Phase-Grating CRT Faceplate
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14
A phase-grating faceplate gives most of the visual advantages of an ultra-fine pitch color CRT when placed over a less expensive and more reliable moderate pitch CRT. Most people have looked at a half-toned picture from a newspaper under a magnifying glass and noted how the large dots completely hide the image. As the glass is lowered to the paper to reduce the magnification, detail reappears as the dots shrink in size and disappear. Technically, the dots are a very strong signal at a specific high spatial frequency that drowns out the picture detail much like a loud high-pitched "howl" would drown out subtle overtones in music. The shadow mask on a TV, even more so than dots in a picture, forms a very strong signal of high spatial frequency, and getting rid of it improves the ability to see detail in the image.