Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Patent
1980-02-22
1981-11-10
Blum, Theodore M.
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
358 60, H01J 2954
Patent
active
043000762
ABSTRACT:
In a color projection TV system using three cathode ray tubes (one for each of the primary colors green, red and blue), the vertical deflection coils of all three CRT's are capacitively coupled in a series string configuration so that they can be driven by a common amplifier. The capacitors provide AC coupling at the sweep frequency, but maintain DC isolation between the deflection coils. For raster-centering purposes various voltage divider configurations including adjustable resistances are used to establish adjustable DC levels at different ends of each coil. If any of these adjustable resistances are adjusted to apply a potential difference across any of the deflection coils, the result is a constant centering current flowing through each of those coils to maintain steady-state magnetic bias fields for vertical centering of the electron beams. In some configurations the sweep amplifier itself is part of the DC centering current path. All of the adjustable resistances associated with a given deflection coil are ganged in aiding relationship so far as their effect on the direction of beam centering is concerned, but the adjustable resistances for each CRT are adjustable independently of any other CRT to facilitate proper fusion of the three primary color images.
REFERENCES:
patent: 2250884 (1938-10-01), Bahring
patent: 2470197 (1946-09-01), Torsch
patent: 2654854 (1953-10-01), Seright
Blum Theodore M.
Zenith Radio Corporation
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