JP2003241551A - Fixing unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing unit and an image forming apparatus where the radiation of heat from a casing to the outside of the casing is restrained to the utmost, temperature rise at a part positioned on the upside of the casing is restrained and also temperature fall inside the casing is restrained so as to make power consumption low. <P>SOLUTION: The fixing unit 8 is constituted so that recording paper P carried nearly in a vertical direction from the downside to the upside of the casing 80 passes between a fixing roller 81 and a pressure roller 83 so that an image may be fixed, and then it is ejected through an upper aperture 93 formed on the casing. Then, an opening/closing means 95 opened when the recording paper P passes through the aperture 93 and closed when it does not pass through the aperture 93 is disposed on the unit 8. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing unit and an image forming apparatus used in an image forming apparatus such as a copying machine, a printer and a facsimile.

[0002]

2. Description of the Related Art FIG. 4 shows a fixing unit used in a conventional image forming apparatus. The fixing unit 8a has an upper opening formed in the casing after the recording paper P conveyed in a substantially vertical direction from the lower side to the upper side of the casing 80a passes between the fixing roller 81a and the pressure roller 83a and is fixed. It is designed to be discharged via 93a. In this way, the upper opening 93a is normally opened as a conveyance path for the recording paper P. However, since it becomes a large opening located above the fixing unit 8a which is a heat source,
The heat generated in the fixing unit 8a is radiated upward from the upper opening 93a, and the paper discharge sensor 91a and the reading optical system (not shown) arranged immediately above the heat are warmed by the heat, but the temperature is set to an allowable temperature. Since it is necessary to suppress it below, there is a demand to minimize the heat received by these parts such as the paper discharge sensor 91a.

On the other hand, if a fan or the like is used to efficiently cool the sheet discharge sensor 91a or the like to keep the temperature below the allowable temperature, the temperature of the fixing roller 81a itself in the fixing unit 8a is lowered. However, the fixing roller 8
Since the temperature of 1a needs to be kept constant, the heater 82a is turned on and the rate of warming the fixing roller 81a is increased due to the lowered temperature, which may result in an increase in power consumption.

[0004]

Therefore, the present invention solves the above-mentioned conventional problems, suppresses the release of heat from the upper opening of the casing as much as possible, and raises the temperature of the portion located above the casing. An object of the present invention is to provide a fixing unit and an image forming apparatus capable of suppressing the temperature decrease inside the casing as well as suppressing the power consumption.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 is such that a recording sheet conveyed in a substantially vertical direction from the lower side to the upper side in a casing has a space between a fixing roller and a pressure roller. In the fixing unit which is configured to be discharged through the upper opening formed in the casing after passing and being fixed, the recording sheet is opened when the recording paper passes through the upper opening,
An opening / closing means for closing the recording paper when it does not pass is provided. According to a second aspect of the present invention, in the first aspect, the opening / closing means is an opening / closing plate whose one end is axially supported by the casing and which is arranged to be swingable in the recording paper conveyance direction.

According to a third aspect of the present invention, in the second aspect, the swinging range of the opening / closing plate is 0 degrees or more and 60 degrees or less with respect to the vertical direction. The invention of claim 4 relates to claim 2
Or 3, the opening / closing plate is disposed on a rotating member that is provided in the casing and forms an upper opening. A fifth aspect of the invention is an image forming apparatus including the fixing device according to any one of the first to fourth aspects.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an image forming apparatus.
In FIG. 1, at the same time when the document is read by the reading unit 1, the recording paper fed from the paper feed tray 2 is sent to the transfer unit 4 with a timing by the registration roller pair 3. The latent image written on the photoconductor 5 by the writing optical system 7 is visualized by the developing device 6 and transferred onto the recording paper sent to the transfer unit 4. The transferred image is fixed by the fixing unit 8 and then discharged to the paper discharge unit 9. Also, jam (paper jam)
In the case of occurrence of the jam, the jammed paper can be removed by opening a cover provided on the right side of the conveyance path of the apparatus main body so as to be openable and closable. In FIG. 1, 10 is a paper discharge tray.

FIG. 2 shows a detailed view of the fixing unit 8. The fixing unit 8 includes a resin casing 80, and a fixing roller 81 and a pressure roller 83 are arranged in the casing. Reference numeral 82 denotes a heater provided in the fixing roller 81,
84 is a separation claw, 85 is a pressure roller bearing, 86 is a pressure roller pressure lever, 87 is a pressure roller pressure spring, 88 is a temperature fuse, 89 is a thermostat, 90 is a paper discharge roller,
Reference numeral 91 denotes a paper discharge sensor.

An upper opening 93 is formed in the casing 80, and the horizontal portion 9 at the upper part of the casing forming the opening is formed.
An opening / closing plate 95 as an opening / closing means for opening / closing the upper opening 93 is arranged at 4. One end of the opening / closing plate 95 is pivotally supported on the horizontal portion 94 of the casing 80, and is arranged to be swingable in the conveying direction of the recording paper P by the rigidity of the recording paper P and the conveying force. The swing range (swing angle) θ of the opening / closing plate 95 is restricted to 0 to 60 degrees with respect to the vertical direction by abutting against the guide plate 92 above it. This ensures the guide function when the recording paper P is turned in the direction of the paper discharge section 9, and prevents the opening / closing plate 95 from swinging more than necessary due to the stiffness of the paper and the conveying force to return to the closed state. Can be prevented.

That is, the opening / closing plate 95 forms the horizontal portion 94 and the upper opening 93 at the lower limit position where it is closed as shown by the chain line, and abuts on the stepped portion 97 of the portion 96 on the opposite side, and is shown by the solid line. The guide plate 92 disposed above the upper opening 93 abuts at the upper limit position where it is opened, and can swing in the range between the lower limit position and the upper limit position.

When the recording paper P passes through the upper opening 93, the opening / closing plate 95 is pushed up by the rigidity and conveying force of the recording paper to bring it from the closed state to the open state, and after passing, it is closed from the open state by its own weight. Therefore, it is preferable that the casing 80 is made of an extremely lightweight material. For example, as with the casing 80, it is preferably made of resin.

In the above structure, when the image forming apparatus is not in operation, the opening / closing plate 95 is positioned at the lower limit position by its own weight and closes the upper opening 93 of the fixing unit 8 (closed state). . When the image forming apparatus operates and printing is started, the opening / closing plate 95 causes the fixing roller 81 and the pressure roller 8 to move.
After passing through 3 to be fixed, it is pushed open by the rigidity and conveyance force of the recording paper P to be ejected, brought to the upper limit position, and the upper opening 93 is opened (open state). Therefore, when the open / close plate 95 is in the open state, the recording paper P is conveyed through the upper opening 93, guided to the guide plate 92, and discharged to the paper discharge unit 9 along the guide plate 92.

As described above, since the upper opening 93 is opened only while the recording paper P is passing, it is possible to prevent the hot air generated from the fixing unit 8 during preheating / standby from being radiated to the outside of the casing through the upper opening 93 of the casing 80. You can At the same time, the temperature inside the fixing unit 8 can be prevented from lowering, so that the lighting rate of the fixing heater 82 can be reduced and the power consumption can be reduced. Further, since the heat radiation to the upper side of the fixing unit 8 is also reduced, the temperature rise inside the machine, that is, the inside of the image forming apparatus is suppressed, and the margin for cooling the inside of the machine is improved.

FIG. 3 shows an example in which the opening / closing plate 95 is arranged at another place. In this example, the opening / closing plate 95 forms the upper opening 93 of the fixing unit 8 and supports the support shaft 99 on the upper portion of the casing 80.
It is disposed on a rotating member 98 that is rotatably provided by. When the opening / closing plate 95 is arranged on such a rotating member 98, when a paper jam occurs, the rotating member 98 is rotated around the support shaft 99 in the arrow direction to open the upper right side of the casing 80. By doing so, it is possible to make the upper opening including the upper opening 93 large, and it is possible to improve the processability of paper jam.

The opening / closing plate 95 shown in each of the above embodiments is merely an example of the opening / closing means, and any mechanism other than the opening / closing plate 95 is not excluded as the opening / closing means, and various opening / closing means may be adopted. You can Further, even when adopting the opening / closing plate type as the opening / closing means, various types such as mechanically opening / closing by automatic control or opening / closing by double opening can be adopted.

[0016]

The invention of claim 1 is as described above,
The opening / closing means closes the upper opening in a preheating / standby state or the like where paper is not being passed, so that heat radiation from the fixing unit is suppressed, so that heat is efficiently maintained in the unit and power consumption is reduced. In addition, the temperature rise of the portion located above the fixing unit is suppressed, and the temperature rise inside the machine can be suppressed efficiently. According to the invention of claim 2, the upper opening can be easily opened and closed by the opening / closing plate. Further, since the opening / closing plate can be opened / closed by passing paper, for example, a complicated opening / closing mechanism and control are not required.

According to the third aspect of the invention, it is possible to surely perform the opening / closing operation by the recording paper by restricting the swing range of the opening / closing plate. According to the invention of claim 4, by attaching the opening / closing plate to the rotating member, it is possible to secure the effect of claims 1 to 3 and to increase the open area of the conveying path at the time of paper jam, thus improving the paper jam handling property. be able to.

The invention of claim 5 can provide an image forming apparatus including the fixing device of any one of claims 1 to 4.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is an enlarged view of the above fixing unit.

FIG. 3 is an enlarged view of a fixing unit showing another example of the location of the opening / closing plate.

FIG. 4 is an enlarged view of a conventional fixing unit.

[Explanation of symbols]

1 Reading Unit 2 Paper Feed Tray 3 Registration Roller Pair 4 Transfer Part 5 Photosensitive Member 6 Developing Device 8 Fixing Unit 9 Paper Ejection Section 81 Fixing Roller 83 Heating Roller 93 Upper Opening 92 Guide Plate 95 Opening / Closing Plate (Opening / Closing Means) 98 Rotating Member

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DA12 JA11 JB26 JC08                 2H033 AA03 BA02 BA05 BA06 BA10                       BA29 CA07 CA14 CA41                 2H072 CB06 JA04                 3F101 FB08 FE02 LA02 LA05 LA07                       LB03

Claims (5)

[Claims] 1. A recording paper, which is conveyed in a substantially vertical direction from below to above in a casing, is passed through a space between a fixing roller and a pressure roller to be fixed, and then discharged through an upper opening formed in the casing. In the fixing unit that is designed to be opened when the recording paper passes through the upper opening,
A fixing unit comprising opening / closing means for closing the recording paper when it does not pass through. 2. The fixing unit according to claim 1, wherein the opening / closing means is an opening / closing plate whose one end is pivotally supported by the casing and is arranged to be swingable in the recording paper conveying direction. 3. The swing range of the opening / closing plate is 0 with respect to the vertical direction.
The fixing unit according to claim 2, wherein the fixing unit has a temperature of not less than 60 degrees and not more than 60 degrees. 4. The fixing unit according to claim 2, wherein the opening / closing plate is arranged on a rotating member which is provided in the casing and forms an upper opening. 5. An image forming apparatus comprising the fixing device according to any one of claims 1 to 4.