| 摘要 |
PURPOSE:To prevent noise from being mixed in from the outside, by using a spiral groove bearing and a coaxial type rotary transformer, and also, forming an annular recessed part going round a shaft, on the upper face of a rotary drum, containing an electronic circuit in this recessed part, and closing up an opening of the recessed part by a shielding plate. CONSTITUTION:By using a spiral groove bearing 30, a surplus space exists in a rotary drum 7, a coaxial type rotary transformer 31 is integrated into this surplus space, and as a result, a space of a size being equal to a space which has been occupied by a conventional plate-shaped rotary transformer is left in the rotary drum 7. Subsequently, by utilizing the space which has been left in the rotary drum 7, an annular recessed part 70 is formed, and since an electronic circuit 100 consisting of a head amplifier 9 and an electronic switch 15, etc., has been integrated into this recessed part 70, a wiring to a magnetic head 8 becomes short. Moreover, by covering an opening of the recessed part 70 with a shielding plate 17, the rotary drum 7 can have a function as a shielding case, as well.
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