초록 ▼

A data input device for use with a tracking surface having light-scattering properties with respect to the device. The device comprising a single laser having a modulated light beam. A beam splitter splits the modulated light beam into two light beams projected along separate paths toward the tracki

A data input device for use with a tracking surface having light-scattering properties with respect to the device. The device comprising a single laser having a modulated light beam. A beam splitter splits the modulated light beam into two light beams projected along separate paths toward the tracking surface. A portion of the light striking the tracking surface reflects back into a cavity of the single laser for self-mixing with the projected light, thereby altering first and second characteristics of the projected modulated light beam according to first and second directions associated with the tracking surface. A detector associated with the laser detects the altered first and second characteristics of the modulated light beam projected by the laser, and a controller responsive to the detector determines the relative movement of the tracking surface and data input device relative to one another as a function of the altered first and second characteristics detected by the detector.

대표청구항 ▼

What is claimed is: 1. A data input device for use with a tracking surface, said tracking surface having light-scattering properties with respect to said device, said device comprising: a single laser having a cavity from which a light beam is projected; a light beam modulator for modulating the fr

What is claimed is: 1. A data input device for use with a tracking surface, said tracking surface having light-scattering properties with respect to said device, said device comprising: a single laser having a cavity from which a light beam is projected; a light beam modulator for modulating the frequency of the light beam over time; a beam splitter for splitting the modulated light beam into a first modulated light beam and a second modulated light beam; said beam splitter being configured to project the first modulated light beam onto said tracking surface along a first light path, at least a portion of the first modulated light beam striking said tracking surface and reflecting back into the cavity of said laser along said first light path and thereby altering at least one first characteristic of the projected modulated light beam, said beam splitter further being configured to project the second modulated light beam onto said tracking surface along a second light path, at least a portion of the second modulated light beam striking said tracking surface and reflecting back into the cavity of said laser along said second light path and thereby altering at least one second characteristic of the projected modulated light beam; a detector associated with the laser for detecting said altered first and second characteristics of the modulated light beam projected by the laser; and a controller responsive to the detector for determining the relative movement of the tracking surface and data input device relative to one another as a function of the altered first and second characteristics detected by the detector. 2. A device as set forth in claim 1 wherein said first modulated light beam travels a first distance between said beam splitter and said tracking surface and said second modulated light beam travels a second distance between said beam splitter and said tracking surface. 3. A device as set forth in claim 2 wherein said first and second distances are different from one another. 4. A device as set forth in claim 3 wherein said first distance is at least 1.2 times the second distance. 5. A device as set forth in claim 4 wherein said first distance is in a range from about 1.2 times to about 1.8 times the second distance. 6. A device as set forth in claim 5 wherein said first distance is in a range from about 1.4 times to about 1.6 times the second distance. 7. A device as set forth in claim 6 wherein said first distance is in a range from about 1.45 times to about 1.55 times the second distance. 8. A device as set forth in claim 2 further comprising a multi-reflection cell for increasing at least one of said first and second distances. 9. A device as set forth in claim 1 wherein said light beam modulator modulates said light beam in a time-based pattern. 10. A device as set forth in claim 9 wherein said time-based pattern comprises a triangular time-based pattern. 11. A device as set forth in claim 1 wherein said light beam modulator comprises a current modulator for modulating the current supplied to the laser. 12. A device as set forth in claim 11 wherein said current modulator modulates said current in a triangular pattern. 13. A device as set forth in claim 1 wherein said single laser comprises at least one of an edge-emitting laser (EEL) and a vertical cavity surface emitting laser (VCSEL). 14. A device as set forth in claim 1 wherein said beam splitter comprises at least two fiber optic strands, a first fiber optic strand carrying said first modulated light beam and a second fiber optic strand carrying said second modulated light beam. 15. A device as set forth in claim 14 further comprising an optic positioned between the fiber optic strands and the tracking surface for refracting the first and second modulated light beams between the tracking surface and the fiber optic strands. 16. A device as set forth in claim 1 wherein said first modulated light beam strikes said tracking surface at an azimuth angle relative to said second modulated light beam. 17. A device as set forth in claim 16 wherein said azimuth angle is between about 1.05 radians (60 degrees) and about 2.09 radians (120 degrees). 18. A device as set forth in claim 17 wherein said azimuth angle is about 1.57 radians (90 degrees). 19. A device as set forth in claim 1 wherein at least one of said first and second modulated light beams strikes said tracking surface at an elevation angle between about 0.17 radian (10 degrees) and about 1. 40 radians (80 degrees). 20. A device as set forth in claim 19 wherein said elevation angle is between about 0.35 radian (20 degrees) and about 1.05 radians (60 degrees). 21. A device as set forth in claim 20 wherein said elevation angle is between about 0.35 radian (20 degrees) and about 0.79 radian (45 degrees). 22. A device as set forth in claim 21 wherein said elevation angle is about 0.52 radian (30 degrees). 23. A device as set forth in claim 1 wherein said first and second altered characteristics comprise frequency shifts in a Doppler waveform of the projected modulated light beam of the laser. 24. A device as set forth in claim 23 further comprising a first filter for filtering the Doppler waveform of the projected modulated light beam to filter out the frequency shifts corresponding to the second altered characteristic of the modulated light beam projected by the laser, thereby revealing a first filtered Doppler waveform of the first altered characteristic. 25. A device as set forth in claim 24 further comprising a second filter for filtering the Doppler waveform of the projected modulated light beam to filter out the frequency shifts corresponding to the first altered characteristic of the modulated light beam projected by the laser, thereby revealing a second filtered Doppler waveform of the second altered characteristic. 26. A device as set forth in claim 25 wherein said first filtered Doppler waveform has a frequency related to the speed of any relative displacement between the tracking surface and the device in an azimuth direction generally along a first axis corresponding to the axis of said first modulated light beam as it strikes said tracking surface, and said second filtered Doppler waveform has a frequency related to the speed of any relative displacement between the tracking surface and the device in an azimuth direction generally along a second axis corresponding to the axis of said second modulated light beam as it strikes said tracking surface. 27. A device as set forth in claim 26 wherein as the modulated frequency of the modulated light beam increases over time, the respective first and second filtered Doppler waveforms of said projected modulated light beam each exhibit a positive modulation signal frequency, and as the modulated frequency of the modulated light beam decreases over time, the respective first and second filtered Doppler waveforms of said projected modulated light beam each exhibit a negative modulation signal frequency, wherein a positive modulation signal frequency of one of said filtered Doppler waveforms greater than a negative modulation signal frequency of said one of said filtered Doppler waveforms indicates that the tracking surface and the device are moving in a positive direction relative one another in an azimuth direction generally along said axis corresponding to said one filtered Doppler waveform of said respective first and second beams, and wherein a positive modulation signal frequency of one of said filtered Doppler waveforms smaller than a negative modulation signal frequency of said one of said filtered Doppler waveforms indicates that the tracking surface and the device are moving in a negative direction relative one another in an azimuth direction generally along said axis corresponding to said one filtered Doppler waveform of said respective first and second beams. 28. A device as set forth in claim 27 wherein said positive and negative modulation signal frequencies are related to the speed of the relative movement between the tracking surface and the device along each respective axis. 29. A device as set forth in claim 1 further comprising a housing, said single laser, beam splitter, detector, and controller being associated with said housing. 30. A device as set forth in claim 29 wherein said housing is adapted to contact said tracking surface. 31. A device as set forth in claim 1 wherein said tracking surface comprises human skin. 32. A device as set forth in claim 1 wherein the detector associated with the laser monitors intensity of the laser. 33. A method of tracking relative movement on a tracking surface having light scattering properties, said method comprising: modulating the frequency of a light beam over time, said light beam being projected from a single laser cavity; splitting the modulated light beam into a first modulated light beam and a second modulated light beam; projecting the first modulated light beam onto said tracking surface along a first light path; projecting the second modulated light beam onto said tracking surface along a second light path; receiving at least a portion of the first modulated light beam reflected by the tracking surface along the first light path within the laser cavity; receiving at least a portion of the second modulated light beam reflected by the tracking surface along the second light path within the laser cavity; mixing said received reflected light portions with light generated within said laser cavity, said mixing thereby altering at least one first characteristic of said projected modulated light beam due to said received reflected portion of the first modulated light beam and altering at least one second characteristic of said projected modulated light beam due to said received reflected portion of the second modulated light beam; projecting a modulated light beam with said at least one first and at least one second altered characteristics from said laser cavity; detecting said at least one first altered characteristic of the modulated light beam; detecting said at least one second altered characteristic of the modulated light beam; and determining movement of the tracking surface and the single laser cavity relative to one another as a function of the detected altered first and second characteristics. 34. The method as set forth in claim 33 further comprising altering data output of the data input device as a function of the determined relative movement. 35. The method as set forth in claim 33 wherein said detected at least one first and second altered characteristics of the modulated light beam comprise frequency. 36. The method as set forth in claim 33 wherein splitting the modulated light beam includes splitting the modulated light beam into the first modulated light beam, the second modulated light beam, and a third modulated light beam and further comprising: projecting the third modulated light beam onto said tracking surface along a third light path; receiving at least a portion of the third modulated light beam reflected by the tracking surface along the third light path within the laser cavity; mixing said received reflected light portions with light generated within said laser cavity, said mixing thereby altering at least one third characteristic of said projected modulated light beam due to said received reflected portion of the third modulated light beam; detecting said at least one third altered characteristic of the modulated light beam; and determining the relative movement of the tracking surface and the single laser cavity relatively toward or away from one another as a function of the detected altered first, second, and third characteristics. 37. The method as set forth in claim 36 further comprising determining the spatial separation between the tracking surface and the single laser cavity. 38. The method as set forth in claim 37 wherein the single laser cavity is housed in a data input device and further comprising (i) suspending tracking of relative movement between said device and said tracking surface when said device is spatially separated from said tracking surface by at least a lift-off detection distance and (ii) maintaining tracking of relative movement between said device and said tracking surface when said device is spatially separated from said tracking surface by less than said lift-off detection distance.