Understanding Display
Display means to arrange something in a prominent place to be seen easily. It means a piece of work to be presented visually. In technological terms, we may define a display as an output device that can present information visually. The most prominent feature of the display is its clarity. Clarity can be understood as the quality of the visual information presented. One of the significant factors on which clarity depends is resolution.
What is Resolution?
Information is presented on display by a series of dots or pixels. Resolution can be stated as a matrix of these pixels. Consider a display with an industry-standard Full HD 1080p resolution. The resolution of this display is 1920 x 1080. This means that the width of the display will be 1,920 pixels, and the height of the display will be 1,080 pixels. In total, the display will have 2,073,600 pixels.
It is a no-brainer that most of our time today is spent looking at a display. Display technologies play a vital role in offering superior picture quality.
Let’s explore different display technologies.
Types of Displays
CRT
CRT stands for Cathode Ray Tube. It can be described as a vacuum tube that produces images when an electron beam strikes a phosphorescent surface. It is an envelope composed of comprehensive, fragile, and heavy glass.
How Does CRT Work?
A cathode is indirectly heated to emit electrons. These electrons are then passed through the control grid. The control grid has a centrally located coaxial hole with the tube’. A negative voltage is supplied to the grid. This negative charge repels electrons and generates a narrow beam. Thus, we can control the beam’s intensity by controlling the negative voltage applied to the control grid. This electron beam is then passed through a series of accelerating and focusing anodes. These anodes are supplied with a high positive voltage, increasing the beam’s velocity and keeping the beam focused. Thus, the beam’s focus can be controlled by controlling the positive voltage applied at the anodes. The focussed beam is passed through x and y deflection plates with a very high velocity. These are horizontal deflection plates and vertical deflection plates, respectively. The forces on both plates are controlled to display the waveform on the screen. The focussed accelerated, and the deflected beam is then made to strike the screen with very high velocity. The inner side of the screen is coated with a particular type of phosphor, and this layer converts electrical energy into light energy. Thus, whenever an electron strikes the screen with a very high velocity, it generates a bright spot on the screen.
LCD
LCD stands for Liquid Crystal Display and is generally used in cell phones, computer monitors, calculators, and digital cameras. Compared to CRTs, they occupy about 60% less space which becomes a huge factor for their preference over the former.
In LCD, liquid crystals are in a state having properties between the liquid state and solid state. These crystals can flow like a liquid, but the molecules can be oriented crystal-like.
How does LCD work?
An LCD screen consists of a horizontal polarizer (which blocks vertical light waves) and a vertical polarizer (which blocks horizontal light waves). The liquid crystal operated with a battery is implemented between the horizontal and vertical polarizer. When the liquid crystal is energized, its elements are correctly aligned, and when it is not energized, it is misaligned. Liquid crystal helps to polarize vertical light waves into horizontal light waves. The color filter (red) is placed in front of the horizontal filter to produce a red color. Similarly, a green and blue color filter produces an image. Any LCD contains millions of such pixels to produce different images.
LED
LED stands for Light Emitting Diode. The LED display uses a group of LEDs as a source of light. In other words, it uses an array of LEDs as pixels for visual presentation. LEDs are used in mobile phones, TV, tablets, and laptops. They find their use in billboards and other outdoor applications due to their brightness.
An LED display is a particular type of LCD where a backlight consists of LEDs instead of CCFLs.
How Does LED work?
LED backlight (source of light) is passed through a vertical polarizer which, after passing through the liquid crystal, is allowed to pass through a horizontal polarizer. The color filter is placed before a horizontal polarizer to produce images. LED display comprises RGB (Red, Green, Blue) LEDs arranged in a fixed pattern. RGB combine to form a pixel. Innumerable colors can be formed by changing the intensity of diodes.
OLED
OLED stands for Organic Light Emitting Diode. OLED displays do not require a backlight and are thin. They are used in mobile phones, VR headsets, tablets, digital cameras, TVs, and laptops. OLED is considered one of the best display technologies to date.
In OLED, organic layers are responsible for the emission of light.
How Does OLED Work?
In semiconductors, the electrons in the stable state are present at the HOMO (Highest Occupied Molecular Orbital) level. The electrons in the excited state are present at LUMO (Lowest Unoccupied Molecular Orbital) level. This electronic semiconductor is connected to the external power supply. Due to this, electrons move from HOMO to LUMO level. They recombine with holes and emit light as they enter the LUMO level. A hole transfer layer is added to reduce the HOMO level and anode barrier; similarly, an electron transfer layer reduces the barrier between LUMO and cathode. Such three OLEDs are placed behind color filters to control each sub-pixel independently. Electron flow and recombination rate can be controlled to produce an image using varying power supplies.
How is an OLED Display different from an LED Display?
Compared to LED displays, it has a higher contrast ratio. Also, the OLED display has a wider viewing angle since OLEDs are much closer to the screen, and light does have to pass through the liquid crystal layer. It has a better response time compared to the LED display.
Future of Displays
With the growth in technology, display technology will see many improvements in the coming years. This includes advancements in virtual and augmented reality glasses, 3D holograms, folding screens, and direct projections (on window screens of the car). Consumers will use these displays to control their appliances. The new types of displays will also influence the presentation of content. Many speculate quantum dot display technology could replace Liquid Crystal Displays (LCDs) in devices such as desktops, notebook computers, and televisions in the future and may create a market worth $8 billion for quantum dot-based components by 2023.
*Disclaimer: This report is based on information that is publicly available and is considered to be reliable. However, Lumenci cannot be held responsible for the accuracy or reliability of this data.
Author
Editorial Team at Lumenci
Through Lumenci blogs and reports, we share important highlights from the latest technological advancements and provide an in-depth understanding of their Intellectual Property (IP). Our goal is to showcase the significance of IP in the ever-evolving world of technology.
