JPH04129931A - Sheet material feeding device - Google Patents

Abstract

PURPOSE:To supply sheet material securely by arranging a spring pressure regulating means which increases pressing contact force by means of a pushing-up spring when a space between a feed roller and a separating roller becomes wide, and decreases the pressing contact force when the space becomes narrow. CONSTITUTION:When a thin sheet is fed subsequent to the feed of a thick sheet a separating roller 5 is elevated allowing a height regulating member (a spring pressure regulating means) 9 to turn counterclockwise around a rotational center 9a and a spring mounted table 8 to be lowered. This reduces the spring pressure to push up the sheet mounted table 1 by means of a pushing up spring 3. Thus, the force to be pushingly applied to a feeding roller 2 for the sheet S is reduced, and the feeding force by the feeding roller 2 is suppressed to be small when a thin sheet is fed, preventing double feed even when a roller space between a feeding roller 4 and the separating roller 5 becomes larger to some extent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet material feeding device used in, for example, an electrophotographic copying machine, a laser beam printer, a paper feeding section of a printing machine, and the like.

(Prior Art) Conventionally, as this type of sheet 1 to material feeding device, one shown in FIG. 3, for example, is known. That is, ], O
] is a sheet mounting table on which the sheet material S is placed, and a feeding roller 102 serving as sheet material feeding means is disposed above the table. The sheet mounting table 101 is pressed against the feeding roller 102 by a pusher spring 103. If a driving force is applied to the feed roller 102 here, the feed roller 102
rotates in the direction of the arrow, and the sheet material 8 is fed in the six directions of the arrow by the frictional force of the contact surface of the feeding roller 102.

Further, in the feeding direction of the sheet material S, a feed roller 104 is disposed downstream of the feed roller 102, and below the feed roller 104, a feed roller 104 is disposed opposite to the feed roller 04. It is the separation roller 105 that is shown. This separation roller 105 is configured to rotate in the opposite direction to the feed roller 104 and feed roller 102. and,
As shown in FIG. 4, the separating roller 105 and the feeding roller 104 have partially alternated surfaces, and depending on the thickness and stiffness of the sheet to be fed, the separating roller 105
The separation roller 105 is movable in the vertical direction so that the distance between the feed roller 104 and the feed roller 104 can be adjusted.

In the conventional device as described above, when only one sheet material is fed by the feed roller 102, the feed roller has a larger friction force than the downstream reversing roller 105]04
The sheet material S is sent further downstream.

On the other hand, when two or more sheet materials are fed by the feeding roller 102, only the sheet material on the most two sides is fed by the feeding roller 10.
4, and the second and subsequent sheets are pushed back backward by a separation roller 105 and are not fed.

(Problem to be solved by the invention) However, in such conventional technology, the distance between the feed roller 104 and the separation roller 105 is adjusted in consideration of the thickness and stiffness of the sheet to be fed. are doing.

Here, in order to feed a thin sheet material, when trying to feed a thick and stiff sheet material with the distance between the two rollers narrowed, the frictional force between the feeding roller 102 and the sheet material The resistance force when the leading edge of the sheet material enters the nip between the roller pair 104 and 105 is greater than the sheet material feeding force generated by the feeding roller 102.
This causes slippage between the material and the sheet material, making feeding impossible. Here, the stronger the pressing force of the push-up spring 103 pushing up the sheet mounting table 101, the more the feed roller 101
Since the sheet material and the feed roller 102 are in strong contact with each other, the frictional force between the feed roller 102 and the sheet material is increased, and even if the distance between the rollers becomes narrow, slipping between the feed roller 102 and the sheet material will not occur (the sheet material In other words, conventionally, the spring pressure of the push-up spring 103 is such that even when the distance between the rollers is narrowed to some extent, the feeding force applied to the sheet material by the feeding roller 102 is vs. 104,
The force is set to be strong to some extent so as to exceed the resistance force when the sheet enters the nip section 105.

However, when the sheet material is strongly pressed against the feeding roller 102 as described above, the frictional force between the sheet materials also increases. In this state, when trying to feed a thin sheet material, when it enters the nip between the roller pair 104 and 105, due to the stiffness of the sheets 1 to 105, the roller pair 104 (not shown in FIG. 4) The amount of deflection caused by the sheet material following the alternating shape of .105 becomes extremely large compared to when the material is conveyed to the thick sheet 1. Therefore, roller pair 104
, 105, the resistance when the sheet material enters the nip portion is small. In addition to this, the increased frictional force between the sheet materials makes double feeding of sheet materials more likely to occur.

Therefore, when trying to feed thin sheets without double feeding while the push-up spring 103 is strong, there is a problem in that the distance between the rollers must be made extremely narrow.

In addition, by feeding the sheet material with a narrow roller interval, when the sheet material enters the nip between the pair of rollers 104 and 105 during feeding, the amount of deflection of the material toward the sea 1 increases, and the sound of the deflection of the sheet material is reduced. Occur.

Furthermore, there is a problem in that the sheet material is often wrinkled or torn.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to prevent the separation roller from moving up and down depending on the thickness of the sheet material being fed. An object of the present invention is to provide a sheet material feeding device that reliably feeds sheet materials and does not cause double feeding by providing a spring pressure adjusting means for appropriately changing the pressure contact force of a feeding roller.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides Sea 1
- A sheet mounting table on which the material is placed, a feeding roller that feeds the sheet material on the sheet mounting table in a fixed direction, and a pushing up of the sheet mounting table to press the sheet material against the feeding roller. A sheet material feeder having a push-up spring, a feed roller which is disposed downstream of the feed roller in item 1 and further conveys the sheet material, and a separation roller which is disposed opposite to the feed roller and rotates in the opposite direction. The apparatus is characterized in that a spring pressure adjusting means is provided that increases the pressing force of the push-up spring when the distance between the feed roller and the separation roller becomes wide, and weakens it when the distance becomes narrow. The spring pressure adjustment means can be configured as a height adjustment member that changes the height of the bottom of the pressure spring in response to the vertical movement of the separation roller. The spring pressure adjusting means includes a separation roller height displacement detecting means, a control means for receiving a signal from the displacement detecting means, calculating a necessary spring pressure, and controlling the amount of movement of the pressing spring, and the control means. It may be configured by a height adjusting means that moves the pressing spring in response to a signal from the height adjusting means.

(For I) Since the pressure contact force of the feed roller changes appropriately in accordance with the thickness of the sheet material supplied from the sheet loading table, the sheet material will reliably enter the feed roller. . At this time, there is no problem such as double feeding of sheet materials.

(Example) The present invention will be explained below based on the illustrated example. 1st
The figure shows a sheet material supply device according to a first embodiment of the present invention. The basic configuration of this device is the same as the conventional device shown in FIG. 3, but to briefly explain, S is the sheet material to be fed, and 1 is the sheet material on which the sheet material is placed!・It is a mounting table. 2 is a feeding roller for feeding the material S to the sea 1, 3
4 is a push-up spring for pushing the sheet loading table 1 and pressing the sheet material S against the feeding roller 2; 4 is a feeding roller for feeding the sheet material S into the device; 5 is a double feeding device for the sheet material S. 6 is a guide plate, and 7 is a separation roller support plate, which is movable in the vertical direction so that the distance between the rollers and the feed roller 4 can be adjusted depending on the thickness of the sheet material S. There is. 8 is a spring mounting table on which the push-up spring 3 is mounted.

Further, in the sheet material feeding device according to the present invention, the pressing force of the push-up spring 3 is strengthened when the distance between the feed roller 4 and the separation roller 5 becomes wider, that is, when the separation roller 5 moves downward. On the other hand, when the distance between the feed roller 4 and the separation roller 5 becomes narrower, that is, when the separation roller 5 moves upward, a spring pressure adjustment means is provided that reduces the pressing force of the push-up spring 3. The spring pressure adjusting means is configured as a height adjusting member 9 in the apparatus of the first embodiment. As clearly shown in FIG. 1, it is formed in a cross-shaped shape and can rotate in both directions around the support portion 9a.

In the apparatus of this embodiment having the above configuration, the sheet mounting table 1
The sheet material S stacked on top is pressed against the feeding roller 2 because the pressing spring 3 pushes the sheet mounting table 1 upward. If the feeding start switch (not shown) is pressed, the feeding roller 2 will start rotating in the direction of the arrow and the uppermost sheets 1 to 3 of the materials
Start feeding it to the right on the drawing. The fed sheet material S enters the nip between the feed roller 4 and the separation roller 5, but the feed roller 4 has lower rubber hardness and greater frictional force with the sheet material S than the separation roller 5, which is rotating in reverse. Therefore, when only one sheet material S enters the nip portion, the sheet material S is fed as the feed roller 4 rotates.

In addition, if two or more sheets 1 to 3 enter the nip part, the sheets 3 and 3 other than the top one are separated by the separation roller 5.
Because it is pushed back by the paper, it is not fed, and in the end, only the topmost sheet is fed. The uppermost sheet material S sent out by the sending roller 4 is sent further forward along the guide plate 6.

Here, in the conventional device, the distance between the feed roller and the separation roller is adjusted in advance according to the thickness and stiffness depending on the type of sheet material to be fed, but in this embodiment In this case, the separation roller is raised upward to reduce the distance between the rollers, so the height adjustment member 9 rotates counterclockwise around the rotation center 9a, and the spring mounting base 8 is lowered to lower the push-up spring. The spring pressure for pushing up the sheet mounting table 1 of No. 3 is reduced. Therefore, when feeding a thin sheet material after feeding a thick sheet material,
When the separating roller 55 is raised upward, the spring pressure of the push-up spring 3 is reduced, so that the force with which the sheet material S is pressed against the feeding roller 2 is reduced. Therefore, when feeding thin sheet materials,
Since the feeding force by the feeding roller 2 is kept low, even if the distance between the feed roller 4 and the separation roller 5 is increased to some extent compared to the conventional method, feeding can be performed without double feeding.

On the other hand, when feeding a thick sheet 1~ material after feeding a thin sheet material, the separation roller 5 is lowered to widen the roller interval. 1 becomes stronger, and the sheet material is strongly pressed against the feeding roller 2, so that the sheet material is smoothly fed without slipping between the feeding roller 2 and the sheet material.

FIG. 2 shows a second embodiment of the invention. However, the same components as those in the first embodiment described above are given the same reference numerals and redundant explanations will be omitted.

The second embodiment shows a device that applies an electrical method to the device of the first embodiment, which mechanically constitutes the adjustment means for the push-up spring 3.

In Fig. 2, there is a hole at the bottom of the separation roller support plate
What is hidden is the height displacement detection means IO. Reference numeral 11 denotes a height adjusting means such as a servo motor connected to the mounting base 8 of the pressing spring. Control means 12 receives the signal from the height displacement detection means 10, converts the displacement of the separation roller 5 into the amount of movement of the spring mounting table 8, calculates the displacement, and inputs the converted output to the height adjustment means. It is.

Even in the present embodiment device having the above configuration, the height adjusting means 1
1 can be interlocked with the vertical movement of the separation roller 5, and the sheet material can be reliably fed as in the first embodiment.

(Effects of the Invention) The present invention has the above configuration and operation, and when the separation roller moves up and down depending on the thickness of the sheet material being fed, the pressure contact force of the feeding roller is adjusted in conjunction with this movement. By installing a spring pressure adjusting means that changes the pressure appropriately, sheet material feeding is possible without causing inconveniences such as poor feeding or double feeding even when thick and thin sheet materials are fed continuously. Can be supplied as a device.

In addition, there is no need to make the distance between the feed roller and separation roller extremely narrow, so there is no risk of wrinkles or tears in the sheet material.
There is no bending sound.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of a sheet material feeding device according to a first embodiment of the present invention, FIG. 2 is a diagram showing the entire configuration of a sheet material feeding device according to the second embodiment, and FIG. FIG. 4, which is a diagram showing the conventional device, is a diagram showing the relationship between the feed roller and the separation roller. Explanation of symbols S... Sheet material 1... Sheet mounting table 2.
...Feed roller 3...Push-up spring 4...Feed roller 5...Separation roller 9...Spring pressure adjustment means (height adjustment member) 10.11.12...Spring pressure adjustment means ( 10... Height displacement detection means, 11... Height adjustment means 12... Control means) Figure Height adjustment member Figure Figure Figure

Claims (3)

[Claims] (1) A sheet loading table on which the sheet material is placed, a feeding roller that feeds the sheet material on the sheet loading table in a fixed direction, and a sheet loading table for pressing the sheet material against the feeding roller. A sheet material feeder having a push-up spring that pushes up a placing table, a feed roller that is disposed downstream of the feed roller and further conveys the sheet material, and a separation roller that is disposed opposite to the feed roller and rotates in the opposite direction. A sheet material characterized in that the feeding device is provided with a spring pressure adjusting means that increases the pressing force by the push-up spring when the distance between the feed roller and the separation roller becomes wide, and weakens it when the distance becomes narrow. Feeding device. (2) The sheet material conveyance according to claim (1), wherein the spring pressure adjustment means is a height adjustment member that changes the height of the bottom of the pressure spring in response to the vertical movement of the separation roller. Device. (3) The spring pressure adjusting means includes a separation roller height displacement detecting means, a control means receiving a signal from the displacement detecting means, calculating a necessary spring pressure, and controlling the amount of movement of the pressing spring; The sheet material feeding device according to claim 1, further comprising a height adjusting means that moves the pressure spring in response to a signal from the means.