HP TECH TAKES
Exploring today's technology for tomorrow's possibilities
How Do Touch Screens Work on Laptops and Tablets?
December 12, 2018
Tapping into touch screens
Most of us are pretty familiar with touch screens. We use this technology daily with our phones, computers, at the ATM, or at the grocery store checkout. Even restaurants have implemented touch display ordering and payment right at the table. Even though we’re constantly tapping and swiping our screens all day long, few of us can actually answer the question: how do touch screens work?
We’re here to help uncover the mystery behind these interactive screens. Together, we can finally dispel the rumor that touch screens are operated by miniature robot elves completing your pointer finger’s many commands. Let’s discuss the most common touch screen technologies, how you can differentiate them, how they work, and how these technologies have impacted our daily lives.
Capacitive vs resistive touch screens
With the first touch screen debuting in 1965, we’ve seen incredible advancements in touch screen technology and computing technology in general. If we told E.A. Johnson that over 2 billion people currently carry touch screens in their pockets every day, he probably wouldn’t have believed us. But that same technology he developed for the Royal Radar Establishment, helped shape the future of the modern touch screen technology that we use daily .
There are many iterations of touch screen technology including infrared and surface acoustic wave (SAW), but there are two that most of us are familiar with. The most common screens we interact with today are capacitive and resistive touch screens. Let’s get to know how these technologies work, and where you’ll see each.
Capacitive touch screens
Capacitive touch screen technology is the style we interact with most. This is the kind of display we see in our smartphones, laptops, and tablet screens.
Capacitive screens are made up of multiple layers of glass and plastic, coated with a conductor material like indium tin oxide, or copper. This conductive material responds when contacted by another electrical conductor, like your bare finger. When you touch your screen, an electric circuit is completed at the point where your finger makes contact, changing the electrical charge at this location. Your device registers this information as a “touch event.”
Once a touch event has been registered, the screen’s receptors signal this event to the operating system, prompting a response from your device - this is the application’s interface that you experience.
Capacitive touch screens generally have a brighter, clearer appearance and are much more sensitive than resistive touch screens. We tend to see capacitive touch screens in more modern technologies like smartphones and tablets. They give us the ability to experience high-quality imagery that imitates reality.
With social media so integrated into our lives, we’re constantly sharing and experiencing life through our devices. Being able to interact with high-quality applications with ease is made possible with the latest capacitive touch screens.
Resistive touch screens
Resistive touch screens work exactly how their name implies - with resistance to touch. A glass or hard plastic layer is blanketed by a resistive metallic layer that conducts charge. The two are separated by spacers in the screen so that when your finger presses firmly on the plastic protective layer, the two layers make contact - changing the electric charge at that location, which cues the software to respond.
Resistive screens are not as bright as capacitive because of their thick blue and yellow colored layers that make their interface appear darker than capacitive screens. You’ll often see resistive screens used on ATM machines, checkout stands, and POS (point of sale) terminals. They tend to be much more durable and affordable than capacitive screens, thanks to that hard plastic outer layer.
Each screen has strengths and weaknesses that make it a better choice for certain applications. Capacitive screens offer more flexibility in functionality as resistive screens lack the ability to register multiple touch points at the same time.
Think about when you zoom in on your smartphone - you’re using two fingers at different receptors to zoom in on an image. Resistive touch screens get confused when you try to apply multiple points to them, since their technology relies on recognizing pressure at a specific location.
What touch screens detect
What touch displays detect differs depending on if the screen is capacitive or resistive. Resistive screens rely on applied pressure which means that sometimes the tip of a pen or another object can initiate a response from the system. Capacitive touch screens use electrical conductors rather than pressure to recognize a command and respond.
But have you ever wondered why capacitive touch screens seem to only work with skin? While that’s not entirely the case, capacitive screens do depend on a specific amount of electrical charge to get a response from the operating system.
This means that other objects with the same charge as your bare finger could complete the same request when using your phone, tablet, or touch screen laptop. This is why touch screens respond to styluses, special gloves, and the occasional pocket-dial.
Before you slip on a pair of gloves ready to text all of your friends about how awesome your new gloves are though, you may want to make sure you’ve got the right pair. Touch screen gloves use conductive thread in the fingertips to maintain the natural electric charge of your finger. This means that not just any glove will be able to register your touch, so make sure you get the right kind of gloves before braving the winter with your smartphone.
While conductive threads and styluses work with touch displays, other objects like a regular pen will not. The difference is in the electric charge of the object. Pens actually have too much electrical charge for a touch screen to recognize. Your screen depends on the perfect recipe of electric charge to complete your requests. Fascinating, isn’t it?
If touch screens work based on their ability to conduct and receive energy, how do touch screen protectors work?
Capacitive touch screens detect electrical current so they don’t need to experience the pressure of your finger like resistive screens do. If your screen protector uses electrically transparent material, it won’t affect the functionality of your screen because it will still be able to register the change in electric charge.
The good news is that as technology in touch screens has advanced, so have their durability. Screen protectors aren’t as necessary now as they were when consumers were first introduced to touch screen products. Many of us are still scarred by the first time we shattered the glass display on our shiny new device. Contrary to over-protective techies, you don’t need to worry so much about the safety of your screen thanks to developments in materials.
Most devices use scratch-resistant material like Gorilla® Glass to protect your screen if it takes a short tumble - though we do not recommend testing your screen’s limits. It’s a durable glass, not the Incredible Hulk. For those who may be coordination-challenged, screen protectors are still a good option to keep your screen in pristine condition.
Most screen protectors are either made of plastic or tempered glass. Plastic protectors help to protect from scratching but don’t do much for impact. If you’re one of those coordination-challenged individuals we mentioned earlier, you may want to consider leveling up to a tempered glass protector, and maybe even a sturdy case to go along with it.
Depending on the thickness of the plastic, you may feel a difference in the sensitivity of your touch screen. Tempered glass adds a thick layer to your screen as well, but the feel is closer to your device’s original screen.
Touch screens for laptops and tablets
Interactive screens enhance the user’s experience by adding in tactile functionality and allowing the user to have more control over their device. With smartphones becoming so integrated into our lives, we’ve become accustomed to accessing anything we need right at our fingertips. This popular technology has permeated our lives with the introduction of touch screen laptops and tablets.
Convertible and detachable laptops with added touch screen technology came onto the tech market shortly after tablets were introduced. Users loved how easily they could navigate their handheld computers and browse the Internet while watching TV, refer to recipes while cooking, and show off family photos on a larger screen than their phone.
Touch screen laptops have become popular with the 2-in-1 laptop style that allows your laptop to be converted to a tablet. Moving windows, adjusting designs, playing games, and scrolling on a laptop has never been easier. You can also bring a dull presentation to life by allowing participants to interact directly with the application via touch screen.
Laptop touch screens - an extension of tablet technology
Both laptops and tablets utilize the same capacitive touch technology. While laptops provide the convenience of a keyboard and trackpad when you need them, tablets offer their own kind of convenience for people on-the-go. When comparing laptop and tablet touch screen products, you’ll often hear about the image display technology.
Modern laptops and tablets typically use LED or LCD displays for the clearest image display. These technologies work with the touch screen layers to display the images you see on your screen. They don’t have a direct impact on how your display works - just what you’re seeing on your screen.
Most devices you’re familiar with using have an LED-backlit display that partners with the LCD (liquid crystal display) to create the bright, colorful display you see when you use your smartphone, tablet, or laptop.
Related article: Top 3 HP 2-in-1 Laptops
About the Author: Sophie Sirois is a contributing writer for HP® Tech Takes. Sophie is a San Diego-based content creation specialist covering the latest in tech and digital news.