JPH0521808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic paper feeder that takes out sheets of paper stacked on a paper feed tray in order from the topmost one and supplies them to a copying machine, a facsimile machine, or the like.

2. Description of the Related Art An automatic paper feeder that has been widely used in the past is a device that takes out a large number of sheets of paper stacked on a paper feed tray one by one, starting from the topmost one, and feeds it into a copying machine, etc. However, as a conventional example, there is the one shown in FIGS. 3 and 4 (Japanese Patent Application Laid-Open No. 58-220032).

A conveyor belt 2 having a large number of suction holes 1 is wound around a drive roll 4 and an idler roll 3, and is rotated in the direction of arrow A by a motor (not shown).
A vacuum box 5 is provided inside the conveyor belt 2 and the rolls 3 and 4, and the air in the vacuum box 5 is discharged through an intake duct 6 by a vacuum fan 7. However, the discharged air is configured to be ejected from the air nozzle 9 via the ejection duct 8. The air nozzle 9 picks up the paper 11 accumulated on the paper feed tray 10.
It opens near the tip. Then, air is ejected from the air nozzle 9 to lift the paper 11 from the uppermost one, and at the same time, the negative pressure generated in the suction hole 1 sucks the uppermost paper, and the paper adsorbed to the conveyor belt 2 is removed from the top. The sheets are supplied one by one onto a platen glass of a copying machine, for example, by means of transport rolls 12 and 13.

Problems to be Solved by the Invention However, in such a conventional automatic paper feeder, when the sheets 11 are taken out one by one from the paper feed tray 10, the frictional force between the sheets causes the uppermost sheet to fall to the lower sheet. The paper, that is, the second paper from the top, is attracted, and these papers are overlapped and transferred to the conveyor belt 2.
There was a problem that it was supplied by This problem arises because the air flow rate blown between the topmost paper and the second paper on the paper feed tray 10 is smaller than the air flow rate between the second paper and the third paper. It is understood as something that occurs.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an automatic paper feeder that reliably transports sheets stacked on a paper feed tray one sheet at a time, starting from the top sheet. purpose.

Means for Solving the Problems The automatic paper feeding device of the present invention includes a plurality of conveyor belts arranged at a distance from each other above a tray on which paper is placed, and a plurality of conveyor belts that are arranged at a distance from each other above a tray on which paper is placed, and a first air nozzle group that ejects air to levitate upper sheets of paper on the tray; suction means that generates negative pressure on the back side of the conveyor belt to attract the levitated sheets to the surface of the conveyor belt; a second air nozzle group provided below the conveyor belt that ejects air toward the vicinity of the downstream side in the direction in which the paper is conveyed by the conveyor belt of the suction means; and an air flow collision wall that switches the direction of the air flow toward the upstream side in the direction in which the paper is conveyed by the conveyor belt.

Effect According to the present invention, the uppermost sheet of paper placed on the tray is levitated by the air jet from the first air nozzle group, comes under the action of the suction force of the suction means, and is attracted to the conveyor belt. and transported.

Due to the air jet emitted by the first air nozzle group,
It would be fine if only the topmost sheet of paper on the tray could be levitated, but due to the adhesion force caused by static electricity between the sheets, the topmost sheet of paper could be stuck tightly and the sheets below it could also be levitated. There is. In this case, a plurality of sheets may be attracted to the conveyor belt and cause double feeding, but this is prevented by the second air nozzle group and the air flow collision wall.

That is, the air jet from the second air nozzle group collides with the air flow collision wall and its direction is switched,
It flows toward the leading edge of multiple sheets of paper that have been attracted or are being attracted to the conveyor belt, and actively flows between the topmost sheet of paper and the sheets of paper below it, separating the sheets of paper below it from the topmost sheet. let Therefore, even if only the top sheet of paper is attracted to the conveyor belt, or even if the top sheet of paper is attracted to the conveyor belt while the lower sheet is in close contact with the top sheet, the lower sheet of paper is attached to the top sheet of paper. Since the sheets are separated from each other, double feeding of sheets is reliably prevented.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings, and components that are substantially the same as those in FIGS. 3 and 4 are denoted by the same reference numerals.

FIG. 1 shows a schematic configuration of an embodiment of the present invention, and FIG. 2 shows a perspective view of the main parts thereof.

A paper guide plate 15 is provided on the paper feed tray 10 for positioning the stacked papers 11. Directly above the stacked sheets 11, a plurality of conveyor belts 2 rotated in the direction of arrow A in FIG. 1 by drive rollers 4 and idler rollers 3 are wound at a distance from each other in the same manner as shown in FIG. has been done. The conveyor belt 2 is provided with suction holes (not shown), and negative pressure is generated near the suction holes by suction of air from the vacuum box 5. Suction duct 6 connected to airbox 5
The downstream side is connected to a vacuum fan 7, and further downstream thereof is connected to a nozzle box 18 via a jet duct 8. A vacuum valve 16 is provided in the middle of the intake duct 6 for sucking the uppermost sheet of paper onto the conveyor belt 2.
A relief valve 17 for supplying air to a first air nozzle group 19 and a second air nozzle group 20, which will be described later, is provided downstream thereof.

The first air nozzle group 19 is attached to the air box 18 so that the ejected air hits the upper part of the leading edge of the sheets 11 being deposited, and the second air nozzle group 20 is inclined at an angle α with respect to the top surface of the sheets 11. The air box 18 blows jet air toward the flat air flow collision wall 21 provided.
installed on. More specifically, the first air nozzle group 19 generates an air flow substantially parallel to the sheets of paper stacked on the paper feed tray 10 to levitate the uppermost sheets of paper, and transfer the uppermost sheets of these sheets to the conveyor belt. 2 to a position where it can be sucked. When a plurality of sheets of paper are levitated by the first air nozzle group 19, the second air nozzle group 20 separates both sheets by blowing air between the topmost sheet and the second sheet immediately below it. The aim is to Here, the three second air nozzle groups 20 are oriented in the direction in which the air ejected from each other is concentrated, and the jets of these air nozzles collide with the air flow collision wall 21, and the direction of the air nozzles is conveyed by the conveyor belt 2. When the direction is switched to go in the opposite direction (indicated by symbol B in FIG. 1) and a plurality of sheets of paper 11 are levitated by the air of the first air nozzle group 19, the uppermost sheet of paper and the sheet immediately below it. This flows between the topmost sheet of paper and the sheet immediately below it, creating stagnant pressure, which cancels out the attraction force caused by static electricity between the topmost sheet of paper and the sheet immediately below it, and causes the topmost sheet of paper to move from the topmost sheet of paper to the sheet immediately below it. separate. The air flow impingement wall 21 is inclined at an angle α with respect to the stacked sheets 11, thereby serving to increase the stagnation pressure.

The highest sheet of paper adsorbed on the conveyor belt 2 is
The transport roll 1 is transported in the direction of arrow B shown in the figure.
2 and 13, the leading edge of the paper is then detected by a photo sensor 22. Note that an actuator 23 is provided on the paper feed tray 10 to detect the height of the stacked papers, and when these papers are consumed and the height becomes low, the actuator 23 acts to detect the height of the stacked papers (not shown). When the switch is turned on, a tray motor (not shown) rotates at the same time to raise the paper feed tray 10 to a predetermined position. Thereafter, when the paper feed tray 10 reaches a predetermined position, the actuator 23 also rises, so by turning off the switch and turning off the tray motor, the paper feed tray stops at that position.

Next, the operation of this embodiment will be explained. First, the vacuum valve 16 is closed, and the relief valve 17 is closed.
is in the open state, and when the vacuum fan 7 is driven, air is supplied to the nozzle box 18 via the relief valve 17 and the jet duct 8, and air jets are generated from the first air nozzle group 19 and the second air nozzle group 20 at predetermined levels. It is ejected in the direction of. 1st
The air from the air nozzle group 19 applies an air stream to the upper part of the paper stacked on the paper feed tray 10,
Air flow collision wall 2 from the other second air nozzle group 20
The air supplied at step 1 is supplied so as to create stagnation pressure between the top sheet of paper and the sheet immediately below it. Therefore, the uppermost sheet of paper loaded on the paper feed tray 10 is levitated by the first air nozzle group, and the second air nozzle group is used to separate the uppermost sheet from the sheet immediately below it.
It is measured by the air nozzle group 20.

Vacuum valve 16 is open, relief valve 1
7 is closed, the action of the vacuum fan 7 causes negative pressure to be generated in the air box 5 through the intake duct 6, and this negative pressure is generated in suction holes (not shown) formed in the conveyor belt 2, thereby causing the conveyor belt to close. 2. Suction the topmost sheet of paper onto the top. At this time, when the negative pressure in the intake duct 6 rises to a predetermined value or more, the relief valve 17 is opened.

When a predetermined period of time has elapsed after the vacuum valve 16 was switched from the closed state to the open state, a clutch (not shown) connected to a drive source (not shown) is turned ON.
, the drive roll 4 is rotated in the direction of arrow A, and the conveyor belt 2 is driven in the direction of arrow B. The paper transported by the transport belt 2 is transported by the transport roll 1
2 and 13, and then passes through the photo sensor 22. When the photo sensor 22 detects the leading edge of the paper passing through, the clutch is turned OFF to stop the operation of the drive roll 4, and the vacuum valve 16 is turned off.
to the closed state. As a result, the paper that had been sucked up to that point is peeled off from the conveyor belt 2, and the paper is supplied via the conveyor rolls 12 and 13 to a platen glass (not shown) of a copying machine, for example.

Effects of the Invention As explained above, according to the present invention, the uppermost sheets of the sheets stacked on the paper feed tray are
The paper is levitated by the air jet from the air nozzle group, and the lowermost paper is separated from the uppermost sheet by the air jet supplied from the second air nozzle group through the air flow collision wall.
The uppermost sheet of paper and the sheet immediately below it can be reliably separated, thereby producing the effect that double feeding of sheets can be prevented. Therefore, it is possible to reliably transport the sheets stacked on the paper feed tray one by one starting from the top one.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing one embodiment of the present invention, Fig. 2 is a perspective view showing its main parts, Fig. 3 is a schematic structure diagram showing a conventional example, and Fig. 4 is a plan view showing its main parts. It is a diagram. 2: Conveyor belt, 4: Drive roll, 6: Intake duct, 7: Vacuum fan, 10: Paper feed tray, 11: Paper, 16: Vacuum valve, 1
7: Relief, 18: Nozzle box, 19: First air nozzle group, 20: Second air nozzle group, 2
1: Air flow collision wall.

Claims (1)

[Scope of Claims] 1. A plurality of conveyor belts arranged at a distance from each other above a tray on which sheets of paper are placed; an automatic paper feeder comprising: a first air nozzle group that levitates the paper; and a suction unit that generates negative pressure on the back side of the conveyor belt to attract the floated paper to the surface of the conveyor belt; a second air nozzle group provided below the conveyor belt for ejecting air toward the downstream side of the conveyance direction of the paper by the conveyor belt; and a second air nozzle group disposed on the back side of the conveyor belt. An automatic paper feeder comprising: an air flow collision wall that switches the air flow direction to be directed upstream in the direction in which the paper is conveyed by the conveyor belt.