This invention relates to a paper feed mechanism for feeding cut sheets, which mechanism is connected to the interior or the exterior of a printing apparatus, such as a copying machine and a printer, or an image forming apparatus.
There are cut sheets of various sizes (for example, A5, A4, A3, B5 and B4). FIG. 1 shows a conventional paper feed mechanism. In FIG. 1, the size of a table 2 on which paper sheets are placed is at least larger than the size of the paper sheet of the maximum size, and paper sheets of various sizes can be suitably set on the table by moving a paper guide 1 in a direction perpendicular to the direction of feed of the paper, that is, by moving the table to a position corresponding to the widthwise dimension of the paper. FIG. 2 is a view as seen from the side of the paper feed mechanism. The height of the uppermost one of the cut sheets stacked on the table 2 is detected by a height sensor 8, and the height is automatically adjusted to a predetermined level by an associated means (connected to the table via pulleys 7 and a line 4) not shown.
When cut sheets of A4-size are loaded into such a conventional paper feed mechanism which can accommodate cut sheets, for example, of up to A3-size, about a half of the paper feed mechanism becomes a useless space. In order that the apparatus can operate efficiently, it is desirable that the number of the cut sheets to be loaded at one time be as large as possible. Therefore, generally, the copying machine or the printer for a higher-speed operation or for mass- printing application is provided with a paper feed mechanism of a larger capacity.
However, accommodating a large number of cut sheets poses a problem in that the size of the apparatus becomes excessively large.