Line scan circuits for cathode ray tube displays
AssigneeInternational Business Machines Corporation
InventorsFrank Ainscow, Edward D. Anwyl
Life of this patent
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Abstract
A line scan circuit for a cathode ray tube display includes a phase detector (3), integrator (4), voltage controlled oscillator (5) and line output stage (6). The integrator, voltage controlled oscillator and line output stage are conventional, but the phase detector is novel. The phase detector compares the phase difference for both the leading and trailing edges of the horizontal synchronization pulses and the line flyback pulses. This forces the line flyback pulses to be centered with respect to the synchronization pulses resulting in improved centering and linearity of the displayed picture.
Claims6
A line scan circuit for a cathode ray tube display adapted to receive horizontal synchronization pulses and to produce a line scan waveform comprising a phase detector adapted to compare the phase difference between said synchronization pulses and line flyback pulses and to produce an output representing the phase difference,
- an integrator adapted to integrate the output of the phase detector and having its output connected to a voltage controlled oscillator,
- and a line output stage connected to receive the output of said oscillator to produce said flyback pulses,
- characterized in that said phase detector is adapted to compare the phases of said synchronization and flyback pulses on both the leading and trailing edges thereof, and to produce phase difference signals therefrom which cause said flyback pulses to be centered on said synchronization pulses.
Dependencies are inferred from the claim text.