TV screen supplementary character display - modifies colour or brightness selected screen areas to define character segments

摘要

The characters of the supplementary screen display system may provide a representation of the television channel being received, or a periodic display of the time, and are each formed by three horizontal segments and four vertical segments. The format and position on the screen of each of the characters is defined by four fixed voltage or current values of the horizontal scan corresponding to the abscissor and by six fixed voltage or current values of the vertical scan, corresponding to the ordinate. These fixed values are compared with the corresponding instantaneous values of the vertical and horizontal scans, to provide a signal used to modify the beam intensity of the tube at the position of the character segments required for display.