display technologies ,old,new,next generation technologies

DISPLAY TECHNOLOGIES

OLD DISPLAY TECHNOLOGY

Cathode ray tubeCathode-Ray Tube or CRT (sometimes called the Braun Tube) has

played an important part in displaying images, movies, and information

The cathode ray tube or (CRT) is a vacuum tube containing one or more electron guns usually three red, green and blue (a source of electrons or electron emitter) and a fluorescent screen used to view images.

cheap to manufacture and the ability to display high quality images.

Working

Figure : Cutaway rendering of a colour CRT:

1. Three Electron guns (for red, green, and blue phosphor dots) 2. Electron beams 3. Focusing coils 4. Deflection coils 5. Anode connection 6. Mask for separating beams for red, green, and blue part of displayed image 7. Phosphor layer with red, green, and blue zones 8. Close-up of the phosphor-coated inner side of the screen

ADVANTAGES

High contrast ratio (over 15,000:1), excellent colour, fairly wide colour gamut and low black level.

No native resolution; the only current display technology capable of true multisyncing

No input lag. Near zero color, saturation, contrast or brightness

distortion. Excellent viewing angle. Allows the use of light guns/pens.

DISADVANTAGES

» Large size and weight, especially for bigger screens (a 20-inch (51 cm) unit weighs about 50 lb (23 kg)).

» Geometric distortion caused by variable beam travel distances. » High power consumption. On average, a CRT monitor consumes 2–10×

the power that an identically sized LCD monitor would consume, depending on the type of backlight used in the LCD screen, and its brightness setting.

» A lot of heat can be emitted during operation, due to relatively high power consumption.

» Sensitive to magnetic interference, which can cause the image to shimmer or the colors to shift.

LCD» Liquid crystals were first discovered in 1888.

» A liquid-crystal display better known as (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.

» The LCD screen is more energy efficient and can be disposed of more safely than a CRT .

Working

Figure 1.2 Reflective twisted nematic liquid crystal display

Figure:1. Polarizing filter film with a vertical axis to polarize light as it enters. 2. Glass substrate with ITO electrodes. 3. Twisted nematic liquid crystal. 4. Glass substrate with common electrode film (ITO) with horizontal ridges to line up with the horizontal filter. 5. Polarizing filter film with a horizontal axis to block/pass light. 6. Reflective surface to send light back to viewer. (In a backlit LCD, this layer is replaced with a light source.)

Passive and active-matrix

Passive matrix Active Matrix

Twisted nematic (TN) Vertical alignment (VA) Blue phase mode

LCD Working Video

» Very compact and light. » Low power consumption. » Very little heat emitted during operation, due to low power

consumption. » The possible ability to have little or no flicker depending on

backlight technology. » Is very thin compared to a CRT monitor.» Emits much less undesirable electromagnetic radiation than a CRT

monitor.» Can be made in almost any size or shape. » Can be made to large sizes (more than 24 inches) lightly and

relatively inexpensively.

Advantages

» Limited viewing angle.» Uneven backlighting in some (mostly older) monitors, causing

brightness distortion, especially toward the edges. » Dead or stuck pixels may occur during manufacturing or through

use. » Poor display in direct sunlight, often completely unviewable.

Cannot be used with light guns/pens. » Hard to read when wearing polarized sunglasses.

Disadvantages

» A plasma display panel (PDP) is a type of flat panel display common to large TV displays 30 inches (76 cm) or larger.

» They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps.

» Plasma displays are bright (1,000 lux or higher for the module), have a wide color gamut, and can be produced in fairly large sizes—up to 3.8 metres (150 in) diagonally

PLASMA

Working

Advantages

» Picture quality » Capable of producing deeper blacks allowing for

superior contrast ratio » Wider viewing angles than those of LCD; images do

not suffer from degradation at high angles like LCDs » Less visible motion blur,very high refresh rates and a

faster response time, contributing to superior performance when displaying content with significant amounts of rapid motion.

Disadvantages

» Screen-door effects (black lines between rows of pixels) become noticeable on screen sizes larger than 127 cm (50 in); the effect is more visible at shorter viewing distances.

» Uses more electrical power, on average, than an LCD TV. » Plasma displays are generally heavier than LCD, and may require

more careful handling such as being kept upright.

NEW DISPLAY TECHNOLOGIES

• Traditional LCD displays use a cold-cathode fluorescent lamp (CCFL) as the light source behind the LCD layer.

• LCD display technology is getting more refined with each passing year. LCD displays are low-cost, lightweight and can produce excellent images, and new LCD developments such as In-Plane Switching (IPS) promise to give LCD displays much wider viewing angles and better visibility in bright light.

• OLED,LED BACKLIT,IPS

OLED

Working

Figure: Schematic of a bilayer OLED: 1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)

LG Curved OLED TV: Design Story

Advantages

• Lower cost in the future• Lightweight and flexible plastic

substrates• Wider viewing angles and improved

brightness• Better power efficiency and thickness• Response time

Disadvantages

» Current costs» Lifespan » Colour balance issues » Water damage

LED-backlit LCD display

IPod Touch 2G BacklightComparison of LCD, edge-lit LED and LED TVs

Techniques

• Full-array LEDs • Dynamic “local dimming” LEDs

• Technology

Advantages

• Heightened Contrast• Increased Colour Accuracy• Energy Efficiency• Thin and Lightweight

Disadvantages

• Sensitive to ESD• Sensitive to voltage spikes• Heat dissipation in some applications• Not true full spectrum White LED

IPS DISPLAY

Schematic diagram of LCD with in-plane switching (IPS)

Technology

Manufactures

Super PLS

» Further improvement in viewing angle

» 10 percent increase in brightness » Up to 15 percent decrease in

production costs » Increased image quality » Flexible panel

Advantages

» IPS panels display consistent, accurate color from all viewing angles

» Unlike TN LCDs, IPS panels do not lighten or show tailing when touched. This is important for touch-screen devices, such as smartphones and tablets.

» IPS panels can process high speed signals without data loss by using copper wiring with low resistance values.

» IPS panels offer clear images and stable response time.

Disadvantages

» IPS panels require up to 15% more power than TN displays.» IPS panels are more expensive to produce than TN displays.

4K DISPLAYS

16:9 resolutions in comparison

Resolutions

• Ultra HD • Digital cinema• Streaming video

Figure: 8K UHD, 4K SHD, FHD and SD

List of 4K monitors, TVs and projectors

65 (164 cm) X Series BRAVIA 4K*1 LED backlight / 3D TV

Next generation of display technology

» Quantum dot display » Surface-conduction electron-emitter display » Laser video display » Carbon nanotube » Interferometric modulator display

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