Multi-touch technology resides in almost every electronic device which hosts a screen that we interact with every day. From smartphones to in-car infotainment systems, cash machines and even some exercise equipment. As a technology, it has come an incredibly long way since it was first developed back in the 1970s and continues to advance as our capability expands.
Despite almost daily use, multi-touch technology goes largely unnoticed by the majority of us. We have become so reliant on the technology ‘just working’ but have no idea how it works.
To avoid diving down too much of a tech geek rabbit hole, I’m going to keep this as an overview and be a little less granular than I could. If you want to know more you can always drop a comment and let me know.
That being said, before we look at why or how it works, we should probably cover what it is.
SO, WHAT IS MULTI-TOUCH TECHNOLOGY?
In computing, “multi-touch” is a technology that enables a surface (a trackpad or touchscreen) to recognise the presence of more than one point of contact with the surface at the same time. Or in layman’s terms, it is the technology that enables you to create all manner of patterns to unlock your phone, use pinch and zoom when looking at maps on a tablet, swipe right (or left) on prospective matches and generally anything else that requires more than one touch-point on a screen to be activated at a time.
WHERE DID IT COME FROM?
Although we are used to having this remarkable technology in everyday objects, it wasn’t always the case. Originally developed in the 1970s by teams at CERN, MIT and Bell Laboratories it was a very expensive and complex feat of engineering that was only used in commercial, big-budget projects (CERN’s particle accelerators are an example of this). Back in what is arguably the dawn of the computing era you needed a lot of screen space to encompass the touch screen aspect, whilst only achieving limited functionality as touch screen displays were only able to register a single touch at any one time.
For a couple of decades, small improvements were made making multi-touch technology more affordable and useable without a great number of pre-requisites being met first. But it wasn’t until 2004 when a French start-up created a 10-point multi-touch device used for controlling music that multi-touch technology became truly commercially viable. Within the next two years, Apple launched the original iPhone, finally bringing multi-touch technology into the hands of the masses. This was quickly followed by other mobile device manufacturers as well as companies from a host of other industries.
HOW DO MULTI-TOUCH SCREENS WORK?
There is a lot that we can go into here, with each of the below categories having multiple variations to suit a whole host of different applications, so in the interest of not turning this into a mini-thesis, we will just cover the basics for now.
Depending on the size and type of the interface you are using, one of four different multi-touch technologies will be in use. These are:
Capacitive – Capacitive multi-touch screens are based on something called ‘capacitive coupling’ which uses electric pulses or conduction to measure whether certain materials have a different conduction or conductivity rate to air. When a finger or a specialised conductive pointing device comes into contact with the screen, a change in electrical pulses is picked up and the change is registered in the sensors housed within the screen. This is then picked up and fed back to the software running the device and a visual response is relayed back to that particular touchpoint. Capacitive touchscreens are typically the most responsive and can pick up smaller movements, however, they are more expensive if you want a higher degree of accuracy. This form of multi-touch technology was made popular by Apple in 2007 when they first released the iPhone before it spread to almost all other mobile and tablet devices.
Resistive – Resistive multi-touch screens are made by placing two flexible sheets together which are coated with a resistive material and separated by either an air gap or microdots. These two sheets have both horizontal and vertical lines within them which, when pressed together, register their connection and the connection point creating a response where the two sheets are touching. Due to how they operate they are very accurate and can support high-resolution displays. Resistive touchscreens work well with almost any stylus, bare finger or even gloved hands, making them very useful when operating in harsh conditions. The downside of resistive multi-touch screens is that they do not register light touches very well, so require reasonable force to be applied before they pick up any interactions. Also, the common resistive multi-touch technology relies on software to detect multiple touchpoints which is flaky at best. We have found technology to both increase the usability of multi-touch resistive touchscreens providing 10-point touch to be in line with capacitive screens AND reduce the pressure required for touch.
Optical – Optical multi-touch screens utilise image sensor technology. They work by using sensors or cameras to monitor the reflection of light that occurs when a finger or pointing device touches the screen. A response is then generated depending on the type of reflection measured. Given the complexities involved, this type of multi-touch screen is often used in larger screens or devices for outdoor applications. Optical multi-touch has typically been the more expensive option however, as technologies improve it is becoming more cost-effective to implement.
Wave – Wave or Dispersive Signal Technology multi-touch screens use a series of sensors to measure the Piezoelectricity, an electric charge that accumulates in certain materials when they are put under stress or strain in the glass as it is depressed. This information is then used to locate the exact location of the touch and an appropriate reaction is then created. This style of screen technology is incredibly accurate and can be used with any object, including gloved fingers and stylus’ to register a touch. The main downside, however, is that once an initial touch has been registered, a stationary object or finger will not be registered again until it moves as it will no longer be exerting a piezoelectric response on the screen.
At GRiD, we use a combination of both resistive and multi-touch resistive screens across our product range. Displays are selected for each product depending on the typical application, the environment that it will be deployed, as well as customer requirements and preferences.
Interested in learning more about how we utilise multi-touch technology within our equipment or want to try out some of our kit to test the suitability for a project you have? Give us a call on +44 (0)1628 810 230 or send an email to firstname.lastname@example.org and one of our team will happily get back to you.