does lcd screen harm eyes factory
47% of U.S. consumers admitted to being unable to last a day without their mobile devices in a 2014 study done by the Bank of America, demonstrating the increasing prevalence of mobile devices. Mobile devices use LCD screens which emit blue light and thus negatively affects not only vision but also overall health. Continual extended screen time mainly can impact your eyes in two major ways.
Digital Eye StrainWhen we look at a screen, our blink rate drops significantly, thus causing digital eye strain. Signs of digital eye strain include slightly blurry vision after using LCD screens for prolonged periods, headaches, dry or tired eyes.
Though digital eye strain is temporary, if left unaddressed, it can turn into a chronic problem.The easiest way to address digital eye strain is to blink more as blinking helps to keep eyes lubricated. Alternatively, try using the “20-20-20 Rule”. Every 20 minutes, stare at something at least 20 feet away for at least 20 seconds. This exercise engages your distance vision and allows the eyes to rest.
Blue Light ExposureBlue light is the highest energy wavelength of visible light. This energy is able to penetrate all the way to the back of the eye, through the eyes’ natural filters. The rapidly increasing amount of blue light exposure that we get each day through digital device use is causing permanent damage to our eyes. The effects of blue light are cumulative and can lead to eye diseases like macular degeneration.
Children are especially at risk due to their developing eyes. Protective pigments which help filter out some of this harmful blue light are not yet present. The risk is worsened further due to their increased exposure to LCD screens.
Try minimising usage of LCD screens by reading print media or using E Ink displays instead. The InkCase, for example, allows users to read for prolonged periods with minimal power consumption by adding a secondary E Ink screen on the back of your phone.
Continuous usage of LCD screens can impact your eyes in few bad ways, that’s why LCD screens are bad for your eyes. For instance, long hours of usage of these screens can cause digital eye strains or the blink rate of your eyes to drop a little. Your eyes can start feeling tired and some sort of blurry vision.
Although, these problems are temporary often, and only get worse in few cases (who doesn’t care for their eyes while using an LCD screen). If you keep blinking the eyes during LCD screen usage, it’ll surely help in keeping them relaxed.
LCD screens (mostly) contains florescent cathode (cold) backlight display, other screen type LED however uses the emitting diodes that are light and are safer over the eyes. Plus, the cathode rays of LCD can be harder on your eyes. So, it is not that safe for the eyes as the other type is.
Experts say that screens like a computer, phone, tablet screens are not that much harmful over the eyes as we think. They can cause temporary damage like blurred vision (for a short time), tiring eyes, redness, etc. that can be resolved with time. But in only a few cases it gets worse but still can be treated.
Although both screen types have their significant pros and cons. But in the case of the eye’s OLED screen is considered a better option. Because they provide better viewing angles, resolution powers, better contrasts, etc. in comparison to the LCD screens.
Discoveries by scientists suggest that LCD screens leak few chemicals almost in every surrounding (environment). And these particles (chemicals) get toxic with time. Also, the breakdown of these chemicals is not easy and takes time, this increase causes a high mobility rate in the environment.are led screens bad for your eyes
see the light flickering at a very high frequency, thestroboscopicdoes exist. If thestroboscopicfrequency is very low, it can be easily observed by human eyes.
If a growing body of scientific evidence is to be believed, the LCD screen may be one your health"s worst enemies, capable of causing eye strain, headaches, and sleepless nights.
If you think about it, this makes perfect sense. Through the vast majority of human existence, our species wasn"t staring at LCD screens for hours on end. In a nutshell, our bodies and brains simply weren"t built to handle it. The problem: Many researchers now believe that when you stare at a bright screen, it effectively tricks your body into thinking it"s daytime, making it more difficult to sleep, and resulting in a host of other problems. To make matters worse: Pretty much all of us are regularly looking at their phones, tablets, and computers in bed, when we should be preparing to hunker down for the night.
One company that"s trying to do something about this issue: Gunnar Optiks, makers of so-called "computer eyewear" that"s designed to mitigate the effects of staring at a screen. When Gunnar first launched a few years back, I was a skeptic of their claims. But in the years since, I"ve become more interested in the topic, spoken to more scientists, and now genuinely feel that they are onto something. To delve deep into the science, I spoke with Gunnar Optiks CTO and co-founder Joe Croft about the science of screens, and what his company is doing about them—short of making you give up all your gadgets for good. (Warning, technical talk ahead!)
There is a lot of new research about the effects of LCD lights on melatonin production and its effects on sleep. A lot of people also use computers, tablets, and phones at night or even in bed. Do you view this as a greater offender to health than staring at a computer during the day?
Why focus efforts on glasses? Do you see a time in which companies such as yours would expand into building filters into computer screens that would accomplish the same end result, but perhaps be more adjustable/tunable depending on your particular needs?Glasses are the only method that serves as a complete solution to Computer Vision Syndrome. A computer screen filter would help with a few issues, but not all. The main issues are the following.
2. Near Point Stress Syndrome. Eye muscles have to stay in a continual state of flexion to focus on computer screens. Glasses can relieve the eye strain by taking some of the focusing load.
3. Quality of Light. Screen filters can help here, but glasses are more effective because they work for not only screen light, but for overhead office lighting as well. Overhead flourescent lights are notorious for creating eye strain. High in HEV, very spiky in terms of spectral transmission. The furthest thing from natural full spectrum light that our visual system is designed to see.
4. Glare/Visual Noise. Screen protectors can help here as well. With proper computer eyewear, however you can eliminate reflections that plague many prescription eyewear wearers. They see the reflection off their cornea on the back side of their glasses. Gunnar eyewear specifically targets all types of glare and reflections.
Have there been any challenges in getting the medical community to accept computer glasses as a category?Within the optical community it has been easy. Eye doctors understand all the principles well and it doesn"t take much explaining. Why they don"t like is the over the counter approach. They much prefer to participate in our custom prescription program.
If you want to show these things help one’s health, how do you test that? If you’re seeing noticeable improvements, how long does it usually take for them to show in users?The first step is to establish a baseline. In our study from 2009 we had all the test subjects (over 100) undergo a CVS (Computer Vision Syndrome) symptom evaluation. This became the baseline for whether we saw an increase, decrease, or no-change with the use of Gunnars. After the multi-week study they underwent the same CVS symptom evaluation and for each symptom (ie headache, dry eye, external eyestrain, internal eyestrain, etc etc) we measured the difference. The results were overwhelmingly positive. Our current study is looking at the increases in productivity due to wearing Gunnars. Most wearers notice a difference right when the put them on, but after a multiweek trial, they are hooked.
Since LCD screens likely suppress melatonin, and keep you awake, would it make sense that in situations when you want to stay more alert, that you’d actually want unfiltered exposure to LCD lights?Sure. Same way that taking a No-Doz every once in a while can help you out. Take enough No-Doz on a continual basis and you"re sure to have problems, though! Seriously, though, it"s good to see that there are positive effects of photo therapy. Especially for people in northern geographical locations, it can be very beneficial. The trick is using it in the proper manner and syncing it to your circadian rhythms.
Some research suggests that the melatonin-suppressing effects of LCD light are somewhat specific to blue (and white light lights that contain blue wavelengths), and are not caused by red or orange lights. Do your glasses specifically focus on these offending wavelengths? Any info on how they filter for them?Yes. We have 35% transmission at 450 nm (blue light) and close to 97% once you get into the warmer part of the spectrum.
“I’ve changed to a high-end smartphone with an OLED screen, but my eyes feel uncomfortable.” More and more netizens have this problem. Do OLED screens really hurt our eyes? Recently, a reporter investigated this phenomenon.
“I would never have thought that my eyes were becoming uncomfortable after using a new mobile phone for a few days.” Recently, a netizen reported this issue.
According to the reporter’s investigation, quite a few users have such questions. There are nearly 400,000 related links in Google search for “Eyes hurt by OLED screens“. Many related posts have resonated with netizens because they also had this symptom.
In the past two years, OLED screen smartphones have become the mainstream, and major smartphone manufacturers in the market are applying OLED screens in their flagship models one after another.
The problem is, do OLED screens really hurt our eyes? The reason why you feel uncomfortable when using mobile phones with OLED screens is that they flicker.
LCD screen usually uses LCD backlight to realize screen luminescence, the flickering frequency of which can reach several kilohertz (Hz) that flickering will basically not occur. The pixels for OLED screens are self-luminous, the low power of which has limited its flickering frequency. At present, the flickering frequency of the PWM dimming of OLED screens on many mobile phones is about 215Hz-250Hz.
In the eyes of communication industry professionals, this value is not high. But even the medical circle has not given a clear answer to this question, which is a great controversy in the industry.
Jie Chuanhong is the director of the ophthalmology department of the Eye Hospital of China Academy of Chinese Medical Sciences. He said in an interview that whether you watch the mobile phone screen, computer screen, or iPad screen for a long time, it is easy to cause visual fatigue, which should not be directly related to the screen.
“There is no direct relationship between OLED screen and eye harm.” Communication industry professionals also said that human eyes are almost imperceptible to the flickering of OLED screens. “Visual fatigue may be caused by staring at the screen for too long.”
Some experts claim that both LCD and OLED screens can harm human eyes because they will emit blue light harmful to the eyes, which is inevitable. However, OLED has a way to avoid this problem, enabling the eye-protection mode (similar to PWM dimming) and changing the color tone of the screen to yellowish.
Many netizens also suggested that when using smartphones with OLED screens, we should increase the brightness as much as possible because the lower the brightness, the more harmful it will be to our eyes. When the brightness of the screen is reduced, the screen of the smartphone will further reduce the flickering frequency.
Some ophthalmologists suggest that “human eyes have different perceptions of OLED flickering, and some people are more sensitive. Sensitive users had better use smartphones with LCD screens.” There has not been a unified medical statement about this conclusion.
Some netizens even made a comparison experiment: you can obviously feel that the screen of P30 Pro is not as good as that of Mate20 Pro. This is easy to understand. Different mobile phones may use different screens, and manufacturers such as Samsung, LG, and BOE have different technologies and product quality.
Some experimental results have shown that screen size is not the main factor influencing visual fatigue but the material and physical properties of different electronic screens.
Even for the same mobile phone, whether the screen is good or not depends on “luck”. Because different brands of OLED screens may be used in the same mobile phone model, in many cases, the mobile phone manufacturer will not specify this, nor does it list the screen provider in detail in the user manual.
For example, Mate20 pro screen suppliers include BOE and LG, and some of their products have experienced “green screen” events after being released on the market. According to media reports, all the mobile phones with green screen problems are those with LG screens. That is to say, the screens in the same mobile phone model may be different for the same price. Whether the mobile phone is good or not depends on luck.
This is almost a common problem in the industry. Initially, both the iPhone XS and XS MAX were equipped with Samsung’s OLED screens. But then Apple listed LG as its second iPhone XS screen supplier. In other words, LG screens may be used in the subsequent batches of iPhone XS and XS MAX. Whether consumers buy LG screens or Samsung screens depends on luck.
The color of OELD screens is more vivid, fuller, and realistic. High-end smartphones have been equipped with OLED screens, which have become the mainstream; LCD screens have been used for low-end smartphones, which are no longer the preferred choice.
Why did this happen? “Terminal products such as the ones with fingerprints under the screen and ultra-thin products can only be realized by using OLED screens.” It has become a common recognition in the industry.
Now there is good news BOE suddenly announced that it has successfully developed fingerprint technology under LCD screen, which will be mass-produced by the end of this year.
It is unrealistic for the mobile phone industry to return to LCD screens from OLED screens, and even some people think it means the degeneration of technology. From the perspective of eye health alone, LCD screens will also emit blue light harmful to human eyes. If we really want to protect our eyes, we must reduce the time consumed by smartphones.
In the visible light spectrum, blue light has wavelengths adjacent to ultraviolet light. Compared to the factory preset setting of 6500 K of typical LCD monitors, Paper Mode is closer to the spectral distribution with long reddish wavelengths so it reduces the amount of blue light, a cause of eye fatigue, and helps prevent eyestrain when reading documents. When used in conjunction with Auto EcoView dimming function, blue light can be reduced by as much as 80%.
Due to the way brightness is controlled on LED backlights, a small number of people perceive flicker on their screen which causes eye fatigue. FlexScan Frameless monitors utilize a hybrid solution to regulate brightness and make flicker unperceivable without any drawbacks like compromising color stability – even on low brightness settings.
The monitor uses an LED-backlit IPS (in-plane switching) LCD panel with 178° viewing angle that minimizes color shift and contrast changes when viewing the screen at an angle. This means that two people sitting at the one computer can easily see the screen with high image quality.
There are many reasons to restrict the amount of time you spend in front of an electronic screen. For example, more hours sitting at a computer or smartphone means fewer hours of being physically active, and looking at a computer screen at night can stimulate the brain and make it difficult to fall asleep.
Here"s another reason to curb screen time: a problem called computer vision syndrome — an umbrella term for conditions that result from looking at a computer or smartphone screen. "It"s most prevalent with computers, and typically occurs when looking at a screen at arm"s length or closer," says Dr. Matthew Gardiner, an ophthalmologist with Harvard-affiliated Massachusetts Eye and Ear Infirmary.
One is dry eyes, caused by a lack of blinking. "When you look at a screen, you"re so involved that you forget to blink. The blink rate goes from 15 times a minute to five or seven times per minute," explains Dr. Gardiner. But you need to blink to re-establish the tear film on the eyes — a thin layer of liquid that protects the surface of the eye. If you don"t blink enough, your eyes dry out, causing blurry vision and discomfort.
The other main problem from staring at a screen too long is eyestrain. Dr. Gardiner says one possible cause of this is the brightness or glare that comes from the electronic screen. "Bright light sources can feel uncomfortable, especially if you have cataracts," Dr. Gardiner says. Eyestrain can also result from focusing up close on a screen without the proper eyeglass prescription. "Any time you strain to see something, maybe because you need reading glasses and have resisted getting them, you can get a headache. You can exhaust your eyes" ability to focus," says Dr. Gardiner.
Some research has even suggested that eyestrain may result from difficulty focusing on the text and images on computer screens in particular, since they"re made of pixels that create blurry edges.
Fortunately, eyestrain and dry eyes are easily treated. Dr. Gardiner recommends using artificial tears several times throughout the day. The artificial tears don"t have to be preservative-free. Another tip: remind yourself to blink from time to time.
If you have eyestrain and headaches after looking at the computer screen for long periods, make sure your eyeglass prescription is up to date. "The proper glasses can reduce eyestrain," says Dr. Gardiner. "The classic example is a person who never needed glasses, and then after age 45 has trouble seeing up close and is straining all day and getting headaches. Once the person gets reading glasses, the headaches are gone."
Dr. Gardiner"s best advice: take a break from electronic screens every 15 to 30 minutes, just for a minute. "Look away from the screen. Do something else, and refocus on a distant target."
Mom warned you not to sit too close to the TV when you were a kid. "In the past, screens were bombarded with energy. That emission back in the 1950s was too strong. In the "60s and "70s, they made safer TVs. Now with LCD or LED TVs, there"s nothing coming out of the screen to hurt you," says Dr. Matthew Gardiner, an ophthalmologist with Harvard-affiliated Massachusetts Eye and Ear Infirmary.
Watching TV for long periods won"t generally lead to computer vision syndrome, since you"re using your distance vision for viewing, not close-up vision, which risks eyestrain. However, sitting too close to a big-screen TV may cause neck strain. "You"ll only see what"s right in front of you, and end up looking around to see all aspects of the screen," says Dr. Gardiner.
More suggestions... if it doesn"t affect your projects, turn the color scheme to grey(darker) document backgrounds rather than white. You can also get a firefox addon called "color that site" which does a custom color scheme or simple brightness slider on a per site basis and stores it.
All lcd"s also blur, and you can become hypersensitive to it. That shouldn"t be a problem using documents so much, but video and gaming blurring can make your eyes strain trying to refocus-away the blur every time.
I’m here to quell your health concerns: staring at a screen doesn’t damage your eyes. They won’t make you go blind, and your doctor isn’t going to worry about your health if he or she hears that you’re spending a lot of time in front of them. However, you might feel uncomfortable after a long time in front of a backlight, and you might even experience the symptoms of Computer Vision Syndrome, a fancy name for the eye strain and discomfort monitors can cause.
You could try adjusting your entire monitor and desk setup to remedy your pain, or you could use moistening eyedrops. The 20-20-20 rule also exists, which dictates that after 20 minutes of screen staring, you should stare at something 20 feet away for 20 seconds. Take a break. Those blue light-filtering glasses you bought could help, too, but doctors aren’t totally convinced. Science just doesn’t back up these glasses’ claims. That said, you could still wear them and hope for the best. They aren’t going to hurt you.
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, digital clocks, calculators, and mobile telephones, including smartphones. LCD screens are also used on consumer electronics products such as DVD players, video game devices and clocks. LCD screens have replaced heavy, bulky cathode-ray tube (CRT) displays in nearly all applications. LCD screens are available in a wider range of screen sizes than CRT and plasma displays, with LCD screens available in sizes ranging from tiny digital watches to very large television receivers. LCDs are slowly being replaced by OLEDs, which can be easily made into different shapes, and have a lower response time, wider color gamut, virtually infinite color contrast and viewing angles, lower weight for a given display size and a slimmer profile (because OLEDs use a single glass or plastic panel whereas LCDs use two glass panels; the thickness of the panels increases with size but the increase is more noticeable on LCDs) and potentially lower power consumption (as the display is only "on" where needed and there is no backlight). OLEDs, however, are more expensive for a given display size due to the very expensive electroluminescent materials or phosphors that they use. Also due to the use of phosphors, OLEDs suffer from screen burn-in and there is currently no way to recycle OLED displays, whereas LCD panels can be recycled, although the technology required to recycle LCDs is not yet widespread. Attempts to maintain the competitiveness of LCDs are quantum dot displays, marketed as SUHD, QLED or Triluminos, which are displays with blue LED backlighting and a Quantum-dot enhancement film (QDEF) that converts part of the blue light into red and green, offering similar performance to an OLED display at a lower price, but the quantum dot layer that gives these displays their characteristics can not yet be recycled.
Since LCD screens do not use phosphors, they rarely suffer 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 are, however, susceptible to image persistence.battery-powered electronic equipment more efficiently than a CRT can be. By 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes.
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, along with OLED displays, 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.
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 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,transparent and flexible, but they cannot emit light without a backlight like OLED and microLED, which are other technologies that can also be made flexible and transparent.
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.
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),
Due to the LCD layer that generates the desired high resolution images at flashing video speeds using very low power electronics in combination with LED based backlight technologies, LCD technology has become the dominant display technology for products such as televisions, desktop monitors, notebooks, tablets, smartphones and mobile phones. Although competing OLED technology is pushed to the market, such OLED displays do not feature the HDR capabilities like LCDs in combination with 2D LED backlight technologies have, reason why the annual market of such LCD-based products is still growing faster (in volume) than OLED-based products while the efficiency of LCDs (and products like portable computers, mobile phones and televisions) may even be further improved by preventing the light to be absorbed in the colour filters of the LCD.
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 are COG (Chip-On-Glass) and TAB (Tape-automated bonding) These same principles apply also for smartphone screens that are much smaller than TV screens.anisotropic conductive film or, for lower densities, elastomeric connectors.
Monochrome and later color passive-matrix LCDs were standard in most early laptops (although a few used plasma displaysGame Boyactive-matrix became standard on all laptops. The commercially unsuccessful Macintosh Portable (released in 1989) was one of the first to use an active-matrix display (though still monochrome). Passive-matrix LCDs are still used in the 2010s for applications less demanding than laptop computers and TVs, such as inexpensive calculators. In particular, these are used on portable devices where less information content needs to be displayed, lowest power consumption (no backlight) and low cost are desired or readability in direct sunlight is needed.
A comparison between a blank passive-matrix display (top) and a blank active-matrix display (bottom). A passive-matrix display can be identified when the blank background is more grey in appearance than the crisper active-matrix display, fog appears on all edges of the screen, and while pictures appear to be fading on the screen.
STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame. Individual pixels are addressed by the corresponding row and column circuits. This type of display is called response times and poor contrast are typical of passive-matrix addressed LCDs with too many pixels and driven according to the "Alt & Pleshko" drive scheme. Welzen and de Vaan also invented a non RMS drive scheme enabling to drive STN displays with video rates and enabling to show smooth moving video images on an STN display.
Bistable LCDs do not require continuous refreshing. Rewriting is only required for picture information changes. In 1984 HA van Sprang and AJSM de Vaan invented an STN type display that could be operated in a bistable mode, enabling extremely high resolution images up to 4000 lines or more using only low voltages.
High-resolution color displays, such as modern LCD computer monitors and televisions, use an active-matrix structure. A matrix of thin-film transistors (TFTs) is added to the electrodes in contact with the LC layer. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is selected, all of the column lines are connected to a row of pixels and voltages corresponding to the picture information are driven onto all of the column lines. The row line is then deactivated and the next row line is selected. All of the row lines are selected in sequence during a refresh operation. Active-matrix addressed displays look brighter and sharper than passive-matrix addressed displays of the same size, and generally have quicker response times, producing much better images. Sharp produces bistable reflective LCDs with a 1-bit SRAM cell per pixel that only requires small amounts of power to maintain an image.
Segment LCDs can also have color by using Field Sequential Color (FSC LCD). This kind of displays have a high speed passive segment LCD panel with an RGB backlight. The backlight quickly changes color, making it appear white to the naked eye. The LCD panel is synchronized with the backlight. For example, to make a segment appear red, the segment is only turned ON when the backlight is red, and to make a segment appear magenta, the segment is turned ON when the backlight is blue, and it continues to be ON while the backlight becomes red, and it turns OFF when the backlight becomes green. To make a segment appear black, the segment is always turned ON. An FSC LCD divides a color image into 3 images (one Red, one Green and one Blue) and it displays them in order. Due to persistence of vision, the 3 monochromatic images appear as one color image. An FSC LCD needs an LCD panel with a refresh rate of 180 Hz, and the response time is reduced to just 5 milliseconds when compared with normal STN LCD panels which have a response time of 16 milliseconds.
Samsung introduced UFB (Ultra Fine & Bright) displays back in 2002, utilized the super-birefringent effect. It has the luminance, color gamut, and most of the contrast of a TFT-LCD, but only consumes as much power as an STN display, according to Samsung. It was being used in a variety of Samsung cellular-telephone models produced until late 2006, when Samsung stopped producing UFB displays. UFB displays were also used in certain models of LG mobile phones.
In-plane switching is an LCD technology that aligns the liquid crystals in a plane parallel to the glass substrates. In this method, the electrical field is applied through opposite electrodes on the same glass substrate, so that the liquid crystals can be reoriented (switched) essentially in the same plane, although fringe fields inhibit a homogeneous reorientation. This requires two transistors for each pixel instead of the single transistor needed for a standard thin-film transistor (TFT) display. The IPS technology is used in everything from televisions, computer monitors, and even wearable devices, especially almost all LCD smartphone panels are IPS/FFS mode. IPS displays belong to the LCD panel family screen types. The other two types are VA and TN. Before LG Enhanced IPS was introduced in 2001 by Hitachi as 17" monitor in Market, the additional transistors resulted in blocking more transmission area, thus requiring a brighter backlight and consuming more power, making this type of display less desirable for notebook computers. Panasonic Himeji G8.5 was using an enhanced version of IPS, also LGD in Korea, then currently the world biggest LCD panel manufacture BOE in China is also IPS/FFS mode TV panel.
In 2011, LG claimed the smartphone LG Optimus Black (IPS LCD (LCD NOVA)) has the brightness up to 700 nits, while the competitor has only IPS LCD with 518 nits and double an active-matrix OLED (AMOLED) display with 305 nits. LG also claimed the NOVA display to be 50 percent more efficient than regular LCDs and to consume only 50 percent of the power of AMOLED displays when producing white on screen.
This pixel-layout is found in S-IPS LCDs. A chevron shape is used to widen the viewing cone (range of viewing directions with good contrast and low color shift).
Vertical-alignment displays are a form of LCDs in which the liquid crystals naturally align vertically to the glass substrates. When no voltage is applied, the liquid crystals remain perpendicular to the substrate, creating a black display between crossed polarizers. When voltage is applied, the liquid crystals shift to a tilted position, allowing light to pass through and create a gray-scale display depending on the amount of tilt generated by the electric field. It has a deeper-black background, a higher contrast ratio, a wider viewing angle, and better image quality at extreme temperatures than traditional twisted-nematic displays.
Blue phase mode LCDs have been shown as engineering samples early in 2008, but they are not in mass-production. The physics of blue phase mode LCDs suggest that very short switching times (≈1 ms) can be achieved, so time sequential color control can possibly be realized and expensive color filters would be obsolete.
Some LCD panels have defective transistors, causing permanently lit or unlit pixels which are commonly referred to as stuck pixels or dead pixels respectively. Unlike integrated circuits (ICs), LCD panels with a few defective transistors are usually still usable. Manufacturers" policies for the acceptable number of defective pixels vary greatly. At one point, Samsung held a zero-tolerance policy for LCD monitors sold in Korea.ISO 13406-2 standard.
Dead pixel policies are often hotly debated between manufacturers and customers. To regulate the acceptability of defects and to protect the end user, ISO released the ISO 13406-2 standard,ISO 9241, specifically ISO-9241-302, 303, 305, 307:2008 pixel defects. However, not every LCD manufacturer conforms to the ISO standard and the ISO standard is quite often interpreted in different ways. LCD panels are more likely to have defects than most ICs due to their larger size. For example, a 300 mm SVGA LCD has 8 defects and a 150 mm wafer has only 3 defects. However, 134 of the 137 dies on the wafer will be acceptable, whereas rejection of the whole LCD panel would be a 0% yield. In recent years, quality control has been improved. An SVGA LCD panel with 4 defective pixels is usually considered defective and customers can request an exchange for a new one.
Some manufacturers, notably in South Korea where some of the largest LCD panel manufacturers, such as LG, are located, now have a zero-defective-pixel guarantee, which is an extra screening process which can then determine "A"- and "B"-grade panels.clouding (or less commonly mura), which describes the uneven patches of changes in luminance. It is most visible in dark or black areas of displayed scenes.
The zenithal bistable device (ZBD), developed by Qinetiq (formerly DERA), can retain an image without power. The crystals may exist in one of two stable orientations ("black" and "white") and power is only required to change the image. ZBD Displays is a spin-off company from QinetiQ who manufactured both grayscale and color ZBD devices. Kent Displays has also developed a "no-power" display that uses polymer stabilized cholesteric liquid crystal (ChLCD). In 2009 Kent demonstrated the use of a ChLCD to cover the entire surface of a mobile phone, allowing it to change colors, and keep that color even when power is removed.
In 2004, researchers at the University of Oxford demonstrated two new types of zero-power bistable LCDs based on Zenithal bistable techniques.e.g., BiNem technology, are based mainly on the surface properties and need specific weak anchoring materials.
Resolution The resolution of an LCD is expressed by the number of columns and rows of pixels (e.g., 1024×768). Each pixel is usually composed 3 sub-pixels, a red, a green, and a blue one. This had been one of the few features of LCD performance that remained uniform among different designs. However, there are newer designs that share sub-pixels among pixels and add Quattron which attempt to efficiently increase the perceived resolution of a display without increasing the actual resolution, to mixed results.
Spatial performance: For a computer monitor or some other display that is being viewed from a very close distance, resolution is often expressed in terms of dot pitch or pixels per inch, which is consistent with the printing industry. Display density varies per application, with televisions generally having a low density for long-distance viewing and portable devices having a high density for close-range detail. The Viewing Angle of an LCD may be important depending on the display and its usage, the limitations of certain display technologies mean the display only displays accurately at certain angles.
Temporal performance: the temporal resolution of an LCD is how well it can display changing images, or the accuracy and the number of times per second the display draws the data it is being given. LCD pixels do not flash on/off between frames, so LCD monitors exhibit no refresh-induced flicker no matter how low the refresh rate.
Color performance: There are multiple terms to describe different aspects of color performance of a display. Color gamut is the range of colors that can be displayed, and color depth, which is the fineness with which the color range is divided. Color gamut is a relatively straight forward feature, but it is rarely discussed in marketing materials except at the professional level. Having a color range that exceeds the content being shown on the screen has no benefits, so displays are only made to perform within or below the range of a certain specification.white point and gamma correction, which describe what color white is and how the other colors are displayed relative to white.
Brightness and contrast ratio: Contrast ratio is the ratio of the brightness of a full-on pixel to a full-off pixel. The LCD itself is only a light valve and does not generate light; the light comes from a backlight that is either fluorescent or a set of LEDs. Brightness is usually stated as the maximum light output of the LCD, which can vary greatly based on the transparency of the LCD and the brightness of the backlight. Brighter backlight allows stronger contrast and higher dynamic range (HDR displays are graded in peak luminance), but there is always a trade-off between brightness and power consumption.
Usually no refresh-rate flicker, because the LCD pixels hold their state between refreshes (which are usually done at 200 Hz or faster, regardless of the input refresh rate).
No theoretical resolution limit. When multiple LCD panels are used together to create a single canvas, each additional panel increases the total resolution of the display, which is commonly called stacked resolution.
As an inherently digital device, the LCD can natively display digital data from a DVI or HDMI connection without requiring conversion to analog. Some LCD panels have native fiber optic inputs in addition to DVI and HDMI.
As of 2012, most implementations of LCD backlighting use pulse-width modulation (PWM) to dim the display,CRT monitor at 85 Hz refresh rate would (this is because the entire screen is strobing on and off rather than a CRT"s phosphor sustained dot which continually scans across the display, leaving some part of the display always lit), causing severe eye-strain for some people.LED-backlit monitors, because the LEDs switch on and off faster than a CCFL lamp.
Only one native resolution. Displaying any other resolution either requires a video scaler, causing blurriness and jagged edges, or running the display at native resolution using 1:1 pixel mapping, causing the image either not to fill the screen (letterboxed display), or to run off the lower or right edges of the screen.
Fixed bit depth (also called color depth). Many cheaper LCDs are only able to display 262144 (218) colors. 8-bit S-IPS panels can display 16 million (224) colors and have significantly better black level, but are expensive and have slower response time.
Input lag, because the LCD"s A/D converter waits for each frame to be completely been output before drawing it to the LCD panel. Many LCD monitors do post-processing before displaying the image in an attempt to compensate for poor color fidelity, which adds an additional lag. Further, a video scaler must be used when displaying non-native resolutions, which adds yet more time lag. Scaling and post processing are usually done in a single chip on modern monitors, but each function that chip performs adds some delay. Some displays have a video gaming mode which disables all or most processing to reduce perceivable input lag.
Dead or stuck pixels may occur during manufacturing or after a period of use. A stuck pixel will glow with color even on an all-black screen, while a dead one will always remain black.
In a constant-on situation, thermalization may occur in case of bad thermal management, in which part of the screen has overheated and looks discolored compared to the rest of the screen.
Loss of brightness and much slower response times in low temperature environments. In sub-zero environments, LCD screens may cease to function without the use of supplemental heating.
The production of LCD screens uses nitrogen trifluoride (NF3) as an etching fluid during the production of the thin-film components. NF3 is a potent greenhouse gas, and its relatively long half-life may make it a potentially harmful contributor to global warming. A report in Geophysical Research Letters suggested that its effects were theoretically much greater than better-known sources of greenhouse gasses like carbon dioxide. As NF3 was not in widespread use at the time, it was not made part of the Kyoto Protocols and has been deemed "the missing greenhouse gas".
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In the modern world, our eyes are constantly bombarded with information from displays. Whether it be from a laptop, smartphone, or some other device, many of us spend a significant portion of our day staring at some kind of display. As such, it is paramount that we should understand the strain placed on our vision and some steps we can take to improve and protect the health of our eyes.
Our eyes are