Philips Electronics North America Corporation

Koninklijke Philips Corporation N.v.

North American Philips Corporation

Stephen Magocs

Scott H Baker

Michael B Larson

Gregory W Keck

Carl J Gilman

In a projection display system for example, a projection lens includes a non-radially symmetrical light stopped that is painted or otherwise applied directly to the surface of an optical lens element of the projection lines.

Non-symmetrical light stop

A system for mounting an infrared (IR) remote control receiver in a rear projection television apparatus features a mirror having a coating wherein visible light is reflected to a viewing device, and light in the infrared regions is passed through the mirror and detected by an IR receiver mounted behind the mirror.

System for mounting infrared receiver behind mirror in rear projection television applications

A front projection screen is made up of a front portion and a rear portion, the front portion having a front surface lenticular lens array and light scattering particles forming a diffusion region between the front and rear surfaces, and the rear portion having a reflective surface spaced apart from the diffusion region. In use, an incoming ray of projected light traverses the diffusion region and the space between the diffusion region and the reflective surface, before being reflected back through these regions again. Thus, the ray traverses different portions of the diffusion region in different directions, increasing the likelihood that the ray will encounter at least one scattering particle, thus reducing the incidence of speckle. A stiffening layer of a glass plate with an anti-reflection coating is bonded to the front surface of the screen.

Front projection screen with lenticular front surface

A beam combiner for an LCD projection television system makes use of a penta-prism which focuses three separate light sources on a viewing screen. The use of a penta-prism as a beam combiner allows for a compact light path, simplicity of manufacturing and a cost effective dichroic mirror arrangement as part of the penta prism. The light path within the penta-prism from the three light sources forms a right-angled triangle which provides the above-identified advantages.

Beam combiner for LCD projector utilizing a penta-prism

A front projection screen is made up of a front portion and a rear portion, the front portion having a front surface lenticular lens array and light scattering particles forming a diffusion region between the front and rear surfaces, and the rear portion having a reflective surface spaced apart from the diffusion region. In use, an incoming ray of projected light traverses the diffusion region and the space between the diffusion region and the reflective surface, before being reflected back through these regions again. Thus, the ray traverses different portions of the diffusion region in different directions, increasing the likelihood that the ray will encounter at least one scattering particle, thus reducing the incidence of speckle.

To prevent light scattering at the edges of CRT's used in projection television, emission of light is prevented beyond a desired region of raster scanning. In one embodiment, portions of the front surfaces of the CRT's outside the desired region are darkened to prevent light emission.

Method and apparatus for reducing scattered light in projection

For enhancing the contrast of a picture on a projection scrren derived from a liquid crystal display, the analyzer, which is normally part of the liquid display unit, is incorporated either in front of or in back of the screen relative to the viewing area or may constitute a layer between the front and rear portion of the screen. In any of these positions, the presence of the analyzer will result in darker portions and therefore in enhanced contrast. When it is used in front of the screen relative to the viewing area, protection of the lenticular surface also results.

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Knoxville, TN, United States of America

Stephen Magocs