| 摘要 |
1519974 Video disc playback R C A CORPORATION 4 Aug 1975 [22 Aug 1974 12 Nov 1974] 32494/75 Heading G5R In a video disk reproducing system, e.g. of the type for capacitive playback of signals recorded as topographic features in spiral groove 13, a bimorph device 38 is provided in the pick up arm 18 between signal pick up 17 and the arm support, which bends when energized and radially displaces the pick up into an adjacent groove to provide a still picture mode of operation, a fast forward play mode or reverse play mode. In the described arrangement four television frames are recorded in each groove convolution. The bimorph is energized with pulses derived from the vertical sync component of the played back video signal and during the vertical blanking period is energized to move the pick up one groove outwards once per record revolution for still picture playback or is energized to move the pick up one groove outwards twice per revolution for reverse play or one groove inwards twice per revolution for fast forward play. As described the bimorph element is a pair of piezo electric layers sandwiched between an inner metal layer and two outer layers 42, 43 to which the energizing pulses are applied. Alternatively the element can be electromagnetic or magneto-strictive. In a second arrangement, Figs. 3 and 4 (not shown) the bimorph element is disposed between the stylus support element 32 and the arm 18. |
