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.

Types of Touch Screen Technology

Touch screens are found in all kinds of devices from ATM machines and cash registers to diagnostic tools in automobile repair shops. They are also used in many media houses, where they allow reporters to report on the weather or news events without having to move away from the screen.

Capacitive

Capacitive touch screen technology is the standard for most modern devices and has supplanted resistive technology. It offers a number of advantages over other technologies, including better durability and lower power consumption.

A capacitive touchscreen works by detecting the slight change in charge caused by your finger touching the surface of the screen. This change in charge is like the static electricity that makes up our bodies, and it allows the processor to accurately locate where your finger is touching.

To do this, a capacitive touch screen uses a conductive layer of indium tin oxide (ITO) and an insulator layer of glass. When your finger touches this, it creates a capacitor, and the human skin acts as a dielectric, affecting the circuit’s overall capacitance.

The touch sensor is connected to a microcontroller that monitors variations in the circuit’s charge-discharge times, and when the value deviates from the standard, it sends a signal to the main controller indicating that you have touched the screen.

Another major advantage of capacitive touch screens is that they can work in a wide range of environments, ranging from dusty rooms to a moist kitchen. The screen can also survive a small crack in the case without failing to function.

Capacitive touchscreens are also easier to clean than resistive screens because they can be wiped with a damp cloth or a soft, nonabrasive soap and water solution. However, it is important to ensure that the screen and edges are completely dry before you use them again.

In addition, they can be easily repaired with an adhesive layer if needed, so they are a good option for high-end devices.

The touchscreen panels of these devices feature a patterned conductive matrix behind the front glass, which is monitored by the touch controller firmware. When a finger or stylus is pressed onto the screen, a minute change in the capacitive field generated by the matrix occurs, and the touch controller firmware determines the finger position using the grid intersections that correspond to each touch location.

A variety of technologies are used for touchscreens, but most rely on electrode grid patterns on etched conductive layers. These are typically called projected-capacitive (PCT) or mutual capacitive. The grids are positioned across each other, resulting in horizontal and vertical patterns that match the touch positions.

Resistive

The most common type of touch screen technology, resistive touchscreens are used in a wide range of consumer and industrial applications. They are particularly popular in point-of-sale (POS) terminals, as well as digital still cameras and GPS devices.

Resistive touchscreens consist of two conductive layers separated by dielectric spacer dots, typically made of indium tin oxide (ITO). When pressure is applied to the top layer by a finger or other object such as a stylus or pen, these two layers come into contact. This creates a change in resistance (an increase in voltage), which the sensor layer detects and the tablet or mobile phone processor can use to determine the X-Y coordinates of that touch.

With their simple structure and low cost, resistive touch screens are a popular choice for portable applications and industrial settings. They offer a reliable user experience in harsh environments, where liquids or debris might interfere with other types of touch screens. They are also ideal for users wearing gloves, as they can be activated using bare fingers, nails or even a stylus.

Because of their simplicity, resistive touch screens are easy to design Touch screen and manufacture. They are available in 4-, 5-, 6- and 8-wire designs, which vary in sensitivity, durability and noise suppression.

They are sensitive to both a single touch point and multi-touch inputs, which can be beneficial in fast-paced applications. However, their single-touch operation limits them to basic touch actions, such as pinching and zooming.

Additionally, they are susceptible to dents and scratches in certain conditions. The film substrate commonly used as a top surface is less transmissive than glass, which can lead to reduced brightness and haze.

While resistive touchscreen technology remains a popular option for many applications, it’s losing market share to projected capacitive technologies, which are becoming the preferred touch-enabled interface choice across most devices. Projected-capacitance touchscreens don’t suffer from the limitations of their predecessors, and they offer high-end devices more features than resistive screens. Consequently, system designers must balance component integration costs against functional performance to provide the best user experience for their customers.

Surface Acoustic Wave (SAW)

The SAW sensor is a type of sensor that detects events through the interaction of acoustic waves and an electrical signal. This technology is very common in electronic circuit devices, such as filters, oscillators, and transformers.

SAW sensors can be divided into two categories: delay line and resonant type. The delayed line-type SAW sensor has a piezoelectric substrate and an interdigital transducer (IDT), which converts the excitation signal into an acoustic wave. The acoustic wave then propagates along the piezoelectric substrate, and its energy is reflected by the reflective gate.

When an acoustic wave reaches the piezoelectric substrate, the amplitude of the acoustic wave decays exponentially with the depth of the piezoelectric material. The penetration depth of SAW is just a couple of wavelengths, which makes it an ideal candidate for acoustic radio frequency (RF) filtering applications in wireless communication systems.

In addition to RF filters, SAWs and bulk acoustic waves find increasing applications in life sciences and microfluidics for sensing or mixing of tiny amounts of liquids. These thumbnail-sized ‘lab-on-a-chip’ (LOC) devices revolutionize diagnostic quests in medicine.

However, there are some limitations to SAW sensors. Unlike other types of sensors, SAW sensors have limited success in liquid environments. This is because the SAWs propagate through a liquid’s surface, which leads to complex flow line patterns in the fluid.

To overcome this limitation, a new generation of SAW sensors is aimed at measuring chemical reaction processes in liquids. They have high resolution, high accuracy, and low power consumption.

For example, FLOWave is a compact and lightweight in-line flowmeter that uses acoustic-surface technology to measure the flow of liquids. It is CIP/SIP capable, and can conform to the strictest hygiene standards.

Another advantage of this type of sensor is that it can be easily inserted in different liquids. The one-piece stainless steel tube body enables highly accurate measurements and no pressure drops, which is especially useful for CIP/SIP operations.

SAWs are a powerful tool for studying material properties, from linear elastic behavior to fracture. They also are the basis for the development of acoustic cavitation phenomena, which induce micron-sized cavities in fluid bulk by using high-power acoustic waves.

Infrared

Infrared touch screens are one of the most common technologies used in commercial applications. They work by detecting interruptions in an invisible light beam that is created by LED lights embedded into the frame of the display screen. These IR LEDs emit horizontal and vertical invisible IR beams, which form grids across the surface of the overlay, and photodetectors are installed across from them to detect interruptions in the light beams as a touch event happens.

Another benefit of IR technology is that it does not require any conductor such as a finger, apparatus or a stylus to operate the device. This eliminates the need for patterning on the glass, making it stronger and more durable than capacitive devices which are more susceptible to breakage when dropped from a height.

However, IR touch screens are not as accurate as capacitive or resistive devices, and the signal can be interrupted by dirt and dust, or Touch screen by moving objects such as a mouse. These problems can be resolved by using a specialized anti-jamming mode in the display, which works by only transmitting a fixed frequency signal to the sensors on the screen.

Additionally, infrared touch screens can be operated with wet or dirty fingers and gloves. This makes them ideal for industrial and medical applications, which require high reliability and safety.

For example, infrared touch screen technology is used in plant control systems, factory automation, and ATM. It is also a good choice for interactive whiteboards, which are widely used in business meetings and distance learning.

Compared with capacitive and resistive technologies, infrared technology is considered more reliable and less expensive. It can support up to 40-point touch input and can be activated by a bare finger, gloved finger or stylus.

Infrared technology is also more resistant to electrostatic and magnetic noises, and can be used for multi-touch operations. This means that multiple people can use a single device at the same time, and it also improves battery life because there is no need to constantly re-calibrate the screen. Furthermore, infrared touchscreens can be applied to large size panels.