03-12-2012, 05:22 PM
Touch panels
[attachment=42313]
Electrical touch panel
Constructed with two plates
One is coated with transitive material
2nd one is coated with resistive material
Voltage drop across the resistive plate
Optical touch panel
A line of infrared LEDs
Light detectors are placed along the opposite direction
Why detectors are used ?
The two crossing beams that are interrupted identified the horizontal and vertical coordinates of the screen position selected
With closely spaced LEDs ,it is possible that
Why the light is not visible to a user ?
Acoustical touch panel
High frequency sound waves are generated across a glass plate
What happen by touching the screen ?
How the screen position is calculated ?
By taking a measurement of the time interval b/w transmission of each wave and its reflection to the emitter
[attachment=42313]
Electrical touch panel
Constructed with two plates
One is coated with transitive material
2nd one is coated with resistive material
Voltage drop across the resistive plate
Optical touch panel
A line of infrared LEDs
Light detectors are placed along the opposite direction
Why detectors are used ?
The two crossing beams that are interrupted identified the horizontal and vertical coordinates of the screen position selected
With closely spaced LEDs ,it is possible that
Why the light is not visible to a user ?
Acoustical touch panel
High frequency sound waves are generated across a glass plate
What happen by touching the screen ?
How the screen position is calculated ?
By taking a measurement of the time interval b/w transmission of each wave and its reflection to the emitter