JPS6056738A - Sheet feeder - Google Patents

Abstract

PURPOSE:To reliably feed a sheet regardless of the thickness and rigidity of the sheet by measuring the amount of time from the start of suction to the time the uppermost sheet on a tray is adsorbed to a transport belt and increasing or decreasing the vacuum pump operation voltage according to whether the measured amount of time is longer or shorter than a reference time. CONSTITUTION:The applied voltage to a vacuum pump 21 is increased or decreased according to whether the amount of time from opening of a shut-down valve 24 of adsorbing means 40 to the time sucking force works upon the uppermost sheet 1a on a tray 2 to be adsorbed to a transport belt 3 is longer or shorter than a reference time previously set corresponding to the thickness and rigidity of the sheet 1, so that the rotational frequency of the pump 21 is increased or decreased to increase or decrease the sucking force of the adsorbing means 40 for the sheet 1a. Thus, suitable sucking force works upon the sheet corresponding to the thickness and rigidity of the sheet, whereby a sheet can be fed reliably regardless of the thickness and rigidity of the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding device, and more specifically, a conveyor belt is disposed above the end of a tray on which paper is placed, and installing an air jetting means for jetting air to the end face of the sheet to separate the sheets from each other; and installing a soaking suction means for sucking the sheet on the conveyor belt ζ;
Relating to a paper feeding device, wherein only the uppermost sheet of the sheets of paper levitated by the air jetting means is adsorbed to the conveyor belt by the suction means, and the uppermost sheet is conveyed by driving the conveyor belt. .

[Prior art]

2. Description of the Related Art Conventionally, there is a paper feeding device that feeds paper on a tray by using the suction force of air.

FIG. 1 shows an example of such a conventional paper feeding device.

In such a paper feeding device, a conveyor belt 3 is disposed above the end of a tray 2 on which a plurality of sheets of paper 1 are placed, and an air jetting means 1° is disposed in front of the tray 2.
A suction means 2° is installed on the conveyor belt 3. here,
The conveyor belt 3 has a large number of holes 3a formed throughout, and is wound around a conveyor belt drive roll 4a and its driven roll 4b. Note that the conveyor belt 3 is driven at a predetermined timing, as will be explained later.

Further, the air blowing means 10 includes a blower 11, a duct 12
and a nozzle plenum 13.

Nozzles 13a and 13b are formed in the nozzle plenum 13. That is, in the air blowing means 1°, air is sucked into the blower 11 from the atmosphere and sent into the nozzle plenum 13 via the duct 12. Furthermore, the air is ejected from the nozzle plenum 13 to the end surface of the paper 1 via the nozzle 13a, and is also ejected to the front end of the conveyor belt 3 via the nozzle 13b. The adsorption means 20 includes a vacuum pump 21,
It consists of a duct 22, a vacuum plenum 23, etc. The bakiem pleenum 23 has an open bottom surface. That is, in this adsorption means 20, air in the vacuum plenum 23 is sucked into the vacuum pump 21 via the duct 22, and is discharged from the vacuum pump into the atmosphere. At this time, a suction force is applied to the paper 1 on the tray 2 through the opening 23a of the vacuum plenum 23 and the hole 3a of the conveyor belt 3 due to the negative pressure generated within the vacuum plenum 23. In addition, the first
In the figure, 5 is an elevator tray that supports the tray 2 in a vertically movable manner, 6a and 6b are paper guides installed on the tray 2, 7a is a drive roll for transporting paper, and 7b
is a driven roll for transporting paper, and 8 is a transport paper detection switch (
9 is a paper conveyance guide, 24 is a normally closed shutdown valve installed in the suction side duct 22, and 30 is a stack height switch from the bottom plate 5a of the elevator tray 5 to the top of the paper 1 on the tray 2. This is a switch (self-resetting normally open switch) for detecting the height up to the upper sheet 1a.

Next, the operation of the paper feeding device will be explained with reference to FIGS. 2(a), Φ), and (C).

In such a paper feeding device, when a power switch is closed, a start signal is issued from a control section (not shown), and the blower 11 and vacuum pump 2f are operated. Then, the sheets of paper located above the sheet of paper 1 are separated from each other and floated by the air ejected from the nozzle 13a (see FIG. 2(a)). Next, when the operator operates a paper feed start button (not shown), a feed signal is generated from the control section. Then,
A shutdown valve driving solenoid (not shown) is activated, and the shutdown valve 24 is opened. As a result, suction force by the suction means 20 is applied to the uppermost sheet 1a of the sheets of paper 1, and the sheet 1
a is attracted to the conveyor belt 3 (see Φ in FIG. 2). At this time, the air ejected from the nozzle 13b enters between the uppermost sheet 1a and the sheet 1b immediately below the sheet 1a, thereby causing the sheets 1a and 1b to be largely separated. Furthermore, after a predetermined period of time has elapsed since the feed signal was issued, a feed signal is issued from the control section and an electromagnetic clutch for driving the conveyor belt (not shown) is activated, whereby the power of the drive device (not shown) is transferred to the conveyor belt drive roll. 4a, and the conveyor belt 3 is rotationally driven. As a result, the paper 1a attracted to the conveyance belt 3 is sent out along the conveyance belt to the paper conveyance rolls 7a and 7b. Furthermore, paper 1a
is nipped by paper transport rolls 7a and 7b and sent to the next paper processing step (not shown).

At this time, the sheet 1a activates the actuator 8a of the conveyed sheet detection switch 8 to close the conveyed sheet detection switch (see FIG. 2). This transport paper detection switch 8
When the control section receives the closing signal, the control section cuts off the generation of the feed signal and the conveyor belt drive signal, closes the shutdown valve 24, and stops the rotation of the conveyor bell l-3. After the paper 1a is completely fed out from the paper transport rolls 7a and 7b, the actuator 8a of the transport paper detection switch 8 returns to its original position, the transport paper detection switch is opened, and the next paper feeding operation is ready. becomes. Then, when the next feed signal is issued by the control section, the paper feeding operation is repeated. Note that in this paper feeding device, when the stack height of the paper 1 becomes lower as the paper feeding progresses, the topmost paper of the paper 1 at that time is moved by the actuator 3oai of the stack height detection switch 30. The tray 2 is moved upward by elevator means (not shown) until the stack height detection switch is closed upon contact with the stack height detection switch, and the uppermost sheet is positioned at a height within a certain range.

In such a conventional paper feeding device, the flow rate of the pump 21 is always constant regardless of the thickness of the paper 1, so if the paper 1 is thin paper, multiple sheets of paper 1 If the paper 1 is made of thick paper, the suction force is insufficient because the paper 1 has a large weight and rigidity. 1 could not be adsorbed onto the conveyor belt 3, and there was a possibility that the paper could not be fed.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a paper feeding device that can reliably feed paper regardless of the thickness or rigidity of the paper.

[Structure of the Invention] In order to achieve the above object, the present invention includes a measuring means for measuring the time from when the suction means starts suction until the top sheet of paper on the tray is suctioned to the conveyor belt. At the same time, when the measurement time by the measurement means is longer than the reference time, the applied voltage for operating the vacuum pump in the adsorption means is increased, and when the measurement time is shorter than the reference time, the voltage applied to the vacuum pump is increased. A control means for reducing the applied voltage is installed to apply an appropriate suction force to the uppermost paper according to the thickness and rigidity of the paper.

〔Example〕

Hereinafter, a paper feeding device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 shows a main part of an embodiment of a paper feeding device according to the present invention. In FIG. 3, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the paper feeding device of this embodiment, the duct 22 of the suction means 40
Five relief valves forming part of a measuring means 50 (see FIG. 4), which will be described later, are installed at the bottom. This relief valve 51 is configured so that a hole 22a formed in the duct 22 is normally closed by a valve body 52. The valve body 52 is pin-coupled to the duct 22 at one end, and has a contact 53 formed at the other end. Contact point 5 of this valve body 52
A contact point 54 is formed on the duct 22 corresponding to No. 3.

Further, a weight 55 is attached to the valve body 52, and the relief valve 51 is closed by the weight of the weight.

The measuring means 50 measures whether the uppermost sheet 1a of the sheets 1 on the tray 2 is loaded after the shutdown valve 24 of the suction means 40 is opened, that is, after the suction means applies a suction force to the uppermost sheet 1a of the sheets 1 on the tray 2. This is to measure the time until the conveyor belt 3 adsorbs the IJ-F valve 5 mentioned above.
In addition to 1, it is equipped with a counter, etc. Further, this paper feeding device includes a control means 60 for controlling the voltage supplied to the pump 21.
It is equipped with As shown in FIG. 4, this control means 60 controls a preset reference time T+c! according to the thickness and rigidity of the paper 1 set on the tray 2. : The measured time T2 run by the measuring means 50 is compared, and if the measured time T2 is longer than the reference time Tl, the voltage applied to the pump 21 of the adsorption means 40 is increased by the operating section 6 of the control means. The rotation speed of the pump is increased to increase the suction force by the suction means 40. Further, when the measurement time T2 is shorter than the reference time Tl, the voltage applied to the pump 2 is reduced by the operation unit 61, the rotational speed of the pump is reduced, and the suction force by the adsorption means 40 is reduced.

In FIG. 3, 56 is a switch for stopping the tray 2 at the initial position when the tray 2 is moved upward after setting the paper 1 on the tray 2, and 57 is a switch for stopping the tray 2 at the initial position.
This is a switch for safety by stopping the tray 2 by cutting off the power supply to the drive motor of the elevator means (not shown) that moves the tray up and down when the tray 2 goes out of control.

Next, the operation of this embodiment will be explained with partial reference to FIG. 1 and also with reference to FIG. 5, and the configuration of this embodiment will be further clarified. Note that FIG. 5 shows the characteristics of the suction means 40 in the paper feeding device of this embodiment, where A is the characteristic curve of the pump 21 and B is the characteristic curve of the paper 1 on the tray 2.
A curve showing the relationship between the suction force P and the flow iQ in the suction means 40 before the top sheet 1a is attracted to the conveyor belt 3; It is a curve showing the relationship between the suction force P and the flow fcQ in the suction means 40.

In this paper feeding device, as in the case of the paper feeding device shown in FIG. 1, when a start signal is output from the control means 60,
When the blower 11 and the pump 21 are operated and a brief feed signal is output from the control means 60 at the next ζ),
The shutdown valve 24 is opened, and the adsorption means 40
A preset initial suction force Pa is applied to the uppermost sheet 1a of the sheets 1 on the tray 2. The operating point of the suction means 40 at this time is I in FIG. Due to the suction force Pa, the uppermost sheet 1a is attracted to the conveyor belt 3 over a period of time. At this time, the operating point of the suction means 40 shifts from ■ to ■ in FIG.

The suction force Pb at that time is considerably larger than the suction force Pa. Therefore, at this time, the pressure inside the duct 22 decreases greatly, so the relief pulp 51
The contact point 53 that was opened against the weight of the contact point 53 that was previously in contact
．． 54 are separated from each other. Here, the measuring means 5o measures the contact point 53 after the shutdown valve 24 is opened.
．． 54 are separated from each other.

Here, if the measured time T2 by the measuring means 5o is longer than the reference time T1 (such as when the paper 1 is thick and heavy), the air sucked from the suction means 4o will be longer than the reference time T1. is increased by an amount according to its size,
The uppermost sheet 1a of the sheets 1 on the tray 2 is strongly attracted by the increase in air. As a result, the time required for the uppermost paper 1a to be attracted to the conveyor belt 3 after the suction force is applied by the suction means 4o is shorter than before and is brought closer to the reference time Tl. t
However, if the measurement time T2 by the measurement means 5o is shorter than the reference time T1 (such as when the paper 1 is thin and light), the air sucked from the suction means 4o will exceed the difference between the measurement time T2 and the reference time Tl. The air is reduced by an amount corresponding to the size, and the uppermost sheet 1a is weakly sucked by the amount of air reduced.

As a result, the uppermost sheet 1a is transferred to the suction means 40.
Therefore, the time required from when the suction force is applied to when the paper is attracted to the conveyor belt 3 is made longer than before, and is brought closer to the reference time Tl.

〔Effect of the invention〕

As explained above, the paper feeding device according to the present invention reduces the time required for the topmost sheet of paper on the tray to be sucked by the conveyor belt after the suction force is applied by the suction means. Since the time is set close to a preset reference time according to the thickness and rigidity of the paper, it is possible to apply a suction force of an appropriate magnitude to the uppermost sheet according to the thickness and rigidity of the sheet. Therefore, when the paper is thin paper, there is no risk of double feeding, and when the paper is thick paper, there is no possibility that the paper cannot be fed, and the paper can be fed reliably.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing a conventional paper feeding device, Figure 2 (a)
, (b) and (C) are conceptual diagrams showing the effect, Part 3
The figure is a conceptual diagram showing one embodiment of the paper feeding device according to the present invention, FIG. 4 is a block diagram of its control means, and FIG. 5 is a graph showing the action of its suction means. ■...Paper, 1a...Top paper, 2...Tray, 3.Transportation belt, 3a...Hole, 4a.Transportation belt driving roller, 4b..Followed roller, 10.Air jetting means, 11. Blower, 12. Duct, 13. Nozzle plenum, 13a, 13b. Nozzle, 21. Pump, 22. Duct, 22a. Hole, 23. Vacuum plenum, 24.・Shutdown valve, 30
...Stack height detection switch, 40...Adsorption means,
50... Measuring means, 51... Relief valve, 52...
... Valve body, 53.54 ... Contact, 55 ... Weight, 60 ... Control means, 61 ... Operation section. Figure 1 11 Figure 3. . 1o 11 Figure 2 (0) (b) 88ノ (C) 8a'

Claims (1)

[Claims] A conveyor belt is disposed above the end of the tray on which the paper is placed, and an air jetting means is installed to blow air to the end surface of the paper to separate the paper from each other. A suction means for adsorbing the above paper is installed, and only the uppermost sheet of the paper floated by the air jetting means is adsorbed to the conveying belt by the suction means, and the uppermost sheet is transferred to the transport belt. In a paper feeding device that is conveyed by a belt drive,
A measuring means is installed to measure the time from when the suction means starts suction until the uppermost sheet is attracted to the conveyor belt, and if the time measured by the measuring means is longer than the reference time, increasing the applied voltage for operating the vacuum pump in the adsorption means;
If the measurement time is shorter than the reference time, a control means is installed to reduce the applied voltage so that an appropriate amount of suction force is applied to the top sheet of paper. A paper feeding device characterized by: