JPH0253338B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a feeder used in an image forming apparatus such as a copying machine, a facsimile machine, or a printer to feed out a large number of stacked sheets one by one starting from the top sheet. This relates to paper devices.

Prior Art The above-mentioned image forming apparatus is equipped with an automatic paper feeder that stacks a large number of sheets of paper or manuscripts on which images are to be formed, and feeds them into the apparatus one by one, starting with the topmost sheet of paper, as necessary. Although such devices are widely used, conventionally, most of the devices have been designed in such a way that a paper feed roller is pressed against the uppermost paper surface and the paper is taken out by friction. However, since such paper feeding devices utilize friction, there are cases where multiple sheets of paper are taken out at the same time, paper is soiled by the paper feeding roller, or there is a misfeed where the coefficient of friction decreases and paper fails to be taken out. There were problems such as the occurrence of

For this reason, paper feeding devices have been proposed in which the topmost paper is sucked and taken out using a conveyor belt with a large number of suction holes that apply negative pressure.
-220032 publication describes such a paper feeding device. This paper feeding device is provided with an air nozzle that opens near the leading edge of a pile of paper (original documents), and applies the negative pressure to the topmost sheet of paper that has been fanned by air ejected from the air nozzle. It has a structure in which it is sucked and taken out using a conveyor belt with a large number of suction holes.

Problems to be Solved by the Invention However, in a device that uses air ejected from an air nozzle to fan paper, the airflow not only flows between the topmost paper and the second paper. , other paper intervals, such as the above 2
The airflow between the top sheet and the second sheet also flows between the second sheet and the third sheet, trying to separate them.
There is no guarantee that the airflow will be stronger than the airflow between the second and third sheets, so if the separation between the second and third sheets is sufficient compared to the separation between the top and second sheets. , a double feed occurs in which the topmost sheet and the second sheet are fed at the same time, or the second sheet is dragged in the conveying direction due to frictional force with the topmost sheet and continues to feed after the topmost sheet is fed. In some cases, this may cause a follow-up to be sent out.

Additionally, the second sheet of paper that has been slightly fed due to friction with the topmost sheet of paper may stop at a slanted position and be sucked up and fed out in the next cycle, resulting in skewed feeding. Ta.

SUMMARY OF THE INVENTION The present invention aims to provide a paper feeding device which handles paper by airflow and which overcomes the above-mentioned drawbacks.

Means and Effects for Solving the Problems Therefore, in the present invention, a first nozzle group that supplies an airflow that levitates the uppermost sheet of stacked sheets to a position where it can be sucked onto a suction surface, and a A second nozzle group is provided for supplying an airflow to separate the uppermost sheet of paper sucked by the suction surface and the sheet below it. As a result, even if the airflow from the first nozzle group lifts both the topmost sheet and the sheet below it, the airflow from the second nozzle group is supplied between the topmost sheet and the sheet below it. to ensure that both sheets are separated.
Only the topmost paper is picked up and transported.

Furthermore, in the present invention, protruding from the suction surface,
a protrusion that partially bends the sheet of paper attracted to the suction surface; and a stop claw that is provided at the front in the paper transport direction and has a gap between the suction surface and the suction surface through which the sheet of paper that is suctioned to the suction surface can pass. and. Therefore, even if the paper below the topmost sheet moves in the transport direction with the topmost sheet due to friction,
When these sheets are bent by the protrusions, the leading ends between the two sheets are opened, so that the lower sheet hits the stop claw and is stopped at that position, and only the uppermost sheet is conveyed. The paper that hits the stop claw and is stopped will be attracted in the next paper feeding cycle, but since the paper is guided by the stop claw and stopped in the correct direction, skew feeding will not occur.

Also. In the present invention, a groove is formed in the suction surface to allow airflow supplied from the second nozzle group above the uppermost sheet to escape. This results in
The suction force of the uppermost sheet of paper against the suction surface is not weakened by the airflow supplied above it from the second nozzle group. Particularly, when the above-mentioned stop claw is provided and the paper is thin and weak, the leading edge of the topmost paper that has been attracted may be peeled off from the suction surface by the airflow from the second nozzle group. There is a possibility that paper jams may occur if the stop pawl gets caught, but by providing the groove as described above, such a possibility is eliminated.

Example Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic elevational view showing one embodiment of the present invention. Reference numeral 1 denotes a paper feed tray, on which a large number of sheets of paper 2 are stacked. A paper feed conveyor 3 is arranged above the paper feed tray 1. This paper feed conveyor 3 is composed of a conveyor belt 6 stretched between a driving roller 4 and a driven roller 5, and the conveyor belt 6 is provided with a large number of suction holes 7 passing through it in the thickness direction. A vacuum box 8 that opens toward the paper feed tray 1 is arranged inside the paper feed conveyor 3 surrounded by the conveyor belt 6. It is connected to the intake side of 10. The intake duct 9 also includes a suction valve 11 for sucking air through the suction hole 7 and the vacuum box 8.
and an intake valve 12 for directly sucking air from the outside.

The discharge port of the blower 10 is connected to a nozzle box 14 via a jet duct 13, and the nozzle box 14 has a first nozzle 15 and a second nozzle 1.
6 is provided. The first nozzle 15 and the second nozzle 16 are each provided in a plurality of groups, and the first nozzle 15 is located at the same height as the top layer of the stacked sheets 2, as shown in the figure. It is also provided so as to be oriented parallel to the paper surface. In contrast, the second nozzle 16 is oriented slightly upward. Reference numeral 17 denotes an actuator that detects the height of the paper 2. When several sheets of paper 2 are fed and the height of the paper becomes lower, the actuator 17 lowers and turns on a switch 18 (not shown). The motor rotates to raise the paper feed tray 1. Therefore, the uppermost layer of the stacked sheets 2 is always held at approximately the same height as the first nozzle 15.

As can be seen from FIG. 3, the conveyor belt 6 is divided into a plurality of parts and stretched parallel to each other between the rollers 4 and 5. Adsorption surface 21 due to the connected surfaces
is formed. The lower surface of the vacuum box 8 is open only at the portion adjacent to the conveyor belt 6.
The portion located between the conveyor belts 6 is not opened,
A groove 22 is provided in this portion. In other words, grooves 22 are formed in the suction surface 21 connecting the lower surfaces of each of the conveyor belts.

Further, a projection 23 fixed to the vacuum box 8 projects downward from the suction surface 21 between a pair of adjacent conveyor belts 6, 6. Furthermore, a stop claw 24 is fixedly disposed on the nozzle box 14 at the front in the paper conveyance direction, and the paper attracted to the suction surface can pass between the stop claw 24 and the suction surface 21. A gap 25 is formed.

The operation of this paper feeding device will be described below. First, a drive system (not shown) and the blower 10 are operated in response to a start signal, and the air sucked into the intake duct 9 through the intake valve 12 is supplied to the nozzle box 14 through the jet duct 13, and the airflow is ejected from the first nozzle 15. is sprayed onto the leading edge of the paper 2 in the uppermost layer, and the leading edges of the paper 2 are floated and separated from each other. Next, the suction valve 11 opens in response to the paper feed signal (at this time, if the pressure inside the suction duct 9 increases, the suction valve 12 closes), and the suction force of the blower 10 is applied to the suction hole through the suction duct 9 and the vacuum box 8. 7, and as shown in FIG. 2, the floating uppermost sheet 2a is attracted onto the conveyor belt 6. In this state, the airflow ejected from the second nozzle 16
This airflow separates the sheets 2a and 2b. Note that, since the strong suction force of the blower 10 acts on the uppermost sheet 2a through the suction hole 7, the sheet 2a is attracted to the conveyor belt 6 regardless of the above-mentioned airflow.
When the suction valve 11 is opened and a certain period of time has elapsed, a clutch (not shown) provided on the drive roller 4 is engaged, and the conveyor belt 6 is driven via the drive roller 4, and the top suctioned thereon is driven. The upper sheet 2a is sent out to the conveyance roller 19. When the leading edge of the paper 2a is detected by the photo sensor 20, the clutch is disengaged, the conveyor belt 6 is stopped, and the suction valve 11 is closed. At the same time, the intake valve 12 is opened due to the pressure difference between the inside and outside of the intake duct 9, so that the supply of air to the nozzle box 14 is continued.

By the way, the top sheet 2a and the second sheet 2b
If the separation from the uppermost sheet 2a is insufficient, the second sheet 2b moves in the conveyance direction due to the frictional force with the uppermost sheet 2a, but these sheets 2a and 2b do not touch the protrusion 2.
3, the vicinity of the sheet 2b is pushed down by the protrusion 23 and bent, so that the central portion of the leading edge of the sheet 2b is separated from the uppermost sheet 2a, as shown in FIGS. 2 and 3. Then, it hits the front stop claw 24 and stops at that position. Then, this paper 2b is transferred to the uppermost paper 2 in the next paper feeding cycle.
It is adsorbed and conveyed in the same manner as in a. In this way, double feeding and additional feeding of paper are reliably prevented. Further, since the paper 2b is regulated by the stop claw 24 and stopped in the correct direction in the conveyance direction, the paper 2b will not be fed diagonally in the next paper feeding cycle.

In addition, especially when the paper is thin and has low stiffness, there is a risk that the leading edge of the topmost paper 2a that has been sucked may peel off from the suction surface 21 and be caught by the stop claw 24 due to the airflow from the second nozzle 16. . In such a state, a large conveyance force is applied to the paper 2a due to the suction force, resulting in a paper jam, but as described above, the suction surface 21 is provided with the grooves 22. Even if there is an airflow blown above the paper 2a from the second nozzle 16, this airflow escapes to the outside through the groove 22 and does not exert any force on the paper 2a, so that the leading edge of the paper 2a is not peeled off. This will not cause paper jams. Also,
The gaps 26 formed on both sides of the protrusion 23 also fit into the groove 2.
It works the same as 2.

Effects of the Invention As described above, according to the present invention, in a paper feeding device that adsorbs and conveys the topmost sheet of stacked sheets, the topmost sheet is reliably separated from the paper below it, and the topmost sheet is Since only the paper is sucked and conveyed, there is no risk of double feeding or tracking of paper.

Also, even if the second sheet of paper moves due to friction with the topmost sheet, this second sheet of paper will be reliably stopped, and this sheet will be fed diagonally in the next paper feed cycle. There isn't.

Furthermore, even if the paper is thin and weak, the leading edge of the suctioned paper will not peel off from the suction surface and cause a paper jam.

[Brief explanation of the drawing]

FIG. 1 is a schematic elevational view showing an embodiment of the present invention;
FIG. 2 is a similar drawing showing the operating state of the same embodiment;
FIG. 3 is a front view of the main parts of FIG. 2 viewed from the left. DESCRIPTION OF SYMBOLS 1... Paper feed tray, 2... Paper, 3... Paper feed conveyor, 4... Drive roller, 5... Followed roller, 6... Conveyance belt, 7... Suction hole, 8... Vacuum box,
9... Intake duct, 10... Blower, 11... Adsorption valve, 12... Adsorption valve, 13... Fumes duct, 14
... Nozzle box, 15... First nozzle, 16... Second nozzle, 17... Operator, 18... Switch, 19
...Conveyance roller, 20...Photo sensor, 21...Adsorption surface, 22...Groove, 23...Protrusion, 24...Stop claw, 25
...Gap, 26...Void.

Claims (1)

[Scope of Claims] 1. In a paper feeding device that suctions and conveys the topmost sheet of stacked sheets, an airflow is supplied to float the topmost sheet of the stacked sheets to a position where it can be sucked onto the suction surface. 1st
a second group of nozzles that protrudes from the suction surface and supplies an airflow between the uppermost sheet of paper that has been floated and attracted to the suction surface and the sheet below it to separate the two sheets; a protrusion that partially bends the paper sucked to the suction surface; and a locking pawl provided at the front in the paper conveyance direction and having a gap between the suction surface and the suction surface through which the paper sucked to the suction surface can pass. A paper feeding device characterized by comprising: 2. In a paper feeding device that sucks and conveys the topmost sheet of stacked sheets, the first one supplies an airflow that lifts the topmost sheet of the stacked sheets to a position where it can be sucked onto the suction surface.
and a second nozzle group that supplies an airflow between the uppermost sheet of paper floated and sucked to the suction surface and the sheet below to separate both sheets, and the suction surface A paper feeding device characterized in that a groove is formed on a surface to release an airflow supplied from the second nozzle group above the uppermost sheet of paper.