LCD Contrast Adjustment and Temperature Compensation


The relationship between the properties of the liquid crystal fluid, contrast, voltage, and temperature may require compensation for the LCD driving voltage. Especially if the monitor has a wide operating temperature range.


There are many ways to compensate the LCD drive voltage, such as manual adjustment by the user, or the product microprocessor providing the LCD with the appropriate voltage based on the measurement of the ambient temperature. These methods are neither practical nor economical.


A common method of temperature compensation is to provide a circuit as shown below to automatically adjust the drive voltage.



The thermistor of the RTH should fit snugly against the LCD module to detect the ambient temperature. Resistor R1 is adjusted to select an appropriate initial voltage (or two fixed voltage divider resistors can be used). R2 is used as the minimum bias resistor.


Various LCD modules of TSINGTEK have built-in PWM function, and users can easily adjust the contrast of LCD according to their needs.