JPH05341674A - Fixing unit for image forming device - Google Patents

Abstract

PURPOSE:To straighten curling at the time of fixing toner by means of a circular-arcuate part and to eject a recording paper in a straight state by providing the circular-arcuate having a large radius, on a part corresponding to the nipping part for fixing of a heating element or the following part. CONSTITUTION:The heating element 4 has, at least, a heater 2 whose one part serves as a heat generating part 1, and a holder 3 holding the heater 2, in the electing side (the arrow A) of the recording paper 8 of the holder 3, the circular-arcuate part having the large radius (holder R-part) 9 is provided on the part adjacent to the part corresponding to the nipping part for fixing 7 of a pressure roller 6, and when a belt 5 is wound on a belt winding roller, the belt 5 is moved along the holder R-part 9. The heating element 4 is constituted in this way, and the curling at the time of fixing the toner is straightened by the holder R-part 9, so that the recording paper 8 carried by the belt 5 is ejected in a straightened state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic image forming apparatus, and more particularly to a fixing device for an image forming apparatus that performs fixing by thermal pressure.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view showing an example of a fixing device of a conventional image forming apparatus.

Among the fixing devices of the electrophotographic image forming apparatus, the conventional fixing device of the image forming apparatus for fixing by heat pressure fixes the toner of the image formed on the recording paper 8 as shown in FIG. Exothermic part 81 that generates heat for
And a holder 8 for holding the heater 82.
3 and a heater 82 for holding the recording paper 8
Pressure roller 86 that presses against the heater 82
And a pressure roller 87, which is interposed between the pressure roller 8 and the pressure roller 87.
In the portion (fixing Nip portion) 87 where 6 contacts the heater 82, the toner of the image on the recording paper 8 is fixed by heating while applying pressure to the fixing Nip portion 87 of the heater 82 (holder 83). The corresponding part is formed in a plane.

[0004]

In the conventional fixing device of the image forming apparatus as described above, the fixing N of the heater (holder) is used.
Since the portion corresponding to the ip portion is formed flat and the recording paper is heated only from the heater side, when the recording paper is discharged out of the pressure roller, it curls toward the pressure roller to form an image. It has a drawback that the subsequent handling of the recording paper is troublesome.

[0005]

A fixing device for an image forming apparatus according to the present invention comprises a heater having at least a part as a heat generating portion for fixing toner of an image formed on a recording medium, and a holder for holding the heater. In a fixing device of an image forming apparatus, a heating element having: a pressure roller that presses the recording medium against the heater; and a belt that is interposed between the heater and the pressure roller and that conveys the recording medium. , A circular arc portion having a large radius is provided in a portion continuous with a portion corresponding to the fixing Nip portion of the pressure roller on the discharge side of the recording medium of the holder, or the fixing Nip of the pressure roller of the holder.
An arc portion having a large radius is provided in a portion corresponding to the portion, and the belt is moved along the arc portion.

[0006]

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

FIG. 1 is a sectional view showing a main part of the embodiment shown in FIG. 3, and FIG. 3 is a perspective view showing a first embodiment of the present invention.

The fixing device 22 shown in FIG. 3 has a heating element 4 having a heater for fixing the toner of the image formed on the recording paper 8, and a pressure roller 6 for pressing the recording paper 8 against the heating element 4. The belt 5 is provided between the heating element 4 and the pressure roller 6 and conveys the recording paper 8. The belt 5 is supplied from the belt supply roller 24 and wound around the belt winding roller 23. .. The pressure roller 6 is pressed against the heating element 4 by a spring 26 via bearings 25 provided at both ends. The spring 26 is held by the frame 27 at the other end.

In the fixing device 22 thus constructed, the recording paper 8 is inserted between the pressure roller 6 and the belt 5 while the belt 5 is moved, and the recording paper 8 is subjected to heat and pressure while being conveyed by the belt 5. Thus, the toner of the image formed on it can be fixed.

As shown in FIG. 1, the heating element 4 has a heater 2 having at least a part of the heating portion 1 and a holder 3 for holding the heater 2, and the recording paper 8 of the holder 3 is discharged. On the side (arrow A), a circular arc portion (holder R portion) 9 having a large radius is provided in a portion continuous with the portion corresponding to the fixing Nip portion 7 of the pressure roller 6, and the belt 5 winds the belt winding roller 23. When it is wound up, it is moved along this holder R portion 9.

By configuring the heating element 4 in this way, the recording paper 8 conveyed by the belt 5 is ejected in a straight state in which the curl generated when the toner is fixed is corrected by the holder R portion 9. It

FIG. 2 is a sectional view showing the main part of the second embodiment of the present invention.

The embodiment shown in FIG. 2 is a heating element 4 of the embodiment shown in FIG.
Instead of the above, a heating element 14 is provided.

The heating element 14 has at least a part of the heating section 1.
No. 1 heater 12 and holder 13 for holding the heater 12
And a portion corresponding to the fixing Nip portion 7 of the pressure roller 6 of the heater 12 (holder 13) is an arc portion (heater R portion) 19 having a large radius.

The operation and effect of this embodiment are the same as those of the embodiment of FIG. 3 (FIG. 1).

4A and 4B are views showing an image forming apparatus using a third embodiment of the present invention. FIG. 4A is a perspective view showing the entire structure, and FIG. 4B is a sectional view taken along the line CC.

The image forming apparatus 68 of FIG. 4 has a heating element 54 for fixing the toner of the image formed on the recording paper 8,
A pressure roller 56 that presses the recording paper 8 against the heating element 54, and a belt 55 that is provided between the heating element 54 and the pressure roller 56 and that conveys the recording paper 8 are provided. The pressure roller 56 is heated by a spring 66 via bearings 65 provided at both ends.
Being pressed against. The other end of the spring 66 is held by the frame 67.

The belt 55 provided between the heating element 54 and the pressure roller 56 is driven by the driving roller 63, and the guide roller 64 and the guide roller 62.
And circulating between the heating element 54 and the drive roller 63,
The pressure roller 56 is driven to rotate to convey the recording paper 8 held between the pressure roller 56 and the pressure roller 56. A developing unit 69 is provided facing the guide roller 62. The developing unit 69 transfers the unfixed toner of the image onto the belt 55, and the belt 55 transfers the unfixed toner to the recording paper 8.
Then, it is retransferred to and fixed by a fixing device.

The heating element 54, as shown in FIG.
It has the same structure as the embodiment of FIG. 3 (FIG. 1). That is, the heater 52 having at least a part of the heat generating portion 51
And a holder 53 for holding the heater 52,
On the discharge side (arrow A) of the recording paper 8 of the holder 53, a circular arc portion (holder R portion) 59 having a large radius is formed in a portion continuous with a portion corresponding to the fixing Nip portion 57 of the pressure roller 56.
Is provided, and when the belt 55 is circularly moved, it is moved along the holder R portion 59.

By configuring the heating element 54 in this way, the curl generated when the toner is fixed is corrected by the holder R portion 59 and the recording paper 8 conveyed by the belt 55 is discharged in a straight state. It

FIG. 5 is a sectional view showing the main part of the fourth embodiment of the present invention.

In the embodiment of FIG. 5, a heating element 74 is provided in place of the heating element 54 of the embodiment of FIG. 1 of the embodiment of FIG. 4, and the configuration of the heating element 74 is the same as that of the embodiment of FIG. Is the same as.
That is, the heating element 74 has at least a part of the heating section 71.
The heater 72 and the holder 73 for holding the heater 72 are provided. It is what

Therefore, the operation and effect of this embodiment are shown in FIG.
Is the same as the embodiment of FIG. 3, that is, the embodiment of FIG. 3 (FIG. 1).

[0024]

As described above, in the fixing device of the image forming apparatus of the present invention, the arc portion having a large radius is provided in the portion corresponding to the fixing Nip portion of the heating element or in the portion subsequent to the fixing Nip portion. The curl generated at the time of fixing is corrected by the arc portion and can be discharged in a straight state. Therefore, the recording medium after image formation can be easily handled.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of the embodiment shown in FIG.

FIG. 2 is a sectional view showing a main part of a second embodiment of the present invention.

FIG. 3 is a perspective view showing a first embodiment of the present invention.

4A and 4B are views showing an image forming apparatus using a third embodiment of the present invention, FIG. 4A is a perspective view showing the entire structure, and FIG. 4B is a sectional view taken along line CC.

FIG. 5 is a sectional view showing a main part of a fourth embodiment of the present invention.

FIG. 6 is a perspective view showing an example of a fixing device of a conventional image forming apparatus.

[Explanation of symbols]

 1, 11, 31, 51, 71, 81 Heat generating part 2, 12, 32, 52, 72, 82 Heater 3, 13, 33, 53, 73, 83 Holder 4, 14, 34, 54, 74, 84 Heat generating element 5.15.35.55.55.75.85 Belt 6.56.76.86 Pressure roller 7.57.77.87 Fixing Nip part 8 Recording paper 9.59 Holder R part 19.79 Heater R part 22 Fixer 23 Belt take-up roller 24 Belt supply roller 25/65 Bearing 26/66 Spring 27/67 Frame 62/64 Guide roller 63 Drive roller 68 Image forming device 69 Exposure and development unit

Claims (2)

[Claims] 1. A heating element having a heater having at least a part as a heating portion for fixing toner of an image formed on a recording medium, and a holder for holding the heater, and the recording medium with respect to the heater. In a fixing device of an image forming apparatus, which comprises a pressure roller for pressing and a belt for conveying the recording medium interposed between the heater and the pressure roller, the pressure roller of the holder on the discharge side of the recording medium A fixing device of an image forming apparatus, wherein an arc portion having a large radius is provided in a portion subsequent to a portion corresponding to the fixing Nip portion, and the belt is moved along the arc portion. 2. A heating element having a heater having at least a part as a heating portion for fixing toner of an image formed on a recording medium and a holder for holding the heater, and the recording medium with respect to the heater. In a fixing device of an image forming apparatus including a pressure roller for pressing and a belt interposed between the heater and the pressure roller to convey the recording medium, a portion of the holder corresponding to a fixing Nip portion of the pressure roller. A fixing device for an image forming apparatus, wherein a circular arc portion having a large radius is provided on the base, and the belt is moved along the circular arc portion.