JPH1120966A - Paper sheet feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet feeding device capable of surely preventing overlapped feeding and unfeeding of paper sheets irrespective of the friction factors of the paper sheets. SOLUTION: A feed roller and a reverse-rotation roller 24 are contacted with each other, the reverse rotation roller 24 includes inside a torque limiter for applying torque of feeding and reverse feeding directions to the reverse rotation roller 24 and, when two or more paper sheets are gripped in a nip part, the reverse rotation roller 24 is reversibly rotated by the function of the torque limiter and overlapped feeding of scooped paper sheets is prevented. Two torque limiters 30 and 31 different in torque are provided in the reverse rotation roller 24, the torque limiters 30 and 31 are switched between a paper sheet having a large friction factor and a paper sheet having a small friction factor, and thus a proper feeding operation is always performed.

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 of an image forming apparatus, and more particularly, to a feed roller rotating in a sheet feeding direction and a feed roller disposed opposite to the feed roller with a sheet passage interposed therebetween. The present invention relates to a sheet feeding device having a reverse roller that is in pressure contact with the sheet and that has a torque applied in a direction opposite to the sheet feeding direction.

[0002]

2. Description of the Related Art A feed roller rotating in a paper feed direction;
2. Description of the Related Art A paper feeder having a reverse roller which is disposed opposite to the feed roller with a paper path interposed therebetween and is in pressure contact with the feed roller and has a torque applied in a direction opposite to the paper feed direction is widely used in an image forming apparatus. . In such a paper feeding device, when two or more sheets are held in the nip portion between the feed roller and the reverse roller, the reverse roller has a lower torque because the coefficient of friction between the sheets is smaller than the coefficient of friction between the sheet and the reverse roller. , So that the multi-fed paper is handled. As a result, the sheets are always sent out one by one toward the registration rollers. Japanese Patent Application Laid-Open No. 4-1892 discloses this type of sheet feeding device.
No. 33, a first connecting main body having a permanent magnet, and a second connecting main body located outside the first connecting main body,
There is disclosed a technique in which one of the first or second connecting bodies is connected to a reverse roller shaft, and the other connecting body is connected to a reverse roller to generate a constant torque when the two bodies are relatively rotated.

[0003]

In the above prior art, a torque limiter having a permanent magnet applies a constant torque to a reverse roller in a direction opposite to a sheet feeding direction to prevent double feeding of sheets. However, if the paper is fixed at a torque setting corresponding to the friction coefficient of the surface of the paper, paper feeding troubles such as non-feeding and double feeding may occur depending on the type and state of the paper. For example, in the two-sided copy mode, when a sheet is fed to transfer an image to the first side (front side), the coefficient of friction is high, but when a sheet is fed to transfer an image to the second side (back side). However, since the paper has once passed through the fixing device and the silicone oil has been applied to both sides, the coefficient of friction is low. If the same torque is applied uniformly to sheets having a difference in friction coefficient in this manner, the above-described paper feed trouble is likely to occur.

A first object of the present invention is to make it possible to switch a plurality of torque values of a torque limiter attached to a reverse roller so that the paper can be reliably adjusted in accordance with various paper friction conditions (difference in friction coefficient). An object of the present invention is to provide a sheet feeding device that can separate and prevent problems such as double feeding and non-feeding. A second object of the present invention is to switch between a plurality of torque limiters having different torque values attached to a reverse roller to reliably adjust the paper according to various paper friction conditions (difference in friction coefficient). An object of the present invention is to provide a sheet feeding device that can separate and prevent problems such as double feeding and non-feeding. A third object of the present invention is to discriminate plain paper in the initial state (the front side in the duplex mode) from paper once passed through the fixing unit (the back side in the duplex mode),
An object of the present invention is to provide a sheet feeding device capable of switching the value of a torque of a torque limiter based on a result thereof, separating sheets reliably, and preventing problems such as double feeding and non-feeding.

[0005]

A first object of the present invention is to provide a feed roller which rotates in a sheet feeding direction, and which is disposed opposite to the feed roller with a sheet path interposed therebetween and is pressed against the feed roller, and is opposed to the sheet feeding direction. In a paper feeder having a reverse roller to which a torque is applied in a direction, a torque limiter that applies a torque to the reverse roller is provided, and the torque value of the torque limiter is switchable. You. The second problem is that, in the paper feeding device of the first means, a plurality of torque limiters having different torque values are prepared, and by switching the torque limiters, the value of the torque applied to the reverse roller can be switched. It is solved by a certain second means. The third problem is solved by the paper feeding device of the first means, wherein the switching of the torque applied to the reverse roller is determined by the third means for discriminating between the front side and the back side of the sheet.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a copying machine to which the present invention is applied. Image reading device (scanner) 1
Includes an illumination lamp 2, a mirror group 3, a lens 4, a color sensor 5, and the like. The apparatus body 6 includes a polygon mirror 7, an f / θ lens, a reflection mirror 8, and the like as an optical writing device. Further thereunder, a photosensitive drum 9, a developing device 10, an intermediate transfer belt 11, a registration roller 12,
Paper transfer roller 13, paper transport unit 14, fixing device 15
It has. The scanner 1 is driven by a stepping motor (not shown), and outputs an image of a document to a color sensor 5 via an illumination lamp 2, a mirror group 3, and a lens 4.
To convert the image information of the original into an electrical signal. The image signal is converted into an optical signal, and based on the image signal intensity level, optical writing corresponding to the original image is performed by a laser through a polygon mirror 7, an f / θ lens, and a reflection mirror 8, and the photosensitive member An electrostatic latent image is formed on the drum 9. This latent image is developed in the developing device 10 and transferred to the intermediate transfer belt 11. This is transferred by the paper transfer roller 13 to the paper sent by the registration roller 12. The sheet is conveyed to the fixing device 15 by the sheet conveying unit 14 and the toner image is fused and fixed.

FIG. 2 is a configuration diagram of the fixing device. In the fixing device 15, the unfixed toner on the sheet is fused with the sheet by applying a fixed heat and pressure by the fixing roller 16 and the pressure roller 17. Further, in order to increase the releasability between the roller and the paper, an oil application felt 18 is in contact with the fixing roller 16, and silicone oil is applied to the surface of the fixing roller 16 from the felt 18. This silicone oil is also applied to the surface of the pressure roller 17 that is in contact with the fixing roller 16. When the paper enters here, silicone oil adheres to both sides of the paper, and the friction coefficient decreases.

FIG. 3 is a front view of a paper feeder using a manual feed table, FIG. 4 is a perspective view of the same, and FIG. The sheet is set against the rollers on the manual feed table 21. When the paper feed motor (not shown) rotates, the reverse rotation roller shaft 23 (FIG. 4) is driven in the direction of arrow A via the gear of the paper feed clutch 22 (FIG. 4). Since the drive transmission of the reverse rotation roller shaft 23 and the reverse rotation roller 24 is through a torque limiter, which will be described later, it is pressed against the paper feed roller 25 by a pressure spring (not shown), and is larger than the rotation transmission torque of the torque limiter. The reverse rotation roller 24 receiving the friction torque does not rotate, and only the reverse rotation roller shaft 23 rotates. When the paper feed clutch 22 is turned on, the paper feed roller 25 is driven. Further, the call roller 26 is also driven via the relay gear. In addition, the reverse rotation roller 24 in contact with the paper feed roller 25 moves with the paper feed roller 25 due to the frictional force with the paper feed roller 25 exceeding the torque of the built-in torque limiter. Next, at the paper feed timing, the pickup solenoid 27 (FIG. 5) is turned on, the calling roller 26 descends, and comes into contact with the paper to feed the paper. Then, the leading end of the fed paper strikes the registration roller 12, and the paper sags between the registration roller 12 and the paper feed roller 25. Note that the reverse rotation roller 24 is a reverse roller described in the claims, and
Indicates the feed roller 3.

FIG. 6 is an explanatory view showing a force relationship when one sheet is sandwiched between the nip portion between the reverse rotation roller and the paper feed roller. FIG. 7 is a diagram illustrating two sheets between the nip portion between the reverse rotation roller and the paper supply roller. FIG. 8 is an explanatory diagram showing a force relationship in the case where the power is applied. In FIG. 6, F1
Is a feeding force applied to the first sheet by the feeding roller 25, F2 is a frictional resistance between sheets, and F3 is a returning force of the torque limiter. In FIG. 7, F4 is the feeding force applied by the first sheet to the second sheet, and F5 and F6 are the return resistance force between the sheets. As shown in FIG. 6, the reverse rotation roller 24 and the sheet feeding roller 2
When one sheet of paper is fed to the nip portion of No. 5, the sheet is fed by the paper feed roller 25 more than the torque force of the torque limiter 28.
Since the feed force (frictional force) is large, the sheet is sent to the registration roller 12 by this feed force. Therefore, the reverse rotation roller 24 rotates together with the sheet due to frictional force. That is, F1> F2 + F3. Further, as shown in FIG. 7, when two or more sheets are fed to the nip portion between the reverse rotation roller 24 and the sheet feeding roller 25, the rotation of the sheet feeding roller 25 is changed to the uppermost sheet because the frictional force between the sheets is small. , But is hardly transmitted to the lower sheet. Therefore, the rotational force from the torque limiter 28 is transmitted to the reverse rotation roller 24,
A force acts in a direction to return the lower sheet to the manual feed table 21. That is, F3> F4 + F5 + F6. If the frictional force of the paper drops,
The relationship between F1, F2, and F3 may be such that F1 <F2 + F3. In particular, when F1 <F3, the sheet conveyed by the recall roller 26 is returned, and as a result, the sheet is not fed. As a countermeasure, the present invention employs a mechanism that can change the value of F3.

FIG. 8 is a configuration diagram showing a first embodiment of a plurality of torque limiters used for the reverse rotation roller of the paper feeding device of the present invention.
9 is a configuration diagram showing the second embodiment, FIG. 10 is an exploded perspective view of the same, and FIG. 11 is a configuration diagram showing a slide mechanism.
As shown in FIG. 8, in this embodiment, the reverse rotation roller 24 is provided with two torque limiters having different torque values, and the two torque limiters are switched as necessary. The idling torque set values of the torque limiter 30 and the torque limiter 31 are T and T ', respectively. The conveying force of the paper feed roller 25 when passing the plain paper is F1, and the back surface (that is, the paper once passing through the fixing device 15 and having a reduced friction coefficient due to the adhesion of the silicone oil) is passed. Assuming that the conveying force of the paper feed roller 25 in this case is F1 ', and the radius of the paper feed roller 25 is R, the relationship between F1, F1' and T, T 'is as follows: F1> RT = F3 F1'> Unless R.T '= F3', paper cannot be fed. When the idling torque of the torque limiter is fixed to a constant value T, F1 '<F3 is satisfied depending on the paper, and as described above, non-feeding occurs. Therefore, the idling torque is changed, and F3>F3'. Let T> T '.

As shown in FIGS. 8 to 10, the torque limiter 31 has a slip torque set between a first member 31a and a second member 31b, and a slit into which a pin 32a of a drive shaft 32 is inserted. 31c and a fitting protrusion 31d that can be coupled to the torque limiter 31 are formed. The torque limiter 30 has an idling torque set between the first member 30a and the second member 30b.
, A fitting protrusion 30d for coupling with the torque limiter 31, and a fitting recess 30e in which the fitting protrusion 31d of the torque limiter 31 is fitted. A recess is formed in the reversing roller 24, and the torque limiter 30 is inserted. A fitting recess 24a in which the fitting projection 30d is always fitted is formed on the bottom surface of the recess. 34 is a torque limiter 31
First spring, 3 disposed between the first spring and the torque limiter 30;
Reference numeral 5 denotes a second spring disposed between the torque limiter 30 and the reverse rotation roller 24.

Next, the operation of the embodiment will be described. When passing plain paper, as shown in FIG. 8, the first member 30a of the torque limiter 30 and the reversing roller 24 mesh with each other and rotate integrally. The second member 30b of the torque limiter 30 and the drive shaft 32 are connected by a pin 33 so as to rotate integrally. At this time, the torque limiter 31 is separated from the torque limiter 30 by the first spring 34 between the two torque limiters 30, 31, and the fitting concave portion 30e of the torque limiter 30 and the fitting projection 31d of the torque limiter 31 are disengaged. I have. Therefore, the entire torque limiter 31 rotates together with the drive shaft 32. In this way, idling starts with the set value of the torque limiter 30. Therefore, the idling torque is T. Here, the first spring 34
And the second spring 3 between the torque limiter 30 and the reversing roller 24
The strength of 5 is set so that the second spring 35 is stronger.
Otherwise, the first spring 34 causes the torque limiter 3
This is because 0 is depressed and disengages from the pin 33 to stop driving.

Next, when forming an image on the back side of the sheet at the time of double-sided copying, as shown in FIG. 9, when the torque limiter 31 is pushed into the reverse rotation roller 24 side, the torque limiter 30 is rotated by the reverse rotation roller 24. The slit 30c is disengaged from the pin 33 to stop driving. Further, the fitting concave portion 30e of the torque limiter 30 and the fitting projection 31d of the torque limiter 31 are fitted together to form a joint, that is, the first member 30a of the torque limiter 30 and the first member 30a of the torque limiter 31 Combined and rotate together. At this time, the second member 31b of the torque limiter 31 is rotated together with the drive shaft 32 by the pin 32a. Therefore, when the torque limiter 30 and the torque limiter 31 of the reversing roller 24 are coupled in this way, idling starts at the set value of the torque limiter 31. Accordingly, the idling torque is T ', and the backing paper having a lower friction coefficient than plain paper can be separated and conveyed. The sliding of the torque limiters 30 and 31 is performed by a solenoid 36 shown in FIG. An arm member 37 is attached to the solenoid 36. When the solenoid 36 rotates around the fulcrum and the solenoid 36 is operated, the torque limiter 31 is pushed in. When the torque limiter 30 is pushed leftward, the state shown in FIG. 9 is obtained. At this time, the shaft is rotated so that the joints engage. To return to the original state, when the solenoid 36 is turned off, the spring 38 attached to the arm member 37 is turned off.
Returns the arm member 37, and the torque limiters 30, 3
1 is returned to the state shown in FIGS. 8 and 11 by a first spring 34 and a second spring 35.

FIG. 12 is a diagram showing a first screen of the operation / display section, and FIG. 13 is a diagram showing a second screen of the same. First, when selecting manual paper feed from the manual feed table 21, the manual paper feed key 42 is pressed on the first screen (touch panel) shown in FIG. Then, the second screen of FIG. 13 appears. In the case of plain paper, the plain paper key 43 is pressed. In the case of the back side (paper on which an image has been formed on one side) in the double-side copy mode, the double-side back key 44 is pressed. As described above, the torque limiters 30 and 31 are switched.

In the above-described embodiment, the paper feed roller 25 rotating in the paper feed direction is opposed to the paper feed roller 25 with the paper path interposed therebetween and pressed against the paper feed roller 25, In a paper feeder having a reverse rotation roller 24 to which a torque is applied in a direction opposite to the paper feeding direction, a torque limiter that applies a torque to the reverse rotation roller 24 is provided, and the torque value of the torque limiter can be switched. By changing the torque value of the torque limiter attached to the reversing roller 24, a plurality of torque values can be switched, so that the paper can be reliably separated according to various paper friction conditions (difference in friction coefficient), and double feed and non-feed can be performed. Such a problem can be prevented.
Further, in the above-described embodiment, a plurality of torque limiters 30 and 31 having different torque values are prepared, and by switching these torque limiters 30 and 31, the reverse rotation roller 2 is provided.
4 can be switched, the plurality of torque limiters 30 and 31 attached to the reversing roller 24 and having different torque values are switched, so that various paper friction conditions (friction coefficients) can be changed. ), The paper can be reliably separated, and problems such as double feeding and non-feeding can be prevented. In the above-described embodiment, the switching of the torque applied to the reversing roller 24 is determined by the front side / back side of the sheet passing paper. The paper that has passed through the fixing unit (the back side in the duplex copying mode) is discriminated, and the torque value of the torque limiter is switched based on the result to reliably separate the paper and prevent problems such as double feeding and non-feeding. be able to.

[0016]

According to the first aspect of the present invention, a plurality of torque values of the torque limiter attached to the reverse roller can be switched, so that the frictional conditions (different coefficients of friction) of various papers can be adjusted. In addition, it is possible to reliably separate sheets and prevent problems such as double feeding and non-feeding.
According to the second aspect of the present invention, by switching the plurality of torque limiters attached to the reverse roller and having different torque values, it is possible to reliably adjust to various paper friction conditions (difference in friction coefficient). Separate paper, double feed,
Problems such as non-feeding can be prevented. According to the third aspect of the present invention, the plain paper in the initial state (the front side in the double-sided copy mode) and the paper once passed through the fixing unit (the back side in the double-sided copy mode) are determined, and the torque limiter is determined based on the result. By switching the torque value, the paper can be surely separated, and problems such as double feed and non-feed can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine to which the present invention is applied.

FIG. 2 is a configuration diagram of a fixing device.

FIG. 3 is a front view of a sheet feeding device using a manual feed table.

FIG. 4 is a perspective view of the same.

FIG. 5 is a perspective view showing a call roller up / down mechanism;

FIG. 6 is an explanatory diagram showing a force relationship when one sheet is sandwiched between a nip portion between a reverse rotation roller and a sheet feeding roller.

FIG. 7 is an explanatory diagram showing a force relationship when two sheets are sandwiched between the nip portion of the reverse rotation roller and the sheet supply roller.

FIG. 8 is a configuration diagram showing a first embodiment of a plurality of torque limiters used for a reverse rotation roller of the sheet feeding device of the present invention.

FIG. 9 is a configuration diagram illustrating a second embodiment of a plurality of torque limiters used for the reverse rotation rollers of the sheet feeding device of the present invention.

FIG. 10 is an exploded perspective view of a plurality of torque limiters used for a reverse rotation roller of the sheet feeding device of the present invention.

FIG. 11 is a configuration diagram showing a slide mechanism of a plurality of torque limiters used for a reverse rotation roller of the sheet feeding device of the present invention.

FIG. 12 is a diagram showing a first screen of an operation / display unit.

FIG. 13 is a diagram showing a second screen in the same manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 22 Paper feed clutch 23 Reverse rotation roller shaft 24 Reverse rotation roller (reverse roller) 25 Paper supply roller (feed roller) 26 Recall roller 27 Pickup solenoid 30, 31 Torque limiter 32 Drive shaft 33 Pin 34 First spring 35 Second spring

Claims (3)

[Claims] A feed roller that rotates in a paper feed direction;
A sheet feeding device having a reverse roller disposed opposite to the feed roller with the sheet path interposed therebetween and pressed against the feed roller to apply a torque in a direction opposite to the sheet feeding direction, wherein a torque is applied to the reverse roller; A sheet feeder provided with a torque limiter, wherein a torque value of the torque limiter is switchable. 2. The paper feeding device according to claim 1, wherein a plurality of torque limiters having different torque values are prepared, and by switching these torque limiters, the value of the torque applied to the reverse roller can be switched. A sheet feeding device characterized by the above-mentioned. 3. The sheet feeding device according to claim 1, wherein the switching of the torque applied to the reverse roller is determined based on the front side / back side of the sheet.