JPS58184173A - Preventing method of crease of paper in dry electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent creases of copy paper even if a rubber roll is used for a long time, by forming the outside face of the rubber roll into a tapered crown shape or reducing slightly the diameter of the center part of the core bar to form it into a recessed shape. CONSTITUTION:A center shaft 9 of a silicone rubber roll 8 having a certain thickness (t) is inclined left and right to the rotation shaft of a polishing grindstone 10 at a certain angle theta and is turned for a certain time to form the outside face of the rubber roll 8 into a tapered crown shape. Otherwise, the diameter in the center part having a certain length l of a core bar 12 is made smaller than diameters in both end parts, and the diameter of the outside circumferential face of the rubber is made even, and this rubber roll 8 becomes gibbous naturally by heating in the use because a volume change of the center thick part of the rubber is great. Even if this rubber roll slightly stepped is used for a long time, creases are not generated on the copy paper. It is more effective to use this rubber roll as a fixing roll than to use it as a pressfixing roll.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing paper wrinkles in a dry type electrophotographic copying machine. .

As shown in FIG. 1, a copying machine in the dry electrophotography method transfers the toner 3 adhered to the photoreceptor 2 onto the copy paper in accordance with the original document 1 on the upper surface, and then transfers the toner 3 onto the copy paper using a silicone rubber roll;
Fixed yMto - with 5! The toner is passed through 6 E-printing rollers, at which time the toner on the paper is heated and melted to be fixed (printed).

By the way, since the silicone rubber roller melts and presses the toner on the copy paper as mentioned above, it must be non-adhesive (type I11) to the molten toner. Tokuko Sho 54-263
It has been proposed to apply the necessary oil to the roll surface to maintain sufficient mold releasability as in No. 73, but this requires a separate mechanism for applying the oil, making the device itself complicated. It's expensive and has some disadvantages.

On the other hand, a method has been proposed in which the necessary and sufficient amount of oil is blended into the rubber material of the silicone rubber roll in advance. In areas where a lot of paper passes through, the oil on the roll side is transferred to the paper side, so the roll diameter gradually decreases depending on the size of the paper being used. A step gradually appears between the diameter and the diameter. ° Therefore, for example B5
If you use a lot of paper and sometimes copy A4 paper or B4 paper, you may need to use A6 paper due to the above-mentioned height difference.
Alternatively, wrinkles may appear on B4 paper.

As a countermeasure against this jealousy, it is best to form a crown 8t on the roll surface in advance as shown in Figure 2, but creating this shape requires the use of an NO polishing machine that costs 10 million yen. This makes it necessary and expensive.

Furthermore, a stepped shape as shown in Fig. 3 can be considered as a relatively simple shape, but even when molding such a shape, if the rubber layer becomes thick, the rubber will thermally expand due to the heat generated during polishing. It has the disadvantage that dimensional accuracy is difficult to achieve. This means that the volume change of i1 Lulicon rubber due to changes in temperature is extremely large, reaching 6 to 9 x lO- per 1°C, and this is only reflected in the volume change of the roll in the thickness direction. -For example, when heated from room temperature 20℃ to 160℃, 8.4
This results in an increase in thickness of ~12.6%.

Based on the above considerations, the present invention is an inexpensive method that can prevent wrinkles as much as possible even during long-term use in the latter method, that is, in silicone rubber rolls in which oil is mixed in the rubber material in advance. We aim to provide the following.

An example of implementing the present invention will be explained below based on the accompanying drawings.

Figure 4 shows the cross-sectional shape of the silicone rubber roll formed into the tapered crown, which is shown in Figure 5 A%B.
The center shaft 9 of a silicone rubber roll 8 having a constant thickness t is rotated at a constant time while being tilted left and right by a constant angle θ with respect to the rotation of the polishing wheel 1, as shown in FIG.
::・.

It is easily obtained. Figure @6 shows another example. In this example, the core bar 12 that supports the roll from the inside does not have the conventional straight shape, and the defined range t in the center part is extended to both sides as shown in the example. Smaller diameter than the line part,
In other words, the silicone rubber on the outer circumferential surface is formed to have a straight diameter Dt-, and the silicone rubber is formed to have a straight diameter Dt- when the roll is heated to 160°C. Since the volume change in the thick part is larger than that in other thin parts, the situation is as shown by the straight chain edge, which means that a medium-height rubber roll is actually used. It will disappear. In this example, if rh-d+=l■, then when heated at 160°C, TeD1-D2==:o, l~0.13■1 In the present invention, as shown in FIG. The appropriate range of the crown amount is expressed in terms of severance based on the diameter difference between the edges and the center.
wm or more), this will cause wrinkles in the paper, and if the pressure roll is 0.2'74 or more (diameter difference of 0.2cm or more), wrinkles will occur in the paper. Therefore, when designing, it is necessary to keep the value below the above value.

On the other hand, in the case where a step is provided as shown in FIG.
The step is to be provided within a range of approximately w+, but it is not necessary to do this for both the pressure roll and the fixing roll, and if only one of the rolls is provided with a step. It is possible to obtain a sufficient effect of increasing the energy efficiency. However, it can be said that it is more effective to provide the step on the fixing roll side rather than on the pressure roll side.

The reason for this is thought to be that since toner is present between the fixing roll and the copy paper, the frictional resistance between the fixing roll and the paper is greater than that between the pressure roll. usually,
The height difference implemented by the fixing roll is designed to be in the range of 0.3 to 0.9 cm, and the pressure roll is designed to be in the range of 0.6 to 2 cm.

FIG. 1 is a graphical representation of an actual trajectory example of the present invention.
The horizontal axis shows the number of copies, and the vertical axis shows the evaluation of the wrinkle occurrence rate for this 1. In this case, the evaluation grade is A, B.
1, B2, BS, B4, B5, B4, and B7 were distinguished by examining the rate at which image defects F occur and the number of wrinkles generated through 10 solid black sheets of A3 paper every time 5000 sheets of A4 paper are copied. In the illustrated example, the (A) line is the conventional one, and the middle (middle) line is the crimping roll k L ym with a step or 0.12 m.
The line e shows the case where the fixing roll has a tapered crown of 0.125. As can be seen in this graph, with the conventional roller, wrinkling becomes noticeable after around 40,000 sheets, and the roller becomes unusable, requiring replacement of the roller. This allows full use without the need to replace the rollers, and in particular, when applied to the fixing roller, its durability has been improved by several orders of magnitude.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the process of dry electrophotography, Figs. 2 and 3 are longitudinal sectional views of a silicone rubber roll, Fig. 4 is a longitudinal sectional view of a silicone rubber roll according to the present invention, and Fig. 5 A%.
B is a manufacturing state diagram, FIG. 6 is a longitudinal sectional view of another example, and FIG.
The figure is a graphical representation of an experimental example. 1... Original 2... Photoreceptor 4... Copy paper 5... Fixing roll 6 f---
Pressure roll 8 , Silicon rubber roll 9 , Center shaft 10 , Grinding wheel 11 , Rotating shaft
12... Core metal patent applicant Fukuyama Kenjo Kogyo Co., Ltd. No. 110 1, 2 Figure 6 w & Figure 4 Procedural amendments May 24, 1976 Commissioner of the Patent Office Haruki Shimada 1981 Patent application No. 6 99F No. 2, Title of the invention Dry electrophotography - Method for preventing paper wrinkles in military aircraft 3, Relationship with the case of the person making the amendment Patent applicant - 8 Attorney 6, Number of inventions increased by amendment 1) No. In the negative second line, ``Together,'' is corrected to ``Together,''. 2)! Page 5, line 11 K [D+ -Dt J.
Dl-Dl” is corrected. 3) -, page 7, line 6, line 6, arrival roll”, a certain tongue% “
Corrected as "core metal of crimp roll." 4) In the 14th line of page 7, replace the phrase "1 is enough" with "
"That's enough," I corrected. 5) 3rd row 19th row K[9xlO%Jtoa=-1, "p
Correct it to ``X 10%''. Above 1: (.

Claims (1)

[Claims] (1) When a fixing roll and/or a pressure roll is manufactured by blending a certain amount of oil into the silicone rubber roll in advance, the center part of the silicone rubber roll has a tapered crown shape that protrudes slightly from both end edges. Suka,
A method for preventing paper wrinkles in a dry type electrophotographic copying machine, characterized in that a core metal that supports a silicone rubber roll from the inside has a concave shape with a diameter slightly smaller at both ends in a certain range in the center.