CN115916675A - Roller - Google Patents

Abstract

A roller for feeding paper includes a surface contacting a paper sheet and having protrusions and grooves. The surface roughness indicating the degree of surface unevenness is in the range of 50 micrometers or more and 80 micrometers or less. The interval of the protrusions is in the range of 0.6mm or more and 0.8mm or less.

Description

Roller

Technical Field

The present invention relates to a roller for feeding paper.

Background

Office equipment such as copiers and printers are generally provided with a paper feed roller. Such rolls need to maintain sufficient conveying capacity and have high wear resistance. In this regard, for example, patent document 1 discloses a paper feed roller having a concave-convex surface.

Documents of the related art

Patent document

Patent document 1: japanese patent application laid-open No. 2002-96938

Disclosure of Invention

Problems to be solved by the invention

During use, since the surface protrusions of the roller are worn and paper dust adheres to the surface of the roller, the friction coefficient of the paper feed roller tends to decrease, resulting in a paper feed problem.

In view of the above, an object of the present invention is to suppress a decrease in the friction coefficient of a paper feed roller.

Means for solving the problems

In order to achieve the above object, a roller according to the present invention is a roller for feeding paper, the roller including a surface contacting with a paper sheet, and having a plurality of protrusions and a plurality of grooves, wherein a surface roughness representing a degree of unevenness of the surface is in a range of 50 micrometers or more and 80 micrometers or less, and wherein intervals of the plurality of protrusions are in a range of 0.6 millimeters or more and 0.8 millimeters or less.

Drawings

Fig. 1 is an explanatory diagram showing a schematic structure of a roller according to the embodiment.

Fig. 2 is an explanatory diagram showing the kinds and conditions of evaluation for the paper feed test.

Fig. 3 is an explanatory diagram showing the results of the paper feed test.

Fig. 4 shows the evaluation result of the protrusion cross-sectional area AR.

Fig. 5 shows the evaluation results of the friction coefficient.

Fig. 6 is an explanatory view of the operation of the roller shown in fig. 1.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the sizes and proportions of the elements are suitably different from those of the actual elements. The embodiments described below include preferred examples of the present invention. Therefore, various technically preferable restrictions apply. However, the scope of the present invention is not limited to these examples unless such examples include descriptions of specific limitations of the present invention.

1. Examples of the embodiments

Now, an embodiment of the present invention is described. First, an example of the outline of the roller 10 according to the present embodiment is described with reference to fig. 1.

Fig. 1 is an explanatory diagram showing a schematic structure of a roller 10 according to the present embodiment.

For convenience of explanation, in the present embodiment, reference is made to a mutually orthogonal three-axis coordinate system including an X axis, a Y axis, and a Z axis.

Hereinafter, the direction indicated by the X-axis arrow is referred to as "+ X direction", and the direction opposite to the + X direction is referred to as "-X direction". The direction indicated by the Y-axis arrow is referred to as "+ Y direction", and the direction opposite to the + Y direction is referred to as "-Y direction". The direction indicated by the Z-axis arrow is referred to as the "+ Z direction", and the direction opposite to the + Z direction is referred to as the "-Z direction".

Hereinafter, the + X direction and the-X direction may be simply referred to as "X direction" without distinction, the + Y direction and the-Y direction may be simply referred to as "Y direction" without distinction, and the + Z direction and the-Z direction may be simply referred to as "Z direction" without distinction.

In one example, the roller 10 is used to feed paper. Examples of the roller 10 include a paper feed roller, a separation roller, and a conveyance roller, which are used in office equipment such as a copying machine and a printer. In the present embodiment, the roller 10 is a paper feed roller.

The "perspective view" in fig. 1 shows the entire roller 10. The "schematic view of the surface" in fig. 1 shows a part of the roller 10 (a part in contact with the sheet PA) as viewed in the + Z direction, and also shows the sheet PA conveyed in the-X direction (the direction indicated by the dotted arrow). Hereinafter, the conveying direction of the paper PA is referred to as "conveying direction".

As shown in "perspective view" in fig. 1, the roller 10 includes: a shaft connecting portion 12 having a shaft hole HL for inserting a rotatable shaft member 16; and a cylindrical rubber portion 14 surrounding the shaft connecting portion 12. The shaft member 16 is rotatable about a central axis AX along the Z-axis. Rotation of the shaft member 16 rotates the roller 10 connected to the shaft member 16. A shaft member 16 may be included in the roller 10. Further, the shaft member 16 and the shaft connecting portion 12 may be formed as a single unit having the same configuration as when the shaft connecting portion 12 is inserted into the shaft member 16.

The shaft connecting portion 12 may be formed of synthetic resin such as plastic harder than rubber, or may be formed of a metal material. The rubber portion 14 is formed of an elastic material such as Ethylene Propylene Diene Monomer (EPDM). The EPDM has a hardness in the range of 30 DEG or more and 50 DEG or less in accordance with the type A hardness of Japanese Industrial Standard (JIS) K6253. In this case, the parameters of wear resistance and compatibility can be controlled by polishing (workability). The type a hardness represents a hardness measured using a type a durometer in accordance with JIS K6253 (corresponding to ISO 7619). Hereinafter, the type A hardness according to JIS K6253 is referred to as "JISA".

Increasing the hardness of the material of the rubber portion 14 is one way to achieve an increase in wear resistance. However, increasing the hardness of the material of the rubber portion 14 results in a decrease in the initial friction coefficient due to a decrease in the nip (nip) width. The reduction of the initial friction coefficient reduces the paper feeding efficiency. In addition, the use of a material such as polyurethane having high abrasion resistance for the rubber portion 14 reduces the reduction in the friction coefficient and increases the cost. In the present embodiment, EPDM is used as the material of the rubber portion 14, and therefore, the cost of the roller 10 can be reduced as compared with the case where polyurethane is used as the material of the rubber portion 14.

As shown in "schematic view of surface" in fig. 1, the outer peripheral surface of the rubber portion 14 (the surface of the roller 10) has grooves 14cc and protrusions 14cv. That is, the roller 10 has a concave-convex surface 14c. The concave-convex surface 14c including the protrusions 14cv and the grooves 14cc is in contact with the paper PA. In one example, the protrusions 14cv and the grooves 14cc of the concave-convex surface 14c shown in fig. 1 alternate and extend in the Z direction (longitudinal direction of the roller 10).

In describing the surface roughness Rz and the interval S of the protrusions 14cv, "schematic view of the surface" shown in fig. 1 is provided for reference, which will be described later. The actual shape of the surface of the roller 10 is not limited to the example shown in the "schematic view of the surface" of fig. 1. Each protrusion 14cv may have a curved side SD when the roller 10 is viewed from the + Z direction. When the roller 10 is viewed from the + Z direction, the side SD is depicted by a line connecting the vertex P1 and the vertex P2 in the conveying direction with respect to the top of the protrusion 14cv (the vertex P1 shown in fig. 1). When two adjacent protrusions 14cv are observed, the vertex P3 of either one corresponds to the vertex P2 of the other.

The initial surface roughness Rz representing the degree of unevenness of the outer peripheral surface of the rubber portion 14 is in the range of 50 μm or more and 80 μm or less. In one example, the term "initial (state)" refers to a state in which the roller 10 has not been mounted for use in office equipment. The surface roughness Rz of the outer peripheral surface of the rubber portion 14 indicates the degree of unevenness of the surface (uneven surface 14 c) of the roller 10. The surface roughness Rz has a ten-point average roughness according to JIS standard B0601 (1994).

In the initial state, the interval S of the protrusions 14cv on the concave-convex surface 14c is in the range of 0.6mm or more and 0.8mm or less. Hereinafter, the interval S of the protrusions 14cv is referred to as "inter-protrusion distance S". The inter-protrusion distance S may be a distance between two apexes of the adjacent protrusions 14cv, i.e., the apex of one protrusion (apex P1) and the apex of the adjacent protrusion (apex P1). The distance S between protrusions may be an average interval of local peaks according to JIS B0601 (1994). The ratio (S/Rz) of the inter-protrusion distance S to the surface roughness Rz is in the range of 7.5 or more and 14 or less. Hereinafter, the unit "micrometer" is referred to as "μm", and the unit "millimeter" is referred to as "mm". The ratio of the inter-protrusion distance S to the surface roughness Rz (S/Rz) is referred to as "protrusion aspect ratio".

When one protrusion 14cv is observed, the height of the protrusion 14cv on the X axis (the locus of the side SD) has the following relationship. In one example, the height of the protrusion 14cv at one position on the X-axis is lower than the height of the protrusion 14cv at other positions in the conveying direction (the-X direction shown in fig. 1) from the position.

If the height of the protrusion 14cv at one position on the X axis is divided higher than the height of the protrusion 14cv at other positions in the conveying direction (the-X direction shown in fig. 1) from that position (i.e., when the sheet is conveyed in the + X direction in fig. 1), the friction coefficient between the sheet PA and the surface of the roller 10 is smaller than that in the present embodiment. More specifically, in the present embodiment, when the height of the protrusion 14cv at one position on the X axis is higher than the height of the protrusion 14cv at the other position in the conveying direction from the position, the friction coefficient between the paper PA and the surface of the roller 10 becomes large, and the decrease in paper feeding performance is suppressed.

Next, referring to fig. 2 to 5, the results of the paper feed test using the roller 10 will now be described. The term "paper feed" refers to the action of the roller 10 through the paper PA.

Fig. 2 is an explanatory diagram of the kind and conditions of evaluation for the paper feed test.

The category shown in fig. 2 contains information on a paper feeding test performed to evaluate performance in a paper feeding environment having a temperature of 10 ℃ and a humidity of 20%. The apparatus used for the paper feeding test was a color printer (docupint C5000 d) manufactured by Fuji Xerox corporation (Fuji Xerox, co., ltd.).

As described above, according to JIS standard B0601 (1994), the surface roughness Rz (unit: μm) is a ten-point average roughness. The measuring device used was a surfing encoder SE-500 manufactured by Kosaka Laboratory, ltd. The measurement conditions were as follows: the cut-off value was 0.8, the measurement length was 8mm, and the measurement speed was 0.1mm/sec.

The measuring device for measuring the inter-protrusion distance S (unit: mm) was a single-pass 3D measuring machine VR-3000 manufactured by Keyence Corp. The measurement conditions were as follows: the total magnification on the monitor was 25-fold and the level of cleavage obtained by High Spot Count (HSC) was 33%. In one example, an average value of "11 vertical lines per image × 2 points in one image (average value of inter-protrusion distances)" is calculated as the inter-protrusion distance S. Specifically, to measure the inter-process distance S, 11 vertical lines are drawn at equal intervals on the image of the sample surface of one image, and the HSC and inter-process distance are calculated for each vertical line. Then, the average of the 11 inter-protrusion distances is calculated as the inter-protrusion distance of one image. Further, two images are taken for one product from different positions, and an average value of the inter-protrusion distances of the two images is calculated as the inter-protrusion distance S. For this evaluation, high points were not measured. The high-point number is the number of points per unit length extending above a height obtained by cutting a measurement curve at a freely selected height (the cutting level is 33% in the measurement condition shown in fig. 2).

Using the simplified bump model shown in FIG. 2, the bump cross-sectional area AR (unit: mm ^ 2) is calculated from the inter-bump distance S and the bump height 14cv. Here, "[ lambda ] denotes a power. The surface roughness Rz is used as the height of the protrusions 14cv. The height Rz0 of the protrusions 14cv shown in fig. 2 represents the initial surface roughness Rz. In one example, a protrusion sectional area AR0 shown in fig. 2 represents a sectional area of the protrusion 14cv in a case where the roller 10 in an initial state is cut along a plane parallel to an XY plane containing the X axis and the Y axis. That is, the initial protrusion cross-sectional area AR0 represents the initial protrusion cross-sectional area AR. The worn cross-sectional area ARa represents the cross-sectional area of the portion of the projection cross-sectional area AR0 worn by paper feed. The worn width Wa indicates the width along the X axis of the portion worn by the paper feed.

As shown in the schematic diagram of the measurement method, the paper PA is placed between the roller 10 and the aluminum plate 102, the roller 10 is rotated counterclockwise at a linear velocity of 300mm/sec with a load of 2.5N applied to the paper PA, and the measurement of the friction coefficient is performed. In one example, the friction coefficient between the paper PA and the surface of the roller 10 is calculated based on (i) a measurement value of the load sensor 100 (force applied to the paper PA in the X direction) obtained by rotating the roller counterclockwise at a linear velocity of 300mm/sec and (ii) a load (2.5N) applied to the paper PA. The measurement of the coefficient of friction was carried out at a temperature of 10 ℃ and a humidity of 20%.

Fig. 3 is an explanatory diagram showing the results of the paper feed test.

The first sample value shown in fig. 3 is for the roller 10 of the present embodiment. As a comparative example in the present embodiment, fig. 3 shows paper feed test values of the first to fourth comparative samples. Hereinafter, for convenience of description, the four comparative samples will be described using the same reference numerals as those of the roller 10.

In the first sample, the material used for the rubber portion 14 was EPDM, and the hardness of the rubber portion 14 was 35 ° according to JISA. The initial surface roughness Rz was 63 μm, the initial inter-protrusion distance S was 0.71mm, and the initial protrusion aspect ratio (S/Rz) was 11.3.

In the first comparative sample and the second comparative sample, the material and hardness of the rubber portion 14 were the same as those in the first sample. In the first comparative sample, the initial surface roughness Rz was 32 μm, the initial inter-protrusion distance S was 0.85mm, and the initial protrusion aspect ratio (S/Rz) was 26.6. In the second comparative sample, the initial surface roughness Rz was 35 μm, the initial inter-protrusion distance S was 0.7mm, and the initial protrusion aspect ratio (S/Rz) was 20.

In the third and fourth comparative samples, the rubber portion 14 was made of the same material as the first sample, but had a hardness of 25 °, which was lower than that of the first sample. In the third comparative sample, the initial surface roughness Rz was 38 μm, the initial inter-protrusion distance S was 0.88mm, and the initial protrusion aspect ratio (S/Rz) was 23.2. In the fourth comparative sample, the initial surface roughness Rz was 36 μm, the initial inter-protrusion distance S was 0.69mm, and the initial protrusion aspect ratio (S/Rz) was 19.2.

In the third comparative sample and the fourth comparative sample, evaluation results of up to 30,000 sheets are shown in fig. 3. This is because the friction coefficient cannot be measured any more after feeding 30,000 sheets of PA.

After feeding 50,000 sheets PA, the projection sectional area AR is smaller than the initial projection sectional area AR. That is, the sheet feeding reduces the projection sectional area AR.

The projection sectional area AR of the first sample is larger than those of the other samples in the initial state and after feeding 50,000 sheets PA.

The friction coefficient after feeding 50,000 sheets PA is smaller than that in the initial state. That is, paper feeding reduces the coefficient of friction. Although the friction coefficient of the first sample was smaller than those of the other samples in the initial state, it was larger than those of the other samples after feeding 50,000 sheets of paper PA. That is, the first sample is more suppressed in the decrease in the friction coefficient due to the sheet feeding than the other samples. In fig. 3, the value for each sample in parentheses represents the percentage reduction of the friction coefficient of each sample from the corresponding value in its initial state.

Fig. 4 shows the evaluation result of the protrusion cross-sectional area AR. In FIG. 4, the vertical axis represents the projection sectional area AR (mm 2), and the horizontal axis represents the number of fed sheets (k sheets).

The projection cross-sectional area AR of the first sample decreased as the number of fed sheets increased. In addition, in the initial state (when the number of fed sheets is zero), the projection cross-sectional area AR of the first sample is larger than those of the first and second comparative samples, and also larger than those of the first and second comparative samples after feeding 15,000, 30,000, and 50,000 sheets. As shown in fig. 4, in the first sample of the present embodiment, a larger projection cross-sectional area AR is maintained although the number of supplied sheets is increased. As a result, in the present embodiment, as shown in fig. 5, a decrease in the friction coefficient is suppressed.

Fig. 5 shows the evaluation results of the friction coefficient. In fig. 5, the vertical axis represents the friction coefficient, and the horizontal axis represents the number of fed sheets (k sheets).

The friction coefficient decreases as the number of fed sheets increases. In the initial state (when the number of fed sheets is zero), the friction coefficient of the first comparative sample is the largest, and the friction coefficient of the first sample is the smallest among the first sample, the first comparative sample, and the second comparative sample. When the fed sheet number is 50,000, the friction coefficient of the first sample is the largest, and the friction coefficient of the first comparative sample is the smallest among the first sample, the first comparative sample, and the second comparative sample. That is, the percentage reduction of the friction coefficient of the first sample was the smallest among the first sample and the first and second comparative samples. For example, the percent reduction in the coefficient of friction of the first sample was-34.1%, while the percent reduction in the coefficient of friction of the second comparative sample was-55.9%, and the percent reduction in the coefficient of friction of the first comparative sample was-66.0%.

Therefore, in the first sample of the present embodiment, a large friction coefficient was maintained despite the increase in the number of sheets fed. That is, in the present embodiment, a decrease in the friction coefficient is suppressed.

Referring to the evaluation results of the first sample having a surface roughness Rz of 63 μm and the second comparative sample having a surface roughness Rz of 35 μm, it is apparent that the larger the surface roughness Rz, the larger the suppression of the decrease in the friction coefficient. Therefore, the surface roughness Rz is preferably larger than 35 μm, that is, 50 μm or more.

In addition, referring to the evaluation results of the first comparative sample in which the inter-protrusion distance S was 0.85mm and the second comparative sample in which the inter-protrusion distance S was 0.7mm, it is apparent that the smaller the inter-protrusion distance S, the greater the suppression of the decrease in the friction coefficient. Therefore, the inter-projection distance S is preferably less than 0.85mm, that is, 0.8mm or less.

In the present embodiment, the roller 10 is formed to satisfy the first conditions that (i) the initial surface roughness Rz is in the range of 50 μm or more and 80 μm or less, and (ii) the initial inter-protrusion distance S is in the range of 0.6mm or more and 0.8mm or less.

Referring to the reduction of the friction coefficient in the combination satisfying the first condition, the combination of the surface roughness Rz of 50 μm and the inter-protrusion distance S of 0.8mm shows the least suppression of the reduction of the friction coefficient. This results in that, in addition to the first condition, if a protrusion aspect ratio (S/Rz) of less than 16 (= 0.8mm/50 μm), i.e., 14 or less is applied, a better suppression of the decrease in the friction coefficient can be expected. In the present embodiment, the roller 10 is formed to satisfy the first condition and the second condition at the same time. The second condition defines a protrusion aspect ratio (S/Rz) in a range of 7.5 or more and 14 or less.

Fig. 6 is an explanatory diagram of the operation of the roller 10 shown in fig. 1. Fig. 6 includes a schematic view of the surface of the roller 10 and a schematic view of the surface of the above-described first comparative sample. Hereinafter, the first comparative sample is referred to as "roller 10Z".

Since the surface roughness Ry of the roll 10 is larger than the surface roughness Ry of the roll 10Z, the projection sectional area AR of the roll 10 is larger than the projection sectional area AR of the roll 10Z. Even in the case of paper feeding, the roller 10 can maintain a large projection cross-sectional area AR, and thus a decrease in the friction coefficient of the roller 10 can be suppressed more than the roller 10Z.

Since the inter-projection distance S of the roller 10 is smaller than the inter-projection distance S of the roller 10Z, the number of contact portions between the sheet PA and the roller 10 per given length L is larger than the number of contact portions between the sheet PA and the roller 10Z. That is, the contact area between the paper PA and the rubber portion 14 in the roller 10 is larger than that in the roller 10Z, so that the pressure per unit area applied to the protrusions 14cv of the roller 10 is reduced to a greater extent than that of the roller 10Z. Therefore, it is expected that the progress of wear of the projections 14cv of the roller 10 due to paper feeding (i.e., the speed of decrease of the projections 14 cv) will be slower than that of the roller 10Z.

Since the inter-projection distance S of the roller 10 is smaller than that of the roller 10Z, the number of grooves 14cc per given length L is larger than that in the roller 10Z. Therefore, the roller 10 can improve the effect of preventing paper dust from being collected in the grooves 14c, compared to the roller 10Z.

Since the surface roughness Rz of the roller 10 is larger than that of the roller 10Z, the volume of the grooves 14cc (the volume of the space defined between the adjacent two protrusions 14 cv) is larger than that of the grooves 14cc in the roller 10Z. The deterioration of the paper feeding performance of the roller 10 due to trapping of paper dust and the like in the grooves 14cc is more prevented than the roller 10Z. That is, the reduction in paper feeding performance is suppressed while preventing the collection of paper dust.

In the above embodiment, the paper feed roller 10 includes the surface (concave-convex surface 14 c) that contacts the paper PA, and the surface includes the protrusions 14cv and the grooves 14cc. The surface roughness Rz representing the degree of surface unevenness is in the range of 50 μm or more and 80 μm or less. The interval S (inter-protrusion distance S) of the protrusions 14cv on the concave-convex surface 14c is in the range of 0.6mm or more and 0.8mm or less.

Therefore, in the present embodiment, the surface roughness Rz is in the range of 50 μm or more and 80 μm or less, and the interval S of the protrusions 14cv is in the range of 0.6mm or more and 0.8mm or less. Therefore, the projection 14cv having a large cross-sectional area (projection cross-sectional area AR) is formed, and the large cross-sectional area (projection cross-sectional area AR) of the projection 14cv is maintained even at the time of paper feeding. In the present embodiment, a decrease in the friction coefficient of the roller 10 is suppressed.

In the present embodiment, the ratio of the interval S of the protrusions 14cv to the surface roughness Rz is in the range of 7.5 or more and 14 or less. That is, in the present embodiment, the first condition and the second condition are satisfied. Under the first condition, (i) the surface roughness Rz is in the range of 50 μm or more and 80 μm or less, and (ii) the interval S of the protrusions 14cv is in the range of 0.6mm or more and 0.8mm or less. In the second condition, the ratio of the spacing S between the protrusions 14cv to the surface roughness Rz is in the range of 7.5 or more and 14 or less.

As will be apparent from the above, in the present embodiment, in the combination of the first condition that the surface roughness Rz and the interval S of the protrusions 14cv are satisfied, the combination of parameters (for example, the surface roughness Rz of 50 μm, the interval S of the protrusions 14cv of 0.8 mm) in which the reduction of the friction coefficient is suppressed insufficiently can be avoided. In the present embodiment, the reduction of the friction coefficient can be favorably suppressed.

In the present embodiment, the material for forming the surface of the roller 10 (the material of the rubber portion 14) is EPDM. By using EPDM rather than high cost materials such as polyurethane, the cost of the roller 10 can be reduced.

In the present embodiment, the hardness of the EPDM used for the surface of the roller 10 is in the range of 30 ° or more and 50 ° or less according to JISA. Parameters of polishing (treatability) and abrasion resistance can be controlled.

2. Modification examples

Various modifications may be made to the foregoing embodiments. Specific modifications that can be applied to the foregoing embodiments will be described below. Two or more kinds of modifications arbitrarily selected from the following modifications may be combined as long as they are not contradictory to each other.

First modification

In the foregoing embodiment, an example of a case where the second condition that the protrusion aspect ratio (S/Rz) is in the range of 7.5 or more and 14 or less is satisfied is given, but the present invention is not limited in this respect.

In one example, the second condition need not be satisfied as long as the first condition is satisfied, in which (i) the initial surface roughness Rz is in the range of 50 μm or more and 80 μm or less, and (ii) the initial inter-protrusion distance S is in the range of 0.6mm or more and 0.8mm or less. Here, it is possible that the suppression of the decrease in the friction coefficient is smaller than the case where both the first condition and the second condition are satisfied. However, the suppression of the decrease in the friction coefficient is expected to be larger than the case where both the first condition and the second condition are not satisfied.

Second modification example

In the above-described embodiment and the first modification, an example is given of a case where the material of the rubber portion 14 is EPDM, but the present invention is not limited thereto. In one example, the material of the rubber portion 14 may be an elastic material other than EPDM, specifically, vinyl methyl silicone rubber (VMQ) or FKM (fluoro rubber). The material of the rubber portion 14 may use a material containing polyurethane if cost permits. In the second modification, the same effects as those of the foregoing embodiment are obtained.

Third modification example

In the above-described embodiment and the first and second modifications, an example is given of a case where the hardness of the rubber part 14 is in the range of 30 ° or more and 50 ° or less according to JISA, but the present invention is not limited in this respect. As long as the rubber portion 14 has hardness that provides wear resistance and workability. The hardness of the rubber portion 14 may be 29 ° according to JISA or 51 ° according to JISA. In the third modification, the same effects as in the foregoing embodiment are obtained.

Description of the reference numerals

10. 10Z … roller, 12 … shaft connection portion, 14 … rubber portion, 14c … concave-convex surface, 14cc … groove, 14cv … protrusion, 16 … shaft member, 100.. Load sensor, 102.. Aluminum plate, ar.. Protrusion cross-sectional area, HL... Shaft hole, PA.. Paper, rz... Surface roughness, and s.. Protrusion distance.

Claims (4)

1. A roller for feeding paper, the roller comprising:

a surface that contacts the sheet and has a plurality of protrusions and a plurality of grooves,

wherein a surface roughness representing a degree of unevenness of the surface is in a range of 50 to 80 μm, and

wherein the interval of the plurality of protrusions is in a range of 0.6mm or more and 0.8mm or less.

2. The roller as set forth in claim 1,

wherein a ratio of an interval of the plurality of protrusions to the surface roughness is in a range of 7.5 or more and 14 or less.

3. The roller according to claim 1 or 2,

wherein the material used to form the surface is Ethylene Propylene Diene Monomer (EPDM).

4. The roller as set forth in claim 3,

wherein the EPDM has a hardness in a range of 30 DEG or more and 50 DEG or less according to type A of Japanese Industrial Standard (JIS) K6253.

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