DETECTOR OF SPEED IN MAGNETIC DISK SERVO TRACK WRITER

摘要

PURPOSE:To detect a speed in fine displacement with high accuracy by detecting fine displacement in high resolution. CONSTITUTION:A laser measuring device 2 to detect the position of a carriage 1 iradiates a laser beam L1 from the back of the carriage 1, detects a reflecting light beam L2 from the carriage 1, and outputs an up-count pulse S1 (at the time of advancing) and a down-count pulse S2 (at the time of regressing) to an up/ down counter 3. The output of a counter to count these output signals is divided into two systems and D/A-converted. Then a speed signal is obtained by differ- entiating them, and speed signals of these two system are alternately outputted by avoding the time when the module of a counter is switched.