JPH0211389Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field> The present invention relates to a device for preventing double feeding of sheet materials, and is particularly applicable to highly reliable sheet material input mechanisms such as copying machines, electronic files, facsimile machines, printing machines, etc. The present invention relates to a device for preventing double feeding of sheet materials, which is used in equipment requiring the following.

<Prior Art> Various means have been conventionally 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 due to 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. .

<Purpose of the invention> In view of the above-mentioned drawbacks, the present invention uses an air suction system and prevents double feeding, instead of using a large force to bring the friction member into contact with the sheet material to prevent double feeding as in the past. By using a sheet material suction device for preventing double feeding, which has a friction member on a part of the surface with the suction port, multiple sheet materials can be conveyed simultaneously without damaging the sheet materials. It is an object of the present invention to provide a highly reliable sheet material double feeding prevention device that can reliably prevent double feeding of sheet materials.

<Embodiment> The apparatus for preventing double feeding of sheet materials of the present invention will be described in detail below with reference to the drawings showing an embodiment of the present invention.

Fig. 1 is a schematic side view of a sheet material suction device for preventing double feeding in an embodiment of the present invention, Fig. 2 is a schematic front view thereof, and Fig. 3 is an enlarged perspective view showing its suction port, friction member, etc. , FIGS. 4a, b, c, and d are explanatory diagrams of the operation, and FIG. 5 is an explanatory diagram of the effect of the friction member. Identical parts are given the same reference numerals.

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. and 12 are attached to slide shafts 10 and 13 fixed to a slide shaft fixing plate (not shown), and are driven by a drive device (not shown).

Next, the operation of the sheet material double-feed prevention device according to this embodiment constructed as described above will be explained with reference to FIGS. 4 and 5.

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 symbol P indicates a plurality of sheet materials stacked on the paper feed base plate 23, respectively. 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 picks up the uppermost sheet material P' of the plurality of sheet materials P stacked on the sheet material suction 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.

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 made 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. .

When the sheet material suction device J for preventing double feeding does not adsorb any sheet material, that is, when there is only one sheet material, the sheet material suction device J for preventing double feeding is shown in the broken line as shown in Fig. 4c. Return to the standby position indicated by .

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 detection operation similar to the above is entered, and the sheet material reaches 1
Repeat until you have a sheet.

In the state in which the sheet material adsorbed by the sheet material adsorption device 21 becomes only the uppermost sheet material P' to be fed as described above, the sheet material conveying device 22 is the highest sheet material
P' is caught and conveyed in the direction of arrow E. Then, the same operation as above is repeated for the next and subsequent sheet materials, and the sheet materials are sequentially conveyed.

One embodiment of the present invention has been described above, but in this embodiment, as described above, 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 is used. As shown in FIG. 5, a friction member 18 is provided at the sheet material adsorption device 21 to adsorb the sheet material for preventing double feeding until the friction member 18 comes into contact with the back surface of the uppermost sheet material P' adsorbed by the sheet material adsorption device 21 with a constant pressure. Device J moves forward. At this time, as shown in FIG. 5, if two sheet materials are pulled up by the sheet material adsorption device 21 at once, the next sheet material P'' to the highest sheet material P' to be conveyed. The back surface of the friction member 1 is pressed with a constant pressure by the friction member 18 described above, so that the friction member 1 is pressed with a constant pressure as shown in FIG.
A gap S ₁ is generated between the sheet materials P' and P'' at the end pushed by 8, and the sheet materials P' and P'' are caused by the inflow of air.
The adsorption force between the sheets between P'' and 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 adsorption force between the sheets acting between the 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.

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 suction device for preventing double feeding according to the present invention, double feeding of sheet materials can be reliably prevented without staining or damaging the sheet materials.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of the sheet material suction device for preventing double feeding according to the present invention, Fig. 2 is a schematic front view thereof, Fig. 3 is an enlarged perspective view showing the suction port, friction member, etc. 4a, b, c, and d are explanatory diagrams for explaining the operation of the present invention, and FIG. 5 is an explanatory diagram of the effect of the friction member. 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 plate, 30...Negative pressure generation fan, P, P', P''... ...Sheet material, J...
Sheet material adsorption device to prevent double feeding.

Claims (1)

[Claims for Utility Model Registration] When the sheet material is at a predetermined paper feeding position, a suction unit that suctions and adsorbs the uppermost surface of the sheet material, and a pressing member that presses the sheet material; A sheet material suction device that lifts up the sheet material by rotating the suction section upward using the member as a fulcrum, and a suction surface having an air suction port and a friction member on the back side of the sheet material lifted by the sheet material suction device. a double-feed prevention device that separates sheet materials other than the topmost sheet material by adsorption; and a double-feed prevention device that reaches a position where a friction member of the double-feed prevention device abuts with a predetermined pressure along the back surface of the sheet material. An apparatus for preventing double feeding of sheet materials, comprising a movement control means including a position control circuit that controls the movement of the sheet material so that the sheet material is moved forward and is moved backward to the standby position after the sheet material adsorption/separation operation is completed.