| 摘要 |
PURPOSE:To prevent interception by providing a locking means for a terminal device of a CATV system in a case so that unlocking is performed by electric control by means of a cipher signal from an input terminal. CONSTITUTION:A lock pin 3 is penetrated to the inside of an upper face of the case 1 and a disc 4 for locking is placed on a chassis 2 by a support pin 5. A lock hole 4b is penetrated to the disc 4 and a lock pin 3 is reserved to the chassis 2 accordingly. The pin 6 is supported elastically to the disc 4 by a spring 7 at all times and in common use with a core for a solenoid coil 8, and retrogressed against the spring 7 when the coil 8 is energized. The cipher signal is superimposed on a television video signal or inputted from an input terminal by the other means, the cipher signal is compared by a data comparison circuit 14, a composite signal with a signal from a terminal address 15 is fed back to a circuit 14 so as to transmit an unlocking instruction signal to a relay circuit 9. |
