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Adaptive Addressing
"Adaptive Addressing" for enhanced low temperature operation.

Adaptive Addressing is an effective way to improve the performance of an LCD at low temperatures. It is a patented method that was developed under a DARPA grant and has been successfully implemented in displays of varying complexity. Liquid Crystal Technologies has the exclusive US rights to this technology for use in enhancing the cold temperature operation of a display.

Overview:

  • Adaptive addressing uses intelligent row and column scans, it does not simply scan down the rows as in a traditional addressing scheme. Only the rows that need to be updated are scanned. The process goes something like this:
    • Analyze the image
    • Ignore rows that have no "on" pixels
    • Update only the pixels that are active and that need to be updated. This means that even if a pixel is active it may not need to be updated, see the example below.
       
  • Optimization is done on the actual image data
    • Rows with corresponding "on" pixels are driven simultaneously.
       
  • Optimization is done in real time for every frame.

How it works:

The block diagram below shows the basic architecture of an LCD module using Adaptive Addressing. The image data stream does not go directly to the row and column drivers as in a traditional module. Instead it goes into the dual-ported video buffer, where the high-speed MCU can access the pixels and determine which pixels need to be updated. It also updates a few pixel tables in its own RAM memory that keep track of a number of pixel characteristics.

When the processing for any given frame is completed, the data is sent to the LCD thru the specialized row and column drivers. The dual-ported video RAM is then ready to accept the next frame of image data.

Cold Temp LCD Block Diagram

Discussions:

  • In Adaptive Addressing there is a tremendous amount of computation going on during a refresh cycle. However with the extremely fast processors available today, this is easily accomplished.
  • The development cycle for an LCD module that uses Adaptive Addressing is much longer than for a normal custom module.
  • It is critical to have the specifications firmly defined before design work begins.

Conclusions:

Some of the benefits of Adaptive Addressing are:

  • Increased temperature range.
  • Improved contrast at all temperatures
  • Improved viewing cone at all temperatures.
  • Decreased power consumption

The design of an LCD module using Adaptive Addressing is straightforward, however it does require a very close working relationship with the customer.

Because every design requirement is different, the best way to move ahead is to call us at (440) 232-8590 to talk to one of our engineering specialists about how "Adaptive Addressing" can solve your low temperature design problems.