The difference between LED TV direct type and side entry type and its advantages and disadvantages

Direct-lit, Direct Illumination-type LED Backlight was widely adopted by TV manufacturers at the beginning of publication; the direct type is to arrange LED crystals evenly behind the LCD panel as a light source. The backlight can be evenly transmitted to the entire screen, and the details of the picture are more delicate and realistic.

Sharp XS1 series LCD TV with direct-lit LED backlight

However, more LED dies are needed than the side-lit LED backlights. The advantage of the direct-lit type is that different backlight module responsibilities can be set separately.

In theory, it is also possible to control the brightness of each LED independently, but 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.

A large-size LCD TV with a direct-lit LED backlight requires thousands of LED dies, 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 die is arranged on the periphery of the liquid crystal screen, and then the light guide plate is used to make the LED backlight module emit light, and the light emitted from the edge of the screen is transmitted through the light guide plate to the center of the screen. Go, so that there is enough backlight in the whole, so that the LCD screen can display.

There are two advantages of the edge-lit LED backlight. One is that it can use fewer LED dies, which saves cost. The second is to create a slim and light body, so that LEDs on the rear of the LED TV LCD panel do not need to be configured. The module, but placed on the side, can reduce the overall thickness of the screen, creating a thinner model than the direct-lit LED-backlit LCD TV.

LCD TV with side-lit LED backlight, the body can be very thin

In terms of shortcomings, in addition to the high 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 some blurring (blooming) )The phenomenon. If the direct-type LED backlight module is disposed at the rear of the liquid crystal screen, the higher the LED grain density, or the more the area of ​​the district dimming, the less likely the blurring phenomenon will occur.

Direct-lit LED TVs consume more power than side-lit LED TVs because of the higher number of LED dies, but still save power compared to 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.

Although the thickness of the edge-lit LED TV is relatively small, the number of LED dies 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 to be higher than that of the screen. The center should be bright, and 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 die configurations, improving luminous efficiency, and lowering LED prices. In terms of LED TV, it is necessary to improve the uniformity of the picture.