GB1284836A - Educational device - Google Patents

Abstract

1284836 TV teaching machines DATAPLEX SYSTEMS Inc 17 Nov 1970 54614/70 Heading G5G Television video signals representing a primary and plural secondary visual images are transmitted together with a synchronizing signal to a receiver wherein selectively operable means are provided to control the transmission to controllable display means of control signals generated in the receiver in response to the synchronizing signal so as to selectively display said secondary images. As shown (Fig. 3), the frame sync. pulse signal in a television receiver is fed to a 4X frequency multiplier 32 coupled to a four stage ring counter 34 whereby the frame scan time is divided into four equal segments (one primary and 3 secondary). During each time segment a signal exists on one or other of the output leads 36, 38, 40 or 42 which are connected by way of AND-gates 44, 48, 50, 52 to an OR-gate 54 the output of which controls the bias on the control grid of the cathode-ray tube and thus controls whether a picture is displayed or not. Second respective inputs to the AND-gates are connected to switches 22, 24, 26 and 28 on a student control panel. In operation a switch 22 is normally closed to uncover the first or primary segment of the picture which includes a question and three possible answers. By selecting switches 24, 26 or 28 to represent his answer the student can uncover selected secondary segments to ascertain whether his answer was correct or not. Digital information to be displayed and derived from a keyboard, computer or printing telegraph machine are converted by known digital-tovideo signal conversion means. Alternatively a programmed slide projector and television camera could be used. Characters on the screen may be accentuated by flashing, underlining or colours and more or less segments may be provided. The signals may be transmitted to a plurality of receivers. If, say, one of the answers is too long to fit into one segment, then two complete frames may be transmitted a suitable interval apart. The switch 22 may be under the control of an instructor. As well as words, drawings can be displayed. A control signal detector 72 is provided whereby a whole frame question can be displayed followed by selection by the student of one out of four possible answers.