Patent ID: 7712053

Claim:
An apparatus for explicit character filtering of ambiguous key input sequences, said apparatus comprising: a display; a processor, wherein said processor manages output of words to said display; a keyboard comprising a plurality of keys coupled to the processor through appropriate interfacing circuitry, wherein at least some of said keys are associated with at least two letters, wherein single, one-tap key inputs of said keys associated with at least two letters comprise an ambiguous key input, and wherein non-single/non-one-tap key inputs of said keys associated with at least two letters comprises an explicit key input that specifies precisely one intended letter, wherein said processor receives at least one sequence of key inputs from said keyboard, and wherein said at least one sequence of key inputs includes both at least one ambiguous key input resulting from a single one-tap key input and at least one explicitly entered intended letter input in a particular position within the sequence of key inputs; a means for recognizing non-single/non-one-tap key input from a single, one-tap key input selected from among a group of precise letter entry means consisting of: 2-key explicit entry; long pressing a key to display and cycle through a character sequence; long pressing on a key to enter a number/digit explicitly; changing to a numbers mode and pressing a key to enter a number/digit explicitly; changing to a multi-tap mode and pressing a key repeatedly to enter a character explicitly; interpreting ambiguous mode key presses as an explicit character by grouping each pair of key presses as a 2-key explicit entry; interpreting ambiguous mode key presses as an explicit character by grouping repeated presses of the same key as a multi-tap entry; using multi-switch keys, thereby permitting ambiguous entry on a simple press and an explicit character entry on a different kind of press; chording by pressing at least two keys simultaneously, with a primary key indicating an ambiguous set of characters and a secondary key indicating which character in the set to select; and using a softkey as a secondary means for offering any character assigned to a key based on analysis of most likely character associated with a preceding keystroke based on words in a current word candidate list; and a memory coupled to said processor, wherein said memory comprises: a word database, wherein words are associated with sequences of key inputs; a means for disambiguating the at least one sequence of key inputs at a word level, wherein a set of candidate words associated with said at least one sequence of key inputs is identified; and a means for filtering the set of candidate words, wherein words from the set of candidate words which do not contain said intended letter in said particular position within the sequence of key inputs are filtered out of the set of candidate words, thereby forming a filtered set of candidate words, wherein only the filtered set of candidate words are output to said display.