System and method for the measurement of stretch film

Abstract

A system for determining an amount of stretch film unwound from a stretch film dispensing apparatus. The stretch film dispensing apparatus includes a roller, from which the stretch film can be unwound, at least one supply roll sensor positioned relative to the roller to sense a distance from the at least one supply roll sensor to an outside face of a supply roll on a core on the roller, and a controller. The controller is configured to determine the amount of stretch film unwound based on the one or more signals provided by the at least one supply roll sensor.

What is claimed is: 
     
         1 . A system for determining an amount of stretch film unwound from a stretch film dispensing apparatus wherein stretch film is unwound from a supply role on a roller that rotates on a longitudinal axis, the system comprising:
 at least one supply roll sensor positioned relative to a roller in the stretch film dispensing apparatus to sense a distance from the at least one supply roll sensor to an outside face of a supply roll on a core on the roller;   a controller connected to the at least one supply roll sensor; and   a core sensor positioned relative to the roller to sense a core distance from the core sensor to an outside face of the core and configured to send a signal representative of the core distance to the controller;   wherein the at least one supply roll sensor is configured to take a first measure of the distance and, after stretch film is unwound from the supply roll, take a second measure of the distance, and send signals representative of the first and second measures of the distance to the controller; and   wherein the controller is configured to determine the amount of stretch film unwound based on signals representative of at least one of the first or second measure, and the core distance.   
     
     
         2 . The system of  claim 1 , wherein the at least one supply roll sensor is one of an optical sensor or a sonic sensor. 
     
     
         3 . The system of  claim 1 , wherein the core sensor is one of an optical sensor or a sonic sensor. 
     
     
         4 . The system of  claim 1 , further comprising a rotation sensor positioned to sense a number of rotations of the core, and send a signal representative of the number of rotations to the controller, and the controller is configured to determine the amount of stretch film unwound based also on the number of rotations. 
     
     
         5 . The system of  claim 4 , wherein the rotation sensor is one of an optical sensor or a sonic sensor. 
     
     
         6 . The system of  claim 1 , wherein the controller is configured to obtain data about a thickness of the stretch film on the supply roll and the controller is configured to determine the amount of stretch film unwound based also on the data. 
     
     
         7 . The system of  claim 6 , wherein the controller is configured to obtain the data from one of a remote server, a local server, an input, a barcode on the stretch film, an image or graphic on the stretch film, a barcode on the supply roll packaging, a barcode on the core, a look-up table, or a color or numeric indicator. 
     
     
         8 . The system of  claim 1 , wherein the at least one supply roll sensor is positioned to sense the distance from a lower portion of the outside face of the supply roll. 
     
     
         9 . The system of  claim 1 , further comprising an indicator coupled to the controller to provide an indication of the amount of stretch film unwound. 
     
     
         10 . A method of measuring an amount of stretch film unwound from a core of a supply roll about a longitudinal axis, the method comprising:
 measuring at least one of a first distance from at least one point radially away from the supply roll to an outside face of the supply roll or a second distance from the at least one point radially away from the supply roll to the outside face of the supply roll after stretch film has been unwound from the supply roll;   measuring at a third distance from at least one point radially away from the supply roll to an outside face of the core; and   determining an amount of stretch film unwound from the supply roll based on the at least one of the first and second distances, and the third distance.   
     
     
         11 . The method of  claim 10 , further comprising sensing a number of rotations of the core and determining an amount of stretch film unwound from the supply roll based also on the number of rotations. 
     
     
         12 . The method of  claim 10 , further comprising indicating when the determined amount of stretch film unwound from the supply roll is at a predetermined threshold. 
     
     
         13 . The method of  claim 10 , wherein the measuring is done with one of an optical sensor or sonic sensor. 
     
     
         14 . The method of  claim 10 , wherein the determining is based also on a thickness of the stretch film on the supply roll. 
     
     
         15 . The method of  claim 10 , wherein the measuring and the determining of the amount of stretch film unwound from the supply roll is done contemporaneously. 
     
     
         16 . The method of  claim 10 , wherein the measuring comprises measuring the first distance and the second distance, and the determining of the amount of stretch film unwound from the supply roll is based on the first distance, the second distance, and the core distance.