JPS6350668Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an electrostatic transfer type electrophotographic copying machine that fixes toner images by applying pressure and heat using a pair of rollers to copy paper that can carry a toner image. The present invention relates to a fixing device.

Conventionally, in the fixing device of an electrostatic transfer type electrophotographic copying machine, two heated rollers (a pair) are pressed against each other with a predetermined pressing force, and a paper (hereinafter referred to as Pressure/heating methods are often used in which fixing is performed by passing a copy paper (this is called a copy paper). However, this type of fixing device has a problem in that wrinkles parallel to the traveling direction of the copy paper are likely to occur. Particularly in wide or vertical copy paper, several lines of wrinkles sometimes appeared.

There are many possible causes for the wrinkles mentioned above, but one of the biggest causes is that the copy paper just before it enters between the two rollers is not guided, so the leading edge of the copy paper is wavy. One example of this is that it becomes shaped and loses its linear flatness.

The second reason is that the two rollers are configured to press against each other by applying pressure to both ends of the rollers, so the pressure contact force at both ends of the rollers is high, and the center part of the rollers is curved slightly lower. It becomes a state. Therefore, the nip width formed by the contact between the two rollers is non-uniform in the axial direction of the rollers, resulting in heat shrinkage of the copy paper or non-uniform feeding speed.

In order to eliminate the above causes, conventional measures have been taken as shown in FIGS. 1 and 2.

That is, in FIG. 1, as a measure to eliminate the first cause, a flat guide member 3 is disposed on the paper feeding side of the heating roller 1 and the pressure roller 2, for example, close to the abdomen of the heating roller 1. By doing this, the copy paper 4 being sent in the direction of the arrow is curved in the direction between the rollers 1 and 2 by the pair of rollers 1 and 2 and by the guide member 3 over a short distance with a small radius of curvature. The curved portion has rigidity, and the tip side also maintains linear flatness rather than wavy shape, which is effective in eliminating the first cause.

However, even with this structure, since the nip width in the axial direction of the rollers is uneven, the amount of heat applied to the copy paper passing between the rollers is uneven, so if the copy paper contains a lot of moisture, When the paper passes between the heating roller 1 and the pressure roller 2, moisture evaporates unevenly due to heating, so that wrinkles may occur partially due to the difference in shrinkage of the paper.

In addition, Fig. 2 shows, as a countermeasure for the second cause,
As shown in the figure, the core member 6 of the heating roller 5 is tapered so that the outer diameter at both ends becomes gradually smaller than the outer diameter at the center, and an elastic body 7 such as silicone rubber is attached to the outer periphery so that the outer diameter is uniform. It was installed so that In this way, when the copy paper passes between the heating roller 5 and the pressure roller 8 which are in pressure contact with each other, an acting force is applied that pulls the copy paper in the length direction of the roller shaft, that is, toward both ends, thereby preventing wrinkles.
This has the advantage that it is less likely to occur, but on the other hand, since the roller has a special structure, there is a problem that it requires time and effort in manufacturing and processing and increases costs.

This invention has a simple structure that prevents the occurrence of wrinkles as much as possible without requiring a special roller structure.
Furthermore, the present invention aims to provide a heat fixing device that can be realized at low cost. Another object of the present invention is to provide a heat fixing device that allows fine adjustment of the vertical displacement of the guide member.

Hereinafter, the present invention will be explained based on the illustrated embodiments. FIG. 3 is a side sectional view of one embodiment of the present invention.

In the figure, 9 is a heating roller that is rotated in the direction of arrow A by a drive device (not shown), and this roller is made of a heat-resistant material with good mold releasability, such as a fluoride resin, on the outer periphery of a cylindrical metal core 10. 25~40μ of resin 11
It is coated uniformly with a certain layer thickness, and a heating source 12 such as a halogen lamp is provided inside.

Reference numeral 13 denotes a pressure roller rotatably disposed below the heating roller 9 so as to press against it along the longitudinal direction of the heating roller 9. It is rotated following the direction of arrow B.

This pressure roller 13 has a heat-resistant elastic member 1 such as silicone rubber on the outer periphery of a cylindrical metal core 14.
5 is uniformly installed with a required layer thickness.

Reference numeral 16 denotes a guide member that constitutes the main part of the present invention, and this guide member guides the copy paper 17, which is fed from the right side and is capable of carrying an unfixed toner powder image, to enter between the heating roller 9 and the pressure roller 13. The rollers are arranged near the paper feeding side of the pair of rollers.

Note that 18 and 19 are fixing members and set screws for fixing the guide member 16.

The guide member 16 is a rectangular plate made of aluminum or the like, as shown in FIG.
The upper center plate part 16a, which is bent into a letter shape and constitutes the upper plate part, has a small area and is made higher than the wide area plate parts 16b and 16c located on both sides thereof, and is made as shown by the arrow F.
It is formed to have a substantially convex shape (or chevron shape) when viewed from the direction.

That is, the plate portions 16a and 16c are bent downward and have a gently tapered shape. Further, the plate portion 16e between the upper plate portion and the lower plate portion 16d, including the upper center plate portion 16a and the plate portions 16b and 16c, is a gently sloped surface rising to the left when viewed in FIG. The lower surface of the copy paper 17 comes into contact with this surface portion and the upper plate portion.

Further, holes 20a, 20 for inserting the set screws 19 are provided on both sides of the lower plate portion 16d extending downward.
b is drilled.

As shown in the figure, the fixing member 18 is formed by bending plate-like pieces 18a and 18b at both ends upward, and the tip of a screw 21 serving as a height adjusting member is screwed into a part of the fixing member 18. The height of the upper center plate part 16a can be adjusted by abutting the center part of the lower plate part 16d and adjusting the amount of deformation (indentation amount) of the lower plate part 16d due to the pressurization.

That is, when the center part of the lower plate part 16d of the guide member 16 is pressurized with the screw 21, since both ends are fixed to the fixing member 18, the inclined surface 16 configuring the upper plate part
A denting force acts near the bent portion e, and the upper center plate portion 16a is displaced upward by the reaction. Therefore, the pressure of the screw 21 is applied to the lower plate part 1.
6d, the upper central plate portion 16a is displaced downward.

In the above configuration, when the copy paper 17 carrying a toner powder image on its surface (upper surface) is conveyed from the right side in FIG. The copy paper 17 is fed along the inclined surface of the plate section 16e, and the center portion of the tip of the copy paper 17 is guided by the upper center plate portion 16a, and the portions on both sides of the tip of the copy paper 17 are guided by the plate portions 16b and 16c, respectively. It is in an upward convex curved state.

When the copy paper 17 is further fed, the central portion of the tip of the copy paper 17 first comes into contact with the surface of the upper heating roller 9, and as the copy paper 17 rotates, it is sandwiched between the heating roller 9 and the pressure roller 13. go.

In this case, both sides of the leading edge of the copy paper 17 also come into contact with the heating roller 9 one after another and are sandwiched between the two rollers, so that the copy paper 17 passes between the rollers in a taut state from the center to both sides. As a result, the toner powder image is fixed on the copy paper 17 without wrinkles by the heating and pressing action of both rollers.

In this embodiment, the guide member 16 is made of an aluminum plate with a thickness of 1.2 mm, the width of which is 360 mm, the length of the central portion of the plate portion 16e serving as a guide surface in the copy paper traveling direction is 40 mm, and the lower part is 360 mm. When the height of the plate part 16d is 56 mm, the lower plate part 16 is fixed by the screw 21.
If the amount of dent in d is 4 mm, the upper center plate part 16
a could be displaced upward by 2 mm, and no wrinkles were observed at copy paper conveyance speeds of 100 mm/sec to 200 mm/sec.

Here, the guide member 16 is a roller whose leading end of the copy paper 17 guided by it is on the upper side.
That is, the inclination angle and fixed position of the upper plate part are set so as to contact the heating roller 9.

For this purpose, it is effective to make the holes 20a and 20b into elongated holes so that the guide member 16 can be adjusted up and down.

FIG. 5 is a perspective view of a main part showing another embodiment in which a cam 22 is used as the height adjusting member.

When the nut 23 is loosened, the cam 22 will come out with the screw 24.
The lower plate portion 16d is recessed by a predetermined amount and is fixed by tightening the nut 23. With this configuration as well, the same effects as described above can be obtained.

As is clear from the above description, the present invention does not require a special roller structure, but instead provides a guide for copying paper between a heating roller and a pressure roller, the upper center of which is higher than the plate portions located on both sides. It guides the member while maintaining the rigidity of an upwardly curved convex shape, and prevents both sides of the copy paper from moving toward the center when viewed from the conveying direction. By pressing the lower center part with an adjustment member, the vertical displacement of the upper center part can be finely adjusted, making individual adjustments extremely easy and effectively eliminating wrinkles in the copy paper. It has the excellent feature of being able to perform the following tasks, and its practical value is extremely great.

[Brief explanation of the drawing]

Fig. 1 is a side view of the main part of the conventional example, Fig. 2 is a sectional view of the main part of another conventional example, Fig. 3 is a side sectional view of an embodiment of the present invention, and Fig. 4 is a side view of the main part of the conventional example. FIG. 5 is a perspective view of a main part of another embodiment of the present invention. 9... Heating roller, 10... Metal core, 11...
...Heat-resistant resin, 12... Heat source, 13... Pressure roller, 14... Metal core, 15... Heat-resistant elastic member, 16... Guide member, 16a... Upper center plate portion, 16b, 16c... ...Plate part, 16d...Lower plate part, 16e...Plate part, 17...Copy paper, 18...
Fixing member, 19, 21... screw, 22... cam.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A pair of rollers rotatably disposed facing each other in order to apply pressure and heat to fix a copy paper that can carry a toner powder image, and between the pair of rollers. The roller is disposed near the abdomen of one of the pair of rollers in order to guide the unfixed copy paper, and the upper center part where the copy paper comes into contact has a gentle taper located on both sides of the roller. The guide member has an inverted L-shaped cross section and is made up of an upper plate part that is higher than the plate part that is attached and bent downward, and a lower plate part that extends downward, and the plate pieces at both ends are bent upward. a fixing member that is curved and fixes both sides of the lower plate portion of the guide member; and a fixing member that contacts the center portion of the lower plate portion of the guide member and presses and deforms that portion to increase the height of the upper center portion of the guide member. A heat fixing device for an electrophotographic copying machine, comprising a height adjusting member capable of displacing a height adjusting member. (2) A heat fixing device for an electrophotographic copying machine according to claim 1, wherein the guide member is vertically adjustable with respect to the fixed member.