What are the LCD Fluid Types?

With LCD’s there are many different LCD fluid types. The most common being TN, STN and FSTN. The LCD fluid twists the orientation of light passing through the glass causing the active pixels to darken. Each fluid offers unique characteristics to your LCD. These characteristics results in changes to the LCDs color, viewing angle, clarity and/or temperature range. The use of which fluid type you choose (TN, HTN, STN or FSTN) will affect the unit cost. TN fluid is less expensive than STN fluid. STN fluid is less expensive than FSTN fluid type. Below is a brief description on a few of the different LCD fluid types with images added to help add clarity.

TN (twisted nematic) is the most common fluid used in static and multiplexed displays. The TN technology comes in one coloration – black characters on a gray background. It is the least expensive and has the lowest visual quality, primarily in viewing angle. TN also has the best response time of the fluid types.

HTN (high twisted nematic) has a contrast and viewing angle close to that of an STN display. The HTN fluid can be used with very low operating voltages and is only slightly more expensive than the TN fluid type. This makes it a popular technology in handheld applications.

STN (super twisted nematic) is the most common fluid among monochrome LCD’s. STN comes in two colorations – dark blue characters on a gray background and dark gray/black characters on a yellow/green background. This is a middle priced fluid type with very good visual quality and contrast similar to the TN.The response time of an STN display is moderate.

FSTN (film compensated super twisted nematic) is the most recent advance to be introduced. FSTN uses STN fluid with the addition of a compensating film which attains a higher contrast and larger viewing angle. The higher contrast supplied by an FSTN allows for a black and white display effect which also makes it the most expensive fluid type.