Mobile Display Types

In this reading, you will learn about several types of displays used in modern mobile devices and monitors. As an IT Support professional, you may need to troubleshoot various types of displays. This might involve repairing damaged mobile device screens. You may even be responsible for selecting and ordering mobile devices for the employees of an organization. In your IT job role, you should have a basic understanding of the technology behind modern displays, as well as their common uses, positive features, and negative flaws.

The top two technologies used in mobile system displays are Liquid Crystal Displays (LCD) and Light Emitting Diodes (LED).

Liquid Crystal Display (LCD) 🖥️

LCDs use liquid crystal technology. Liquid crystals have the properties of both a liquid and a solid. The crystals can be aligned in a variety of patterns and manipulated with electricity. How the liquid crystals are arranged and manipulated inside display panels affects refresh rates, image quality, and display performance. LCDs require backlighting, often provided by LEDs. Displays that need backlighting are also called non-emissive or passive displays. The backlighting unit (BLU) requires extra space, which makes LCD panels thicker and less flexible than other displays. Polarizers on either side of the liquid crystal layer control the path of the backlight to ensure the light is aimed toward the user.

The following are common LCD display types used for mobile devices:

• In-Plane Switching (IPS)

  • How it works: In IPS displays, the liquid crystals are aligned horizontally to the screen. Electricity is passed between the ends of the crystals to control their behavior.

  • Uses: IPS technology is used in touch screen displays and high-end monitors. They are often used for design, photography, video/film editing, animation, movies, and other media. They can also be used for games that rely on color accuracy and wide viewing angles, as opposed to speed.

  • Positives: IPS displays provide vibrant colors, high-quality graphics, and wide viewing areas. Additionally, they offer excellent color reproduction, accuracy, and contrast.

  • Negatives: IPS displays are expensive. They have low refresh rates and slow response times. However, response times have been improving as the IPS technology evolves. IPS displays can be affected by "IPS Glow," where the backlight is visible from side viewing angles.

• Twisted Nematic (TN)

  • How it works: In TN displays, the liquid crystals are twisted. When voltage is applied, the crystals will untwist to change the angle of the light they transmit.

  • Uses: TN displays are appropriate for basic business use (e.g., email, document, and spreadsheet applications). They are also used for games that need rapid display response times.

  • Positives: TN displays are low cost, easy to produce, have excellent refresh rates, response times, and resolutions. They are versatile and can be manufactured for any size and/or shape.

  • Negatives: TN displays have narrow viewing angles, low image quality, color distortion, and poor color accuracy and contrast.

• VA-Vertical Alignment

  • How it works: In VA displays, the liquid crystal molecules are vertically aligned. They tilt when electricity passes through them.

  • Uses: VA displays are intended for general purpose. Provides mid-range performance for graphic work, movies, and TV.

  • Positives: VA displays offer great contrast, deep black shades, and fast response times. They are mid-range quality for refresh rates, image quality, viewing angle, and color reproduction.

  • Negatives: On VA displays, motion blur and ghosting occur with fast-motion visuals.

Organic Light Emitting Diodes (OLED) 💡

OLEDs are diodes that emit light using organic (carbon-based) materials when electricity is passed through the diodes. Displays that are able to convert electricity into light are called emissive or active displays.

• How it works: The basic structure of an OLED display consists of an emissive layer placed between a cathode (which injects electrons) and an anode (which removes electrons). Electricity enters through the cathode layer, passes into the emissive layer and conductive layer to create light, then out through the anode layer.

• Uses: OLED display technology can be used in foldable smartphones, rollable TVs, as backlighting in LCD TVs, for gaming, and inside VR headsets.

• Positives: OLED displays deliver excellent picture quality, wide viewing angles, infinite contrast, fast response rate, and brilliant colors with true blacks. They are energy-efficient, simpler to make, and much thinner than LCDs. OLED panels can be built to be flexible and even rollable.

• Negatives: OLED displays are sensitive to light and moisture. Blue LEDs degrade faster than other LED colors, causing color distortion over time. They are also prone to image retention and burn-in.

• Active Matrix Organic Light Emitting Diode (AMOLED)

  • How it works: AMOLED displays are a type of display technology that utilizes light-emitting diodes (LEDs) as the light source. LED displays are commonly used in various devices, including mobile phones, tablets, and monitors.

LED displays can be categorized into two main types: LCD with LED backlight and OLED.

1. LCD with LED Backlight: LCD with LED backlight displays, also known as LED-LCD displays, use a liquid crystal display (LCD) panel with LED backlighting. The LCD panel controls the light passing through it, while the LED backlight provides the light source.

There are different types of LCD with LED backlight displays:

• Full-Array LED: In full-array LED displays, the LEDs are distributed across the entire back panel of the display. They can be further categorized into two subtypes:

  • Direct-lit: Direct-lit displays have LEDs placed evenly behind the entire screen.

  • Local dimming: Local dimming displays divide the screen into zones, with each zone having its own set of LEDs. This allows for more precise control of brightness and contrast in different areas of the screen.

• Edge-lit LED: In edge-lit LED displays, the LEDs are placed around the edges of the display panel. The light is then spread across the screen using light guides or diffusers. Edge-lit displays are thinner and lighter than full-array displays but may have less uniform backlighting.

2. OLED (Organic Light-Emitting Diode): OLED displays use organic compounds that emit light when an electric current is applied. Unlike LCD displays, OLED displays do not require a separate backlight. Each pixel in an OLED display emits its own light, allowing for individual pixel control and deep blacks.

There are different types of OLED displays:

• AMOLED (Active-Matrix OLED): AMOLED displays use an active-matrix backplane, which allows for faster pixel response times and better image quality. AMOLED displays are commonly used in smartphones and high-end mobile devices.

• PMOLED (Passive-Matrix OLED): PMOLED displays use a passive-matrix backplane, which is simpler and less expensive but has slower response times. PMOLED displays are commonly used in smaller devices, such as wearable gadgets and small information displays.

Each type of display has its own characteristics, advantages, and disadvantages. LCD displays with LED backlighting generally offer good color reproduction, high brightness, and wide viewing angles. OLED displays provide deeper blacks, better contrast, and potentially more vibrant colors. However, OLED displays can be more susceptible to burn-in and have a shorter lifespan compared to LCD displays.

When troubleshooting displays, it's important to consider the specific type of display being used and its unique characteristics in order to diagnose and resolve any issues effectively.