Apart from the whole functionality of the Electric Vehicle chargers, the display can be the toughest choice, that will influence the whole user experience. It’s worth considering a few topics to make it right and last for many years.

Nowadays there are many companies focused on delivering the best possible electric vehicle charging solutions to the market, but only the best ones will survive. The display is one of the components that can make it stand out from the competition, as this is the part that users interact the most. Here is the list of the parameters that will help you to make the right decisions and avoid failures.

The size of the displays

Everything concerned with the displays goes bigger now. We live in the visual world, and everything that’s around us is colorful and bright. We buy huge TVs and phones, and we are surrounded by enormous public information displays. So, what’s the proper size for the charging station?

For the EV chargers the most popular sizes are 7″, 10.1″ and 15″, but some of the producers are picking even 32.1″ displays that cover almost the whole front of the machine. The size depends on your design, but it’s worth considering which is the most convenient for the user. The station will be used by people in every age, in a different condition, and with different skills, so picking smaller than 7″ display, can make the usage more complicated for some of them.

On the other hand, choosing a display bigger than 15″ makes the whole EV charger appear much modern and effective.

Brightness

This is one of the most important parameters form the user’s point of view. There is nothing more frustrating than not clearly visible content on the display. The choice depends on the location of the application, and the insolation there. In simple words: the higher brightness, the better display performance under the sun.

Consider if the charger is going to be used indoor or outdoor. If it will be mainly mounted in the underground car parks, it’s ok to go for 300-500cd/m2. Outdoor applications require much more than that to handle the direct sunlight. For chargers that are going to stand outside, the brightness should be at least in a range of 1000cd/m2, but even 2000cd/m2 could be recommended.

Brightness and minimization of the reflections are the keys to the proper readability of the display. Keep in mind, that if you will go for air bonding of the touch and the display, you may lose up to 50% of the contrast. More details can be found in “Optical or air bonding?” paragraph.

Viewing angles

The viewing angle is the maximum angle at which the user can see the image with the acceptable quality. Mainly, we distinguish four types of displays, which are TN, VA, MVA, and IPS.

TN type is the most cost-efficient technology. The angles are mostly narrower than in the case of the other types, but low prices and short matrix reaction time compensates the smaller viewing cone. In order to extend the viewing angles, O-film can be added to the display. When buying a TN-type display you should always pay attention to the viewing direction expressed in hour angle. It describes the direction from which the user should look at the display.

VA and MVA types are characterized by rather short reaction time, wide angles, and high contrast. It classifies them somewhere very close to the IPS display type.

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IPS matrix technology has not only most of VA’s advantages but also very good color reproduction and highest viewing angles in both axes. Riverdi definitely recommends IPS for indoor and outdoor applications, as allows us to see the content from every point of view.

Buttons, touch, or maybe touchless?

Both, buttons and touch solutions are very popular, but the whole world is currently switching to capacitive touch technology. It’s completely understandable, as we are “in touch” with our smartphones almost all the time, and we used to it.

At Riverdi, touch is our biggest passion and we are real experts with designing and tuning them. We are focused on all three touch technologies: capacitive, resistive, and touchless. Our industrial capacitive touch controllers can handle even up to 15mm glass thickness by standard, and we can make them work with water or gloves.

As we live in the time of the pandemic, and it seems we will need to get used to it, displays based on touchless solutions are becoming more and more popular. Such an option can be based on external sensors, or by picking a very sophisticated touch controller that will recognize the movement form the distance. It requires an advanced tuning, but can be delivered by Riverdi, and will definitely make your #EVcharger stand out from the competition.

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By making here the right choice you can avoid a lot of time spent on servicing. Most of the chargers located in public places are exposed to damage or vandalism.

From our experience for sizes 7″- 10.1″ it’s recommended to use thermally tempered or chemically strengthen glass at least 4-6 mm thick. Also, it can be worth considering a Gorilla Glass, which is a chemically strengthen type of glass, that can resist the pressure of 50kg, and its hardness is 9H (when the diamond is 10H). However, still, the most popular and cost-efficient is the thermally tempered glass with the thickness from 4mm up to 10mm and we use such technology in most of our projects.

Some of the applications are using PMMA, which in my opinion, is not the best choice for the EV charges, as it can be quite easily scratched. A scratched display is definitely not something that a user would like to experience while charging a car. Replacing the whole front by the manufacturer can be also very time and money consuming. Tempered glass is way more durable, and Riverdi can deliver in a very competitive price range.

Optical or air bonding?

Air bonding is a method of gluing the touch to the display by using the adhesive tape on the edges, This is the most popular process, as it’s pretty easy and cost-efficient. The main disadvantage is the loss of even 50% of the display contrast because of the air gap between air-bonded parts.

Optical bonding is a process of putting the touch panel to the display by using liquid adhesive glue. The process uses an optical-grade adhesive to glue glass to the top surface of a display. It completely eliminates the air gap between the touch panel and the display. In general, this process improves the optical performance, as well as the durability of the module.

A couple of years ago the choice was pretty obvious, as the air bonding was way less expensive than optical bonding. Now, the price difference is not significant, and it can be in a range of a couple of dollars for 7″ display. I think that’s acceptable for a brightness and color depth improvement.

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The air bonding not only improves the quality when the display is on, but also it makes the display looks way more effective once it’s off.

Here you can see a comparison of our optically bonded 10.1″ IPS display and 7” display with air gap between TFT and touch.

Interface

For the EV chargers we mostly see LVDS as the most popular interface for sizes 7″-15″. LVDS means low-voltage differential signaling, and in simple words LVDS operates at low power and can run at very high speeds using inexpensive twisted-pair copper cables. It is less (than others) susceptible to common-mode noise. LVDS technology is not dependent on a specific power supply, such as +5V. This means there is an easy migration path to lower supply voltages such as +3.3V, +2.5V, or even lower while still maintaining the same signaling levels and performance.

However, if needed, we can also develop a #DisplaySolution based on HDMI (High-Definition Multimedia Interface), MIPI (Mobile Industry Processor Interface), or eDP(Embedded DisplayPort) interface. The advantage of using HDMI is that the cable can handle both audio and video signals, and it’s very popular for laptops, tablets, and large TVs, but the cables are pretty expensive compared to analog ones. Fundamental features of MIPI are high performance, low power consumption, low EMI, but the disadvantage is the fact that is mostly designed for sizes up to 7″. The benefits of using eDP are included advanced power-saving features such as seamless refresh rate switching, small size connectors, maximum power efficiency, and supporting up to 8k resolution graphics. eDP is used widely in notebook computers and all-in-one systems.

Seems like a lot of things to consider, but you don’t need to think about them on your own. At #Riverdi, we can help you to answer all the questions properly, and pick the right options. It’s really worth to take.

If you are currently in the development process of your electric vehicle charging station, or you are considering some upgrades to the existing one, feel free to contact me. We already implemented dozens of display solutions for the charging industry to the market, which makes us real experts in this area.

Additionally, check Switch To Riverdi where we offer samples and tooling charges completely free of charge!