The notes below are recommended 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 behave 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.
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.
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 display, STN display, FSTN display, normal temperature range or wide temperature range. Contrast is not affected by LED backlight, EL backlight of the type of polarizer such as Reflective polarizer, Transflective polarizer and Transmissive polarizer.
The three types of displays and how to adjust the contrast is listed below.
Alphanumeric LCD display / character LCD module / numeric LCD displays: The majority of our LCD display modules contain a resistor that allows the contrast to be adjusted. 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 adjust the contrast through their software or firmware. This includes the following models: 8 x 1 LCD Display module, 8 x 2 LCD module, 16 x 1 LCD Display, 16 x 2 LCD Display, 16 x 4 LCD Display, 20 x 2 LCD Display, 20 x 4 LCD Display, 24 x 2 LCD Display, 40 x 1 LCD Display, 40 x 2 LCD Display, 40 x 4 LCD Display
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 contrast adjust must be done on the customers board.
Monochrome Graphic LCD Displays: Many of these displays also contain a resistor to adjust the contrast. Customers may also have the ability to adjust the contrast through their software or firmware. This includes the following models: 122 x 32 graphic LCD display, 128 x 128 graphic LCD display, 128 x 64 graphic LCD display, 240 x 64 graphic LCD display.
Many custom LCD displays may have the contrast resistor added at no additional cost.
