Browse Prior Art Database

CRT Display Position Indicator

IP.com Disclosure Number: IPCOM000052830D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Crow, JD: AUTHOR

Abstract

A position of interest on an interactive CRT display screen is indicate by pushing a flexible lightguide film against the screen with a finger or other object and sensing phosphor light coupled into the film at the position of contact between the film and screen. The film is normally spaced slightly away from the screen by an elastic cladding which may be either liquid or solid.

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CRT Display Position Indicator

A position of interest on an interactive CRT display screen is indicate by pushing a flexible lightguide film against the screen with a finger or other object and sensing phosphor light coupled into the film at the position of contact between the film and screen. The film is normally spaced slightly away from the screen by an elastic cladding which may be either liquid or solid.

For an interactive CRT display, it is desirable to be able to indicate a position of interest on the CRT faceplate. This is commonly done using a light pen, which is cumbersome to use and often unreliable.

I propose to use a transparent plastic lightguide thick film 10 and laminate it over the surface of a CRT faceplate 12 in order to capture CRT phosphor- generated light from a local region 14 on the faceplate and guide it to a photodiode 16 (or photodiode array) placed along the edge 18 (or around the edge) of the film. A synchronizing of the photosignal with the CRT raster scan will indicate the position of the CRT-to-guide coupling.

Coupling is accomplished by pushing the lightguide against the faceplate, with pressure 20 from a finger or similar object. To localize light coupling to the region pressed, an elastic cladding 22 is inserted between the guide and the faceplate. This elastic material may be a solid, such as RTV rubber, or even a liquid.

Deformation of the lightguide film effects light coupling because the film is being pressed against the CRT...