Author Topic: NHD-7.0-800480EF-ATXV#-CTP vertical viewing angle  (Read 1859 times)

LarryG

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NHD-7.0-800480EF-ATXV#-CTP vertical viewing angle
« on: May 10, 2016, 07:57:38 AM »
Puzzled....regardless of content, colors are good when the display is viewed from below (negative vertical angle) but transition to washed out as you change to viewing from above (positive vertical angle).  Horizontal viewing angles appear consistent.

I'm driving the display in High Color (16bit) mode from an STM F469 ARM chip (has a built-in display driver with a 24bit RGB interface).  The display clock is 32Mhz and all other setups (VSync, HBP, etc.) are per your display specification.

I'm driving the backlight from a buck converter with the backlight drive and a DAC output (brightness control) summed together into the converter's feedback port.  I've settled on a backlight drive of 8.8V to provide a satisfactory level of brightness.

Any ideas? 

Paul_B

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Re: NHD-7.0-800480EF-ATXV#-CTP vertical viewing angle
« Reply #1 on: May 18, 2016, 12:58:40 PM »
Afternoon Larry,

Before we can dive into this topic I believe it is beneficial to understand the different LCD technologies on the market:

TN - Twisted Nematic
IPS - In Plane Switching
MVA - Multi-domain Vertical Alignment

TN (Twisted Nematic) is the most common technology and economical solution. The main advantage is that it provides the shortest response times. Another important factor is that they are cheaper to manufacture, resulting in low prices for end users. The drawbacks to the technology is the color shifts that occur at wider viewing angles. This is known as gray-scale inversion.

IPS (In Plane Switching) renders you the widest angles and usually better color production over traditional TFT (or Twisted Nematic TFT).

MVA (Multi-domain Vertical Alignment) is essentially a compromise between the two TFT technologies, providing wider viewing angles than the standard TN, but less color consistency than the IPS at the wide angles. Besides the wider viewing angles when compared to a TN type TFT, MVA also offers the advantage of no gray-scale inversion.

Therefore with the MVA type TFT you will still notice minor changes in color when viewing from the wide angles, however no inversion of color will take place.

If your application requires even wider viewing angles than our MVA type TFT, and excellent color consistency at those wide angles, I would recommend using an IPS type TFT, which typically will be the most expensive of the three technologies.

 

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