EP0465259A1

EP0465259A1 - Elastic roller for paper feeding

Info

Publication number: EP0465259A1
Application number: EP91306106A
Authority: EP
Inventors: Hiroaki Tanaka; Yasutoki Ito; Masahiko Ueno; Hitoshi Itani
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 1990-07-06
Filing date: 1991-07-04
Publication date: 1992-01-08
Anticipated expiration: 2011-07-04
Also published as: DE69106605T2; EP0465259B1; DE69106605D1

Abstract

An elastic roller (10) for paper feeding of an existing rubber compound has an outer circumferential surface divided into plural sections (11) to make a surface layer of the outer circumferential surface of the elastic roller (10) easily deformable, which increases frictional force on paper being conveyed, thereby obtaining a greater conveying force.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an elastic roller for paper feeding in a paper feeder of copier, printer of information processing apparatus or the like.
Generally, in the paper feeder for copier, printer of information processing apparatus or the like, an elastic roller is used for paper feeding. Such elastic roller is required to have a large conveying force in order to attain a reliable paper feeding. In particular, a greater conveying force is required when feeding film for overhead projector (OHP).
Hitherto, attempts to provide the elastic roller with a great conveying force have been centered upon study for the rubber compound from which the elastic roller is made and which demonstrates a higher coefficient of friction by, for example, blending the materials for the elastic roller to be low in hardness or large in tackiness by impregnating much oil or the like.
Incidentally, when considering the material blending for the elastic roller in order to obtain a large conveying force in the elastic roller, the optimum dosing must be calculated taking various blending agents or ingredients into account so as to satisfy many properties such as processability and storage stability, in addition to obtaining a high coefficient of friction. But such job requires much time, labor and material cost.
Accordingly, in order to have a large conveying force with an existing rubber compound, an elastic roller with a ground surface (hereinafter called surface ground roller) has been in use.
Although the surface ground roller obtains a large conveying force by increasing the frictional force against paper being conveyed by grinding and roughening the surface, the manufacturing cost is greatly raised for the addition of the process of surface grinding. Moreover, the surface ground pattern is worn as the paper feeding is repeated, and the conveying force is lowered as the wearing progresses, deteriorating paper feeding condition in a short period. Thus, the surface roughness of the surface ground roller is usually about 3 to 100 µ, and accordingly the surface wearing of only 0.2 mm makes the surface smooth and slick, where paper cannot be fed satisfactorily.
Besides, the surface ground roller is specified in the direction of frictional force since the surface ground roller has on its surface directional markings caused by abrasive in the process of surface grinding. In the case where two or more surface ground rollers are used mounted on one and the same shaft, attention should therefore be paid so that they are all in the same direction otherwise satisfactory paper feeding cannot be performed; e.g. paper can run obliquely to result in paper feeding failure. Fig. 10 shows the result of experiment conducted to prove the orientation of frictional force of the surface ground roller. In this experiment, by installing the surface ground roller in correct direction (normal grain use) and in wrong direction (reverse grain use), the coefficient of friction with respect to the surface roughness was measured. The conditions of the experiment were 200 g in load, 250 mm/s in roller peripheral speed, 23°C in temperature, and 55% in humidity. As a result, it is known that the coefficient of friction is greater in the normal grain use than in the reverse grain use. It is hence evident that the surface ground roller is specified in direction.

SUMMARY OF THE INVENTION

The invention has been devised in the light of the foregoing, and it is a primary object thereof to provide an elastic roller for paper feeding capable of exhibiting a large conveying force, using an existing rubber compound.
The present inventors, as a result of intensive studies to achieve the above object, have found the elastic roller for paper feeding capable of exhibiting a great conveying force using an existing rubber compound.
More specifically, the inventors prepared rubber rollers of the width of 40 mm, 30 mm, 20 mm and 10 mm each for the outside diameters of 38⌀, 34⌀, 31⌀, 27⌀, 24⌀, and measured the coefficient of friction µ in the conditions of load of 100 to 400 g and roller peripheral speed of 100 to 500 mm/s. The results obtained are as shown in Table 1 as for the outside diameters of 38⌀, 31⌀, 24⌀ at the load of 100 g and roller peripheral speed of 100 mm/s, and as shown in Table 2 as for the outside diameters of 38⌀, 31⌀, 24⌀ at the load of 400 g and roller peripheral speed of 500 mm/s.
It is known from these results that, provided the load and the roller peripheral speed be constant, the friction of coefficient µ is nearly unchanged, almost regardless of the width and outside diameter.
However, summing up in terms of the load per width, as shown in Table 3 (which shows the result of measurement at the load of 100 mg per 10 mm of width, and roller peripheral speed of 500 m/s), it is known that the coefficient of friction µ is higher in a narrower rubber roller.
Therefore, as the elastic roller for paper feeding in which a large conveying force is required, it is preferable to have a plurality of narrow rubber rollers instead of one broad roller. The reason for the increase in frictional force is considered to be such that the surface layer portion of the rubber roller is easily, elastically deformable when the rubber roller width is narrower than when broader, so that the frictional resistance to paper increases.
Finally, the inventors have discovered it effective to divide the outer circumferential surface of the elastic roller so that the surface layer portion thereof may be easily deformed in order to obtain an elastic roller for paper feeding exhibiting a great conveying force even with an existing rubber compound.
Accordingly, the invention provides an elastic roller for paper feeding comprising a plurality of narrow elastic rollers disposed parallel at a predetermined pitch.
In this elastic roller, the frictional resistance to paper being conveyed increases due to deformation of edge portions of each of the plural narrow elastic rollers, so that a great conveying force may be obtained.
The invention also provides an elastic roller for paper feeding having plural annular cuts formed at a predetermined pitch in the outer circumferential surface thereof.
In this elastic roller, the surface layer portion of the elastic roller is easily deformable owing to the presence of the plural annular cuts, resulting in an increased frictional resistance to paper, so that a great conveying force is obtained.
The invention further provides an elastic roller for paper feeding having plural annular grooves formed at a predetermined pitch in the outer circumferential surface thereof.
In this elastic roller, by forming plural annular grooves, multiple edge portions are formed on the outer circumferential surface of the elastic roller, and by the deformation of the edges, the frictional resistance to paper increases, thereby ensuring a great conveying force.
Moreover, the invention provides an elastic roller for paper feeding comprising a plurality of narrow elastic rollers disposed parallel at a predetermined pitch, and annular cuts or grooves are formed in the outer circumferential surface of each of the narrow elastic rollers.
In this elastic roller, the surface layer portion of each narrow elastic roller is easily deformable owing to the annular cuts or grooves, which, in combination with the deformability of edge portions of each narrow elastic roller, further increases the frictional resistance to paper to obtain a greater conveying force.
Still more, the invention provides an elastic roller for paper feeding having annular grooves formed at a predetermined pitch in the outer circumferential surface thereof, and annular cuts are formed in the surface portions or lands between the adjacent annular grooves and between the annular grooves at both ends and the both end edges of the outer circumferential surface.
In this elastic roller, the surface layer portions of the elastic roller is easily deformable owing to the plural annular cuts, which, in combination with the deformability of the edge portions adjacent the annular grooves, serves to increase the frictional resistance to paper, thereby ensuring a great conveying force.
Furthermore, the invention provides an elastic roller for paper feeding having multiple ridges or microveins with top end width of 0.5 mm or less formed, on the outer circumferential surface at a pitch not greater than 1 mm and orthogonally in the paper conveying direction.
In this elastic roller, the surface roughness of the outer circumferential surface thereof becomes coarser due to the microveins, and the frictional resistance to paper increases, so that a greater conveying force may be obtained.
Thus, according to the invention, an elastic roller for paper feeding capable of exhibiting a great conveying force is provided, using an existing rubber compound, and as compared with the conventional method of considering the material blending, the time, labor and material cost may be greatly saved. Besides, unlike the surface ground roller, the frictional force is not specified in direction, and there is no difference in the conveying force depending on the rotating direction. Consequently, a plurality of elastic rollers, if mounted at random with regard to rotational direction, may be utilized concurrently without attendance of any troubles such as those encountered by the surface ground roller.
Preferred embodiments of the invention will now be described in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of an elastic roller for paper feeding in a first embodiment of the invention;
Fig. 2 is a front view showing an example of an elastic roller used in an experiment for explaining that the elastic roller of the first cmbodiment can exhibit a great conveying power;
Fig. 3 and Fig. 4 are front views of elastic rollers for paper feeding in second and third embodiments of the invention;
Fig. 5 is an explanatory drawing showing an example of an elastic roller used in an experiment for explaining that the elastic rollers in the second and third embodiments can exhibit a great conveying force;
Fig. 6 and Fig. 7 are front view and side view of a fourth embodiment;
Fig. 8 is a diagram showing the result of an experiment for explaining that the elastic roller in the fourth embodiment can exhibit a great conveying force;
Fig. 9 is an explanatory drawing showing an example of vein shape and dimension of the elastic roller used in the same experiment; and
Fig. 10 is a diagram showing the result of an experiment for explaining that the frictional force of the surface ground roller is specified in direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First of all, the elastic roller for paper feeding in the first embodiment of the invention will be explained by referring to Fig. 1. This elastic roller 10 comprises a plurality of, for example, four narrow rollers 11 disposed parallel at a predetermined pitch.
In the elastic roller 10 of the first embodiment, the area of contact with the paper being conveyed increases owing to an elastic deformation of the edge portions 11a of the rollers 11 so that a great conveying force is obtained.
Table 4 shows the measurement results of the experiment conducted to explain that the elastic roller 10 of the first embodiment produces a large conveying force. That is, in the experiment, the conveying force for plain paper wasmeasured, with the three elastic rollers a to c fabricated as shown in Fig. 2 A to C, in the experimental condition of load of 400 g, and roller peripheral speed of 100 mm/s. The elastic rollers a to c measure 38⌀ in outside diameter, 8⌀ in inside diameter.
The result shows that the maximum conveying force was exhibited by the elastic roller c consisting of a plurality of parallelly disposed narrow rollers. It is hence evident that the elastic roller 10 of the first embodiment brings about a large conveying force.
The elastic rollers for paper feeding in the second and third embodiments of the invention will now be explained with reference to Figs. 3 and 4. The elastic roller 2 shown in Fig. 3 has a plurality of, for example, seven annular cuts 22 formed at a predetermined pitch in the outer circumference of a broad roller 21. The elastic roller 30 of the third embodiment in Fig. 4 has a plurality of, for example, six annular grooves 32 formed at a predetermined pitch in the outer circumference of a broad roller 31.
In the elastic roller 20 of the second embodiment, the surface of the roller 21 is easily deformable owing to the presence of the cuts 23 and the contact area with the paper increases, so that a larger conveying force is obtained. In the elastic roller 30 of the third embodiment, the annular grooves 32 allow multiple edge parts 31a formed on the outer circumference of the roller 31 to be deformable, thereby increasing the area of contact with the paper, and ensuring a large conveying force.
Table 5 shows the measurement result of the experiment conducted for proving that the elastic roller of the second embodiment and the elastic roller of the third embodiment can exhibit a great conveying force. That is, in the experiment, rubber rollers of 38⌀ outside diameter, 20⌀ inside diameter and 4 mm width were processed as shown in Fig. 5 A to E to obtain the elastic rollers No. 1 to No. 5 for the second embodiment, and processed as shown in fig. 5 F to I to obtain the elastic rollers No. 6 to No. 9 for the second embodiment, while the elastic roller No. 10 was not processed, and the coefficient of friction µ for plain paper and OHP film was measured. The experimental conditions were as follows: load of 400 g, roller peripheral speed of 100 mm/s, temperature of 23°C and humidity of 55%. Numerals appearing in Fig. 5 indicate the dimensions in the unit of mm.
It is known from the result of experiment that the elastic rollers No. 1 to No. 5 of the second embodiment of the invention are higher in the coefficient of friction µ as compared with the unprocessed elastic roller No. 10 , and also that the elastic rollers No. 5 to No. 9 of the third embodiment of the invention are, although the roller effective width is decreased, equivalent to the unprocessed elastic roller No. 10 in the coefficient of friction µ. It is hence evident that the elastic roller 20 of the second embodiment of the invention and the elastic roller 30 of the third embodiment bring about a great conveying force.
Furthermore, the elastic roller for paper feeding of the fourth embodiment of the invention will now be explained with reference to Figs. 6 and 7. In this elastic roller 40 , ridges or veins 41a having a triangular cross-section are formed on the outer circumference of the broad roller 41, the pitch between the adjoining veins 41a being 1 mm or less.
In the elastic roller of the fourth embodiment, since the veins 41a are formed on the outer circumference at a pitch of 1 mm or less, the surface roughness on the outer circumference of the roller 41 is coarse same as on the surface ground roller, and the frictional resistance with the paper increases, so that a great conveying force is brought about.
In the fourth embodiment, the veins 41a are shown as having a triangular cross-section,but it is not limitative in the invention, and the cross-sectional shape may be other than triangular as far as the pitch of the veins 41a is not greater than 1 mm and the top end width is not greater than 0.5 mm.
Fig. 8 shows the result of experiment for three elastic rollers having the shape, dimension (unit: mm), pitch, top end width and height of veins as shown in Fig. 9 A to C, and for the surface ground roller as a comparative one, in the conditions of load of 100 g and roller peripheral speed of 500 mm/s. However, it should be appreciated that the veins of the triangular cross-section shown in Fig. 9A is pointed at the top, and has not top end width as such.
It is known from the experiment that the conveying force becomes smaller when the vein pitch exceeds 1 mm, and that the conveying force after long-term use is lowered when the top end width exceeds 0.5 mm. Therefore, the veins may preferably have a pitch not greater than 1 mm and top end edge not greater than 0.5 mm, and when these conditions are satisfied, the surface does not become slick, with less lowering of conveying force if the wear is promoted, unlike the surface ground roller.

Claims

An elastic roller for paper feeding by making use of frictional force, wherein an outer circumferential surface of said roller is divided into plural sections, so that a surface layer part of each of said sections may be easily deformed.
An elastic roller for paper feeding of claim 1, wherein said roller comprises plural narrow elastic rollers disposed parallel at a predetermined pitch.
An elastic roller for paper feeding of claim 1, wherein annular cuts are formed at a predetermined pitch in an outer circumferential surface of said roller.
An elastic roller for paper feeding of claim 1, wherein annular grooves are formed at a predetermined pitch in an outer circumferential surface of said roller.
An elastic roller for paper feeding of claim 1, wherein said roller comprises plural narrow elastic rollers disposed parallel at a predetermined pitch, and annular cuts or grooves are formed in an outer circumferential surface of each of said narrow elastic rollers.
An elastic roller for paper feeding of claim 1, wherein annular grooves are formed at a predetermined pitch in an outer circumferential surface of said roller, and annular cuts are formed in the outer circumferential surface between the annular grooves and between the annular grooves at both ends and the outer circumferential both end edges.
An elastic roller for paper feeding of claim 1, wherein multiple microveins with a pitch not greater than 1 mm and front end width not greater than 0.5 mm are formed on an outer circumferential surface of said roller, orthogonally to the direction in which paper is conveyed.