Gas display panel with light pen
First Claim
1. A gas panel of the type having row and column coordinate wires forming a matrix of light emitting cells, means for applying a sustain voltage to said row wires and a different sustain voltage to said column wires to produce an alternating polarity sustain voltage across each cell to produce a succession of brief light flashes from any previously written cell, and means for addressing particular row and column wires for write and erase operations, the improvement comprising,means for disturbing the timing of the leading edge of a sustain voltage of the cells of an addressed coordinate wire, whereby each previously written cell of the addressed coordinate produces a light flash at a time different from the light flash of other previously written cells, andmeans including a light pen positionable at a cell of the array for detecting a light flash at the time of the leading edge of the disturbed sustain voltage and for signalling the address of the addressed coordinate.
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Accused Products
Abstract
An improved light pen is provided for a gas display panel of the type in which an alternating polarity sustain voltage produces a succession of brief light flashes in a matrix of light emitting cells. The timing for the sustain voltage is disturbed along a selected coordinate of the matrix. The coordinate of a light pen is identified when light with this disturbed timing is detected by the pen. Circuits for disturbing the sustain voltage of an individual cell of the matrix are also disclosed.
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Citations
7 Claims
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1. A gas panel of the type having row and column coordinate wires forming a matrix of light emitting cells, means for applying a sustain voltage to said row wires and a different sustain voltage to said column wires to produce an alternating polarity sustain voltage across each cell to produce a succession of brief light flashes from any previously written cell, and means for addressing particular row and column wires for write and erase operations, the improvement comprising,
means for disturbing the timing of the leading edge of a sustain voltage of the cells of an addressed coordinate wire, whereby each previously written cell of the addressed coordinate produces a light flash at a time different from the light flash of other previously written cells, and means including a light pen positionable at a cell of the array for detecting a light flash at the time of the leading edge of the disturbed sustain voltage and for signalling the address of the addressed coordinate.
Specification