Stylus & Finger operated Touch Screen Interfaces

The touch screen interface is operated with either a Stylus or a Finger.It has a transparent touch sensitive panel just in front of the screen. The “touch” is recognized by a change in electrical voltage. Infra red is also used in certain devices to detect the “touch”

The interaction is very direct and easy to learn, unlike a mouse where the User is forced to learn to co-ordinate his hand movements with that of the cursor movement on the interface. Touch screen interfaces are best suited for information retrieval purposes.They also save costs (hardware, hardware upgrade costs etc,.Touch screens can be used in scenarios when “space” becomes a constraint. (No need to cables, keyboards etc.) They are used in Pocket PCS, Handhelds, PDAs, Smart & Mobile Phones, Interactive Kiosks, Car GPS systems, LCD Plasma Panels etc.,Handwriting recognition is also possible. "Tree structure" is not recommended to display complex hierarchies.
Touch screen interfaces have their own limitations in terms of button size & touch precision. This is a lot more pronounced Finger based interaction than Stylus based interaction.
• The input speeds are much slower than two/multi-finger keyboard operation.
• The absence of hand rest/support system leads to fatigue and hence this interaction is not suitable for large volumes of data entry and high usage frequency.
• Keyboard entry is itself a “learnt” habit. Therefore, QWERTY keyboards are not recommended for touch screens which have the above mentioned limitations.
• Its best to use a keypad which had alphabets arranged alphabetically in 3 rows. (9x8x9 )
• These virtual numeric keypads need to resemble the “telephone” keypad. It’s a lot easier for the user. The numeral 1 is placed on the top left corner on a “telephone” keypad.
• A stylus works more like a mouse. (Single Click, Double Click, Click & Drag etc.,)
• Conventional Windows GUI elements will work well for Stylus operations. (Scroll bars, Double clicks, Click and Drag etc.,) See the interaction in Nokia 7710. However for Finger operations, its better to use “Push Buttons” for “Page Up” & Page Down” functions instead of scroll bars. Dragging is not recommended for Finger operations.
The touch screens can be either Wall mounted, Floor Standing, Handheld, Docked, or Framed.

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