Liquid Crystal Display:

Introduction:

A flat-panel display or other electronically controlled optical device that makes use of polarizers and the light-modulating capabilities of liquid crystals is known as a liquid-crystal display (LCD). Liquid crystals don't emit light directly; instead, they create images in either color or monochrome utilizing a backlight or reflector. There are LCDs that can show random images (like on a general-purpose computer display) or fixed displays with little information that can be seen or hidden. Examples of devices with these displays include those that use predefined words, digits, and seven-segment displays, such as those seen in digital clocks.They both make use of the same fundamental technology, although some displays have larger components, whereas others employ a grid of tiny pixels to create random images. Depending on the polarizer configuration, LCDs can be switched between being normally on (positive) and off (negative). A character negative LCD will have a black backdrop with letters that are the same color as the backlight, while a character positive LCD will have black writing on a background that is the opposite of the color of the illumination. Blue LCDs have optical filters applied to the white to give them their distinctive appearance.

 

Liquid Crystal Display

There are many different applications for LCDs, such as LCD televisions, computer monitors, instrument panels, cockpit displays for airplanes, and interior and outdoor signs. LCD projectors and portable consumer electronics like digital cameras, watches, clocks, calculators, and mobile phones, including smartphones, frequently include small LCD screens. Consumer electronics items like DVD players, gaming consoles, and clocks all employ LCD screens. In almost all applications, LCD screens have taken the place of heavy, clunky cathode-ray tube (CRT) displays.

Compared to CRT and plasma displays, LCD panels come in a larger range of screen sizes, with sizes ranging from tiny digital watches to extremely large television receivers. OLEDs, which are easily formed into various shapes and have a lower response time, wider color gamut, virtually infinite color contrast, and viewing angles, as well as lower weight for a given display size and a slimmer profile (because OLEDs use a single glass or plastic panel while LCDs use two glass panels; the thickness of the panels increases with size but the increase is more noticeable on LCDs) and possibly lower power consumption, are gradually replacing LCDs (as the display is only "on" where needed and there is no backlight).However, because OLEDs require extremely expensive electroluminescent materials or phosphors, they are more expensive for a given display size. OLEDs experience screen burn-in due to the use of phosphors as well, and there is presently no means to recycle OLED displays. In contrast, LCD panels can be recycled, albeit the technology needed to do so is not yet widely available.

 

Liquid Crystal Display

Due to the lack of phosphors in LCD screens, they hardly ever experience image burn-in when a static image is shown on a screen for an extended period of time, such as the table frame for an airline flight schedule on an indoor sign. However, image persistence can happen with LCDs. Compared to a CRT, an LCD panel uses less energy and can be disposed of more safely. It may be utilized in battery-powered electronic devices more effectively than a CRT because of its minimal electrical power consumption. By 2008, annual sales of LCD-screen televisions had surpassed those of CRT models globally, rendering the CRT obsolete for the majority of uses.

 

History:

In Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry, Joseph A. Castellano narrates the beginnings and complicated history of liquid-crystal displays from the insider's viewpoint during the early years. Another article by Hiroshi Kawamoto, which is available at the IEEE History Center, examines the beginnings and development of LCD from a different angle up to 1991. The Engineering and Technology History Wiki has an article by Peter J. Wild that details the contributions of Switzerland to LCD advancements.

 

The liquid crystalline nature of cholesterol extracted from carrots (two melting points and color generation) was discovered in 1888 by Friedrich Reinitzer (1858–1927), who presented 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 "Flüssige Kristalle" in 1904. (Liquid Crystals). Charles Mauguin conducted the first experiments with thin layers of liquid crystals contained between plates in 1911.

 

Georges Friedel described the composition and characteristics of liquid crystals in 1922 and divided them into three groups (nematics, smectics and cholesterics). The electrically switched light valve, also known as the Frederiksz transition, which is the fundamental component of all LCD technology, was created by Vsevolod Frederiks in 1927.The "Liquid Crystal Light Valve," the first practical implementation of the technique, was patented by the Marconi Wireless Telegraph firm in 1936. Dr. George W. Gray published the first significant English-language work, Molecular Structure and Properties of Liquid Crystals, in 1962. By applying a voltage to a small layer of liquid crystal material, Richard Williams of RCA discovered in 1962 that liquid crystals exhibited some intriguing electro-optic properties. This led him to develop an electro-optical effect. This effect is predicated on the formation of what are now known as "Williams domains" within the liquid crystal via an electro-hydrodynamic instability.

 

Mohamed M. Atalla and Dawon Kahng at Bell Labs created the MOSFET (metal-oxide-semiconductor field-effect transistor) in 1959, and it was first demonstrated in 1960. Paul K. Weimer at RCA created the thin-film transistor (TFT) in 1962, building on their work with MOSFETs. It was a different kind of MOSFET from the typical bulk MOSFET.

 

By using field-induced dichroic dye realignment in a homeotropically orientated liquid crystal, George H. Heilmeier, then working at the RCA laboratories, was able to achieve the phenomenon Williams had found in 1964. Heilmeier's work on scattering effects in liquid crystals led to the creation of the first operational liquid-crystal display based on what he named the dynamic scattering mode when practical issues with this novel electro-optical phenomenon forced him to continue (DSM).A DSM display's originally clear transparent liquid crystal layer transforms into a milky turbid state when a voltage is applied. Although DSM displays could be used in transmissive and reflective modes, they needed a significant current to operate. The National Inventors Hall of Fame inducted George H. Heilmeier, who is credited with creating LCDs. An IEEE Milestone is Heilmeier's work.

 

Liquid Crystal Display

The UK's Royal Radar Establishment in Malvern, England, started working on liquid crystals in the late 1960s. The RRE team helped George William Gray and his colleagues at the University of Hull continue their research, which led to the discovery of cyanobiphenyl liquid crystals with the ideal stability and temperature characteristics for use in LCDs.

 

In 1968, Bernard Lechner of RCA Laboratories came up with the concept of a TFT-based liquid-crystal display (LCD). In 1968, Lechner, F.J. Marlowe, E.O. Nester, and J. Tults constructed an 18x2 matrix dynamic scattering mode (DSM) LCD that used conventional discrete MOSFETs to show the theory.

 

Hoffmann-LaRoche submitted a patent application in Switzerland on December 4, 1970, for the twisted nematic field effect (TNFE) in liquid crystals (Swiss patent No. 532 261) with Martin Schadt and Wolfgang Helfrich, who were then employed by the Central Research Laboratories, listed as the inventors. Hoffmann-La Roche granted a license for the invention to Swiss manufacturer Brown, Boveri & Cie, its joint venture partner at the time. Brown, Boveri & Cie 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 watches with TN-LCDs as well as a variety of other products. On April 22, 1971, James Fergason submitted a similar patent in the US while working at the Kent State University Liquid Crystal Institute alongside Sardari Arora and Alfred Saupe.ILIXCO (now LXD Incorporated), a Fergason business, began manufacturing LCDs based on the TN-effect in 1971. These LCDs quickly replaced the subpar DSM versions thanks to advancements in lower operating voltages and lower power usage. A US patent was granted to Tetsuro Hama and Izuhiko Nishimura of Seiko in February 1971 for an electronic wristwatch utilizing a TN-LCD. The Gruen Teletime, a watch with a four digit display, was the first TN-LCD wristwatch to hit the market in 1972.

 

T. Peter Brody's group at Westinghouse in Pittsburgh, Pennsylvania, prototyped the active-matrix thin-film transistor (TFT) liquid-crystal display panel idea in the United States in 1972. Brody, J. A. Asars, and G. D. Dixon showed the first thin-film transistor liquid crystal display at Westinghouse Research Laboratories in 1973. (TFT LCD). As of 2013, TFT-based active matrix displays are used in all contemporary high-resolution and high-quality electronic visual display systems. Brody initially used the phrase "active matrix" in 1975 after he and Fang-Chen Luo developed the first flat active-matrix liquid-crystal display (AM LCD) in 1974.

 

Although these needed an internal light source for lighting, North American Rockwell Microelectronics Corp announced the use of DSM LCDs for calculators in 1972 for commercialization by Lloyds Electronics Inc. Following suit, Sharp Corporation began mass-producing TN LCDs for watches in 1975 and DSM LCDs for pocket-sized calculators in 1973. Other Japanese manufacturers quickly established themselves as market leaders in the wristwatch industry, including Seiko with its first 6-digit TN-LCD quartz wristwatch and Casio with the "Casiotron." A team at RCA created color LCDs based on guest-host interaction in 1968.The Japanese company Sharp Corporation created a specific kind of such a color LCD in the 1970s. They were awarded patents for their creations, including one by Shinji Kato and Takaaki Miyazaki in May 1975, which was further enhanced by Fumiaki Funada and Masataka Matsuura in December 1975. Fumiaki Funada, Masataka Matsuura, and Tomio Wada of the Sharp company patented TFT LCDs in 1976, while Kohei Kishi, Hirosaku Nonomura, Keiichiro Shimizu, and Tomio Wada of the Sharp company improved them in 1977. These TFT LCDs were identical to the prototypes created by a Westinghouse team in 1972. However, due to issues with the materials used to make the TFTs, these TFT-LCDs were not yet prepared for usage in products.

 

The super-twisted nematic (STN) structure for passive matrix-addressed LCDs was created in 1983 by scientists at the Brown, Boveri & Cie (BBC) Research Center in Switzerland. The related patent applications submitted in Switzerland on July 7 and October 28 cited H. Amstutz et al. as inventors. Switzerland CH 665491, Europe EP 0131216, the United States Patent 4,634,229, and many other nations have all given patents. In 1980, Dutch Philips and Brown Boveri established Videlec, a 50/50 joint venture. Philips possessed the necessary expertise to create integrated circuits for the control of huge LCD displays.Additionally, Philips hoped to deploy LCDs in new product generations of telephones, video equipment, and hi-fi systems and had stronger access to markets for electronic components. Theodorus Welzen and Adrianus de Vaan, two Philips researchers, created a video speed-drive method in 1984 to address the short response time of STN-LCDs and enable high-resolution, high-quality, and fluid-moving video pictures on STN-LCDs. The problem of driving high-resolution STN-LCDs with low-voltage (CMOS-based) drive electronics was resolved by Philips inventors Theodorus Welzen and Adrianus de Vaan in 1985, opening the door for the use of high-quality (high resolution and video speed) LCD panels in battery-operated portable products like notebook computers and mobile phones.In 1985, the Swiss company Videlec AG was fully bought by Philips. Following that, Philips relocated the Videlec manufacturing facilities to the Netherlands. Years later, in high-volume production for the burgeoning mobile phone market, Philips successfully produced and marketed whole modules (comprising the LCD screen, microphone, speakers, etc.).

 

Japan is where the first handheld color LCD televisions were created. The R&D department of Hattori Seiko started working on color LCD pocket televisions in 1980. The Epson TV Watch, a wristwatch featuring a tiny active-matrix LCD television, was the first LCD television to be made by Seiko Epson and was released in 1982. In 1983, Sharp Corporation unveiled the dot matrix TN-LCD. Epson introduced the ET-10, the first portable LCD television with full color, in 1984.

 

The Citizen Pocket TV, a 2.7-inch color LCD TV featuring the first commercial TFT LCD, was unveiled by Citizen Watch in the same year. A 14-inch, active-matrix, full-color, full-motion TFT-LCD was unveiled by Sharp in 1988. As a result, Japan established a large-size LCD industry that produced TFT computer monitors and LCD televisions, among other large-size LCD products. The 3LCD projection technology was created by Epson in the 1980s, and it was licensed for use in projectors in 1988. The first portable, full-color LCD projector was Epson's VPJ-700, which debuted in January 1989.

 

As an alternative to LCDs with twisted nematic fields, inventors proposed electro optical effects in 1990 under several names (TN- and STN- LCDs). One method was to create an electric field that was essentially parallel to the glass substrates by using interdigital electrodes on just one glass substrate. Additional work was required in order to fully utilize the capabilities of this In Plane Switching (IPS) technology. Following careful examination, Guenter Baur and others filed details of favorable embodiments in Germany and obtained patents in several nations.The inventors' former employer, the Fraunhofer Institute ISE in Freiburg, has granted these patents to LC ingredient supplier Merck KGaA in Darmstadt. Soon after, in 1992, engineers at Hitachi iron out a number of the IPS technology's practical features to connect the thin-film transistor array as a matrix and prevent undesired stray fields between pixels.

 

Hitachi further enhanced the viewing angle dependence by enhancing the electrode's shape (Super IPS). Early producers of active-matrix addressing LCDs based on IPS technology were NEC and Hitachi. The implementation of large-screen LCDs with acceptable visual performance for flat-panel computer displays and television screens has reached a significant milestone. Samsung created the optical patterning method that permits multi-domain LCD in 1996.Therefore, through 2006, multi-domain and in-plane switching LCD systems predominated. The LCD industry started moving away from Japan in the late 1990s and toward South Korea and Taiwan, which then moved to China.

 

The image quality of LCD televisions surpassed that of CRT TVs in 2007 as opposed to CRT-based TVs. In terms of global sales, LCD televisions initially exceeded CRT TVs in the fourth quarter of 2007. According to Displaybank, of the 200 million TVs expected to be supplied globally in 2006, 50% were expected to be LCD TVs. Toshiba unveiled 2560 1600 pixels on a 6.1-inch (155 mm) LCD panel in October 2011 that was ideal for usage in a tablet computer, particularly for the display of Chinese characters. TGP (Tracking Gate-line in Pixel), which shifts the driving circuitry from the boundaries of the display to in between the pixels, was also widely adopted in the 2010s, enabling thin bezels.Although LCDs can be made transparent and flexible, they lack the ability to emit light without a backlight, unlike other transparent and flexible technologies like OLED and microLED. The viewing angles of LCDs can be increased using special films.

 

Panasonic created IPS LCDs with a contrast ratio of 1,000,000:1 in 2016, making them competitive with OLEDs. Later, this technique was used to create dual layer, dual panel, or LMCL (Light Modulating Cell Layer) LCDs, which are now widely available. The technology replaces one liquid crystal layer with two and can be combined with quantum dot sheets, a mini-LED backlight, and other components.