| 摘要 |
A speed normalization circuit for eliminating the need to fine tune a servomechanism, such as a daisy wheel printer, after manufacture, for example, in order to compensate for speed variations caused by tolerance variations throughout the manufacturing process and evidenced by variations in the actual print wheel speed and the actual carriage speed, is disclosed. In operation, when a restore sequence is called for (power up, remote restore, cover open/resume, check/resume), the carriage is restored to the leftmost home position and is then stepped three times by an identical amount (twelve increments, 1/120 of an inch per increment). The average value of the actual carriage speed for these three movements is determined and a compensation value is selected. If the carriage speed is too slow, the nominal speed value stored in a read only memory look-up table is incremented by a fixed value (i.e., plus one, two, or three units); if the speed is too fast, the nominal speed value is decremented by a fixed value (i.e., minus one, two, or three units). The compensation value is added to the nominal speed value during subsequent actual operation of the servomechanism. For the print wheel, there are two programmed movements upon restore, namely, one half rotation in each direction (one forward, one reverse) for a total of ninety-six increments per movement. The speed compensation value is calculated in the same manner. Other features are also disclosed. |
