JPH0789623A - Sheet feeding device and sheet material property detecting device - Google Patents

Abstract

PURPOSE:To provide separate carrying of sheets securely in a paper, feeding device using suction force of air by mounting a fluctuating means for fluctuating the distance of a sheet tray and a sheet suction part according to strength of the sheet and a control means for controlling the fluctuating means. CONSTITUTION:A first sheet S1 of a sheet sheaf S on a sheet tray 1 is sucked in a feeding means 14 by suction force of a sheet suction means 4 sucked air in by an air suction means 12 and the sheet is fed by the turning movement of this feeding means 14. Strength of the sheet S1 is detected by detecting means 30 and 31 mounted near the sheet suction means 4 when the sheet S1 is sucked in by the sheet suction means 4 and a fluctuating means 29 moves the sheet tray 1 according to this detected result and distance between the sheet tray 1 and the sheet suction means 4 is fluctuated by the fluctuating means 29. Thereby, various kinds of carried sheets S can be fed stably by the same suction force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device in an image forming apparatus such as an electrophotographic copying machine. More specifically, the sheet sucking force of air is used to transfer sheets from a stack of sheets stacked on a sheet tray. The present invention relates to a sheet feeding device that separates and conveys sheets one by one.

[0002]

[Prior art]

<Prior Art 1> Conventionally, a sheet feeding device in an image forming apparatus such as an electrophotographic copying machine is a roller sheet feeding device of a type that conveys sheets stacked on a sheet tray to the downstream side by rotation of a sheet feeding roller. Is common. In this conventional roller paper feeder, the roller surface is made of an elastic material such as rubber,
Moreover, the performance depends largely on the friction coefficient of the roller surface. Therefore, the feeding performance may not be stable due to changes in the roller outer shape due to wear, changes in the roller material over time, changes in the friction coefficient on the roller surface due to paper powder adhesion, etc. It had the drawback of not having it.

In view of the above-mentioned problems, there has been proposed an air feeding device which sucks and conveys a sheet by utilizing the suction force of air. FIG. 6 shows a typical air-feeding device that has been conventionally proposed. Sheet tray 1 with stacked sheets
A sheet conveying unit 100 is arranged above 01. The sheet conveyance unit 100 includes a sheet suction unit 102, a conveyance belt 103 having a plurality of suction holes 103a, and a suction hole 1
03a and a blower 104 that sucks air through the sheet suction unit 102. In the vicinity of the leading edge of the sheet, a nozzle 1 that ejects air to float the sheet
05, a nozzle 106 for blowing air to the second and subsequent sheets to separate only one sheet is arranged. The nozzles 105 and 106 are connected to a blower 107 and supplied with air.

The device operates as follows.

First, air is ejected from the nozzle 105 by the action of the blower 107 to float several sheets on the sheet tray. Then, the action of the blower 104 causes the uppermost sheet to be attracted to the conveyor belt 103. Next, the conveyor belt is driven to convey the sheet to the downstream side. At this time, air is blown from the nozzle 106 to the sheet front end by the action of the blower 107, and the double-fed sheets are blown back and separated. Then, only one sheet is conveyed to the next conveying roller pair 108. <Prior Art 2> Conventionally, a sheet feeding device in an image forming apparatus such as an electrophotographic copying machine is generally a roller sheet feeding device that conveys sheets stacked on a sheet tray to a downstream side by rotation of a sheet feeding roller. Target. In this conventional roller feeding device, the roller surface is made of an elastic material such as rubber, and its performance is largely due to the friction coefficient of the roller surface.
Therefore, the feeding performance may not be stable due to changes in the roller outer shape due to wear, changes in the roller material over time, changes in the friction coefficient on the roller surface due to paper powder adhesion, etc. It had the drawback of not having it.

In view of the above problems, there has been proposed an air feeding device that sucks and conveys a sheet by utilizing the suction force of air. FIG. 17 shows a typical air feeding device that has been conventionally proposed. A sheet conveying unit 100 is arranged above the sheet tray 101 on which sheets are stacked. The sheet conveyance unit 100 includes a sheet suction unit 102, a conveyance belt 103 having a plurality of suction holes 103a, and a suction hole 1
03a and a blower 104 that sucks air through the sheet suction unit 102. In the vicinity of the leading edge of the sheet, a nozzle 1 that ejects air to float the sheet
05, a nozzle 106 for blowing air to the second and subsequent sheets to separate only one sheet is arranged. The nozzles 105 and 106 are connected to a blower 107 and supplied with air.

The device operates as follows. First,
Air is ejected from the nozzle 105 by the action of the blower 107, and several sheets on the sheet tray are floated. Then, the uppermost sheet is attracted to the conveyor belt 103 by the action of the blower 104. Next, the conveyor belt is driven to convey the sheet to the downstream side. At this time, air is blown from the nozzle 106 to the front end of the sheet by the action of the blower 107,
The sheets that have been double-fed are blown back and separated. Then, only one sheet is conveyed to the next conveying roller pair 108.

What is important in the above-described multi-feed separation system is to blow air between the first sheet to be conveyed and the second sheet to be separated.

As shown in FIG. 18 (a), when air is blown between the first sheet S1 and the second sheet S2, this portion has a positive pressure and is separated into the second sheet. A downward force is generated to assist the. In addition, an upward force is generated on the first sheet to assist the attraction to the conveyor belt. Therefore, the first sheet and the second sheet are naturally separated.

Thus, in the above-mentioned conventional example, the first sheet S1 to be conveyed and the second sheet S2 to be separated.
If there is even a small gap at the tip of the air, air will enter between the sheets and the second sheet can be separated. However, when the leading edges of the first sheet and the second sheet are in close contact with each other due to entanglement of the fibers of the sheet or burrs due to defective cutting of the sheet, as shown in FIG. Air does not enter between the second sheet S1 and the second sheet S2, and the lower side of the second sheet is in a positive pressure state.

In this case, the air is blown up from the lower side of the second sheet, and a force is exerted to help the first sheet and the second sheet adhere to each other. Further, in the case of a particularly thin sheet, the first sheet and the second sheet are adsorbed by the suction force of air from the suction holes of the conveyor belt. As described above, there is a drawback in that double feeding cannot be sufficiently prevented for a sheet whose leading end is in complete contact.

Further, the nozzle 10 is used to prevent double feeding.
If the air jet from 6 is made strong, there is a problem that the air is blown back to the first sheet to be conveyed.

As described above, the conventional paper feeding device cannot realize stable paper feeding with no paper feeding failure and no change in paper feeding performance over time.

Therefore, in view of the above points, the following excellent devices have been proposed. FIG. 19 shows the improved air feeding device.

Reference numeral 1 is a sheet tray on which a plurality of sheets can be stacked.
It is loaded so that it can be struck against. Reference numeral 3 is a sheet conveying unit. Reference numeral 4 denotes a first sheet suction portion, which is composed of a substantially flat bottom surface 5 facing the sheet bundle stacked on the sheet tray 1, an air suction opening 6 opened in the substantially flat bottom surface 5, and a suction chamber 7. ing.

Reference numeral 8 denotes a second sheet suction portion, which is arranged on the downstream side in the sheet conveying direction with respect to the first substantially flat bottom surface 5 and forms a predetermined angle with the first substantially flat bottom surface 5. Second substantially planar bottom surface 9 displaced upward, second substantially planar bottom surface 9
It is composed of an air suction opening 10 and a suction chamber 11. The first sheet suction section 4 and the second sheet suction section 8 are each provided with an air suction blower 12A.
Is connected to the blower 12B. The suction of the blower 12A and the blower 12B can be turned on / off by the valves 13A and 13B, respectively.

A conveyor belt 14 is laid around so as to cover the surfaces of the first sheet suction section 4 and the second sheet suction section 8. The conveyor belt 14 has a plurality of suction holes 14a.
Has been opened. The conveyor belt 14 includes rollers 15 and 1
The sheet is supported by 6, 17, and 18 with a predetermined tension, and is intermittently driven in the direction of arrow A by a driving unit (not shown) to convey the sheet. The roller 15 is arranged at a position where the first substantially flat bottom surface 5 and the second substantially flat bottom surface 9 intersect,
It functions as a displacement fulcrum portion 15a for displacing the sheet so as to be convex downward.

Reference numeral 19 is a nozzle for ejecting air to float the sheet, and 20 is a nozzle for ejecting air to separate only one sheet. The nozzles 19 and 20 are connected to a blower 21 for ejecting air. Nozzles 19 and 2
The ejection of air from 0 can be selectively switched by the valve 22. Reference numeral 23 is a pair of conveying rollers for conveying the conveyed sheet further downstream.

Next, the operation of the above air feeding device will be described.

First, the valve 22 is switched to the position a by a switching means such as a solenoid (not shown), the blower 21 is operated, and air is ejected from the nozzle 19 toward the front end of the sheet. Then, several sheets are blown up and float up. Then, the valve 13A and the valve 13B are respectively switched to the positions c and f by a switching means such as a solenoid (not shown), the blower 12A and the blower 12B are operated, and the air is passed through the suction openings 6 and 10 and the intake hole 14a. Is sucked.

As a result, the uppermost sheet S1 is sucked by the first and second sheet suction portions 4 and 8 and adheres to the conveyor belt 14. Specifically, as shown in FIG. 19, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing portion 4, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing portion 8. At this time, since the suction forces of the first and second sheet suction portions 4 and 8 are set to be sufficiently strong, the sheet bends against the stiffness of the sheet with the displacement fulcrum portion 15a serving as a fulcrum, tip,
The central portion is in close contact with the conveyor belt 14.

That is, the sheet S1 has the substantially flat bottom surfaces 5, 9
Following the above, it becomes a downwardly convex "V" shape with the displacement fulcrum 15a as the fulcrum. At this time, it is assumed that the second sheet S2 is in close contact with the sheet S1. In this case, the sheet S
The vicinity of the central portion of 2 substantially follows the sheet S1. However, since the surface of the second sheet suction portion 8 is covered with the sheet S1, the suction force does not work near the tip of the sheet S2.

Therefore, the sheets become stiffer, the sheet S2 maintains the planar shape without being bent with the displacement fulcrum portion 15a as a fulcrum, the leading ends of the sheets are separated, and a gap e is formed between the sheets. After that, the conveyor belt 14 is driven by a driving unit (not shown), and the sheet S1 is conveyed in the arrow A direction. At the same time, the valve 22 is switched to the position of b, air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2, and the sheet S2 is stably separated as described with reference to FIG. Therefore, only the sheet S1 is conveyed downstream and is passed to the pair of conveying rollers 23. <Prior Art 3> Conventionally, in an image forming apparatus such as an electrophotographic copying machine, depending on the type of the sheet, in particular, the stiffness (thickness) of the sheet, the transfer voltage, the suction force of air feeding, and the retard roller of roller feeding. It is known that various optimum conditions in image formation, such as the retard pressure and the fixing temperature during fixing, change.

Therefore, there is provided a device in which a user or a service person judges the stiffness (thickness) of a sheet by relying on human senses such as visual sense and tactile sense, and manually changes various conditions optimal for image formation. Proposed. <Prior Art 4> Conventionally, a sheet feeding device in an image forming apparatus such as an electrophotographic copying machine is generally a roller sheet feeding device that conveys a sheet stacked on a sheet tray to a downstream side by rotation of a sheet feeding roller. Target. In this conventional roller feeding device, the roller surface is made of an elastic material such as rubber, and its performance is largely due to the friction coefficient of the roller surface.
Therefore, the feeding performance may not be stable due to changes in the roller outer shape due to wear, changes in the roller material over time, changes in the friction coefficient on the roller surface due to paper powder adhesion, etc. It had the drawback of not having it.

In view of the above problems, there has been proposed an air feeding device which sucks and conveys a sheet by utilizing the suction force of air. FIG. 29 shows an example of a conventionally proposed air feeding device. Reference numeral 201 denotes a sheet tray on which a plurality of sheets can be stacked, and the sheets are stacked such that the leading ends of the sheets abut against the sheet alignment guide plate 202. Reference numeral 203 denotes a sheet conveying unit. Reference numeral 204 denotes a first sheet suction portion, which is a substantially flat bottom surface 205 facing the sheet bundle stacked on the sheet tray 201 and a substantially flat bottom surface 20.
5, air suction opening 206, suction chamber 2
It is composed of 07.

Reference numeral 208 denotes a second sheet suction portion, which is a first sheet suction portion.
Of the first substantially planar bottom surface 205, which is disposed on the downstream side in the sheet conveying direction with respect to the substantially planar bottom surface 205 of the first planar surface 205.
Second substantially planar bottom surface 209 displaced above 05, second
Air suction opening 21 formed in the substantially planar bottom surface 209 of the
0, a suction chamber 211. The first sheet suction section 204 and the second sheet suction section 208 are connected to an air suction blower 212. Blower 21
The suction of 2 can be turned on / off by the valve 213.

The conveyor belt 214 covers the surfaces of the first sheet suction section 204 and the second sheet suction section 208.
Have been passed over. The transport belt 214 has a plurality of suction holes 214a. The conveyor belt 214 is
It is supported by rollers 215, 216, 217, and 218 with a predetermined tension, and is driven by a driving means (not shown) so that the arrow A
It is driven intermittently in the direction to convey the sheet. Laura 2
15 is arranged at a position where the first substantially flat bottom surface 205 and the second substantially flat bottom surface 209 intersect, and functions as a displacement fulcrum portion 215a for displacing the sheet so as to be convex downward.

Reference numeral 219 is a nozzle for ejecting air to float the sheet, and 220 is a nozzle for ejecting air to separate only one sheet. Nozzles 219 and 22
0 is connected to a blower 221 for jetting air. The ejection of air from the nozzles 219 and 220 can be selectively switched by a valve 222. A pair of conveying rollers 223 conveys the conveyed sheet further downstream.

Next, the operation will be described. The valve 222 is switched to the position a by a switching means such as a solenoid (not shown), the blower 221 is operated, and air is ejected from the nozzle 219 toward the front end of the sheet. Then, several sheets are blown up and float up. And
The valve 2 by switching means such as a solenoid (not shown)
13 is switched to the position of c, the blower 212 operates, and air is sucked through the suction openings 206 and 210 and the suction hole 214a. Then, the uppermost sheet S1 is sucked by the first and second sheet suction portions 204 and 208,
It comes into close contact with the transport belt 214.

More specifically, as shown in FIG. 29, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing section 204, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing section 208. In this way, the sheet bends against the stiffness of the sheet with the displacement fulcrum portion 215a serving as a fulcrum, and the tip of the sheet,
The central portion is in close contact with the conveyor belt 214. In other words, the sheet S1 has a “<” shape protruding downward with the displacement fulcrum portion 225a as a fulcrum, following the substantially flat bottom surfaces 205 and 209. At this time, it is assumed that the second sheet S2 is in close contact with the sheet S1.

In this case, since the angle θ is previously set to the above-mentioned angle, the second sheet S2 has the displacement fulcrum portion 2
25a is used as a fulcrum to maintain a flat shape without bending, the leading ends of the sheets are separated, and a gap e is formed between the sheets. Then, the conveyor belt 214 is driven by a driving unit (not shown),
The sheet S1 is conveyed in the direction of arrow A. At the same time,
The valve 222 is switched to the position of b, the air is blown from the nozzle 220 into the gap e between the sheet S1 and the sheet S2, and the sheet S2 is stably separated. Therefore, only the sheet S1 is conveyed downstream, and the conveyance roller pair 223
Passed to.

[0032]

[Problems to be Solved by the Invention]

<Problem of the first invention> However, when feeding various types of sheets, when the distance from the uppermost sheet of the sheet bundle to the conveyor belt is set (fixed) to be long, the uppermost sheet and the conveyor belt lifted by the air from the nozzle 105. Because of the long distance between

When a thin (light) paper is fed, the sheet is completely adsorbed to the sheet adsorbing section 102, but when a thick (heavy) paper is replenished, the sheet is adsorbed to the sheet adsorbing section 102 due to insufficient suction force. Cannot be performed and the stability of feeding is impaired.

On the other hand, when the distance from the uppermost sheet of the sheet bundle to the conveyor belt is set short (fixed), the nozzle 105
Since the distance between the uppermost paper floated by the air from and the conveyor belt is short, the result is as follows.

When thick (heavy) paper is fed, the sheet is completely adsorbed to the sheet adsorbing section 102, but when thin (light) paper is fed, the first sheet is completely adsorbed to the sheet adsorbing section 102. However, since the distance is short, the suction force also acts on the second sheet, and even the second sheet may be adsorbed along with the first sheet and double-fed.
As described above, there is a problem that various types of sheets cannot be stably fed with one setting.

It is an object of the present invention to provide a sheet feeding device that reliably separates and conveys a sheet in a sheet feeding device using the suction force of air. <Problem of the Second Invention> However, the air feeding device described above has the following disadvantages.

Consider, for example, the case of conveying a very thick and strong sheet.

In this case, several sheets are floated by the action of air from the nozzle 19, and the uppermost sheet S1 is sucked by the first sheet suction section 4 and the second sheet suction section 8.
At this time, since the first sheet suction portion is closer to the sheet S1, the sheet S1 is first sucked onto the first sheet suction portion 4. Then, the rear portion of the sheet S1 is restrained by the first sheet suction portion 4.

Here, since the sheet S1 has a strong elasticity, it is hard to bend with respect to the displacement fulcrum portion 15a and is difficult to be sucked by the second sheet suction portion 8. Therefore, as shown in FIG. 20, the gap e between the sheets is not sufficiently obtained, and the effect of separating the air by the nozzle 20 is not sufficiently performed, so that the sheet feeding failure, especially the double feeding is likely to occur. .

It is an object of the present invention to provide a sheet feeding device which ensures separation of the leading edge of a sheet. <Problem of the third invention> However, in the above-mentioned conventional example, in order to set the above-mentioned conditions, a user or a serviceman senses the resilience (thickness) of the seat by a human sense such as sight or feel. Since the judgment was made based on the above, there are variations in judgment due to physical condition and emotions, and variations in judgment due to individual differences at that time, and it is possible to reliably set various conditions such as paper feeding and transfer to the optimum state. could not.

It is an object of the present invention to provide a sheet physical property detecting device capable of measuring physical properties of a sheet and setting various conditions such as sheet feeding and image formation in an optimum state based on the measurement result. It is what <Problem of Fourth Invention> However, when feeding various types of paper, if the angle θ is fixed and the paper is conveyed as it is, the suction force of the first sheet suction portion 204 and the second sheet suction portion 208 is set weak (fixed). When the sheet with weak stiffness is fed, the sheet is completely adsorbed on the conveyor belt 214 and the separation condition is good. As a result, the first sheet S1 does not project downward, which hinders the stability of separation (FIG. 30).

On the other hand, when the suction force of the first sheet suction portion 204 and the second sheet suction portion 208 is set strongly (fixed), if a sheet having a strong stiffness is fed, only the first sheet of the conveyor belt 214 is completely fed. It is adsorbed on and is well separated. However, when a weak sheet is fed, the first sheet is completely adsorbed to the conveyor belt 214, but the second sheet S2
Also, the second sheet may be sucked, and the second sheet may be convex downward with the displacement fulcrum portion 209a as a fulcrum along with the first sheet (FIG. 31) and may be double-fed. . As described above, there is a problem that various types of paper cannot be stably fed with one setting.

According to the present invention, when a sheet is adsorbed by the first and second sheet adsorbing portions, the angle of the leading end portion is set to an optimum angle according to the type of the sheet, and stable sheet feeding is enabled. The purpose is to provide a device.

[0044]

[Means for Solving the Problems]

<Means of First Invention> The present invention is a plurality of sheets (S).
A sheet tray (1) for stacking sheets, a sheet suction section (4) facing the stacked sheet bundle (S) and having a plurality of air suction openings (6) on a substantially flat bottom surface (5), At least one air suction unit (12) for sucking the sheet (S) by sucking air through the air suction opening (6) of the sheet suction unit (4), and the sheet suction unit (4) Detecting means (30, 31) for detecting the stiffness of the sheet (S), which is provided in the vicinity of
And the sheet tray (1) and the sheet suction section (4)
Fluctuating means (29) for varying the distance between the sheet and the sheet (S) according to the stiffness of the sheet (S), control means (37) for controlling the varying means (29), and feeding means (1) for feeding the sheet.
4) and are included.

Further, according to the present invention, the sheet tray (1) for stacking a plurality of sheets (S) and the plurality of air suctions on the substantially flat bottom surface (5) facing the stacked sheet bundle (S). A first sheet suction portion (4) having an opening (6), and a plurality of airs arranged on the substantially flat bottom surface (9) arranged downstream of the first sheet suction portion (4) in the sheet conveying direction. A second sheet suction portion (8) having a suction opening (10), a second sheet suction portion (8) disposed downstream of the first sheet suction portion (4) and upstream of the second sheet suction portion (8), Displacement fulcrum part (15a) for displacing the sheet (S) sucked by the first and second sheet suction parts (4, 8) so as to be convex downward.
And at least one air suction means (12) for sucking a sheet by sucking air through the air suction openings (6, 10) of the first and second sheet suction portions (4, 8). A detection means (30, 31) provided near the air suction means (12) for detecting the stiffness of the sheet (S), the sheet tray (1) and the first and second sheet suctions. Fluctuating means (29) for varying the distance to the section (4, 8) according to the stiffness of the sheet (S),
It is characterized by having a control means (39) for controlling the changing means and a feeding means (14) for feeding the sheet. <Means of Second Invention> The present invention is a plurality of sheets (S).
A sheet tray (1) on which sheets are stacked, and a first sheet suction section (4) facing the stacked sheet bundle (S) and having a plurality of air suction openings (6) on a substantially flat bottom surface (5). )
And a second air suction opening (10) arranged downstream of the first sheet suction portion (4) in the sheet conveying direction and displaced upward with respect to the substantially flat bottom surface (5). Of the first sheet suction section (8) and the first sheet suction section (4) disposed downstream of the first sheet suction section (4) and in the vicinity of the upstream side of the second sheet suction section (8). Displacement fulcrum (15a) for displacing the sheet (S) attracted to the parts (4, 8) so as to be convex downward, and the tip of the sheet bundle (S) stored in the sheet tray (1). At least one air blowing means (19) for blowing air to the vicinity and at least one of the first and second sheet suction portions (4, 8) and the displacement fulcrum portion (15a) are wound to cover a plurality of surfaces. A conveyor belt (14) having suction holes (14a) Conveying suction holes (14a) and said first belt (14), a second sheet suction section (4,
The sheet (S) is transferred to the conveyor belt (14) by sucking air through the air suction openings (6, 10) of 8).
At least one air suction means (1
2A, 13B) and a control means (47) for independently sucking air from the first and second sheet suction portions (4, 8). At the time of feeding (S), air is first sucked from the second sheet suction section (8), and then the first sheet is sucked.
The control means (47) controls the air suction from the sheet suction section (4).

A sheet tray (1) for stacking a plurality of sheets (S) and a plurality of air suction openings () on the substantially flat bottom face (5) facing the stacked sheet bundle (S). A first sheet adsorbing part (4) having 6);
Of the second sheet suction portion (4) arranged downstream of the sheet suction portion (4) in the sheet conveying direction and having a plurality of air suction openings (10) displaced downward with respect to the substantially flat bottom surface (5). 8) and downstream of the first sheet suction section (4) and in the vicinity of the upstream side of the second sheet suction section (8), and the first and second sheet suction sections (4, 8). ), A displacement fulcrum (15a) for displacing the sheet (S) adsorbed by the sheet (S) so as to be convex upward, and the sheet tray (1).
At least one air blowing means (19) for blowing air near the tip of the sheet bundle (S) stored in
A conveyor belt (1) wound around at least the first and second sheet suction portions (4, 8) and the displacement fulcrum portion (15a) and having a plurality of suction holes (14a) on the surface.
4) and the sheet by sucking air through the suction holes (14a) of the conveyor belt (14) and the air suction openings (6, 10) of the first and second sheet suction portions (4, 8). At least one air suction means (12A, 13B) for adsorbing (4) onto the conveyor belt (14);
A sheet feeding device comprising: a control unit (47) for independently sucking air from the first and second sheet suction units (4, 8), and feeding the sheet (S). Occasionally, the control means (47) controls so that air is sucked from the second sheet suction portion (8) first and then air is sucked from the first sheet suction portion (4). Is characterized by. <Means of Third Invention> The present invention is directed to a first sheet suction portion (which faces the sheet (S) to be measured and has at least one air suction opening (6) in the substantially flat bottom surface (5). 4), a second sheet suction portion (8) facing the sheet (S) and having at least one air suction opening (10) on the substantially flat bottom surface (9), and the first and second sheets. Is provided near at least one air suction means (12) for sucking air through the air suction openings (6, 10) of the sheet suction section (4, 8), and the first sheet suction section (4). And a first detecting means (50) for detecting that the sheet (S) is adsorbed by the first sheet adsorbing section (4), and the vicinity of the second sheet adsorbing section (4). And that the sheet (S) is adsorbed by the second sheet adsorbing part (8). After the sheet (S) is adsorbed by the second detecting means (60) for detecting and the first sheet adsorbing section (4), the sheet (S) is detected by the second sheet adsorbing section (8). And a measuring means (57a) for detecting the time until the completion.

The distance from the measured sheet (S) to the first detecting means (4) is different from the distance from the sheet (S) to the second detecting means (8). It is characterized by

Further, it is characterized in that it has display means (56) for displaying the signal measured by the measuring means (57a). <Means of Fourth Invention> The present invention relates to a plurality of sheets (S).
A sheet tray (1) on which sheets are stacked, and a first sheet suction section (4) facing the stacked sheet bundle (S) and having a plurality of air suction openings (6) on a substantially flat bottom surface (5). And a second sheet suction portion (8) arranged on the downstream side in the sheet conveying direction with respect to the first sheet suction portion (4) and having a plurality of air suction openings (10) on the substantially flat bottom surface (9). ) Is disposed downstream of the first sheet suction section (4) and upstream of the second sheet suction section (8), and is sucked by the first and second sheet suction sections (4, 8). Fulcrum portion (15a) for displacing the formed sheet (S) so as to be convex downward
And at least one air suction means for sucking the sheet (S) by sucking air through the air suction openings (6, 10) of the first and second sheet suction portions (4, 8). (12) and the first sheet suction section (4)
And a protrusion (3) that is provided in the vicinity of and is movable by being pushed by the adsorbed sheet (S).
0) and detection for detecting the amount of movement of the protrusion (30) that is pushed and moved by the sheet (S) when the sheet (S) is adsorbed by the first sheet adsorbing section (4). Means (31), said first sheet suction section (4) and second
Angle varying means (7) for varying the angle (θ) formed by the sheet suction portion (8) with the displacement fulcrum portion (15a) as the apex.
5, 76, 77, 79) and a feeding means (14) for feeding the sheet.

[0049]

[Action]

<Operation of the First Invention> The first sheet (S ₁ ) of the sheet bundle (S) on the sheet tray ( ₁ ) is the air suction means (1
Air is sucked by the sheet suction means (4) by 2) and is sucked by the feeding means (14) by the suction force of the sheet suction means (4), and is fed by the rotation of the feeding means (14).

When the sheet (S ₁ ) is adsorbed by the sheet adsorbing means (4), a detecting means (3) provided near the sheet adsorbing means (4) for detecting the stiffness of the sheet.
0, 31) detects the stiffness of the sheet (S ₁ ), and the changing means (29) moves the sheet tray (1) according to the detection result to move the sheet tray (1) and the sheet suction means (4). Vary the distance to and.

As a result, even when various types of sheets (S) are fed, the sheets (S) can be stably fed by the same suction force. <Operation of the Second Invention> The sheets (S) stacked on the sheet tray (S) are blown up by (19), and the first detection means (8) that starts sucking air first The leading end of the first sheet (S) is attracted to the conveyor belt 14. This sheet (S) is attracted to the conveyor belt 14 by the attraction force of the first detecting means (4) to be operated next, and the displacement fulcrum portion 15a causes the first and second sheet attraction portions (4, 8). ) Is bent in a convex shape. As a result, the leading edge of the first sheet can be reliably separated from the second sheet, and a stable sheet feeding device that does not cause feeding defects such as double feeding and changes in sheet feeding performance over time is realized. can do. <Operation of Third Invention> When the air suction means (12) is operated, suction force acts on the first and second sheet suction portions (4, 8) to suck the sheet (S). In the suction of the sheet (S), first, the sheet (S) is sucked by the first sheet suction unit (S) and the suction is detected by the first detection unit (50), and the second sheet is slightly delayed. The suction is performed by the suction unit (8) and the second detection unit (60) detects the suction.

The time from the detection of the sheet (S) by the first detection means (50) until the sheet (S) is adsorbed by the second sheet adsorption section (8) is measured by the measurement means (5).
7a), whereby the physical properties of the sheet (S) such as stiffness and thickness can be detected. For example, the optimum conditions for sheet feeding image formation can be set for the sheet (S) feeding device or the image forming apparatus. Can be set. <Operation of Fourth Invention> The sheet (S) on the sheet tray (1) is sucked by the suction force of the first and second sheet suction portions (4, 8), and an angle is generated at the displacement fulcrum portion (15a). (Θ) and bent in a convex shape. The detection protrusion (30) is moved by the sheet (S) adsorbed by the first and second sheet adsorption units (4, 8), and the movement amount is detected by the detection means (3).
The strength of the sheet (S) is detected by the detection in 1).

Based on the above detection result, the angle (θ) formed by the second sheet suction portion (8) with respect to the first sheet suction portion (4) determines the angle varying means (75, 76, 77, 79).
Fluctuated by. As a result, the tip of the sheet (S) can be separated by bending the sheet (S) at an angle (θ) optimal for the stiffness of the sheet (S), and the same suction force can be applied to various sheets (S). With this, stable paper feeding can be performed.

The reference numerals in parentheses are shown for reference to the drawings and do not limit the structure of the present invention.

[0055]

【Example】

<Embodiment 1 of the first invention> An embodiment according to the first invention will be described below with reference to the drawings.

FIG. 1 shows an air feeding device of the electrophotographic copying machine.

In FIG. 1, reference numeral 1 denotes a sheet tray on which a plurality of sheets S can be stacked, and the sheets are stacked so that their leading ends abut against the sheet alignment guide plate 2. Reference numeral 3 is a sheet conveying unit. Reference numeral 4 denotes a first sheet suction portion, which is composed of a substantially flat bottom surface 5 facing the sheet bundle described in the sheet tray 1, an air suction opening 6 opened in the substantially flat bottom surface 5, and a suction chamber 7. ing.

Reference numeral 8 denotes a second sheet suction portion, which is arranged on the downstream side in the sheet conveying direction with respect to the first substantially flat bottom surface 5 and forms a predetermined angle θ with the first substantially flat bottom surface 5. Second substantially flat bottom surface 9 displaced above the air, air suction opening 10 formed in the second substantially flat bottom surface 9, and suction chamber 11
It is composed by.

The first sheet suction section 4 and the second sheet suction section 8 are connected to an air suction blower 12. The suction of the blower 12 can be turned on / off by the valve 13. The conveyor belt 14 is stretched over the surfaces of the first sheet suction unit 4 and the second sheet suction unit 8 so as to cover the surfaces thereof. The conveyor belt 14 has a plurality of suction holes 14
a is opened. The conveyor belt (feeding means) 14 is
The sheet is supported by rollers 15, 16, 17, and 18 with a predetermined tension, and is intermittently driven in the direction of arrow A by a driving unit (not shown) to convey the sheet. Roller 15 is first
Is disposed at a position where the substantially flat bottom surface 5 and the second substantially flat bottom surface 9 intersect, and functions as a displacement fulcrum portion 15a for displacing the sheet so as to be convex downward.

Reference numeral 19 is a nozzle for ejecting air to float the sheet, and 20 is a nozzle for ejecting air to separate only one sheet. The nozzles 19 and 20 are connected to a blower 21 for ejecting air. Nozzles 19 and 2
Air ejection from 0 can be selectively switched by the valve 22. Reference numeral 23 is a pair of conveying rollers for conveying the conveyed sheet further downstream.

Next, a mechanism for making the sheet tray 1 movable according to the stiffness of the sheet will be described.

Reference numeral 27 denotes a rack attached to the sheet tray 1, which is engaged with a pinion gear 28 and is movable in the direction of arrow B in the drawing. Reference numeral 29 is a motor (changing means) for rotating the pinion gear 29. These are for setting the sheet tray 1 to a height satisfying the following two conditions according to the sheets to be sent. First, only the uppermost sheet S1 is the second sheet suction portion 8
The second is that the second sheet S2 is not adsorbed at the same time as the first sheet S1.

A means for detecting the stiffness of the sheet will be described. Reference numeral 30 denotes a detection protrusion that is movable in the direction of arrow C in the figure. Reference numeral 31 is a font sensor that detects the position of the detection protrusion 30.

Next, the operation of the above-mentioned air feeding device when the stiffness of the sheet is strong will be described with reference to FIG. First of all, the sheet tray 1 is located near the conveyor belt 14 (FIG. 3). This is the home position. The valve 22 is switched to the position a by a switching means such as a solenoid (not shown), the blower 21 is operated, and the nozzle 19
From the air toward the tip of the seat. Then, several sheets are blown up and float up. Then, the valve 13 is switched to the position c by a switching means such as a solenoid (not shown), the blower 12 is operated, and air is sucked through the suction openings 6 and 10 and the intake hole 14a.

As a result, the uppermost sheet S1 is sucked by the first and second sheet suction portions 4 and 8 and adheres to the conveyor belt 14. Specifically, as shown in FIG. 1, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing portion 4, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing portion 8. Although the downward force is applied to the detection protrusions 30 by its own weight, the rear end of the sheet does not move much lower than the substantially flat bottom surface 5 because the sheet is strong, and the detection protrusions 60 are pushed by the sheet and move upward. The photo sensor 31 is turned on. The control means 37 receiving the signal from the photo sensor 31 determines the thickness (weight) of the sheet.

Generally, if the sheet is strong, it is a heavy (thick) sheet, and if it is weak, it is a light (thin) sheet. In this case, the sheet is heavy and is less likely to be adsorbed by the transport belt 14, so the position of the sheet tray 1 may remain close to the transport belt 14. Therefore, the paper is fed as follows. The first sheet S1 is in close contact with the first sheet suction section 4 and the second sheet suction section 8. That is, the sheet S1 follows the substantially flat bottom surfaces 5 and 9 and has a downwardly convex "C" shape with the displacement fulcrum portion 15a as the fulcrum, and the second sheet S2 has the displacement fulcrum portion 15a as the fulcrum. Maintains a flat shape without bending as a fulcrum,
The leading ends of the sheets are separated, and a gap e is formed between the sheets.

After that, the conveying belt 14 is driven by the driving means (not shown), and the sheet S1 is conveyed in the direction of arrow A. At the same time, the valve 22 is switched to the position of b, air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2, and the sheet S2 is stably separated. Therefore, only the sheet S1 is conveyed downstream and is passed to the pair of conveying rollers 23. After that, an image is formed by a known image forming apparatus.

FIG. 2 shows the setting when the stiffness of the sheet is weak. Since the detection protrusion 30 is applied with a downward force due to its own weight, when the paper is adsorbed, the rear end of the paper has a substantially flat bottom surface 5.
It goes down against. That is, the detection protrusion 30 is lowered and the photo sensor 31 is turned off. The control means 37 receiving the signal from the photo sensor 31 determines the thickness (weight) of the sheet. In this case, since the sheet is a light sheet, when the position of the sheet tray 1 is high, the distance α between the first sheet S1 and the first sheet suction portion 4 is small, so the suction force is strong and the first sheet S1 is Since the second sheet S2 is easily adsorbed at the same time when adsorbed,
The following operation is performed to lower the position of the sheet tray 1.

The control means 37 operates the motor 29 to lower the rack 27 via the pinion gear 28, thereby moving the sheet tray 1 downward so as to satisfy the above-mentioned conditions.
(FIG. 4) As a result, the distance β between the first sheet S1 and the first sheet suction portion 4 increases, and only the sheet S1 bends against the stiffness of the sheet with the displacement fulcrum portion 15a as a fulcrum, The leading edge and the central portion of the sheet come into close contact with the conveyor belt 14. The subsequent steps are the same as those described for the case of a strong sheet. After that, when the sheet feeding operation is completed, the sheet tray 1 is moved so that the position of the uppermost sheet of the sheet comes to the home position described above.

In the present embodiment, the measurement of the movement amount of the detection protrusion 30 is described in only two steps, but the present invention is not limited to this, and the measurement is performed in multiple steps using a slide volume or the like. It is easily conceivable that stable feeding of various kinds of sheets can be performed by performing or stepless measurement. Further, in the present embodiment, the detection protrusion is about to fall downward due to its own weight, but the present invention is not limited to this, and any device that generates a force in the direction opposite to the suction direction, such as using a spring, is effective. It's easy to think of.

Further, in this embodiment, the case where the stiffness of the sheet is detected on the trailing edge side of the sheet is shown. However, the present invention is not limited to this, and the same applies when the leading edge side or the lateral side of the sheet is detected. It goes without saying that various effects can be obtained.

Further, in the present embodiment, the height of the sheet tray 1 is changed according to the stiffness of the sheet, but the height of the first sheet suction portion 4 may be changed, and the height of the sheet tray 1 and the first tray may be changed. It is easily conceivable that it is effective if it changes the distance to the sheet suction unit 4.

In the present embodiment, the sheet transporting unit having the first and second sheet suction units is described, but the present invention is not limited to this, and one sheet suction unit (FIG. 5) may be provided. It is easy to think that it is effective.

In this embodiment, the sheet tray 1 returns to the home position close to the conveyor belt after the feeding is completed, but it is clear that it may be just before the feeding is started. <Embodiment 1 of the second invention> Hereinafter, the present invention will be described in detail based on embodiments.

FIG. 7 best represents the present invention. Since the configuration itself is exactly the same as the above-mentioned conventional example, the description is omitted.

Next, the operation of the present invention will be described (the operation is based on the timing chart of FIG. 9 and the block chart of FIG. 10). First, the valve 22 is switched to the position a by a switching means such as a solenoid (not shown), the blower 21 is operated, and air is ejected from the nozzle 19 toward the front end of the sheet. Then, several sheets are blown up and float up. And first, blower 12A and blower 12
B operates. Next, the valve 13B is switched to the position f by switching means such as a solenoid (not shown), and air is sucked through the suction opening 10 and the intake hole 14a.

Then, the uppermost sheet S1 is sucked by the second sheet suction portion 8 and adheres to the conveyor belt 14. At this time, only the second sheet suction portion 8 is operating, and the rear portion of the sheet S1 is not restrained. Therefore, only the leading end of the sheet S1 is surely moved to the second sheet suction portion 8.
Is adsorbed on. Therefore, it becomes easy to separate and convey only the sheet S1. Then, after that, the valve 13A is switched to the position c by a switching means such as a solenoid (not shown), and the air is sucked through the suction opening 6 and the intake hole 14a. Then, the sheet bends around the displacement fulcrum portion 15a as a fulcrum against the stiffness of the sheet,
The central portion is in close contact with the conveyor belt 14.

More specifically, as shown in FIG. 8, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing portion 4, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing portion 8. That is, the sheet S1 follows the substantially flat bottom surfaces 5 and 9 and has a downward V-shaped shape with the displacement fulcrum portion 15a as a fulcrum. At this time, it is assumed that the second sheet S2 is in close contact with the sheet S1. In this case, the vicinity of the central portion of the sheet S2 substantially conforms to the sheet S1. However, since the surface of the second sheet suction portion 8 is covered with the sheet S1, the suction force does not work near the tip of the sheet S2.

Therefore, the sheet becomes stiff, the sheet S2 maintains a flat shape without being bent with the displacement fulcrum portion 15a as a fulcrum, the leading ends of the sheets are separated, and a gap e is formed between the sheets (FIG. 8). . After that, the conveyor belt 14 is driven by a driving unit (not shown), and the sheet S1 is conveyed in the arrow A direction. At the same time, the valve 22 is switched to the position of b, air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2, and the sheet S2 is stably separated as described with reference to FIG. Therefore, only the sheet S1 is conveyed downstream and is passed to the pair of conveying rollers 23.

Then, after a predetermined time (the sheet is paired with the roller pair 2
(After being sandwiched by 3), the valves 13A and 13B are in the d and g positions, respectively, and the blowers 12A and 12B are also stopped. After a predetermined time (after the sheet passes through the roller pair 23), the conveyor belt 14 and the blower 21 are stopped, the valve 22 is also set to the position a, and the sheet feeding operation is completed.

As described above, if the sheet suction portion on the sheet front end side is sucked first, a thick and strong sheet can be surely sucked to the first and second sheet suction portions, and the sheets can be reliably separated. Can be transported. Second Embodiment of Second Invention Next, another embodiment will be described.

The same parts as those in the first embodiment are designated by the same symbols and their explanations are omitted.

FIG. 11 shows a second embodiment of the present invention.

40A is a second sheet suction portion. Second
The sheet suction unit 40A is arranged downstream of the first sheet suction unit 4 in the sheet conveying direction. Secondly, the sheet suction section 40A has a hollow suction roller 41A having a plurality of suction holes 41a on its surface, a suction chamber section 42, and a suction roller 4.
A cover 43 that roughly covers the portion other than the portion for sucking the 1A sheet
Consists of Reference numeral 44 denotes a displacement fulcrum portion that bends the sheet S downward in a convex shape. Since the surface of the suction roller 41A that attracts the sheet has a curvature, it is substantially the first surface.
Is located above the sheet suction portion (substantially planar bottom surface 5).

The first sheet suction section 4 and the second sheet suction section 40A are connected to the blower 12. The conveyor belt 14 is stretched over the surfaces of the first sheet suction unit 4 and the second sheet suction unit 40A so as to cover the surfaces thereof. The conveyor belt 14 is supported by rollers 40A, 16, 17, and 18 with a predetermined tension, and is intermittently driven in the direction of arrow A by a driving unit (not shown) to convey the sheet.

Also in this embodiment, the same effect as in the first embodiment can be obtained by sucking the air from the second sheet suction portion 40A before the first sheet suction portion 4. . <Third Embodiment of Second Invention> Next, a third embodiment will be described with reference to FIG. This embodiment is an application of the above-described embodiment to lower separation sheet feeding (a method of separating stacked sheets one by one from the bottom sheet and feeding the sheets).

The configuration is such that the top and bottom of the first embodiment are turned upside down, and sheets are stacked on the first sheet suction portion and its vicinity, and function as the sheet tray 1. Further, the sheet blowing nozzle 19 is eliminated. The operation of the other parts is exactly the same as that of the first embodiment, and since the top and bottom are simply reversed, the description is omitted.

Next, the operation of this embodiment will be described (the operation is based on the timing chart of FIG. 15).

First, the blower 12A and the blower 12B are operated. Next, the valve 13B is switched to the position f by switching means such as a solenoid (not shown), and air is sucked through the suction opening 10 and the intake hole 14a. Then, the lowermost sheet S1 is adsorbed by the second sheet adsorbing portion 8 and adheres to the conveyor belt 14. At this time,
Since only the second sheet suction portion 8 is operating and the portion behind the sheet S1 is not restrained, the sheet S1
Only the tip of the sheet is surely adsorbed to the second sheet adsorbing portion 8.

Therefore, it becomes easy to separate and convey only the sheet S1. Then, after that, the valve 13A is switched to the position c by a switching means such as a solenoid (not shown), and the air is sucked through the suction opening 6 and the intake hole 14a. Then, the sheet bends around the displacement fulcrum portion 15a as a fulcrum against the stiffness of the sheet, and both the leading end and the central portion of the sheet come into close contact with the transport belt 14. For details, see FIG.
As shown in FIG. 5, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing portion 4, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing portion 8.

That is, the sheet S1 has a substantially flat bottom surface 5,
In accordance with No. 9, it becomes a downward convex V shape with the displacement fulcrum portion 15a as a fulcrum. At this time, if the second sheet S
2 and the sheet S2 are in close contact with the sheet S1. In this case, the vicinity of the central portion of the sheet S2 is substantially aligned with the sheet S1. However, since the surface of the second sheet suction portion 8 is covered with the sheet S1, the suction force does not work near the tip of the sheet S2. Therefore, the sheet becomes stiff, the sheet S2 maintains the planar shape without being bent with the displacement fulcrum portion 15a as a fulcrum, the sheet ends are separated, and a gap e is formed between the sheets (FIG. 13).

After that, the conveying belt 14 is driven by the driving means (not shown), and the sheet S1 is conveyed in the direction of arrow A. At the same time, the valve 22 is switched to the position b, and air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2 to blow up the second and subsequent sheets (FIG. 14).

As a result, the sheet S2 is stably separated as described with reference to FIG. Therefore, only the sheet S1 is conveyed downstream and is passed to the pair of conveying rollers 23. Then, after a predetermined time (the sheet is paired with the roller pair 23
Valve 13A, 13B respectively d, g
And the blowers 12A and 12B also stop. At the same time, the conveyor belt 14 also stops. After a predetermined time (after the sheet passes through the roller pair 23), the blower 21
Is stopped, the valve 22 is also set to the position a, and the sheet feeding operation is completed.

As described above, if the sheet suction section on the sheet front end side is traded first, even a thick and strong sheet can be surely adsorbed to the first and second sheet adsorbing sections, and the sheets can be reliably separated. Can be transported. <Embodiment 4 of the Second Invention> FIG. 16 shows a fourth embodiment of the present invention. The configuration itself is such that the second sheet suction portion of the third embodiment is configured by the suction roller shown in the second embodiment, and the operation and the like are exactly the same, so description thereof will be omitted. <Embodiment 1 of the third invention> Hereinafter, the present invention will be described in detail based on embodiments.

FIG. 21 shows an air feeding device equipped with the sheet physical property detecting device of the present invention.

Reference numeral 1 is a sheet tray on which a plurality of sheets can be stacked, and the leading edge of the sheet is a sheet alignment guide plate 2
It is loaded so that it can be struck against. Reference numeral 3 is a sheet conveying unit. Reference numeral 4 denotes a first sheet suction portion, which is composed of a substantially flat bottom surface 5 facing the sheet bundle stacked on the sheet tray 1, an air suction opening 6 opened in the substantially flat bottom surface 5, and a suction chamber 7. ing. Reference numeral 8 denotes a second sheet suction portion, which is disposed on the downstream side in the sheet conveying direction with respect to the first substantially flat bottom surface 5 and forms a predetermined angle θ above the first substantially flat bottom surface 5. It comprises a displaced second substantially flat bottom surface 9, an air suction opening 10 opened in the second substantially flat bottom surface 9, and a suction chamber 11.

The first sheet suction section 4 and the second sheet suction section 8 are connected to a blower 12 for sucking air. The suction of the blower 12 can be turned on / off by the valve 13. The conveyor belt 14 is stretched over the surfaces of the first sheet suction unit 4 and the second sheet suction unit 8 so as to cover the surfaces thereof. The conveyor belt 14 has a plurality of suction holes 14
a is opened. The conveyor belt 14 includes rollers 15,
It is supported by 16, 17, 18 with a predetermined tension,
The sheet is conveyed by being intermittently driven in the direction of arrow A by the driving unit 58. The roller 15 is arranged at a position where the first substantially flat bottom surface 5 and the second substantially flat bottom surface 9 intersect, and the displacement fulcrum 5 for displacing the sheet so as to be convex downward.
functions as a.

Reference numeral 19 is a nozzle for ejecting air to float the sheet, and 20 is a nozzle for ejecting air to separate only one sheet. The nozzles 19 and 20 are connected to a blower 21 for ejecting air. Nozzles 19 and 2
The ejection of air from 0 can be selectively switched by the valve 22. A pair of transport rollers 23 transports the transported sheet further downstream, and is driven by the drive means 59.

Reference numeral 50 denotes a first detecting means, which is arranged near the first sheet suction portion 4. Reference numeral 51 is a detection arm, which is rotatable around a fulcrum 52. The detection arm 51 is in the position of f protruding from the first suction portion when the sheet is not sucked. The detection arm 51 is
When the sheet is adsorbed, it is pushed by the sheet and pivots around the fulcrum 52 to the position of g. At this time, the photo sensor 5
3 determines that the sheet is adsorbed.

Reference numeral 60 denotes a second detecting means, which is arranged near the second sheet suction portion 8. A detection arm 61 is rotatable about a fulcrum 62. The detection arm 61 is located at a position h protruding from the second suction portion when the sheet is not sucked. The detection arm 61 is
When the sheet is adsorbed, it is pushed by the sheet and pivots about the fulcrum 62 to the position of i.
3 determines that the sheet is adsorbed.

Next, the operation of the above embodiment will be described with reference to the timing charts of FIGS. 21, 22, 23, and 24 and the block chart of FIG.

First, the detection start button of the operation unit (not shown) is pressed. Then, the blower 21 is operated, the valve 22 is switched to the position a by a switching means such as a solenoid (not shown), and air is ejected from the nozzle 19 toward the front end of the sheet. Then, several sheets are blown up and float up. Then, the blower 12 operates, the valve 13 is switched to the position c by a switching means such as a solenoid (not shown), and the suction openings 6 and 10 and the intake hole 14 are provided.
Air is sucked through a.

As a result, since the first sheet suction portion is closer to the sheet than the second sheet suction portion 8, the uppermost sheet S1 is first sucked by the first sheet suction portion 4,
It comes into close contact with the conveyor belt 14. Specifically, as shown in FIG. 22, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing section 4. Then, as described above, the detection arm 51 is pushed by the sheet to the position of g, and is detected by the photo sensor 53, and the first detection unit 50 detects that the sheet is adsorbed.

Next, after a little delay, the vicinity of the leading edge of the sheet is adsorbed by the second sheet adsorbing portion 8 (FIG. 23). At this time, since the suction force of the first and second sheet suction portions is set to be sufficiently strong, the sheet bends against the stiffness of the sheet with the displacement fulcrum portion 15a as a fulcrum, and the leading end portion of the sheet is Second
Adhere to the sheet suction part of. That is, the sheet S1 follows the substantially flat bottom surfaces 5 and 9 and has a downward V-shaped shape with the displacement fulcrum portion 15a as a fulcrum. Then, as described above, the detection arm 61 is pushed by the sheet to the position of i and is detected by the photo sensor 63, and the second detection unit 6 is detected.
0 detects that the sheet is adsorbed.

As described above, there is a time lag from the time when the sheet is sucked by the first sheet suction portion 4 until the time when it is sucked by the second sheet suction portion 8. This time lag differs depending on the type (physical properties) of the sheet. For example, if the sheet is weak (thin), the displacement fulcrum portion 15a is weak.
Since it bends immediately and is immediately adsorbed by the second sheet adsorbing portion 8, the time lag is small.

On the other hand, since a strong (thick) sheet is strong, it is hard to bend at the displacement fulcrum 5a, and is gradually adsorbed to the second sheet adsorbing portion 8, resulting in a large time lag. By measuring this time with a measuring means (not shown), the type of the sheet (physical properties), particularly the strength of the sheet (thickness of the sheet) can be determined. The strength of the body is displayed on a display device (not shown). Depending on the display,
The various conditions that the user or service person is most suitable for the seat,
For example, the transfer current, the suction force of air feeding, the fixing temperature, etc. can be set.

Thereafter, the blower 12 is stopped and the valve 13
Becomes the position of d, the blower 21 stops, the valve 22 becomes the position of b, and the sheet returns onto the sheet tray 1. <Embodiment 2 of the third invention> In the above-mentioned embodiment, the sheet physical property detecting device has been described, but it can be combined with the sheet feeding device of the image forming apparatus.

Regarding the combined apparatus, FIG.
This will be described with reference to FIGS. 22, 23, a timing chart FIG. 25, and a block chart FIG. The configuration is as described above.

The operation of this apparatus will be described.

The sheets are first and second sheet suction devices 4,
Since it has been adsorbed on the sheet 8, the physical properties of the sheet are detected and displayed, and the optimum conditions are set, the description is omitted because it has been described above.

Then, the copy start button of the operation unit (not shown) is pressed. Then, the sheet S1 is adsorbed by the first and second sheet adsorption components 4 and 8 in exactly the same manner as described above. At this time, the second sheet S2 is the sheet S1
I was in close contact with.

In this case, the vicinity of the central portion of the second sheet S2 substantially conforms to the sheet S1. However, since the surface of the second sheet suction portion 8 is covered with the sheet S1, the suction force does not work near the tip of the sheet S2.
Therefore, the sheet becomes stiff, the sheet S2 maintains the planar shape without being bent with the displacement fulcrum 15a as the fulcrum, the sheet ends are separated, and a gap e is formed between the sheets.

Then, the conveyor belt 1 is driven by the driving means 58.
4 is driven, and the sheet S1 is conveyed in the arrow A direction.
At the same time, the valve 22 is switched to the position of b, air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2, and the entire area of the sheet S2 is stably separated from the sheet S1.

Therefore, only the sheet S1 is conveyed downstream and delivered to the pair of conveying rollers 23. Then, after a predetermined time (after the sheet is nipped by the pair of conveying rollers 23), the blower 12 is stopped and the valve 13 is at the position d. Then, after a further predetermined time (after the sheet has passed through the pair of transport rollers 23), the blower 21 stops, the transport belt 14 also stops, and the transport of the sheet is completed. <Embodiment 1 of Fourth Invention> The present invention will be described in detail below based on embodiments.

FIG. 27 shows an air feeding device of an electrophotographic copying machine embodying the present invention.

Reference numeral 1 denotes a sheet tray on which a plurality of sheets can be stacked, and the leading edge of the sheet is a sheet alignment guide plate 2
It is loaded so that it can be struck against. Reference numeral 3 is a sheet conveying unit. Reference numeral 4 denotes a first sheet suction portion, which is composed of a substantially flat bottom surface 5 facing the sheet bundle stacked on the sheet tray 1, an air suction opening 6 opened in the substantially flat bottom surface 5, and a suction chamber 7. ing. Reference numeral 8 denotes a second sheet suction portion, which is disposed on the downstream side in the sheet conveying direction with respect to the first substantially flat bottom surface 5 and forms a predetermined angle θ above the first substantially flat bottom surface 5. It comprises a displaced second substantially flat bottom surface 9, an air suction opening 10 opened in the second substantially flat bottom surface 9, and a suction chamber 11.

The first sheet suction section 4 and the second sheet suction section 8 are connected to a blower 12 for sucking air. 7
Reference numeral 9b is a flexible duct that can expand and contract in response to the movement of the second sheet suction portion. The suction of the blower 12 can be turned on / off by the valve 13. The conveyor belt 14 is stretched over the surfaces of the first sheet suction unit 4 and the second sheet suction unit 8 so as to cover the surfaces thereof. The transport belt 14 has a plurality of suction holes 14a. The conveyor belt 14 is supported by rollers 15, 16, 17, and 18 with a predetermined tension, and is intermittently driven in the direction of arrow A by a driving unit (not shown) to convey the sheet.
The roller 15 is arranged at a position where the first substantially flat bottom surface 5 and the second substantially flat bottom surface 9 intersect, and functions as a displacement fulcrum portion 15a for displacing the sheet so as to be convex downward.

The roller 17 uses the spring 74 to convey the belt 1.
It also functions as a tensioner for 4. Reference numeral 19 is a nozzle that ejects air to float the sheet, and 20 is a nozzle that ejects air to separate only one sheet. The nozzles 19 and 20 are connected to a blower 21 for ejecting air. The ejection of air from the nozzles 19 and 20 can be selectively switched by a valve 22. Reference numeral 23 is a pair of conveying rollers for conveying the conveyed sheet further downstream.

Next, a mechanism for making the angle θ variable according to the stiffness of the seat will be described. 25 is a roller 15,
An angle adjusting shaft support plate through which 16 shafts pass is rotatable about the shaft center of the roller 15. Reference numeral 76 denotes an angle adjustment arm rotatably attached to the angle adjustment support plate 75, and 77 denotes a rack to which the angle adjustment arm 76 is rotatably attached, which is indicated by an arrow B in the drawing by engaging with the pinion gear 79a. It can be moved in any direction.
79 is a motor for rotating the pinion gear 79a.

These are the angles θ depending on the sheet to be fed.
To set the angle to satisfy the following two conditions. The first is that only the uppermost sheet S1 is completely adsorbed by the second sheet adsorbing section 8, and the second is that the second sheet S2 is the first sheet S1. This means that the force of maintaining the flatness of the second sheet S2 due to the stiffness of the paper is larger than the force of being attracted at the same time and being convex downward with the displacement fulcrum portion 15a as a fulcrum.

Next, the means for detecting the stiffness of the sheet, which is the core of the present invention, will be described. Reference numeral 30 denotes a detection protrusion that is movable in the direction of arrow C in the figure. Reference numeral 31 is a photo sensor for detecting the position of the detection protrusion.

The operation of the above-described air feeding device when the stiffness of the sheet is strong will be described with reference to FIG. The valve 22 is switched to the position a by a switching means such as a solenoid (not shown), the blower 21 is operated, and air is ejected from the nozzle 19 toward the front end of the sheet. Then, several sheets are blown up and float up. Then, the valve 13 is switched to the position c by a switching means such as a solenoid (not shown), the blower 12 is operated, and air is sucked through the suction openings 6 and 10 and the intake hole 14a.

Accordingly, the top sheet S1 is
The conveyance belt 14 is sucked by the second sheet suction units 4 and 8.
Stick to. Specifically, as shown in FIG. 27, the vicinity of the central portion of the sheet is adsorbed by the first sheet adsorbing section 4, and the vicinity of the leading end of the sheet is adsorbed by the second sheet adsorbing section 8. A downward force due to its own weight is applied to the detection protrusion 30,
Since the paper is strong, the rear end of the paper does not drop much below the substantially flat bottom surface 5, and the detection protrusion 30 is pushed by the paper and moves upward, turning the photo sensor 31 on.

If the separation angle θ is large, the first sheet S1
Is not adsorbed to the second sheet adsorbing section 8 in a stable manner,
The following operation is performed to reduce the separation angle. The control means 37 that receives the on signal of the photosensor is the motor 7
9 is moved to lower the rack 77 via the pinion gear 79a, and the angle θ is set to the above angle.

As a result, the sheet bends against the stiffness of the sheet with the displacement fulcrum portion 15a as the fulcrum, and both the leading end and the central portion of the sheet come into close contact with the conveyor belt 14. That is, the sheet S1 follows the substantially flat bottom surfaces 5 and 9 and has a downward V-shaped shape with the displacement fulcrum portion 15a as a fulcrum. At this time, it is assumed that the second sheet S2 is in close contact with the sheet S1. In this case, since the angle θ is set in advance to the above-mentioned angle, the second sheet S2 has the displacement fulcrum 15
With the a as a fulcrum, the sheet is kept flat without being bent, the leading ends of the sheets are separated, and a gap e is formed between the sheets.

After that, the conveying belt 14 is driven by the driving means (not shown), and the sheet S1 is conveyed in the direction of arrow A. At the same time, the valve 22 is switched to the position of b, air is blown from the nozzle 20 into the gap e between the sheet S1 and the sheet S2, and the sheet S2 is stably separated. Therefore, only the sheet S1 is conveyed downstream and is passed to the pair of conveying rollers 23. After that, an image is formed by a known image forming apparatus.

FIG. 28 shows the settings when the sheet is not sufficiently stiff. Since the downward force due to its own weight is applied to the detection protrusion 30, the rear end of the paper is lowered with respect to the substantially planar bottom surface 5 when the paper is adsorbed. That is, the detection protrusion 30 is lowered and the photo sensor 31 is turned off. When the stiffness of the sheet is weak and the separation angle θ is small, when the first sheet S1 is adsorbed, the second sheet S2 is likely to be adsorbed at the same time, so the separation angle θ must be set to a large value. Moves up the rack.

In the present embodiment, the measurement of the movement amount of the detection projection 30 is explained in only two steps, but the present invention is not limited to this, and it is possible to measure in multiple steps using a slide volume or the like. It is easily conceivable that the paper can be stably fed to various kinds of papers if the measurement is performed or the measurement is performed steplessly. Further, in the present embodiment, the detection projection 30 tries to fall downward due to its own weight, but the present invention is not limited to this, and it is effective to use, for example, a spring or the like, which generates a force directed in the opposite direction to the suction direction. It's easy to think of.

Further, in the present embodiment, the case where the stiffness of the sheet is detected on the trailing end side of the sheet is shown, but the present invention is not limited to this, and the same applies when the leading end side or the lateral side of the sheet is detected. It goes without saying that such an effect can be obtained.

[0130]

【The invention's effect】

<Effect of the First Invention> According to the present invention, in a sheet feeding device including a sheet tray for stacking a plurality of sheets and a sheet conveying section having a sheet suction section, the sheet suction section is provided in the vicinity thereof. The sheet stiffness is detected by the means for detecting the stiffness of the sheet, and the controller that receives the signal detects the thickness (weight) of the sheet from the correlation between the stiffness of the sheet and the thickness (weight). By making a judgment and automatically changing the distance between the sheet tray and the first and second sheet suction portions to the most suitable distance, it is possible to stably feed various types of sheets with the same suction force. . <Effect of the Second Invention> As described above, according to the present invention, in the air feeding device utilizing the suction force of the air, the leading edge of the sheet is first adsorbed on the transport belt to thereby secure the leading edge of the sheet. Since it is configured so that the sheets can be reliably separated, stable feeding is possible without a feeding failure such as a double feeding and a change in feeding performance with time. <Effect of the Third Invention> As described above, according to the present invention, the first detecting means detects that the sheet (S) is adsorbed by the first sheet adsorbing portion, and then the second detecting means delays. When the second detecting means detects that the sheet is adsorbed by the detecting means, and the measuring means measures the time between the two cases, the physical properties of the sheet can be detected. Various conditions in formation and the like can be set to an optimum state. <Effect of the Fourth Invention> According to the present invention, the sheet feeding unit has the first sheet suction unit and the second sheet suction unit that makes an angle with respect to the first sheet suction unit. In the above, in the first sheet suction section, a protrusion provided near the substantially flat sheet suction section and movable at least in the vertical direction of the sheet suction section starts the sheet feeding operation and the sheet suction section moves the sheet. When the sheet is adsorbed, the amount of movement of the sheet due to the force received from the sheet is detected to reliably detect the stiffness (thickness) of the sheet, and the control device receiving the signal automatically By varying the angle formed by the sheet suction section to the angle most suitable for the stiffness of the sheet, it is possible to stably feed various types of sheets with the same suction force.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a sheet feeding device according to an embodiment of the first invention.

FIG. 2 is a vertical cross-sectional side view of the sheet feeding device when feeding a weak sheet.

FIG. 3 is a vertical sectional side view of the sheet feeding device, which also shows the sheet position in the home position.

FIG. 4 is a vertical cross-sectional side view of the sheet feeding device, which also shows the position of the sheet with weak stiffness.

FIG. 5 is a vertical cross-sectional side view of the sheet feeding device when there is one sheet suction unit.

FIG. 6 is a vertical cross-sectional side view of a sheet feeding device according to related art 1.

FIG. 7 is a vertical cross-sectional side view of the sheet feeding device according to the first embodiment of the second invention.

FIG. 8 is a functional diagram of the sheet feeding device.

FIG. 9 is a timing chart according to the operation of the present invention.

FIG. 10 is a block diagram of the control of the sheet feeding device.

FIG. 11 is a vertical sectional side view of the sheet feeding device according to the second embodiment of the second invention.

FIG. 12 is a vertical cross-sectional side view of the vertical cross-sectional side view according to the third embodiment of the second invention.

FIG. 13 is a functional diagram of the third embodiment of the second invention.

FIG. 14 is a functional diagram of the third embodiment of the second invention.

FIG. 15 is a timing chart according to the third embodiment of the second invention.

FIG. 16 is a vertical sectional side view of the sheet feeding device according to the fourth embodiment of the second invention.

FIG. 17 is a vertical sectional side view of the sheet feeding device according to the related art 2.

FIG. 18 is also a sheet feeding device according to the principle of the air feeding device, in which (a) is a vertical side view and (b) is an operation diagram.

FIG. 19 is a vertical cross-sectional side view of the sheet feeding device according to the related art 2.

FIG. 20 is an operation diagram of a sheet feeding device according to the related art 2.

FIG. 21 is a vertical cross-sectional side view of a sheet feeding device to which the sheet physical property detecting device according to the first embodiment of the third invention is applied.

FIG. 22 is an operation diagram of the sheet feeding device and the sheet physical property detecting device.

FIG. 23 is an operation diagram of the sheet feeding device and the sheet physical property detecting device.

FIG. 24 is a timing chart of the sheet physical property detecting device.

FIG. 25 is a timing chart of the sheet physical property detecting device.

FIG. 26 is a block diagram of the sheet physical property detecting device.

FIG. 27 is a vertical sectional side view of the sheet feeding device according to the fourth invention.

FIG. 28 is an operation diagram of the sheet feeding device similarly.

FIG. 29 is a vertical cross-sectional side view of the sheet feeding device according to the related art 4.

FIG. 30 is a function diagram of FIG. 29.

FIG. 31 is a functional diagram of FIG.

[Explanation of symbols]

S sheet S ₁ first sheet S ₂ second sheet 1 sheet tray 4 first sheet suction section 5 substantially flat bottom surface 6 air suction opening 8 second sheet suction section 9 substantially flat bottom surface 10 air Suction opening 12 Blower (air suction means) 12A, 12B Blower (air suction means) 14 Conveyor belt (feeding means) 15a Displacement fulcrum part 19 Nozzle (air blowing means) 29 Motor (changing means) 30 Detection protrusion 31 Photo sensor 30 and 31 means for detecting stiffness of sheet 37 control means 40 detection protrusion 41 photo sensor 40, 41 means for detecting stiffness of sheet 40A second sheet suction portion (suction roller) 41A suction roller 41a suction hole 47 control means 50 First detection means 51,61 Detection arm 53,63 Photo sensor 57 Control section 57a Measuring section (measuring means ) 60 second detecting means 75 angle adjusting support plate 76 angle adjusting arm 77 rack 79 motor 79a pinion 79b flexible duct 75, 76, 77, 79 angle varying means

Claims (23)

[Claims] 1. A sheet tray on which a plurality of sheets are stacked, a sheet suction section facing a plurality of stacked sheets and having a plurality of air suction openings on a substantially planar bottom surface, and an air of the sheet suction section. At least one air suction means for sucking the sheet by sucking air through the suction opening; a detection means provided in the vicinity of the sheet suction portion for detecting the stiffness of the sheet; A change means for changing the distance between the sheet tray and the sheet suction section according to the stiffness of the sheet; a control means for controlling the change means; and a feeding means for feeding the sheet. Sheet feeding device. 2. The sheet feeding apparatus according to claim 1, further comprising at least one air blowing unit for blowing air in the vicinity of the leading end of the sheet bundle stored in the sheet tray. 3. The sheet feeding apparatus according to claim 1, wherein the feeding unit is a conveyance belt which is wound around the sheet suction portion and has a plurality of suction holes on a surface thereof. 4. The projection means is movable by being pushed by the adsorbed sheet,
The sheet feeding device according to claim 1, wherein the sheet feeding device is configured by at least one measuring unit that measures a movement amount of the protrusion. 5. The projection is movable in a direction substantially perpendicular to the sheet suction portion.
The sheet feeding device described in. 6. A sheet tray on which a plurality of sheets are stacked, a first sheet suction section that faces a stacked sheet bundle, and has a plurality of air suction openings on a substantially planar bottom surface, A second sheet suction section which is arranged downstream of the sheet suction section in the sheet conveying direction and has a plurality of air suction openings on a substantially flat bottom surface; and a second sheet downstream of the first sheet suction section and the second sheet. Displacement fulcrum portion disposed upstream of the suction portion and configured to displace the sheets sucked by the first and second sheet suction portions so as to be convex downward, and the first and second sheet suction portions. At least one air suction means for sucking a sheet by sucking air through the air suction opening, a detection means provided near the air suction means for detecting the stiffness of the sheet, and the sheet Tray and above A changing unit that changes the distance between the first and second sheet suction units according to the stiffness of the sheet; a control unit that controls the changing unit; and a feeding unit that feeds the sheet. A characteristic sheet feeding device. 7. The sheet feeding apparatus according to claim 6, wherein the feeding unit is a conveyance belt which is wrapped around the sheet suction portion and has a plurality of suction holes on a surface thereof. 8. The projection means is movable by being pushed by the adsorbed sheet,
The sheet feeding device according to claim 6, wherein the sheet feeding device is configured by at least one measuring unit that measures a movement amount of the protrusion. 9. The sheet feeding apparatus according to claim 8, wherein the protrusion is movable in a substantially vertical direction with respect to the first sheet suction portion. 10. A sheet tray on which a plurality of sheets are stacked, a first sheet suction section that faces the stacked sheet bundle, and has a plurality of air suction openings on a substantially planar bottom surface, Of the first sheet suction section, and a second sheet suction section disposed downstream of the sheet suction section in the sheet conveying direction and having a plurality of air suction openings displaced upward with respect to the substantially flat bottom surface. A displacement fulcrum arranged downstream and in the vicinity of the upstream side of the second sheet suction portion, for displacing the sheet sucked by the first and second sheet suction portions so as to be convex downward. At least one air blowing unit for blowing air to the vicinity of the leading end of the sheet bundle stored in the sheet tray, and a plurality of surfaces wound around at least the first and second sheet suction portions and the displacement fulcrum portion. A conveyor belt having a suction hole, conveying the first and the suction holes of the belt, at least one for attracting the sheet to the conveying belt by sucking air through the air suction opening of the second sheet suction section
A sheet feeding device comprising: individual air suction means; and control means for independently sucking air from the first and second sheet suction portions, the sheet feeding device comprising: 2. The sheet feeding device according to claim 1, wherein the control means controls to suck air from the sheet suction portion first, and then to suck air from the first sheet suction portion. 11. The second sheet suction portion is composed of a substantially flat bottom surface having a plurality of air suction openings, and the first sheet suction portion and the second sheet suction portion are the displacement fulcrums. 11. The sheet feeding device according to claim 10, wherein the sheet feeding device has a predetermined angle with the portion as an apex so as to be convex downward. 12. The second sheet suction portion is a suction roller having a plurality of air suction openings, and the displacement fulcrum portion is a part of the surface curvature of the suction roller. 10. The sheet feeding device according to item 10. 13. A sheet tray on which a plurality of sheets are stacked, a first sheet suction section that faces the stacked sheet bundle, and has a plurality of air suction openings on a substantially planar bottom surface, Of the first sheet suction section, and a second sheet suction section disposed downstream of the sheet suction section in the sheet conveying direction and having a plurality of air suction openings displaced downward with respect to the substantially flat bottom surface. A displacement fulcrum disposed downstream and in the vicinity of the upstream side of the second sheet suction portion, for displacing the sheet sucked by the first and second sheet suction portions so as to be convex upward; At least one air blowing unit for blowing air to the vicinity of the leading end of the sheet bundle stored in the sheet tray, and a plurality of surfaces wound around at least the first and second sheet suction portions and the displacement fulcrum portion. A conveyor belt having a suction hole, conveying the first and the suction holes of the belt, at least one for attracting the sheet to the conveying belt by sucking air through the air suction opening of the second sheet suction section
A sheet feeding device comprising: individual air suction means; and control means for independently sucking air from the first and second sheet suction portions, the sheet feeding device comprising: 2. The sheet feeding device according to claim 1, wherein the control means controls to suck air from the sheet suction portion first, and then to suck air from the first sheet suction portion. 14. The second sheet suction portion is composed of a substantially flat bottom surface having a plurality of air suction openings, and the first sheet suction portion and the second sheet suction portion are the displacement fulcrums. 14. The sheet feeding device according to claim 13, wherein the sheet feeding device has a predetermined angle with the portion as the apex so as to be convex upward. 15. The second sheet suction portion is a suction roller having a plurality of air suction openings, and the displacement fulcrum portion is a part of the surface curvature of the suction roller. 13. The sheet feeding device according to item 13. 16. A first sheet adsorbing portion facing a sheet to be measured and having at least one air suction opening on a substantially flat bottom surface, and at least one air facing the sheet and having a substantially flat bottom surface. A second sheet suction portion having a suction opening; at least one air suction means for sucking air through the air suction openings of the first and second sheet suction portions; and a first sheet suction portion of the first sheet suction portion. A first detection unit that is provided in the vicinity of the first sheet suction unit and detects that the sheet has been sucked by the first sheet suction unit; and a sheet that is provided in the vicinity of the second sheet suction unit. Second detection means for detecting that the sheet is adsorbed by the second sheet adsorbing section, and the sheet is detected by the second sheet adsorbing section after the sheet is adsorbed by the first sheet adsorbing section. Up to Sheet properties detecting apparatus comprising: the measuring means. 17. The sheet according to claim 16, wherein the distance from the sheet to be measured to the first detecting means is different from the distance from the sheet to the second detecting means. Physical property detector. 18. A display means for displaying a signal measured by the measuring means.
The sheet physical property detection device described in 1. 19. A sheet tray on which a plurality of sheets are stacked, a first sheet suction section that faces the stacked sheet bundle, and has a plurality of air suction openings on a substantially planar bottom surface, Of the first sheet suction section, and a second sheet suction section disposed downstream of the sheet suction section in the sheet conveying direction and having a plurality of air suction openings displaced upward with respect to the substantially flat bottom surface. A displacement fulcrum arranged downstream and in the vicinity of the upstream side of the second sheet suction portion, for displacing the sheet sucked by the first and second sheet suction portions so as to be convex downward. At least one air blowing unit for blowing air to the vicinity of the leading end of the sheet bundle stored in the sheet tray, and a plurality of surfaces wound around at least the first and second sheet suction portions and the displacement fulcrum portion. A conveyor belt having a suction hole, conveying the first and the suction holes of the belt, at least one for attracting the sheet to the conveying belt by sucking air through the air suction opening of the second sheet suction section
Individual air suction means, a first detection means arranged near the first sheet suction section and detecting that the sheet has been sucked by the first sheet suction section, and the second sheet A second device that is disposed in the vicinity of the suction unit and detects that the sheet has been sucked by the second sheet suction unit.
And a measuring means for measuring the time between the sheet being adsorbed by the first sheet adsorbing section and the sheet being adsorbed by the second sheet adsorbing section. Sheet feeding device. 20. A sheet tray on which a plurality of sheets are stacked, a first sheet suction section that faces a stacked sheet bundle, and has a plurality of air suction openings on a substantially planar bottom surface, A second sheet suction section which is arranged downstream of the sheet suction section in the sheet conveying direction and has a plurality of air suction openings on a substantially flat bottom surface; and a second sheet downstream of the first sheet suction section and the second sheet. Displacement fulcrum portion disposed upstream of the suction portion and configured to displace the sheets sucked by the first and second sheet suction portions so as to be convex downward, and the first and second sheet suction portions. At least one air suction means for sucking a sheet by sucking air through the air suction opening of the first sheet suction means, provided near the first sheet suction portion, and pushed by the sucked sheet. Can be moved And a detection unit that detects the amount of movement of the protrusion that is pushed and moved by the sheet when the sheet is adsorbed by the first sheet adsorbing unit, and the first sheet adsorbing unit. A sheet feeding device comprising: an angle changing unit that changes an angle formed by the first sheet suction unit and the second sheet suction unit with the displacement fulcrum portion as an apex; and a sheet feeding unit that feeds the sheet. 21. The sheet feeding apparatus according to claim 20, further comprising at least one air blowing unit for blowing air in the vicinity of the leading end of the sheet bundle stacked on the sheet tray. 22. The feeding means is wrapped around the first and second sheet suction portions and the displacement fulcrum portion,
21. The sheet feeding device according to claim 20, wherein the sheet feeding device has a plurality of suction holes on a surface thereof. 23. The sheet feeding apparatus according to claim 20, wherein the protrusion is movable in at least a vertical direction of the first sheet suction portion.