JPH0675490A - Fixing device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To prevent curling of paper and to prevent sticking of a preceeding sheet to the following sheet when lots of sheets are printed, by passing a sheet having a molten toner by heating through a pair of cooling rollers and then cooling these cooling rolers with a fan. CONSTITUTION:A paper sheet 1 carrying a toner in the image transferred from a photosensitive body is passed through between a heat roller 2 and a pressure roller 3 where the toner is molten by heating with the heat roller heated by a heater lamp 4. During this process, the toner is also pressed by the pressure roller 3, so that the molten toner permeates in the fiber of the paper 1 and is fixed. After completion of fixing, the paper sheet 1 is discharged by rotation of the heat roller 2 and the pressure roller 3 and passed between the cooling rollers 5, 6 facing to each other cooled by a fan 7. Thereby, the paper sheet 1 is discharged in a state with solidified toner and no temp. difference between the front and rear surfaces.

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 printer, and more particularly to an electrophotographic printer in which a toner transferred onto a sheet is melted and fixed by a heat roller having a heater lamp at its center. Fixing device.

[0002]

2. Description of the Related Art Among fixing devices for a conventional electrophotographic printer, a fixing device for an electrophotographic printer that melts and fixes toner transferred onto a sheet by a heat roller having a heater lamp in its center is known. A method is employed in which a pressure roller provided opposite to the heat roller presses the paper against the heat roller, and the toner melted by the heat roller is permeated into the fibers of the paper and fixed.

[0003]

In the conventional fixing device of the electrophotographic printer as described above, when the paper passes between the heat roller and the pressure roller, heat is applied only from the heat roller, and therefore the paper is heated. There is a drawback that a temperature difference occurs between the front and back sides, which causes curling. Further, since the melted toner is discharged before it is completely solidified, there is a problem in that when a large number of sheets are continuously printed, the preceding paper may adhere to the following paper. .

[0004]

A fixing device for an electrophotographic printer according to the present invention includes a heat roller having a heater lamp at its center for melting and fixing toner transferred onto a sheet, and a heat roller for the heat roller. A pressure roller that presses the sheet of paper, a cooling roller that cools the sheet of paper that has passed between the heat roller and the pressure roller, and a fan that flows air to the cooling roller to cool the sheet of paper.

[0005]

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

FIG. 1 is a front view showing an embodiment of the present invention.

The fixing device shown in FIG. 1 has a heater lamp 4 in the center thereof, and a heat roller 2 which is heated by the heater lamp 4 is provided so as to face the heat roller 2 and is sandwiched between the heat roller 2. And a pressure roller 3 for fixing the toner on the printing paper by applying a predetermined pressure to the printing paper 1.

The sheet 1 bears the toner of the image transferred from the photoconductor (not shown), and is heated by the heater lamp 4 when passing between the heat roller 2 and the pressure roller 3. The toner is melted by being heated by 2. At this time, since pressure is applied by the pressure roller 3, the melted toner penetrates into the fibers of the paper 1 and is fixed.

The sheet 1 which has been fixed has a heat roller 2
Also, the pressure roller 3 is discharged by the rotation of the pressure roller 3, and passes between the cooling roller 5 and the cooling lower roller 6 provided opposite to each other. The cooling roller 5 and the cooling lower roller 6 are
It is made of a material that is hollow and has good thermal conductivity.
It is cooled by the fan 7. Therefore, when the sheet 1 passes between the cooling roller 5 and the cooling lower roller 6,
They are cooled and the temperature difference between the front and back is eliminated, and the toner is discharged in a solid state.

[0010]

As described above, in the fixing device of the electrophotographic printer of the present invention, the paper which is heated by the heat roller and melts the toner is passed between the pair of cooling rollers, and the pair of cooling rollers is passed. By cooling the cooling roller with a fan, there is an effect that the temperature difference between the front side and the back side of the paper after fixing can be eliminated, and curling can be prevented, and the paper is ejected with the toner solidified. Therefore, even when printing a large number of sheets in succession,
There is an effect that it is possible to prevent the phenomenon that the front sheet adheres to the latter sheet.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Paper 2 Heat Roller 3 Pressure Roller 4 Heater Lamp 5 Cooling Roller 6 Cooling Lower Roller 7 Fan

Claims (1)

[Claims] 1. A heat roller having a heater lamp at its center for melting and fixing toner transferred onto a sheet, a pressure roller for pressing the sheet against the heat roller, the heat roller and the pressure. A fixing device for an electrophotographic printer, comprising: a cooling roller for cooling the sheet that has passed between the rollers; and a fan for flowing air to the cooling roller to cool the sheet.