acronym abbreviation for tft lcd touch screen manufacturer

TFT-based displays have a transistor for each pixel on the screen. This allows the electrical current that illuminates the display to be turned on and off at a faster rate, which makes the display brighter and shows motion smoother. LCDs that use TFT technology are called "active-matrix" displays, which are higher-quality than older "passive-matrix" displays. TFT technology provides the best resolution of all the flat display technologies, but it is also expensive than monochrome lcd. So TFTs are used in high-quality LCD displays, if you see a LCD monitor at your local computer market, it should be an active tft lcd display, Basically, it is a high-quality tft lcd monitor.

Passive-matrix display. A passive-matrix display is anLCD screen display that contains a series of wires that cross each other. See the dual scan display for a full definition on this term.

What is an Active-matrix Display (TFT)? Alternatively referred to as TFT ( thin-film transistor) and AMLCD ( active-matrix LCD ), an active-matrix display is an LCD ( liquid crystal display) introduced with the IBM ThinkPad in 1992.

It uses a matrix of thin film transistors(TFTs) and capacitors to control the image produced by thedisplay. The brightness of each pixel is controlled by modifying the electrical charge of the corresponding capacitors.

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

The transmittance of a pixel of an LCD panel typically does not change linearly with the applied voltage,sRGB standard for computer monitors requires a specific nonlinear dependence of the amount of emitted light as a function of the RGB value.

It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction.Response Time Compensation) technologies.

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.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.

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.

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.

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:

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.

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).

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.

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.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

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. S2CID 129569963.

Information technology company Teleste Corporation revealed on Thursday that its subsidiary Teleste Information Solutions (former Mitron) entered into a frame agreement with passenger and logistics company Deutsche Bahn for TFT-LCD displays.

It has so far been difficult for AMOLED panels to replace TFT-LCD units for use in smartphones because smartphone vendors except Samsung Electronics are worried about Samsung Display dominating global supply of AMOLED panels.

According to the report, the tech giant may continue using a-Si TFT-LCD for its computers until the end of the first quarter before making the shift to IGZO.

This report finds that shipment volume of the Taiwanese small and medium size TFT-LCD panels continued to grow in the third quarter of 2015, arriving at 303.6 million units, up 6.6% sequentially.

In 2013, Hsieh said, the global production capacity of large-sized TFT-LCD panels will decrease about 8%, while shipments of new-size panels (such as 39-, 50-, 58-, 60-, and 65-inch) by AUO and CMI are expected to account for more than 20% of the overall shipments.

As you might already be aware, there’s a large variety of versatile digital display types on the market, all of which are specifically designed to perform certain functions and are suitable for numerous commercial, industrial, and personal uses. The type of digital display you choose for your company or organization depends largely on the requirements of your industry, customer-base, employees, and business practices. Unfortunately, if you happen to be technologically challenged and don’t know much about digital displays and monitors, it can be difficult to determine which features and functions would work best within your professional environment. If you have trouble deciphering the pros and cons of using TFT vs. IPS displays, here’s a little guide to help make your decision easier.

TFT stands for thin-film-transistor, which is a variant of liquid crystal display (LCD). TFTs are categorized as active matrix LCDs, which means that they can simultaneously retain certain pixels on a screen while also addressing other pixels using minimal amounts of energy. This is because TFTs consist of transistors and capacitors that respectively work to conserve as much energy as possible while still remaining in operation and rendering optimal results. TFT display technologies offer the following features, some of which are engineered to enhance overall user experience.

The bright LED backlights that are featured in TFT displays are most often used for mobile screens. These backlights offer a great deal of adaptability and can be adjusted according to the visual preferences of the user. In some cases, certain mobile devices can be set up to automatically adjust the brightness level of the screen depending on the natural or artificial lighting in any given location. This is a very handy feature for people who have difficulty learning how to adjust the settings on a device or monitor and makes for easier sunlight readability.

One of the major drawbacks of using a TFT LCD instead of an IPS is that the former doesn’t offer the same level of visibility as the latter. To get the full effect of the graphics on a TFT screen, you have to be seated right in front of the screen at all times. If you’re just using the monitor for regular web browsing, for office work, to read and answer emails, or for other everyday uses, then a TFT display will suit your needs just fine. But, if you’re using it to conduct business that requires the highest level of colour and graphic accuracy, such as completing military or naval tasks, then your best bet is to opt for an IPS screen instead.

Nonetheless, most TFT displays are still fully capable of delivering reasonably sharp images that are ideal for everyday purposes and they also have relatively short response times from your keyboard or mouse to your screen. This is because the pixel aspect ration is much narrower than its IPS counterpart and therefore, the colours aren’t as widely spread out and are formatted to fit onto the screen. Primary colours—red, yellow, and blue—are used as the basis for creating brightness and different shades, which is why there’s such a strong contrast between different aspects of every image. Computer monitors, modern-day HD TV screens, laptop monitors, mobile devices, and even tablets all utilize this technology.

IPS (in-plane-switching) technology is almost like an improvement on the traditional TFT display module in the sense that it has the same basic structure, but with slightly more enhanced features and more widespread usability. IPS LCD monitors consist of the following high-end features.

IPS screens have the capability to recognize movements and commands much faster than the traditional TFT LCD displays and as a result, their response times are infinitely faster. Of course, the human eye doesn’t notice the difference on separate occasions, but when witnessing side-by-side demonstrations, the difference is clear.

Wide-set screen configurations allow for much wider and versatile viewing angles as well. This is probably one of the most notable and bankable differences between TFT and IPS displays. With IPS displays, you can view the same image from a large variety of different angles without causing grayscale, blurriness, halo effects, or obstructing your user experience in any way. This makes IPS the perfect display option for people who rely on true-to-form and sharp colour and image contrasts in their work or daily lives.

IPS displays are designed to have higher transmittance frequencies than their TFT counterparts within a shorter period of time (precisely 1 millisecond vs. 25 milliseconds). This speed increase might seem minute or indecipherable to the naked eye, but it actually makes a huge difference in side-by-side demonstrations and observations, especially if your work depends largely on high-speed information sharing with minimal or no lagging.

Just like TFT displays, IPS displays also use primary colours to produce different shades through their pixels. The main difference in this regard is the placement of the pixels and how they interact with electrodes. In TFT displays, the pixels run perpendicular to one another when they’re activated by electrodes, which creates a pretty sharp image, but not quite as pristine or crisp as what IPS displays can achieve. IPS display technologies employ a different configuration in the sense that pixels are placed parallel to one another to reflect more light and result in a sharper, clearer, brighter, and more vibrant image. The wide-set screen also establishes a wider aspect ratio, which strengthens visibility and creates a more realistic and lasting effect.

When it comes to deciphering the differences between TFT vs. IPS display technologies and deciding which option is best for you and your business, the experts at Nauticomp Inc. can help. Not only do we offer a wide variety of computer displays, monitors, and screen types, but we also have the many years of experience in the technology industry to back up our recommendations and our knowledge. Our top-of-the-line displays and monitors are customized to suit the professional and personal needs of our clients who work across a vast array of industries. For more information on our high-end displays and monitors, please contact us.

TFT is a Thin Film Transistor, TFT refers to each LCD liquid crystal display pixels that are driven by integration in the behind of the Thin Film Transistor. Therefore, the TFT-type display has the advantages of high responsiveness, high brightness, and high contrast, and its display effect is close to that of CRT display, TFT-LCD is one of the most liquid crystal displays.TFT display is also a kind of active-matrix liquid crystal display equipment. TFT-LCD is one of the best LCD color displays, TFT-LCD has the advantages of fine and vivid image, lightweight, low power consumption, and good environmental protection performance, widely used in TV, laptop, mobile phone, monitor, medical beauty, and other equipment.

Unlike TN, TFT displays are “backlit” – the imaginary light path is not from top to bottom, as in TN, but from bottom to top. In this way, a special light tube is set on the back of the liquid crystal, and the light source shines upward through the lower polarizer. Since the upper and lower interlayer electrodes are changed into FET electrodes and common electrodes, the performance of liquid crystal molecules will also change when the FET electrode is switched on. The display purpose can be achieved through shading and light transmission, and the response time is greatly improved to about 80ms.TFT is commonly known as “true color” because it has higher contrast and richer colors than TN-LCD, and the screen updates faster.

The main feature of TFT-LCD, as opposed to TN, is one semiconductor switch per pixel. Because each pixel can be directly controlled by point pulses. Therefore, each node is relatively independent and can be controlled continuously. Such a design method not only improves the response speed of the display screen but also can accurately control the display grayscale, which is why TFT color is more realistic than DSTN.

The TFT panel is cut from a larger substrate. LCD products also have a large array of transistors to control the three primary colors, and current manufacturing technology is difficult to ensure that tens or even hundreds of millions of transistors on a large substrate are without a single problem. If there is a problem with one of the transistors, then the corresponding color of the corresponding point of the transistor will go wrong (only a certain fixed color can be displayed), and this point is commonly called “bad point”. The probability of bad spots is not fixed in position, so a substrate is likely to be wasted a lot. Generally, LCD requires that the bad point is less than 5, and some large manufacturers have narrowed the standard to 3, or even 0, which will reduce the yield rate. Some smaller manufacturers expand the bad points, which naturally reduces costs and quality, which is one reason why some manufacturers have been able to slash prices.

Although there are many manufacturers capable of producing LCDs, there are only a handful of manufacturers capable of producing TFT panels.ACER, as a well-known enterprise in the IT industry, is quite powerful. Although IT does not have the ability to produce TFT panels by itself,

The display sets the electron, the communication and the information processing technology in one body, is considered as the electron industry after the 20th-century microelectronics, the computer another important development opportunity.

The principle of field emission flat display is similar to that of CRT, which only has one to three electron guns and up to six. The field emission display adopts an electron gun array (electron emission micro tip array, such as diamond film tip cone), and the display with a resolution of VGA (640×480×3) needs 921,600 electron emission micro tips with uniform performance.

Glow plasma display are through small vacuum plasma discharge excitation discharge cavity light-emitting materials, luminous effect, and low power consumption is its shortcomings (only 1.2 lm/W, and lamp luminous efficiency more than 80 lm/W, 6 watts per square inch display area), but in 102 ~ 152 cm diagonal field of the large-screen display has a strong competitive advantage.

The semiconductor light-emitting diode (LED) display scheme, due to the successful development of GaN blue light-emitting diode, has won absolute control over the market of the video display with very large screens, but this kind of display is only suitable for large outdoor displays, and video display with a small and medium screen does not have its market.

Special TFT – LCD, LCD flat panel display, is the only one in the brightness, contrast, such as power, life, volume and weight of integrated performance to catch up with and surpass that of the CRT display device, it features good performance, large-scale production, a high degree of automation, low cost of raw materials, the vast development space, will quickly become the mainstream product of the new century, is one of the highlights of the 21st-century global economic growth.

TFT-LCD, which USES liquid crystal as the excellent characteristic of the light valve, divides the luminous display device into two parts, namely the light source and the control of the light source. As a light source, no matter from luminous efficiency, full color, or life, has achieved brilliant results, but also in continuous deepening. Since the invention of the LCD, the backlight has been continuously improved, from monochrome to color, from thick to thin, from side fluorescent lamps to flat fluorescent lamps. The latest achievements in light sources will provide a new backlight for LCD. With the progress of light source technology, there will be newer and better light sources and LCD applications. Is the control of the light source, the rest of the large scale integrated circuit technology and semiconductor technology transplanted, successfully developed the thin film transistor (TFT) production technology, implements the matrix addressing the control of the liquid crystal light valve, solved the LCD light valve and the controller, so that the advantages of liquid crystal display (LCD).

The TFT thin-film transistor (matrix) — which “actively” controls individual pixels on the screen — is the origin of the so-called active matrix TFT.So how exactly do images come about? The basic principle is simple: a display screen consists of a number of pixels that can emit light of any color, and controlling each pixel to display a corresponding color does the trick. In TFT LCD, backlight technology is generally adopted. In order to accurately control the color and brightness of each pixel, a switch similar to a shutter needs to be installed after each pixel. When the “shutter” is opened, light can come through, but when the “shutter” is closed, light cannot come through.

Liquid crystal displays (LCDs) are filamentous, and their molecular structure changes as the environment change, giving them different physical properties — allowing light to pass through or block it — in the case of louvers.

TFT color filter is divided into red, green, and blue according to the color, which is successively arranged on the glass substrate to form a group (dot pitch) corresponding to a pixel. Each monochrome filter is called a sub-pixel. That said, if a TFT display supports a maximum resolution of 1280×1024, it needs at least 1280×3×1024 sub-pixels and transistors. For a 15-inch TFT display (1024 x 768), a pixel is about 0.0188 inches.

As you know, pixels are critical to a display, and the smaller each pixel, the larger the maximum possible resolution of the display. But because of the physical limitations of transistors, the TFT is roughly 0.0117 inches (0.297mm) per pixel, so the maximum resolution for a 15-inch display is 1,280 by 1,024.[1]

TFT technology is the basis of liquid crystal (LC), inorganic and organic thin-film electroluminescence (EL and OEL) flat panel displays.TFT is a kind of film necessary for manufacturing circuits formed by sputtering and chemical deposition process on the non-single wafers such as glass or plastic substrate, and large-scale semiconductor integrated circuit (LSIC) is produced by processing of the film. Using non-single-crystal substrate can greatly reduce the cost, which is the extension of traditional LSI to large-area, multi-function, and low-cost direction.

The first generation of large-area glass substrate (300mm×400mm) TFT-LCD production line was put into production in the early 1990s. By the first half of 2000, the area of glass substrate has been expanded to 680mm×880mm), and the recent 950mm×1200mm glass substrate will also be put into operation. In principle, there is no area limit.

The 1.3-inch TFT chip used for liquid crystal projection has a resolution of one million pixels in XGA.The resolution of the SXGA (1280×1024) 16.1-inch TFT array amorphous silicon film thickness is only 50nm, and the TAB ON GLASS and SYSTEM ON GLASS technology, its IC integration, requirements for equipment and supply technology, technical difficulty than the traditional LSI.

TFT was first used as a matrix location circuit to improve the optical valve characteristics of liquid crystals. For high-resolution displays, the accurate control of object elements is realized through voltage adjustment in the range of 0-6v (its typical value is 0.2 to 4V), thus making it possible for LCD to achieve a high-quality high-resolution display.TFT-LCD is the first flat panel display in human history to surpass CRT in display quality. Now people are starting to integrate the drive IC into the glass substrate, and the whole TFT will be more powerful than traditional large-scale semiconductor integrated circuits.

The glass and plastic substrates fundamentally solve the cost problem of large-scale semiconductor integrated circuits and open up wide application space for large-scale semiconductor integrated circuits.

In addition to traditional film formation processes such as sputtering and CVD (chemical vapor deposition) and MCVD (molecular chemical vapor deposition), laser annealing technology has also been applied, which can produce amorphous and polycrystalline films as well as monocrystalline films. Not only can make silicon membrane but also can make other Ⅱ – Ⅵ and Ⅲ – Ⅴ semiconductor thin film.

Low voltage applications, low drive voltage, solid use safety, and reliability improvement; Flat, light, and thin, saving a lot of raw materials and space; Low power consumption, its power consumption is about one-tenth of the CRT display, reflective TFT-LCD is only about one percent of the CRT, saving a lot of energy; TFT-LCD products also have specifications, models, size series, variety, convenient and flexible use, maintenance, update, upgrade easy, long service life and many other characteristics. The display range covers the application range of all monitors from 1 inch to 40 inches and the large projection plane, which is a full-size display terminal; Display quality from the simplest monochrome character graphics to high resolution, high color fidelity, high brightness, high contrast, the high response speed of various specifications of video display; Display mode has direct vision type, projection type, perspective type, and reflection type.

No radiation, no flicker, no harm to the user’s health. In particular, the appearance of TFT-LCD electronic books and periodicals will bring mankind into the era of a paperless office and paperless printing, and trigger the revolution of human learning, communication, and recording civilization.

The temperature range from -20℃ to +50℃ can be used normally, and the low temperature working temperature of TFT-LCD after temperature reinforcement can reach -80 ℃. It can be used as a mobile terminal display, desktop terminal display, and large screen projection TV. It is a full-size video display terminal with excellent performance.

The TFT LCD screen display, for the general masses, is no longer a difficult noun. And it is another after semiconductor could create a large number of emerging technology products of the business turnover, more because of its features, thin so it than using the application scope of the cathode ray tube (CRT, cathode ray tube) display made by wider. Today, I’m going to talk about how the TFT LCD Touch Screen Display Works.

As I mentioned earlier, liquid-crystal displays (LCDs) refer to a bunch produced by using the TFT screen LCD display. Now for LCD displays the name is directed mostly used in notebook computers, or desktop computer applications display. Is the thin film transistor TFT LCD display. Abbreviation of TFT LCD. This kind of display form has two main characteristics, one is a thin film transistor, the other is TFT LCD itself. Let’s talk about the TFT screen itself.

We usually think of substances like water as three states, solid-liquid, and gas. The three states of material actually are for water, for different materials, a different state may exist.

This type of TFT LCD screen was first discovered, had been spent more than one hundred years ago. In 1888 AD, the Austrian botanist Friedrich Reinitzer, found in the observation from the plant refined out of benzoic acid cholesterol (cholesteryl benzoate) found that when the melting behavior of the compound heated to 145.5 ℃, Solid can melt, presents a kind of solid phase and liquid phase between the half gonorrhea melt flow of the liquid. This situation will always maintain ℃ temperature rise to 178.5 degrees, to form a clear isotropic liquid (isotropic liquid).

The next year, in 1889, the study of thermodynamic equilibrium and the phase transfer German physicist O.L Ehmann, compounds for a more detailed analysis of this. He found that under the polarizing microscope, half of the viscous liquid gonorrhea liquid compounds with different parts peculiar to the crystal birefringence (birefringence) of the optical properties, namely, optical interphase (optically anisotropic). It will be a name to this as the liquid crystal. Since then, scientists will be the nature of this new discovery, known as the fourth state material – LCD (liquid crystal). It at a specific temperature range can have the characteristics of the liquid and solid at the same time.

General with water, solid lattice in heating because it is over, began to heat and destroy the lattice, when the temperature exceeds melting point will be dissolved into a liquid. And cause the type of liquid crystal is different (see figure 2), when the solid heat does not directly into the liquid, will be dissolved to form a liquid crystal state. When you continue heating, it will only then dissolve into a liquid (isotropic liquid). This is called the secondary dissolution phenomenon.

Its structure is composed of TFT LCD molecules stick together, forming a layer structure. It’s every layer of the molecular long axis direction parallel to each other. And the long axis direction for each layer plane is vertical or a tilt Angle. Due to its structure is very similar to crystals, so they are called phase. The order parameter S (the order parameter) tend to be 1. Type in layered crystal layer and interlayer bonding can fracture because of temperature, so the layer and interlayer sliding more easily. But each layer within the molecular bonding is stronger, so it is not easy to be interrupted. Therefore in the context of the monolayer, Its arranged orderly and viscosity is bigger. If we use the macroscopic phenomenon to describe the physical properties of liquid crystal, we can make a group of regional average points as the liquid crystal molecules are pointing in the direction of the arrow (director), which is the direction of a group of liquid crystal molecules regional average. And with lamellar liquid crystal, because of its structure, the TFT LCD molecules will cambium-like so can point to a vector of different classification of the different lamellar liquid crystal again. When the long axis of the liquid crystal molecules are vertical stand, Call it “Sematic A phase.” if stand long axis direction of the TFT LCD molecules have some Angle of tilt (tilt), call it “Sematic C phase”. In A, C and other letters to name, which was discovered in accordance with the order to address, and so on, there should be A “Semantic phase B is.” but later found A deformation phase B is C phase, And the liquid crystal molecules in the structure layer by layer, in addition to each layer of TFT LCD molecules have tilt Angle, the tilt Angle between layer by layer will form a helical structure.

Nematic is a Greek word, the word mean in the thread is the same as in English. Mainly because with the naked eye to observe the liquid crystal, it looks like a silk pattern. The LCD screen molecules on the space of the regular arrangement of one dimension, all rod long axis of the liquid crystal molecules will choose a particular direction (that is, pointing vector) as the main shaft and arranged parallel to each other. And don’t like lamellar liquid crystal has a layered structure. Compared with the layer column type liquid crystal alignment is no order, That is to say, its order parameter S is smaller than the lamellar liquid crystal, and its viscosity is smaller, so it is easier to flow (its flow mainly comes from the free movement of molecules in the long axis direction). Linear liquid crystal is the common TFT LCD display screen TN(Twisted nematic) type liquid crystal.

Most of the sources of the name, because are generated by the derivative of the cholesterol. But some without cholesterol structure of LCD screen with this liquid crystal phase. This kind of liquid crystal as shown in figure 5, if it is a layer of a layer to separate, would very much like a linear LCD screen. But look at the Z-axis, may find it pointing in the direction of the arrow will with layers and layers of different distribution, like a spiraling when the pointing vector rotate 360 degrees for molecular layer thickness is called a pitch. Because of its every layer like linear LCD, so also known as Chiral nematic phase. In terms of cholesterol crystal, and pointing in the direction vector of the vertical distribution of LCD screen molecules, due to the different point to vector, will have the different optical or electrical differences, thus has produced different features.

If we are according to the molecular weight of high and low points can be divided into liquid crystal polymer (polymer liquid crystal, the polymer in many of the liquid crystal molecules) and low molecular liquid crystal. This kind of classification of TFT LCD belongs to the application of the low molecular liquid crystal. If the reasons for the formation of liquid crystal state, because it can be divided into type temperature formation of liquid crystal state to a liquid crystal (thermotropic), and because of the concentration and the formation of a liquid crystal state type lyotropic liquid crystal (lyotropic).

In the classification of the mentioned before, Lamellar liquid crystal and liquid crystal of the linear type liquid crystal to cause the more common, as the temperature changes and form liquid crystal state. For the lyotropic liquid crystal, we need to consider the situation of molecules dissolved in a solvent. When the concentration is low, the molecular and mixed and disorderly, which are distributed in the solvent of the isotropic solution, but when higher concentration is greater than a certain critical concentration, because the molecule has no enough space to form mixed and disorderly, the distribution of molecular began to gather to form part of the rules, To reduce the space of the block. Therefore form different sex (anisotropic).

The solution so types lyotropic TFT screen molecules in the appropriate solvents reaches a certain critical concentration, the formation of liquid crystal state. Type lyotropic liquid crystal is one of the best examples that is soap. When soap bubbles in the water will not be at once into a liquid, and the bubble in the water for a long time, after the formation of white matter, is its liquid crystal state.

Due to the structure of the liquid crystal molecules for different parties (Anisotropic), so caused by the photoelectric effect will vary because of a different direction, in short, that is, the liquid crystal molecules in the dielectric coefficient and refractive index, and so on photoelectric properties have different sex, so we can use these properties to change the intensity of the incident light, so that the formation of gray-scale, to apply on the display component. We’ll discuss below, is one of the characteristics of liquid crystal belongs to the optical and electrical related, about the following items:

Our dielectric coefficient can be separated into two directions respectively is epsilon / / (and point to parallel component) and epsilon coming (a component perpendicular to the pointing vector). When the epsilon / / > epsilon coming then called the dielectric coefficient of different parts of LCD, can be used in parallel coordination. And epsilon / / < epsilon is called the dielectric coefficient of the different part coming negative type of TFT screen, only can be used in vertical coordination will need the photoelectric effect. When the applied electric field, the liquid crystal molecules will vary with dielectric coefficient is positive or negative, To determine whether the orientation of the liquid crystal molecules is parallel or perpendicular to the electric field, to determine whether the light penetrates. Now on most commonly used type TN LCD TFT LCD that belongs to the dielectric coefficient are type liquid crystal. When the dielectric coefficient of square difference Δ epsilon (= epsilon / / – epsilon) comes, the greater the LCD of the critical voltage (threshold voltage) will be smaller. So the LCD can be in the low voltage operation.

Liquid crystal molecules are also known as heterotropic crystals because they are mostly formed from rod-like or saucer-like molecules, and thus have different physical properties that are parallel to or perpendicular to the long axis of the molecule. Like the dielectric perp, the refractive index is also divided into vectors perpendicular to and parallel to the vector, namely, n // and n perpendicular to each other.

In addition, for uniaxial crystal, there are two different definitions of refraction coefficient, one is no, which refers to the refraction coefficient of ordinary ray, so it is shortened to no, and ordinary ray refers to the electric field component of its light wave is perpendicular to the optical axis, and the other is ne, which refers to the refraction coefficient of extraordinary ray. The extraordinary ray is referred to as the light of the electric field component parallel to the optical axis. At the same time, it defines the birefringence (birefringence) Δ n = no-no for the above two refractive index differences.

In accordance with the described above, the lamellar liquid crystal, linear liquid crystal, and LCD screen for cholesterol levels, because of its long liquid crystal molecules like a stick, so point to the direction of the vector and the molecular long axis parallel. To be defined with reference to the refraction coefficient of a single optical axis crystal, it will have two refractive indexes, respectively is perpendicular to the direction of the long axis of the liquid crystal n coming (= ne) and parallel to the long axis of the liquid crystal direction n / / (= no), so when the incident light liquid crystal, will be affected by two refractive indexes, cause in the vertical long axis of the liquid crystal and LCD long axis parallel to the direction of the speed of light will be different.

If with the molecular long axis parallel to the direction of light speed, when less than perpendicular to the speed of the molecular long axis direction, which means that parallel the molecular long axis direction of refractive index is greater than the vertical direction of the refractive index (because the refractive index is inversely proportional to the speed of light), is the one – no > 0. So the birefringence Δ n > 0, we think that it is called optics is a type of LCD, and lamellar liquid crystal and LCD are all belong to the optical is almost linear LCD. If the light of the parallel to the direction of the long axis was faster, On behalf of the flat to the governor of the axis of the refractive index is less than the vertical direction, so the birefringence Δ n < 0. We call it is the optical negative type of LCD. The cholesterol liquid crystal optical negative type of LCD.

For example, the elastic constant (kappa 11, kappa 22, kappa 33) contains the three most important constants: kappa 11 is the elastic constant at splay, kappa 22 is the elastic constant at the twist. Kappa 33 refers to predominating the elastic constants of bending (bend). The other as the coefficient of viscosity (viscosity coefficients and eta), will affect the rotational speed of the liquid crystal molecules with reaction time (response time), its value as small as possible. But this feature is affected by temperature is the largest. In addition to magnetic susceptibility (magnetic susceptibility), but also because of liquid crystals of different sex, Divided into c / / c coming. And the difference of magnetic susceptibility is defined as Δ c = c / / – c coming. In addition to the conductance coefficient (conductivity), and so on the photoelectric properties. Liquid crystal properties of the most important are the dielectric coefficient and refractive index of liquid crystal. The dielectric coefficient is determined liquid crystal under the influence of the electric field to the characteristics of the liquid crystal molecules, while the refractive index is liquid crystal in the light of its important parameters influencing the light path. The LCD is in using the liquid crystal itself of these features, the appropriate use of voltage, to control the rotation of the TFT LCD molecules, in turn, affect the direction of the light, to form different grayscale, a tool for displaying images. Of course, LCD itself is not alone as the monitor, also need other materials to help, Below, we will introduce the composition of various materials and operating principle of TFT LCD display.

I remember in high school physics class, when to teach the relevant physical properties of light, to do a lot of physical experiments, the purpose is to prove that light is a wave. And the marching direction of light waves, and the electric field and magnetic field perpendicular to each other. Light itself of the electric field and magnetic field component at the same time also is perpendicular to each other. That is to say with the electric field and magnetic field component direction, each other is two parallel to each other. (see figure 7) and the role of the polarizing film is like a fence, usually will be cut off a component perpendicular to the fence, With a fence parallel component only permitted through. So if we picked up a piece of the light polarization slabs, feel like wearing sunglasses, the light became dark. But if the two pieces of polarizing film ideas together, it won’t be the same. When you rotate the two pieces of the relative Angle of the polarizing film, you will find that as the relative Angle is different, the brightness of the light will be more and darker. When two polaroids fence Angle perpendicular to each other, Light was completely failing. (see figure 8) and a liquid crystal display is to use this feature. Use upper and lower two pieces of fences between perpendicular slant plate, filled with liquid crystal, recycle electric field control liquid crystal rotation, to change the direction of light, so that different electric field sizes, can form different gray-scale brightness.

The upper and lower two layers of glass are mainly to grip the LCD with. Below the glass layer with Thin film transistor (thin film transistor, TFT screen), while the layer above the glass with a Color filter (Color filter). If you notice (see figure 3), these two pieces of glass are in contact with the side of the LCD screen, not smooth, but with jagged grooves. The main purpose of the groove with the hope of a long rod, liquid crystal molecules will line up along the grooves. In this way, Liquid crystal molecules are arranged neatly. Because if it is smooth and flat, the arrangement of the liquid crystal molecules will not neat, causing light scattering, forming a light-leaking phenomenon. In fact, this is just a theory that told us to put the glass and LCD interface, complete processing so that the arrangement of liquid crystal has a certain order. But in the actual manufacturing process, and can not be with such a groove, the distribution of glass is made usually in glass coating on the surface layer of the PI (polyimide), and then a cloth to do the action of friction (rubbing), In order to make the surface molecules of PI no longer be scattered and arranged in a fixed and uniform direction, this layer of PI is called the coordination membrane, and its function is just like the grooves in the glass in FIG. 3, which provides the interface conditions for the uniform arrangement of liquid crystal molecules and allows the liquid crystals to be arranged in a predetermined order.

We can know from figure 10, when there is no applied voltage between the upper and lower two pieces of glass, the arrangement of LCD will be in accordance with the match to the membrane of the upper and lower two pieces of glass. For TN type of LCD, and match to the film’s point of view of the poor to 90 degrees. (see figure 9) so the liquid crystal molecules are arranged by the up and down automatically rotate 90 degrees when the incident light passes through the upper polarizing film, the polarization of light waves will only order direction. Through the liquid crystal molecules, the liquid crystal molecules rotate for 90 degrees, so when the waves reach the lower polarizing film, the polarization direction of the light just turned 90 degrees. The polarizing film of the lower and upper polarizing film, 90 – degree Angle is just the differences. (see figure 9) so can smoothly through the light, but if we applied voltage between the upper and lower two pieces of glass, because the type TN LCD for the dielectric coefficient of different sex more positive type of LCD (epsilon / / > epsilon coming, represent the parallel direction of the dielectric coefficient is larger than the dielectric coefficient of the vertical direction, so when the liquid crystal molecules are influenced by an electric field, will tend to be parallel to the orientation of the electric field direction.), so we can see from figure 10, At this time, the polarized light wave passing through the upper polarizer will not change the polarization direction when passing through the liquid crystal molecule, so it cannot pass through the lower polarizer.

The so-called NW (Normally white), is to point to when we don’t apply voltage on the LCD screen panel, we can see the panel is pervious to light, also is bright, so-called Normally white. But on the other hand, when we don’t apply voltage on the LCD panel if the panel is not pervious to light, the look is black, it’s called NB (Normally black). We have just mentioned in figure 9 and figure 10 all belongs to the configuration of NW, also we can know from figure 11, For type TN LCD, located in the upper and lower glass is perpendicular to the membrane, and the difference between NB and NW just lies in the relative position of the polarizing film is different. For NB, the fluctuation of the polarizing film polarity is parallel to each other. So when the NB no applied voltage, the light will be because the polarity of the LCD to rotate 90 degrees to be pervious to light. Why there are NW and NB these two kinds of a different configuration of the polarizing film? Mainly for different applications. Commonly used in a desktop computer or notebook computer, most of the NW configuration. That’s because, if you notice, generally the use of computer software environment, you will find that most of the entire screen is a bright spot, that is to say, computer software for the application of white background and black text. Since on the point of the majority, using NW is more convenient, of course. Also because the NW window does not need to add the voltage, the average will compare to save electricity. In turn, said that the application of the NB environment mostly belongs to the screen for the application of black.

The STN LCD and TN LCD are very similar in structure, the main difference between TN LCD, the arrangement of the liquid crystal molecules, the rotation angle from top to bottom. A total of 90 degrees and type the STN LCD liquid crystal molecules are arranged, the rotation angle will be greater than 180 degrees, usually is 270 degrees. (see figure 12) because of its rotation Angle is different, its characteristics different. We from figure 13 TN type and type the STN LCD voltage of the transmittance curve can know, when the voltage is low, the light penetration rate is very high. With a high voltage, the light of the penetration rate is very low. So they belong to the Normal White polaroids configuration. When the voltage in the middle position, the change of type TN LCD curve is flat, and the change of the STN LCD type curve is steep. So in TN type LCD, when transmittance change from 90% to 10%, corresponding to the voltage difference is larger than the STN LCD. We mentioned before, in the liquid crystal display, The different characteristics of TN and STN will result in TN type LCD, which has more grayscale changes than STN type LCD, so generally TN type LCD has 6~8 bits of changes. It is 64 ~ 256 gray-scale changes. Type the STN LCD for a maximum of 4 bits are only 16 orders of gray-scale changes. In addition, the STN type and TN LCD has a different place is the reaction time (response time) general type the STN LCD it’s response time to type in more than 100 ms and TN LCD its response time is 30 ~ 50 ms as shown in the image change quickly for the STN LCD type ghosting effect phenomenon is easy to happen.

TFT LCD Chinese translation of the name is called a thin film transistor liquid crystal display, from the beginning, we mentioned LCD voltage control is needed to produce gray. And the use of a thin-film transistor to generate the voltage, to control the transition of liquid crystal display, is called a TFT LCD. From the point of the cross-section structure of figure 8, between upper and lower two layers of glass, with LCD, will form a parallel plate capacitor, we call it the CLC (capacitor of liquid crystal). Its size is about 0.1 m3, But on the practical application, the capacitance and unable to keep the voltage to the next time to update the data in the picture.

That is to say, when TFT is good to the capacitor charging power, it is impossible to maintain voltage, until the next TFT this point charge again. (in general of 60 Hz screen update frequency, need time to keep about 16 ms.) as a result, there were changes in voltage, displayed gray scale is not correct. Therefore generally on the design of the panel, we will add a storage capacitor CS (storage capacitor is about 0.5 pF). So charged electric voltage can keep until the next update screen. But the right, long on the glass TFT itself, just use a transistor to make the switch. Its main work is to determine the LCD source voltage on the driver whether to charge to this point. As for this point more charge to high voltage, so as to show how the gray-scale. It is outside of the LCD source driver.

If you have a chance, take a magnifying glass, close to the LCD screen. You will find that as shown in figure 9 shows. We know that red, blue and green, are the so-called primary colors. That is to say, using the three kinds of color, can produce a variety of different colors. In a lot of flat-panel displays, this principle is used to show the color. We put the RGB 3 kinds of color, is divided into independent three points, each has different gray-scale changes, then the three neighboring RGB display point, as the basic unit of a display, Pixel is that this a pixel, and can have different color changes. Then for a need for a 1024 * 768 resolution display screen, we just let the composition of the flat panel display with 1024 * 768 pixels, can show a picture of the right. In figure 9, each point between the Black part of RGB is called the Black matrix. We can find that looking back on it in figure 8Black matrix is mainly used to cover do not intend to previous to light part. Such as some ITOs walk the line, or Cr/Al walk the line or are part of a TFT. This is why we in figure 9, the highlight of each RGB, it seems, is not a rectangle, and also on the top left corner is a piece of black matrix cover part, this part of a black missing Angle is the location of the TFT.

Figure 9 shows the common arrangement of color filters. Stripe is most commonly used in OA products, such as laptops, desktop computers, etc. Why is stripe used in this application? More often than not, the reason is now software is the Windows interface. That is to say, we can see the screen content, is composed of a pile of boxes of various sizes. The strips, just can make the edge of the box, look more straight, and there won’t be a straight line, look have the feeling of burrs or serrated. But if it is applied in the AV products, just not the same. Probably because the TV signal is a character, the character of the line is not straight, the contour is a mostly irregular curve. So in the beginning, the Use Mosaic arrangement used in AV products is (Mosaic, or called arranged diagonally). But the latest AV products, more have been improved to use triangle arrangement (triangle, or known as the delta). In addition to the above arrangement, still have a kind of arrangement, which is called a square arrangement. It is not the same as the first few, it is not three-point to as a pixel, but with four points as a pixel. And just four points are combined to form a square.

The CRT screen, it is using a high-speed electron gun that emits electrons, hits the phosphors on the silver screen, so as to produce the light, to show the picture. LCD itself, however, can only control the brightness of the light through, no glowing function itself. Therefore, a liquid crystal display must be combined with a backplate, to provide high brightness, brightness, and uniform distribution of the light source. We can see in figure 14, of the backplate of the main parts are CCFL (cold cathode tube), reflex plate, guide plate, prism sheet, Diffuser plate, and so on. Tubes are the main light-emitting parts, by a light guide, everywhere. The light distribution and baffle will be limited only to the TFT LCD light direction. Finally, by prism sheet and help diffuser, the light evenly distributed to all areas, provide TFT LCD a bright light. While TFT LCD is borrowed by the rotation of the voltage-controlled liquid crystal, control through the brightness of the light, so as to form different grayscale.

Another box in figure 14 glue and spacer structure of two kinds of ingredients. The box adhesive USES is to make the LCD panel in the upper and lower two layers of glass, to be able to stick close and to provide a panel of LCD screen molecules, cut off from the outside world, so the box plastic as its name suggests, is around and around in the panel to the liquid crystal molecules box limited to within a panel. The spacer is mainly provided two-layer glass support, it must be distributed evenly on the glass, or a part but uneven distribution cause spacer gathered together, it will block the light, It is also unable to maintain the appropriate gap between the upper and lower glass, which will lead to uneven distribution of electric field and affect the performance of the crystal grayscale.

A very important specification of LCD is brightness, and the most important factor to determine the brightness is the opening rate. What is the opening rate? Is simple light can pass through the effective area proportion. 17, let’s look at the picture to the left of figure 17 is an LCD display from directly above or below the past structure. When the light is emitted through the backplate, not all of the light can be through the panel, like for LCD source driver chip and the gate driver chip signal line, and TFT itself, the stored voltage is the use of storage capacity, etc. These places besides incomplete pervious to light, but also because the light through these places is not under voltage control, to display the correct gray-scale, so have to use the black matrix to cover, in order to avoid interference to other correct brightness of the light area. So the effective area of the previous to light, it’s just like figure 17 shows area on the right. This piece of the effective area of the previous to light and the ratio of the total area is called the opening rate.

When the light is emitted from the backlight plate, it will pass through the polarizer, glass, LCD screen, color filter, etc. It is assumed that the penetration rate of each part is as follows:

Color filter:27%(assume that the material itself has a penetration rate of 80%, but since the filter itself is painted with color, only light waves of that color can be allowed to pass through. For RGB primary colors, only one of the three colors can be allowed to pass through. Therefore, only one-third of the brightness is left.

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When a voltage is applied between the upper and lower surfaces, the liquid crystal molecules are aligned in the direction of the electric field, forming a vertical alignment. At this point, the incident light is not affected by the Liquid Crystal Molecules, straight out of the lower surface.

The liquid crystal cannot emit light by itself, and the backlight should be added behind the LCD panel. A few years ago, CCFL cold cathode backlighting was the dominant market application, but with the development of technology, the LED backlight has gradually replaced the traditional CCFL backlight.

TFT displays are also known as an “Active Matrix TFT LCD module” and have an array of thin film transistors fabricated on the glass that makes the LCD. There is one of these transistors for each pixel on the LCD.

LCDs use voltage applied to a field of microscopic liquid crystals to change the crystal’s orientation, which in turn changes the polarization of the liquid crystal which creates light or dark pixels on the display.

Beautiful, complex images: All of our TFT modules are full-color graphic displays. Unlike standard monochrome character displays, you can create complex images for an imaginative user experience.

Thin and light: These are ideal display modules for handheld devices, communications equipment, information displays, and test and measurement equipment.

Single Supply: Most of the TFTs use an integrated controller with built-in voltage generation so only a single 3.3v supply is needed for both the panel power and logic voltage.

Many of our character LCD modules use a standard HD44780 controller, so they can be quickly integrated into a new product or used as a replacement in your existing products.

Many of the LCD