JPH0470688A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of warp when a heating element is energized to generate heat by supporting and fixing the heating element at one point to a heating element holder. CONSTITUTION:The heating element 2 is fixed by adhesion to the heating element holder 1 only at one point in the center in the length direction of the holder 1. Therefore, even when the heating element 2 which is energized to generate the heat is thermally expanded, displacement caused by the thermal expansion occurs in a horizontal direction and the warp or the bending of the heating element 2 is not caused. Thus, a wrinkle is prevented from occurring on an endless film 3 which rotates in contact with the heating element 2 and the endless film 3 is prevented from being protrusively folded because the film 3 comes close to the center.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a fixing device installed in an image forming apparatus such as an electrophotographic copying device, and in particular to a fixing device that heats and fixes a toner image on a recording paper via a heat-resistant film. The present invention relates to a fixing device.

[Prior Art] As a heating type fixing device installed in an image forming apparatus such as an electrophotographic copying device, those shown in FIGS. 2 and 3 have been provided. 1 is a heating element holder made of heat-resistant resin, 2 is a heating element, 3 is a heat-resistant endless film, 4 is a driving roller, 5 is a driven roller, 6 is a pressure roller, and between the pressure roller 6 and the heating element 2 An endless film 3 is interposed between the drive roller 4 and the driven roller 5, and the rollers are rotated in the directions of the arrows. The heat from the heating element 2 is transmitted via the endless film 3 to the toner image supported on a recording sheet (not shown) that is transferred between the recording sheet and the pressure roller 6, thereby melting and fixing the toner image. A detection sensor 7 detects the deviation of the film 3 using the film i48.

As shown in FIG. 14, the heating element 2 is bonded to the recess of the heating element boulder 1, and as shown in FIG. The heating element 2 is adhered at multiple points by applying the adhesive to the points.

[Problems to be Solved by the Invention] By the way, in the conventional fixing device, since the heat generating element 2 and the heat generating element holder 1 are bonded at multiple points, as shown in FIG. In the transverse direction, when no current is applied, it is in a normal state as shown by the broken line, but when electricity is applied and heat is generated, warping or bending occurs due to thermal expansion, as shown by the solid line.

This occurs because the heating element 2 and the heating element holder 1, which have different coefficients of linear expansion, are integrated, and if the heating element warps when electricity is applied to generate heat, wrinkles may occur in the endless film that rotates in contact with the heating element. However, the film may be folded in a convex shape near the center, making it impossible to heat the film in a convex manner, which may lead to poor fixing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that can solve these conventional problems and prevent warping when the heating element is energized to generate heat.

[Means for Solving the Problems] An example of a configuration that achieves the object of the present invention is to record information via a heat-resistant sheet member held between a heating element held in a heating element holder and a pressure member. A fixing device that melts and fixes a toner image carried on a sheet, characterized in that the heating element is fixed to the heating element holder by a fixing means provided at one location in the length direction. It is something.

[Function] In the fixing device configured as described above, the heating element is supported and fixed at one point on the heating element holder, so the heating element is not restricted from thermal expansion due to heat generated by electricity, but only extends in the length direction, and does not warp. No bending or bending will occur.

[Example 1] Figures 1 to 5 show Example 1 of the fixing device according to the present invention.
1 is a cross-sectional view taken along the line AA of the fixing device shown in FIG. 2.

In this embodiment, the heating element 2 is fitted into the fitting recess of the heating element holder 1 and bonded, as in the conventional example.
The adhesive 9 applied to the bottom surface 1a of the fitting recess is applied only to one point in the center in the length direction. Furthermore, since the heating element 2 thermally expands due to the heat generated by electricity, a gap is provided in advance between the heating element holder 1 and the heating element holder 1, as shown in FIG. 5, in consideration of the amount of thermal expansion indicated by diagonal lines.

In other words, according to this embodiment, the heating element 2 is fixed to the heating element holder 1 by adhesive bonding only at one point in the center in the longitudinal direction, so that even if the heating element 2 thermally expands due to heat generation due to electricity, Displacement due to thermal expansion occurs in the horizontal direction as shown in FIG. 5, and the heating element 2 does not warp or bend as shown in FIG.

If warping and bending of the heating element 2 is eliminated in this way, it is possible to prevent wrinkles from occurring in the endless film 3 that rotates in contact with the heating element 2, and to prevent the endless film 3 from bending toward the center and into a convex shape. can do. Further, in the bonding process, it is only necessary to apply adhesive at one point near the center, so the process can be shortened and costs can be reduced. Furthermore, since only a small amount of adhesive is required, costs are reduced.

Example 2 Figures 6 and 7 show a second embodiment of the present invention.

In this embodiment, a projection 1b is provided near the longitudinal center of the bottom surface 1a of the heating element holder 1, and the projection 1b is fitted and fixed in a groove 2a provided in the longitudinal center of the heating element 2. . Embodiment 3 It is preferable to provide a loose fit in consideration of thermal expansion. FIGS. 8 and 9 show Embodiment 3 of the present invention.

In this embodiment, contrary to Embodiment 2, the heating element 2 is
A protrusion 2c is provided on the holder 1, and the mounting structure is such that the protrusion 2c is fitted into the groove 2c of the heating element holder 1 at the center as shown in FIG.

Example 4 FIG. 10 shows Example 4.

In the second embodiment described above, the protrusion 1b is provided on the heat generating element holder 1, and this protrusion 1b is fitted into the groove 2a of the heat generating element 2. However, in this embodiment, the temperature detection sensor attached to the heat generating element holder 1 is A working thermistor 10 is provided with a protrusion 10a, and the protrusion 10a passes through the heating element holder 1 and fits into the groove 2a of the heating element 2.

Example 5 FIG. 12 shows Example 5.

In the fourth embodiment described above, the protrusion 10a of the thermistor 10 is fitted into the groove 2a of the heating element 2, but in this embodiment,
The projection 10a is not fitted into the groove 2a, and the projection 10a is not fitted into the groove 2a.
Adhesive is applied to the tip surface of a to secure it in place.

In addition, in the above-described embodiment, in the structure in which the heating element 2 is fixed by a fitting method, an adhesive may also be used for attachment.

[Effects of the Invention] As explained above, according to the present invention, by fixing the heating element to the heating element holder at one point by adhesion or fitting, even if the heating element is deformed due to thermal expansion, it can be prevented from warping. Since there is no bending or bending, it is possible to prevent wrinkles from occurring in the film that rotates in contact with the heating element, and the film from being partially bent and folded into a convex shape.

Furthermore, the cost can be reduced by simplifying the bonding process and reducing the amount of adhesive.

[Brief explanation of the drawing]

1 to 5 show Embodiment 1 of the fixing device according to the present invention, FIG. 3 is a schematic perspective view of the fixing device, FIG. 2 is a front view thereof, and FIG. 1 is A-A in FIG. 2. The sectional view, FIG. 4 is a bottom view of the heating element holder, and the fifth section is a diagram showing the extension of the heating element. 6 and 7 are perspective views and sectional views showing Example 2, FIGS. 8 and 9 are perspective views and sectional views showing Example 3, and FIG. 10 is a sectional view showing Example 4, FIG. 11 is a perspective view of the thermistor, and FIG. 12 is a sectional view showing the fifth embodiment. 13 to 16 show a conventional example, and FIG. 13 is a perspective view showing how the heating element and heating element holder are assembled;
FIG. 4 is an exploded perspective view thereof, FIG. 15 is a diagram showing a state in which adhesive is applied to the heating element holder, and FIG. 16 is a diagram illustrating deformation of the heating element. 1... Heating element holder 2... Heating element 3...
・Endless film 6...Pressure roller 9...
Adhesive and 4 other people

Claims (1)

[Claims] 1. A toner image carried on a recording sheet is melted and fixed via a heat-resistant sheet member held between a heating element held in a heating element holder and a pressure member. A fixing device characterized in that the heating element is fixed to the heating element holder by a fixing means provided at one location in the length direction. 2. Claim 1, wherein the fixing means is an adhesive.
The fixing device described in . 3. The fixing device according to claim 1, wherein the fixing means is of a fitting type.