JPS554140A - Still picture program selector circuit - Google Patents

Abstract

PURPOSE: To make it possible to select a still picture signal without providing a channel selection switch circurit separately, by maintaining the content of a channel selection register before still picture switching at the time of the switching operation.

CONSTITUTION: With the alternation switch of switch circuit 1 depressed, a corresponding output becomes low in level and the corresponding output of latch group 2 is latched at a high level. Selection another station, therefore, results in that outputs of latch group 2 which correspond each other before and after the switching both become high in level, the output of OR- ELSE circuit 7 decreases in level, and the output of latch group 2 except that corresponding to a newly-selected channel becomes in low in level. The output of circuit 7 is inputted to monostable multivibrator 8 as well and then supplied to channel selection register 5 via AND circuit 9, so that a desired channel will be selected. To receive a still picture, switch 10 is placed at the terminal A side. Consequently, terminal A is held at a low level to close circuit 9, and the content of channel selection register 5 before the switching of switch 10 to terminal A is maintained. The program of the still picture of the selected channel is therefore reproduced by still picture receiver circuit 4.

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