LCD display contrast the scope of how much in the end?

I just start with a display SAMSUNG T190, which claims to the 20000:1 contrast, what the parameters were in sight more obvious? LCD display brightness are the scope of how much? Eyes seem obvious? (CRT will work with the poor is how? ) I am worried about is the quality of the machine to errant Thank you! ! ~

now on the highest to 25000:1, Samsung is also the company's! If you do not Cha Taiduo contrast with 2000 than 5000's with the human eye can not see, but if in 2000 with more than 20,000 effect is quite clear, especially when the darkness of a movie camera scenes of 20000:1 can be seen in 2000:1 can not see the details! I have used is the T190