iPhones: The Magic (Multi) Touch

By Eliza Mitchell

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Touchscreens have become a widely familiar aspect of society. Whether it is on our videogame device, smartphone, tablet or even in the car, it is an extensively used technology. Since its first inklings in the late 1960s, the industry for touch screens has gone through the roof, leading us through a variety of different devices like Apple’s touchscreen phone in 1983 and the PDA. The iPhone, though touchscreen, introduced a new compilation of existing technologies that kicked all the styluses and finicky finger manipulating to the curb: the multi-touch system. In order to understand how big of a leap the system is in the field of technology, it is important to understand how a regular touchscreen works first.

Courtesy William Hook/Flickr

Courtesy William Hook/Flickr

The regular touchscreen functions with only one point being recognized at a time. In other words, if you try to put five styluses on a Nintendo DS at once and expect to play Mario Kart, the device is probably going to malfunction, and then send Yoshi into a ditch. There are multiple reasons why this occurs which depend upon the technology that the company employs while developing their touchscreen system. The majority of the basic touchscreens use “sensors and circuitry to monitor changes in a particular state,” according to HowStuffWorks.com. In the general sense: put your finger on the screen and the system recognizes that the screen is no longer in its original form, thus computing the change accordingly.

Another touchscreen technology is built to track changes through the use of electrical current. This is utilized in the iPhone. The way this works is through a layer of material that holds an electrical charge. When there is pressure at a certain point, it changes the charge for that area, translating it into a command in the device. This electrical system is in a capacitive touch screen. There is another electrical type called a resistive touch screen where a tap causes a change in the circuits’ resistance by making a conductive layer and a resistive layer come into contact.

The last two types of touchscreen systems are a little less common, but interesting nonetheless. One of them uses waves. Whether sound waves or light waves, the process is the same: when pressed, your finger causes the waves to either be blocked or reflected. Pure wave action, with the tap of a finger! The least frequently used type of touchscreen is one that uses transducers. Transducers wait for either a change in vibration, or use cameras to “monitor [differences] in light and shadow,” according to HowStuffWorks.com.

So now onto the iPhone’s multi-touch technology: what makes it so special? One of the features is the ability to zoom in and out with two fingers. How does it work? Apple didn’t really introduce anything new. They just mixed and matched a lot of the technology that already existed. What makes the use of such a common process so innovative is the division of the screen into a coordinate system, giving each point its own ability to signal the iPhone’s processor, as opposed to simply giving the same ability along an axis like other products utilizing the capacitive touchscreen. The iPhone takes this process and uses one of two methods: a self-capacitance touchscreen or a mutual capacitance touchscreen. The former uses “sensing circuits and electrodes” to determine the placement of the finger, according to HowStuffWorks.com. The mutual capacitance screen involves an entire grid of lines to monitor the touch. While the sensing lines find the finger, the driving lines carry the current.

With all the wonderful technology used in this device, it is difficult to think of a drawback. One exists: the iPhone can only operate via skin contact. There can be no gloves or styluses used because they do not conduct electricity like we do. The plus? No butt dialing. The negative? Frosty fingers when calling in the cold. Although, who can complain about the ice and snow, when you can claim that you have the magic touch?

Eliza Mitchell can be reached at [email protected]