Waveform correction circuit for dynamic focus amplifier
US5486741A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 3, 1994 |
| Grant date | Jan 23, 1996 |
| Priority date | — |
| Expiry date | Aug 3, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/26
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A dynamic focus amplifier, comprising: a first circuit responsive to a vertical rate sawtooth waveform for generating at the vertical rate a modulating waveform having a desired component of a given shape during trace intervals and an undesired time compressed version of the given shape during retrace intervals; a second circuit responsive to the sawtooth waveform for generating a pulse waveform at the vertical rate, substantially corresponding in width and phase to a vertical retrace blanking waveform; and, a differential amplifier stage, formed by Darlington pairs, for combining the modulating waveform and the pulse waveform to remove the undesired time compressed version of the given shape from the modulating waveform. The second circuit may comprise a capacitor which is charged in a first direction by the sawtooth waveform during vertical trace and charged in an opposite direction during vertical retrace.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.