| 摘要 |
PURPOSE:To prevent sufficiently the resonance of a pcikup arm by processing the 1st and the 2nd output voltages and compensating their variations with time due to temperature fluctuations, and holding a pickup and a record disk in invariably constant position relation according to the temperature-compensated outputs. CONSTITUTION:The time when a sound passes through a route (x) in a figure is denoted as Tx, and the sound velocity increases by (k) times. When it is reflected by the record disk 4, namely, when the sound passes through a route (y), the time is denoted as Ty. Output voltages Vx and Vy are proportional to the times Tx and Ty, so a division output Vz is (b+kc)/a and depends upon values (a), (b), (c), and (k) regardless of ambient temperature. The values (a) and (k) are determined by the material and the thickness of a head shell 8 is always constant, and the value (b) is regarded almost as constant. The value (c) is nearly proportional to the height H of the head shell, so the characteristics of the division output Vz to the height H do not depend upon the temperature. This division output Vz is shifted in level by a level shifting circuit 21 to obtain an obtain an output voltage VH. |
