JP2975856B2 - Automatic paper feeding method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sheet feeder and a sheet feeder having a structure in which sheet media (hereinafter, referred to as sheets) stacked on a sheet feed table is fed by frictional force of a sheet feed roller rotating in contact with a sheet surface. It concerns the paper method.

[0002]

2. Description of the Related Art An automatic paper feeder having a structure in which paper stacked on a paper feed table is fed by a paper feed roller is widely used for office equipment such as a printer of an information processing apparatus, an image reading apparatus, a copying machine, and a facsimile machine. Have been. Various paper sheets having different sizes and thicknesses are used in office work sites, and in slips and the like, sheets in which a large number of copy sheets are bound (referred to as “multiple copy sheets”) are also used. Therefore, in an automatic paper feeder for office equipment, a device capable of stably feeding these various types of paper is required.

[0003] In the case of automatically feeding a stack of sheets separated one by one, thin paper generally tends to cause a double feed, and thick paper tends to cause a paper feed error (paper is not fed out). Further, in the case of a multi-sheet copy sheet, if the sheet feeding force is increased, delamination of the sheet tends to occur. In order to prevent double feed of thin paper and delamination of a large number of sheets of paper from occurring, a conventional automatic paper feeder uses a small standard paper feed force. Means for increasing the paper feeding force when paper cannot be sent out is employed.

FIGS. 5 and 6 show examples of an automatic sheet feeding apparatus and a sheet feeding method employing the above-mentioned means. In FIG. 5, the paper feed roller 4 is fixed to a roller shaft 13, and the roller shaft 13 is supported at the tip of a support lever 12 that can freely swing around a fulcrum shaft 11. A driven gear 14 is fixed to one end of the roller shaft 13, and the driven gear 14 meshes with a transmission gear 16 supported on the fulcrum shaft 11.
The support lever 12 has a pad shaft 21 parallel to the roller shaft 13.
A pad table 22 urged clockwise in the figure by a spring (not shown) is pivotally supported on the pad shaft 21, and a separation pad 23 is attached to the tip of the pad table 22. The separation pad 23 is pressed against the peripheral surface of the paper feed roller 4 by the urging force of the spring.

The paper 29 to be fed is stacked on the paper feed table 1 driven up and down by a motor (not shown).
The upper surface of the sheet comes into contact with the paper feed roller 4 by the upward movement, and is fed by the clockwise rotation of the paper feed roller 4 in FIG. Are separated. The rotation direction of the transmission gear 16 when the paper feed roller 4 feeds out the paper 29 is counterclockwise in the drawing, and is a direction in which the support lever 12 swings upward. Transmission gear 1
A tangential force corresponding to the driving load of the feed roller 4 acts on the meshing portion between the transmission gear 1 and the driven gear 14.
The tangential force applied from 6 to the driven gear 14 is upward. Since this tangential force acts to lift the support lever 12 upward, as the tangential force increases, that is, as the driving load of the feed roller 4 increases, the pressing force of the feed roller 4 against the sheet increases. Drops. That is, in the conventional apparatus, even when the driving load of the paper feed roller 4 becomes large, the pressing force of the paper feed roller 4 against the paper is not increased, thereby avoiding the occurrence of double feed during thin paper feeding. .

The paper feed position serving as a reference for the paper 29 is set by detecting the tip of a sensor lever 24 integrated with the support lever 12 by a paper feed position sensor 26. That is, the paper feed table 1 is raised, and the paper 29 pushes up the paper feed roller 4,
When the leading end of the sensor lever 24 is detected by the paper feed position sensor 26 when the predetermined push-up height is reached,
Is stopped, and the rotation of the paper feed roller 4 is started. The pressing force between the paper feed roller 4 and the paper 29 at the reference paper feed position is set by the weight of members such as the paper feed roller and the pad base and the urging force of the first spring 25.
In the illustrated apparatus, since the weight of the paper feed roller 4 and the pad base 22 is greater than the pressing force required to feed the thin paper without double feed, the first spring 25 in the direction in which the support lever 12 is lifted is used for the reference paper feed. The pressing force of the paper feed roller at the position is adjusted so as to be a desired value.

When the paper 29 is a thick paper or the like having a large paper feeding resistance, the paper cannot be sent out by the pressing force at the reference paper feeding position. Therefore, in the illustrated device, a second spring 27 for increasing the pressing force of the paper feed roller 4 is provided. The second spring 27 is a hairspring spring having one end fixed to the immovable member 31, and its free end 32 is opposed to the tip of the sensor lever 24, and after the tip of the sensor lever 24 is detected by the paper feed position sensor 26. Further, it is provided at a position where it comes into contact with the tip of the sensor lever 24 when the sensor lever swings (therefore, the support lever 12 moves up).

Next, a paper feeding operation in the above-described apparatus will be described with reference to FIG. When the sheet 29 is pushed up by the sheet feeding table 1 and the sheet feeding roller 4 reaches the reference sheet feeding position, the tip of the sensor lever 24 is detected by the sheet feeding position sensor 26. In response to the detection signal of the paper feed position sensor 26, the lifting of the paper feed table 1 is stopped, and the rotation drive of the paper feed roller 4 is started. When the sheet 29 is a thin sheet or a large number of copy sheets that are sent out with a small sheet feeding force, the sheet 29 is sent out at this reference position. A sheet detection sensor 33 is provided on the sending side of the sheet 29, and the sending of the sheet 29 is detected by the sheet detection sensor 33.

If the sheet is thick paper or the like having a large sheet feeding resistance, the sheet is not fed at the reference sheet feeding position where the sheet feeding force is set small. Therefore, at the timing when the paper feed roller 4 starts to rotate and rotates by a predetermined amount, the paper detection sensor 3
The detection signal of No. 3 is inspected, and if no paper is detected, the paper feed roller 4 is stopped and the paper feed table 1 is raised again. This raising operation causes the support lever 12 to move upward beyond the reference sheet feeding position, and the tip of the sensor lever 24 is moved to the second spring 2.
7 against the free end 32 and is pushed in. Further, the swing amount of the sensor lever 24 reduces the amount of displacement of the first spring 25, and the urging force applied by the first spring 25 in the direction of lifting the support lever 12 also decreases. Therefore, by moving the paper feed table 1 upward, the pressing force of the paper feed roller 4 increases. After the paper feeding force is increased in this way, the paper feeding roller 4 is rotated again to feed out the paper 29.

[0010]

However, in the above-mentioned conventional structure, the pressing force of the paper feed roller on the paper is changed in two stages, so that the spring 25 for adjusting the pressing force of the paper feed roller 4 is provided. 27 are required, and the spring force must be set for each of these two springs.
Further, if the sheet feeding resistance of the sheet 29 is large, the sheet feeding roller 4 is lifted accordingly, so that it is necessary to provide a space above the sheet feeding roller to allow the sheet feeding roller to rise. Further, for a sheet having a large sheet feeding resistance, the sheet feed roller is stopped, the sheet table is further raised, and the sheet feeding roller is driven again to feed the sheet. Therefore, the sheet throughput is reduced.

The present invention provides a paper feeding method which prevents double feed of thin paper by an operation completely different from that of the conventional apparatus, and furthermore, by using such a method, the structure is simpler and the apparatus is more compact. It is an object of the present invention to obtain an automatic sheet feeder that can perform the above-described processing and improve the throughput.

[0012]

According to the present invention, after the paper feed roller 4 in a stopped state is once pressed against the paper 29 stacked on the paper feed table 1, the paper feed roller 4 is pressed while reducing the pressing contact force.
Is rotated to give paper feeding force, thereby preventing double feeding of thin paper. In an automatic sheet feeding apparatus having a structure in which the sheet feeding table 1 is moved upward to press the sheet 29 against the sheet feeding roller 4, the sheet feeding table 1 is once raised to a height where the upper surface of the sheet exceeds the reference sheet feeding position, and then the sheet feeding is performed. The paper feeding operation of the above method is performed by rotating the paper feeding roller while lowering the paper board 1. The rotation start timing of the paper feed roller 4 is at the same time as or immediately after the operation of decreasing the pressing force of the paper feed roller 4 is started. In a structure in which the paper feed roller 4 is pressed against the paper 29 by raising the paper feed table 1, the rotation of the paper feed roller 4 starts simultaneously with or immediately after the lowering operation of the paper feed table 1 is started.

The automatic paper feeder according to the present invention controls the pressing force and the rotation start timing of the paper feed roller 4 according to the above-described method, and when the driving load of the paper feed roller 4 increases, the paper feed roller 4 The tangential force of the transmission mechanism acts in a direction to increase the pressing force on the transmission 29. In other words, in the apparatus in which the paper feed roller 4 is driven by the belt drive, the tangential force of the belt wound around the transmission wheel that is supported on the frame side is applied to the driven wheel that is supported by the member that supports the paper feed roller 4. The transmission wheel and the driven wheel are arranged so as to work downward. In the case where the paper feed roller 4 is rotated by a gear mechanism, a tangential force from a transmission gear 16 supported on the frame side is applied to a member (support lever in the illustrated example) 12 that supports the paper feed roller 4. The driven gear 14 and the intermediate gear 15 are arranged so as to act downward on the gear 16 that has been set.

[0014]

When the stacked papers 29 are once pressed by the paper feed roller 4 and the paper feed roller 4 is rotated while reducing the pressing force, a frictional paper feed force is applied to one of the stacked papers. The occurrence rate of double feed at the time of feeding the paper is greatly reduced. This effect is presumed to be due to the following reasons. That is, the stacked sheets constitute an elastic system schematically shown by a spring 34 and a dash pot 35 as shown in FIG. Then, the gap between the papers, which are considered to be in contact at many points, is crushed, and when the pressing force of the paper feed roller 4 is released, the elastic recovery force in the direction perpendicular to the plane of each paper causes the papers to lose their mutual contact. The gap between them widens. Although the deformation of the paper in the direction perpendicular to the plane is slight and varies depending on the type of paper (texture of the paper itself and surface treatment), the degree of freedom as schematically shown in FIG. It can be considered that the vibration system is constituted. Therefore, when the pressing force P of the stacked sheets 29 is applied and released, each sheet vibrates in the direction perpendicular to the plane of the sheet adjacent thereto, and at a certain moment, one sheet Is larger than the gap when the stacked sheets are placed in a stationary state.

[0015] The frictional force between the papers which resists the feeding of the papers at the time of paper feeding and causes double feed is due to static friction. Friction force drops rapidly (dynamic friction)
However, it is possible to feed a sheet with a small sheet feeding force without generating a double feed. When the stacked paper vibrates as described above, the coefficient of static friction between the papers temporarily decreases when the gap between one paper and the adjacent paper is opened. It is speculated that double feed of paper is avoided due to slippage (feeding) between them.

The above-described vibration of the paper is caused not only when the pressing force P is instantaneously released but also when the pressing force P is reduced at a certain speed or more. However, when the sheet feeding table 1 was lowered at a speed substantially equal to the speed at which the sheet feeding table 1 was being lifted, a large reduction in the occurrence rate of double feed was observed. Further, the vibration of the stacked paper as described above also occurs when the paper feed tray on which the paper is loaded is changed from ascending to descending.

According to the method of the present invention, double feed of thin paper can be avoided by the above-described operation, so that when the driving load of the paper feed roller 4 increases, the paper feed roller 4
Even if a paper feed roller drive mechanism that increases the pressing force of the paper 1 on the paper 1 is used, double feed does not occur when feeding thin paper. Further, by using such a driving mechanism of the feed roller, the feed roller 4 is strongly pressed against the sheet due to an increase in the driving load acting on the feed roller 4 for thick paper having a large feed resistance. Since a large paper feeding force is applied to the paper, it is possible to prevent a thick paper from being erroneously fed.

That is, in the device of the present invention having the above structure,
The thin paper is fed at a rapid stage when the pressing force of the paper feed roller 4 on the stacked paper has begun to decrease, and when the paper is thick paper, the vibration of the paper due to the release of the pressing force has subsided. Due to the operation of the drive system 4, the paper is sent out when the pressing force of the paper feed roller 4 increases.

[0019]

1 to 3 show an embodiment of the present invention. FIG. 2 is an overall perspective view of an automatic paper feeder, FIG. 1 is a schematic perspective view of a main part of the automatic paper feeder, FIG. 3 is a control flowchart. In FIG. 2, a paper feed table 1 is mounted on a frame 2 so as to be able to swing up and down by a pivot pin 3, and a paper feed roller 4 is disposed above a front edge thereof. The front edge 7 of the paper feed table 1 is moved up and down by a cam (not shown) (not shown) driven by gears 5 and 6 by a motor (not shown). Guide groove 8 in paper feed table 1
The movable side guide 9 which slides along is provided,
The front frame 2 is a fixed side guide.
1. A roller shaft 1 mounted on the tip of a support lever 12 which can freely swing around a fulcrum shaft 11 shown more clearly in FIG.
The driven gear 14 is fixed to the front end of the roller shaft 13. The driven gear 14 is connected to the fulcrum shaft 11 via an intermediate gear 15 that is supported by the support lever 12.
The transmission gear 16 is supported by the transmission gear 16. Transmission gear 16
Is driven clockwise by a motor (not shown) to rotate the paper feed roller 4 in the paper feed direction clockwise in the figure. FIG.
In the apparatus shown in (1), six paper feed rollers 4 are fixed to the roller shaft 13, and the front edge of the paper feed table facing each paper feed roller is provided to alleviate the one-side contact of the paper feed roller 4. Recess 17 or a leaf spring 18 is provided. The leaf spring 18 is formed integrally with the paper feed table 1.

The pad shaft 21, the pad base 22, the separation pad 23, the sensor lever 24, the first spring 25, and the paper feed position sensor 26 are configured similarly to the conventional apparatus shown in FIG. The device according to the embodiment of the present invention does not include a member corresponding to the second spring 27 shown in the conventional example of FIG. Reference numeral 28 in FIG. 2 denotes a paper guide placed further on the sheet sending side of the separation pad 23 in FIG.

Next, the operation of the illustrated embodiment will be described with reference to the flowchart of FIG. When the sheet feeding is instructed, the sheet feeding table 1 rises, and the sheet 29 comes into contact with the sheet feeding roller 4 by this rise, and the sheet feeding roller 4 is moved up to a predetermined reference sheet feeding position. The reference paper feed position is detected by the paper feed position sensor 26 detecting the tip of the sensor lever 24. The controller that controls the elevation of the paper feed table 1 is as follows:
After receiving the detection signal of the sheet feeding position sensor 26, the sheet feeding table 1 is further raised by the set height α. The value of α is selected to be about 3 mm. Next, the controller gives a lowering command to the sheet feeding table 1 and simultaneously gives a rotation start command to the drive motor of the sheet feeding roller 4. That is, the sheet feeding operation is
It is started during the lowering operation of the sheet feeding table. The descending amount of the paper feed table 1 is set in advance in the controller as a value β. Usually, β may be set to α, but β may be smaller than α. When the paper feed table 1 is lowered by the set value β, the lowering operation of the paper feed table 1 is stopped, and the rotation of the paper feed roller 4 is continued.

When the sheets 29 stacked on the sheet feeding table 1 are thin paper, they are fed at an initial point in time when the sheet feeding table 1 starts to descend. When the sheet 29 is a thick sheet having a large sheet feeding resistance, the sheet 29 is fed when the sheet feeding table 1 stops and the sheet feeding table 1 stops.

[0023]

According to the method of the present invention described above,
It is possible to effectively prevent double feed of paper during automatic paper feed of stacked paper. In addition, the automatic sheet feeding apparatus of the present invention, which prevents double feeding of thin paper by the above method, does not require a member such as a second spring for changing the pressing force of the sheet feeding roller against the sheet in two steps, and does not require such a member. In addition to eliminating the need for power adjustment work, the cost of the apparatus can be reduced. In addition, a space for allowing the roller provided above the paper feed roller to rise can be small, and the installation space for the paper feed device can be reduced. Furthermore, since the operation of waiting for the detection of the fed sheet and raising the sheet feeding table again becomes unnecessary, the throughput of the sheet is improved. Further, since only one spring for adjusting the pressing force of the paper feed roller can be provided, there is an effect that the work load at the time of assembling the apparatus is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a main part of an embodiment apparatus.

FIG. 2 is an overall perspective view of the apparatus according to the embodiment.

FIG. 3 is a flowchart showing an operation of the embodiment apparatus.

FIG. 4 is a schematic explanatory view showing an action of preventing double feed.

FIG. 5 is a schematic perspective view showing a main part of a conventional similar device.

6 is a flowchart showing a sheet feeding operation of the apparatus of FIG.

[Description of Signs] 1 paper feed table 4 paper feed roller 11 fulcrum shaft 12 support lever 16 transmission gear 25 first spring 29 paper

Claims (5)

(57) [Claims] An automatic sheet feeding method for pressing and rotating a sheet feeding roller (4) against a sheet surface of stacked sheets (29) and feeding the sheets (29) one by one by its frictional driving force. The automatic feeder is characterized in that once the stopped paper feed roller (4) is once pressed against the paper (29), the paper feed roller (4) is rotated to feed the paper while releasing the pressing force. Paper method. 2. A sheet (29) is stacked on a sheet feeding table (1), and the sheet (29) is brought into contact with a sheet feeding roller (4) by raising the sheet feeding table (1). In the paper feeding method of the automatic paper feeder, after raising the paper feed tray (1) to a level where the upper surface of the stacking paper (29) exceeds the reference paper feed position, lower the paper feed tray (1), An automatic sheet feeding method characterized by starting the rotation of the sheet feeding roller (4) at the same time as or immediately after the start of the lowering operation of the sheet feeding table (1). 3. A paper feed roller (4) is provided so as to be able to move up and down and to be urged downward by its own weight or a spring, and the paper of the paper feed roller (4) is moved when the paper feed roller (4) is moved upward. 3. The automatic sheet feeding method according to claim 2, further comprising a spring for increasing a pressure applied to the automatic sheet feeding apparatus. 4. A paper feed roller for pressing and rotating against the paper surface of the stacked paper (29) and feeding the paper one by one by friction driving force.
In the automatic paper feeder provided with (4), the paper feed roller (4) is supported by a freely movable member (12), and the rotational drive system of the paper feed roller (4) has a driving tangential force. The paper feed roller
(4) is arranged to act in the direction of pressing against the paper (29), and stack paper (29) is fed at the time of paper feeding.
An automatic paper feeder, which once presses and contacts the paper feed roller and rotates the paper feed roller (4) while releasing the pressing force. 5. A paper feed table (1) driven up and down and a fulcrum shaft (11).
The paper feed roller (4), which is pivotally supported at the tip of a support lever (12) that can freely swing around, and the rotational drive force is transmitted to the paper feed roller (4), which is pivotally supported by a fulcrum shaft (11). A transmission element (16) is provided.When the transmission element (16) rotates in the direction of lowering the support lever (12), the paper feed roller (4) rotates in the paper feeding direction, and the paper feed table (1) After ascending beyond the reference paper feed position,
An automatic paper feeder characterized by lowering to a reference paper feed position and starting to rotate at the same time as or immediately after the start timing of the lowering operation.