Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-06-23
2002-07-02
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S098000, C271S030100, C271S171000
Reexamination Certificate
active
06412769
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a paper feeder mounted in an image-forming machine such as copier, facsimile or printer to feed a paper toward an image-forming unit.
DESCRIPTION OF THE PRIOR ART
The conventional image-forming machine is equipped with a paper feeder which takes out, piece by piece, papers stacked on a paper-feed tray starting from the uppermost one, and feeds it toward the image-forming unit. The paper feeder that is widely and practically used is of the type in which a feed roller is brought into contact with the paper at the uppermost position stacked on the paper-feed tray to feed the paper by frictional force. In the paper feeder of the type in which the feed roller is brought into contact with the paper to feed it, however, slipping occurs between the feed roller and the paper when the feed roller is worn out, thereby causing the paper to be contaminated. Furthermore, when the feed roller is worn out to a great extent, the paper is not fed smoothly. Therefore, a problem resides in the durability of the feed roller.
The paper feeder is further equipped with a paper separation means for separating the paper at the uppermost position from the second and subsequent papers stacked on the paper-feed tray. The paper separation means is generally of a pawl separation type, friction pad type or gate type. However, none of them is capable of reliably separating a paper from the subsequent papers, and there occurs often feeding of plural pieces of papers at one time in an overlapped manner or occurrence of clogging of paper.
In order to solve the problems of the paper feeder equipped with the above-mentioned feeder roller and the paper separation mechanism, Japanese Unexamined Patent Publication (Kokai) No. 107347/1994 (JP-A 6-107347) discloses a paper feeder of the air suction type. The paper feeder of the air suction type comprises a paper-stacking means for stacking the papers; a suction/feed means having a drive roller and a driven roller arranged above the paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between the drive roller and the driven roller and having a suction port in the bottom wall thereof, and a conveyer belt arranged being wrapped round the drive roller, driven roller and suction duct and having plural holes formed therein; and an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed, which includes an air duct equipped with plural floatation nozzles to jet out the air against an upper portion at the front end of the papers stacked on the paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of the suction/feed means. The air jetted out from the floatation nozzles is blown to the upper portion of the papers stacked on the paper-stacking means to float several pieces of upper papers. The paper at the uppermost position thus floated is sucked and conveyed by a feed belt of the suction/feed means. On the other hand, the thus floated papers other than the uppermost paper are separated from the uppermost paper by the air that is jetted out from the separation nozzles and enters between the uppermost paper and the second paper. In order to reliably separate one paper from the other, the air must be reliably introduced between the uppermost paper and the second and subsequent papers. For this purpose, according to the paper feeder disclosed in Japanese Unexamined Patent Publication (Kokai) No. 107347/1994, a protrusion is provided on the lower surface of the bottom wall of the suction duct to come into contact with the conveyer belt thereby to give a curve to the conveyer belt, so that the paper adsorbed by the conveyer belt is caused to have undulation. Consequently, the air can easily enters between the uppermost paper and the second paper.
The above paper-stacking means comprises a frame that is mounted to freely move between an acting position and a non-acting position drawn out from the acting position, and a paper-stacking plate mounted on the frame to freely move up and down. The frame is drawn out to the non-acting position, and plural papers are stacked on the paper-stacking plate as required. Then, the frame is returned back to the acting position so that the plural papers stacked on the paper-stacking plate are positioned as required with respect to the air-blowing means and the suction/feed means.
The paper feeder further includes a means for holding down the rear end of the papers and for detecting the height of the papers. The means for holding down the rear end of the papers and for detecting the height of the papers includes a support member, a pushing member mounted on the support member so as to move over a predetermined range in a direction toward the paper-stacking plate and in a direction to separate away therefrom, and a detector for detecting the position of the pushing member. The pushing member is pushed at its lower end to the uppermost paper of the plural papers on the paper-stacking plate to prevent the papers on the paper-stacking plate from moving backward by the air sent from the air-blowing means. Further, the position or height of the pushing member is detected by the detector to detect the height of the uppermost paper on the paper-stacking plate, that is pushed by the lower end of the pushing member. As a considerable number of pieces of papers on the paper-stacking plate are consumed and the height of the uppermost paper on the paper-stacking plate becomes lower than a predetermined threshold value, the paper-stacking plate is elevated by a required amount.
In the conventional paper feeder of the air suction type, plural floatation nozzles and separation nozzles provided in the air duct constituting the air-blowing means are arranged in a range corresponding to a maximum paper size. When the papers of small sizes are used, therefore, the air jetted from the nozzles also act onto both sides of the papers placed on the paper-stacking means. As a result, there arises a problem that there occurs a so-called overlapped paper feeding in which the papers are excessively floated and plural papers are fed at one time.
In the paper feeder disclosed in the above Japanese Unexamined Patent Publication (Kokai) No. 107347/1994, the protrusions are provided on the side of the suction ports. Therefore, the paper adsorbed by the conveyer belt is excessively undulated due to the mutual action between the protrusions and the suction. Consequently, the undulation remains on the paper even after being conveyed and it is liable to cause a paper clogging (jamming) in the subsequent conveyance.
Further, even when the uppermost paper and the second and subsequent papers are relatively smoothly separated, there often occurs the so-called overlapped paper feeding in which plural pieces of papers are fed at one time when there is some distance between the feed belt and the separation nozzles.
Desirably, the plural floatation nozzles and separation nozzles provided in the air duct constituting the air-blowing means are selected for their number and arrangement according to the size of the papers and the quality (weight) of the papers. In the conventional paper feeder, however, the floatation nozzles and the separation nozzles are formed in one member that constitutes the air duct. To cope with the papers of various sizes and various qualities, therefore, there must be provided air ducts of several kinds having floatation nozzles and separation nozzles in various numbers and in various arrangements, resulting in an increase in the cost.
In the above-mentioned paper feeder of the air suction type, the papers stacked on the paper-stacking means float in different conditions based on the velocity of the air blown from the plural floatation nozzles provided in the air duct constituting the air-blowing means. That is, when the air velocity is set to be adapted to thick and heavy papers, the thin papers are excessively floated givin
Fuchi Masami
Goda Mitsuhiro
Higashiyama Masaki
Yamamoto Kiyonori
Kyocera Mita Corporation
Skaggs H. Grant
Smith , Gambrell & Russell, LLP
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