What Is the Difference Between Grade A & B LCD Screens?

Liquid crystals in an LCD screen change their opacity when electricity passes through them. Because they can be transparent or opaque -- depending on the current flowing through them -- they have the ability to produce images you see on the monitor, television or other LCD device. Because LCD devices can have imperfections that lower their value, manufacturers and distributors grade LCDs using letters of the alphabet, such as A+, A, B and C.

Grade A LCDs are high-quality screens that have fewer imperfections than Grade B LCDs. Grade A LCDS do not have scratches, marks or lines. They also can't have spots in the central viewing area, light leakage or dead pixels. Grade A+ LCDs have the highest quality screens and very few imperfections. A Grade C LCD has the greatest number of defects and can have lines that are unnoticeable on RGB backgrounds. Grade C LCDs can also have light leakage.

While still acceptable, Grade B LCDs could have dead pixels and scratches that are not in the central viewing area. Although a Grade B LCD can have marks, you won't be able to see them on blue backgrounds. Lines are also unnoticeable on gray scale backgrounds. Like Grade A units, Grade B units do not have light leakage. Grade A LCDs can have up to three spots and Grade B units may have up to six.

If you don't mind living with some of the defects that refurbished Grade B LCDs have, you can save money by choosing one of those instead of a Grade A LCD that's higher quality. Even though Grade B LCDs may have scratches, they won't be in the central area of a TV or monitor where your eyes probably focus the most. If you work with digital imaging and video production, you may prefer to pay extra for a high-quality LCD. Before you purchase a used or refurbished LCD, ask the seller about potential defects the unit may have. When you can view an LCD screen in person, look for lines, dead pixels and other problems that you can only see when the unit is on.