US 6,069,597 A · Circuit and method for controlling the brightness of an FED device

Abstract

A circuit and method for controlling the brightness of a display screen implemented using a flat panel field emission display (FED) screen. Within the FED screen, a matrix of rows and columns is provided and emitters are situated within each row-column intersection. Rows are activated sequentially and separate gray scale information is presented to the columns. When the proper voltage is applied across the cathode and anode of the emitters, they release electrons toward a phosphor spot, e.g., red, green, blue, causing an illumination point. The present invention includes brightness control circuitry positioned across the row drivers for altering the applied voltage to the rows causing a change in brightness cross the FED screen. The applied voltage can be pulse width modulated or amplitude modulated to alter the brightness of the FED screen. Because the relative column voltages remain constant within the present invention, gray scale resolution is not compromised as brightness is altered. Within one FED screen implementation, it is more efficient to alter the row voltage; however, in an alternative embodiment of the present invention the column voltages are modulated in amplitude or pulse width to alter the brightness of the FED screen. The brightness circuitry of the present invention can be made responsive to a manual brightness knob or can be responsive to an ambient light sensor.

Claims20

Dependent claims

A field emission display (FED) screen comprising:

a brightness signal indicating a brightness level for said field emission display screen;
a plurality of column drivers each coupled to a respective column line, said column drivers for driving amplitude modulated voltage signals over column lines;
a plurality of row drivers each coupled to a respective row line, said plurality of row drivers for driving a first voltage signal over one row line at a time, wherein a pixel is comprised of intersections of one row line and at least three column lines;
a horizontal synchronization clock signal for synchronizing the refresh of individual row lines;
and
a brightness control circuit coupled to receive said brightness signal and coupled to enable said plurality of row drivers, said brightness control circuit for generating a row on-time pulse having a width that varies proportional to said brightness signal and generated in synchronization with said horizontal synchronization clock signal, and wherein said plurality of row drivers are enabled to apply said first voltage signal only during said on-time pulse and disabled otherwise.

3 more elements

A field emission display screen comprising:

a plurality of column drivers each coupled to a respective column line, said column drivers for driving amplitude modulated voltage signals over a plurality of column lines, wherein said amplitude modulated voltage signals represent gray-scale data for a respective row of pixels;
a plurality of row drivers each coupled to a respective row line, said plurality of row drivers for driving a first voltage signal over one row line at a time, wherein a pixel is comprised of intersections of one row line and at least three column lines;
a horizontal synchronization clock signal for synchronizing the refresh of individual row lines and for synchronizing the loading of said gray-scale data into said plurality of column drivers;
a brightness control circuit coupled to enable lines of said plurality of row drivers for generating an on-time pulse having a variable width and synchronized with said horizontal synchronization clock signal wherein said plurality of row drivers are enabled to drive said first voltage signal only during said variable width on-time pulse and disabled otherwise;
and
a plurality of multi-layer structures situated at intersections of respective row lines and respective column lines, each multi-layer structure for illuminating at a brightness that is linearly proportional to said width of said on-time pulse.

3 more elements

A field emission display screen comprising:

a plurality of column drivers each coupled to a respective column line, said column drivers for driving amplitude modulated voltage signals over column lines;
a plurality of row drivers each coupled to a respective row line, said plurality of row drivers for driving a first voltage signal over one row line at a time, wherein a pixel is comprised of intersections of one row line and at least three column lines;
a horizontal synchronization clock signal for synchronizing the refresh of individual row lines and for synchronizing the loading of gray-scale data into said plurality of column drivers for a row of pixels;
and
a brightness control circuit coupled to enable lines of said plurality of column drivers, said brightness control circuit for generating an on-time pulse having a variable pulse width and synchronized with said horizontal synchronization clock signal, wherein said plurality of column drivers are enabled to drive said amplitude modulated voltage signals during said variable pulse width of said on-time pulse.

2 more elements

Dependencies are inferred from the claim text.

Circuit and method for controlling the brightness of an FED device

Life of this patent

Circuit and method for controlling the brightness of an FED device

Life of this patent

Abstract

Claims20