125617764-HAIER-All-About-LED-TVs-Training-Presentation.pdf

Haier TV Technical Training Document

Table of Contents

What is an LED?Pros and Cons of LEDWhat types of backlights are in the LCD TV?

What is an LED TV?Which technique is better?

LED-backlit vs. CCFL-backlit

LED TV vs. LCD TV

Haier LED TV ListHaier LED TV Main Features

Differences between LED & LCD Terminal Connections

What is an LED?• Like a normal diode, the LED consists of a chip of

semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge- carriers—electrons and holes—flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.

• The wavelength of the light emitted, and therefore its color, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a non-radiative transition which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near- infrared, visible or near-ultraviolet light.

• LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have made possible the production of devices with ever-shorter wavelengths, producing light in a variety of colors.

• LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially GaN/InGaN, also use sapphire substrate.

Most materials used for LED production have very high refractive indices. This means that much light will be reflected back in to the material at the material/air surface interface. Therefore Light extraction in LEDs is an important aspect of LED production, subject to much research and development.

Pros and Cons of LED

• Efficiency: LEDs produce more light per watt than incandescent bulbs.• Color: LEDs can emit light of an intended color without the use of color filters that traditional lighting methods

require. This is more efficient and can lower initial costs.• Size: LEDs can be very small (smaller than 2 mm2) and are easily populated onto printed circuit boards.• On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds.

LEDs used in communications devices can have even faster response times.• Cycling: LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps

that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.• Dimming: LEDs can very easily be dimmed either by pulse-width modulation or lowering the forward current.• Cool light: In contrast to most light sources, LEDs radiate very little heat in the form of IR that can cause damage

to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.• Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.• Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life,

though time to complete failure may be longer. Fluorescent tubes typically are rated at about 10,000 to 15,000 hours, depending partly on the conditions of use, and incandescent light bulbs at 1,000–2,000 hours.

• Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.

• Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.

• Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.

Pros:

Pros and Cons of LED•High initial price: LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than most conventional lighting technologies. The additional expense partially stems from the relatively low lumen output and the drive circuitry and power supplies needed.•Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment. Over-driving the LED in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure. Adequate heat-sinking is required to maintain long life. •Voltage sensitivity: LEDs must be supplied with the voltage above the threshold and a current below the rating. This can involve series resistors or current-regulated power supplies.•Light quality: Most cool-white LEDs have spectra that differ significantly from a black body radiator like the sun or an incandescent light. The spike at 460 nm and dip at 500 nm can cause the color of objects to be perceived differently under cool-white LED illumination than sunlight or incandescent sources, due to metamerism, red surfaces being rendered particularly badly by typical phosphor based cool-white LEDs. However, the color rendering properties of common fluorescent lamps are often inferior to what is now available in state-of-art white LEDs.•Area light source: LEDs do not approximate a “point source” of light, but rather a lambertian distribution. So LEDs are difficult to use in applications requiring a spherical light field. LEDs are not capable of providing divergence below a few degrees. This is contrasted with lasers, which can produce beams with divergences of 0.2 degrees or less.

Cons:

•Blue hazard: There is a concern that blue LEDs and cool-white LEDs are now capable of exceeding safe limits of the so-called blue-light hazard as defined in eye safety specifications such as ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems.•Blue pollution: Because cool-white LEDs (i.e., LEDs with high color temperature) emit proportionally more blue light than conventional outdoor light sources such as high-pressure sodium lamps, the strong wavelength dependence of

What types of backlights are in the LCD TV?

• At present there are two main methods of backlighting in LCD flat panels: Cold-Cathode Fluorescent Lamp (CCFL) and LED (light-emitting diode). There are several others, and these includes S***'s Hot Cathode Fluorescent Lamp (HCFL), though only one television currently uses this technology.

CCFL is the most widespread method of backlighting for LCD televisions, and consists of a series of tubes laid horizontally down the screen.

A cutaway of a CCFL-backlit LCD showing the different layers of polarizers and filters, and the thin fluorescent tubes themselves on the right. (Credit: Ty Pendlebury/CNET Australia)

• LED backlighting has been in use in televisions since 2004 when it first appeared on a S*** WEGA television. Though there are several different ways of backlighting using LEDs, the idea is the same: A lot of LED bulbs are used to light the screen.

LED-backlit vs. CCFL-backlit

LED-backlit LCD TVs differ from conventional CCFL-backlit LCD TVs in the following:

• They can produce an image with greater dynamic contrast compared with CCFL-backlit LCD TVs.• With Edge-LED lighting they can be extremely slim. Current models on the market can be less

than one inch thick.• They can offer a wider color gamut, especially when RGB-LED backlighting is used.• Lesser environmental pollution on disposal.• Higher cost due to current market product placement.

LED-backlit CCFL-backlit

What is an LED TV?•

LED-backlit LCD television (called LED TV by many TV manufacturers and not to be confused with true LED displays) is an LCD TV that uses LED backlighting rather than fluorescent lights used in traditional LCD televisions.

•

The LEDs can come in two forms, Dynamic RGB LEDs which are positioned behind the panel, or white Edge-LEDs positioned around the rim of the screen which use a special diffusion panel to spread the light evenly behind the screen.

RGB Dynamic LEDsThis method of backlighting allows dimming to occur locally 

creating specific areas of darkness on the screen. This can show

truer blacks, whites and PRs at much higher dynamic contrast 

ratios, at the cost of less detail in small bright objects on a dark 

background, such as star fields.

Edge‐LEDsThis method of backlighting allows for LED‐backlit TVs to become 

extremely thin. The light is diffused across the screen by a special 

panel which produces a uniform color range across the screen.Sharp also has LED backlighting technology that aligns the LEDs 

on back of the TV like the RGB Dynamic LED backlight, but it lacks 

the local dimming of other sets.

Which technique is better?

They both have their pros and cons. LCD TVs using edge-lit LCDs can be ultra-thin, because the LED sources are on the side. Edge-lit LED-lit LCDs are also less expensive than LCD TVs using LED backlit technology.On the other hand, LCD TVs that use LEDs across the rear of the display can create sharply deeper blacks, through a technique called “local dimming.” When a scene calls for a dark image, the LEDs in that area can be shut off completely, so no light leaks through what should look black. Edge-lit LED-based LCD

RGB Dynamic LED-based LCD

LED TV vs. LCD TV

• CONTRAST / BLACK LEVELS• Traditional LCD televisions always have their backlight on when the TV is on. To create black or

dark areas the screen must block the light by twisting the crystals to a closed position, often resulting in a lower contrast ratio and less detail in dark areas of the picture. This is a shortcoming in LCD technology that LED TVs with local dimming are attempting to correct. With the controlled backlighting the LEDs can be dimmed in dark areas of the picture to create darker blacks and better detail in dark scenes.

• ADVANTAGE: Local dimming LED TV technology has a clear advantage in contrast and black levels.

• COLOR ACCURACY• With white LED backlights the difference between the two technologies isn't very significant, but

with RGB colored lights or a color wheel to affect the backlight color the LED TVs have an advantage in displaying realistic color.

• ADVANTAGE: Without colored LEDs or another way to affect the backlight color these two technologies are nearly equal. With colored backlighting LED takes the advantage.

LED TV vs. LCD TV• VIEWING ANGLES• While traditional LCDs have improved their useable viewing angles over the years this is still a

shortcoming of the technology itself and even the best LCDs will suffer from contrast degradation when viewed from angles wider than around 30 degrees off center. The LED backlit LCDs we've seen have done a fantastic job of correcting this issue and have viewing angles that rival plasma TVs (but at a much higher price).

• ADVANTAGE: LED TV

• FUNCTIONAL CONSIDERATIONS• COMPUTER USE• LCD technology of either sort is immune to screen burn-in so they are equally well suited for

computer use.• ADVANTAGE: Even.

• FAST-MOVING VIDEO PLAYBACK• Displaying fast moving video is a function of the response time and refresh rate in LCD and LED

televisions. The type of backlighting in the TV has no effect on the reproduction of fast moving video. You will want to compare response times and refresh rates when making a purchase decision.

• ADVANTAGE: Even

LED TV vs. LCD TV• LONGEVITY• Most manufacturers are claiming approximately 100,000 hours lifetime for their televisions. LED

backlit televisions are brand new and don't have much of a track record but LED lights are typically long lived.

• ADVANTAGE: LED televisions do not have much history. They should have an advantage since the flourescent style backlighting used in traditional LCDs ever so slightly change color hue over time. Light emitting diode technology should not have as much degradation over time. Quality of manufacture for either technology will also matter.

• PRODUCTION SIZE AND COST• LED backlight televisions are currently available in sizes ranging from 22 inches to 70 inches.

Traditional LCD televisions are available in sizes as small as 15 inches and as large as 65 inches. When comparing LED TVs and traditional LCDs in the same size the LED backlit model will be more expensive, in some cases vastly more expensive.

• ADVANTAGE: There is certainly a much larger number of LCD TVs being produced today, with LED televisions demanding a premium for the often better picture quality.

• POWER CONSUMPTION• The local dimming LED TVs we've come across have used quite a bit more power than a traditional

LCD TV in the same screen size. This type of LED television approaches plasma displays in power usage. The edge lit LED televisions use less power than an LCD of the same size.

• ADVANTAGE: 1st: Edge lit LED, 2nd LCD TV (flourescent), 3rd: Local dimming LED.

Haier LED TV Main Features

Haier LED TV Main Features

Haier LED TV Main Features

Haier LED TV Main Features

Haier LED TV Main Features

Haier LED TV Main Features

Haier LED TV Main Features

• MEMC - Motion Estimation & Motion Compensation:Motion estimation examines the movement of objects in an image sequence to try to

obtain vectors representing the estimated motion. Motion compensation uses the knowledge of object motion so obtained to achieve data compression. In interframe coding, motion estimation and compensation have become powerful techniques to eliminate the temporal redundancy due to high correlation between consecutive frames.

• AVL - Automatic Volume Leveler(Limiter):Limit the maximum volume level. Protect your hearing and also the speakers from

the over-the-top sound/noise.

Glossaries:

Haier LED TV Main Features

• SRS - Sound Retrieval System: The SRS technology applies head-related transfer functions (HRTFs) to create an immersive

3D soundfield using only two speakers, widening the “sweet spot,” creating a more spacious sense of ambience, and producing strong localization cues for discrete instruments within an audio mix. SRS is not a Dolby matrix surround decoder but works with normal stereo recordings.

• DCR - Dynamic Contrast Ratio:Moving from a system that displays a static motionless image to a system that displays a

dynamic, changing picture slightly complicates the definition of the contrast ratio, because of the need to take into account the extra temporal dimension to the measuring process. Thus the ratio of the luminosity of the brightest and the darkest color the system is capable of producing simultaneously at any instant of time is called static contrast ratio, while the ratio of the luminosity of the brightest and the darkest color the system is capable of producing over time is called dynamic contrast ratio. Haier LED TV has 1,000,000:1 DCR to make the dynamic pictures more smooth.

Glossaries:

Differences between LED & LCD Terminal Connections

Q: How to identify which mainboard is for LED and which LCD?A: Please check the pictures out. LED TV mainboard’s terminals are aligned to make the cables connect with the board

HORIZONTALLY. On the contrary, terminals on LCD TV, VERTICALLY.

LED LCD

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