thermal management of lcd displays brands

2023-01-03 12:32:11

BoldVu® displays deliver unparalleled visual performance in outdoor environments. With luminance ratings up to 5000 nits, their high-efficiency LED backlight and obsessively engineered optical stack achieve incredibly bright imagery in the face of intense sunlight – and will do so day-in and day-out for 10 full years. So bring on the sun, BoldVu’s got it managed.

Nothing will destroy a display faster than inadequate thermal management. CoolVu® is BoldVu’s multi-patented thermal management technology that extracts and expels heat from inside the BoldVu®, without exposing display electronics to ambient air or environmental contaminants, like dust, dirt and moisture and without the use of air filters – which means typically no periodic maintenance required. With CoolVu®, BoldVu® displays can operate in environments up to 122°F (50°C) without any degradation in visual performance.

BoldVu® displays are designed to live in a world of turbulence. ToughVu® cover glass shields delicate electronic components from the effects of adverse weather and vandalism. And with its low diffuse reflection, low haze, and anisotropy and bi-refringence qualities, ToughVu® glass ensures that digital imagery shines with brilliance and delivers maximum contrast, color accuracy, color saturation, and viewing angles.

As an added layer of intelligence, BoldVu® displays are equipped with a MEMS sensor which detects and reports on shock and impact events, so in the event of attempted vandalism, you’ll be in the know.

The world is full of spectacular color, and BoldVu® ensures that every one of them is accurately reproduced. The meticulously engineered optical stack achieves ultra-bright whites and super deep blacks so that every color in-between appears as vibrant as you could hope for. A billion colors never looked so good.

At the heart of BoldVu® is a sophisticated logic controller that receives data from electronic components within the display and autonomously optimizes parameters affecting image quality, chassis thermals, and power draw. With built-in intelligence, BoldVu® takes care of itself so you don’t have to.

With an embedded media player and a 13-megapixel camera capable of 4K video at 30fps, BoldVu® makes delivering amazing, interactive campaigns easier than ever. Output gorgeous graphics, measure audience engagement1 via the USB camera, and translate insights into more effective campaigns.

InfiniteTouch® is a next-gen PCAP touch sensor exclusively available on BoldVu® displays. Comprised of multiple layers of glass with index-matched sputter ITO conductors, containing no plastic films, InfiniteTouch® delivers high transmission, low reflection, and true tablet-like responsiveness, making it an incredible platform for delivering engaging interactive experiences.

The Internet of Things (IoT) is changing the way we live, work, and how cities and venues are able to offer digital services to the citizens and visitors they serve. As the IoT continues to grow the need for communications and data processing infrastructure grows with them.

An optional structure affixed atop BoldVu®, the Comms Cap is an additional housing for IoT and connectivity devices designed to extend functionality beyond the edges of the digital screen.

When you place a display out in the world, you never know what to expect. BoldVu® displays self-monitor and report on over 150 operating parameters and settings to the SmartVu® Portal. Via the secure web interface you can see how displays are performing, adjust what they’re doing, and troubleshoot errant behavior, all from anywhere you can access the internet.

BoldVu® LT Semi-Outdoor displays are designed for placement in areas protected from direct sun exposure, like in shopping malls and subway stations where its 850 nit operating luminance is bright but not overbearing.

BoldVu® outdoor displays are intended for deployment in areas out in the open and exposed to the elements. With a daytime operating luminance of 3500 nits BoldVu® is an excellent fit for a wide array of outdoor venues.

BoldVu® XT displays are for outdoor venues with big skies and ultra-bright sunlight like stadiums and raceways. When the sunglasses come out, the 5000 nit daytime luminance of BoldVu® XT still shines bright.

The CoolVu® thermal management system operates without air filters or coolants, requiring zero regular maintenance, while ensuring on-spec performance across temperature extremes (-40°C ~ +50°C / -40° F ~ +122° F).

With full product development, engineering, fabrication, assembly, and configuration under one roof, BoldVu® is a turnkey solution that makes deployment as easy as bolting to the ground, connecting power, and standing back in awe.

BoldVu® is built for as many components to be field replaceable as possible so in the event of part failure or vandalism, displays can be serviced in their installed position and back online with minimal downtime.

2 Intel, the Intel logo, and other Intel names and brands are the sole property of Intel Corporation or its subsidiaries in the US and/or other countries.

4 Power consumption based on full luminance with a white display field, averaged over 10 years of 24/7 use. All figures subject to change without notice.

Nothing will destroy a display faster than inadequate thermal management. CoolVu® is BoldVu’s multi-patented thermal management technology that extracts and expels heat from inside the BoldVu, without exposing display electronics to ambient air or environmental contaminants, like dust, dirt and moisture. With CoolVu®, BoldVu® displays can operate in environments up to 122°F (55°C) without any degradation in visual performance.

An optional structure affixed atop BoldVu®, the Comms Cap is an additional housing for IoT and connectivity devices designed to extend functionality beyond the edges of the digital screen.

2 Intel, the Intel logo, and other Intel names and brands are the sole property of Intel Corporation or its subsidiaries in the US and/or other countries.

4 Power consumption based on full luminance with a white display field, averaged over 10 years of 24/7 use. All figures subject to change without notice.

thermal management of lcd displays brands

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thermal management of lcd displays brands

The pace of development in the electronics and telecommunication fields has been accelerating in all aspects of the business. For example, electronics/telecommunications equipment has traditionally been housed in large buildings, smaller buildings (sheds) and outdoor cabinets. The introduction of electronics to the outdoor environment has imposed serious constraints on enclosure design since temperature and humidity are the two major causes of electronics failure. Since most electronic systems do not include environmentally hardened designs, the enclosure must provide an environment in which they can survive. Among the equipment/systems involved are displays such as LCD, LED and other monitors.

The use of LEDs (Light Emitting Diodes) has been increasing exponentially in the last few years. In the beginning, heat dissipation was not a worrisome problem because of the low power the LED’s used. However, their power consumption and their useful life and reliability are dependent on how their temperature can be controlled, especially in view of high-power LEDs used for illumination and outdoor signage applications. The most important goal in LED cooling is to maintain junction temperature (Tj, the temperature at the p-n junction) from rising above prescribed levels since the junction temperature is a good predictor of the useful life of the LED component. In addition, the junction temperature in many cases must be kept relatively constant since fluctuations and shifts affect the intensity and the color of the LED light output. From a thermal standpoint, junction temperature, as with many other electronic components and systems, is influenced by power levels, heat sinking (high conductivity materials, convection cooling, extended surfaces, heat spreading, heat pipes, etc), ambient temperature, interface materials, applied pressures (clamping to reduce thermal contact resistance).

Thermal management of LEDs can range from the use of natural convection to the use of liquid cooling loops that allow for far higher heat removal rates than employing gases as the cooling medium. Air natural and forced convection, up to very recently, have been the cooling methodology of choice when cooling with a fluid. At the system level, and especially for outdoor applications, liquid cooling is normally not suitable; therefore, only cooling solutions that use natural or forced air convection are employed such as fans, blowers, air-to-air heat exchangers, air-conditioners and other passive cooling techniques.

What is more, display devices such as monitors have incorporated LED technology and must also be thermally managed outdoors since they require hardened enclosures to carry out their tasks.

The objective here is to cover the thermal management of LEDs at the system level, both discrete LED modules or outdoor enclosures (LED walls or LED monitors). This assumes that LED and board level thermal management has been dealt with separately. Nowadays, enclosures that contain LEDs are being installed in various environmental conditions. Most will be fitted with either air conditioning/thermoelectric cooling or air-to-air heat exchangers as needed because of relatively high heat dissipation requirements; for lower heat generation levels, flow-through fan cooling is sufficient. For example, there has been an unprecedented growth of the application of LEDs for outdoor (and indoor) signage or video systems such as sports displays, advertising billboards, and gas station pump customer information displays. These all are enclosures with one wall comprised of LEDs. In addition, recently LED display monitors have been installed in outdoor enclosures and therefore require thermal management. Figure 1 shows an illustration of these two types of enclosures.

The goal is to maintain peak temperatures in the enclosures below a certain level that is normally prescribed (the lowest junction temperature of the LED components) by the manufacturers. Humidity levels are of concern, but since most enclosures are either sealed or its temperatures are much higher than the air’s dew points, humidity is generally not a problem (after the transient effect of opening/closing the enclosure is eliminated.)

The designer should be aware that the air temperatures within the enclosures will be a function of: the amount of heat generated by all the electronic equipment in the enclosure; the amount of heat generated by auxiliary and cooling equipment (fans, etc.); ambient conditions (outdoor air), particularly temperature, solar radiation, wind speeds, etc.; objects surrounding the enclosure (shading, ground reflections, buildings, trees, etc.); enclosure design (surface area, shape, paint’s radiation characteristics, etc.) and air exchange with the outside air, either passive by infiltration, or active by fans or blowers.

Let us consider an enclosure that has installed LED equipment that dissipates a certain amount of heat. The first step is always to realize that the design temperature is that temperature that the enclosure air will attain when there is heat balance, or in equation form:

where, Qequipment comprises the LEDs and its electronics heat dissipation, Qsolar load is the solar heat load and Qcooling-system is the amount of heat removed by the cooling system. The solar load is a complicated term because it includes contributions from all modes or heat transfer. For example:

Normally, the value of Qradiated will always be positive (towards enclosure) but the other two can be either positive or negative, depending on the enclosure’s temperature. Thus, if Qbalance is not zero, this means that the temperature inside the enclosure is either higher/lower than the set temperature and the enclosure is losing/gaining heat by convection and conduction.

Furthermore, since incident solar radiation varies during the daylight hours, the designer must decide whether to conduct a steady state or transient analysis. Moreover, since Qradiation is a very complex term that includes, among other effects, solar declination, latitude, time of year, solar azimuth, atmospheric absorption, atmospheric clearness, re-radiation from other walls, buildings, ground etc., and incident wall surface properties, some simplifying measures must be taken into account. The result is that one can effectively double or triple the amount of heat flux being added into the enclosure depending on the calculation method. The calculation of the cooling load is carried out using several methods. One of these methods is the ASHRAE’s cooling load calculation methods. Normally, when calculating cooling loads, one would include a) Space heat gain, b) Space cooling load, and c) Space heat extraction rate. Space heat gain is the rate at which heat enters or is generated within the space at any given instant. This includes for the enclosure heat transferred into the conditioned space from the external walls and roof due to solar radiation, convection and temperature differential.

One normally includes instantaneous solar radiation effects and delayed effects. The delayed effects include the slow build-up of energy that the external walls accumulate as they absorb solar radiation. This happens because walls are normally thick and massive; making energy absorbed important. For LED enclosures this is not included since its walls are thin (at the most 3 cm when insulation might be added) and should not be included. Another component of heat gain is latent heat due to moisture infiltration. For sealed LED outdoor enclosures, the power electronics are kept in an airtight enclosure with negligible contribution.

where, α -absorptance of solar radiation surface, It – total solar radiation [W/m2], ho– coefficient of heat by long wave radiation and convection [W/K-m2], ε – hemispherical emittance, and ΔR a radiation correction factor [W/m2]. Figure 2 shows typical Sol-Air temperatures for various latitudes.

For roofs: ΔR =63 W/m2, for walls: ΔR = 0, for dark surfaces, α/It = 0.052, which is the maximum value for any surface. To calculate heat transfer into the conditioned space,

where U is the overall heat transfer coefficient for the wall and A is the surface area for the wall. The term, U, includes convective and radiation effects by the internal and external airflow (See AHSHRAE’s Fenestration Chapter for more details, ASHRAE, 1981, 1986) and the wind outside, in addition to conduction through the walls. The solar load calculated will be added to the equipment load to find the total cooling load. The solar load will include three surfaces that can be illuminated simultaneously, with the roof always included.

Display/signage enclosures have evolved. Typical LED system design has been the display shown in Figure 3. They typically were metal enclosures measuring 5-10 m wide, 250 mm deep and 5 m high. These enclosures could have thousands of LEDs each measuring, typically,5- 8 by 5-8 by 3 mm and dissipating an average of 1W each, all installed on the largest vertical wall. Therefore, the total amount of heat dissipation for this enclosure (including the electronics needed to control and manage the LEDs) could reach thousands of Watts. Figure 3 shows a CFD model of this enclosure using Phoenics by CHAM Ltd of the UK.

In the last few years, display outdoor enclosures are also being designed to house various display signage equipment configurations such as LED monitors with dissipating heat rates ranging from 200 to 1500 W, depending on the size and type of auxiliary equipment. These enclosures are installed in various environmental conditions, and typically the enclosures, without major structural modifications, may be fitted with fans, air conditioning or air-to-air heat exchangers as needed. Figure 4 shows at typical enclosure (CFD model).

Equipment housed in these enclosures include TV LED monitors that have been initially designed for indoor use and have been slightly hardened to be placed in a hot, dry environment without the support of an enclosure. Many manufacturers sell these monitors.

The goal of the designer is to maintain the peak temperatures in the enclosures, which are below a certain level that is normally prescribed by the electronic equipment manufacturer. Humidity levels are also of concern, but since in most enclosures, its temperatures are much higher than the air’s dew points, humidity is generally not an issue (after the transient effect of opening and closing the enclosure is eliminated). However, typically, the LED monitors are not fully outdoor rated, that is they must be protected from rain and moisture, therefore they must be installed in IP55/56/66 enclosures.

Most enclosures need to be designed to keep the system operating with slight internal overpressure. Cooling air is guided to flow into a gap between the LED screen surface and external transparent wall guided by guide-vanes, and the cooling system also must allow for air to flow to the rest of the enclosure, in addition to the flow in the LED/Wall gap. Overpressure is used to maintaining IP55 and IP66 design and a fan and filter inlet system construction allows for proper solar mitigation technology. For further solar mitigation purposes, if used, a solar shield overhang can reduce solar loading.

Finally, of paramount importance is to keep the LED surface (especially when in full solar exposure) under a maximum temperature. For the above LED monitor, this temperature is 110 C. Since, maximum solar radiation for latitudes below 35 N or S can generate surface temperatures higher than 110 C, then a typical construction would involve a gap between the outdoor facing glass plane and the LED monitor (see Figure 5).

thermal management of lcd displays brands

Here is a picture inside the TV without the rear cover. The power supply includes the inverter stage for the backlight panel using only two HV transformers. Such design idea sounds very good because all EEFL tubes are connected in parallel avoiding the use of small transformers/inverters stages for each lamp minimizing in this way electronic issues on the backlight stage.

Compared to former CCLF, the new EEFL shows superior performance and applications. This incredible technology combines low power consumption and enhanced luminescence as compared to similar lighting sources. The most attractive feature of EEFL (External Electrode Fluorescent Lamp) is the absence of electrodes in the discharge tube, which is the main factor limiting lamp life. Electrode burn-out is the main cause of fault in CCFL. Because each CCFL lamp need its own ballast the new EEFL technology is simpler in electronics circuitry reducing in this way the rate of failures. EEFL lamps consist of a completely enclosed glass tube with external metal electrodes at both ends. This design minimizes electrode burn-out and results in a longer lamp life. Because the electrodes in former CCFL technology are in direct contact with the rare gasses, CCFL run warmer than the EEFL which are completely cool. On average, EEFL lamps have a lamp life of over 50,000 hours.

I figured out that three main areas on the circuit layout requires additional cooling. The hottest part was the digital class D audio amplifier (STA381BW) because overheats to much (manufacturer datasheet claims approx 3 watts of heat dissipation !!!) so I put a passive aluminum cooler to cool it down. Because the rear plastic cover touched the cooler I cut one of the corners. Using a smaller one was to weak to cool down the device at safe temperatures.

The digital scaler image MT5366 processor and glue logic ICs are located below a metallic RFI shield acting at the same time as a heatsink. Unfortunately the metal shield in use affects the efficiency on thermal conductivity of heat because is to thin leading to hot spots on the components. To correct such design issue the most convenient is to install a passive cooler. To cool down the MT5366 system on chip platform processor an older 486 mother board heatsink (the black one after changes third picture below) do the job well. The use of a thicker heatsink improves the thermal conductivity (spread of heat) avoiding hot spots on the devices.

The last part that requires additional cooling was the HDMI switch inputs selector (SiI9185 device schematic picture above) soldered on the right corner next to the HDMI inputs. Its based on the HDMI 1.3, DDC, HDCP specifications including a CEC (consumer electronics control) single wire bus interface to transmit I/O remote commands through a home network and EDID display identification (plug & play feature stored on serials EEPROMs). Researching datasheets from other versions I figured out that the device in operation consumes approximately 1.5 watts average but such information is not released by manufacturer. The device reach a working temperature of approximately 100 grads Celsius when HDMI inputs are enabled receiving stream data. Watching TV channels (digital DVB or analog cable) the HDMI switch remains cool because is in power down/suspend mode. At glance the HDMI switch overheats only when the inputs are enabled. Without an appropriate heatsink the life endurance of the device is affected because such operating condition can lead to a short circuit on terminals due silicon breakdown !!! . The HDMI switch integrates electrostatic discharge protections on its inputs up to 2kV discarding any possibilities of damages due weak ESD spikes but strong lightning electromagnetic discharges are a big problem without ESD protectors.

In the case of factory cooling all mentioned devices use the "ePad" enhancement, a small metal surface below the IC core case to transfer the silicon heat to PCB board. Despite the idea to reduce manufacturing costs avoiding in this way the use of external heatsinks such cheap PCB cooling solution is not appropriate at all. We verified on all the mentioned devices an excessive heat that unfortunately can lead to operational malfunctions/issues leading to a short durability.

After changes the overall heat is reduced due the improvements on heat conductivity and air convection cooling reducing the average working temperature on overall components avoiding at the same time hot spots on digital ICs (core of the silicon device).

To improve more the cooling on the T-Con LCD panel board we put a SinoGuide TCP400 series thermal pad on the main IC to increase the heat transfer on the metallic shield (this is more thick in diameter and seems to be OK for cooling purposes).

thermal management of lcd displays brands

The displays feature a Full HD or 4K LCD with a high brightness LED backlight producing an image up to 1,000 nits. The DI Series features models which are dust proof IP5X rated for protection from contaminants and debris and features a fanless thermal management system for virtually silent operation. With the industry’s thinnest form factors—as thin as 29 mm—the displays are ideal for premium high-end applications such as retail and banking environments.

thermal management of lcd displays brands

Taking into account the conditions inherent to digital billboards and multimedia kiosks, particularly for outdoor, it can be said that the key element of these systems is, besides ventilation, temperature control.

Strongly recommended, the thermal management of the equipment ensures the normal and correct functioning of all components – besides avoiding their deterioration.

PARTTEAM & OEMKIOSKS, aware of the importance of temperature and ventilation systems, seeks to ensure maximum efficiency and reliability in all its products.

The requirements of an internal environment are easy to understand, since there is total control of the environment and a certain stability. This makes digital billboards or indoor multimedia kiosks don"t require as much care as outdoor equipment.

Therefore, outside, there are other attentions that must be taken, being the primordial element of this system the control of the temperature. Moreover, PARTTEAM & OEMKIOSKS has a proprietary system – CROXTHERM® – for thermal management and display cooling.

Temperature management ensures that all system components function correctly. Through this management, stains are prevented, more specifically when the temperature on the screen surface is high; good levels of performance are guaranteed and a long life of the integrated components is ensured.

Junction temperature: The junction temperature is the active region of the LED. This is where electrons jump between the two semiconductors to produce photons. A low junction temperature helps LEDs to produce more light. The junction temperature is affected by current, thermal path and ambient temperature.

Although it is important to ensure that any outdoor display can withstand the weather, it is equally important to ensure that it withstands the varying temperatures of an outdoor environment.

Both cold and heat affect LCD displays. Therefore, it is important to consider thermal management, since it protects the equipment from the outside temperature, ensuring image quality, low power consumption and component conservation.

In a structure, in case the relative humidity of the air is 80% and the temperature is 30ºC, the air will contain approximately 25 milliliters of water. If the temperature drops to 15ºC, the air will contain about 13 milliliters with the same humidity.

The other 12 milliliters condense. At first it may not seem like much, but with the natural movement of air, this amount is concentrated in the coolest parts of the equipment.

PARTTEAM & OEMKIOSKS sun protection foils offer several advantages throughout the year, adapting to both the exterior and interior. In addition to being able to control light, they ensure thermal optimization. In other words, they allow better insulation in winter and a significant reduction of heat in summer.

A glass covered with these sunscreen foils can prevent infrared radiation, controlling peaks of light and reducing them to a level pleasing to the human eye. This creates effective protection for the equipment.

Faced with the fact that outdoor kiosks are subject to adverse environmental conditions that can affect the performance of sensitive electronic components – from extreme temperatures to humidity and dust –, this equipment must be prepared to maintain its internal temperatures, regardless of climate.

For indoor kiosks, extreme temperatures are less risky, so the ambient temperature tends to remain constant. Often, these kiosks maintain their temperature through convection ventilation. However, if the structure is overheated, a fan can be used to dissipate the heat from the electronic components and the upper ventilation of the kiosk.

The ventilation systems cool the components of an equipment, guaranteeing the quality of the air that circulates and preventing the infiltration of pollutant gases, bacteria and humidity.

This effect is controlled in all projects, studying the location and positioning of the equipment in order to analyze the position of the sun during the day and to understand if it will harm its use.

For a good functioning of our kiosks, an efficient and correctly tested ventilation is essential. Perfect air circulation must be guaranteed at all times. For this reason, air inlet and outlet flows must be measured at regular intervals.

One of the most effective ways to avoid the heating of a digital signage equipment is through the use of air conditioning, which regulates the air temperature according to the billboard"s temperature.

In this case, if there is no “connection” with the exterior – other than through air conditioning – the entrance of humidity, dust and water is avoided.

Studies have shown that electronic components tend to last longer if temperatures remain low. But there are other factors in the structure that must be considered, such as the risk of condensation and energy costs.

In fact, the important thing is to maintain a stable temperature and not necessarily low in the equipment. The ideal recommended temperature is approximately 25°C, protecting the components, minimizing the risk of condensation and reducing energy costs.

Thermoelectric cooling uses the Peltier effect to transfer heat from one side of the device to the other. It can be used for heating or cooling (although, in practice, cooling is the main application).

In order to combat the high temperatures in some locations, PARTTEAM & OEMKIOSKS kiosks are covered with thermal insulation. That is, they are prepared to allow a lower heat exchange, so that the external heat is not felt inside the kiosk and the cooling system has a higher efficiency.

At PARTTEAM & OEMKIOSKS, the equipment is designed with intensive quality testing. Firstly, a study is carried out taking into account the heat dissipation of the components and the place where they will be installed – analyzing the average ambient temperature and sun exposure.

On the factory floor, the kiosks are placed inside a greenhouse with projected heat sources – where they stay for several hours –, and this test is monitored through data collected by sensors scattered over several areas of the kiosk. The objective is to understand if the heat is becoming concentrated and putting in question the functioning of some component.

Tests are also performed with cooling and ventilation systems to see if the correct system is being used. If necessary, a readjustment is made during the assembly process to ensure the proper functioning of the equipment.

thermal management of lcd displays brands

Many cities around the world, especially Paris and other European cities, are seeing heat waves like they’ve never known this summer. Record-breaking temperatures swept across the continent, impacting Europeans, many of whom don’t have air conditioning in their homes.

These extreme temperatures can also harm digital displays, which are typically designed to operate between 32 and 90 degrees Fahrenheit. However, as the temperature increases for long periods, like the intense European heat, which reached 108.7 degrees Fahrenheit in Paris, digital signage may experience issues or even stop functioning.

Because heat damage has been so prevalent this year, it’s essential to take a moment and think about how to protect your displays. Even if you haven’t been affected by the recent heat waves, consider your area’s climate and whether or not your devices are protected.

If you’re worried about heat damage or live in an area where extreme temperatures are prevalent, consider exploring a custom solution. Manufacturers can often create screen enclosures complete with fans or an internal heating unit. Each of these elements helps air circulate within the displays, thus stabilizing the internal temperature. Some custom work can protect devices from temperatures ranging anywhere from -22 degrees to 131 degrees Fahrenheit. Thermal management technology is an ideal safeguard for when temperatures fall outside of the optimal operating zone.

Whether outside or indoors, protecting your displays from direct sunlight is crucial. Direct sunlight will not only increase a device’s overall temperature, but it can also create specific hotspots. Hotspots refer to areas of high heat that can lead to permanent scarring of the LCD, LED or plasma screen. In LCD screens specifically, direct sunlight can cause the Liquid Crystal cells inside the display to boil, leaving behind a black spot. This phenomenon is known as solar clearing. If the LCD screen overheats, it can also lead to isotropic failure, and you may need to replace the device. Position digital signage out of direct sunlight, whenever possible. Whether inside a custom screen enclosure or under a tent or awning, this tactic will extend the life of your device. At least very least, provide proper airflow to keep the displays cool and functioning properly.

Anti-glare glass protects your screens, as well. They deflect the light, improving readability as well as keeping your digital displays cool. Do your research first, though, as some anti-glare displays will reduce visibility for people wearing polarized lenses.

Temperature regulation should be a key player from the beginning of your digital signage deployment. Installation should begin with a site assessment to determine where to place your displays to avoid hotspots and solar clearing as well as optimize the user experience. Installers should also understand how sunlight and heat affect digital displays, not to mention how the devices themselves can generate heat after being powered on for long periods.

Kinettix has a global partnership of field techs who understand the inner workings of these displays and are ready to help you with your digital signage deployment. Our skilled partners know the importance of digital signage thermal management and know when to recommend increased protections.

thermal management of lcd displays brands

With more than 3,300 employees in production and engineering and with factories in China and Taiwan, Powertip is a leader in LCD displays. Founded in 1991, Powertip now has more than 90,000 m2 of production space and can therefore effortlessly respond to all issues and developments in the market for a wide range of LCD technologies and applications.

Within LCD manufacturing, Powertip has many different products on offer, with more than 79 standard series and more than 1,000 different model configurations. This makes Powertip a uniquely positioned manufacturer with an exceptional diversity and flexibility in development and production.

Powertip has with an ISO quality certificate and a reputation for being a very proactive and innovative player built up a leadership position in the current display market, reinforced by a global network of reliable, representative partners. This makes the application of Powertip displays a safe choice. For use in a wide range of applications and machines, Powertip can offer the right display solution.

thermal management of lcd displays brands

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.

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.

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