How to Improve LCD Response Time
With the recent widely use of PC and online games, and PCs equipped with DVD drives give users more opportunities to see moving images such as those in 3D games or action movies on screen. This increase in motion picture content means computer monitors must be able to display not only still images, but moving ones as well. The customer has more and more fast response time request for LCD display. Unfortunately, slow response time is one of the drawbacks for LCD. With the technology progress, LCD can meet most of the requirements for response time.
Slower vs Faster Response time
If response time is slow, the transition from one picture (or frame) to another can produce an afterimage or blurring effect. This problem occurs not only when looking at motion pictures, but also during scrolling. For this reason, panels with faster response times are typically recommended for displaying moving images.
|Slower (higher) response time||Faster (Lower) Response time|
Fig.1 Slower and Faster Response time
Listed below are calculations for the liquid crystal response times that the displays meet, with consistent reliability, for various application standards. Response time is measured in milliseconds (ms, 1/100 second). The shorter the time frame, the better the display quality.
Liquid crystals are rarely completely turned on or off. Instead, they cycle in between gray states. The following are two common methods the display industry uses to measure response time:
Fig.2 LCD Response Time Definition
At present, there is no accepted standard for the computation of Gray-to-Gray response time. The above definition is just for reference.
How to improve LCD Response Time?
There are several ways to improve the LCD response time.
Optimize LCD material and structure
Key parameters of faster response time are listed below and the improvement can be done first by optimizing the following parameters.
- Liquid Crystal Materials: The lower the viscosity, the faster the response and the higher of the voltage.
- Temperature: The higher the temperature, the faster the response (But some LCDs have to be used at lower temperature). The lower the temperature, the higher viscosity the liquid crystal material.
- Production process: To make cell gap thinner. This is the most effective measure. The thinner the cell gap, the faster the response (but the yield will be lower and cost will be higher).
- Driving: The lower the multiplex, the faster the response. (But more expensive driving)
- Use LCD heater to make the liquid crystal material warmer.
- Technologies: TN is faster than STN (but the contrast will be lower).
Normal TN Response Time
25ms at +70°C
35ms at +25°C
100ms at 0°C
250ms at -20°C
800ms at -30°C
5000ms at -40°C
Normal STN Response Time
200ms at +70°C
250ms at +25°C
450ms at 0°C
1000ms at -20°C
8000ms at -30°C
~60,000ms at -40°C