Know Your Touchscreen

Today you can find touchscreens in a lot of devices, mostly mobile devices ( phones, tablets, game consoles ). It's comfortable to use and can have many features that makes navigating, browsing, playing, or whatever much easier. But do did you know that there are different kinds of touchscreens? I'll give you a quick overview on this topic.

Types of touchscreens:

Resistive

Consists of layers. The touching is recorded by top two layers. One layer has voltage applied to it, the other one senses it. If you press on the screen, the layer become connected and the position can be read from the panel which starts to rapidly check between the axes, one at a time.

P: Low cost
P: Liquid resistant
P/N: Can be used with almost any item, have to use pressure
N: Easily damaged by sharp objects
N: Poor contrast

Touch: Single, can be dual/multi

Best usage: Restaurants, hospitals, factories, handheld applications ( phones )

Surface acoustic wave

It is most advanced type of touch screens. Ultrasonic waves pass over the screen panel, and by touching it, some of the waves are absorbed. The registers then see the changes in waves and with the information received, a touching position can be calculated.

P: Good image resolution, clarity
N: Interference from screen contamination ( dirt, dust, water )
N: Screen has to be touched with finger, soft-tip stylus or wearing gloves don't work

Touch: Single, dual, multi

Best usage: Banks, ATMs, public places, anywhere indoors with high usage.

Capacitive

Almost the same as resistive screen, but you can't use the screen with your gloves or with any other electrically insulating item, the screen is glass. In this case, human finger is the capacitance for the screen.

P: 90% of the light is transmitted from the screen
P: Doesn't need heavy pressure
N: Have to use fingers or special stylus

Touch: Single, can be dual/multi

Best usage: Mobile devices

Iphone uses capacative touchscreen

Infrared

X and Y ( both have infrared LED transmittors and receivers ) axes are used for recording the disturbances in the LED photodetectors. The beams make up a grid on the panel and if anything disrupts the beam, we have a recording and can locate the finger/or whatever.

P: All the light is transmitted because there's no overlay
P: Almost any item is good for using the screen
N: Anything can interrupt the beams ( dust, dirt )

Touch: Single, dual, multi

Best usage: ATMs, hospitals, kiosks

Optical imaging

Sensors are placed in the corners of the device and on the other side of the screen the infrared back lights are in the cameras viewfield. When you touch the panel, it creates a shadow and the cameras pick up the signal.

P: Precise - can tell exact location the size of the touching object
P: Clear image, no overlay
P: can be used on very large devices
N: Contamination can interrupt sensors
N: Needs thicker device than other solutions

Touch: Single, dual, multi

Best usage: Anywhere indoors that needs a big screen

Samsung optcal imaging monitor

Dispersive signal technology

It uses mechanical energy ( bending waves ) created by the object toucing the screen. The waves are picked up by sensors and the location is calculated by a certain algorithm.

P: Fast and accurate
P: Good image quality
P: Scalable to big screens
P/N: Needs motion for deteting location, isn't disrupted by other objects
N: Not so much used as others ( few suppliers )
N: Only 1 touching point is recognized

Touch: Single

Best uses: Big screens

Acoustic pulse recognition

Uses sound created by your touch, each position of the screen has an unique sound. The sound is picked up by transducers in the edges of the screen and the location of the touch is found.

P: Good optical clarity
P: Durable ( scratches and dust don't affect it )
P: Good for large devices
P/N: Isn't disrupted by other objects, needs motion to be detected

Touch: Single

Best uses: Kiosks, lobbies, schools, corporations