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A bright dot defect or hot pixel is a group of three sub-pixels (one pixel) all of whose transistors are "off" for TN panels or stuck "on" for MVA and PVA panels. [2] This allows all light to pass through to the RGB layer, creating a bright pixel that is always on. Another cause of bright dot may be the presence of impurities in the liquid crystal.
The cause of LCD image retention is different from phosphor aging as in CRTs, but the visual phenomenon is the same: uneven use of display pixels. Slight LCD image retention can be recovered. When severe image retention occurs, the liquid crystal molecules have been polarized and cannot rotate in the electric field, so they cannot be recovered.
Three distinct types of defective pixels are described: Type 1 = a hot pixel (always on, being colour white) Type 2 = a dead pixel (always off, meaning black) Type 3 = a stuck pixel (one or more sub-pixels (red, blue or green) are always on or always off) The table below shows the maximum number of allowed defects (per type) per 1 million pixels.
Some LCD panels have defective transistors, causing permanently lit or unlit pixels which are commonly referred to as stuck pixels or dead pixels respectively. Unlike integrated circuits (ICs), LCD panels with a few defective transistors are usually still usable. Manufacturers' policies for the acceptable number of defective pixels vary greatly.
The pixels on OLEDs inevitably lose their brightness over time. The longer an OLED pixel is used (illuminated), the dimmer it will appear next to a lesser-used pixel. [6] In the case of LCDs, the physics of burn-in are different than plasma and OLED, which develop burn-in from luminance degradation of the light-emitting pixels.
When pixels on a row are being addressed, a V sel potential is applied, and all other rows are unselected with a V unsel potential. The video signal or column potential is then applied with a potential for each m columns individually. An on-switched (lit) pixel corresponds to a V on, an off-switched (unlit) corresponds to a V off potential. [1]
LCD crosstalk is a visual defect in an LCD screen which occurs because of interference between adjacent pixels.. Owing to the way rows and columns in the display are addressed, and charge is pushed around, the data on one part of the display has the potential to influence what is displayed elsewhere. [1]
In 2008, LCD TV shipments were up 33 percent year-on-year compared to 2007 to 105 million units. [10] In 2009, LCD TV shipments raised to 146 million units (69% from the total of 211 million TV shipments). [11] In 2010, LCD TV shipments reached 187.9 million units (from an estimated total of 247 million TV shipments). [12] [13]