Touchscreens have been one of the most exemplary and widely used discoveries in the last decade. There were times when we used to tap really hard on our keyboard phones. Only people who have used phones with a keyboard know what a real struggle looks like. Touchscreens are almost everywhere to serve today’s tech-notched, high 4G paced lifestyle.
They’re just in our smartphones but are used extensively in ATMs, supermarkets, LCDs, cars, laptops, EVMs, self-service grocery checkouts, even in airplane seats. And you may have noticed that not these all are the same. The touchscreens have touched not only our lives but have been proven handy. With the arrival of the touch-sensitive screens, you save a tremendous amount of time & the headache aroused from its troublesome alternatives. Did you ever think about the technology that works behind this prodigious invention? If not, worry not. In this article, we have curated everything that you need to know about the touchscreens and their working.
There may be many technologies when it comes to the touchscreen, but they all serve the same utmost goal, that is to send precise electrical signals from specific locations on the screen. You might have noticed that the touchscreen you use at the ATM is quite different than the one you use on your smartphone. If so, you got it right. There are many different touch technologies out there. The major technologies used amply are what we are going to focus in this article.
It is undoubtedly the majorly used technology in the touch-sensitive world. Resistive touchscreens are made of two separate layers. The top or outer layer of this type is made from a slightly transparent and flexible material, such as polyethylene, which is very commonly used to manufacture plastic bottles. The bottom layer is made of something rigid, usually a glass substrate.
Above mentioned two layers are thinly coated with some metal compound like Indium Tin Oxide to make it electrically conductive in nature. In addition to that, these layers are separated by spacers, which are tiny insulating dots that don’t conduct electricity. They help in keeping both the layers apart so as to avoid any false touch signals. When the screen is on and you tap on the screen with your finger, the top layer connects with the bottom one which changes the voltage and causes the electric current to interrupt. That interruption is noticed by the device and it then locates the precise location of the point of contact of your fingers with the screen. The software registers the coordinates of the location that you’ve touched and thus acts accordingly.
The best advantage of using the resistive touchscreens is this that you can command these screens with bare fingers as well as with the gloves, as they respond to the pressure applied. Along with the pros come cons. The major downside of using these touchscreens is that they can’t understand multiple-touches, zoom-ins or swipe commands.
The resistive touchscreens are quite affordable and durable. They generally used in the credit card readers in stores, ATMs, et cetera.
Considering the complex issues and other drawbacks in the resistive touchscreens, it is safe not to use it in the smartphones. This is where the capacitive touchscreens come in. This term is derived from the widely used electronic component, capacitor.
The basic design of the capacitive touchscreen consists of a sheet of glass which contains a grid of hair-thin lines of a conductive metal, usually made out of Indium Tin Oxide. The grid lines act as an insulator and are situated on the opposite sides of the glass sheet. The sensing lines detect the electric current.
At the intersection of these horizontal and vertical grid lines, produces electrostatic field, which is detected as neutral by the processor in your smartphone or computer devices. All of this changes when the screen comes in contact with your fingers. It is well-known that human skin has a natural capacitance. As soon as your fingers get in touch with the screen, this contact descends the charge at the intersection of the grids where the capacitor is said to be located. This point of contact disrupts the electromagnetic field and redistributes itself accordingly. These changes are detected by the microprocessor and it figures out the pattern you’re making. The software, in turn, generates the action that you’re seeking. It could be a tap, zoom-in or a swipe.
The grids are extremely thin and thus gaining the advantage over the resistive types. The capacitive touchscreens detect the slightest of changes and thus letting you process even the multiple touches at a time.
Like resistive touchscreens, these ones also seem to tag along with a few glitches with it. The downside with using the capacitive touchscreens is this that you can’t use these devices while having your gloves on, as the clothing material is not conductive in nature. Unless you’re wearing gloves with special fingertips made with metal fibers inside. Similarly, if your screen has water drops or sweats on the screen, it won’t be able to operate.
SAW (SURFACE ACOUSTIC WAVE)
The basic principle behind this technology is the piezoelectric effect induced between the transducers and the receivers. The touch screen absorbs these waves and generates the appropriate function at the touched points detected on the screen surface. This type has advantages above other touchscreens. SAW screens are easy to use, durable and give excellent screen visibility/clarity as compared to others.
SAW has even better scratch resistance than the capacitance ones. They will have high touch sensitivity, and hence you can use them while wearing the gloves or soft-tip stylus.
Other touch screens use an additional layer of screen over the basic one, but the Infrared touch screens don’t. Instead of that, these touch screens use infrared transmitters and receivers to generate an invisible grid of light beams across the screen. When an object interrupts these invisible infrared waves, sensors are able to sense these disruptions and this leads to the creation of touch at those points.
The bright side of this technology is that this produces the stupendous image quality of all touch screens. These touch screens are hermetic to the surface scratches. The only downside to this technology is this that it may cause an illusive or accidental touch as the infrared beams are actually above the glass surface.