Controlling the brightness of an FED device using PWM on the row side and AM on the column side

A computer system comprising:

• a) a microprocessor coupled to a bus;
• b) a memory unit coupled to said bus;
• c) an input device coupled to said bus;
• and
• d) a display screen coupled to said bus wherein said display screen is a field emission display (FED) screen comprising:
• d1) a plurality of column drivers for driving amplitude modulated voltage signals over a plurality of column lines wherein each column driver is coupled to a respective column line and receives image data for said respective column line;
• d2) a plurality of row drivers for driving a voltage pulse over a plurality of row lines wherein each row driver is coupled to a respective row line, said plurality of row lines intersecting said plurality of column lines and wherein a subpixel is defined as an intersection of one row line and one column line;
• d3) an enable circuit for enabling only one row driver at a time, said enable circuit coupled to each row driver of said plurality of row drivers;
• and
• d4) a pulse width modulation circuit for generating said voltage pulse wherein said pulse width modulation circuit is for varying the width of said voltage pulse in order to effect brightness within said FED screen without loss of gray scale resolution capability of said FED screen wherein said brightness is linearly related to said width of said voltage pulse.

In a field emission display (FED) screen having a plurality of column lines intersecting a plurality of row lines, a method of adjusting the brightness of said FED screen comprising the steps of:

• a) driving amplitude modulated voltage signals over said plurality of column lines using a plurality of column drivers wherein each column driver is coupled to a respective column line and receives image data for said respective column line;
• b) over time, driving a voltage pulse over said plurality of row lines using a plurality of row drivers, each row driver being coupled to a respective row line and wherein said voltage pulse is driven over only one row line at a time and wherein a subpixel is defined as the intersection of a row and column line;
• and
• c) controlling said brightness of said FED screen, while maintaining gray scale resolution of FED screen, by pulse width modulation of the pulse width of said voltage pulse wherein said brightness increases with an increase in said pulse width and wherein said brightness decreases with a decrease in said pulse width.

A field emission display (FED) screen comprising:

• a plurality of column drivers for driving modulated voltage signals over a plurality of column lines wherein each column driver is coupled to a respective column line and receives image data for said respective column line;
• a plurality of row drivers for driving a voltage pulse over a plurality of row lines wherein each row driver is coupled to a respective row line, said plurality of row lines intersecting said plurality of column lines and wherein a subpixel is defined as an intersection of one row line and one column line;
• an enable circuit for enabling only one row driver at a time, said enable circuit coupled to each row driver of said plurality of row drivers;
• and
• a pulse width modulation circuit for generating said voltage pulse wherein said pulse width modulation circuit is for varying the width of said voltage pulse in order to effect brightness within said FED screen without loss of gray scale resolution capability of said FED screen.