Method and device for tracking relative movement by correlating signals from an array of photoelements

A device for tracking relative movement between said device and a region of interest, the device comprising:

• a navigation sensor having a two-dimensional array of photoelements responsive to reception of light energy to define an array field of view;
• first circuit means for deriving a sequence of frames of signals in which each signal in each frame of said sequence is indicative of light energy from said region of interest received at an individual photoelement at a specific time, said each frame thereby being indicative of features within said region of interest when said region of interest is in said array field of view, said first circuit means outputting said signals, each of said signals corresponding to one photoelement of said array;
• and
• second circuit means, connected to said first circuit means, for correlating first and second frames of said sequence of frames of signals that are output from said first circuit means to determine displacement of said features within said region of interest during a time period between deriving said first and second frames, said second circuit means including an array of correlation signal-generating circuits in one-to-one correspondence with said signals, each correlation-signal generating circuit receiving from said first frame the signal corresponding to an individual photoelement of said array and additionally being selectively connectable to receive from said second frame the signals corresponding to other photoelements immediately adjacent to said individual photoelement in said array, each correlation-signal generating circuit generating a correlation signal output responsive to said signal from said first frame and to said signals from said second frame, said correlation signal outputs being indicative of correlations between light energy received at said individual photoelement for deriving said first frame and light energy received at said other photoelements for deriving said second frame, thereby enabling said determination of displacement of said features.

A method of tracking movement of a scanner device relative to a surface of interest to form an image of said surface, the method comprising steps of:

• fixing an image sensor to said scanner device;
• fixing a two-dimensional array of photoelements to said scanner device, each of said photoelements in said array having plural nearest-neighbor photoelements adjacent thereto;
• forming first image information of said surface of interest using said image sensor;
• forming second image information of said surface of interest using said array of photoelements;
• assembling an image of said surface of interest from said first image information, including positioning said first image information based on said second image information, including substeps of:
• (a) correlating patterns of surface reflectivity detected by said array of photoelements at a first specific time and a second specific time, including generating plural correlation outputs for each photoelement, said correlation outputs being responsive to light energy received at said each photoelement at said first specific time and light energy received at said nearest-neighbor photoelements of each said photoelement at said second specific time, and
• (b) based on said patterns of surface reflectivity correlated in substep (a), determining a magnitude and direction of travel of said scanning device relative to said surface of interest.

A scanner for forming an image of a surface of interest comprising:

• a housing;
• an imaging sensor fixed to said housing for capturing image information of said surface of interest;
• a two-dimensional array of photoelements fixed to said housing for forming navigation information, each photoelement in said array having at least one nearest-neighbor photoelement adjacent to said each photoelement;
• frame means for capturing successive frames of said navigation information from said photoelements in an arrangement such that each frame includes pixel values in which each pixel value is responsive to received light energy at a corresponding photoelement at a time of capturing said each frame;
• means, connected to said frame means, for correlating each pixel value of a first frame with those pixel values of a second frame that correspond to nearest-neighbor photoelements of a photoelement with which said each pixel value corresponds.