TN LCD vs. IPS LCD: What’s the Difference?

“TN and IPS are the most common LCD panel types. TN LCDs have advantage in cost and can meet severe environment challenge, while IPS LCDs have excellent performance in wide viewing angle and color restoration.

I. TN LCD and IPS LCD technology

As early as the CRT display, given its unique imaging principle, the color, brightness, and contrast from the display can maintain good visual quality no matter from any viewing angle around the screen. However, its bulky structure has limited the design and application of displays for many applicants. As technology develops, flat panel displays take over the mainstream in the display market.

LCD is one of the main flat-panel display technologies. When it was just launched and the price was too high, it was difficult for the public to accept, so the LCD panel factories launched the affordable version, TN LCD.

To reduce the cost, the structure of TN LCD is simplified and the arrangement of liquid crystal molecules changes. It comes with the natural defects of the low color display quality and small effective viewing angle. When we look at the screen beyond the effective viewing angle, we will notice obvious image distortion.

In 1995, Hitachi was the first to introduce the IPS technology in LCD and put it into mass production in 1996. Ever since, the technology has undergone continuous innovation through Super-IPS, Advanced-SuperIPS, IPS-Pro, and still going on.

In another word, IPS technology is an upgraded version of TN technology.

Next, we will explain the differences between the IPS LCD and TN LCD.

- Liquid crystal arrangement differs

TN panel stands for twisted nematic panel

When a TN display is on, the liquid crystal molecules horizontally rotate in helical; when the display is off, they are in the vertical orientation.

IPS panel stands for in-plane switching panel

When the IPS display is on, the liquid crystal molecules of the panel rotate in a similar direction as in TN panels. However, when the display is off, they still rotate horizontally but change from the original spiral to layers.

By changing the electric field direction from vertical to horizontal, IPS technology can keep the liquid crystals stay parallel to the screen regardless the display is on or off. In addition, with the improvement of the structure, the viewing angle is enlarged significantly.

- TN LCD vs. IPS LCD: narrower viewing angle

The liquid crystal molecules of the TN panel lay in the vertical direction, in consequence, the light can emit around the vertical area. Therefore, we can only get better visual quality at a very limited angle and notice the obvious color distortion in tilting angles.

In contrast, in IPS panels, the horizontal arrangement of the LC benefits the light emission at any angle, which enables a wide effective viewing angle. It can reach 170 to nearly 180 degrees both vertically and horizontally, so we also call the IPS LCD an “all viewing angle” display.

- TN LCD vs. IPS LCD: lower grayscale display

Grayscale is the ability of color transition.

TN LCD (6bit) can display 2.62 million colors, while IPS LCD (8bit) can display 16.77 million colors.

From black to white, IPS can display more colors in the process of transition, so the transition performance is more natural and smooth.

- TN LCD vs. IPS LCD: faster response time

Due to the high contrast ratio and wide color gamut of HD, IPS panels take more time to respond than TN panels. In particular, in showing the dynamic HD pictures IPS are easy to appear ghosts and jitters. However, the phenomenon has greatly improved in recent years.

Hence, the business fields that require HD tend to choose IPS, such as consumer goods, medical treatment, design, cultural media, etc.

- TN LCD vs. IPS LCD: inferior in the color restoration

Grayscale and color mainly determine the ability of color restoration.

Compared to the TN panels, IPS panels have more gray levels, the imaging performance is more delicate, and can restore the color image in fine and vivid effect. As figure 4 shows, the image display on the TN panel appears only black in all four corners, with no details. While the IPS can show multiple color layers.

- TN LCD vs. IPS LCD: lower screen hardness, water ripples while being pressed

Due to the horizontal layout of liquid crystal molecules, under external pressure, the restoration speed of the IPS is about 10 times faster than TN which molecules in a vertical layout.

In addition, the surface of the IPS LCD is protected by a transparent resin film with high hardness, so it can remain the same when touched and there are no water ripples created on the screen surface. If we look at the screen with a magnifier, we can see that the pixels distribute towards the left like fish-scaled.

In contrast, when pressing the TN panel with a finger, there are water ripples on the surface, but the surface can restore quickly when the pressure is released. In addition, if it is bonded with a capacitive touchscreen, the cover of the CTP is normally hard (glass or hard plastic), which can release the pressure in touch.

- TN LCD vs. IPS LCD: higher aperture ratio, light transmittance, lower power consumption