Analysis of the principle of led backlight structure
2020-12-17
LED backlight structure As can be seen from the above figure, the manufacture of LED backlights starts with making a light guide plate from acrylic resin, then making a white dot pattern that scatters the light on the light guide plate, and then attaching reflective films, diffusers, prism films and other optics. Diaphragm, and assemble, then assemble LED light reflector, etc., to assemble the backlight source. Structure and principle of led backlight light guide plate As shown in the figure above, the LED SMD lamp backlight needs to transmit the light emitted by the SMD lamp forward while being totally reflected in the light guide plate. The reflection point pattern at the bottom of the light guide plate changes regularly, and the incident angle is smaller than the total reflection angle. Part of the light energy is emitted from the surface of the light guide plate, turning the linear light source into a surface light source As shown in the figure above, the reflective dots at the bottom of the light guide plate are white dot patterns formed by screen printing. The dots have a small diameter and a small number near the lamp; and the dots far away from the lamp have a large diameter and large number; At the farthest part from the lamp, because of the reflective diaphragm, the dot diameter is slightly smaller and the number is slightly smaller. This setting ensures that the brightness of the entire display is uniform.
(1) Before injection molding starts, first open the mold and keep a certain gap.
(2) Fill the mold with resin.
(3) With filling, the pressure in the mold increases, and the gap for mold opening increases with the extension of the positioning rod.
(4) Before the resin filling is completed, fill the mold cavity with resin completely, and then press at high speed after the filling is confirmed by detection.
(5) After the resin is filled, step pressure control is performed while maintaining pressure.
(6) The final pressure is maintained until the cooling is completed, and the light guide plate is made after cooling. Structure and principle of led backlight The brightness enhancement film is used to increase the brightness of the screen. It is divided into two types: refraction enhancement film (upward prism) and total reflection enhancement film (downward prism). The refraction-type brightening sheet is formed by transferring a plastic resin film under high pressure. As shown in the figure above, the apex angle of the refractive diaphragm is 90 degrees, and the upper and lower parts are orthogonal to each other. In order to produce the off-angle effect, a lower diffusion film (referred to as the diffusion film) is installed at the lower part, and a light guide plate, a reflective film, etc. are further provided; a white dot pattern is also printed under the light guide plate. Using the scattering effect of this pattern, an outgoing beam of about 60 degrees is generated, and then the scattering and refraction effect of the lower diffuser is used to turn into a 30-degree outgoing beam, and the refraction-type light-enhancing sheet is further used to make the beam normal direction to the display screen. In this way, the two light-increasing sheets orthogonal to each other concentrate the components on the light surface in the normal direction, thereby improving the brightness. In this mechanism, due to the Fresnel reflection loss and light absorption loss, the light utilization rate is reduced.
The total reflection type light-increasing sheet is formed by using a UV-curable resin on a polyester film to transfer the shape of the light-increasing sheet. As shown in the figure above, the apex angle of this kind of prism film is 60-70 degrees, and it is used in combination with diffuser film, light guide plate with lens, reflective film, etc. For the light beam emitted from the light guide plate at 65-70 degrees, the total reflection effect makes its normal direction into the display screen. Compared with the refraction-type brightness enhancement sheet, it uses fewer parts and materials, and because the total reflection of the light is used, the Fresnel reflection loss and the light absorption loss are small, so that the light utilization rate is improved. Structure and principle of reflective film for led backlight The LED backlight reflective film is usually set at the bottom of the light guide plate to reflect light inside the light guide plate to reduce the attenuation of the traveling light; while the reflective film located around the lamp tube is to take out the light efficiently. Structure and principle of led backlight diffusion film Diffusion film, also called astigmatism film, is used to increase light diffusion, prevent display mottle, and improve the brightness of LCD screen. Some of the production methods are to roughen the surface of the PET (poly ethylent terephthalate) film, and some are to seal the surface of the PET.
