| 摘要 |
PURPOSE:To allow a little bit rotation of a tone arm and reduce the influence of electromagnetic viscosity, and to improve follow-up characteristics of the tone arm, by providing a compensating means for allowing the stable linear tracking of an MFB arm. CONSTITUTION:The output of a potentiometer 60 is differentiated by a differentiator 61, whose output is inputted to a base driving circuit 53 through a compensator consisting of a low-cut filter having cutoff frequency which is about 20% of an arm resonance frequency. The base driving circuit 53 imposes operational amplification on the output of the compensator 52 and that of a differential amplifier which outputs the difference between both output voltages of magnetic effect elements 43 and 44 to flow a corresponding driving current to a motor 23. Consequently, torque corresponding to the composite output of the rotation angle of the tone arm 4 and the moving speed of an arm base 16 is generated at a motor 23 to move the tone arm 4 in the tracking direction together with the arm base 16. |
