JP2001063854A - Paper feeder - Google Patents

Abstract

(57) [Problem] To provide a paper feeder capable of obtaining a sufficient separation performance for a wide range of types of paper. SOLUTION: In a paper feeding apparatus 1 provided with a paper feed roller 5 for feeding paper P, and a separation means 7 which comes into contact with the paper feed roller 5 and separates the paper P one by one, A first separation pad 11 in contact with the paper roller 5, a first support 13 for supporting the first separation pad 11, and a first support 13
A first pressure spring 15 for urging the sheet toward the paper feed roller 5,
A second separation pad 17 that comes into contact with the paper feed roller 5 downstream of the first separation pad 11 in the rotation direction of the paper feed roller 5.
A second support 19 for supporting the second separation pad 17,
A second pressure spring for urging the second support base toward the paper feed roller;

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device in an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art Generally, when a paper is fed by a paper feed roller, a support having a separation pad (friction member) is brought into pressure contact with the paper feed roller (obtains a separation pressure). There is a printer that separates and feeds sheets one by one (friction pad method). The separation force of the sheet by the separation pad is largely different between the two portions due to the difference in the drag received by the sheet when the sheet comes into contact with the separation pad.
The first is a section (pre-separation section) from the position where the leading end of the sheet comes into contact with the separation pad to the position where the paper feed roller and the separation pad enter the nip section (pre-separation section). The second is the section from the nip section entry start position. This is a section (main separation section) up to the nip center position.

The separation performance of the pre-separation unit and the main separation unit differs depending on the type of paper (strength of the paper), and the angle at which the paper enters the separation pad (the moving direction of the paper and the separation pad). ), And the separation pressure at the nip portion between the paper feed roller, the separation pad, and the nip portion (the pressure applied to the paper feed roller by the separation pad). Therefore, there is an optimum approach angle and an optimum separation pressure for each type of paper (each paper type).

[0004]

However, in the above-described paper feeder, even if the strength of the paper is different depending on the paper type in the two regions of the pre-separator and the main separator.
The entering angle of the sheet and the separation pressure on the sheet are constant.
For this reason, when the type of paper to be fed is different (when the strength of the paper is different), there is a problem that it is difficult to obtain sufficient separation performance and it is difficult to handle a wide range of paper.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeder capable of obtaining a sufficient separation performance for a wide variety of types of sheets.

[0006]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus including a sheet feeding roller for feeding a sheet, and separating means for contacting the sheet feeding roller and separating the sheets one by one. , The separating means includes: a first friction member that abuts on the paper feed roller; a first support member that supports the first friction member;
A first urging member for urging the support member toward the paper feed roller, a second friction member contacting the paper feed roller downstream of the first friction member in the rotation direction of the paper feed roller, and a second friction member And a second urging member for urging the second supporting member toward the paper feed roller.

According to the first aspect of the present invention, the paper called by the paper feed roller (moved downstream from the initial position due to the rotation of the paper feed roller) is multi-fed (in a state where two or more sheets are overlapped). In this case, the paper is separated by a first separation unit including a paper feed roller and a first friction member, and then fed while being separated by a second separation unit including a paper supply roller and a second friction member.

That is, in a section (first pre-separation section) from a contact position to the first friction member to a nip portion entry start position between the sheet feeding roller and the first friction member, the frictional force of the first friction member causes The movement of the second and subsequent sheets is prevented (separated one by one). This sheet enters the nip portion between the paper feed roller and the first friction member. If the sheet is double-fed at this time, a section from the nip entry position to the center position of the nip portion (first separation section) In, the member is separated and moves toward the second friction member.

Next, the sheet is a section (a second pre-separation section) from a contact position to the second friction member to a start position of a nip portion entry of the paper feed roller and the second friction member, and a nip from the nip entry position. Section to the center of the section (second main separation section)
Are fed while being separated.

The separating means includes first and second friction members that respectively contact different portions of the sheet feeding roller, so that the angle of entry of the sheet (the angle formed between the sheet and the first and second friction members) is reduced. Since there is a difference between the paper feed roller and the first friction member and between the paper feed roller and the second friction member, it is possible to obtain sufficient separation performance for a wide range of papers (different types of papers). it can. Also, if the urging forces of the first and second urging members are made different, the pressing force (separation pressure) of the first and second friction members against the paper feed roller can be made different, and the separation angle and the separation pressure can be reduced. The separation pressure can be made different, and a more sufficient separation pressure can be obtained corresponding to a wide range of sheets.

According to a second aspect of the present invention, in the first aspect, the pressing force of the first friction member on the sheet feeding roller is smaller than the pressing force of the second friction member on the sheet feeding roller. It is characterized by the following.

According to the second aspect of the present invention, the second aspect is provided.
In addition to the same operation and effect as the invention described in (1), when a sheet having weak stiffness is called out by the sheet feeding roller, the sheet is directed to the first separation section where the entering angle is smaller than that of the second separation section. In the first pre-separation section of the first separation section, the angle of entry of the sheet is small, and the sheet easily slides on the surface of the first separation pad from the leading end thereof, thereby receiving the sheet from the first friction member at the leading end of the sheet. Since the drag increases, the frictional force from the first friction member works sufficiently to increase the separability. Next, the paper is separated and fed by the first main separation unit and the second separation unit.

On the other hand, when a sheet having a high stiffness is called by the paper feed roller, the sheet comes into contact with the first friction member and enters the first separation member while pushing the first support member by the strength of the stiffness. It moves toward the second separating section having a large angle. The paper is separated and fed by the second separation unit.

At this time, in the second pre-separation section of the second separation section, since the entering angle of the sheet is large, the second pre-separation section of the second end of the sheet leading end is
Since the drag received from the friction member is reduced, the occurrence of non-feeding of the paper can be reduced.

That is, when the first support member is not pushed by the paper having a strong stiffness, the first friction member having a small approach angle receives a large resistance to the leading end of the paper and the paper is fed by the stiffness of the paper. Although the paper is deformed convexly toward the paper roller and causes non-feeding, in the present invention, the paper having a strong stiffness is not separated between the paper feeding roller having a small approach angle and the first friction member. By separating between the paper feed roller having a large entering angle and the second friction member, the drag applied to the leading end of the paper can be reduced, so that the non-feeding of the paper having a strong stiffness can be prevented.

The third aspect of the present invention is the first or second aspect.
In the invention described in (1), the first support member is located at a substantially central position in the width direction of the second support member.

According to the third aspect of the present invention, in the first aspect,
Alternatively, the same effect as that of the invention described in 2 can be obtained, and the separation means can be reduced in size with a simple configuration.

According to a fourth aspect of the present invention, in the third aspect of the invention, the second friction member has a comb-like shape, and the first friction member is provided between each comb-tooth portion. It is characterized by being located.

According to the fourth aspect of the present invention, there is provided the third aspect.
In addition to the same operation and effect as the invention described in the above,
By making the friction member comb-shaped, the width of the boundary between the first friction member and the second friction member can be reduced, so that even if wavy occurs in the width direction of the paper, Makes it difficult for the leading end of the sheet to be caught, thereby preventing non-feeding due to the sheet being caught.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, in the comb teeth portion of the second friction member,
A curved portion is formed at a contact portion with the leading end of the sheet.

According to the fifth aspect of the present invention, the fourth aspect
In addition to the same operation and effect as the invention described in the above,
By forming a curved portion at the corner of the comb tooth portion of the friction member,
Even if the paper undulates in the width direction, the leading end of the paper becomes more difficult to be caught and non-feeding due to the paper being caught can be further prevented.

[0022]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIGS. FIG.
FIG. 2 is a side view showing a sheet feeding device according to the present invention, and FIG.
FIG. 2 is a perspective view showing the separating means of FIG.

The paper feeder 1 is provided in an image forming apparatus (not shown) such as a copying machine, a printer, a facsimile, etc., and feeds paper toward an image forming section of the image forming apparatus. is there. As shown in FIG.
Generally includes a bottom plate 3 on which the paper P is loaded, a paper feed roller 5 for feeding the paper P, and a separating unit 7 for separating the paper P one by one.

The bottom plate 3 is provided on a paper feed tray (not shown), and the uppermost sheet of the paper P stacked on the bottom plate 3 is in contact with the paper feed roller 5. The bottom plate 3 has a compression spring 9 between the bottom plate 3 and the paper feed tray.
However, by pushing up (pressing) the bottom plate 3 toward the feed roller 5, the paper P stacked on the bottom plate 3 is pressed (pressed) against the feed roller 5.

The paper feed roller 5 is in contact with one end of the paper P in the paper feed direction and is in contact with the uppermost paper of the paper P. Paper feed roller 5
Is rotated in a direction indicated by an arrow by a driving force from a driving source (not shown), so that the uppermost sheet of the sheets P stacked on the bottom plate 3 is called and fed to the image forming unit.

As shown in FIG. 1 and FIG.
A first separation pad (first friction member) 11, a first support base (first support member) 13 to which the first separation pad 11 is attached, and the first support base 13 facing the paper feed roller 5. A first pressure spring (first biasing member) 15 for pressing (biasing);
Second separation pad (second friction member) 17 and second support base (second support member) 1 to which second separation pad 17 is attached
9 and a second pressure spring (second urging member) 21 for pressing the second support base 19 toward the paper feed roller 5.

First separation pad 11 and second separation pad 1
Numeral 7 is made of a material having a predetermined friction coefficient. When the paper P called up by the paper feed roller 5 is multi-fed (in a state where two or more papers are overlapped), the second and subsequent papers are caused by the friction. This is to prevent the movement of P. The first and second separation pads 11 and 17 are made of different materials having different friction coefficients so that the paper P
And the drag received from the second separation pads 11 and 17 can be adjusted. Note that the drag received by the paper P depends on the diameter of the paper feed roller, the friction coefficient of the separation pad, and the angle of entry of the paper P, which will be described later. If used, 100
gf (per / 50 mm paper width), and several gf in the case of using 45 kg paper P, which is a thin paper having low stiffness.
(Per 50 mm paper width).

The first support 13 is connected to a fulcrum 22 provided on the second support 19. The first support 13 is
A first pressure spring provided between a downstream end of the first support base 13 in the paper feeding direction (hereinafter, simply referred to as “downstream side”) and a downstream end of the second support base 19. Due to the urging force of 15, the first separation pad 11 is rotated around the fulcrum 20 so that the first separation pad 11 abuts (presses) on the paper feed roller 5 to obtain a separation pressure.

First separation pad 11 for paper feed roller 5
As shown in FIG. 1, the first nip portion 23 which is a press contact portion with the sheet P is located at a portion where the sheet P enters at an entry angle θ1. Further, in the present embodiment, the urging force of the first pressure spring 15 is such that the pressing force of the first separation pad 11 against the paper feed roller 5 is larger than the pressing force of the stiff paper P pressing the first separation pad 11. (Separation pressure) is set to be smaller. In the present embodiment, the first pressure spring 1
The urging force of No. 5 is set to about 50 gf (// 50 mm).

The second support table 19 is moved by the urging force of a second pressure spring 21 provided between the second support table 19 and the paper feed tray.
To the second separation pad 1
7 is pressed against the paper feed roller 5 to obtain a separation pressure. This second separation pad 17 is, as shown in FIG.
It is in pressure contact with the downstream side of the paper feed roller 5 from the first separation pad 11. In the present embodiment, the second separation pad 1
7 is applied to the first separation pad 1.
The pressure is set to be higher than the separation pressure applied to one sheet feed roller 5.

The second separation pad 17 for the feed roller 5
As shown in FIG. 1, the second nip 25, which is a press-contact portion of, is located at a portion where the sheet P enters at an entry angle θ2. Since the second nip 25 is located downstream of the first nip 23 in the rotation direction of the paper feed roller 5,
The angle of entry θ2 of the paper P into the second nip 25 is greater than the angle of entry θ1 into the first nip 23 (θ1 <θ).
2).

Here, the force acting on the sheet P will be schematically described with reference to FIG. FIG. 3 is a schematic diagram for explaining the force acting on the sheet. In general, when the sheet P comes into contact with the separation pad and the entrance angle θ of the sheet P to the separation pad is larger than the friction angle (arctan θ <1 / the coefficient of friction of the separation pad), the sheet P is convex upward. , And non-feeding occurs. The easiness of non-feeding increases as the friction angle increases, in other words, as the approach angle θ of the paper P increases.

On the other hand, when the strength of the paper P is considered, the strength of the paper P causes the paper P to bend and easily slide on the surface of the separation pad. , M), and a frictional force acts to prevent the movement. The distance La from the paper feeding position where the paper P is set to the position where the leading end of the paper P contacts the first separation pad 11 (the distance L in the case of the approach angle θ1).
a) is shorter than the distance Lb to the position where it comes into contact with the second separation pad 17 (the distance Lb in the case of the entry angle θ2).

That is, when the approach angle is θ1 <θ2, the distance La <Lb, and as the approach angle θ of the paper P increases,
Since the distance L is long, the stiffness of the sheet is weakened, and the pressing force of the sheet against the separation pad is reduced. Therefore, the ease of non-feeding of the sheet P depends on the approach angle θ and the strength of the sheet P. When the ease of non-feeding of the paper P is calculated, the approach angle θ is 30 °> 25 °> 35 °> 40 °
> 45 °.

Thus, the first separating portion 24 between the paper feed roller 5 and the first separation pad 11, the paper feed roller 5 and the second
It is desirable to set an appropriate approach angle for each of the second separation unit 26 and the separation pad 17. More specifically, the second separation unit 2
It is desirable that the approach angle at 6 is set to 40 ° to 45 °, and the approach angle at the first separation unit 24 is set to 25 ° to 30 ° in order to cope with paper P with low stiffness.

The first and second support tables 13 and 19 are
The first support base 13 is arranged so as to intersect with each other.
Upstream in the paper feeding direction (hereinafter simply referred to as “upstream”).
That. ) Is a concave portion 19 a formed at a substantially central position in the width direction at the upstream end of the second support base 19.
It is exposed from. Therefore, as shown in FIG. 2, the width L1 of the first nip portion 23 is shorter than the width L2 of the second nip portion 25 (L1 <L2). By adjusting the width L1 of the first nip 23 and the width L2 of the second nip 25 (by adjusting the nip width ratio), the first and second nips 23, It is possible to adjust the nip pressure of 25. With a simple configuration in which the first support 13 is positioned substantially at the center of the second support 19, the separation means 7
Can be reduced in size.

Next, the operation of the first embodiment based on the above configuration will be described. When the paper P having low stiffness (the above-described 45 kg paper in the present embodiment) is called by the paper feed roller 5 and the paper P is multi-fed (in a state where two or more sheets are overlapped), the first separation unit 24 is used. After being separated by
The paper is fed while being separated by the separation unit 26.

That is, when the paper P having a low stiffness is called by the paper feed roller 5, the paper P goes to the first separation unit 24 where the entering angle is smaller than that of the second separation unit 26. In the first pre-separation section of the first separation section 24 (a section from the position where the leading end of the sheet P abuts on the first separation pad 11 to the position where the sheet P starts to enter the first nip section 23), the entry angle of the sheet P Is small, the paper P easily slides on the surface of the first separation pad 11 from the leading end thereof, so that the drag received from the first separation pad 11 at the leading end of the paper increases. Therefore, the frictional force from the first separation pad 11 works sufficiently to increase the separation property, and the movement of the second and subsequent sheets is prevented (the sheets are separated one by one).

The sheet P enters the nip 23 between the paper feed roller 5 and the first separation pad 11. At this time, if the sheet P is multi-fed, the first separation section of the first separation section 24 ( First
The paper P is separated and moves toward the second separation pad 17 in a section from a position where the entry into the nip portion 23 starts to enter and a center position of the first nip portion 23). And the paper is
The second pre-separation unit of the second separation unit 26 (from the position where the leading end of the paper P contacts the second separation pad 17, the second nip 25
Section from the entry start position to the second nip portion 25) and the second main separation portion (the section from the entry start position to the second nip portion 25).
And the sheet is fed further downstream while being separated. Note that the separation effect for the paper P having a weak stiffness includes the second main separation unit, the first separation unit, and the first separation unit.
The effect is larger in the order of the pre-separator and the second pre-separator. Regarding the non-feedability, the first pre-separation unit of the first separation unit 23 has the largest drag, but for the 45 kg paper P, this drag is a few gf (around / 50 mm) and should be ignored. Can be.

Separating means 7 includes first and second separation pads 1 respectively contacting different portions of paper feed roller 5.
1 and 17, the angle of entry of the paper P is
And in the second separation sections 24 and 26,
Sufficient separation performance can be obtained for a wide range of papers (different types of papers). Further, if the urging forces of the first and second pressure springs 15 and 21 are made different, the separation pressure of the first and second separation pads 11 and 17 with respect to the paper feed roller 5 can be made different. The separation pressure can be made different, and a sufficient separation pressure can be obtained for a wide range of paper P.

On the other hand, when the paper P having strong stiffness (the above-mentioned 135 kg paper in this embodiment) P is called by the paper feed roller 5, this paper P hits the first separation pad 11 as shown in FIG. Touch As shown in FIG. 5, the paper P moves toward the second separation unit 26 having a larger entering angle than the first separation unit 24 while pressing the first support base 13 due to the strength of the paper P. Then, the sheet P is
The paper is separated by the pre-separation unit and the second main separation unit and fed further downstream.

At this time, in the second pre-separation section of the second separation section 26, since the entering angle of the sheet P is large, the drag received from the second separation pad 17 at the leading end of the sheet P is small, and The occurrence of feeding can be reduced.

That is, when the first support 13 is a sheet P
If it is not pushed, the first separation portion 24 having a small approach angle
In this case, the sheet P may be deformed convexly toward the paper feed roller 5 due to the stiffness of the sheet P and cause non-feeding. In the embodiment, the paper P having a strong stiffness is separated only by the second separation unit 26 having a large approach angle,
Since the drag applied to the leading end of the sheet can be reduced, it is possible to prevent the non-feed of the sheet P having a strong stiffness.

The effect of separating the paper P having a strong stiffness is greater in the order of the second main separation section and the second pre-separation section. In addition, in the case of replenishment of the paper P to which the paper bundle is added when the remaining amount of paper is reduced, the paper is cut at the replenishment portion, so that the coefficient of friction between the papers decreases.
Variations in the coefficient of friction between sheets increase. For example, while the normal variation is about 0.05, when the variation at the time of replenishment is about 0.2 to 0.3, the separation effect of the second pre-separation section is better than that of the second main separation section. And the separation effect in the second pre-separation section increases.

Next, another embodiment will be described. In the description, the same parts as those described above are denoted by the same reference numerals and description thereof will be omitted.

FIG. 6 is a plan view showing the separating means according to the second embodiment. In the second embodiment, the second support 19 has a comb shape, and the second separation pad 17 is attached to the second support 19 having a comb shape. The first separation pad 1 attached to the first support 13 in the form of a comb is provided between the 17
1 is different from the first embodiment.

The width of the boundary 27 between the first separation pad 11 and the second separation pad 17 can be reduced by forming the first and second support bases 13 and 19 in a comb shape. Even if the paper P with weak paper is fed, even if the paper P undulates in the width direction, the leading end of the paper P hardly gets caught in the boundary portion 27, and the non-feeding due to the paper P being caught can be prevented. .

FIG. 7 is a plan view showing the separating means according to the third embodiment, and FIG. 8 is a perspective view showing the second support table of FIG. In the third embodiment, as shown in FIGS. 7 and 8, the corner of the comb teeth 17a of the second separation pad 17 is so-called chamfered to form a curved portion 17b. different. Note that the curved portion 17b may be formed by R processing instead of chamfering.

By forming the curved portions 17b at the corners of the comb teeth 17a of the second separation pad 17, even if the paper P is wavy in the width direction, the paper P is hardly caught on the boundary portion 27. In addition, non-feeding due to paper jam can be further prevented. Also, the curved portion 17 is formed over the entire corner of the comb tooth portion 17a.
By forming b, even when a narrow paper P is fed, both side edges of the paper P are less likely to be caught by the corners of the comb teeth portion 17a, so that it is possible to cope with a paper P having a different width. it can.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the first support table 13 and the second support table 19 may be arranged at positions separated from each other, as long as the separation pad is pressed against the paper feed roller 5 at two places.

As shown in FIG. 9, the first pressure spring 1
Instead of 5, a configuration in which the first support 13 is urged in the rotation direction by a leaf spring 29 may be employed.

[0052]

According to the first aspect of the present invention, the separating means includes the first and second friction members which respectively contact different portions of the paper feed roller, so that the paper entering angle is equal to that of the paper feed roller. Since there is a difference between the first friction member and the paper feed roller and the second friction member, it is possible to obtain sufficient separation performance for a wide range of sheets (sheets of different types). Further, if the urging forces of the first and second urging members are made different, the pressing force (separation pressure) of the first and second friction members against the paper feed roller can be made different. The separation pressure can be varied, and a sufficient separation pressure can be obtained for a wide range of sheets.

According to the second aspect of the invention, the same effect as that of the first aspect of the invention is obtained, and the paper having a strong stiffness is separated between the paper feed roller having a small entering angle and the first friction member. The paper feed roller with a large approach angle and the second
By being separated from the friction member, the drag received by the leading end of the sheet can be reduced, so that the non-feeding of the sheet having a strong stiffness can be prevented.

According to the third aspect of the invention, the same effects as those of the first or second aspect of the invention can be obtained, and the size of the separating means can be reduced with a simple configuration.

According to the fourth aspect of the present invention, the same effects as those of the third aspect of the invention can be obtained, and the first and second aspects can be achieved.
By making both of the friction members comb-shaped, the width of the boundary between the first friction member and the second friction member can be reduced, so that even if waving occurs in the width direction of the paper,
The leading end of the paper is less likely to be caught on the boundary portion, and non-feeding due to the caught paper can be prevented.

According to the fifth aspect of the present invention, the same effect as that of the fourth aspect of the invention is obtained, and the curved portion is formed at the corner of the comb tooth portion of the second friction member, so that the width direction of the sheet can be improved. Even when the paper is wavy, the leading end of the paper is more difficult to be caught, and non-feeding due to the paper being caught can be further prevented.

[Brief description of the drawings]

FIG. 1 is a side view showing a sheet feeding device according to the present invention.

FIG. 2 is a perspective view showing a separating unit of FIG. 1;

FIG. 3 is a schematic diagram illustrating a force acting on a sheet.

FIG. 4 is a side view showing a state in which a sheet is in contact with a first separation pad.

FIG. 5 is a side view showing a state where a first support base is rotated by a sheet.

FIG. 6 is a plan view showing a separating unit according to a second embodiment.

FIG. 7 is a plan view showing a separating unit according to a third embodiment.

FIG. 8 is a perspective view showing a second support table of FIG. 7;

FIG. 9 is a side view illustrating a sheet feeding device according to a modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper feeder 5 Paper feed roller 7 Separation means 11 1st separation pad (1st friction member) 13 1st support base (1st support member) 15 1st pressure spring (1st biasing member) 17 2nd separation Pad (second friction member) 19 Second support base (second support member) 21 Second pressure spring (second urging member) 29 Leaf spring (first urging member)

Claims (5)

[Claims] 1. A sheet feeding apparatus comprising: a sheet feeding roller for feeding a sheet; and a separating unit that comes into contact with the sheet feeding roller and separates the sheets one by one. A first friction member, a first support member for supporting the first friction member, a first urging member for urging the first support member toward the paper feed roller, and a rotation direction of the paper feed roller from the first friction member A second friction member that abuts on the paper feed roller on the downstream side of the above, a second support member that supports the second friction member, and a second urging member that urges the second support member toward the paper feed roller. A paper feeding device, comprising: 2. The sheet feeding device according to claim 1, wherein a pressing force of the first friction member on the sheet feeding roller is smaller than a pressing force of the second friction member on the sheet feeding roller. 3. The sheet feeding device according to claim 1, wherein the first support member is located at a substantially central position in a width direction of the second support member. 4. The supply according to claim 3, wherein the second friction member has a comb-like shape, and the first friction member is located between the comb-tooth portions. Paper equipment. 5. The sheet feeding device according to claim 4, wherein a curved portion is formed at a portion of the comb tooth portion of the second friction member that abuts on a leading end of the sheet.