Method and apparatus for using pressure information for improved computer controlled handwriting recognition, data entry and user authentication

• US 6,707,942 B1
• Filed: 03/01/2000
• Issued: 03/16/2004
• Est. Priority Date: 03/01/2000
• Status: Expired due to Fees

• Current Assignee: Access Company Limited
• Original Assignee: Palmsource Incorporated (Access Company Limited)
• Inventors: Endejan, Edward, Cortopassi, Michael
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Lu, Tom Y.
• Application Number:
  US09/516,656
• Time in Patent Office: 1,476 Days
• Field of Search: 382/186, 382/187, 382/119, 382/224, 382/313, 345/179, 345/156, 341/23
• US Class Current: 382/186
• CPC Class Codes: G06F 3/033 Pointing devices displaced or positioned by the user , e.g. mice, trackballs, pens or joysticks; Accessories therefor digitisers characterised by the transducing means G06F3/041
• CPC Class Codes: G06V 30/1423 the instrument generating sequences of position coordinates corresponding to handwriting preprocessing or recognising digital ink G06V30/32
• CPC Class Codes: G06V 30/373 using a special pattern or subpattern alphabet

Abstract

A method and system utilizing both (x, y) coordinate (“spatial”) stroke data and associated pressure information for improved handwriting recognition. The method and system can also be applied to all types of handwriting-based data entry applications and also to user authentication. The digitizer pad used in the computer system gives both spatial information and associated pressure data when a stroke is being drawn thereon, e.g., by a stylus. Pressure information can be used to differentiate between different character sets, e.g., upper case and lower case characters for certain alphabetic characters. The spatial stroke data then identifies the particular character. The pressure information can also be used to adjust any display attribute, such as character font size, font selection, color, italic, bold, underline, shadow, language, etc. The associated pressure information can also be used for recognizing a signature. In this case, a user is allowed to sign a name on the digitizer pad. This provides non-character based user authentication that relies not only on the spatial stroke data but also on the pressure applied at different points in the signed name or image. Pressure information can also be used to provide improved handwriting-based data entry. For instance, in a drafting program, the pressure of a drawn line can be used to determine its width. Generally, pressure data can also be used to improve handwriting recognition tasks and heuristics.

Claims

1. A method of recognizing data representing a user-drawn character, said method comprising the steps of:

a) accessing spatial stroke data and pressure data captured by a digitizer and representing said user-drawn character wherein respective pressure data is associated with respective spatial stroke data;

b) storing said spatial stroke data and pressure data into a computer memory wherein pressure data of a first range represents a first character set and pressure data of a second range represents a second character set;

c) performing character recognition on said spatial stroke data and said pressure data, said step c) comprising the steps of;

c1) using said pressure data to identify a character set; and

c2) using said spatial stroke data to identify a particular character within said identified character set; and

d) displaying said particular character on a display screen of a computer system.

2. A method as described in claim 1 wherein said first character set comprises upper case alphabetic characters and wherein said second character set comprises lower case alphabetic characters.

3. A method as described in claim 1 wherein said first character set comprises characters of a first size and wherein said second character set comprises characters of a second size, said first and second sizes being different.

4. A method as described in claim 1 wherein said first character set comprises characters of a first font and wherein said second character set comprises characters of a second font, said first and second fonts being different.

5. A method as described in claim 1 wherein said first character set comprises characters of a first language and wherein said second character set comprises characters of a second language, said first and second languages being different.

6. A method as described in claim 1 wherein said computer system is a portable computer system.

7. A method as described in claim 1 wherein said computer system is a palm sized computer system.

8. A method as described in claim 1 wherein said digitizer comprises:

a first region for capturing spatial stroke data and pressure data associated with alphabetic characters and not numeric characters; and

a second region for capturing spatial stroke data and pressure data associated with numeric characters and not alphabetic characters.

9. A method as described in claim 1 wherein said digitizer is separate in area from said display screen.

10. A computer system comprising a processor, a memory unit, a display screen and a digitizer wherein said memory contains instructions that when executed implement a method of recognizing data representing a user-drawn character, said method comprising the steps of:

a) accessing spatial stroke data and pressure data captured by said digitizer and representing said user-drawn character wherein respective pressure data is associated with respective spatial stroke data;

b) storing said spatial stroke data and pressure data into said memory wherein pressure data of a first range represents a first character set and pressure data of a second range represents a second character set;

c) performing character recognition on said spatial stroke data and said pressure data, said step c) comprising the steps of;

c1) using said pressure data to identify a character set; and

c2) using said spatial stroke data to identify a particular character within said identified character set; and

d) displaying said particular character on said display screen.

11. A computer system as described in claim 10 wherein said first character set comprises upper case alphabetic characters and wherein said second character set comprises lower case alphabetic characters.

12. A computer system as described in claim 10 wherein said first character set comprises characters of a first size and wherein said second character set comprises characters of a second size, said first and second sizes being different.

13. A computer system as described in claim 10 wherein said first character set comprises characters of a first font and wherein said second character set comprises characters of a second font, said first and second fonts being different.

14. A computer system as described in claim 10 wherein said first character set comprises characters of a first language and wherein said second character set comprises characters of a second language, said first and second languages being different.

15. A computer system as described in claim 10 wherein said computer system is a portable computer system.

16. A computer system as described in claim 10 wherein said computer system is a palm sized computer system.

17. A computer system as described in claim 10 wherein said digitizer comprises:

a first region for capturing spatial stroke data and pressure data associated with alphabetic characters and not numeric characters; and

a second region for capturing spatial stroke data and pressure data associated with numeric characters and not alphabetic characters.