Closing device as insertion preventer for magnetic-tape cassettes, in particular video-tape cassettes

摘要

A closing cylinder is intended to prevent the unauthorised reproduction of a recording on video tape. According to an exemplary embodiment, this is performed by the cylindrical core 1 being inserted into a cavity of the video-tape cassette 4 which is unoccupied and accessible from the outside, namely into the round opening provided for a transmitting diode (d = 12 +/- 0.2 mm), the diode opening 8. When the key is withdrawn, the tumblers 6/7 move into the light window 9 of the video-tape cassette 4. The cylindrical core 1 terminates flush with the main outer side of the video-tape cassette 4 and, together with two projections 2/3, blocks a passage of the control groove 5, crossing the diode opening 8. Normally a feeler in the video recorder mechanically senses the correct position of the video-tape cassette 4. Since, however, the cylindrical core 1 located in the diode opening 8 blocks the passage of the control groove 5, the video-tape cassette 4 is not accepted by the video recorder, thereby preventing the reproduction of a magnetic recording. <IMAGE>