A 45-Degree Reflection-Type Color Kinescope

The 45 degree reflection-type color kinescope is an experimental tube of the single gun type in which the color is changed by applying a control voltage directly to the screen assembly. The screen assembly consists of a multi-apertured metal plate coated on the front side with red, green, and blue phosphor strips and mounted parallel to a glass plate coated with a transparent conductive film. An electron beam scans the back of the metal plate at an angle of incidence of approximately 45 degrees. The portion of the beam passing through the slots is reflected by the electric field between the plates, causing it to fall back on one set of phosphor strips. By varying the potential of the glass "reflector" plate, the beam can be shifted from one color phosphor to another. The scanning beam is not required to follow the aperture pattern and the color purity is independent of beam focus. A feature of this tube is the automatc registry of the three colors over all parts of the screen. The screen is not difficult to construct; the power required to switch colors at megacycle frequencies is small. Other characteristics of this tube which should be noted are: the unconventional shape of the bulb, and the need, in some forms of the tube, for a "keystoning" correction of the scanning. Experimental one-gun tubes having screens seven inches in diameter have been built and operated with the RCA color system.