LED & LCD TV Explained


LED & LCD TV Explained

LCD stands for “liquid crystal display” and technically, both LED and LCD TVs are liquid crystal displays. The basic technology is the same in that both television types have two layers of polarized glass through which the liquid crystals both block and pass light. So really, LED TVs are a subset of LCD TVs.

LED, which stands for “light emitting diodes,” differs from general LCD TVs in that LCDs use fluorescent lights (Cold Cathode Flourescent Lamps) while LEDs use light emitting diodes. Also, the placement of the lights on an LED TV can differ.

The fluorescent lights in an LCD TV are always behind the screen. On an LED TV, the light emitting diodes can be placed either behind the screen, (DIRECT LED) or around its edges (Edge Lit LED TV). The difference in lights and in lighting placement has generally meant that LED TVs can be thinner than LCDs. It has also meant that LED TVs run with greater energy efficiency and can provide a clearer, better picture than the general LCD TVs.

LED TVs provide a better picture for two basic reasons. First, LED TVs work with a color wheel or distinct RGB-colored lights (red, green, blue) to produce more realistic and sharper colors. Second, light emitting diodes can be dimmed. The dimming capability on the back lighting in an LED TV allows the picture to display with a truer black by darkening the lights and blocking more light from passing through the panel. This capability is not present on edge-lit LED TVs but only on Direct LED TVs.

The above diagram shows how local dimming effectively allows the possibility to dim the specific LEDs in the backlight array to drastically increase the contrast, improving the black levels while simultaneously brightening bright areas of the image ! This can be seen on the Philips 9000 series of LED TVs !