System and method for recognizing touch typing under limited tactile feedback conditions

Abstract

A system is disclosed for recognizing typing from typing transducers that provide the typist with only limited tactile feedback of key position. The system includes a typing decoder sensitive to the geometric pattern of a keystroke sequence as well as the distance between individual finger touches and nearby keys. The typing decoder hypothesizes plausible key sequences and compares their geometric pattern to the geometric pattern of corresponding finger touches. It may also hypothesize home row key locations for touches caused by hands resting on or near home row. The resulting pattern match metrics may be combined with character sequence transition probabilities from a spelling model. The typing decoder then chooses the hypothesis sequence with the best cumulative match metric and sends it as key codes or commands to a host computing device.

Description

CROSS REFERENCE TO RELATED APPLICATIONSReferenced-applications[0001]Ser. No. 09 / 236,513 Jan. 1, 1999 U.S. Pat. No. 5,463,388 Jan. 29, 1993 U.S. Pat. No. 5,812,698 Jul. 14, 1997 U.S. Pat. No. 5,818,437 Jul. 26, 1995 U.S. Pat. No. 6,137,908 Jun. 29, 1994 U.S. Pat. No. 6,107,997 Jun. 27, 1996.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention pertains to typing recognition systems and methods, and more particularly to recognition of typing in air or on a relatively smooth surface that provides less tactile feedback than conventional mechanical keyboards.[0004]2. The Related Art[0005]Typists generally employ various combinations of two typing techniques: hunt and peck and touch typing. When hunting and pecking, the typist visually searches for the key center and strikes the key with the index or middle finger. When touch typing, the fingers initially rest on home row keys, each finger is responsible for striking a certain column of keys and the typist ...

AI Technical Summary

Benefits of technology

[0018]A secondary objective of this invention is to beneficially incorporate key / hand alignment measurements from resting hands into recognition decisions without explicitly shifting the key layout into alignment with the resting hands.

Problems solved by technology

However, even skilled touch typists occasionally fall back on hunt and peck to find rarely-used punctuation or command keys at the periphery of the key layout.

Touch typing is considered impractical on such devices for several reasons: a shrunken key layout may have a key spacing too small for each finger to be aligned with its own key column, the smooth screen surface provides no tactile feedback of finger / key alignment as keys are struck, and most touchscreens cannot accurately report finger positions when touched by more than one finger at a time.

The only remaining barrier to fast touch typing on an MTS is the lack of tactile feedback.

First, any textures added to the surface to indicate key centers can potentially interfere with smooth sliding across the surface during multi-finger pointing and dragging operations.

Second, the MTS proximity sensors actually allow zero-force typing by sensing the presence of a fingertip on the surface whether or not the finger applies noticeable downward pressure to the surface.

Typists can limit the hand drift by anchoring their palms in home position on the surface, but many keystrokes will still be slightly off center due to drift and reach errors by individual fingers.

Such hand drift and erroneous finger placements wreak havoc with the simple ‘nearest key’ recognizers disclosed in the related touchscreen and touch keyboard art.

However, such systems have a major weakness.

Unfortunately, heavy reliance on spelling models and alternative entry processes is simply impractical for a general-purpose typing recognizer.

Typing, after all, is the fallback entry process for many handwriting and speech recognition systems, and the only fallback conceivable for typing is a slower, clumsier typing mode.

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