Two-Dimensional Position Sensing Systems and Sensors Therefor

• US 20120261548A1
• Filed: 12/16/2011
• Published: 10/18/2012
• Est. Priority Date: 06/16/2009
• Status: Active Grant

• Current Assignee: Avanindra Utukuri, Jonathan Clarke, Stephen Mcfadyen
• Original Assignee: Avanindra Utukuri, Jonathan Clarke, Stephen Mcfadyen
• Inventors: Utukuri, Avanindra, Clarke, Jonathan, McFadyen, Stephen
• Granted Patent: US 8,969,769 B2
• Time in Patent Office: Days
• US Class Current: 250/206.1
• CPC Class Codes: G01D 5/34 the beams of light being detected by photocells
• CPC Class Codes: G01S 3/784 using a mosaic of detectors
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06F 3/03542 Light pens for emitting or receiving light
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

Two dimensional position sensing system and sensors for use in such systems are disclosed. The sensors incorporate linear array sensors having sensor elements and an aperture plate. Some embodiments include a radiation source that directs radiation onto some of the sensor elements. Other embodiments including radiation blocking objects that block radiation from reaching some of sensor elements. The direction or position of the radiation source or radiation blocking object may be estimated from the radiation incident on the sensor elements.

Claims

1-26. -26. (canceled)

27. A method of estimating the position of a radiation source relative to a sensing region, the method comprising:

positioning a first position sensor in a first position relative to the sensing region, wherein the first position sensor comprises;

a first linear array sensor having a plurality of first sensor elements, the first sensor elements facing the sensing region;

a first aperture plate positioned between the first linear array sensor and the sensing region to block radiation from the sensing region from reaching the first linear array sensor;

a first aperture formed in the first aperture plate to allow radiation from the radiation source to reach at least one of the first sensor elements;

positioning a second position sensor in a second position relative to the plane, wherein the first and second position sensors are separated by a distance, wherein the second position sensor comprises;

a second linear array sensor having a plurality of second sensor elements, the second sensor elements facing the sensing region;

a second aperture plate positioned between the second linear array sensor and the sensing region to block radiation from the sensing region from reaching the second linear array sensor;

a second aperture formed in the second aperture plate to allow radiation from the radiation source to reach at least one of the second sensor elements;

receiving a first radiation intensity signal from the first linear array sensor, wherein the first intensity signal includes intensity value corresponding to radiation incident on the first sensor elements through the first aperture;

determining a first ray relative to first position sensor based on the first intensity signal;

receiving a second radiation intensity signal from the second linear array sensor, wherein the second intensity signal includes intensity value corresponding to radiation incident on the second sensor elements through the second aperture;

determining a second ray relative to the second position sensor based on the second intensity signal; and

estimating the position of the radiation source to be at the intersection of the first and second rays.

28. The method of claim 27 wherein the sensing region is a surface of a display screen.

29. The method of claim 27 wherein the sensing region is a surface of a writing surface.

30. The method of any claim 27 wherein the radiation source is an active radiation source that emits radiation detectable by the first and second position sensors.

31. The method of claim 27 wherein the radiation source is a passive reflective radiation and further including providing one or more active radiation sources in a fixed position, and wherein the passive radiation source reflects radiation from the active radiation sources onto the first and second position sensors.

32. The method of claim 27 wherein the first radiation intensity signal includes at least one first signal high intensity value exceeding a first threshold value, and wherein the first ray is determined based on the at least one first signal high intensity value.

33. The method of claim 27 wherein the second radiation intensity signal includes at least one second signal high intensity value exceeding a second threshold value, and wherein the second ray is determined based on the at least one second signal high intensity value.

34. The method of claim 27 wherein the first radiation intensity signal includes a first range of high intensity values exceeding a first threshold value, and wherein determining the first ray includes:

selecting a first center sensor element based on the first range of high intensity values; and

determining the first ray based on the first center sensor element.

35. The method of claim 27 wherein the second radiation intensity signal includes a second range of high intensity values exceeding a second threshold value, and wherein determining the second ray includes:

selecting a second center sensor element based on the second range of high intensity values; and

determining the second ray based on the second center sensor element.

36. The method of claim 27 wherein the first radiation intensity signal includes at least one first signal low intensity value below a first threshold value, and wherein the first ray is determined based on the at least one first signal low intensity value.

37. The method of claim 27 wherein the second radiation intensity signal includes at least one second signal low intensity value below a second threshold value, and wherein the second ray is determined based on the at least one second signal low intensity value.

38. The method of claim 27 wherein the first radiation intensity signal includes a first range of low intensity values below a first threshold value, and wherein determining the first ray includes:

selecting a first center sensor element based on the first range of low intensity values; and

determining the first ray based on the first center sensor element.

39. The method of claim 27 wherein the second radiation intensity signal includes a second range of low intensity values below a second threshold value, and wherein determining the second ray includes:

selecting a second center sensor element based on the second second range of low intensity values; and

determining the second ray based on the second center sensor element.

40. The method of claim 27 wherein the first radiation intensity signal is a first analog radiation intensity signal and wherein determining the first ray includes:

converting the first analog radiation intensity signal into a corresponding first final radiation intensity; and

determining the first ray based on the first final radiation intensity signal.

41. The method of claim 27 wherein the second radiation intensity signal is a second analog radiation intensity signal and wherein determining the second ray includes:

converting the second analog radiation intensity signal into a corresponding second final radiation intensity; and

determining the second ray based on the second final radiation intensity signal.

42. The method of claim 27 wherein the first radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the first sensor elements and wherein determining the first ray includes:

selecting a first center sensor element based on a first range of high intensity values; and

determining the first ray direction based on the first center sensor element.

43. The method of claim 27 wherein the second radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the second sensor elements and wherein determining the second ray includes:

selecting a second center sensor element based on a second range of high intensity values; and

determining the second ray direction based on the second center sensor element.

44. The method of claim 27 wherein the first radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the first sensor elements and wherein determining the first ray includes:

selecting a first center sensor element based on a first range of low intensity values; and

determining the first ray direction based on the first center sensor element.

45. The method of claim 27 wherein the second radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the second sensor elements and wherein determining the second ray includes:

selecting a second center sensor element based on a second range of low intensity values; and

determining the second ray direction based on the second center sensor element.

46. The method of claim 27 including filtering the radiation intensity signal to remove spurious values before determining first ray.

47. The method of claim 27 including filtering the radiation intensity signal to remove spurious values before determining second ray.

48. The method of claim 27 wherein determining the first ray includes looking up an angle in a first lookup table.

49. The method of claim 27 wherein determining the second ray includes looking up an angle in a second lookup table.

50. The method of claim 27 wherein determining the first ray includes calculating an angle.

51. The method of claim 27 wherein determining the second ray includes calculating an angle.