Hybrid active matrix thin-film transistor display
AssigneeCopytele, Inc.
InventorsFrank J. DiSanto, Denis A. Krusos, Segey L. Shokhor, Alexander Kastalsky
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Abstract
A cold-cathode flat panel display using thin-film-transistor (TFT) anode circuit is disclosed. Associated with each pixel element is a TFT circuit comprising first and second transistors electrically cascaded and a capacitor in communication with an output of the first device and an input of the second transistor used to selectively address pixel elements in the display and hold pixels in their selected states for the frame time. Cold cathode sources are used to emit electrons that are drawn to selected pixel elements that include phosphor areas, which emit light of a known wavelength when struck by the emitted electrons.
Claims38
A flat panel display arranged in a matrix of N rows and M columns comprising:
- a first surface containing an anode thereon, said anode comprising:
- a plurality of electrically conductive areas each associated with a row (N) and a column (M) defining a pixel location;
- a phosphor layer associated with each of said areas;
- a TFT circuit operable to apply a predetermined voltage to an associated one of the conductive areas, said TFT circuit, comprising:
- first and second electrically cascaded transistors;
- and
- a capacitor electrically connected between an output of said first transistor and an output of said second transistor, wherein the capacitor and output of the second transistor are electrically coupled to the associated conductive area;
- and
- a cold cathode, deposited on a second surface, facing said first surface, comprising:
- a conducting layer disposed on said second surface;
- and
- an emitter material disposed on said conducting layer operable to emit electrons when an associated threshold voltage is exceeded.
A display comprising:
- an anode deposited on a first surface arranged in a matrix of N rows and M columns comprising:
- a plurality of electrically conductive areas;
- a phosphor layer associated with each of said areas;
- a TFT circuit operable to apply a predetermined voltage to an associated area, said TFT circuit, comprising:
- first and second electrically cascaded transistors;
- and
- a capacitor electrically connected between an output of said first transistor and an output of said second transistor, wherein the capacitor and output of the second transistor are electrically coupled to the associated conductive area;
- a first grid;
- a cold cathode facing said anode deposited on a second surface, said cold cathode comprising:
- an emitter material operable to emit electrons when a threshold voltage is exceeded;
- and
- a conducting layer underneath said emitter material deposited on said second surface;
- a plurality of spaces electrically isolating said anode, first grid and cold cathode, wherein a vacuum is within said space.
A flat panel display having an anode and a cathode, said display arranged in a matrix of N rows and M columns, wherein the intersection of a row and column constitutes a pixel, in combination therewith the improvement comprising:
- a cold cathode for emitting electrons to be directed to said anode, and
- a TFT circuit for each pixel, said circuit employing first and second active devices in cascade and each coupled between an associated row (N) and column (M) to define a pixel at said location M and N and when activated operative to attract said emitted electrons to said pixel location;
- wherein each said TFT circuit comprises:
- first and second electrically cascaded transistors;
- and a capacitor electrically connected between an output of said first transistor and an output of said second transistor, and the capacitor and output of the second transistor are electrically coupled to the associated pixel.
Dependencies are inferred from the claim text.