an lcd displays color using the price

LCD Monitor Course II, which kicks off this session, will address certain points one must know to choose the LCD monitor best-suited to one"s needs from the various models available. Part 1 will focus on color gamut. While wide color gamuts are the latest trend in LCD monitors, color gamut is a term that lends itself to misunderstanding. Our hope is that this session will help users better understand the color gamut of LCD monitors and better select, use, and adjust the products.

Note: Below is the translation from the Japanese of the ITmedia article "IT Media LCD Monitor Course II, Part 1" published on November 11, 2008. Copyright 2011 ITmedia Inc. All Rights Reserved.

A color gamut defines a more specific range of colors from the range of colors identifiable by the human eye (i.e., the visible spectrum). While color imaging devices include a wide range of devices, such as digital cameras, scanners, monitors, and printers, since the range of colors they can reproduce varies, the color gamut is established to make these differences clear and to reconcile the colors that can be used in common between devices.

Various methods are used to express (diagram) the color gamut, but the common method used for display products is the xy chromaticity diagram of the XYZ color system established by the International Commission on Illumination (CIE). In an xy chromaticity diagram, the colors of the visible range are represented using numerical figures and graphed as color coordinates. In the following xy chromaticity diagram, the area shaped like an upside-down "U" surrounded by dotted lines indicates the range of colors visible to human beings with the naked eye.

Various standards govern color gamuts. The three standards frequently cited in relation to personal computers are sRGB, Adobe RGB, and NTSC. The color gamut defined by each standard is depicted as a triangle on the xy chromaticity diagram. These triangles show the peak RGB coordinates connected by straight lines. A larger area inside a triangle is regarded to represent a standard capable of displaying more colors. For LCD monitors, this means that a product compatible with a color gamut associated with a larger triangle can reproduce a wider range of colors on screen.

This is a CIE XYZ color system xy chromaticity diagram. The areas enclosed in dotted lines represent the range of colors human beings can see with the naked eye. The ranges corresponding to the sRGB, Adobe RGB, and NTSC standards defining color gamuts appear as triangles connecting their RGB peak coordinates. The color gamut of an LCD monitor"s hardware can be indicated using similar triangles. An LCD monitor is not capable of reproduction (display) of colors outside its color gamut.

The standard color gamut for personal computers is the international sRGB standard prepared in 1998 by the International Electrotechnical Commission (IEC). sRGB has established a firm position as the standard in Windows environments. In most cases, products like LCD monitors, printers, digital cameras, and various applications are configured to reproduce the sRGB color gamut as accurately as possible. By ensuring that the devices and applications used in the input and output of image data are sRGB compatible, we can reduce discrepancies in color between input and output.

However, a look at the xy chromaticity diagram shows that the range of colors that can be expressed using sRGB is narrow. In particular, sRGB excludes the range of highly saturated colors. For this reason, as well as the fact that advances in devices such as digital cameras and printers have led to widespread use of devices capable of reproducing colors more vivid than those allowed under the sRGB standard, the Adobe RGB standard and its wider color gamut have recently drawn interest. Adobe RGB is characterized by a broader range than sRGB, particularly in the G domain—that is, by its ability to express more vivid greens.

Adobe RGB was defined in 1998 by Adobe Systems, maker of the well-known Photoshop series of photo-retouching software products. While not an international standard like sRGB, it has become— backed by the high market share of Adobe"s graphics applications—the de facto standard in professional color imaging environments and in the print and publishing industries. Growing numbers of LCD monitors can reproduce most of the Adobe RGB color gamut.

NTSC, the color-gamut standard for analog television, is a color gamut developed by the National Television Standards Committee of the United States. While the range of colors that can be depicted under the NTSC standard is close to that of Adobe RGB, its R and B values differ slightly. The sRGB color gamut covers about 72% of the NTSC gamut. While monitors capable of reproducing the NTSC color gamut are required in places like video production sites, this is less important for individual users or for applications involving still images. sRGB compatibility and the capacity to reproduce the Adobe RGB color gamut are key points of LCD monitors that handle still images.

The visual differences between Adobe RGB (photo at left) and sRGB (photo at right). Converting a photograph in the Adobe RGB color gamut to the sRGB domain results in the loss of highly saturated color data and loss of tonal subtleties (i.e., a susceptibility to color saturation and tone jumping). The Adobe RGB color gamut can reproduce more highly saturated colors than sRGB color. (Note that the actual colors displayed will vary with factors such as the monitor used to view them and the software environment. The sample photographs should be used for reference only.)

In general, the LCD monitors currently available for use with PCs have color gamuts capable of displaying nearly the entire sRGB gamut, thanks to the specifications for their LCD panels (and panel controls). However, given the rising demand mentioned above for reproducing color gamuts broader than sRGB, recent models have expanded the color gamuts of LCD monitors, with Adobe RGB serving as one target. But how is such expansion of LCD monitor color gamuts taking place?

Improvements in backlights account for a significant proportion of the technologies expanding the color gamuts of LCD monitors. There are two major approaches to doing this: one involves expanding the color gamut of cold cathodes, the mainstream backlight technology; the other involves RGB LED backlights.

On the subject of color-gamut expansion using cold cathodes, while strengthening the LCD panel"s color filter is a quick fix, this also lowers screen luminance by decreasing light transmissivity. Increasing the luminance of the cold cathode to counter this effect tends to shorten the life of the device and often results in lighting irregularities. Efforts to date have overcome these drawbacks to a large extent; many LCD monitors feature cold cathodes with wide color gamuts resulting from modification of their phosphors. This generates cost benefits as well, since it makes it possible to expand the color gamut without major changes in the existing structure.

Use of RGB LED backlights has increased relatively recently. These backlights make it possible to achieve higher levels of luminance and purity of color than cold cathodes. Despite certain disadvantages, including lower color stability (i.e., radiant-heat problems) than a cold cathode and difficulty in attaining a uniform white color across the entire screen, since it involves a mixture of RGB LEDs, these weaknesses have been resolved for the most part. RGB LED backlights cost more than cold-cathode backlights and are currently used in a fairly small proportion of LCD monitors. However, based on their efficacy in expanding color gamuts, the number of LCD monitors incorporating the technology will likely increase. This is also true for LCD televisions.

In passing, many LCD monitors that extol wide color gamuts promote the area ratios of specific color gamuts (i.e., triangles on the xy chromaticity diagram). Many of us have probably have seen indications of attributes such as Adobe RGB rates and NTSC rates in product catalogs.

However, these are only area ratios. Very few products include the entire Adobe RGB and NTSC color gamuts. Even if a monitor featured a 120% Adobe RGB ratio, it would remain impossible to determine the extent of the difference in RGB values between the LCD monitor"s color gamut and the Adobe RGB color gamut. Since such statements lend themselves to misinterpretation, it is important to avoid being confused by product specifications.

To eliminate problems involving labeled specifications, some manufacturers use the expression "coverage" in place of "area." Clearly, for example, an LCD monitor labeled as having Adobe RGB coverage of 95% can reproduce 95% of the Adobe RGB color gamut.

From the user"s perspective, coverage is a more user-friendly, easier-to-understand type of labeling than surface ratio. While switching all labeling to coverage presents difficulties, showing in xy chromaticity diagrams the color gamuts of LCD monitors to be used in color management will certainly make it easier for users to form their own judgments.

With regard to the difference between area labeling and coverage labeling as gauges of an LCD monitor"s color gamut, to use Adobe RGB as an example, in many cases, even a monitor with an Adobe RGB ratio of 100% in terms of area will feature coverage of less than 100 percent. Since coverage impacts practical use, one must avoid the mistake of seeing a higher figure as automatically better.

When we check the color gamut of an LCD monitor, it"s also important to remember that a wide color gamut is not necessarily equivalent to high image quality. This point may generate misunderstanding among many people.

Color gamut is one spec used to measure the image quality of an LCD monitor, but color gamut alone does not determine image quality. The quality of the controls used to realize the full capabilities of an LCD panel having a wide color gamut is crucial. In essence, the capacity to generate accurate colors suited to one"s own purposes outweighs a wide color gamut.

When considering an LCD monitor with a wide color gamut, we need to determine if it has a color-gamut conversion function. Such functions control the LCD monitor"s color gamut based on the target color gamut, such as Adobe RGB or sRGB. For example, by selecting sRGB mode from a menu option, we can adjust even an LCD monitor with a wide color gamut and high Adobe RGB coverage so that the colors displayed on screen fall within the sRGB color gamut.

Few current LCD monitors offer color-gamut conversion functions (i.e., feature compatibility with both Adobe RGB and sRGB color gamuts). However, a color-gamut conversion function is essential for applications demanding accurate color generation in the Adobe RGB and sRGB color gamuts, such as photo retouching and Web production.

For purposes requiring accurate color generation, an LCD color monitor lacking any color-gamut conversion function but having a wide color gamut can actually be a disadvantage in some cases. These LCD monitors display each RGB color mapped to the color gamut inherent to the LCD panel in eight bits at full color. As a result, the colors generated are often too vivid for displaying images in the sRGB color gamut (i.e., the sRGB color gamut cannot be reproduced accurately).

Shown here are examples of an sRGB color gamut photograph displayed on an sRGB-compatible LCD monitor (photo at left) and on an LCD monitor with a wide color gamut but incompatible with sRGB and with no color-gamut conversion function (photo at right). While the photograph at right appears vivid, saturation is unnaturally high in parts of the photo. We also see a significant departure from the colors envisioned by the photographer, as well as so-called memory colors.

In more than a few cases, as expanding LCD monitor color gamuts result in the capacity to reproduce a wider range of colors and more opportunities to check colors or adjusting images on monitor screens, problems such as breakdowns in tonal gradations, variations in chromaticity caused by narrow viewing angles, and screen display irregularities, less conspicuous at color gamuts in the sRGB range, have become more pronounced. As mentioned earlier, the mere fact of incorporating an LCD panel with a wide color gamut does not ensure that an LCD monitor offers high image quality. On this subject, let"s take a close look at various technologies for putting a wide color gamut to use.

First we look at technologies to increase gradation. Key here is the internal gamma-correction function for multi-level gradation. This function displays eight-bit input signals on screen in each RGB color from the PC side after first subjecting them to multi-level gradation to 10 or more bits in each RGB color inside the LCD monitor, then assigning these to each RGB eight-bit color deemed optimal. This improves tonal gradations and gaps in hue by improving the gamma curve.

On the subject of the viewing angle of an LCD panel, while larger screen sizes generally make it easier to see differences, particularly with products with wide color gamuts, variations in chromaticity can be an issue. For the most part, chromaticity variation due to viewing angle is determined by the technology of the LCD panel, with superior ones showing no variation in color even when viewed from a moderate angle. Setting aside the various particulars of LCD panel technologies, these generally include in-plane switching (IPS), vertical alignment (VA), and twisted nematic (TN) panels, listed from smaller to larger chromaticity variation. While TN technology has advanced to the point at which viewing angle characteristics are much improved from several years back, a significant gap remains between this technology and VA and IPS technologies. If color performance and chromaticity variation are important, VA or IPS technology remains the better choice.

A uniformity-correction function is a technology for reducing display irregularities. The uniformity referred to here refers to colors and brightness (luminance) on screen. An LCD monitor with superior uniformity has low levels of screen luminance irregularities or color irregularities. High-performance LCD monitors feature systems that measure luminance and chromaticity at each position on screen and correct them internally.

This is a comparison of monitors with and without uniformity correction. An LCD monitor with uniformity correction (photo at left) has more uniform luminance and color on screen than one lacking uniformity correction (photo at right). The two photographs above have been adjusted to equalize levels to emphasize display irregularities. Actual irregularities would be less conspicuous.

To make full use of an LCD monitor with a wide color gamut and to display colors as the user intended, one needs to consider adopting a calibration environment. LCD monitor calibration is a system for measuring colors on screen using a special-purpose calibrator and reflecting the characteristics of the colors in the ICC profile (a file defining device color characteristics) used by the operating system. Going through an ICC profile ensures uniformity between the color information handled by graphics software or other software and the colors generated by the LCD monitor to a high degree of precision.

Software calibration refers to following the instructions of specialized calibration software to adjust parameters such as luminance, contrast, and color temperature (RGB balance) using the LCD monitor"s adjustment menu, approaching the intended color through manual adjustments. Graphics driver colors are manipulated in some cases in place of the LCD monitor"s adjustment menu. Software calibration features low cost and can be used to calibrate any LCD monitor.

However, variations in precision can arise since software calibration involves manual adjustment. Internally, RGB gradation can suffer because display balance is matched by thinning RGB output levels using software processing. Even so, use of software calibration will likely make it easier to reproduce colors as intended than using no calibration at all.

In contrast, hardware calibration is clearly more precise than software calibration. It also requires less effort, although it can be used only with compatible LCD monitors and entails certain setup costs. In general, it involves the following steps: calibration software controls the calibrator; matching color characteristics on screen with target color characteristics and directly adjusting the LCD monitor"s luminance, contrast, and gamma-correction table (look-up table) at the hardware level. Another aspect of hardware calibration that cannot be overlooked is its ease of use. All tasks through the preparation of an ICC profile for the results of adjustment and registering this to the OS are done automatically.

The EIZO LCD monitors currently compatible with hardware calibration include models in the ColorEdge series. The FlexScan series uses software calibration. (Note: As of January 2011, FlexScan monitors compatible with EasyPIX ver. 2 offer hardware calibration functionality.)

By combining a ColorEdge-series monitor with a calibrator and ColorNavigator special-purpose color-calibration software, one can achieve easy, precise hardware calibration.

In the next session, we will examine LCD monitor interfaces and a number of video interfaces for LCD monitors, including the latest generation of interfaces such as HDMI and DisplayPort.

In this article, we"ll look at the gradations that result from the maximum number of colors that can be displayed and the look-up table (LUT). While these factors are a step beyond what average users consider when choosing products, they have a significant impact on color reproduction. Users are well-advised to understand these factors, especially when choosing an LCD monitor for color-intensive applications like photo retouching or design work.

Note: Below is the translation from the Japanese of the ITmedia article "Maximum Display Colors and Look-Up Tables: Two Things to Consider When Choosing a Monitor" published February 18, 2009. Copyright 2011 ITmedia Inc. All Rights Reserved.

While most LCD monitor catalogs show the maximum number of colors each model can display, few people pay much attention to this figure. That"s because most products today can display a staggering number of colors—more than 16 million. Users are unlikely to be dissatisfied because the product displays too few colors. However, the figure for maximum number of colors is associated with some unexpected pitfalls.

The LCD monitors currently available for PC use need to accurately display full-color video signals in the number of colors generated when using eight bits for each RGB color (for a total of 24 bits) input from the PC. Using eight bits for each RGB color, we can generate roughly 16.77 million colors, based on the following calculations:

We need to keep two points in mind: First, not all leading LCD monitors can reproduce the entire full color range of approximately 16.77 million colors. Second, this full color range of 16.77 million colors can be achieved in different ways. The LCD monitors currently available generally fall into the following three categories with respect to the maximum number of colors and method of color reproduction.

Only the Type 1 LCDs in the table above achieve full color in the true sense of the term, reproducing each RGB color at eight bits on an LCD panel operating at eight bits. Products that fall into Types 2 or 3 offer so-called virtual full color. Virtual full color products cost less to implement, but generally offer inferior capacity to express gradation than true eight-bit LCD panels.

When we look at monitor specs, it"s easy to identity a Type 3 model: The number of colors will be specified as 16.19 or 16.20 million. However, since both types 1 and 2 show approximately 16.77 million colors it can be difficult to identify the applicable type from a catalog. An LCD panel operating at eight bits is superior in some ways with respect to picture quality, and users are advised to be careful when choosing monitors for graphics applications. (Note that in some cases, the figure of 24 bits—eight for each RGB color—is used instead.)

Certain LCD televisions and LCD monitors for commercial use are based on LCD panels that reproduce each RGB color at 10 bits. In theory, these monitors can generate 1,073,741,824 (or approximately 1.073 billion) colors; but they also require graphics accelerators and software capable of handling 10-bit color. For these reasons, they are not yet common in the PC industry.

Let"s consider at a simple description of frame rate control (FRC). FRC is a system for increasing the number of apparent colors by manipulating the frame rate, taking advantage of afterimage effects in the human eye. Switching rapidly between white and red, for example, will create what the human eye perceives as pink.

An LCD panel with six-bit operation plus FRC can actually generate just 262,144 colors (six bits [26 = 64] to the third power [for each RGB color]). We can apply FRC to each RGB color and change the display interval between each of the LCD panel"s original colors (in the case of four-bit FRC) to generate three simulated colors between each pair of individual colors. For each RGB color, this adds the following number of simulated colors: (6 bits – 1) * 3 = 189 colors. We obtain the total number of colors by calculating (6 bits + 189 = 253) to the third power (each RGB color) = 16,194,277 colors (≈ approximately 16.19 or 16.20 million colors).

More and more recent products feature technologies that take FRC one step further. These technologies make it possible to reproduce approximately 16.77 million colors by operating the number of bits exceeding those with traditional FRC to generate even more stimulated colors, then taking from these the eight-bit (256-gradation) scale needed to achieve full color on an LCD monitor.

Under real-life conditions, factors other than the panel, such as quality of ICs for image control, can also significantly affect picture quality. The difference in picture quality between eight bits and six bits plus FRC is often not apparent on visual inspection. Minimizing environmental lighting (for example, by dimming lights) can make such differences easier to spot. Displaying gradation patterns that change linearly, one going from shadow to highlight, can also highlight such differences. Such display tendencies apply equally to still images, moving images, games, and other applications.

Sample gradation display using a full-color display operating at eight bits (left) and virtual full-color display operating at six bits plus FRC (right). While this display exaggerates the difference to make it easier to see, eight-bit operation generally offers greater gradation display capability.

We"ve noted that six-bit operation plus FRC is inferior to eight-bit operation in terms of gradation display capability. However, this doesn"t mean eight-bit operation is always superior with respect to color reproduction and gradation. The look-up table (LUT) is a key factor in an LCD monitor"s ability to display tonal grades and transitions.

An LUT is a table containing the results of calculations. When a system needs to process a standardized calculation, we can improve performance by having it look up an LUT value instead of performing the calculation.

In the context of LCD monitors, the term LUT refers to a component that calculates input signals from the PC (at eight bits per RGB color) and maps them to output signals suited to the LCD monitor (also at eight bits per RGB color). An inexpensive LCD monitor will employ an LUT table with eight bits per RGB color; an LCD monitor designed for color reproduction applications will incorporate an LUT with more than eight bits (i.e., 10 or 12 bits) per RGB color and employ internal calculations at 10 or more bits to map input signals to output signals.

Diagram of procedural flow from the input of a video signal to display on screen for an LCD monitor with LUT and internal precision exceeding eight bits. Target gamma attributes (i.e., 1.8 or 2.2) are determined in advance based on calculations assuming no difference between individual LCD panels. Since determining target gamma attributes alone will not result in correct color temperatures, the color space is calculated at a precision greater than eight bits, and a color gamut covering the color temperature of white is configured. Corrections on the output side offset differences between individual LCD panels and result in a smooth tone curve. An LUT of more than eight bits allows color displays with more subtle tonal variations.

How does an LUT with more than eight bits improve display quality? If a catalog says an LCD monitor is capable of displaying "approximately 16.77 million (of 1,064,330,000)" colors, the unit incorporates an LUT of 10 bits per RGB color (1024 gradations to the third power = 1,064,330,000 colors). Specifically, the input signal from the PC, with eight bits per RGB color, is subjected to multi-gradation within the LCD monitor at 10 bits per RGB color, then output at the optimal display colors at eight bits per RGB color. This results in significantly smoother tonal transitions and improves hue divergence by improving the gamma curve of each RGB color in the output. A 12-bit LUT generates approximately 16.77 million optimal colors from roughly 68 billion, improving color reproduction and gradation beyond even a 10-bit LUT.

Next, let"s look at calculations for multi-gradation of an eight-bit per RGB color input signal at 10 or more bits per RGB color within an LCD monitor. Even if we use a 10- or 12-bit LUT, calculating multi-gradation at 14 or 16 bits will result in even more precise final tonal transitions. The need for 16-bit precision when the final output is only eight bits may not be obvious, but particularly when we seek to depict subtle differences between colors at a low-gradation gamut (shadow gamut), the precision of internal calculations is extremely important. In essence, the higher the number of bits used in the internal calculations, the closer the gamma curve in a low-gradation gamut to the theoretical curve.

A look at the current range of LCD monitors shows that even in lower-cost categories, growing numbers of products offer 10-bit LUTs. Nevertheless, only products at the top of their class have bit counts greater than LUT bit counts. In particular, models that process colors to the most stringent requirements, using 12-bit LUTs and 14- or 16-bit internal calculations, are ideal for color management use, targeting applications that require high-performance color.

Visual comparisons of a monitor employing an eight-bit LUT and eight-bit internal calculation with one incorporating an LUT of 10 or more bits and internal calculations of 10 or more bits shows unexpected differences. Since the latter class of products tends to feature high-performance ICs for image control, differences in picture quality are likely to be even more apparent to a discerning viewer than for entry-level products associated with inconsistent performance. When we examine the grayscale chart, models with higher bit-count LUTs and internal calculations tend to produce smoother tonal transitions and better representation of tones in shadow areas. Such products have almost no tone jumps or hue divergence and offer stable contrast in which lightness and darkness in gradation are depicted naturally. For all these reasons, we recommend a product with at least a 10-bit LUT—not just for applications that require high-fidelity color reproduction, but for ordinary PC users seeking better picture quality.

A depiction of improvements in gradation following adjustments using an LUT of 10 bits or more and internal calculations of 10 bits or more . The gamma curve is closer to the ideal, with smoother gray-scale representation.

Some high-end LCD monitors use a 3D-LUT, which takes the LUT concept even further. A traditional LUT system has one LUT for each RGB color and refers to the LUT for each RGB color when displaying a certain color and calculating the target color using the three RGB colors from each LUT.

In contrast, a 3D-LUT is a three-dimensional LUT blending each RGB color (i.e., a three-dimensional table assigning R, G, and B to each of three axes). Since the LUT includes points of intermediate gradations blending R, G, and B, it offers improved color representation for intermediate gradations and improved gray-scale accuracy.

Let"s use EIZO"s widescreen LCD monitors as examples. Model CG242W in the ColorEdge series features a 3D-LUT. The difference between theoretical values and actual measured values in intermediate gradations is smaller than with traditional LUTs.

3D-LUTs also shine when converting color gamuts in a color-management environment. They make it possible to reallocate the approximately 16.77 million colors allocated to one color gamut to another color gamut with high precision, minimizing the loss of information from the original color gamut. In addition, since the 3D-LUT offers improved color reproduction from RGB blending, the user"s manipulations and color adjustments generally have the expected results with respect to parameters such as brightness, chroma, and hue. Perhaps this is the most important aspect of performance for an LCD monitor used in color management, which above all else requires accurate color reproduction.

The number of bits at which the LCD panel operates, its LUT, and the precision of the internal calculations all significantly affect the color reproduction capabilities of an LCD monitor. In not a few cases, even products with specs that look similar at first glance can diverge unexpectedly in display tendencies. Assessing monitor picture quality from catalog specs alone is unrealistic; users should inspect an actual monitor unit with their own eyes before purchasing.

A lot of consumers wonder how manufacturers determine the LCD display panel prices. After all, display solutions such as TFT LCDs and HMI touch screens do not always come cheap. And sometimes, a few products that can indeed be purchased for lower prices may come with several quality issues.

Hence, we’ve rounded up a list of factors that influence how to display modules such as TFTs, LCD, and touch screens are priced. You can also use these factors to evaluate to whom you should place your next orders for your display solutions.

LCD fluids are used in altering the light orientation passing through glass substrates. Hence, this causes the panel’s active pixels to darken. Different kinds of LCD panel fluids provide unique characteristics and change a panel’s viewing angle, temperature range, and display clarity.

TN fluid contains liquid crystal substances that allow light to pass through by twisting and untwisting at a 90-degree angle. This display technology is available in monochrome; that is, black characters against a gray background.

The viewing angle is limited in a panel containing TN fluid. This means that the text or image display becomes harder to read if you rotate the device away from its center. The display is also not that sharp compared to displays using other technologies.

Another characteristic of this fluid is that it works well even in colder temperatures. It’s because TN fluid has the quickest response time among the other LCD fluid types.

TN fluid is considered the cheapest LCD fluid type. However, this doesn’t mean that TN isn’t widely used. The display technology is greatly utilized in digital clocks, pagers, and gas pumps.

LCD modules with STN fluid enjoy a wider display angle, greater multiplexing, higher image contrast, and sharper response than devices using TN fluids. However, modules with STN fluids may have slower response times when used in lower temperatures due to the fluid freezing inside the device.

STN fluid falls under the moderately cheap LCD module price. Furthermore, STN fluid is widely utilized in several monochrome LCD devices such as POS machines, inexpensive feature phones, and informational screens of some devices.

The CSTN fluid technology takes away the monochrome finish of the typical STN fluid devices. Red, green, and blue filters are added to the fluid module to allow a colored display. New versions of CSTN often feature a viewing angle of 140 degrees and 100ms response times.

CSTN is a bit pricier than TN and STN fluids. But it’s a good choice if you need to display color images on your LCD device. In fact, a lot of color feature phones use CSTN as an alternative to the TFT displays, saving almost half the manufacturing costs.

A device using FSTN fluid has better viewing angles and can produce a sharp black-and-white coloration. It is a good choice for devices that need to display small yet easy-to-read images.

In terms of cost, the LCD display module price of a unit with FSTN is higher compared to TN and STN. But this is concerning the better visual quality that FSTN offers.

To cap off this part, the fluids used in a screen is a big factor in determining the overall LCD screen display panel price. As you can see, the four fluid types often used in LCD screens rise in costs with respect to the visual quality produced by each technology.

The temperature range in which LCD screen displays may work varies intensely. Some displays continue to work at optimal performance even when used in cold or hot outdoor temperatures. Lower-quality LCD panels may start having glitches at the slightest change of temperature and humidity. Hence, the temperature range may have a huge impact on the LCD display panel price as well.

In hot environments– The liquid crystals may begin to deteriorate, while the electrical components will start overheating and cause damage to the display screen performance.

Now, most LCD screen panels don’t experience such temperature extremes. In fact, a typical LCD TV can operate properly between approximately o°C and 32°C (32° – 90° F). Meanwhile, other screen modules (usually the industrial-grade ones) have unique capabilities to work in even more extreme ends of the temperature scale.

If you want to look for the most cost-effective type of LCD panel for your device, then you must consider the following standard LCD unit temperature types:

Normal temperature units work well in environments that have indoor temperatures at approximately 20-35°C (68-95°F). Some LCD modules may work well above up to 50°C (122°F). Such LCD modules can be used in daily settings by the typical consumer public.

LCD units under this type are made to withstand lower and higher temperature ranges. Extreme operating temperatures may range anywhere from -30°C to 85°C (-22-185°F). Most LCD modules with wide/extreme temperature capabilities are used in extremely cold areas such as Artic places and ski resorts, as well as humid and moisture-rich hot outdoor areas.

Generally, the LCD module price goes up if the entire display unit can withstand higher temperature ranges. Those who can operate under normal temperature ranges only are usually cheaper.

Hence, you must consider the places where you’ll be installing your LCD display devices. You can’t just use cheaper LCD modules for an industrial-grade display machine. Treat your LCD panel as an investment and select a panel that will yield better screen performance that’ll last several years for you and your business.

It’s an unspoken rule, but monochrome modules are generally cheaper than color-capable ones. However, color-capable display modules may also have cost variations depending on their display capabilities.

Color LCDs have three subpixels that hold red, blue, and green color filters. Each subpixel can have as much as 256 color shades, depending on the variation and control of the voltage applied to it.

Now, when you combine 256 shades of both red, blue, and green subpixels, color LCDs can display a color palette of up to 16.8 million colors. And all these are made possible by millions of transistors etched onto the glass modules.

Display size also plays a large role in an LCD device’s color capability. Smaller screens need fewer pixels and transistors since they have smaller display sizes. These screens are also less costly to make. Now, larger screens with high color resolution and huge display sizes require more transistors and pixels, justifying the higher prices of such monitors.

A touch screen display module is more costly than a non-touch monitor module. Touch capability is integrated into Human Machine Interface (HMI) modules and is generally used in kiosks, bank ATMs, hospital equipment, and similar devices in other industries.

HMI touch screen price is also dependent on what kind of touch screen technology it uses. Here are some of the common touch technologies integrated to HMI touch screen devices:

This type of touch screen technology is made up of a top polythene layer and a glass-bottom layer separated by microdots or an air gap. This module is then attached to a touch screen controller.

Resistive touch screen panels are used in most bank ATMs and some older models of cellular phones. They carry the lowest HMI touch screen price among all other touch screen technologies.

Capacitive touch screens are the most common in the display industry today. This technology uses transparent conductors, insulators, and glass to create the panel. An electrostatic field change in the screen’s module happens when a human finger touches the screen surface. This ultimately creates signals that are sent to the touch screen controller for processing.

In general, capacitive touch screens are the most cost-effective choice for HMI machines. Since they are considered the gold standard of commercial touch screen technologies, they do come with a high price tag.

Infrared grid technology uses photodetector pairs and X-Y infrared LED components to allow sensors to pick up the touch and its exact location. Infrared grids have been used in several touch screen modules before the capacitive touch screen technology took over.

We’ve explained the following factors at length for both public consumers and business clients to understand the variations in TFT, LCD, and HMI touch screen prices.

Cheap doesn’t necessarily mean low-quality. Also, expensive options aren’t always a wise choice, either. You can maximize your buying or manufacturing options if you know how to compare LCD modules and panels depending on the specifications you truly need for your display machines and devices.

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Pataudi Road, Gurgaon, Dist. Gurugram Shop No. 6, Nikhil Complex Near Capt. Umang Bharadwaj Chowk, Pataudi Road, Gurgaon - 122001, Dist. Gurugram, Haryana

Perumanallur, Tiruppur, Dist. Coimbatore Sun Plaza, 2nd Floor, Eswaran Koil Street Triuppur Road, Perumanallur, Tiruppur - 641666, Dist. Coimbatore, Tamil Nadu

- TD1630-3 delivers touchscreen versatility, offering fantastic flexibility for retail or business settings. With advanced ergonomics, the display can tilt or layread more...

M.T.H. Road, Mannurpet, Chennai UNIVERSAL CNC HARDWARE #48-A, 1st Floor, Ambattur industrial Estate,, M.T.H. Road, Mannurpet,, Chennai - 600058, Dist. Chennai, Tamil Nadu

In order to create the shades required for a full-colour display, there have to be some intermediate levels of brightness between all-light and no-light passing through. The varying levels of brightness required to create a full-colour display is achieved by changing the strength of the voltage applied to the crystals. The liquid crystals in fact untwist at a speed directly proportional to the strength of the voltage, thereby allowing the amount of light passing through to be controlled.

In practice, though, the voltage variation of LCDs can only be achieved at a slow speed, perhaps as slow as 25ms. This may be adequate for mainly static screen applications such as office or web browsing, but leads to motion blurring on videos and games. To combat this, manufacturers reduce the screen colours from 8 bits to 6 bits per colour per pixel – from 24 bit true colour to 18 bit colour. Although this might not seem like much, it’s actually a massive drop in the number of colours that can be accurately represented on a screen.

In a true-colour monitor there are 24 bits of colour data per pixel, divided into three groups of 8 bits each giving 256 possible colour shades for the colours red, green and blue. This is known as RGB colouring, the basis of a large part of computer colour theory and practice. When blended together this system gives an enormous colour range, with 256 x 256 x 256 = 16,777,216 possible colours per pixel. If, on the other hand, the colour depth is reduced to 18 bits, with only 6-bits for the red, green and blue hues, there are now only 64 different possible shades per element. This results in 6 bit colour LCDs delivering a maximum of 64 x 64 x 64 = 262,144 colours, a massive loss of around sixteen and a half million colours!

However, there are two major advantages to losing all these colours is a much increased response time, considerably reducing motion blur. The colours that are lost are imitated through a form of dithering, and also a technique called Frame Rate Control (FRC) which displays alternate shades on successive frame refreshes to average to the desired colour in the human eye. This can produce adequate colour information for perception to be fooled, except where the difference is too great as flicker may then be seen. The second advantage is simply cost: 6 bit LCD monitors are far cheaper to produce.

As multimedia applications have become more widespread the lack of true 24-bit colour on LCD monitors remains an issue. More businesses and home users are using more demanding colour applications involving photographic or video work, CAD or DTP, so they have demanded more from their monitors.

The screen response times in LCD monitors has come down considerably, to a great extent relieving many of the ghosting and motion trail issues. However, true 8 bit colour in flat panel monitors remains hugely expensive, and only available in very high end LCD monitors. On the next page, we’ll see how TFT LCD monitors made a considerable difference to colour representation in affordable LCD monitors.

On home appliances, it is often necessary to display numbers and words to convey information, such as the current time displayed on the clock, the current temperature information on the kettle… etc. The two most commonly used displays are LED displays and LCD displays, this article will compare the advantages and disadvantages of LED displays and LCD displays, and provide a two-step quick way to quickly determine whether this product is an LCD or LED display.

LCD displays are the most common displays in daily life, from your mobile phone screen to home appliances, you can use LCD displays, but whether it is a color or black and white LCD display, in fact, the principle is the same. There are two main components within the LCD display:Backlight module

Black-and-white LCD displays are widely used in a variety of low-cost products, and the picture above is a black-and-white LCD display used in science calculator.

Advantages of monochrome LCD displays:Can show very compact information.Each display point of the calculator as shown below is very close to each other, and high-resolution text can be displayed

Power savingBlack and white LCD displays can operated without a lot of power compared to full-color LCD, when products that do not require full-color demand and need to control power consumption are often used.

CheapIf you just want to display a set of numbers or a few ICONs, the price of using a black-and-white LCD display is much cheaper than that of a full-color LCD, and it is often used in a large number of consumer products.

Disadvantages of monochrome LCD displays:Small viewing angle, not easy to use for outdoor application.Usually black and white liquid crystal display in the front view, the display is the clearest, but due to the LCD panel characteristics, as long as the side view, the clarity will be declined, outdoor will be affected by strong light, the viewing angle is not large, the clarity is not enough, LED display due to the word luminescence characteristics, there is no viewing angle problem.

Can only be used in monochromeIf you need multi-color applications, you can only upgrade to a full-color LCD display that is many times more expensive, and the LED display can simply add different colors to the LED display without significantly increasing the cost

The structure and basic introduction of the display in this article this article, compared with LCD displays, self-illumination characteristics, so that LED displays in the outdoor visibility is high, high brightness, but also no viewing angle problem. LED displays are the same as black and white LCD liquid crystals, and the display information must be designed in advance and cannot be arbitrarily transformed. The price of LED displays is between full-color LCDs and monochrome LCDs, and if properly designed, they can save the cost of achieving display performance.

This article briefly introduces the basic principles and advantages and disadvantages of two common LCD displays, and provides two steps to quickly determine whether the display in hand is an LED display, and product designers can follow these two steps to understand which display the product is used when observing the product.

The color range of a computer is defined by the term color depth, which is the number of colors that the equipment can display, given its hardware. The most common normal color depths you"ll see are 8-bit (256 colors), 16-bit (65,536 colors), and 24-bit (16.7 million colors) modes. True color (or 24-bit color) is the most frequently used mode as computers have attained sufficient levels to work efficiently at this color depth.

Some professional designers and photographers use a 32-bit color depth, but mainly to pad the color to get more defined tones when the project renders down to the 24-bit level.

LCD monitors struggle with color and speed. Color on an LCD has three layers of colored dots that make up the final pixel. To display a color, a current is applied to each color layer to generate the desired intensity that results in the final color. The problem is that to get the colors, the current must move the crystals on and off to the desired intensity levels. This transition from the on-to-off state is called the response time. For most screens, it rates around 8 to 12 milliseconds.

The problem with response time becomes apparent when LCD monitors display motion or video. With a high response time for transitions from off-to-on states, pixels that should have transitioned to the new color levels trail the signal and result in an effect called motion blurring. This phenomenon isn"t an issue if the monitor displays applications such as productivity software. However, with high-speed video and certain video games, it can be jarring.

Because consumers demanded faster screens, many manufacturers reduced the number of levels each color-pixel renders. This reduction in intensity levels allows the response times to drop and has the drawback of reducing the overall range of colors that the screens support.

Color depth was previously referred to by the total number of colors that the screen can render. When referring to LCD panels, the number of levels that each color can render is used instead.

High-speed LCD monitors typically reduce the number of bits for each color to 6 instead of the standard 8. This 6-bit color generates fewer colors than 8-bit, as we see when we do the math:

This reduction is noticeable to the human eye. To get around this problem, device manufacturers employ a technique called dithering, where nearby pixels use slightly varying shades of color that trick the human eye into perceiving the desired color even though it isn"t truly that color. A color newspaper photo is a good way to see this effect in practice. In print, the effect is called halftones. Using this technique, the manufacturers claim to achieve a color depth close to that of the true color displays.

Why multiply groups of three? For computer displays, the RGB colorspace dominates. Which means that, for 8-bit color, the final image you see on the screen is a composite of one of 256 shades each of red, blue, and green.

There is another level of display that is used by professionals called a 10-bit display. In theory, it displays more than a billion colors, more than the human eye discerns.

The amount of data required for such high color requires a very-high-bandwidth data connector. Typically, these monitors and video cards use a DisplayPort connector.

Even though the graphics card renders upwards of a billion colors, the display"s color gamut—or range of colors it can display—is considerably less. Even the ultra-wide color gamut displays that support 10-bit color cannot render all the colors.

Professional displays often tout 10-bit color support. Once again, you have to look at the real color gamut of these displays. Most consumer displays don"t say how many they use. Instead, they tend to list the number of colors they support.

The amount of color matters to those that do professional work on graphics. For these people, the amount of color that displays on the screen is significant. The average consumer won"t need this level of color representation by their monitor. As a result, it probably doesn"t matter. People using their displays for video games or watching videos will likely not care about the number of colors rendered by the LCD but by the speed at which it can be displayed. As a result, it is best to determine your needs and base your purchase on those criteria.

Glass substrate with ITO electrodes. The shapes of these electrodes will determine the shapes that will appear when the LCD is switched ON. Vertical ridges etched on the surface are smooth.

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directlybacklight or reflector to produce images in color or monochrome.seven-segment displays, as in a digital clock, are all good examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.

LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in LCD projectors and portable consumer devices such as digital cameras, watches, digital clocks, calculators, and mobile telephones, including smartphones. LCD screens are also used on consumer electronics products such as DVD players, video game devices and clocks. LCD screens have replaced heavy, bulky cathode-ray tube (CRT) displays in nearly all applications. LCD screens are available in a wider range of screen sizes than CRT and plasma displays, with LCD screens available in sizes ranging from tiny digital watches to very large television receivers. LCDs are slowly being replaced by OLEDs, which can be easily made into different shapes, and have a lower response time, wider color gamut, virtually infinite color contrast and viewing angles, lower weight for a given display size and a slimmer profile (because OLEDs use a single glass or plastic panel whereas LCDs use two glass panels; the thickness of the panels increases with size but the increase is more noticeable on LCDs) and potentially lower power consumption (as the display is only "on" where needed and there is no backlight). OLEDs, however, are more expensive for a given display size due to the very expensive electroluminescent materials or phosphors that they use. Also due to the use of phosphors, OLEDs suffer from screen burn-in and there is currently no way to recycle OLED displays, whereas LCD panels can be recycled, although the technology required to recycle LCDs is not yet widespread. Attempts to maintain the competitiveness of LCDs are quantum dot displays, marketed as SUHD, QLED or Triluminos, which are displays with blue LED backlighting and a Quantum-dot enhancement film (QDEF) that converts part of the blue light into red and green, offering similar performance to an OLED display at a lower price, but the quantum dot layer that gives these displays their characteristics can not yet be recycled.

Since LCD screens do not use phosphors, they rarely suffer image burn-in when a static image is displayed on a screen for a long time, e.g., the table frame for an airline flight schedule on an indoor sign. LCDs are, however, susceptible to image persistence.battery-powered electronic equipment more efficiently than a CRT can be. By 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes.

Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, often made of Indium-Tin oxide (ITO) and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.

The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented.Sharp Corporation. The patent that covered that specific mixture expired.

Most color LCD systems use the same technique, with color filters used to generate red, green, and blue subpixels. The LCD color filters are made with a photolithography process on large glass sheets that are later glued with other glass sheets containing a TFT array, spacers and liquid crystal, creating several color LCDs that are then cut from one another and laminated with polarizer sheets. Red, green, blue and black photoresists (resists) are used. All resists contain a finely ground powdered pigment, with particles being just 40 nanometers across. The black resist is the first to be applied; this will create a black grid (known in the industry as a black matrix) that will separate red, green and blue subpixels from one another, increasing contrast ratios and preventing light from leaking from one subpixel onto other surrounding subpixels.Super-twisted nematic LCD, where the variable twist between tighter-spaced plates causes a varying double refraction birefringence, thus changing the hue.

LCD in a Texas Instruments calculator with top polarizer removed from device and placed on top, such that the top and bottom polarizers are perpendicular. As a result, the colors are inverted.

The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of 2010-era LCDs are used in television sets, monitors and smartphones, they have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background. When no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, particularly in smartphones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).

Displays for a small number of individual digits or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment.alphanumeric or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see passive-matrix and active-matrix addressed LCDs.

LCDs, along with OLED displays, are manufactured in cleanrooms borrowing techniques from semiconductor manufacturing and using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:

Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50 and 58 inch LCDs to be made per mother glass, specially 58 inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.AGC Inc., Corning Inc., and Nippon Electric Glass.

The origins and the complex history of liquid-crystal displays from the perspective of an insider during the early days were described by Joseph A. Castellano in Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry.IEEE History Center.Peter J. Wild, can be found at the Engineering and Technology History Wiki.

In 1888,Friedrich Reinitzer (1858–1927) discovered the liquid crystalline nature of cholesterol extracted from carrots (that is, two melting points and generation of colors) and published his findings at a meeting of the Vienna Chemical Society on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss des Cholesterins, Monatshefte für Chemie (Wien) 9, 421–441 (1888)).Otto Lehmann published his work "Flüssige Kristalle" (Liquid Crystals). In 1911, Charles Mauguin first experimented with liquid crystals confined between plates in thin layers.

In 1922, Georges Friedel described the structure and properties of liquid crystals and classified them in three types (nematics, smectics and cholesterics). In 1927, Vsevolod Frederiks devised the electrically switched light valve, called the Fréedericksz transition, the essential effect of all LCD technology. In 1936, the Marconi Wireless Telegraph company patented the first practical application of the technology, "The Liquid Crystal Light Valve". In 1962, the first major English language publication Molecular Structure and Properties of Liquid Crystals was published by Dr. George W. Gray.RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what are now called "Williams domains" inside the liquid crystal.

The MOSFET (metal-oxide-semiconductor field-effect transistor) was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, and presented in 1960.Paul K. Weimer at RCA developed the thin-film transistor (TFT) in 1962.

In 1964, George H. Heilmeier, then working at the RCA laboratories on the effect discovered by Williams achieved the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier continue to work on scattering effects in liquid crystals and finally the achievement of the first operational liquid-crystal display based on what he called the George H. Heilmeier was inducted in the National Inventors Hall of FameIEEE Milestone.

In the late 1960s, pioneering work on liquid crystals was undertaken by the UK"s Royal Radar Establishment at Malvern,