The Introduction Of Polarizer Sheet
May 04, 2022
The optical element that can make natural light into polarized light is called polarizer, also called polarized light sheet, polarizer. It has the function of masking and transmitting the incident light, which can make the longitudinal light or transverse light one kind of transmission and the other kind of masking. It is a composite material made of polarizing film, inner protective film, pressure-sensitive adhesive layer and outer protective film lamination.
Principle of polarization
The asymmetry of vibration direction for propagation direction is called polarization, which is one of the most obvious signs of transverse waves distinguishing from other longitudinal waves, and only transverse waves have polarization phenomenon. Light waves are electromagnetic waves, and the direction of propagation of light waves is the direction of propagation of electromagnetic waves. The electric vibration vector E and the magnetic vibration vector H are both perpendicular to the propagation speed v. Therefore, light waves are transverse waves, which are polarized, and light with polarization is called polarized light.
Polarizing film has two categories: black and white and color, and can be divided into three categories: transmission, reflection and anti-transmission according to the application. Generally, the polymer compound polyvinyl alcohol film is used as the substrate, and then iodine with strong dichroism is impregnated and stabilized by aqueous boric acid solution, and then it is stretched in one direction. After stretching, iodine molecules are neatly adsorbed on top of the film, which has polarization or detection properties.
Polarizer Classification
Polarizers are classified according to their functions, including transmitting polarizers, reflecting polarizers, half-transmitting and half-reflecting polarizers, and compensating polarizers.
Polarizers are classified according to the polarizing material and include the following.
Iodine-based polarizers: easy to obtain high transmittance and high polarization optical properties, but poor resistance to high temperature and humidity, and low polarizer cost, high market share and wide application areas
Dye-based polarizer: not easy to obtain high transmittance and high polarization optical properties, but better resistance to high temperature and high humidity. It is mostly used in industrial fields such as automobiles and ships.
Composition of polarizer
The basic structure of polarizing film consists of PVA (polyvinyl alcohol) in the middle, two layers of TAC (triacetate), PSA film (pressure sensitive adhesive), Release film (release film) and Protective film (protective film). In order to protect the physical properties of the polarizing film, a layer of PVA with high light transmission rate, good water resistance and certain mechanical strength (TAG) film is laminated on each side of the PVA for protection, which forms the original polarizing film.
In the production of ordinary TN-type LCD polarizers, a certain thickness of PSA is coated on one side of the polarizer sheet and laminated with an isolation film to protect the PSA. On the other side, according to the type of product, protective film, reflective film and semi-transparent and semi-reflective film are laminated to form the finished polarizer.
For STN type LCD polarizer products, the PSA layer is laminated with phase difference film and protective film with certain phase difference compensation value according to the customer's different needs, thus forming STN type LCD polarizer products.
Different types of polarizers
1. The polarizer made by using high temperature and moisture resistant pressure sensitive adhesive and special dipping treatment of PVA is the wide temperature type polarizer.
2、If the pressure-sensitive adhesive is added to prevent the passage of ultraviolet rays, the polarizer can be made into an anti-ultraviolet ray polarizer.
3、The STN polarizer can be made by laminating the birefringent optical compensation film on the transmittance sheet.
4、Wide view polarizer or narrow view polarizer can be made by laminating the light steering film on the transmitting sheet. Color polarizer can be made by coloring the pressure-sensitive adhesive, PVA film or TAC film.
