JP3844042B2 - Sheet feeding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet supply apparatus that supplies and feeds stacked sheets one by one, and more particularly, to a sheet supply apparatus of a type in which sheets are conveyed by a feeding roll and a separation roll.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a sheet feeding apparatus used in an image forming apparatus such as a printer or an electrophotographic copying machine, a feeding roll that is rotationally driven in a sheet conveying direction and a torque that is opposite to the sheet conveying direction are applied. And a separating roll that is disposed in pressure contact with the feeding roll.
[0003]
In such a sheet supply apparatus, the separation roll is driven and rotated in the same direction as the supply roll (sheet conveyance direction) under the condition where the sheet is not sent out and the condition where only one sheet is sent out. It has become. This is set so that the frictional force between the feeding roll and the separation roll and the frictional force between the feeding roll and the separation roll through one sheet are larger than the limit torque of the torque limiter provided on the separation roll. Is due to
[0004]
On the other hand, under the condition where two sheets are sent out, the separation roll rotates or stops in the direction opposite to the feeding roll (the direction opposite to the sheet conveying direction). This is because the separation roll is not affected by the frictional force of the feeding roll, but is only affected by the small frictional force between the two fed sheets, and this small frictional force is less than the limit torque of the torque limiter. This is because the value is also set to be smaller. As a result, the excessively fed sheet (the sheet that contacts the separation roll) is pushed back or stopped, and only one sheet is supplied.
[0005]
Thus, in the sheet supply apparatus described above, it is necessary to use a material having a high coefficient of friction on the surfaces of the feeding roll and the separation roll from the viewpoint of reliably feeding the sheets one by one. For example, rubber materials such as ethylene propylene diene rubber (EPDM) and chloroprene rubber (CR) have been used.
[0006]
Recently, silicone rubber has attracted attention as a surface material for these feed rolls and separation rolls.
Silicone rubber, for example, has a property that the coefficient of friction is not easily lowered even when silicone oil used in a fixing device adheres (see Japanese Patent Laid-Open No. 63-17743), and a coating layer for increasing gloss on a paper is provided. It is an excellent material having the property (Japanese Patent Application No. 11-162808) that the friction coefficient is hardly lowered even when the coated paper is passed.
[0007]
[Problems to be solved by the invention]
However, silicone rubber has lower abrasion resistance than the above-mentioned EPDM, and there is a technical problem that if silicone rubber is used as a surface material for a feed roll or separation roll, the life of both rolls will be shortened. It was.
In particular, the separation roll in which the rotational resistance due to the torque limiter exists has a larger amount of wear than the feeding roll, so that the service life is significantly reduced.
[0008]
Therefore, in order to improve the wear resistance, it is conceivable to form a hard silicone rubber layer on the surfaces of the feed roll and the separation roll, but this time, paper dust tends to adhere to the surfaces of both rolls. As a result, there was a technical problem in that the friction coefficient between the two rolls was significantly reduced by the adhering paper dust, and double feed and misfeed were induced.
[0009]
As a means for solving such a technical problem, for example, a technique has been proposed in which a cleaning roll is disposed in pressure contact with a separation roll, and the friction coefficient of the separation roll is maintained by cleaning the surface of the separation roll. However, not only the cost increases, but also the cleaning roll is pressed against the separation roll in addition to the feeding roll, so that the braking force acting on the separation roll changes. There was a technical problem that it was impossible to obtain stable paper feeding performance.
In addition, the silicone rubber layer of the separation roll is more easily worn, and the life is shortened.
[0010]
The present invention has been made in order to solve the above technical problem, and provides a sheet supply apparatus that can obtain a stable supply performance over a long period of time with a simple configuration.
[0011]
[Means for Solving the Problems]
That is, as shown in FIG. 1, the present invention includes a feeding roll 1 that is rotationally driven in the sheet conveying direction, and a brake torque that is disposed in pressure contact with the feeding roll 1 and that is in a direction opposite to the sheet conveying direction. And a separation roll 2 to which the sheets S stacked on the sheet stacking means 3 are fed one by one and supplied to the surfaces of the feeding roll 1 and the separation roll 2 respectively. Elasticity with a coefficient of friction of 0.5 or more measured after slipping a coated paper having a length of 2.97 m at an ambient temperature of 10 ° C., a humidity of 15%, a pressing force of 1.96 N, and a drawing speed of 100 mm / s. Layers 1b and 2b are provided, and the hardness of the feed roll 1 is lower than the hardness of the separation roll 2.
This captures the feed roll 1 and the separation roll 2 from the viewpoint of material properties.
[0012]
In such technical means, the feeding roll 1 is applied with a brake torque in the direction opposite to the sheet conveying direction.
Here, when only one sheet S is sandwiched between the feeding roll 1 and the separation roll 2, the brake torque applied to the separation roll 2 is separated in the sheet conveyance direction via the sheet S. 2 is rotated, and when a plurality of sheets S are sandwiched between the feeding roll 1 and the separating roll 2, the sheet S that contacts the separating roll 2 is stopped or the sheet conveying direction is set. In order to convey in the reverse direction, the separation roll is set to a size that can be stopped or rotated in the reverse direction.
[0013]
Moreover, as a preferable aspect of the supply roll 1 and the separation roll 2, the rubber surfaces 1a and 2a are respectively provided on the surfaces of the supply roll 1 and the separation roll 2 and the hardness of the separation roll 2 is determined. In addition, a material having a low hardness can be used.
As a more preferred embodiment, the surfaces of the feed roll 1 and the separation roll 2 are respectively provided with silicone rubber layers 1a and 2a having a silica content of 20 parts by weight or less, and the hardness of the separation roll 2 In addition, a material having a low hardness can be used.
[0014]
In such an embodiment, the elastic layers 1b and 2b of the feed roll 1 and the separation roll 2 are formed by pressing the elastic layers 1b and 2b in a state where the pressing force is 1.96 N in an environment where the ambient temperature is 10 ° C. and the humidity is 15%. After restraining, the coated paper is sandwiched, and the coated paper corresponding to 2.97 m (10 sheets in the longitudinal direction of JIS A4 size) is slipped at a drawing speed of 100 mm / s, and then the friction coefficient is measured and this friction coefficient is 0. Any material may be used as long as the material is 5 or more.
Here, the elastic layers 1b and 2b are not limited to the above-described silicone rubber or rubber-based material, and may be made of, for example, a soft synthetic resin.
[0015]
Further, in the above-described aspect , the method for conveying the sheets S stacked on the sheet stacking means 3 to the pressure contact portion between the feeding roll 1 and the separation roll 2 may be appropriately selected from various methods. Is a pull-in roll 4 that pulls in and takes out the sheet S in contact with the uppermost sheet S among the sheets S stacked on the sheet stacking means 3.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows Embodiment 1 of an image forming apparatus incorporating a sheet feeding apparatus to which the present invention is applied . The first embodiment is a reference form showing the basic configuration of the image forming apparatus according to the second embodiment.
In FIG. 1, an image forming apparatus 21 according to the present embodiment is connected to an external device 25 such as an image reading apparatus (IIT) 23 for reading a document image and a personal computer (PC) via a communication line 27. A portion 29 is provided. Further, an image recording control unit 33 that controls the image writing device 31 based on image information from the receiving unit 29, an image carrier 35 on which an electrostatic latent image is written by the image writing device 31, and this A charger 37 that is arranged along the circumferential direction of the image carrier 35 and charges the image carrier 35, and a developing device 39 that develops toner on the charged image carrier 35 with toner are provided. The toner image on the image carrier 35 is transferred to the sheet as a sheet conveyed by the roller 43. Further, a fixing device 45 for fixing the image transferred to the paper, a discharge roller 47 for discharging the fixed paper, a discharge tray 49 for stacking the paper discharged by the discharge roller 47, and the image carrier 35 And a cleaner 41 that collects excess toner that is not used for transfer.
[0017]
Further, the image forming apparatus 21 is provided with a plurality (four in the present embodiment) of paper supply trays 59 for storing paper according to size or paper feeding direction, and these paper supply trays. 59 is configured such that a bottom plate (not shown) provided therein moves up and down by driving a motor (not shown). Above this paper supply tray 59, a paper supply device 60 as a sheet supply device is provided. The paper supply device 60 is in contact with the upper surface of the paper raised by the bottom plate and separates and conveys the paper. Then, the sheet is conveyed to an image forming unit made up of an image carrier 35 and the like. Each paper supply tray 59 is provided with an air blowing device 71 that blows air against the side surface of the paper.
[0018]
FIG. 3 is a perspective view showing the paper supply device 60. The paper supply device 60 frictionally contacts the upper surface of the stacked paper P and draws out the paper P in order, and pulls out the paper P drawn out from the pull-in roll 61 and conveys the paper P toward the downstream portion. A sheet feeding roll (feed roll) 62 as a feeding roll to be fed, and a separation roll (retard roll) 63 for separating the sheets P one by one while being pressed by the sheet feeding roll 62 are provided.
[0019]
The paper feed roll 62 is driven by receiving power from a feed motor (not shown) via a drive gear (not shown) and a feed clutch. On the other hand, the drawing roll 61 is configured to rotate via the arm 81 with the feed shaft 62 a of the sheet feeding roll 62 as a rotation center, and rotates in conjunction with the driving of the sheet feeding roll 62 by the gears 82. Further, the pull-in roll 61 falls on the upper surface of the paper P via the link 84 by the operation of a solenoid 83 that operates in response to a drive signal from a control unit (not shown), and is driven to rotate with a predetermined pressing force. By doing so, it is possible to feed out the paper P. Further, the movement of the arm 81 is detected by the photo sensor 85, and when the upper surface height of the paper P becomes low due to the transport of a predetermined number of papers P, the bottom plate in the paper supply tray 59 rises. The height of the paper P is configured to fall within a certain range.
[0020]
The separation roll 63 is brought into contact with the paper feed roll 62 with a weak pressure by a spring 89 via a support 88 having a pivot 87 as a rotation center. Further, the separation roll 63 is connected to the first gear 91 and the fixed second gear 92 via the torque limiter 90. Here, when the separation roll 63 rotates with the paper feed roll 62, the slip torque of the torque limiter 90 is transmitted to the first gear 91 via the retard shaft 63a, and the first gear 91 tends to rotate clockwise. However, since the second gear 92 is fixed, the first gear 91 operates to ride on the second gear 92, and as a result, the retard pressure, which is the pressure on the paper feed roll 62, is increased. Yes.
[0021]
In the present embodiment, as shown in FIG. 4, the paper feed roll 62 has a silicone rubber layer 62b of H _S 25 (value based on the old JISA, hereinafter simply referred to as JISA) on the outer peripheral surface of the feed shaft 62a. It is formed in a cylindrical shape.
On the other hand, the separation roll 63 is formed by forming an H _S 44 (JISA) silicone rubber layer 63b having a higher hardness than the silicone rubber layer 62b in a cylindrical shape on the outer peripheral surface of the retard shaft 63a.
Therefore, due to the above-described hardness relationship, the separation roll 63 bites into the paper feed roll 62 at the press contact portion N between the paper feed roll 62 and the separation roll 63.
[0022]
Next, the paper supply process according to the present embodiment will be described based on the schematic diagram shown in FIG.
When the paper supply is started, as shown in FIG. 5A, the paper feed roll 62 is driven and rotated, and accordingly, the drawing roll 61 is also driven and rotated. Then, the uppermost sheet P1 in contact with the drawing roll 61 is pulled out and conveyed toward the sheet feeding roll 62 side.
At this time, the separation roll 63 is in direct contact with the paper feed roll 62 and rotates following the rotation of the paper feed roll 62 by the frictional force acting between the paper feed roll 62 and the separation roll 63.
[0023]
Here, as shown in FIG. 5B, when only one sheet P 1 is taken out by the drawing roll 61, the sheet P 1 is carried into the pressure contact portion between the sheet feeding roll 62 and the separation roll 63. .
At this time, the separation roll 63 comes into contact with the paper feed roll 62 via the paper P1, and rotates following the rotation of the paper feed roll 62 by the frictional force acting between them. As a result, the paper P1 is conveyed.
[0024]
On the other hand, as shown in FIG. 5C, when the two sheets P1 and P2 are taken out by the drawing roll 61, these sheets P1 and P2 are carried into the pressure contact portion between the sheet feeding roll 62 and the separation roll 63. Is done.
At this time, the separation roll 63 comes into contact with the paper feed roll 62 via the two sheets P1, P2, but since the frictional force acting between these two sheets P1, P2 is small, the torque limiter 90 The reverse rotation torque of the sheet feed roller 62 does not follow the rotation of the sheet feed roll 62 but rotates in the opposite direction to the sheet feed roll 62 at the press contact portion. As a result, the paper P1 in contact with the paper feed roll 62 is conveyed, while the paper P2 in contact with the separation roll 63 is pushed back toward the paper supply tray 59 (not shown).
[0025]
Then , as shown in FIG. 5D, when the conveyance of the sheet P1 is completed, the drawing roll 61 is moved to a position separated from the next sheet P2 by the operation of the solenoid 83.
At this time, the paper feed roll 62 is driven and continues to rotate, and the pull-in roll 61 is also driven and rotated accordingly.
At this time, the separation roll 63 comes into direct contact with the paper feed roll 62 again, and rotates following the rotation of the paper feed roll 62 by the frictional force acting between the paper feed roll 62 and the separation roll 63.
[0026]
In this series of processes, when the paper feed roll 62 and the separation roll 63 are in direct contact with each other, the separation roll 63 is fed at the pressure contact portion between the paper feed roll 62 and the separation roll 63 as shown in FIG. The paper roll 62 is bitten.
In the pressure contact portion N of the paper feed roll 62 and the separation roll 63, the pressure contact portion inlet speed V1 and the pressure contact portion central speed V2 on the surface of the paper feed roll 62 are different (V1 ≠ V2), and the pressure contact portion central speed V2 and pressure contact are different. The part exit speed V3 is different (V2 ≠ V3).
[0027]
Then, a minute slip occurs partially between the paper feed roll 62 and the separation roll 63 in the press contact portion N, and foreign matters such as paper dust attached to the surface of the separation roll 63 due to this slip are removed from the paper feed roll. Therefore, the situation in which the friction coefficient of the separation roll 63 decreases is effectively avoided.
[0028]
Further, the foreign matter removed from the separation roll 63 is transferred to the paper feed roll 62 side, but it has been confirmed that this does not cause a situation in which the friction coefficient of the paper feed roll 62 decreases. Details of this will be described later.
[0029]
In the present embodiment, the separation roll 63 is reversely rotated when the paper P is double-fed and pushed back toward the paper supply tray 59. However, the present invention is not limited to this. Of course, the roll 63 may be stopped and held at the press contact portion N.
[0030]
Embodiment 2
The present embodiment is almost the same as the first embodiment, but paying attention to the characteristics of the elastic layers provided on the surfaces of the paper feed roll 62 and the separation roll 63, a material that can suppress the decrease in the friction coefficient is selected. It is a thing.
Of the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are given here. Description is omitted.
[0031]
The present inventors supply coated paper as paper P using a paper feed roll 62 or a separation roll 63 having a synthetic rubber such as ethylene propylene diene rubber (EPDM) or chloroprene rubber (CR) or a rubber foam on the surface. When paper was used, the friction coefficient of the roll surface suddenly decreased, and it was found that paper feeding defects and double feeding frequently occur.
Therefore, as a result of intensive investigations to solve such problems, the present inventors have found that the friction coefficient is drastically reduced by adhering the specific components of the coated paper to these synthetic rubbers. . Specifically, kaolin (kaolin: Al ₂ Si ₂ O ₅ (OH) ₄ silicate aluminum compound), which is a natural mineral pigment, among the white pigments that are the main component of the coating color in coated paper Has been found to have adhered to the surface of these synthetic rubbers and became the main cause of drastic reduction in the coefficient of friction.
[0032]
Furthermore, in response to this discovery, the present inventors have found a method for measuring the coefficient of friction after rubbing the coated paper, and measuring with various roll materials, and the coated paper affected by the coefficient of friction after rubbing the coated paper The transport performance of P was examined. FIG. 6 is a schematic configuration diagram of a coated paper rubbing device, FIG. 7A is a schematic configuration diagram of a friction coefficient measuring device, and FIG. 7B is a method for reading a friction force from a measurement value by the friction coefficient measuring device. FIG. 8 shows the relationship between various roll materials and the coefficient of friction after rubbing (slip) the coated paper.
[0033]
In FIG. 6, reference numeral 101 denotes a measurement roll, and the roll has an outer diameter of 15 mm, a width of 17 mm, and a wall thickness of 3.5 mm, and is in a state where rotation is constrained. Reference numeral 102 denotes a plate, which is sandwiched between the coated paper P and the measurement roll 101 and pressed with a pressing force Q of 1.96 N ± 10%. As other conditions at the time of slip, in this embodiment, the atmospheric temperature is 10 ± 1 (° C.), the atmospheric relative humidity is 15 ± 2 (%), and the coated paper P is 209 gsm of Super Art Kanto manufactured by Oji Paper Co., Ltd. The equivalent art paper was used, and the coated paper P and roll were used after being stored in the above atmosphere for 24 hours. The coated paper P is rubbed at a drawing speed of 100 ± 10 (mm / s), and the length of the coated paper P to be slipped is 0.297 m × 10 sheets = 2.97 m, and is drawn in the T direction in the figure. Was carried out.
[0034]
With respect to the measuring roll 101 on which the coated paper P was rubbed under the above conditions, the friction coefficient was measured with the friction coefficient measuring device shown in FIG. As a friction coefficient measuring device, a friction coefficient measuring device 104 includes a seesaw 106 disposed on a seesaw holding base 105 via a fulcrum 107, and a measuring roll 101 in a state where a coated paper P is disposed at one end of the seesaw 106. A weight 108 to be pressed and a load cell 109 for detecting the force (frictional force) of the seesaw 106 generated by rotating the measurement roll 101 are provided. Further, the detection content of the load cell 109 is output to the amplifier 110 and the voltage measuring device 111. In this embodiment, the ambient temperature is 10 ± 1 (° C.) and the ambient relative humidity is 15 ± 2 (%), which is the same environment as when the coated paper is rubbed, and the coated paper P is super art manufactured by Oji Paper Co., Ltd. Using Kanto 209 gsm or equivalent art paper, the coated paper P and roll were measured after being stored in the above atmosphere for 24 hours. Further, the pressing force by the weight 108 was 1.96 N ± 10%, and the measuring roll 101 was rotated in the direction of the arrow at a peripheral speed of 100 ± 10 (mm / s).
[0035]
FIG. 7B is a diagram for explaining the concept of the reading value of the frictional force, and the frictional force changes with the rotation of the measuring roll 101 as shown in FIG. In this change, when the coated paper P shown in FIG. 6 is rubbed, the measurement roll 101 is fixed and rubbed, so that the point where the coated paper P is rubbed in the measurement roll 101 is compared with other points. The coefficient decreases. If this reduction point is extracted, this becomes the friction coefficient necessary for the measurement. That is, the frictional force F (N) shown in FIG. 7B is the friction coefficient after rubbing.
[0036]
FIG. 8 shows the measurement results of the coefficient of friction after rubbing the coated paper in various roll materials under the above conditions. As can be understood from FIG. 8, urethane rubber, chlorinated polyethylene, and EPDM often have a low coefficient of friction of about 0.2 after rubbing the coated paper, and even the best material, EPDM-8, has a coefficient of friction of about 0.2. It is understood that it is in a low state as 48. On the other hand, silicone rubber generally maintains a high coefficient of friction even after rubbing the coated paper. However, as shown in FIG. 8, not all silicone rubbers maintain a high coefficient of friction, and roll materials Q-01 and Q-02 have a considerably low coefficient of friction after rubbing the coated paper. Value.
[0037]
As a result of analysis by the inventors, it has been surprisingly found that the coefficient of friction after rubbing the coated paper varies depending on the content of silica contained in the silicone rubber. This contained silica is used in silicone rubber rolls as a reinforcing filler. If the reinforcing filler is less than 10 parts by weight, it does not contribute to the improvement of rubber strength, and if it is more than 100 parts by weight, the rubber elasticity is remarkably increased. It is known to be lost (Japanese Patent Laid-Open No. 4-298426). The roll materials composed of the above-mentioned silicone rubbers of Q-01 and Q-02 both have a silica content of about 25 parts by weight, and the roll materials of Q-1 to Q-11 all have a silica content. Is 20 parts by weight or less. For example, in the roll material of Q-9, 10 parts of fumed silica with respect to 100 parts of dimethylsiloxane / methylvinylsiloxane copolymer rubber, and when the silica content is low, the friction coefficient after rubbing the coated paper is maintained high. It can be understood that the silica content is preferably 20 parts by weight or less.
[0038]
In this manner, in the present embodiment, the surface elastic layers of the paper feed roll 62 and the separation roll 63 are appropriately selected from the roll materials Q-1 to Q-11 described above.
This prevents a decrease in the frictional resistance of the paper feed roll 62 and the separation roll 63 due to the passage of paper in the first place. Further, the separation roll 63 is cleaned by the paper feed roll 62, so that it is like coated paper. Even in the case of using paper P that easily generates extraneous foreign matter, it is possible to maintain a good friction coefficient over a long period of time.
[0039]
◎ Experimental example 1
In the paper supply device 60 shown in FIG. 3, H _S 34 (JISA) silicone rubber rolls are used as the paper feed roll 62 and the separation roll 63, and 15,000 sheets of paper P (JISA 4 size lateral feed, the same applies hereinafter) are passed through. The amount of wear of the paper feed roll 62 and the separation roll 63 was investigated.
The results are shown in FIG. According to this, when the same hardness of the sheet feeding roller 62 and separating roller 63, the wear amount of the separation roller 63 it is grasped large two times the amount of wear of the sheet feed roller 62.
[0040]
◎ Experimental example 2
In the paper supply device 60 shown in FIG. 3, three types of the same H _S (34, 40, 44 (JISA)) silicone rubber rolls are used as the paper feed roll 62 and the separation roll 63, and 15000 sheets of paper P are passed through. Thus, the amount of wear of the separation roll 63 and the friction coefficient of the separation roll 63 before and after the sheet passing were investigated.
The results are shown in FIG. According to this, it is understood that the higher the hardness is, the more the amount of wear of the separation roll 63 is reduced, while the friction coefficient after passing the paper is remarkably lowered.
[0041]
◎ Experimental example 3
In the paper supply apparatus 60 shown in FIG. 3, a silicone rubber roll of H _S 44 (JISA) is used as the separation roll 63, while two types of silicone rubber rolls of H _S 25 and 44 are used as the paper feed roll 62, and 5000 sheets The sheet P was passed through, and the amount of wear of the separating roll 63 and the friction coefficient of the separating roll 63 before and after the sheet passing were investigated.
The results are shown in FIG. According to this, it is understood that by making the paper feed roll 62 to have a lower hardness than the separation roll 63, it is possible to suppress a significant decrease in the friction coefficient after the separation roll 63 passes the paper. In addition, it is understood that the amount of wear of the separation roll 63 is substantially the same or slightly improved.
[0042]
Experimental example 4
In the sheet feeding apparatus 60 shown in FIG. 3, it was employed to that employed a silicone rubber roll (H _S both 34 (JISA)) as the paper roll 62 and the separating roller 63, EPDM rolls (H _S both 31 (JISA)) and Each of these was used to pass through 60000 sheets of paper P, and the amount of wear of the separation roll 63 and the coefficient of friction before and after the sheet passing were investigated.
The results are shown in FIG. According to this, when the paper feed roll 62 and the separation roll 63 have the same hardness, the wear amount of the separation roll 63 using silicone rubber is about three times larger than the wear amount of the separation roll 63 using EPDM. It is grasped that. In addition, it is understood that both of the friction coefficients after the separation roller 63 after passing the paper are significantly reduced.
[0043]
◎ Experimental example 5
In the paper supply device 60 shown in FIG. 3, a combination of an H _S 25 (JISA) silicone rubber roll as the paper feed roll 62 and an H _S 44 (JISA) silicone rubber roll as the separation roll 63, and the paper feed roll 62. In addition, the separation roll 63 that employs an EPDM roll of H _S 31 is used, and 100,000 sheets of paper P are passed through, and the wear amount of the separation roll 63 and the friction before and after the paper feed roll 62 and the separation roll are passed. The coefficient was investigated.
The results are shown in FIG. According to this, when silicone rubber is used, by making the paper feed roll 62 lower in hardness than the separation roll 63, it is possible to suppress a significant decrease in the coefficient of friction after the separation roll 63 passes, and when EPDM is used. It can be seen that a higher coefficient of friction can be maintained. In addition, it is understood that the amount of wear of the separation roll 63 can be improved as compared with the case of using EPDM. Furthermore, when silicone rubber is used, since the friction coefficient of the paper feed roll 62 hardly changes before and after the sheet passing, the foreign matter removed from the separation roll 63 by the paper feed roll 62 adversely affects the paper feed roll 62. It is also understood that it does not affect.
[0044]
【The invention's effect】
As described above, according to the present invention, the material characteristics of the feed roll and the separation roll are devised, and the surface of the separation roll is cleaned by the feed roll. Performance can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a sheet feeding apparatus according to the present invention.
FIG. 2 is an explanatory diagram showing an overview of Embodiment 1 of an image forming apparatus incorporating a sheet feeding device to which the present invention is applied;
FIG. 3 is a perspective view of a paper supply device.
FIG. 4 is an explanatory diagram illustrating a pressure contact portion between a paper feed roll and a separation roll.
FIGS. 5A to 5D are schematic views showing a paper supply process.
6 is a schematic configuration diagram of a coated paper rubbing apparatus in Embodiment 2. FIG.
7A and 7B are a schematic configuration diagram of a friction coefficient measurement device according to a second embodiment, and an explanatory diagram for explaining a friction coefficient measurement method from measured values.
FIG. 8 is a graph showing the relationship between various roll materials and the coefficient of friction after rubbing the coated paper.
9 is a chart showing the results of Experimental Example 1. FIG.
10 is a chart showing the results of Experimental Example 2. FIG.
11 is a chart showing the results of Experimental Example 3. FIG.
12 is a chart showing the results of Experimental Example 4. FIG.
13 is a chart showing the results of Experimental Example 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Feed roll, 1a ... Silicone rubber layer, 1b ... Elastic layer, 2 ... Separation roll, 2a ... Silicone rubber layer, 2b ... Elastic layer, 3 ... Sheet stacking means, 4 ... Pull-in roll, 21 ... Image forming apparatus, 60 ... paper supply device, 61 ... drawing roll, 62 ... feeding roll, 62b ... silicone rubber layer, 63 ... separation roll, 63b ... silicone rubber layer, 90 ... torque limiter, N ... pressure contact, P ... paper, S ... Sheet

Claims (1)

A sheet feeding roll that is rotationally driven in the sheet conveying direction; and a separation roll that is disposed in pressure contact with the feeding roll and that is applied with a brake torque in a direction opposite to the sheet conveying direction. In a sheet feeding device that feeds and feeds one sheet at a time,
A coated paper having a length of 2.97 m was slipped onto the surfaces of the feeding roll and the separating roll at an atmospheric temperature of 10 ° C., a humidity of 15%, a pressing force of 1.96 N, and a drawing speed of 100 mm / s, respectively. A sheet feeding apparatus comprising an elastic layer having a friction coefficient measured later of 0.5 or more, and a hardness of the feeding roll lower than that of the separation roll.

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