Minimizing monitor energy consumption is an important goal, and energy-saving models are readily available. When these phosphor colors converge, they create the millions of colors available. The monitor's glow is emitted from phosphors in a layer at the front of the screen. In these monitors, liquid crystals are sandwiched between polarizing filters and charged by transistors.
Fluorescent tubes provide the light source, which comes from behind the crystal layer.
The voltage level applied by the transistors is what varies the colors and shades and brightness to produce the images. Full voltage across the crystals creates black, and color uses some state in between. As LCD manufacturers make improvements to compete with the cheaper CRT monitors, other performance differences that were a problem with older LCD models, such as lower contrast, brightness, and color display, have become less of an issue for general users. Coupled with the computer's graphics card, a CRT monitor can produce a sharp image in more than one resolution. For example, a CRT monitor may be capable of a maximum resolution of 1,280 x 1,024 pixels, but to enlarge the type and images on the screen, the user can change the resolution to 800 x 600 pixels without losing sharpness.