Many portable electronic devices are designed to utilize only a touch-screen for text input, generally using some form of
stylus to contact the screen. Such devices generally input text using some form of
handwriting recognition, which is slow and often inaccurate, or an on-screen keyboard, which essentially requires the user to perform ''one-finger''
typing, often on a reduced-size keyboard. The Continuous
Stroke Word-Based Text Input
System allows someone to use a small on-screen keyboard to quickly enter words by drawing a continuous line that passes through or near the keys of each letter in a word in sequence without lifting the
stylus (similar to a children's connect-the-dots drawing). The user traces an input pattern for a word by contacting the keyboard on or near the key of the first letter of the word, then tracing through each letter in sequence, lifting the
stylus from the screen upon reaching the last letter. In one preferred embodiment, the user traces a small circle around each double-letter that occurs in the word to reduce
ambiguity. In another preferred embodiment, a
database of words is organized according to the first and last letters so that only a small number of words need to be explicitly scored for each input pattern. In another preferred embodiment, the expected
path length corresponding to each word is stored in the
database and is compared to the actual input
path length entered to further limit the number of words to be explicitly scored. The input pattern is analyzed to identify inflection points of various types, each of which has a greater or lesser probability of corresponding to a letter of the word being input. Words are scored according to the average distance from each letter to the nearest inflection point (or to the
nearest point of the traced line if there are more letters in the word than detected inflection points in the input pattern).