Envelope feeding system and speed control for mail sorting machines

Envelope feeding apparatus for a mail sorting machine having a magazine section for receiving a supply of envelopes to be sorted, means for picking off the envelopes one at a time from the envelope supply at a pickoff station, and means for sorting and depositing the envelopes in a storage area of the machine, said envelope feeding apparatus comprising:

• feeding means for feeding the envelope supply in the magazine section to the pickoff station;
• multiple speed drive means for driving said feeding means, said drive means having active and inactive states and a plurality of discrete speed settings for driving said feeding means at a plurality of discrete speeds when said drive means is in the active state;
• switch means engageable by envelopes at the pickoff station, said switch means having a first condition when an envelope is present at the pickoff station and a second condition when an envelope is not present at the pickoff station;
• means for decrementing said drive means from one speed setting to the next lower speed setting each time said switch means has been in the first condition for a first predetermined time period;
• and
• means for incrementing said drive means from one speed setting to the next higher speed setting each time said switch means has been in the second condition for a second predetermined time period.

In a mail sorting machine having a magazine section for receiving a supply of envelopes to be sorted, pickoff means for picking off the envelopes one at a time from the envelope supply at a pickoff station, feeding means for feeding the envelope supply in the magazine section to the pickoff station, and means for sorting and depositing the envelopes in a storage area of the machine, the improvement comprising:

• drive means for driving said feeding means, said drive means having active and inactive states and a plurality of discrete speed settings for driving said feeding means at a plurality of discrete speeds in the active condition of said drive means;
• a switch at the pickoff station engaged by an envelope present at the pickoff station to effect a first condition of the switch, said switch having a second condition when an envelope is not present at the pickoff station to engage the switch;
• counter means operable to count down toward a minimum count state when said switch is in the first condition and to count up toward a maximum count state when said switch is in the second condition;
• means for decrementing said drive means to the next lower speed setting each time said minimum count state is reached;
• means for incrementing said drive means to the next higher speed setting each time said maximum count state is reached;
• means for resetting said counter means to an initial count state between the minimum and maximum count states each time said drive means is incremented or decremented;
• and
• means independent of said counter means for effecting the inactive state of said drive means when said switch has been continously in the first condition for a predetermined time period.

An envelope feeding mechanism for feeding envelopes to an envelope pickoff device in a mail sorting machine, said mechanism comprising:

• a conveyor surface defining a generally straight conveyor path having an input end and a discharge end located adjacent the pickoff device, said conveyor surface being inclined from side to side and being adapted to receive a supply of envelopes with the envelopes arranged side to side and each envelope having a lower edge thereof on the conveyor surface and oriented transversely to said conveyor path;
• first and second toothed belts supported on the machine for movement generally along said conveyor path from the input end to the discharge end thereof to deliver the envelopes in the envelope supply to the pickoff device one at a time, each belt having a plurality of teeth between which grooves are presented for receiving the lower edges of the envelopes;
• a side panel projecting upwardly from a low side of said conveyor surface, said side panel being inclined from vertical and oriented substantially perpendicular to said conveyor surface to receive side edges of the envelopes that are being conveyed on the conveyor surface;
• a third toothed belt supported on the machine for movement generally along said side panel at an elevated position relative to said first and second belts, said third belt having a plurality of teeth between which grooves are presented for receiving the side edges of the envelopes to maintain the envelopes generally upright and to assist in conveying the envelopes along said conveyor path;
• and
• drive means for driving all of said belts at substantially the same speed, whereby the envelopes are maintained generally upright with the lower edges thereof remaining transverse to the conveyor path as the envelopes travel along said path.

A method of feeding envelopes to an envelope pickoff station in a mail sorting machine, said method comprising the steps of:

• arranging a plurality of envelopes side to side on a movable conveyor with each envelope occupying a substantially vertical plane;
• driving the conveyor toward the pickoff station to deliver the envelopes thereof;
• sensing whether or not an envelope is present at the pickoff station;
• decreasing the speed at which the conveyor is driven when an envelope is present at the pickoff station for a first predetermined time period selected as being indicative of undue bunching of the envelopes on the conveyor;
• and
• increasing the speed at which the conveyor is driven when an envelope is not present at the pickoff station for a second predetermined time period selected as being indicative of undue looseness of the envelopes on the conveyor.