lcd panel taking advantage of fluorescent lamp price
The main functionality of the Basic Input/Output System (BIOS) is to perform the initial hardware checks after the computer is powered on and start up the operating system.
Which of the acronyms listed below refers to a series of basic hardware diagnostic tests performed by the startup BIOS after the computer is powered on?
After replacing a modular hardware component inside computer case, the updated information about specific parameters of the new device can be stored in: (Select 2 answers)
After completing the initial diagnostics and assigning system resources, the startup BIOS program checks for information about secondary storage devices that might contain the OS. The list of devices and the order in which they should be checked can be found and arranged in the CMOS setup utility, and this option is commonly referred to as:
After launching Windows Virtual PC application technician receives error message stating that the Hardware-Assisted Virtualization (HAV) feature is not enabled on the computer. Which of the following steps might help in fixing this problem?
Responsible for performing installations and repairs (motors, starters, fuses, electrical power to machine etc.) for industrial equipment and machines in order to support the achievement of Nelson-Miller’s business goals and objectives:
• Provide electrical emergency/unscheduled diagnostics, repairs of production equipment during production and performs scheduled electrical maintenance repairs of production equipment during machine service.
When it comes todisplay technologies such asprojectorsand panels, factors such as resolution and refresh rate are often discussed. But the underlying technology is equally, if not more, important. There are tons of different types of screens, from OLED and LED to TN, VA, and IPS. Learn about the various monitor and television types, from operation to pros and cons!
The most common form of monitor or TV on the market is LCD or Liquid Crystal Display. As the name suggests, LCDs use liquid crystals that alter the light to generate a specific colour. So some form of backlighting is necessary. Often, it’s LED lighting. But there are multiple forms of backlighting.
LCDs have utilized CCFLs or cold cathode fluorescent lamps. An LCD panel lit with CCFL backlighting benefits from extremely uniform illumination for a pretty even level of brightness across the entire screen. However, this comes at the expense of picture quality. Unlike an LED TV, cold cathode fluorescent lamp LCD monitors lack dimming capabilities. Since the brightness level is even throughout the entire array, a darker portion of scenes might look overly lit or washed out. While that might not be as obvious in a room filled with ambient light, under ideal movie-watching conditions, or in a dark room, it’s noticeable. LED TVs have mostly replaced CCFL.
An LCD panel is transmissive rather than emissive. Composition depends on the specific form of LCD being used, but generally, pixels are made up of subpixel layers that comprise the RGB (red-green-blue) colour spectrum and control the light that passes through. A backlight is needed, and it’s usually LED for modern monitors.
Please note that some of the mentioned types may be considered a sub-category of LCD TVs; therefore, some of the names may vary depending on the manufacturer and the market.
1)Film layer that polarizes light entering2)glass substrate that dictates the dark shapes when the LCD screen is on3)Liquid crystal layer4)glass substrate that lines up with the horizontal filter5)Horizontal film filter letting light through or blocking it6)Reflective surface transmitting an image to the viewer
While many newer TVs and monitors are marketed as LED TVs, it’s sort of the same as an LCD TV. Whereas LCD refers to a display type, LED points to the backlighting in liquid crystal display instead. As such, LED TV is a subset of LCD. Rather than CCFLs, LEDs are light-emitting diodes or semiconductor light sources which generate light when a current passes through.
LED TVs boast several different benefits. Physically, LED television tends to be slimmer than CCFL-based LCD panels, and viewing angles are generally better than on non-LED LCD monitors. So if you’re at an angle, the picture remains relatively clear nonetheless. LEDs are alsoextremely long-lasting as well as more energy-efficient. As such, you can expect a lengthy lifespan and low power draw. Chances are you’ll upgrade to a new telly, or an internal part will go out far before any LEDs cease functioning.
Please note that some of the mentioned types may be considered a sub-category of LED TVs; therefore, some of the names may vary depending on the manufacturer and the market.
Further segmenting LED TVs down, you"ll find TN panels. A TN or twisted nematic display is a type of LED TV that offers a low-cost solution with a low response time and low input lag.
These displays are known for their high refresh rates, ranging from 100Hz to 144Hz or higher. As a result, many monitors marketed towards gamers feature TN technology. The fast response time and low input lag make them ideal for fast-paced action and gaming. However, TN panels have some limitations.
They suffer from inferior colour reproduction, meaning that the colours they display may be less accurate and vibrant than other technologies. Additionally, they have poor viewing angles, meaning the picture quality can degrade when viewed from certain angles. This is due to the way the liquid crystal molecules point at the viewer and the orientation of the light polarizers at 90-degree angles.
Overall, while TN panels are an affordable and fast option, they may not be the best choice for those looking for accurate colour reproduction and wide viewing angles.
Like TN, IPS or In-plane Switching displays are a subset of LED panels. IPS monitors tend to boast accurate colour reproduction and great viewing angles. Price is higher than on TN monitors, but in-plane switching TVs generally feature a better picture when compared with twisted nematic sets. Latency and response time can be higher on IPS monitors meaning not all are ideal for gaming.
An IPS display aligns liquid crystals in parallel for lush colours. Polarizing filters have transmission axes aligned in the same direction. Because the electrode alignment differs from TN panels, black levels, viewing angles, and colour accuracy is much better. TN liquid crystals are perpendicular.
A VA or vertical alignment monitor is a type of LED monitor that features excellent contrast ratios, colour reproduction, and viewing angles. This is achieved by using crystals that are perpendicular to the polarizers at right angles, similar to the technology used in TN monitors. VA monitors are known for their deep blacks and vibrant colours, making them popular for media consumption and gaming.
They also have better viewing angles than TN monitors, meaning that the picture quality remains consistent when viewed from different angles. However, the response time of a VA monitor is not as fast as that of a TN monitor, which can be a concern for those looking to use the monitor for fast-paced action or gaming.
The pricing of VA monitors varies, but they are typically more expensive than TN monitors and less costly than IPS or OLED monitors. Overall, VA monitors are an excellent option for those looking for a balance between good picture quality and affordability.
A quantum dot LED TV or QLED is yet another form of LED television. But it’s drastically different from other LED variants. Whereas most LED panels use a white backlight, quantum dot televisions opt for blue lights. In front of these blue LEDs sits a thin layer of quantum dots. These quantum dots in a screen glow at specific wavelengths of colour, either red, green, or blue, therefore comprising the entire RGB (red-green-blue) colour spectrum required to create a colour TV image.
Quantum Dot TV (QD-TV): A type of television that uses quantum dots, also known as semiconductor nanocrystals, to produce more accurate and vibrant colours.
Please note that some of the mentioned types may be considered a sub-category of Quantum Dot TVs; therefore, some of the names may vary depending on the manufacturer and the market. Also, it"s worth mentioning that not all brands use the same technology. Some are using QD films or QD-LEDs, others are using QD-OLEDs, and the list could go on.
An OLED or organic light-emitting diode display isn’t another variation of LED. OLEDs use negatively and positively charged ions for illuminating individual pixels. By contrast, LCD/LED TVs use a backlight that can make an unwanted glow. In OLED display, there are several layers, including a substrate, an anode, a hole injection layer, a hole transport layer, an emissive layer, a blocking layer, an electron transport layer, and a cathode. The emissive layer, comprised of an electroluminescent layer of film, is nestled between an electron-injecting cathode and an electron removal layer, the anode. OLEDs benefit from darker blacks and eschew any unwanted screen glow. Because OLED panels are made up of millions of individual subpixels, the pixels themselves emit light, and it’s, therefore, an emissive display as opposed to a transmissive technology like LCD/LED panels where a backlight is required behind the pixels themselves.
The image quality is top-notch. OLED TVs feature superb local dimming capabilities. The contrast ratio is unrivalled, even by the best of QLEDs, since pixels not used may be turned off. There’s no light bleed, black levels are incredible, excellent screen uniformity, and viewing angles don’t degrade the picture. Unfortunately, this comes at a cost. OLEDs are pricey, and the image isn’t as bright overall when compared to LED panels. For viewing in a darkened room, that’s fine, but ambient lighting isn’t ideal for OLED use.
Please note that OLED technology can be applied to various displays and devices, and the list mentioned above may not be exhaustive. Also, some types may be considered a sub-category of OLED.
As you can see, a wide variety of displays are available on the market today, each with their unique advantages and disadvantages. While many monitors and TVs are referred to by various names, such as LED, IPS, VA, TN, or QLED, many are variations of LCD panels. The specific technology used in a display, such as the colour of backlighting and the alignment of pixels, plays a major role in determining the overall picture quality.
When choosing the right type of monitor or display for your needs, it"s important to consider all the options available and weigh the pros and cons of each one. This can include things like resolution, refresh rate, response time, colour accuracy, and more subjective factors like overall picture quality and viewing angles.
Do you wonder what’s better: fluorescent lights (including compact fluorescent lights, or CFLs) or light emitting diodes (LEDs)? Well here’s a head-to-head comparison of the two followed by an in-depth discussion of each technology in turn.
Fluorescent light bulbs are a specific type of gas-discharge light (also known as a high intensity discharge, HID, or arc light). CFL is an acronym that stands for compact fluorescent light. Standard fluorescent lights are available in tubes (generally 48 to 84 inches in length). CFLs are much smaller. They are still tubes but they are, as the name implies, “compact.” CFLs were designed to replace standard applications for incandescent bulbs as they are both more efficient and longer lasting.
Fluorescent bulbs produce light by converting ultraviolet emissions with a fluorescent coating on the inside of the tube. UV radiation is generated in the first place by an electrical charge that is run through the inert mercury glass internal to the bulb. The gas is excited by the electricity andreleases ultraviolet radiation as a consequence. Fluorescent lights require ignition, which is typically provided by a voltage pulse or a third electrode (an additional metal part) internal to the bulb. Starting is relatively simple with small tubes but can require significant voltage with larger lights.
Fluorescent light bulbs previously required a “warm-up” period in order to evaporate the internal gas into plasma, but now there are several near-instantaneous starting technologies for fluorescent light (those include “quick-start,” “instant start,” and “rapid-start”). Additionally, as the light heats up it requires additional voltage to operate. Voltage requirements in fluorescent bulbs are balanced by a ballast (a magnetic device in older bulbs and an electrical one in newer fluorescent technology). As the fluorescent light ages, more and more voltage is required to produce the same amount of light until eventually the voltage exceeds the fixed resistance provided by the ballast and the light goes out (fails). Fluorescent lights become less and less efficient over time because they must use more and more voltage to produce the same lumen output as the light degrades.
Fluorescent technology has been around for more than 100 years and it generally represents a high efficiency way to provide lighting over a vast area. The lights are much more efficient as well as longer lasting than incandescent bulbs, however, they fail in both categories when compared to LED.
Fluorescent lights contain toxic mercury.Mercury, as well as the phosphor inside the bulbs, are hazardous materials that present a waste disposal issue at the end of a light’s life. Broken bulbs release a small amount of toxic mercury as a gas and the rest is contained in the glass itself.
Fluorescent lights age significantly if they are frequently switched on and off.Typical lamp life for a CFL is about 10,000 hours but this can degrade as a consequence of frequent switching (turning on and off). Burning life is extended if lamps remain on continuously for long periods of time. It’s worth thinking about in the event that you are using CFLs in conjunction with motion sensors that frequently activate and time out.
Fluorescent lights are omnidirectional.Omnidirectional lights produce light in 360 degrees. This is a large system inefficiency because at least half of the light needs to be reflected and redirected to the desired area being illuminated. It also means that more accessory parts are required in the light fixture itself in order to reflect or focus the luminous output of the bulb (thus increasing unit costs).
Older fluorescent lights have a brief warm-up period. Once the arc is ignited it melts and evaporates metal salts internal to the device. The light doesn’t arrive at full power until the salts are fully evaporated into plasma. This is corrected in many newer models that utilize “rapid start” or similar technologies.
Fluorescent lighting emits a small amount of UV radiation.Ultraviolet light is known to cause fading of dyed items or paintings exposed to their light.
Fluorescent lights require a ballast to stabilize the light.In the event that there is a minor flaw in the ballastthe light may produce an audible hum or buzz.
Common applications for fluorescent lighting include warehouses and schools or commercial buildings. CFLs are also used as a replacement for incandescent lights in many residential applications.
When current passes through the semiconductor material the device emits visible light.It is very much the opposite of a photovoltaic cell(a device that converts visible light into electrical current).
LEDs have an extremely long lifespanrelative to every other lighting technology (including fluorescent lights). New LEDs can last 50,000 to 100,000 hours or more. The typical lifespan for a fluorescent bulb, by comparison, is 10-25% as long at best (roughly 10,000 hours).
LEDs areextremely energy efficientrelative to every other commercially available lighting technology. There are several reasons for this, including the fact that they waste very little energy in the form of infrared radiation (much different than most conventional lights to include fluorescent lights), and they emit light directionally (over 180 degrees versus 360 degrees, which means there are far fewer losses from the need to redirect or reflect light).
Color:LEDs can be designed to generate the entire spectrum of visible light colors without having to use the traditional color filters required by traditional lighting solutions.
In particular, LED lights are relatively expensive. The up-front costs of an LED lighting project are typically greater than most of the alternatives. This is by far the biggest downside that needs to be considered. That said, the price of LEDs are rapidly decreasing and as they continue to be adopted en masse the price will continue to drop. (If you received a proposal for LED lights that just costs too much, don"t give up hope. Value engineering can help.)
The first practical use of LEDs was in circuit boards for computers. Since then they have gradually expanded their applications to include traffic lights, lighted signs, and more recently, indoor and outdoor lighting. Much like fluorescent lights, modern LED lights are a wonderful solution for gymnasiums, warehouses, schools, and commercial buildings.
They are also adaptable for large public areas (which require powerful, efficient lights over a large area), road lighting (which offer significant color advantages over low and high pressure sodium lights), and parking lots. For an interesting take on the history of street lighting in the United States readhere.
different methods of producing light. Fluorescent bulbs contain inert gas within the glass casing while LEDs are a solid state technology. Fluorescent lights produce UV radiation and then convert it into visible light through the use of a phosphor coating inside the bulb. LEDs emit electromagnetic radiation across a small portion of the visible light spectrum and don’t waste energy by producing waste heat or non-visible electromagnetic radiation (such as UV). There is such a thing as an IRED (infrared emitting diode) which is specifically designed to emit infrared energy.
In the last few yearsLED efficiency has surpassed that of fluorescent lights and its efficiency improvements are progressing at a much more rapid rate. Further, fluorescent lamps require the use of a ballast to stabilize the internal current that produces light. When the ballast has a minor imperfection or is damaged, the light can produce an audible buzzing noise. Other shortcomings include the following:
Fluorescent lights are non-directional, meaning that they emit light for 360 degrees. As you might expect, a large portion of this light is wasted (for example, that portion that is directed at the ceiling).
As good as fluorescent light efficiency has become, LED is better (and continues to improve at a more rapid pace). As long as fluorescent lights last, LED lights last much longer. Further, fluorescentlamps require the use of a ballast to stabilize the internal current that produces light. When the ballast
has a minor imperfection or is damaged, the light can produce an audible buzzing noise. Other shortcomings include waste disposal issues (due to CFL"s reliance on mercury), and non-directional light generation. Non-directional light generation is a bigger deal than you might think. For example, light that is being directed at the ceiling rather than the room is wasted light. Therefore, CFL (as well as the related standard fluorescent bulbs) might have good “source efficiency” (i.e. it looks good on paper), but will fall short of LED when it comes to the more important measure: “system efficiency” (actual efficiency in real world applications).
Fluorescent light is available in a range of CCT values that can be adjusted by changing the amount of phosphor inside the bulb. Typical values range between warm white at 2700K to daylight at 6500K depending on the lighting requirement.
CRI for LED is highly dependent on the particular light in question. That said, a very broad spectrum of CRI values is available ranging generally from 65-95.
Typical CRI values for fluorescent light are between 62 and 80. This is fairly good color rendering but it leaves room for improvement when compared to LED.
LEDs are an ideal light for purposely turning on and off because they respond rather instantaneously (there is no warm up or cool down period). They produce steady light without flicker.
Fluorescent lights exhibit a short delay when turning on. Older fluorescent models actually required a significant warm up period before the tube would light but this has been improved with newer, rapid-start fluorescent lights. Possible failures or delays in the start-up process are typically due to faulty starters, transformers, or ballast. Fluorescent bulbs may also flicker, display swirling or pink light, light at the ends of the tube only, or cycle on and off as the bulb reaches the end of its useful life.
LEDs are very easy to dim and options are available to use anywhere from 100% of the light to 0.5%. LED dimming functions by either lowering the forward current or modulating the pulse duration.
Newer CFL bulbs can be dimmed very effectively (down to about 15% of their normal light) while older fluorescent bulbs are often not suitable for dimming. If looking to dim a fluorescent bulb, make sure that you choose a ballast that is rated for dimming.
LEDs emit light for 180 degrees. This is typically an advantage because light is usually desired over a target area (rather than all 360 degrees around the bulb). You can read more about the impact of directional lighting by learning about a measurement called “useful lumens” or “system efficiency.”
LEDs are very efficient relative to every lighting type on the market. Typical source efficiency ranges 37 and 120 lumens/watt. Where LEDs really shine, however, is in their system efficiency (the amount of light that actually reaches the target area after all losses are accounted for). Most values for LED system efficiency fall above 50 lumens/watt.
Fluorescent and CFL lights are very efficient compared to incandescent lights (50-100 lumens/watt source efficiency). They lose out to LEDs principally because their system efficiency is much lower (<30 lumens/watt) due to all of the losses associated with omnidirectional light output and the need to redirect it to a desired area.
LED efficiency drops as current increases. Heat output also increases with additional current which decreases the lifetime of the device. The overall performance drop is relatively low, however, when compared to fluorescent lights.
Fluorescent lights also experience efficiency losses as the device ages and additional current is required to achieve the same lighting output. Efficiency losses are greater and the degradation time shorter in the case of fluorescent bulbs.
LEDs produce a very narrow spectrum of visible light without the losses to irrelevant radiation types (IR or UV) associated with conventional lighting, meaning that most of the energy consumed by the light source is converted directly to visible light.
Fluorescent lights actually produce primarily UV radiation. They generate visible light because the bulb is coated with a layer of phosphor which glows when it comes into contact with UV radiation. Roughly 15% of the emissions are lost due to energy dissipation and heat.
Fluorescent lights produce primarily UV radiation. They generate visible light because the bulb is coated with a layer of phosphor which glows when it comes into contact with UV radiation. Although most UV radiation stays within the bulb, some does escape into the environment which can potentially be a hazard.
Fluorescent lights can fail in a number of different ways. Generally they exhibit an end-of-life phenomenon known as cycling where the lamp goes on and off without human input prior to eventually failing entirely.
Foot candle is a measure that describes the amount of light reaching a specified surface area as opposed to the total amount of light coming from a source (luminous flux).
LEDs are very efficient relative to every lighting type on the market. Typical source efficiency ranges 37 and 120 lumens/watt. Where LEDs really shine, however, is in their system efficiency (the amount of light that actually reaches the target area after all losses are accounted for). Most values for LED system efficiency fall above 50 lumens/watt.
Fluorescent and CFL lights are very efficient compared to incandescent lights (50-100 lumens/watt source efficiency). They lose out to LEDs principally because their system efficiency is much lower (<30 lumens/watt) due to all of the losses associated with omnidirectional light output and the need to redirect it to a desired area.
Fluorescent lights emit heat that is absorbed by the ballast and/or lost to the environment. Roughly 15% of the emissions are lost due to energy dissipation and heat losses. In some circumstances heat emissions could be beneficial, however, it is generally a bad thing to emit heat as it represents an energy inefficiency. The ultimate purpose of the device is to emit light, not heat.
LEDs last longer than any light source commercially available on the market. Lifespans are variable but typical values range from 25,000 hours to 200,000 hours or more before a lamp or fixture requires replacement.
Fluorescent lights have good lifespan relative to some bulbs but not compared to LED. Typical lifespan values range from 7,000 hours to 15,000 hours before a bulb requires replacement. Note: sometimes fluorescent lights need to be changed out before the end of their useful life to preempt serious degradation effects like flicker or changing light color (turning pink).
Fluorescent lights are relatively cheap to purchase but relatively expensive to maintain. Fluorescent bulbs will likely need to be purchased several times and the associated labor costs will need to be paid in order to attain the equivalent lifespan of a single LED light.
Fluorescent bulbs are particularly fragile - especially T5, T8, and T12 tubes. Perhaps more importantly, broken fluorescent bulbs require special handling and disposal due to hazardous materials like mercury inside the lights.
Compact fluorescent lights (CFLs) are designed to be small (such that they can replace an incandescent household light). Even so, they typically aren’t produced below roughly a centimeter in width. Standard fluorescent tubes are bulky and fragile at the same time. Neither compare to the small size and robust build of a solid state light like LED.
Fluorescent lights with regular magnetic ballasts (such as the T12 tube) are not generally recommended for temperatures below 50-60 Degrees Fahrenheit. For colder weather choose a fluorescent light with an electronic ballast such as a T8 tube.
LEDs produce significantly less heat than conventional gas discharge lights.This is typically a positive, however, for the unique case of application with traffic lights, there is a small potential that snow can accumulate on the bulbs. In reality, however, this is generally not an issue due to the use of visors and/or proper orientation of the light within a fixture that shields it from the elements.
Fluorescent bulbs are not generally recommended for outdoor lighting. CFLs will work but as the temperature drops the light quality suffers significantly. This is noticeable slightly below the freezing level and dramatic below about 5 degrees Fahrenheit.
To evaluate the performance of display devices, several metrics are commonly used, such as response time, CR, color gamut, panel flexibility, viewing angle, resolution density, peak brightness, lifetime, among others. Here we compare LCD and OLED devices based on these metrics one by one.
A fast response time helps to mitigate motion image blur and boost the optical efficiency, but this statement is only qualitatively correct. When quantifying the visual performance of a moving object, motion picture response time (MPRT) is more representative, and the following equation should be used
From Figure 5, we can gain several important physical insights: (1) Increasing the frame rate is a simple approach to suppress image motion blur, but its improvement gradually saturates. For example, if the LC response time is 10 ms, then increasing the frame rate from 30 to 60 fps would significantly reduce the MPRT. However, as the TFT frame rate continues to increase to 120 and 240 fps, then the improvement gradually saturates. (2) At a given frame rate, say 120 fps, as the LC response time decreases, the MPRT decreases almost linearly and then saturates. This means that the MPRT is mainly determined by the TFT frame rate once the LC response time is fast enough, i.e., τ≪Tf. Under such conditions, Equation (1) is reduced to MPRT≈0.8Tf. (3) When the LC response is <2 ms, its MPRT is comparable to that of an OLED at the same frame rate, e.g., 120 fps. Here we assume the OLED’s response time is 0.
The last finding is somehow counter to the intuition that a LCD should have a more severe motion picture image blur, as its response time is approximately 1000 × slower than that of an OLED (ms vs. μs). To validate this prediction, Chen et al.
If we want to further suppress image blur to an unnoticeable level (MPRT<2 ms), decreasing the duty ratio (for LCDs, this is the on-time ratio of the backlight, called scanning backlight or blinking backlight) is mostly adopted
As Figure 6 depicts, there are two types of surface reflections. The first one is from a direct light source, i.e., the sun or a light bulb, denoted as A1. Its reflection is fairly specular, and in practice, we can avoid this reflection (i.e., strong glare from direct sun) by simply adjusting the display position or viewing direction. However, the second reflection, denoted as A2, is quite difficult to avoid. It comes from an extended background light source, such as a clear sky or scattered ceiling light. In our analysis, we mainly focus on the second reflection (A2).
To investigate the ACR, we have to clarify the reflectance first. A large TV is often operated by remote control, so touchscreen functionality is not required. As a result, an anti-reflection coating is commonly adopted. Let us assume that the reflectance is 1.2% for both LCD and OLED TVs. For the peak brightness and CR, different TV makers have their own specifications. Here, without losing generality, let us use the following brands as examples for comparison: LCD peak brightness=1200 nits, LCD CR=5000:1 (Sony 75″ X940E LCD TV); OLED peak brightness=600 nits, and OLED CR=infinity (Sony 77″ A1E OLED TV). The obtained ACR for both LCD and OLED TVs is plotted in Figure 7a. As expected, OLEDs have a much higher ACR in the low illuminance region (dark room) but drop sharply as ambient light gets brighter. At 63 lux, OLEDs have the same ACR as LCDs. Beyond 63 lux, LCDs take over. In many countries, 60 lux is the typical lighting condition in a family living room. This implies that LCDs have a higher ACR when the ambient light is brighter than 60 lux, such as in office lighting (320–500 lux) and a living room with the window shades or curtain open. Please note that, in our simulation, we used the real peak brightness of LCDs (1200 nits) and OLEDs (600 nits). In most cases, the displayed contents could vary from black to white. If we consider a typical 50% average picture level (i.e., 600 nits for LCDs vs. 300 nits for OLEDs), then the crossover point drops to 31 lux (not shown here), and LCDs are even more favorable. This is because the on-state brightness plays an important role to the ACR, as Equation (2) shows.
Calculated ACR as a function of different ambient light conditions for LCD and OLED TVs. Here we assume that the LCD peak brightness is 1200 nits and OLED peak brightness is 600 nits, with a surface reflectance of 1.2% for both the LCD and OLED. (a) LCD CR: 5000:1, OLED CR: infinity; (b) LCD CR: 20 000:1, OLED CR: infinity.
Recently, an LCD panel with an in-cell polarizer was proposed to decouple the depolarization effect of the LC layer and color filtersFigure 7b. Now, the crossover point takes place at 16 lux, which continues to favor LCDs.
For mobile displays, such as smartphones, touch functionality is required. Thus the outer surface is often subject to fingerprints, grease and other contaminants. Therefore, only a simple grade AR coating is used, and the total surface reflectance amounts to ~4.4%. Let us use the FFS LCD as an example for comparison with an OLED. The following parameters are used in our simulations: the LCD peak brightness is 600 nits and CR is 2000:1, while the OLED peak brightness is 500 nits and CR is infinity. Figure 8a depicts the calculated results, where the intersection occurs at 107 lux, which corresponds to a very dark overcast day. If the newly proposed structure with an in-cell polarizer is used, the FFS LCD could attain a 3000:1 CRFigure 8b), corresponding to an office building hallway or restroom lighting. For reference, a typical office light is in the range of 320–500 luxFigure 8 depicts, OLEDs have a superior ACR under dark ambient conditions, but this advantage gradually diminishes as the ambient light increases. This was indeed experimentally confirmed by LG Display
Calculated ACR as a function of different ambient light conditions for LCD and OLED smartphones. Reflectance is assumed to be 4.4% for both LCD and OLED. (a) LCD CR: 2000:1, OLED CR: infinity; (b) LCD CR: 3000:1, OLED CR: infinity. (LCD peak brightness: 600 nits; OLED peak brightness: 500 nits).
For conventional LCDs employing a WLED backlight, the yellow spectrum generated by YAG (yttrium aluminum garnet) phosphor is too broad to become highly saturated RGB primary colors, as shown in Figure 9aTable 2. The first choice is the RG-phosphor-converted WLEDFigure 9b, the red and green emission spectra are well separated; still, the green spectrum (generated by β-sialon:Eu2+ phosphor) is fairly broad and red spectrum (generated by K2SiF6:Mn4+ (potassium silicofluoride, KSF) phosphor) is not deep enough, leading to 70%–80% Rec. 2020, depending on the color filters used.
Transmission spectra of color filters and emission spectra of (a) YAG WLED, (b) KSF WLED, (c) QDEF and (d) Vivid Color LED. KSF, potassium silicofluoride; QDEF, quantum dot enhancement film; WLED, white light-emitting diode; YAG, yttrium aluminum garnet.
A QD-enhanced backlight (e.g., quantum dot enhancement film, QDEF) offers another option for a wide color gamutFigure 9c), so that high purity RGB colors can be realized and a color gamut of ~90% Rec. 2020 can be achieved. One safety concern is that some high-performance QDs contain the heavy metal Cd. To be compatible with the restriction of hazardous substances, the maximum cadmium content should be under 100 ppm in any consumer electronic product
Recently, a new LED technology, called the Vivid Color LED, was demonstratedFigure 9d), which leads to an unprecedented color gamut (~98% Rec. 2020) together with specially designed color filters. Such a color gamut is comparable to that of laser-lit displays but without laser speckles. Moreover, the Vivid Color LED is heavy-metal free and shows good thermal stability. If the efficiency and cost can be further improved, it would be a perfect candidate for an LCD backlight.
A color filter array is another effective approach to enhance the color gamut of an OLED. For example, in 2017, AUO demonstrated a 5-inch top-emission OLED panel with 95% Rec. 2020. In this design, so-called symmetric panel stacking with a color filter is employed to generate purer RGB primary colors
As mentioned earlier, TFT LCDs are a fairly mature technology. They can be operated for >10 years without noticeable performance degradation. However, OLEDs are more sensitive to moisture and oxygen than LCDs. Thus their lifetime, especially for blue OLEDs, is still an issue. For mobile displays, this is not a critical issue because the expected usage of a smartphone is approximately 2–3 years. However, for large TVs, a lifetime of >30 000 h (>10 years) has become the normal expectation for consumers.
Here we focus on two types of lifetime: storage and operational. To enable a 10-year storage lifetime, according to the analysis−6 g (m2-day)−1 and 1 × 10−5 cm3 (m2-day)−1, respectively. To achieve these values, organic and/or inorganic thin films have been developed to effectively protect the OLED and lengthen its storage lifetime. Meanwhile, it is compatible to flexible substrates and favors a thinner display profile
The next type of lifetime is operational lifetime. Owing to material degradation, OLED luminance will decrease and voltage will increase after long-term drivingT50) can be as long as >80 000 h with a 1000 cd m−2 luminanceT50, half lifetime) with an initial luminance of 1000 nits. However, this is still ~20 × shorter than that of red and green phosphorescent OLEDs
To further enhance the lifetime of the blue OLED, the NTU group has developed new ETL and TTF-EML materials together with an optimized layer structure and double EML structureFigure 10a shows the luminance decay curves of such a blue OLED under different initial luminance values (5000, 10 000, and 15 000 nits). From Figure 10b, the estimated T50 at 1000 nits of this blue OLED is ~56 000 h (~6–7 years)
Power consumption is equally important as other metrics. For LCDs, power consumption consists of two parts: the backlight and driving electronics. The ratio between these two depends on the display size and resolution density. For a 55″ 4K LCD TV, the backlight occupies approximately 90% of the total power consumption. To make full use of the backlight, a dual brightness enhancement film is commonly embedded to recycle mismatched polarized light
The power efficiency of an OLED is generally limited by the extraction efficiency (ηext~20%). To improve the power efficiency, multiple approaches can be used, such as a microlens array, a corrugated structure with a high refractive index substrateFigure 11 shows the power efficiencies of white, green, red and blue phosphorescent as well as blue fluorescent/TTF OLEDs over time. For OLEDs with fluorescent emitters in the 1980s and 1990s, the power efficiency was limited by the IQE, typically <10 lm W−1(Refs. 41, 114, 115, 116, 117, 118). With the incorporation of phosphorescent emitters in the ~2000 s, the power efficiency was significantly improved owing to the materials and device engineering−1 was demonstrated in 2011 (Ref. 127), which showed a >100 × improvement compared with that of the basic two-layer device proposed in 1987 (1.5 lm W−1 in Ref. 41). A white OLED with a power efficiency >100 lm W−1 was also demonstrated, which was comparable to the power efficiency of a LCD backlight. For red and blue OLEDs, their power efficiencies are generally lower than that of the green OLED due to their lower photopic sensitivity function, and there is a tradeoff between color saturation and power efficiency. Note, we separated the performances of blue phosphorescent and fluorescent/TTF OLEDs. For the blue phosphorescent OLEDs, although the power efficiency can be as high as ~80 lm W−1, the operation lifetime is short and color is sky-blue. For display applications, the blue TTF OLED is the favored choice, with an acceptable lifetime and color but a much lower power efficiency (16 lm W−1) than its phosphorescent counterpartFigure 11 shows.
Power efficiency of white, red, green and phosphorescent blue and fluorescent/TTF blue OLEDs over time. Data are compiled from Refs. 41, 45, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133.
To compare the power consumption of LCDs and OLEDs with the same resolution density, the displayed contents should be considered as well. In general, OLEDs are more efficient than LCDs for displaying dark images because black pixels consume little power for an emissive display, while LCDs are more efficient than OLEDs at displaying bright images. Currently, a ~65% average picture level is the intersection point between RGB OLEDs and LCDs
In addition to the aforementioned six display metrics, other parameters are equally important. For example, high-resolution density has become a standard for all high-end display devices. Currently, LCD is taking the lead in consumer electronic products. Eight-hundred ppi or even >1000 ppi LCDs have already been demonstrated and commercialized, such as in the Sony 5.5″ 4k Smartphone Xperia Z5 Premium. The resolution of RGB OLEDs is limited by the physical dimension of the fine-pitch shadow mask. To compete with LCDs, most OLED displays use the PenTile RGB subpixel matrix scheme
The viewing angle is another important property that defines the viewing experience at large oblique angles, which is quite critical for multi-viewer applications. OLEDs are self-emissive and have an angular distribution that is much broader than that of LCDs. For instance, at a 30° viewing angle, the OLED brightness only decreases by 30%, whereas the LCD brightness decrease exceeds 50%. To widen an LCD’s viewing angle, three options can be used. (1) Remove the brightness-enhancement film in the backlight system. The tradeoff is decreased on-axis brightness
In addition to brightness, color, grayscale and the CR also vary with the viewing angle, known as color shift and gamma shift. In these aspects, LCDs and OLEDs have different mechanisms. For LCDs, they are induced by the anisotropic property of the LC material, which could be compensated for with uniaxial or biaxial films
Cost is another key factor for consumers. LCDs have been the topic of extensive investigation and investment, whereas OLED technology is emerging and its fabrication yield and capability are still far behind LCDs. As a result, the price of OLEDs is about twice as high as that of LCDs, especially for large displays. As more investment is made in OLEDs and more advanced fabrication technology is developed, such as ink-jet printing
Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directlybacklight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.
LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens have replaced heavy, bulky and less energy-efficient cathode-ray tube (CRT) displays in nearly all applications. The phosphors used in CRTs make them vulnerable to image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs do not have this weakness, but are still susceptible to image persistence.
Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, often made of Indium-Tin oxide (ITO) and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.
The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented.Sharp Corporation. The patent that covered that specific mixture expired.
Most color LCD systems use the same technique, with color filters used to generate red, green, and blue subpixels. The LCD color filters are made with a photolithography process on large glass sheets that are later glued with other glass sheets containing a TFT array, spacers and liquid crystal, creating several color LCDs that are then cut from one another and laminated with polarizer sheets. Red, green, blue and black photoresists (resists) are used. All resists contain a finely ground powdered pigment, with particles being just 40 nanometers across. The black resist is the first to be applied; this will create a black grid (known in the industry as a black matrix) that will separate red, green and blue subpixels from one another, increasing contrast ratios and preventing light from leaking from one subpixel onto other surrounding subpixels.Super-twisted nematic LCD, where the variable twist between tighter-spaced plates causes a varying double refraction birefringence, thus changing the hue.
LCD in a Texas Instruments calculator with top polarizer removed from device and placed on top, such that the top and bottom polarizers are perpendicular. As a result, the colors are inverted.
The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of 2010-era LCDs are used in television sets, monitors and smartphones, they have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background. When no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, particularly in smartphones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).
Displays for a small number of individual digits or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment.alphanumeric or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see passive-matrix and active-matrix addressed LCDs.
LCDs are manufactured in cleanrooms borrowing techniques from semiconductor manufacturing and using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:
Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50 and 58 inch LCDs to be made per mother glass, specially 58 inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.AGC Inc., Corning Inc., and Nippon Electric Glass.
The origins and the complex history of liquid-crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.IEEE History Center.Peter J. Wild, can be found at the Engineering and Technology History Wiki.
In 1888,Friedrich Reinitzer (1858–1927) discovered the liquid crystalline nature of cholesterol extracted from carrots (that is, two melting points and generation of colors) and published his findings at a meeting of the Vienna Chemical Society on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss des Cholesterins, Monatshefte für Chemie (Wien) 9, 421–441 (1888)).Otto Lehmann published his work "Flüssige Kristalle" (Liquid Crystals). In 1911, Charles Mauguin first experimented with liquid crystals confined between plates in thin layers.
In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.
In 1964, George H. Heilmeier, then working at the RCA laboratories on the effect discovered by Williams achieved the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier continue to work on scattering effects in liquid crystals and finally the achievement of the first operational liquid-crystal display based on what he called the George H. Heilmeier was inducted in the National Inventors Hall of FameIEEE Milestone.
In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern, England. The team at RRE supported ongoing work by George William Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals, which had correct stability and temperature properties for application in LCDs.
The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968.dynamic scattering mode (DSM) LCD that used standard discrete MOSFETs.
On December 4, 1970, the twisted nematic field effect (TN) in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.Brown, Boveri & Cie, its joint venture partner at that time, which produced TN displays for wristwatches and other applications during the 1970s for the international markets including the Japanese electronics industry, which soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. James Fergason, while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute, filed an identical patent in the United States on April 22, 1971.ILIXCO (now LXD Incorporated), produced LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption. Tetsuro Hama and Izuhiko Nishimura of Seiko received a US patent dated February 1971, for an electronic wristwatch incorporating a TN-LCD.
In 1972, the concept of the active-matrix thin-film transistor (TFT) liquid-crystal display panel was prototyped in the United States by T. Peter Brody"s team at Westinghouse, in Pittsburgh, Pennsylvania.Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display (TFT LCD).high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.active-matrix liquid-crystal display (AM LCD) in 1974, and then Brody coined the term "active matrix" in 1975.
In 1972 North American Rockwell Microelectronics Corp introduced the use of DSM LCDs for calculators for marketing by Lloyds Electronics Inc, though these required an internal light source for illumination.Sharp Corporation followed with DSM LCDs for pocket-sized calculators in 1973Seiko and its first 6-digit TN-LCD quartz wristwatch, and Casio"s "Casiotron". Color LCDs based on Guest-Host interaction were invented by a team at RCA in 1968.TFT LCDs similar to the prototypes developed by a Westinghouse team in 1972 were patented in 1976 by a team at Sharp consisting of Fumiaki Funada, Masataka Matsuura, and Tomio Wada,
In 1983, researchers at Brown, Boveri & Cie (BBC) Research Center, Switzerland, invented the passive matrix-addressed LCDs. H. Amstutz et al. were listed as inventors in the corresponding patent applications filed in Switzerland on July 7, 1983, and October 28, 1983. Patents were granted in Switzerland CH 665491, Europe EP 0131216,
The first color LCD televisions were developed as handheld televisions in Japan. In 1980, Hattori Seiko"s R&D group began development on color LCD pocket televisions.Seiko Epson released the first LCD television, the Epson TV Watch, a wristwatch equipped with a small active-matrix LCD television.dot matrix TN-LCD in 1983.Citizen Watch,TFT LCD.computer monitors and LCD televisions.3LCD projection technology in the 1980s, and licensed it for use in projectors in 1988.compact, full-color LCD projector.
In 1990, under different titles, inventors conceived electro optical effects as alternatives to twisted nematic field effect LCDs (TN- and STN- LCDs). One approach was to use interdigital electrodes on one glass substrate only to produce an electric field essentially parallel to the glass substrates.Germany by Guenter Baur et al. and patented in various countries.Hitachi work out various practical details of the IPS technology to interconnect the thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.
Hitachi also improved the viewing angle dependence further by optimizing the shape of the electrodes (Super IPS). NEC and Hitachi become early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and In Plane Switching subsequently remain the dominant LCD designs through 2006.South Korea and Taiwan,
In 2007 the image quality of LCD televisions surpassed the image quality of cathode-ray-tube-based (CRT) TVs.LCD TVs were projected to account 50% of the 200 million TVs to be shipped globally in 2006, according to Displaybank.Toshiba announced 2560 × 1600 pixels on a 6.1-inch (155 mm) LCD panel, suitable for use in a tablet computer,
In 2016, Panasonic developed IPS LCDs with a contrast ratio of 1,000,000:1, rivaling OLEDs. This technology was later put into mass production as dual layer, dual panel or LMCL (Light Modulating Cell Layer) LCDs. The technology uses 2 liquid crystal layers instead of one, and may be used along with a mini-LED backlight and quantum dot sheets.
Since LCDs produce no light of their own, they require external light to produce a visible image.backlight. Active-matrix LCDs are almost always backlit.Transflective LCDs combine the features of a backlit transmissive display and a reflective display.
CCFL: The LCD panel is lit either by two cold cathode fluorescent lamps placed at opposite edges of the display or an array of parallel CCFLs behind larger displays. A diffuser (made of PMMA acrylic plastic, also known as a wave or light guide/guiding plateinverter to convert whatever DC voltage the device uses (usually 5 or 12 V) to ≈1000 V needed to light a CCFL.
EL-WLED: The LCD panel is lit by a row of white LEDs placed at one or more edges of the screen. A light diffuser (light guide plate, LGP) is then used to spread the light evenly across the whole display, similarly to edge-lit CCFL LCD backlights. The diffuser is made out of either PMMA plastic or special glass, PMMA is used in most cases because it is rugged, while special glass is used when the thickness of the LCD is of primary concern, because it doesn"t expand as much when heated or exposed to moisture, which allows LCDs to be just 5mm thick. Quantum dots may be placed on top of the diffuser as a quantum dot enhancement film (QDEF, in which case they need a layer to be protected from heat and humidity) or on the color filter of the LCD, replacing the resists that are normally used.
WLED array: The LCD panel is lit by a full array of white LEDs placed behind a diffuser behind the panel. LCDs that use this implementation will usually have the ability to dim or completely turn off the LEDs in the dark areas of the image being displayed, effectively increasing the contrast ratio of the display. The precision with which this can be done will depend on the number of dimming zones of the display. The more dimming zones, the more precise the dimming, with less obvious blooming artifacts which are visible as dark grey patches surrounded by the unlit areas of the LCD. As of 2012, this design gets most of its use from upscale, larger-screen LCD televisions.
RGB-LED array: Similar to the WLED array, except the panel is lit by a full array of RGB LEDs. While displays lit with white LEDs usually have a poorer color gamut than CCFL lit displays, panels lit with RGB LEDs have very wide color gamuts. This implementation is most popular on professional graphics editing LCDs. As of 2012, LCDs in this category usually cost more than $1000. As of 2016 the cost of this category has drastically reduced and such LCD televisions obtained same price levels as the former 28" (71 cm) CRT based categories.
Monochrome LEDs: such as red, green, yellow or blue LEDs are used in the small passive monochrome LCDs typically used in clocks, watches and small appliances.
Mini-LED: Backlighting with Mini-LEDs can support over a thousand of Full-area Local Area Dimming (FLAD) zones. This allows deeper blacks and higher contrast ratio.
Today, most LCD screens are being designed with an LED backlight instead of the traditional CCFL backlight, while that backlight is dynamically controlled with the video information (dynamic backlight control). The combination with the dynamic backlight control, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan, simultaneously increases the dynamic range of the display system (also marketed as HDR, high dynamic range television or FLAD, full-area local area dimming).
The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure (prism sheet) to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD (invented by Philips researchers Adrianus de Vaan and Paulus Schaareman),
A pink elastomeric connector mating an LCD panel to circuit board traces, shown next to a centimeter-scale ruler. The conductive and insulating layers in the black stripe are very small.
A standard television receiver screen, a modern LCD panel, has over six million pixels, and they are all individually powered by a wire network embedded in the screen. The fine wires, or pathways, form a grid with vertical wires across the whole screen on one side of the screen and horizontal wires across the whole screen on the other side of the screen. To this grid each pixel has a positive connection on one side and a negative connection on the other side. So the total amount of wires needed for a 1080p display is 3 x 1920 going vertically and 1080 going horizontally for a total of 6840 wires horizontally and vertically. That"s three for red, green and blue and 1920 columns of pixels for each color for a total of 5760 wires going vertically and 1080 rows of wires going horizontally. For a panel that is 28.8 inches (73 centimeters) wide, that means a wire density of 200 wires per inch along the horizontal edge.
The LCD panel is powered by LCD drivers that are carefully matched up with the edge of the LCD panel at the factory level. The drivers may be installed using several methods, the most common of which