LED backlights are divided into direct-lit and side-lit, each with advantages and disadvantages, as well as cost differences, but in terms of the price of the end products are high and low; research institute LEDinside believes that because ultra-thin TV is increasingly popular, side-light LED TV sales will grow faster and the price will be more approachable. Direct-lit LED TVs are popular with consumers who need high-end audio and video equipment.
Direct-lit, Direct Illumination-type LED Backlight was widely adopted by TV manufacturers at the beginning of the publication; LEDinside said that the direct type is to arrange the LED chips evenly behind the LCD panel. The light source allows the backlight to be evenly transmitted to the entire screen, and the details of the picture are more delicate and realistic.
However, more LED chips are needed than the side-lit LED backlight. The advantage of the direct-lit type is that different backlight module rights can be set separately. In theory, each LED can be independently controlled to control the brightness. However, the line and design cost are not easy. In fact, multiple areas are set in the backlight of the screen, so that these areas can independently adjust the brightness.
LEDinside said that a large-size LCD TV with a direct-lit LED backlight requires thousands of LED chips, which is relatively expensive. Especially when the early LED TV was just launched, the RGB tri-color LED was used to improve the color rendering, the color of the picture could be more vivid, and the cost was naturally high. However, with the use of cheaper white LEDs as backlights in recent years, it is now possible. Adjust to the better level.
As for the edge-lit LED backlight, the LED chip is disposed on the periphery of the liquid crystal screen, and then matched with the light guide plate, so that when the LED backlight module emits light, the light emitted from the edge of the screen is transmitted through the light guide plate to the area in the center of the screen. So that there is enough backlight in the whole, the LCD screen can be displayed.
LEDinside said that there are two advantages of edge-lit LED backlights. One is that fewer LED chips can be used to save costs. The second is to create a slimmer body that does not need to be behind the LED TV LCD panel. The LED module is placed on the side, which reduces the overall thickness of the screen and creates a thinner model than the direct-lit LED-backlit LCD TV.
In terms of shortcomings, LEDinside said that in addition to the higher cost of the direct-lit LED TV, when the bright area on the screen is adjusted to a dark area during the picture conversion process, the gray level of the adjacent picture area is affected and reduced, resulting in a slight The phenomenon of blurring. If the direct-type LED backlight module is disposed at the rear of the liquid crystal screen, the higher the density of the LED chip, or the more the area of ​​the district dimming, the probability of blurring will be relatively small.
Direct-lit LED TVs consume more power than side-lit LED TVs because of the higher number of LED chips, but they are still more power efficient than CCFL-backlit LCD TVs. The advantage of the edge-lit LED backlight technology is that it can build a relatively thin LED TV model, and the cost is relatively cheap; but the shortcoming of the current edge-lit LED backlight is that the picture uniformity is not good.
LEDinside pointed out that although the thickness of the edge-lit LED TV is relatively small, the number of LED chips used is relatively small, and the light is sent to the screen through the light guide plate, which causes the brightness of the peripheral edge of the LED TV. Brighter than the center of the screen, the edge area of ​​the screen will be higher than the temperature in the middle of the screen.
At present, the efforts of manufacturers in various countries are naturally trying to improve the blurring phenomenon, thickness and cost of direct-lit LED TVs. This must be done by optimizing the number of LED chip configurations, improving luminous efficiency, and lowering LED prices. The TV side is to improve the shortcomings of the picture uniformity.
Source: Electronic Engineering Album - Taiwan
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