Introduction to LTPS?

Low Temperature Poly-silicon (LTPS) was originally a technology company in North America in Japan to reduce the energy consumption of Note-PC displays,The technology developed to make Note-PC appear thinner and lighter, Around the mid-1990s, this technology began to enter the trial stage。The new generation of organic light-emitting panel OLED derived from LTPS also officially entered the practical stage in 1998,Its biggest advantage is ultra-thin, light weight, low power consumption。 Can provide brighter colors and clearer images。

Low temperature polysilicon

 TFT LCD can be divided into polysilicon (Poly-Si TFT) and amorphous silicon (a-Si TFT), The difference between the two lies in the characteristics of the transistor。The molecular structure of polysilicon is arranged neatly and directionally in a grain,Therefore, the electron movement rate is 200-300 times faster than that of disordered amorphous silicon; The generally called TFT-LCD refers to amorphous silicon, Mature technology, It is the mainstream product of LCD。Polysilicon products mainly include high-temperature polysilicon (HTPS) and low-temperature polysilicon (LTPS)。

 Low Temperature Poly-silicon (LTPS) thin film transistor liquid crystal displays are in the packaging process,Using excimer laser as a heat source, After the laser light passes through the projection system, Will produce a laser beam with uniform energy distribution, Projected on a glass substrate with an amorphous silicon structure, When the amorphous silicon structure glass substrate absorbs the energy of the excimer laser, Will transform into a polysilicon structure, Because the entire treatment process is completed below 600 ℃, Therefore, general glass substrates are applicable.

Characteristic

  LTPS-TFT LCD has the advantages of high resolution, fast response, high brightness, and high aperture ratio。In addition, since the silicon crystal arrangement of LTPS-TFT LCD is more orderly than that of a-Si,Make the electron movement rate relatively higher than 100 times,The peripheral driving circuit can be fabricated on the glass substrate at the same time,Reach the goal of system integration, save space and drive IC cost。

  Simultaneously,Since the driver IC circuit is directly made on the panel,Can reduce the external points of the components, Increase reliability, simpler maintenance, shorten assembly process time and reduce EMI characteristics,This reduces the design time of the application system and expands the design freedom.

  The highest technology of LTPS-TFT LCD is to achieve System on Panel,The first generation of LTPS-TFT LCD uses built-in drive circuit and high-performance pixel transistors to achieve high resolution and high brightness. It has made LTPS-TFT LCD and a-Si have a great difference.

  The second generation of LTPS-TFT LCD through the advancement of circuit technology,From the analog interface to the digital interface, Reduce power consumption. The carrier mobility of this generation of LTPS-TFT LCD is 100 times that of a-Si TFT, The electrode pattern line width is about 4μm,The characteristics of LTPS-TFT LCD have not been fully utilized.

  The third-generation LTPS-TFT LCD is more complete in peripheral large-scale integrated circuit (LSI) integration than the second-generation,Its purpose is: (1) There are no peripheral parts to make the module lighter and thinner,It can also reduce the number of parts and assembly man-hours;(2) Simplified signal processing can reduce power consumption;(3) Equipped with memory to minimize power consumption.

  Because LTPS-TFT LCD liquid crystal display has the advantages of high resolution, high color saturation, and low cost,High hopes are placed on a new wave of displays.With its high circuit integration characteristics and low cost advantages,It has an absolute advantage in the application of small and medium-sized display panels. But p-Si TFT has two problems,One is that the off-state current (ie leakage current) of the TFT is relatively large (Ioff=nuVdW/L);Second, it is difficult to prepare high-mobility p-Si materials in large areas at low temperatures.There are certain difficulties in the process.

  It is a new generation technology product derived from TFT LCD.The LTPS screen is manufactured by adding a laser processing process to traditional amorphous silicon (a-Si) TFT-LCD panels.The number of components can be reduced by 40%,And the connection part can be reduced by 95%,Greatly reduce the chance of product failure.This screen has greatly improved in terms of energy consumption and durability,Both horizontal and vertical viewing angles can reach 170 degrees, Display response time up to 12ms,The display brightness reaches 500 nits, The contrast ratio can reach 500:1.

There are three main ways to integrate low-temperature p-Si drivers:

1、Hybrid integration of scanning and data switching,The circuit is integrated together,The switch and shift register are integrated in the column circuit, Multiple addressing drivers and amplifiers are connected to the flat panel display with inherited circuits;

2、All drive circuits are fully integrated on the display screen;

3、Drive and control circuits are integrated on the display screen.

 


Post time: Jan-07-2021