Overview

Many applications of displays involve installation in environments having a high humidity level. Of specific importance in this regard is the marine environment. In this application, an LCD, OLED or Plasma monitor, no matter how well sealed, will eventually “inhale” moisture within the enclosure. Once inside the enclosure, it is extremely difficult to remove the water vapor. As a result, the protective clear window installed in front of the display will develop a fogged appearance when it becomes chilled. Ways in which it can become chilled include direct impingement of air conditioned air onto the face of the display or spray impacting the outside. The fog which develops inside of the window is frequently difficult to remove without heating the glass or opening the display. General Digital™ Optical Bonding Laboratories™ has developed two distinctly different ways to prevent this from being an issue.

The first technique is to optically bond the window to the flat panel display. This eliminates the air space between the display and the window, thereby eliminating moisture entirely from the space, and hence, the problem of condensation.

The second technique it to provide a hermetically sealed window which includes a desiccating gasket as a part of the seal. This window is, in effect, a custom thermo-pane window tailored to the display. The following paragraphs will describe in more detail the trade-offs in this design.

Basic Design

Two pieces of glass are held in close proximity to one another and are sealed by a specially designed gasket. This gasket, in addition to providing a spacer for the protective window also excludes interchange with the ambient air. The adhesive used is designed to provide a moisture absorbing (desiccating) ability. Thus, as time goes on, the moisture content between the two pieces of glass will actually decrease. In addition, the dead air space between the two glass surfaces forms a thermal barrier, preventing the inner glass from becoming chilled when the outer surface is chilled. The overall effect is to eliminate the fogging which otherwise could occur.

Both our experience and the information from manufacturers of similar products show that the moisture content of a desiccant sealed optical window remains below 10% RH for years. Consequently, in the absence of mechanical damage to the protective window, the display will never be subject to condensation fogging.

Comparing the mechanical design of the sealed window to other designs, we find that this approach adds depth to the display. The thinnest design we would recommend is 7/16″. This is composed of two pieces of 3 mm glass, spaced apart by the thinnest desiccant gasket available (3/16″). In addition, there will need to be a small air gap between the inner layer of the window and the LCD, OLED or Plasma display. Compared with a 3 mm protective window, we need an additional 5/16″ inch in the display depth. Optical bonding does not add this extra space.

The trend for LED backlights in TFT displays are increasing at a rapid pace. More and more suppliers are offering new LCD sizes and formats on a regular basis.

NEC is introducing 5 new TFT’s incorporating a newly designed LED units that achieve both long operating life of 70,000 hours and low power consumption in the backlight system.

The main characteristics of the new modules are as follows:

1. Long-Life and Low-Power White LED Unit
The newly designed white LED unit, outperforms conventional cold-cathode fluorescent lamps (CCFL) with an operating life of 70,000 hours at room temperature (25 degrees Celsius). It reaches an operating life of 60,000 hours at a high temperature of 60 degrees Celsius, and boasts high reliability that is ideal for display devices in industrial equipment exposed to severe environmental conditions. All new modules reduce power consumption by more than 20 percent compared to conventional CCFL backlight systems.

2. Compatibility
Each of the new modules is compatible with NEC LCD Technologies’ conventional standard products of the same size in relation to outer dimensions, position of mounting holes, and screen center. Each also maintains signal compatibility with conventional products. Thus, the modules can be replaced easily without the need to change any of their peripheral appliances.

3. Wide operating temperature range
A wide operating temperature range, from –20 to +70 degrees Celsius, guarantees operation even in extreme conditions. Moreover, the luminance of the white LED backlight performs exceptionally well under low temperatures, even from initial startup.

Material referenced above can be found on NEC’s web site:

http://www.necelam.com/news/newsdetail.html?page=long_life_low-power_white_led_for_industrial_display#1

Posted by: John Clauson, Feb 16, 2009

Toshiba America has released five new Industrial TFT modules that incorporate an LED Backlight with a 70,000 Hour MTBF; or, in simple terms, approximately 8 years of continuous operation (to half brightness of the initial luminance specifications).  This spec equals and exceeds what is common with traditional CCFL backlight products.  The Benefits of the LED backlights are lighter weight, lower electrical noise, low power consumption, instant “on” and better performance in cold temperatures, better shock & vibe, and a wider adjustable luminance range.  These panels are also designed with a replaceable backlight structure and Toshiba has added the LED driver circuitry to the electrical interface which simplifies design and sourcing concerns. These panels are ideal for a myriad on industrial applications:

For additional information, please email ask.LCD@avnet.com. Specs for these modules are also available below:

http://www.toshiba.com/taec/components/Datasheet/LCD/LTA057A343F.pdf

http://www.toshiba.com/taec/components/Datasheet/LCD/LTA065B0D2F.pdf

http://www.toshiba.com/taec/components/Datasheet/LCD/LTA084C271F.pdf

http://www.toshiba.com/taec/components/Datasheet/LCD/LT084AC37000.pdf

http://www.toshiba.com/taec/components/Datasheet/LCD/LT104AC36100.pdf

For more information on this TFT module, check out these documents:

lq150×1lg82_pa

Overview

As more and more LCDs find their way into outdoor applications, the need becomes far greater for them to not only be able to withstand severe temperature extremes (heat and cold) and solar radiation, but the LCD must also be readable when exposed to extreme optical conditions such as direct and indirect sunlight, glare and reflection. On an average sunny day, the illumination of ambient daylight is approximately 30,000 nits. Therefore, a TFT’s brightness should be over 900 nits to get a clear image for an outdoor application.

Most off-the-shelf LCDs are not properly equipped to handle all of these requirements. There are  several brightness enhancement solutions to meet/exceed our customers’ requirements.

Benefits of Brightness Enhancements for TFT Modules

• Increase brightness up to 100% with enhancement films alone
• Improve display contrast and readability
• Improve display clarity and image quality
• Superior uniformity
• Improved operating temperature range and brightness

Options

Both passive and active backlight modifications can dramatically improve sunlight readability. One of the most efficient and cost-effective solutions is the GenFlective™ display, a hybrid of transflective and passive enhancements. Avnet also offers a standard transflective display, which incorporates a highly reflective polarizer that reflects ambient light back out of the display. Thirdly, Avnet provides the traditional value-add backlight solution, an active enhancement featuring your choice of CCFL, LED or NVIS backlight technology.

Passive Enhancements

Benefits of GenFlective™ Technology

• Requires no more power than OEM panel
• Dissipates no more heat than OEM panel
• Simplifies integration of value-add display
• Easier to address cooling due to low power
• Can often be combined with other passive enhancements (optical bonding) or active enhancements (sunlight/daylight readable backlights/edgelights)
• Typical enhancement of OEM luminance of 20% to 100%

A GenFlective™-enhanced LCD is a display that has been altered, using passive enhancements, to improve the brightness (transmissive and/or reflective) and/or the contrast of the display. Although each display has its own personality, due to differences in design, manufacturing techniques and in the stock film stack, our value-add partner can typically enhance the performance of an OEM panel utilizing Optical Management Films, Polarizers and Diffusers, and a multitude of films and coatings (Contrast Enhancement, Index Matched, Antireflective, etc.)The display would be characterized under darkroom conditions and three different simulated daylight conditions. We would then do an evaluation of the OEM films in the LCD and modify this configuration as we deem reasonable. We will do up to four iterations of backlight film modifications and submit the data to you, along with our analysis of what the data tells us. 

Transflective Panels

Although they are designed to reflect ambient light back out the display to augment its performance in direct sunlight, transflective panels have insufficient transmissive luminance (typically ~200 nits) to be considered usable in diffused lighting conditions where direct sunlight is not available (e.g., cloudy or rainy days).

Original Post by Bob Waddell, Dec. 7, 2008

In recent years, the 7.0″ wide VGA (800 x 480) digital TFT has become one of the most popular displays in the world. The consumer applications are numerous – portable DVD, rear seat entertainment and especially digital photo frames use this display in the tens of millions annually. There is a great deal of interest in this product for commercial and industrial users too, and for good reason:

• A 7.0″ wide TFT has an active area of approximately 6″ x 3.6″, which is easily visible
• The wide format display makes it a perfect choice for applications where two windows are desired – say, one window for a graphic image, the other for related data
• It is large enough to have a touch screen that can be easily used

However, the immense volume of the 7.0″ WVGA in the  marketplace has created an issue in the industrial space. The TFT manufacturers who focus on the industrial market are committed to supplying displays that provide the following key features:

• Long term support — minimum 3 to 5 years
• Wide operating temps — -20 to +70C is standard
• Backward compatible design changes — if a product is modified, it is relatively transparent to the user: Mounting hole locations and connectors don’t change; interfaces and pinouts don’t change; and the supply is not interrupted.

The high volume of 7.0″ consumer displays has driven prices down so low that many of the industrial suppliers initially did not offer a product. Consumer suppliers, when seeing a periodic slowdown in demand, would flood the market with their products at prices far below what the industrial TFTs can build them for. It is not unusual to see a consumer-grade 7.0″ WVGA TFT available at a fraction of the cost of an industrial display.

There are now several industrial TFT suppliers that offer a 7.0″ WVGA TFT in a variety of configurations:

• LED or CCFL backlight
• Up to a -30 to +80C operating temp
• With or without touch
• TTL or LVDS interface

None of these are available at pricing comparable to the consumer products that come into, then exit, the industrial space. But that is not the market that they are competing against either.

Every OEM company needs to do what is in their best interest when it comes to deciding what display is the best choice for their product. It is extremely important to keep in mind that long-term availability, a consistent product offering and uninterrupted supply can save a tremendous amount of time and engineering resources just a few years down the road.

Photo of an Industrial 3.5-inch TFT Module from Sharp

New designs for industrial applications using thin film transistor active matrix LCDs (better known as TFTs for short) are booming. Pricing for TFTs continue to decline as new fabs come on line, new techniques to improve manufacturing efficiency are implemented and overall TFT supply continues to grow. Although these new fabs generally support consumer goods (televisions, monitors, MP3 players, GPS & Navigation devices, phones, etc.), they also help the industrial market by freeing up space in the lower-gen fabs which means greater capacity for industrial-grade glass. Many customers are moving away from older technologies (i.e. STN, CSTN, etc.) in favor of TFTs because of relative price parity and the inherent superiority of TFT optical characteristics. Another driving impetus for increased TFT demand is power, or lack thereof.  The evolution of low-power TFTs and low-power semiconductors now allow TFTs to be used in applications previously unthinkable. Hand held applications abound across all vertical markets and the age of the Dick Tracy video communicator wrist band is here (in fact, we’re helping many companies design very similar products).

And, of course, as costs for TFTs keep dropping, new designs for TFTs come out of the woodwork (literally…and you’ll see what I mean in a minute). Because of low cost, abundant supply, better power characteristics, improvements in overall TFT technology, etc., many customers that have never designed with TFTs are now doing so. Why? Well, at the very least, to make their products more appealing because it’s universally accepted that TFT’s are cool. And TFTs can help anyone’s product look cool too. On a more practical level, these new, non-traditional TFT customers may also be looking to provide a quantum leap in user interface or performance or usability or ruggedness. The obvious example of this phenomenon would be in instrumentation and test equipment, where it only makes sense to upgrade analog or passive displays to something faster, more accurate, more intuitive and something more cool (because marketing is an important aspect of any new design). However, my favorite example of new non-traditional customers now designing with TFTs is a medical OEM who has been one of the largest manufacturers of x-ray light boxes. Historically, this customer purchased lots of wood, opaque plastic and hardware. However, as TFT technology continues to evolve (in combination with our nation’s investment into health care, HIPPA legislation and the continuous technological overhaul of our nation’s hospitals), this non-traditional customer is looking to replace their conventional light boxes with high-resolution, multi-megapixel displays that can pull-up patient x-rays and other medical scans (along with other pertinent patient data) from the server instantaneously. This customer is a great story, but there are many more just like them.

Although the market and supplier base for TFTs is fairly mature — the industrial TFT market was established well over a decade ago — the rapid adoption of TFTs for new designs combined with the influx of new TFT sources out of Asia has stirred up the supply chain and caused some confusion among industrial customers. In many respects, it’s the Wild West and paradigms are shifting.

Most notably, the heavy adoption of TFTs within the consumer market has resulted in rapid price degradation for consumer display. As a result, many engineers like the look of these consumer displays and, more importantly, they also like the low cost of these consumer displays as well. Consequently, we receive calls everyday where an engineer has cracked open the latest commercial navigation device, DVD player or monitor in an effort to base their new design on the TFT embedded within the device.  Once these customers move down the path with their design effort, however, they find it near impossible to find engineering support or stable supply. Worse yet, consumer displays are constantly being spun to improve yields, performance, etc. which cause tremendous life-cycle issues for OEMs who don’t want to continuously redesign the display. In other words, even if you’re successful in designing in the display and can find a stable source, the product will probably have a very short life cycle which will force another redesign.

So what does this mean to me (the Industrial OEM)?

The large numbers of manufacturers who have emerged to support this growth market combined with the massive number of new displays available to the market make selecting the right TFT extremely difficult, especially for engineers splitting time on other components of the new design. I’ve also found that company’s designing solutions with TFTs generally don’t want to redesign after 6-9 months, especially when the initial design took upwards of a year to complete. Unless a company is prepared to invest resources to redesign on a regular interval, they need to lock into a product that incorporates terms and conditions more conducive to industrial applications. In others words, these OEMs need to design with truly industrial panels rather than consumer displays.

So what’s the difference between an “industrial” display and a “consumer” display?

The principal difference between industrial and consumer displays is longevity — an industrial display will be available for a minimum of 3 years (and well beyond that in many cases). These panels are not built on the latest generation fab, which will make them more expensive to manufacturer than panels produce on the latest and greatest fabs; however, this very fact also helps the TFT manufacturer alleviate the pressure to continuously spin their TFT designs. Generally speaking, a good industrial display will incorporate the following key attributes:

• Longevity – look for a 3+ year guarantee for mass production (MP) and take note as to when your desired panel actually went into production
• 6-Month EOL Policy – a 6-month end-of-life (EOL) policy  providing up to 6 months to place a last-time buy (LTB) is extremely important to help bridge the supply chain until the TFT re-design is complete, especially for applications where new certifications are required
• Industrial Roadmap – a strong industrial roadmap with follow-on drop-in replacements for products that are slated for EOL; backward compatibility is extremely important for a quick re-design and most industrial TFT suppliers offer this feature
• Field-Replaceable Backlight – over the life of the panel, a backlight will eventually fade (or fail), so replaceable backlights are a quick, inexpensive way to improve total cost of ownership (TCO) and overall service
• Shock & Vibe – industrial panels are typically much more rugged that consumer panels
• Better Overall Optical Characteristics – industrial panels typically have much improved optical characteristics such as brightness, viewing angle and contrast ratio
• Op Temp – -20 degrees Celsius to +70 degrees Celsius is fast becoming the industrial standard and some suppliers are now offering -30c to +80
• Engineering Support – in addition to the Avnet team, most industrial display manufacturers offer great engineering support state side

A consumer display will always deliver an excellent price point. In some cases, they are half the price of the same diagonal industrial display; but consumer displays can (and typically will) pose the following design challenges:

• Product Quality & Consistency – consumer TFTs tend to be lower quality displays; the factories sort their yields into different grades and the “A” grade panels typically become allocated to customers that demand “A” grade (i.e. the Apple’s and the Motorola’s) or those that will pay the price premium (i.e. the industrial market). Lower grade panels tend to have more pixel defects, are susceptible to color shift, etc. This is not a rule of thumb, but something to be looking for should you not design with an industrial panel.
• Unstable Supply – spikes in global demand could cause your panel to suddenly become unavailable…and this happens quite frequently with “monitor-based” displays (i.e. 15.0”, 17.0”, 19.0”, etc.)
• Rapid EOL – unexpected EOL with limited or no advanced notice always results in a fire drill; not only do you need to secure enough product to bridge the design gap, but you also need to design-in the replacement
• Lack of Backward Compatibility – most
• No Frills – consumer displays are designed for “disposable” applications, so there are no design considerations for replaceable backlights, robust op temps, specialty films, etc.

There are some instances where low-cost consumer TFTs make sense: if you can’t get a product to market profitably (and the TFT is often one of the most expensive components), then there’s no point going to market in the first place. However, we urge customers to also consider total cost of ownership with respects to the entire supply chain. There’s certainly piece of mind knowing that you’ve designed with a solid industrial-grade display and that the industrial display itself will probably be in production much longer than your own product. It’s just one less thing to worry about. 

As a final word about consumer TFTs versus industrial TFTs, take a visit to your local Fry’s Electronics. You can now buy a 24.0” monitor for $129.00; however, if you compare the same monitors side by side, the optical performance is inconsistent. In other words, there are visible differences in the same brand monitor. It’s very inconsistent and representative of lower grade modules.   I personally like the idea of only spending $129.00 on a 24.0” monitor for my wife and kids, but I’m not sure that I want it to be the face of my company’s flag ship product.

So what is Avnet doing to help our customers with Industrial-Grade Displays?

Over the years, we have counseled customers not to design with the lower-cost consumer equivalent, especially if their application truly warranted an industrial-grade display. In one particular instance, however, an Avnet customer opted to design with a consumer TFT for their medical monitor because the consumer display was half the cost of the industrial-grade equivalent. Well, that’s a huge difference. It’s difficult to argue that the customer made the wrong decision. From the customer’s perspective, they could experience 50% fallout and still break even — at least from a purchase price variance (PPV) perspective. However, as predicted, the consumer panel was abruptly EOL’ed after about 6 months of production with no more panels available from the factory. The lack of available product caused a fire drill at the customer to secure all available product in the channel (including the broker channel) in parallel with diverting scarce engineering resources from new projects to the imperiled project’s redesign. 

It’s hard to say what price point warrants the risk to design with a consumer display in a truly industrial application — PPV is critical to keeping your company competitive. Unfortunately, many companies have been brought to their knees after going “lines down” as the result of an unexpected EOL. From our experience, our customers typically opt for the industrial-grade TFT after only one bad experience.

Hopefully this provides a good overview of the industrial market and the value of industrial-grade displays. If you’re planning a new design with a TFT, please enlist the help of Avnet’s talented sales team. For quick reference of what’s available, what’s new and what’s possible, we encourage you to browse our Industrial Display Solutions Guide or view products on our www.embeddedmatrix.com web site. However, our online tools are no substitute for our experienced team of Account Managers, Display Business Development managers and Field Applications Engineers, so please give us a call and get us involved in your next design. Avnet boasts industry-leading display suppliers, services and capabilities and we’re here to help.