Light pen controlled method and equipment for evaluating fluorescent screen pictures

In display equipment comprising a fluorescent screen, display control means including horizontal and vertical deflecting voltages for generating an electron beam and scanning the screen to display thereon successive pictures, and a light pen having an operative position directing a receiving optical system towards screen areas brightened by the electron beam and transducing the light received by the optical system from the brightened screen areas to generate bright-up control pulses for intensifying the electron beam whereby a light spot appears in the area of the screen towards which the light pen optical system is directed:

• (a) a pulse generator controlled by, and responsive to, the bright-up control pulses generated by the light pen, the pulse generator being operable to generate bright-up pulse trains timed relative to the control pulses to display a pilot area in said area of the screen and target pulses in a predetermined timed relationship to the bright-up pulse trains to display sharply defined target marks having coordinates determining a predetermined geometrical relation of the marks outside and adjacent the pilot area,
• (b) switch means arranged parallel to the deflecting voltages generating means for the electron beam and controlled by the target pulses to be closed in response thereto, and
• (c) means receiving the instantaneous deflecting voltages corresponding to the coordinates of the target marks upon closing of the switch means.