tft vs lcd display in mobile quotation

IPS (In-Plane Switching) lcd is still a type of TFT LCD, IPS TFT is also called SFT LCD (supper fine tft ),different to regular tft in TN (Twisted Nematic) mode, theIPS LCD liquid crystal elements inside the tft lcd cell, they are arrayed in plane inside the lcd cell when power off, so the light can not transmit it via theIPS lcdwhen power off, When power on, the liquid crystal elements inside the IPS tft would switch in a small angle, then the light would go through the IPS lcd display, then the display on since light go through the IPS display, the switching angle is related to the input power, the switch angle is related to the input power value of IPS LCD, the more switch angle, the more light would transmit the IPS LCD, we call it negative display mode.

The regular tft lcd, it is a-si TN (Twisted Nematic) tft lcd, its liquid crystal elements are arrayed in vertical type, the light could transmit the regularTFT LCDwhen power off. When power on, the liquid crystal twist in some angle, then it block the light transmit the tft lcd, then make the display elements display on by this way, the liquid crystal twist angle is also related to the input power, the more twist angle, the more light would be blocked by the tft lcd, it is tft lcd working mode.

A TFT lcd display is vivid and colorful than a common monochrome lcd display. TFT refreshes more quickly response than a monochrome LCD display and shows motion more smoothly. TFT displays use more electricity in driving than monochrome LCD screens, so they not only cost more in the first place, but they are also more expensive to drive tft lcd screen.The two most common types of TFT LCDs are IPS and TN displays.

tft vs lcd display in mobile quotation

• Set up, feed and operate screen presses efficiently referencing blueprints and job jackets, while maintaining high quality and performance standards.

• Dexterity and Arm-Hand Steadiness – ability to quickly move hands, arms, fingers to grasp, manipulate or assemble and the ability to keep hand and arm steady.

tft vs lcd display in mobile quotation

The TFT-LCD (Flat Panel) Antitrust Litigationclass-action lawsuit regarding the worldwide conspiracy to coordinate the prices of Thin-Film Transistor-Liquid Crystal Display (TFT-LCD) panels, which are used to make laptop computers, computer monitors and televisions, between 1999 and 2006. In March 2010, Judge Susan Illston certified two nationwide classes of persons and entities that directly and indirectly purchased TFT-LCDs – for panel purchasers and purchasers of TFT-LCD integrated products; the litigation was followed by multiple suits.

TFT-LCDs are used in flat-panel televisions, laptop and computer monitors, mobile phones, personal digital assistants, semiconductors and other devices;

In mid-2006, the U.S. Department of Justice (DOJ) Antitrust Division requested FBI assistance in investigating LCD price-fixing. In December 2006, authorities in Japan, Korea, the European Union and the United States revealed a probe into alleged anti-competitive activity among LCD panel manufacturers.

The companies involved, which later became the Defendants, were Taiwanese companies AU Optronics (AUO), Chi Mei, Chunghwa Picture Tubes (Chunghwa), and HannStar; Korean companies LG Display and Samsung; and Japanese companies Hitachi, Sharp and Toshiba.cartel which took place between January 1, 1999, through December 31, 2006, and which was designed to illegally reduce competition and thus inflate prices for LCD panels. The companies exchanged information on future production planning, capacity use, pricing and other commercial conditions.European Commission concluded that the companies were aware they were violating competition rules, and took steps to conceal the venue and results of the meetings; a document by the conspirators requested everybody involved "to take care of security/confidentiality matters and to limit written communication".

This price-fixing scheme manipulated the playing field for businesses that abide by the rules, and left consumers to pay artificially higher costs for televisions, computers and other electronics.

Companies directly affected by the LCD price-fixing conspiracy, as direct victims of the cartel, were some of the largest computer, television and cellular telephone manufacturers in the world. These direct action plaintiffs included AT&T Mobility, Best Buy,Costco Wholesale Corporation, Good Guys, Kmart Corp, Motorola Mobility, Newegg, Sears, and Target Corp.Clayton Act (15 U.S.C. § 26) to prevent Defendants from violating Section 1 of the Sherman Act (15 U.S.C. § 1), as well as (b) 23 separate state-wide classes based on each state"s antitrust/consumer protection class action law.

In November 2008, LG, Chunghwa, Hitachi, Epson, and Chi Mei pleaded guilty to criminal charges of fixing prices of TFT-LCD panels sold in the U.S. and agreed to pay criminal fines (see chart).

The South Korea Fair Trade Commission launched legal proceedings as well. It concluded that the companies involved met more than once a month and more than 200 times from September 2001 to December 2006, and imposed fines on the LCD manufacturers.

Sharp Corp. pleaded guilty to three separate conspiracies to fix the prices of TFT-LCD panels sold to Dell Inc., Apple Computer Inc. and Motorola Inc., and was sentenced to pay a $120 million criminal fine,

Chunghwa pleaded guilty and was sentenced to pay a $65 million criminal fine for participating with LG and other unnamed co-conspirators during the five-year cartel period.

In South Korea, regulators imposed the largest fine the country had ever imposed in an international cartel case, and fined Samsung Electronics and LG Display ₩92.29 billion and ₩65.52 billion, respectively. AU Optronics was fined ₩28.53 billion, Chimmei Innolux ₩1.55 billion, Chungwa ₩290 million and HannStar ₩870 million.

Seven executives from Japanese and South Korean LCD companies were indicted in the U.S. Four were charged with participating as co-conspirators in the conspiracy and sentenced to prison terms – including LG"s Vice President of Monitor Sales, Chunghwa"s chairman, its chief executive officer, and its Vice President of LCD Sales – for "participating in meetings, conversations and communications in Taiwan, South Korea and the United States to discuss the prices of TFT-LCD panels; agreeing during these meetings, conversations and communications to charge prices of TFT-LCD panels at certain predetermined levels; issuing price quotations in accordance with the agreements reached; exchanging information on sales of TFT-LCD panels for the purpose of monitoring and enforcing adherence to the agreed-upon prices; and authorizing, ordering and consenting to the participation of subordinate employees in the conspiracy."

On December 8, 2010, the European Commission announced it had fined six of the LCD companies involved in a total of €648 million (Samsung Electronics received full immunity under the commission"s 2002 Leniency Notice) – LG Display, AU Optronics, Chimei, Chunghwa Picture and HannStar Display Corporation.

On July 3, 2012, a U.S. federal jury ruled that the remaining defendant, Toshiba Corporation, which denied any wrongdoing, participated in the conspiracy to fix prices of TFT-LCDs and returned a verdict in favor of the plaintiff class. Following the trial, Toshiba agreed to resolve the case by paying the class $30 million.

On March 29, 2013, Judge Susan Illston issued final approval of the settlements agreements totaling $1.1 billion for the indirect purchaser’ class. The settling companies also agreed to establish antitrust compliance programs and to help prosecute other defendants, and cooperate with the Justice Department"s continuing investigation.

tft vs lcd display in mobile quotation

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.

In-plane switching was developed by Hitachi Ltd. in 1996 to improve on the poor viewing angle and the poor color reproduction of TN panels at that time.

Initial iterations of IPS technology were characterised by slow response time and a low contrast ratio but later revisions have made marked improvements to these shortcomings. Because of its wide viewing angle and accurate color reproduction (with almost no off-angle color shift), IPS is widely employed in high-end monitors aimed at professional graphic artists, although with the recent fall in price it has been seen in the mainstream market as well. IPS technology was sold to Panasonic by Hitachi.

Most panels also support true 8-bit per channel color. These improvements came at the cost of a higher response time, initially about 50 ms. IPS panels were also extremely expensive.

IPS has since been superseded by S-IPS (Super-IPS, Hitachi Ltd. in 1998), which has all the benefits of IPS technology with the addition of improved pixel refresh timing.

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.

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.

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

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.

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.

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.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

Richard Ahrons (2012). "Industrial Research in Microcircuitry at RCA: The Early Years, 1953–1963". 12 (1). IEEE Annals of the History of Computing: 60–73. Cite journal requires |journal= (help)

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.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

tft vs lcd display in mobile quotation

Quote: Hi, I am wondering if you could send me some example prices if we ordered 2 or 3 sample displays, and what would be the price if we ordered 1000 peaces?

Leadtek is a professional LCD display supplier who has paid great efforts to research and development of TFT-LCM, especially on its application of consumable and industrial products. The sizes of LCM includes 1.4”, 2.4”, 3.5", 3.51", 4.3", 4", 5", 7", 8", 10.1” and 11.6". And among them the 3.5”, 4.3", 5", 7” and 10.1" LCM has achieved the leading level of the industry, and mainly applied to vehicle-applications, tablet PCs, smartphones, medical equipment, measurement equipment, E-books, EPC and industrial products, and provides powerful and reliable supports on supplies and qualities. We are cooperating with famous foreign companies on research and developments and will bring out the series products of the industrial control LCD display. Also, we explore the overseas market and build up a long-term relationship with our overseas partners and agents, Leadtek products will be worldwide in the near future.

tft vs lcd display in mobile quotation

Display size, contrast, color, brightness, resolution, and power are key factors in choosing the right display technology for your application. However, making the right choice in how you feed the information to the display is just as vital, and there are many interface options available.

All displays work in a similar manner. In a very basic explanation, they all have many rows and columns of pixels driven by a controller that communicates with each pixel to emit the brightness and color needed to make up the transmitted image. In some devices, the pixels are diodes that light up when current flows (PMOLEDs and AMOLEDs), and in other electronics, the pixel acts as a shutter to let some of the light from a backlight visible. In all cases, a memory array stores the image information that travels to the display through an interface.

According to Wikipedia, "an interface is a shared boundary across which two separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these. Some computer hardware devices such as a touchscreen can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system.” In other words, an interface is something that facilitates communication between two objects. Although display interfaces serve a similar purpose, how that communication occurs varies widely.

Serial Peripheral Interface (SPI) is a synchronous serial communication interface best-suited for short distances. It was developed by Motorola for components to share data such as flash memory, sensors, Real-Time Clocks, analog-to-digital converters, and more. Because there is no protocol overhead, the transmission runs at relatively high speeds. SPI runs on one master (the side that generates the clock) with one or more slaves, usually the devices outside the central processor. One drawback of SPI is the number of pins required between devices. Each slave added to the master/slave system needs an additional chip select I/O pin on the master. SPI is a great option for small, low-resolution displays including PMOLEDs and smaller LCDs.

Philips Semiconductors invented I2C (Inter-integrated Circuit) or I-squared-C in 1982. It utilizes a multi-master, multi-slave, single-ended, serial computer bus system. Engineers developed I2C for simple peripherals on PCs, like keyboards and mice to then later apply it to displays. Like SPI, it only works for short distances within a device and uses an asynchronous serial port. What sets I2C apart from SPI is that it can support up to 1008 slaves and only requires two wires, serial clock (SCL), and serial data (SDA). Like SPI, I2C also works well with PMOLEDs and smaller LCDs. Many display systems transfer the touch sensor data through I2C.

RGB is used to interface with large color displays. It sends 8 bits of data for each of the three colors, Red Green, and Blue every clock cycle. Since there are 24 bits of data transmitted every clock cycle, at clock rates up to 50 MHz, this interface can drive much larger displays at video frame rates of 60Hz and up.

Low-Voltage Differential Signaling (LVDS) was developed in 1994 and is a popular choice for large LCDs and peripherals in need of high bandwidth, like high-definition graphics and fast frame rates. It is a great solution because of its high speed of data transmission while using low voltage. Two wires carry the signal,  with one wire carrying the exact inverse of its companion. The electric field generated by one wire is neatly concealed by the other, creating much less interference to nearby wireless systems. At the receiver end, a circuit reads the difference (hence the "differential" in the name) in voltage between the wires. As a result, this scheme doesn’t generate noise or gets its signals scrambled by external noise. The interface consists of four, six, or eight pairs of wires, plus a pair carrying the clock and some ground wires. 24-bit color information at the transmitter end is converted to serial information, transmitted quickly over these pairs of cables, then converted back to 24-bit parallel in the receiver, resulting in an interface that is very fast to handle large displays and is very immune to interference.

Mobile Industry Processor Interface (MIPI) is a newer technology that is managed by the MIPI Alliance and has become a popular choice among wearable and mobile developers. MIPI uses similar differential signaling to LVDS by using a clock pair and one to eight pairs of data called lanes. MIPI supports a complex protocol that allows high speed and low power modes, as well as the ability to read data back from the display at lower rates. There are several versions of MIPI for different applications, MIPI DSI being the one for displays.

Display components stretch the limitations of bandwidth. For perspective, the most common internet bandwidth in a residential home runs on average at around 20 megabits per second or 20 billion 1s and 0s per second. Even small displays can require 4MB per second, which is a lot of data in what is often a tightly constrained physical space.

To give an example, a small monochrome PMOLED with a resolution of 128 x 128 contains 16,384 individual diodes. A still image of various diodes carrying current represents a frame. A frame rate is the number of times that a picture needs refreshing. Most videos have a frame rate of 60 fps (frames per second), which means that it is updated 60 times every second.

Take the same PMOLED display with the 128 x 128 resolution and 16,384 separate diodes; it requires information as to when and how brightly to illuminate each pixel. For a display with only 16 shades, it takes 4 bits of data. 128 x 128 x 4 = 65,536 bits for one frame. Now multiply it by the 60Hz, and you get a bandwidth of 4 megabits/second for a small monochrome display.

tft vs lcd display in mobile quotation

This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data.

tft vs lcd display in mobile quotation

This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data.

tft vs lcd display in mobile quotation

Liquid Crystal Display (LCD) screens are a staple in the digital display marketplace and are used in display applications across every industry. With every display application presenting a unique set of requirements, the selection of specialized LCDs has grown to meet these demands.

LCD screens can be grouped into three categories: TN (twisted nematic), IPS (in-plane switching), and VA (Vertical Alignment). Each of these screen types has its own unique qualities, almost all of them having to do with how images appear across the various screen types.

This technology consists of nematic liquid crystal sandwiched between two plates of glass. When power is applied to the electrodes, the liquid crystals twist 90°. TN (Twisted Nematic) LCDs are the most common LCD screen type. They offer full-color images, and moderate viewing angles.

TN LCDs maintain a dedicated user base despite other screen types growing in popularity due to some unique key features that TN display offer. For one,

TN TFTs remain very popular among competitive PC gaming communities, where accuracy and response rates can make the difference between winning and losing.

Refresh rates and response times refer to the time it takes pixels to activate and deactivate in response to user inputs; this is crucial for fast-moving images or graphics that must update as fast as possible with extreme precision.

VA, also known as Multi-Domain Vertical Alignment (MVA) dislays offer features found in both TN and IPS screens. The Pixels in VA displays align vertically to the glass substrate when voltage is applied, allowing light to pass through.

Displays with VA screens deliver wide viewing angles, high contrast, and good color reproduction. They maintain high response rates similar to TN TFTs but may not reach the same sunlight readable brightness levels as comparable TN or IPS LCDs. VA displays are generally best for applications that need to be viewed from multiple angles, like digital signage in a commercial setting.

IPS (In-Plane Switching) technology improves image quality by acting on the liquid crystal inside the display screen. When voltage is applied, the crystals rotate parallel (or “in-plane”) rather than upright to allow light to pass through. This behavior results in several significant improvements to the image quality of these screens.

IPS is superior in contrast, brightness, viewing angles, and color representation compared to TN screens. Images on screen retain their quality without becoming washed out or distorted, no matter what angle they’re viewed from. Because of this, viewers have the flexibility to view content on the screen from almost anywhere rather than having to look at the display from a front-center position.

IPS displays offer a slightly lower refresh rate than TN displays. Remember that the time for pixels to go from inactive to active is measured in milliseconds. So for most users, the difference in refresh rates will go unnoticed.

Based on current trends, IPS and TN screen types will be expected to remain the dominant formats for some time. As human interface display technology advances and new product designs are developed, customers will likely choose IPS LCDs to replace the similarly priced TN LCDs for their new projects.

tft vs lcd display in mobile quotation

When the frame rate is 16 FPS, the human eye will think that the image is coherent, and a higher frame rate can get smoother and more realistic animation. Generally, 25 to 30 FPS is acceptable, but increasing the frame rate to 60 FPS can significantly improve the sense of interaction and realism.

At present, most video frame rates are less than 60FPS, so the refresh rate of the mobile phone screen should not be less than 60Hz. In theory, the higher the refresh rate, the more delicate and smooth the screen display and operation, so many flagship phones currently use 90Hz or even 120Hz refresh rates.

If we look at the mobile phone posters, we can find that there are many different terms about screen materials and technologies: TFT LCD, TFT, IPS, LTPS, OLED, AMOLED, etc., which are dazzling.

The three primary colors of light are red, green, and blue. By mixing these three colors in different proportions, almost all colors in nature can be obtained. Therefore, each pixel on the mobile phone screen is also composed of a mixture of these three colors.

In LCD technology, although the word “liquid crystal” is very conspicuous, the liquid crystal does not emit light. A backplane composed of LEDs (light-emitting diodes) is needed to provide a white light source, also called “Backlight”.

On the basis of the backlight for each pixel, a layer of red, green, and blue films is added. White light passing through these films becomes colored light of red, green, and blue.

But if the intensities of these three types of light are the same, they will become white or grey when mixed. Therefore, the intensity of each light must be flexibly controlled to mix multiple colors.

At this time, it is the turn of the liquid crystal material to appear. Liquid crystal has a characteristic, that is, under the action of an electric field, its molecular arrangement will change, which will affect the permeability of light. Changing the voltage can adjust the amount of light transmitted.

For LCD screens, the liquid crystal layer sandwiched between the backlight and the film adjusts the passable light by adjusting the input voltage. After passing through the colored film, the three primary colors of light with different intensities can be obtained. After mixing, thousands of colors will be obtained.

The so-called TFT (Thin-film transistor) refers to the thin film transistor array on the glass substrate of the liquid crystal panel, which allows each pixel of the LCD to be equipped with its own semiconductor switch, thereby achieving independent and precise control of “point-to-point”.

Therefore, the main LCD screen is also called a TFT-LCD. However, IPS and LTPS are actually implemented by different technologies under TFT-LCD, so we won’t repeat them here.

The structure of the OLED screen is much simpler than that of the LCD. It does not require a backlight, nor does it have a liquid crystal or color filter film. The internal organic material coating is like a small colored light bulb, which can emit light when it is powered on.

AMOLED: Everyone already knows about OLED. The previous AM refers to the driving method of OLED. Its full name is Active Matrix. TFT is usually used as a switch to control the current through organic materials to achieve different colors. All OLEDs currently used in mobile phones are AMOLED, so it can be considered that the two are the same thing.

Super AMOLED: Samsung’s improvement to AMOLED, canceled the middle touch sensor panel, and built the AMOLED sensor layer on the screen, so the control is more sensitive, thinner, and brighter, and the presentation effect in the sun is better.

Dynamic AMOLED: It is also the AMOLED improved technology launched by Samsung, currently mainly used in high-end devices. This technology changes the organic materials in OLEDs and is said to achieve a wider dynamic range. When the image contrast is high, it can display more dark details.

Because the liquid crystal layer cannot be completely closed, some backlight will always pass through, so the LCD cannot display pure black, only dark grey. And OLED can realize a pure black display by controlling the switch of each pixel.

The backlight of the LCD screen can easily leak from the screen and the frame of the mobile phone to form a light leakage phenomenon. This phenomenon is very common in the era of rough mobile phone workmanship, and it is rarely seen now.

LCD is limited by the backlight layer and liquid crystal layer due to its complex technology, and the screen thickness is much larger than that of OLED. Of course, this thickness is not worth mentioning on the TV, but in the mobile phone, where the pursuit of slimness and extremely limited internal space, the screen is thinner, and more other components can be plugged in to improve other performance.

Since the LCD screen has a backlight, it must be fully lit when in use, and OLED can individually control the switch of each pixel, so the power consumption of the LCD screen is much greater than that of OLED. In the picture below, Smartisan R1 and Xiaomi mix2s are both LCD screens, and battery life is obviously at a disadvantage under long-term video play.

Due to the long response time of the LCD screen, smear will occur when the screen slides quickly. The OLED responds quickly, clean, and without smear.

Because the organic material used in the OLED screen will be aging faster if there is a large pixel workload, some are relatively idle, there will be an inconsistent degree of aging of the entire screen, resulting in different areas of color display deviation. This phenomenon is called burning the screen.

Burn-in is the shortcoming of the OLED screen. For LCD, the backlight is fully lit, and the aging time of LCD is longer, so there is basically no problem of burn-in.

For LCD, to control the screen brightness, you can directly adjust the brightness of the backlight. But OLED is more troublesome. It needs to switch the screen at high frequency to achieve dimming. If you want to brighten, you turn on the screen more times, and if you want to dim, you turn off the screen more times.

Since the time for switching the screen each time is very short, although the human eye cannot perceive the change of the screen each time, it can feel the average brightness and darkness over a period of time, thus achieving the effect of dimming.

For example, to achieve a brightness of 50%, it takes half the time to turn on the screen and half the time to turn off the screen. At a lower brightness, it takes longer to turn off the screen. The screen flashes once and again, and it can even be visible to the naked eye,then the eyes will be very uncomfortable.

This phenomenon of OLED is called a strobe, hence the name “eye-damaging screen”. In contrast, LCD screens generously call themselves “eye protection screens.”

Although there are shortcomings, the shortcomings do not conceal the advantages. At present, the OLED display has entered the mainstream and gradually occupies the market space of LCD display. This is especially obvious in high-end mobile phones.

tft vs lcd display in mobile quotation

Displays are a standard component of almost any device, application or machine. From the simple monochrome LCD character display used in portable testing equipment, to full colour graphic TFT screens used for infotainment, we have become well accustomed to the visual display of information and messages. Each area of application has specific requirements for its displays, and Telerex has a range of display technologies and product lines from trusted suppliers.

Both character and graphic LCD displays use only a moderate amount of electricity and take up only a moderate amount of space, and are therefore very suited to mobile applications on batteries. In TFT displays every pixel is directed by a tiny semiconductor that controls the amount of light that is allowed to pass through, which results in better resolution, contrast, and speed. With OLED displays a major step has been taken thanks to their very clear resolution, high contrast, wide viewing angle, and significantly lower power consumption. Finally, e-Paper displays provide the ideal solution for applications such as e-readers, interactive billboards, and interactive price tags in supermarkets, for which power consumption is critical and the display must remain static for a long period of time.

tft vs lcd display in mobile quotation

When we purchase a new smartphone we go through a list of specifications that includes the processor, software, cameras, display type, battery, etc. The display of the smartphone is something which has always been a concern for people. And smartphone technology has advanced so much in the past decade that you get several display technology options to choose from.

Today, a smartphone is not just a means to send and receive calls and texts. It has become a general necessity, so choosing the right technology should be your main priority. Coming back to displays, as we said there are plenty of display types available right now.

Two of the main contenders for display technologies that are widely available are AMOLED and LCD. Here in this article, we will be comprising AMOLED vs LCD and find out which one is better for you.

Starting with the AMOLED first, it is a part of the OLED display technology but with some more advanced features. To completely know about it must understand its all three components. The first one is LED, “Light Emitting Diode”. Then we have “O” which stands for organic and makes the OLED.

It actually means that organic material is placed with two conductors in each LED, which helps to produce the light. And the “AM” in AMOLED means Active Matrix, it has the capability to increase the quality of a pixel.

The AMOLED display is similar to the OLED in various factors like high brightness and sharpness, better battery life, colour reproduction, etc. AMOLED display also has a thin film transistor, “TFT” that is attached to each LED with a capacitor.

TFT helps to operate all the pixels in an AMOLED display. This display might have a lot of positives but there are a few negatives too let’s point both of them out.

It comes with individual LEDs so, the pixels can be turned on and off individually. This will show you true black colours, as the pixels on the black part of the image will be turned off.

A major issue with these displays is of burning of pixels. After showing a specific image or colour for a longer period of time, the pixel can get burned. And if there is a problem with a single pixel it will affect the entire display.

Low outdoor visibility, usually the AMOLED Displays are quote not bright in direct sunlight and outdoor readability could be a problem for some devices but average screen brightness.

The LCD stands for “Liquid Crystal Display”, and this display produces colours a lot differently than AMOLED. LCD display uses a dedicated backlight for the light source rather than using individual LED components.

The LCD displays function pretty simply, a series of thin films, transparent mirrors, and some white LED lights that distributes lights across the back of the display.

As we have mentioned, an LCD display always requires a backlight and also a colour filter. The backlight must have to pass through a thin film transistor matrix and a polarizer. So, when you see it, the whole screen will be lit and only a fraction of light gets through. This is the key difference comparing AMOLED vs LCD and this is what differentiates these two display technologies.

The LCD displays are cheaper compared to the AMOLED as there is only one source of light which makes it easier to produce. Most budget smartphones also use LCD displays.

LCD displays have bright whites, the backlight emits lots of light through pixels which makes it easy to read in outdoors. It also shows the “Accurate True to Life” colours, which means it has the colours that reflect the objects of the real world more accurately than others.

LCDs also offer the best viewing angle. Although it may depend on the smartphone you have. But most high-quality LCD displays support great viewing angles without any colour distortion or colour shifting.

The LCD displays can never show the deep blacks like AMOLED. Due to the single backlight, it always has to illuminate the screen making it impossible to show the deep blacks.

The LCDs are also thicker than other displays because of the backlight as it needs more volume. So, LCD smartphones are mostly thicker than AMOLED ones.

Both of these display technologies have their own Pros and Cons. Taking them aside everything ends up with the user preferences as people might have different preferences among different colours and contrast profiles. However, a few factors might help you to decide which one fits perfectly for you.

Let’s start with the pricing. Most AMOLED display smartphones always cost more than an LCD smartphone. Although the trend is changing a bit. But still, if you want to get a good quality AMOLED display you have to go for the flagship devices.

The colors are also very sharp and vibrant with the AMOLED displays. And they look much better than any LCD display. The brightness is something where LCDs stood ahead of the AMOLED display. So using an LCD display outdoors gives much better results.

The last thing is battery consumption, and there is no one near the AMOLED displays in terms of battery. As of now, all smartphones feature a Dark Mode and most of the apps and UI are dark black with a black background. This dark UI on smartphones doesn’t require any other light, it gives the AMOLED displays a boost in battery performance.

Looking at all these factors and comparing AMOLED vs LCD displays, the AMOLED displays are certainly better than the LCDs. Also, the big display OEMs, like Samsung and LG are focusing more the OLED technologies for their future projects. So, it makes sense to look out for AMOLED displays. That being said, if we see further enhancements in the LCD technology in terms of battery efficiency and more, there is no point to cancel them at this moment.

tft vs lcd display in mobile quotation

TFT LCD monitors are susceptible to glare and reflection from direct sunlight or high-bright applications. In almost all TFT LCDs there is an air gap between the TFT panel and the cover lens. Having an air gap causes repeat refraction between each component level of the display when in high-brightness installations. Reducing the reflection inside these components with optical bonding gives greater contrast and makes the screen more viewable in outdoor or high bright conditions without the need to increase the brightness of the screen itself.

Optical bonding is a process where a layer of resin is applied between the glass or touchscreen and TFT LCD TFT panel of a monitor, bonding them to make a solid laminate with no gaps or pockets of air. When choosing a screen for any project, you should evaluate the environment and operating conditions the screen will have to endure. Industrial grade screens and panel PCs are made rugged with all types of features available to withstand any type of application. One such feature available to consider is optical bonding.

Optical bonding is popular among the military, marine, medical, transportation and retail sectors whereby a higher performing display is required due to the harsh environments. Optical Bonding is suited to industries that tend to use rugged displays in high reliability environments or industries where displays need to be seen in high ambient light conditions. The process of Optical Bonding is particularly well suited and much more effective when applied to devices that operate outdoors or in heavily lighted environments.

When LCD displays are manufactured, including touchscreens, the front glass of the screen is layered onto the LCD module. This doesn’t present a problem in standard viewing environments, however in certain conditions, like with outdoor placement, the tiny gap between the 2 layers can impair viewing performance.

The display from an non-optically bonded monitor is created by the light of the LCD reflecting through the gap and then the outer glass of the screen. The light is interrupted and bends when it passes through the gap and glass of the screen and some of the light is actually reflected back to the LCD module, this is called refraction. This refraction through the layers impairs the intensity and clarity of the end image and thus lowers brightness and readability. By bonding the LCD module and glass together you remove the interruptions and chances for the light to be reflected back. More light gets through to the surface of the screen and therefore the image is brighter.

The same principle is applied when an external source of light hits the screen. With an non-bonded screen, the gap between the glass and LCD module creates opportunities for refraction which bounces external light back off the screen to the viewer as glare. When bonded together the light passes through the bonded layers and is absorbed somewhat into the screen. Optical bonding is therefore important in making screens sunlight readable.

The additional resin layer in optical bonding absorbs shock. This provides high durability for use in public access areas, factories, or other harsh environments.

The most obvious benefit to adding a resin bonding layer between the glass and LCD module is that it physically prevents dust and liquid ingress from getting between the two. The quality of manufacturing means that dust and water isn’t a big problem for screens in standard environments. What can be a problem however is condensation getting between the glass and LCD panel in environments with wide temperature ranges or fluctuating humidity. Condensation can cause screens to become foggy from moisture that penetrates the air gap. Again, the physical filling of the gap prevents this problem from arising. Optical bonding should therefore be considered for any outdoor application as well as indoor applications where consistent temperatures aren’t maintained.

A touch monitor with optical bonding maintains a more accurate touch response because the pressure is maintained through the substrate, rather than being delayed by a gap.

Assured Systems are partnered with design and manufacturers industrial displays with optically bonded touch screens request, their displays or touchscreen displays can be optically bonded to remove the air gap inside the screen. If you require an optically bonded display or optically bonded panel PC please get in touch with Assured Systems.

tft vs lcd display in mobile quotation

LCD stands for “Liquid Crystal Display” and TFT stands for “Thin Film Transistor”. These two terms are used commonly in the industry but refer to the same technology and are really interchangeable when talking about certain technology screens. The TFT terminology is often used more when describing desktop displays, whereas LCD is more commonly used when describing TV sets. Don’t be confused by the different names as ultimately they are one and the same. You may also see reference to “LED displays” but the term is used incorrectly in many cases. The LED name refers only to the backlight technology used, which ultimately still sits behind an liquid crystal panel (LCD/TFT).

As TFT screens are measured differently to older CRT monitors, the quoted screen size is actually the full viewable size of the screen. This is measured diagonally from corner to corner. TFT displays are available in a wide range of sizes and aspect ratios now. More information about the common sizes of TFT screens available can be seen in our section about resolution.

The aspect ratio of a TFT describes the ratio of the image in terms of its size. The aspect ratio can be determined by considering the ratio between horizontal and vertical resolution.

16:9 = wide screen formats such as 1920 x 1080 and 2560 x 1440. 16:9 is commonly used for multimedia displays and TV’s and is increasingly becoming the standard

Ultra-high resolution panels will offer varying aspect ratios including Ultra HD (3840 x 2160 = 16:9), 4K (4096 x 2160 = an odd 1:9:1 aspect ratio) and 5K (5120 x 2880 = 16:9)

The resolution of a TFT is an important thing to consider. All TFT’s have a certain number of pixels making up their liquid crystal matrix, and so each TFT has a “native resolution” which matches this number. It is always advisable to run the TFT at its native resolution as this is what it is designed to run at and the image does not need to be stretched or interpolated across the pixels. This helps keep the image at its most clear and at optimum sharpness. Some screens are better than others at running below the native resolution and interpolating the image which can sometimes be useful in games.

You generally cannot run a TFT at a resolution of above its native resolution although some screens have started to offer “Virtual” resolutions, for example “virtual 4k” where the screen will accept a 3840 x 2160 input from your graphics card but scale it back to match the native resolution of the panel which is often 2560 x 1440 in these examples. This whole process is rather pointless though as you lose a massive amount of image quality in doing so.

Make sure your graphics card can support the desired resolution of the screen you are choosing, and based on your uses. If you are a gamer, you may want to consider whether your graphics card can support the resolution and refresh rate you will want to use to power your screen. Also keep in mind whether you are planning to connect external devices and the resolution they are designed to run at. For instance if you have a 16:10 format screen and plan to use an external device which runs at 16:9, you will need to ensure the screen is able to scale the image properly and add black borders, instead of distorting the aspect ratio of the image.

Ultra-high resolutions must be thought of in a slightly different way. Ultra HD (3840 x 2160) and 4K (4096 x 2160) resolutions are being provided nowadays on standard screen sizes like 24 – 27” for instance. Traditionally as you increased the resolution of panels it was about providing more desktop real estate to work with. However, with those resolutions being so high, and the screen size being relatively small still, the image and text becomes incredibly small if you run the screen at normal scaling at those native resolutions. For instance imagine a 3840 x 2160 resolution on a 24” screen compared with 1920 x 1080. The latter would probably be considered a comfortable font size for most users. These ultra-high resolutions nowadays are about improving image clarity and sharpness, and providing a higher pixel density (measured as pixels per inch = PPI). In doing so, you can improve the sharpness and clarity of an image much like Apple have famously done with their “Retina” displays on iPads and iPhones. To avoid complications with tiny images and fonts, you will then need to enable scaling in your operating system to make everything easier to see. For instance if you enabled scaling at 150% on a 3840 x 2160 resolution, you would end up with a screen real estate equivalent to a 2560 x 1440 panel (3840 / 1.5 = 2560 and 2160 / 1.5 = 1440). This makes text much easier to read and the whole image a more comfortable size, but you then get additional benefits from the higher pixel density instead, which results in a sharper and crisper image.

Generally you will need to take scaling in to consideration when purchasing any ultra-high resolution screen, unless it’s of a very large size. The scaling ability does vary however between different operating systems so be careful. Apple OS and modern Windows (8 and 10) are generally very good at handling scaling for ultra-high res displays. Older operating systems are less capable and may sometimes be complicated. You will also find varying support from different applications and games, and often end up with weird sized fonts or sections that are not scaled up and remain extremely small. A “standard” resolution where you don’t need to worry about scaling might be simpler for most users.

More and more you will see resolutions referred to by their common HD equivalents, particularly when it comes to TV’s. HD content is based purely on the resolution of the source and is commonly defined by the number of pixels vertically in the resolution. i.e. a 720 HD source has 720 vertical pixels in it’s resolution and a 1080 will have 1080. On top of this, there are two ways of showing this content, either using a progressive scan (e.g. 1080p) or an interlaced scan (1080i).

To display this content of this type, your screen needs to be able to 1) handle the full resolution naturally within its native resolution, and 2) be able to handle either the progressive scan or interlaced signal over whatever video interface you are using. If the screen cannot support the full resolution, the image can still be shown but it will be scaled down by the hardware and you won’t be take full advantage of the high resolution content. So for a monitor, if you want to watch 1080 HD content you will need a monitor which can support at least a vertical resolution of 1080 pixels, e.g. a 1920 x 1080 monitor.

In today’s monitor market resolutions are being pushed even higher and we need to start thinking about them in a different way. See the subsequent sections on pixel pitch and PPI for more information on how we should think about resolution now.

This has given rise to modern Ultra HD standards and terms like 4K and 5K. Ultra HD is a term for monitors with a 3840 x 2160 resolution, that being four times the resolution of Full HD 1920 x 1080. Screens with this Ultra HD resolution are often referred to as “4K” as well, although strictly that should only be used for screens with 4092 x 2160 resolution (4K representing the vertical resolution here). There are also some 5K capable monitors produced which offer 5120 x 2880 resolution (5K here representing the vertical resolution). Please see the following sections which talk about Pixel Pitch and PPI and will help you understand these higher resolutions in more detail.

Unlike on CRT’s where the dot pitch is related to the sharpness of the image, the pixel pitch of a TFT is related to the distance between pixels. This value is fixed and is determined by the size of the screen and the native resolution (number of pixels) offered by the panel. Pixel pitch is normally listed in the manufacturers specification. Generally you need to consider that the ‘tighter’ the pixel pitch, the smaller the text will be, and potentially the sharper the image will be. To be honest, monitors are normally produced with a sensible resolution for their size and so even the largest pixel pitches return a sharp images and a reasonable text size. Some people do still prefer the larger-resolution-crammed-into-smaller-screen option though, giving a smaller pixel pitch and smaller text. It’s down to choice and ultimately eye-sight.

For instance you might see a 35″ ultra-wide screen with only a 2560 x 1080 resolution which would have a 0.3200 mm pixel pitch. Compare this to a 25″ screen with 2560 x 1400 resolution and 0.2162 mm pixel pitch and you can see there will be a significant different in font size and image sharpness. There are further considerations when it comes to the pixel pitch of ultra-high resolution displays like Ultra HD and 4K. See the section on PPI for more information.

Resolution is typically thought as a factor which determines the screen area or screen “real estate” you will have available. In years gone by as panel sizes increased, resolutions were increased as well and so bigger screens could offer you more desktop space to work with. Split-screen working and high resolution image work become more and more possible. This is fine up to a point, but pushing resolution for the purposes of delivering more desktop real-estate reaches a point where it becomes somewhat impractical for desktop monitors. For instance, a 40″ 3840 x 2160 resolution delivers a comfortable pixel pitch and font size natively (very similar to a 27″ at 2560 x 1440), so if you wanted a higher resolution than this you would have to increase the screen size again probably. You start to reach the point where sitting close to a screen so large becomes impractical.

Instead manufacturers are now focusing on delivering higher resolutions in to existing panel sizes, not for the purpose of providing more desktop real-estate, but for the purpose of improving image sharpness and picture quality. Apple started this trend with their “Retina Displays” used in iPads and iPhones, improving image sharpness and clarity massively. It is common now to see smaller screens such as 24″ and 27″ for instance, but with high resolutions like 3840 x 2160 (Ultra HD) or even 5120 x 2880 (5K). By packing more pixels in to the same screen size which would typically offer a 2560 x 1440 resolution, panel manufacturers are able to provide much smaller pixel pitches and improve picture sharpness and clarity. To measure this new way of looking at resolution you will commonly see the spec of ‘Pixels Per Inch’ (PPI) being used.

Of course the problem with this is that if you run a screen as small as 27″ with a 5K resolution, the font size is absolutely tiny by default. You get a massive boost of desktop real-estate, just like when moving from 1920 x 1080 to 2560 x 1440, but that’s not the purpose of these higher resolutions now. To overcome this you need to use the scaling options in your Operating System software to scale the image and make it more usable. Windows provides for instance scaling options like 125% and 150% within the control panel. On a 3840 x 2160 Ultra HD resolution if you use a 150% scaling option for example you will in effect reduce the desktop area by a third, resulting in the same desktop area as a 2560 x 1440 display (i.e. 2560 x 150% = 3840). The OS scaling makes font sizes more comfortable and reasonable, but you maintain the sharp picture quality and small pixel pitch of the higher resolution panel. A 3840 x 2160 res panel scaled at 1