| 摘要 |
PURPOSE:To detect a recording signal at a constant linear speed out of a rotary recording medium, by providing a control voltage generating part consisting of a constant voltage circuit, a potentiometer and an auxiliary resistance, and generatting the voltage of a level which is adversely proportional to the radius of the rotary recording medium. CONSTITUTION:The synthetic resistance value (l) of an auxiliary resistance 53 and a potentiometer 52 is corresponding to the distance from the center (a) of a rotary recording medium 1 to the most outer circumference part (c). The resistance value (r) of the meter 52 to an earth is corresponding to the distance from the center (a) to a signal detecting means 6. The both-end voltage of the value (l), i.e., the voltage value V0 drawn to an output terminal 4 at a control voltage generating part 5 is adversely proportional to the resistance (r). The voltage V0 is applied to a motor 2 via an amplifier 3, and as a result the motor 2 gives the constant linear speed control to the speed of revolution of the medium 1 to the means 6. |
