Method and apparatus for automated filling of mail trays

Abstract

A mail tray filler includes a filling mechanism that is vertically movable to be lowered and lifted into and out of a mail tray. With the mechanism in the raised position an empty mail tray is moved into position to underneath the mechanism. The mechanism lowers a feeding arm down into the first mail tray to feed envelopes starting at a forward end of the mail tray. The apparatus detects a pack pressure of the envelopes. When the pack pressure exceeds a predetermined threshold, the relative position of the feed arm is moved towards a back end of the mail tray to make room for more envelopes. After the pack pressure is below the predetermined threshold feeding continues. When the tray is full, the feeding arm is lifted from the mail tray, and a next empty mail tray is advanced.

What is claimed is: 
     
         1 . A method for operating an automated mail tray filling mechanism, the tray filling mechanism being vertically movable to be lowered and lifted into and out of a mail tray, mail trays being moved on a mail tray transport beneath the mail tray filling mechanism, the method comprising:
 advancing an empty mail tray to underneath the tray filling mechanism;   lowering a feeding arm down into the first mail tray to a position at a forward end of the mail tray;   feeding envelopes from the mail tray filling mechanism into the mail tray through the lowered feeding arm;   detecting a pack pressure of envelopes in the mail tray on the lowered feeding arm and when the pack pressure exceeds a predetermined threshold moving the relative position of the feed arm towards a back end of the mail tray and resuming feeding envelopes after the pack pressure is below the predetermined threshold;   lifting the feeding arm from the mail tray when it is full; and   advancing a next empty mail tray to underneath the tray filling mechanism.   
     
     
         2 . The method of  claim 1  wherein the step of moving the relative position of the feed arm comprises moving the mail tray transport. 
     
     
         3 . The method of  claim 1  wherein the step of moving the relative position of the feed arm comprises moving the tray filling mechanism. 
     
     
         4 . The method of  claim 3  wherein the step of moving the relative position of the feed arm also comprises moving the mail tray transport. 
     
     
         5 . The method of  claim 1  including a step of selecting the predetermined threshold for the pack pressure to maintain a firm vertical envelope stack at a pressure less than pressure that would cause friction to prevent subsequent envelopes from sliding into the stack. 
     
     
         6 . The method of  claim 1  further including a step of detecting the back end of the mail tray and whereby the step of lifting the feeding arm is a function of such detection of the back end of the mail tray. 
     
     
         7 . The method of  claim 6  wherein the step of detecting includes receiving a signal from a mechanical switch that is depressed when it comes into contact with the back end of the mail tray. 
     
     
         8 . The method of  claim 6  wherein the step of detecting includes receiving a signal from an optical sensor that determines when the feeding arm is in proximity to the back end of the mail tray. 
     
     
         9 . The method of  claim 6  wherein the step of detecting includes computing a distance that the relative position of the feed arm has moved towards a back end of the mail tray and comparing the computed distance to a known length of the mail tray. 
     
     
         10 . The method of  claim 9  wherein the step of computing includes using one or more encoders to measure movement of the feed arm or mail tray transport. 
     
     
         11 . The method of  claim 1  including a further step concurrent with the steps for feeding envelopes, the further step comprising determining whether a repack interval has been reached and initiating a repack operation if the repack interval has been reached. 
     
     
         12 . The method of  claim 11  wherein the repack operation comprises moving the relative position of the feed arm towards a front end of the mail tray to compress a stack of envelopes already fed into the mail tray. 
     
     
         13 . The method of  claim 12  wherein the repack interval is initiated as a function of the feed arm having moved towards the back end of the mail tray by a predetermined distance. 
     
     
         14 . The method of  claim 12  wherein the repack interval is initiated as a function of a predetermined number of envelopes having been fed into the mail tray. 
     
     
         15 . The method of  claim 12  wherein the repack interval is based on observation of a predetermined pressure profile being sensed on the feeding arm from the stack of envelopes. 
     
     
         16 . The method of  claim 12  wherein the repacking step of moving the relative position of the feed arm towards the front end of the mail tray includes moving the feed arm by a predetermined distance. 
     
     
         17 . The method of  claim 12  wherein the repacking step of moving the relative position of the feed arm towards the front end of the mail tray includes moving the feed arm until a predetermined pressure is detected on the feed arm. 
     
     
         18 . The method of  claim 1  wherein when the pack pressure is less than a predetermined minimum threshold moving the relative position of the feed arm away from the back end of the mail tray and resuming feeding envelopes after the pack pressure is above the predetermined minimum threshold. 
     
     
         19 . The method of  claim 1  further including a step of determining that the mail tray is full by counting a quantity of envelopes fed into the tray and comparing the counted quantity to a predetermined tray capacity number. 
     
     
         20 . The method of  claim 19  further including a step of ignoring when the pack pressure exceeds the predetermined threshold in order to allow the mail tray to be filled fully to the predetermined tray capacity number when the mail tray is almost full. 
     
     
         21 . The method of  claim 1  further include a step of determining that the mail tray is full by scanning for an optical mark on a designated last envelope. 
     
     
         22 . The method of  claim 21  further including a step of determining that the mail tray is full by counting a quantity of envelopes fed into the tray and comparing the counted quantity to a predetermined tray capacity number, and overriding the step of scanning for the optical mark if the predetermined tray capacity number is met. 
     
     
         23 . An automated mail tray filling apparatus, the apparatus comprising
 a feeding arm that is vertically movable to be lowered and lifted into and out of a mail tray, the feeding arm further arranged to be movable in upstream and downstream directions parallel to a length of mail trays transported beneath feeding arm, the feeding arm having a mail pack pressure sensor positioned at the end of the feeding arm in contact with envelopes fed into the mail tray; and   a mail tray transport arranged to transport a series of mail trays beneath the feeding arm.   
     
     
         24 . The apparatus of  claim 23  further including an apparatus controller configured to perform the following steps:
 advancing an empty mail tray to underneath the feeding arm; 
 lowering the feeding arm down into the first mail tray to a position at a forward end of the mail tray; 
 feeding envelopes into the mail tray through the lowered feeding arm; 
 detecting a pack pressure of envelopes in the mail tray from the mail pack pressure sensor and when the pack pressure exceeds a predetermined threshold moving the relative position of the feed arm towards a back end of the mail tray and resuming feeding envelopes after the pack pressure is below the predetermined threshold; 
 lifting the feeding arm from the mail tray when it is full; and 
 advancing a next empty mail tray to underneath the tray filling mechanism. 
 
     
     
         25 . The apparatus of  claim 24  further including a sensor for detecting the back end of the mail tray and whereby apparatus controller is configured to cause the feeding arm to raise as a function of such detection of the back end of the mail tray. 
     
     
         26 . The apparatus of  claim 25  wherein the sensor comprises a mechanical switch positioned on a rear portion of the feeding arm such that is depressed when it comes into contact with the back end of the mail tray. 
     
     
         27 . The apparatus of  claim 25  wherein the sensor comprises an optical sensor positioned to detect the back end of the mail tray in proximity to the feeding arm. 
     
     
         28 . The apparatus of  claim 24  wherein the sensor is one or more encoders coupled to motors that move the feed arm or mail tray transport and wherein an apparatus control is in operative communication with said one or more encoders to determine the distance moved. 
     
     
         29 . The apparatus of  claim 24  wherein the apparatus control is configured to determine whether a repack interval has been reached and initiating a repack operation if the repack interval has been reached, said determination done concurrently with feeding of envelopes. 
     
     
         30 . The apparatus of  claim 29  wherein the apparatus control is configured to initiate the repack interval as a function of a predetermined number of envelopes having been fed into the mail tray. 
     
     
         31 . The apparatus of  claim 29  wherein the repack interval is based on a predetermined pressure profile being sensed by the mail pack pressure sensor. 
     
     
         32 . The apparatus of  claim 29  wherein the apparatus control is configured to cause the feed arm to move by a predetermined distance as part of the repack operation. 
     
     
         33 . The apparatus of  claim 29  wherein the apparatus control is configured to cause the feed arm to move the feed arm until a predetermined pressure is detected by the mail pack pressure sensor during the repack operation. 
     
     
         34 . The apparatus of  claim 24  wherein when the pack pressure exceeds a predetermined minimum threshold the apparatus controller is configured to cause the relative position of the feed arm to move away from the back end of the mail tray and resume feeding envelopes after the pack pressure is above the predetermined minimum threshold. 
     
     
         35 . The apparatus of  claim 24  wherein the apparatus controller is configured to determine that the mail tray is full by counting a quantity of envelopes fed into the tray and comparing the counted quantity to a predetermined tray capacity number. 
     
     
         36 . The apparatus of  claim 35  wherein the apparatus controller is further configured to ignore when the pack pressure exceeds the predetermined threshold in order to allow the mail tray to be filled fully to the predetermined tray capacity number when the mail tray is almost full. 
     
     
         37 . The apparatus of  claim 24  further comprising an optical scanner positioned to scan fed envelopes, the optical scanner coupled to the apparatus controller and wherein the apparatus controller is configured to determine that the mail tray is full upon detection by the optical scanner of an optical mark on a designated last envelope. 
     
     
         38 . The apparatus of  claim 37  wherein the apparatus controller is further configured to determine that the mail tray is full by counting a quantity of envelopes fed into the tray and comparing the counted quantity to a predetermined tray capacity number, and ceasing scanning for the optical mark if the predetermined tray capacity number is met.