Pressure sensitive writing tablet, control method and control program therefor

• US 6,788,297 B2
• Filed: 02/19/2002
• Issued: 09/07/2004
• Est. Priority Date: 02/21/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Tabata, Toshiroh, Itoh, Hiroji, Mori, Masaya
• Primary Examiner(s): Lao, Lun-Yi
• Application Number:
  US10/078,794
• Publication Number:
  US 20020113779A1
• Time in Patent Office: 931 Days
• Field of Search: 345/173-183, 345/104, 178/18-1-, 178/19-1-, 382/202-203, 382/217-223, 382/187, 382/186, 382/181, 382/188, 382/189, 463/37-38
• US Class Current: 345/179
• CPC Class Codes: G06F 3/04144 using an array of force sensing means position sensing using the local deformation of sensor cells G06F3/0447
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

Since the surface of the touch panel is often slippery, pressure points of the writing stylus on a touch panel may easily skip along the input contiguous line. The present invention calculates the velocity of writing stylus movement at each segment of the input contiguous line from a touch location and detection time of each touch which may be detected at intervals, produces a line drawing which connects each pair of touch locations of touches that are temporally adjacent in the detection order with a line of a type determined based on the calculated velocity, and displays the line drawing on the LCD.

Claims

1. A pressure sensitive writing tablet comprising:

a touch panel for generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched the touch surface;

means for generating touch data including data on a touch location and a touch time for each touch of said writing stylus to said touch surface by sampling the output signal of said touch panel, determining if there was a touch of said writing stylus to said touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of said touch;

means for determining, based on said touch data, whether each touch of said touch data is a touch on a contiguous line input on said touch panel;

means for generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities;

means for determining, based on said velocity data, a type of a line connecting the touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order defined as adjacent touches, wherein said line type determining means sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when the velocity is low;

means for producing a line drawing connecting the touch locations of the respective adjacent touches based on the line types determined by said line type determining means; and

a display device for displaying the line drawing produced by said line drawing producing means.

2. The tablet of claim 1, wherein said display device is provided at a side opposite to said touch surface of said touch panel.

3. The tablet of claim 1, wherein when said line type determining means determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1): earlier and later adjacent touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting the touch locations of C(−

1) and C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and L2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of a triangle C(0)-Ra—

C(1).

4. The tablet of claim 1, wherein a time interval for detecting the output signal of said touch panel by said touch data generating means is shorter than the minimum time interval defined as the time required for a user to move the writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.

5. Electronic paper comprising a pressure sensitive writing tablet of claim 1.

6. A pressure sensitive writing tablet comprising:

a touch panel for generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched the touch surface;

means for generating primary touch data including data on a primary touch location and a touch time for each touch of said writing stylus to said touch surface by sampling the output signal of said touch panel, determining if there was a touch of said writing stylus to said touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of said touch;

means for determining, based on said primary touch data, whether each touch of said primary touch data is a touch on a contiguous line input on said touch panel;

means for generating secondary touch data including data on a secondary touch location for each touch by computing the secondary touch location which is obtained from correcting, by a predetermined correction process, a primary touch location of a touch included in said primary touch data and located on the target touch contiguous line and defined as a target touch, based on primary touch locations of multiple touches defined as correcting touches herein having the respective touch times within a predetermined time range Ta including the touch time of said target touch;

means for producing a line drawing connecting with a selected line the secondary touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order defined as adjacent touches; and

,

a display device for displaying the line drawing produced by said line drawing producing means.

7. The tablet of claim 6, wherein said correcting touches in said correction process are touches at primary touch locations in a predetermined area Ao containing the primary touch location of said target touch.

8. The tablet of claim 7, wherein said correction process counts for each primary touch location the number of correcting touches having the same primary touch location, and selects a primary touch location having the highest count as a secondary touch location for the target touch.

9. The tablet of claim 8, wherein said correction process computes an average position of the primary touch locations of the correcting touches, and selects this average position as the secondary touch location for said target touch if there is no primary touch location having the highest count.

10. The tablet of claim 6, wherein a time interval for detecting the output signal of said touch panel by said touch data generating means is shorter than the minimum time interval defined as the time required for a user to move the writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.

11. The tablet of claim 6, wherein said display device is provided at a side opposite to said touch surface of said touch panel.

12. Electronic paper comprising a pressure sensitive writing tablet of claim 6.

13. The tablet of claim 6, further comprising:

means for generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities; and

means for determining, based on said velocity data, a type of a line connecting the secondary touch locations of the adjacent touches.

14. The tablet of claim 13, wherein said line type determining means sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when the velocity is low.

15. The tablet of claim 14, wherein when said line type determining means determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1):

earlier and later writing stylus touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting the touch locations of C(−

1) and C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and R2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of a triangle C(0)-Ra—

C(1).

16. A method for controlling a pressure sensitive writing tablet, comprising the steps of:

generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched the touch surface;

generating touch data including data on a touch location and a touch time for each touch of said writing stylus to said touch surface by sampling said output signal generated by said output signal generating step, determining if there was a touch of said writing stylus to said touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of said touch;

determining, based on said touch data, whether each touch of said touch data is a touch on a contiguous line input on said touch panel;

generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities;

determining, based on said velocity data, a type of a line connecting the touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order defined as adjacent touches, wherein said line type determining step sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when the velocity is low;

producing a line drawing connecting the touch locations of the respective adjacent touches based on the line types determined by said line type determining step; and

displaying the line drawing produced by said line drawing producing step.

17. The method of claim 16, wherein said displaying step displays at the back of said touch panel.

18. The method of claim 16, wherein when said line type determining step determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1): earlier and later adjacent touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting the touch locations of C(−

1) and C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and L2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of a triangle C(0)-Ra—

C(1).

19. The method of claim 16, wherein a time interval for detecting the output signal of said touch panel by said touch data generating step is shorter than the minimum time interval defined as the time required for a user to move the writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.

20. A method for controlling a pressure sensitive writing tablet comprising the steps of:

generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched a touch surface of a touch panel;

generating primary touch data including data on a primary touch location and a touch time for each touch of said writing stylus to said touch surface by sampling the output signal of said touch panel, determining if there was a touch of said writing stylus to said touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of said touch;

determining, based on said primary touch data, whether each touch of said primary touch data is a touch on a contiguous line input on said touch panel;

generating secondary touch data including data on a secondary touch location for east touch by computing the secondary touch location which is obtained from correcting, by a predetermined correction process, a primary touch location of a touch included in said primary touch data and located on the contiguous line, defined as target touch, based on primary touch locations of multiple touches, defined as correcting touches, having the respective touch times within a predetermined time range Ta including the touch time of said target touch;

producing a line drawing connecting with a selected line the secondary touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order, defined as adjacent touches; and

displaying the line drawing produced by said line drawing producing step.

21. The method of claim 20, wherein said displaying step displays at the back of said touch panel.

22. The method of claim 20, wherein a time interval for detecting the output signal of said touch panel by said touch data generating means is shorter than the minimum time interval defined as the time required for a user to move the writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.

23. The method of claim 20, wherein said correcting touches in said correction process are touches at primary touch locations in a predetermined area Ao containing the primary touch location of said target touch.

24. The method of claim 23, wherein said correction process counts for each primary touch location the number of correcting touches having the same primary touch location, and selects a primary touch location having the highest count as a secondary touch location for the target touch.

25. The method of claim 24, wherein said correction process computes an average position of the primary touch locations of the correcting touches, and selects this average position as the secondary touch location for the target touch if there is no primary touch location having the highest count.

26. The method of claim 20, further comprising the steps of:

generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities; and

determining, based on said velocity data, a type of a line connecting the secondary touch locations of the adjacent touches.

27. The method of claim 26, wherein said line type determining step sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when the velocity is low.

28. The method of claim 27, wherein when said line type determining step determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1):

earlier and later writing stylus touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting the touch locations of C(−

1) and C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and L2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of a triangle C(0)-Ra—

C(1).

29. A control program for a pressure sensitive writing tablet, comprising the computer implemented steps of:

generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched the touch surface;

generating touch data including data on a touch location and a touch time for each touch of said writing stylus to said touch surface by sampling said output signal generated by said output signal generating step, determining if there was a touch of said writing stylus to said touch surface based on to sampled data, and, if tore was a touch, detecting the touch location and touch time of said touch;

determining, based on said touch data, whether each touch of said touch data is a touch on a contiguous line input on said touch panel;

generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities;

determining, based on said velocity data, a type of a line connecting the touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order, defined as adjacent touches, wherein said line type determining means sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when to velocity is low;

producing a line drawing connecting the touch locations of to respective adjacent touches based on the line types determined by said line type determining step; and

displaying the line drawing produced by said line drawing producing step.

30. The program of claim 29, wherein when said line type determining step determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1): earlier and later adjacent touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting to touch locations of C(−

1) ad C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and L2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of in triangle C(0)-Ra—

C(1).

31. The program of claim 29, wherein a time interval for detecting to output signal of said touch panel by said touch data generating step is shorter than to minimum time interval defined as to time required for a user to move to writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.

32. A control program for a pressure sensitive writing tablet, comprising the computer implemented steps of:

generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched a touch surface of a touch panel;

generating primary touch data including data on a primary touch location and a touch time for each touch of said writing stylus to said touch surface by sampling the output signal of said touch panel, determining if there was a touch of said writing stylus to said touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of said touch;

determining, based on said primary touch data, whether each touch of said primary touch data is a touch on a contiguous line input on said touch panel;

generating secondary touch data including data on a secondary touch location for each touch by computing the secondary touch location which is obtained from correcting, by a predetermined correction process, a primary touch location of a touch included in said primary touch data and located on the contiguous line, defined as target touch, based on primary touch locations of multiple touches, defined as correcting touches, having the respective touch times within a predetermined time range Ta including the touch time of said target touch;

producing a line drawing connecting with a selected line the secondary touch locations of two touches that are onto contiguous line and temporally adjacent to each other into detection order defined as adjacent touches; and

displaying the line drawing produced by said line drawing producing step.

33. The program of claim 32, wherein said correcting touches in said correction process are touches at primary touch locations in a predetermined area Ao containing the primary touch location of said target touch.

34. The program of claim 33, wherein said correction process counts for each primary touch location the number of correcting touches having the same primary touch location, and selects a primary touch location having tire highest count as a secondary touch location for the target touch.

35. The program of claim 34, wherein said correction process computes an average position of the primary touch locations of the correcting touches, and selects this average position as the secondary touch location for the target touch if there is no primary touch location having the highest count.

36. The program of claim 32, further comprising the computer implemented steps of:

generating velocity data by calculating, based on said touch data, a velocity of said writing stylus at each segment of the contiguous line input on said touch surface, said velocity data including data relating to the calculated velocities; and

determining, based on said velocity data, a type of a line connecting the secondary touch locations of the adjacent touches.

37. The program of claim 36, wherein said line type determining step sets, as a connecting line between two touch locations of adjacent touches, a line having a less curvature when the velocity of said writing stylus between said two touch locations on said touch surface is high than when the velocity is low.

38. The program of claim 37, wherein when said line type determining step determines that said writing stylus has moved on a curve between the adjacent touches, it defines the following,

C(0), C(1):

earlier and later writing stylus touches, respectively,

C(−

1);

a touch one before C(0),

C(2);

a touch one after C(1),

L1;

a line connecting the touch locations of C(−

1) and C(0),

L2;

a line connecting the touch locations of C(1) and C(2),

Ra;

an intersection of L1 and L2; and

sets the line connecting C(0) and C(1) to a line type passing inside the sides of a triangle C(0)-Ra—

C(1).

39. The program of claim 32, wherein a time interval for detecting the output signal of said touch panel by said touch data generating means is shorter than the minimum time interval defined as the time required for a user to move the writing stylus by z on said touch panel, where z represents a shortest distance between touch locations which can be identified on said touch panel.