Friday, February 25, 2011

Tablet computer 5

Handwriting recognition

Because tablet personal computers normally use a stylus, they quite often implement handwriting recognition, while other tablet computers with finger driven screens do not. Finger driven screens however are potentially better suited for inputting "variable width stroke based" characters, like Chinese/Japanese/Korean writing, due to their built in capability of "pressure sensing". However at the moment not much of this potential is already used, and as a result even on tablet computers Chinese users often use a (virtual) keyboard for input.

Touchscreen hardware
Touchscreens are usually one of two forms;

    * Resistive: Resistive touchscreens are passive and can respond to any kind of pressure on the screen. They allow a high level of precision (which may be needed, when the touch screen tries to emulate a mouse for precision pointing, which in Tablet personal computers is common) but may require calibration to be accurate. Because of the high resolution of detection, a stylus is often used for resistive screens. Although some possibility exist for implementing multi-touch on a resistive touch-screen, the possibilities are quite limited. As modern tablet computers tend to heavily lean on the use of multi-touch, this technology has faded out and has been replaced by:

    * Capacitive: Capacitive touchscreens tend to have better accuracy and responsive than resistive screens. Because they require a conductive material, such as a finger tip, for input, they are not common among (stylus using) Tablet PCs but are more prominent on the smaller scale "tablet computer" devices for ease of use, which generally do not use a stylus, and need multi-touch capabilities.

Other touch technology used in tablets include:

    * Palm recognition. It prevents inadvertent palms or other contacts from disrupting the pen's input.

    * Multi-touch capabilities, which can recognize multiple simultaneous finger touches, allowing for enhanced manipulation of on-screen objects.Since mid-2010, new tablet computers with mobile operating systems forego the Wintel paradigm, have a different interface and have created a new type of computing device.These mobile OS tablet computer devices are normally finger driven and use multi-touch capacitive touch screens, instead of the simple resistive touchscreens of typical stylus driven systems. First of these was the iPad, with others following. In foregoing the x86 precondition (a requisite of Windows compatibility), the new class of tablet computers use a version of an ARM architecture processor heretofore used in portable equipment (e.g., MP3 players and cell phones) now powerful enough (especially with the introduction of the ARM Cortex family)for tasks such as internet browsing, light production work and gaming.

Some professional-grade Tablet PCs use pressure sensitive films that additionally allows pressure sensitivity such as those on graphics tablets.

Concurrently capacitive touch-screens, which use finger tip detection can often detect the size of the touched area, and can make some conclusions to the pressure force used, for a similar result.

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