Positive and Negative
Display Modes
What types of image the
display creates is a cosmetic issue. There are only two basic display modes,
positive and negative.
Positive Mode
A positive image on an LCD display is opaque when the pixel is "ON", and
transparent when the pixel is "OFF". On almost all displays the
image is smaller than the background, so this mode of operation is favored
in an application where ambient light is high and it will help with the
contrast of the display, especially for a display utilizing a Reflective
rear polarizer. An example would be a alpha-numeric character on a larger
background. The segments or dots on the character would absorb light
(appearing dark) and the background (the larger area) would reflect light
enhancing the characters. Here are several typical Operational Mode &
Viewing Mode combinations and the resulting images (assuming no backlighting
which can color the background):
- TN: Black characters on a Gray background
- STN-Green: Dark Violet / Black characters on a Green background.
- STN-Silver: Dark Blue / Black characters on a Silver background
- FSTN: Black characters on a White / Gray background
Negative Mode
A negative image on an LCD display is opaque when the pixel is "OFF",
and transparent when a pixel in "ON". Since the image area is typically
smaller than the background, the portion of the display that could reflect
light and give the characters definition in this mode is minimized.
Therefore, this mode is typically only used when there is a backlight and
the ambient lighting conditions are medium to dim. Using a backlight, the
transparent segments of the display will "glow" because the backlight will
be viewable only when the pixels are turned on. A high ambient light
condition could wash out the backlight. Here are several typical Operational
Mode & Viewing Mode combinations and the resulting images (assuming a
backlight with the specified coloration listed):
- TN: Glowing Green-Yellow characters on a light Gray background (Green-Yellow
Backlight)
- STN ("Blue-Negative"): Glowing Green-Yellow characters on an light Blue
background (Green-Yellow Backlight)
- FSTN: Glowing White characters on a Black background (White Backlight)
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