Misconvergence measuring apparatus

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.