摘要:
Display apparatus which includes a cathode ray tube. Electrical signals carrying information indicative of visual images are conveyed to an electrode in the tube and an electron beam is modulated in response to the signal and scans the screen in line and field directions to generate visual images. The line scan causes the beam to move alternately in the forward sweep (display) and flyback directions and the apparatus is arranged to cause the ratio of blanking period to display period to be greater than conventional values, i.e. at least 23.08%. Increasing blanking time and hence available flyback time over conventional values allows display improvement techniques, such as increasing field rate or number of lines per field, to be used without requiring, for example, line output transistors with higher voltage ratings.
摘要:
A vertical deflection amplifier (20) of a video display apparatus includes first (Q1) and second (Q2) transistor amplifier output stages arranged in a totem-pole, push-pull configuration. A vertical deflection winding (Lv) is coupled to the output stages at a deflection amplifier output terminal (22). An S-capacitor (C1) is coupled to the deflection winding (L v ) at a second terminal (21) remote from the output terminal (22). A source (23) of deflection rate signals is coupled to the deflection amplifier (20) for generating a deflection current (iv) in the deflection winding (Lv). A base current generating circuit (40) is coupled to one (Q1) of the transistor amplifier output stages for providing base current (i 1) thereto. The S-capacitor voltage (V1) is applied to the base current generating circuit (40) for enabling conduction of base current (i1) in the one amplifier output stage (Q1). When the video display apparatus is first turned on, the initially discharged S-capacitor (C1) is slowly charged from a DC voltage supply (+30V) to delay generation of vertical deflection past completion of picture tube degaussing.