| 摘要 |
PURPOSE:To attain automatically the selection of fast feed, by using an operating key for fast feed in common use with an operating key for fast speed for a medium and a large scale track jumping. CONSTITUTION:Command signals Sa, S1, and Sf are applied respectively to terminals 32, 33 and 36 of an optical beam control circuit 15 from an output terminal of an operating command section 16 when the fast feeding by one track jumping is performed. The command signal Sa is applied to a track jump period designating circuit 38, a pulse Pa is obtained and applied to one contact of a switch 39. The switch 39 is turned on by being applied to a control terminal with the command signal S1 from a terminal 33 and the pulse Pa is applied to one-track jump designating circuit 40 through the switch 39. The command signal Sf is applied from the terminal 36 to the one-track jump designating circuit 40, a drive pulse PD1 having a prescribed width T2 is obtained at one output terminal and a braking pulse PB1 having a prescribed width T3 is obtained with a negative polarity at the other output terminal. A tracking control means 45 is driven finally in response to the drive pulse PD1, the tracking control means 45 is braked in response to the control pulse PB1, allowing to attain the one-track jumping. |
