CALIBRATION DISPLAY APPARATUS

摘要

PURPOSE:To enable calibration of a deflection circuit very easily, by a method wherein the phosphor surface of a CRT is coated with a fluorescencers wavelength different from that of the surface and a filter adapted to pass light with the wavelength and a photodetector are provided near the coated part thereof. CONSTITUTION:The phosphor surface of a CRT 1 is coated with at least a pair of fluorescencers of the wavelength different from that of the surface. When a beam 3 hits the coated part 2, light with a different wavelength is generated. Filters 4 and 5 transmit the light with the wavelength of the fluorescencer coating; the light is received with light receiving elements 6 and 7 to be converted into changes in the electrical signal with photoelectric convertor sections 8 and 9 and amplified with amplifiers 10 and 11 to a specified level. Then, outputs of the amplifiers 10 and 11 are compared with an input signal 13 by a calibration logic section 12 and a gain of a deflection amplifier 14 is adjusted to control an applied voltage of a deflection plate 15. This permits a deflected beam to depict the size of an input signal accurately with respect to the given input signal.