JPH028301Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a hot plate type drying and fixing device.

Prior Art A conventional hot plate drying and fixing device, for example, a fixing device for a wet type electrophotographic copying machine, is equipped with a hot plate and a guide roller that applies a conveyance force to the copy paper and strikes the transfer paper against the hot plate. However, copy paper is heated only by contact with a hot plate, and in order to achieve sufficient heating, it is necessary to increase the length of contact with the hot plate, which poses the problem of taking up more space. Ta. Even if the guide rollers are actively heated in an attempt to compensate for the insufficient heating by the hot plate, the copy paper only comes into contact with the guide rollers momentarily, so there is no direct heat conduction from the guide rollers to the copy paper. Since there is only a slight amount of heat transfer through the air, it was not possible to dramatically improve the fixing performance.

If the copy paper is brought into contact with the guide roller, the guide roller will be smeared with toner from the copy paper, and the rotation of the guide roller will re-offset the dirt on the guide roller onto the copy paper that carries the image, causing duplication. There was a problem that the image quality deteriorated.

Purpose The present invention aims to eliminate the above-mentioned drawbacks of the conventional hot plate type drying and fixing device, and to provide a hot plate type drying and fixing device that can reliably heat and dry and fix copy paper during a short conveyance distance. The purpose is

Configuration The configuration of the present invention that achieves the above object will be explained in detail with reference to embodiments shown in the drawings.

In FIG. 1, a copy paper, for example, a transfer paper on which a photoreceptor 1 has been transferred, is separated from the photoreceptor 1 by a turn roller 2, guided to a conveyance guide plate 3, and sent to a fixing device.

The fixing device includes a pair of inlet rollers 4, a guide roller 5 that contacts the copy paper fed by the pair of inlet rollers 4 and feeds the copy paper, and a heat roller that contacts and guides the copy paper fed by the guide roller 5 and heats it. Board 6
A heat source 7, such as a sheathed heater, installed in the hot plate 6 to heat the hot plate 6; It has a cleaning roller 8 for cleaning toner stains on the surface. A cleaning roller 11 for removing toner stains is arranged in contact with the outlet roller pair 9.

The copy paper discharged from the pair of exit rollers 9 of the fixing device is stored in a tray 10.

As shown in FIGS. 2 and 3, the hot plate 6 of the fixing device, that is, the hot plate type drying and fixing device
The portion between the roller pair 9 and the pair of exit rollers 9 is formed as a curved surface so that the side that contacts the copy paper is convex, and is a tangential plane that passes through the nip point (contact point) of the pair of exit rollers 9 and contacts the guide roller 5. The curved surface is arranged such that a part of the curved surface protrudes toward the guide roller 5 side.

The inlet roller pair 4 is arranged at a position shifted from the tangential plane P to the guide roller 5 side. Due to the above-described arrangement of the inlet roller pair 4, guide roller 5, and hot plate 6, the copy paper 12 has an arc angle θ as shown in FIG.
It comes into contact with the surface of the guide roller 5 in a wound state within a range of . Further, due to the above arrangement of the guide roller 5, the hot plate 6, and the pair of outlet rollers 9, the copy paper 12 is pressed against the convex curved surface of the hot plate 6 by the tensile force of the pair of outlet rollers 9.

Therefore, by heating the guide roller 5 and heating the hot plate 6, the copy paper 12 is moved to the guide roller 5.
The evaporation of the copying solvent on the copy paper is strengthened by the conduction heat from the copy paper and the improvement in the heat transfer effect due to the enhanced degree of contact by the hot plate 7, thereby promoting fixing. In particular, since the image surface of the copy paper is wrapped around the guide roller 5, the image surface is directly heated, thereby improving fixing performance.

Since the image surface of the copy paper comes into contact with the guide roller 5, the toner on the copy paper is offset to the guide roller 5, and as the guide roller 5 rotates, it is again offset onto the copy paper, degrading the copy quality. To prevent this, a cleaning roller 8 is brought into contact with the guide roller 5 to remove the toner adhering to the guide roller 5.

By bringing the cleaning roller 8 into contact with the pair of inlet rollers 4 as well, toner stains on the pair of inlet rollers 4 can be cleaned.

When heating the guide roller 5, as shown in FIG. 4 and FIG. Guide roller 5 transfers heat from the hot plate
It can be made to conduct to In this case, if the hot plate 6 is formed with an arcuate curved surface that just contacts the large diameter portion 5a, the heat transfer effect will be great.

Furthermore, as shown in FIG. 6, a structure may be adopted in which a heat source 13, such as a halogen lamp or a sheathed heater, is disposed in the hollow portion of the guide roller 5. Further, a structure in which a planar heater is arranged on the surface of the guide roller 5 may also be used.

In the examples shown in Figures 4 and 6, the guide roller is made of a material with good thermal conductivity, such as metal, and is dimensioned to reduce the heat capacity of the guide roller in order to improve the rise characteristics during heating. Considering the shape, etc., thermal efficiency is good and good fixing performance can be obtained.

Effects This invention increases the adhesion area of the copy paper to the guide roller and improves its adhesion to the hot plate, which improves heating properties.Furthermore, the image surface of the copy paper is directly heated by the guide roller, improving fixing performance. will improve.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a part of a copying machine using a thermal fixing device according to the present invention, FIG. 2 is an enlarged explanatory diagram of the fixing device portion, and FIG. 3 is a diagram showing the relationship between guide rollers and copy paper. , FIG. 4 is a perspective view of an example of the guide roller, FIG. 5 is a front view of FIG. 4, and FIG. 6 is a sectional view of another example of the guide roller. 4... Entrance roller pair, 5... Guide roller, 6...
...heat plate, 7...heat source, 8...cleaning roller, 9...exit roller pair.

Claims (1)

[Scope of utility model registration request] In a hot plate type drying and fixing device having a pair of inlet rollers, a guide roller, a heat source and a heated hot plate and a pair of outlet rollers, at least a part of the hot plate is formed as a convex curved surface on the copy paper contact surface side. and a part of the curved portion of the hot plate is arranged so as to protrude toward the guide roller from a tangential plane that passes through the contact point of the pair of exit rollers and touches the guide roller;
A hot plate type drying and fixing device, characterized in that the pair of inlet rollers are disposed offset from the tangential plane toward the guide roller, and the guide roller is heated by heating means.