JPS5838787B2 - Fukushiyakino Kamiokuri Souchi - Google Patents

Description

[Detailed description of the invention] The present invention relates to a paper feeding device for a copying machine.

Paper feeding devices for copying machines include those that simply transport paper and those that perform some processing on the paper being fed.

An example of the latter is a fixing device that heats and fuses a toner image formed on paper.

Referring to FIG. 1, a fixing device using a pair of rollers will be described.

In the figure, reference numeral 1 indicates a fixing roller, and reference numeral 2 indicates a pressure roller.

The fixing roller 1 consists of a cored metal roller 3, a Teflon layer 4 formed on the outer periphery of the core roller 3, and a heater 5, and an anti-offset liquid 7 is supplied and applied to the surface of the roller by a web 6.

The pressure roller 2 is brought into pressure contact with the fixing roller 1 by an appropriate means (not shown).

The rollers 1 and 2 are so-called straight rollers having the same diameter in the axial direction.

Then, when the paper S having the toner image A is fed between the rollers 1 and 2 rotating in the direction of the arrow, the toner image A is melted and fixed on the paper S by the heat of the heater 5 and the pressure between the rollers.

By the way, since the fixing roller 1 is heated by the heater 5, its central portion 1a expands as shown by the chain line in FIG.

This expansion of the fixing roller causes the pressing force with the pressure roller 2 in the axial direction to be larger in the center and smaller at both ends, which changes the pressure on the paper S being fed and causes the problem of wrinkles on the paper. be.

As a roller that eliminates the above-mentioned problems, there is a roller as shown in FIG.

This roller 8 is a so-called drum-shaped roller in which both end portions 8a are formed to have a larger diameter than a central portion 8b, and the pressure in the central portion does not increase even if the central portion expands due to heating.

When a pressure roller is brought into pressure contact with the drum-shaped roller and the paper is fed, a force is applied to the paper that pulls it to both sides, making it possible to feed the paper stably without wrinkles. .

However, since the roller 8 is an elastic roller and the difference in diameter D2-D1 is about 0.01 to 0.1 mm, the change in diameter in the axial direction can be processed with high accuracy and the surface roughness can be reduced. Although this can be done for experimental purposes, it is difficult to produce it in large quantities from a cost standpoint.

In the present invention, at least one of a pair of rollers is an elastic roller, and by changing the temperature distribution of the means for heating this roller, the roller is deformed into a drum shape, and stable paper feeding operation is achieved. The purpose of the present invention is to provide a paper feeding device that performs the following operations.

The present invention will be explained below with reference to illustrated embodiments.

In FIG. 4, an elastic layer 10 is formed around a hollow core roller 9, and a heater 11 is inserted inside to form an elastic roller 12 as a fixing roller.

This roller 12 is a straight roller with a uniform diameter.

The elastic layer 10 is preferably made of silicone rubber, fluororubber, or the like, which meets the requirements for a fixing roller, such as releasability and heat resistance.

The heater 11, which is inserted into the roller 12 and heats it from the inside, has an end 11a corresponding to both ends 12a of the roller 120, 12a.

11a is tightly wound, and the central portion 11b is hardly wound.

Therefore, as shown in FIG. 5a, the temperature distribution of the heater 11 is higher at both ends than at the center, thereby heating the roller.

Therefore, the elastic roller 12 heated by the heater 11 exhibiting the temperature distribution shown in FIG. 5a expands and deforms at both ends 12a, 12a as shown by the chain lines.

The deformation of both ends of the elastic roller 120 may be large or small depending on the amount of heat generated by the heater and the material and thickness of the elastic layer 10.

According to experiments, the difference in diameter between the center and both ends of the elastic roller 12 is 0. Values up to a maximum value of 0.3 ynvn were obtained from Qlmm.

The above values are optimally selected and set by combining the heat generation amount of the heater and the elastic layer 10, depending on the surface temperature of the roller necessary for melting the toner image and the paper used.

When paper was fed by replacing the elastic roller 12 as described above with the fixing roller 1 shown in FIG. 1, good results with no wrinkles were obtained.

As long as the heating means has a temperature distribution as shown in FIG. 5a, it is not necessary to place it inside the roller itself, and as shown in FIG. A similar deformation of both ends of the roller can be obtained.

When the elastic roller 12 is used as a fixing roller as shown in FIG.
5 may be conducted, and in this case, the heat distribution changes smoothly, which is advantageous.

The surface temperature of the fixing roller is a problem in fixing the toner image, but when heating the fixing roller with a heating means as shown in FIGS. to obtain a surface temperature of

Further, the elastic roller 12 shown in FIG. 4 may be replaced with the pressure roller instead of the fixing roller 1 shown in FIG. 1, or both rollers may be replaced with the elastic roller 12. Of course.

When the former was configured and the heater 5 was set to 700W and the heater 11 was set to 200W and 84-size paper was sent, no wrinkles occurred and the fixing result was good.

The diameter at this time was 0.05 mm.

Note that the heater 11 as one of the means for heating the elastic roller is not limited to the distribution of heat generating parts as shown in FIG. 4, but may be changed as appropriate depending on the degree of the drum shape formed as a result of expansion. .

Further, as shown in FIG. 5, the temperature distribution of the heating means may be a W-shaped temperature distribution in which not only both ends but also the center part is heated and deformed as a large diameter part.

An elastic roller heated by a heating means with such a temperature distribution becomes a drum-shaped roller distributed at both ends around the center, and is particularly effective when the roller width is long.

Further, the elastic roller may be formed with an appropriate number of large diameter parts and small diameter parts by changing the temperature distribution as necessary.

When three or more large diameter portions are formed, it is desirable and effective to set the temperature distribution so that both ends have the largest diameter.

The elastic roller 12 may be coated with the heat-shrink tube 7, a resin coating, metal foil, or the like, or may be provided with an anti-offset layer made of Teflon, silicone rubber, or the like that has a release effect.

As described above, at least one of the pair of rollers that presses against each other and rotates to feed the paper is an elastic roller,
According to the paper feeding device of the present invention, which heats the roller with a heating means having a higher temperature distribution at both ends than at the center, the straight elastic roller can be heated without any mechanical processing. Since a drum-shaped roller corresponding to the temperature distribution of the heating means can be obtained, a stable paper feeding device without wrinkles can be obtained.

Being able to make a straight roller into a drum shape without using any means such as cutting allows the surface roughness of the roller to be kept uniform and is extremely effective in terms of cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a fixing device of a copying machine, FIG. 2 is a longitudinal sectional view of a conventional fixing roller, FIG. 3 is a side view showing another example of the same as above, and FIG. 4 is a paper feeding device of the present invention. FIG. 5 is a temperature distribution diagram of means for heating the same roller, and FIGS. 6 and 7 are side views showing other examples of the heating means. 11... Heater 12... Elastic roller.

Claims (1)

[Claims] 1. At least one of a pair of rollers that feed the paper by rotating in pressure contact with each other is an elastic roller, and at least both ends of the elastic roller have a diameter of 0.01 to
A paper feeding device for a copying machine, characterized in that the roller is heated by heating means having a temperature distribution that provides a large diameter portion and a small diameter portion so that the roller has a large diameter portion with a large diameter of 0.3 ynvt.