| 摘要 |
A system for interlocking the rotation of master and slave shafts is particularly suitable for use in film editing tables. …<??>The or each slave shaft (33) is controlled by, firstly, a velocity servo loop which compels the slave shaft to rotate in precise speed synchronism with a remote or line master shaft (33a). This primary feedback loop compromises encoders (36, 35) generating trains of pulses having a characteristic representative of rotational speed, and bipolar frequency-to-voltage converters (42, 43) deriving from these pulse trains analogue voltages which are applied to a differential amplifier (32) to produce an error signal to be driven to zero for control of the slave shaft speed. Additionally, a secondary feedback loop includes a digital-to-analogue converter (41) for deriving a third analogue voltage proportional to the digitally measured difference between the characteristics of the first and second trains of digital pulses. This third analogue voltage is combined with the first or second analogue voltage in a mixer (37) to form a composite input to the differential amplifier and, being derived through a secondary feedback loop parallel to the primary loop, maintains the shaft feed in precisely interlocked synchronism. |
