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IPS vs TFT: which technology is best for my design?

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Jul 11, 2019

The tried and trusted TFT is the display of choice for most industrial designs, but it does have its limitations in viewability and colour vibrancy. But what about the relatively new technology, IPS (in plane switching) which has turned the TFT into a super-TFT? What are the benefits and drawbacks of each?

What is an IPS-TFT display?

In-Plane Switching (IPS) is a technology that overcomes the viewing limitations of conventional TFT-LCDs. It is also known as Super TFT.

IPS derives its name from the fact that the liquid-crystal molecules are aligned in parallel with the glass plates, whereas the TN principle adopted in conventional TFT displays is based on perpendicular alignment of the molecules. In an IPS display, the crystals remain oriented in parallel whether the pixel is turned on or off.

Electrodes are placed on the same sheet of glass, instead of on opposing sides, so that when the signal is applied, the crystals rotate horizontally in the same plane.

What is a TFT display?

A TFT display is a form of Liquid Crystal Display with thin film transistors for controlling the image formation. The TFT technology works by controlling brightness in red, green and blue sub-pixels through transistors for each pixel on the screen. The pixels themselves do not produce light; instead, the screen uses a backlight for illumination.

What are the benefits and negatives of an IPS-TFT display?

Benefits of using an IPS-TFT display:

  • Because the pixels block light when in the off state (the opposite situation to conventional TFT), IPS TFT exhibits high contrast and the background is true black when the display is powered down.
  • Better readability in sunlight
  • This is less disturbing than bright-pixel defects in a conventional TFT.
  • Colour reproduction is also more accurate,
  • Contrast and colour are more consistent over a wider viewing angle
  • Optimum visibility is achieved throughout wide-ranging conditions and environments, including daylight.

Negatives of using an IPS-TFT display:

  • Size ranges at resent are fairly limited for IPS displays
  • Response times are lower
  • Power consumption is higher
  • IPS-TFT displays come at a higher cost than standard TFTs due to more complex production.

What are the benefits and negatives of a TFT display?

Benefits of a TFT:

  • Mature technology means manufacturing processes are efficient and yields are high
  • Prices are very competitive
  • Available in a wide range of sizes
  • Can be cut down to custom fit an enclosure, without loss of performance

Negatives of using a TFT display:

  • Contrast can be limited
  • Colour inversion can be seen at extreme viewing angles
  • Display not completely black when switched off

IPS-TFT vs TFT-LCD: summary of positives and negatives

IPS-TFT TFT-LCD
+ - + -
High contrast and true background Display sizes more limited Efficient manufacturing processes and high yields Contrast can be limited
Better sunlight readability Lower response time Very competitive prices Colour inversion at extreme viewing angles
Accurate colour reproduction Higher power consumption Wide range of sizes available Display not completely black when switched off
Contrast and colour are more consistent over a wide viewing angle Higher cost Cut down options available
Optimum visibility

Display choice really does depend on your application, end user and environment. It may be a higher-grade IPS is needed to satisfy outdoor requirements, or a lower cost standard TFT display is sufficient. Before you make your choice, why speak with us and we will be happy to talk you through your options.

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