JP2003040473A - Paper separating and feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve paper separating performance of a paper separating and feeding device for supplying a paper in a top position from a plurality of papers loaded in a paper container onto a paper feeding path. SOLUTION: A plurality of feed rollers 3 are provided on a feed shaft 7 and a plurality of separation belts are provided on a reverse shaft 81 on a downstream side. The separation belt is a belt which travels to circulate so that frictional force in a direction for returning the paper to a side of the paper container is exerted to the paper. The feed rollers and the separation belts are positioned alternately in a shaft direction of the feed shaft, and a part of the respective feed rollers and separation belts are overlapped each other. At least one of a pair of rotating shaft bodies stretching the separation belts across is a reverse shaft, a diameter of the rotating shaft body which is closer to a nip part of the paper out of the pair of the rotating shaft bodies is not longer than one-quarter of a diameter of the feed rollers, and friction coefficient μbetween the paper and the separation belt is less than the friction coefficient between the paper and the feed roller. Furthermore, positional relation of the separation belt to the feed roller is set so that a tip end of the paper from the feed roller abuts on a part, which stretches evenly, of the separation belt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet separating / feeding apparatus for feeding the uppermost sheet from a plurality of sheets stacked in a sheet container to a sheet feeding path, and a sheet separating / feeding apparatus provided with the sheet separating / feeding apparatus. The present invention relates to an image forming apparatus such as a copying machine, a printer, and a printing machine.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 11-322104 discloses
As a paper separating apparatus that solves the problems of the paper separating apparatus disclosed in Japanese Patent Laid-Open No. 54-24104, even if the lower paper superposed by the paper feeding means is the first paper, the lower paper It is disclosed that the conveyance abnormality can be prevented by feeding the paper back by rotating the separation roller. This paper separating device is characterized in that a feed roller and a separation roller are provided, and a paper guide member for guiding the leading end of the paper sent by the paper feeding means to the separation roller side.

As described above, the invention disclosed in Japanese Patent Laid-Open No. 11-322104 is likely to occur when two sheets of paper are fed out and the leading edge of the lower sheet is ahead of the leading edge of the uppermost sheet. This is an invention for suppressing feeding (delivering two sheets without separating them). However, if the paper feed cassette containing the paper is left in an environment where the temperature and humidity change, curling or the like may occur at the leading end of the paper depending on the type of paper. Therefore, in the present invention, the leading edge of the sheet may hit the feed roller side first instead of the separating roller side, and the sheet separating function is not always satisfactory.

Therefore, the inventor of the present invention has disclosed in Japanese Patent Laid-Open No. 11-3221.
In order to improve the separation performance of the paper separating device described in Japanese Patent Publication No. 04-04, the overlap amount L between the feed roller 3 and the separating roller 85 which constitutes the paper separating device shown in FIG.
An experiment was conducted by changing the diameter of the separation roller 85 to be from mm to 1.1 mm, and it was found that the separation performance of the paper P is improved by reducing the diameter. The results of this experiment are summarized in FIG. It should be noted that when the reference numerals shown in FIG. 10 are described, 7 is a feed shaft (feed rotation shaft), 1
Reference numeral 1 is a cylindrical member, 21 is a relay shaft, and 34 is a support plate. The reverse shaft (reverse rotation shaft) 81 rotates the separation roller 85 in the direction opposite to the feed roller 3.

The vertical axis of FIG. 11 is the "separation performance ratio" defined below. That is, the magnitude of the force pressing the paper P against the feed roller from below is changed between the case of using the separation roller (diameter 16 mm) provided in the conventional apparatus and the case of using the separation roller of this experiment. The maximum value within the range where the paper was not double fed was calculated. Then, the ratio (Ta / Tb) of the maximum value Ta in the case of using the separation roller of this experiment to the maximum value Ta in the case of the conventional separation roller was defined as "separation performance ratio". The larger the “separation performance ratio”, the more reliably the paper can be fed without double feeding. Figure 1
As shown in FIG. 1, when the diameter of the feed roller was fixed to 32 mm and the diameter of the separation roller was reduced from 16 mm to smaller than this, it was found that the separation performance sharply increased from the separation roller diameter of 8 mm. At this time, the diameter of the separation roller is 1/4 of the diameter of the feed roller.

However, if the diameter of the separating roller 85 is too small, it becomes difficult to guide the leading edge of the sheet to the nip portion between the feed roller 3 and the separating roller 85, and in some cases, the contact angle of the leading edge of the sheet with respect to the surface of the separating roller 85. Becomes steep (the angle between the lower surface of the leading edge of the sheet and the surface of the separation roller 85 is large), and the frequency of non-feeding increases. In FIG. 10, when the diameter of the separation roller 85 is 1/4 of the diameter of the feed roller 3,
It can be seen that the leading edge of the sheet comes into contact with the separation roller 85 at an angle close to vertical.

Further, in the paper separating apparatus disclosed in Japanese Patent Laid-Open No. 11-322104, it is necessary to arrange a pickup roller on the upstream side of the feed roller in order to pre-feed the paper to the nip portion. There was a problem that the cost was high. Separation roller 8 as shown in FIG.
Although the pickup roller can be omitted by reducing the diameter of 5, the same side effect as described above occurs.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the invention according to claim 1 is to set a sheet located at the top of a plurality of sheets stacked in a sheet container. In the sheet separating / feeding device configured to feed onto the sheet feeding path, the diameter of the separating roller is set in order to preferentially feed the uppermost sheet (improving the sheet separating performance) when the sheets are fed by stacking two sheets. The purpose is to reduce the paper non-feeding that tends to occur when the value is reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the sheet can be fed without buckling, and the sheet separating / feeding can accurately and continuously continue the feeding operation. The purpose is to provide a device.

An object of the invention according to claim 3 is to provide a sheet separating / feeding device according to the invention of claim 1 or 2 which can perform a sheet feeding operation without using a pickup roller. The object of the invention of claim 4 is to claim 1 or 2
In the invention described above, it is to suppress a change in the sheet separation / feeding performance due to the abrasion of the sheet feeding member accompanying the feeding operation. An object of the invention of claim 5 is to enable the invention of claim 1 or 2 to be implemented even when the separation belt is made of a thin material. It is an object of the invention of claim 6 to provide a sheet separating / feeding device further improving the sheet separating function in the invention of claim 5. It is an object of the invention of claim 7 in the invention of claim 1 or 2 to improve the reliability of the paper feeding operation by preventing the edge of the paper from coming into contact with the paper guide member or the like.

An object of the invention according to claim 8 is to provide a sheet separating / feeding device which can be operated at a low cost at low cost by providing a separating member which does not require operating energy and exhibits the same effect as the separating belt. Especially.

The object of the invention of claim 9 is, in the invention of claim 8, the sheet separation, which allows the sheet to be fed without buckling, and allows an accurate feeding operation to be continued stably. The purpose is to provide a feeding device.
It is an object of the invention of claim 10 to provide a sheet separating / feeding device further improving the sheet separating function in the invention of claim 8 or 9.

The objects of the invention of claim 11 are:
(EN) A high-performance image forming apparatus provided with any one of the sheet separation and feeding devices of No. 0.

[0014]

The invention according to claim 1 is
A plurality of feed rollers arranged on a common feed rotation axis (feed axis) and a plurality of feed rollers arranged on the common reverse rotation axis (reverse axis) on the downstream side (downstream side in the paper conveyance direction) of which can be circulated. An endless separation belt, and the uppermost paper is sent out from a plurality of papers stacked in a paper container by rotation of a feed roller, and the paper is sandwiched by the feed roller and the separation belt. A sheet separating / feeding device configured to supply a sheet onto a sheet feeding path while being in contact with a conveying unit (a nip portion between the feed roller and the separating belt).
The feed rollers and the separation belts are alternately arranged in the axial direction of the common feed rotation axis of the feed rollers, and a part of each of the feed rollers and the separation belt overlaps each other.
The separation belt is a belt that travels so as to exert a frictional force on the paper in a direction to return the paper to the paper container side, and at least one of a pair of rotary shafts that hangs the separation belt is the reverse rotary shaft, In addition, the diameter of the rotary shaft closer to the paper sandwiching / conveying portion of the pair of rotary shafts is 1/4 or less of the diameter of the feed roller, and the coefficient of friction between the paper and the separation belt is The position of the separation belt relative to the feed roller is set so that the friction coefficient between the rollers is lower and the leading edge of the paper sent from the feed roller contacts the flatly stretched portion of the separation belt. It is a characteristic sheet separating and feeding device.

The invention according to claim 2 is based on claim 1
A paper separating / feeding device characterized in that the following relationship is established between the angle θ formed by the separation belt with the lower surface of the paper fed by the rotation of the feed roller and the friction coefficient μ between the paper and the separation belt. Is.

[0016]

## EQU3 ## tan θ <1 / μ (1)

The invention according to claim 3 is the invention according to claim 1 or 2.
In the above, the paper container is a paper tray for stacking paper on a vertically movable bottom plate, and the bottom plate is loaded in the paper tray by a force in a direction of rising toward the feed roller side by a biasing mechanism. The paper is characterized in that the positional relationship of the feed roller with respect to the paper tray is set so that the vicinity of the tip of the uppermost paper of the plurality of papers can contact the feed roller with a predetermined pressure contact force. It is a separate feeding device.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the above, the sheet separating / feeding device is characterized in that both widthwise ends of the feed roller and both widthwise ends of the separation belt are rounded with a radius of 0.2 mm or more.

The invention according to claim 5 is claim 1 or 2
At the width of both ends of the feed roller at a radius of 0.2 m
A sheet separating / feeding device having a roundness of m or more, a diameter larger than that of the reverse rotation shaft, a cylindrical member for inheriting the separation belt, and an end radius of 0.2 mm or more. It is a device.

According to a sixth aspect of the present invention, in the fifth aspect, the friction coefficient between the sheet and the separation belt is μ, the friction coefficient between the sheet and the cylindrical member is μB, and the friction coefficient between the sheet and the feed roller is μF. In this case, the paper separating and feeding device is characterized in that μF> μB ≧ μ.

The invention according to claim 7 is the invention according to claim 1 or 2.
In the above, the distance between the plurality of feed rollers arranged on the feed rotation axis is such that the distance between the feed roller located at the axial end of the feed rotation axis and the feed roller inside the feed roller is between the other feed rollers. The sheet separating and feeding device is characterized in that it is larger than the interval.

The invention according to claim 8 is provided with a plurality of feed rollers arranged on a common feed rotation shaft, and a plurality of separation members fixedly arranged on a common fixed shaft on the downstream side of the feed roller. The uppermost sheet is sent out from the plurality of sheets stacked in the container by the rotation of the feed roller, and the sheet is fed onto the sheet feeding path while being in contact with the sheet sandwiching and conveying section composed of the feed roller and the separating member. In the sheet separating / feeding device, the feed rollers and the separating members are alternately arranged in the axial direction of the common feed rotation shaft of the feed rollers, and the feed rollers and the separating members are respectively arranged. Partially overlap each other, and the separating member has a flat inclined surface,
The coefficient of friction between the separating belts is lower than the coefficient of friction between the paper and the feed rollers, and the positional relationship of the separating members with respect to the feed rollers is such that the leading edge of the paper sent from the feed rollers contacts the inclined surface of the separating member. The sheet separating / feeding device is set so that when the sheet comes into contact with the inclined surface, the inclined surface exerts a force in a direction to return the sheet to the sheet container side. Is.

According to a ninth aspect of the present invention, between the angle θ formed by the lower surface of the leading edge of the sheet sent from the feed roller and the inclined surface of the separating member in the eighth aspect, and the friction coefficient μa between the sheet and the inclined surface. The paper separating and feeding device is characterized in that the following relationships are established.

[0024]

## EQU4 ## tan θ <1 / μa (2)

According to a tenth aspect of the present invention, in the eighth or ninth aspect, the friction coefficient between the paper and the feed roller is μF,
When the friction coefficient of the inclined surface is μC and the friction coefficient of the overlapping portion is μD, μF> μD ≧ μC.

The invention of claim 11 relates to claims 1 to 10.
An image forming apparatus comprising the sheet separating / feeding device described in any one of 1.

The inventions of claims 8 and 9 are preferably configured as follows. (1) As described in claim 3, the paper container is a paper tray for stacking paper on a vertically movable bottom plate, and the bottom plate has a direction in which the paper container is raised toward the feed roller by an urging mechanism. Position of the feed roller relative to the paper tray so that the vicinity of the tip of the uppermost paper among the plurality of sheets stacked in the paper tray can be contacted with the feed roller with a predetermined pressure contact force when a force is applied. A paper separating and feeding device characterized in that a relationship is set,
(2) As described in claim 4, both ends in the width direction of the feed roller and both ends in the width direction of the separating member are rounded with a radius of 0.2 mm or more, (3) The claim 7. As described above, in the interval between the plurality of feed rollers arranged on the feed rotation axis, the distance between the feed roller located at the axial end of the feed rotation axis and the feed roller inside the feed roller is determined by the other feed rollers. Be larger than the distance between the rollers.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment (Claim 1) FIG. 1 is a sectional view of a sheet separating / feeding device (sheet separating device), and FIG. FIG. 3 and FIG. 3 are explanatory diagrams showing a connected state of the drive device attached to the side plate and the gear.

As shown in FIG. 2, a plurality of feed rollers 3
And a plurality of separation belts (reverse belts) 84 are arranged alternately in the axial direction of the respective drive shafts (feed shaft 7, reverse shaft 81). Further, as shown in FIGS. 1 and 2, a part of the separation belt 84 overlaps the feed roller 3, and the overlap amount L is about 0.4.
It is set within a range of up to 1.1 mm. Feed roller 3
Is an axial direction of the cylindrical member 11 attached to the feed shaft 7 by press-fitting at least two ring portions 3a made of a rubber material, for example, EP rubber, having a friction coefficient larger than that of the paper sheets. It is configured by mounting the same at predetermined intervals. The feed shaft 7 is rotatably supported by the side plates 9 and 10. The feed roller 3 is rotationally driven in the paper feeding direction by the drive gear and the feed gear meshing with each other being rotated by a drive means described later.

The separation belt 84 is stretched over the cylindrical member 82 attached to the reverse shaft 81 and the support shaft 83 under tension, and is arranged alternately with the feed roller 3 as described above. . Here, the support shaft 83 is rotationally driven by the drive gear 20 via the reverse gear 27, and rotates in the same direction as the feed roller 3. It is important that the friction coefficient of the separating belt 84 with respect to the paper is lower than the friction coefficient of the feed roller 3 with respect to the paper. Further, the separation belt 84 and the shaft (cylindrical member 82 and support shaft 83) that spans the separation belt 84 are
A support plate 34 that is freely rotatable by the relay shaft 21 on the side plates 9 and 10.
It is rotatably supported by. Further, the spring 50 is attached between the support plate 34 and the side plate 9 with both ends thereof fixed. For example, when thick paper enters the nip portion, if the deformation of the paper is forced by the overlap amount, the sheet is not fed. The spring 50 has a function of adjusting the maximum pressing force of the overlap portion.

In the paper tray 1, a large number of paper sheets P are stacked on the bottom plate 41. The bottom plate 41 controls an elevating mechanism (not shown) including a spring and a motor to feed the paper P to the feed roller 3 at 50 to 600 gf (about 490 to about 5).
It is pressed in contact with a pressing force of 880 mN. As a result, the feed roller 3 also serves as a pickup roller.
In FIG. 3, reference numeral 25 is a driving means and reference numeral 26 is a feed gear.

In the paper separating apparatus having the structure shown in FIG. 10, when the diameter of the separating roller 85 is reduced, the curvature of the surface of the separating roller with which the leading end of the paper comes into contact increases, so that the paper is curled. In some cases, when a so-called “stiff” paper is used, the fluctuation range (temporal fluctuation) of the angle formed by the lower surface of the leading edge of the paper and the separation roller becomes very large. Further, since this angle tends to be close to 90 °, there is a problem that a conveyance abnormality is likely to occur.

On the other hand, in the sheet separating apparatus of the present embodiment, the portion where the leading edge of the sheet contacts, that is, the separation belt 8
The radius of curvature of the surface of No. 4 can be made very large, and it is also easy to form it substantially infinitely (planar shape).
Further, even when the paper is curled to some extent or a so-called "stiff" paper is used, the fluctuation range of the angle formed by the lower surface of the leading end of the paper and the separation belt is not so large. For this reason, even if the lower sheet that has been superposed and fed first comes out first, the upper sheet can be reliably prioritized and fed onto the sheet feeding path by feeding the lower sheet backward.

The material of the entire separation belt or the surface layer of the separation belt is mainly rubber, but the material is not limited to this and may be a plastic material or a metal material having a friction coefficient lower than that of rubber, or a cloth material. It is also possible to have a structure in which a plastic material is applied to the surface. In addition, the surface friction (of the surface that contacts the paper) may be adjusted by surface treatment (roughening, plating, etc.).

Second Embodiment (Claim 2) The overall structure of the sheet separating / feeding device of the present embodiment is basically the same as that of the first embodiment. Therefore, the sectional view of the apparatus is the same as that of FIG. 1, the schematic view of the nip portion viewed from the sheet feeding side is the same as that of FIG. 2, and the connection state of the driving device attached to the side plate and the gear is the same as that of FIG. Therefore, no duplicate explanation will be given.

FIG. 4 is an explanatory view showing the basic structure of the sheet separating / feeding apparatus according to this embodiment. This figure shows the relationship of the forces acting when the front end of the paper P that has moved to the right in the drawing comes into contact with the separation belt 84, and the symbol θ represents the angle between the paper (the lower surface of the front end) and the separation belt 84. Code R
Is the vertical drag force on the surface of the separation belt, the symbol μ is the coefficient of friction between the paper and the separation belt 84, the symbol μR is the static friction force along the surface of the separation belt, and the symbol F is the normal force R and the static friction force μ.
It is the result of R. As is clear from this figure, a force that pushes the sheet P back toward the resultant force F acts on the leading edge of the sheet P. That is, the separation belt 84 acts as a reverse belt.

FIG. 4 shows the case of tan θ = 1 / μ,
In this case, the resultant force acting on the paper from the separation belt is opposite to the traveling direction of the paper, so that the paper P buckles. tan θ> 1 /
In the case of μ as well, the resultant force similarly acting on the sheet is downward, so that the sheet buckles. Only when tan θ <1 / μ, the sheet is conveyed to the nip portion between the feed roller 3 and the separation belt 84. That is, the resultant force acting on the paper is upward,
The sheet of paper rises along the separation belt 84 and is guided to the nip portion. Therefore, by changing the friction coefficient μ between the paper / separation belt 84 and the angle θ formed by the paper and the separation belt so that tan θ <1 / μ holds, buckling of the paper is prevented and this is ensured. It can be supplied on the feed path.

As is clear from the above inequality: tan θ <1 / μ, the range in which θ can be taken varies depending on the value of μ,
The smaller is, the larger θ can be taken. The advantage of the large θ is that the overlapping portion (nip portion) can be arranged on the upstream side in the sheet feeding path. If .theta. Is small, the overlapping part will be separated from the paper and will be closer to the downstream side. In this case, since the paper is deformed in the overlapping portion so as to undulate in the direction perpendicular to the transport direction, wrinkles and the like are likely to occur on the paper.

Third Embodiment (Claim 4) FIG. 5 is a front view of a feed roller 3 and a separation belt 84 which form the nip portion of the sheet separating / feeding apparatus. Since both widthwise end portions of the feed roller 3 and the separation belt 84 are made of rubber, they are slightly worn during use and their operating characteristics change. In the present embodiment, in order to solve this problem, both ends of the feed roller 3 and the separation belt 84 in the width direction (corners on the left and right sides of the drawing) are rounded with a radius of 0.2 mm or more in advance. According to the present embodiment, even if the above members are worn to some extent, the operating characteristics at the initial stage of use can be maintained as they are. The corners may be chamfered instead of being rounded as shown in FIG. For rounding, a method of cutting a corner portion or a method of filling a prefabricated mold with raw material rubber and solidifying it can be adopted. In addition,
When the separation belt is rounded as described above, this belt needs to have a certain thickness, and therefore it is important to select the material of the separation belt in consideration of this point.

That is, when the belt material selected is thinner than the radius of the roundness, as shown in FIG. 6, a cylindrical member 82 having a diameter larger than that of the reverse shaft 81 and inheriting the separation belt 84 is provided. It is desirable that the end radius of the cylindrical member 82 be 0.2 mm or more. The cylindrical member 82 has a step 82a at the portion where the separation belt 84 runs. At the overlap portion, the sheet and the cylindrical member 82 are in contact with each other, and the edge portion thereof is rounded. With such a structure, even when a thin material is used as the material of the separation belt 84, the separation belt 8
Radius 0.2mm at both widthwise ends of 4 (corners on the left and right of the drawing)
The same effect as when the above roundness is provided is obtained.

Further, in this embodiment, the coefficient of friction between the sheet and the separation belt is μ, and the coefficient of friction between the sheet and the cylindrical member is μ.
B, when the friction coefficient between the paper and the feed roller is μF, it is desirable that μF> μB ≧ μ. By doing so, θ can be increased and the friction coefficient of the overlapping portion can be increased, so that the separation performance of the paper sheet is further improved. In this case, a plastic sheet or a metal sheet may be used as the separation belt, or a sheet having a surface layer formed by applying a polymer material onto a base material such as cloth may be used. The cylindrical member may be made of a plastic material or a metal material having a roughened surface to increase the friction coefficient, or a rubber material.

Fourth Embodiment (Claim 7) FIG. 7 is a front view showing an arrangement of a plurality of feed rollers 3 forming a nip portion of a sheet separating / feeding device. The distance between the plurality of feed rollers arranged on the feed shaft (feed rotation shaft) 7 is a distance D between the feed roller positioned at the axial end of the feed shaft and the feed roller inside the feed roller.
However, it is larger than the distance d between the other feed rollers. Since the separation belts and the feed rollers are alternately arranged as shown in FIG. 2, when the distance D is narrow, the paper nipped in the nip portion is large at the axial end portion of the feed shaft of the nip portion. Since the sheet has an inclination, the edge of the sheet may come into contact with a sheet guide member (not shown). The present embodiment eliminates this problem.

Fifth Embodiment (according to claim 8) FIG. 8 is an explanatory view showing a main configuration of a sheet separating / feeding apparatus. In this embodiment, a separating member 84a in the shape of a separating belt is provided instead of the separating belt. As shown in FIG. 4, the surface of the separating member 84a that comes into contact with the leading edge of the paper is a flat inclined surface made of rubber. The function and effect of the separating member 84a is the separating belt 84 shown in FIG. It is almost the same as that of
Moreover, no operating power is required. The separating member 84a only needs to be formed of rubber at the portion that comes into contact with the paper, and the material of the other portions does not matter. Further, instead of the separating member 84a in FIG. 8, it is possible to provide a separating member having a very simple structure in which the surface of the inclined plate is covered with rubber, for example.

The material of the entire separating member 84a or the surface layer thereof is mainly rubber, but the material is not limited to this, and may be a plastic material or a metal material having a lower friction coefficient than rubber, or a cloth. It is also possible to have a structure in which a plastic material is applied to the surface of the. In addition, the surface friction (of the surface that contacts the paper) may be adjusted by surface treatment (roughening, plating, etc.).

In the present embodiment, when the friction coefficient between the paper and the feed roller is μF, the friction coefficient of the inclined surface is μC, and the friction coefficient of the overlap portion is μD, μF> μD ≧ μC. It is desirable to configure. By doing so, the above θ can be made large. In addition, since the friction coefficient of the overlapping portion is high, the frictional force between the back surface of the paper and the inclined surface becomes large, and the paper separation performance becomes higher. In this case, in the separating member 84a, the inclined surface (the surface layer with which the paper contacts) is formed of a plastic plate or a metal plate, or the inclined surface is formed by attaching a plastic sheet or a metal sheet on a rubber base material. Can be formed. Further, the constituent materials of the feed roller and the overlap portion and the surface treatment method thereof can be selected in consideration of the friction coefficient of the inclined surface of the separating member, and the surface is roughened or a rubber material is adopted. Therefore, it is possible to increase the friction coefficient. In the separating member 84a, it is desirable that the inclined surface portion is projected more outward than the other portions, so that the sheet can be more reliably brought into contact with the inclined surface portion.

Sixth Embodiment (Claim 11) FIG. 9 shows an electrophotographic image forming apparatus including the sheet separating / feeding apparatus according to the first to fifth embodiments. It is a structure explanatory view. Therefore, in this image forming apparatus, it is possible to reliably and stably perform the sheet separating and feeding operation. Numeral 101 shown in FIG. 9 is a fixing roller.
110 is a fixing unit, 141 is a photoconductor, 142 is a charging roller, 143 is a mirror, 143 is a developing device, 144a is a developing roller, 146 is a cleaning unit, 146a is a blade, 147 is a transfer unit, 148 is a transfer member, 149 is a The registration roller 250 is an exposure unit, and the paper P is discharged from the image forming apparatus after the development image is transferred and then the image is fixed while the paper P travels along the path indicated by the broken line.

[0047]

As is apparent from the above description, according to the present invention, the following effects can be obtained. (1) Invention of Claim 1 The sheet separating and feeding apparatus of the present invention is a separation belt system in which the separation roller provided in the conventional apparatus is downsized. By using such a separation belt, the radius of curvature of the overlap portion (the portion for separating the upper and lower sheets that have been superposed and fed) can be reduced without causing the above-mentioned side effect.
It is possible to reduce the size, and thereby the separating performance of the upper and lower sheets can be improved. That is, even if the diameter of the roller around which the separation belt is stretched is reduced, the leading edge of the paper is brought into contact with the roller surface having a small radius of curvature (large curvature), unlike the case where the diameter of the separation roller is reduced in the conventional apparatus. By arranging the separation belt so that there is no
It is possible to suppress the occurrence of non-feeding of the paper due to the leading edge of the paper contacting the separation roller at an angle close to a right angle.

According to the first aspect of the invention, the leading edge of the sheet is brought into contact with the flat portion of the surface of the separation belt.
Since the contact angle between the leading edge of the paper and the separation belt is controlled within a narrow range, even if the lower paper that has been superposed and fed first, the lower paper is sent backwards to ensure that the upper paper Can be preferentially supplied on the paper feeding path. As described above, according to the first aspect of the invention, it is possible to obtain the same effect as the diameter of the separation roller in the conventional apparatus is reduced without causing side effects, and the radius of curvature of the separation belt. By effectively using most of them, it becomes possible to greatly improve the paper separation function.

(2) Invention of Claim 2 In the invention of Claim 2, the predetermined inequality tan θ <1 / μ is established so that the paper does not buckle when it comes into contact with the separation belt. Therefore, it is possible to provide a sheet separating / feeding device capable of stably continuing an accurate sheet feeding operation.

(3) Invention of Claim 3 In the sheet separating and feeding apparatus of the present invention, the feed roller has a structure which also serves as a pickup roller which is a sheet feeding means (sheet feeding means) in the conventional apparatus. Since it is unnecessary, the structure is simplified and a low-cost feeding device can be provided.

(4) Invention of Claim 4 In the present invention, since both ends in the width direction of the feed roller and the separation belt are rounded with a radius of 0.2 mm or more, the paper separation / paper separation caused by abrasion accompanying the feeding operation is performed. It is possible to provide a sheet separating / feeding device that can suppress changes in the feeding performance, have little change in function over time, and have stable performance.

(5) The invention of claim 5 According to the present invention, even when the separation belt is made of a thin material, a radius of 0.2 mm or more is provided at both ends in the width direction of the separation belt as in the invention of claim 4. The same effect as when the roundness is provided is obtained.

(6) Invention of Claim 6 According to the present invention, it is possible to provide a sheet separating / feeding device having further excellent sheet separating performance.

(7) Invention of Claim 7 In the sheet separating and feeding apparatus of the present invention, the edge of the sheet is prevented from coming into contact with a member such as a sheet guide member by adjusting the distance between the feed rollers. Therefore, the reliability of the paper feeding operation is enhanced.

(8) The invention according to claim 8 In the sheet separating / feeding device of the present invention, the operating energy is unnecessary, and the separating member which provides the same effect as the separating belt is provided, so that it can be provided at a low cost and Operation at low cost becomes possible.

(9) Invention of claim 9 In addition to the effect of the invention of claim 8, the same effect as the effect of the invention of claim 2 can be obtained.

(10) Invention of Claim 10 According to the present invention, it is possible to provide a sheet separating / feeding device having further excellent sheet separating performance.

(11) Invention of claim 11 In the present invention, since the sheet separating / feeding device according to any one of claims 1-10 is provided, a high-performance image forming excellent in the sheet separating / feeding function is formed. A device can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sheet separating / feeding device (sheet separating device) according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a nip portion forming the sheet separating / feeding device of FIG. 1 as viewed from a sheet feeding side.

3 is a structural explanatory view of the sheet separating / feeding device of FIG. 1, and is an explanatory view showing a connected state of a drive device attached to a side plate and a gear.

FIG. 4 is an explanatory diagram showing a basic configuration of a sheet separating / feeding device according to a second embodiment of the present invention.

FIG. 5 is a front view of a feed roller that constitutes a sheet separating / feeding device according to a third embodiment of the invention.

FIG. 6 is a front view showing a structure in the vicinity of a separation belt when a thin belt is used as a material for the separation belt.

FIG. 7 is a front view showing an arrangement procedure of feed rollers constituting a sheet separating / feeding device according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a basic configuration of a sheet separating / feeding device according to a fifth embodiment of the present invention.

FIG. 9 is a configuration explanatory diagram of an image forming apparatus including the sheet separating / feeding device of the present invention.

FIG. 10 is a cross-sectional view showing a conventional example of a sheet separating / feeding device.

11 is a graph showing a paper feed separation performance test result of the paper separation feeding apparatus of FIG.

[Explanation of symbols]

1 paper tray 3 feed rollers 7 Feed axis 9 side plate 10 side plate 11 Cylindrical member 20 drive gear 21 Relay shaft 25 Drive means 26 Feed Gear 27 Reverse gear 34 Support plate 41 Bottom plate 50 springs 81 Reverse axis 82 Cylindrical member 82a step 83 Support shaft 84 separation belt 84a separating member D, d Distance between feed rollers L overlap amount P paper

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H072 BA03 BA20 CA01 JA02 JA03                       JC08                 3F343 FA02 FB02 FC01 FC23 GA01                       GB01 GC01 GD01 HD16 JA16                       JD10 JD37 JD39 KB05

Claims (11)

[Claims] 1. A plurality of feed rollers arranged on a common feed rotation shaft, and an endless separation belt arranged on the downstream side of the common feed rotation shaft so as to freely circulate. The uppermost sheet is sent out from the multiple sheets stacked in the sheet container by the rotation of the feed roller, and the sheet is fed onto the sheet feeding path while making contact with the sheet nip transport section consisting of the feed roller and the separation belt. In the paper separating and feeding device configured to do, each feed roller and each separation belt are arranged alternately in the axial direction of the common feed rotation axis of the feed roller,
In addition, the feed roller and the separation belt partially overlap each other, and the separation belt is a belt that travels so as to exert a frictional force on the paper to return it to the paper container side. At least one of the pair of rotary shafts around which the belt is stretched is the reverse rotary shaft, and the diameter of the rotary shaft closer to the sheet sandwiching and conveying unit is the diameter of the feed roller. The diameter is 1/4 or less of the diameter, the friction coefficient between the paper and the separation belt is lower than the friction coefficient between the paper and the feed roller, and the leading edge of the paper sent from the feed roller is stretched flat in the separation belt. A sheet separating / feeding device, wherein a positional relationship of the separating belt with respect to the feed roller is set so as to abut the portion. 2. The following relationship is established between the angle θ formed by the separation belt and the lower surface of the leading edge of the paper sent by the rotation of the feed roller, and the friction coefficient μ between the paper and the separation belt. The sheet separating / feeding device according to claim 1. ## EQU1 ## tan θ <1 / μ (1) 3. The paper container is a paper tray for stacking paper on a vertically movable bottom plate, and the bottom plate is urged by a urging mechanism to a force in an upward direction toward the feed roller, and the paper tray is urged. The positional relationship of the feed roller with respect to the paper tray is set so that the vicinity of the leading end of the uppermost sheet of the plurality of sheets stacked inside can contact the feed roller with a predetermined pressure contact force. The sheet separating / feeding device according to claim 1 or 2. 4. The sheet separating / feeding device according to claim 1, wherein the widthwise ends of the feed roller and the widthwise ends of the separation belt are rounded with a radius of 0.2 mm or more. . 5. A radius of 0.
A cylindrical member having a roundness of 2 mm or more, having a diameter larger than that of the reverse rotation shaft, and inheriting the separation belt, and having an end radius of 0.2 mm or more of the cylindrical member. 2. The sheet separating / feeding device described in 2. 6. When the friction coefficient between the paper and the separation belt is μ, the friction coefficient between the paper and the cylindrical member is μB, and the friction coefficient between the paper and the feed roller is μF, μF> μB ≧ μ The sheet separating / feeding device according to claim 5. 7. The distance between the plurality of feed rollers arranged on the feed rotation shaft is such that the distance between the feed roller positioned at the end of the feed rotation shaft in the axial direction and the feed roller inside the feed roller is different from that of the other feed rollers. The sheet separating / feeding apparatus according to claim 1, wherein the sheet separating / feeding apparatus is larger than a space between the sheets. 8. A paper feed container provided with a plurality of feed rollers arranged on a common feed rotation shaft and a plurality of separation members fixedly arranged on a common fixed shaft on the downstream side of the feed rollers. A sheet separation method in which the uppermost sheet is sent out from a plurality of sheets by the rotation of a feed roller, and the sheets are fed onto the sheet feeding path while being in contact with the sheet holding / conveying unit composed of the feed roller and the separating member. In the feeding device, each feed roller and each separation member are arranged alternately in the axial direction of the common feed rotation axis of the feed roller, and the feed roller and the separation member partially overlap each other. The separation member has a flat inclined surface, and the coefficient of friction between the sheet and the separation member is lower than the coefficient of friction between the sheet and the feed roller. The positional relationship of the separating member with respect to these feed rollers is set so that the leading end of the separated sheet contacts the inclined surface of the separating member. When the sheet contacts the inclined surface, the inclined surface contacts the sheet. Is arranged so as to exert a force in a direction to return the sheet to the sheet container side. 9. The following relationship is established between the angle θ formed by the lower surface of the leading edge of the sheet sent from the feed roller and the inclined surface of the separating member, and the friction coefficient μa between the sheet and the inclined surface. The sheet separating / feeding device according to claim 8. ## EQU2 ## tan θ <1 / μa (2) 10. The friction coefficient between the paper and the feed roller is μ
10. The sheet separating / feeding apparatus according to claim 8 or 9, wherein F, where μF> μD ≧ μC, where F is the friction coefficient of the inclined surface and μD is the friction coefficient of the overlapping portion. 11. An image forming apparatus comprising the sheet separating / feeding device according to claim 1. Description: