Allied Corporation

John C Wilson, Jr

Richard L Cohen

Mitchell Aron

A directional optical filter (41) is provided for a shadow mask color cathode ray tube (shadow mask CRT) (47) having a plurality of display elements on its face (49). Two sets of light absorbing planes are arranged at approximately 90.degree. from one another and serve to block light passing therethrough from an angle greater than a predetermined angle of viewing. In order to reduce moire patterns which would result from varying coincidences of the planes with patterns of phosphor dots on the shadow mask CRT (47), filter sheets (43, 45) containing the light absorbing planes are rotated so that at least one set of light absorbing planes is misaligned with a set of closely-adjacent phosphor dots by approximately 15.degree.. Advantages include the ability to provide a parallel light absorbing plane directional optical filter in association with a shadow mask CRT and an ability to control the range of preferred viewing angles to differing amounts substantially in the horizontal and vertical directions.

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Wayne, NJ, United States of America

John C Wilson, Jr