GB1296072A - - Google Patents

Abstract

1296072 Measuring personal movements, electrically TELESTRATOR INDUSTRIES Inc 18 Nov 1969 [18 Nov 1968] 56251/69 Heading G1N [Also in Divisions G5 and H4] An audio-visual teaching system comprises a magnetic tape recorder controlling the display of still pictures projected from 54 on to the screen 52 of an electrostatic storage tube 51, the tube also being capable of displaying line drawings either stored as changing X and Y co-ordinates on magnetic tape as part of the teaching program, or generated by a conductive pencil 13 when moved over a conductive light-transmitting film 11 on the tube surface. The pencil 13 is used to generate the signals for storage when compiling the teaching program, which is thus able to draw markers or diagrams on the pictures projected from film strip 54, as well as provide an audio commentary. The signals for X and Y deflection of the beam, for erase and blackout, and for advance of the film strip, are modulated on subvideo frequencies on the magnetic tape. At certain points in the lesson the student may be required to answer a question by ticking a box projected on the screen, and the tape is then stopped after signals representing the area of the box for the correct answer have been read off. These signals are then compared with those generated by the pencil and if coincidence is detected the tape is re-started. If the wrong answer is given a second tape recorder may be started to give supplementary information prompting a correct answer and a return to the basic program. An alternative display device in which the stored X and Y co-ordinates control motors moving a stylus over a powder-covered glass plate is described. The X and Y voltages are generated by pickoff by the pencil of a voltage with A.C. and D.C. components from a tin oxide layer fed with D. C. along the X-axis and A. C. along the Y-axis, these components being separated to give the X and Y signals. Specification 1294340 is referred to.