A liquid crystal display device includes a first substrate, a second substrate and a liquid crystal layer. By adding a path for a noise to pass through, the noise is differentially processed through two paths which have the same electrical conditions with each other. The present invention also discloses a liquid crystal display device incorporated with the backlight module disclosed. A value of at least one first ray is compared to a first threshold. As a result, the number of times buttons need to be actuated by the user to enter a character string can be significantly reduced.