JPS6256052B2 - - Google Patents

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 An air jetting means for jetting air to the end face of the sheet to separate the sheets from each other is installed, and a suction means for sucking the sheets to the conveyor belt is installed, so that the sheets of paper levitated by the air jetting means are installed. The present invention relates to a paper feeding device in which only the uppermost sheet of paper is attracted to the conveyor belt by the suction means, and the uppermost sheet of paper 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 10 is disposed in front of the tray 2.
At the same time, a suction means 2 is installed on the conveyor belt 3.
0 is set. 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,
It consists of a duct 12, a nozzle plenum 13, etc. The nozzle plenum 13 includes nozzles 13a,
13b is formed. That is, in the air blowing means 10, 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 transferred from the nozzle plenum 13 to the nozzle 13.
It is ejected onto the end surface of the paper 1 via a, and
It is ejected to the front end of the conveyor belt 3 via the nozzle 13b. The adsorption means 20 includes a vacuum pump 21, a duct 22, and a vacuum plenum 2.
Consists of 3rd prize. The vacuum plenum 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 that time, the negative pressure generated in the vacuum plenum 23 causes the opening 23a of the vacuum plenum 23 and the hole 3a of the conveyor belt 3 to
A suction force is applied to the paper 1 on the tray 2 through the . In FIG. 1, reference numeral 5 indicates an elevator tray that supports the tray 2 in a vertically movable manner;
a and 6b are paper guides installed in tray 2;
Reference numeral 7a denotes a driving roll for paper conveyance, 7b denotes a driven roll for paper conveyance, 8 denotes a conveyance detection switch (return type normally open switch), 9 denotes a paper conveyance guide, and 24 denotes a normally closed roller installed in the suction side duct 22. The shutdown valve 30 is a stack height (height from the bottom plate 5a of the elevator tray 5 to the uppermost sheet 1a of the sheets 1 on the tray 2) detection switch (self-resetting normally open switch).

Next, the operation of the paper feeding device will be explained with reference to FIGS. 2a, b, 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 the vacuum pump 21 are operated. Then, the nozzle 13a
Due to the air ejected from the paper sheet 1, the paper sheets located above the paper sheet 1 are separated from each other and floated (see FIG. 2a). Next, when the operator operates a paper feed start button (not shown), a feed signal is generated from the control section. Then,
A solenoid for driving a shutdown valve (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 1, and the sheet 1a is suctioned to the conveyor belt 3 (see FIG. 2b). At this time, nozzle 1
The air ejected from the paper 3b enters between the uppermost sheet 1a and the sheet 1b directly 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 actuated, whereby the power of the drive device (not shown) is transferred to the conveyor belt. It is transmitted to the drive roll 4a, and the conveyor belt 3 is rotationally driven. Thereby, the paper 1a attracted to the conveyance belt 3 is sent out along the conveyance belt to the paper conveyance rolls 7a and 7b. Further, the 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 upper measuring means a operates the actuator 8a of the conveyed paper detection switch 8 to close the conveyed paper detection switch (see FIG. 2c). When the control section receives the closing signal of the paper carrying paper detection switch 8, the control section cuts off the generation of the feed signal and the conveyor belt drive signal, closes the shutdown valve 24, and shuts down the conveyor belt 3. stop the rotation. Paper 1
After the paper a is completely fed out from the paper transport rolls 7a and 7b, the actuator 8a of the transport detection switch 8 returns to its original position, the transport paper detection switch is opened, and the next paper feeding operation is enabled. Become.
Then, when the next feed signal is issued by the control section, the paper feeding operation is repeated. In addition,
In this paper feeding device, when the stack height of paper 1 becomes lower as paper feeding progresses, the topmost paper of the paper 1 at that time comes into contact with the actuator 30a of the stack height detection switch 30. Then, until the stack height detection switch is closed, the tray 2 is moved upward by an elevator means (not shown), and the uppermost sheet is positioned at a height within a certain range.

By the way, in such a conventional paper feeding device, in order to control the stack height of the paper 1 on the tray 2, the actuator 30a of the stack height detection switch 30 is activated by a part of the uppermost paper 1a of the paper 1. As described above, the switch is energized to operate and detect the stack height of the sheets 1. However, with such a configuration, the actuator 30a of the stack height detection switch 30 directly presses down a part of the top sheet 1a, which may cause skew to the top sheet 1a, or may cause the top sheet 1a to skew. If the upper sheet 1a is fluttering due to air disturbance from the air jetting means 10, there is a risk that the stack height detection switch 30 will detect a noise signal.

In view of this, conventional paper feeding devices have been devised in which the tray 2 is moved upward by a certain height when a certain number of sheets of paper 1 on the tray 2 have been fed. However, in such a paper feeding device, even if the tray 2 is moved up by the height corresponding to the number of sheets fed, if the thickness of the paper 1 changes, the distance to move the tray 2 up will change accordingly. Since it must be set separately depending on the thickness of paper 1,
It was very troublesome and difficult in practice.

In addition, in the conventional paper feeding device, the top paper 1a
There is one in which the stack height of the paper 1 is controlled by detecting the position of the paper 1 using a photo sensor or a mechanical switch. However, in such a paper feeding device, the top paper actually flaps due to the air from the air jetting means 10, so it is difficult to accurately detect its position, and there is no practical method. Nakatsuta.

Furthermore, in any of these conventional paper feeding devices, the distance between the topmost paper 1a and the conveyor belt 3 is constant regardless of the thickness of the paper 1, so if the paper 1 is thin paper, If multiple sheets of paper 1 are attracted to the conveyor belt 3 and conveyed, so-called double feeding, or if the paper 1 is thick paper, the paper 1 may not be attracted to the conveyor belt 3 due to insufficient suction power. , there was a risk that paper could not be fed.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and
To provide a paper feeding device that can reliably feed paper regardless of the thickness of the paper.

[Structure of the invention]

A measuring means is installed to measure the time from when the suction means starts suction until the top sheet of paper on the tray is suctioned to the conveyor belt, and when the measurement time by the measuring means is longer than a predetermined time, is installed with a control means that moves the tray upward and moves the tray downward if the measured time is shorter than the predetermined time, so that the top sheet of paper is always positioned at an appropriate height. The position of the uppermost paper is detected without using a photo sensor or mechanical sensor, and the uppermost paper is separated from the conveyor belt by an appropriate distance depending on the thickness of the paper. An appropriate amount of suction force is applied to the paper according to the thickness, rigidity, etc. 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 addition, in Figure 3,
Elements that are the same as those shown in FIG. 1 are designated by the same reference numerals.

In the paper feeding device of this embodiment, a relief valve 50, which constitutes a part of a measuring means to be described later, is installed in the duct 22 of the suction means 40. This relief valve 50 has a hole 2 bored in the duct 22.
2a is normally closed by a valve body 51. The valve body 51 is pin-coupled to the duct 22 at one end, and has a contact 52 formed at the other end. A line point 53 is formed on the duct 22 corresponding to the contact point 52 of the valve body 51. In addition, the valve body 5
1 is attached with a weight 54, and the relief valve 50 is closed by the weight of the weight.
The measuring means measures the time from when suction force is applied to the uppermost sheet 1a of the sheets 1 on the tray 2 by the suction means 40 until the uppermost sheet 1a is attracted to the conveyor belt 3. In addition to the above-mentioned relief valve 50, it is equipped with a counter and the like. In FIG. 3, 55 is a switch for stopping the tray at the initial position when moving the tray 2 upward after setting the paper 1 on the tray 2.
Reference numeral 6 denotes 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) for moving 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 FIGS. 1 and 4, and the configuration of this embodiment will be further clarified. In FIG. 4, A is the characteristic curve of the pump 21, and B is the suction force P and flow rate Q in the suction means 40 before the top sheet 1a of the sheets 1 on the tray 2 is suctioned to the conveyor belt 3. The curve C indicates the relationship between the suction means 4 after the uppermost sheet 1a has been suctioned to the conveyor belt 3.
It is a curve showing the relationship between suction force and flow rate Q at 0.

In this paper feeding device, when a start signal is output from the control means (not shown), as in the case of the paper feeding device shown in FIG.
is actuated and then a pre-feed signal is output from the control means, the shutdown valve 24 is activated.
is opened, and the suction means 40 picks up the paper 1 on the tray 2.
The suction force that is initially set in advance for the top paper 1a of
Let Pa act. The operating point of the suction means 40 at this time is shown in FIG. its suction power
Due to Pa, the uppermost sheet 1a is attracted to the conveyor belt 3 after a certain amount of time. At this time, the operating point of the adsorption means 40 is as shown in FIG.
Let's move on. 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 is greatly reduced, so the valve 50 is opened against the weight of the weight 54, and the contacts 52 and 53, which were in contact with each other until then, are separated from each other. Here, the measuring means completes measuring the time from when the valve 24 is opened until the contacts 52 and 53 are separated from each other. Here, if the time measured by this measuring means is longer than the standard time set in advance according to the thickness and rigidity of the paper, the elevator means (not shown) will move by a distance determined according to the length of time. The uppermost sheet 1a is positioned at an appropriate height by moving a tray (not shown) upward. Further, if the measurement time is shorter than the reference time, the tray 2 is moved down by a distance determined according to the shortness of the time.

In addition, in the above embodiment, the measuring means is the valve 50.
However, the present invention is of course not limited to this, and the point is to use a method (for example, a duct A method of installing a pressure sensor inside the duct 22, detecting a change in the pressure inside the duct 22 with the pressure sensor and detecting that the uppermost sheet 1a is attracted to the conveyor belt 3, etc.) is used. The measuring means may be configured in any manner as long as it is configured.

〔Effect of the invention〕

As explained above, in the paper feeding device according to the present invention, the suction force from the suction means is applied to the uppermost sheet of paper on the tray until the uppermost sheet is attracted to the conveyor belt. measure time,
Since the tray is moved up and down based on the difference between this measurement time and the reference time, the position of the topmost sheet of paper can be reliably detected without using a photo sensor or mechanical sensor. Since the difference between the time and the standard time differs depending on the thickness and rigidity of the paper, it is possible to separate the top paper by an appropriate distance from the conveyor belt depending on the thickness and stiffness of the paper, and thereby An appropriate suction force can be applied to the upper sheet of paper depending on the thickness and rigidity of the sheet. Therefore, there is no risk of double feeding when using thin paper, and there is no possibility that paper cannot be fed when using thick paper.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a conventional paper feeding device, FIG. 2 a, b, and c are conceptual diagrams showing its operation, and FIG. 3 is a conceptual diagram showing an embodiment of the paper feeding device according to the present invention. FIG. 4 is a graph showing the action of the adsorption means. 1...Paper, 1a...Top paper, 2...Tray, 3...Transport belt, 3a...Hole, 4a...
Conveyor belt drive roller, 4b...Followed roll, 1
0...Air blowing 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... suction means,
50... Relief valve, 51... Valve body, 52,
53... Contact, 54... Weight.

Claims (1)

[Scope of Claims] 1. Air jetting means 10, which has a conveyor belt 3 disposed above the end of the tray 2 on which the sheet 1 is placed, and jets air to the end surface of the sheet to separate the sheets from each other. At the same time, a suction means 40 for adsorbing the paper to the conveyor belt is installed, and only the uppermost sheet of the paper floated by the air jetting means is transferred to the conveyor belt by the suction means. In the paper feeding device, the uppermost sheet 1 is attracted to the conveyor belt 3 and the uppermost sheet is conveyed by driving the conveyor belt, and the uppermost sheet 1 is attracted to the conveyor belt 3 after the suction means 40 starts suctioning. A measuring means is installed to measure the time until the end, and when the time measured by the measuring means is longer than a predetermined time, the tray 2 is moved upward, and when the measured time is shorter than the predetermined time, the tray 2 is moved upward. The paper feeding device is characterized in that a control means for moving the tray 2 downward is installed so that the uppermost paper 1 is always positioned at an appropriate height.