7.4.11

Measuring pixel defects classes: The ISO-9241 way

International standards (ISO-9241) set of specifications for measuring pixel defects.

The International Standards Organization (ISO) has published its own set of
specifications for measuring pixel defects in flat panel monitors, contained within the ISO 9241 set of standards.

These identify three classes for measuring pixel defects in flat panel monitors:

  • Class 0 panels are completely defect-free, including no full pixel or sub-pixel defects.
  • Class 1 panels permit any or all of the following:
    • 1 full bright ("stuck on") pixel
    • 1 full dark ("stuck off") pixel
    • 2 single or double bright or dark sub-pixels
    • 3 to 5 "stuck on" or "stuck off" sub-pixels (depending on the number of each)
  • Class 2 panels permit any or all of the following:
    • 2 full bright pixels
    • 2 full dark pixels
    • 5-10 single or double bright or dark sub-pixels (again, depending on the number of each; no more than 5 bright ("stuck on") subpixels are permitted).
  • Class 3 panels permit any or all of the following:
    • 5 full bright pixels
    • 15 full dark pixels
    • 50 single or double sub-pixels stuck on or off


Defect type definitions

  • Bright/dark dot: A sub-pixel stuck on or off.
  • Bright spots/lines: Spots or lines that appear light in the display. Defects do not
vary in size or intensity (contrast) when contrast voltage is varied. Contrast variation
can be achieved through the use of varying gray shade patterns. This defect may
not completely block the light emitted by any pixels.
  • Cluster: A group of defective sub-pixels which are in close proximity to each other.
  • Cross lines off: When the unit lights, lines in both the minor and major axis do not
appear.
  • Dark spots/lines: Spots or lines that appear dark in the display patterns and are
usually the result of contamination. Defects do not vary in size or intensity (contrast)
when contrast voltage is varied. Contrast variation can be achieved through the use
of varying gray shade patterns. This defect may not completely block the light
emitted by any pixels.
  • Dim line: When the unit lights, line(s) in the minor (vertical) or major (horizontal)
axis appear dim, but not completely on or off.
  • Horizontal line: A line of pixels that crosses the display horizontally in portrait
mode.
  • Mottling: When the unit lights, variation/non-uniformity (splotchiness) appears light
(white) with the display and might vary in size.
  • Newton ring: A "rainbow" effect caused by non-uniform cell thickness.
  • Pixel: A picture element made up of three primary color sub-pixels (red, green, and
blue), which combine to represent a single color dot on the display.
  • Polarizer dent: Physical damage to the polarizer that does not damage the glass.
When the unit lights, spots appear light (white) with display patterns dark and do
not vary in size. This defect may not completely block the light emitted by any
pixels.
  • Polarizer scratch: Physical damage to the polarizer that does not damage the glass.
When the unit lights, lines appear light (white) with display patterns dark and do
not vary in size. This defect may not completely block the light emitted by any
pixels.
  • Rubbing line/defects: Horizontal or diagonal lines that appear gray with the
display patterns dark and may have resulted from an "out of control" rubbing
process on the polyimide or "waves" on the BEFs or prism sheets.
  • Sub-pixel: A single point of light representing a primary color (red, green, or blue),
which combines with the other two primary color sub-pixels to form a complete
pixel.
  • Vertical line: A line of pixels that crosses the display vertically in portrait mode.

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