Resistive touchscreen
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Resistive touchscreens are composed of two flexible sheets coated with a resistive material and separated by an air gap or microdots. When contact is made to the surface of the touchscreen, the two sheets are pressed together, registering the precise location of the touch. Because the touchscreen senses input from contact with nearly any object (finger, stylus/pen, palm) resistive touchscreens are a type of "passive" technology.
For example, during operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the uniform voltage gradient is applied to the second sheet to ascertain the Y coordinate. This operation occurs instantaneously, registering the exact touch location as contact is made.
Resistive touchscreens typically have high resolution (4096 x 4096 DPI or higher), providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device.
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[edit] Advantages
Resistive touchscreen technology works well with fingertip input.
Costs are relatively low when compared with active touchscreen technologies.
Resistive touchscreen technology can also support multi-touch input. [1]
[edit] Disadvantages
Due to the nature of passive touchscreen design, when "inking" (taking handwritten notes with a stylus), one cannot press one's large hand down on the screen while writing [2] [3]. This is the tradeoff between having a dedicated implement (stylus) versus the ability to use one's fingers as a stylus. A few modern tablets recognize both fingers and a stylus, and avoid this problem by deactivating recognition for non-stylus input when the stylus makes contact.
For people who must grip the active portion of the screen or must set their entire hand down on the screen, alternative touchscreen technologies are available, such as active touchscreen in which only the stylus creates input and touches from the hand are rejected. However, there are now newer touchscreen technologies which allow you to use multi-touch without the aforementioned vectoring issues. [4]
[edit] See also
[edit] References
- FreshPatents.com — Full patent description of passive touch system and method of detecting user input
- ^ "Multi-touch comes to resistive touchscreens", http://www.umpcportal.com/2009/02/multi-touch-comes-to-resistive-touchscreens, retrieved 2009-06-23 15:25 CDT
- ^ "Netbooks: Swivel Touchscreen Does Not Equal Tablet PC", http://jkontherun.com/2009/06/22/netbooks-swivel-touch-screen-does-not-equal-tablet-pc/, retrieved 2009-06-23 15:16 CDT
- ^ "Asus Eee PC T91 for taking notes: “don’t expect it”", http://www.asustablet.com/asus-eee-pc-t91-handwriting-taking-notes-powerpoint/, retrieved 2009-06-23 15:20 CDT
- ^ "Multi-touch comes to resistive touchscreens", http://www.umpcportal.com/2009/02/multi-touch-comes-to-resistive-touchscreens, retrieved 2009-06-23 15:25 CDT
