| 摘要 |
PURPOSE:To prevent false operation due to change of a projector or the like due to ageing or disturbing light by utilizing polarization by the film and by constituting a device so that the variation of the amount of polarization thereof is negated each other. CONSTITUTION:The light from a projector 2 enters a light receiver 4 through the intermediary of a mirror 71, a lens 121, polarizing filters 11 and 10 and a mirror 73. The light from the projector 2 enters the light receiver 4 also through the intermediary of a mirror 72, a lens 122, polarizing filters 9 and 8 and a mirror 74. The output signal of the light receiver 4 is amplified by an amplifier 6 and taken out as a control signal from a terminal 7. By this control signal, a magnetic recording tape 1 is operated. |
