pls tft vs tft lcd factory

2023-01-03 12:32:11

If you want to buy a new monitor, you might wonder what kind of display technologies I should choose. In today’s market, there are two main types of computer monitors: TFT LCD monitors & IPS monitors.

The word TFT means Thin Film Transistor. It is the technology that is used in LCD displays. We have additional resources if you would like to learn more about what is a TFT Display. This type of LCDs is also categorically referred to as an active-matrix LCD.

These LCDs can hold back some pixels while using other pixels so the LCD screen will be using a very minimum amount of energy to function (to modify the liquid crystal molecules between two electrodes). TFT LCDs have capacitors and transistors. These two elements play a key part in ensuring that the TFT display monitor functions by using a very small amount of energy while still generating vibrant, consistent images.

Industry nomenclature: TFT LCD panels or TFT screens can also be referred to as TN (Twisted Nematic) Type TFT displays or TN panels, or TN screen technology.

IPS (in-plane-switching) technology is like an improvement on the traditional TFT LCD display module in the sense that it has the same basic structure, but has more enhanced features and more widespread usability.

These LCD screens offer vibrant color, high contrast, and clear images at wide viewing angles. At a premium price. This technology is often used in high definition screens such as in gaming or entertainment.

Both TFT display and IPS display are active-matrix displays, neither can’t emit light on their own like OLED displays and have to be used with a back-light of white bright light to generate the picture. Newer panels utilize LED backlight (light-emitting diodes) to generate their light hence utilizing less power and requiring less depth by design. Neither TFT display nor IPS display can produce color, there is a layer of RGB (red, green, blue) color filter in each LCD pixels to produce the color consumers see. If you use a magnifier to inspect your monitor, you will see RGB color in each pixel. With an on/off switch and different level of brightness RGB, we can get many colors.

Winner. IPS TFT screens have around 0.3 milliseconds response time while TN TFT screens responds around 10 milliseconds which makes the latter unsuitable for gaming

Winner. the images that IPS displays create are much more pristine and original than that of the TFT screen. IPS displays do this by making the pixels function in a parallel way. Because of such placing, the pixels can reflect light in a better way, and because of that, you get a better image within the display.

Winner. While the TFT LCD has around 15% more power consumption vs IPS LCD, IPS has a lower transmittance which forces IPS displays to consume more power via backlights. TFT LCD helps battery life.

Normally, high-end products, such as Apple Mac computer monitors and Samsung mobile phones, generally use IPS panels. Some high-end TV and mobile phones even use AMOLED (Active Matrix Organic Light Emitting Diodes) displays. This cutting edge technology provides even better color reproduction, clear image quality, better color gamut, less power consumption when compared to LCD technology.

This kind of touch technology was first introduced by Steve Jobs in the first-generation iPhone. Of course, a TFT LCD display can always meet the basic needs at the most efficient price. An IPS display can make your monitor standing out.

The PLS panel is a panel developed and manufactured by Samsung’s as proprietary display design technology. Its performance is very close to that of IPS. The production cost is reduced by about 15% compared with IPS, so it is quite competitive in the market. Its advantages and disadvantages are similar to IPS, the only advantage is that it is lower cost than IPS.

The full name of the PLS panel is called Plane to Line Switching. The driving method is that all the electrodes are located on the same plane, and the liquid crystal molecules are driven by vertical and horizontal electric fields. We can see the difference between the PLS panel in the drive mode and the VA class (including MVA and Samsung’s own PVA) and the IPS panel.

Although the PLS panel has been published in 11 years, it has not been widely publicized, so most people do not know the PLS panel. However, Samsung introduced the PLS panel display, which is mainly for mid-range and mid-end users. It can be seen that this time Samsung still wants to carry out large-scale publicity on the PLS panel. It is generally better than the IPS displays because of wide viewing angles, high brightness and colour accuracy.

According to the TFT technology classification, it can be classified into high-temperature polysilicon (HTPS), low-temperature polysilicon (LTPS), amorphous silicon (a-Si), and IGZO. The other part can be classified into TN, IPS, VA, PLS, etc. according to the liquid crystal arrangement or imaging technology. It looks a bit messy, but it’s actually easier to judge.

The IPS panel is also known as the hard screen. It has a high viewing angle, fast response, good colour reproduction and moderate price. The shortcoming is that there is light leakage. The PLS is Samsung’s panel based on IPS standards, which is at the same level as IPS with a slightly better approach.

Using the PLS panel that Samsung uses to combat IPS, the feature is a wide viewing angle. The figure below shows that the panel performs well in terms of viewing angle in the left and right directions, with viewing angles of up to 178 degrees. The colour gamut also reached 72% NTSC, remember that I have said that the quality of 72% NTSC in the notebook screen is good. The display colour reaches 16.7M (8-bit) which provides a better colour display than a normal 6-bit screen.

pls tft vs tft lcd factory

AMOLED and TFT are two types of display technology used in smartphones. AMOLED (active-matrix organic light-emitting diode) displays are made up of tiny organic light-emitting diodes, while TFT (Thin-Film Transistor) displays use inorganic thin-film transistors.

AMOLEDs are made from organic materials that emit light when an electric current is passed through them, while TFTs use a matrix of tiny transistors to control the flow of electricity to the display.

Refresh Rate: Another key difference between AMOLED and TFT displays is the refresh rate. The refresh rate is how often the image on the screen is updated. AMOLED screens have a higher refresh rate than TFT screens, which means that they can display images more quickly and smoothly.

Response Time: The response time is how long it takes for the pixels to change from one colour to another. AMOLED screens have a shorter response time than TFT screens..

Colour Accuracy/Display Quality: AMOLED screens are more accurate when it comes to displaying colours. This is because each pixel on an AMOLED screen emits its own light, which means that the colours are more pure and true to life. TFT screens, on the other hand, use a backlight to illuminate the pixels, which can cause the colours to appear washed out or less vibrant.

Viewing Angle: The viewing angle is the angle at which you can see the screen. AMOLED screens have a wider viewing angle than TFT screens, which means that you can see the screen from more angles without the colours looking distorted.

Power Consumption: One of the main advantages of AMOLED displays is that they consume less power than TFT displays. This is because the pixels on an AMOLED screen only light up when they need to, while the pixels on a TFT screen are always illuminated by the backlight.

Production Cost: AMOLED screens are more expensive to produce than TFT screens. This is because the manufacturing process for AMOLED screens is more complex, and the materials used are more expensive.

Availability: TFT screens are more widely available than AMOLED screens and have been around for longer. They are typically used in a variety of devices, ranging from phones to TVs.

Usage: AMOLED screens are typically used in devices where power consumption is a concern, such as phones and wearable devices. TFT screens are more commonly used in devices where image quality is a higher priority, such as TVs and monitors.

AMOLED and TFT are two different types of display technology. AMOLED displays are typically brighter and more vibrant, but they are more expensive to produce. TFT displays are cheaper to produce, but they are not as bright or power efficient as AMOLED displays.

The display technology that is best for you will depend on your needs and preferences. If you need a screen that is bright and vibrant, then an AMOLED display is a good choice. If you need a screen that is cheaper to produce, then a TFT display is a good choice. However, if you’re worried about image retention, then TFT may be a better option.

pls tft vs tft lcd factory

Have you ever wonder where TFT derive from? Why is TFT referred to as LCD? The phenomenon started in early days, when bulky CRT displays were thing of the past and LCD was its replacement, but as time progresses, there were still room for improvement, which leads to the birth of TFT’s.

TFT is a variant of an LCD which uses thin film transistor technology to improve an image quality, while an LCD is class of displays that uses modulating properties of liquid crystals to form what we call an LCD (liquid crystals display) which in fact does not emits light directly.

Even though LCDs were very energy efficient, light weight and thin in nature, LCD were falling behind to the CRT display, which then leads to a change in LCD manufacturing, where performance became a big problem.

For example, having a 2001 Mustang vs a 2014 Mustang, the dimensions and engine of the 2014 has been redesign for performance reasons, not mentioning user friendly, so does the LCD to TFT.

As the birth of TFT, the elements are deposited directly on the glass substrate which in fact the main reason for the switch was because TFTs are easier to produce, better performance in terms of adjusting the pixels within the display to get better quality.

LCDs became ineffective over a period of time, almost all aspect of watching a TV, playing video games or using a handheld device to surf the net became daunting, this phenomenon is known as high response time with low motion rate.

Another problem with LCD was crosstalking, in terms of pixelating, this happens when signals of adjacent pixels affects operations or gives an undesired effect to the other pixel.

As TFT’s become very popular throughout the century due to its elaborate low charge associate and outstanding response time, LCDs became a thing of the past, and TFT became the predominant technology with their wider viewing angles and better quality this technology will be around for a long time.

pls tft vs tft lcd factory

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 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.

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.

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.

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.

pls tft vs tft lcd factory

Tried and trusted TFT technology works by controlling brightness in red, green and blue sub-pixels through transistors for each pixel on the screen. The pixels themselves do not produce light; instead, the screen uses a backlight for illumination.

So, why use a TFT display? Well, it is a mature technology meaning the manufacturing processes are efficient, yields high and cost much lower than AMOLED.

TFT displays also have a much longer lifespan than AMOLED displays and are available in a far greater range of standard sizes, which can be cut down to fit a space restricted enclosure for a relatively low cost adder.

pls tft vs tft lcd factory

In recent years, smartphone displays have developed far more acronyms than ever before with each different one featuring a different kind of technology. AMOLED, LCD, LED, IPS, TFT, PLS, LTPS, LTPO...the list continues to grow.

There are many display types used in smartphones: LCD, OLED, AMOLED, Super AMOLED, TFT, IPS and a few others that are less frequently found on smartphones nowadays, like TFT-LCD. One of the most frequently found on mid-to-high range phones now is IPS-LCD. But what do these all mean?

LCD means Liquid Crystal Display, and its name refers to the array of liquid crystals illuminated by a backlight, and their ubiquity and relatively low cost make them a popular choice for smartphones and many other devices.

LCDs also tend to perform quite well in direct sunlight, as the entire display is illuminated from behind, but does suffer from potentially less accurate colour representation than displays that don"t require a backlight.

Within smartphones, you have both TFT and IPS displays. TFT stands for Thin Film Transistor, an advanced version of LCD that uses an active matrix (like the AM in AMOLED). Active matrix means that each pixel is attached to a transistor and capacitor individually.

The main advantage of TFT is its relatively low production cost and increased contrast when compared to traditional LCDs. The disadvantage of TFT LCDs is higher energy demands than some other LCDs, less impressive viewing angles and colour reproduction. It"s for these reasons, and falling costs of alternative options, that TFTs are not commonly used in smartphones anymore.Affiliate offer

IPS technology (In-Plane Switching) solves the problem that the first generation of LCD displays experience, which adopts the TN (Twisted Nematic) technique: where colour distortion occurs when you view the display from the side - an effect that continues to crop up on cheaper smartphones and tablets.

The PLS (Plane to Line Switching) standard uses an acronym that is very similar to that of IPS, and is it any wonder that its basic operation is also similar in nature? The technology, developed by Samsung Display, has the same characteristics as IPS displays - good colour reproduction and viewing angles, but a lower contrast level compared to OLED and LCD/VA displays.

According to Samsung Display, PLS panels have a lower production cost, higher brightness rates, and even superior viewing angles when compared to their rival, LG Display"s IPS panels. Ultimately, whether a PLS or IPS panel is used, it boils down to the choice of the component supplier.

This is a very common question after "LED" TVs were launched, with the short answer simply being LCD. The technology used in a LED display is liquid crystal, the difference being LEDs generating the backlight.

One of the highlights from TV makers at the CES 2021 tradeshow, mini-LED technology seemed far removed from mobile devices until Apple announced the 2021 iPad Pro. As the name implies, the technique is based on the miniaturization of the LEDs that form the backlight of the screen — which still uses an LCD panel.

Despite the improvement in terms of contrast (and potentially brightness) over traditional LCD/LED displays, LCD/mini-LEDs still divide the screen into brightness zones — over 2,500 in the case of the iPad and 2021 "QNED" TVs from LG — compared to dozens or hundreds of zones in previous-generation FALD (full-array local dimming) displays, on which the LEDs are behind the LCD panel instead of the edges.

AMOLED stands for Active Matrix Organic Light-Emitting Diode. While this may sound complicated it actually isn"t. We already encountered the active matrix in TFT LCD technology, and OLED is simply a term for another thin-film display technology.

OLED is an organic material that, as the name implies, emits light when a current is passed through it. As opposed to LCD panels, which are back-lit, OLED displays are "always off" unless the individual pixels are electrified.

This means that OLED displays have much purer blacks and consume less energy when black or darker colours are displayed on-screen. However, lighter-coloured themes on AMOLED screens use considerably more power than an LCD using the same theme. OLED screens are also more expensive to produce than LCDs.

Because the black pixels are "off" in an OLED display, the contrast ratios are also higher compared to LCD screens. AMOLED displays have a very fast refresh rate too, but on the downside are not quite as visible in direct sunlight as backlit LCDs. Screen burn-in and diode degradation (because they are organic) are other factors to consider.Affiliate offer

OLED stands for Organic Light Emitting Diode. An OLED display is comprised of thin sheets of electroluminescent material, the main benefit of which is they produce their own light, and so don"t require a backlight, cutting down on energy requirements. OLED displays are more commonly referred to as AMOLED displays when used on smartphones or TVs.

Super AMOLED is the name given by Samsung to its displays that used to only be found in high-end models but have now trickled down to more modestly specced devices. Like IPS LCDs, Super AMOLED improves upon the basic AMOLED premise by integrating the touch response layer into the display itself, rather than as an extra layer on top.

Resolution describes the number of individual pixels (or points) displayed on the screen and is usually presented for phones by the number of horizontal pixels — vertical when referring to TVs and monitors. More pixels on the same display allow for more detailed images and clearer text.

Speaking of pixel density, this was one of Apple"s highlights back in 2010 during the launch of the iPhone 4. The company christened the LCD screen (LED, TFT, and IPS) used in the smartphone as "Retina Display", thanks to the high resolution of the panel used (960 by 640 pixels back then) in its 3.5-inch display.

As a kind of consolation prize for iPhone XR and iPhone 11 buyers, who continued relying on LCD panels, Apple classified the display used in the smartphones with a new term, "Liquid Retina". This was later applied also to the iPad Pro and iPad Air models, with the name defining screens that boast a high range and colour accuracy, at least based on the company"s standards.

TFT(Thin Film Transistor) - a type of LCD display that adopts a thin semiconductor layer deposited on the panel, which allows for active control of the colour intensity in each pixel, featuring a similar concept as that of active-matrix (AM) used in AMOLED displays. It is used in TN, IPS/PLS, VA/PVA/MVA panels, etc.

LTPS(Low Temperature PolySilicon) - a variation of the TFT that offers higher resolutions and lower power consumption compared to traditional TFT screens, based on a-Si (amorphous silicon) technology.

IGZO(Indium Gallium Zinc Oxide) - a semiconductor material used in TFT films, which also allows higher resolutions and lower power consumption, and sees action in different types of LCD screens (TN, IPS, VA) and OLED displays

LTPO(Low Temperature Polycrystaline Oxide) - a technology developed by Apple that can be used in both OLED and LCD displays, as it combines LTPS and IGZO techniques. The result? Lower power consumption. It has been used in the Apple Watch 4 and the Galaxy S21 Ultra.

Among televisions, the long-standing featured technology has always been miniLED - which consists of increasing the number of lighting zones in the backlight while still using an LCD panel. There are whispers going around that smartphones and smartwatches will be looking at incorporating microLED technology in their devices soon, with it being radically different from LCD/LED displays as it sports similar image characteristics to that of OLEDs.

In the case of LCD displays, the main advantage lies in the low manufacturing cost, with dozens of players in the market offering competitive pricing and a high production volume. Some brands have taken advantage of this feature to prioritize certain features - such as a higher refresh rate - instead of adopting an OLED panel, such as the Xiaomi Mi 10T.

pls tft vs tft lcd factory

Hi all, I"ve done some research on tft vs IPS screens and it seems tft screens are the worst type around. With that said, all the videos and articles I found were from 5ish years ago. Are tft screens still garbage? If so, why in the world would Motorola put it in their flagship?

I have noticed that distributors for small and medium TFT, they consider TFT still a top quality product, it"s enough to see product list of any online distributor like

pls tft vs tft lcd factory

Screen replacement is very fragile product. We strongly suggest test before installation. Please simulates testing, which means mobile phone apart, (motherboard + LCD or screen) connected audio cable and new replacement, power on, test finished. If test OK, please install it. If it can not show, please contact us at the very first time. And please do not force it to be installed in mobile phone. We will not be responsible once the screen is installed.

pls tft vs tft lcd factory

Monitors with this matrix - the most common. First invented LCD monitors were based on technology TN. Of 100 monitors in the world about 90 have TN the matrix. Are the cheapest and simple to manufacture and therefore the most massive.

Able to convey color in 18or 24-x bit range ( 6or 8 bit per channel Rgb), which, although a good indicator in comparison with the first LCD monitors on TNIn our time, this is not enough for high-quality color reproduction.

Based on TN monitors can be considered more eco-friendly in comparison with monitors on other LCD matrixes. They consume the least electricity, due to the use of low-power backlights.

The main goal was to get rid of shortcomings. TN matrices. Later, this technology was replaced by S —IPS(Super —IPS). Monitors with this technology produce Dell, LG, Philips, Nec, ViewSonic, ASUS and Samsung(Pls). The main purpose of these monitors is to work with graphics, photo processing and other tasks that require accurate color reproduction, contrast and standards compliance. sRGB and Adobe RGB. They are mainly used in professional work with 2D / 3D graphics, photo editors, and pre-print masters, but are also popular with those who simply want to please their eyes with a high-quality picture.

- variation IPS from Samsung. Unlike IPSIt is possible to place the pixels more densely, but the contrast suffers (not very successful design of pixels). Contrast no higher 600:1 - the lowest among LCD matrices. Even u TN matrices this figure is higher. Matrices Pls can use any kind of backlight. According to characteristics, more preferable than MVAPVA matrices.

LCD Monitor Screens (Liquid Crystal Display, liquid crystal monitors) are made of a substance (cyanophenyl), which is in a liquid state, but at the same time has some properties inherent in crystalline bodies. In fact, these are liquids that have anisotropic properties (in particular, optical) that are associated with orderliness in the orientation of molecules.

The first working LCD display was created by Fergason in 1970. Prior to this, liquid crystal devices consumed too much energy, their lifespan was limited, and the image contrast was depressing. The new LCD was presented to the public in 1971, and then it received hot approval. Liquid crystals (Liquid Crystal) are organic substances that are capable of changing the amount of transmitted light under voltage. The liquid crystal monitor consists of two glass or plastic plates, between which there is a suspension. The crystals in this suspension are arranged in parallel with respect to each other, thereby allowing light to penetrate through the panel. When an electric current is applied, the arrangement of the crystals changes, and they begin to prevent the passage of light. LCD technology is widely used in computers and projection equipment. The first liquid crystals were notable for their instability and were hardly suitable for mass production. The real development of LCD technology began with the invention of British scientists a stable liquid crystal - biphenyl (Biphenyl). The first-generation liquid crystal displays can be observed in calculators, electronic games and watches. Modern LCD monitors are also called flat panels, active dual-scan arrays, thin-film transistors. The idea of LCD monitors has been in the air for more than 30 years, but the studies that were carried out did not lead to an acceptable result, so LCD monitors have not won the reputation of devices that provide good image quality. Now they are becoming popular - everyone likes their elegant look, thin camp, compactness, economy (15-30 watts), moreover, it is believed that only wealthy and serious people can afford such luxury

There are two types of LCD monitors: DSTN (dual-scan twisted nematic - dual-scan crystal screens) and TFT (thin film transistor - on thin-film transistors), also called passive and active matrices, respectively. Such monitors consist of the following layers: a polarizing filter, a glass layer, an electrode, a control layer, liquid crystals, another control layer, an electrode, a glass layer and a polarizing filter. The first computers used eight-inch (diagonal) passive black and white matrix. With the transition to active matrix technology, the screen size has grown. Almost all modern LCD monitors use panels on thin-film transistors, providing a bright, clear image of a much larger size.

The size of the monitor depends on the working space occupied by it, and, importantly, its price. Despite the well-established classification of LCD monitors depending on the screen size diagonally (15, 17, 19-inch), the classification according to the working resolution is more correct. The fact is that, unlike CRT-based monitors, whose resolution can be changed quite flexibly, LCD displays have a fixed set of physical pixels. That is why they are designed to work with only one resolution, called a worker. Indirectly, this resolution determines the size of the matrix diagonal, however, monitors with the same working resolution may have a different matrix size. For example, monitors with a diagonal of 15 to 16 inches basically have a working resolution of 1024Ѕ768, which means that this monitor actually has a physical 1024 pixels horizontally and 768 pixels vertically. The working resolution of the monitor determines the size of the icons and fonts that will be displayed on the screen. For example, a 15-inch monitor can have a working resolution of 1024Ѕ768 and 1400Ѕ1050 pixels. In the latter case, the physical dimensions of the pixels themselves will be smaller, and since the same number of pixels are used in both cases when forming the standard icon, then at a resolution of 1400Ѕ1050 pixels the icon will be smaller in physical dimensions. For some users, too small icons at high resolution of the monitor may be unacceptable, so when you buy a monitor, you should immediately pay attention to the working resolution. Of course, the monitor is able to display the image in another, different from the working resolution. This mode of operation of the monitor is called interpolation. In the case of interpolation, the image quality is poor. Interpolation mode significantly affects the display quality of screen fonts.

LCD monitors are inherently digital devices, so the native interface for them is considered a digital DVI interface, which can have two types of convectors: DVI-I, combining digital and analog signals, and DVI-D, transmitting only a digital signal. It is considered that DVI is more preferable for connecting an LCD monitor to a computer, although it is also possible to connect via a standard D-Sub connector. DVI-interface is also supported by the fact that in the case of an analog interface double conversion of the video signal takes place: first the digital signal is converted to analog in a video card (D / A conversion), which is then transformed into a digital electronic unit of the LCD monitor itself (ADC conversion), as a result, the risk of various signal distortion increases. Many modern LCD monitors have both D-Sub and DVI connectors, which allows you to simultaneously connect two system units to the monitor. You can also find models with two digital connectors. In low-cost office models, only the standard D-Sub connector is generally present.

The basic component of the LCD matrix are liquid crystals. There are three main types of liquid crystals: smectic, nematic and cholesteric. According to their electrical properties, all liquid crystals are divided into two main groups: the first one includes liquid crystals with positive dielectric anisotropy, and the second with negative dielectric anisotropy. The difference lies in how these molecules react to an external electric field. Molecules with positive dielectric anisotropy are oriented along the field lines of force, while molecules with negative dielectric anisotropy are perpendicular to the lines of force. Nematic liquid crystals have a positive dielectric anisotropy, and smectic, on the contrary, negative. Another remarkable property of LC molecules is their optical anisotropy. In particular, if the orientation of the molecules coincides with the direction of propagation of plane-polarized light, then the molecules have no effect on the plane of polarization of light. If the orientation of the molecules is perpendicular to the direction of light propagation, then the plane of polarization is rotated so as to be parallel to the direction of orientation of the molecules. The dielectric and optical anisotropy of the LC molecules makes it possible to use them as a kind of light modulators that allow the desired image to be formed on the screen. The principle of operation of such a modulator is quite simple and is based on changing the plane of polarization of the light passing through the LCD cell. The LCD cell is located between two polarizers, the polarization axes of which are mutually perpendicular. The first polarizer cuts plane-polarized radiation from the light transmitted from the illumination lamp. If there were no LCD cell, then such plane-polarized light would be completely absorbed by the second polarizer. An LCD cell placed in the path of the transmitted plane-polarized light can rotate the plane of polarization of the transmitted light. In this case, part of the light passes through the second polarizer, that is, the cell becomes transparent (fully or partially). Depending on how you control the rotation of the polarization plane in the LCD cell, there are several types of LCD matrices. So, the LCD cell, placed between two crossed polarizers, allows you to modulate the transmitted radiation, creating a gradation of black and white. To obtain a color image, it is necessary to use three color filters: red (R), green (G) and blue (B), which, being installed on the white propagation path, will allow you to get three basic colors in the right proportions. So, each pixel of an LCD monitor consists of three separate subpixels: red, green, and blue, which are controlled LCD cells and differ only in the filters used, installed between the top glass plate and the output polarizing filter.

The main technologies in the manufacture of LCD displays: TN + film, IPS (SFT) and MVA. These technologies differ in the geometry of surfaces, polymer, control plate and front electrode. Of great importance are the purity and type of polymer with the properties of liquid crystals, applied in specific developments.

The TN-type liquid crystal matrix (Twisted Nematic) is a multi-layer structure consisting of two polarizing filters, two transparent electrodes and two glass plates, between which the nematic-type liquid-crystal substance with positive dielectric anisotropy is located. Special grooves are applied to the surface of the glass plates, which allows creating initially the same orientation of all liquid crystal molecules along the plate. The grooves on both plates are mutually perpendicular, so the layer of liquid crystal molecules between the plates changes its orientation by 90 °. It turns out that LC molecules form a structure twisted in a spiral (Fig. 3), which is why such matrices are called Twisted Nematic. Glass plates with grooves are located between two polarization filters, and the axis of polarization in each filter coincides with the direction of the grooves on the plate. In the normal state, the LCD cell is open because the liquid crystals rotate the plane of polarization of the light passing through them. Therefore, plane-polarized radiation, formed after the passage of the first polarizer, will pass through the second polarizer, since its axis of polarization will be parallel to the direction of polarization of the incident radiation. Under the influence of the electric field created by transparent electrodes, the molecules of the liquid crystal layer change their spatial orientation, lining up along the direction of the field lines of force. In this case, the liquid crystal layer loses the ability to rotate the plane of polarization of the incident light, and the system becomes optically opaque, since all light is absorbed by the output polarizing filter. Depending on the applied voltage between the control electrodes, it is possible to change the orientation of the molecules along the field not completely, but only partially, that is, to adjust the degree of twist of the LC molecules. This, in turn, allows you to change the intensity of the light passing through the LCD cell. Thus, installing a backlight lamp behind the LCD matrix and changing the voltage between the electrodes, you can vary the degree of transparency of one LCD cell. TN matrices are the most common and cheap. They have certain disadvantages: not very large viewing angles, low contrast and the inability to get the perfect black color. The fact is that even with the application of maximum voltage to the cell, it is impossible to unwind the LC molecules and orient them along the field lines of force. Therefore, such matrices, even when the pixel is completely turned off, remain slightly transparent. The second drawback is associated with small viewing angles. To partially eliminate it, a special diffusing film is applied to the monitor surface, which allows to increase the viewing angle. This technology is called TN + Film, which indicates the presence of this film. Finding exactly which type of matrix is used in the monitor is not so easy. However, if the monitor has a “broken” pixel caused by the failure of the transistor controlling the LCD cell, it will always glow brightly (in red, green or blue) in the TN-matrices, since the open pixel in the TN-matrix corresponds to the absence of voltage on the cell. You can recognize a TN matrix by looking at black at maximum brightness — if it’s rather gray than black, then this is probably the TN matrix.

IPS-matrix monitors are also called Super TFT-monitors. A distinctive feature of IPS-matrices is that the control electrodes are located in them in the same plane on the lower side of the LCD cell. In the absence of voltage between the electrodes, the LC molecules are parallel to each other, the electrodes and the polarization direction of the lower polarizing filter. In this state, they do not affect the polarization angle of the transmitted light, and the light is completely absorbed by the output polarizing filter, since the polarization directions of the filters are perpendicular to each other. When voltage is applied to the control electrodes, the generated electric field rotates the LC molecules by 90 ° so that they are oriented along the field lines. If a light is passed through such a cell, then due to the rotation of the polarization plane, the upper polarizing filter will let the light through without interference, that is, the cell will be in the open state (Fig. 4). By varying the voltage between the electrodes, it is possible to force the LC molecules to rotate at any angle, thereby changing the transparency of the cell. In all other respects, IPS cells are similar to TN matrices: a color image is also formed by using three color filters. IPS-matrices have both advantages and disadvantages compared with TN-matrices. The advantage is the fact that in this case it turns out perfectly black, and not gray, as in TN-matrices. Another indisputable advantage of this technology is large viewing angles. The disadvantages of IPS-matrices should be attributed to a pixel response time longer than for TN-matrices. However, we will return to the question of the pixel response time. In conclusion, we note that there are various modifications of IPS-matrices (Super IPS, Dual Domain IPS), allowing to improve their characteristics.

MVA is a development of VA technology, that is, technology with vertical alignment of molecules. In contrast to the TN and IPS matrices, in this case, liquid crystals with negative dielectric anisotropy are used, which are oriented perpendicular to the direction of the electric field lines. In the absence of voltage between the plates of the LCD cell, all liquid crystal molecules are oriented vertically and have no effect on the polarization plane of the transmitted light. Since the light passes through two crossed polarizers, it is completely absorbed by the second polarizer and the cell is in the closed state, while, in contrast to the TN matrix, it is possible to obtain an ideally black color. If a voltage is applied to the electrodes located above and below, the molecules rotate 90 °, orienting themselves perpendicularly to the lines of the electric field. With the passage of plane-polarized light through such a structure, the polarization plane rotates by 90 ° and the light freely moves through the output polarizer, that is, the LCD cell is in the open state. The advantages of the systems with the vertical ordering of molecules are the possibility of obtaining ideally black color (which, in turn, affects the possibility of obtaining high-contrast images) and the short response time of the pixel. In order to increase the viewing angles in systems with vertical molecular ordering, a multi-domain structure is used, which leads to the creation of matrices of the MVA type. The meaning of this technology is that each subpixel is divided into several zones (domains) using special protrusions, which somewhat change the orientation of the molecules, causing them to align with the surface of the protrusion. This leads to the fact that each such domain shines in its direction (within a certain solid angle), and the combination of all directions expands the viewing angle of the monitor. The advantages of MVA-matrices include high contrast (due to the possibility of obtaining perfectly black color) and large viewing angles (up to 170 °). Currently, there are several varieties of MVA technology, such as Samsung"s PVA (Patterned Vertical Alignment), MVA-Premium, and others, which further enhance the performance of MVA matrices.

Today, in LCD monitors, the maximum brightness declared in the technical documentation ranges from 250 to 500 cd / m2. And if the brightness of the monitor is high enough, then this is necessarily indicated in the advertising booklets and presented as one of the main advantages of the monitor. However, just this is one of the pitfalls. The paradox is that you cannot rely on the figures indicated in the technical documentation. This applies not only to brightness, but also to contrast, viewing angles and pixel response time. Not only can they not at all correspond to the values actually observed, sometimes it is generally difficult to understand what these numbers mean. First of all, there are different measurement techniques described in various standards; Accordingly, measurements carried out according to different methods give different results, and you can hardly find out by which method and how the measurements were taken. Here is one simple example. The measured brightness depends on the color temperature, but when they say that the monitor brightness is 300 cd / m2, the question arises: at what color temperature is this maximum brightness reached? Moreover, manufacturers indicate the brightness not for the monitor, but for the LCD matrix, which is not at all the same. To measure the brightness, special reference signals of generators with precisely specified color temperature are used, therefore the characteristics of the monitor itself as the final product may differ significantly from those stated in the technical documentation. But for the user, the characteristics of the monitor itself, and not of the matrix, are of paramount importance. Brightness is a really important feature for an LCD monitor. For example, with insufficient brightness, you can hardly play various games or watch DVD movies. In addition, it will be uncomfortable working behind the monitor in daylight conditions (external illumination). However, on this basis, to conclude that a monitor with a declared brightness of 450 cd / m2 is something better monitor with a brightness of 350 cd / m2, it would be premature. Firstly, as already noted, the declared and real brightness is not the same thing, and secondly, it is quite enough that the LCD monitor has a brightness of 200-250 cd / m2 (but not asserted, but actually observed). In addition, the fact how the brightness of the monitor is regulated is also important. From the point of view of physics, the brightness can be adjusted by changing the brightness of the backlight lamps. This is achieved either by adjusting the discharge current in the lamp (in the monitors, cold cathode fluorescent lamp, CCFL cold cathode fluorescent lamps are used as backlight), or through the so-called pulse-width modulation of the lamp power. With pulse-width modulation, the voltage on the backlight lamp is supplied by pulses of a certain duration. As a result, the illumination lamp does not glow continuously, but only at periodically repeated time intervals, but due to the inertia of vision, it seems that the lamp is constantly lit (the pulse repetition rate is more than 200 Hz). Obviously, by varying the width of the applied voltage pulses, you can adjust the average brightness of the backlight lamp. In addition to adjusting the brightness of the monitor due to the backlight, sometimes this adjustment is carried out by the matrix itself. In fact, a constant component is added to the control voltage on the electrodes of the LCD cell. This allows you to fully open the LCD cell, but does not allow it to completely close. In this case, with an increase in brightness, black ceases to be black (the matrix becomes partially transparent even when the LCD cell is closed).

No less important characteristic of the LCD monitor is its contrast, which is defined as the ratio of brightness white background to the brightness of the black background. Theoretically, the contrast of the monitor should not depend on the brightness level set on the monitor, that is, at any brightness level, the measured contrast should have the same value. Indeed, the brightness of the white background is proportional to the brightness of the backlight lamp. In the ideal case, the ratio of the transmittance of light by the LCD cell in the open and closed state is a characteristic of the LCD cell itself, but in practice this ratio may depend on both the set color temperature and the set brightness level of the monitor. Recently, the contrast of the image on digital monitors has increased markedly, and now this figure often reaches the value of 500: 1. But here everything is not so simple. The fact is that the contrast can be indicated not for the monitor, but for the matrix. However, as experience shows, if a contrast of more than 350: 1 is indicated in a passport, then this is quite enough for normal work.

Reaction time, or pixel response time, as a rule, is indicated in the technical documentation for the monitor and is considered one of the most important characteristics of the monitor (which is not quite right). In LCD monitors, the pixel response time, which depends on the type of matrix, is measured in tens of milliseconds (in the new TN + Film-matrices, the pixel response time is 12 ms), and this leads to blurring the changing picture and can be noticeable by sight. Distinguish between on time and off time of a pixel. By the time the pixel is turned on is the time required for opening the LCD cell, and by the time it is off it is the time needed to close it. When they talk about the response time of a pixel, they understand the total time on and off of a pixel. The on time of the pixel and the time it turns off can vary significantly. When they talk about the response time of a pixel, indicated in the technical documentation on the monitor, they mean the reaction time of the matrix, and not the monitor. In addition, the pixel response time, indicated in the technical documentation, is interpreted differently by different matrix manufacturers. For example, one of the options for interpreting the on (off) time of a pixel is that it is the time of changing the brightness of a pixel from 10 to 90% (from 90 to 10%). So far, speaking of measuring the response time of a pixel, it is implied that we are talking about switching between black and white colors. If there are no questions with black color (the pixel is just closed), then the choice of white color is not obvious. How will the pixel reaction time change if measured when switching between different semitones? This question is of great practical importance. The fact is that switching from black to white or, conversely, in real applications is relatively rare. In most applications, transitions between semitones are implemented, as a rule. And if the switching time between black and white turns out to be less than the switching time between grayscale, then the pixel response time will not have any practical value and it is impossible to focus on this characteristic of the monitor. What conclusion can be drawn from the above? It"s very simple: the pixel response time claimed by the manufacturer does not allow us to unambiguously judge the dynamic response of the monitor. In this sense, it is more correct to speak not about the switching time of a pixel between white and black colors, but about the average switching time of a pixel between semitones.

All monitors are by nature RGB-devices, that is, the color in them is obtained by mixing in different proportions of the three basic colors: red, green and blue. Thus, each LCD pixel consists of three color subpixels. In addition to the fully closed or fully open state of the LCD cell, intermediate states are also possible when the LCD cell is partially open. This allows you to shape the color tone and mix the color shades of the base colors in the right proportions. At the same time, the number of colors reproduced by the monitor theoretically depends on how many color shades can be formed in each color channel. Partial opening of the LCD cell is achieved by applying the required voltage level to the control electrodes. Therefore, the number of reproducible color shades in each color channel depends on how many different voltage levels can be applied to the LCD cell. For the formation of an arbitrary voltage level, you will need to use high-resolution DAC circuits, which is extremely expensive. Therefore, in modern LCD monitors are most often used 18-bit DACs and less often - 24-bit. When using an 18-bit DAC, there are 6 bits for each color channel. This allows you to form 64 (26 = 64) different voltage levels and, accordingly, to obtain 64 color shades in one color channel. All in all, by mixing the color shades of different channels, it is possible to create 262,144 color shades. When using a 24-bit matrix (24-bit DAC scheme), each channel has 8 bits, which makes it possible to form 256 (28 = 256) color shades in each channel, and the whole matrix reproduces 16 777 216 color shades. At the same time, for many 18-

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