LCD Screens - Information, Features, Faults, Troubleshooting
Categorized list of all available screens and their substitutes:
Laptopdisplay.eu aims to keep in stock both new and used laptop displays (a.k.a. screens, TFT panels, LCD matrixes), that can be found in over 95% of laptops used nowadays. We offer competitive prices, high quality and excellent customer care.
We can advise you which display to order if you need replacement or upgrade. We need to know the exact model of your laptop.
On this page we are providing some information about laptop screens, their characteristics and common problems, that we consider to be useful for you.
When laptop screen replacement is needed?
These are the most common reasons:
- Broken laptop screen;
- Horizontal or vertical lines on the screen;
- Dark or light blemishes on screen's viewable area;
- Black spots on the screen ;
- Dark (dim) display, backlight not functioning;
- Upgrade from TN to IPS type, from low to high resolution, etc.
LCD (Liquid Crystal Display) generate image by transmitting light through small cells, called subpixels.These cells are full of liquid crystal, that becomes non-transparent when electrically powered. Three neighboring pixels (red, green, blue) form a pixel - a changing color dot. The number of rows and columns of pixels provides one of the main characteristics of the displays - their resolution.
The liquid crystal cells are enclosed between two thin plates of glass. That's why the screens are very fragile.
During manufacturing process liquid crystal may not be enough to fill a cell. This subpixel will always be transparent, thus bright during operation. It will be of red, green or blue color and will not be visible on bright image. This is called a "stuck subpixel". When all 3 neighboring cells are empty, there will be a white "stuck pixel".
When the transistor that should transmit electricity to a certain pixel is faulty, this pixel would be constantly non-transparent (black). This is called a "bad pixel".
Pixel faults are not degenerative. Their number is not growing during usage and they are not considered as a defect, they can be just irritating. Nevertheless, we test all the screens that we sell and lower the price of ones with stuck/dead pixels. We always mention noticed during tests pixel faults in item description.
In some case screens develop faults due to way of use, environmental factors, or just old age.
- Asymmetrical defects - non-functional areas, constantly lit horizontal or vertical lines, uneven backlight.
These image defects are caused by the screen itself and are removed by replacing it. In rare cases the screen may be repaired.
Horizontal line on screen
Brighter left part of the screen
- Defects on entire viewable area - blurred image, wrong colors, shadows, non-functional backlight
These types of defects can be caused both by the screen, or by other computer parts, like interface (ribbon) cable, inverter, graphics adapter (GPU), motherboard, etc. The fault must be diagnosed bu a competent technician.
Upgrade or downgrade
Sometimes the screen needs to be replaced, because it causes discomfort during usage. E.g. in most cases a screen with glossy surface can be replaced with a matte (anti-glare) screen. Matte screens are recommended for outdoor use. Another option is replacing the display with one of higher resolution. Unfortunately it is not always possible. Most laptops with LVDS screen interface support only basic resolution.:
4:3 - 1024*768
16:10 - 1280*800
16:9 - 1366*768
Fortunately newer laptops use eDP screen interface, which provides higher chances for successful upgrade.
On the other hand, you may have a screen with unnecessarily high resolution that shows smaller fonts on certain operating systems that do not offer good scalability. In this case, you may look for a screen with lower resolution, that will be more comfortable for e.g. text writing.
What do we need to know before ordering a screen?
Size and aspect ratio
The main characteristic of the displays is the size of their viewable area, measured in inches.
Aspect ratio is the proportion width/height of viewable area or number of columns/rows of pixels. Years ago computers used the first TV aspect ratio 4:3. It has been gradually replaced with 16:10 (Wide Screen). In the last 10 years both 4:3 and 16:10 displays have been replaced with 16:9.
Nowadays the most common consumer grade laptops have 15.6" displays with 16:9 aspect ratio, while 14" displays are preferred for business laptops. Before 2010 the most common sizes were 15.4" or 14.1" with aspect ratio 16:10.
The most common screen resolutions nowadays are:
- HD Ready 1366x768 (1366 columns x 768 rows of pixels);
- HD++ 1600x900
- Full HD 1920x1080
The higher the resolution, the finer image is.
Backlight is not a spare part, but a function of the laptop. It generates even white light that passes through the liquid crystal matrix that creates colorful image.There are two types of backlight: with a Cold Cathode Luminescent Lamp (CCFL) or with Light Emitting Diodes (LED). Both light sources are an integral part of the display.
The older displays are lit up by a luminescent lamp, 2mm in diameter. This lamp is powered by an external "inverter", generating AC over 600 Volts. These lamps have a relatively high energy consumption and shorter life - on average 10000 hours. At the end of its life the lamp darkens, changes its color to yellow or pink and finally stops to function at all. It may cause damage to the inverter too. A very common situation is a backlight shutting down after a few minutes of operation. It is usually caused by an exhausted lamp, overloading the inverter. The thermal protection of the inverter switches it off to protect damage.
Displays with LED backlight are lit up by a LED strip. It is usually powered by voltage higher than the laptop's operating voltage, and there is an inverter integrated in the screen. LED screens are preferred for their longer life and lower power consumption.
LED backlight has a disadvantage to CCFL - when their brightness control signal has a frequency of 1000Hz or less, there is a hardly noticeable, but tiring out the eyes flickering.It is caused by the way brightness is tuned - using Pulse Width Modulation (PWM). PWM signal is provided by laptop's GPU and can have frequency up to 10000Hz. There is no flickering if the frequency is above 2000Hz. Unfortunately many low-grade laptops use 800Hz-1000Hz PWM. The frequency does not depend on the screen, but on the way the laptop's GPU controls it. If the screen is not fully compatible, GPU may use low frequency to ensure compatibility.
Every screen model comes with different firmware versions for the laptop brand it is intended for. Backlight may flicker if incorrect version of the screen is installed. E.g. a screen for HP may not work correctly on a Lenovo laptop, even if screen's model is the same. That's why it is very important to tell us the brand and model of your laptop, when you order a screen.
There are two types of surfaces - glossy (glare) or matte (anti-glare). The choice is a matter of personal preferences. Glossy screens have a smooth surface, which is an advantage when used for image processing. But glossy screens are unsuitable for outdoor work, because they reflect the environmental light. Laptops do not know and do not care about your screen's surface. You may have options which type to order and you must make a decision which surface is better for you.
Genuine and replicas
LCD manufacturing technology is very complex. Very few factories in the world are capable of producing large (above 10") screens. That's why all laptop screens on the market are genuine. There are less than 10 manufacturers worldwide. Most of their models are interchangeable with another manufacturers'. The characteristics and prices of different manufacturers are almost identical.That's why laptop manufacturers install whichever models are available on the market at a certain moment. Two laptops of a same model and configuration may have installed screens of different brands.
New or used
The answer of this question is a matter of personal preferences too. Common screens have very long life, and most defects do not depend on their age. So used screens are preferred by most of our customers - they get similar quality at a much lower price.
All the screens that we sell are tested. We provide 6 months manufacturer's warranty for new screens, and 1 month warranty for used ones. These periods are long enough for discovery of rare hidden defects, that we have not observed during our tests.