Temperature Compensation for LCDs

Blaze Display Technology Co., Ltd. | Updated: Nov 27, 2018

 

The optimal contrast setting for LCD display varies with ambient temperature. For most applications this variation in contrast is tolerable over the "normal" temperature range of 0°C to +50°C. Most LCD modules are available with an extended temperature range option which allows the display to operate from -20°C to +70°C. The changes in contrast are NOT usually tolerable over this wide range of temperatures, which means a way of adjusting the contrast voltage as the ambient temperature changes must be provided.

 

As the temperature decreases the LCD fluid requires a higher operating voltage in order to maintain a given optical contrast. See Figure 1. One way to provide for this is to give the user control of the contrast. This is a simple solution but quite often its not desirable or practical.

 

The controlling microprocessor could measure the ambient temperature and supply the proper voltage to the LCD, but this is complicated and expensive. The most common solution to the temperature compensation problem is to provide a circuit such as that in Figure 2 to adjust the contrast voltage automatically.

 

 

 

This circuit will work for all character modules and graphic modules up to 320 x 240. Modules larger than this are not available with the extended temperature option.