Increasing LCD Contrast



Oftentimes it is possible to improve the sharpness, or LCD contrast, on your current display without having to redesign your current product. Many of these improvements can be realized without the tooling fees necessary to build a custom LCD display module.

Before we move forward, I need to clarify that the type of displays we are talking about are monochrome LCDs and not TFT or OLED’s. Monochrome displays include charactergraphic and segment LCD displays.

Character Alphanumeric LCD Display Monochrome Graphic LCD module Segment LCD Display 

Two easy fixes to improve LCD contrast


monochrome LCD display unitizes three different voltages: Ground (zero volts), the displays max voltage (3V, 3.3V or 5 volt) and the contrast-adjust voltage.

The contrast-adjust voltage performs the same function as the lens on a camera. By adjusting the lens, the user can bring the image into perfect sharpness. The contrast-adjust voltage performs a similar function by adjusting the voltage to provide a sharper image. The LCD contrast voltage is set before your product is shipped, but changes in temperature can affect the sharpness requiring the voltage to be modified in the field.


Monochrome LCD displays are built by trapping a nematic fluid between two layers of glass. Switching the fluid in your monochrome LCD from one fluid to another can increase the sharpness of your display.

This nematic fluid is referred to as Twisted Nematic (TN) since it has the ability to twist or rotate when voltage is applied to the LCD. When the display is powered up, the fluid rotates sideways and blocks light from passing through. When the power is turned OFF, the fluid rotates back to its original state and allows light to pass through. The more the fluid in your LCD display can twist, the sharper the image.

There are three common types of TN fluid: Twisted Nematic (TN), Super Twisted Nematic (STN) and Film Super Twisted Nematic (FSTN). TN fluids are similar to the three grade of gasoline for your car; the better the fluid, the more it is able to twist and the higher its cost.

LCD Display suppliers are able switch between fluids without a tooling cost or a higher Minimum Order Quantity (MOQ).

Twisted Nematic (TN)

The fluid with the least twist and lowest cost is Twisted Nematic (TN). TN cannot rotate as much as STN and FSTN and therefore produces a display with the least amount of clarity. TN is not a bad option if you are building a cost sensitive product where clarity is not as critical. Products that use TN include pagers, digital watches and many gas pumps.

Super Twisted Nematic (STN)

STN is the medium grade fluid and is the most popular of the three because if offers a good performance at an affordable cost. Products that use a STN fluid include credit card readers, home alarm systems and scales.

Film Super Twisted Nematic (FSTN)

FSTN is the high-end or ‘ premium super unleaded’ fluid. It offers the greatest amount of twist and therefore the greatest sharpness. The cost increase from STN to FSTN ranges from 8% to 12% more expensive. If ultimate sharpness is critical, FSTN is the way to go. Products that incorporate FSTN include medical devices, avionics and high-end audio.

To find out more about increasing the sharpness on LCD displays, please contact Focus LCDs at 480-503-4295.