Today we all make use of touch screens and they have been completely mimicked in our day to day, since we use them continuously. But, how does touch screen technology work, what types are there and what is their history and evolution? We explain it to you in this article.
Displays are output devices at the source, adding to them the ability to be tactile and interact with them has made them the foundation on which all the pocket computers and tablets we continually use are based.
Touch screens, the LCD industry revolution
The first electronic agendas did not make use of touch screens but had full keyboards that occupied all or almost all the available surface, which forced the screens to be extremely small when used and made their users have to navigate to through less complicated with buttons.
It was the appearance of Apple‘s Newton that first brought us the use of touchscreens, which was followed years later by the Palm Pilot. The birth of this type of device is due to the need to be able to make notes by making sketches, but especially due to the use of certain languages with non-Western calligraphy such as Chinese, Japanese, Arabic and many others that required a form of writing. be able to enter freehand written text.
The pencil of light: when the monitor turns into canvas
Long before the appearance of LCD touch screens and even before the popularization of the mouse, optical sensor pens were used, which were used with CRT monitors and their operation was based on capturing the passage of the electron beam through the screen.
All graphics cards of the time used to have an outlet to connect the stylus and be able to draw on the screen. Although it is not an LCD touch screen technology, it was the forerunner in terms of the way of working of what were the LCD touch screens that we use today.
In the case of the PC, the success of the mouse as an input interface to navigate the user interface ended up replacing the use of the stylus, which over time fell into the greatest of oblivion, never to be used again and passed to be a relic of the past.
Types of touch screens and their functions
Touchscreens have become commonplace on a daily basis and are used in many devices today. There are different types and therefore different functions, below we describe how each type works.
Resistive touchscreens: the first pocket computers and their stylus
In 1992 Apple introduced the first touchscreen pocket computer in history: the Apple Newton. It was an evolution of electronic agendas, but with a new type of interface, which used a resistive panel to capture the keystrokes through the finger or with a stylus on the screen.
Resistive screens are made up of two layers filled with electrodes, which are placed face to face on the same side both. In the middle of both layers there is an inert gas. The way of working of these is very simple, when we press on the screen making pressure then the two panels get closer and the pressure of the inert gas increases. The consequence? The electrodes that are organized in mesh capture the pulsation and with this the system can know in which exact area of the screen we are pulsating.
Resistive screens were widely used in various products until 2007, so they had a long life in the market. Not only the previously mentioned Apple Newton, but also other PDAs such as the mythical Palm Pilot and PocketPCs with Microsoft operating system made use of resistive screens. We also have the case of consoles such as the Nintendo DS, not to mention how many ATMs of cashiers and banks also used this type of panel.
Capacitive touch screens: the most used today
In January 2007, Apple presented its first iPhone and one of the things that stood out the most was the adoption of a screen with a capacitive panel. A touch panel technology very different from the resistive panel that had been used at that time and that did not require the use of a stylus to work.
How do they work? Capacitive screens do not work by putting pressure on the surface, but is based on the fact that the human body is a natural conductor of electricity. So when building a capacitive screen, use is made of a transparent and conductive material integrated into a glass or plastic. When it comes to cataloging the types of capacitive screens we can do it in two different types:
- Capacitive surface: In this case, an electrode is placed, one for each corner of the screen, which maintain a fixed level of voltage throughout the screen and are connected to each other. The simple fact of touching the screen with your finger in an area changes the direction of the current and with it there is a change in voltage that the sensors underneath themselves end up capturing.
- Projected capacitive screen: It is the most sensitive type of touch screen, since a simple contact on it is interpreted as an input. So it is not common for it to be used on smartphones and tablets. It uses a vertical electrode line with a constant current level even when we are not using the screen, which are accompanied by another horizontal electrode line that is activated when we place our finger on the screen.
Haptic-type touchscreens
A haptic screen is a screen that gives us the feeling of having touched a surface and therefore gives us a sensory response. They are the newest type of touch screens where the objective is none other than to replace the sensation of touch that we have when pressing certain surfaces, especially when we press the buttons of the control knob of a console or the keys of a keyboard.
There are three ways in which you can give the sensation of touching on the screens, which are as follows:
- Models : They are the rarest of all, they are based on the creation of a scale model of the object with which we have to interact, the fact of touching the model means touching that part of the interface that it represents in the system.
- Wearable: instead of making the screen emit a response, what we do is put on special accessories such as thimbles and gloves that provide the sensory response.
- Integrated in the screens: the haptic response technology is in the screen itself, which gives a response, in general through manipulating the electrical charge around where we have the finger.
If you want to know more about haptic screens we recommend that you look at the article in HardZone entitled: ” Touch screen technologies, what are they and how do they work? ”
The future of displays and their devices
We are not going to see many changes in terms of touch screen technology in the coming years, especially due to the fact that in the applications in which these types of screens are used there is no request for an advance beyond what already invented. What we are going to see is an improvement at the level of interaction, especially in capacitive screens that, although they allow you to be able to press in both places at the same time, do not have the same resolution as resistive screens, which makes them worse in the face of uses like drawing.
Of course, where we are going to see integrated capacitive screens is going to be in many everyday devices that today use buttons to function. For example we are going to find that at a certain moment the buttons of appliances, elevators and even the controls in the car.
The handicap to overcome? The current capacitive screens are almost all of the capacitive surface type, which is based on the placement of electrodes in the four frames. This conflicts with recently developed technologies that break with frame-type screens and allow them to take any shape, not just rectangular or square, allowing their integration to new types of devices.