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Light Guidance System For Visual Display Unit

IP.com Disclosure Number: IPCOM000048876D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kirkman, DH: AUTHOR

Abstract

An electrochromic or other passive display module has an illumination system suitable for the rear projection of the displayed image onto the front screen of a visual display unit (VDU). The illumination system comprises a wedge-shaped light guide overlying the display module and an adjacent side light guide contacting the module wall. Both guides are illuminated at their ends remote from the module. Light escaping from the module other than to a projection lens is reflected back by a curved mirror.

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Light Guidance System For Visual Display Unit

An electrochromic or other passive display module has an illumination system suitable for the rear projection of the displayed image onto the front screen of a visual display unit (VDU). The illumination system comprises a wedge-shaped light guide overlying the display module and an adjacent side light guide contacting the module wall. Both guides are illuminated at their ends remote from the module. Light escaping from the module other than to a projection lens is reflected back by a curved mirror.

The display module 10 includes an array of rough-surfaced display electrodes 11 onto which an electrochromic material in solution, such as a viologen, may be selectively deposited to form an image. The rough surfaces of the electrodes are good scatterers of light so that, whatever the angle of incidence, a high proportion of incident light will reach the aperture of a projection lens system 20 which magnifies the displayed image. The magnified image is then projected onto the rear of a translucent screen 25 by means of two beam folding mirrors 22 and 23.

The illumination system for the display comprises a lamp 30 such as a tungsten-halogen lamp with an elliptical dichroic reflector. The reflected beam from this lamp is of limited angular divergence and is directed onto the ends of a pair of light guides 31 and 32. Excess heat is reflected away by means of a hot mirror 33.

The light guide 31 is wedge-shaped and overlies the upper face 12 of the module 10. A film of index matching fluid may be sandwiched between wedge 31 and face 12. Light incident upon the input face of the wedge ligh...