Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1995-02-16
1997-12-23
Powell, Mark R.
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
313497, H04N 912
Patent
active
057011346
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a picture display device comprising a video drive circuit and a display unit having a vacuum envelope which is provided with a transparent face plate with a luminescent screen and a rear plate, said display unit comprising a plurality of juxtaposed sources for emitting electrons, a plurality of electron transport ducts cooperating with the sources for transporting the electrons in the form of electron currents, and selection means for withdrawing each electron current at predetermined locations from its transport duct and for directing said current towards desired pixels of the luminescent screen.
A picture display device of this type is described in the non prepublished European Patent Application no. 92204007.6 (PHN 13.963), with reference to publication number EP 0550104A2.
The display unit mentioned above is of the flat-panel type, as disclosed, for example in European Patent Applications EP-A-400 750 and EP-A-436 997. Display units of the flat-panel type are constructions having a transparent face plate and, arranged at a small distance therefrom, a rear plate, which plates are interconnected by means of partitions and in which the inner side of the face plate is provided with pixels in the form of a phosphor pattern, one side of which is provided with an electrically conducting coating (the combination also being referred to as luminescent screen). If (video information-controlled) electrons impinge upon the luminescent screen, a visual image is formed which is visible via the front side of the face plate. The face plate may be flat or, if desired, curved (for example, spherical or cylindrical).
The display unit described in European Patent Applications EP-A-400 750 and EP-A-436 997 comprises a plurality of juxtaposed sources for emitting electrons, local electron transport ducts cooperating with the sources and each having walls of high-ohmic, electrically substantially insulating material having a secondary emission coefficient suitable for transporting emitted electrons in the form of electron currents and a selection structure comprising selectively energizable electrodes (selection electrodes) for withdrawing each electron current from its transport duct at predetermined extraction locations facing the luminescent screen, while further means are provided for directing extracted electrons towards pixels of the luminescent screen for producing a picture composed of pixels.
The operation of this known display unit is based on the recognition that electron transport is possible when electrons impinge on an inner wall of an elongate evacuated cavity (referred to as "compartment") defined by walls of a high-ohmic, electrically substantially insulating material (for example, glass or synthetic material), if an electric field of sufficient power is generated in the longitudinal direction of the "compartment" (by applying an electric potential difference across the ends of the "compartment"). The impinging electrons then generate secondary electrons by wall interaction,. which electrons are attracted to a further wall section and in their turn generate secondary electrons again by wall interaction. The circumstances (field strength E, electrical resistance of the wall, secondary emission coefficient .delta. of the walls) may be chosen to be such that a substantially constant vacuum current will flow in the "compartment".
Starting from the above-mentioned principle, a flat-panel picture display unit can be realised by providing each one of a plurality of juxtaposed "compartments", which constitute transport ducts, with a column of extraction apertures at a side which is to face a display screen. It will then be practical to arrange the extraction apertures of adjacent transport ducts along parallel lines extending transversely to the transport ducts. By associating selection electrodes arranged in rows with the arrangement of apertures, which selection electrodes are energizable by means of a first (positive) electric voltage (pulse) for withdrawing el
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Lambert Nicolaas
Van Gorkom Gerardus G. P.
Kraus Robert J.
Powell Mark R.
Suraci John
U.S. Philips Corporation
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