Envelope feeder with selective suction cup assist

Abstract

The novel solution provides a method for feeding of individual envelopes from a stack of envelopes in a hopper for an inserter machine. At the downstream end of the hopper, a friction feeder serially feeds individual envelopes from the stack. A suction cup is selectively actuated to engage with the envelope to pull a leading portion of the envelope away from the stack to assist the friction feeder in feeding envelopes. Selective actuation is based on monitoring downstream movement of fed envelopes. The suction cup is engaged when the envelopes travel a shorter distance than would be expected based on the movement of the feeder.

Claims

1. A method for feeding of individual envelopes from a stack, the method comprising: stacking envelopes in a hopper, the hopper having an upstream end and a downstream end; at the downstream end of the hopper, serially feeding individual envelopes from the stack using a friction feeder; selectively actuating a suction cup to engage with the envelope to pull a leading portion of the envelope away from the stack to assist the friction feeder in feeding envelopes; and wherein the step of selective actuation Is based on monitoring downstream movement of fed envelopes, and wherein the suction cup is engaged when the envelopes travel a shorter distance than would be expected based on the movement of the feeder.

2. The method of claim 1 further Including removing vacuum from the suction cup in order to release the envelope for further feeding by the friction feeder.

3. The method of claim 1 wherein the suction cup is engaged when envelopes fail to travel a distance set as a predetermined threshold.

4. The method of claim 3 wherein the suction cup is engaged for a predetermined number of subsequent envelopes after the predetermined threshold Is not met.

5. An apparatus for feeding of Individual envelopes from a stack, the apparatus comprising: a hopper for holding a stack of envelopes, the hopper having an upstream end and a downstream end; a friction feeder at the downstream end of the hopper, serially feeding individual envelopes from the stack; a suction cup mechanism that is selectively actuatatable to engage with the envelope to pull a leading portion of the envelope away from the stack to assist the friction feeder in feeding envelopes; and wherein the friction feeder includes an encoder for measuring a distance that a fed envelope has nominally been transported, and an optical sensor that detects an actual position of the envelope at a particular point downstream, and wherein the suction cup mechanism, in operative communication with the encoder and the optical sensor, is configured to engage when the envelopes travel a shorter measured distance than would be expected based on the movement of the feeder measured by the encoder.

6. The apparatus of claim 5 wherein the suction cup mechanism includes a valve for removing vacuum from a suction cup in order to release the envelope for further feeding by the friction feeder.

7. The apparatus of claim 5 wherein the suction cup mechanism, in operative communication with the encoder and the optical sensor, is configured to engage when envelopes fail to travel a distance set as a predetermined threshold, based on the comparison of the actual distance traveled compared to the distance expected for travel based on the feeder encoder.

8. The apparatus of claim 7 wherein the suction cup mechanism, in operative communication with the encoder and the optical sensor, is configured to engage for a predetermined number of subsequent envelopes after the predetermined threshold is not met.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects and advantages of the present invention will become more readily apparent upon consideration of the following detailed description, taken in conjunction with accompanying drawings, in which like reference characters refer to like parts throughout the drawings and in which:

(2) FIG. 1 is an isometric view of the hopper and feeder in accordance with the present invention.

(3) FIG. 2 is a top view of the hopper and feeder in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(4) FIGS. 1 and 2 illustrate the envelope hopper 10 used with the present invention. As shown, the envelope hopper 10 includes a plurality of polished, bottom rods 21-23 for supporting a stack 19 of envelopes 20 and providing the envelopes 20 to an envelope feeder 26 at the downstream end of the envelope hopper 10. The rods 21-23 form a supporting surface below the stack 19. Preferably, the envelope hopper 10 is tilted to the left such that the supporting surface is tilted at an angle to facilitate movement of the stack 19 towards the feeder 26, and for feeding. A polished, side rod 24 is provided above the supporting surface on the left-side of the envelope hopper 10 to register the left edge of the envelopes 20. An envelope pusher assembly 25 provides pressure on the stack 19, towards the feeder 26.

(5) At the downstream end of the hopper 10, the feeder 26 is preferably a friction belt that pulls and singulates envelopes into a driven feed nip formed by rollers 27 and 28. In feeder 26, during every cycle the feed belts separate a single envelope 20 out of the stack 19 and move it into the take away nip rollers 27, 28. Feeder 26 further includes an encoder that tracks the motion of the feeder for each envelope, whereby a nominal transport distance caused by the feeder 26 is known (not taking slippage into account).

(6) A suction cup 30 is positioned proximally to the feeder 26 to assist in feeding of envelopes 20. The suction cup actuator 29 causes the suction cup 30 to move forward to engage the surface of the leading portion of envelope 20. The actuator 29 then pulls the suction cup 30 and the leading portion of envelope 20 away from the stack 19. The vacuum to the suction cup 30 is then cut off by an air valve, as the feeder 26 belt, and take away nip rollers 27,28 feed the singulated envelope 20.

(7) The quality of the feeder 26 performance is measured by comparing the measured feed distance versus the nominal feed distance. The measured feed distance is the distance the feed belts move from starting acceleration to the moment when the leading edge of the envelope 20 arrives at the location of the feed confirm sensor 32 (at this point leading edge of the envelope is downstream from the pinch point of take away nip roller 27, 28). The nominal feed distance is the distance between the bottom wall of the hopper 10 and feed confirm sensor 32. If the feeder 26 is working ideally, the measured feed distance should be the same as the nominal distance. But due to slippage, the distance feed belts travel to the moment the envelope arrives at the feed confirm sensor may be longer than the nominal distance.

(8) In accordance with the improved system described herein, the feed distance is monitored every cycle and compared to a maximum allowed distance for particular material size. If the feed distance is lower than a threshold value the suction cup mechanism 29, 30 stays deactivated. If the feed distance exceeds the threshold value the suction cup mechanism 29, 30 is activated for N consecutive cycles. After N cycles are expired the control algorithm deactivates the suction cup mechanism. N is a configurable number that can be set in advance.

(9) Although the invention has been described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the spirit and scope of this invention.