We sat down with one of our display experts to answer a few frequently asked questions about Display Integration.In the second edition of our Ask an Expert blog series, we asked our followers to submit questions about how to integrate displays, touchscreen technology, optical bonding, or other display topics on LinkedIn. We received interesting questions spanning many topics, and sat down with one of our display integration experts, Jim Badders, to answer them all.
What components make up an “Integrated Display”?
Normally, when we say Integrated Display, it incorporates some type of display module like an LCD, OLED, or E-Paper. It could also include a touchscreen, either Resistive or PCAP, or just a cover glass. Integrated displays include some type of adhesive to adhere the cover glass or touchscreen to the display module, such as an air-gap gasket or an optically clear adhesive (LOCA or OCA) bond.
There are other options that could also be part of an integrated display. We've included other components like injection-molded plastic housings, machined metal bezels, EMI/RFI shielding, gasketing, frame bonding, heat spreading, protective films and coatings (such as anti-glare or anti-reflective), driver boards and single board computers, graphic overlays, and membrane and capacitive touch switches, to name more common ones. It really depends on what the requirements are, because there are a lot of options.
What makes automotive displays different from other types of display modules?
Automotive displays are generally considered more rugged and have wider temperature performance ranges. Being part of a vehicle exposes the display to extreme road vibration and environmental conditions like direct sunlight, extreme hot and cold. Automotive displays also need increased brightness for sunlight readability compared to something like a medical display, where it has more consistent lighting.
Display mounting is very important for the automotive industry. Automotive display mounts often have custom bezels that enclose the liquid crystal structure and light guide within the display with different mounting features incorporated into the protective metal frame. There can also be special connectors for automotive attachment, quick module installation, and replacement.
How do you decide on what type of touchscreen to use?
We look at a few factors if the type of touchscreen is not specified. First, we must determine if they need a resistive touchscreen or a project capacitive (PCAP) touchscreen. Once we know that, we can determine the touchscreen interface type. This can be “passive architecture”, where the flex tails coming off the touchscreen don’t have their own controller chips or, what’s more common is “Chip-on-Flex”, where the touchscreen has all the interface and controller firmware and circuitry mounted on the flex tails.
Glass thickness can also play a big part in the determination of the touchscreen, as well as any front surface finishes, since these can influence optical performance and cost. Plain cover glass is less expensive than a chemically strengthened glass that has anti-reflection (AF), anti-glare (AG), or anti-fingerprint (AF) coatings, or any combination.
How do you choose what bonding to use?
The most important consideration is the environment in which the touchscreen will operate along with how it will be used and mounted. Is it a military or aerospace application where it may be subject to harsh impact? If so, Liquid Optically Clear Adhesive (LOCA) or Optically Clear Adhesive (OCA) bonding has a much higher impact resistance and durability than something like air-gap bonding.
Another consideration is sunlight readability. If it is an automotive display, or a display for an agricultural application where it may be under direct sunlight, we would likely go with LOCA bonding or a dry-film optical bond, which provides significantly higher sunlight readability and optical clarity.
We are always happy to look at device requirements and suggest the optimal way to bond, so the best course of action is to talk to our experts about your specific display needs.
How much do Display Integration techniques vary between industries?
It really boils down to how a display will be mounted and used, but there are other factors such as weight restrictions that can change how displays are integrated. For an industrial application, we might injection mold a plastic bezel for the display, which could just be mounted on a piece of equipment. In contrast, for a military or an aerospace application, the display may need to be installed into a much more durable, more complex structured housing or bezel. This could also require several different coatings and treatments to the cover glass.
Shock and vibration also plays a part. If the display is for an automotive application, it might need specific gasketing to help prevent buzz, squeak, and rattle (BSR) for user experience or to ensure that the module does not move around and damage critical components. We always evaluate any project requirements from the customer to determine the best way to integrate their display.
How can I protect my display?
Boyd offers several different ways to protect displays. If the cover glass needs to be protected on the outer edges, we can machine metal bezels or injection mold plastic housings. For preventing moisture and particulate ingress, we have a variety of gasketing and sealing solutions. Segmented frame gaskets waterproof and dustproof display assemblies while maximizing raw material yield, performance, and cost. We’ve sealed the most advanced display assemblies for the world’s leading brands for the last decade with bezel bonds and front frame gaskets for IP rated waterproof, vibration damping, and world class push-out performance.
If we are protecting just the front surface of a display, then there are a few different approaches. There are strong protective materials, such as polyester films with a hard coating, or different chemically strengthened types of cover glass. AF, AG, and AS coatings are also useful, and while they do not necessarily protect the display itself, they do help optimize user experience.
What is the most exciting display application that you have worked on?
The most exciting applications are usually new display programs where a customer comes to us and just says "we need a display and a touchscreen," because we can help define exactly what they need. Boyd offers so many different solutions and we can incorporate different technologies into a display module that it is always exciting to figure that out.
It is also exciting when people learn about everything we can do. We can injection mold the plastic housings, machine metal bezels, create custom gaskets and shields, add thermal technologies, enhance brightness and contrast, and we integrate all these solutions together as a vertically integrated manufacturer. That is the best part: being able to help our customers with a unique, integrated solution that enhances their customers' user experience while optimizing energy demand and cost.
What do you think is the future of Display Integration?
A few years ago, I might have said that the future would be displays coming out with in-cell or on-cell touch where the PCAP touch sensor is built directly into the LCD structure. There is some of that out there, but for most applications, it is still a requirement to have the LCD and touchscreen be separate components.
Nowadays, I see a lot more Organic Light Emitting Diode (OLED) displays and micro-LED displays versus the widely used thin-film-transistor (TFT) LED displays. We are also seeing more desire for applications that have multiple displays mounted behind a single piece of cover glass, or curved glass in the automotive industry. Touchscreen technology is always improving, so PCAP displays are getting sensitive enough to work even if you are wearing your thickest ski or driving gloves. Displays certainly have an exciting future ahead!