Plasma panel light pen tracking using adaptive tracking scan
AssigneeBell Telephone Laboratories, Incorporated
InventorsPeter Dinh-Tuan Ngo, William Herbert Ninke
Life of this patent
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Abstract
A light pen tracking system and method particularly adapted for use with a plasma panel in which a first plurality of display sites on a display device are sequentially excited in such manner as to generate a signal which may be detected by a light pen. Upon detection of a first light signal, a second set of display sites centered at a location identified by the first signal and having smaller area than the first scanned area is then scanned. Because a relatively small area is scanned in the second scanning mode, and because the center of this smaller area has been localized by the previous signal detection, it is possible to more closely track rapid movements of a light pen on a display surface.
Claims11
Apparatus for detecting a moving light sensor over a plasma panel display surface having a plurality of plasma cells located at respective display sites, selected ones of said plurality of cells being periodically activated, thereby to emit light pulses at periodic intervals and at a fixed time in each such interval, comprising
- first means for sequentially activating at least selected ones of said plurality of plasma cells at times different from said fixed times,
- second means for sequentially activating at least selected ones of a subset of said plurality of plasma cells at times other than said fixed times, the position of said subset having a predetermined relationship to the position of said light sensor at the time said sensor last detected a light pulse at one of said plurality of plasma cells at other than said fixed time, and
- output means responsive to said light sensor for generating signals indicating the positions at which said sensor detects light pulses at other than said fixed times.
The machine method of tracking a light sensor moving over a plasma panel display surface having a plurality of plasma cells comprising the steps of
- A. generating a visible image on said display surface, with individual cells activated by said generating emitting light signals at fixed period times,
- B. generating a finder mode scanning light pulse beginning at a reference point on said display surface and continuing over said display surface until detected by said light sensor located at an arbitrary first position on said display surface, said finder mode scanning light pulse being generated by sequentially activating at least some of said cells on said panel at other than said fixed times,
- C. generating a tracker mode scanning light pulse over an area comprising a subset of said display surface and having a known position relative to said first position, said tracker mode scanning light pulse continuing until detected by said light sensor at a second position, said tracker mode scanning light pulse being generated by sequentially activating at least some of said cells in said subset at other than said fixed times, and
- D. repeating step C with said second position replacing said first position.
Dependencies are inferred from the claim text.