What Is Touch Screen Technology?
Touch screen is a display that allows users to interact with a computer by touching the screen. This eliminates the need for a separate monitor to show what is happening, keyboard to type in commands and mouse to point at the screen to tell the computer where to go.
You have probably seen these screens in mall kiosks, smartphones, and tablet computers. But how do they work? Today’s Wonder of the Day explores this question.
Graphical User Interface (GUI)
A GUI (pronounced /ju:ai/) is an interface that allows users to navigate and control a computer or other electronic device through the use of icons and other visual representations on the screen. These visuals allow for easy recognition and classification of data, as well as simple navigation and call to action. This is a major improvement over the CLI (Command Line Interface), which requires users to type in commands using a keyboard.
GUIs are common on many consumer electronics such as mobile phones, tablets and laptop computers, but they are also used in industrial environments to operate robots, machines and other equipment. Some touch screens on HMIs run a commercial operating system, such as Windows Touch screen Embedded Compact, but others are designed for specific applications and work with real-time operating systems, such as RTOS (real time operating system).
In both cases, touch screens provide a clearer and more user-friendly way to interact with and control machines. Unlike the traditional keyboard and mouse, which require the user to physically position themselves near the device to activate the functions, the touchscreen eliminates the need for physical positioning by simply requiring a touch on the display. This enables users to interact with devices in any environment, including those where gloves are required. This can lead to more efficient interaction with the machine and improved productivity.
Resistive Touch Screen
Resistive touch screens utilize electrodes that create a uniform voltage across their entire conductive surface. When you touch the screen, your conductive finger initiates current flow between the two layers, which in turn changes the voltage of one or more sensors positioned underneath. The sensors send a precise voltage reading to the touchscreen controller. This is used to identify the area touched. There are different types of resistive touchscreens that vary in terms of durability and sensitivity.
In 4-wire analog resistive touch screens, the top and bottom layers have a set of electrodes (busbars) positioned perpendicular to each other. When the layer is touched, these electrodes create a voltage divider that allows the system to detect the coordinates of the point of contact.
With this information, the touchscreen controller can determine what action to take. For example, if the screen is pressed on a corner, it will be sent a command to rotate that specific corner of the display.
A drawback of resistive touch screens is that the film substrate commonly used as a top layer can reduce the device’s optical clarity and add a haze. A transparent glass overlay with indium tin oxide deposited on it can improve the screen’s visual quality. However, it will increase the cost of the touchscreen. Nevertheless, the simplicity and durability of resistive touch screens make them a popular option for industrial applications.
Surface Wave Touch Screen
Touch screen technology is so popular that it’s almost a necessity for modern point of sale systems (POS). The touchscreen sensor has to do the trick without switches, membranes or bits of plastic that would block the view of the display beneath. It does so by using a combination of different technologies, including capacitive, resistive and surface acoustic wave.
Surface acoustic wave touch screens work the same way that your hand affects the electromagnetic fields created by radio waves from an old-style radio. As you move your hand up close, the electromagnetic field changes and the radio registers the change. This system is more robust than other types of touchscreens and is often used in high traffic public information kiosks, amusement parks and bank ATMs.
In this type of system, the touchscreen sensor is made of glass Touch screen and has transmitting and receiving piezoelectric transducers on one side and acoustic wave reflectors on the other. When you place your finger on the screen, the touch sensor detects the interruption of the acoustic wave and sends a signal to the controller that indicates where the touch point is located.
The controller compares the touch sensor’s acoustic wave signals with the reference average waveform it had acquired when the touchscreen was in an untouched state to determine where the touch point is located. It then uses this location data to select a command that is sent electronically to the computer or to another device. The controller also knows when a finger leaves the screen and can keep track of multiple touch points simultaneously, if needed.
Infrared Touch Screen
The IR touch screen utilizes an array of LED light emitters and photo detector pairs that are hidden along the edges of the panel, forming an invisible grid on the device’s display. When a finger or other object touches the screen, it disrupts this pattern of LED light and provides the device with input on the X and Y positioning of the touch point.
The pixel-level sensing method allows for the use of a bare finger, gloved hand, or even stylus. Unlike capacitive touchscreens, IR touchscreens do not transfer a charge to the fingers and can work with wet or dirty fingers. Its sensors are also resistant to electrostatic interference, making them more durable than other technologies.
Like other touch screen technology, the IR touch sensor detects variations in pressure. It does this by connecting a glass panel to a film screen separated by a small gap. When the user’s finger closes the gap, it creates an electrical current that is detected by the sensor.
The sensor then sends this information to the screen, allowing the user to perform different actions such as single-tap, double-tap, pinch, or swipe. The IR touch screen is a more economical option than other touch screen technologies, and it can be used on larger screens without losing accuracy. Its only drawbacks are its susceptibility to dust and scratches.