JPH07168470A - Fixing device - Google Patents

Abstract

PURPOSE:To extremely simplify the constitution of a fixing device and to make the operability and the heat efficiency thereof excellent. CONSTITUTION:The fixing device is provided with a heating roller 50 generating heat to fixed temperature and a pressure roller 10 brought into contact with the roller 50 by fixed pressure. By rotating the rollers 10 and 50 while interposing paper 54 on which toner (not shown in a figure) is transferred between them, the toner is fixed on the paper 54. Besides, it is provided with a paper attraction means 12 attracting the paper 54 to the outside circumferential surface 10a of the roller 10 and a paper separation means 14 separating the paper 54 attracted to the outside circumferential surface 10a of the roller 10.

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 electrophotography used in an image recording device such as an electrophotographic printer or an electrophotographic copying machine.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional fixing device of this type. Hereinafter, description will be given with reference to this drawing.

The conventional fixing device is provided with a heating roller 50 which generates heat at a constant temperature and a pressure roller 52 which comes into contact with the heating roller 50 at a constant pressure. The sheet 54 on which the toner (not shown) has been transferred is sandwiched and rotated so that the toner is transferred to the sheet 5.
It is fixed at 4. The sheet 54 has a guide portion 64a.
Is introduced in the direction of the arrow 66a, is subjected to the fixing process, and is discharged from the guide portion 64b in the direction of the arrow 66b.

A halogen lamp 56 as a heat source is provided inside the heating roller 50, and an oil impregnated pad 60 impregnated with an oil 58 for offset prevention is provided on the outer periphery of the heating roller 50. A peeling claw 62 for preventing the adhesion is provided on the outer circumference. Pressure roller 52
Has a heat-resistant rubber layer on the outer periphery that can be driven and rotated while being in pressure contact with the heating roller 50.

The diameter of the heating roller 50 or the pressure roller 52 is 25 to 60 depending on the image recording specifications of the image recording apparatus.
In the same image recording apparatus, the heating roller 50 and the pressure roller 52 have substantially the same diameter.

Further, in the case of a conventional fixing device, in fixing an image on a normal plain paper with a toner, the moving speed (peripheral speed) of a transfer device (not shown) such as a photoconductor and the moving speed of the heating roller 50. And the operation is almost the same, and image formation is in progress.

By the way, when a thick sheet is used, a special toner requiring high heat is used, or the like, for example, when fixing an image with color toners on a transparent sheet for OHP, fixing is performed under normal fixing conditions. Because it is not possible, another fixing mode is prepared.

In order to form a transparent fixed image by fixing the color toner on the transparent sheet, in order to form a smooth fixed toner image surface without containing air bubbles inside the color toner, This is because it is necessary to supply more heat energy than under normal fixing conditions.

In such a case, the conventional fixing device deals with the following three kinds of techniques.

The temperature of the heating roller is raised.

The fixing speed is delayed. That is, the rotation speeds of the heating roller and the pressure roller are delayed.

Re-fix. That is, the fixing process is performed again on the sheet that has once undergone the fixing process. For example, JP-A-60-121477 and JP-A-60-1
No. 21478, Japanese Patent Laid-Open No. 63-271385, and the like.

[0013]

However, in the above-mentioned prior art, a material having a high heat resistance, a high-power heat source,
It is necessary to use a high-performance temperature controller etc.
Invites higher prices. Also, when switching between the normal temperature mode and the high temperature mode, the operation is not performed until the temperature becomes constant, so the operability is deteriorated. In the above-mentioned conventional technique, a highly functional speed controller is required, and it is also necessary to match the speed with the transfer system, resulting in complication and cost increase. Also,
Since the processing speed becomes slower as the time required for heating increases, the operability deteriorates. In the above prior art,
Once the paper that has undergone the fixing process is ejected from the fixing device,
After passing through a special conveyance path, it is introduced into the fixing device again and a second fixing process is performed, resulting in an extremely complicated configuration. Moreover, even the paper once subjected to the fixing process is cooled while passing through the conveying path, so that the thermal efficiency in the fixing process is poor.

[0014]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a fixing device having an extremely simple structure and excellent operability and thermal efficiency.

[0015]

The present invention has been made in order to achieve the above-mentioned object, and is a heating roller that generates heat at a constant temperature and a pressurizing member that is in contact with the heating roller at a constant pressure. The fixing device is provided with a roller, and the pressure roller and the heating roller sandwich and rotate the sheet on which the toner is transferred to fix the toner on the sheet.

That is, the fixing device according to the first aspect of the present invention is a sheet adsorbing means for adsorbing the sheet on the outer peripheral surface of the pressure roller, and a sheet detaching section for detaching the sheet adsorbed on the outer peripheral surface of the pressure roller. And means.

According to a second aspect of the present invention, in the fixing device, an endless thin body is sandwiched between the pressure roller and the heating roller together with the sheet, and a sheet adsorbing unit that adsorbs the sheet on an outer peripheral surface of the thin body. A sheet removing means for removing the sheet adsorbed on the outer peripheral surface of the thin body.

[0018]

The operation of the fixing device according to the first aspect is as follows. The sheet on which the toner is transferred is sandwiched between the heating roller and the pressure roller, and the toner is fixed on the sheet by rotating the heating roller and the pressure roller. At this time, the paper is attracted to the outer peripheral surface of the pressure roller by the paper suction means. Then, the paper makes one rotation with the rotation of the pressure roller, and then is again sandwiched between the heating roller and the pressure roller, and the second fixing process is performed. Subsequently, when the sheet adsorbed on the outer peripheral surface of the pressure roller is removed by the sheet removing means, the sheet is ejected.

The operation of the fixing device according to the second aspect is as follows. The sheet on which the toner is transferred is sandwiched between the heating roller and the pressure roller together with the thin-walled body, and the toner is fixed on the sheet by rotating the heating roller and the pressure roller. At this time, the sheet is sucked onto the outer peripheral surface of the thin body by the sheet suction means. Then, the sheet makes one rotation with the rotation of the thin body, and then is sandwiched again by the heating roller and the pressure roller, and the second fixing process is performed. Then, when the sheet adsorbed on the outer peripheral surface of the thin body is removed by the sheet removing means, the sheet is ejected.

As described above, in the fixing device of the present invention, re-fixing is possible without requiring a special conveying path or the like.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the fixing device described in claim 1. Hereinafter, description will be given with reference to this drawing. However, the same parts as those in FIG.

This fixing device is provided with a heating roller 50 that generates heat at a constant temperature and a pressure roller 10 that comes into contact with the heating roller 50 at a constant pressure. Toner is transferred to the paper sheet 54 by sandwiching the transferred paper sheet 54 (not shown) and rotating it.
Is to be fixed in. Further, a sheet suction means 12 for sucking the sheet 54 on the outer peripheral surface 10a of the pressure roller 10,
The pressure roller 10 is provided with a sheet removing means 14 for removing the sheet 54 adsorbed on the outer peripheral surface 10a.

A pressure roller 10 having a diameter of 80 mm is disposed in a heating roller 50 containing a halogen lamp 56 so that it can be pressed and driven. A paper feed direction switching claw 20 is provided on the fixing and discharging side. Paper feed direction switching claw 2
A value of 0 ensures switching between the direction for re-fixing the sheet 54 after fixing with the rotation of the pressure roller 10 and the direction for discharging the sheet 54 at the end of fixing.

Paper suction means 12 and paper removal means 14
Is for adsorbing or separating the sheet 54 by an electrostatic action. Therefore, a conductor layer 10b such as a metal foil is provided on the inner peripheral surface of the pressure roller 10, and the sheet suction means 12 is provided.
As the DC bias power source, a sheet biasing means 14 is used as the AC bias power source. Further, by applying the output voltage of the DC bias power supply or the AC bias power supply to the conductor layer 10b by the changeover switch 22, the paper 54 is attracted to or detached from the outer peripheral surface 10a of the pressure roller 10.

The outer periphery of the pressure roller 10 has a guide portion 6
A cover 24 integrated with 4a covers it at regular intervals. Further, on the outer periphery of the heating roller 50,
The oil applying rollers 26 and 28 for applying the offset preventing oil 58 to the surface of the heating roller 50 and the cleaning roller 30 for cleaning the surface of the heating roller 50 are provided. Further, the paper feeding direction switching claw 20 and the switching switch 22 are interlocked by a control device such as a computer (not shown).

The operation of the fixing device having the above structure will be described.

When the paper 54 is fed from the direction of the arrow 66a, the paper feed direction switching claw 20 directs its tip toward the heating roller 50 side, and the changeover switch 22 causes the output voltage of the paper suction means 12 to change to the conductor layer. 10b is applied. Subsequently, the paper 54 is sandwiched between the heating roller 50 and the pressure roller 10, and the first fixing process is performed by the rotation of the heating roller 50 and the pressure roller 10.

Then, the sheet 54 makes one revolution as the pressure roller 10 rotates while being attracted to the outer peripheral surface 10a of the pressure roller 10 by the action of the sheet attracting means 12. Then, it is sandwiched between the heating roller 50 and the pressure roller 10 again, and the second fixing process is performed. At this time, when the second fixing process starts, the paper feeding direction switching claw 20 directs its tip toward the pressure roller 10 side, and the switching switch 2
2 causes the output voltage of the paper removing means 14 to change to the conductor layer 10b.
Applied to. Therefore, the sheet that has been subjected to the second fixing process is discharged in the direction of arrow 66b.

FIG. 2 is a sectional view showing an embodiment of the fixing device according to the present invention. Hereinafter, description will be given with reference to this drawing. However, the same parts as those in FIG. 1 or FIG.

This fixing device is provided with a heating roller 50 which generates heat at a constant temperature and a pressure roller 52 which comes into contact with the heating roller 50 at a constant pressure. The pressure roller 52 and the heating roller 50 are toner. Toner is transferred to the paper sheet 54 by sandwiching the transferred paper sheet 54 (not shown) and rotating it.
Is to be fixed in. Further, the endless thin body 32 is sandwiched between the pressure roller 52 and the heating roller 50 together with the sheet 54, the sheet adsorbing means 34 for adsorbing the sheet 54 to the outer peripheral surface 32 a of the thin body 32, and the outer peripheral surface of the thin body 32. 32
Paper removing means 36 for removing the paper 54 attracted to a
It has and.

The thin body 32 is made of nickel or the like having a diameter of 80 mm and a thickness of 0.1 mm or less, and is formed into a cylindrical shape. The sheet suction means 34 and the sheet release means 36 have the same principle as the sheet suction means 12 and the sheet release means 14 in FIG.
The outer peripheral surface 32 a of the sheet 54 adsorbs or detaches the sheet 54.

The operation of the fixing device having the above structure will be described.

When the paper 54 is fed from the direction of the arrow 66a, the paper feed direction switching claw 20 directs its tip toward the heating roller 50 side, and the changeover switch 22 causes the output voltage of the paper suction means 34 to be thin. 32 is applied. Subsequently, the sheet 54 is sandwiched between the heating roller 50 and the pressure roller 52 together with the thin body 32, and the first fixing process is performed by the rotation of the heating roller 50 and the pressure roller 10.

Then, the sheet 54 makes one rotation as the pressure roller 52 rotates while being attracted to the outer peripheral surface 32a of the thin body 32 by the action of the sheet attracting means 32. And
It is sandwiched again with the heating roller 50, the pressure roller 52, and the thin body 32, and the second fixing process is performed. At this time, when the second fixing process starts, the paper feeding direction switching claw 20 directs its tip toward the pressure roller 52 side, and
The output voltage of the sheet removing means 36 is applied to the thin body 32 by the changeover switch 22. Therefore, the sheet that has been subjected to the second fixing process is discharged in the direction of arrow 66b.

In the two embodiments described above, the heating roller 50 is used, but the heating roller 50 is not limited to this, and may be any one that heats the paper and toner. . Such a thing is also included in the concept of the "heating roller" in the present invention.
In that case, the pressure roller 10 or the thin body 32 and the pressure roller 52 must be configured to rotate.

Further, a cleaning member for cleaning the surface of the pressure roller 10 or the thin body 32 may be additionally provided.

In the above embodiment, the pressure roller 1
0 or a thin body 32 with a diameter of 80 mm was used, but this is in consideration of the case of A4 or letter size transparent sheets for OHP being fed vertically, and the perimeter around which each sheet can be wrapped. This is set to Therefore, if transverse feed is possible, the diameter can be 80 mm or less.

Further, although the pressure contact force between the heating roller and the pressure roller was not particularly mentioned, it is possible to change the pressure at the time of the first fixing and at the time of re-fixing, thereby forming a higher quality image. Becomes

Further, although the example in which the re-fixing is performed once has been described, the re-fixing can be repeated any number of times if necessary.

Furthermore, the paper suction means 12 and 34 and the paper removal means 14 and 36 may utilize vacuum suction or the like.

As described above, according to the fixing devices of the above-described two embodiments, different fixing is required,
For example, for fixing a transparent color toner image on a transparent sheet for OHP, only a structural change to increase the diameter of a conventional pressure roller or a conventional pressure roller is used. An endless thin-walled body can be interposed between the roller and the pressure roller to enable the driven body to output a high-quality image without reducing the output speed. In addition, it can be easily realized without any significant change in the device structure and cost increase.

[0042]

According to the fixing device of the present invention, the sheet which has once been subjected to the fixing process is adsorbed to or detached from the pressure roller or the like, so that the sheet is re-fixed without requiring a special conveyance path or the like. be able to. That is, since no special conveyance path or the like is required, the configuration can be made extremely simple and the cooling of the paper due to the paper passing through the conveyance path or the like can be suppressed. Moreover, there is no waiting time at the time of mode switching, no large delay in processing speed, and the like, and operability is good. Therefore, it is possible to provide a fixing device having an extremely simple structure and excellent operability and thermal efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a fixing device according to claim 1.

FIG. 2 is a sectional view showing an embodiment of the fixing device according to the present invention.

FIG. 3 is a sectional view showing a conventional example of a fixing device.

[Explanation of symbols]

 10,52 Pressure Roller 10a Pressure Roller Outer Surface 12,34 Paper Adsorption Means 14,36 Paper Release Means 32 Thin Wall 32a Thin Wall Outer Surface 50 Heating Roller 54 Paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display B65H 5/06 F

Claims (2)

[Claims] 1. A sheet having a heating roller that generates heat at a constant temperature and a pressure roller that comes into contact with the heating roller at a constant pressure, the pressure roller and the heating roller having toner transferred thereto. In a fixing device for fixing this toner to this paper by sandwiching and rotating the paper, paper adsorbing means for adsorbing the paper on the outer peripheral surface of the pressure roller, and the paper adsorbed on the outer peripheral surface of the pressure roller. A fixing device, which is provided with a sheet releasing means for releasing the sheet. 2. A paper sheet having a heating roller that generates heat at a constant temperature and a pressure roller that comes into contact with the heating roller at a constant pressure, and the pressure roller and the heating roller have toner transferred thereto. A fixing device for fixing the toner to the sheet by sandwiching and rotating the sheet, and an endless thin body sandwiched between the pressure roller and the heating roller together with the sheet, and the sheet on the outer peripheral surface of the thin body. 2. A fixing device, comprising: a paper adsorbing device for adsorbing the paper, and a paper removing device for removing the paper adsorbed on the outer peripheral surface of the thin body.