Backlight module is the key to LCD panel? One of the ingredients, due to the liquid crystal itself? The function of lighting and backlight module is to provide sufficient and evenly distributed light sources, so that it can display images normally. Liquid crystal panels have been widely used in monitors, notebook computers, and? Do cameras and projectors have growth potential? Electronic products, thus driving the backlight module and its related? The demand for components continues to grow, and the panel is low-priced? Stimulated, notebook computers, liquid crystal displays and other large-size panels have the greatest demand, which is the main driving source for the growth of backlight module demand and the second key for backlight module to be used as liquid crystal panel. Component.
Backlight module is the second key of LCD panel? parcel
Second, the backlight module? Don't:
Generally speaking, backlight module can be divided into front light type and backlight type. And the backlight type can be divided according to the requirements of its scale and the position of the lamp? , develop the next one? Three major structures:
(1) side light structure: the light source is a single light source placed on the side, and the light guide plate is injection-molded without printing design, which is generally used for small and medium-sized backlight modules below 18 inch. The light source with the incident side is designed to be light in weight. Thin, narrow frame, low power consumption, and suitable for mobile phones and individuals? Osuke？ (PDA), the light source of notebook computer, also has a large backlight module with side light structure at present.
(2) Bottom lighting structure: the backlight module with super-large size, and the side lighting structure can no longer be used. , consumption of electricity? And have an advantage in the world, so? The light source of the light guide plate is placed directly under the direct structure? Developed? . The light source consists of spontaneous light source (? Such as lamp tubes, light emitting diodes
) after being reflected by the reflecting plate, it is uniformly diffused upwards through the diffusing plate, and then exits from the front. With the increasing installation space, more than two tubes can be used according to the size of the TFT panel, but at the same time, the number has also increased. How thick is the module? , heavy? , power consumption? Its advantage is Gao Hui? 、? Good angle of light, light? Use effect? Tall and simple in structure? Wait, so it suits portability and space requirements? Be picky about LCD monitors and LCD TVs. Are they high in power consumption? (use? Cathode tube), uniformity? Problems such as heating caused by liquid crystal still need to be improved.
(3) Hollow-out structure: With the increase of the required image size, LCD also faces? The direction of large-scale development, now this? The super-large LCD was photographed? As a monitor and wall-mounted TV, only large screen, high and light are required. Is there a high demand for electrical work? Under the low heat effect, the recently developed hollow structure backlight module uses a hot cathode tube as the light source. This structure uses air as the transmission medium of the light source, and the light source covers downward. After the lens and the reflector adjust the direction and reflect, one part passes upward through the exit surface of the light guide plate, and the other part is reflected again by total reflection. Enter the cavity until it passes through the light guide plate after refraction and reflection, and the upward light source either enters the light guide plate directly or exits after reflection: what shape is the light guide plate? It is a wedge-shaped structure, which aims to achieve homogenization effect.
Key optics of backlight module? Component introduction:
Backlight module mainly provides uniform and high brightness light source for LCD panel. The ordinary point or line light source is converted into a high and uniform Ikki by a simple and effective optical mechanism. Surface light source products. What is the general structure? Use? The linear light source of the cathode tube enters the light guide plate through the reflector, and the transformed linear light source is distributed into a uniform surface light source, and then the light is homogenized through the diffuser. The light collection function of the lens improves the uniformity of the light source? . Here we introduce several basic components of backlight module.
3. The backlight module consists of light source, light guide plate, plastic frame (shell), reflector, diffuser, sequins (BEF, prism sheet), black and white adhesive tape, etc. Due to the increasingly thin backlight requirements, some parts need to add metal frames.
diffuser
Material: made of PET or PC, with smooth front and rough back.
Manufacturing method: 1. A diffusion layer (made of transparent resin mixed with light diffusion material) is coated on the PET substrate.
2. Using PC as the base material, the uneven rough surface is formed by hot pressing with a roller.
Identification method: PET material will be slightly yellow when light passes through; When light passes through, the PC material will be slightly blue.
Function:
Upper diffuser: 1. Correct the angle of light.
Protective prism sheet
Lower diffuser: evenly diffuse and reflect the light source, cover the dot, and prevent scattering points from appearing on the front.
Brightening film
Manufacturing material: serrated or wavy PMMA microstructure is coated on the PET substrate.
There are two kinds of prism sheets. The difference is that the microstructure directions on the substrate are different (perpendicular to each other).
Function: improve the front brightness.
Type:
BEF Ⅱ-(regular prism) increases by about 60% in one direction, while the overlap of two vertical directions can increase by 120%.
BEF Ⅲ-(irregular prism to avoid interference) increases by about 59% in one direction, while the overlap of two vertical directions can increase by11%.
RBEF-Microstructure is arc rather than right angle, brightness contrast: BEFⅱ& gt；; Comparison of RBEF perspectives: RBEF & gt；; BEF
DBEF-3M patent, the structure is made up of multilayer reflective polarizers, which can change the direction of light and reuse it after reflection.
Reflective sheet
Material: PET and PC substrate with reflectivity of 90%.
Function: Reflect the incident light from the lamp tube and scatter the light source.
Light Guide Plate
As the propagation medium of backlight module light source, the linear light source emitted by CCFL is converted into a surface light source.
Material: PMMA-optical acrylic board, namely plexiglass.
Features: low surface roughness and good optical performance.
Function: receive light source and guide the scattering direction of light.
Type: printing (printing diffusion points by screen printing), non-printing (making with tools with set points or lines).
Non-printing includes machining, etching and paper replacement.
Direct type (light source is at the back of the light guide plate) and side type (light source is at the side)
Rectangular, wedge, arc, etc.
Screen printing: Hot-dried or UV ink (light source material SiO _ 2/TiO _ 2 with diffusion and reflection characteristics) is used as printing raw material and coated on the reflective surface of LGP to make dots, which destroys the total reflection of LGP and makes the incident light have scattering characteristics, forming diffuse reflection effect and uniformly emitting from the front of LGP.
Dot arrangement: from sparse to dense, from small to large.
Light source:
Cold cathode lamp tube (CCFL): Under high pressure, high-speed electrons collide with mercury atoms, and the mercury atoms quickly return to a stable state from an unstable state. Energy is released in the form of ultraviolet rays (wavelength 253.7nm), which are absorbed by fluorescent powder and converted into visible light.
Function: provide light source
Lampshade: concentrate the incident light and guide it into the light guide plate for heat dissipation.
ALSET material, its main structure is to attach a layer of white reflector to the metal substrate, and the reflectivity can be increased by silver plating or attaching silver to the reflector surface.
Other components:
Plastic frame: supports and protects the internal materials.
Aluminum plate: provide bottom support and fix the circuit board.
Optical specifications for backlight touch group detection;
Detection items such as central brightness, central chromaticity, 9-point average brightness and 9-point brightness uniformity.