It’s Hot Y’all: A Texan’s Guide to Thermal Management for Touch Screen Displays
We lost count of how many days it was over 100 degrees here in Austin, Texas this July. We can tell you that Accuweather lists the “Actual Temp” of this past Saturday as 107 degrees. Yep, that’s hot. We’re often tasked with providing touch display solutions for places even hotter than a sunny Texas July. Grab a tall glass of sweet iced tea, and check out the various methods we have to manufacture touch screen displays that can navigate a desert combat zone.
- Cooling Fans
- It’s almost too obvious to list, but it can’t be left out. There’s a myriad of cooling fan options for both consumer and industrial applications. Costs vary greatly, mostly depending on the materials used. Higher end cooling fans can be aluminum or copper with optimized heat pipes, integrated heat sinks, and high quality ball bearing assemblies. On the lower end of the cost spectrum, you can find plastic fans of any shape and size imaginable just to get some air moving through your assembly.
- When designing a complete touch display that will require a fan, you must consider the additional power required, mounting options, and the additional space required before you finalize your housing design.
- Heat Sinks
- Heat sinks, or heat exchangers, transfer heat generated by an electronic or mechanical device into the atmosphere (or liquid cooling system) by maximizing the surface area. The fluid transfers the heat away from the device, allowing it to cool to the desired temperature. Metals with high thermal conductivity are used. Aluminum alloys are the most common heat sink material. Aluminum costs less, weighs less, and gets the job done for most applications. For environments where higher levels of thermal conductivity are a requirement for operation, copper provides the best heat dissipation. Some heat sinks use a combination of aluminum fins with a copper base to save on cost and weight where they can.
- Much like the cooling fan market, there are endless options available. Heat sinks can be combined with other thermal management materials such as heat exchange gaskets and cooling fans.
- Housing Material and Design
- Typical touch display housing materials are steel and/or aluminum. Steel costs less and is more durable than aluminum, making it an attractive option for most industrial applications. Aluminum costs more than steel, but is lighter weight, and a good conductor of heat, allowing for better dissipation in high heat applications where you might incorporate a heat sink and fan combination. Aluminum is the primary choice for field/mobile applications, automotive, medical, and aerospace applications.
- There are more exotic (and expensive) materials such as magnesium, titanium, and a variety of hybrid alloys in an emerging market. These are typically found in niche applications more so the industrial space and come with increased costs.
- Heat Exchange/Dissipation Gaskets
- Gaskets offer a wide variety of increasingly efficient solutions for thermal management. Heat interface pads can efficient transfer thermal energy from an LCD to a heat sink. Heat dissipation gaskets can cover flexible printed circuits to protect sensitive electronic components. Hybrid metal gaskets can transfer heat from a touch display to a housing or heat sink. Since gaskets are highly conformable, they can easily eliminate surface irregularities.
- Gaskets can be used to mount displays, touch screens, optical filters, and complete assemblies. Lightweight and corrosion resistant, they can be laser cut and formed for an precise fit.
- Hot mirrors
- Hot mirrors are multilayer dielectric coated substrates (glass/plastic/film) that separate infrared (IR) from the visible part of the spectrum. This protects displays and optical components from solar heat and radiation. LCD components are very susceptible to high heat and solar energy. The “blackout” effect can happen quickly resulting in image degradation and in some cases permanent damage to sensitive components. This can be a critical failure in outdoor applications such as public use terminals, mobile computing devices, industrial controls, and military field applications.
- Hot mirrors offer high optical transmittance combined with high IR blocking, making it ideal for everything from surgical lasers to fish finders. They can be combined with touch screens, EMI filters, and LCD heaters to survive the most demanding environments.
- Extended Temperature Displays
- Designing the right touch display starts with choosing the right LCD. LCDs of every size have a wide variety of features, and every manufacturer has their strengths and weaknesses. For industrial applications such as agricultural equipment or military field computing, heat and direct sunlight must be taken into consideration. Standard LCD operating temperatures are 0-50 degrees Celsius (0-122F). That’s fine for the TV on your wall or the monitor on your desk, but not for walking around in the desert or in a hot factory. Once the display goes beyond that range, you start to get the “black out” effect and lose the image. In some cases, the damage can be permanent. Extended temperature displays typically have an operating temperature of 0-85 degrees Celsius (185F), greatly reducing the risk of “black out” for most industrial environments.
- For our OFM Series Open Frame Monitors we exclusively selected extended temperature LCDs. This allows us to offer sunlight readability without the cost and time of changing the entire assembly.
As you can see, when it comes to keeping things cool, we have more than a few tools in the box. From half-inch optical filters to mobile computers on the battle field, we design and manufacture products that beat the heat. Our extensive experience with various industrial markets that share similar environmental concerns, yet have unique application requirements and design cycles makes us a versatile partner for efficient solutions to thermal management in touch screen displays.