JPS5939636A - Paper feed device - Google Patents

Abstract

PURPOSE:To prevent a paper feed miss and a duplicate feed by providing a variable-contact pressure means making the contact pressure of a separation means variable based on a null-paper signal from a paper transport sensor in a device separating and feeding the paper by a joint operation of a feed means and a separation means. CONSTITUTION:Sheets of paper on the paper feed bed 1 of a paper feed device are separated one by one and fed to a transport path 12 side by a feed roller 2 rotated with a motor 6 through a belt 7 and a separation means 3 comprised of a pad 5 in contact with said roller 2 by friction and a support plate 5 protecting it from outside. In this paper feed device, the separation means 3 is connected to a variable-contact pressure roller 8 connected to a reversible motor 9 through a belt 10. When no paper is detected at necessary timing for paper arrival in a transport paper sensor 15, the motor 9 is controlled to rotate in the positive direction to increase the contact pressure of the separation means 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper feeding device used in copying machines, facsimile machines, printing machines, etc., and more particularly, the present invention relates to a paper feeding device used in copying machines, facsimile machines, printing machines, etc. The present invention relates to a type of paper feeding device that separates sheets one by one and conveys them downstream.

The paper feeding device referred to herein includes both a transfer paper feeding device and a document feeding device.

Conventionally, in this type of paper feeding device, the contact pressure between the separating means and the feeding means (hereinafter referred to as the contact pressure of the separating means) was constant, so it cannot always be said that the contact pressure is appropriate for papers of different thicknesses. It was difficult. In other words, it was difficult to say that the contact pressure was appropriate for reliably separating and transporting sheets of paper one by one.

In other words, if the contact pressure is designed for thick paper, there is a risk of double feeding or non-feeding when thin paper is used.

However, it is known that the contact pressure of the separating means is changed depending on the position of contact with the feeding means.

However, even with such a device, the width of the paper used may not reach the appropriate contact pressure position, and the contact pressure range is also limited, so the usable paper range is ultimately narrowed and the function cannot be fully utilized. It was impossible. Another disadvantage is that there are many adjustments to be made in the manufacturing process.

The present invention was made in view of the above-mentioned drawbacks of the conventional examples, and its purpose is to always apply appropriate contact pressure to paper of a wide range of thickness, thereby ensuring reliable single-sheet feeding. Our goal is to provide a paper feeding device that can.

For this purpose, when the conveyed paper sensor installed downstream of the feeding means does not detect the paper at the required timing from the start of the paper feeding operation to when the paper arrives, the separating means uses the paper out signal from the conveyed paper sensor. The contact pressure is controlled to increase from the fully initialized state.

The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows a paper feeding device according to an embodiment of the present invention. A simplified side view.

In FIG. G, numeral 1 is a paper feed tray, and stacked papers are accommodated on this paper feed tray 1. The paper feed tray 1 has a downward slope on the downstream side (paper feed side), and a feed roller (feeding means) 2 is provided at the tip of the tray. This is the model that will be sent out. A separation member (separation means) 3 is in contact with the feed roller 2 from above, the contact portion of which has a full arc that coincides with the feed roller 2. This separation member 3 is made up of a knot 4 which is in direct frictional contact with the feed roller, and a support plate 5 which holds this pad 4 from the outside. The feed roller 2 is connected to a drive motor 6 by a belt 7, and is rotated by the drive motor 6 in a direction in which the paper is sent out, that is, in a counterclockwise direction. Further, the separation member 3 is connected to a variable contact pressure roller (contact pressure variable means) 8, and this variable contact pressure roller 8 is connected by a belt 10 to a drive motor 9 capable of forward and reverse rotation. As is clear from the figure, if the drive motor 9 is rotated counterclockwise (this is referred to as forward rotation), the separation member 3 will be strongly pressed against the feed roller 2.
The contact pressure of the separation member 3 will increase. Conversely, if the drive motor 9 is rotated clockwise (this is called reverse rotation),
The contact pressure of the separation member 3 will be initialized. 11 is a stacked paper sensor that detects stacked papers. The paper whose double feeding is prevented by the separation member 3 is conveyed one by one into the paper conveyance path 12, and is further conveyed by a plurality of conveyance roller pairs 1 provided on the downstream side.
3 and 14. A transmission type conveyed paper sensor 15 is provided in the conveyance path 12 and near the feed roller 2.

FIG. 2 shows the output signal from the conveyed paper sensor 15.

It is an explanatory diagram showing the relationship with each drive motor 6.9.

In the figure, 16 is a control circuit, 17 is a feed roller drive circuit, and 18 is a separating member drive circuit.

Further, a is a feed roller drive signal outputted from the control circuit 16, and b is a paper detection signal from the conveyed paper/sensor 15, which is taken into the control circuit 16. Further C
is a separation member drive signal output from the control circuit 16.

FIG. 3 is a timing chart of each of these signals a + b He.

That is, the feed roller 2 starts rotating via the drive motor 6 at the timing when the feed roller drive signal a rises to S level.
After the start of rotation, the paper will reach the conveyed paper sensor 15 position after a period of time, and the paper detection signal should rise. However, as shown in the timing chart of FIG. 3, when the C output does not rise after t time from the rise of the C output, the separation member drive signal C is outputted from the control circuit 16 as a pulse Pi as shown in the figure. .

Therefore, the drive motor 9 is rotated forward by the pulse PI of this C output, and the contact pressure of the separating member 3 is increased via the variable contact pressure roller 8.

When the contact pressure of the separation member 3 increases, the frictional force between the feed roller 2 and the lowermost paper increases, so that the paper can be reliably fed out into the paper conveyance path 12 one by one. If the contact pressure of the separation member 3 is still insufficient even after controlling the rotation angle of the variable contact pressure roller 8 - times, the rotation angle Ps+pPa'(
r is output similarly, and the rotation angle of the variable contact pressure roller 8 is controlled so as to increase the contact pressure of the separation member 3 in stages.

In this way, when the bottom paper is detected by the conveyed paper sensor 15, the paper detection signal becomes high level, and based on this C output, control is performed in the control circuit 16 to turn off the C output. .

Therefore, in other words, the 7'P pulse P1+P2+P3 of the clLI force is output based on the paper out signal which is the low level b output.

FIG. 2 is a simplified side view of main parts showing another embodiment.

In the figure, 19 is a controller that controls the electromagnet 20. This electromagnet 20 is made of a metal support plate 5
and are facing each other with a minute interval 'fi-:a'.

As in the first embodiment, the separation part 3 is fully engaged with the variable contact pressure roller 8, but in this embodiment, it is urged counterclockwise by the variable contact pressure roller 8. shall be taken as a thing. In the initialization state, the attraction force by the electromagnet 20 is strengthened to weaken the contact pressure of the molecule 'ff portion 3 against the biasing force in the counterclockwise direction.

The contact pressure of the separation member 3 is increased by sending a control signal similar to that in the first embodiment to the controller 19, suppressing the current flowing to the electromagnet 20, and thereby weakening the excitation force of the electromagnet.

As described above, the present invention is designed to control the contact variable means to increase the contact pressure of the separation means when the fed paper is not detected at a predetermined timing during the conveyance path, so that the contact pressure of the separation means is increased. It is possible to use a very wide variety of papers, and to provide a paper feeding surface that is almost free from paper feeding errors and double feeding.

[Brief explanation of the drawing]

FIG. 1 is a simplified side view of a paper feeding device according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing the relationship with the control mechanism, and FIG.
This figure is the same timing chart, and FIG. 4 is a simplified side view of the main part according to the second embodiment. DESCRIPTION OF SYMBOLS 1... Paper feed table, 2... Feeding means, 3... Separation means, 8... Contact pressure variable means, 15... Transport paper sensor.

Claims (1)

[Claims] A paper feed table and a stack of paper on the paper feed table are conveyed one by one. The feeding means that sends out during the route and the movement of this feeding means. In a device consisting of a separating means that makes frictional contact and a conveyed paper sensor installed downstream of the conveying means, a contact pressure n'' variable means is provided to vary the contact pressure of the separating means, and the paper arrival sensor at the conveyed paper sensor When paper is not detected at the required timing, the contact pressure variable means is fully controlled based on the paper out signal from the conveyed paper sensor, and the contact pressure of the initialized dividing means is increased. Paper feeding device.