PC Peripherals How touch screen works?

P

Prophet

Disciple
Can anyone tell me how touch screen works and also how touch gestures work like mobile phones - sliding, rotating, etc.???
 
in touchscreen their are two types of technologies, capacitative and resistive.. most modern phones like iphone, or any other sony or nokia models now use the capacitative now. it being much more sensitive and responsive and feather touch... in the resistive, now outdated, there is a thin film above the glass screen with a very very small gap and this type of touchscreen only works efficiently with a stylus.. like in the older phones. everyone used to have a stylus.. so basically, when you press the screen with the stylus, the thin film above the screen comes in contact with the screen which basically completes a circuit at that particular point, and thats how you get the functionality. hence, the extra pressure that is required on older touchscreens..

am not really sure about the capacitative, but these i guess simply have sensor technology built in, and hence these are much light to operate and very very responsive and more expensive too..

and about the gestures, they are mainly software based. the touchpad is capable of sensing multiple touchs already, but if the software or the driver or firmware of the touchpad does not have programming of what to do when multiple touch is sensed, you simple wont have the function. basically, the device doesnt know what to do when multiple fingers are used even though it senses both of them. if the driver has the features of multiple touch gestures, then the multiple touch translates into a function according to whatever is specified in the driver. most modern laptops even have customizable settings for multi touch and gesture operations which can be turned on or off or small customizations can be made depending on the flexibility of the driver of the hardware.. in laptops for eg. .you can have settings customized as to what to do when you slide two fingers simultaneously, scroll or zoom.. the touchpads which have the scrolling function basically have drivers that tell them that if they sense a touch along the sides within 1 cm, it has to be translated into a scroll function. if the finger is tapped in the left half, then it is left click, on right half, right click. if the finger is moved clockwise in a circular motion, that can be used to increase or decrease volumes of the computer.. similarly the pinching function found on the iphones and ipod touch.. it is programmed such that if you put two fingers and start pinching, ie. bring them towards each other, it zooms out of the screen and vice versa.. hope this clears it..

so bottomline, all gestures, software based.. if there is a particular gesture that is programmed in the driver of the touchpad, it will translate that gesture into a unique function.
 
There are many types of Capacitive touchscreen viz. the simple one, surface capacitive, Projected, Mutual, Self Capacitance
The most widely used is the Mutual Capacitive, it allows multi touch operation

In mutual capacitance there is a capacitor at every intersection of each row and column of the screen. Voltage is applied to the rows and columns.
Bringing a finger or conductive stylus close to the surface of the screen surface changes the local electrostatic field which reduces the mutual capacitance.
Since the capacitance changes at every INDIVIDUAL cell of the screen, the capacitance change can be measured to accurately determine the touch location by measuring the voltages in the axes.

The gestures are deduced from the continuous touch operation by the underlying driver-which is the software part interpreting the voltage readings
 
flash23 said:
There are many types of Capacitive touchscreen viz. the simple one, surface capacitive, Projected, Mutual, Self Capacitance

The most widely used is the Mutual Capacitive, it allows multi touch operation

In mutual capacitance there is a capacitor at every intersection of each row and column of the screen. Voltage is applied to the rows and columns.

Bringing a finger or conductive stylus close to the surface of the screen surface changes the local electrostatic field which reduces the mutual capacitance.

Since the capacitance changes at every INDIVIDUAL cell of the screen, the capacitance change can be measured to accurately determine the touch location by measuring the voltages in the axes.

The gestures are deduced from the continuous touch operation by the underlying driver-which is the software part interpreting the voltage readings
Click to expand...

Can this technology be applied to a normal LED monitor to convert it in a touch screen ?
 
^^^ Yes it can be applied. Basically, a complete touchscreen is a normal screen with overlaying sensors.

By proper synchronization of the matter being displayed and the "TOUCH or GESTURE sensed" an effective touchscreen is made.
 
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