Popular display technologies used for tablets

I am pretty sure that you have visited a computer shop before. And when you have examined all those great looking tablets, you've noticed that some of them have much brighter and/or more colorful screens. Read this guide and I promise that you will be able to tell the difference between LCD and AMOLED displays in a jiffy.

1. Liquid-Crystal Displays (LCDs) use the light modulating properties of liquid crystals to display information. Basically, crystals change their orientation when electrical current flows through a suspension that contains them, either allowing light to pass through them, or blocking it.

Companies have been building LCD-based displays for their watches for several decades now. Of course, since LCDs don't emit light on their own, a light source must be placed behind one of the two sheets of polarized material; otherwise, the information that shows up on the LCD display will only be visible in direct sunlight, or in well-lit areas.

LCDs are cheap to produce, but the resulting displays aren't of the highest quality. They have a big response time, which can make objects that move around look blurry on the screen. Contrast is weak, and viewing angles are poor. Power efficiency isn't stellar either, because the backlight source, which draws a lot of power, needs to be kept on at all times.

You will often find LCD-based displays in low-end tablets. Thin Film Transistor (TFT) LCDs use the "active matrix" technology, improving image quality – especially its contrast. They are a bit more expensive, but if you have a low budget, a TFT display is well worth the extra money.

2. Organic Light-Emitting Diode (OLED) displays can be built using small cells or polymers. They use tiny LEDs which can be lit up individually. Each pixel is made out of three LEDs (red, green and blue) that combine their light to produce the desired colors. These displays are thinner, smaller, use less power - about 50% of the energy needed by an LCD - and can display much deeper blacks, because they don't need to use a backlight. This means that OLED displays have a much better contrast ratio in comparison with standard LCDs, providing a better picture quality. Additionally, OLEDs have a much faster response time, being the gamers' favorite displays.

Modern OLED-based displays use several layers, which help improve efficiency; many of them utilize a dual-layer structure, with one of the layers being conductive and the other one emissive. When a positive source of energy is applied to the cathode, electrons will start to flow from cathode to the anode, reaching a layer of holes that is placed near the emissive layer.

Organic LEDs have a limited lifespan, though; several reports have demonstrated that these displays start to lose their impressive brightness after a few years of daily usage. It is estimated that an OLED display will run for about 30,000 hours until its brightness is reduced to half.

3. Active-Matrix OLED (AMOLED) is a newer version of the organic light-emitting diode technology. It's still expensive, so it can't be found in too many large-sized devices. Unlike OLEDs, AMOLED displays use an active matrix of pixels that generate light, utilizing two or three thin-film transistors for each pixel.

The first transistor controls a storage capacitor, while the other one sets the proper current intensity that's necessary for each particular pixel. Since the already available electrical energy is stored by the capacitor, AMOLED displays use less power in comparison with the OLED-based ones. The higher refresh rates also help, reducing power consumption, because the LEDs will stay lit much less after the signal that has triggered the pixels stops.

Companies continue to create new types of displays; if everything works out as planned, we will soon get to see transparent OLED screens, flexible displays, Quantum-dot LEDs and other impressive technologies.