This invention relates to a paper feeder used with a recording apparatus such as a printer for feeding sheet-like paper stacked on a hopper, and in particular to a paper feeder comprising a paper returner for returning an overlappedly transported sheet of paper to the hopper, the paper returner having a function of separating and feeding sheets of paper one by one.
A paper feeder used with a recording apparatus comprises two paper feeding rollers placed in a paper width direction, the one paper feeding roller being fixedly placed on one side edge side, and the other being built in an edge guide and semi-fixedly placed movably matching the paper width. A base end of the hopper is attached rotatably to a shaft at a right angle to the entry direction such that the whole of paper in the width direction is moved up or down at the same time by a cam mechanism associated with rotation of the paper feeding roller. A rotatable separation pad holder is provided with a separation pad to separate the sheets one by one from the hopper and feed each sheet.
When paper is abutted against the paper feeding roller, and at the same time, the separation pad is pressed against the paper feeding roller as the hopper moves up, the top sheet of paper is separated and fed. When the sheet arrives at a transport roller and skew removal is terminated, the paper feeding roller is rotated and stopped at a home position. Meanwhile, positioning is performed such that a distance between a leading edge of the paper sheet and a recording head is made constant is performed, and then print is started. When the paper feeding roller is stopped at the home position, a gap is formed between the paper feeding roller and the separation pad, but a part of the sheet being printed exists. At this time, another sheet overlappedly sent enters the gap, and two or more overlapped sheets may also be fed in conjunction with the sheet being printed in some cases. As a measure against such trouble, an idle roller is usually pressed against the separation pad. When a sheet being printed exists between the paper feeding roller and the separation pad, it is pressed against the separation pad by the idle roller, whereby entry of the sheets overlappedly sent is prevented. Each sheet whose entry is blocked is pushed and returned to the hopper by operating a paper return lever (paper returner) after the print terminates.
This related paper feeder comprises the separation pad holder and the paper return lever as separate components, and thus has a complicated structure and a large number of parts, leading to an increase in costs. Since the paper returning operation is performed after print, the next paper feed operation cannot be started until the paper returning operation terminates, and thus the time interval between the print termination of one sheet and the print start of another sheet (throughput) is prolonged. Further, since the sheet being printed is pressed against the idle roller, a contact load with the sheet occurs and leads to a load of a motor drive system, etc.
USPTO Backgrounds
USPTO Backgrounds