Adjusting keyboard

• US 5,748,512 A
• Filed: 02/28/1995
• Issued: 05/05/1998
• Est. Priority Date: 02/28/1995
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Vargas, Garrett R.
• Primary Examiner(s): Elmore, Reba I.
• Assistant Examiner(s): Lewis, Monica
• Application Number:
  US08/396,444
• Time in Patent Office: 1,162 Days
• Field of Search: 364/709.12, 364/419, 364/419.02, 364/419.13, 364/709.15, 345/173-178, 200/512, 341/23, 178/18, 395/893
• US Class Current: 708/142
• CPC Class Codes: G06F 3/0237 using prediction or retrieval techniques
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus

Abstract

An adjusting keyboard for a small, touch screen display for a personal digital assistant provides a system and method for selecting a character for entry when a key of the keyboard is struck off center. The system and method of the adjusting keyboard select the next character for entry from the keyboard based on the occurrence frequency of a predetermined number of previously entered characters and the distance the user has contacted the touch screen keyboard from the center points of proximate keys including the key actually contacted. Contact by the user within 0.2 of the key length from the center point of a key is considered a direct hit, and the character represented by that key is entered. For touch contacts beyond 0.2 of the length of the key from the center point of the key, the method of the present invention selects two adjacent keys and the key actually contacted and determines which of the characters represented by those three proximate keys is the most likely candidate for entry based on occurrence frequency and the distance between the contact point and the center points of each of the proximate keys. Once the character has been selected for entry, the occurrence frequency on that character is incremented in a table in memory to reflect occurrence frequency for that character based on the user'"'"'s own use. A word prediction algorithm can also be run in the background to enhance the character selection based on occurrence frequency.

Claims

1. A keyboard for a computer comprising:

a contact sensitive surface divided into areas to define keys for the keyboard wherein each key represents a character and the area of each key has a center point;

sensing means in conjunction with the contact sensitive surface for resolving contact with the contact sensitive surface to a contact point;

character selection means for selecting a character from the characters represented by the keys of the keyboard, the character selection means comprising;

contact point location means for determining the location of the contact point with respect to the nearest center points of a predetermined number of proximate keys and determining the distances of the contact point from the center points of each of the proximate keys;

occurrence frequency determination means for determining which character represented by the proximate keys has the greatest frequency of following a predetermined number of preceding characters previously selected by the character selection means; and

index calculation means for calculating a character index for each character represented by each proximate key as a function of the occurrence frequency and the distances of the contact point from the center points of each of the proximate keys.

2. The system of claim 1, wherein the area of each key is defined by key dimensions and wherein a character represented by one of the proximate keys is selected regardless of the character index value where the contact point is within the area of one of the proximate keys and the distance from the contact point to the center point of the one proximate key is less than a predetermined multiple of the key dimensions.

3. The system of claim 2, wherein the predetermined number of proximate keys is three.

4. The system of claim 2, wherein key area is rectangular, the key dimensions are a width and a height and the distance from the contact point to the center point is less that 0.2 of the key width.

5. The system of claim 1, wherein the index calculating means calculates a frequency value that is a function of the occurrence frequency and divides the frequency value by the distance from the contact point to the center point of each of the proximate keys.

6. The system of claim 5, wherein the system further includes word prediction means for continuously predicting the next character of a character string and comparator means for comparing the next character from the word prediction means to the characters represented by the proximate keys and if the next character resulting from the word prediction means matches one of the characters represented by one of the proximate keys, the index calculation means increases the occurrence frequency for that character.

7. The system of claim 1, wherein the occurrence frequency determination means is a set of tables have entries for the occurrence frequency of each character and wherein the entry for the occurrence frequency in the occurrence frequency table for the character selected by the selection means is incremented.

8. The system of claim 1, wherein the system sets the occurrence frequency to a low value for a character which was just erased to make its selection less likely.

9. A method for selecting a character as a result of a user contact with a keyboard wherein the keyboard comprises a contact sensitive surface divided into areas to define keys for the keyboard, each key represents a character and the area of each key has a center point, the method comprises the steps of:

a. resolving the user contact with the keyboard to a contact point;

b. identifying a predetermined number of proximate keys having center points nearest the contact point;

c. determining the distances of the contact point from the center points of each of the proximate keys;

d. determining the occurrence frequency of each character represented by each proximate key based on a predetermined number of preceding characters;

e. calculating a character index value for each of the characters represented by each proximate key, the index being a function of the occurrence frequency of the character and the distance of the center point of each proximate key from the contact point;

f. selecting the character with the greatest character index value.

10. The method of claim 9, wherein the area of each key is defined by key dimensions and wherein a character represented by one of the proximate keys is selected regardless of the character index value where the contact point is within the area of one of the proximate keys and the distance from the contact point to the center point of the one proximate key is less than a predetermined multiple of the key dimensions.

11. The method of claim 10, wherein the predetermined number of proximate keys is three.

12. The method of claim 10, wherein key area is rectangular, the key dimensions are a width and a height and the distance from the contact point to the center point is less that 0.2 of the key width.

13. The method of claim 9, wherein the step of calculating the character index value for each of the characters represented by each proximate key further includes calculating a frequency value that is a function of the occurrence frequency and dividing the frequency value by the distance from the contact point to the center point of each of the proximate keys.

14. The method of claim 13, wherein characters from a word prediction algorithm are compared to the characters represented by the proximate keys and if a character resulting from the word prediction algorithm matches one of the characters represented by one of the proximate keys, the occurrence frequency for that character is increased.

15. The method of claim 9, wherein the occurrence frequency is determined from a set of occurrence frequency tables and wherein the occurrence frequency in the occurrence frequency table for the character with the highest index value is incremented.

16. The method of claim 9, wherein the occurrence frequency is set to a low value for a character which was just erased to make its selection less likely.

17. A computer-readable medium on which is stored a program module for selecting a character as a result of a user contact with a keyboard wherein the keyboard comprises a contact sensitive surface divided into areas to define keys for the keyboard, each key represents a character and the area of each key has a center point, the program module comprising instructions which when executed by the computer, performs the steps of:

a. resolving the user contact with the keyboard to a contact point;

b. identifying a predetermined number of proximate keys having center points nearest the contact point;

c. determining the distances of the contact point from the center points of each of the proximate keys;

d. determining the occurrence frequency of each character represented by each proximate key based on a predetermined number of preceding characters;

e. calculating a character index value for each of the characters represented by each proximate key, the index being a function of the occurrence frequency of the character and the distance of the center point of each proximate key from the contact point;

f. selecting the character with the greatest character index value.

18. The computer-readable medium of claim 17, wherein the area of each key is defined by key dimensions and wherein a character represented by one of the proximate keys is selected regardless of the character index value where the contact point is within the area of one of the proximate keys and the distance from the contact point to the center point of the one proximate key is less than a predetermined multiple of the key dimensions.

19. The computer-readable medium of claim 18, wherein the predetermined number of proximate keys is three.

20. The computer-readable medium of claim 18, wherein key area is rectangular, the key dimensions are a width and a height and the distance from the contact point to the center point is less that 0.2 of the key width.

21. The computer-readable medium of claim 17, wherein the step of calculating the character index value for each of the characters represented by each proximate key further includes calculating a frequency value that is a function of the occurrence frequency and dividing the frequency value by the distance from the contact point to the center point of each of the proximate keys.

22. The computer-readable medium of claim 21, wherein characters from a word prediction algorithm are compared to the characters represented by the proximate keys and if a character resulting from the word prediction algorithm matches one of the characters represented by one of the proximate keys, the occurrence frequency for that character is increased.

23. The computer-readable medium of claim 17, wherein the occurrence frequency is determined from a set of occurrence frequency tables and wherein the occurrence frequency in the occurrency frequency table for the character with the highest index value is incremented.

24. The computer-readable medium of claim 17, wherein the occurrence frequency is set to a low value for a character which was just erased to make its selection less likely.