A tablet PC is a notebook- or slate-shaped mobile computer. Its touch screen or digitizing tablet technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse. The computer is linked to a network using a wireless or wired link.
The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal notebooks are impractical or unwieldy, or do not provide the needed functionality.
Technology
The tablet PC is a culmination of advances in shrinking notebook hardware and improvements in integrated digitizers as methods of input. A digitizer is typically integrated with the screen, and correlates physical touch or digital pen interaction on the screen with the virtual information portrayed on it. A tablet's digitizer is an absolute pointing device rather than a relative pointing device like a mouse or touchpad. A target can be virtually interacted with directly at the point it appears on the screen.
A Tablet PC in its original form also has little if any persistent memory - instead it can be passed between users that can tick off or sign on a document that is displayed.
Inputting data
A user can enter text using handwriting recognition, an on-screen (virtual) keyboard, speech recognition, or standard keyboard. Shorthand-like entry methods, which enable pen-driven input at speeds comparable to touch-typing, and are unique to the Tablet PC, include AlphaTap, Inscribe, Shark (a.k.a. ShapeWriter) and MessagEase.
Tablet PCs using Windows XP Tablet PC Edition may utilize the Ink object as a means of data input and storage. This is a data type created as part of the Windows XP Tablet PC Edition API that allows one to manipulate and process handwritten data, including recognition results and, in some cases, the pressure information for each part of the stroke. Properties of Ink can be changed in much the same way as properties of other objects, and the data can be saved to allow future reference. Many applications referencing the Ink object also allow handwritten notes to be filtered and searched through, based on the recognition results stored when Ink is saved.
A popular use of the tablet PC form factor is to enable computerized manipulation, organization, and reading of large amounts of printed information. In particular, casual readers may download electronic versions of their favorite books to read on their tablet PCs, or students may scan in the pages of textbooks and just bring their tablet PCs to class in lieu of bulky textbooks.
Handwriting recognition
Modern day processors and advances in recognition algorithms make the conversion from handwriting to text far more practical now than it was in early attempts of tablet PCs.
Current handwriting recognition technology employed by tablet PCs focuses more on generic times recognition, rather than letter recognition. Each block of handwriting is compared to a dictionary of words. The word with the closest spelling to its primary guess of the written word is chosen, often with a list of alternatives presented to the user. On words in the dictionary, this method is more accurate than letter recognition. However, this becomes a problem for words not in the computer's dictionary, such as email and web addresses, new slang terms, and proper names. Handwriting recognition software often presents a letter recognizer option to better enable precise input.
Handwriting recognition in Windows
The integrated handwriting recognition in Windows XP Tablet PC Edition 2005 can recognize print, cursive, or mixed writing. Accuracy can be increased by configuring the recognizer to expect left-handed writing or right-handed writing. Recognition in a variety of languages is available with the install of a recognizer pack. The handwriting engine cannot be trained in Windows XP, forcing the user to retrain their handwriting to be better recognized by the system.
The integrated handwriting recognition in Windows Vista is, however, trainable in a variety of ways. Vista offers the option for users to correct specific errors in recognition, provide samples for a set of common characters, or to provide a large set of handwriting data by providing handwriting samples for 50 distinct sentences directly on the computer. There is also the option to use personalized handwriting recognition to watch what words the user emails, or what words they must correct most often, and automatically add those words to the dictionary for improved recognition in the future.
A Typical Tablet PC Screenshot, showing a docked TIP from Tablet PC Edition 2005
Enlarge
A Typical Tablet PC Screenshot, showing a docked TIP from Tablet PC Edition 2005
Tablet PC Input Panel
The original Tablet PC Input Panel (TIP) included a handwriting panel, an on-screen keyboard, and a write anywhere function which allowed the user to literally write anywhere on the screen, after which the recognized data would then be sent to the currently focused input box.
The enhanced TIP introduced in the Service Pack 2 update (Windows XP Tablet PC Edition 2005) includes improved handwriting recognition, the option to correct a recognition error before it is sent to an application, and integrates the option to manually add a word to the computer's dictionary to improve its recognition in the future. The TIP can also add inline correction functionality to applications that support Advanced Text Input Services. This works by the TIP temporarily storing the recognition results from data that it inputs into the application. This version of the TIP removed the write anywhere function in favor of a floating interface. In applications which used certain supported text controls, an icon would appear when the pen was in proximity to the screen. Tapping or hovering over this icon would open the floating TIP, which would expand horizontally and vertically as needed when the user wrote to the edge of the window. For applications which could not pop up the floating TIP, the docked state was still supported, in which the TIP would stick to the top or bottom of the screen, moving all other windows out of the way (expanding downward if docked at the top).
Types of digitizers
Active digitizer
An active digitizer, used in most tablet PCs, can track the position of the pen when it is in proximity to the digitizer. This feature allows the user to "hover" over items on the screen. This can provide helpful functionality such as the ability to view tooltips and auto-hidden items, and to navigate through menus without accidentally activating an item.
Active digitizers can be installed behind the screen, allowing for maximum visibility, although most manufacturers install protectors over the screen to decrease the risk of damage to the LCD.
By using an active digitizer, the user's hand may rest on the screen without affecting the image or mouse pointer; only movement of the stylus affects the mouse pointer.
The most widely used digitizer, a Wacom digitizer projects electromagnetic signals that are reflected by the tablet's pen. The computer then calculates the position of the stylus based on the point in the electromagnetic field the stylus interacts with. Electronic switches inside the pen can change properties of the reflection. For example, a pressure-sensitive switch located behind the tip of the pen is a capacitive change switch, and side switches change the frequency. These features allow the computer to calculate how hard the user is pressing down on the screen and whether a switch is pressed.[1]
Tablets relying on electromagnetic resonation suffer from "jitter", specifically around the edges of the screen. Because the metal at the edges of the screen—as well as in other parts of the computer—changes the properties of the signal that is being reflected back, the tablet digitizer cannot maintain a totally accurate sense of the pen's position. This can make some tasks difficult, e.g. slowly drawing straight lines, aiming at interface elements at the edges, or writing small characters.
UC Logic and Finepoint make other digitizers used in a few tablet PCs. Models incorporating these digitizers suffer from the lack of support in many graphics applications.
Averatec's C3500 line uses UC Logic digitizers. Compaq's TC1000 and Gateway's Convertible Notebook series use Finepoint digitizers.
Finepoint's digitizer technology incorporates a battery-powered pen which actively transmits RF signals to be received by the tablet sensor. This results in lower power usage of the tablet PC itself, but greater size and weight of the pen because of the battery. The main advantage is that the accuracy problems related to interference from metal at the edge of the screen is not an issue.
Early revisions of Finepoint's digitizer, used in Compaq's TC1000, specifically suffered from the use of obscure, non-rechargeable AAAA batteries to power the pen, and did not support pressure sensitivity.
Modern Gateway Convertible Notebooks (CX200/210, CX2600/2700, etc.) use Finepoint MP-800 digitizers. The batteries inside these pens are recharged by an inductance coil while the pen is stored in its compartment. Concerns over the reliability of the pen are the main problem with these models.[2]
Passive digitizer
A passive digitizer, used in a touchscreen based tablet PC, only knows where the position of the finger is when the user presses down on it. This causes the pointer on the screen to jump to the location of the press and instantly "click". Passive digitizers are either capacitive or resistive. They offer lower accuracy and a higher rate of error—e.g. when the user's hand rests on the screen surface—which makes them less common in tablet PCs.
Hybrid digitizer
Windows Vista adds formal support for hybrid digitizers including the ability of applications to distinguish between pen and touch input, as well as ability to turn touch input on or off. [3]
More recently, tablet PCs have been equipped with hybrid digitizers that respond to both active pen and passive touch input. This allows the user to utilize simple finger based navigation, as well as the precision of pen input. An example of a tablet PC equipped with a hybrid digitizer is the Lenovo X60 Tablet with MultiTouch.
Also, TabletKiosk's i440D is a Slate PC with a hybrid, hot-switchable display (although current Vista drivers only allow the active digitizer at this time...XP Tablet 2005 supports full hybrid function)
Stroking pen
The stroking pen is a combination of a regular biro and a digitizer. While writing on a piece of paper that roughly fits onto the graphics tablet (or tablet PC) an exact digital copy is produced (as long as the paper stays in position). The advantages of this device are: a more natural writing experience, longer battery life of the tablet PC (because the display brightness can be turned down without limiting the visibility) and a spare (exact) paper copy for moments when it is needed (e.g., exams or loss of data on the tablet). The last point may also be seen as a disadvantage, because most people use a tablet to avoid using paper in the first place.
The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal notebooks are impractical or unwieldy, or do not provide the needed functionality.
Technology
The tablet PC is a culmination of advances in shrinking notebook hardware and improvements in integrated digitizers as methods of input. A digitizer is typically integrated with the screen, and correlates physical touch or digital pen interaction on the screen with the virtual information portrayed on it. A tablet's digitizer is an absolute pointing device rather than a relative pointing device like a mouse or touchpad. A target can be virtually interacted with directly at the point it appears on the screen.
A Tablet PC in its original form also has little if any persistent memory - instead it can be passed between users that can tick off or sign on a document that is displayed.
Inputting data
A user can enter text using handwriting recognition, an on-screen (virtual) keyboard, speech recognition, or standard keyboard. Shorthand-like entry methods, which enable pen-driven input at speeds comparable to touch-typing, and are unique to the Tablet PC, include AlphaTap, Inscribe, Shark (a.k.a. ShapeWriter) and MessagEase.
Tablet PCs using Windows XP Tablet PC Edition may utilize the Ink object as a means of data input and storage. This is a data type created as part of the Windows XP Tablet PC Edition API that allows one to manipulate and process handwritten data, including recognition results and, in some cases, the pressure information for each part of the stroke. Properties of Ink can be changed in much the same way as properties of other objects, and the data can be saved to allow future reference. Many applications referencing the Ink object also allow handwritten notes to be filtered and searched through, based on the recognition results stored when Ink is saved.
A popular use of the tablet PC form factor is to enable computerized manipulation, organization, and reading of large amounts of printed information. In particular, casual readers may download electronic versions of their favorite books to read on their tablet PCs, or students may scan in the pages of textbooks and just bring their tablet PCs to class in lieu of bulky textbooks.
Handwriting recognition
Modern day processors and advances in recognition algorithms make the conversion from handwriting to text far more practical now than it was in early attempts of tablet PCs.
Current handwriting recognition technology employed by tablet PCs focuses more on generic times recognition, rather than letter recognition. Each block of handwriting is compared to a dictionary of words. The word with the closest spelling to its primary guess of the written word is chosen, often with a list of alternatives presented to the user. On words in the dictionary, this method is more accurate than letter recognition. However, this becomes a problem for words not in the computer's dictionary, such as email and web addresses, new slang terms, and proper names. Handwriting recognition software often presents a letter recognizer option to better enable precise input.
Handwriting recognition in Windows
The integrated handwriting recognition in Windows XP Tablet PC Edition 2005 can recognize print, cursive, or mixed writing. Accuracy can be increased by configuring the recognizer to expect left-handed writing or right-handed writing. Recognition in a variety of languages is available with the install of a recognizer pack. The handwriting engine cannot be trained in Windows XP, forcing the user to retrain their handwriting to be better recognized by the system.
The integrated handwriting recognition in Windows Vista is, however, trainable in a variety of ways. Vista offers the option for users to correct specific errors in recognition, provide samples for a set of common characters, or to provide a large set of handwriting data by providing handwriting samples for 50 distinct sentences directly on the computer. There is also the option to use personalized handwriting recognition to watch what words the user emails, or what words they must correct most often, and automatically add those words to the dictionary for improved recognition in the future.
A Typical Tablet PC Screenshot, showing a docked TIP from Tablet PC Edition 2005
Enlarge
A Typical Tablet PC Screenshot, showing a docked TIP from Tablet PC Edition 2005
Tablet PC Input Panel
The original Tablet PC Input Panel (TIP) included a handwriting panel, an on-screen keyboard, and a write anywhere function which allowed the user to literally write anywhere on the screen, after which the recognized data would then be sent to the currently focused input box.
The enhanced TIP introduced in the Service Pack 2 update (Windows XP Tablet PC Edition 2005) includes improved handwriting recognition, the option to correct a recognition error before it is sent to an application, and integrates the option to manually add a word to the computer's dictionary to improve its recognition in the future. The TIP can also add inline correction functionality to applications that support Advanced Text Input Services. This works by the TIP temporarily storing the recognition results from data that it inputs into the application. This version of the TIP removed the write anywhere function in favor of a floating interface. In applications which used certain supported text controls, an icon would appear when the pen was in proximity to the screen. Tapping or hovering over this icon would open the floating TIP, which would expand horizontally and vertically as needed when the user wrote to the edge of the window. For applications which could not pop up the floating TIP, the docked state was still supported, in which the TIP would stick to the top or bottom of the screen, moving all other windows out of the way (expanding downward if docked at the top).
Types of digitizers
Active digitizer
An active digitizer, used in most tablet PCs, can track the position of the pen when it is in proximity to the digitizer. This feature allows the user to "hover" over items on the screen. This can provide helpful functionality such as the ability to view tooltips and auto-hidden items, and to navigate through menus without accidentally activating an item.
Active digitizers can be installed behind the screen, allowing for maximum visibility, although most manufacturers install protectors over the screen to decrease the risk of damage to the LCD.
By using an active digitizer, the user's hand may rest on the screen without affecting the image or mouse pointer; only movement of the stylus affects the mouse pointer.
The most widely used digitizer, a Wacom digitizer projects electromagnetic signals that are reflected by the tablet's pen. The computer then calculates the position of the stylus based on the point in the electromagnetic field the stylus interacts with. Electronic switches inside the pen can change properties of the reflection. For example, a pressure-sensitive switch located behind the tip of the pen is a capacitive change switch, and side switches change the frequency. These features allow the computer to calculate how hard the user is pressing down on the screen and whether a switch is pressed.[1]
Tablets relying on electromagnetic resonation suffer from "jitter", specifically around the edges of the screen. Because the metal at the edges of the screen—as well as in other parts of the computer—changes the properties of the signal that is being reflected back, the tablet digitizer cannot maintain a totally accurate sense of the pen's position. This can make some tasks difficult, e.g. slowly drawing straight lines, aiming at interface elements at the edges, or writing small characters.
UC Logic and Finepoint make other digitizers used in a few tablet PCs. Models incorporating these digitizers suffer from the lack of support in many graphics applications.
Averatec's C3500 line uses UC Logic digitizers. Compaq's TC1000 and Gateway's Convertible Notebook series use Finepoint digitizers.
Finepoint's digitizer technology incorporates a battery-powered pen which actively transmits RF signals to be received by the tablet sensor. This results in lower power usage of the tablet PC itself, but greater size and weight of the pen because of the battery. The main advantage is that the accuracy problems related to interference from metal at the edge of the screen is not an issue.
Early revisions of Finepoint's digitizer, used in Compaq's TC1000, specifically suffered from the use of obscure, non-rechargeable AAAA batteries to power the pen, and did not support pressure sensitivity.
Modern Gateway Convertible Notebooks (CX200/210, CX2600/2700, etc.) use Finepoint MP-800 digitizers. The batteries inside these pens are recharged by an inductance coil while the pen is stored in its compartment. Concerns over the reliability of the pen are the main problem with these models.[2]
Passive digitizer
A passive digitizer, used in a touchscreen based tablet PC, only knows where the position of the finger is when the user presses down on it. This causes the pointer on the screen to jump to the location of the press and instantly "click". Passive digitizers are either capacitive or resistive. They offer lower accuracy and a higher rate of error—e.g. when the user's hand rests on the screen surface—which makes them less common in tablet PCs.
Hybrid digitizer
Windows Vista adds formal support for hybrid digitizers including the ability of applications to distinguish between pen and touch input, as well as ability to turn touch input on or off. [3]
More recently, tablet PCs have been equipped with hybrid digitizers that respond to both active pen and passive touch input. This allows the user to utilize simple finger based navigation, as well as the precision of pen input. An example of a tablet PC equipped with a hybrid digitizer is the Lenovo X60 Tablet with MultiTouch.
Also, TabletKiosk's i440D is a Slate PC with a hybrid, hot-switchable display (although current Vista drivers only allow the active digitizer at this time...XP Tablet 2005 supports full hybrid function)
Stroking pen
The stroking pen is a combination of a regular biro and a digitizer. While writing on a piece of paper that roughly fits onto the graphics tablet (or tablet PC) an exact digital copy is produced (as long as the paper stays in position). The advantages of this device are: a more natural writing experience, longer battery life of the tablet PC (because the display brightness can be turned down without limiting the visibility) and a spare (exact) paper copy for moments when it is needed (e.g., exams or loss of data on the tablet). The last point may also be seen as a disadvantage, because most people use a tablet to avoid using paper in the first place.
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