In order for printers to operate effectively, they must be able to perform different tasks during a print cycle, such as picking up a sheet of paper, feeding it into the printer and expelling it after printing. To perform such tasks, printers generally have different motor-driven gear trains. For example, to pick up a sheet of paper, a printer may have one gear train that, when engaged, triggers a mechanism that can pick up the next sheet of paper. The printer would have another gear train to eject the sheet of paper after printing. Accordingly, printers generally include numerous gears and different gear trains.
Additionally, a printer may include a multiplexer to engage different gear trains. For example, the printer described in U.S. Pat. No. 4,728,963, naming Steve O. Rasmussen et al. as inventors, includes a multiplexer. In that printer, the multiplexer has three multiplexer gears. A different multiplexer gear is required for each different task that the printer can perform. Each multiplexer gear is engaged by moving a trigger. Different printer tasks are actuated by engaging different multiplexer gears.
A problem with printers having multiplexer gears and multiple gear trains is that numerous, complex and costly gear mechansims are required. This invention offers a printer capable of performing different tasks without requiring complex gear trains and multiplexer gears. In other words, the invented printer includes a carriage-actuated clutch that may be used to trigger different tasks. Thus, the invented printer may be manufactured much less expensively and with fewer parts than existing printers.
As stated, one task that a printer must perform is to pick a sheet of paper and feed it into the printer. To accomplish this a printer must have a paper-feed mechanism. One type of paper-feed mechanism, as described in U.S. Pat. No. 4,728,963, includes a spring-biased plate that articulates between raised and lowered positions. Paper is stacked on the plate and when a certain gear train is engaged, the plate is allowed to articulate to its raised position. In its raised position, drive rollers contact the top sheet on the stack and feed it into the printer. Thereafter, the gear train causes the plate to articulate to its lowered position. As stated, such a paper-feed mechanism may be triggered by a multiplexer and requires a separate multiplexer gear and a complex and costly gear train.
The invented printer includes a paper-feed mechanism that can be triggered by the same carriage-actuated clutch that may be used to trigger other functions. Additionally, the paper-feed mechanism of the invented printer does not require a gear train that causes the plate to articulate between raised and lowered positions. Thus, the invented printer includes a simpler and more economical paper-feed mechanism than is present in existing printers.