are lcd monitors hazardous made in china

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Some chemicals in liquid crystal displays (LCDs) could alter genes, they said. Animal cells mutated unexpectedly if exposed, and preliminary results of their ongoing study published in Proceedings of the National Academy of Sciences on Monday (Dec 9) showed that one of the most polluted places was the home.

Over the years, screen panel manufacturers have pushed LCD technology to higher resolutions and faster refreshing rates, but the chemical composition of the liquid crystal that fills their screens has hardly changed.

They exposed embryonic chicken cells to liquid crystal taken from the screens and compared them to cells grown in normal conditions. They found genetic changes that suggested the exposed cells had mutated.

Scientists have discovered that LCD screens leak chemicals into just about every environment where they are found, according to a new study, and these particles have the potential to be toxic over time.As described in a study published last week in Proceedings of the National Academy of Sciences, researchers collected dust samples from seven buildings in China: a cafeteria, student dorm, classroom, hotel, home, lab, and an electronics repair shop. Nearly half of the 53 samples tested positive for liquid crystal particles—which are supposed to stay sealed in the screen after manufacturing—even in places where there were no LCD devices at the time of collection.AdvertisementThe international research team analyzed 362 chemicals used in LCD screens and found that nearly 100 have the potential to be toxic. These particles don’t break down quickly and have "high mobility" in the environment. When inhaled or ingested, according to the study, these particles can build up in the body over time with toxic effects, potentially causing digestive problems and other health issues.“These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning,” said University of Saskatchewan environmental toxicologist and lead author John Giesy in a press release. “Now we also know that these chemicals are being released by products just by using them.”According to the study, these chemicals are "simply filled" into the space between polarizers (light filters) during manufacturing and are not chemically bonded to any base material. This means that "they can be released during production; through wastewater; or during active use, disposal, or recycling."To be clear, the researchers didn"t observe any adverse health effects from the accumulation of liquid crystals in the human body; they only found that these crystals do in fact leak from devices, and that they have the potential to be toxic.

“We don’t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects,” said Giesy.AdvertisementLab testing showed that the hazardous substances found in phones were similar to flame retardants, which have proven to be toxic to living creatures, creating problems with animals’ digestive systems and hindering their ability to absorb nutrients. They also disrupted their gallbladders and thyroids.The team says the next step is to understand the effect of these chemicals on humans, animals, and the environment. “Since there are more and more of these devices being made, there’s a higher chance of them getting into the environment,” said Giesy.Right now, there are no standards for measuring them and no regulations limiting exposure to them. “We are at ground zero,” he said.Giesy’s previous work was the first to shed a spotlight on toxic perfluorinated and polyfluorinated chemicals (PFCs). PFCs used to be in all kinds of oil and water-resistant products such as raincoats and non-stick pans. His findings led to a global ban of PFCs.

On seemingly every street, laborers sit on the pavement outside workshops ripping out the guts of household appliances with hammers and drills. The roads in Guiyu are lined with bundles of plastic, wires, cables and other garbage. Different components are separated based on their value and potential for re-sale. On one street sits a pile of green and gold circuit boards. On another, the metal cases of desktop computers.

At times, it looks like workers are reaping some giant plastic harvest, especially when women stand on roadsides raking ankle-deep “fields” of plastic chips.

In one workshop, men sliced open sacks of these plastic chips, which they then poured into large vats of fluid. They then used shovels and their bare hands to stir this synthetic stew.

According to the April 2013 U.N. report “E-Waste in China,” Guiyu suffered an “environmental calamity” as a result of the wide-scale e-waste disposal industry in the area.

Most of the workers in Guiyu involved in the e-waste business are migrants from destitute regions of China and poorly educated. Many of them downplayed the potential damage the industry could cause to their health.

Several migrants said that while the work is tough, it allows them more freedom than working on factory lines where young children are not permitted to enter the premises and working hours are stringent.

“Before people were washing metals, burning things and it severely damaged people’s lungs,” Wong added. “But now, compared to before, the [authorities] have cracked down pretty hard.”

A group of farmers who had migrated from neighboring Guangxi province to cultivate rice in Guiyu told CNN they did not dare drink the local well water.

“It may not sound nice, but we don’t dare eat the rice that we farm because it’s planted here with all the pollution,” Zhou said, pointing at water-logged rice paddy next to him.

Asked who did eat the harvested rice, Zhou answered: “How should I know? A lot of it is sold off … they don’t dare label the rice from here as ‘grown in Guiyu.’ They’ll write that its rice from some other place.”

“Why are they stopping the garbage from reaching us?” asked one man who ran a plastic sorting workshop. “Of course it’s hurting our business,” he added.

Potentially toxic chemicals leaking from smartphone, iPhone, television and computer screens in homes, offices, and schools could harm human health, reports a new study. The findings of the study are published in the journal Proceedings of the National Academy of Sciences.

‘LCD Screen Pollution: More toxic chemicals from LCD televisions and computer screens are found in household dust. Liquid crystal monomers, the chemical building blocks of everything from flat-screen TVs to solar panels, are found to be potentially hazardous to humans, animals, and the environment. Hence, identifying a perfect solution to get rid of this LCD screen pollution could save millions of lives, both human and animal.’

"These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning. Now we also know that these chemicals are being released by-products just by using them,"said Giesy, Canada Research Chair in Environmental Toxicology at USask.

"We don"t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects,"said Giesy.

The researchers found the specific monomers isolated from the smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhibit animals" ability to digest nutrients and to disrupt the proper functioning of the gallbladder and thyroid--similar to dioxins and flame retardants which are known to cause toxic effects in humans and wildlife.

To understand how common these monomers are in the environment, researchers tested dust gathered from seven different buildings in China--a canteen, student dormitory, teaching building, hotel, personal residence, lab, and electronics repair facility. Nearly half of the 53 samples tested positive for the liquid crystal monomers.

Ninety percent of the monomers tested had concerning chemical properties. They either accumulate in organisms, resist degradation in the environment, or are easily transported long distances in the atmosphere. Nearly one-quarter of the chemicals tested had all three troubling characteristics.

LCD panels are almost exclusively produced in three Asian countries: China, Japan, and South Korea. It"s estimated that 198 million square metres of liquid crystal display were produced last year--enough to cover the entire Caribbean island of Aruba.

For many years, huge amounts of globally produced e-waste--including LCD displays--have been dismantled, disposed of, and introduced into the environment.

"Right now, there are no measurements of these monomers in surface waters. Our next steps are to understand the fate and effect of these chemicals in the environment,"said Giesy.

Adeline Dorcas. (2019, December 11). LCD Screen Pollution: Your Household Dust may Contain More Toxic Chemicals from LCDs. Medindia. Retrieved on Jan 16, 2023 from https://www.medindia.net/news/healthwatch/lcd-screen-pollution-your-household-dust-may-contain-more-toxic-chemicals-from-lcds-191963-1.htm.

Adeline Dorcas. "LCD Screen Pollution: Your Household Dust may Contain More Toxic Chemicals from LCDs". Medindia. Jan 16, 2023. .

Adeline Dorcas. "LCD Screen Pollution: Your Household Dust may Contain More Toxic Chemicals from LCDs". Medindia. https://www.medindia.net/news/healthwatch/lcd-screen-pollution-your-household-dust-may-contain-more-toxic-chemicals-from-lcds-191963-1.htm. (accessed Jan 16, 2023).

Adeline Dorcas. 2021. LCD Screen Pollution: Your Household Dust may Contain More Toxic Chemicals from LCDs. Medindia, viewed Jan 16, 2023, https://www.medindia.net/news/healthwatch/lcd-screen-pollution-your-household-dust-may-contain-more-toxic-chemicals-from-lcds-191963-1.htm.

By summer, she was admitted to hospital, where doctors struggled to diagnose the cause. "I was terrified. I feared I might be paralysed and spend the rest of my life in a wheelchair," she said.

An occupational diseases hospital which saw several victims diagnosed the problem in August and Wintek stopped using the chemical. But thanks to the previous months of exposure, at least 62 workers would require medical care. Many spent months in hospital.

The chemical"s potential risks are well-known in industry, as are safe exposure limits. But the Wintek manager who decided to switch from alcohol to n-hexane for cleaning – apparently because it dried more quickly – did not assess the dangers. It was used without proper ventilation.

Apple declined to answer questions about the poisonings or about the firms involved, saying it does not reveal who it works with, although its spokeswoman added that Wintek had been "quite proactive" in discussing the issue. Instead it pointed to its code of conduct, which sets strict requirements for working and environmental practices, adding that many suppliers say they are the only customer carrying out such checks.

But the 2010 audit shows that manufacturers are routinely breaching the code. The majority – 54% – broke the 60-hour weekly work limit more than half the time. Another 39% failed to meet occupational injury prevention requirements; 17% failed on chemical exposure standards; and 35% did not meet wage and benefits requirements, with 24 of the 102 factories audited paying less than minimum wage for regular hours.

But until it identifies its manufacturers, outsiders have no way of assessing how well its policies are working and what action it is taking to deal with problems such as the n-hexane poisoning.

"Apple is the most paranoid about commercial and product secrecy. That"s getting in the way of ensuring workers" rights are protected," says Geoff Crothall of China Labour Bulletin, a Hong Kong-based organisation campaigning for workers" rights.

"Apple products are not cheap and most Apple customers are willing to pay a premium – so why not add a tiny little bit extra to ensure working and environmental standards are met, as well as product quality?" he asked.

In the meantime, while Wintek says most of the poisoned employees have returned to work, at least some are opting to protect themselves by leaving factory life.

In China the mountain of discarded TVs, phones, computers, monitors, e-toys and small appliances grew by 6.7m tonnes in 2015 alone. That’s an 107% increase in just five years. To get a sense of scale, if every woman, man and child in China had an old LCD monitor and dumped it the pile would not equal the 2015 tonnage. [1]

The region’s fast-increasing middle class is the main driver of e-waste increases, not population growth, the report by the United Nations University found. However, Asia’s 3.7kg per person of waste is still tiny compared to Europe’s 15.6 kg per person, it said.

“Growing incomes, the creation of more and more gadgets and ever-shorter lifespans of things like mobile phones are the reasons for this tremendous increase in Asia,” said co-author Ruediger Kuehr of the UN University.

Although plenty of e-waste is recycled in Asia it’s mainly done by backyard businesses who resort to hammers and burning to access re-usable metals, resulting in local pollution and health impacts. Mobile phones, TVs, monitors, printers and other electronics contain hazardous materials such as mercury and lead. Ink toner from printers is also considered toxic.

The scale of e-waste exported to Asia has previously been difficult to estimate. BAN put GPS trackers inside old printers and monitors sent to recycling centres in the US last year to enable them to get a clearer picture. About 40% left the US with most ending up in Asia. Nearly all of these exports were illegal under US law. “Some of the trackers died so it’s likely 50% were exported,” Puckett said.

China, once a big importer of e-waste, has cracked down but Hong Kong has picked up the slack, with an estimated 100 containers of e-waste entering the port each day Puckett said. “There are at least a 100 small e-waste junk yards in a semi-rural part of Hong Kong called the New Territories. That’s where we found most of the printers and monitors with our trackers.”

Proper recycling of electronics is costly and expensive and is rarely done, even in the US. Manufacturers need to remove all toxins from their products and make them easier to repair and recycle, said Puckett. Another solution in Puckett’s view is to adopt a lease-based business model where people lease rather than buy most electronics, and use upgrades or trade-ins to get the latest features.[1] My estimate based on the average weight of a 17in LCD monitor – 4.5 kgs. So 220 monitors would weigh 1 tonne

"These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning. Now we also know that these chemicals are being released by products just by using them," said Giesy, Canada Research Chair in Environmental Toxicology at USask.

"We don"t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects," said Giesy.

The researchers found the specific monomers isolated from the smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhibit animals" ability to digest nutrients and to disrupt the proper functioning of the gallbladder and thyroid--similar to dioxins and flame retardants which are known to cause toxic effects in humans and wildlife.

To understand how common these monomers are in the environment, researchers tested dust gathered from seven different buildings in China--a canteen, student dormitory, teaching building, hotel, personal residence, lab, and electronics repair facility. Nearly half of the 53 samples tested positive for the liquid crystal monomers.

Ninety per cent of the monomers tested had concerning chemical properties. They either accumulate in organisms, resist degradation in the environment, or are easily transported long distances in the atmosphere. Nearly one quarter of the chemicals tested had all three troubling characteristics.

LCD panels are almost exclusively produced in three Asian countries: China, Japan, and South Korea. It"s estimated that 198 million square metres of liquid crystal display were produced last year--enough to cover the entire Caribbean island of Aruba.

For many years, huge amounts of globally produced e-waste--including LCD displays--have been dismantled, disposed of, and introduced into the environment.

"Right now, there are no measurements of these monomers in surface waters. Our next steps are to understand the fate and effect of these chemicals in the environment," said Giesy.

Puckett’s documentary came out more than a decade after nearly every developed nation on the globe had ratified the Basel Convention, an international treaty to stop developed countries from dumping hazardous waste on poorer nations.

The U.S. is the only industrialized country in the world that hasn’t ratified the treaty. Its hazardous waste is still getting exported to countries with fewer health and environmental safety laws, according to Puckett’s latest investigation.

"The vast majority of electronics collected for recycling in the U.S. are recycled in the U.S.," says Eric Harris of the Institute of Scrap Recycling Industries, a Washington, D.C-based recycling trade association. "We would really challenge the notion that there"s a mass exodus of equipment that"s leaving in an unprocessed manner."

Puckett’s GPS receiver leads the way to another set of high fences. A sign out front proclaims that it’s farmland. But a look over the fence reveals a lot the size of a football field piled 15-feet high with printers. Workers are breaking them. Their clothes are dusted black with toner ink, a probable carcinogen known to cause respiratory problems.

Su talks to the workers and finds out many are migrants from mainland China who are residing in Hong Kong without the official documents required for them to legally be there, she says.

Electronics are often labeled as raw plastics to get through customs, Lau said, but they’re actually whole devices that the junkyard workers dismantle. They sell the most valuable components to buyers in mainland China, while workers indiscriminately dump the worthless leftovers.

“When I was young, I used to drink water directly from the river,” he says through an interpreter. “Now I do not even dare drink water from the well.”

Hong Kong bans the import of hazardous e-waste like cathode ray tubes and flat-screens from the United States and other developed nations, according to Environmental Protection Department spokesperson Heidi Liu.

“On the whole, Hong Kong has been effective in combatting hazardous waste shipments,” Liu says, citing 21 instances in the past three years in which cargo loads of e-waste were sent back to the United States.

Electronics recyclers with e-Stewards certification can export the raw plastics and metals that come from dismantling electronics. But they adopt a strict no-export policy with regard to whole, non-working electronics with hazardous materials still inside. They can also export used electronics as long as they"ve been tested and proven to be still functioning.

Last May, Puckett’s team dropped two non-working LCD TVs, with tracking devices placed inside, at separate recyclers in Oregon. From there, the tracked electronics traveled to Total Reclaim’s warehouse in south Seattle. Then they went to the Port of Seattle, across the Pacific Ocean to the Port of Hong Kong and ultimately to two junkyards in the New Territories.

"Goodwill Industries International is committed to understanding new insights into the e-cycling space from the final report," the statement states, and "encourages Goodwill organizations participating in the Dell Reconnect program to evaluate the continuation of their contracts with Dell" to take steps to ensure that electronics are responsibly recycled.

In a phone interview, co-owner Craig Lorch acknowledged that some of Total Reclaim"s LCD flat-screen monitors have been shipped to Hong Kong, despite the company’s no-export policy.

Both the Oregon Department of Environmental Quality and the Washington Department of Ecology have launched investigations into whether Total Reclaim violated their state hazardous waste laws.

Lorch says economic realities forced the company to renege on pledges to recycle all the waste that they collect. In recent years, LCD monitors have become a larger portion of the waste stream, but the flatscreens are expensive and time-consuming to dismantle.

Printers, which hold little value, and LCD TVs, which are expensive to recycle because of the tedious dismantling work associated with mercury, make good candidates for export.

“This e-waste recycling business is like the wild, wild west,” says Wendy Neu, a 30-year veteran of the recycling and scrap metal industry. “People are getting paid to recycle these materials through government programs and then are exporting to China and Africa.”

The Institute of Scrap Recycling Industries has opposed versions of those bills, arguing that these types of laws on exports would harm the recycling sector and are unnecessary because the industry is well-regulated by existing state and federal laws.

Long, the 18-year-old daughter of peasant farmers from Guizhou, was supposed to dip her rubber-gloved right index finger into the oil and then rub each screen for 10 to 20 seconds. The company—Fangtai Huawei Electronic Technology—gave Long and her coworkers paper masks, but they rarely used them. They were too hot, and anyway the women who worked there often exhaled onto the screens because the condensed moisture from their breath made cleaning easier. Long worked from 8 am until 11 pm, and as late as 4 am in the busy season.

She didn"t complain. Long had fallen onto a kerosene lamp when she was 1 year old and burned her face; her father told her she had to be extra cheerful to make up for the scarring. Long had hoped to be a teacher for blind and deaf children, to help them through their own disabilities, but, tired of watching her parents labor in the field day after day, Long left for the city in the winter of 2011. At Fangtai Huawei, with overtime she could earn as much as 3,000 yuan (about $485) a month to help her family.

But if working conditions were improving at Chinese factories, Long did not see it. Soon after she began working at Fangtai Huawei, her fingertips started tingling. After a few months, her feet and hands were numb. Long couldn"t hold the screens properly. Her coworkers started getting sick too—Zi Renchun, a 25-year-old from Yunnan province, lost her appetite. Shang Jiaojiao, who had begun working at age 14, had joint pain and eventually could barely lift herself out of bed. By summer, some of the workers were collapsing.

In mid-July, Long found herself unable to move her legs. “I was just lying on my bed all day and needed help to eat,” she says. Long ended up in a hospital in Guangzhou with more than 30 other Fangtai Huawei workers. Doctors found they"d been exposed to n-hexane, presumably in the “banana oil.” It"s an industrial solvent that causes neurological damage at just 50 parts per million. Workers using it are supposed to wear respirators and operate in a ventilated area. As treatment, Long endured daily injections—she says they “hurt more than anything else in the world.” We interviewed her in a hotel a few blocks from the hospital; officials there wouldn"t answer our questions or allow us to see her on the premises. Long still tries to stay cheerful. “When I cry,” she says, “I cry secretly.”

Even after the reforms triggered by the Foxconn scandal, thousands of people like Long arrive young and healthy in China"s cities every year only to face the health consequences of working for factories with inadequate labor safeguards. Nobody really knows how many are injured or get sick; official Chinese government statistics put the workplace injury rate at 115 per 10,000 workers—slightly higher than the US and significantly higher than the European Union. But few observers trust China"s numbers. The government underreports occupational injuries, and one survey found that as many as seven out of 10 migrant workers, who make up a third of the workforce, don"t participate in China"s workers" compensation system.

Electronic waste or e-waste in China refers to electronic products that are no longer usable and are therefore dumped or recycled. China is the world"s largest importer and producer of electronic waste

The major sources of e-waste processed in China are households, domestic institutions such as schools and hospitals, government agencies and businesses, and equipment manufacturers.

In 2012, China adopted the extended producer responsibility (EPR) system from the EU, which held manufacturers responsible for the collection and recycling of electronics. Otherwise known as “Producer Takeback,” the EPR management system requires manufacturers to carry out environmentally safe management of their products even after they are discarded.

Though legislation and regulations have been accepted by the developed countries against illegal exportation of e-waste, the high number of illegal shipments continues to exacerbate the e-waste problem in China.Basel Convention out of the EU or the OECD but illegal shipments are still rising in China and other developing countries.

Many companies, like Nintendo, are aware of the problem of e-waste and are developing their own initiatives such as creating collective e-waste reclamation campaigns.

In 1992, the United Nations Basel Convention was established to control the transboundary movement and disposal of hazardous waste. The Basel Convention makes up the global legal infrastructure addressing the transnational trade of e-waste. It is the centerpiece of an international legal regime that has shaped or influenced many countries’ national legislation on e-waste.

The Convention does not impose a complete ban on the international transfer of hazardous waste. The transfer may be allowed under certain conditions, for example, if the state of export does not have the technical capacity and the necessary facilities, capacity or suitable disposal sites in order to dispose of the wastes in question in an environmentally sound and efficient manner. The definition of some of these key terms, “technical capacity,” “necessary facilities,” “environmentally sound and efficient manners,” and “wastes required as raw material” can be rather controversial in practice. Different countries may understand differently what can be counted as “necessary facilities” and what varieties of materials should be seen as “e-waste.

At the global scale, trajectories of global e-waste flows are shaped by the multitude of loopholes, contradictions and ambiguous articles left by the Basel Convention and by different countries’ disparate attitudes towards the e-waste trade.

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.

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.MicroLED.)

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.

Displays having a passive-matrix structure are employing Crosstalk between activated and non-activated pixels has to be handled properly by keeping the RMS voltage of non-activated pixels below the threshold voltage as discovered by Peter J. Wild in 1972,

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 t