![]() ![]() LED screens are more visible outside when compared to LCD or projection. “The digital signage system objective is one that the user’s content resolution will match the perception of resolution of the viewer’s eye, which is based upon the fovea of the eye and the distance to the screen, to the created resolution of the LED display.”īefore you decide to use an LED screen, consider lighting. “When factoring in digital signage sizes, the implied viewing distance and the ability of the eye to discern the pixels and notice pixelation, a viewing distance of 1.25 to 2 meters can be expected,” writes Gary Feather, CTO of NanoLumens. The more nits you have on your screen, the brighter the screen. In a word, a nit is a unit of visible-light intensity. ![]() In terms of brightness, an LED screen ranges from 300 nits to 700 nits for low to medium light conditions, and 2500 nits for higher light conditions or outdoor applications. This type of display uses light emitting diodes to visualize images. LED screens can range in size anywhere from 10 inches up to 95 inches. Overview of LEDįirst, let’s talk about LED screens. To help you better understand the difference, here’s a closer look at LED screens versus LCD screens. It’s a sticky subject, especially now that we are seeing more and more LED screens being used indoors. Where they were primarily used outdoors at large sporting events or other venues, LED screens are now popping up indoors – mostly thanks to a lowered price point and the flexibility of LED screen shapes.Īs the popularity of LED screens grows, there’s still confusion regarding which kind of commercial-grade screen should be used: LED or LCD? It can be seen that a polarizer absorbs half of the light of the conventional but not of the new backlight.Digital displays are always changing, so it’s crucial to understand the existing difference between LED and LCD screens. A demonstrator backlight is shown in Figure 4 next to a conventional backlight. The birefringence of the foils is maintained surprisingly well in the hot-embossing process so that this seems a promising route for mass fabrication. Microscope pictures in Figure 3 illustrate good shape reproduction. Microstructuring is done by diamond-tool machining or hot embossing. Perpendicular to the stretch direction typical values are 1.54 for PET and 1.56 for PEN. Through stretching, 10,11 the index of refraction in the stretch direction typically increases to 1.70 and 1.85 for PET and PEN, respectively. The first 8,9 uses uniaxially oriented poly(ethylene naphthalate) (PEN) and PET foils. Two types of polarized-light backlights have been developed. Stretched birefringent poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) foils microstructured using (left) diamond-tool machining and (right) hot embossing. 6,7 The additional challenge associated with the latter approach, apart from manufacturing issues, relates to how one can eliminate large absorption losses in the metal film.įigure 3. It has also been proposed to integrate a wire-grid reflective polarizer into the light guide. 5 These approaches suffer from several drawbacks, however, including the nonuniform extraction of light and the need to inject collimated light, with the associated efficiency losses. Use has also been made of oriented poly(ethylene terephthalate) (PET) foils 4and liquid-crystalline polymers. In this context, both polarization-dependent light scattering 1,2 and the polarization dependence of the so-called Brewster angle 3 have been demonstrated. We aim to apply the angular and polarization selection more efficiently. The latter must be depolarized and re-emitted by the backlight system. Light with the desired polarization state is transmitted, but orthogonally polarized light is reflected toward the backlight. A second enhancement that is sometimes used recycles the polarization. This is done using micro-optical foils that select and transmit light emitted in certain angular ranges and recycle the rest (see Figure 1). The luminance is therefore usually enhanced in the viewing direction, at the expense of light emitted at large angles. Of every lumen of light generated in the backlight, only 2–8% is used owing to light losses in polarizers, color filters, and other optical layers. The optical efficiency of color LCDs is notoriously low.
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