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 .- 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;   selecting a first center sensor element based on the first intensity signal;   determining a first ray relative to first position sensor based on the first center sensor element;   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;   selecting a second center sensor element based on the second intensity signal;   determining a second ray relative to the second position sensor based on the second center sensor element; 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  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 source and further including providing one or more active radiation sources in a fixed position, and wherein the passive reflective 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 the first center sensor element based on the first range of high intensity values. 
 
     
     
         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 the second center sensor element based on the second range of high intensity values. 
 
     
     
         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 the first center sensor element based on the first range of low intensity values. 
 
     
     
         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 the second center sensor element based on the second range of low intensity values. 
 
     
     
         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 
 selecting the first center sensor element 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 
 selecting the second center sensor element 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 the first center sensor element based on a first range of high intensity values. 
 
     
     
         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 the second center sensor element based on a second range of high intensity values. 
 
     
     
         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 the first center sensor element based on a first range of low intensity values. 
 
     
     
         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 the second center sensor element based on a second range of low intensity values. 
 
     
     
         46 . The method of  claim 27  including filtering the radiation intensity signal to remove spurious values before determining the first ray and before determining the second ray.