JPH0219059B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention is applicable to sheet material feeding devices, particularly machines such as copying machines, electronic files, facsimile machines, printing machines, etc., which require high reliability in the sheet material input mechanism. The present invention relates to a sheet material feeding device used in the device.

<Prior Art> Conventionally, various means have been provided for separating and conveying a plurality of sheets stacked on a paper feed plate one by one. For example, there is a method using corner separation claws. This method has the disadvantage that if the force acting between the sheet materials, the so-called adhesion force between sheets, is large, it is impossible to separate the sheets, and furthermore, the edges of the sheet materials may be damaged. .

There is also a method of using a friction member such as a reversing roller, but with this method, if the thickness of the sheet material changes, delicate adjustments must be made to match the change.
If this adjustment is not performed or if the adjustment is inappropriate, there is a drawback that sheet materials are likely to be fed in duplicate. Furthermore, the disadvantages of the above method are that the sheet material may be soiled or damaged, and the separation ability may be reduced due to changes in the coefficient of friction caused by the presence of paper dust or changes in the roller material over time. It is.

Furthermore, there is a method that uses a suction air box together with rollers, belts, etc., but this method separates only the sheet material to be fed when more than two sheets are being fed at once. It is not suitable for devices that require high reliability in the input mechanism for sheet materials, as described above, as it has many drawbacks such as being able to easily damage and stain the sheet material. .

<Object of the Invention> In view of the above, the present invention includes a suction unit that suctions the uppermost surface of the sheet material by air suction and a pressing member that presses the sheet material when the sheet material is at a predetermined paper feeding position. a first sheet material suction means that lifts up the sheet material by rotating the suction section upward using the pressing member as a fulcrum; and a suction device having an air suction port and a friction member on the back surface of the lifted sheet material. It is adsorbed by the surface,
a second sheet material suction means for separating sheet materials other than the uppermost sheet material; a moving means for reciprocating the second sheet material suction means from a standby position to a vicinity of a predetermined sheet material suction position; The moving means moves the second sheet material adsorption means forward to a position where the friction member of the adsorption means abuts against the back surface of the sheet material with a predetermined pressure, and after the sheet material adsorption and separation operation is completed, moves the second sheet material adsorption means back to the standby position. a movement control means for controlling the uppermost sheet material; and a sheet material conveyance means for gripping and conveying the uppermost sheet material, wherein the friction member of the second sheet material adsorption means abuts against the back surface of the sheet material with a predetermined pressure. Accordingly, a gap is created between the uppermost sheet material and the other sheet materials, thereby weakening the adhesion force between the sheets of the sheet material, and the first sheet adsorption means is characterized in that when the first sheet adsorption means Sheet material feeding that dynamically creates a space between the plurality of sheet materials to weaken the adhesion force between the sheets and prevent double feeding of the sheet materials when the materials are lifted at the same time. The purpose is to provide equipment.

<Example> Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic side view of a sheet material suction device of a sheet material feeding device according to an embodiment of the present invention, FIG. 2 is a schematic front view of the sheet material suction device, and FIG. 3 is a schematic front view of the sheet material suction device. Partial perspective view of the device, Figures 4a, b,
c and d are explanatory diagrams of the operation of the sheet material feeding device, and FIG. 5 is a diagram of a mechanism for preventing double feeding of sheet materials by the sheet material feeding device. Note that the same parts are given the same symbols.

In FIGS. 1 and 2, J indicates the entire sheet material suction device for preventing double feeding, which has a suction air casing 1. A negative pressure chamber 2 is formed inside the suction air casing 1, and a part of the suction air casing 1 has an air suction port 14 projecting forward.
A sheet material adsorption section 3 is formed. Sheet material adsorption section 3 forming this air suction port 14
In the center is a frame 5 that divides the air suction port 14 into two.
A friction member protection portion 9 is provided near the top end of the frame 5 to sharpen the ends of the friction member 18 and the sheet material suction portion 3. Further, a negative pressure generating fan 30 for generating negative pressure inside the negative pressure chamber 2 is attached to the lower part of the suction air casing 1. Furthermore, the entire unit described above is designed to freely reciprocate in the direction indicated by the arrow A in FIG. 1
2 is attached to slide shafts 10 and 13 fixed to a slide shaft fixing plate (not shown), and is driven by a drive device (not shown).

Next, the operation of the sheet material double feeding prevention device of this embodiment constructed as described above will be explained with reference to FIG. 4.

In FIG. 4, reference numeral 21 denotes a sheet material suction device, 22 a sheet material conveyance device, 23 a paper feed base plate provided vertically movably in the direction of arrow C, and 24 a document conveyance guide. , the reference numeral 41 indicates a pressure roller, and the reference numeral P indicates a plurality of sheet materials stacked on the paper feed base plate 23. Further, the symbol P' indicates the sheet material to be fed, that is, the uppermost sheet material, and the symbol P'' indicates the sheet material next to the uppermost sheet material P'.

First, in FIG. 4a, when an instruction is given to start feeding sheet materials, the sheet feeding base plate 23 transfers the uppermost sheet P' of the plurality of sheet materials P stacked thereon to the sheet material adsorption device 21. The sheet material rises along the direction of arrow C until it touches the suction port which is the sheet material suction surface. At this time, the sheet material suction device J for preventing double feeding is in the standby position shown by the solid line, and no suction operation is performed.

Next, as shown in FIG. 5B, the uppermost sheet material P' is sucked by the sheet material suction device 21, and is raised to a predetermined position shown in the figure, that is, a sheet feeding position, and then stopped.
Note that when the sheet material is at the paper feeding position, a substantially constant pressure is applied to the sheet material by the pressure roller.

Then, the sheet material suction device J for preventing double feeding starts the suction operation, and moves forward until the friction member 18 comes into contact with the back surface of the uppermost sheet material P' that has been suctioned by the sheet material suction device 21 with a constant pressure. . Thereafter, it retreats slightly to a predetermined position indicated by a solid line, that is, a sheet material adsorption detection position. The forward and backward movement of the sheet material adsorption device J for preventing double feeding is performed by a position control circuit (not shown). At this position, it is detected whether the sheet material is adsorbed to the suction port of the sheet material suction device J for preventing double feeding. A negative pressure detector (not shown) measures the negative pressure inside the suction air casing when it is being adsorbed and when it is not being adsorbed. In this case, since the suction force of the sheet material suction device J for preventing double feeding is weaker than the suction force of the sheet material suction device 21, the sheet material suction device J for preventing double feeding will not pull down the sheet material. .

If the sheet material is not adsorbed by the sheet material adsorption device J for preventing double feeding, that is, if the sheet material is
In the case of only one sheet, as shown in FIG. 4c, the sheet material suction device J for preventing double feeding returns to the standby position shown by the broken line.

On the other hand, if two or more sheet materials are being pulled up by the sheet material suction device 21, the fourth
As shown in Figure b, sheet material adsorption device J for preventing double feeding
The next sheet material P'' is attracted to the suction port, and the uppermost sheet material P' and the next sheet material P'' are separated. Note that the suction force of the sheet material suction device J for preventing double feeding is set to be larger than the suction force between sheets. Then, the above-mentioned negative pressure detector detects the above-mentioned state, and the double-feed prevention sheet material suction device J returns to the standby position shown by the solid line in Figure 4a, and the sheet material P'' falls and returns to its original position. After the predetermined time required to return has elapsed, a similar detection operation is performed as described above, and the sheet material is 1
Repeat until you have a sheet.

In the state in which the sheet material adsorbed by the sheet material adsorption device 21 as described above becomes only the uppermost sheet material P' to be fed, the pressure applied by the pressure roller is released by a solenoid (not shown), Fourth
As shown in FIGS. c and d, the sheet material conveying device 22 picks up the uppermost sheet material P' and conveys it in the direction of the arrow E. Then, the same operation as above is repeated for the next and subsequent sheet materials, and the sheet materials are sequentially conveyed.

Next, the mechanism for preventing double feeding of sheet materials in the sheet material feeding device of this embodiment will be explained using FIG.

In this embodiment, as described above, the friction member 18 is provided in a part of the sheet material suction section 3 forming the suction port 14 of the sheet material suction device J for preventing double feeding.
As shown in the figure, the sheet material suction device J for preventing double feeding moves forward until the friction member 18 comes into contact with the back surface of the uppermost sheet material P' adsorbed by the sheet material suction device 21 with a constant pressure. At this time, as shown in the same figure, if two sheet materials are pulled up by the sheet material adsorption device 21 at once, the next sheet material P'' of the highest sheet material P' to be conveyed is The back side is pressed with a constant pressure by the friction member 18, and therefore, as shown in the figure, there is a gap S ₁ between the sheet materials P' at the end where the friction member 18 presses. occurs, and due to the inflow of air, the sheet material P′,
The adsorption force between sheets P'' is weakened, and a shift _S2 also occurs at the rear of the pushed sheet material, that is, at the leading edge of the sheet material, and the interpaper adsorption force acting between sheet materials P' and P'' is weakened. The sheet material P'' is attracted to the suction section 3 of the sheet material suction device J for preventing double feeding.

However, if the adsorption force between sheets is strong, the sheet material
Since P′ and P″ are trying to move at the same time, the gap S ₁
Although the occurrence of deviation _S2 is tried to be suppressed, the sheet material becomes stiff because the pressure roller 41 is pressurizing the sheet material. The next sheet material P'', which is subjected to a large force by the friction member 18, is curved more than the uppermost sheet material P', thus creating a gap _S1 and a deviation _S2 , and for the same reason as above. The sheet material P'' is attracted to the suction section of the sheet material suction device J for preventing double feeding.

In addition, even when there are more than two sheets pulled up by the sheet material suction device 21, the same effect as described above is applied to the lower sheet materials, and the above-mentioned double feeding is carried out sequentially or at a time until only one sheet material at the top remains. Preventive action is taken. Even if the force with which the friction member 18 is pressed against the back surface of the sheet material is very small, a sufficient effect can be obtained. Furthermore, even if the friction member does not protrude from the sheet material adsorption surface as in this embodiment, or even if the friction member is not positioned as in this embodiment, almost the same effect can be obtained as long as it is on the sheet material adsorption surface of the same device. Needless to say, it can be done.

<Effects> As described above, according to the sheet material feeding device of the present invention, the folded portion of the lifted sheet material is pressed by the pressing member, and the sheet material is pressed by the friction member. Therefore, even if multiple sheets are adsorbed, a space is created between the sheets and the suction force between the sheets is significantly reduced, so that the sheet material that is not being fed is easily peeled off from the sheet material that is to be fed. It is possible to prevent double feeding of sheet materials.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a sheet material suction device of a sheet material feeding device according to an embodiment of the present invention, FIG. 2 is a schematic front view of the sheet material suction device, and FIG. 3 is a schematic front view of the sheet material suction device. Partial perspective view of the device, Figures 4a, b,
c and d are explanatory diagrams of the operation of the sheet material feeding device, and FIG. 5 is a diagram of a mechanism for preventing double feeding of sheet materials by the sheet material feeding device. DESCRIPTION OF SYMBOLS 1... Suction air casing, 2... Negative pressure chamber, 3... Sheet material adsorption part, 8, 12... Slider, 10, 13... Slide shaft, 9... Friction member protection part, 14... Air Suction port, 18... Friction member, 21... Sheet material adsorption device, 22... Sheet material conveyance device, 23... Paper feed base plate, 30... Negative pressure generation fan, 41... Pressure roller, P ,P′,
P″...Sheet material, J...Sheet material adsorption device to prevent double feeding.

Claims (1)

[Scope of Claims] 1. A suction unit that suctions and adsorbs the uppermost surface of the sheet material when the sheet material is at a predetermined paper feeding position, and a pressing member that presses the sheet material, the pressing member a first sheet material suction means that lifts up the sheet material by rotating the suction section upward using the suction part as a fulcrum; and a suction surface having an air suction port and a friction member on the back surface of the lifted sheet material,
a second sheet material suction means for separating sheet materials other than the uppermost sheet material; a moving means for reciprocating the second sheet material suction means from a standby position to a vicinity of a predetermined sheet material suction position; The moving means moves the second sheet material adsorption means forward to a position where the friction member of the adsorption means abuts against the back surface of the sheet material with a predetermined pressure, and after the sheet material adsorption and separation operation is completed, moves the second sheet material adsorption means back to the standby position. a movement control means for controlling the uppermost sheet material; and a sheet material conveyance means for gripping and conveying the uppermost sheet material, wherein the friction member of the second sheet material adsorption means abuts against the back surface of the sheet material with a predetermined pressure. A sheet material feeding device characterized in that a gap is created between the uppermost sheet material and the other sheet materials, thereby weakening the adhesion force between the sheets.