Thin-film-transistor liquid-crystal display – Wikipedia

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LG IPS technology development
Name Nickname Year Remarks
Horizontal IPS H-IPS 2007 Improves[quantify] contrast ratio by twisting electrode plane layout. Also introduces an optional Advanced True White polarizing film from NEC, to make white look more natural[quantify]. This is used in professional/photography LCDs.[citation needed]
Enhanced IPS E-IPS 2009 Wider[quantify] aperture for light transmission, enabling the use of lower-power, cheaper backlights. Improves[quantify] diagonal viewing angle and further reduce response time to 5ms.[citation needed]
Professional IPS P-IPS 2010 Offer 1.07 billion colors (10-bit color depth).[citation needed] More possible orientations per sub-pixel (1024 as opposed to 256) and produces a better[quantify] true color depth.
Advanced High Performance IPS AH-IPS 2011 Improved color accuracy, increased resolution and PPI, and greater light transmission for lower power consumption.[20]

Advanced fringe field switching (AFFS)[edit]

This is an LCD technology derived from the IPS by Boe-Hydis of Korea. Known as fringe field switching (FFS) until 2003,[21] advanced fringe field switching is a technology similar to IPS or S-IPS offering superior performance and color gamut with high luminosity. Color shift and deviation caused by light leakage is corrected by optimizing the white gamut, which also enhances white/grey reproduction. AFFS is developed by Hydis Technologies Co., Ltd, Korea (formally Hyundai Electronics, LCD Task Force).[22]

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan’s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

Hydis introduced AFFS+ which improved outdoor readability in 2007.[citation needed]

Multi-domain vertical alignment (MVA)[edit]

It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction.[citation needed] Modern MVA panels can offer wide viewing angles (second only to S-IPS technology), good black depth, good color reproduction and depth, and fast response times due to the use of RTC (Response Time Compensation) technologies.[citation needed] When MVA panels are viewed off-perpendicular, colors will shift, but much less than for TN panels.[citation needed]

There are several “next-generation” technologies based on MVA, including AU Optronics’ P-MVA and AMVA, as well as Chi Mei Optoelectronics’ S-MVA.

Patterned vertical alignment (PVA)[edit]

Less expensive PVA panels often use dithering and FRC, whereas super-PVA (S-PVA) panels all use at least 8 bits per color component and do not use color simulation methods.[citation needed]S-PVA also largely eliminated off-angle glowing of solid blacks and reduced the off-angle gamma shift. Some high-end Sony BRAVIA LCD TVs offer 10-bit and xvYCC color support, for example, the Bravia X4500 series. S-PVA also offers fast response times using modern RTC technologies.[citation needed]

Advanced super view (ASV)[edit]

Advanced super view, also called axially symmetric vertical alignment was developed by Sharp.[23] It is a VA mode where liquid crystal molecules orient perpendicular to the substrates in the off state. The bottom sub-pixel has continuously covered electrodes, while the upper one has a smaller area electrode in the center of the subpixel.

When the field is on, the liquid crystal molecules start to tilt towards the center of the sub-pixels because of the electric field; as a result, a continuous pinwheel alignment (CPA) is formed; the azimuthal angle rotates 360 degrees continuously resulting in an excellent viewing angle. The ASV mode is also called CPA mode.[24]

Plane line switching (PLS)[edit]

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels and touts improved viewing angles and image quality, increased brightness and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.[25]

TFT dual-transistor pixel (DTP) or cell technology[edit]

Patent TFT Store Electronic Systems

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Display industry[edit]

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

LCD glass panel suppliers
Panel type Company Remarks major TV makers
IPS-Pro Panasonic Solely for LCD TV markets and known as IPS Alpha Technology Ltd.[26] Panasonic, Hitachi, Toshiba
H-IPS & P-IPS LG Display They also produce other type of TFT panels such as TN for OEM markets such as mobile, monitor, automotive, portable AV and industrial panels. LG, Philips, BenQ
S-IPS Hannstar
Chunghwa Picture Tubes, Ltd.
A-MVA AU Optronics
A-HVA AU Optronics
S-MVA Chi Mei Optoelectronics
AAS InnoLux Corporation
S-PVA S-LCD (Samsung/Sony joint venture) Samsung, Sony
AFFS Samsung For small and medium size special projects.
ASV Sharp Corporation LCD TV and mobile markets Sharp, Sony
MVA Sharp Corporation Solely for LED LCD TV markets Sharp
HVA CSOT HVA and AMOLED TCL[27]

Electrical interface[edit]

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15″) TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.[citation needed]

Backlight intensity is usually controlled by varying a few volts DC, or generating a PWM signal, or adjusting a potentiometer or simply fixed. This in turn controls a high-voltage (1.3 kV) DC-AC inverter or a matrix of LEDs. The method to control the intensity of LED is to pulse them with PWM which can be source of harmonic flicker.[citation needed]

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).[citation needed]

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn’t match the display panel resolution.

Liquid crystals are constantly subjected to toxicity and eco-toxicity testing for any hazard potential. The result is that:

  • wastewater from manufacturing is acutely toxic to aquatic life,[28]
  • but may have an irritant, corrosive or sensitizing effect in rare cases. Any effects can be avoided by using a limited concentration in mixtures,
  • are not mutagenic – neither in bacteria (Ames test) nor in mammalian cells (mouse lymphoma assay or chromosome aberration test),
  • are not suspected of being carcinogenic,[29]
  • are hazardous to aquatic organisms (bacteria, algae, daphnia, fish),[28]
  • do not possess any significant bioaccumulation potential,
  • are not easily biodegradable.[29]

The statements are applicable to Merck KGaA as well as its competitors JNC Corporation (formerly Chisso Corporation) and DIC (formerly Dainippon Ink & Chemicals). All three manufacturers have agreed not to introduce any acutely toxic or mutagenic liquid crystals to the market. They cover more than 90 percent of the global liquid crystal market. The remaining market share of liquid crystals, produced primarily in China, consists of older, patent-free substances from the three leading world producers and have already been tested for toxicity by them. As a result, they can also be considered non-toxic.

The complete report is available from Merck KGaA online.[29]

The CCFL backlights used in many LCD monitors contain mercury, which is toxic.

See also[edit]

References[edit]

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  4. ^ a b Kuo, Yue (1 January 2013). “Thin Film Transistor Technology—Past, Present, and Future” (PDF). The Electrochemical Society Interface. 22 (1): 55–61. Bibcode:2013ECSIn..22a..55K. doi:10.1149/2.F06131if. ISSN 1064-8208.
  5. ^ Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). “A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel”. IEEE Transactions on Electron Devices. 20 (11): 995–1001. Bibcode:1973ITED…20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.
  6. ^ Brotherton, S. D. (2013). Introduction to Thin Film Transistors: Physics and Technology of TFTs. Springer Science & Business Media. p. 74. ISBN 9783319000022.
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  8. ^ Kimizuka, Noboru; Yamazaki, Shunpei (2016). Physics and Technology of Crystalline Oxide Semiconductor CAAC-IGZO: Fundamentals. John Wiley & Sons. p. 217. ISBN 9781119247401.
  9. ^ Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 322–324. ISBN 978-3540342588.
  10. ^ Richard Ahrons (2012). “Industrial Research in Microcircuitry at RCA: The Early Years, 1953–1963”. 12 (1). IEEE Annals of the History of Computing: 60–73.
  11. ^ “TFT LCD – Fabricating TFT LCD”. Plasma.com. Archived from the original on 2013-05-02. Retrieved 2013-07-21.
  12. ^ “TFT LCD – Electronic Aspects of LCD TVs and LCD Monitors”. Plasma.com. Archived from the original on 2013-08-23. Retrieved 2013-07-21.
  13. ^ Oleg Artamonov (2004-10-26). “X-bit’s Guide: Contemporary LCD Monitor Parameters and Characteristics (page 11)”. Xbitlabs.com. Archived from the original on 2009-05-19. Retrieved 2009-08-05.
  14. ^ Marek Matuszczyk, Liquid crystals in displays Archived 2004-12-23 at the Wayback Machine. Chalmers University Sweden, c. 2000.
  15. ^ “TN Film, MVA, PVA and IPS – Panel Technologies”. TFT Central. Retrieved 9 September 2009.
  16. ^ “IPS or TN panel?”. eSport Source. Retrieved 23 May 2016.
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  18. ^ IPS-Pro (Evolving IPS technology) Archived 2010-03-29 at the Wayback Machine
  19. ^ “Archived copy” (PDF). Archived from the original (PDF) on 2012-11-15. Retrieved 2013-11-24.{{cite web}}: CS1 maint: archived copy as title (link)
  20. ^ tech2 News Staff. “LG Announces Super High Resolution AH-IPS Displays”. Tech2.in.com. Archived from the original on 2013-06-06. Retrieved 2013-07-21.
  21. ^ “AFFS & AFFS+”. Technology. Vertex LCD. Archived from the original on 2016-05-18. Retrieved 2010-08-12.
  22. ^ K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). “A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology”. SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159.
  23. ^ “Sharp Advanced Super View (ASV) – Sharp”. www.sharpsma.com. Retrieved 2019-06-12.
  24. ^ The World of Liquid Crystal Displays from personal.kent.edu/%7Emgu
  25. ^ “Samsung SyncMaster SA850: World’s First Monitor on PLS Matrix”. X-bit labs. 2011-05-30. Retrieved 2013-07-21.
  26. ^ IPS Alpha Technology Ltd Archived 2007-12-24 at archive.today
  27. ^ “About Us”. www.szcsot.com. Retrieved 2019-06-05.
  28. ^ a b Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). “Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa”. Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.
  29. ^ a b c “Display solutions | Merck KGaA, Darmstadt, Germany”. www.merck-performance-materials.com. Retrieved 2018-02-17.

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