Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1989-05-04
1991-01-29
Willis, Davis L.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
324404, G01J 132
Patent
active
049888579
ABSTRACT:
This invention is concerned with apparatus for automatically measuring misconvergence in the production of color Braun tubes or color display apparatus using color Braun tubes. This misconvergence measuring apparatus includes a photoelectric transducer of split light-sensitive structure which is disposed in front of the phosphor screen of a color Braun tube with a deflection yoke mounted, a deflection source for supplying to the deflection yoke a waveform for deflecting the electron beams of the color Braun tube by a constant unit at a time, and a control unit for detecting the excited bright position on the phosphor screen at which the photoelectric transducer produces the maximum output and for controlling the deflection source, whereby the output of the photoelectric transducer is measured for the respective three primary colors of red R, green G, blue B or color differences G-B, B-R and R-G, and when the maximum value or centroid position of each color or color difference is obtained, the desired amounts of horizontal and vertical misconvergence are automatically measured from the positional differences of horizontal and vertical deflection. Moreover, a maximum output detection circuit for a color Braun tube is provided in which the output waveform from the photoelectric transducer is clearly derived in the form of an approximately normal distribution by use of focus potential change.
REFERENCES:
patent: 3188477 (1965-06-01), Ault
patent: 4602272 (1986-07-01), Duschl
patent: 4674877 (1987-06-01), Bullinga
patent: 4894593 (1990-01-01), Barten
Peter G. J. Barten, Spot Size and Current Density Distribution of CRT's, Japan Display '83, Oct. 3-5, 1983, Kobe, Japan, pp. 280-283.
Atobe Takashi
Ishikawa Takaaki
Karasawa Takumi
Mizuno Kazuhiko
Tsukii Michio
Hitachi , Ltd.
Le Que Tan
Willis Davis L.
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