阅读说明：本技术 纸页类分离垫和图像形成装置 (Paper sheet separating pad and image forming apparatus ) 是由 小西宽文 西本宗宏 奥野雄大 峯章弘 市毛秀俊 于 2019-07-17 设计创作，主要内容包括：本发明提供一种纸页类分离垫以及包含该纸页类分离垫的图像形成装置,从纸粉未蓄积在接触面的使用初期起直到反复进行供纸而使纸粉蓄积在该接触面之后的长时间内,分离性能及供纸性能持续良好,能够在不会发生重送或供纸不良的情况下将纸页类持续稳定地向图像形成装置中进行供纸。纸页类分离垫(1)包含由热塑性弹性体构成的与纸页类接触的接触面(2),该接触面(2)被厚度为3μm以上的氧化膜(4)覆盖,该氧化膜(4)由上述热塑性弹性体的氧化物构成。图像形成装置包含该纸页类分离垫(1)。(The invention provides a paper sheet separating pad and an image forming apparatus including the same, which can continuously and stably feed paper sheets to an image forming apparatus without double feed or poor paper feed, and which has good separating performance and paper feed performance for a long time after paper powder is repeatedly fed from the initial stage of use until the paper powder is accumulated on a contact surface. The paper sheet separation pad (1) comprises a contact surface (2) which is formed by a thermoplastic elastomer and is in contact with the paper sheets, the contact surface (2) is covered by an oxide film (4) with the thickness of more than 3 mu m, and the oxide film (4) is formed by the oxide of the thermoplastic elastomer. The image forming apparatus includes the paper sheet separating pad (1).)

1. A paper sheet separation pad comprising a contact surface that contacts paper sheets, wherein at least the contact surface is formed of a thermoplastic elastomer and is covered with an oxide film having a thickness of 3 [ mu ] m or more, the oxide film being formed of an oxide of the thermoplastic elastomer.

2. The paper sheet separating pad according to claim 1, wherein the thermoplastic elastomer is at least one selected from the group consisting of polyester-based thermoplastic elastomers and polyurethane-based thermoplastic elastomers.

3. The paper sheet separating pad according to claim 1 or 2, wherein the thickness of the oxide film is 10 μm or less.

4. An image forming apparatus comprising the paper sheet separation pad according to any one of claims 1 to 3.

Technical Field

The present invention relates to a paper sheet separating pad constituting a paper feeding mechanism for separating a plurality of stacked paper sheets one by one and feeding them, and an image forming apparatus including the paper sheet separating pad.

Background

Image forming apparatuses such as laser printers, electrostatic copiers, plain paper facsimile machines, and multifunction machines thereof are provided with a paper feed mechanism.

The paper feeding mechanism is a mechanism for preventing so-called double feed in which paper sheets stacked and stored in a paper feeding cassette or a paper feeding tray of the image forming apparatus are erroneously fed in a state of being overlapped by 2 or more sheets, and separating and feeding the paper sheets one by one to the image forming apparatus.

The paper feeding mechanism is configured by, for example, combining a paper feeding roller and a paper sheet separation pad.

As the paper sheet separation pad constituting the paper feeding mechanism, for example, a flat paper sheet separation pad made of a thermoplastic elastomer or the like having one surface (upper surface) thereof as a contact surface with the paper feeding roller or the paper sheets is used (see patent documents 1 to 3 and the like).

The paper sheet separation pad is disposed in the vicinity of the paper feed cassette or the paper feed tray, for example, in a state where the contact surface can contact the outer peripheral surface of the paper feed roller from below the paper feed roller.

The paper feed roller is disposed above the paper feed cassette or the paper feed tray, for example, in a state in which the outer peripheral surface thereof can contact the upper surface of the uppermost 1 st paper sheet stacked and stored in the paper feed cassette or the paper feed tray and the contact surface of the paper sheet separation pad.

When the paper feed roller is rotated in a state where the outer peripheral surface is brought into contact with the upper surface of the 1 st paper sheet and the contact surface of the paper sheet separation pad by a predetermined load such as an elastic force of a spring, the 1 st paper sheet is fed from the paper feed cassette or the paper feed tray.

At this time, there are the following cases: not only the 1 st sheet but also 2 or more sheets including the 2 nd or less sheets are fed from the sheet feeding cassette or the sheet feeding tray in a stacked state.

However, among the overlapped sheets, the forward feeding of the sheets other than the 1 st sheet and not more than the 2 nd sheet which are in direct contact with the sheet feeding roller is suppressed by the frictional force of the sheet separating pad.

Then, only the 1 st sheet directly contacting the paper feed roller is separated from the 2 nd or less sheets, and the paper is fed into the image forming apparatus by the rotation of the paper feed roller.

Disclosure of Invention

Problems to be solved by the invention

The paper sheet separation pad is required to have excellent paper feed performance, which is a characteristic opposite to the above-described separation performance, in addition to excellent separation performance of the paper sheets, that is, to be able to stably feed only 1 paper sheet by rotation of the paper feed roller without causing a paper feed failure.

In addition, in the paper sheet separating pad, it is considered that the key for stabilizing the above-described separation performance and paper feed performance is: even when a plurality of sheets are continuously fed, the surface state of the contact surface, particularly the friction coefficient, does not change greatly.

However, in the actual paper sheet separating pad, there are cases where: by repeating the feeding of the paper sheets, paper dust and the like generated from the paper sheets are accumulated on the contact surface to gradually decrease the friction coefficient, and accordingly, the separation performance of the paper sheets is gradually decreased, and finally, the double feed occurs.

In addition, in order to improve the separation performance of an actual paper-sheet separation pad, the friction coefficient in the initial stage of use is often higher than the range suitable for paper-sheet feeding, and in this case, there are cases where: in particular, only 1 sheet of paper cannot be stably fed, and a paper feed failure occurs.

The invention provides a paper sheet separating pad which can continuously and stably feed paper sheets to an image forming apparatus without double feed or poor paper feed for a long time from the initial stage of use when paper dust is not accumulated on a contact surface until paper dust is accumulated on the contact surface after paper feed is repeated.

In addition, the invention aims to provide an image forming device comprising the paper sheet separation pad.

Means for solving the problems

The present invention relates to a paper sheet separation pad comprising a contact surface that contacts a paper sheet, wherein at least the contact surface is formed of a thermoplastic elastomer, and the contact surface is covered with an oxide film having a thickness of 3 μm or more, the oxide film being formed of an oxide of the thermoplastic elastomer.

The present invention also relates to an image forming apparatus including the paper sheet separating pad of the present invention.

Effects of the invention

According to the present invention, it is possible to provide a paper sheet separating pad which can continuously and stably feed paper sheets to an image forming apparatus without causing double feed or a paper feed failure, while maintaining good separation performance and paper feed performance for a long period of time from an initial stage of use when paper dust is not accumulated on a contact surface until paper dust is accumulated on the contact surface after paper feed is repeated.

Further, according to the present invention, an image forming apparatus including the paper sheet separating pad can be provided.

Drawings

Fig. 1 is a perspective view showing an appearance of an embodiment of a paper sheet separating pad according to the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of a paper feeding mechanism including the paper sheet separating pad of the present invention.

Fig. 3 (a) and (b) are diagrams illustrating a mechanism by which paper sheets can be fed or separated by a paper feed mechanism including a paper feed roller and a paper sheet separation pad.

Fig. 4 is a diagram illustrating the principle of measuring the thickness of the oxide film formed on the contact surface of the paper-sheet separation pad by the nanoindentation method.

Fig. 5 is a diagram illustrating an outline of an apparatus for performing a wear test in which an oxide film formed on a contact surface of a paper-sheet separating pad is worn by friction with paper-sheets.

Detailed Description

Separating pad for paper sheets

The paper sheet separation pad of the present invention is characterized in that at least the contact surface is formed of a thermoplastic elastomer, and the contact surface is covered with an oxide film having a thickness of 3 μm or more, the oxide film being formed of an oxide of the thermoplastic elastomer.

In the present invention, for example, the friction coefficient of the contact surface before being covered with the oxide film, which is made of a thermoplastic elastomer, is set to be higher than a range suitable for separation or feeding of paper sheets, or set to be high in a range suitable for separation or feeding of paper sheets, as in the conventional case.

The contact surface is covered with an oxide film having a small friction coefficient and a thickness of 3 μm or more, which is made of an oxide of a thermoplastic elastomer, so that the friction coefficient of the contact surface is adjusted to a range suitable for separation of paper sheets or paper feeding.

When paper feeding of paper sheets is started by rotating the paper feeding roller in this state, the oxidation film gradually wears due to friction between the paper feeding roller and the paper sheets as paper feeding is repeated, and the friction coefficient of the contact surface tends to increase.

However, since the paper dust is gradually accumulated on the contact surface in parallel with the abrasion of the oxide film, the accumulated paper dust suppresses a rapid increase in the friction coefficient, and the friction coefficient of the contact surface is maintained in a range suitable for the separation of the paper sheets or the paper feeding.

Therefore, according to the paper-sheet separating pad of the present invention, the friction coefficient of the contact surface can be maintained in a range suitable for separating paper sheets or feeding paper continuously for a long time from the initial stage of use when paper dust is not accumulated on the contact surface until paper dust is accumulated on the contact surface by repeating paper feeding.

Thus, the separation performance and the paper feeding performance can be maintained for a long period of time, and paper can be fed to the image forming apparatus stably and continuously without double feeding or paper feeding failure.

Fig. 1 is a perspective view showing an appearance of an embodiment of a paper sheet separating pad according to the present invention.

Referring to fig. 1, the entire paper-sheet separation pad 1 of this example is formed of a thermoplastic elastomer into a rectangular flat plate shape having a constant thickness, is non-porous with substantially no air bubbles inside, and has a contact surface 2 with which the paper-feeding roller and the paper-sheets come into contact.

That is, the paper-sheet separating pad 1 has a contact surface 2 and an opposite surface 3 facing away from the contact surface 2, which are provided substantially in parallel with each other, and thus has a substantially constant overall thickness.

In the paper-sheet separating pad 1, the planar shape in the surface direction from the contact surface 2 to the opposite surface 3 is rectangular, so that the entire pad has a rectangular flat plate shape.

As the thermoplastic elastomer, for example, at least one selected from the group consisting of a polyester-based thermoplastic elastomer and a polyurethane-based thermoplastic elastomer can be used.

In addition, for example, a filler such as titanium oxide or carbon black may be contained in the thermoplastic elastomer in order to adjust the hardness, the friction coefficient of the contact surface 2, and the like.

As shown enlarged in fig. 1, the contact surface 2 is covered with an oxide film 4, and the oxide film 4 is made of an oxide of the thermoplastic elastomer forming the contact surface 2.

The thickness of the oxide film 4 needs to be 3 μm or more as described above.

If the thickness of the oxide film 4 is less than this range, the above-described effect by covering the contact surface 2 with the oxide film 4, that is, the effect of suppressing double feeding or paper feeding failure by adjusting the friction coefficient of the contact surface 2 before accumulating paper dust to a range suitable for separation of paper sheets or paper feeding, is not obtained.

Therefore, particularly at the initial stage of use of the paper-sheet separating pad 1, the separating performance is insufficient and double feeding is likely to occur, or only 1 paper-sheet cannot be stably fed and a paper feeding failure is likely to occur.

On the other hand, by setting the thickness of the oxide film 4 to 3 μm or more, the friction coefficient of the contact surface 2 covered with the oxide film 4 at the initial stage of use can be adjusted to a range suitable for separation of paper sheets or paper feeding.

In particular, in the initial stage of use of the paper-sheet separating pad 1, 2 or more paper sheets can be separated well, and only 1 paper sheet can be stably fed to the image forming apparatus without causing a paper feeding failure.

As described above, by making the friction coefficient increase due to the abrasion of the oxide film 4 and the friction coefficient decrease due to the accumulation of paper dust at the time of repeated paper feeding compatible with each other, the friction coefficient of the contact surface 2 can be maintained in a range suitable for the separation of the paper sheets or the paper feeding.

Therefore, the paper sheets can be continuously and stably fed to the image forming apparatus without double feed or a paper feed failure occurring for a long time from the start of use.

The thickness of the oxide film 4 is preferably 10 μm or less in the above range.

As described later, the oxide film 4 is usually formed by irradiating the contact surface 2 made of a thermoplastic elastomer with ultraviolet rays or the like, for example, but it is not easy to form the oxide film 4 having a large thickness exceeding the above range.

That is, in order to form the oxide film 4 having a large thickness, it is necessary to increase the irradiation time of ultraviolet rays or increase the irradiation intensity, but the temperature may reach a high temperature, which may cause thermal deformation of the paper-sheet separation pad 1 or oxidation degradation to cause cracks in the contact surface 2.

In addition, the time and energy consumption required for forming the oxide film 4 increase, which also causes a reduction in productivity of the paper-sheet separating pad 1 and an increase in manufacturing cost.

In contrast, by setting the thickness of the oxide film 4 to 10 μm or less, the paper-sheet separation pad 1 can be efficiently manufactured at a low cost with good productivity without causing thermal deformation, cracks, or the like.

In the present invention, by setting the thickness of the oxide film 4 to an arbitrary value within the above range, the friction coefficient of the contact surface 2 of the paper-sheet separating pad 1 can be arbitrarily adjusted within a range suitable for separation of paper-sheets or paper feeding.

That is, the greater the thickness of the oxide film 4 within the above range, the smaller the friction coefficient of the contact surface 2 of the paper-sheet separating pad 1 can be; conversely, the smaller the thickness of the oxide film 4, the larger the friction coefficient of the contact surface 2 can be.

The paper sheet separation pad 1 is manufactured by molding a thermoplastic elastomer into a sheet shape, irradiating one surface of the contact surface 2 with ultraviolet rays, oxidizing the thermoplastic elastomer exposed on the one surface to form an oxide film 4, and then cutting the oxide film into a rectangular shape or the like.

In order to set the thickness of the oxide film formed on the contact surface 2 within the above range, for example, the cumulative light amount of the ultraviolet rays irradiated to one surface of the contact surface 2 may be adjusted.

The cumulative light amount is obtained by a product of the irradiation intensity per unit area of the ultraviolet light irradiated to one surface of the contact surface 2 and the irradiation time, and is a total light amount of the ultraviolet light irradiated to the one surface.

The thickness of the oxide film 4 can be increased as the accumulated light amount is increased.

The range of the accumulated light amount may be set according to the kind of the thermoplastic elastomer constituting the contact surface 2, and the likeIn any range, considering that the contact surface 2 is covered with the oxide film 4 having a thickness of 3 μm, the cumulative light amount is preferably 50mJ/cm²Above, particularly preferably 200mJ/cm²The above.

Wherein the accumulated light amount is preferably 1000mJ/cm in this range²The concentration is preferably 500mJ/cm²The following.

Even if the cumulative light amount exceeds this range, the above effect cannot be obtained, and in addition, when the oxide film 4 is formed by irradiation with ultraviolet rays, as described above, the temperature may become high, and thermal deformation of the paper-sheet separation pad 1 may easily occur, or oxidation degradation may occur, and cracks may occur in the contact surface 2.

On the other hand, by setting the cumulative light amount to the above range, the contact surface 2 can be covered with the oxide film having a thickness of 3 μm or more without causing thermal deformation, cracks, or the like, and the initial friction coefficient of the contact surface can be reduced.

Fig. 2 is a schematic cross-sectional view showing an example of a paper feeding mechanism incorporating the paper-sheet separation pad of the present invention.

Referring to fig. 1 and 2, the paper feeding mechanism 5 of this example includes a paper feeding roller 7 having at least an outer peripheral surface 6 formed of rubber or the like, and the paper-sheet separating pad 1 of the present invention.

The paper-sheet separation pad 1 is disposed in the vicinity of a paper feed cassette or a paper feed tray, not shown, with the contact surface 2 facing the outer peripheral surface 6 of the paper feed roller 7 from below the paper feed roller 7.

The paper feed roller 7 is disposed above the paper feed cassette or the paper feed tray in a state where the outer peripheral surface 6 can contact the upper surface of the uppermost 1 st paper sheet P stacked and stored in the paper feed cassette or the paper feed tray and the contact surface 2 of the paper sheet separation pad 1.

Examples of the rubber forming the outer circumferential surface 6 of the paper feed roller 7 include ethylene propylene rubber (EPDM) and the like.

In order to feed paper to the image forming apparatus by using the paper feed mechanism 5 of the above example, as shown in fig. 2, a predetermined load is applied by an elastic force of a spring or the like to bring the outer peripheral surface 6 of the paper feed roller 7 into contact with the upper surface of the 1 st paper sheet P and the contact surface 2 of the paper sheet separation pad 1.

Therefore, for example, the spring may be provided on the paper feed roller 7 side, on the paper feed cassette or the paper feed tray side, and on the paper sheet separation pad 1 side.

The springs may be provided on the paper feed roller 7 side, the paper feed cassette or the paper feed tray side, and the paper sheet separation pad 1 side, respectively.

The paper feed roller 7 in the contact state is rotated in a direction indicated by an arrow of a one-dot chain line in the figure.

In this way, the uppermost 1 st sheet P contacted by the outer peripheral surface 6 of the sheet feeding roller 7 is fed out from the sheet feeding cassette or the sheet feeding tray as indicated by the solid arrow in the figure as the sheet feeding roller 7 rotates.

At this time, as described above, the paper sheets may be fed from the paper feed cassette or the paper feed tray in a double feed state, that is, in a state where 2 sheets or 3 sheets are overlapped, and in this case, the forward feed of the paper sheets P of the 2 nd or less is suppressed by the friction force of the contact surface 2 of the paper sheet separation pad 1.

Therefore, only the 1 st sheet directly contacting the outer peripheral surface 6 of the paper feed roller 7 is separated from the 2 nd or less sheet and fed into the image forming apparatus.

Fig. 3 (a) and (b) are diagrams illustrating a mechanism by which paper sheets can be fed or separated by a paper feed mechanism including a paper feed roller and a paper sheet separation pad.

In these figures, the friction coefficient of the outer peripheral surface 6 of the paper feed roller 7 with respect to the paper sheets P is μ R, the friction coefficient of the contact surface 2 of the paper sheet separation pad 1 with respect to the paper sheets P is μ S, the friction coefficient between the 2 paper sheets P stacked on top of each other is μ P, and the load for bringing the outer peripheral surface 6 of the paper feed roller 7 into contact with the contact surface 2 of the paper sheet separation pad 1 is F.

In the drawings, white arrows indicate the feeding direction of the paper sheets P.

First, referring to fig. 3 (a), when only 1 sheet of paper P is fed between the outer peripheral surface 6 of the paper feed roller 7 and the contact surface 2 of the paper separation pad 1, a frictional force μ R × F is generated between the outer peripheral surface 6 of the paper feed roller 7 and the sheet of paper P in accordance with the rotation of the paper feed roller 7 as indicated by an arrow of a one-dot chain line in the figure.

In this state, a frictional force μ S × F is generated between the paper sheet P and the contact surface 2 of the paper sheet separating pad 1.

In this case, even if the friction coefficients μ R and μ S differ by a small amount, or μ R ═ μ S, or μ R < μ S, the paper feeding failure of the paper sheet P may occur.

That is, since the frictional force μ R × F is equal to or smaller than the frictional force μ S × F, the paper sheets P cannot be smoothly fed at a predetermined speed or cannot be fed at all.

On the other hand, if μ R > μ S and μ R is sufficiently large, the frictional force μ R × F can be made significantly larger than the frictional force μ S × F.

Therefore, the paper-sheets P can be smoothly fed into the image forming apparatus at a predetermined speed as indicated by white arrows in the figure against the frictional force μ S × F in accordance with the rotation of the paper feed roller 7.

As described above, in the present invention, the contact surface 2 of the paper-sheet separating pad 1 is covered with the oxide film 4 at the initial stage of use, and the paper dust is gradually accumulated in parallel with the progress of the wear of the oxide film 4, whereby the rapid increase in the friction coefficient μ S can be suppressed.

Therefore, the above-described conditions can be satisfied by combining the paper sheet separation pad 1 with the paper feed roller 7, and the paper feed roller 7 is formed of rubber such as EPDM on the outer circumferential surface 6, and the friction coefficient μ R with respect to the paper sheets P is significantly larger than the friction coefficient μ S.

That is, if μ R > μ S can be set and μ R is sufficiently large, the paper-sheets P can be smoothly fed to the image forming apparatus at a predetermined speed in accordance with the rotation of the paper-feeding roller 7.

Referring to fig. 3 (b), when 2 sheets of paper P are stacked and fed between the outer peripheral surface 6 of the paper feed roller 7 and the contact surface 2 of the paper separation pad 1, a frictional force μ P × F is generated between the stacked sheets of paper P as the paper feed roller 7 rotates as indicated by an arrow of a single-dot chain line in the figure.

In the same manner as described above, a frictional force μ R × F is generated between the outer peripheral surface 6 of the paper feed roller 7 and the paper sheets P, and a frictional force μ S × F is generated between the paper sheets P and the contact surface 2 of the paper sheet separation pad 1.

However, the friction coefficient μ P between the paper sheets is generally smaller than the friction coefficient μ R with respect to the outer peripheral surface 6 of the paper feed roller 7 made of rubber and the friction coefficient μ S with respect to the contact surface 2 of the paper sheet separation pad 1 made of a thermoplastic elastomer.

Therefore, the friction force μ P × F between the paper sheets is also smaller than the friction forces μ R × F and μ S × F.

Thus, when the paper feed roller 7 is rotated, the 1 st (upper side in the figure) paper-sheet P directly contacting the outer peripheral surface 6 of the paper feed roller 7 is fed out to the image forming apparatus as indicated by the white arrow in the figure.

However, as described above, the coefficient of friction μ S with respect to the contact surface 2 of the paper sheet separation pad 1 is larger than the coefficient of friction μ P between the paper sheets P (μ P < μ S) with respect to the 2 nd paper sheet P (lower side in the figure) which is in direct contact with the contact surface 2, and thus the feeding forward is suppressed.

As a result, only the 1 st sheet P and the 2 nd sheet P are separated from each other, and the sheet is fed into the image forming apparatus by the rotation of the sheet feed roller 7.

The behavior of the 2 nd sheet P after the 1 st sheet P is fed is shown in fig. 3 (a).

That is, with respect to only 1 sheet P of the 2 nd sheet, since the frictional force μ R × F is significantly larger than the frictional force μ S × F at the time of the next sheet feeding, the sheet can be smoothly fed into the image forming apparatus at a predetermined speed with the rotation of the sheet feeding roller 7.

In addition, as the paper sheet P, generally, a substantially homogeneous paper sheet is repeatedly used.

Therefore, even if a plurality of sheets of paper-sheets P are stacked and fed between the outer peripheral surface 6 of the paper-feed roller 7 and the contact surface 2 of the paper-sheet separation pad 1, the friction coefficient μ P and the friction force μ P × F between the paper-sheets P in direct contact are substantially constant.

Therefore, although the figure shows a case where 2 sheets of paper sheets P are stacked, even in a case where 3 or more sheets of paper sheets P are stacked, the behavior of each sheet P is the same.

In order to set the friction coefficient μ S of the contact surface 2 of the paper sheet separating pad 1 so as to satisfy the above-described relationship, the type of the thermoplastic elastomer, the amount of the filler contained, the thickness of the oxide film 4 covering the contact surface 2, and the like may be adjusted.

The specific range of the friction coefficient μ S of the contact surface 2 of the paper sheet separating pad 1 may be set to any range that satisfies the above relationship.

The range can be set arbitrarily according to the rotation speed of the paper feed roller 7 combined with the paper-sheet separation pad 1, the material of the outer circumferential surface 6, the load applied when the contact surface 2 of the paper-sheet separation pad 1 is brought into contact with the outer circumferential surface 6 of the paper feed roller 7, the type of paper-sheet, and the like.

For example, according to the study of the inventors, the friction coefficient μ S of the contact surface 2 of the paper-sheet separating pad 1, which is combined with the paper feed roller 7 having the outer peripheral surface 6 made of rubber such as EPDM, for feeding plain paper as the paper-sheets P, is preferably in a range of 0.55 to 0.80.

The friction coefficient of the contact surface 2 made of the thermoplastic elastomer, which is not covered with the oxide film 4 and to which the paper powder is not attached, is usually about 0.86 to 0.90.

Therefore, in the paper sheet separation pad 1 used in combination with the paper feed roller 7 and the paper sheets P, the friction coefficient μ S of the contact surface 2 covered with the oxide film 4 in the initial stage of use is preferably set to the range of 0.55 to 0.80.

If the friction coefficient μ S is less than this range, the paper sheet separating performance is insufficient, and particularly, the paper sheet separating pad 1 may be repeatedly fed at the initial stage of use.

As described above, the friction coefficient μ S of the contact surface 2 and the thickness of the oxide film 4 have a correlation, and in order to make the friction coefficient μ S smaller than the above range, the thickness of the oxide film 4 needs to be increased to be larger than the above range.

Therefore, when the oxide film 4 is formed by irradiation with ultraviolet rays, the temperature may reach a high temperature, which may cause thermal deformation of the paper-sheet separation pad 1 or oxidation degradation to cause cracks in the contact surface 2.

In addition, the time and energy consumption required for forming the oxide film 4 increase, which also causes a reduction in productivity of the paper-sheet separating pad 1 and an increase in manufacturing cost.

On the other hand, if the friction coefficient μ S is larger than the above range, it is difficult to stably feed only 1 sheet of paper particularly in the initial stage of use of the paper-sheet separating pad 1, and a paper feed failure is likely to occur.

On the other hand, when the friction coefficient μ S of the contact surface 2 covered with the oxide film 4 with respect to the plain paper as the paper-sheets P is within the above range, the occurrence of double feed or paper feed failure can be suppressed particularly at the initial stage of use of the paper-sheet separating pad 1.

Further, by making a balance between an increase in the friction coefficient due to abrasion of the oxide film 4 and a decrease in the friction coefficient due to accumulation of paper dust when paper is repeatedly fed, the friction coefficient μ S of the contact surface 2 with respect to the plain paper, which is the paper sheet P, can be maintained within the above-described appropriate range for a long period of time.

That is, the friction coefficient μ S of the contact surface 2 on which the paper powder is accumulated with respect to the plain paper, which is a paper sheet, can be maintained in the range of 0.05 to 0.80 instead of the abrasion of the oxide film 4 when the paper is repeatedly fed.

Therefore, the paper sheets can be continuously and stably fed to the image forming apparatus without double feed or a paper feed failure occurring for a long time from the start of use.

The thickness, planar shape, and the like of the paper sheet separating pad 1 can be set as appropriate according to the shape, structure, and the like of the image forming apparatus in which the paper sheet separating pad 1 is incorporated.

Among them, the thickness of the paper sheet separation pad 1 is preferably 0.5mm or more, particularly preferably 1.0mm or more, preferably 1.5mm or less, and particularly preferably 1.2mm or less, in view of suppressing the generation of chatter sound at the time of paper feeding and also separating paper sheets well.

In the illustrated example, the paper-sheet separating pad 1 is formed of a thermoplastic elastomer and has a single-layer structure, but the paper-sheet separating pad may be formed of a thermoplastic elastomer and has a laminated structure of 2 or more layers including a surface layer whose contact surface is covered with an oxide film.

< image Forming apparatus >

The image forming apparatus of the present invention is characterized by including the paper sheet separating pad of the present invention.

Specifically, the image forming apparatus of the present invention is configured by mounting a paper feeding mechanism configured by combining the paper sheet separating pad of the present invention with a paper feeding roller or the like shown in fig. 2.

As described above, the image forming apparatus of the present invention includes various image forming apparatuses using an electrophotographic method, such as a laser printer, an electrostatic copier, a plain paper facsimile machine, or a multifunction machine thereof.