Customizing Displays - A Primer

When designing a product today, you know that the appearance, human interface, and usability of that product is going to be judged in comparison to the smartphone. Indeed, in some cases, users make the decision to rely on a smartphone for most, if not all, of their human interactions.

Where the product definition calls for the product to have the ability to operate without that reliance, the designer still has to deal with high customer expectations and establish a look and feel that will stand out from the competition. Luckily, there are many ways that displays can be customized, often at a reasonable cost. In this article, I will focus on LCDs, arguably the most common and most affordable way available to customize display technology.

The first decision to make is determining what size and resolution of display you need. The physical display area and the kind of information you are going to display are key. High-resolution video has different constraints than three rows of alphanumeric characters. However, it can be useful to future-proof your interface by using a more capable display than is specified by your requirements document. The key to affordability is to choose a display area and aspect ratio that is available. Consulting with an expert is useful here since there are a considerable number of options, not just the usual 16:9 of TVs and 4:3 of computer monitors. Everything from round displays to elongated “letterbox” displays can be sourced. While a full custom LCD screen can be designed with the pixel pitch and pixel dimensions of your choice, this can drive a much longer delivery of prototypes, as well as higher NRE and unit cost. You should also be aware that there are different LCD technologies that have different fields of view. If your product needs to be just as visible from the sides as it is from the front, then an appropriate technology, such as IPS, needs to be chosen.

Next is choosing the bezel and finish for the display. Referred to as the cover lens, the outer layer of glass serves multiple functions. The size and shape are a crucial part of the industrial design. The outer edges can be covered by a bezel of the glass edge, which can be rounded or shaped to fit directly into, or onto, the housing. The inside of the cover lens is typically printed with a black ink border which masks all but the active display area. This is a great place for a company logo which is then protected from wear and tear by the glass. There are multiple choices for surface finish, anti-glare, anti-microbial, and anti-fingerprint. Finally, you need to decide how tough the cover lens needs to be. Thinner keeps the weight low, crucial in wearable devices, but if you need vandal proofing then thicker is better. There are also various choices in chemical treatment that makes the glass itself more resistant to scratching and breaking.

The next variable to consider is the display’s brightness. If your product is normally used indoors, then the normal brightness of around 400 to 600 NITS should be acceptable. If the system is used outdoors, then a custom backlight could be designed to boost the brightness to around 1000 NITS. The tradeoff here is higher power consumption, so this could be a problem for battery-powered systems.

The last area for customization I want to discuss is touch. The benefit of a well-executed touch interface is that the human interface becomes primarily software-driven. If a new mode of operation is added during a product's life cycle, there is no need to redesign the hardware. Older systems used resistive touch, where a plastic film on the front of the display measured resistance values to determine the position of the finger. These films are susceptible to wear and environmental damage, and we do not recommend them for new designs. Capacitive touch uses a layer of glass just under the cover lens, so it is much more robust and is capable of handling multi-finger touch. Another option is to extend the touch sensor beyond the edge of the display itself so that additional buttons can be set up and delineated by printing onto the cover lens. Be aware that the touch controller should be tuned to operate in your final enclosure for optimum performance.

There are many ways that display technology can be optimized to make your product stand out from the competition. Don't just look for an off-the-shelf display. It's better to get engaged with a team of display experts to explore what can be done and what is affordable.

If you have more questions or need help finding the right display for your product, send us an email to sales@usmicroproducts.com and our display engineers will be happy to assist you!