| There are two main types of the LED HDTV, and | | | | problem. |
| they can be split into two different versions by the | | | | The Problems With Local-dimming |
| type of back lighting they use. One is called an edge-lit | | | | As ever with all of this technology, there is a downside |
| LED and the other is known as a back-lit LED | | | | to this idea. The problems occur when one block of |
| television. In this article we will look at the back-lit LED | | | | lights is covered by a light and a dark part of the |
| HDTV and try to understand how it works. | | | | image. This will then have the same problems |
| What is a Back-lit LED HDTV? | | | | associated with an LCD TV where the block cannot |
| All TVs of this type are lit by LED lights, which have | | | | be switched of completely, and so it is impossible to |
| been shown to give some advantages over other | | | | get the black part completely dark. |
| types of lighting. Back-lit LED televisions have the LED | | | | There is a way to resolve this issue, and that would be |
| lights placed directly behind the screen, which is similar | | | | to have one LED light for every pixel on the TV |
| the the way an LCD TV has it's lighting arranged. | | | | screen - but the problem with this is that it would be |
| These LED lights are placed into blocks, and are | | | | far to expensive to build a TV in this way and so they |
| grouped together so that they can be controlled at the | | | | would be too expensive for most people to buy. |
| same time. Therefore, each block has the ability to be | | | | However, with all things taken into account, this method |
| switched off and on separately to the other blocks | | | | of building a back-lit LED HDTV does generally |
| around it. The advantage of this is that in an image | | | | produce a TV with a better picture than that of most |
| with some dark areas and some light areas, the dark | | | | LCD TVs. |
| parts can have their blocks switched of completely to | | | | LED HDTV Summary |
| enable an completely black signal. | | | | So as we can see, there is actually more than one |
| This extra control isn't possible on an LCD television. | | | | type of LED HDTV that you can buy, and the way |
| Local-dimming Technology | | | | that it is built can have a big effect on the quality of |
| The name of this technique is local dimming, and this is | | | | the picture that you get. So if you are looking to buy |
| the term you should be looking for if you want to buy | | | | an LED television then it is important to understand the |
| an LED TV that is built in this way. The main | | | | differences in design because they can have a big |
| advantage is an LED HDTV with this type of | | | | impact on the performance of the TV. |
| technology may have a better contrast ratio than | | | | Back-lit LED HDTVs also have a couple of other |
| other types of high-definition television. LCDs have | | | | disadvantages when compared to edge-lit models - or |
| always traditionally had a problem with a poor contrast | | | | LCD televisions for that matter. You can find out more |
| ratio compared to that of a plasma TV, and so this | | | | about these issues by visiting the links in the resource |
| method of backlighting is aimed at addressing this | | | | box below. |