Method and device for uniforming luminosity and reducing phosphor degradation of a field emission flat display

A field emission display (FED) comprising a cathodic structure in the form of conductive strips defined on a dielectric substrate and having field stimulable electron emission sites distributed over their surface, each strip being individually biasable in sequence by a column scanning circuitry of a pixel driving matrix of the display, which driving matrix comprises conductive extractor strips orthogonal to said columns, selectable in sequence by a row selection circuitry, characterized in that it comprises

• a first nonvolatile memory capable of storing values of relative emission efficiency of each pixel reflecting a compound emission efficiency of the cathodic and anodic structure of the display as measured during a testing of the device;
• a logic circuit capable of sequentially stimulating each row with a constant biasing signal, reading the value of the current through each column driving stage, generating a value of relative emission efficiency of the cathodic structure alone for each pixel, and combining said value with the corresponding value stored in said first nonvolatile correction memory;
• at least a second electrically alterable memory, capable of storing said combined value of relative efficiency of each pixel when turning-on the display;
• said second memory storing a matrix of correction values that are read at every screen refreshing.

A field emission display (FED) system comprising:

• a cathodic structure having individually selectable columns comprised of conductive strips defined on a dielectric substrate and field stimulable electron emission sites distributed on a surface of said strips;
• conductive extractor strips forming rows orthogonal to said columns;
• a pixel driving matrix connected to bias individual ones of said columns and rows to stimulate selected ones of said sites;
• a correction memory array programmable during a testing phase of the display capable of storing relative emission efficiency values of each individual pixel of the display;
• a correction circuit connected to receive a video signal and the value of a memory cell which corresponds to said video signal, and connected to provide said pixel driving matrix with a column driving signal derived from said value and said video signal;
• wherein said testing phase is entered when said display is powered on.

A field emission display (FED) system comprising:

• a cathodic structure having individually selectable columns comprised of conductive strips defined on a dielectric substrate and field stimulable electron emission sites distributed on a surface of said strips;
• conductive extractor strips forming rows orthogonal to said columns;
• a pixel driving matrix connected to bias individual ones of said columns and rows to stimulate selected ones of said sites;
• a correction memory array programmable during a testing phase of the display capable of storing relative emission efficiency values of each individual pixel of the display;
• a correction circuit connected to receive a video signal and the value of a memory cell which corresponds to said video signal, and connected to provide said pixel driving matrix with a column driving signal derived from said value and said video signal;
• wherein said testing phase is entered periodically during use of said display.

A field emission display (FED) system comprising:

• a cathodic structure having individually selectable columns comprised of conductive strips defined on a dielectric substrate and field stimulable electron emission sites distributed on a surface of said strips;
• conductive extractor strips forming rows orthogonal to said columns;
• a pixel driving matrix connected to bias individual ones of said columns and rows to stimulate selected ones of said sites;
• a correction memory array programmable during a testing phase of the display capable of storing the current ouput of each individual pixel of the display;
• a correction circuit connected to receive a video signal and the value of a memory cell which corresponds to said video signal, and connected to provide said pixel driving matrix with a column driving signal derived from said value and said video signal;
• wherein said testing phase is entered when said display is powered on.

A field emission display (FED) system comprising:

• a cathodic structure having individually selectable columns comprised of conductive strips defined on a dielectric substrate and field stimulable electron emission sites distributed on a surface of said strips;
• conductive extractor strips forming rows orthogonal to said columns;
• a pixel driving matrix connected to bias individual ones of said columns and rows to stimulate selected ones of said sites;
• a non-volatile first correction memory array containing values corresponding to emission efficiency values of each individual pixel of the display as determined at time of manufacture;
• a volatile second correction memory array programmable periodically during a test phase of the display capable of storing relative emission efficiency values of each individual pixel of the display as determined at the time of each testing;
• a correction circuit connected to receive a video signal and the value of a memory cell of each of said memories which corresponds to said video signal, and connected to provide said pixel driving matrix with a column driving signal derived from said value and said video signal;
• wherein said testing phase is entered when said display is powered on.