| 摘要 |
A flying spot continuous motion telecine comprises an oscillator 1 which drives a horizontal counter 4A and a vertical counter 5. These in turn drive horizontal and vertical scan generators 6 and 7 respectively which produce sawtooth scan currents in the deflector 8 of a flying spot c.r.t. 9. Objective 10 focusses an image of the c.r.t. raster on the continuously moving film 11, and photocells 12 produce colour value signals R, G and B which are processed to form signals Y, R-Y and B-Y. These latter signals first pass through respective band pass filters 14, 16 and 18 and then the Y signal is analogue-to-digital (A/D) converted in an A/D converter 21, and the R-Y and B-Y are multiplexed by switch 38 and A/D converted in an A/D converter 20. The converters 20 and 21 are clocked by pulses from the oscillator 1. The digital signals, which are derived in sequential form by the flying spot scanning, are written into picture stores 22 and 23 under the control of store control logic 28 and read out again in interlaced form. The interlaced digital signals are reconverted to analogue form in D/A converters 24, 25 and 26 and finally encoded in a colour encoder 27. The counter 4A is programmable so as to vary the line scanning frequency of the flying spot, and the horizontal scan amplitude is changed in inverse proportion to the change in line scanning frequency. This causes the active (picture information containing) part of each scanned line to have the same duration for any selected line frequency, so that the clock frequency need not be changed with changing line scanning frequency. This avoids the need for switchable band pass filters which would be required if the clock frequency were changed. |
