Patent Application
20090256306
1. Field of the Invention
This present invention relates to a paper feeding device, and more particularly to a paper feeding device preferably applicable to an office device such as a printer, a copier and a scanner.
2. The Related Art
A conventional paper feeding device is generally used in various office devices such as a printer, a copier, a scanner and the like, it is highly desirable to feed single paper sheet from a stack of paper sheets placed at a paper feeding plate. There are many known prior paper feeding devices for single sheet feeding of paper.
A particular paper feeding device is disclosed in U.S. Pat. No. 5,573,338. In accordance with this patent, the paper feeding device includes a pick roller, a first spring element, a second spring element, a separator pad and a gate. The first spring element and the second spring element are disposed to contact with the pick roller at different positions in the conveying direction of the paper. The gate is provided between the first spring element and the second spring element to suppress the feed of papers. The separator pad is disposed to contact with the pick roller at the downstream side of the second spring element. In operation, the lowermost paper is in contact with the pick roller due to its own weight. As the pick roller rotates, plural pieces of papers will enter between the first spring element and the pick roller. Due to the action of the gate, the lowermost paper and several pieces of papers enter between the second spring element and the pick roller. And then only the lowermost paper can pass through the pick roller and the separator pad.
However, during the process of the paper feeding, the first spring element always presses on the pick roller, so the pick roller is prone to be abraded as the first spring element rubs it too much. In addition, the first spring element presses on the pick roller before the paper feeding device conveying papers to provide a prior press acting on the pick roller. The single paper needs a large enough push force to push the first spring element to insert between the first spring element and the pick roller, so when the push force acting on the single paper is not large enough, the paper feeding of single paper will be false.
Accordingly, an object of the invention is to provide a paper feeding device to reduce the abrasion of a pick roller and enhance the reliability of single paper feeding.
To achieve the object, the paper feeding device includes a pick roller, a spring element and a separator pad. The pick roller has a roller surface. The spring element is disposed above the pick roller. The spring element has two spring arms extending toward two ends of the pick roller. Free ends of the two spring arms extend to position outside the two ends of the pick roller and below the roller surface so as to be contactless with the roller surface and are pushed forward and upward by papers and then transfer a press force to the pick roller. The separator pad is arranged in front of the spring element and contacts with the roller surface of the pick roller for cooperating with the pick roller to separate a lowermost one of the papers.
According to another aspect of the present invention, the paper feeding device is provided to the present invention which also includes a pick roller, a spring element and a separator pad. The pick roller has a roller surface, and at least one annular gap is defined around the roller surface. The spring element is disposed above the pick roller. The spring element has at least one spring arm extending toward the pick roller, a free end of the spring arm extends into the annular gap so as to be contactless with the roller surface and lies below the roller surface for being pushed forward and upward by papers and then transferring a press force to the pick roller by papers. The separator pad is arranged in front of the spring element and contacts with the roller surface of the pick roller for cooperating with the pick roller to separate a lowermost one of the papers.
As described above, because the spring arm does not contact with the pick roller directly, the spring arm does not rub the pick roller, so the present invention can avoid the pick roller being abraded. Otherwise, no prior press acts on the spring arm, the paper is much easy to push the spring arm to enter between the spring arm and the pick roller, so the present invention enhances the reliability of single paper feeding.
The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which:
Referring
The bracket 300 placed above the pick roller 100 has a support board 310. A plurality of location pegs 311 vertically projects forward from proper places of the support board 310. The bottom of the support board 310 extends and inclines rearward to form a prop board 320. Two ends of the support board 310 extend upward and downward to form two fixing portions 330 which are fixed on the upper frame 200.
The spring element 400 stamped from a metallic sheet has a holding portion 410. A plurality of first location holes 411 are opened in the holder portion 410 for mating with the location pegs 311 to fix the holder portion 410 on the support board 310 of the bracket 300. Two spring arms 420 extend from two ends of the top of the holding portion 410. The two spring arms 420 are respectively disposed outside two ends of the pick roller 100 in the axial direction of the pick roller 100. Each spring arm 420 has a clip portion 421 which extends and then bends downward and rearward from the top of the holding portion 410. The clip portion 421 clips the top of the support board 310. A free end of the clip portion 421 extends to form a spring portion 422 with a hooked tip bent forward. Free ends of the two spring portions 422 extend to positions outside the two ends of the pick roller 100 and are below the roller surface 110 so as to be contactless with the roller surface 110. The distance between the two spring arms 420 is larger than the length of the pick roller 100.
The press pad 500 has a pad holder 510 and a press portion 520 extending and inclining rearward from the bottom of the pad holder 510. The press portion 520 is placed in front of the spring arms 420 and against the front of the prop board 320 of the bracket 30. A plurality of second location holes 511 are opened in the pad holder 510 for mating with the location pegs 311 to fix the pad holder 510 on the support board 310 of the bracket 300. The tip of the press portion 520 is beyond the prop board 320 and faces the roller surface 110 of the pick roller 100. A small gap is formed between the tip of the press portion 520 and the pick roller 100.
The separator pad 600 is placed in front of the press pad 500. The friction coefficient of the separator pad 600 is larger than that of the papers and smaller than that of the pick roller 100. The separator pad 600 has a basic portion 610. A plurality of third location holes 611 are defined in the basic portion 610 for mating with the location pegs 311 to fix the basic portion 610 on the support board 310 of the bracket 300. A connect portion 620 extends and bends rearward from the tip of the basic portion 610. A separator portion 630 extends and bends forward from the tip of the connect portion 620 and contacts the roller surface 110 of the pick roller 100.
The restoration unit 700 includes a main body 710 and a spring 720. The main body has a base 711. A retaining rod 712 protrudes forward from the base 711. Two connecting rods 713 extend from two sides of the top of the base 711, and two pivots 714 respectively protrude outward from the two connecting rods 713 which are fixed on the upper frame 200. One end of the spring 720 surrounds the retaining rod 712 and resists on the base 711, and the other end of the spring 720 resists on the upper frame 200.
In
The lowermost paper and several pieces of the papers thereon move to the separator portion 630 of the separator pad 600. The press portion 520 of the press pad 500 presses the papers to prevent them from curling. As the friction coefficient of the separator pad 600 is larger than that of the papers but smaller than that of the pick roller 100, the papers on the lowermost paper are prevented from entering to the position where the separator portion 630 is in contact, and only the lowermost paper passes through between the pick roller 100 and the separator portion 630. The paper entering into between the pick roller 100 and the separator portion 630 pushes the separator portion 630 upward, and at the same time the separator portion 630 pushes against the base 711 of the main body 710 of the restoration unit 700. The base 711 rotates upward around the pivots 714, and the base 711 pushes against the spring 720 to be compressed. After the paper is fed completely, the compressed spring 720 is released to press the base 711 to move downward, the base 711 further pushes the separator portion 630 to contact the pick roller 100 again for a next paper feeding.
According to the paper feeding device of the present invention as described above, the free ends of the spring portions 422 are below the roller surface 110 of the pick roller 100, the spring arms 420 plays a role of feeding the papers firstly. Because the spring arms 420 are not in direct contact with the pick roller 100, the spring arms 420 do not abrade the pick roller 100, so the present invention avoids the pick roller 100 being abraded. Furthermore there is no a prior press acting on the spring arms 420, the paper is much easier to push the spring arms 420 for entering into between the spring arms 420 and the pick roller 100 when feeding single paper even the paper has a small thickness. So the present invention can enhance the reliability of single paper feeding.
In this embodiment, the paper entering into between the pick roller 100 and the separator portion 630 pushes the separator portion 630 upward, and at the same time the separator portion 630 pushes against the base 711′ of the main body 710′ of the restoration unit 700, the main body 710′ moves upward with the separator portion 630. As the contact portion 620 presses on the main body 710′ and the retaining arms 743 are fixed on the upper frame 200 and the axial holes 716′ of the main body 710′ respectively, so the torsion spring 740 will be distortion. After the paper is fed completely, the torsion spring 740 is released to press the main body 710′ downward, and the main body 710′ further pushes the separator portion 630 to contact the pick roller 100 again for a next paper feeding. As the torsion spring 740 is arranged transversely, which reduces the lengthways space and furthermore reduces the bulk of the paper feeding device 10.
Embodiments of the present invention have been discussed in detail. However, the embodiments are merely specific examples for clarifying the technical contents of the present invention and the present invention is not to be construed in a restricted sense as limited to the specific examples. Such modifications and variations that may be apparent to those skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.
