| 摘要 |
<p>PURPOSE:To realize a simply structured apparatus by a method wherein, while rotary transformers for propagation of a signal are shortcircuited both on the rotary side and on the stationary side during the disuse of a channel in order to use them as a shortcircuiting transformer for reducing the cross talk, a shortcircuiting switch for the transformer on the rotary side is controlled by light. CONSTITUTION:A rotary drum 10 is installed on a stationary drum 9 of the apparatus, and light-receiving parts 8a, 8b are installed at the drum 10. The light-receiving parts 8a, 8b are arranged face to face with concentric light-sources 7a, 7b. Heads 3a, 3b are installed at the drum 10. A signal which has been reproduced with this head 3a is amplified at a channel amplifier 4a through coils 1a, 2a, and coils 1b, 2b are short- circuited by actuating switches 5b, 6b so that an interference signal reproduced at the head 3b can be eliminated. When the coils 1b, 2b are shortcircuited, the propagation of interference can be reduced by short-circuiting the coils 1b, 2b. If the coils 1a, 2a and the coils 1b, 2b are used alternately for a channel for propagation, control signals to be given to a group consisting of the switch 5a and the light source 7a and another group consisting of the switch 6b and the light source 7b are switched alternately.</p> |
