Computer graphics processing and selective visual display system – Display driving control circuitry – Controlling the condition of display elements
Reexamination Certificate
1999-10-18
2001-10-23
Huynh, Ba (Department: 2773)
Computer graphics processing and selective visual display system
Display driving control circuitry
Controlling the condition of display elements
C345S169000, C707S793000, C704S003000, C704S004000, C341S023000
Reexamination Certificate
active
06307549
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to reduced keyboard systems, and more specifically to reduced keyboard systems using disambiguation to resolve ambiguous keystrokes.
BACKGROUND OF THE INVENTION
For many years, portable computers have been getting smaller and smaller. The principal size-limiting component in the effort to produce a smaller portable computer has been the keyboard. If standard typewriter-size keys are used, the portable computer must be at least as large as the keyboard. Miniature keyboards have been used on portable computers, but the miniature keyboard keys have been found to be too small to be easily or quickly manipulated by a user.
Incorporating a full-size keyboard in a portable computer also hinders true portable use of the computer. Most portable computers cannot be operated without placing the computer on a flat work surface to allow the user to type with both hands. A user cannot easily use a portable computer while standing or moving. In the latest generation of small portable computers, called Personal Digital Assistants (PDAs), companies have attempted to address this problem by incorporating handwriting recognition software in the PDA. A user may directly enter text by writing on a touch-sensitive panel or screen. Unfortunately, the accuracy and speed of the handwriting recognition software has to date been less than satisfactory.
It would therefore be advantageous to develop a keyboard for entry of text into a computer that is both small and operable with one hand while the user is holding the computer with the other hand. Prior development work has considered use of a keyboard that has a reduced number of keys. As suggested by the keypad layout of a Touch-Tone telephone, many of the reduced keyboards have used a 3-by-4 array of keys. Each key in the array of keys contains multiple characters. As a user enters a sequence of keys, there is therefore ambiguity in the resulting output since each keystroke may indicate one of several letters. Several approaches have been suggested for resolving the ambiguity of the keystroke sequence.
One suggested approach for unambiguously specifying characters entered on a reduced keyboard requires the user to enter two or more keystrokes to specify each letter. The keystrokes may be entered either simultaneously (chording) or in sequence (two-stroke specification). Neither chording nor two-stroke specification has produced a keyboard having adequate simplicity and efficiency of use. Two-stroke specification is inefficient, and chording is complicated to learn and use.
Other suggested approaches for determining the correct character sequence that corresponds to an ambiguous keystroke sequence are summarized in the article “Probabilistic Character Disambiguation for Reduced Keyboards Using Small Text Samples,” published in the Journal of the International Society for Augmentative and Alternative Communication by John L. Arnott and Muhammad Y. Javad (hereinafter the “Arnott article”). The Arnott article notes that the majority of disambiguation approaches employ known statistics of character sequences in the relevant language to resolve character ambiguity in a given context. That is, existing disambiguating systems statistically analyze ambiguous keystroke groupings as they are being entered by a user to determine the appropriate interpretation of the keystrokes. The Arnott article also notes that several disambiguating systems have attempted to use word level disambiguation to decode text from a reduced keyboard. Word level disambiguation disambiguates entire words by comparing the sequence of received keystrokes with possible matches in a dictionary after the receipt of an unambiguous character signifying the end of the word. The Arnott article discusses many of the disadvantages of word-level disambiguation. For example, word level disambiguation oftentimes fails to decode a word correctly, because of the limitations in identifying unusual words and the inability to decode words that are not contained in the dictionary. Because of the decoding limitations, word level disambiguation does not give error-free decoding of unconstrained English text with an efficiency of one keystroke per character. The Arnott article therefore concentrates on character level disambiguation rather than word level disambiguation, and indicates that character level disambiguation appears to be the most promising disambiguation technique.
Still another suggested approach is disclosed in a textbook entitled
Principles of Computer Speech
, authored by I. H. Witten, and published by Academic Press in 1982 (hereinafter the “Witten approach”). Witten discusses a system for reducing ambiguity from text entered using a telephone touch pad. Witten recognizes that for approximately 92% of the words in a 24,500 word dictionary, no ambiguity will arise when comparing the keystroke sequence with the dictionary. When ambiguities do arise, however, Witten notes that they must be resolved interactively by the system presenting the ambiguity to the user and asking the user to make a selection between the number of ambiguous entries. A user must therefore respond to the system's prediction at the end of each word. Such a response slows the efficiency of the system and increases the number of keystrokes required to enter a given segment of text.
Disambiguating an ambiguous keystroke sequence continues to be a challenging problem. As noted in the publications discussed above, satisfactory solutions that minimize the number of keystrokes required to enter a segment of text have failed to achieve the necessary efficiencies to be acceptable for use in a portable computer. Moreover, the publications have taught away from using word level disambiguation and have focused on character level disambiguating techniques. It would therefore be desirable to develop a disambiguating system that minimizes the ambiguity of entered keystrokes and thereby maximizes the efficiency of text entry.
SUMMARY OF THE INVENTION
The present invention provides a reduced keyboard using word level disambiguation to resolve ambiguities in keystrokes. The keyboard is constructed with full-size keys, preferably twelve keys arrayed in three columns and four rows or three rows and four columns. A plurality of letters and symbols are assigned to at least several of the keys, so that keystrokes by a user are ambiguous. A user enters a keystroke sequence wherein each keystroke corresponds to the entry of one letter of a word. Because individual keystrokes are ambiguous, the keystroke sequence could potentially match more than one word with the same number of letters. The keystroke sequence is processed by comparing the keystroke sequence with stored vocabulary modules to match the sequence with corresponding stored words or other interpretations. Words that match the sequence of keystrokes are simultaneously and automatically presented to the user in a list on a display as each keystroke is received (hereinafter referred to as “the selection list”). The other interpretations of the keystroke sequence are also provided to the user in the selection list. The words and other interpretations are presented in order of decreasing frequency of use, with the most commonly used word presented first.
In accordance with one aspect of the invention, the user presses an unambiguous select key to delimit an entered keystroke sequence. After receiving the select key, the disambiguating system automatically selects the most commonly used word and adds the word to the sentence being constructed if the user continues to enter additional text.
In accordance with another aspect of the invention, the select key that is pressed by the user to delimit the end of a word is also used to select less commonly used words from the selection list presented to the user. If the most commonly used word presented to the user at the top of the selection list is not the desired word, the user presses the select key again to advance from the most frequently used word to the second most frequently used w
Grover Dale L.
Grunbock Cheryl A.
King Martin T.
Kushler Clifford A.
Christensen O'Connor Johnson & Kindness PLLC
Huynh Ba
Tegic Communications Inc.
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