Method of Correcting a Multi-Feed in an Automatic Document Feeder

Abstract

A method for operating a paper feed system for use in a printing apparatus that detects multi-feeds and separates all sheets while allowing a single sheet to continue is disclosed. The separation method controls a motor for the separator roller that can be torque controlled, allowing varying torques depending on media type and/or user input. The separation method detects multi-feeds, correct the multi-feed, and ultimately feeds one sheet at a time through the automatic document feeder.

Claims

1. A method of separating multi-feeds in an automatic document feeder, comprising: initiating a scan request so that at least one media page advances to the multi-feed sensor; stopping the pick motor if a multi-feed is detected; increasing the separator motor torque in gradual increments, to provide additional separating torque; determining if the multi-feed is clear; restarting pick motor if the multi-feed is clear; resuming normal feed and separation process.

2. The method of claim 1, wherein the sensor is ultra-sonic.

3. The method of claim 1, wherein the sensor is optical.

4. The method of claim 1, wherein a driving feed belt mated with a counter-rotating separator roller is used, and the separator roller is counter-rotated to prevent multiple sheets from feeding.

5. The method of claim 4, wherein the separator roller is torque controlled with a motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0015] FIG. 1 shows the schematic layout of the ADF pick and separation system.

[0016] FIG. 2 shows the ADF pick and separation system.

[0017] FIG. 3 shows the ADF separator motor and roller with the with the feed belt and pick assembly removed.

[0018] FIG. 4 shows the ADF separation system with an ultrasonic multi-feed sensor.

[0019] FIG. 5 shows the multi-feed correction process.

[0020] FIG. 6 shows a printer with an automatic document feeder (ADF).

DETAILED DESCRIPTION

[0021] It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the terms having, containing, including, comprising, and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles a, an, and the are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. The use of including, comprising, or having and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Terms such as about and the like are used to describe various characteristics of an object, and such terms have their ordinary and customary meaning to persons of ordinary skill in the pertinent art.

[0022] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements Like numerals refer to like elements throughout the views.

[0023] Referring initially to FIG. 1, the ADF layout is shown, which operates inside a printer 601 (see FIG. 6). The pick tire 101 and feed belt 111 are driven by the pick motor (not shown in this figure) and move the media in the process direction 121 shown. The separator roller 131 is driven in the opposite direction by the separator motor (not shown in this figure).

[0024] Referring now to FIG. 2, the separator motor 201 and the pick motor 211 are depicted. The separator motor 201 is current controlled to provide a specific torque value. Because motor torque is proportional to motor current, by controlling the current through the separator motor, the proper counter-rotating torque is achieved at the separator roller 131. The motor current is controlled by adjusting the command signals to the motor driver.

I.sub.M=G.sub.MD*V.sub.REF [0025] I.sub.M: Motor Current (Amp) [0026] G.sub.MD: Motor Driver Gain [0027] V.sub.REF: Reference Voltage (Volt)

T.sub.M=K.sub.T*(I.sub.MI.sub.NL) [0028] T.sub.M: Motor Torque (mNm) [0029] K.sub.T: Motor Torque Constant (mNm/Amp) [0030] I.sub.NL: Motor No Load Current (Amp)

[0031] FIG. 3 shows the separator roller 131 and motor 201 with the feed belt 111 and pick assembly 221 removed. Since the reference voltage is a value that can be change through the scanner firmware, the torque value at the separator roller 131 can be changed, allowing different torque settings for different media scanned. The torque on the separator roller could also be changed by the user depending on the media used.

[0032] A multi-feed sensor 421 is shown in FIG. 4. For the multi-feeds that pass the feed/separation system, the ADF has a two-part sensor to identify this situation. This two-part ultrasonic sensor 421 that is downstream of the feed belt/separator roller has an ultrasonic transmitter 401 and an ultrasonic receiver 411. Alternatively, an optical or infrared sensor may be used to provide the same function as the ultrasonic sensor shown here. The ultrasonic sensor detects when two or more sheets are present due to the air gap between sheets that muffles the sound of the transmitter.

[0033] FIG. 5 shows the multi-feed correction process where the separation motor torque is increased to prevent the multi-feed from advancing. During normal operation, a user initiates a scan request 501 and at least one media page advances to the multi-feed sensor 511. If the multi-feed sensor does not detect a multi-feed, then the media page advances through the ADF 522 to completion 523. If a multi-feed is detected 521, i.e., two or more sheets are present in the path, then the pick motor is stopped 525. Thus, the driving force on the multiple sheets would stop. The separator motor torque is increased in gradual increments, for example 5% 530, to provide additional separating torque. The media interval is then viewed 535 and the multi-feed sensor queried to determine if the multi-feed is clear 540. If the multi-feed is cleared, then the separator motor torque is reset to its default value 545, and feeding is resumed. If not, then unless the maximum separator motor torque has been reached 550, then the separator motor torque is increased 530. The separator motor torque is increased in gradual steps until the bottom sheet(s) reverse direction and the multi-feed sensor 421 reports that a single sheet is present. The pick motor would restart, and the normal feed and separation process would resume. If the maximum separator motor torque is reached 550, and the multi-feed is not cleared, then multi-feed jam is declared 575, requiring user intervention.

[0034] It is also possible during the separation process that the separator roller 131 is slipping on the bottom sheet and spinning in reverse. In this case, the multi-feed sensor 421 is monitored, and if there is no change in the status within a certain time period, then the speed of the separator roller 131 is reduced, while increasing the torque. The process would continue until the multi-feed sensor 421 reports a single sheet is present. The pick motor 211 then restarts, and the normal feed and separation process would resume.

[0035] The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.