how to repair an lcd screen made in china
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Mandy, ETS is obviously a company that you are connected to and this could easily be taken for spam. I think we can make an exception at this time since you are asking a good market research question that may be useful to many.
Having checked out your video, I personally will not use the aftermarket screen as a replacement for my X. It just doesn"t have what I expect for a $1000 USD phone. I recognize that $300 USD for a replacement is hefty but the aftermarket screen does not appear to have the quality that I would expect for my phone.
Maybe your significant other tossed your phone off the balcony after discovering flirty texts with a certain coworker, or maybe you were just blackout drunk and dropped your phone on the club’s tile washroom floor while taking a shameless mirror selfie. Either way, your mobile’s glass screen likely looks like a drunken spider’s web.
Luckily for you, smartphone repairs in China are both affordable and fast. But before you venture off to your city’s electronics sales and repair market, we encourage you to browse these six helpful tips for repairing your phone screen:
As with damage to just about any electronic product, knowing the extent of the destruction will go a long way towards ensuring your trusty repairman doesn’t try and pull a fast one by over-quoting or overstating the damage.
In the case of phone glass and the LCD – or more recently AMOLED – screen underneath, it helps to know whether just one, or both, of these elements needs replacing (particularly so you can better estimate the cost).
While broken glass on the front of your mobile is obvious and easy to diagnose, a damaged screen (the part that actually displays all the programs and interface) can be a bit trickier to identify. Look for black spots, discolored areas, new lines and out-of-place patterns on your screen, as any of these may indicate a problem with the screen. Naturally, a totally black screen is a pretty good indicator that something is amiss.
One way to test your screen is to hold down on an app on your phone’s ‘desktop area’ until it starts vibrating, allowing you the move the app to new locations on your screen. Move the app to all parts of your display, if the app is unable to reach a certain area, this is a good indication that you’ll be fixing more than just broken glass.
From our experience, this may very likely be the most important step of all. When having your device"s screen or glass fixed, be sure to show the person doing the repair that all of its key components are in working order. In particular, be sure to demonstrate that both your front and rear cameras work, as well as the speaker and microphone.
We cannot count how many times we have heard of a phone being returned after a repair only for the owner to discover that the phone’s microphone (key for, you know, speaking on the phone) or cameras are no longer working. Also from experience: most repair people are unlikely to take your word that your camera was fine before you handed it over to them.
This should probably go without saying, but here we go anyway: having your mobile device repaired by someone other than a company technician from your phone’s particular brand will likely (like basically 100 percent) result in your warranty being voided.
Not every repair shop will give you the option of watching your phone’s crushed glass be replaced. This is because many smaller shops, particularly in electronics markets, will have your phone sent to an offsite repair area and tell you to come back in a few hours to collect it.
If possible, try and find a shop that will complete the repair in front of you. The main reason we encourage this is because we have heard several unfortunate stories where costumers have had their fully-functioning phone battery swapped out for one that can only hold a two-hour charge. Sad!
The price of having your phone’s glass or LCD screen replaced will depend greatly on the make and model of your phone, the honesty of the person fixing it and – like all things in Asia – your bargaining skills. If your local smartphone repair person wants RMB300 to replace your iPhone 6’s shattered glass, lowball them and offer RMB150. From our experience, repair people seem more inclined to budge on price when it comes to older model phones, meaning your brand new iPhone Xs Plus or Huawei P20 will likely have a higher price point and less discount wiggle-room.
Finding a good repair shop with honest staff who do repairs at a high quality and reasonable price can sometimes be difficult. If you manage to track down a good phone-fixing location, be sure to recommend it to your friends to save them the potentially costly and annoying trial-and-error process when having their glass or screen replaced.
Our Service 1.We Will provide you User manual in English or operating videos for free. 2.24 hours technical support by email or video call via we chat or skype. 3. Free training to make sure you master the operating of our products.
► When the leading Korean players Samsung Display and LG Display exit LCD production, BOE will be the most significant player in the LCD market. Though OLED can replace the LCD, it will take years for it to be fully replaced.
► As foreign companies control evaporation material and machines, panel manufacturers seek a cheaper way to mass-produce OLED panels – inkjet printing.
When mainstream consumer electronics brands choose their device panels, the top three choices are Samsung Display, LG Display (LGD) and BOE (000725:SZ) – the first two from Korea and the third from China. From liquid-crystal displays (LCD) to active-matrix organic light-emitting diode (AMOLED), display panel technology has been upgrading with bigger screen products.
From the early 1990s, LCDs appeared and replaced cathode-ray tube (CRT) screens, which enabled lighter and thinner display devices. Japanese electronics companies like JDI pioneered the panel technology upgrade while Samsung Display and LGD were nobodies in the field. Every technology upgrade or revolution is a chance for new players to disrupt the old paradigm.
The landscape was changed in 2001 when Korean players firstly made a breakthrough in the Gen 5 panel technology – the later the generation, the bigger the panel size. A large panel size allows display manufacturers to cut more display screens from one panel and create bigger-screen products. "The bigger the better" is a motto for panel makers as the cost can be controlled better and they can offer bigger-size products to satisfy the burgeoning middle-class" needs.
LCD panel makers have been striving to realize bigger-size products in the past four decades. The technology breakthrough of Gen 5 in 2002 made big-screen LCD TV available and it sent Samsung Display and LGD to the front row, squeezing the market share of Japanese panel makers.
The throne chair of LCD passed from Japanese companies to Korean enterprises – and now Chinese players are clinching it, replacing the Koreans. After twenty years of development, Chinese panel makers have mastered LCD panel technology and actively engage in large panel R&D projects. Mass production created a supply surplus that led to drops in LCD price. In May 2020, Samsung Display announced that it would shut down all LCD fabs in China and Korea but concentrate on quantum dot LCD (Samsung calls it QLED) production; LGD stated that it would close LCD TV panel fabs in Korea and focus on organic LED (OLED). Their retreats left BOE and China Stars to digest the LCD market share.
Consumer preference has been changing during the Korean fab"s recession: Bigger-or-not is fine but better image quality ranks first. While LCD needs the backlight to show colors and substrates for the liquid crystal layer, OLED enables lighter and flexible screens (curvy or foldable), higher resolution and improved color display. It itself can emit lights – no backlight or liquid layer is needed. With the above advantages, OLED has been replacing the less-profitable LCD screens.
Samsung Display has been the major screen supplier for high-end consumer electronics, like its own flagship cell phone products and Apple"s iPhone series. LGD dominated the large OLED TV market as it is the one that handles large-size OLED mass production. To further understand Korean panel makers" monopolizing position, it is worth mentioning fine metal mask (FMM), a critical part of the OLED RGB evaporation process – a process in OLED mass production that significantly affects the yield rate.
Prior to 2018, Samsung Display and DNP"s monopolistic supply contract prevented other panel fabs from acquiring quality FMM products as DNP bonded with Hitachi Metal, the "only" FMM material provider choice for OLED makers. After the contract expired, panel makers like BOE could purchase FFM from DNP for their OLED R&D and mass production. Except for FFM materials, vacuum evaporation equipment is dominated by Canon Tokki, a Japanese company. Its role in the OLED industry resembles that of ASML in the integrated circuit space. Canon Tokki"s annual production of vacuum evaporation equipment is fewer than ten and thereby limits the total production of OLED panels that rely on evaporation technology.
The shortage of equipment and scarcity of materials inspired panel fabs to explore substitute technology; they discovered that inkjet printing has the potential to be the thing to replace evaporation. Plus, evaporation could be applied to QLED panels as quantum dots are difficult to be vaporized. Inkjet printing prints materials (liquefied organic gas or quantum dots) to substrates, saving materials and breaking free from FMM"s size restriction. With the new tech, large-size OLED panels can theoretically be recognized with improved yield rate and cost-efficiency. However, the tech is at an early stage when inkjet printing precision could not meet panel manufacturers" requirements.
Display and LGD are using evaporation on their OLED products. To summarize, OLED currently adopts evaporation and QLED must go with inkjet printing, but evaporation is a more mature tech. Technology adoption will determine a different track for the company to pursue. With inkjet printing technology, players are at a similar starting point, which is a chance for all to run to the front – so it is for Chinese panel fabs. Certainly, panel production involves more technologies (like flexible panels) than evaporation or inkjet printing and only mastering all required technologies can help a company to compete at the same level.
Presently, Chinese panel fabs are investing heavily in OLED production while betting on QLED. BOE has four Gen 6 OLED product lines, four Gen 8.5 and one Gen 10.5 LCD lines; China Star, controlled by the major appliance titan TCL, has invested two Gen 6 OLED fabs and four large-size LCD product lines.
Remembering the last "regime change" that occurred in 2005 when Korean fabs overtook Japanese" place in the LCD market, the new phase of panel technology changed the outlook of the industry. Now, OLED or QLED could mark the perfect time for us to expect landscape change.
After Samsung Display and LGD ceding from LCD TV productions, the vacant market share will be digested by BOE, China Star and other LCD makers. Indeed, OLED and QLED have the potential to take over the LCD market in the future, but the process may take more than a decade. Korean companies took ten years from panel fab"s research on OLED to mass production of small- and medium-size OLED electronics. Yet, LCD screen cell phones are still available in the market.
LCD will not disappear until OLED/QLED"s cost control can compete with it. The low- to middle-end panel market still prefers cheap LCD devices and consumers are satisfied with LCD products – thicker but cheaper. BOE has been the largest TV panel maker since 2019. As estimated by Informa, BOE and China Star will hold a duopoly on the flat panel display market.
BOE"s performance seems to have ridden on a roller coaster ride in the past several years. Large-size panel mass production like Gen 8.5 and Gen 10.5 fabs helped BOE recognize the first place in production volume. On the other side, expanded large-size panel factories and expenses of OLED product lines are costly: BOE planned to spend CNY 176.24 billion (USD 25.92 billion) – more than Tibet"s 2019 GDP CNY 169.78 billion – on Chengdu and Mianyang"s Gen 6 AMOLED lines and Hefei and Wuhan"s Gen 10.5 LCD lines.
Except for making large-size TVs, bigger panels can cut out more display screens for smaller devices like laptops and cell phones, which are more profitable than TV products. On its first-half earnings concall, BOE said that it is shifting its production focus to cell phone and laptop products as they are more profitable than TV products. TV, IT and cell phone products counted for 30%, 44% and 33% of its productions respectively and the recent rising TV price may lead to an increased portion of TV products in the short term.
Except for outdoor large screens, TV is another driver that pushes panel makers to research on how to make bigger and bigger screens. A research done by CHEARI showed that Chinese TV sales dropped by 10.6% to CNY 128.2 billion from 2018 to 2019. Large-size TV sales increased as a total but the unit price decreased; high-end products like laser TV and OLED TV saw a strong growth of 131.2% and 34.1%, respectively.
The change in TV sales responded to a lifestyle change since the 4G era: people are getting more and more used to enjoy streaming services on portable devices like tablets and smartphones. The ‘disappearing living room" is a phenomenon common for the young generation in Chinese tier-1 cities.
Millions of young white-collars support the co-leasing business in China and breed the six-billion-dollar Ziroom, a unicorn company that provides rental and real estate management services. As apartments can be leased by single rooms instead of the whole apartment, living rooms become a public area while tenants prefer to stay in their private zones – it hints that the bedroom is too small to fit in a TV.
Besides the tier-1 cities" "disappearing living rooms," the mobile Internet gives another reason to explain the declining TV sale in China. Various streaming services and high-speed networks allow people to watch programs wherever and whenever they would like to. However, the change in life does not imply TV will disappear. For families, the living room is still a place for family members to gather and have fun. The growth of high-end TV sales also tells the "living room" economy.
The demand for different products may vary as lifestyles change and panel fabs need to make on-time judgments and respond to the change. For instance, the coming Olympics is a new driving factor to boost TV sales; "smart city" projects around the world will need more screens for data visualization; people will own more screens and better screens when life quality improves. Flexible screens, cost-efficient production process, accessible materials, changing market and all these problems are indeed the next opportunity for the industry.
Shenzhen Startek Electronic Technology Co., Ltd. mainly provides their clients with the service of designing LCD panels. Their company is committed to the customization service, R&D, sale and after-sales service of LCD and TFT display products. At present, Shenzhen Startek Electronic Technology Co., Ltd. company has a team of more than 100 employees. Shenzhen Startek Electronic Technology Co., Ltd’s product are widely used in PDA, Telecommunication terminals.
Changsha Sunman Electronics Co., Ltd established in 1995, this is a company approved as high-tech enterprise by Hunan Science and Technology Bureau and a star company in Changsha High and New Technology Industrial Development Zone. They are also one of the first ten members as with their company developing steadily, they have created a reliable product quality and after-sale service, specializing in researching.
This company specialized in Mobile Phone Parts and Accessories. Guangzhou Taoyuan Electronic Technology Co., Ltd is a professional manufacturer and exporter specialized in the mobile phone accessories industry. This is located in Guangzhou, China. They have over 10 years of experience in LCD screen factory, and five years’ experience in exporting. Products cover a wide range of repair parts and accessories for Apple and other devices.
Shenzhen City Mingxinhui Technology Co., Ltd.company is engaged in the import and export business of electronic intelligent equipment, digital products, electronic components, wireless headphones, and etc. They manufacture the best quality LCD screen and offer at friendly and affordable rates.
Qingdao Miko Technology Company Ltd. implementing strict quality control. They have an independent department and testing standard for checking the safety and quality of their products. High quality is the first criterion of their purchasing team. Qingdao Miko Technology Company Ltd. is a professional LCD screen manufacturer.
SZ Xianheng Technology Co., Ltd. is an industrial LCD display solutions provider, through high-quality LCD screen products and display driver program for the display and touch control terminal device. So far their products have been widely used in medical, military, intelligent transportation, finance, security, electricity, industry and other industries.
Shenzhen U-Chance Electronic Technology Co., Ltd. was established in 2007 and is located in Shenzhen China, which have the biggest electric market in Asia. Their main business product include: Mobile phone LCD screen display, Touch screen, Flex cables, Phone parts, Phone charger and data line, Phone case and other repair parts.
Shenzhen Yunlea Electronics Co., Ltd. company is located in Shenzhen city, 5km away from Shenzhen airport. They team has nearly 10 years of experience. They pay close attention to developments in worldwide touch display field, and set up good cooperation partnership with many first-class manufacturers and raw materials suppliers.
Guangzhou Shooan Electronic Technology Co., Ltd. is a trusted manufacturer and LCD screen supplier. They strength lies in understanding the special needs of clients, to provide the most suitable products and professional technical supports. Guangzhou Shooan Electronic Technology Co., Ltd. is your one stop solution. They have over 10 years’ sales experience in the phone LCD screen.
Guangzhou Yingyi Electronic Co.,LTD is focus on developing and supplying in LCD Assembly, all flex cable, tempered glass protector, protector case, glass, usb cable, back cover and other spare parts in repairing for mobile phone. They can able export to the worldwide. They have a professional team with good after-sales service.
Truemax Electronics Co., Limited, specializes in suppling all kinds of Mobile Parts & Accessories. It is a serious company, which has gained lots of Trust, Reputation & Support from our customers all over the world. They honor customers including Distributors, Repairing Centers, Mobile Assemblers, E-bay Shop Owners, Online Sellers etc.
BOE Technology Group Co., Ltd. is the famous chinese LCD display manufacturers. It is the world’s leading semiconductor display technology, products, and services provider. Products are widely used in mobile phones, tablets, laptops, monitors, televisions, cars, digital information displays, and other display fields.
The main products of Beijing STONE technology co., LTD company are industrial electronic series, advanced series, and civil and commercial series. They focus on the development and production of china HMI LCD display manufacturers, production and sales of LCD display modules for 16 years. The company master TFT LCD technology and software system.
The company serves the consumer display market of the mobile terminal and professional display market. Its products are widely used in many fields such as smartphone, tablet computer, smart wear, car display, medical display, industrial control, aviation display, and smart home. They also provide the best product experience for customers through TIANMA and NLT brands.
Xinli optoelectronics co., LTD is a professional development, production and sales of capacitive touch, micro camera module and integrated touch module products. The quality for their products are widely recognized and trusted by many customers from the worldwide. They can provide your desirable LCD screen.
Shenzhen sanlong electronics co., LTD is a professional engaged in LCD display module, electronic components, production, design, research and development, sales as one of the high-tech enterprises. Products are widely used in mobile phones, game consoles, PDA, portable DVD, video phone, intercom doorbell, car video, industrial control medical and other fields.
TCL display technology (Huizhou) co., LTD company is committed to the r&d, production and sales of TFT-LCD display modules, it is a modern high-tech enterprise that provides a full range of product LCD module technology and manufacturing support services for TCL group member enterprises and international electronic enterprises.
Tian Yi fu electronics co., LTD has ten semi-automatic COG production lines, 1.5KK of monthly COG products, covering COG, TAB, COB and other LCD module products, TFT, CSTN and other color LCD display products. All products will be tested and make sure all work before shipment. They also offer a satisfying and excellent services.
Jiangmen yidu semiconductor co., LTD is mainly engaged in research and development, manufacturing and sales of the LCD display and LCD display module. Products are widely used in all kinds of electronic products. They manufacture outstanding and great LCD screen. You can truly trust and rely for this company. This is one of the leading LCD screen manufacturer.
The company integrates research and development, design, production, sales, and service into one. They have full capability to provide comprehensive touch and display integrated solutions for the complete machine display manufacturers of smart phones, specializing in the development and manufacture of Sensor sensors, capacitive touch screens.
What exactly is short in the market? Your iPhone’s screen is one solid unit made up of several elements that are fused together with OCA (optically clear adhesive). The exterior glass, the digitizer panel (touch sensor), the polarizer and LCD panel. The LCD panel is the key component that is in short supply. Originally Apple had 3 manufacturers to produce LCD panels (LG, Sharp and Toshiba). Apple’s authorized manufacturers have the exclusive technology to produce LCD panels. Other Chinese manufacturers can copy the glass, digitizer, polarizers, OCA, flex cables, backlights, frames and everything except for the main component of the LCD assembly.
How were we getting these parts before? A big leak in Apple’s supply chain. The iPhone 5, 5S and 5C all share most of the same raw components including the LCD panel, the only difference is the flex cable and plastic frame. Independent factories in China can produce these components and can manufacture any 5 series assembly from an LCD panel. Shown on the left is a pulse pressing machine, used to connect the flex cable to the LCD. We use one of these to repair LCDs with damaged flex cables.
So what’s happening?A few things, first Apple has cut off LG and Toshiba, making Sharp their exclusive supplier for iPhone LCD panels and implemented very tight security. Secondly, they have had Foxconn destroy stockpiles of series 5 LCD panels to reduce the parts and material leakage to factories that re-engineer them for the independent repair industry. Along with this strategy, Apple has instructed Foxconn to reduce series 6 materials leakage from their manufacturing centers. Lastly, Apple is working aggressively with US Customs to seize inbound parts.
How long is this shortage going to last? In short,we have no idea. At the time of this writing, LCD prices have been steadily rising for 6 months and replacement iPhone 6S LCDs cost twice what Apple charges for their repair service. Apple does not intend to compete with independent repair shops, instead they are squeezing the profit out of the industry. LCD refurbishing may help shops cut cost but without new LCD panels entering the system it won’t last long.
What does this mean for the independent repair community?Apple is the only repair operation that is immune. Even the Chinese LCD refurbishing plants used by the large chain repair companies are running out of LCDs. Continually rising costs may push out the big chains but with lower overhead and clever problem-solving, the owner-operated shops stand a fighting chance.
What can we do?Apple has done everything in their power to protect their repair monopoly. When there’s only one repair shop around, prices and wait time goes up and quality goes down. Apple has every incentive to eliminate the parts market. Don’t let them. Check out the Right to Repair Bill.
For more than a century, the United States and China have been partners in an occasionally graceful but often awkward cultural-political tango. In this insightful narrative, Shouhua Qi, part of a new generation of scholars whose life experiences in China and the West serve as the basis for an acute analysis of cross-cultural perceptions, weaves literary and cultural criticism together with journeys across time, politics, and popular culture. Part memoir, Qi reveals the China complex as a manifestation of the search for meaning at many levels; personal, national, and global. With the future of the U.S. and China so intertwined now more than ever before, Qi"s cogent assessment of the interpersonal foundations of the US-China relationship in the twenty-first century is a must-read.
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 directly,backlight 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.
The origins and the complex history of liquid-crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.IEEE History Center.Peter J. Wild, can be found at the Engineering and Technology History Wiki.
In 1888,Friedrich Reinitzer (1858–1927) discovered the liquid crystalline nature of cholesterol extracted from carrots (that is, two melting points and generation of colors) and published his findings at a meeting of the Vienna Chemical Society on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss des Cholesterins, Monatshefte für Chemie (Wien) 9, 421–441 (1888)).Otto Lehmann published his work "Flüssige Kristalle" (Liquid Crystals). In 1911, Charles Mauguin first experimented with liquid crystals confined between plates in thin layers.
In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.
The MOSFET (metal-oxide-semiconductor field-effect transistor) was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, and presented in 1960.Paul K. Weimer at RCA developed the thin-film transistor (TFT) in 1962.
In 1964, George H. Heilmeier, then working at the RCA laboratories on the effect discovered by Williams achieved the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier continue to work on scattering effects in liquid crystals and finally the achievement of the first operational liquid-crystal display based on what he called the George H. Heilmeier was inducted in the National Inventors Hall of FameIEEE Milestone.
In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern, England. The team at RRE supported ongoing work by George William Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals, which had correct stability and temperature properties for application in LCDs.
The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968.dynamic scattering mode (DSM) LCD that used standard discrete MOSFETs.
On December 4, 1970, the twisted nematic field effect (TN) in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.Brown, Boveri & Cie, its joint venture partner at that time, which produced TN displays for wristwatches and other applications during the 1970s for the international markets including the Japanese electronics industry, which soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. James Fergason, while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute, filed an identical patent in the United States on April 22, 1971.ILIXCO (now LXD Incorporated), produced LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption. Tetsuro Hama and Izuhiko Nishimura of Seiko received a US patent dated February 1971, for an electronic wristwatch incorporating a TN-LCD.
In 1972, the concept of the active-matrix thin-film transistor (TFT) liquid-crystal display panel was prototyped in the United States by T. Peter Brody"s team at Westinghouse, in Pittsburgh, Pennsylvania.Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display (TFT LCD).high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.active-matrix liquid-crystal display (AM LCD) in 1974, and then Brody coined the term "active matrix" in 1975.
In 1972 North American Rockwell Microelectronics Corp introduced the use of DSM LCDs for calculators for marketing by Lloyds Electronics Inc, though these required an internal light source for illumination.Sharp Corporation followed with DSM LCDs for pocket-sized calculators in 1973Seiko and its first 6-digit TN-LCD quartz wristwatch, and Casio’s ‘Casiotron’. Color LCDs based on Guest-Host interaction were invented by a team at RCA in 1968.TFT LCDs similar to the prototypes developed by a Westinghouse team in 1972 were patented in 1976 by a team at Sharp consisting of Fumiaki Funada, Masataka Matsuura, and Tomio Wada,
In 1983, researchers at Brown, Boveri & Cie (BBC) Research Center, Switzerland, invented the passive matrix-addressed LCDs. H. Amstutz et al. were listed as inventors in the corresponding patent applications filed in Switzerland on July 7, 1983, and October 28, 1983. Patents were granted in Switzerland CH 665491, Europe EP 0131216,
The first color LCD televisions were developed as handheld televisions in Japan. In 1980, Hattori Seiko"s R&D group began development on color LCD pocket televisions.Seiko Epson released the first LCD television, the Epson TV Watch, a wristwatch equipped with a small active-matrix LCD television.dot matrix TN-LCD in 1983.Citizen Watch,TFT LCD.computer monitors and LCD televisions.3LCD projection technology in the 1980s, and licensed it for use in projectors in 1988.compact, full-color LCD projector.
In 1990, under different titles, inventors conceived electro optical effects as alternatives to twisted nematic field effect LCDs (TN- and STN- LCDs). One approach was to use interdigital electrodes on one glass substrate only to produce an electric field essentially parallel to the glass substrates.Germany by Guenter Baur et al. and patented in various countries.Hitachi work out various practical details of the IPS technology to interconnect the thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.
Hitachi also improved the viewing angle dependence further by optimizing the shape of the electrodes (Super IPS). NEC and Hitachi become early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and In Plane Switching subsequently remain the dominant LCD designs through 2006.South Korea and Taiwan,
In 2007 the image quality of LCD televisions surpassed the image quality of cathode-ray-tube-based (CRT) TVs.LCD TVs were projected to account 50% of the 200 million TVs to be shipped globally in 2006, according to Displaybank.Toshiba announced 2560 × 1600 pixels on a 6.1-inch (155 mm) LCD panel, suitable for use in a tablet computer,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 called Full-area Local Area Dimming (FLAD)
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.
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.
Twisted nematic displays contain liquid crystals that twist and untwist at varying degrees to allow light to pass through. When no voltage is applied to a TN liquid crystal cell, polarized light passes through the 90-degrees twisted LC layer. In proportion to the voltage applied, the liquid crystals untwist changing the polarization and blocking the light"s path. By properly adjusting the level of the voltage almost any gray level or transmission can be achieved.
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. 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 2009, 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. Currently Panasonic is using an enhanced version eIPS for their large size LCD-TV products as well as Hewlett-Packard in its WebOS based TouchPad tablet and their Chromebook 11.
In 2015 LG Display announced the implementation of a new technology called M+ which is the addition of white subpixel along with the regular RGB dots in their IPS panel technology.
Most of the new M+ technology was employed on 4K TV sets which led to a controversy after tests showed that the addition of a white sub pixel replacing the traditional RGB structure would reduce the resolution by around 25%. This means that a 4K TV cannot display the full UHD TV standard. The media and internet users later called this "RGBW" TVs because of the white sub pixel. Although LG Display has developed this technology for use in notebook display, outdoor and smartphones, it became more popular in the TV market because the announced 4K UHD resolution but still being incapable of achieving true UHD resolution defined by the CTA as 3840x2160 active pixels with 8-bit color. This negatively impacts the rendering of text, making it a bit fuzzier, which is especially noticeable when a TV is used as a PC monitor.
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 technolog