tft lcd displays matrix lcds quotation

2023-01-03 12:32:11

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.

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.

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).

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.

tft lcd displays matrix lcds quotation

TFT displays are full color LCDs providing bright, vivid colors with the ability to show quick animations, complex graphics, and custom fonts with different touchscreen options. Available in industry standard sizes and resolutions. These displays come as standard, premium MVA, sunlight readable, or IPS display types with a variety of interface options including HDMI, SPI and LVDS. Our line of TFT modules include a custom PCB that support HDMI interface, audio support or HMI solutions with on-board FTDI Embedded Video Engine (EVE2).

tft lcd displays matrix lcds quotation

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.

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.

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:

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.

tft lcd displays matrix lcds quotation

The transmission (luminance) versus the applied voltage characteristic is shown in Fig. 11. The shown characteristic is for normal viewing angle and indicates that grayscale levels can be achieved by varying the voltage across the LCD. Unfortunately, the transmission – voltage curve is viewing angle dependent, leading to grayscale errors and color shift in a display when it is viewed from significant angles to the display normal.

The equivalent circuit with the parasitic elements of a pixel cell and a typical TFT-LCD pixel layout are shown in fig. 12. The pixel consists of a switch TFT device, with the gate electrode connected to the row driver lines and the source electrode connected to the column driver lines. Furthermore, a storage capacitor is connected in parallel to the LC pixel capacitance.

The aperture part is the light transparent part and it is designated for the placement of the liquid crystal while the TFT, voltage lines and storage capacitor areas are non-light transparent. The ratio between the transparent portion of a pixel and its surrounding electronics is called aperture ratio or fill factor. Furthermore, in the shown layout design, the storage capacitor is connected to an adjacent row line resulting in the maximization of the aperture ration but the load capacitance of the row lines is, also, increased. The counter electrode of the LC pixel capacitor is the common ITO electrode on the opposite substrate (Den Boer, 2005). For large displays, this configuration is difficult to be used due to the large RC delay time of the row lines. In order to overcome this problem, a common storage bus can be placed in the aperture area which reduces the load capacitance of the row lines, but also reduces the aperture ration of the pixel.

The crosstalk effect is caused due to the column-line video-signal coupling during one frame and a DC component is being added to the AC data voltage. The DC component can not be entirely eliminated for all gray across the entire pixels matrix, resulting to slight difference in the pixel transmittance between the odd and even frames. A solution to this problem is the polarity inversion method. Apart from elimination of the DC component, the influence of the flicker on the display image quality is also eliminated with the use of a polarity inversion method. Four different polarity inversion methods have been widely used. Figure 13 shows the configuration of the four polarity inversion methods. The type of the polarity inversion method has an impact on the power consumption of the display. In the frame inversion method, all the pixels are driven to + Vp polarity in one frame period and then all of them are driven to – Vp polarity during the next frame period. This method is the most power-efficient method. However, this method is sensitive to the flicker and to vertical and horizontal crosstalk, meaning that this method can not be used in high image quality displays.

A full color LCD display can be generated by incorporating red, green and blue color filters at the pixels. In order to produce the desirable color tone, the pixel is divided into three sub-pixels each one having red, green and blue color filter, respectively. The three sub-pixels have the same dimensions and the proper combination of each color tone; by applying the right voltages to the liquid crystals, the desired pixel emissive colour will be produced. The width of each sub-pixel is three times smaller than the sub-pixel length and when the three sub-pixels are very closely placed in parallel, a square full color pixel is produced. Figure 14 shows a full colour square pixel.

tft lcd displays matrix lcds quotation

T. Arai, H. Iiyori, Y. Hiromasu, M. Atsumi, S. Ioku, and K. Furuta,“Aluminium-Based Gate Structure for Active Matrix Liquid Crystal Displays,” IBM Journal of research and Development, Vol. 42, No. 3/4, pp. 491–499,1998.

D. Eliav, E.H.A. Langendijk, S. Swinkels, I. Baruchi, “Suppression of Color Breakup in Color-Sequential Multiple-Primary Projection Displays,” SID Digest, Vol. 36, No. 1, pp. 1510–1513, 2005.

N. Fisekovic, T. Nauta, N.J. Cornelissen, and J. Bruinink, “Improved Motion- Picture Quality of AM-LCDs Using Scanning Backlight,” Proceedings of International Display Workshops, pp. 1637–1640, 2001.

K. Fujimori, Y. Narutaki, and N. Kimura, “High-Transmissive Advanced TFT LCD Technology,” Sharp Technical Journal, No. 4, 2003. (sharpworld.com/corporate/info/rd/index.html).

H. Gleskova and S. Wagner, “DC-Bias Stressing of a-Si:H TFTs Fabricated at 150°C on Polyimide Foil,” IEEE Transactions on Electron Devices, Vol. 48, No. 8, p. 1667, 2001.

J. Hirakata, A. Shingai, Y. Tanaka, K. Ono, and T. Furuhashi, “Super-TFT-LCD for Moving Picture Images with the Blink Backlight System,” SID Digest, Vol. 32, No. 1, pp. 990–993, 2001.

M.D. Jacunski, M.S. Shur, and M. Hack, “Threshold Voltage, Field Effect Mobility and Gate-to-Channel Capacitance in Polysilicon TFT’s,” IEEE Transactions on Electron Devices, Vol. 43, No. 9, pp. 1433–1440, 1996.

Y. Kanemori, M. Katayama, N. Nakazawa, H. Kato, K. Yano, and Y. Fukuoka, “10.4 in.-Diagonal Color TFT-LCDs without Residual Images,” SID Digest, pp. 408–411, 1990.

K. Karim, A. Nathan, M. Hack, and W. Milne, “Drain Bias Dependence of Threshold Voltage Stability of Amorphous Silicon TFTs,” IEEE Electron Device Letters, Vol. 25, No. 4, pp. 188–190, 2004.

S.-J. Kim, Y.-C. Sung, and O.-K. Kwon, “Pre-Emphasis Driving Method for Large Size and High Resolution TFT-LCDs,” SID Digest, Vol. 34, No. 1, pp. 1354–1357, 2003.

F.R. Libsch and S.-C.A. Lien, “Understanding Crosstalk in High-Resolution Color Thin-Transistor Liquid Crystal Displays,” IBM Journal of Research and Development, Vol. 42, pp. 467–479, 1998.

A.G. Lewis, D.D. Lee, and R.H. Bruce “Polysilicon TFT Circuit Design and Performance,” IEEE Journal of Solid-State Circuits, Vol. 27, No. 12, pp. 1833–1842, 1992.

B.-W. Lee, K. Song, D.-J. Park, Y. Yang, U. Min, S. Hong, C. Park, M. Hong, and K. Chung, “Mastering the Moving Image: Refreshing TFT-LCDs at 120 Hz,” SID Digest, Vol. 36, No. 1, pp. 1583–1585, 2005.

H. Nakagawa, “Current Trends of Flat Panel Displays Viewed from Applications,” Sharp Technical Journal, No. 4, 2003. (http://sharpworld.com/corporate/info/rd/index.html).

K. Ono, Y. Imajo, I. Mori, R. Oke, S. Kato, K. Endo, H. Ishino, and Y. Ooishi, “New IPS Technology Suitable for LCD-TVs,” SID Digest, Vol. 36, No. 1, pp. 1848–1851, 2005.

K. Suzuki, “Compensative Addressing for Switching Distortion in a-Si TFTLCD,” Proceedings of 7th International Display Research Conference, pp. 107–110, 1987.

K.H. Shin, J.Y. Ahn, K.D. Kim, H.H. Shin, and I.J. Chung, “Acceptable Motion Blur Levels of a LCD TV Based on Human Visual System,” SID Digest, Vol. 37, No. 1, pp. 287–290, 2006.

Y.-C. Sung and O.-K. Kwon, “Low-Cost TFT-LCDs with Pre-Emphasis Driving Method for Large-Size and High-Definition TVs,” IEEE Transactions on Consumer Electronics, Vol. 53, No. 4, pp. 1674–1681, 2007.

Y. Son, J. Kim, H. Cho, J. Hong, J. Na, D. Kim, D. Han, J. Hong, Y. Jeon, and G. Cho, “A Column Driver with Low-Power Area-Efficient Push-Pull Buffer Amplifiers for Active-Matrix LCDs,” Proceedings of IEEE International Solid- State Circuits Conference, pp. 142–143, 2007.

J.H. Souk and J. Lee, “Recent Picture Quality Enhancement Technology Based on Human Visual Perception in LCD TVs,” IEEE Journal of Display Technology, Vol. 3, No. 4, pp. 371–376, 2007.

J.H. Stessen and J.G.R. vanMourik, “Algorithm for Contrast Reserve, Backlight Dimming, and Backlight Boosting on LCD,” SID Digest, Vol. 37, No. 1, pp. 1249–1252, 2006.

E. Takeda, “Simplified Method of Capacitively Coupled Driving for TFTLCD,” Proceedings of 9th International Display Research Conference, pp. 580–583, 1989.

H. Takatsuji, E.G. Colgan, C. Cabral, Jr., and J.M.E. Harper, “Evaluation of Al(Nd)-alloy Films for Application to Thin-Film-Transistor Liquid Crystal Displays,” IBM Journal of Research and Development, Vol. 42, No. 3/4, pp. 501–508, 1998.

W.-C. Tsai, J.-Y. Lai, K.-Y. Tu, H.-T. Lin, and F.-Y. Gan, “A Novel Barrierless Cu Gate for TFT-LCD,” SID Digest, Vol. 37, No. 1, pp. 1181–1184, 2006.

E. Takeda, Y. Nan-no, Y. Mino, A. Otsuka, S. Ishihara, and S. Nagata, “Capacitively Coupled TFT-LCD Driving Method,” SID Digest, Vol. 31, No. 2, pp. 87–94, 1990.

S. Uchikoga, “Future Trend of Flat Panel Displays and Comparison of its Driving Methods,” Proceedings of 18th International Symposium on Power Semiconductor Devices & IC’s, pp. 1–5, 2006.

J.-S. Yoo, “A Novel Polysilicon TFT with Lateral Body Terminal for Driving Circuit Application of AMLCDs,” ITE Technical Report, Vol. 23, No. 67, p. 27, 1999.

Y.-S. Son, H.-H. Son, Y.-S. Kim, H.-S. Oh, and G.-H. Cho, “A Gray-Level Dependent Pre-Emphasis Column Driver with Fast Settling for Active-Matrix LCD Applications,” IEEE Transactions on Circuits and Systems - Part II, pp. 1057–1061, 2007.

tft lcd displays matrix lcds quotation

160x100 Dot Matrix COG, FSTN, Gray background, White Edge lit, Bottom view, Wide temp, Transflective (positive), 3.0V LCD, 3.3V LED, RoHS Compliant. This COG display has a wide temperature range: -20° Celcius to +70° Celcius which equates to (-4° Fahrenheit to +158° Fahrenheit).

FSTN (Film-compensated Super-twisted Nematic) provides a sharper contrast than STN by adding a film. The cost is approximately 5% higher than STN. FSTN works great for indoor and outdoor applications and is mainly used in graphic displays and higher end products. The Transflective polarizer is a mixture of Reflective and Transmissive. It provides the ability to read the LCD with or without the backlight on. It will work for all lighting conditions from dark with backlight to direct sunlight which makes it the most common choice. There is no cost difference between Transflective, Transmissive and Reflective.

Focus LCDs can provide many accessories to go with your display. If you would like to source a connector, cable, test jig or other accessory preassembled to your LCD (or just included in the package), our team will make sure you get the items you need.Get in touch with a team member today to accessorize your display!

Focus Display Solutions (aka: Focus LCDs) offers the original purchaser who has purchased a product from the FocusLCDs.com a limited warranty that the product (including accessories in the product"s package) will be free from defects in material or workmanship.

tft lcd displays matrix lcds quotation

128x32 Dot Matrix COG, FSTN, Gray background, White Edge lit, Bottom view, Wide temp, Transflective (positive), 3.0V LCD, 3.0V LED, RoHS Compliant. This display has a wide temperature range: -20° Celcius to +70° Celcius which equates to (-4° Fahrenheit to +158° Fahrenheit).

tft lcd displays matrix lcds quotation

Technology can be confusing because it evolves quickly, and there are complex acronyms for almost everything. If you are thinking ofbuildinga monitor or want to learn about the technology, you will encounter the term TFT Monitor at some point.

A lot goes on behind the glass surface, and we will look at this in comparison to other technologies to paint a clear picture of what TFT is and how it evolved.

TFT is an acronym for Thin Film Transistor, and it is a technology used in Liquid Crystal Display screens. It came about as an improvement to passive-matrix LCDs because it introduced a tiny, separate transistor for each pixel. The result? Such displays could keep up with quick-moving images, which passive-matrix LCDs could not do.

Also, because the transistors are tiny, they have a low power consumption and require a small charge to control each one. Therefore, it is easy to maintain a high refresh rate, resulting in quick image repainting, making a TFT screen the ideal gaming monitor.

The technology improved on the TN (Twisted Nematic) LCD monitor because the shifting pattern of the parallel, horizontal liquid crystals gives wide viewing angles. Therefore, IPS delivers color accuracy and consistency when viewed at different angles.

Both TFT and IPS monitors are active-matrix displays and utilize liquid crystals to paint the images. Technically, the two are intertwined because IPS is a type of TFT LCD. IPS is an improvement of the old TFT model (Twisted Nematic) and was a product of Hitachi displays, which introduced the technology in 1990.

The monitors can create several colors using the different brightness levels and on/off switches. But unlike OLED, both TFT and IPS do not emit light, so most have bright fluorescent lamps or LED backlights to illuminate the picture. Also, neither of them can produce color, so they have an RGB color filter layer.

Easy to Integrate and Update: By combining large-scale semiconductor IC and light source technology, TFTs have the potential for easy integration and updating/development.

Wide Application Range: TFTs are suitable for mobile, desktop screens, and large-screen TVs. Additionally, the technology can operate at a temperature range of -20°C to +50°C, while the temperature-hardened design can remain functional at temperatures not exceeding -80°C.

Impressive Display Effect: TFT displays use flat glass plates that create an effect of flat right angles. Combine this with the ability of LCDs to achieve high resolutions on small screen types, and you get a refreshing display quality.

Good Environmental Protection: The raw materials used to make TFT displays produce zero radiation and scintillation. Thus, the technology does not harm the user or the environment.

Mature Manufacturing Technology: TFT technology came into existence in the 60s. Over time, its manufacturing technology has matured to have a high degree of automation, leading to cheaper, large-scale industrial production.

Wide View Angle: One of the main advantages of IPS screens is their wide viewing angle due to the horizontal liquid crystals. They do not create halo effects, grayscale, or blurriness, but these are common flaws with TFTs.

Better Color Reproduction and Representation: The pixels in TFTs function perpendicularly after activation with the help of electrodes. However, IPS technology makes the pixels function while parallel horizontally. Thus, they reflect light better and create a more original and pristine image color.

Faster Frequency Transmittance: Compared to TFT, IPS screens transmit frequencies at about 25ms, which is 25x faster. This high speed is necessary to achieve wide viewing angles.

Liquid Crystal Display (LCD) is a front panel display that utilizes liquid crystals held between two layers of polarized glass to adjust the amount of blocked light. The technology does not produce light on its own, so it needs fluorescent lamps or white LEDs.

As explained earlier, TFT improved on the passive-matrix LCD design because it introduces a thin film transistor for each pixel. The technology reducescrosstalkbetween the pixels because each one is independent and does not affect the adjacent pixels.

LED screens are like the new kids on the block in the display market, and they operate very differently from LCDs. Instead of blocking light, LEDs emit light and are thinner, provide a faster response rate, and are more energy-efficient.

Since IPS is a type of TFT, when comparing the two, we are essentially looking at the old Thin-Film Transistor technology (Twisted Nematic) vs. the new (IPS). Even though TN is relatively old, this digital display type has its advantages, a vital one being the fast refresh rate. This feature makes such screens the preferred option by competitive gamers. If you have any inquiries about the technology,contact usfor more information.

tft lcd displays matrix lcds quotation

The liquid crystal display (LCD) technology has been used in several electronic products over the years. There are more reasons for LCDs to be more endearing than CRTs.

tft lcd displays matrix lcds quotation

What is an active-matrix liquid crystal display? Also known as TFT Display, or Thin Film Transistor Display. An active matrix liquid crystal display is the display industry’s term for the type of flat panel display that is currently the overwhelming choice of notebook computer manufacturers, due to light weight, very good image quality, wide color gamut, and response time. With active matrix displays, each pixel is controlled by a switch-device which actively maintains the pixel state while other pixels are being addressed. This generally makes the screens faster, brighter, and more colorful then passive matrix control of each pixel, while preventing crosstalk from inadvertently changing the state of an unaddressed pixel.

Figures 3a–d show optical and SEM (scanning electron microscopy) images of the fabricated CL and CLSE pixel structures. Each structure has the same pixel size (80 μm × 240 μm) and minimum pattern size (5 μm). As shown in Fig. 3d, the white line patterns are the ITO interdigitated pixel and common electrodes. They are well connected to the source electrode and gate line via through holes, and the common electrodes at both ends cover the underlying data lines to prevent electrical noise from being applied to the LC layer. As will be shown later, this noise shield electrode (SE) is what makes the black matrix above the data line unnecessary

Optical and SEM (scanning electron microscopy) images of fabricated (a, b) CL and (c, d) CLSE pixel structures. The five white line patterns in (d) are the ITO interdigitated pixel and common electrodes. (e) Images from the normal direction and from 50 degrees to the left and right of a 2.3-inch-diagonal display incorporating the IPS TFT-LCD panel. (f) The three-black matrix (BM) patterns (top: BM covering both gate and data lines, middle: BM covering only the data lines, and bottom: without BM) and (g) optical images of pixels without BM (left: LC on and off voltages supplied to every other data line, right: LC off voltage supplied to all data lines).

Figure 3e shows images from the normal direction and from 50 degrees to the left and right of a 2.3-inch-diagonal display incorporating the IPS TFT-LCD panel fabricated in our laboratory, (f) the three black matrix (BM) patterns (top: BM covering both gate and data lines, middle: BM covering only the data lines, and bottom: without BM), and (g) optical images of panel areas without the BM (left: LC on and off voltages supplied to every other data line, right: LC off voltage supplied to all data lines). As can be seen in the image from the normal direction, the brightness and contrast of the display area with the top BM and middle BM patterns are almost the same, but the contrast of the display area without the BM is relatively lower because of the lower darkness level of the LC off pixels indicating “HITACHI”. As shown in Fig. 3g, this is due to light leaking through the aperture between the data line and adjacent common lines. Therefore, in the CL structure, the BM on the drain line is necessary to obtain a high contrast ratio by shielding light leakage. This is the same as in the conventional structure. On the contrary, there is no light leakage along the gate line through the gaps between the gate line and edges of the pixel/common electrodes, as is clearly shown in Fig. 3g. This is a unique advantage of the CL structure because the conventional structure must shield these gaps with the BM to prevent light leakage. The suppression of light leakage along the gate line in the CL structure is due to the driving scheme (see Fig. 2b,a for a comparison with the conventional structure). During the holding period (tOFF) in the conventional structure, regardless of the pixel voltage, Vp (including Vp = 0), nonzero Vgp and Vgc are always applied to keep the TFT off, and these voltages are applied to the LC layer, inducing light leakage as reported in

Figure 4a shows the gate voltage (Vg) dependence of the panel brightness, while the inset shows that of the TFT current (transfer characteristics). The gray curves are for the conventional IPS TFT-LCD with the TFT before enhancement, the common line, and the matrix BM (MBM) shown at the top of Fig. 3f. The blue curves are for the proposed CL structure with the enhanced TFT and the stripe BM (SBM) shown in the middle of Fig. 3f. In this case, enhanced TFT characteristics were obtained by using an MNOS TFT without back-channel oxidation that was enhanced by the BTS process. In both structures, the threshold voltages for panel brightness, defined by extrapolating the straight part of the brightness curves, reflect those of the TFT transfer curves defined as Vg at a drain current of 10−12 A, and they are well matched to be 4 V and 9 V, respectively. The maximum brightness for the CL structure is 137% higher than that for the conventional structure, which is due to the increase in the aperture ratio from 38 to 52% that results from the elimination of the common line and the BM covering the gate line.

(a) Dependence of panel brightness and TFT current on gate voltage for the conventional pixel structure of 38% aperture ratio (AR) with matrix black matrix (MBM) over both drain and gate lines and proposed CL pixel structure of 52% AR with strip black matrix (SBM) over only the drain lines. Transfer characteristics before and after bias temperature stress (BTS) treatment are shown in the inset. (b) Charging and (c) holding characteristics of enhanced TFT of the CL structure with gate as a common line. Vg and Vd in the TFT ON state are 30 V and +/−7 V, respectively.

To estimate the charging and holding characteristics of the MNOS-enhanced TFT in the panel, the gate TFT ON and OFF time dependences of the panel brightness were measured (Fig. 4b,c). The charging characteristics in Fig. 4b are plotted as a function of tON at tOFF = 16.6 ms, Vg = 30 V, and Vd = ± 7 V. The holding characteristics in Fig. 4c are plotted as a function of tOFF at tON = 34 μs. 95.1% charging at tON = 34 μs and 95.3% holding at tOFF = 16.6 ms indicate that the enhanced TFT has sufficient charging and holding performance to drive a standard VGA (640 × 480 pixels) panel (the number of scanning lines is estimated as tOFF/tON = 16.6/0.034 = 488).

To confirm the driving conditions for the CL structure without the BM along the gate line (with the SBM), the tOFF dependence of the contrast ratio (CR) in the CL panel was further investigated as shown in Fig. 5a, where CR is plotted as a function of tOFF for the CL panels with the matrix BM (MBM) and the strip BM (SBM). The inset shows the brightness in the bright (Vd = 7 V) and dark (Vd = 0 V) states of the CL panel with the SBM as a function of tOFF and an optical image of the panel with tOFF = 6.4 ms. The SBM and MBM panels keep CR higher than 240 with tOFF > 16.6 ms, the frame period of a display panel without flicker being noticeable to the human eye. both panels decrease CR when tOFF is less than 16.6 ms; the CR of the SBM panel decreases faster than the CR of the MBM panel. As shown in the inset, the decrease in CR was due to the increase in dark-state brightness with decreasing tOFF as light leakage increases along the gate line. This light leakage is induced by the voltage Vgp = Vgc = VgON = 30 V applied only for 34 μs during the TFT ON (charging) state, which is 1/488th the duration, tOFF = 16.6 ms, of the TFT OFF (holding) state with Vgp = Vgc = VgOFF = 0 V, but the ratio increases with decreasing tOFF and becomes effective enough to switch on LC layer and induce light leakage. However, it should be stressed again that the CL panel with the normal holding (TFT OFF) time of 16.6 ms does not suffer from the light leakage along the gate line, so the aperture ratio can be increased by removing the BM along the gate line.

(a) Contrast ratio (CR) for CL panels with matrix BM (MBM) and stripe BM (SBM) plotted as a function of tOFF. The inset shows the brightness in the bright (Vd = 7 V) and dark (Vd = 0 V) states of the CL panel with the SBM as a function of tOFF and an optical image of the panel with tOFF = 6.4 ms. Vd (= VLC) dependence of (b) brightness and (c) contrast ratio of the CLSE panel. Insets of (b): optical images indicating the elimination of the BM from the CLSE structure (upper left) and the MBM in the conventional structure (lower right). Insets of (c): CLSE panel composed of different areas with three different pixel structures and aperture ratios (ARs), i.e., CLSE structure without BM (60%), CL structure with SBM (52%), and conventional structure with MBM (38%).

Figure 6 indicates the effect of bias temperature stress (BTS) on the TFT characteristics. As the stressing time, tS, of the positive gate stress voltage, Vst = + 77 V, increases from 0 to 3600 s, the transfer (Id-Vg) curve shifts in the positive direction (Fig. 6a). Vth is defined as Vg at which Id = 10−12 A and ΔVth is defined as the Vth shift from the initial value via BTS. As shown in Fig. 6b, ΔVth increases logarithmically with increasing tS: ΔVth = 2.17 + 4.93 × log (tS). The mechanism behind the gate-stress-induced Vth shift is electron tunnel injection from the a-Si:H semiconductor into the SiOx gate insulator. For confirmation, ΔVth of MNOS TFTs with different SiOx thicknesses is plotted as a function of the electric field applied to the SiOx layer in Fig. 6c. Here, the thickness of the SiOx was varied (5, 10, 20, 50 nm), while the SiN thickness was fixed at 200 nm. The electric field applied to SiOx, Eox, was calculated using the following equation,

Effect of bias temperature stress (BTS) on TFT characteristics. (a) The transfer (Id–Vg) curve shifts in the positive direction with positive gate bias stress of Vst = + 77 V over the duration of 0–3600 s. (b) ΔVth, defined as the Vth shift from the initial value via BTS, increases logarithmically with increasing tS, following ΔVth = 2.17 + 4.93 × log (tS). (c) ΔVth of MNOS TFTs with different SiOx thicknesses from 5 to 50 nm as a function of the electric field applied to the SiOx layer.

Figure 7a shows the effect of back-channel oxidation (BCO) and passivation (PAS) on the Id-Vg characteristics of the MNOS TFT. The Id-Vg curve with Vth = 5.1 V is further enhanced to Vth = 10.9 V after BCO, although there is a slight degradation of the slope of the current increase in the sub-threshold region. The slope recovers after PAS without any change to the enhanced characteristics

(a) Effect of back-channel oxidation (BCO) and passivation (PAS) on Id–Vg characteristics of MNOS TFT. (b) Vth and Vth standard deviation, σVth, after BTS and after BCO without BTS treatments and (c) SiOX thickness as a function of position along gate-line, x.

The advantage of BCO over BTS is the uniformity of the enhanced characteristics; Fig. 7b shows the distribution of the enhanced Vth as a function of position along gate-line, x, for the MNOS TFTs connected with a 90-mm-long gate line in the TFT substrate after BTS and BCO treatments. The average value of Vth and the standard deviation, σVth, for pristine TFTs before BTS or BCO, are 5.1 V and 0.35 V, respectively. After BCO, Vth is uniformly enhanced, with an average Vth = 11 V and σVth = 0.4 V without increasing σVth. On the other hand, after BTS, Vth is nonuniformly enhanced with an average Vth = 9.3 V and σVth of 1.4 V. In particular, Vth increases linearly as a function of position along gate-line, x. As the gate SiOx thickness linearly decreases, from (54 nm) to (47 nm) with increasing x as shown in Fig. 7c, the increase in ΔVth after BTS with x is due to increase in the electric field applied to SiOx as shown in Fig. 6c and Eq. 1.

It has been shown that the Vth of the MNOS TFT is independent of the gate SiOx thickness when the thickness is more than 5 nm8a, Vth of the MNOS TFT with the BCO treatment becomes almost independent of the BCO SiOx thickness. As shown in the inset, the thickness of BCO SiOx composed of oxidized a-Si:H linearly increases with BCO processing time, and the Vth increase almost saturates at a BCO SiOx thickness greater than 5 nm. Therefore, the enhanced MNOS TFT after BCO has a uniformly high Vth that is robust to thickness fluctuations of the gate and BCO SiOx layers. BCO also has an advantage over BTS in terms of the stability of Vth as shown in Fig. 8b, which plots the annealing time dependence of Vth for BCO and BTS. In this experiment, the stoichiometry (x) of the gate SiOx was 1.78 for BTS and 1.78 and 1.9 for BCO. The annealing temperature in the N2 atmosphere was 200 °C. In the case of BTS, Vth decreased to the pristine value after approximately 5 h of annealing, while Vth decreased more slowly in the case of BCO. In particular, the annealing time required for Vth to fall to 7 V was 7.5 times longer than that of BTS. Increasing the stoichiometry (x) of the gate SiOx dramatically improved the BCO-enhanced Vth to as much as 11 V, which was stably maintained after 24 h of annealing at 200 °C.

(a) Dependence of Vth on thickness of back-channel oxidized (BCO) SiOX. The inset shows the SiOx thickness dependence on the BCO process time for RF powers of 200 W and 500 W. (b) Stability of Vth as a function of annealing time for three different TFTs with gate SiOx stoichiometry, x = 1.78 and bias temperature stress (BTS), x = 1.78 and BCO, and x = 1.9 and BCO. The temperature of annealing in the N2 atmosphere was 200 °C. (c) Band diagram of back-channel oxidized MNOS TFT. The red arrows show the electric dipoles at the SiOX/a-Si:H and a-Si:H/BCO SiOX interfaces.

A schematic band model for the MNOS TFT with the BCO treatment and the sectional structure of the interface between the a-Si:H and gate and BCO SiOx are shown in Fig. 8c. The uniformly high Vth that is independent of SiOx thickness is due to the dipoles generated at the channel and back-channel interfaces between a-Si:H and SiOx8 of reference

tft lcd displays matrix lcds quotation

TFT displays have become increasingly common in our daily lives. They are used in cars, laptops, tablets, and smartphones, as well as in industrial applications and many more. But what are TFT displays and why are they so important?

A TFT (Thin Film Transistor) display is a type of display technology that uses a thin layer of transparent material to produce an image on the screen. The display is made up of thin layers of organic material called organic transistors, which are stacked together on a glass substrate and covered with a thin layer of plastic or metal oxide.

TFT displays are also used in many other industrial applications, such as industrial control systems, medical devices, automotive infotainment systems, and more.

The basic concept behind a TFT display is simple: it uses light to create an image on a screen. Light passes through the glass substrate and the organic transistors until it reaches the top layer of the display.

The basic design of a TFT display has remained unchanged for more than 20 years. In this design, the sub-pixels are arranged in a grid pattern, with each subpixel connected to its neighbor by wires that form rows and columns.

In 1982, Sanyo introduced the world’s first 16-inch (40 cm) LCD with a resolution of 640×480 pixels. This was followed by the introduction of 30-inch (76 cm) screens in 1984 and 40-inch (100 cm) screens in 1985.

The first large format TFT display was introduced in 1987 by NEC Corporation, which used a 1024×768 pixel screen for its PC monitor line, called CRT Professional Display System or “Videotronic” system. The technology was licensed to NEC’s competitors such as Hitachi and Toshiba for use in their own monitors and televisions. The system was marketed as “Super Video” and replaced the aging “Videotron” CRT monitors that were still being used at the time. The first LCD TV was also produced in 1987 by Sony.

In 1989, Sharp’s first TFT-LCD TV set was introduced with a resolution of 576×320 pixels, while the world’s first large format high definition screen with a resolution of 1024×768 pixels was introduced by NEC in 1994.

Over the years, TFT display technology has developed by leaps and bounds. It has been used in tablets, smartphones, notebooks, game consoles, and computer monitors. The technology is also used in digital cameras, camcorders, MP3 players, and GPS devices.

What does the TFT display technology comprise? From far, you can easily assume TFT to be a single unit. But in reality, it comprises different components that work together.

The backlight of the TFT display is a very important component. It provides the light for the pixels and is also responsible for illuminating the display. The light emitted by a backlight can be controlled by varying the amount of current running through it.

When it comes to LCD displays, there are two types of backlights; Active matrix and Passive matrix. Active matrix backlight has several layers of electrodes, which are used to control the amount of current flowing through them.

Whereas, Passive matrix backlight consists of one electrode layer that acts as a switch between off and on states. The active matrix backlights are more expensive than passive-matrix ones because they require more power to operate.

The pixel is the smallest unit in a TFT display. It is the basic unit of information that is displayed on the screen. The pixel consists of three sub-elements, namely; Red, Green, and Blue (RGB).

The number of sub-pixels that are used in each pixel varies with different display technologies. In full-color LCDs, there are three types of sub-pixel: red, green, and blue (RGB). Full color TFT displays use a combination of Red, Green, and Blue (RGB) sub-pixels to represent full color.

The light that is transmitted through each TFT is controlled by applying voltages of different values to each pixel in turn. To do this, a control circuit called a driver circuit is required. The driver circuit controls the voltage applied to each pixel with reference to a set of parameters known as “pixel information”.

The control system can be further divided into 3 sub-systems: the interface, the timing, and the data transfer system (DTS). These systems work together to provide all of the necessary functions for controlling TFT displays from external sources such as computers, printers, or TVs.

This is another component of a TFT display system. It consists of a liquid crystal material sandwiched between two glass plates. This material is responsible for controlling the light by changing its refractive index.

-Wide viewing angle: The viewing angle of the TFT display is larger than that of the CRT set. It is generally considered to be the best choice for applications requiring an extended viewing angle.

-Transparency: TFT display has better transparency than CRT set, which makes it more suitable for applications requiring high transparency such as window displays and computer monitors.

-High resolution: TFT display can produce higher resolution than CRT display. For example, the pixel density of TFT is about 3 million pixels per square inch (PPI), which is about three times that of conventional liquid crystal displays (LCDs) whose pixel density is about 100 ppi.

-Reliability: Since it uses no moving parts, the TFT screen does not need any maintenance or repair, and therefore the reliability is higher than that of LCDs and plasma displays.

-Power saving: TFT display consumes much less power than CRT. The power consumption of a mainstream TFT display is about 1/10 that of a typical LCD. In some applications, the power consumption can be reduced to 1/100 or less of that of a CRT.

-Compatibility: Since it uses no moving parts, the TFT screen does not have any mechanical problems such as screen flicker and image sticking problems found in plasma displays and LCDs.

-High resolution: Although the pixel density of TFT is about 3 million pixels per square inch (ppi), the resolution is more than 100 ppi which makes it more suitable for many applications where high resolution is needed.

-Consistency: Since it uses no moving parts, the image displayed on the TFT display is not affected by temperature and humidity, which makes it more consistent than LCDs and plasma displays.

-Cost: The cost of a TFT display is lower than that of LCDs and plasma displays. For example, in some applications where image quality is not critical, the cost of a TFT display may be only a few tens to a few hundreds of dollars while the cost of LCDs or plasma displays may be several thousand to several tens of thousands.

-Excellent color display: We can’t deny the fact that TFTs have a superior color display. This simply means that the color of pixels can be accurately reproduced.

-Very thin: When compared with LCDs and plasma displays, which are very thick, TFTs are very thin and lightweight. In addition, the cost of mounting a large size TFT screen to a wall panel is relatively low.

-No ghosting: ‘Ghosting’ refers to the fact that the display shows a bright spot on the screen when the screen is turned off. TFT screens do not show ghosting. TFTs produce a sharp image even when they are turned off.

-No geometric distortion: Geometric distortion refers to the shape of the display on a flat surface. TFTs produce a sharp image even when they are turned off.

-No radiation: TFTs do not emit any harmful radiation, and there is no need for shielding or shielding materials to protect people from harmful radiation.

Considering that TFTs use less power, it is possible to reduce energy consumption by up to 50% compared with LCDs. In addition, if you use LED backlights in TFT displays, you can reduce power consumption by up to 75% compared with conventional backlights.

If a product uses a backlight, there is a high possibility that the color of the screen will be affected after some time due to dust or dirt that comes into contact with it. But it is possible to prevent this problem by using TFTs with LED backlights, which have no problems such as those caused by dust and dirt.

Workability refers to the ease with which you can operate a product. When working with a screen that has TFTs, it is possible to increase the amount of information that can be displayed at one time. It is also possible to reduce the number of times you must change settings on a product by increasing its usability.

Design refers to what you can create with the use of a product. Using TFTs, it is possible to create products that have a thin profile and are lightweight, which makes them more convenient for transportation and storage.

Human interface refers to what you touch when using a product or what you see on the screen when using a product (e.g., buttons and other controls). By integrating the TFTs into the display part of a product, it is possible to make the human interface easier.

Amoled refers to a technology that replaces the traditional liquid crystal display (LCD) with an organic light-emitting diode (OLED). Modern TFTs are similar to Amoled in terms of their structure, but they differ from Amoled in terms of their performance.

The TFTs of the present invention have superior characteristics compared to Amoled, such as high contrast ratio and response speed. The TFTs also have superior characteristics compared to conventional display devices such as CRT and plasma display panels, which cannot be achieved by these conventional display devices.

IPS refers to a technology that replaces the traditional liquid crystal display (LCD) with in-plane switching technology. The IPS display has superior features to TFT due to its high contrast ratio, wide viewing angle, and high response speed.

There are certain limitations to TFTs. For example, there is a limit to the size of the display and the resolution of the image that can be displayed on a display. Also, because TFTs are considered to be a kind of organic semiconductor displays, they have a short life span and therefore need frequent replacement.

Because of their high resolution, TFT displays are used in display monitors. The type of TFT used in display monitors can be categorized as either active matrix or passive matrix. Active matrix TFTs use a thin film transistor (TFT) as its active component, whereas passive matrix uses a liquid crystal display (LCD).

TFTs are also being used in portable electronic devices such as mobile phones, personal digital assistants (PDAs), and cameras. These devices require high-resolution screens because the user must be able to view accurate images and text on the screen. TFTs are also being used in laptops, which have a much larger screen size than many other portable electronic devices.

Because of their size and high resolution, laptop computers use passive matrix TFT displays instead of LCDs for larger displays than those found on smaller-sized portable electronics devices that use LCDs for their displays (e.g., mobile phones and PDAs).

TFT displays are used in front-projection TVs. The type of TFT used in front-projection TVs can be categorized as either active matrix or passive matrix. Active matrix TFTs use a thin film transistor (TFT) as its active component, whereas passive matrix uses a liquid crystal display (LCD).

Head-mounted displays (HMDs) use liquid crystal on silicon technology to create small, inexpensive, low-power VR headsets that can be worn on the head. Some HMDs use active matrix TFT technology while others use passive matrix TFT technology. Active matrix HMDs use shorting bars or glass electrodes to control each pixel; passive matrix HMDs use a liquid crystal material that allows for the creation of an image by controlling the voltage applied to each pixel.

TFTs are used in projectors to create the on-screen image from the input signal. TFTs are used in both active matrix and passive matrix projectors. Active matrix projectors use shorting bars or glass electrodes to control each pixel, while passive matrix projectors use a liquid crystal material that allows for the creation of an image by con

tft lcd displays matrix lcds quotation

You Might Also Be Interested In