JPH07137872A - Paper feeder - Google Patents

Abstract

PURPOSE:To prevent a drive load from increasing and a torque limiter from deteriorating by surely performing release of pressure contact of a separate roller from a feed roller. CONSTITUTION:A forced release part 4d is provided in a pressure lever 4 for pressurizing a bearing 8 of a separate roller 9. When a solenoid 1 is turned off, a release lever 2 is turned by action of a spring 13, to press a protruded part 4c of the pressure lever 4 by a point end of this lever 2. Then in the pressure lever 4, its upper side part 4a is turned in a lowering down direction, to press down the bearing 8 by the forced release part 4d. Thus by adding press down force by the forced release part 4d to the own weight of the separate roller 9, biting force with a feed roller 10 is overcome to surely release pressure contact with the feed roller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for separating and feeding sheets into one sheet, and more particularly to a friction separating roller type sheet feeding device.

[0002]

2. Description of the Related Art As a sheet feeding device for feeding sheets one by one from a sheet cassette or a sheet tray of an image forming apparatus such as a copying machine, a facsimile, a printer, etc., a feed roller rotating in a sheet feeding direction and this feed A friction separating roller (FRP) type sheet feeding device having a pair of rollers which are pressed against the rollers to be paired with each other and to which a driving force is applied in a direction opposite to the feeding direction via a torque limiter is well known. In this type of paper feeding device, when the sheets stacked and stored in the cassette or the tray are sequentially sent from the top to the nip between the feed roller and the separate roller by the calling roller, when the sheets are double-fed here. Is configured to separate sheets and feed the sheets one by one. The separate roller is constantly in pressure contact with the feed roller, and the driving force is always applied in the direction opposite to the feeding direction via the torque limiter. Therefore, there is a problem that the load on the drive system is large and the torque limiter deteriorates rapidly with time. Further, in recent years, the number of front-loading type image forming apparatuses has increased, but in the case of this type of image forming apparatus, the sheet feeding direction and the drawing direction of a cassette or tray are often different. Therefore, in this type of image forming apparatus, when the paper feeding device is stopped while the paper is caught in the nip of the separation feeding unit of the paper feeding device due to occurrence of paper jam during the paper feeding operation,
Pulling out the cassette or the tray from the image forming apparatus may not only damage the paper but also damage the components in the cassette or the tray. In order to deal with such a problem, there has been proposed a paper feeding device of a type in which a separate roller is provided so as to be able to come into contact with and separate from a feed roller, and when the image forming operation is completed, the pressure contact of the separate roller with the feed roller is released. ing. Here, an example of the sheet feeding device of that system will be described with reference to the drawings.

In the separating and feeding section of the sheet feeding device of the copying machine shown in FIG. 3, the feed roller 10 is attached to the feed roller shaft 12.
Is installed. Further, a separate roller 9 is mounted via a torque limiter 11 on the separate roller shaft 7 rotated in the direction of arrow A by a drive source (not shown). The bearing 8 of the separate roller shaft 7 is mounted on the upper side portion 14 a of the pressure lever 14. Pressure lever 14 is L
It has a V-shape and is rotatably supported by shafts 6 provided at the corners of the L-shape. A protruding portion 14c is provided at the tip of one side 14b extending below the pressure lever 14. Further, one end of the spring 5 is locked to the tip of the one side 14b. The other end of the spring 5 is locked to a machine frame (not shown). A release lever 2 is rotatably supported by a shaft 3 in the vicinity of the protruding portion 14c of the pressure lever 14. The other end of the spring 13, one end of which is locked to a machine frame (not shown), is locked near the tip of the release lever 2. The opposite end of the release lever 2 is connected to the tip of the arm 1a of the pressure release solenoid 1.

When the copying operation of the copying machine is started, the pressure release solenoid 1 is turned on. Then, the arm 1a is pulled into the solenoid, and the release lever 2 rotates about the shaft 3 in the direction toward the solenoid 1. Then,
The tip of the release lever 2 is the protruding portion 14c of the pressure lever.
The pressure lever 2 is pulled by the spring 5 to press the bearing 8 of the separate roller shaft 7 upward.
As a result, the bearing 8 slides upward in a separate roller movement guide (not shown), and the separate roller 9 is brought into pressure contact with the feed roller 10.

Feed roller 10 of separate roller 9
After completion of the press contact with, the clutch (not shown) is engaged at a predetermined timing, and the feed roller shaft 12 is driven in the direction of arrow A by a drive source (not shown). Then, the separate roller 9 is rotated along with the feed roller 10, and the sheet called between the rollers is fed. At this time, a driving force is applied to the separate roller 9 in the direction of arrow A via the torque limiter 11, and a constant torque is applied in the direction opposite to the paper feeding direction (direction of arrow S). As a result, when the called sheets are double-fed, they are separated and fed into one sheet.

When the copying operation of the copying machine is completed, the solenoid 1 is turned off. Then, the retraction of the arm 1a is released, and the release lever 2 is operated by the spring 13 so that
It rotates about the shaft 3 as a fulcrum in a direction away from the solenoid 1. Then, the tip of the release lever 2 presses the protruding portion 14c of the pressure lever. The pressure lever 14 pushed by the projecting portion 14c rotates about the shaft 6 in the direction of extending the spring 5. Therefore, the separate roller shaft 7
The bearing 8 is released from the upward pressure. Usually, when the solenoid 1 is turned off, the upward pressure on the bearing 8 is released, and the separate roller 9 falls due to its own weight. The contracting force of the spring 13 is stronger than that of the spring 5. Therefore, when the solenoid 1 is turned off, the contracting force of the spring 13 overcomes the contracting force of the spring 5, and the release lever 2 moves to the pressure lever 1.
The upper side 14a of 4 is rotated downward.

In this way, when the copying operation of the copying machine equipped with the paper feeding device is completed, the pressure contact of the separate roller with the feed roller is released, and the separate roller is dropped by its own weight.

[0008]

[Problems to be Solved by the Invention] However, FRP
In the paper feeding device of the method, due to the biting force acting between the feed roller and the separate roller, which is unique to this method,
The separate roller may not drop due to its own weight.
In a normal FRP type sheet feeding device, since the driving force in the opposite direction to the sheet feeding direction is always applied to the separate roller shaft,
If the pressure contact between the separate roller and the feed roller is not released, the torque limiter will continue to operate, resulting in a large load on the drive system, and deterioration of the torque limiter is accelerated.

Further, even if the drive source is stopped, the aforementioned biting force is maintained for a while. Therefore, when the cassette or the tray is pulled out from the apparatus with the paper near the nip between the feed roller and the separate roller, there is a problem that the paper is unavoidably damaged.

Further, in the conventional image forming apparatus,
Since the pressure contact of the separate roller with the feed roller is released only when the image forming operation is not performed, after the separation and feeding of the sheet by the sheet feeding device is completed and the sheet is delivered to the conveying means in the subsequent stage, or Even during execution of the image forming operation by the image forming means of the forming apparatus, the separate roller is in pressure contact with the feed roller, and at this time, since the driving force in the direction opposite to the paper feeding direction is applied to the separate roller shaft, There has been a problem that separate measures against the increase in driving load and the deterioration of the torque limiter are necessary.

An object of the present invention is to solve the above-mentioned problems in the conventional sheet feeding device.

[0012]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned problem is solved by a feed roller which rotates in the sheet feeding direction and a driving force which is pressed against the feed roller to form a pair and which drives in the opposite direction via a torque limiter. A friction separating roller type sheet feeding device having a separating / feeding section composed of a separate roller provided with a pressure roller, a pressure contact means for pressing the separate roller against the feed roller, and a release for releasing the pressure contact by the pressure contact means. In a sheet feeding device including a member and a driving unit that drives the releasing member, the pressing unit or the releasing member is provided with a forced releasing unit, and the driving unit drives the releasing member to cause the pressing unit to drive the releasing member. The separate roller is forcibly released from the pressure contact with the feed roller, and the separate roller is pressed against the feed roller. On, the forced release portion is resolved by having the separate roller or the support member and the gap.

Further, in order to solve the above-mentioned problems, the present invention provides a sheet detecting means near the downstream side of the separating and feeding section in the sheet conveying direction, and the sheet detecting means is provided after the sheet to be fed. When the edge is detected, it is proposed to release the pressure contact of the separate roller with the feed roller.

Further, according to the present invention, in order to solve the above-mentioned problems, a sheet detecting means is provided in the vicinity of the downstream side of the separating and feeding section in the sheet conveying direction, and the sheet detecting means is continuously fed. It is proposed to release the pressure contact of the separate roller with the feed roller when the trailing edge of the final sheet is detected.

[0015]

The pressure contact means for pressing the separate roller against the feed roller, or the release member for releasing the pressure contact is provided with a forced release portion, and the release member is driven by the drive means to release the pressure contact of the separate roller with the feed roller. At this time, the pressure release is forcibly released by the force release unit. When the separate roller is in pressure contact with the feed roller, the forced release section has a gap with the separate roller or its supporting member, so that the forced release section affects the pressure contact operation and the pressure contact release operation. To prevent.

Other functions will be apparent from the description of the embodiments below.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The sheet feeding device of this embodiment is mounted in a copying machine, and FIG. 1 shows the vicinity of the separation feeding section. As shown in this figure, the paper feeding device of the present embodiment includes a pressure lever 4
Since the sheet feeding device has the same configuration as that of the sheet feeding device described with reference to FIG. 3 except that the shape is different, duplicate description will be omitted.

As shown in FIG. 1, the pressure lever 4 of the sheet feeding apparatus of this embodiment has a forced release portion 4d extending upward in a U-shape from the upper side portion 4a near the rotation shaft 6 thereof. There is. The forced release portion 4d is configured to surround the bearing 8 of the separate roller shaft mounted on the upper side portion 4a by about half.

FIG. 3 is a side view showing the structure around the pressure lever 4 and the bearing 8. As shown in this figure, the bearing 8 is arranged in the space of the guide member 15 and is mounted on the upper side portion 4 a of the pressure lever 4. Then, similarly to the above-described paper feeding device, the pressure lever 4 rotates about the shaft 6 as a fulcrum, whereby the bearing 8 is guided by the guide member 15 to slide up and down. The guide member 15 is omitted in FIGS. 1 and 3. Further, as shown in this figure, a slight gap is provided between the forced release portion 4d of the pressure lever 4 and the bearing 8.

In the sheet feeding device of the present embodiment thus constructed, the operation from the copying operation start of the copying machine to the separation and feeding of the sheets is the same as that of the sheet feeding device described with reference to FIG. Omit it.

When the copying operation of the copying machine is completed, the solenoid 1 is turned off and the release lever 2 is rotated by the action of the spring 13. Then, the tip of the release lever 2 pushes the protruding portion 4c of the pressure lever 4 to the left in FIG. As a result, the pressure lever 4 has the shaft 6 as a fulcrum.
Rotate clockwise at. At this time, the pressure lever 4
Since the forced release portion 4d is provided in the, the forced release portion 4d pushes the bearing 8 downward. As a result, the separating roller 9 is reliably separated from the feed roller 10 by its own weight being applied with the pushing-down force by the forced releasing portion 4d.

In this embodiment, the separate roller 9
Is reliably separated from the feed roller 10, so that useless torque is prevented from occurring and power consumption is reduced.
The durability of the torque limiter can also be improved. Further, even when the weight of the separate roller is reduced, it is possible to reliably separate the separate rollers, so that the degree of freedom in design can be increased.

The spring 13 is pressed so that the force of the forced release portion 4d pushing down the bearing 8, that is, the force of the release lever 2 pushing the pressure lever 4 overcomes the biting force acting between the separate roller 9 and the feed roller 10. It goes without saying that it is set. Also, as mentioned above,
Since a slight gap is provided between the forced release portion 4d and the bearing 8, when the bearing 8 is pushed by the pressure lever 4 and guided by the guide member 15 to slide, the bearing 8 is added. The pressure lever 4 and the guide member 15 are not locked. If the forced release portion 4d is provided without a gap between the forced release portion 4d and the bearing 8, when the separate roller 9 is pressed against the feed roller 10 and released from the pressure contact, the upper side portion 4a of the pressure lever 4 or the forced release portion 4a is forced. Even if the bearing 8 is pushed by the release portion 4d, there is no play between the members, so that the bearing 8 cannot slide smoothly. Further, when the separate roller 9 is brought into pressure contact with the feed roller 10, the pressure lever 4
The weight of the bearing is applied to the bearing 8
There is also a possibility of defective press contact due to the above, or poor contact due to sliding of the bearing 8. Therefore, by providing a slight gap between the forced release portion 4d and the bearing 8, it is possible to prevent defective pressure contact and to provide a stable separation pressure between both rollers.
Moreover, since the bearing 8 slides smoothly, the pressure release force does not increase. Further, the upper side 4a of the pressure lever
Since the forcible release portion 4d has a U-shaped tip end portion, the workability is not impaired when the device is assembled. In addition, since the surface of the forced release portion 4d that comes into contact with the bearing 8 has a substantially circular shape that follows the shape of the bearing 8, when pushing down the bearing 8, the pushing-down force acts in the center direction of the bearing 8,
The pushing force does not escape.

By the way, the separation roller 9 is kept in pressure contact with the feed roller 10 during the copying operation of the copying machine even after the separation and feeding of the paper by the paper feeding device is completed. That is, the sheets separated and fed into one sheet by the separate roller 9 and the feed roller 10 are delivered to the conveying means in the subsequent stage, and the solenoid 1 is operated while the image forming operation of the image forming unit of the copying machine is being performed. Is in an energized (ON) state, the separate roller 9 is pressed against the feed roller 10 and is driven in the direction opposite to the paper feeding direction. Therefore, a load is applied to the drive source and useless power is consumed. Also, the durability of the torque limiter is reduced. Furthermore, the temperature of the solenoid 1 in the energized state rises. Therefore, the feed roller 1 of the separate roller 9 after the separation and feeding of the paper is completed.
The pressure contact time to 0 should be as short as possible. Therefore, as another embodiment of the present invention, a paper sensor for detecting the fed paper is provided in the vicinity of the downstream side of the separation feeding unit in the paper conveyance direction, and when the trailing edge of the fed paper is detected, the separate roller is detected. It is proposed to release the pressure contact of 9 with the feed roller 10.

That is, in another embodiment of the present invention,
A paper sensor (not shown) is installed in the vicinity of the downstream side in the paper transport direction of the separation / feed unit constituted by the separate roller 9 and the feed roller 10. Then, the copying operation of the copying machine is started, and the sheets separated into one sheet by the separating / feeding unit are separated roller 9 and feed roller 10.
It is fed through the nip part of. When the above-described paper sensor detects the trailing edge of the fed paper, the detection signal is sent to the control means (not shown), and the control means outputs an off signal to the solenoid 1. As a result, the separate roller 9 is separated from the feed roller 10 similarly to the sheet feeding device of the above-described embodiment described with reference to FIGS.
Therefore, it is possible to prevent useless generation of torque, reduce power consumption, and improve the durability of the torque limiter. Further, since the energization time of the solenoid 1 is shortened, it is possible to prevent the temperature rise of the solenoid 1.

However, when performing continuous copying with a high-speed copying machine, it is difficult to turn on / off the solenoid 1 for each sheet to press and release the separate roller 9 and the feed roller 10 from each other. Therefore, in such a case, the solenoid 1 is continuously turned on until the copying operation is completed, but even in that case, after the final sheet is separated and fed, the separate roller 9 is quickly fed to the feed roller 10. It is desirable to release the pressure contact. Therefore, as still another embodiment of the present invention, when the above-mentioned paper sensor detects the trailing edge of the last paper of continuously fed paper, the separate roller 9 releases the pressure contact with the feed roller 10. To propose. As a result, it is possible to prevent unnecessary torque from being generated after the end of continuous sheet feeding, reduce power consumption, and improve the durability of the torque limiter. In case of limitless paper feeding (switching to another paper feeding device that contains the same size paper when the paper is finished and continue feeding), the paper feeding is stopped Because you can speed up the timing,
There is a margin when switching to another paper feeding device.

[0028]

As described above, according to the paper feeding device of the present invention, since the pressing member or the pressure releasing member (in the embodiment, the pressing member 4 is provided with the forced releasing portion, the pressing force is applied). Since the member 4 also functions as a pressure release member) is provided with the forced release portion, the pressure contact of the separate roller with the feed roller can be reliably released. Therefore, there is no defect in the pressure contact release due to the biting force between the rollers, which is peculiar to the FRP type paper feeder, and it is possible to prevent the generation of useless torque, reduce the power consumption, and improve the durability of the torque limiter. .

According to the second aspect of the present invention, when the trailing edge of the separated and fed sheet is detected, the pressure contact of the separate roller with the feed roller is immediately released, so that useless torque is prevented from occurring and power consumption is reduced. The durability of the torque limiter can be improved. Further, it is possible to reduce the load of the driving means that drives the pressure release member.

According to the third aspect of the present invention, it is possible to prevent unnecessary torque generation after the end of continuous sheet feeding, reduce power consumption, and improve the durability of the torque limiter. Also,
There is a margin when switching to another paper feeding device by limitless paper feeding.

[Brief description of drawings]

FIG. 1 is a perspective view showing the vicinity of a separating / feeding section of an embodiment of a sheet feeding device of the present invention.

FIG. 2 is a side view showing the vicinity of a pressure lever of the sheet feeding device.

FIG. 3 is a perspective view showing an example of a conventional sheet feeding device.

[Explanation of symbols]

 1 Solenoid 2 Release Lever 4, 14 Pressure Lever 4d Forced Release Section 5, 13 Spring 8 Bearing 9 Separate Roller 10 Feed Roller 11 Torque Limiter 15 Guide Member S Feeding Direction

Claims (3)

[Claims] 1. A separating / feeding unit comprising a feed roller rotating in a sheet feeding direction and a separate roller which is pressed against the feed roller to form a pair and which is given a driving force in the opposite direction via a torque limiter. And a pressing member for pressing the separate roller to the feed roller, a releasing member for releasing the pressing contact by the pressing member, and a driving unit for driving the releasing member. In the sheet feeding device, the pressure contact means or the release member is provided with a forced release portion, and the drive means drives the release member to force the pressure contact means to press the separate roller against the feed roller. At the same time as releasing, when the separate roller is pressed against the feed roller, the forcibly releasing portion causes the separate roller to Sheet feeding apparatus characterized by having the supporting member and the gap. 2. A sheet detecting means is provided in the vicinity of the downstream side of the separating and feeding section in the sheet conveying direction, and when the sheet detecting means detects the rear end of the sheet to be fed, the feed roller of the separate roller. The sheet feeding device according to claim 1, wherein the pressure contact with the sheet is released. 3. A sheet detecting means is provided in the vicinity of the downstream side of the separating and feeding section in the sheet conveying direction, and when the sheet detecting means detects the trailing edge of the last sheet of continuously fed sheets, the separate sheet detecting means is provided. The sheet feeding device according to claim 1, wherein the pressure contact of the roller with the feed roller is released.