JPH10181912A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed a cut sheet stably surely separated one by one regardless of a different kind of the cut sheets, in a paper feeder. SOLUTION: In a friction surface of a friction member extended in a delivery route by a paper feed roller 31 of a loaded cut sheet 11, a static friction coefficient to general superior paper is set to 1.0 to 1.5, so as to generate sufficient friction contact when displaced into contact with a tip end part of the delivered cut sheet 11, so that the cut sheet 11 can be separated surely one by one.

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 for sequentially feeding and feeding a stacked cut sheet from one side thereof by a feed roller contacting the cut sheet, and more particularly, to a cantilever extending in a cut sheet feeding path. The present invention relates to a sheet feeding device that separates cut sheets one by one by frictional contact when a friction member comes into contact with a leading end portion of a cut-out sheet to be fed and is displaced, thereby preventing double feeding. It is used for feeding a recording sheet or a document in a printer, a facsimile, or the like, feeding a document for an image reading apparatus, and in various other cases in which a plurality of stacked cut sheets are fed out one by one and used.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 7-196186 discloses such a sheet feeding device. This conventional device is shown in FIG.
Cut sheet b loaded on paper feed tray a as shown in
A friction member e that extends from below in a feed-out path by the paper feed roller c, and has a lower end pivotally supported by a shaft d to undulate.
This comes into contact with the entire width of the leading end of the cut sheet b that is fed out each time the paper feed roller c makes one rotation, and resists the urging of the restoring spring f and is displaced as shown by the phantom line in FIG. Cut sheet b fed out by 1
Separate the sheets one by one so that they can be fed one by one without double feeding.

The angle α between the friction surface of the friction member e and the uppermost surface of the cut sheet b is set in a range of 85 to 55 degrees so that the friction member e can be surely separated by the friction.

The above publication also discloses a friction member made of an elastic sheet provided with its lower end fixed under the same angle conditions as described above.

[0005]

By the way, fine adjustment is required for separating the cut sheet by the friction member as described above. According to experiments by the present inventors, when the cut sheet advances while pushing away the friction member, it is better to weaken the restoring force of the friction member to the initial position so that the friction member does not receive residual deformation. In order to surely separate the cut sheets, it is better to increase the restoring force so as to increase the frictional force between them. These are incompatible and difficult to set in a well-balanced manner. In addition, since the cut sheet is easy to bend, that is, the stiffness differs depending on the paper quality and thickness, the friction resistance received from the same friction member varies, and the separation performance also varies.

The friction member e disclosed in the above publication is disposed at a downstream position in the sheet feeding direction relatively far from a nip position where the sheet feeding roller c contacts and feeds out the cut sheet b. The cut sheet b which is fed out and abuts against the friction member e and is separated while buckling due to the frictional contact with the friction member e is provided with a large degree of freedom of deformation between the nip portion of the feed roller c and the friction member. When the friction member e passes through while being pushed away, the friction member e is inclined and easily escapes from the friction member e, so that the cut sheet b of any thickness is hardly subjected to residual deformation.

However, in such a conventional apparatus, the separation performance of the cut sheet b is unstable, and double feed sometimes occurs. Since the friction member e of the conventional device has only a uniform friction surface in the frictional contact direction of the cut sheet b, the front end of the cut sheet b approaches the front end while pushing away the friction member e, so that the slippery contact is made. The cut sheet b may be slipped off the friction member e before the cut sheet b is sufficiently separated, and may come off in a double feed state before the cut sheet b is sufficiently separated. Although the setting of the angle somewhat suppresses this, it is insufficient, and double feed is particularly likely to occur in a cut sheet b having a weak stiffness due to paper quality and thinness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeder capable of reliably separating sheets one by one and feeding sheets stably regardless of the type of cut sheet.

[0009]

In order to achieve the above object, according to the present invention, there is provided a sheet feeding device comprising: a sheet feeding roller which comes into contact with a stacked cut sheet from one side thereof and sequentially feeds the cut sheet; , The cantilever friction that separates the cut sheets one by one by frictional contact when the cut sheets extend from the other side of the loaded cut sheet to the cut sheet feeding path and come into contact with the leading end of the cut sheet and are pushed away. A friction coefficient of the friction surface of the friction member with general high-quality paper is set to 1.0 to 1.5.

In such a configuration, the leading end of the cut sheet fed by the paper feed roller abuts against the friction member and advances while pushing away the friction member, but the leading end of the cut sheet moves toward the leading end of the friction member. However, the contact angle of the friction member with the friction surface gradually decreases. However, the static friction of the friction surface with respect to general high-quality paper is set to 1.0 to 1.5. Sufficient contact friction is given until the portion comes off the tip of the friction member, so that the sheet can be reliably separated and fed one by one regardless of the type of cut sheet.

The friction surface is preferably formed by coating a urethane resin, and can be easily coated by silk printing.

If the area ratio of the coated portion of the urethane resin to the non-coated portion changes in the direction of frictional contact of the friction member with the cut sheet, the leading end of the cut sheet moves from the base side to the tip side of the friction member. A satisfactory coefficient of friction can be set for each position at the time of shifting to, and the separation characteristics for various cut sheets are further improved.

In this case, it is preferable that the area ratio of the urethane resin coated portion is set to be larger toward the tip of the friction member in order to exert a sufficient separating function up to the tip of the friction member. When the coating portion of the urethane resin is formed in a V-shape or an inverted V-shape to form a stripe pattern arranged with a change in density and thickness in a frictional contact direction with the cut sheet to achieve the above condition, It is easy to change the area ratio of the cut sheet continuously in a symmetrical state, and the effective separation of the cut sheet can be continuously advanced from the base side to the tip of the friction member in a well-balanced left and right direction, further improving the separation characteristics. .

The friction member is made of an elastic sheet, and includes first and second friction members having different friction coefficients of friction surfaces, and the second friction member is arranged side by side or flush with the first friction member. If it is provided so as to overlap the middle part from the base side,
First and second friction surfaces having different predetermined friction coefficients.
When the friction member of the cut sheet shares the friction surface in contact with the front end of the cut sheet in the left-right direction or the friction contact direction with the cut sheet, the front end of the cut sheet moves from the base side of the friction member to the front end. The required coefficient of friction can be satisfied compositely according to each position, and it is easy to cope with the separation of various cut sheets.

If the second friction member is provided so as to be able to adjust the position in the direction of frictional contact with the cut sheet, the position adjustment can variously set the composite friction coefficient with the first friction member. It can be changed, and it is convenient and easy to respond to the separation of various cut sheets.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sheet feeding device according to an embodiment of the present invention.

(Embodiment 1) Embodiment 1 is shown in FIGS.
FIG. 4 illustrates a case of the sheet feeding device 1 that feeds a recording sheet by a copying machine as illustrated in FIG. The copying machine is of a digital type, and the scanning optical system 2 scans a document placed manually on a platen glass or automatically sent by a document feeder (not shown). The scanned image is formed on the image sensor 4 of the image reading unit 3 and converted into an electric image signal. This image signal is sent to the print head 5, and the print head 5 emits a laser beam 6 modulated by the image signal to the photosensitive drum 7 to perform image exposure.

The photosensitive drum 7 is located substantially at the center of the copying machine main body 10, and its surface is uniformly charged by a charging brush 8 for the image exposure. The electrostatic latent image formed by the image exposure on the charged surface of the photosensitive drum 7 is developed by the developing unit 9 with a toner to become a visible image. This visible image is transferred to the cut sheet 11 sent from the paper feeding device 1 or the like by the transfer roller 12 or the like. The cut sheet 11 after the transfer is sent to a fixing device 13 and subjected to a fixing process. Thereafter, the cut sheet 11 is discharged to a discharge tray 15 directly or by a discharge roller 14.

In the main body 10 of the copying machine, a paper feeder 16 for feeding a fixed or regular cut sheet 11 is provided at the bottom or the like. The paper feeding device 16 includes a paper feeding cassette 17 that can be taken in and out, and a paper feeding cassette 1 that is mounted.
And a paper feed roller 18 in the copying machine main body 10 for feeding out the cut sheet 11 in the main body 7. The paper feeder 1 is shown as being used as a so-called manual paper feeder, and is provided so as to protrude from the side of the copier main body 10. Thus, a plurality of cut sheets 11 of paper quality and size not prepared in the copying machine main body 10 can be stacked as needed, or one sheet can be placed and fed.

The sheet feeder 1 is used for a cut sheet 11 to be used.
3, the left and right side guides 22 provided on the paper feed tray 21 can be adjusted in position according to the width of the cut sheet 11 as shown in FIG. The left and right side guides 22 are interlocked by an interlocking gear 23 provided in the sheet feeding tray 21, and feed the cut sheets 11 of any size by so-called centering type positioning in which the center is adjusted to the same position.

Such a manual paper feeder 1 is used for postcards,
Various cut sheets 11 other than paper, for example, a resin sheet for an overhead projector, or a sheet of thinner paper than plain paper are often used. In some cases unexpected types of cut sheets 11
Is sometimes used.

The paper feeder 1 is an auxiliary device that is used less frequently, and a small and simple paper feed mechanism is desired, but a paper feed performance capable of handling various cut sheets 11 is required. In the first embodiment, as shown in FIGS. 1 to 3, the sheet feeding device 1 is
A simple separation method using a friction member 33 that hinders the advancement of the next lower cut sheet 11 that is to be double-fed to the outermost cut sheet 11 by the frictional contact at that time while being pushed away by the cut sheet 11 fed out In addition, a stable sheet feeding performance can be exhibited for various cut sheets 11. However,
The paper feeder of the present invention can be similarly applied to a usual paper feeder of a copying machine, and can also be applied to automatically feed a document. As described above, the present invention can be applied to a machine other than a copying machine.

The paper feed roller 31 of the paper feeder 1 is provided on the copying machine main body 10 side. Paper feed tray 2 of paper feeder 1
1 is a cut sheet 11 fed from the paper feeding device 16
And extends slightly obliquely upward from a base 36 having an outer guide 35 of a paper passing path 34 for receiving the photosensitive drum 7 toward the photosensitive drum 7, and the base 36 is hinged to the copying machine main body 10 at a side (not shown). The rotation of the paper feed tray 21 around the hinge connection part and the paper feed path 3
4 can be opened and closed for jam processing and the like.

The paper feed tray 21 has a push-up plate 26 pivotally supported at its rear end by a shaft 24 and urged upward by a spring 25.
1 is pressed against the paper feed roller 31 and the paper feed roller 31 is rotated, so that the outermost surface is
In the first embodiment, the uppermost cut sheet 11 can be fed and fed. The surface of the paper feed roller 31 is made of rubber such as EPDM, for example, and has an appropriate frictional force.
However, it is not limited to this.

The paper feed roller 31 has a substantially half-moon shape, and its notch faces the cut sheet 11 when paper is not fed, and its outer peripheral portion is rotated once during paper feed and has no cut. , The cut sheet 11 is sent out. When the sheet is not fed, the cam 31b, which rotates in synchronization with the sheet feeding roller 31, comes into contact with the cam follower 26a of the push-up plate 26 to push down the push-up plate 26 against the spring 25. The sheet 11 is largely separated from the sheet feeding roller 31 so that the cut sheet 11 can be easily loaded or pulled out by hand until the sheet 11 comes into contact with the predetermined position of the sheet feeding tray 21, that is, the friction member 33 only during non-sheet feeding. .

When the paper feed roller 31 starts rotating at the time of paper feeding, the cam 31b is disengaged from the cam follower 26a at the same time or slightly later when the notch portion does not face the cut sheet 11, so that the push-up plate 26 becomes free. The cut sheet 11 is pressed against the outer diameter surface of the sheet feed roller 31 that has begun to be rotated by the bias of the spring 25 so that sheet feeding is performed.

The friction member 33 of the first embodiment is made of an elastic sheet material. When the cut sheet 11 is fed out by the paper feed roller 31, it is elastically bent and deformed and pushed away. The cut sheets 11 are separated one by one, and the sheet feed roller 31 contacts the uppermost surface of the stacked cut sheets 11 and feeds out the sheet. The cut sheet 11 extends from the lowermost side of the sheet 11 to the feeding path 30 of the cut sheet 11.

Here, the mechanism of separation by the friction member 33 will be considered. The actual separating mechanism is a combination of the movement in which the cantilevered friction member 33 is pushed away by the cut sheet 11 and the partial buckling of the cut sheet 11. This will be described below in principle and qualitatively for the sake of simplicity.

Now, as shown in FIG. 5A, a condition is considered in which the cut sheet 11 which is about to advance by the force F receives a frictional force on the friction surface 33a of the friction member 33 and is balanced.
Mu _B coefficient of friction with respect to the cut sheet 11 of the friction surface 33a of the friction member 33, when the contact angle theta (fixed value in this case), when Fcosθ = μ _B · Fsinθ ...... (1), because commensurate, mu _B · tan .theta <1 (cut sheet 11 _{proceeds.) ...... (2) μ B} · tanθ ≧ 1 ( cut sheet 11 is stopped.) (3) the relationship is established. Shows the critical value of the contact angle θ traveling cut sheet 11 is slipped on the range of suitable friction coefficient mu _B in FIG. 6 (b).

In principle, from the above equations (2) and (3),
Whether the progression of the cut sheet 11 regardless of the force F, are to be understood as determined only by the friction coefficient mu _B and contact angle theta. Therefore, assuming that the friction coefficient μ _B does not change, the cut sheet 1
It is necessary to make a difference in the contact angle θ between the outermost cut sheet 11 and the next lower cut sheet 11 with respect to the friction surface 33a in order to loosen 1. That is, separation by the friction member 33 means to drive the contact angle θ of only the outermost cut sheet 11 from the stop area of the cut sheet 11 to the advancing area.

However, normally, the outermost surface of the cut sheet 11 is very close to the lowermost one, and is in a state of close contact. It is considered that there is almost no difference in the angle θ.

While the friction member 33 is pushed away by the cut sheet 11 fed by the paper feed roller 31, the frictional contact at that time causes the outermost cut sheet 11 to move to the next or lower position as shown in FIG. 2B. Buckled larger than the cut sheet 11, and the cut sheet 1 on the outermost surface
1 so that the contact angle θ of the first cut sheet 11 is significantly smaller than the contact angle θ of the cut sheet 11 at the next position or lower, and the cut sheet 11 is separated into individual sheets.
Only the cut sheet 11 passing therethrough and the next lower cut sheet 11 is stopped to prevent double feeding.

However, in practice, the cut sheet is easy to bend depending on the paper quality and thickness, that is, the strength of the stiffness differs, and the cut sheet 11 fed out by the feed roller 31 is moved by the friction member 33. It is difficult to reliably separate and handle without undergoing residual deformation.

In the first embodiment, the friction member 33 is made of, for example, a polycarbonate film, and has a thickness of about 200 μm, which is a commercially available product, so that a suitable restoring force for loosening the cut sheet 11 can be obtained. The friction surface 33a has a necessary friction coefficient obtained by coating the surface of the polycarbonate film with a material having a large friction coefficient such as urethane resin. The friction surface 33a preferably has a static friction coefficient of about 1.0 to 1.5 with respect to general high-quality paper. Further, it is preferable to set the angle between the friction surface 33a and the outermost cut sheet 11 to 90 degrees to 120 degrees. In the first embodiment, the friction surface 33a under the above conditions was easily obtained by performing a thermosetting treatment at about 80 ° C. for about 30 minutes after coding the polyurethane resin by silk printing with about 200 mesh.

Thus, while the leading end of the cut sheet 11 fed by the paper feed roller 31 abuts against the friction member 33 and advances while pushing away the same, the leading end of the cut sheet 11 moves toward the leading end of the friction member 33. With the shift, the contact angle between the friction member 33 and the friction surface 33a is changed as shown in FIG.
(B), as shown in FIG. 1B, the frictional surface 33 gradually decreases as θ ₁ to θ _3. Sufficient contact friction is given until the leading end of the sheet 11 comes off the leading end of the friction member 33.
Regardless of the type, one sheet can be reliably separated and fed stably.

Here, as shown in FIG. 2A, the area ratio of the urethane resin coated portion 33a1 to the non-coated portion 33a2 changes in the direction of frictional contact of the friction member 33 with the cut sheet 11. Therefore, a satisfactory friction coefficient can be set for each position when the leading end of the cut sheet 11 shifts from the base side to the leading end side of the friction member 33, and the separation characteristics for various cut sheets 11 can be further improved. improves.

If the change in the area ratio is set to be larger toward the tip of the friction member 33 as in the first embodiment shown in FIG. It is suitable for exhibiting a sufficient separating function to the leading end, and the urethane resin coating portion 33a1 is formed in a V shape or an inverted V shape as shown in FIG. If the area ratio is changed by forming a stripe pattern having a change in density or thickness, the area ratio of the coating portion 33a1 is easily changed continuously in a symmetrical state, and the friction member 33 is formed. The effective separation of the cut sheet 11 can be continuously progressed from the base side to the front end with good left-right balance, and the separation characteristics are further improved.

The change in the area ratio is that the total contact friction μ ₁ , μ ₂ , and μ ₃ in the entire width of each part of the cut sheet 11 and the friction surface 33a is 1 / μ ₁ = tan θ ₁ 1 / μ ₂ = Tan θ ₂ 1 / μ _{2 It} is preferable that the setting is made so as to satisfy = tan θ ₂ .

Further, in the first embodiment, the friction member 33
As shown in FIG. 1, the friction surface 33a is located inside the outer diameter of the paper feed roller 31, so that the paper feed roller 31 comes into contact with the cut sheet 11 and feeds from the nip position N. The distance of the friction member 33 to the friction surface 33a is extremely small as compared with the above-described conventional example. Therefore, the cut sheet 11 between the nip position N and the friction surface 33a is not required.
Of the friction surface 33
Since the sheet is easily received by the friction of a, the sheet can be easily separated, the separating performance can be improved, and high-speed sheet feeding can be performed. The setting of the angle of the friction member 33 has provided a good result.

One cut sheet 11 is fed out by one rotation of the paper feed roller 31, and the rear end of the cut sheet 11 is moved to the nip position N.
Is released, the friction member 33 is released from the pressing by the cut sheet 11 fed and becomes free, so that it returns to the original state. At this time, the cut sheet 1 fed
The cut sheet 11 below the second order that was to be multi-fed to 1,
It is possible to prevent the friction member 33 from being pushed back to the original position by the returning force, and to prevent the next sheet feeding from being disturbed, and the angle setting of the friction member 33 can be easily performed. Adapted and convenient.

(Embodiment 2) This embodiment 2 is shown in FIG.
As shown in FIG. 7, the friction member 33 is made of an elastic sheet, and has different friction coefficients of the friction surfaces.
3A and 33B, the second friction member 33A is provided so that a predetermined number of the second friction members 33A are alternately arranged side by side in a state flush with the first friction member 33B. Of course, it is preferable for the arrangement state to be symmetrical in terms of the left-right balance of the separation characteristics, but the number of arrangements and arrangement states are arbitrary.

As described above, the first and second friction members 33A, 33A whose friction surfaces 33a are set to predetermined different friction coefficients are used.
3B is a friction surface 3 that is in contact with the front end of the cut sheet 11.
3a are shared in the left-right direction, and the required friction coefficient can be complexly satisfied according to each position when the leading end of the cut sheet 11 shifts from the base side to the leading end of the friction member 33. It is easy to cope with separation of the cut sheet 11.
In this case, although not shown, the first and second friction members 33 are provided.
The frictional surfaces 33a of A and 33B are also provided with a coat portion as in the first embodiment after having different friction coefficients, and the area ratio of the coat portion is the same as in the first embodiment. It is also suitable as being changed.

Further, for example, the main first friction member 33A having a long contact friction range with the cut sheet 11 is fixed by bonding the common base portion 33A1 into the slit 37a of the support wall 37 or the like. The sub second friction member 33B having a short contact friction range has a common base 33B.
1 is screwed and fixed with a screw 53 facing the slit 37a from the back, and the position can be adjusted in the direction of contact friction by loosening the screw 53.

Thus, by adjusting the position in accordance with environmental conditions such as moisture which greatly affects the type and separation characteristics of the cut sheet 11, the share ratio of the friction surface 33a by the second friction member 33B can be changed and adjusted appropriately. It is possible to exhibit excellent separation characteristics.

This position adjustment changes the degree of contact friction with the cut sheet 11, and the same effect can be obtained by changing the angle between the cut sheet 11 and the cut sheet. It is effective to adjust the position of one friction member 33 in the same manner as in the first embodiment.

Since other structures, functions and effects are the same as those of the first embodiment, the same members and portions are denoted by the same reference characters and overlapping drawings and descriptions are omitted.

In the first and second embodiments, the friction member 33
Is described only in the case where the elastic sheet is an elastic sheet. However, the present invention is not limited to this, and the present invention can be similarly applied to a rigid body which is rotatably supported by a base and provided with a restoring force by a spring.

(Embodiment 3) This embodiment 3 is shown in FIG.
As shown in FIG. 9, the second friction member 33B is
The first and second friction members 33A and 33B are provided so as to overlap the middle portion from the front base side of the friction member 33A, and the friction surfaces 33a are set to predetermined different friction coefficients.
The friction surface 33a that contacts the front end of the cut sheet 11 is
It is possible to share in the direction of contact friction with the cut sheet 11 and complexly satisfy the required coefficient of friction according to each position when the leading end of the cut sheet 11 moves from the base side to the leading end of the friction member 33. It is easy to cope with separation of various cut sheets 11.

The friction surfaces 33a of the first and second friction members 33A and 33B are provided with a coating portion 33a1 after having different friction coefficients. These two coats 3
It is preferable that the area ratio of 3a1 is changed as in the first embodiment.

In addition, for example, the long main first friction member 33A is fixed by bonding it in the slit 37a of the support wall 37, while the short sub second friction member 33A is fixed.
B is screwed and fixed to the slit 37a with a screw 53 facing from the back, and the position can be adjusted in the direction of contact friction by loosening the screw 53.

Thus, the position of the cut sheet 11 is adjusted in accordance with environmental conditions such as humidity, which greatly affects the type and separation characteristics of the cut sheet 11, so that the share of the friction surface 33a by the second friction member 33B can be changed to adjust the position. It is possible to exhibit excellent separation characteristics.

This position adjustment changes the degree of the contact friction with the cut sheet 11, and the same applies to the case where the angle between the cut sheet 11 and the first and second friction members 33A and 33B is changed. Has the effect.

Since other structures, functions and effects are the same as those of the first embodiment, the same members and portions are denoted by the same reference characters and overlapping drawings and descriptions are omitted.

(Embodiment 4) Embodiment 4 is similar to FIG.
As shown in FIG. 5, a friction member 33 having a urethane resin coat similar to that of the first embodiment but not applied to the friction surface 33a is bonded to the support wall 37 or the like, as in the case of the first embodiment. Although provided so as to be located within the outer diameter of the paper feed roller 31, the cut sheet 11 fed out along the outer diameter of the paper feed roller 31 is provided on the back of the friction member 33 in the next paper passing path of the feeding path 30. The third embodiment differs from the first to fourth embodiments in that a guide 72 for guiding the sheet 71 to be fed is provided.

As a result, the cut sheet 11 fed out by the paper feed roller 31 advances while pushing away the friction member 33.
The cut sheet 11 itself is limited until it comes into contact with the guide 72, and the cut sheet 11 itself is strongly contacted with the friction surface 33 a of the friction member 33 due to the reaction force due to the forced change of direction by the guide 72. Since the sheet is oriented along 33a, the sheet can be smoothly pulled out first, and the separation performance is high, and the inconvenience that the cut sheet 11 is hardly fed or not fed does not occur.

Further, in each of the above-described first to fourth embodiments, the paper feeder 1 of the top-up type has been described. Can be applied. Although the center alignment method has been described, skew is unlikely to occur even if the cut sheet 11 acts on a biased position if there are a plurality of paper feed rollers 31. Therefore, the configuration of Embodiment 1 is also applied to the one-side alignment method. can do.

In any case, the first paper feed roller 31A
A plurality of at least one of the second friction member 33A and the paper feed roller 31 and the friction member 33 can be appropriately arranged.

[0058]

According to the present invention, while the leading end of the cut sheet fed by the paper feed roller abuts against the friction member and advances while pushing it away, the leading end of the cut sheet moves toward the leading end of the friction member. With the shift, the contact angle of the friction member with the friction surface gradually decreases. However, since the friction surface is set to have a static friction against general high-quality paper of 1.0 to 1.5, the cut sheet is Sufficient contact friction is given until the leading end of the sheet comes off the leading end of the friction member, so that the sheet can be reliably separated and fed one by one regardless of the type of cut sheet.

The friction surface is preferably formed by coating a urethane resin, and can be easily coated by silk printing.

When the area ratio of the coated portion of the urethane resin to the non-coated portion changes in the direction of frictional contact of the friction member with the cut sheet, the front end of the cut sheet moves from the base side to the front end side of the friction member. A satisfactory coefficient of friction can be set for each position at the time of shifting to, and the separation characteristics for various cut sheets are further improved.

In this case, it is preferable that the area ratio of the urethane resin coated portion is set to be larger toward the tip of the friction member in order to exert a sufficient separating function up to the tip of the friction member. When the coating portion of the urethane resin is formed in a V-shape or an inverted V-shape to form a stripe pattern arranged with a change in density and thickness in a frictional contact direction with the cut sheet to achieve the above condition, It is easy to change the area ratio of the cut sheet continuously in a symmetrical state, and the effective separation of the cut sheet can be continuously advanced from the base side to the tip of the friction member in a well-balanced left and right direction, further improving the separation characteristics. .

The friction member is made of an elastic sheet, and includes first and second friction members having different friction coefficients on the friction surface, and the second friction member is arranged side by side or in front of the first friction member. If it is provided so as to overlap the middle part from the base side,
First and second friction surfaces having different predetermined friction coefficients.
When the friction member of the cut sheet shares the friction surface in contact with the front end of the cut sheet in the left-right direction or the friction contact direction with the cut sheet, the front end of the cut sheet moves from the base side of the friction member to the front end. The required coefficient of friction can be satisfied compositely according to each position, and it is easy to cope with the separation of various cut sheets.

When the second friction member is provided so as to be able to adjust the position in the direction of frictional contact with the cut sheet, this position adjustment allows various settings of the composite friction coefficient with the first friction member. It can be changed, and it is convenient and easy to respond to the separation of various cut sheets.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of a sheet feeding device according to a first embodiment of the present invention.

FIGS. 2A and 2B show a main part of the sheet feeding device of FIG. 1, wherein FIG. 2A is a front view and FIG.

FIG. 3 is a sectional view showing the entire sheet feeding device of FIG. 1;

FIG. 4 is a schematic configuration diagram of a copying machine having the paper feeding device of FIG. 1;

5A and 5B are explanatory views illustrating the principle of separation of cut sheets by a friction member to which the present invention is applied.
(B) is a graph which shows the boundary conditions of a stop and advancing when a cut sheet contacts a friction member.

FIG. 6 is a perspective view of a main part of a sheet feeding device according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a main part of the sheet feeding device of FIG. 6;

FIG. 8 is a perspective view of a main part of a sheet feeding device according to a third embodiment of the present invention.

FIG. 9 is a sectional view of a main part of the sheet feeding device of FIG. 8;

FIG. 10 is a sectional view of a main part of a sheet feeding device according to a fourth embodiment of the present invention.

FIG. 11 is a cross-sectional view of a main part showing a conventional sheet feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper feeder 10 Copier main body 11 Cut sheet 21 Paper feed tray 26 Push-up plate 30 Feeding-out path 31 Paper feed roller 33 Friction member 33a Friction surface 33a1 Coat part 33a2 Non-coat part 33A First friction member 33B Second friction Member 37 Support wall

Claims (7)

[Claims] A sheet feed roller which comes into contact with the stacked cut sheets from one side thereof and sequentially feeds the cut sheets; and a cut sheet which extends from the other side of the stacked cut sheets to a cut sheet feeding path and feeds the cut sheets. In a paper feeder provided with a cantilevered friction member that separates cut sheets one by one by frictional contact when the front end portion is pushed away, the friction surface of the friction member has a coefficient of static friction with general high quality paper. Is 1.
A sheet feeding device characterized by being set to 0 to 1.5. 2. The paper feeding device according to claim 1, wherein the friction surface is formed by coating a urethane resin. 3. The paper feeder according to claim 2, wherein the area ratio of the urethane resin coated portion to the non-coated portion changes in the direction of frictional contact of the friction member with the cut sheet. 4. The sheet feeding device according to claim 3, wherein the area ratio of the urethane resin coated portion increases toward the tip of the friction member. 5. The coated portion of the urethane resin is formed in a V-shape or an inverted V-shape, and is formed in a stripe pattern arranged with a change in density and thickness in a direction of frictional contact with a cut sheet. The sheet feeding device according to any one of the above. 6. The friction member is made of an elastic sheet and includes first and second friction members having different friction coefficients of friction surfaces.
3. The sheet feeding device according to claim 1, wherein the friction member is provided so as to be arranged side by side with the first friction member or to overlap an intermediate portion from the front base side. 4. 7. The sheet feeding device according to claim 6, wherein the second friction member is provided so as to be able to adjust a position in a friction contact direction with the cut sheet.