Cathode-ray display tube for color printers

A cathode-ray display tube system for color printers, the cathode ray tube having a phosphor screen for producing thereon a light spot which is variable in position and color in response to input signals to expose photo-sensitive color paper, said phosphor screen including:

• a blue-emitting phosphor having a maximum ability of color emission in the range of wavelengths of 480 m.mu. and below with a radiant energy in the range of wavelengths of about 480 m.mu. and higher being 10% or less of the overall radiant energy;
• a green-emitting phosphor having a maximum ability of color emission in the range of wavelengths of 520 through 570 m.mu. with a radiant energy in the range of wavelengths of about 500 m.mu. and less and of about 630 m.mu. and higher being 5% or less of the overall radiant energy;
• and
• a red-emitting phosphor having a maximum ability of color emission in the range of wavelengths of 630 through 750 m.mu. with a radiant energy in the range of wavelengths of about 590 m.mu. and less being about 10% or less of the overall radiant energy;
• phosphor dots for producing color in a region of wavelengths to which ordinary photosensitive color paper is not sensitive and located beyond the area of normal raster;
• said tube system further comprising
• a photoelectric converter coupled to said phosphor dots for detecting light emission from said phosphor dots;
• a control circuit coupled to said photoelectric converter which is receptive of at least two pulse signals from said converter for determining the raster scanning condition of said phosphor dots:
• and an electron beam deflection circuit for said cathode-ray tube which is controllable by the output of said control circuit.