JPH0329704B2 - - Google Patents

Description

[Detailed Description of the Invention] -Field of Industrial Application- This invention is applicable to copiers, computer printers,
Or it relates to a device that automatically supplies slip paper to a facsimile device, image reader, etc.
More specifically, an automatic paper feeder is provided with a structure that separates the paper by passing the paper between a paper feed roller that contacts the top surface of the stacked paper and feeds it, and a friction pad that is pressed by the paper feed roller. The present invention relates to a support structure for a paper feed roller in the present invention.

-Prior Art- There are various structures of automatic paper feeding devices installed in computer printers, image readers, etc., but as shown in FIG. The paper 2 is passed between a paper feed roller 3 that contacts the upper surface and applies a frictional feeding force thereto, and a friction pad 4 that is pressed by the paper feed roller 3 to separate and feed the paper into individual sheets. Those with a structure are used.

FIG. 2 shows an example of an automatic paper feeder of a printer, in which a pulse motor 5 is used to feed a paper tray 1
The upper surface of the sheet tray 1 is detected by a limit switch 6 so that the upper surface of the sheet 2 is always held at a predetermined sheet feeding position. And the paper feed roller 3 is connected to the branch pin 7.
It is pivoted to the tip of a support arm 8 that can be freely rotated around, and is movable up and down, and is brought into contact with the upper surface of the paper 2 by its own weight or by a suitable spring.

In FIG. 2, 11 is a bracket that supports the friction pad 4, 12 is a support pin of the bracket 11,
13 is a coil spring that urges the bracket 11 toward the paper feed roller 3; 14 is a rack fixed to the paper table 1; 15 is a pinion driven by the pulse motor 5; the pinion 15 meshes with the rack 14; ing. 16 is a front edge guide for the paper 2, 17 is a manual feed tray, 18 and 19 are guide plates, 20 is a platen, 21 is a print head, 22 is a printing section formed between these, and 23 and 24 are paper feeders. It's Laura.

Some automatic paper feeding devices have a structure in which the paper tray 1 is urged upward by a spring to press the top surface of the paper 2 against the paper feeding roller 3 which is pivoted in a fixed position. In this structure, the pressing force between the paper feeding roller 3 and the paper 2 changes depending on the amount of paper 2 loaded, and the stability of paper feeding and paper separation operations decreases accordingly. Further, in an automatic paper feeder in which the paper table 1 is in a fixed position, the paper feeding position changes depending on the amount of paper 2, and the amount of paper 2 that can be loaded is limited.

As shown in FIG. 2, the paper table 1 is raised and lowered so that the upper surface of the paper 2 is held at a predetermined paper feeding position,
A structure in which a paper feed roller 3, which is attached to the upper surface of the paper held at a predetermined paper feed position so as to be able to move up and down, is pressed into contact with it by its own weight or a spring, allows the pressing force between the paper feed roller 3 and the paper 2 to be accurately controlled. , and the paper feeding position does not change, so the paper feeding operation is stable and a wider range of paper can be automatically fed.

As shown in FIG. 2, in an automatic paper feeder in which a friction pad 4 is pressed against the paper feed roller 3 that feeds the paper 2 to form a paper separation climate, the paper feed roller 3
Since it is necessary to bring the paper into contact with both the upper surface of the paper 2 and the friction pad 4, the friction pad 4 is pressed against the paper feed roller 3 while being oblique to the incoming paper. The paper 2 is deflected slightly upward at the contact portion between the paper feed roller 3 and the friction pad 4, and is sent out.

-Problems to be Solved by the Invention- Paper of various thicknesses are used in office processing sites depending on the purpose of use, and an automatic paper feeder is required to reliably feed paper of various thicknesses. In addition, a function that allows for smooth paper feeding is required. However, in a structure in which the paper 2 is separated by the paper feed roller 3 and the friction pad 4, when the paper is thick, the roller 3 and the paper 2 are separated.
It is necessary to increase the pressing force with the paper, and weaken it when using thin paper. However, it is troublesome to adjust the pressing force of the paper feed roller 3 according to the thickness of the paper, so in reality, an average pressing force is set to correspond to all the paper sheets. For this reason, even with an automatic paper feeder with the structure shown in Figure 2, there is a limit to the thickness of paper that can be reliably fed.
When using thin paper such as Kg reams or 55 Kg reams, two sheets of paper were fed at a rate of about 10 to 20 times/500 times, and thick paper could only be fed up to about 180 Kg reams.

This invention prevents the occurrence of two-sheet feeding when using the above-mentioned thin paper in an automatic paper feeder having a paper separation mechanism structured as shown in FIG. In other words, it is an object of the present invention to provide an automatic sheet feeding device that can more reliably and smoothly separate and feed sheets of a wider range of thicknesses.

-Means for Solving the Problem- This invention raises and lowers the paper table 1 so that the upper surface of the paper 2 is held at a predetermined paper feeding position, and the upper surface of the paper 2 held at the predetermined paper feeding position. A support arm 8 having a fulcrum on the paper feed side supports the paper feed roller 3 to be pressed against the paper feed roller 3 so as to be movable up and down.
This is aimed at an automatic paper feeder that has a structure in which the paper feed roller 3 is pressed against the paper 2 by its own weight or a spring. The above-mentioned problem has been solved, and the present invention is characterized by the provision of a stopper 30 that suppresses the upward movement of the paper feed roller 3, which is mounted so as to be vertically movable, to 1 mm or less.

-Function- As a result of observing the paper feeding operation in the conventional automatic paper feeding device in detail, it was found that in the conventional automatic paper feeding device, if the paper feeding roller 3 slips when feeding thick paper and the paper cannot be fed, Development in which the paper roller 3 moved upward was observed. This invention was made based on the idea that paper feeding failure during thick paper feeding could be avoided by suppressing the upward movement of the paper feed roller 3, which was observed through the above observation. It has been found that as a result of feeding paper by limiting the amount of upward movement of the paper feed roller 3 from the normal position to about 0.1 to 0.5 mm using No. 30, the inability to feed paper when feeding thick paper can be avoided. It has been found that thick paper can be fed even if the pressing force between the paper feed roller 3 and the paper 2 is set smaller than that of the conventional one. By setting the pressing force between the paper feed roller 3 and the paper 2 to be smaller than that of the conventional device, it was possible to avoid two-sheet feeding when thin paper was fed.

Although it is difficult to theoretically and strictly analyze the phenomenon in which the paper feed roller 3 moves upward when paper feeding becomes impossible during cardboard feeding, when the tip of the cardboard collides with the friction pad 4, it causes a large It is thought that this is because the reaction force acts on the peripheral surface of the paper feed roller 3 and causes the support arm 8 to rotate clockwise in the figure around the fulcrum pin 7. Since the coefficient of friction between the paper 2 and the paper 2 is generally greater than 1, it is thought that this overcomes the weight of the paper feed roller 3 or the pressing force of the spring and moves the paper feed roller 3 upward.

If the upward movement of the paper feed roller 3 is suppressed by the stopper 30, the force that tries to move the paper feed roller 3 upward will be received by the stopper 30, and the paper that is larger than the own weight or spring force of the paper feed roller 3 will be Since the reaction force in the tangential direction from 2 acts on the paper 2 as a pushing force, the pushing force of the paper feed roller 3 that actually acts on the paper 2 increases against thick paper, and as a result, the friction pad The larger the load resistance acting from 4, that is, the thicker the paper, the stronger the paper feed roller 3 will be pressed against the paper 2.
It is thought that the inability to feed paper due to slipping of the paper feed roller 3 can be avoided.

-Example- Figure 1 shows an example of this invention.
The stopper 30 is configured by having the tip of a stopper screw 33 screwed into a bracket 32 extending from a stationary member 31 facing above the support arm 8 that pivotally supports the paper feed roller 3. Reference numeral 34 indicates the setting of the stopper screw 33. This is a lock nut to prevent positional changes. As mentioned above, the upper surface of the paper 2 is maintained at a predetermined paper feeding position by raising and lowering the paper tray 1. Therefore, although the paper feeding roller 3 is supported so as to be able to move upward, it is always kept at a constant position. in its normal position. The stopper screw 30 is provided at a position that prevents the paper feed roller 3 from moving upward by 1 mm or more from the normal position by abutting the tip of the stopper screw 30 with the support arm 8.

Reference numeral 25, which is only shown in FIG. 1, is a plastic plate spring provided to further urge the rear end of the friction pad 4 toward the paper feed roller 3.

-Effects of the Invention- According to the configuration of the present invention described above, it is possible to avoid paper feeding failure due to slipping of the paper feed roller when feeding thick paper, and to reduce the set value of the pressing force between the paper feed roller and the paper compared to the conventional one. It became possible to feed cardboard by making it smaller than the device. By being able to set the pressing force between the paper feed roller and the paper to a small value, it is possible to avoid as much as possible the double sheet feeding that occurs when feeding thin paper. This has the effect of providing an automatic paper feeder that can separate sheets more reliably and feed them smoothly.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a side view of essential parts, and FIG. 2 is a side view schematically showing a printer employing the automatic paper feeding device of the present invention. In the figure, 1: paper table, 2: paper, 3: paper feed roller, 4: friction pad, 5: pulse motor, 6: limit switch, 7: fulcrum pin, 8: support arm, 14: rack, 15: pinion, 30: Stoppa.

Claims (1)

[Scope of Claims] 1. While maintaining the top surface of the sheets stacked on the paper table at a predetermined paper feeding position, the paper is fed by a paper feed roller that is pressed against the top surface, and the fed paper is fed. It has a structure in which the paper is passed between a paper roller and a friction pad pressed against it to separate the paper into individual sheets, and the paper feed roller is vertically movable by a support arm having a fulcrum on the paper feeding side. In an automatic paper feeder that is mounted and pressed against the top surface of the paper by its own weight or a spring, a stopper whose position can be adjusted freely to regulate the upward movement position of the paper feed roller is provided, and the distance between the stopper and the stopper is 1 mm.
A support structure for a paper feed roller in an automatic paper feeder, characterized in that the paper feed roller is in contact with the upper surface of the paper at the predetermined paper feed position with the following gap remaining.