System and Method For Detecting the Location, Size and Shape of Multiple Objects That Interact With a Touch Screen Display

• US 20090135162A1
• Filed: 03/08/2006
• Published: 05/28/2009
• Est. Priority Date: 03/10/2005
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Lashina, Tatiana A., Van De Wijdeven, Sander B.F.
• Application Number:
  US11/908,032
• Publication Number:
  US 20090135162A1
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

A system, method and apparatus is disclosed for detecting the location, size and shape of an object, or multiple objects, placed on a plane within the touch sensor boundaries of a touch screen (10).

Claims

1. A method for detecting the location, shape and size of at least one object placed on a plane within the touch sensor boundaries of a touch screen (10), the touch screen (10) including on its periphery a plurality of light transmitters L_i{i=1−

N} and a plurality of sensors S_k{k=1−

M}, the method comprising the acts of;

(a) acquiring calibration data for each of the N light transmitters L_i;

(b) acquiring non-calibration data for each of the N light transmitters L_i;

(c) computing N minimum area estimates of said at least one object using the calibration data and the non-calibration data;

(d) combining the N minimum area estimates to derive a total minimum object area estimate of the at least one object;

(e) computing N maximum area estimates of said at least one object using the calibration data and the non-calibration data;

(f) combining the N maximum area estimates to derive a total maximum object area estimate of the at least one object; and

(g) combining the total minimum and maximum object area estimates to derive the boundary area of the at least one object.

2. The method of claim 1, wherein said act (a) of acquiring calibration data is performed over a single cycle of operation starting with a first light transmitter L_i (i=1) and ending with a last light transmitter L_i (i=N).

3. The method of claim 2, wherein said act (a) of acquiring calibration data further comprises the acts of:

turning on each of said N light transmitters L_i for a predetermined length of time in a predetermined sequence;

during the turn-on time of said i-th light transmitter L_i, detecting the presence or absence of a light signal from said i-th light transmitter L_i at each of said M sensors S_k; and

storing the detected presence or absence of said light signal from said i-th light transmitter for each of said M sensors S_k as said calibration data.

4. The method of claim 2, wherein said act (a) of acquiring calibration data is performed with no objects present in the plane of the touch screen (10).

5. The method of claim 1, wherein said acts (b) through (g) are performed over multiple sequential cycles of operation.

6. The method of claim 1, wherein said act (b) further comprises the acts of:

(a) turning on each of said N light transmitters L_i in a predetermined sequence for a predetermined length of time; and

(b) during the turn-on time of said ith light transmitter L_i, detecting the presence or absence of a light signal from said i-th light transmitter L_i at each of said M sensors S_k; and

(c) storing the presence or absence of said light signal from said i-th light transmitter for each of said M sensors S_k as said non-calibration data.

7. The method of claim 6, wherein said act (b) of acquiring non-calibration data is performed in the presence of said at least one object.

8. The method of claim 1, wherein said act (c) further comprises:

(1) retrieving the calibration data from a data repository;

(2) retrieving the non-calibration data from the data repository;

(3) determining from the retrieved calibration data a range of sensors M illuminated by the i-th light transmitter;

(4) determining from the retrieved non-calibration data a range of sensors M not illuminated by the i-th light transmitter;

(5) computing an i-th minimum area estimate for the at least one object from the range of sensors M illuminated by the i-th light transmitter determined at said act (3) and from the range of sensors M illuminated by the i-th light transmitter determined at said act (4); and

(6) repeating said acts (3)-(5) for each light transmitter L_i.

9. The method of claim 8, further comprising the act of storing the N minimum area estimates.

10. The method of claim 1, wherein said act (d) further comprises the act of performing a mathematical intersection of the N minimum area estimates computed at said act (c).

11. The method of claim 10, wherein the mathematical intersection of the N minimum area estimates is computed as:

$\begin{array}{cc}{A}_{{\mathrm{Total}}_{\min }}=<br><br>\{\begin{array}{cc}\mathrm{\varnothing <br><br>},& \mathrm{if}<br><br><br><br>A_{L_{0_{\min }}}=A_{L_{1_{\min }}}=\mathrm{\dots <br><br>}=A_{L_{N_{\min }}}=0\\ \left(\underset{i=0,A_{L_{i<br><br><br><br>\max }}}{\stackrel{N-1}{\bigcap <br><br>}}<br><br>A_{L_{i<br><br><br><br>\max }}\right),& \mathrm{otherwise}\end{array}& \left(2\right)\end{array}$

12. The method of claim 8, further comprising the act of storing the N maximum area estimates.

13. The method of claim 1, wherein said act (e) further comprises the act of performing a mathematical intersection of the N maximum area estimates computed at said act (e).

14. The method of claim 13, wherein the mathematical intersection of the N maximum area estimates is computed as:

$\begin{array}{cc}{A}_{{\mathrm{Total}}_{\max }}=\{\begin{array}{cc}\mathrm{\varnothing <br><br>},& <br><br>\mathrm{if}<br><br><br><br>A_{L_{0_{\max }}}=A_{L_{1_{\max }}}=\mathrm{\dots <br><br>}=A_{L_{N_{\max }}}=0\\ \underset{i=0,A_{L_{i_{\max }}}\ne <br><br>\mathrm{\varnothing <br><br>}}{\stackrel{N-1}{\bigcap <br><br>}<br><br>A_{L_{i_{\max }}},}& <br><br>\mathrm{otherwise}\end{array}& \left(1\right)\end{array}$

15. The method of claim 1, wherein said act (g) further comprises the act of performing a mathematical intersection of the total minimum object area estimate derived at said act (d) and the total maximum object area estimate derived at said act (f).

16. The method of claim 6, wherein said predetermined sequence is one of a (a) plain sequence, (b) optimized sequence and (c) interactive sequence.

17. The method of claim 16, wherein turning on each of said N light transmitters L_i in accordance with the plain sequence comprises the acts of:

i) turning on a first light transmitter L_i located in the periphery of the touch screen (10) for said predetermined length of time;

ii) proceeding in one of a clockwise or counter-clockwise direction to an adjacent light transmitter L_i located in the periphery of the touch screen (10);

iii) turning on said adjacent light transmitter L_i located in the periphery of the touch screen (10) for said predetermined length of time;

iv) repeating said acts (ii)-(iii) for each light transmitter L_i located in the periphery of the touch screen (10).

18. The method of claim 16, wherein turning on each of said N light transmitters L_i in accordance with the optimized sequence comprises the acts of:

i) sequentially turning on those light transmitter L_i located in the respective corners of the periphery of the touch screen (10) for a predetermined length of time and

ii) selecting at least one additional light transmitter L_i located in on the periphery of the touch screen (10) to provide maximum detection information; and

ii) turning on the selected at least one additional light transmitter L_i touch screen (10).

19. The method of claim 16, wherein turning on each of said N light transmitters L_i in accordance with the interactive sequence comprises:

i) retrieving non-calibration data from a previous cycle of operation;

ii) determining from the non-calibration data in a present cycle of operation which of said light transmitters L_i to turn on, where the determination is a based on the at least one object'"'"'s previously detected position

iii) turning on said light transmitters L_i as determined at act (ii) in a further predetermined sequence for said predetermined length of time;

iv) turning on each of the respective corner light transmitters L_i touch screen (10).

20. An apparatus for detecting the location, shape and size of at least one object placed on a plane within the touch sensor boundaries of a touch screen (10), the touch screen (10) comprising a plurality of light transmitters L_i {i=1−

N} and sensors S_k {k=1−

M} arranged around a periphery of said touch screen (10).

21. An apparatus according to claim 20, wherein the plurality of light transmitters L_i {i=1−

N} and the plurality of sensors S_k {k=1−

M} are arranged in an alternating pattern around the periphery of the touch screen (10).

22. An apparatus according to claim 20, wherein the shape of said touch screen (10) is one of a square, a circle and an oval.

23. An apparatus according to claim 20, wherein each transmitter L_i transmits a light beam having a characteristic light beam width {acute over (α

)} during its respective turn-on time.

24. The apparatus of claim 23, wherein the characteristic light beam width {acute over (α

)} can be different for different light transmitters.

25. An apparatus according to claim 20, wherein said plurality of light transmitters L_i {i=1−

N} is located in a first plane around the periphery of the touch screen (10) and the plurality of sensors S_k {k=1−

M} are arranged in a second plane around the periphery of the touch screen (10), wherein said second plane is substantially adjacent said first plane.

26. An apparatus according to claim 20, wherein each of said light transmitters L_i are spaced equidistant around the periphery of said touch screen (10).

27. An apparatus according to claim 21, wherein each of said light transmitters L_i are spaced non-equidistant around the periphery of said touch screen (10).

28. An apparatus according to claim 21, wherein certain of said light transmitters L_i orientation towards the center of said touch screen (10) is not perpendicular to said touch screen (10).

29. An apparatus for detecting the location, shape and size of at least one object placed on a plane within the touch sensor boundaries of a touch screen (10), the touch screen (10) including on its periphery a plurality of light transmitters L_i {i=1−

N} and a plurality of sensors S_k {k=1−

M}, the system comprising;

means for acquiring calibration data for each of the N light transmitters L_i;

means for acquiring non-calibration data for each of the N light transmitters L_i;

means for computing N minimum area estimates of said at least one object using the calibration data and the non-calibration data;

means for combining the N minimum area estimates to derive a total minimum object area of the at least one object;

means for computing N maximum area estimates of said at least one object using the calibration data and the non-calibration data;

means for combining the N maximum area estimates to derive a total maximum object area of the at least one object; and

means for combining the total minimum and maximum object areas to derive an actual object area of the at least one object.