fixing belt is likely to deteriorate. In the case where the peeling belt or the tension applying member is provided only at both ends of the fixing belt, and the double belt also serves as a meandering regulating member, the frictional force between the fixing belt and the peeling member or the tension applying member is small. Since the stress on the end face is also small, the fixing belt can be hardly deteriorated.

  According to the present invention, since the release member is provided only at both ends of the fixing belt, the sheet passing area of the fixing belt is not in direct contact with the release member and heat is not lost while the recording paper is favorably released. Thus, there is an effect that it is possible to provide a fixing device capable of good and stable peeling of the recording paper without lowering the WUT due to the peeling member and without causing nonuniformity of the temperature of the fixing belt.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing a fixing device according to Embodiment 1 of the present invention.

  In FIG. 1, the heating roll 1 is made of aluminum having an outer diameter of 30 mm and a thickness of 0.5 mm. The fixing belt 2 is stretched between a heating roll 1 and a peeling member 3. The fixing belt 2 is formed by sequentially forming a 0.2 mm thick silicone rubber layer and a 0.03 mm Teflon (registered trademark) layer on a 0.05 mm thick polyimide base material. Its circumference is 115 mm, and its width is 230 mm. The peeling member 3 has a pipe shape with an outer diameter of φ10 mm, is formed of PPS (polyphenylene sulfide), is rotatably supported by the rotating shaft 4, and is attached to both ends (both ends) of the fixing belt. Is provided.

  The halogen lamp 5 as the heating means is turned on / off according to the temperature detected by the temperature detection means 6 arranged so as to come into contact with the heating roll 1, and the heating roll 1 and further the fixing belt 2 are brought to a desired temperature. Heat and keep warm. The pressure roll 7 is formed by forming a 5 mm thick silicone rubber layer on a cored bar made of aluminum having an outer diameter of φ20 mm. The pressure roll 7 is pressed against the heating roll 1 by a load of 20 kgf by means not shown, and is supported so as to be able to rotate with the heating roll 1.

  FIG. 2 is a front view schematically showing the fixing device according to Embodiment 1 of the present invention. In FIG. 2, the peeling member 3 is provided outside the recording paper passing width of the fixing belt 2.

  Next, the operation will be described with reference to FIG.

  In FIG. 1, first, the heating roll 1 is rotated in the direction of the arrow by a rotation driving means (not shown), and the fixing belt 2 is caused to travel in the direction of the arrow along with the rotation. As the fixing belt 2 runs, the pressure roll 7 rotates in the direction of the arrow. In this state, the halogen lamp 5 is turned on / off according to the temperature detected by the temperature detecting means 6, and the temperature of the heating roll 1 is heated and kept at 170 ° C.

  At this time, the temperature of the fixing belt 2 is also about 170 ° C. In this state, when the recording paper on which the unfixed toner image is formed passes through the nip portion formed by the fixing belt 2 and the pressure roll 7, the unfixed toner image is generated by the heat and pressure of the nip portion. Then, the recording paper is conveyed by the fixing belt 2 and peeled off from the fixing belt 2 at the position of the peeling member 3. At this time, the recording sheet can be reliably peeled from the fixing belt 2 due to the large curvature of the peeling member 3.

  Here, it experimented about the influence on the WUT of the peeling member 3. FIG. The temperature detecting means 6 is attached to the recording paper passing area of the fixing belt 2.

  First, the WUT required to raise the heating roll 1 from 20 ° C. to 170 ° C. was measured with no peeling member attached, and the value was 22 seconds. Next, when a peeling member that is the same material as that of the peeling member 3 and is attached to the entire area in the axial direction is attached as an equivalent to the conventional general peeling roll, the WUT was 24 seconds when the same measurement was performed. On the other hand, when the peeling member 3 was attached, it was 22 seconds, which was about 2 seconds shorter than that corresponding to a conventional general peeling roll, which was the same as when no peeling member was attached.

  Furthermore, this time, it experimented about the influence on the temperature uniformity of the peeling member 3. FIG. When the temperature distribution in the case where the peeling member is not attached is used as a reference, when the peeling member covering the entire axial direction is attached with the same material as the peeling member 3, the outer side (both ends of the recording paper passing area) with respect to the center The temperature dropped by 2 ° C.

  This is presumably because the contact state between the peeling member and the fixing belt 2 is uneven, varies depending on the position in the axial direction, and the central portion is insufficient. On the other hand, the peeling member 3 had no effect on the recording paper passing area even when it was attached.

  According to the configuration of the present embodiment, the sheet passing area of the fixing belt 2 does not lose heat by the direct contact of the peeling member 3, so that there is no decrease in WUT and the temperature of the fixing belt is not uniform. Further, it is possible to provide a fixing device in which neither occurs.

  Although the temperature detection means 6 is in contact with the heating roll 1, it may be in contact with the inside of the fixing belt 2.

  In addition, two rotation shafts 4 are provided at both end portions of the fixing belt 2, but this may be one in which one shaft is supported at both ends without being in contact with the fixing belt 2. In this case, not only the strength improvement effect with respect to the bending of the rotating shaft 4 but also the effect of preventing the buckling of the fixing belt 2 due to the structure that hits the rotating shaft 4 even when the fixing belt 2 buckles.

  Further, the halogen lamp 5 is provided on the inner side of the heating roll 1, but it may be provided on the outer side of the heating roll 1 and on the inner side of the fixing belt 2. May be provided. In the case of providing the outer periphery of the heating roll 1 and the inner periphery of the fixing belt 2, for example, a configuration in which a halogen lamp 5 is provided inside a metal pipe other than the heating roll 1 can be used.

  Further, although the halogen lamp 5 is used as the heating means, this may be various heaters or heating means using electromagnetic induction.

(Embodiment 2)
Next, FIG. 3 is a sectional view showing a schematic configuration of the fixing device according to the second embodiment of the present invention.

  In FIG. 3, the peeling member 3 itself has an arcuate sliding guide surface on which the fixing belt 2 slides without rotating, and the inner surface outside the recording paper passing width of the fixing belt 2 slides there. It is configured to move. The tension applying member 8 has substantially the same shape as the peeling member 3 and is configured to apply a desired tension to the fixing belt 2 by a spring 9.

  FIG. 4 is an enlarged perspective view of the peeling member 3 (tension applying member 8). The peeling member 3 has a sliding guide surface 3a of the fixing belt and a flange 3b (meandering restriction portion) with which the end surface of the fixing belt 2 abuts.

  The basic operation in this configuration is almost the same as in the first embodiment. Since tension is applied to the fixing belt 2 by the tension applying member 8 and the spring 9, the traveling of the fixing belt 2 is more stable as compared to the state without the tension applying member 8.

  Further, since the tension applying member 8 can be moved by the spring 9 and the peeling member 3 is not moved, the peeling position between the fixing belt 2 and the recording paper is fixed as in the case where the tension applying member 8 is not provided. Can be kept in.

  Further, even if the fixing belt 2 meanders to either side in the rotation axis direction, the end surface comes into contact with the flange 3b of the peeling member 3 or the tension applying member 8, and the meandering is suppressed at that position. It should be noted that no deterioration of the end face of the fixing belt 2 was observed even when running in that state for a long time.

  According to the configuration according to the present embodiment, the peeling members 3 are provided only at both ends of the fixing belt, and the fixing belt 2 slides on an arcuate sliding guide surface or the like so that it rotates in a cylindrical shape. There is no need to do this, and a fan-like shape having an arc is sufficient, and the size can be reduced and the heating roll 1 can be brought closer. Accordingly, it is possible to provide a fixing device in which the separation position of the recording paper can be brought close to the nip portion where the toner is fixed, the variation width of the separation position is suppressed, and the degree of gloss is suppressed.

  Further, according to this configuration, since the tension applying member 8 can be moved, a stable tension can be applied to the fixing belt 2, so that the peeling member 3 is not movable and the peeling position is kept constant. Can do. Thereby, stable peeling of the recording paper can be realized. Further, by providing the tension applying member 8 only at both ends of the fixing belt, the WUT is not lowered and the temperature of the fixing belt is not uneven.

  In addition, according to such a configuration, the peeling member 3 or the tension applying member 8 also serves as a member that stops the progress of the meandering, thereby preventing meandering without any special means. Further, in the case of the peeling member over the entire axial direction, if a meandering restriction member is attached to a place where the frictional force between the fixing belt 2 and the peeling member is large, the pressing force to the end face of the fixing belt 2 by the meandering restriction member is large, and the fixing member The belt 2 is likely to deteriorate.

  However, in the case where the peeling member 3 or the tension applying member 8 is provided only at both ends of the fixing belt as in this configuration, and it also serves as a meandering regulating member, the fixing belt 2 and the peeling member 3 or the tension applying member 8 Since the frictional force is small and the stress on the end face of the fixing belt 2 by the meandering regulating member is also small, the fixing belt 2 can be hardly deteriorated.

  In the present embodiment, the peeling member 3 and the tension applying member 8 are substantially the same members, but different materials or shapes may be used. Further, since the same member is used for each, both of the meandering restricting portions for the fixing belt 2 are provided. However, the meandering restricting portion (the flange portion 3b) is either the peeling member 3 or the tension applying member 8. Therefore, different members can be used.

  The fixing device according to the present invention has an effect of fixing a toner image formed on a recording paper, and is applied to an electrophotographic apparatus using an electrophotographic process such as a copying machine, a facsimile, and a printer.

Sectional drawing which shows the outline of the fixing device in Embodiment 1 of this invention. 1 is a front view showing an outline of a fixing device in Embodiment 1 of the present invention. Sectional drawing which shows the outline of the fixing device in Embodiment 2 of this invention. The expansion perspective view of the peeling member in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating roll 2 Fixing belt 3 Peeling member 5 Halogen lamp (heating means)
7 Pressure roll 8 Tension applying member

Claims (4)

A fixing belt,
A heating roll included in the fixing belt;
A pressure roll that pressurizes the heating roll via the fixing belt;
Heating means for heating at least one of the fixing belt or the heating roll;
A peeling member that is included in the fixing belt and disposed downstream of a nip portion formed by the fixing belt and the pressure roll;
The fixing device according to claim 1, wherein the peeling member is provided only at both ends of the fixing belt outside the sheet passing area. The fixing device according to claim 1, wherein the peeling member is fixed by itself and contacts the fixing belt to slide and guide the fixing belt. 2. A tension applying member included in the fixing belt and movably installed at both ends outside the sheet passing area of the fixing belt, and tension is applied to the fixing belt by the tension applying member. Or the fixing device according to 2; At least one of the peeling member and the tension applying member has meandering restricting means that comes into contact with the end face of the fixing belt, and the peeling member or the tension applying member restricts meandering of the fixing belt. The fixing device according to any one of claims 1 to 3.

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