Method and a device for optically detecting the position of an object by measuring light reflected by that object

• US 7,518,738 B2
• Filed: 09/02/2004
• Issued: 04/14/2009
• Est. Priority Date: 09/02/2003
• Status: Expired due to Fees

• Current Assignee: H2i Technologies
• Original Assignee: H2i Technologies
• Inventors: Plantier, Philippe G., Sylvestre, Julien P., Cavallucci, Gilles
• Primary Examiner(s): Chowdhury; Tarifur R.
• Assistant Examiner(s): Akanbi; Isiaka O
• Application Number:
  US10/540,579
• Publication Number:
  US 20060152740A1
• Time in Patent Office: 1,685 Days
• Field of Search: 356/614, 345/175
• US Class Current: 356/614
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

This detection method comprises: a step during which a receiver measures the quantity of light reflected by an object when the object is illuminated by an emitter for at least two different emitter—receiver pairs on the same side relative to the object, a step of calculating at least two characteristic values from the measured values, and a step of determining at least one position of the object by directly reading a table indexed by the two characteristic values, the content of said table being predetermined and set before said measurement step.

Claims

1. An optical detection method of determining the position of an object in a particular detection area of a surface, the method comprising:

a preliminary step of disposing in the vicinity of said detection area and on the same side thereof relative to the object at least four elements including two emitters of light and at least two receivers of light adapted to cover the detection area, each emitter being adapted to emit light in such a way that it does not hit said surface in the detection area, said emitters and receivers being disposed in an alternating and regular arrangement, the method further comprises;

a step during which one of said receiver measures the quantity of light reflected by the object when the object is illuminated by one of said emitters for at least two different emitter—

receiver pairs,

a step of calculating at least two characteristic values from said measured values, wherein, as emitters and receivers are disposed in the alternating and regular arrangement, a characteristic value is calculated for each emitter by averaging the values measured by the receivers on each side of said emitter when only said emitter is turned on, and

a step of determining at least one position of the object by directly reading a table indexed by said at least two characteristic values, the content of said table being predetermined and set before said measurement step.

2. A method according to claim 1, wherein, a characteristic value is calculated for each emitter by calculating a function of the values measured by at least three receivers when only that emitter is turned on, the coefficients of this affine function being a function of the distance between each receiver and that emitter.

3. A method according to claim 1, wherein said measurement step is repeated for each of said emitter—

receiver pairs until a stable quantity of reflected light is measured.

4. A method according to claim 1, wherein said predetermined table is obtained by a polynomial regression method from a number of preliminary measurements effected under the same conditions as apply to said measurement step.

5. A method according to claim 1, wherein said surface is substantially plane, and wherein, during said preliminary step, there are disposed in a single line emitters and receivers of light having an emission axis, respectively a reception axis, substantially parallel to said particular detection area.

6. A method according to claim 1, wherein said detection area is rectangular and the emitters and receivers are disposed in the vicinity of only one side of said rectangular area.

7. A method according to claim 1, wherein the light emitted by the light emitters is ordinary non-coherent light.

8. A method according to claim 7, wherein the wavelength of the light emitted is in one of the following ranges of wavelengths:

UV, visible, infrared.

9. A method according to claim 1, wherein said detection area comprises a set of elementary areas each associated with a given function so that any position of the object in an elementary area activates the function associated with that elementary area.

10. The use of a detection method according to claim 1 to detect the displacement of an object or to measure the speed of displacement of an object.

11. An optical detection method of determining the position of an object in a particular detection area of a surface, the method comprising:

a preliminary step of disposing in the vicinity of said detection area and on the same side thereof relative to the obiect at least four elements including two emitters of light and at least two receivers of light adapted to cover the detection area, each emitter being adapted to emit light in such a way that it does not hit said surface in the detection area, said emitters and receivers being disposed in an alternating and regular arrangement, the method further comprising;

a step during which one of said receiver measures the quantity of light reflected by the obiect when the object is illuminated by one of said emitters for at least two different emitter—

receiver pairs,

a step of calculating at least two characteristic values from said measured values, wherein, as emitters and receivers are disposed in the alternating and regular arrangement, a characteristic value is calculated for each receiver by averaging the values measured by that receiver when the emitters situated on each side of said receiver are turned on successively,

a step of determining at least one position of the obiect by directly reading a table indexed by said at least two

characteristic values, the content of said table being determined and set before said measurement step.

12. A method according to claim 11, wherein said measurement step is repeated for each of said emitter—

receiver pairs until a stable quantity of reflected light is measured.

13. A method according to claim 11, wherein said predetermined table is obtained by a polynomial regression method from a number of preliminary measurements effected under the same conditions as apply to said measurement step.

14. A method according to claim 11, wherein said surface is substantially plane, and wherein, during said preliminary step, there are disposed in a single line emitters and receivers of light having an emission axis, respectively a reception axis, substantially parallel to said particular detection area.

15. A method according to claim 11, wherein said detection area is rectangular and the emitters and receivers are disposed in the vicinity of only one side of said rectangular area.

16. A method according to claim 11, wherein the light emitted by the light emitters is ordinary non-coherent light.

17. A method according to claim 11, wherein said detection area comprises a set of elementary areas each associated with a given function so that any position of the object in an elementary area activates the function associated with that elementary area.

18. The use of a detection method according to claim 11 to detect the displacement of an object or to measure the speed of displacement of an object.

19. An optical detection device for determining the position of an object on a particular detection area of a surface, said device comprising, disposed in the vicinity of said particular area, and on the same side thereof with respect to the object, at least four elements including:

at least two emitters of light adapted to emit light so that it does not hit said surface in the detection area, and

at least two receivers one receiver of light adapted to cover said detection area and to measure a value representative of the quantity of light reflected by the object,

said emitters and receivers being disposed in an alternating and regular arrangement,

said device further comprising control means for turning on said emitter and processor means adapted;

to obtain and store for at least two different emitter—

receiver pairs the quantity of light reflected by said object and measured by said receiver when the object is illuminated by said emitter,

to calculate at least two characteristic values from said measured values, wherein as emitters and receivers are disposed in the alternating and regular arrangement, a characteristic value is calculated for each emitter by averaging the values measured by the receivers on each side of said emitter when only said emitter is turned on, and

to determine at least one position of the object by directly reading a table indexed by said at least two characteristic values, the content of said table being predetermined and set before said step of obtaining the quantity of light reflected by said object.

20. A device according to claim 19, wherein, the processor means calculate a characteristic value for each emitter by calculating a function of the values measured by at least three receivers when only that emitter is turned on, the coefficients of this affine function being a function of the distance between each receiver and that emitter.

21. A device according to claim 19, wherein the processor means are adapted to repeat said measurement step for each of said emitter and receiver pairs until a stable quantity of reflected light is measured.

22. A device according to claim 19, wherein said predetermined table is obtained by a polynomial regression method from a number of preliminary measurements effected under the same conditions as apply to said measurement.

23. A device according to claim 19, wherein said surface is substantially plane, and wherein said emitters and receivers are disposed in a single line and have respective light emission and reception axes substantially parallel to said particular detection area.

24. A device according to claim 19, wherein said detection area is rectangular and the emitters and receivers are disposed in the vicinity of only one side of said rectangular area.

25. A device according to claim 19, wherein the light emitted by the light emitters is ordinary non-coherent light.

26. A device according to claim 25, wherein the wavelength of the light emitted is in one of the following ranges of wavelengths:

UV, visible, infrared.

27. A device according to claim 19, wherein said particular area comprises a set of elementary areas each associated with a given function so that any position of the object in an elementary area activates the function associated with that elementary area.

28. A device according to claim 27, wherein said particular area corresponds to an input area and each of the elementary areas corresponds to a key.

29. A data input terminal including a device according to claim 19.

30. The use of a detection device according to claim 19 to detect the displacement of an object or to measure the speed of displacement of an object.

31. An optical detection device for determining the position of an object on a particular detection area of a surface, said device comprising, disposed in the vicinity of said particular area, and on the same side thereof with respect to the object, at least four elements including:

at least two emitter of light adapted to emit light so that it does not hit said surface in the detection area, and

at least two receivers of light adapted to cover said detection area and to measure a value representative of the guantity of light reflected by the obiect,

said emitters and receivers being disposed in an alternating and regular arrangement,

said device further comprising control means for turning on said emitter and processor means adapted;

to obtain and store for at least two different emitter—

receiver pairs the quantity of light reflected by said obiect and measured by said receiver when the object is illuminated by said emitter,

to calculate at least two characteristic values from said measured values, wherein as emitters and receivers are disposed in an alternating and regular arrangement, a characteristic value is calculated for each receiver by averaging the values measured by that receiver when the emitters situated on each side of said receiver are turned on successively, and

to determine at least one position of the obiect by directly reading a table indexed by said at least two characteristic values, the content of said table being predetermined and set before said step of obtaining the guantity of light reflected by said obiect.

32. A device according to claim 31, wherein the processor means are adapted to repeat said measurement step for each of said emitter and receiver pairs until a stable quantity of reflected light is measured.

33. A device according to claim 31, wherein said predetermined table is obtained by a polynomial regression method from a number of preliminary measurements effected under the same conditions as apply to said measurement.

34. A device according to claim 31, wherein said surface is substantially plane, and wherein said emitters and receivers are disposed in a single line and have respective light emission and reception axes substantially parallel to said particular detection area.

35. A device according to claim 31, wherein said detection area is rectangular and the emitters and receivers are disposed in the vicinity of only one side of said rectangular area.

36. A device according to claim 31, wherein the light emitted by the light emitters is ordinary non-coherent light.

37. A device according to claim 31, wherein said particular area comprises a set of elementary areas each associated with a given function so that any position of the object in an elementary area activates the function associated with that elementary area.

38. A data input terminal including a device according to claim 31.

39. The use of a detection device according to claim 31 to detect the displacement of an object or to measure the speed of displacement of an object.