4 types of TFT LCD technology

The global flat panel display industry is now dominated by TFT (Thin Film Transistor) LCDs. Due to its low price, clear colors, acceptable view angles, low power consumption, manufacturing-friendly design, slim physical structure, etc., it has forced CRT (Cathode-Ray Tube) VFD (Vacuum Fluorescent Display) out of the market and limited LED (Light Emitting Diode) displays to large display areas. TFT LCD displays have several uses, including in televisions, computer monitors, medical equipment, household appliances, cars, kiosks, point-of-sale (POS) terminals, low-end mobile phones, industrial meters, smart homes, portable devices, video gaming systems, projectors, consumer electronics, and advertisements. Visit our knowledge base for additional details about TFT screens.

When we refer to an LCD that employs TFT technology to enhance picture attributes like addressability and contrast, we are referring to a TFT LCD. In contrast to passive matrix LCDs or straightforward, direct-driven LCDs with a few segments without TFT in each pixel, a TFT LCD is an active matrix LCD.

The TFT LCD technology comes in a variety of forms. Different TFT LCD technologies have unique characteristics and uses.

TN (Twisted Nematic) Type

One of the most established and affordable types of LCD display technology is the TN type TFT LCD display. Although TN TFT LCD screens offer quick reaction times, its principal benefits are poor color reproduction and constrained viewing angles. Depending on the viewing angle, colors will change. To make matters worse, it has a gray scale inversion issue with the viewing angle. The primary genetic problems required a considerable deal of work from scientists and engineers to address. Although modern TN displays can appear noticeably better than previous TN displays from decades ago, TN TFT LCD screens still generally have worse viewing angles and color compared to other TFT LCD technologies.

IPS (In-plane switching) Type

Hitachi Ltd. created the IPS TFT LCD display in 1996 to enhance TN panels' low viewing angles and subpar color fidelity. Its moniker is a result of the in-cell twist/switch distinction it has from TN LCD panels. Instead of moving perpendicular to the panel plane, the liquid crystal molecules travel parallel to it. With this modification, the matrix's light dispersion is reduced, improving the broad viewing angles and color reproduction that are distinctive to IPS. Although IPS TFT displays are more expensive to produce and have lower panel transmission rates than TN type TFT displays, these drawbacks do not prohibit them from being employed in high-end display applications that need excellent color, contrast, viewing angles, and clear pictures.

MVA (Multi-Domain Vertical Alignment) Type

Multi-domain Vertical Alignment (MVA) technique was created by Fujitsu.

With its uniform alignment of the liquid crystal molecules, mono-domain VA technology is frequently utilized for monochrome LCD displays to produce a clean black backdrop and improved contrast. It also causes the brightness to change with the viewing angle.

This issue is resolved by MVA by giving the liquid crystal molecules on a single pixel more than one orientation. This is accomplished by segmenting each pixel into two or four domains, which are then used to pretilt the liquid crystal molecules in different directions utilizing protrusions on the glass surfaces. This may be done to make the brightness of the LCD panel look consistent from a variety of viewing angles.

MVA is still used in some applications but it is gradually replaced by IPS TFT LCD Display.

AFFS (Advanced Fringe Field Switching) Type

This LCD technology was developed by the Korean company Boe-Hydis and is based on IPS. Advanced fringe field switching, also known as fringe field switching (FFS) before 2003, is a technology that is comparable to IPS and offers greater performance, a wide color range, and high luminance. By expanding the white gamut, which also improves white/grey reproduction, color shift and deviation brought on by light leakage are rectified. Hydis Technologies Co., Ltd. (formerly Hyundai Electronics, LCD Task Force), a Korean company, creates AFFS.

The AFFS patent was licensed by Hydis Technologies Co., Ltd. to Hitachi Displays in 2004. To produce high-end panels for their product range, Hitachi uses AFFS. Hydis also granted Sanyo Epson Imaging Devices Corporation a license to use its AFFS in 2006. (Reference)

The AFFS and IPS have a similar design philosophy in that they both arrange the crystal molecules parallel to the substrate to enhance viewing angles. The AFFS, on the other hand, is more sophisticated and can better optimize power usage. Most significantly, AFFS has high transmittance, which means that more light energy is transferred toward the surface and less is absorbed within the liquid crystal layer. Because IPS TFT LCDs often have poorer transmittances, a brighter backlight is required. The tiny, optimized active cell space of the AFFS is at the heart of this transmittance discrepancy.

Because of its exceptional contrast, brightness, and color stability, AFFS has been employed in high-end LCD applications, such as high-end smartphones.