Image Credit: Allied Electronics, Inc. | Digi-Key Corporation | Saint-Gobain Plastic Films and Tapes
Display filters and films are designed to filter, enhance and/or protect monitors or flat panel displays (FPD). They are often used with liquid crystal displays (LCD), cathode ray tubes (CRT), vacuum fluorescence displays (VFD), medical equipment, and scientific instrumentation. There are two main types of display filters and films: polarizing and non-polarizing. Polarizing display filters and films use semi-silvered mirrors to permit the passage of specific planes of light. They remove unwanted reflections from non-metallic surfaces such as glass and water without reflecting the overall color balance.
There are two subcategories of polarizing display filters and films: linear and circular. Linear polarizing filters and films transmit light waves along one axis and absorb them along the other. The transmitting and absorbing axes of linear polarization are oriented at 90 degrees to each other. Circular polarizing filters and films are similar to linear polarizers, but include a quarter-wave plate set at a 45-degree angle to the axis of polarization. Non-polarized display filters and films are also commonly available.
Display filters and films differ in terms of specifications and features. Specifications include substrate material and filter color. Features include EMI/RFI shielding, anti-scratch coatings, anti-glare or anti-reflective (AR) coatings, and contrast enhancement (CE) coatings. Non-polarizing filters are usually made of acrylic or polycarbonate materials. Color choices include: gray, red, yellow, amber, bronze, blue and green. Polarizing display filters and films are made of acrylic. Color choices include: neutral gray, red, yellow, amber, blue and green.
In terms of product features, some display filters and films provide shielding against electromagnetic interference (EMI) and radio frequency interference (RFI). Others use scratch-resistant, anti-glare, or CE coatings. Display filters and films that feature clear hard coatings provide excellent scratch resistance and are designed for applications with few external light reflections. Display filters and films with anti-glare, clear hard coats provide excellent display resolution and are suitable for medium to bright light applications.
Differences Among Manufacturers
Suppliers of display filters and films use a wide range of adhesives for gasketing and conductive grounding. They use various silk screening techniques and can apply conductive bus bars for shielding purposes. Some display filter manufacturers provide testing and certification services for light transmission, haze, Gardner gloss levels and light deviation. Others offer CNC and laser cutting for small-volume or large-volume production runs. Display filters and films that are destined for sale in Europe should bear the CE mark and meet all relevant European Union (EU) directives.