What Are The Categories Of Optical Films, Do You Know Them All?
Apr 22, 2022
Optical film is a broad sense of optical properties of film products, mainly divided into polarizer and backlight module (BLU) in the optical film two, the main application areas for TFT-LCD LCD panel, polarizer can also be used in the OLED panel. Panel production capacity continues to shift to the mainland, on the one hand, LCD LCD panels, especially large-size products investment growth, driving the growth of optical film demand; on the other hand, the localization of polarizers also brings greater opportunities.
Thin film materials can be divided into functional films (film) and selective separation films (membrane). The application of functional film products on polymer substrates is becoming more and more popular in various fields, especially films with optical functions.
1. Classification of optical films: optical films for polarizers and backlight modules
Optical films are coated or plated with one or more layers of dielectric or metal films or combinations of films on optical components or individual substrates to change the transmission characteristics of light, including projection, reflection, absorption, scattering, polarisation and phase change. The change in transmittance and reflectance gives different properties to light in different planes of polarisation.
Optical films can be broadly divided into two groups: polarizers and backlight modules optical films, the main application area is TFT-LCD liquid crystal panels. LCD mainly consists of liquid crystal, backlight modules, glass substrates, polarizers and TFT electrodes and other major components. Liquid crystal display devices belong to the flat panel display device, its basic structure is multi-layer flat panel shape. Typical LCDs are mainly composed of liquid crystal layers, glass substrates, polarizers and TFT electrodes. Of course, different types of LCD devices may differ in some parts, but all LCD devices are composed of two substrates engraved with transparent conductive electrodes, sandwiched between a liquid crystal layer, packaged into a bias flat box, and then mounted on the outer surface of the polarizer three-layer structure. Among them, the backlight module optical film roughly contains reflective film, diffusion film, ordinary prism sheet, multifunctional prism sheet, micro-lens film, reflective polarisation brightening film and other six kinds.
The cost of LCD panels can be broken down to show that material costs account for more than 70% of the total manufacturing cost of LCD, depreciation costs account for 11%, labour costs, overhead costs, sales and management costs account for 5-6% each. Backlight modules account for 18.2% of the cost of materials, colour filters account for 14.7%, polarizers account for 9.5% and glass substrates account for 8.9%.
The cost of brightness enhancement film, diffusion film and reflective film in the backlight module accounted for 32%, 7% and 2% respectively, with a total of 41%. TAC (cellulose triacetate) film and PVA (polyvinyl alcohol) film are the main raw materials in the polarizer, accounting for 50% and 12% of the cost respectively.
2. Optical film is the key component of LCD backlight module
LCD is currently the most mature technology in the field of flat panel display, the most manufacturers, the product market share is the highest. LCD typical three-layer structure, the liquid crystal layer is distributed with many vertical and horizontal tiny wires, the use of voltage to control the direction of the liquid crystal molecules, the refraction of light out to produce the picture.
The backlight module (BLU) is the key component that provides the light source to the back of the LCD display. the LCD panel itself does not have light emitting properties, therefore a light emitting source must be added to the LCD panel in order to display it. Generally speaking, the LCD backlight module is made up of backlight source, optical film, adhesive type products, insulation type products, plastic frame and other components. Among them, the optical film is one of the key components of the backlight module, according to its role can be divided into diffuser, reflector, light guide plate, prism sheet, lamp reflector, etc. In terms of technological development, the development trend of LCD includes large screen, high definition, use of LED backlight instead of CCFL backlight, ultra-thin, wide colour gamut, support for 3D display and intelligence, etc. However, none of these development trends will change the basic backlight display principle and structure of LCD. As a result, LCD has become the mainstream display technology of the moment by taking advantage of its small size, light weight, no radiation, no glare, anti-interference, anti-vibration and large display angle.
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