Touchscreen technologies. Overview, advantages and disadvantages.
Touchscreens are offered with different types of touch technologies. It is a good idea to know the difference between the technologies, to be able to offer best advice when selling touch solutions to different types of applications.
Lets start by listing the most common touch technologies. And then dig deeper into the pros and cons.
Resistive Touch: This technology uses a layer of resistance material, such as plastic or glass, that changes resistance when pressure is applied to it. The touch is detected when the resistance at the point of pressure changes.
Capacitive Touch: This technology uses a layer of conductive material, such as copper, that stores electrical charge. When a finger comes in contact with the screen, it changes the amount of charge stored at that point, which can be detected and used to determine the location of the touch.
Surface Acoustic Wave (SAW) Touch: This technology uses ultrasonic waves that travel over the surface of the screen. When a touch is applied, it creates a disturbance in the waves, which can be used to determine the location of the touch.
Infrared Touch: This technology uses infrared light beams that are transmitted across the screen. When a touch is applied, it interrupts the light beams, which can be used to determine the location of the touch.
Optical Imaging Touch: This technology uses cameras to capture images of the screen and detect touches by analyzing changes in the images.
Projected Capacitive Touch: This technology is similar to capacitive touch, but it uses a matrix of electrodes to create a grid of capacitive sensing points. This allows for a more accurate and sensitive touch detection.
Now that we have covered the different technologies, lets have a closer look at how it works, and when to use it - and when not to use it!
RESISTIVE TOUCH
Here we see the finger pushing down the front layer, and creating a small voltage between the 2 layers
Resistive touch is a type of touch technology that uses a layer of resistance material, such as plastic or glass, to detect touch input. The technology works by using two transparent, electrically conductive layers separated by a small gap. The top layer is a flexible material, such as plastic, and the bottom layer is typically made of glass. A small voltage is applied across the two layers, creating an electric field between them.
When a user touches the screen, the pressure of the touch causes the top layer to come into contact with the bottom layer, completing an electrical circuit and changing the resistance at that point. This change in resistance is detected by the touch controller and used to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of resistive touch include:
Cost-effectiveness: Resistive touch is relatively inexpensive compared to other touch technologies, making it a popular choice for budget-friendly devices.
Versatility: Resistive touch can be used with a stylus or a finger, making it a good option for devices that require input from both types of input.
Durability: The flexible top layer of a resistive touch screen is highly durable and resistant to scratches, making it a good choice for devices that will be used in rough environments.
Disadvantages of resistive touch include:
Accuracy: The accuracy of resistive touch can be limited by the size of the gap between the two conductive layers and the pressure required to complete the circuit.
Responsiveness: The pressure required to activate a resistive touch screen can make it less responsive than other touch technologies.
Image quality: The layer of resistance material can degrade the image quality of the screen, leading to reduced brightness and color accuracy.
Flexibility: The flexible top layer of a resistive touch screen can become deformed over time, leading to reduced accuracy and sensitivity.
Overall, resistive touch is a good choice for devices that require basic touch input at a low cost, but it may not be the best choice for devices that require high accuracy or responsiveness.
CAPACITIVE TOUCH
The touch is already happening just before the finger is touching the glass
Capacitive touch technology is a type of touch technology that uses a layer of conductive material, such as copper, to detect touch input. The technology works by using a layer of conductive material, such as a sheet of copper, that is coated with a transparent, insulating material. A small voltage is applied to the conductive layer, creating an electric field around it.
When a user touches the screen with a conductive object, such as a finger, the electrical charge at that point changes. This change in charge is detected by the touch controller and used to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of capacitive touch include:
Accuracy: Capacitive touch is highly accurate, making it a good choice for devices that require precise touch input.
Responsiveness: Capacitive touch is highly responsive, making it a good choice for devices that require fast and responsive touch input.
Durability: The conductive layer of a capacitive touch screen is highly durable and resistant to scratches, making it a good choice for devices that will be used in rough environments.
Image quality: The transparent insulating layer of a capacitive touch screen does not degrade image quality, allowing for high-quality display.
Disadvantages of capacitive touch include:
Cost: Capacitive touch is more expensive than other touch technologies, making it a less popular choice for budget-friendly devices.
Conductivity: Capacitive touch requires a conductive object, such as a finger, to activate the touch, making it less versatile than other touch technologies.
Sensitivity: Capacitive touch can be less sensitive than other touch technologies, making it less suitable for devices that require fine control or precision.
Overall, capacitive touch is a good choice for devices that require highly accurate and responsive touch input, but it may not be the best choice for devices that require basic touch input or are budget-friendly.
SURFACE ACOUSTIC WAVE
The touch point is determined by analyzing where the soundwaves break
SAW (Surface Acoustic Wave) touch technology is a type of touch technology that uses high-frequency sound waves to detect touch input. The technology works by using a series of transducers and reflectors along the edges of the touch screen. The transducers send out high-frequency sound waves that travel across the surface of the screen and are reflected back by the reflectors.
When a user touches the screen, the touch distorts the sound waves, causing a change in the wave patterns that are reflected back to the transducers. The touch controller detects this change and uses it to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of SAW touch include:
Accuracy: SAW touch is highly accurate, making it a good choice for devices that require precise touch input.
Durability: The high-frequency sound waves used in SAW touch are not affected by scratches or other damage to the touch screen, making it a good choice for devices that will be used in rough environments.
Versatility: SAW touch can be used with a stylus or a finger, making it a good option for devices that require input from both types of input.
Disadvantages of SAW touch include:
Cost: SAW touch is more expensive than other touch technologies, making it a less popular choice for budget-friendly devices.
Complexity: SAW touch is a complex technology that requires a large number of components, making it more difficult to manufacture and maintain than other touch technologies.
Responsiveness: The high-frequency sound waves used in SAW touch can make the touch less responsive than other touch technologies.
Overall, SAW touch is a good choice for devices that require precise touch input and durability, but it may not be the best choice for devices that require fast and responsive touch input or are budget-friendly
INFRARED TOUCH
The finger is disrupting the infrared light.
Infrared touch technology is a type of touch technology that uses infrared light beams to detect touch input. The technology works by placing a series of infrared light-emitting diodes (LEDs) and photodetectors around the edges of the touch screen. The LEDs emit infrared light beams that cross over the surface of the screen and are detected by the photodetectors.
When a user touches the screen, the touch blocks some of the infrared light beams, causing a change in the amount of light detected by the photodetectors. The touch controller detects this change and uses it to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of infrared touch include:
Durability: Infrared touch does not require any physical contact with the screen, making it more durable and resistant to scratches and other types of damage than other touch technologies.
Versatility: Infrared touch can be used with a stylus or a finger, making it a good option for devices that require input from both types of input.
Cost: Infrared touch is less expensive than other touch technologies, making it a good choice for budget-friendly devices.
Disadvantages of infrared touch include:
Accuracy: Infrared touch can be less accurate than other touch technologies, making it less suitable for devices that require precise touch input.
Sensitivity: Infrared touch can be less sensitive than other touch technologies, making it less suitable for devices that require fine control or precision.
Light interference: Infrared touch can be affected by ambient light, making it less suitable for devices that will be used in bright or outdoor environments.
Overall, infrared touch is a good choice for devices that require durability and a low cost, but it may not be the best choice for devices that require precise touch input or will be used in bright or outdoor environments.
OPTICAL IMAGING TOUCH
Cameras watching where the finger is blocking the light.
Optical imaging touch technology is a type of touch technology that uses cameras to detect touch input. The technology works by placing one or more cameras around the edges of the touch screen and shining a pattern of light on the screen. The cameras capture images of the light pattern on the screen and use them to determine the location of the touch.
When a user touches the screen, the touch distorts the light pattern on the screen, causing a change in the image captured by the cameras. The touch controller detects this change and uses it to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of optical imaging touch include:
Accuracy: Optical imaging touch is highly accurate, making it a good choice for devices that require precise touch input.
Versatility: Optical imaging touch can be used with a stylus or a finger, making it a good option for devices that require input from both types of input.
Durability: Optical imaging touch does not require any physical contact with the screen, making it more durable and resistant to scratches and other types of damage than other touch technologies.
Disadvantages of optical imaging touch include:
Cost: Optical imaging touch is more expensive than other touch technologies, making it a less popular choice for budget-friendly devices.
Complexity: Optical imaging touch is a complex technology that requires multiple cameras and a sophisticated touch controller, making it more difficult to manufacture and maintain than other touch technologies.
Light interference: Optical imaging touch can be affected by ambient light, making it less suitable for devices that will be used in bright or outdoor environments.
Overall, optical imaging touch is a good choice for devices that require precise touch input and durability, but it may not be the best choice for devices that are budget-friendly or will be used in bright or outdoor environments.
PROJECTED CAPACITIVE TOUCH
An electronic field is created on the surface, and interacts with the users finger.
Projected Capacitive Touch (PCAP) technology is a type of touch technology that uses an electric field to detect touch input. The technology works by creating an electric field over the surface of the touch screen using a grid of electrodes. When a user touches the screen, the touch disrupts the electric field and changes the capacitance of the electrodes, causing a change in the amount of charge stored in the electric field.
The touch controller detects this change in capacitance and uses it to determine the location of the touch. The touch controller then sends this information to the device's operating system, which uses it to control the device's user interface.
Advantages of PCAP include:
Accuracy: PCAP is highly accurate, making it a good choice for devices that require precise touch input.
Multi-touch: PCAP supports multi-touch input, making it a good choice for devices that require multiple touch inputs at the same time.
Durability: PCAP is durable and resistant to scratches and other types of damage, making it a good choice for devices that will be used frequently.
Sensitivity: PCAP is highly sensitive, making it a good choice for devices that require fine control or precision.
Disadvantages of PCAP include:
Cost: PCAP is more expensive than other touch technologies, making it a less popular choice for budget-friendly devices.
Complexity: PCAP is a complex technology that requires a sophisticated touch controller, making it more difficult to manufacture and maintain than other touch technologies.
Light interference: PCAP can be affected by ambient light, making it less suitable for devices that will be used in bright or outdoor environments.
Overall, PCAP is a good choice for devices that require precise touch input, multi-touch support, durability, and sensitivity, but it may not be the best choice for budget-friendly devices or for devices that will be used in bright or outdoor environments.
