LCD vs AMOLED: Breaking down the key differences

LCD and OLED are different types of display technologies found in the electronics we use today. Both technologies perform the same function i.e. displaying images, but they do so in very different ways, lending each technology a distinct set of advantages and disadvantages.

What is an LCD?

LCD stands for liquid crystal display. In LCD technology, light is focused and modulated via a set of filters and microscopic lenses before passing through a colour filter. If the light passes through a red filter, we see red light. If it passes through a green one, we see green, and so on. No light means black, and a combination of red, green, and blue at equal intensity results in white.

These microscopic lenses are made up of liquid crystals, hence the term: liquid crystal display.

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A simplified overview of the LCD structure is as follows:

1. The farthest layer is the backlight. It’s usually an array of white LEDs that shine towards the front of the display

2. In front of this LED layer is a Fresnel lens and diffuser. The job of these two layers is to diffuse the light from the LEDs and to create a uniform layer of light.

3. The light then passes through a combination of various filters and polarisers so that the light waves are oriented in a specific direction – vertical or horizontal – for the next stage.

4. Once polarised, the light passes through an array of microscopic liquid crystals. These crystals twist or rotate to block or allow the light to pass through them. The amount of twist or rotation is controlled by electricity. By blocking or allowing light through, each crystal changes the intensity of light at that point.

5.This light then passes through another layer of polarisers and colour filters to finally give us the image we see.

The type of liquid crystal used to control the light gives us different types of displays i.e. TN, VA, and IPS. The type of backlight used also gives us LED LCD, CFL LCD, miniLED LCD, etc.

As you can see, the LCD structure is very complex, and light must pass through multiple layers before we see it.

What is OLED?

OLED or Organic Light Emitting Diode is a display technology that uses organic chemical compounds – organic simply means that these are carbon-based chemicals – to produce an image.

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Unlike an LCD, which requires a backlight and several layers of lenses, polarises, and filters, an OLED display is comprised of microscopic chemical dots which react to electricity. When a voltage is applied to these dots, they emit light. Different chemicals emit different colours of light, and the variation in voltage increases or decreases their brightness.

To manufacture an OLED display, various chemicals are deposited on a substrate – usually silicon – in microscopic patterns determined by a kind of template. These dots can also be printed via a heavily modified inkjet printer.

AMOLED is simply a kind of OLED display where a layer of microscopic transistors is used to control the voltage passing through the organic compounds instead of, say, electrical wires. AMOLEDs are more efficient and consume less power, so they ‘re more likely to be found in smartphone displays.

LCD vs OLED: Key differences

1. Power:

LCD displays are more complex and consume more power. OLED displays are very simple in design and consume much less power. 

2. Cost:

LCD displays are cheap to manufacture. OLED displays are more expensive to manufacture.

3. Brightness:

LCD displays are usually not as bright because light must pass through several layers of diffusion and filtering. OLED displays can get very bright as the chemical compounds directly emit light.

4. Longevity:

LCD displays can last much longer and don’t die as easily. OLED displays can degrade rapidly without adequate precautions being taken.

5. Colour accuracy:

LCD displays can deliver accurate colours, but it takes more effort to get them to do so. OLED displays can more easily deliver accurate colours

6. Contrast:

LCD displays have good contrast and typically manage 1000:1. Light bleeds through various filters resulting in lower contrast than OLED. Since OLED displays are self-emissive and no significant filters are involved, they offer the best contrast, often more than 1000000:1.

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7. Response time:

This is the time it takes for a pixel to transition from one colour to the next. LCDs tend to be slower (1-5 ms for fast displays) as it takes more times for liquid crystals to twist and untwist. OLEDs are much faster (0.03-0.1 ms) as the colour transition largely depends on whether an electrical charge is present or not.

OLED and LCD displays have distinct strengths and weaknesses, but often the choice of which to use simply comes down to cost. OLEDs do offer the best image quality, response, time, contrast, and are much thinner, but the cost is usually too high to justify their use in all applications.