JPH04313538A - Fixing device - Google Patents

Abstract

PURPOSE:To minimize the occurrence of an influence exercised on a fixed film by regulation, to prevent an unreasonable force from being applied on the film, to perform smooth regulation of the film, and to prevent production of wrinkles by a method wherein the occurrence of the deviation of an endless fixed film during conveyance is regulated in a place located farmost away from a drive part for a film. CONSTITUTION:A rib 3 is formed on the outer periphery of the end on the one side of a fixed film 2. A regulating member 16 regulates rightward movement of the fixed film 2 through interference with the rib 3. A support plate 17 is located in a position facing the regulating member 16 with the film 2 nipped therebetween and supports the fixed film 2 from the inside. When, during conveyance of the fixed film 2, a force exerted in a direction C is applied on the film 2, the rib 3 is collided with the regulating member 16 to effect regulation. Thus, through regulation of the rib 3, a position where aside movement is regulated is a place located farmost away from a drive roller part, a necessary regulation force is minimized, an influence on the fixed film 2 is reduced, and an unreasonable force is prevented from being exerted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a laser beam printer, an electrostatic printer, etc., which records a toner image on a recording sheet.

0002

2. Description of the Related Art Conventionally, as a means for fixing toner images on recording paper, for example, a fixing method using a heat-resistant film is described in Japanese Patent Application Laid-Open No. 63-313182. In this case, a thin endless film is used, and the film is passed between rollers,
Since the film is driven under tension, the film shifts.

In contrast, a method has been proposed, for example, as shown in FIG. 9, in which a rib is provided on at least one end of the fixing film, and the rib is regulated by a regulating member to suppress the shift.

In FIG. 9, 1 is a heating element, 2 is a fixing film, 3 is a rib, 4 is a drive roller, 5 is a tension roller, 6 and 7 are tension roller bearings, 8 and 9 are biasing means, and 10 is a pressure roller. Pressure roller, 11 is a heat insulating member, 12 is a stay,
13 is an entrance guide, 14 is a separation guide, 15 is a paper discharge roller consisting of rollers 15a and 15b, and 18 is a regulating member.

[0005]

However, in the conventional technique shown in FIG. 9, since the regulating member 18 is provided along the outer periphery of the drive roller 4, the fixing film 2 and the rubber layer of the drive roller 4 are Since the regulating surface of the rib 3 is slid onto the regulating member 18 at the part where the constraining force is strong, the regulating force is large and excessive force is easily applied to the rib 3, which may cause damage to the rib 3. Further, when the regulating force becomes large, there is a problem in that the fixing film becomes wrinkled or damaged.

The present invention is an attempt to solve the above-mentioned problems. That is, the present invention minimizes the influence of misalignment regulation on the fixing film, and enables stable misalignment regulation without applying excessive force to the film or causing wrinkles or the like on the film. The object of the present invention is to provide a fixing device.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention fixes an unfixed toner image carried on a recording sheet by heating it through a heat-resistant endless fixing film. , in a fixing device in which the fixing film is driven by a drive unit constituted by at least one roller, a regulating member for regulating deviation of the fixing film during driving is located at a position farthest from the drive unit; It is assumed that it is provided.

[0008]

[Function] According to the present invention, since the shift of the fixing film is controlled at the location farthest from the drive unit of the fixing film,
The influence of the regulation on the fixing film is minimal, no excessive force is applied to the fixing film, wrinkles, etc. can be avoided, and stable deviation regulation can be performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, 1 is a heating element with a low heat capacity, and 2 is a fixing film.

The fixing film 2 is a 20 μm thick film made of a heat-resistant resin such as polyimide, polyetherimide, or PES, and one side of the film is coated with a release layer such as PTFE. The total thickness of the fixing film 2 is generally preferably 50 μm or less.

Reference numeral 3 denotes a rib provided on the outer periphery of one side (front) end of the film 2, and even if it is integrally molded of the same material as the fixing film 2, it may be made of another material with good sliding properties, such as urethane, afterward. It may also be formed by adhering ribs of rubber, silicone rubber, or the like. The fixing film 2 is stretched between a drive roller 4 and a tension roller 5, and together with the heating element 1 forms a film transport path. Further, the fixing film 2 is given tension by urging the tension roller 5 in the direction of arrow A through the tension roller bearings 6 and 7 by the urging means 8 and 9, and is applied with tension in the direction of arrow B by the driving roller 4. transported to.

Here, in order to reliably convey the fixing film 2, the drive roller 4 has a core made of iron or the like and a coating layer of silicone rubber or the like is provided on the surface thereof.

A pressure roller 10 is made of rubber elasticity such as silicone rubber with good release properties, and presses the fixing film 2 against the heating member 1 with the force necessary for fixing. Further, both ends of the pressure roller 10 are supported by bearings (not shown) so as to rotate following the fixing film 2.

The heating element 1 is fixed on a stay 12 having a rigidity sufficient to withstand the pressing force via a heat insulating member 11 made of heat-resistant resin.

13 is an entrance guide for the recording sheet; 14
15 is a separation guide, and 15 is a paper discharge roller consisting of a pair of rollers 15a and 15b.

FIG. 2 is a plan view seen from the direction of arrow D in FIG. 1, and 16 is a regulating member that interferes with the rib 3 to regulate the movement of the fixing film 2 in the right direction in the figure. ,1
A support plate 7 is provided at a position corresponding to the regulating member 16 across the film 2, and supports the fixing film 2 from the inside. The regulating member 16 and the support plate 17 are fixed to a fixing frame (not shown).

By adjusting the biasing forces f1 and f2 by the biasing means 8 and 9, the fixing film 2 is always biased in the direction of arrow C during transportation.

When the fixing film 2 is conveyed, a biasing force acts on the film 2 in the direction of the arrow C, but the ribs 3
It is regulated by colliding with.

Here, as shown in FIG. 3, there is a nip portion E between the heating body and the pressure roller in the film transport path, and a drive roller portion F.
, tension roller part G, deviation amount t for one rotation of the fixing film 2 as shown in FIGS. 4 and 5, and film tension T of the fixing film 2, the position regulating deviation is the drive Regulating force P when regulating deviation at the farthest location from roller part F, and regulating force P at other locations
When comparing ', P is smaller than P' as shown in FIG.

Therefore, in the above structure, the position where the deviation is restricted by regulating the rib 3 is the farthest place from the drive roller part F, so that the regulating force P necessary for regulating the deviation is is minimized, the influence on the fixing film 2 is small, and no unreasonable force is applied, so that the ribs 3 can be smoothly regulated by the regulating member 16 without wrinkles or the like appearing on the fixing film 2.

In this case, at least the surface of the regulating member 16 that slides on the rib 3 is desirably made of a material such as polyacetal or fluororesin that has good sliding properties.

In the configuration shown in FIG. 1, a recording sheet (not shown) passes over the entrance guide 13 and is fed between the fixing film 2 and the pressure roller 10, and the toner image on the recording sheet is transferred to the heating member 1. The recording sheet is heated and melted by heat and pressure from the pressure roller 10, fixed on the recording sheet, and is discharged from the apparatus by the paper discharge roller 15 via the separation guide 14.

As described above, by regulating the rib 3 provided at one end of the fixing film 2 at the farthest point from the drive roller 4, the effect of regulation on the fixing film 2 is minimized, and the rib 3 is Since the regulating member 16 can smoothly regulate the fixing film 2, the fixing film 2 is not wrinkled, and stable deviation regulation can be performed. Further, since the influence of the regulation on the ribs 3 is the least, wear of the ribs 3 and when the ribs 3 are formed by adhesion, it is possible to prevent adhesion peeling, etc., and the durability is greatly improved.

FIG. 6 is a sectional view showing a second embodiment of the present invention. In this second embodiment, ribs 3 are provided on the outer periphery of both ends of the fixing film 2, and the fixing film 2 is moved by the tension roller 5 via the tension roller bearings 6 and 7 by the urging means 8 and 9 to the arrow A. Tension is applied by urging in the direction of arrow B by the drive roller 4.
transported in the direction of

FIG. 7 is a front view seen from the direction of arrow H in FIG.
5. This is a regulation guide as a regulation member provided integrally with 5.

Here, the distance between the regulating surfaces of the regulating guides 25a and 25b is configured to be slightly shorter than the distance between the inner surfaces of the ribs 3 at both ends of the fixing film 2. Further, at least the regulating portions of the ribs 3 of the regulating guides 25a, 25b are desirably made of a material with good sliding properties.

When the fixing film 2 is transported, deviation occurs,
When the film 2 deviates in the direction of the arrow I, the rib 3 is regulated by the regulation guide 25a, and when it deviates in the direction of the arrow J, the rib 3 is regulated by the regulation guide 25b, and the deviation is stopped.

At this time, the regulating position of the rib 3 is the farthest from the drive roller 4, and the regulating force is the smallest, so the influence of regulation on the fixing film 2 is small and no unreasonable force is applied. In addition, since the ribs 3 can be smoothly regulated without wrinkles etc. on the fixing film 2, the ribs 3
Also, the durability of the fixing film 2 is improved.

Furthermore, since the ribs 3 are provided at both ends, it is possible to control even if the fixing film 2 is shifted to either side, so there is no need to perform the complicated process of adjusting the direction of the shift. Furthermore, the upper unit of the film transport path and the pressure roller 10
, the lower unit such as the entrance guide 25 and the separation guide 14,
When assembled as separate units, ease of assembly is greatly improved.

FIG. 8 is a sectional view showing a third embodiment of the present invention. In the figure, 31 is a heating body, and 32 is a fixing film. The fixing film 32 is also a thin endless film in which one side of a heat-resistant resin is coated with a release layer such as PTFE.

Reference numeral 33 denotes a drive roller that also serves as a pressure roller, and has a rubber elastic layer made of silicone rubber or the like having good release properties, and is used to move the fixing film 32 in the direction of arrow K by a pressure means (not shown). It is pressed against the heating body 31 with the force necessary for fixing. 34 is a film guide shaft, and the fixing film 32 is attached to the heating body 31 in a slack state to the extent that no tension is applied.
and the film guide shaft 34, forming a film transport path. The heating body 31 is fixed on a stay 36 having a rigidity that can withstand the pressing force via a heat insulating member 35 made of heat-resistant resin. Further, 37 is an entrance guide, 38 is a separation guide, 39 is a roller 39a,
39b.

9 and 10 are front views seen from the direction of arrow L in FIG. 8. FIG. As shown in FIG. 9, reference numerals 40 and 41 are regulation guides for regulating the ends of the film 32, respectively, and are rotatable at both ends of the film guide shaft 34 with an interval slightly longer than the width of the fixing film 32. installed on.

In the configuration shown in FIG. 8, the drive roller 33
When the fixing film 32 rotates in the direction of the arrow M, the fixing film 32 is conveyed in the direction of the arrow N due to the pressure applied to the heating body 31 . As shown in FIG. 9, the regulation guides 40 and 41 have a diameter that increases toward the outside, and when the fixing film 32 is conveyed, deviation occurs, and the fixing film 3 is moved in the direction of the arrow O.
2 is displaced and comes into contact with the regulation guide 40, the regulation guide 40 rotates together with the film 32 as shown in FIG. 10, and the deviation stops in equilibrium. At this time, since the regulating position of the film 32 is the farthest from the driving part of the drive roller 33, the regulating force is the smallest, the influence of regulation on the fixing film 32 is the least, and unreasonable force is not applied. Therefore, the film 32 can be smoothly regulated without wrinkles or the like appearing on the film 32. Similarly, if the shift direction is arrow Q in FIG.
It is regulated by the regulation guide 41.

Here, it is desirable that at least the portions of the regulation guides 40 and 41 that regulate the fixing film 32 be made of a material with good sliding properties.

As described above, even when the outer periphery of the fixing film 32 is driven by the drive roller 33, by regulating the fixing film 32 at the farthest point from the drive unit, the effect of regulation on the fixing film 32 can be minimized. Fixing film 3
2 can be smoothly regulated, and the durability of the fixing film 32 is improved.

Further, in the above structure, the fixing film 3
Since the number of rollers for driving the fixing device 2 can be significantly reduced, the size of the fixing device can be reduced and ease of assembly can be improved. Moreover, since the fixing film 32 is driven without applying tension, the driving torque of the fixing device is significantly reduced, so that versatility can be expanded.

[0037]

[Effects of the Invention] As explained above, according to the present invention,
Since shifting of the endless fixing film during transport is controlled at the farthest point from the drive unit of the film, the effect of regulation on the fixing film is minimized, and no excessive force is applied to the film, allowing the film to be It can be regulated smoothly and has the effect of improving the durability of the film.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view seen from the direction of arrow D in FIG. 1;

FIG. 3 is an explanatory diagram of a fixing film regulation location.

FIG. 4 is an explanatory diagram of the regulating force depending on the regulating location of the fixing film.

[Figure 5] Another regulation force depending on the regulation location of the fixing film
FIG.

FIG. 6 is a sectional view showing a second embodiment of the present invention.

7 is a front view seen from the direction of arrow H in FIG. 6. FIG.

FIG. 8 is a sectional view showing a third embodiment of the present invention.

9 is a front view of one state seen from the direction of arrow L in FIG. 8. FIG.

10 is a front view of another state seen from the direction of arrow L in FIG. 8. FIG.

FIG. 11 is a sectional view showing an example of a conventional technique.

[Explanation of symbols]

Claims (2)

[Claims] 1. An unfixed toner image carried on a recording sheet via a heat-resistant endless fixing film is heated and melted to fix it, and the fixing film is composed of at least one or more rollers. A fixing device driven by a drive section, wherein a regulating member for regulating shifting of the fixing film during driving is provided at a position farthest from the drive section. 2. The fixing device according to claim 1, wherein the fixing film has a rib in the circumferential direction at least on one end thereof, and the regulating member regulates the rib.