JPH0235313B2 - TEICHAKUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for fixing a toner image on a support material under pressure by transporting the toner image support material under pressure by a pair of fixing rollers.

Conventionally, the heat chamber method was used as the fixing method.
Heat fixing methods such as a flash fixing method and a heat roller method, and a pressure fixing method have been proposed.

The heat fixing method melts and fixes the toner by heating the toner image, and the pressure fixing method uses pressure applied between a pair of fixing rollers to press the toner. The pressure fixing method has attracted particular attention in recent years because it does not require heat, so there is no so-called wait time unlike the heated roller method, in which the roller cannot be used until the temperature rises to a required temperature, and there is no risk of fire.

However, in the case of the pressure fixing method, pressure is applied on the side plate by air pressure or spring pressure, so if the transfer material is passed between the rollers at a position that is symmetrical in the longitudinal direction of the rollers, the rollers will be tilted and the transfer material This has the disadvantage that pressure is not uniformly applied to the image forming apparatus, resulting in areas of high pressure and areas of low pressure, resulting in poor fixing.

Therefore, in the case of a pressure fixing method, the pressure applied to the entire body is generally very large in order to obtain the necessary fixing pressure even in areas with low pressure, or when the transfer material has various sizes, the center of the roller is always applied. It was necessary to design it so that it could pass through. However, in the former case, the durability and pressure resistance of the device are increased, making the device larger and heavier, and in the latter case, after the toner image is transferred from the photoreceptor to the transfer material, the transfer material is removed from the photoreceptor. In order to separate the transfer material, measures must be taken such as charging the transfer material using corona discharge, etc., or gripping the leading edge of the transfer material with a grip to ensure reliable conveyance. This has the disadvantage that it becomes difficult to adopt the method, leading to increased costs and complexity of the device.

SUMMARY OF THE INVENTION The present invention aims to eliminate the drawbacks of the prior art as described above and to provide a pressure fixing device that can apply uniform pressure to a transfer material using a simple method.

That is, the present invention provides a member that maintains the gap between a pair of rollers within a certain amount at the pressure-applied portions at both ends of the fixing device, thereby simplifying the device without making it larger or more complicated. The present invention aims to provide a pressure fixing device that can utilize a one-sided separation method.

A pressure fixing device according to the present invention includes a pair of fixing rollers and a pressure applying means for applying pressure between the pair of fixing rollers, and a support member that supports a toner image with this pair of fixing rollers is set with reference to one end side. A fixing device that fixes a toner image by nipping and conveying the toner image, characterized by having a regulating member on the reference side of one side, separate from the pressing means, for regulating the spread of the distance between the axes of the pair of fixing rollers. It is something.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 schematically shows an example of an electrophotographic apparatus to which the present invention can be applied. In the figure, 1 is a photoreceptor whose surface has a photoconductive layer and an insulating layer, 2 and 3 are chargers,
Reference numeral 4 indicates an image exposure section, 5 a full-surface exposure lamp, 6 a developing device, 7 a transfer charger, 8 a separation means, 9 a cleaner, and 10 a fixing device. The photoreceptor 1, which has a photoconductive layer and an insulating layer on its surface, rotates as shown by the arrow in the figure, and is subjected to image exposure by the chargers 2, 3 and the image exposure section 4, and full-surface exposure by the lamp 5. The developing device 6 performs development with the latent image on the surface.

The toner image adhered on the photoreceptor by the development is transferred onto the transfer material P by the transfer charger 7.

The transfer material P having the toner image is separated from the photoreceptor 1 by the separating means 8, and the toner image on the transfer material is fixed to the transfer material by the fixing device 10. Note that the toner remaining on the photoreceptor 1 after transfer is removed by a cleaner 9.
Cleaned by.

The above explanation shows the case where latent image formation is performed by a method well known as the NP method.
This may be a Carlson process or any other similar process. It may also be a method such as EF, a belt-shaped photoreceptor, a magnetic latent image method, or anything that provides a toner image that can be fixed on the transfer material P by pressure. It can be applied to the present invention.

FIG. 2 shows a pressure fixing device to which the present invention can be applied. As shown, the fixing device 10 has two pressure fixing rollers 11, 12, which are connected to side plates 13, 14 through bearings at their ends.
is supported by. The side plates 13 and 14 at both ends of these rollers are connected so that they can rotate with respect to the fulcrum 0, and the ends opposite to the fulcrum 0 are connected by bolts 15, and are arranged around the gilt 15. The side plates 13 and 14 are attracted to each other by a spring 16, and the rollers 11 and 12 are pressed against each other. As the transfer material P passes through the two rollers 11 and 12 that are pressed against each other, the toner on the transfer material P is fixed under pressure.

FIG. 3 is an explanatory diagram showing the distribution of pressure applied to the transfer material sandwiched between the two rollers 11 and 12. A is the case where there is no transfer material. b shows the transfer material passing through an axially symmetrical portion of the roller, and the pressure distribution is almost uniform as shown in b'. c shows how the transfer material passes through an axially asymmetrical position of the roller. As for the pressure distribution, since the roller is tilted, excessive pressure is applied to the central part of the transfer material in the axial direction of the roller, and conversely, the roller floats at the end of the roller axis, and the necessary pressure is not applied and the pressure distribution is c′ The result will be unevenness as shown in the figure.

The present invention prevents the roller from tilting when the transfer material passes through an axially asymmetric position of the roller, as shown in FIG. 3c, resulting in an uneven pressure distribution as shown in FIG. 3c'. This invention is characterized in that it is provided with a fixing roller over-inclination prevention mechanism for this purpose.

FIG. 4 shows an embodiment of the invention. In this embodiment, the roller over-inclination prevention mechanism consists of inter-roller gap holding members X provided at both ends of the roller. In this embodiment, the inter-roller gap holding member X has side plates 13 and 1 as shown in FIG.
The rollers 1 and 4 are arranged so that the distance between the side plates 13 and 14 that support the upper roller 11 and the lower roller 12, respectively, is kept to a certain distance or less by sandwiching the ends of the rollers 11 and 12. The arrangement of the roller gap holding member X is not limited to the position shown in the embodiment, and may be selected so as to reduce the load on the roller gap holding member X and facilitate gap adjustment. The upper and lower legs of the gap holding member This is to correct uneven pressure applied to the transfer material.

FIG. 4b schematically shows the effect of the gap holding member X in preventing excessive roller inclination, and FIG. 4b' shows how uneven pressure has been corrected.

If the thickness and width of the transfer material are different, the pressure distribution applied to the transfer material can be made uniform by adjusting the gap y between the upper and lower legs of the gap holding member X or by replacing it with an appropriate member. It becomes possible to

FIG. 4a' shows a modified example in which the gap y of the gap holding member X can be adjusted. Gap y
can be adjusted.

FIG. 5 shows another embodiment of the invention. In this embodiment, the roller over-inclination prevention mechanism consists of a resilient member provided at the end of the roller. That is,
Fig. 5 shows a roller excessive inclination prevention mechanism X that uses a resilient member 19 such as a spring or an elastic body. This prevents the defect that one end of the shaft in the axial direction rises excessively. This makes it possible to obtain a uniform pressure as shown in FIG. 5b'.

As mentioned above, by using an elastic member as the roller over-inclination prevention mechanism . It is also effective in preventing shocks when paper enters.

FIG. 6 shows yet another embodiment of the invention.
In this embodiment, the fixing roller over-inclination prevention mechanism consists of two or more pressure rolls 20, 20', 20'', etc., which are arranged in parallel in the axial direction of the fixing roller and can act independently of each other. Become.

In this embodiment, between two fixing rollers 11,1
The pressure applied to the pressure roller 2 is applied by three or more pressure rolls 20, 20', 20'', etc. that can be operated independently. When the transfer material is wide, all the pressure rolls (20, 20', 20'' in the figure) '') applies pressure between the fixing rollers, and if the width of the transfer material is narrow and the paper is passed unevenly in the axial direction of the fixing roller, pressure is applied by the necessary number of pressure rolls corresponding to the width of the transfer material. It is done. Therefore, even if the width or thickness of the transfer material changes, it is possible to apply uniform pressure to the transfer material without always tilting the fixing roller. In addition, by dividing the pressure member into multiple parts in this way, there is no problem of roller deflection that occurs when pressure is applied to both ends of the fixing roller, and pressure can be applied to the transfer material in a more uniform distribution. .

In the embodiment shown in FIG. 6, one fixing roller is divided into two or more parts, and the pressure rolls 20, 2
Fixing rollers 11, 12 independently by 0', 20''...
pressure can be applied between them.

By providing the pressure mechanism described above, when the width of the transfer material is wide, all the fixing rollers perform the fixing, and when the width of the transfer material is narrow, pressure is applied between the fixing rollers using the required number of pressure rolls. ,
Even when the width and thickness of the transfer material changes, fixing with uniform pressure distribution can be performed without always tilting the fixing roller. Further, by dividing the roller in this manner, the total pressure applied to one roller can be reduced, and the weight of the fixing roller can be reduced.

In the above fixing device, when the width of the transfer material becomes narrow, the pressure in the roller axial direction is increased by increasing the spring pressure, for example, by tightening the bolt 15 holding the spring 16 on the side where the roller floats. It is possible to change the distribution and adjust the pressure distribution to be uniform during paper passing. By attaching a handle or the like to the head of the bolt used for this adjustment, the operation becomes easier.

As explained above, by providing an over-inclination prevention mechanism for the pressure fixing roller, the present invention makes it possible to adopt a one-sided separation method without complicating the device, and when the width of the transfer material changes. To provide a pressure fixing device that can fully cope with the above.

[Brief explanation of drawings]

Figure 1 is a schematic illustration of an electrophotographic device, Figure 2 is an illustration of a fixing device, and Figures 3 a, b, b', c, and c' are pressure applied to a transfer material by a general fixing device. FIG. 4a is a side view showing one embodiment of the present invention, FIG. 4a' is a partial view showing a modification thereof, and FIG. 4b is an explanation of the effect of the roller over-inclination prevention mechanism. 4b' is a diagram showing the pressure distribution of the roller, FIG. 5a is a side view showing another embodiment of the present invention, and FIG. 5b is a diagram showing the effect of the roller over-inclination prevention mechanism. 5b' is a diagram showing the pressure distribution of the roller, FIG. 6a is a front view showing still another embodiment of the present invention, and FIG. 6b is a diagram showing the effect of the roller over-inclination prevention mechanism. FIG. 1... Photoreceptor, 2, 3... Charger, 4... Image exposure section,
5...Full surface exposure lamp, 6...Developer, 7...Transfer charger, 8...Separation means, 9...Cleaner, 10...Fixing device, 11, 12...Fixing roller, 13, 14...Side plate, 15...Gilt, 16... Spring, 17... bolts,
18...Nut, 19...Elastic member, 20, 20',
20″...pressure roll.

Claims (1)

[Scope of Claims] 1. A pair of fixing rollers, and a pressure means for applying pressure between the pair of fixing rollers, and a supporting member that supports a toner image with the pair of fixing rollers, with one end side as a reference. A fixing device that fixes a toner image by pinching and transporting the toner image, the fixing device having a regulating member on the reference side of one side, separate from the pressure means, for regulating the spread of the distance between the axes of the pair of fixing rollers. Device.