GB1512656A - Television channel display - Google Patents

Abstract

1512656 Alphanumeric character generators MAGNAVOX CO 2 June 1975 [5 June 1974] 23774/75 Heading H4T A character generator for a TV receiver, e.g. for display of channel number, comprises horizontal and vertical voltage-controlled oscillators 92, 93 respectively receiving horizontal and vertical drive signals of the receiver, a data decoder 96 having a number of outputs a, b, c ... g each corresponding to a selected character segment (see Fig. 4) which may be displayed in response to an address signal. The VCO's 92, 93 supply clock signals respectively to horizontal and vertical counters 63, 64 which control gates68, 69,71,72andflip-flop70. The formation of a character is initiated by pulseforming circuits 160, 170 which control flip-flops 65, 75. Selection of segments according to the output of the decoder 96 is accomplished by gates 78, 79, 81, 82, 83. Gates 78, 79 have inputs from the horizontal and vertical logic circuit. The outputs of the horizontal and vertical counters is shown in Fig. 6 for a two-character display. Coincidence of these outputs results in the required pattern generation. Size of characters is determined by circuit 91 (Fig. 2, not shown) controlling the clock frequencies of VCO's 92, 93. The circuit 91 may comprise a slowly-discharging capacitor which causes the characters to shrink to zero size as they are displayed. A cursive slant to the characters may be obtained by varying the intervals T1, .... T5, Fig. 4. This is accomplished by pulse-width modulation of the outputs of the VCO's.