JP2647268B2 - Sheet feeding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding a large number of sheets in an image forming apparatus. The present invention relates to a mechanism for replacing the paper feed roller with another paper feed roller when it has decreased.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional sheet feeding apparatus. In the figure, a laminated sheet P is generally made of rubber.
By the conveying action of the pair of sheet feeding rollers a, the sheet is picked up by the conveying roller b and the separating roller c, is separated one by one by the separating roller c, and is fed downstream by the conveying roller b. d is a motor for driving the paper feed roller.

[0003] Further, the sheet P is composed of a sheet feeding roller a and a sheet P.
Is picked up by the frictional force between the rollers, but the rubber roller surface has an appropriate amount of oil and maintains the frictional force. By picking up the sheet P, the oil on the surface of the paper feed roller a is robbed by the sheet P and gradually decreases. However, if the pick-up operation is stopped and left for a while, the oil will seep out from the inside of the roller. hand,
The oil on the surface recovers moderately.

[0004]

However, in the conventional example, since the sheet P is picked up only by a pair of paper feed rollers, when a large number of sheets P are continuously operated, the roller a Since the oil content on the surface continues to decrease, the frictional force against the sheet P decreases, which may cause a pickup failure. Further, if the operation of the roller a is continued in a state where the oil content is small, the surface of the roller a wears quickly, There is a disadvantage that the durability of the paper roller a deteriorates.

Therefore, the present invention divides the paper feed roller into at least two sets, each group is provided with a driving means for separating and contacting the sheet, and a drive means is provided between the paper feed roller and the separation / transport roller. A sensor for detecting the presence or absence of a sheet is provided, and when the sensor does not detect the sheet within a predetermined time after picking up the sheet, the signal of the sheet feed roller set in operation is separated from the sheet and deactivated according to the signal. Provided is a sheet feeding device that operates by bringing another sheet feed roller of a stopped group into contact with a sheet so as to prevent a reduction in frictional force of the roller and improve the durability of the roller. The purpose is to do so.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a stacked sheet and a plurality of paper feed rollers for picking up the stacked sheet. In the sheet feeding apparatus, the plurality of paper feed rollers are divided into at least two sets, and drive means for separating and contacting each set of paper feed rollers with the sheet are provided on the downstream side of the paper feed rollers. a detection sensor for detecting the presence or absence of the picked-up <br/> sheet, when the timing for detecting the sheet to which the sensor is picked up exceeds the predetermined time, receives the signal, was operating Control means for separating a set of sheet feeding rollers from the sheet and pressing another sheet feeding roller of the paused group against the sheet so as to perform a feeding operation. To be

[0007]

According to the above arrangement, the stacked sheets are picked up by a plurality of paper feed rollers and fed downstream.

[0008] At this time, from the feed roller of the operating set
When the pickup sensor detects that the picked-up sheet is
When the time exceeds the predetermined time, the signal is received.
The feed roller of the set that is operating according to the instruction of the control means
Is lifted by the driving means to deactivate and is at rest
A set of paper feed rollers is pressed against the sheet by
Move .

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view, and FIG. 2 is a perspective view of a part thereof. In FIG. 1, reference numeral 1 denotes a sheet feeding device, and a large number of sheets P are stacked on a deck type cassette or the like.

Arms 3a, 3b and 4a, 4b are pivotally supported by the fixed support rod 2, and the ends of the arms 3a, 3b on the side of the feed roller 5 are fixed to each other to form a shaft. A paper feed roller 5 is pivotally supported. Arms 4a, 4
b is formed in the same manner as the arms 3a and 3b, and the paper feed roller 6 is pivotally supported at the end.

Then, pulleys 5 are attached to the side ends of the rollers 5 and 6.
a, 6a are provided, and motors 7, 8 having pulleys 7a, 8a at their shaft ends are fixed at positions facing the pulleys 5a, 6a.
The belts 9 and 10 are stretched around a and 8a.

The fixed solenoids 11a, 11a
1b is connected to the arms 3b and 4a. When the solenoids 11a and 11b are turned on, the paper feed rollers 5 and 6 are lifted away from the sheet P via the arms 3b and 4b, and when the solenoids 11a and 11b are turned off. The paper rollers 5 and 6 are pressed against the upper surface of the sheet P by their own weight.

A separating / transporting roller 12 composed of a separating roller 12a and a transporting roller 12b is provided downstream of the paper feeding rollers 5 and 6.
A sheet detection sensor 13 for detecting the presence or absence of the sheet P is provided between the separation roller 6 and the separation / conveyance roller 12.

After the feed rollers 5 and 6 are activated, the leading edge of the sheet P is detected by the detection sensor 13 to determine the speed thereof.
A control unit 14 is provided for controlling the solenoid 11a or 11b of the feed roller 5 or 6 in operation to be turned off and the solenoid 11b or 11a to be turned on.

Next, the operation of this embodiment will be described.

When a large number of sheets P are stacked and a detection sensor for detecting the presence or absence of the sheets P is turned on to instruct sheet feeding, for example, the paper feed roller 5 is rotated by a motor 7 in the direction of the arrow and the solenoid is operated. When the sheet 11a is turned off, the sheet feeding roller 5 is pressed against the stacked sheets P by its own weight, and the pickup operation is started.

At this time, the solenoid 11b is turned on, the paper feed roller 6 is lifted, and is separated from the sheet P.

As shown in FIG. 1, the sheet P is conveyed to the separation / conveyance roller 12 by the paper feed roller 5, and the multiply fed sheet P is separated by the separation roller 12a, and one sheet P is moved to the downstream side. It is carried out and conveyed to an image forming unit or the like.

When such a pickup operation is repeated, the oil on the rubber surface of the paper feed roller 5 decreases, and after the sheet P is picked up, the detection sensor 1
The control unit 1 determines that the delay of the time to reach the third time exceeds a predetermined time.
4, at that time, after the fed sheet P has passed, the solenoid 11 a is turned on to lift the sheet feed roller 5, separate from the sheet P, and turn off the solenoid 11 b to feed the sheet P. The roller 6 is lowered onto the sheet P, and starts picking up the sheet P by its own weight. At this time, the paper feed roller 5 is separated from the sheet P.
After a while, the separated roller 5 allows oil to seep out from the inside of the rubber forming the roller 5 to recover the conveying force. Then, it waits for the time when the oil content of the roller 6 decreases and is switched.

Next, another embodiment will be described with reference to FIGS.

The paper feed rollers 5 and 6 are supported by shafts 15 and 16 on support plates 17 and 17, respectively.
The shaft 7 is supported by a shaft 21, and the shaft 21 is supported by a fixed device frame (not shown).

A double pulley 18 is fixed to the shaft 21. Pulleys 15a and 16a opposed to the double pulley 18 are fixed to the shafts 15 and 16, respectively. And belts 15b and 16b are stretched. A pulley 21a is fixed to the end of the shaft 21, and a roller drive motor 22 having a pulley 22a at the end of the shaft facing the pulley 21a.
And a belt 22b is stretched between these pulleys 21a and 22a.

A pulley 17a is provided on one side of the support plate 17.
A support plate drive motor 19 having a pulley 19a at the shaft end facing the pulley 17a is fixedly provided, and a belt 20 is stretched between the pulleys 17a and 19a.

Further, holes 5a and 6a are provided on the other side of the support plate 17 at equal distances from the shaft 21 and in directions opposite to each other. The holes 5a and 6a are fitted into these holes 5a and 6a when turned off. When a solenoid 23 having a push rod 23a which comes out when the switch is turned on is fixed, and the push rod 23a is fitted in the hole 5a, the roller 5 comes into pressure contact with the sheet P and the hole 6a
, The roller 6 is pressed against the sheet P.

When the support plate 17 is rotated, the solenoid 23 is turned on so that the push rod 23a comes out of the holes 5a and 6a.

In such a configuration, for example, the paper feed roller 5
When the control unit 14 determines that the delay of the time for detecting the leading edge of the sheet P by the sensor 13 shown in FIG. 1 exceeds a predetermined time, the sheet P being fed at that time passes. After that, when the solenoid 23 is turned on and the support plate drive motor 19 rotates the support plate 17 by 180 degrees, the solenoid 23 is turned off, and the sheet feeding roller 6 is pressed against the sheet P, and at this time, the sheet feeding roller 5 Leave P. Other operations are the same as those of the above embodiment.

[0028]

As described above, according to the present invention,
When the timing at which the sheet picked up from the activated paper feed roller is detected by the detection sensor exceeds a predetermined time, the activated paper feed roller is lifted by the driving means in accordance with an instruction from the control means. To stop the operation, and operate the paper feed rollers of the paused pair. That is,
When the oil content of the operating paper feed roller decreases and slipping begins to occur on the sheet, the oil oozes out on the roller surface during pausing, and is replaced with a paper feed roller whose frictional force has been recovered. Since the paper feed roller always holds the necessary frictional force, the durability of the paper feed roller can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention and including a control block diagram.

FIG. 2 is a perspective view of a part of FIG.

FIG. 3 is a front view of another embodiment.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a conventional perspective view.

[Explanation of symbols]

1: sheet feeding, 5, 6: feeding roller, 12:
Separation / conveyance rollers, 11a, 11b: driving means (solenoid); 13, detection sensors; 14, control means (control section);

Claims (1)

(57) [Claims] 1. A sheet feeding apparatus having a stacked sheet and a plurality of sheet feeding rollers for picking up the stacked sheet, wherein the plurality of sheet feeding rollers are divided into at least two sets. A drive unit for separating and contacting each set of sheet feeding rollers with the sheet; a detection sensor provided downstream of the sheet feeding roller and the separation / conveyance roller to detect the presence or absence of the picked-up sheet; when the timing for detecting the sheet in which the detection sensor is picked up exceeds the predetermined time, receives the signal, the paper feed roller pair that was operated away from the sheet, were other resting set And a control means for controlling the sheet feeding roller to press the sheet against the sheet to perform a sheet feeding operation.