Range finder

Abstract

A system and method for measuring a height of objects on a moving surface comprising providing a linear image sensor positioned transverse to a direction of travel of the moving surface, and at least one light source positioned collinear to the linear image sensor and proximate to an edge of the moving surface so that the light source projects a unique patterned light sequence across a width of the moving surface, detecting a transverse shift in a portion of the unique patterned light sequence with respect to the direction of travel of the moving surface as an object passes through the unique patterned light sequence, determining an amount of shift of the portion of the unique patterned light sequence, and determining a height of the object based on the portion of the unique patterned light sequence shift.

1 . A method for measuring a height of objects on a moving surface comprising:
 a. providing
 (i) a linear image sensor positioned transverse to a direction of travel of the moving surface, and 
 (ii) at least one light source positioned collinear to said linear image sensor and proximate to an edge of the moving surface so that said at least one light source projects a unique patterned light sequence across a width of the moving surface; 
   b. detecting a transverse shift in a portion of said unique patterned light sequence with respect to the direction of travel of the moving surface as an object passes through said unique patterned light sequence;   c. determining an amount of shift of said portion of said unique patterned light sequence; and   d. determining a height of the object based on said portion of said unique patterned light sequence shift.   
   
   
       2 . The method for measuring a height of objects on a moving surface of  claim 1 , said unique patterned light sequence comprising a series of light bars separated by non-lighted spaces. 
   
   
       3 . The method for measuring a height of objects on a moving surface of  claim 2 , said light bars and non-lighted spaces having at least two differing widths. 
   
   
       4 . The method for measuring a height of objects on a moving surface of  claim 3 , said light bars having at least two differing widths and said non-lighted spaces having at least two differing widths that also differ from said at least two differing light bar widths. 
   
   
       5 . The method for measuring a height of objects on a moving surface of  claim 2 , wherein said series of light bars and said non-lighted spaces define a plurality of words across the width of the moving surface. 
   
   
       6 . The method for measuring a height of objects on a moving surface of  claim 5 , wherein a width of said light bars are selected from approximately one and three pixels and a width of said non-lighted spaces are selected from approximately two and four pixels. 
   
   
       7 . The method for measuring a height of objects on a moving surface of  claim 5 , wherein the step of detecting a transverse shift further comprises:
 a. detecting edges of said light bars;   b. determining a sequence of said light bars and said non-lighted spaces; and   c. extracting at least one of said plurality of words based on said sequence of said light bars and said non-lighted spaces.   
   
   
       8 . The method for measuring a height of objects on a moving surface of  claim 7 , wherein the step of determining a height further comprises comparing said amount of shift of said at least one of said plurality of words to a predetermined location of said at least one of said plurality of words when the object is not present. 
   
   
       9 . The method for measuring a height of objects on a moving surface of  claim 1 , wherein said unique patterned light sequence is formed by a diffractive optical lens. 
   
   
       10 . The method for measuring a height of objects on a moving surface of  claim 1 , wherein said unique patterned light sequence is a T-bar sequence. 
   
   
       11 . The method for measuring a height of objects on a moving surface of  claim 2 , wherein said light bars and non-lighted spaces have a length in the direction of travel of the moveable surface of at least 3 pixels. 
   
   
       12 . The method for measuring a height of objects on a moving surface of  claim 2 , wherein the step of detecting said lighted bar edges further comprises the steps of
 a. detecting transitions from lighted bars to adjacent non-lighted spaces; and   b. using linear interpolation to determine the approximate pixel location of each of said transitions.   
   
   
       13 . A method for measuring a height of objects on a moving surface comprising:
 a. providing
 (i) a linear image sensor positioned transverse to a direction of travel of the moving surface, and 
 (ii) a first and second light source that project a unique sequence of lighted bars having differing widths and non-lighted spaces having differing widths across the width of the moving surface, wherein said first and second light sources are spaced apart from each other on opposite sides of the moving surface; 
   b. detecting a shift in a portion of said unique sequence of lighted bars and non-lighted spaces as an object passes through said unique light sequence;   c. determining an amount of shift of said portion of said unique light sequence; and   d. determining a height of the object based on said amount of shift of said portion of said unique light sequence.   
   
   
       14 . The method for measuring a height of objects on a moving surface of  claim 13 , wherein said first and said second light sources are alternately cycled on and off. 
   
   
       15 . The method for measuring a height of objects on a moving surface of  claim 13 , wherein said step of detecting a shift further comprises:
 a. detecting edges of said lighted bars;   b. determining a width of said detected lighted bars and respective adjacent non-lighted spaces; and   c. extracting at least one of a plurality of code words based on a sequence of said lighted bars and said non-lighted spaces, wherein said code word is defined by at least two lighted bars and two non-lighted spaces.   
   
   
       16 . The method for measuring a height of objects on a moving surface of  claim 13 , wherein a width of said light bars are selected from approximately one and three pixels and a width of said non-lighted spaces are selected from approximately two and four pixels. 
   
   
       17 . The method for measuring a height of objects on a moving surface of  claim 13 , wherein said light bars and non-lighted spaces have a length in the direction of travel of the moveable surface of at least 3 pixels. 
   
   
       18 . The method for measuring a height of objects on a moving surface of  claim 15 , wherein the step of detecting said lighted bar edges further comprises the steps of
 c. detecting transitions from lighted bars to adjacent non-lighted spaces; and   d. using linear interpolation to determine the approximate pixel location of each of said transitions.   
   
   
       19 . The method for measuring a height of objects on a moving surface of  claim 18 , wherein the step of determining a height further comprises comparing said amount of shift of said at least one of said plurality of words to a location of at least one of said plurality of words when the object is not present. 
   
   
       20 . A range finder for measuring the height of objects on a moving surface comprising:
 a. a linear image sensor positioned transverse to a direction of travel of the moving surface;   b. at least one light source positioned collinear to said linear image sensor and proximate to an edge of the moving surface, wherein said light source projects a unique sequence of light bars and respective adjacent non-lighted spaces across a width of the moving surface transverse to the direction of travel; and   c. a processor operatively connected to said linear image sensor and said at least one light source for calculating a height of the object as it passes through said unique sequence of lights bars and respective adjacent non-lighted spaces.   
   
   
       21 . The range finder of  claim 20 , said light bars having at least two differing widths and said non-lighted spaces having at least two differing widths that differ from said at least two differing light bar widths. 
   
   
       22 . The range finder of  claim 20 , wherein a series of light bars and adjacent non-lighted spaces together form a plurality of unique words. 
   
   
       23 . The range finder of  claim 20 , further comprising a second light source positioned collinear to said linear image sensor and said first light source proximate to an opposite edge of the moving surface. 
   
   
       24 . The range finder of  claim 21 , further comprising at least one diffractive optical element for forming said unique sequence of light bars and respective adjacent non-lighted spaces. 
   
   
       25 . The range finder of  claim 23 , wherein said first and said second light sources alternately illuminate said belt at a predetermined frequency.