Abstract: A system is described for synchronizing the display of characters within a character image area on a raster scanned cathode ray tube. The system's input is a composite blanking signal which includes conventional horizontal rate and vertical rate blanking pulses. In response to the composite blanking signal, the system generates a reset signal when the tube's scan reaches a reference position such as at the top of display. The reset signal and the composite blanking signal are used to develop a control signal when the composite blank signal indicates that the tube's scan has reached the character image area. Other circuitry responds to the control signal and the composite blanking signal for addressing a conventional character display circuit. The latter circuit is thus synchronized to output, to the cathode ray tube, data which is imaged within the character image area.

Abstract: A system for correcting for vertical off-axis optical projection distortions in a projection television is disclosed. In a projection television wherein the image projection axis is obliquely disposed in the vertical direction relative to the projection screen axis, a system for correcting for video image distortion caused by this configuration involving modulating the vertical size input is disclosed. A vertical rate correction signal is developed from the vertical output circuit and provided in a feedback arrangement to a sawtooth wave signal generating circuit for regulating electron beam vertical sweep in a projection television CRT, or CRT's. By decreasing CRT electron beam vertical sweep rate across that portion of the projection screen where the video image is vertically stretched and increasing the vertical sweep rate for the vertically compressed portion of the video image, a linear, distortion-free image is presented on the projection screen.