Two-Dimensional Position Sensing Systems and Sensors Therefor

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.

1 . A method of estimating the direction of a radiation source positioned in a sensing region, the method comprising:
 providing a radiation sensor, the radiation sensor comprising:   a linear array sensor having a plurality of sensor elements, the sensor elements facing the sensing region;   an aperture plate positioned between the linear array sensor and the sensing region to block radiation from the sensing region from reach the linear array sensor; and   an aperture formed in the aperture plate to allow radiation from the radiation source to reach some of the sensor elements;   receiving an intensity signal from the linear array sensor, wherein the intensity signal includes intensity values corresponding to radiation incident on the sensor elements through the aperture; and   determining the direction based on the intensity signal.   
     
     
         2 . The method of  claim 1  wherein the radiation intensity signal includes at least one high intensity value exceeding a threshold value, and wherein the direction is determined based on the at least one high intensity value. 
     
     
         3 . The method of  claim 1  wherein the radiation intensity signal includes a range of high intensity values exceeding a threshold value, and wherein determining the direction includes:
 selecting a center sensor element based on the range of high intensity values; and 
 determining a direction based on the center sensor element. 
 
     
     
         4 . The method of  claim 1  wherein the radiation intensity signal includes at least one low intensity value below a threshold value, and wherein the direction is determined based on the at least one low intensity value. 
     
     
         5 . The method of  claim 1  wherein the radiation intensity signal includes a range of low intensity values below a threshold value, and wherein determining the direction includes:
 selecting a center sensor element based on the range of low intensity values; and 
 determining a direction based on the center sensor element. 
 
     
     
         6 . The method of  claim 1  wherein the radiation intensity signal is an analog signal and wherein determining the direction includes:
 converting the analog radiation intensity signal into a corresponding final radiation intensity; and 
 determining a direction based on the final radiation intensity signal. 
 
     
     
         7 . The method of  claim 6  wherein the radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the sensor elements and wherein determining the direction includes:
 selecting a center sensor element based on a range of high intensity values; and 
 determining a direction based on the center sensor element. 
 
     
     
         8 . The method of  claim 6  wherein the radiation intensity signal is a digital signal having either a high value or a low value corresponding to each of the sensor elements and wherein determining the direction includes:
 selecting a center sensor element based on a range of low intensity values; and 
 determining a direction based on the center sensor element. 
 
     
     
         9 . The method of  claim 1  including filtering the radiation intensity signal to remove spurious values before determining the direction. 
     
     
         10 . The method of  claim 1  wherein determining the direction includes looking up an angle in a lookup table. 
     
     
         11 . The method of  claim 1  wherein determining the direction includes calculating an angle. 
     
     
         12 . 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;   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;   determining a first ray relative to first position sensor;   determining a second ray relative to the second position sensor; and   estimating the position of the radiation source to be at the intersection of the first and second rays.   
     
     
         13 . The method of  claim 12  wherein the sensing region is a surface of a display screen. 
     
     
         14 . The method of  claim 12  wherein the sensing region is a surface of a writing surface. 
     
     
         15 . The method of  claim 12  wherein the radiation source is an active radiation source that emits radiation detectable by the first and second position sensors. 
     
     
         16 . The method of  claim 12  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. 
     
     
         17 . The method of  claim 12  wherein the sensing region is a surface of a display screen. 
     
     
         18 . The method of  claim 12  wherein the sensing region is a surface of a writing surface. 
     
     
         19 . A method of estimating the position of a radiation source relative to a sensing region, the method comprising:
 providing a plurality of active radiation sources adjacent the sensing region;   positioning a first position sensor in a first position relative to the sensing region wherein radiation emitted by at least some of the radiation sources is incident upon the first radiation sensor;   positioning a second position sensor in a second position relative to the plane wherein radiation emitted by at least some of the radiation sources is incident upon the second radiation sensor, and wherein the first and second position sensors are separated by a distance;   determining a first ray relative to first position sensor;   determining a second ray relative to the second position sensor; and   estimating the position of the radiation source to be at the intersection of the first and second rays.   
     
     
         20 . The method of  claim 19  wherein radiation from a first group of active radiation sources is blocked from reaching the first position sensor and radiation from a second group of radiation sources is blocked from reaching the second radiation sensor and wherein the first ray corresponds to the first group and the second ray corresponds to the second group. 
     
     
         21 .- 26 . (canceled)