Modify the LCD Contrast Adjustment on Your LCD Display

The notes below on modifying the LCD contrast adjustment on your LCD display are recommended only for monochrome LCDs:

Contrast is the ratio of the LCD segments that are “ON” and the LCD segments that are “OFF”. The goal is to have the greatest visible difference between the “ON” LCD module segments and the “OFF” LCD module segments. This can all be referred to as the ‘sharpness’ of the liquid crystal display.

The same LCD will not perform the same on two different products. One customer may install a standard LCD module and have a sharp image. Another customer may install the same LCD and find the display is not clear enough. How do you solve this problem?

LCD contrast adjustment

One solution is to modify the resistor value that controls the contrast of the monochrome LCD by increasing or decreasing the resistance value of the resistor. If you find that the contrast is not as sharp as you like, please contact us to identify which resistor on your LCD display module will modify the contrast. We will help you through the LCD contrast adjustment.

When you locate the correct resistor, remove the resistor and replace it with a potentiometer (we recommend a 10K ohm value). Adjust the potentiometer until you arrive at the sharpness you desire. Notify Focus Displays of the correct contrast resistor value and we will modify the resistor on all future displays.

Contrast can be affected by other variables such as TN fluid, STN fluid, FSTN fluid, normal temperature range or wide temperature range. Contrast is not affected by the LED backlight, EL backlight, or of the type of polarizer such as Reflective polarizer, Transflective polarizer and Transmissive polarizer.

Types of monochrome displays

The three types of monochrome LCD displays where you can modify the LCD contrast adjustment is listed below.

Alphanumeric LCD display / character LCD module: The majority of our LCD display modules contain a resistor

that allows for the LCD contrast adjustment. There are a few monochrome LCD’s that may need to have the printed circuit board modified to accept the contrast resistor. Customers may also have the ability to perform the LCD contrast adjustment through their software or firmware.

This includes the following modules: 8×1 LCD module, 8×2 LCD module, 16×1 LCD module, 16×2 LCD module, 16×4 LCD module, 20×2 LCD module, 20×4 LCD module, 24×2 LCD module, 40×1 LCD module, 40×2 LCD module, 40×4 LCD module

Static LCD Segment Displays – 7 (seven) segment, 14 (fourteen) segment, 16 (sixteen) segment displays: This type of display does not contain any resistors or a printed circuit board. The LCD contrast adjustment must be done on the customers board.

Monochrome Graphic LCD Displays: Many of these displays also contain a resistor to perform the LCD contrast adjustment. Customers may also have the ability to adjust the contrast through their software or firmware.

This includes the following modules: 122×32 graphic LCD module, 128×128 graphic LCD module, 128×64 graphic LCD module, 240×64 graphic LCD module.

Note: Many custom LCD modules may have the LCD contrast resistor added at no additional cost.