GB671285A - Improvements in or relating to television receiving apparatus - Google Patents

Abstract

671,285. Television. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. June 14, 1950. [Aug. 18, 1949], No. 14836/50. Class 40 (iii). A cathode-ray tube television receiver is provided with means for adjusting the scanning generators to vary the screen area occupied by the picture and for simultaneously adjusting a masking device so as to cover that portion of the screen not occupied by the picture. The arrangement for adjusting the scanning generators is shown in Fig. 1 and comprises a two-position switch 24 the pairs of contacts 26, 27; 28, 29 and 30, 25 of which, when shorted by means of the contact elements 31, 32, 33, reduce, or short circuit, resistances 76, 91 and 60 in the frame and line scanning circuits which are of such magnitude that the raster which, in the switch position shown in the drawing, is of normal rectangular shape and of area less than that of the screen 22, is unformly expanded so that the screen is completely filled, the picture having the same aspect ratio in each switch position. Figs. 2 and 4 show the arrangement of the marking device which comprises a first masking member 122 rigidly secured to movable side members 123, 124 and a second masking member 125 pivotally attached to a pair of crank arms 127 which are pivotally attached to a fixed frame member 116 and to the movable side members 123, 124 so that vertical movement of the latter members, which is effected by operation of the switch 24 (Fig. 1) via a crank arm 133 rigidly attached to shaft 23 of switch 24 and pivotally attached to member 124, causes the masking members to occupy either of the positions shown in Figs. 2 and 4, the former corresponding to normal picture presentation and the latter to the expanded presentation.