Types of Touch Screens

A touch screen is a display that can be manipulated with a finger or other object (such as a stylus). This type of interface is becoming more common in consumer electronics.

The first touchscreen system, introduced in 1983 by Hewlett-Packard with their HP-150 computer, used infrared beams to detect a user’s touch. It had its problems, but was the beginning of what is now a widely accepted touchscreen technology.

Resistive

Resistive touch screen technology is perhaps the most common type of touchscreen and has a variety of uses, including consumer electronics and point-of-sale applications. They are particularly popular in low-cost applications that require rugged environments, indirect sunlight, and simple touch features.

The technology works on the principle of resistance, requiring two flexible layers separated by an air gap. The top layer is usually polyethylene terephthalate (PET) film coated with ITO, while the bottom layer is typically glass or an insulating substrate. When a finger presses onto the touchscreen, it causes the top and bottom PET layers to physically come in contact and sends a signal to the controller.

It has several advantages over projected-capacitance touch screens. For starters, it is easier to integrate into an application, and it is more durable. Additionally, resistive touchscreens respond to pressure and can be used with a variety of input objects, including fingers and gloves.

Compared to projected-capacitance technology, they are also more accurate and are 3-4 times more responsive when using a stylus. This makes them ideal for signature capture and any interface that requires a fine-tip touch, like button activation.

However, resistive touchscreens are susceptible to a few drawbacks. They can be hard to see in direct sunlight, and they may be less sensitive to inadvertent touches. They are also less tolerant of scratches and wear, which can result in a need for frequent calibration.

They are also susceptible to aging, which can cause them to become discolored and start to fail over time. In addition, they are more expensive than projected-capacitance technologies.

One of the more important things to consider when choosing between resistive and capacitive is the function of your application. Resistive touchscreens are more accurate and can be more comfortable to use for business applications. Capacitive touchscreens are able to support more advanced input devices such as passive styluses and gloves, but they lack the accuracy and precision required for handwriting recognition and small control elements.

In terms of price, resistive touchscreens are still Touch screen relatively inexpensive for most uses, but they do have some disadvantages. Their lower optical transmissivity ( 80%) leads to reduced brightness and a certain level of haze, and they can break down at high temperatures, which increases the likelihood of them registering light touches such as water drops on the surface. They can also be more fragile than capacitive screens and require occasional calibration, which can be costly for long-term use.

Capacitive

Capacitive touchscreens are one of the most popular types of touch screens available on modern smartphones and tablet PCs. They’re also used in a wide range of industrial electronics, including kiosk systems and digital signage.

Capacitive touch screen technology uses an insulating outer layer (typically glass) coated with a transparent conductive metal compound. Since the human body is an electrical conductor, touching the surface of a capacitive touchscreen panel results in a disruption of the screen’s electrostatic field, which can be detected and processed by a controller.

The resulting change in capacitance is sent to the control software for processing, allowing the screen to register input from a finger or a specialised input device, such as a stylus. This makes capacitive touchscreens very sensitive and accurate, enabling them to detect light touches.

Projected capacitive touchscreens (PCT) use a grid of tiny, transparent electrodes, which are etched into the protective glass coating in a matrix formation. Everywhere the lines overlap, a capacitor is formed.

In order to function, the electrodes need to maintain a consistent voltage across the entire conductive layer. This is done by etching the conductive material into an X-Y grid pattern on either one or two layers of the display, similar to how pixels are etched into the liquid crystal displays in modern computers and TVs.

If the conductive layer is damaged, the sensor will still measure the change in the electrostatic field, but will not generate signals. This makes projected capacitive touchscreens very robust, which can be a major benefit in business applications where the screen may be exposed to a variety of elements and contaminants.

Mutual capacitance is another form of capacitive touch screen technology, which allows for multiple touches to be registered on a single screen. It operates on a series of parallel conductive grids, a technology that originated in CERN.

Unlike resistive touch technology, which is more common in industrial electronics because it can be used in environments with tougher conditions, mutual capacitance does not require the user to wear gloves. This can make it more useful in consumer electronics, especially when it is cold outside, when users may want to use their hands to control the screen.

Infrared

An infrared touch screen is a type of touchscreen technology that uses infrared light to sense the presence of a finger or object. It is commonly used in interactive whiteboards and in many other applications where a high level of precision is required.

Unlike resistive and capacitive touch technologies, infrared touch screens don’t require patterning on their glass, which makes them more durable and resistant to damage. Infrared technology also enables the use of a broader range of objects, including gloved fingers and wet hands, to write on the screen.

Most infrared touch devices use a matrix of infrared beams that are transmitted through LEDs and photo-detectors with a receiving end. When an opaque object touches the display, it blocks some of these beams and photo-detectors detect this interruption. This information is used by the controller electronics to determine where and how a user touched the display.

Infrared sensors detect a disturbance in the infrared beams, and this information is processed to identify the point of contact and give the device a precise location for the touch event. The process is similar to how the magic eye beams in an intruder alarm work.

Another type of infrared touch technology, Linear Correlating Infrared (LCIR), is a more innovative version of infrared technology that offers 100% sunlight immunity, reliable two-touch functionality and input compatibility with gloves and a 5mm stylus. This advanced technology is ideal for a wide variety of industrial, defense and avionic applications where ultra-reliable touch screen function is a must.

Besides, infrared technology allows for higher contrast and image clarity than other types of touch screen technology. Its superior image clarity and light transmission can provide the most vivid images and crisp text.

Moreover, infrared touch screen overlays come as a simple to assemble kit that can be installed directly on the display or alternatively, on a glass or acrylic panel in front of the display. They are a cost-effective and reliable option to transform any LCD or LED display into a multi-touch screen.

Surface Acoustical Wave

Surface Acoustical Wave (SAW) touch screen technology is one of the most popular types of touchscreens in use today. It differs from other types of touchscreen technology by using ultrasonic sound waves to detect touch commands.

A SAW touch screen is made of a glass panel with two transmitting transducers and corresponding receivers placed along the edges. Each transducer generates a specific type of ultrasonic sound wave that travels across the screen. The sound waves then bounce off a series of reflector arrays along the edge of the screen and are detected by two receivers for each axis.

Unlike other touch screen technologies, SAW technology uses only one layer of glass to create a high resolution and durable touch interface. This makes it easy to produce large size touch screens.

SAW touch screen technology is also resistant to scratching, making it an excellent choice Touch screen for public areas where it will be used by many people at once. It is also a great option for commercial and industrial applications, because it can withstand heavy use.

When a person touches the SAW touch screen, the ultrasonic sound waves are absorbed by a finger or stylus. This change in the ultrasonic waves registers the touch event and sends the information to the controller for further processing.

Another benefit of SAW touch screen technology is that it is highly accurate and sensitive to a range of different touch events. It can be used to detect pressure as well as the direction a finger or stylus is placed on the touch screen.

Unlike other technologies, SAW touch screen technology has no moving parts and therefore does not have the potential for failure. In addition, it can be operated in a variety of environments, including dusty, damp and wet conditions.

SAW touch screen technology is ideal for use in a variety of applications, including education and healthcare. It is also a good choice for businesses and government agencies because it can withstand heavy use and is extremely durable. It can be used to control devices such as digital signage, security systems and industrial machines.