Non-contact sensing system

Abstract

A non-contact sensing system for detecting a double feed condition of mail. The non-contact sensing system generally includes a mail sorting machine that routes and moves the mail, a non-contact sensor, and a controller. The non-contact sensor is positioned proximate to the conveyor and generates a signal that is indicative of the thickness of the mail. The controller receives the signal from the non-contact sensor and generates an output signal that indicates a double feed condition.

1 . A non-contact sensing system for detecting a double feed condition of mail pieces, the non-contact sensing system comprising:
 a mail sorting machine having at least one conveyor configured to move the mail;   a non-contact sensor positioned near the conveyor and configured to generate a signal indicative of a thickness of the mail being moved by the at least one conveyor; and   a controller configured to receive the signal from the non-contact sensor and generate an output signal indicative of a double feed condition.   
   
   
       2 . The non-contact sensing system of  claim 1 , wherein the non-contact sensor is an optical sensor. 
   
   
       3 . The non-contact sensing system of  claim 1 , wherein the non-contact sensor is a laser sensor. 
   
   
       4 . The non-contact sensing system of  claim 1 , wherein the non-contact sensor is a reflective sensor. 
   
   
       5 . The non-contact sensing system of  claim 1 , further comprising a second sensor configured to generate a second signal indicative of a leading edge of a mail piece. 
   
   
       6 . The non-contact sensing system of  claim 5 , wherein the controller is configured to receive the second signal from the second sensor and initialize the non-contact sensor in response to the receipt of the second signal. 
   
   
       7 . The non-contact sensing system of  claim 1 , wherein the controller is configured to generate a thickness profile, and the output signal is at least partially based on the thickness profile. 
   
   
       8 . The non-contact sensing system of  claim 7 , wherein the thickness profile includes at least one thickness delta value, the thickness delta value corresponding to a change in thickness. 
   
   
       9 . The non-contact sensing system of  claim 7 , wherein the thickness profile includes an add-on value, the add-on value based at least partially on an expected mail overlapping amount. 
   
   
       10 . A method of calculating the likelihood of a double feed condition of mail, the method comprising:
 generating a thickness profile for the mail;   comparing the thickness profile of the mail to a historical thickness profile, the historical thickness profile at least partially based on a previously generated thickness profile; and   calculating a confidence value associated with the likelihood of a double feed condition, the confidence value at least partially based on the comparison of the thickness profile to the historical thickness profile.   
   
   
       11 . The method of  claim 10 , further comprising temporarily recording the thickness profile. 
   
   
       12 . The method of  claim 11 , further comprising creating the historical thickness profile after comparing and matching a number of recorded thickness profiles. 
   
   
       13 . The method of  claim 10 , further comprising generating an expected double feed profile, the expected double feed profile based at least partially on a comparison between the length of the thickness profile and the length of the historical thickness profile. 
   
   
       14 . The method of  claim 13 , wherein generating the expected double feed profile comprises
 measuring the thickness and length of potentially overlapping pieces of mail with a non-contact sensor;   generating a historical length based at least partially on a previously measured lengths of mail;   calculating an offset value between the potentially overlapping pieces of mail, the offset value based at least partially on the historical length; and   generating a thickness profile of the potentially overlapping pieces of mail based at least partially on the offset value.   
   
   
       15 . The method of  claim 13 , further comprising generating the confidence value based at least partially on the comparison of the thickness profile and the expected double feed thickness profile. 
   
   
       16 . A method of calculating the likelihood of a double feed condition of mail, the method comprising:
 generating a thickness profile of the mail;   identifying a first distinct thickness and a second distinct thickness in the generated thickness profile of the mail, wherein a first transition between the first distinct thickness and the second distinct thickness is assigned a first position value; and   identifying a double feed condition based at lest partially in response to the detection of a second position value at a second transition between the first thickness and the second thickness.   
   
   
       17 . The method of  claim 16 , further comprising relating the first position value and the second position value to a first piece of mail and a second piece of mail. 
   
   
       18 . The method of  claim 17 , further comprising calculating the length of the first piece of mail and the length of the second piece of mail based at least partially on the first position value and the second position value. 
   
   
       19 . The method of  claim 18 , further comprising verifying the length of the first piece of mail and the length of the second piece of mail are greater than a minimum length. 
   
   
       20 . The method of  claim 18 , further comprising identifying a double feed condition based on the calculated length of the first piece of mail and the calculated length of the second piece of mail.