twisted nematic tn lcd panel free sample

The Nematic liquid crystal state is a unique state not included in the above 3 states. It is a state between the crystalline (solid) and isotropic (liquid) states. Even in the state of liquid crystals, there are several types of liquid crystal states, as below.

The nematic liquid crystal phase is characterized by molecules maintain the general order of tending to point in the same direction. It has one dimensional order. See Fig.1

In smectic phase, molecules show two-dimensional order not present in the nematic. The molecules maintain the general orientationally of nematic, but also tend to align themselves in layers or planes. It is the state between nematic (one-dimensional order) and solid state (three-dimensional order). See Fig.1.

The cholesteric (or chiral nematic) liquid crystal phase is typically the molecules are directionally oriented and stacked in a helical pattern, with each layer rotated at a slight angle to the ones above and below it. See Fig.1.

TN stands for twisted nematic. This is a type of LED (a form of LCD) panel display technology. TN panels are characterized as being the fastest and cheapest among the other main types of display panels, VA (vertical alignment)and IPS (in-plane switching). As such, they work great for gaming monitors and gaming laptops. However, TN panels also offer the worst viewing angles and color when compared to VA and IPS panels.

PerformanceFastest: low response times, highest refresh rates, minimal motion blur; Low input lagLongest response times typically; Higher refresh rates possibleSlower response times than TN, faster response times than VA; Gaming-quality refresh rates are rare

DisplayWorst viewing angles;Worst colorViewing angles typically better than TN, worse than IPS; Good color; Best contrast;Best image depthBest viewing angles; Best color

A TN panel is an abbreviation for Twisted Nematic. It is an LCD display technology that is still being manufactured and used in electronic devices today.

Although newer, better display technologies have developed over the years, TN panels are still bought due to their affordability (see top budget monitors) and great gaming features. In this article, I"ll explain what a TN panel is and how it works.

TN stands for Twisted Nematic display. It is a type of LCD screen used in various electronic devices, including laptops, computer monitors, TVs, gaming systems, tablets, and mobile phones.

Many studies have been done on panel-type LCD vs. IPS displays. It"s true that the quality of the image is not as good as ISP panels because of the way TN displays are made, plus they are cheaper to produce.

TN displays have a high refresh rate than other display technologies. This makes them popular with gamers who want to get a higher refresh rate (see 120hz monitors). With a TN panel monitor, images will be updated quickly, which reduces blurriness and ghosting during fast motion.

A TN display has a better response time which makes it well suited for gaming. When playing games, you can"t afford to have a bad response time. In other words, the time taken from pushing a button to seeing action on your screen should be as low as possible. A faster response time ensures that you enjoy fast-paced games without any hassles.

TN displays typically have a low response time of below 5 MS. This means that a TN monitor will show more detail in faster-moving scenes compared to a VA monitor.

TN display is a good choice in a work monitor for small businesses needing to get up and running quickly. It"s less expensive, has great gaming features, and is easy to get. However, TN displays have a lower quality of color and contrast.

TN displays are enough for most people, especially if they"re going to use them for the office. For high performance and a display of good colors, you might want to consider a VA display. While more expensive, they"re also brighter and crisper than TN panels. And if you have the budget for it, an ISP screen is the way to go. They have the highest quality of color and contrast available on the market today—perfect if you"re trying to convey complex imagery in your storefront.

TN screens still make up a significant portion of the market, but they have fallen out of favor due to their poor color and viewing angle performance (see ultra-wide monitors) and lower contrast ratio.

The main problem with TN panels is viewing angles. When you move your head even slightly off-center, you can see a huge difference in color between what you"re looking at directly and what appears when you look at the screen from an angle. For example, if you"re viewing a white background, then move your head even slightly down or up, you"ll see that the background starts to take on another color.

Because of these limitations, TN displays are not as popular with graphic designers and similar professions as other flat-panel technologies such as IPS (in-plane switching) and AHVA or Advanced Hyper-Viewing Angle.

The low contrast ratio is something you can experience every time you use an old laptop or a monitor with this type of panel. If you put two colors right next to each other, like black and white, it will be extremely hard for your eyes to distinguish between them; the color difference will be almost imperceptible.

An LCD panel uses a combination of polarizers, color filters, and liquid crystals to produce an image. The backlight shines through red, green, and blue filters.

If you have an old or even new monitor or laptop (see what they are still good for here), it"s likely using a TN panel. Here are the TN panel features.

They are an older type of LCD technology. They were the first to be used in computer monitors but have been superseded by the superior IPS and VA technologies.

Panel type TN has a high refresh rate which is not an issue if you want to play games, watch movies because there"s no ghosting effect taking place on the screen. The best TN panels can reach refresh rates as high as 240 Hz.

The limited viewing angles. These types of panels can be hard to use when sitting at an angle, and the image quality takes a hit if you"re not sitting directly in front of the monitor.

Unimpressive color gamut makes TN screens inappropriate for professional graphic designers, architects and photographers who need accurate color representation.

TN panels have a poor contrast ratio, which means they can"t display deep blacks. In other words, the darkest parts of the picture will look gray. This is especially troubling when it comes to darker games and movies since the details of dark scenes will be lost in shadows.

If you"re looking for the highest possible resolution, TN panels aren"t the best option. They have a maximum resolution of 1920 x 1080, compared with 4K or 5K for IPS and VA panels.

Yes, TN panels can damage the eyes. Most people don"t feel comfortable using a TN panel for a long time unless it comes with eye care technologies such as anti-flicker and blue light filters. If you like to watch movies on a computer all day, the IPS panel is recommended.It emits blue light. The reason we need to avoid blue light is that it wouldmake our eyes uncomfortable and cause headaches. You may have experienced this when you were playing computer games in the past: the screen was bluish and made your eyes uncomfortable. So if you worry about eye safety, please choose an IPS panel instead of a TN panel.

The viewing angle of most TN panels ranges from 170/160 degrees. If you sit directly in front of the display with your head leveled, you will experience this viewing angle. But if you were to rotate your head so that your line of sight is at an angle greater than 170 degrees, then colors will begin to drift and distort on a TN panel.

The color quality of TN panels is not that good. They do not produce crisp colors, so this type of monitor is not suitable for users who work on graphics or images.

I"ve had a TN monitor for over 2 years now, and I really complain about its colors. It"s just that they don"t have a good color range as IPS panels, especially in the reds, but if you"re not an artist, you"ll hardly notice it.

The TNs have the worst contrast ratio, while IPS displays have the best. TN Panels have lower contrast ratios of around 1,000:1 to 2,000:1. This is not that great for movies or TV shows, but it"s still acceptable.

If you are planning to use your computer in a very bright light environment, you should choose the IPS ones, which have better visibility in a lot of light conditions than TN panels.

Response time is the time taken for a pixel to change from one color to another. A TN panel has a response time of fewer than 5 milliseconds (ms). A lower response time like this is better because fast-moving images will appear smoother and more natural.

The refresh rates of TN panels range from 60Hz and 144Hz. This represents an improvement over older TN panels, which had refresh rates of only 60Hz. The refresh rate is the number of times per second that a screen can refresh the image it displays.

If you"re looking to upgrade your setup for gaming, TN panels are the way to go. They"re the most responsive of all panel technologies, with high refresh rates.

Good gaming monitors have a low response time. The lower the number, the better. In LCD TN panels, response times are typically around 1ms, making them ideal for gaming.

The best TN panel for gaming has very high refresh rates. Some models can reach up to 240Hz refresh rates, which means that they can display content at up to 240 frames per second (fps). This is great for gamers who want high responsiveness and smooth graphics without suffering from screen tearing or image stuttering due to visual lag.

TN (Twisted Nematic) monitors were the first type of LCD monitors to make their way to the mainstream. TN Panels are generally cheaper than IPS models and look great from straight-on, which is great if you"re using your monitor to read emails or surf the web.

IPS or In-Plane Switching monitors have better viewing angles than TN models, so you can see accurate colors from almost any angle. Because of this feature, they tend to be more expensive than TN monitors.

Suppose you want a monitor for general office use, solid gaming performance, and don"t care too much about color accuracy and viewing angles. In that case, a TN panel monitor will be ideal for you.

The response time of TN panels tends to be faster than VA panels. TN panel monitors typically have a response time of 1-5ms, while a VA panel monitor"s response time typically ranges from 5-20ms.

In general, TN panels are suitable for gamers because they offer a greater level of responsiveness when playing fast action games such as first-person shooters, while VA panels are better suited for general use.

A TN panel can be adjusted to perform better. Do not change anything unless you know what you are doing; otherwise, twerking your display to perform better is easy.

The default color settings on TN panels aren"t very good, which is why you"ll often see extremely saturated or inconsistent colors. There are ways to adjust the settings to get a much more accurate picture that will please your eyes and make your screen more suitable for photo and video editing.

The answer is YES. I did good research and found that the majority of laptops use either TN or IPS panels. In the past, TN panels were favored for their simplicity and lower cost. They tend to be less expensive because they have fewer color reproduction capabilities and typically have a shorter lifespan.

IPS panels are generally more expensive because they have a longer lifespan and offer better color reproduction capabilities. However, TN displays still dominate the laptop market because they are cheaper to make and offer more responsive performance.

No, all laptop TN panels do not have the same quality. Their difference can be attributed to their features such as color gamut, refresh rates, viewing angles, and response time. Some offer good features, good image quality, and some TN panels don"t look very good at all.

The twisted nematic effect (TN-effect) was a main technology breakthrough that made LCDs practical. Unlike earlier displays, TN-cells did not require a current to flow for operation and used low operating voltages suitable for use with batteries. The introduction of TN-effect displays led to their rapid expansion in the display field, quickly pushing out other common technologies like monolithic LEDs and CRTs for most electronics. By the 1990s, TN-effect LCDs were largely universal in portable electronics, although since then, many applications of LCDs adopted alternatives to the TN-effect such as in-plane switching (IPS) or vertical alignment (VA).

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.

The twisted nematic effect is based on the precisely controlled realignment of liquid crystal molecules between different ordered molecular configurations under the action of an applied electric field. This is achieved with little power consumption and at low operating voltages. The underlying phenomenon of alignment of liquid crystal molecules in applied field is called Fréedericksz transition and was discovered by Russian physicist Vsevolod Frederiks in 1927.

The illustrations to the right show both the OFF and the ON-state of a single picture element (pixel) of a twisted nematic light modulator liquid crystal display operating in the "normally white" mode, i.e., a mode in which light is transmitted when no electrical field is applied to the liquid crystal.

In the OFF state, i.e., when no electrical field is applied, a twisted configuration (aka helical structure or helix) of nematic liquid crystal molecules is formed between two glass plates, G in the figure, which are separated by several spacers and coated with transparent electrodes, E1 and E2. The electrodes themselves are coated with alignment layers (not shown) that precisely twist the liquid crystal by 90° when no external field is present (left diagram). If a light source with the proper polarization (about half) shines on the front of the LCD, the light will pass through the first polarizer, P2 and into the liquid crystal, where it is rotated by the helical structure. The light is then properly polarized to pass through the second polarizer, P1, set at 90° to the first. The light then passes through the back of the cell and the image, I, appears transparent.

To display information with a twisted nematic liquid crystal, the transparent electrodes are structured by photo-lithography to form a matrix or other pattern of electrodes. Only one of the electrodes has to be patterned in this way, the other can remain continuous (common electrode). For low information content numerical and alpha-numerical TN-LCDs, like digital watches or calculators, segmented electrodes are sufficient. If more complex data or graphics information have to be displayed, a matrix arrangement of electrodes is used. Because of this, voltage-controlled addressing of matrix displays, such as in LCD-screens for computer monitors or flat television screens, is more complex than with segmented electrodes. For a matrix of limited resolution or for a slow-changing display on even a large matrix panel, a passive grid of electrodes is sufficient to implement passive matrix-addressing, provided that there are independent electronic drivers for each row and column. A high-resolution matrix LCD with required fast response (e.g. for animated graphics and/or video) necessitates integration of additional non-linear electronic elements into each picture element (pixel) of the display (e.g., thin-film diodes, TFDs, or thin-film transistors, TFTs) in order to allow active matrix-addressing of individual picture elements without crosstalk (unintended activation of non-addressed pixels).

In 1962, Richard Williams, a physical chemist working at RCA Laboratories, started seeking new physical phenomena that might yield a display technology without vacuum tubes. Aware of the long line of research involving nematic liquid crystals, he started experimenting with the compound p-azoxyanisole which has a melting point of 115 °C (239 °F). Williams set up his experiments on a heated microscope stage, placing samples between transparent tin-oxide electrodes on glass plates held at 125 °C (257 °F). He discovered that a very strong electrical field applied across the stack would cause striped patterns to form. These were later termed "Williams domains".

Although successful, the dynamic scattering display required constant current flow through the device, as well as relatively high voltages. This made them unattractive for low-power situations, where many of these sorts of displays were being used. Not being self-lit, LCDs also required external lighting if they were going to be used in low-light situations, which made existing display technologies even more unattractive in overall power terms. A further limitation was the requirement for a mirror, which limited the viewing angles. The RCA team was aware of these limitations, and continued development of a variety of technologies.

Another potential approach was the twisted-nematic approach, which had first been noticed by French physicist Charles-Victor Mauguin in 1911. Mauguin was experimenting with a variety of semi-solid liquid crystals when he noted that he could align the crystals by pulling a piece of paper across them, causing the crystals to become polarized. He later noticed when he sandwiched the crystal between two aligned polarizers, he could twist them in relation to each other, but the light continued to be transmitted. This was not expected. Normally if two polarizers are aligned at right angles, light will not flow through them. Mauguin concluded that the light was being re-polarized by the twisting of the crystal itself.

Wolfgang Helfrich, a physicist who joined RCA in 1967, became interested in Mauguin"s twisted structure and thought it might be used to create an electronic display. However RCA showed little interest because they felt that any effect that used two polarizers would also have a large amount of light absorption, requiring it to be brightly lit. In 1970, Helfrich left RCA and joined the Central Research Laboratories of Hoffmann-LaRoche in Switzerland, where he teamed up with Martin Schadt, a solid-state physicist. Schadt built a sample with electrodes and a twisted version of a liquid-crystal material called PEBAB (p-ethoxybenzylidene-p"-aminobenzonitrile), which Helfrich had reported in prior studies at RCA, as part of their guest-host experiments.

At this time Brown, Boveri & Cie (BBC) was also working with the devices as part of a prior joint medical research agreement with Hoffmann-LaRoche.James Fergason, an expert in liquid crystals at the Westinghouse Research Laboratories. Fergason was working on the TN-effect for displays, having formed ILIXCO to commercialize developments of the research being carried out in conjunction with Sardari Arora and Alfred Saupe at Kent State University"s Liquid Crystal Institute.

When news of the demonstration reached Hoffmann-LaRoche, Helfrich and Schadt immediately pushed for a patent, which was filed on 4 December 1970. Their formal results were published in Applied Physics Letters on 15 February 1971. In order to demonstrate the feasibility of the new effect for displays, Schadt fabricated a 4-digit display panel in 1972.

This work, in turn, led to the discovery of an entirely different class of nematic crystals by Ludwig Pohl, Rudolf Eidenschink and their colleagues at Merck KGaA in Darmstadt, called cyanophenylcyclohexanes. They quickly became the basis of almost all LCDs, and remain a major part of Merck"s business today.

Gerhard H. Buntz (Patent Attorney, European Patent Attorney, Physicist, Basel), "Twisted Nematic Liquid Crystal Displays (TN-LCDs), an invention from Basel with global effects", Information No. 118, October 2005, issued by Internationale Treuhand AG, Basel, Geneva, Zurich. Published in German

With so many companies in the market churning out newer and newer gaming monitors, shopping for LCD monitors can be confusing. Not only is there a lot of marketing noise out there today, but there are also debates on what panel/monitor type is the best?

When it comes to buying either a TV for home or a monitor for your office or a display for that gaming setup in your basement, things can be distilled down to usage and based on that; you can compare what different panels have to offer and how they will suit you. In this article, we will be having a quick look at the three most commonly used panels – TN, IPS and VA and helping you understand what they have to offer, and what they can be best used for. But first, a basic run on what an LCD is.

The major drawback of the CRT (cathode ray tube) technology was that it occupied quite a significant amount of space. The CRT displays worked on the principle of ‘light emission’ and they consumed a lot of power, which just added up to the size issue. The solution to these problems came in technological research on developing a screen that consumes less power (hence, increasing productivity), and which was smaller. Lit using fluorescent tubes, LCDs (liquid crystal displays) consume less power, are way thinner than the CRTs, and work on the principle of ‘blocking light’ rather than emitting it.

LCDs are made from a passive/active matrix grid made of conductors, the latter called as thin film display (or a TFT). Pixels are mounted on this grid at each intersection (and an active matrix has a transistor located at each pixel intersection). This network structure controls a pixel’s luminance and consuming a little amount of current. This ability leaves us with a choice to switch the current on and off more often on the grid, and this leads to a high ‘refresh rate.’ And a high refresh rate means a ‘smoother’ operation.

Developments in these screen types lead to LED TVs. The main difference between these and the LCDs is that they are lit using Light Emitting Diodes instead of fluorescent tubes. So technically, a LED display is a ‘LED backlit LCD screen.’

This LED backlighting helps in enhancing the color contrast and it consumes less power as compared to fluorescent tube lit panels. It significantly improves the overall picture quality by tapping into a wider RGB color range, and there is a better brightness achieved which allows you to see the images clearly, even in well-lit environments. On top of these things, LED backlit displays to consume less power and are lightweight too. So there are no drawbacks of this technology as such, resulting in backlighting being used in more and more panels every day. Today, we have three types of backlighting: White Edge, Full LED array, and Local Dimming LEDs.

White edge implements a diffusion panel, with white LED around the edges of the screen. This helps disperse the light evenly throughout the screen. A full LED array, as the name suggests, implements arrays of LED lights placed right behind the screen that collectively controlled for an even light dispersion. The third one is the Local Dimming LED system, which implements an array of dynamic led lights that can either be controlled in groups or individually to obtain an even light pattern.

This information, however not essential for everyone to know, is a good bit for panel enthusiasts and pro gamers, as having a high refresh rate depends on the panel’s build and it’s resolution. Now, let’s go ahead and have a look at the three most commonly used panels on these LCD monitors – TN, IPS, and VA.

The most common LCDs are based on TN (Twisted Nematic) panel designs. Manufactured on a vast scale and pretty cheap, TN displays can be found in most homes. Primarily made for supporting low response times, TN panels remain to this day, a cheaper option for gamers who want a massive resolution with a low response time and a high refresh rate. Not to say that the IPS panels don’t have these features, but an IPS panel with the same features as a TN (1ms response time, QHD resolution and a 144Hz refresh rate for example) will always be more expensive. However, while the price is good with the TN, the color quality and viewing angles take a toll. They are the drawbacks of a TN panel when compared to other panels out there.

TN displays, (TFT-LCDs for example), work by passing light through two polarized screens, a color filter and liquid crystals that tend to twist and block light in correspondence of the current applied to them. This type of an arrangement leaves a lot in your hands as you can change the amount of current applied to adjust the crystal twists. Hence, you can achieve virtually any color or shade reproduced on the screen. But while precise adjustments are possible with a TN display, there are some drawbacks to this structure.

Every LCD’s pixel is constructed using some red, green and blue sub-pixels. Colors and shades are produced by mixing different brightness levels for these pixels that result in the perception of a particular solid color by the user’s eyes. The problem with TN panels comes from its adoption of a 6-bit per channel model, which outputs 64 shades per color, instead of the 8-bit per channel, 256 shades implementation. Needless to say, color accuracy takes a toll here. And while the TN compensates for this issue with ‘dithering,’ (using alternating colors to produce a certain perceived shade) it is still a poor substitute for 24-bit color reproduction. On top of that, narrow viewing angles don’t help the case, as there is a ‘washout’ produced that puts TN panels at a low level concerning color accuracy.

But if your main concern is not the aesthetics of the performance, but the performance itself, TN LCD screens reign supreme over other panel types because of providing us low response times and high refresh rates on a budget.

TN panel displays have very fast GTG pixel response times that are usually well under the typical 5ms TFT-LCD average. This makes these displays a good choice for competitive gamers who are willing to sacrifice some color accuracy and viewing angles for great performance at a good price.

In-Plane-Switching, or IPS, was designed to overcome the shortcomings of a Twisted Nematic panel and they are replacing TN panels. These panels also use polarized filters, liquid crystals, and transmitters. However, in this case, the arrangement is different. The liquid crystals in an IPS panel design are aligned in a way that allows less light to distort and achieves better color visibility. Additionally, IPS panels use 8-bits of depth per color unlike TN’s 6-bit, which results in a wider 256 shades spectrum. This takes care of the color accuracy problem.

The second thing that is improved in IPS panels is the range of viewing angles. While Twisted Nematic panel displays ‘washed out’ at shallow angles, IPS displays have rich colors that don’t shift/fade when viewed from side angles. One other significant improvement of the IPS screen was that there were no trailing distortions when you touched them. This made them ideal for Touch-screen applications.

While marketed as the best of the best, IPS screens have some drawbacks of their own. The major one happens to be the cost. The construction of IPS panels requires a greater number of transmitters and lighting for each pixel. Now, the higher the resolution of the constructed panel will be, the greater number of pixels will be mounted on the panel. This results in a complex architecture, and they cost more than their TN counterparts. However, with the rising competition in the market, the prices of IPS panels have come down from expensive to reasonable, and you can get a decent IPS display for a few hundred dollars. However, the more you want from your monitor as a consumer, the more pricey it will become. This leaves high-end IPS monitors most commonly found at the desks of editing professionals and competitive gamers – people who want a lot of color accuracy and detailing along with decent speed and longevity.

IPS’s complex technology introduced some additional overhead that reduced the responsiveness of these panels. For quite some time, these panels clocked in around 8ms grey-to-grey. However, due to the popularity of these panels, response times, as well as refresh rates, have been improved quite a lot (the majority averaging at 60Hz)- at the cost of bigger price tags, of course.

Today, many variants of the IPS also exist, like Samsung’s popular PLS (plane line switching) panels. These variants are not entirely different from IPS, though there are subtle ‘generational improvements’ like enhancements in viewing angles, brightness and whatnot. LG also has a variation to the IPS, called as the eIPS, which is basically a IPS panel you can get on a budget. However, in real world use, the usage experience varies by a little factor.

VA (Vertical Alignment) panel technology sits between the high speeds of TN and the color richness of IPS panels. Constructed implementing IPS’s 8-bit color depth per channel approach (that has a crystal design capable of reproducing rich colors), VA (and its variants) also retain some of the low latency of TN panels. This results in a display that is ‘almost’ as fast as TN and as colorful as IPS.

Often reaching 5000:1, VN panels have a superior contrast as compared to both IPS and TN screens, and this remains the highlight among other features. These panels reproduce better black levels than TN or IPS. However, there are more issues with VA panels today than there are advantages, and some of these issues can’t be ignored.

First on the list of cons is the color (and contrast) shift that happens when we view media from a wide angle. And while the viewing angles of VA panels are wider than TN, the shift is similar to a TN panel and renders most VA panels ‘not ideal’ for tasks that require a great amount of color accuracy. When it comes to gaming, there’s another issue. VA panels offer rapid light-to-dark pixel transitions. However, darker color shifts aren’t as speedy, and it can lead to blurring during high-performance tasks.

Just like there are variants of IPS, VA panels also have their own. To put it simply, they progressed from 1998 to 2005 (and beyond) from MVA, AMVA to AMVA+. MVA or Multi-domain Vertical Alignment technology first came out in 1998 and provided a 25ms response time with 160-170 degree viewing angles. This was, of course, a lot of value at the time. Today, these panels can be found as AMVA (Advanced MVA) in many displays, and they offer a contrast ratio as high as 5000:1 (which is the best contrast ratio in LCD technology), and QHD (2560 x 1440p) resolution at a wide screen size like 32 inches. So again, a lot of value here as well. After that, we have the AMVA+ which had improved viewing angles on the standard AMVA.

So in a nutshell, while VA panels are much better than average TN panels regarding color reproduction, they are still not good enough if you were to switch to premium TN panels oriented for gaming purposes. And when it comes to IPS panels, they dominate the list but with one disadvantage – price. If we were to talk about performance, high-end IPS panels reign over all else, with response times as low as 1ms, 144Hz refresh rates and supporting resolutions all the way up to 4K and 5K. If, however, you want to talk ‘value for money,’ TN panels give you decent colors and speed at decent rates. And if you have some more money in your pocket after selecting a TN panel of certain specifications, you can look for a VA panel that will offer you some added color quality and viewing angles. It’s all about comparison here, and understanding the fundamentals of these panels is a good starting point.

In conclusion, the type of panel to be used is determined by the purpose of the monitor. In photography, graphics design, video and picture edits, where the displayed colors, as well as the viewing angle and contrast, are of great importance, the IPS should be considered. If the refresh rate, price and the reaction time is needed more than the other characteristics, the TN panel should be considered.

However, an IPS panel can have a higher reaction and refresh rate, but this will lead to an increase in the cost of production as well as the cost of acquiring it. It might also lead to a great increase in power consumption.

For our PresentationPoint users and digital signage in general, we can transform this recommendation as follows. For advertising and public information screens e.g. in hotels: use an IPS panel. In areas where the graphics qualities are not that important, use a TN panel. Think here about information screens in factories.

PC monitors and laptop screens come in all manner of shapes and sizes, but at their heart nearly all have one thing in common: an LCD panel. But not all LCDs are created equal. Some are better for gaming, some offer better contrast and some produce more accurate-looking colours. So, which is the best LCD type for your needs?

We’ll get to how the technology works below, but what you probably want to know off the bat is which technology is right for you. Here we’ll break down the main characteristics of each type: IPS, VA and TN.

Both IPS and VA have two main advantages over TN panels. The first is that they offer much better viewing angles. In other words, you can view both VA and IPS panels from far shallower angles and still be able to see what’s on-screen without much, or any, colour degradation. This is quite a big deal.

VA panels don’t tend to be quite as good as IPS, and as a result there can be a somewhat noticeable variation in brightness when viewed from different angles. ButIPS suffers from what’s known as ‘IPS glow’. This is where the backlight of the LCD shines through when the display is viewed from a certain angle.

Another advantage of IPS and VA panels is that both tend to present better colour reproduction – again, because they simply have a more controlled and precise ability to manage the light that passes through.

As for other differences, IPS tends to have a faster response time than VA since its crystals don’t have to tip over and then twist as they do with VA (see below). You can get fast-refreshing gaming monitors that use VA, but they offer a poor experience due to the slow pixel response time. IPS is slower than TN, but can be fast enough for responsive gaming.

Meanwhile, VA’s last hurrah is contrast. Since its resting state blocks light, its black level is the lowest of all LCDs, yet it can still produce bright colours when needed. A typical IPS or TN panel will have a contrast of 1000:1 or lower. VA panels can double that. This is the reason VA tends to be the best choice for TVs, where a deep black level is important for enjoying movies.

As for TN, it isn’t all bad news – it has a couple of key advantages. The first is that it’s easier to produce so can be used to make cheaper monitors.

If you’re after a monitor that offers great image quality for day-to-day work and image editing, but aren’t particularly bothered about super-competitive gaming, then go for an IPS screen. They deliver the best all-round experience for work and play, and you can still get gaming IPS monitors that refresh at over 100Hz, making them nearly as good as the best TN gaming screens.

However, if gaming is your be-all and end-all then TN is the way to go. Not only are they the most responsive – with the latest displays having refresh rates of 240Hz – but they also tend to be relatively affordable.

In the case of LCDs, a grid of pixels made from liquid crystal is sandwiched between two polarising filters and placed in front of a backlight. As light passes through this assembly, it’s either blocked by the second filter or allowed to pass, depending on the orientation of the molecules in the liquid crystal. Vary the voltage and it varies the orientation of the molecules.

This basic principle is what controls the pixels of any LCD panel. Split each pixel into three and add colour filters for red, green and blue and you have yourself a colour LCD screen.

These fundamentals apply to all the different types of LCD available to buy. However, in order to improve certain characteristics of the displays, different types of LCD have been developed that tweak the way in which the liquid crystal, polarising filters and the electrodes are arranged and controlled.

The original and most basic version of a modern LCD is TN, or twisted nematic. This has the polarisers arranged at ninety degrees to one another, so that – normally – no light passes through them. However, the resting state of the crystal has the molecules arranged in a helix, which twists the polarisation of the light as it passes through, in turn allowing it to pass through the second filter.

When a voltage is applied to the liquid crystal the molecules point directly towards the viewer, so no longer twisting the light, resulting in it being blocked by the second polarising filter. TN works well enough, but famously suffers from poor viewing angles (see above), which is why alternative models were developed.

The most famous of these is IPS, or in-plane switching. Here the polarising filters are in the same orientation so that light is blocked when the crystal is in its resting twisted state, rather than allowed to pass through as it would in TN. Then, when activated, the crystals line up in the same direction as the polarising filters and parallel to their surface: for instance, when switched they’re in-plane.

There are several variations on IPS, such as S-IPS and H-IPS, that use slightly different pixel structures and layouts, and have optimisations for faster response times – most displays that are referred to as IPS are in fact S-IPS panels – but the fundamentals are the same.

Samsung has also developed PLS as an alternative to IPS. It’s basically a reworking of the technology that allows Samsung to manufacture the panels without infringing on existing patents.

The other most common variant is Vertical Alignment (VA). Here the crystals are arranged perpendicular to the polarisers, which are again orientated at right-angles as they are with TN. As such, in its resting state a VA panel blocks light as the light isn’t being twisted. When a voltage is applied the crystals tip to a more horizontal position and twist, allowing light to pass through.

So, why would anyone ever buy a TN panel? For starters, they’re cheap. They don’t cost a lot to produce, so they’re often used in the most budget-friendly options. If you don’t value color reproduction or need excellent viewing angles, a TN panel might be fine for your office or study.

TN panels also have the lowest input lag—typically around one millisecond. They can also handle high refresh rates of up to 240 Hz. This makes them an attractive option for competitive multiplayer games—especially eSports, where every split-second counts.

IPS technology was developed to improve upon the limitations of TN panels—most notably, the poor color reproduction and limited viewing angles. As a result, IPS panels are much better than TNs in both of these areas.

In particular, IPS panels have vastly superior viewing angles than TNs. This means you can view IPS panels from extreme angles and still get accurate color reproduction. Unlike TNs, you’ll notice very little shift in color when you view one from a less-than-ideal perspective.

IPS panels are also known for their relatively good black reproduction, which helps eliminate the “washed out” look you get with TN panels. However, IPS panels fall short of the excellent contrast ratios you’ll find on VAs.

While high refresh rates were typically reserved for TNs, more manufacturers are producing IPS panels with refresh rates of 240 Hz. For example, the 27-inch 1080p ASUS VG279QM uses an IPS panel and supports 280 Hz.

Previously, TNs exhibited less input lag than any other panel, but IPS technology has finally caught up. In June 2019, LG announced its new Nano IPS UltraGear monitors with a response time of one millisecond.

Despite the gap being closed, you’ll still pay more for an IPS panel with such a low response time than you would for a TN with similar specs. If you’re on a budget, expect a response time of around four milliseconds for a good IPS monitor.

One last thing to be aware of with IPS panels is a phenomenon called “IPS glow.” It’s when you see the display’s backlight shining through it at more extreme viewing angles. It’s not a huge problem unless you view the panel from the side, but it’s something to keep in mind.

VA panels are something of a compromise between TN and IPS. They offer the best contrast ratios, which is why TV manufacturers use them extensively. While an IPS monitor typically has a contrast ratio of 1000:1, it’s not unusual to see 3000:1 or 6000:1 in a comparable VA panel.

In terms of viewing angles, VAs can’t quite match the performance of IPS panels. Screen brightness, in particular, can vary based on the angle from which you’re viewing, but you won’t get the “IPS glow.”

VAs have slower response times than TNs and the newer Nano IPS panels with their one-millisecond response rates. You can find VA monitors with high refresh rates (240 Hz), but the latency can result in more ghosting and motion blur. For this reason, competitive gamers should avoid VA.

Compared to TNs, VA panels do offer much better color reproduction and typically hit the full sRGB spectrum, even on lower-end models. If you’re willing to spend a bit more, Samsung’s Quantum Dot SVA panels can hit 125 percent sRGB coverage.

For these reasons, VA panels are seen as the jack of all trades. They’re ideal for general use, but they either match or fall short in most other areas except contrast ratio. VAs are good for gamers who enjoy single-player or casual experiences.

When compared to CRT monitors, all LCD panels suffer from some form of latency issue. This was a real problem when TN panels first appeared, and it’s plagued IPS and VA monitors for years. But technology has moved on, and while many of these issues have been improved, they haven’t been eliminated entirely.

Uneven backlighting is another issue you’ll find on all panel types. Often this comes down to overall build quality—cheaper models slack on quality control to save on production costs. So, if you’re looking for a cheap monitor, be prepared for some uneven backlighting. However, you’ll mostly only notice it on solid or very dark backgrounds.

LCD panels are also susceptible to dead or stuck pixels. Different manufacturers and jurisdictions have different policies and consumer laws covering dead pixels. If you’re a perfectionist, check the manufacturer’s dead-pixel policy before you buy. Some will replace a monitor with a single dead pixel for free, while others require a minimum number.

Office or study use: Your budget should be your primary concern here. VA is the do-it-all panel, with superior viewing angles to TN, but either would do the trick. You can save some money because you don’t need high refresh rates or ultra-low latency. They’re still nice, though. You’ll see a noticeable difference in smoothness just when moving the Windows cursor on a monitor with a 144 versus 60 Hz refresh rate.

Photo and video editors/Digital artists: IPS panels are still generally favored for their ability to display a wide gamut of colors. It’s not unusual to find VA panels that also cover a wide gamut (125 percent sRGB, and over 90 percent DCI-P3), but they tend to exhibit more motion blur during fast-paced action than IPS panels. If you’re serious about color accuracy, you’ll need to properly calibrate your monitor.

Programmers who mount monitors vertically: You might think TN panels are great for programmers, but that’s not necessarily the case. TN panels have particularly bad viewing angles on the vertical axis. If you mount your monitor in portrait mode (as many programmers and mobile developers do), you’ll get the worst possible viewing angles from a TN panel. For the best possible viewing angles in this scenario, invest in an IPS display.

Competitive online gamers: There’s no question TN panels are still favored in the eSports world. Even the cheapest models have fast response times and support for high refresh rates. For 1080p gaming, a 24-inch will do just fine, or you could opt for a 1440p, 27-inch model without breaking the bank. You might want to go for an IPS panel as more low-latency models hit the market, but expect to pay more.

Non-competitive, high-end PC gamers: For a rich, immersive image that pops, a VA panel will provide a higher contrast ratio than IPS or TN. For deep blacks and a sharp, contrasting image, VA is the winner. If you’re okay with sacrificing some contrast, you can go the IPS route. However, we’d recommend avoiding TN altogether unless you play competitively.

Best all-rounder: VA is the winner here, but IPS is better in all areas except contrast ratio. If you can sacrifice contrast, an IPS panel will provide fairly low latency, decent blacks, and satisfactory color coverage.

If you can, check out the monitor you’re interested in in-person before you buy it. You can perform some simple ghosting and motion blur tests by grabbing a window with the mouse and moving it rapidly around the screen. You can also test the brightness, watch some videos, and play with the onscreen display to get a feel for it.

This review article comprises three contents: 1) a general introduction of liquid crystals (LCs) and their chronological developments until their current status, 2) the descriptions of the achievements of defect-free and optically high-quality LC displays (LCDs), and 3) the description of the new and alternative methods for improving existing LCD technologies in terms of high-speed response, viewing angles, and power consumption through nanoparticle doping and optical compensation on a laboratory level. When these technologies are successfully developed, they will be used in the industry, where the fabrication process will be performed in a large-clean room using automated robotics.

Currently, liquid crystal displays (LCDs) are used as information displays for televisions, notebook computers, personal computers, desktop computers, mobile phones, car navigators, and a variety of other instruments. They are indispensable in our daily lives and jobs. In this paper we first provide an overview of the history of the evolution of LCD technology from its inception to the present. However, the current state of LCDs has been realized by many accumulations of new technologies over the last 60 years. Thus, an LCD is an example of successful innovation in these centuries. Then, we discuss and introduce how high-performance LCDs were realized in terms of their performances such as optically high-quality and large-area LCDs in the early stages in the 1970s and 1980s and accomplishments in high-speed response, wide viewing angles, and low power consumption by comparing existing technologies with new approaches of doping nanoparticles (NPs) into LCDs and novel asymmetric optical compensation through computer simulations. If these new technologies are successfully realized in the laboratory, they can be applied to large-scale production in a large-clean room with robotics.

Since then, chemistry and physics research has been primarily conducted by scientists in Europe2–5) and subsequently in the U.S.A.6) LCs have been categorized into nematic, smectic, and discotic types. They have been understood as rod-like or discotic-type organic molecules of finite order in a temperature range.2–7)

LCD research started with thermography8) and infrared-phonics​Fig.11.et al. published a book on LCs and LCDs in which they predicted the possibility of digital calculators using LCDs due to the low power consumption of LCDs compared with existing calculators using light-emitting tube displays.

In 1973, SHARP Corp., Japan developed and sold the world’s first digital calculator using DSM LCDs, where DIC corporation (the former company name was Dainippon Ink and Chemicals, Incorporated) provided useful LC materials and necessary ionic molecules (Fig. ​(Fig.22).

Figure ​Figure33 shows the historical development of LCDs and organic light-emitting diode (OLED) displays. Currently, 4K and 8K LCD TVs are available, and OLED displays are used in smartphones and partially in TVs.

Chronological development of products using LCDs and OLED displays (Source: 1985–1997 Sangyo Times and 1998–2025 HIS Market). Reproduced with permission from Ref. 17 (IET©).

Therefore, it was necessary to fabricate defect-free LCDs with high optical quality for practical applications. To realize defect-free LCDs, S. Kobayashi and his colleagues successfully fabricated defect-free LCDs,

Figure ​Figure44 depicts the current LCD structure, which includes 2-dimensional thin film transistor drivers, resulting in several pixels of up to 4K and 8K (3840 × 2160, 7680 × 4320 RGB pixels, respectively: ITU-BT.2020: Parameter values for ultra-high definition television systems for production and international programme exchange. https://www.itu.int/rec/R-REC-BT.2020) and a large area with 80-inch diagonals. The red, green, and blue cell color filters were invented by T. Uchida in 1981.

Figure ​Figure55 shows the structure and operation principles of TN LCDs. Under the quiescent condition (Voff), the LC conformation has a 90° twist by adding a chiral agent. With the crossed polarizers, the electric field of incident light rotates along the twisted LC molecules and transmits, resulting in the white state (called normally white). When an operating voltage (Von) is applied, the LC molecules take a vertical conformation except for the two boundary regions, where strong anchoring of the LC molecules is achieved. The transformation of the LC molecules from the planar conformation to the vertical conformation is caused by the torque equation:

Nowadays, TN LCDs are widely used in desktop PCs, notebook PCs, and indicators for all kinds of measuring instruments such as thermometers. An STN LCD is a TN LCD variation, where the twisting angle is increased up to 170°–270° rather than 90°. An STN LCD has a high direct multi-plex that enables it to exhibit 540 × 270 dot-matrix displays due to a sharp V-T curve.

Figure ​Figure77 depicts a cross-sectional view of an ECB LCD and its operation principle.​(Fig.7a),7a), LC molecules with a pretilt angle are oriented to be 45° to the transmission axes of the crossed polarizer; this situation produces the white state by illuminating this device from the bottom direction. The generation of the pretilt angle ensures defect-free LCDs. Under an operation voltage (Fig. ​(Fig.7b),7b), LC molecules take a slated conformation in unison due to the positive dielectric torque. In the Appendix, we explain the optical effect in an optical system, where a planar LC cell with optical anisotropy is sandwiched between the crossed polarizers. This effect occurs commonly in all types of LCDs.

Cross-sectional view of an electrically controlled birefringence (ECB) LCD and its operation principle. (a) Quiescent essential condition. (b) Operation voltage.

Figure ​Figure88 shows the structure and operation principles of IPS and FFS LCDs with the driving electrodes (designated as inter-digital electrodes), rubbing direction, and LC molecular switching.

Cross-sectional view of in-plane switching (IPS) and fringe field switching (FFS) LCDs comprising driving electrodes and molecular switching.17 (IET©).

In the two LCD devices, LC molecules are aligned and switched in a plane. Under the quiescent condition, LC molecules are oriented at an angle to yield the white state; LC molecules with a positive Δε rotate in the plane when an operation voltage is applied to the electrodes. When the direction of LC molecules takes 45° to the edge direction of the crossed polarizers, the LC device produces the white state. When the angle is null, the device produces the black state.

An IPS LCD with a negative Δε is also available. IPS LCDs have a wide angle of view; thus, they are widely used in LCD TVs, advanced notebook PCs, and VR.

Figure ​Figure99 shows the structure of VA LCDs and their operation principles. Under the quiescent condition (Voff), a VA LCD produces a black state with the crossed polarizers. When an operation voltage (Von) is applied, LC molecules with a negative Δε take an inclined conformation, resulting in the white state,

Structure of vertically aligned (VA) LCDs and operation principles. (a) Under the quiescent condition (Voff). (b) Under an operation voltage (Von). Reproduced with permission from Ref. 28 (IET©).

Figure ​Figure1010 shows the structure of optically compensated bent (OCB) LCDs with a biaxial optical compensator. In an OCB LCD, LC molecules are aligned in a bent conformation; this device is designed for normally white operations by applying a bias voltage of 1.6 V. When an operation voltage is applied, this device exhibits a black state by switching the retardation form π to zero. This device has a ten-fold faster response speed compared with other LCDs using nematic LCs.

Figure ​Figure1111 depicts the molecular switching in a polymer-stabilized V-shaped (PSV) FLC LCD and its V-T curve characteristics.​Fig.11A,11A, (a) is the state of the polymer-stabilized ferroelectric liquid crystal display (PS-FLCD) molecules at the quiescent condition (Vappl = 0), where the polymer molecules are red-colored. In (b) the minus electric voltage is applied; then the FLC molecules tend to incline toward the left direction due to their permanent polarization, and in (c) the situation of the positive electric voltage is applied. In these processes, each of the FLC molecule slide and rotate on a cone like structure. In this figure, all the FLC molecules are represented as a projected figure on a plain. Under the crossed polarizers, the configurations (b) and (c) produces white state, whereas in (a) the black state is produced. In Fig. ​Fig.11B,11B, we show the electro-optical performance of the polymer stabilized V-shaped switching FLCD, called PSV FLCD that exhibits V-shaped gray scale operation. While, the ordinary FLCD exhibits a hysteresis operation with a memory capability.

The conventional FLC LCD exhibits hysteresis characteristics and bi-stability in its V-T curve. In contrast, a PSV FLC LCD exhibits a continuous grayscale IPS. This was demonstrated for the first time.

Figure ​Figure1212 shows how a full-color image will be constructed in the switching process of a field-sequential (also designated as color-sequential) LCD accompanying the timing chart in this device, where the switching of the backlight is performed sequentially in the order of R–G–B, each with a switching-on-time of 4.6 ms and the related switching on and off the LCD. Thus, it is required that τ = τon + τoff < 4.63 ms.

An FSC LCD has 30% low power consumption and exhibits three-fold higher lightness than color filter-based LCDs. Field-sequential full-color LCDs have been fabricated by using PSV FLCDs and narrow gap TN LCDs, with the latter being used as airport indicators in the baggage claim area.

In 1972, F. Takeuchi, a staff of BUSICOM Corporation in Osaka, became a visiting researcher at RIKEN, Saitama, Japan, where S. Kobayashi conducted LC research as a member of staff at RIKEN. In the early stage of the research, Takeuchi observed the appearance of unfamiliar patterns in TN LCD cells. He inquired “what are they?” Kobayashi explained that they are “disclinations (disinclinations) originating from the discontinuity of refractive indices and are visible when the TN cell is sandwiched between two closed polarizers”.

The structure and operation are shown in Fig. ​Fig.5.5. However, it is impossible to fabricate optical defect-free TN LCDs. To fabricate defect-free TN LCDs, it is necessary to provide a pretilt angle, which is provided in advance before applying the operation voltage by performing the rubbing process on both substrates. Thus, the entire inclination of the LC molecule system is performed in unison, as will be introduced and discussed in the following parts of this paper. An illustrative explanation of the pretilt angle generation is presented in the Appendix.

When the splay and bent conformation coexist in a 90° twisted cell, the reverse twist disclination occurs, which causes light leakage and degrades optical contrast in the black state in the TN LCD cell. Takeuchi proposed an off 90° twist, i.e., 88° twist conformation that has lower energy than that of a 90° twist. This method was very effective and was granted a U.S. patent.

Figure ​Figure1515 shows the molecular conformation of the existing reverse tilt disclination in the TN LCD cell without a pretilt angle in both substrates. If there is no pretilt angle, there is no reverse tilt disclination.​Fig.1616.

Figure ​Figure1616 was obtained by Kobayashi and Takeuchi through collaboration with facilities at both RIKEN and BUSICOM Co. The results shown in Fig. ​Fig.1616 were demonstrated at RIKEN in October 1972, and many people saw a working TN LCD for the first time. The same demo was also performed at Tokyo Institute of Technology. It was also presented at the 1973 SID International Symposium

The TN LCD shown in Fig. ​Fig.1616 was fabricated using a prototype of the rubbing machine; its practical version was invented by S. Kobayashi in 1972–1973.​Fig.1717 is preserved in the Memorial Room at RIKEN as her 100-Year Anniversary.

In the 1980s, digital LCD watches and calculators were manufactured using the technique of oblique vacuum evaporation of oxide materials to realize LC molecular alignment with an appropriate pretilt angle.

To remove the stripe domain, H. Fukuro and S. Kobayashi modified the surface of a polyimide polymer by attaching alkyl branches to polyimide alignment molecules, as shown in Fig. ​Fig.18a,18a, and applying the rubbing process to them. Through this technique, they successfully produced high pretilt angles of 7°–10° (Fig. ​(Fig.18b)18b) and fabricated a defect-free STN LCD.​(Fig.19)19) and word processors.

The conventional FLCD demonstrates a bi-stable electro–optical operation; however, the adoption of polymer stabilization brings symmetric and V-shaped electro–optical characteristics.

An example of photo alignment technology for removing the reverse tilt disclinations to realize defect-free TN LCD with actual results. (a) First UV irradiation. (b) Second UV irradiation.

Regarding the physics of LC alignment in LCDs, we used lessons learned from our life mentor, Professor Koji Okano, who taught us statistical mechanics such as the steric interaction between LC molecules and substrates​Figs.1414 and ​and1616.

Figure ​Figure2424 demonstrates how to realize a wide viewing angle in TN and OCB LCDs by optical compensation. Figure ​Figure24a24a shows ISO transmission curves with viewing angle dependence; however, the transmission is homogeneous.

Figure ​Figure2626 shows argon laser light projected on a screen after passing through TN LCDs, where (a) shows TN LCDs without NP doping, and (b) shows a 0.075-wt.% PγCd-ZrO2-doped TN LCD cell. As shown in Fig. ​Fig.26a,26a, diffraction and laser speckle patterns are observed, whereas, in Fig. ​Fig.26b,26b, the optical pattern becomes uniform. The reduction in the number of speckle-patterns and crosses may be attributed to the forward optical scattering by NPs, and thus, de-coherence occurs when light passes through the NP-doped ECB cell, where the size of the NP is significantly smaller than the optical wavelength. This type of optical scattering will be analyzed with Rayleigh–Gans criteria such that

Argon laser light projected on a screen after passing through two TN LCD cells. (a) TN LCD without NP doping. (b) 0.075-wt.% PγCd-ZrO2-doped TN LCD cell.

where cd is the unit for luminance and W is the unit of power consumption for one square meter by assuming that power consumption is proportional to the display area (Table ​(Table2).2). Herein, we compare the LE of a standard commercial LCD TV and an NP-doped field-sequential TN LCD; their LE values are 1.95 and 5.13, respectively. According to the standard value of The Energy Star Program version 5.3 (https://www.energystar.gov/products/spec/television_specification_version_5_3_pd), LE is 3.8 (cd/W).

According to the Energy Star Program (ESP) version 5.3, the power consumption of LCD TV with 50 inches in the diagonal must be 108W or less. The ESP gives luminance efficiency (LE) = 3.8 (cd/W).

Ligand molecules such as oleic acid were adopted to prevent the segregation of QDs kept in an organic solvent before they are used to construct the LCD backlight. The design of the core/shell structure is to realize a long exciton lifetime. Photo-luminance produced by the illumination using a blue light source is red, green, and blue lights with a narrow half-value width, depending on the size.

As mentioned above, LCDs are widely used as information displays for televisions, computer monitors, and various instruments. However, their response speed needs further improvement. To this end, several methods have been adopted as follows: (1) using LC materials with low viscosity,

Figure ​Figure2929 illustrates the optical system of an OC ECB LCD cell, whose e-axis, e1, is rotated by π/4 from the x-axis, and the e-axis of the compensator (+A-plate), e2, is crossed to e1, where R = 2π(ne − no) d/λ is the optical retardation of each axis 1 and 2, where e and o denote the extraordinary and ordinary refractive index axes, respectively.

When the retardation in axes 1 and 2 is equal, the system is symmetric