Backlight and edge light refer to two different lighting techniques used in LCD displays.
Backlight refers to a source of light placed behind the LCD screen, This light illuminates the screen from the back, making the image on the screen visible. The backlight is usually provided by a set of LED lights or a single light guide panel (LGP) that are positioned behind the LCD screen. The LGP distributes light evenly across the screen and provides a bright and uniform backlight.
Edge light, refers to a lighting technique where the source of light is placed along the edges of the LCD screen. This light is then guided by a set of light pipes or guides to the center of the screen, where it illuminates the LCD pixels.
One of the main differences between backlight and edge light is the way in which they illuminate the LCD screen. In backlighting, light is distributed evenly across the entire screen, resulting in a bright and uniform image. In edge lighting, the light is distributed from the edges of the screen and guided to the center, resulting in a less uniform illumination. This can lead to darker areas along the edges and corners of the screen, which can be noticeable in some displays.
Another difference between backlight and edge light is the way in which they are implemented. Backlighting requires more space behind the LCD screen to accommodate the LED lights or LGP. This makes it more challenging to implement in thin displays. Edge lighting, on the other hand, is more compact and can be implemented in the thinner displays, as the light source is located along the edges.
One more difference is the level of control over the brightness and color temperature of the screen. In backlighting, it is easier to adjust the brightness and color temperature of the screen, as the LED lights or LGP can be adjusted to produce the desired light output. In the edge lighting, adjusting the brightness and color temperature of the screen is more challenging, as the light is distributed from the edges of the screen and may not be as uniform as in backlighting.
Cost of implementing backlight and edge light also different. Backlighting is generally more expensive than edge lighting.