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LCDs for demanding applications

 

What stands behind demanding applications? Generally speaking, we can say that these are various devices exposed to adverse factors. Among them, e.g., electromagnetic interferences, dusty or humid environments, prevailing weather conditions. They can impact the operation of the devices, even yielding damage to the module. What to do to prevent such situations?

 

If you ever used a smartphone in “extreme” weather conditions, that is, on a sunny or frosty day, you might have noticed how these factors influence your device. It is hard to manipulate; the smartphone is operating slow while the battery is dying fast. What is more, it is damageable. Such problems are common for various electronic components, including LCDs. In this article, we point out how to provide proper operation of LCDs in extreme environments.

LCDs for industry

Portable measuring devices. Among these devices, you can find, e.g., various meters, data loggers, or detectors commonly used in industry, e.g., mining or shipbuilding sectors. These devices require LCDs of heightened brightness (at least 1000 cd/m2) and extended operating temperature (at least -20~70°C). It would help if you also considered wide viewing angle to provide perfect readability of content presented on the screen, no matter viewing direction.

 

In such applications, you can use, e.g., 5-inch WF50DSYA3MNN0# by Winstar (1100 cd/m2, -20~70°C, 80°/80°/80°/80°). It supports the MIPI interface, which, although usually connoted with smartphones, tablets, or laptops, is also widely used in other portables, e.g., measuring devices. Its most important assets are high efficiency obtained with low power consumption and immunity to electromagnetic interferences. 

Human-Machine Interfaces. Currently, in HMIs, e.g., used to control the production processes, touch solutions between 5- and 10-inch are more and more often applied. To provide the best quality of the presented content, you should choose LCDs of at least 750 cd/m2 brightness and -20~70°C operating temperature. The users will also appreciate the wide viewing angle.

In these kinds of applications, Unisystem’s clients commonly use, e.g., 7-inch WF70A8SYAHLNN0# by Winstar (1100 cd/m², -20~70°C, 85°/85°/85°/85°, operated by LVDS interface). However, today, the deliveries of these kinds of products might be a bit problematic. For a few months, we have been experiencing impediments connected with shortages of some components caused by the pandemic demand for consumer electronics, e.g., tablets (one of their most popular sizes is 7-inch). Analysts say that such a situation may continue until the end of 2021. To avoid delays in deliveries, we encourage our clients to place framework orders, especially in projects with a strict lead time (contact us to learn more about framework orders). 

In the case of touch solutions to apply in industry, you should also consider other peculiar circumstances crucial for the users’ convenience, e.g., the possibility to operate in rubber gloves achieved by the proper calibration of the module. 

Let’s take a look at the other interesting LCDs to apply in the industry – the Smart Display series by Winstar, e.g., WL0F00050000FGAAASA00 (400 cd/m², -20~70°C, 80°/80°/80°/80°, operated by CAN interface). These are “out of the box” solutions that enable you to create a device’s interface on your’s own with a set of standard UI objects such as, e.g., meters and gauges, buttons, sliders, graphs, process progress icons. However, due to 400 cd/m2 brightness, WL0F00050000FGAAASA00 might not be appropriate to apply in intensely lighted spaces (learn more about Smart Display series). 

LCDs for digital signage

LCDs used in digital signage are usually intended to operate in continuous mode – 24/7. In such applications, the crucial parameter is “LED life time” – an average time of failure-free operation of LEDs that form the LCDs’ backlight specified as the number of hours followed by degradation of LEDs (learn more about LED life time). For LCDs intended for digital signage, this parameter should be as highest value as possible – prevailingly, it is about 70 000 h.

Advertising media in cities. These are various devices installed in the urban areas, such as e.g., billboards, advertising panels on stations or stops, interactive kiosks or totems, etc. In the case of LCDs set in our temperate climate zone, one of the crucial parameters is operating temperature. These solutions should be adjusted to function properly both in low and high temperatures. Then, it would help if you chose LCDs with operating temperature range between at least -20 and 60°C. (Otherwise, you need to provide LCDs with additional heating in winter and cooling in summer.) The readability of present content depends on the LCD’s brightness – at least 1000 cd/m2* and viewing angle – 89°/89°/89°/89°. Moreover, if you are going to install a device in a sunny spot, remember to use LCDs with hiTNI, which prevents the “black blotches” on the LCDs screens caused by the temporary loosing of the liquid crystals’ primary features when they are exposed to solar radiation (learn more about the liquid crystals).

In such applications, you will appreciate 31.5-inch P320HVN07.0 by AUO (2500 cd/m2, 89°/89°/89°/89°, -20~60°C, operated by LVDS interface, LED life time – 70 000 h) or 43-inch DLH4309-B by Litemax (1800 cd/m², 89°/89°/89°/89°, -20~60°C, operated by DVI, HDMI, or DP interface, LED life time – 100 000 h). Both upgraded with hiTNI. 

*As long as LCDs are not located in sunny spots. In devices exposed to intensive solar radiation, we recommend at least 2500 cd/m2 brightness (such solutions are available on Litemax’s offer). 

Passenger information carriers in public transport vehicles. These are various devices, which you can find in public transport vehicles. They are used to present, e.g., timetables, vehicles’ routes with an estimated time of approaching the next station/stop, or additional information about, e.g., current weather conditions. They can also be used as advertising media. In these types of applications, the principal parameter is not the operating temperature – it can be between 0 and 50°C, but it would help if you chose LCDs with at least 1000 cd/m2 brightness and 89°/89°/89°/89° viewing angle to provide the perfect readability of presented content. It is also worth noticing that you can not use discretionary electronics in public transport vehicles. In the case of, e.g., railway vehicles, devices need to meet the rules of EN 50155 standard, so they have to be appropriately resistant to bumps and shakes, vibrations, or interferences. 

On the Unisystem’s offer, you can find, e.g., 28-inch SSH2845-E by Litemax (1000 cd/m², 89°/89°/89°/89°, 0~50˚C, operate by VGA or DVI interface, LED life time – 70 000 h), which is compatible with EN 50155 standard. What is more, its panoramic shape will go well with limited spaces, e.g., in trains’ compartments.

 

How to protect LCDs? – additional recommendations

As described above, fine-tuning of LCD’s parameters provide protection only against such factors as, e.g., low and high temperatures. Beyond them, there are also other LCD damaging factors, e.g., dust and water. The best form of electronics protection against dust and water is an enclosure of appropriate tightness described with IP codes defined in EN 60529 standard (learn more about the IP codes). 

If LCD is combined with a touch sensor and cover glass, we suggest considering optical bonding. It is a way of combining LCDs with other components by transparent glue or foil, which are stiffened by, e.g., UV radiation. As a result, there is no air between each component, so there is no place for any contaminations causing adverse fogging (learn more about optical bonding). 

On the market, there are also a few types of coatings, which can be an upgrade for the end-user. One of the most popular is AG (anti-glare) or AR (anti-reflective) coating, which reduces the light reflections. In the case of devices located in public spaces, e.g., kiosks and totems operated by touch, you can consider using AS (anti-shatter) coating, which prevents the spreading the glass splinters when the module’s surface is damaged, e.g., smashed, or AM (anti-microbial) coating, which prevents the propagating of germs deposited on the module’s surface by the users. 

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In this article, we described chosen parameters and measures that can upgrade the operation of the device intended to use in extreme environments. We always say that each project requires an individual approach. Same in the case of such modules – you should comprehensively analyze all the factors that may influence the proper operating of the module. No doubt, it will help you choose the appropriate LCD for your demanding application. 

 Uni's Guide