Dead pixels are defects of LCD production. These can be caused by misalignment, improper cuts of the components, and even dust particles landing on LCD matrix can lead to “dead pixels”.
Generally LCD panels that leave the factory for installation in laptops or for parts resale have been inspected for dead pixels. Over the years the quality control standards for LCD’s improved dramatically, and as the technology became more affordable, factories can now afford to dispose of most obvious defects that would have been let out “in to the wild” just a few years back.
Still, most LCD manufacturers, and by extension laptop vendors allow some amount of pixel defects to be present for them to consider product 100% functional.
Dead pixels that can be observed “in the wild” can be divided into three sub-categories: Dark pixel, Bright Pixel, Dark/Bright Sub Pixel.
Each pixel on a typical LCD panel is made up of three sub-pixels: Red, Green and Blue. Pixel defects can happen to an entire pixel (all three sub-pixel affected), or can only affect one or two colors in the sub-pixel.
So what can be wrong with a pixel?
Due to dust, misalignment or other factors such as undue pressure or shock, pixels may never “turn on” – meaning they will never pass the light from the backlight, and will remain dark, these are called Dark Pixels. Pixels also may never turn off – meaning the pixel will always stay transparent and the light from the backlight will traverse through the pixel freely, these are called Bright Dots.
Any of the above can happen to an individual sub-pixel by itself to make a partial pixel defect. These are not as noticeable since typically they are three times smaller, but if they remain bright, they can still be well visible and thus fairly annoying.
What can be done about dead pixels?
Typically dead pixels cannot be fixed, however any “dead” pixel can be a “stuck pixel” that may only be experiencing problems intermittently. Stuck pixels can appear due to shock, pressure or long periods of electrical inactivity, but unlike dead pixels, stuck pixels are not permanently dead, and can be revived.
Stuck pixels can sometimes be brought to life by:
– Running imaging software that circulates color patterns on your screen for a duration of time, which may help nudge the stuck pixels into normal operation.
– Sometimes stuck pixels can be gently massaged into operation, this typically affects Dark dots best – since they are off due to a lack of electrical contact.
– Some methods include applying heat to the LCD surface, we have never seen this method work for us, and we don’t recommend it as further damage to working pixels may be caused.
What does LaptopScreen.com do about dead pixels?
LCD Manufacturer’s and specific laptop Vendor’s pixel policy still allows a certain number of defects for them to “close their eyes” on the problem and claim it to be fully functional. At the time of writing, typical dead pixel policy allows up to four Dark Dots in conjunction with no more than two Bright Dots for the LCD panel to be considered 100% functional. Such general policy is understandable, however it does not acknowledge the difference a Bright Dot in a corner makes compared to the same Bright Dot right smack in the center of the screen.
Unlike laptop vendors, LaptopScreen.com does make a determination that some types of pixel arrangement, like an annoying bright dot in the center, does definitely affect the viewing experience. And thus we will exchange any screen, even with-in general “dead pixel allowance”, if the customer is unhappy with the image of the panel they have received from us. Simply contact our Support Department if you have been the “lucky one” to find an annoyance.
Please note, due to continual improvement of LCD manufacturing process, rising affordability of the technology and because of LaptopScreen.com’s unrelenting negotiations with suppliers, dead pixels are almost extinct. Chances of finding a dead pixel on one of our screens is about one in a thousand.