US3254888A

US3254888A - Sheet feeding apparatus having ultrasonic means to detect overlapping

Info

Publication number: US3254888A
Application number: US293024A
Authority: US
Inventors: Street Leslie John
Original assignee: Parnall and Sons Ltd
Current assignee: Parnall and Sons Ltd
Priority date: 1962-07-06
Filing date: 1963-07-05
Publication date: 1966-06-07
Anticipated expiration: 1983-06-07
Also published as: GB1040158A; FR1361736A; NL294955A

Description

June 7, 1966 L. J. STREET 3,254,888

lNv/ENToR LESLIE IoHN STREET Bla mow- *EJE/MM United States Patent O 3 254 888 SHEET FEEDING APARATUs HAVING ULTRA- SQNIC MEANS TO DETECT OVERLAPPING Leslie John Street, Long Ashton, near Bristol, England,

assignor to Parnall 8: Sons Limited, Birmingham, England, a British company Filed July 5, 1963, Ser. No. 293,024 Claims priority, application Great Britain, July 6, 1962, 25,956/ 62 8 Claims. (Cl. 271-57) This invention relates to sheet feeding apparatus, for example, of the kind wherein the sheets are fedsingly from a stack in machines for sorting bank checks, football pool coup-ons and the like into receiving stations appropriate to coded information on the sheets.

In sheet feeding apparatus of the aforesaid kind precautions are usually taken to avoid so far as possible the feeding of two or more overlapping sheets since such double feeding would, for example, result in the failure of associated apparatus to read information on one or more of the overlapping sheets. In previously proposed feeding apparatus these precautions have usually taken the form of the provision of belts, wheels or the like running in the reverse direction and frictionally and/or pneumatically engaging the opposite side of the sheets to that of the belts, wheels or the like which serve to frictionally and/ or pneumatically engage the individual sheets to transport the sheets from the stack.

`It is found in practice that despite the provision of means such as the aforesaid reverse running belts, wheels or the like it is still possible occasionally for two or more overlapping sheets to be fed, and the present invention has for its object the provision of a method and means for detecting the occurrence of such double feeding for initiating appropriate action in further apparatus to which the sheets are transported.

The invention consists of the incorporation in sheet feeding apparatus of means for detecting the feed of two or more overlapping sheets comprising a transmitter and a receiver of longitudinal air pressure vibrations located on opposite sides of the path of feed of a sequence of sheets, and control means for varying the output' of the transmitter and/or the sensitivity of the receiver for distinguishing between the presence of one and two or more overlapping sheets between said transmitter and receiver.

The invention further resides in the meth-od of detecting the feeding of two or more'overlapping sheets comprising4 the adjustment of the output and/or the sensitivity respectively of a transmitter and receiver of longitudinal air pressure vibrations located one on each side of the path of feed of a sequence of sheets so that the receiver senses the difference between the presence of a single sheet and two or more overlapp-ing sheets between said transmitter and receiver, and utilizing the response of the receiver to the feed of two or more overlapping sheets to initiate action in apparatus feeding and/ or receiving said sequence of sheets.

Preferably in the aforesaid apparatus and method said longitudinal air pressure vibrations are of ultra-sonic wave length.

One example of the practical realization of the invention is described with reference to the accompanying drawing showing in side elevation a single sheet feeder according to the invention in partly diagrammatic form.

The sheet feeding apparatus illustrated is designed to deliver single sheets intermittently from a stack of sheets such as, for example, bank checks, or football pool coupons, and comprises a magazine 10 for accommodating a stack 11 of said sheets with the sheets disposed in parallel vertical planes also parallel with the plane of a feed 3,254,888 Patented June 7, 1966 gap between the forward and reverse running elements forming parts of sheets transporting and rejecting means respectively hereinafter described. Means is provided for urging thefront face of the foremost sheet 12 of the stack into engagement with the forward running elements 13 of the sheet transporting means for example by supporting the magazine 12 on a conveyor belt 14 so that the conveyor urges the front partly open face of the magazine 12 towards said forward running elements 13.

The sheet transporting means comprises two parallel running toothed endless rubber belts 13 passing over continuously driven toothed pulley wheels 27 so that the belts follow parallel triangular courses with their upward vertical runs dening one side of the feed gap. The belts 13 are ported in longitudinally spaced apart regions and the said vertical runs move before respective hollow shoes 15 to which are applied a partial vacuum. On the opposite side of the feed gap to the vertical runs of the belts 13 is a portedflat face 16 of a fixed sheet rejecting head generally designated 17. Within the head 17 is disposed a drum (not shown) having ports in approximately one half of its circumference with another part of the circumference stepped inwardly to a lesser radius than that of the ported sector. The ported drum sector projects through a window in the ported face 16 slightly beyond the plane of said face. The drum is continuously rotated in the opposite direction to that of the pulley wheels 27 and in synchrony with the movement of the belts 13. The ports in the face 116 of the rejecting head and periphery of the drum communicate through valve ports in the drum, to a vacuum source (not shown). The aforesaid rejecting head is more fully described and claimed in the specification of our patent application No. 269,245 filed April l, 1963 in the United States.

Beyond the fixed head 17 the belts 13 coact with idle rollers 26,' serving to continue the feed of the sheets from the sphere of operation of the rejecting head 17 to reading and/ or sorting mechanism (not shown).

Located one on each side of the path of the intermittently fed sheets on the horizontal runs of the belts 13 and aligned substantially normally to the plane of said sheets is an output head 28 connected to a transmitter 29, and a receiver 30. The transmitter 29 and receiver 30 consist of magneto-striction transducers generating and receiving longitudinal air pressure vibrations preferably in the ultra-sonic range between kc./sec. and 100 kc./sec. with 40 kc./sec. found to be a particularly practical choice. However the invention is not limited to the aforesaid wave band since both higher and lower frequencies can be employed although in the case of frequencies below 20 kc./sec. extraneous noise can cause diiiiculty.

The assembly of transmitter and receiver may advantageously be that marketed by Delavan Manufacturing Company of West Des Moines, Iowa, under the name of Sonac coupler assemblies and described in Descriptive Bulletin 41-2 of Augsut 1961 published by that company.

While

transducers

29 and 30 may both be located irnmediately in proximity to the path of the sheets it is more convenient to feed for example the output from the remote transmitter 29 via a pipe 31 to the head 28 as illustrated. Both the transmitter 29 and the receiver are connected to an amplifier 32 incorporating a sensitivity or gain control 33, and the amplifier output controls a relay 34 having output terminals 35.

The relay controlled terminals 35 are connected for example to control the feed of the sheets to subsequent sheet processing apparatus. For example the opening of the circuit through the terminals 35, following a double feed, may be used via a solenoid valve 36 connected to the terminals 35 by line 37 to vent supply conduit 38 leading to the vacuum shoes 15 to atmosphere to arrest Si further feeding from the stack 11, and to operate via a further solenoid a detlector to divert all sheets in transit to an appropriate receptacle. Alternatively the terminals may simply be connected to an alarm device.

In operation a stack 11 of sheets is inserted in the magazine with the sheets parallel t0 the feed gap and the front face of the foremost sheet 12 urged into engagement with the upward runs of the ported belts 13. As the ported areas of the belts 13 reach the upper marginal part of the front face of the foremost sheet 12 the vacuum in the shoes 15 behind the belts 13 is communicated through the belt ports and serves to suck the foremost sheet 12 against the belts 13 whereby the sheet 12 is lifted from the stack and is transported into the region of the fixed head 17. Shortly after the foremost sheet 12 has been gripped on the belt 13 the vacuum is applied to the ports in the face 16 of the fixed head and this usually serves to suck onto this face 16 any second sheet that may be adhering to the foremost sheet 12, while allowing the first sheet to proceed in View of the low friction between two overlapping sheets. After the upper marginal part of the foremost sheet 12 has been transported past the fixed head and after the application of vacuum to the fixed head ports, the vacuum is then applied to the ports in the reverse running drum so that the drum tends to return any second sheet back towards the stack 11.

Despite the operation of the aforesaid head 17 occasionally two overlapping sheets escape past the head and proceed between the transmitting head 28 and the receiver 30. However, in setting up the machine the sensitivity control 33 is adjusted to give an acceptance of one thickness of the sheets, with a reasonable margin of tolerance, without operation of the relay 34, Whereas the presence of two or more thicknesses of sheets between the transmitter head 28 and receiver`30 blocks transmis-sion of the ultrasonic beam and thereby is made to give rise to a loss of signal in the receiver sufficient to operate the relay so as for example to arrest further feeding and to -direct the sheets in transit to a reject station from whence they can be later taken for further processing.

It is to be appreciated that the above device is particularly effective -in sensing a pair of overlapping -sheets not simply due to the relatively small signal loss owing to the presence of a double thickness of sheets between the transducers, but due to the unexpectedly large signal loss which is found to occur at the interface between the sheets, this being important in practice since the device is thereby able toy distinguish reliably between a wide variety of single sheet thicknesses and the presence of two overlapping sheets. Further the device is insensitive to variation in colour density of the sheets, unlike photoelectric devices, and makes use of parts having long life.

We claim:

1. A sheet feeding apparatus incorporating means for detecting the presence of two or more overlapping sheets of paper or the like moving along a feed path from a feeding means adapted to normally feed said sheets one at a time along said path comprising a transmitter and a receiver of longitudinal air pressure vibrations located on opposite sides of the path of feed of a sequence of said sheets, and control means for adjusting said detector means to condition it for distinguishing between the presence of one and two or more overlapping sheets traversing the beam of longitudinal air pressure vibrations between said tran-smitter and receiver. l

2. Sheet feeding apparatus according to claim 1 wherein said transmitter and receiver operate at a frequenc above 20 kc./ sec.

3. Sheet feeding apparatus according to claim 1 wherein said transmitter and receiver operate at a frequency between 20 kc./ sec. and 100 kc./sec.

4. Sheet feeding apparatus according to claim 1, wherein said transmitter and receiver consist of magnetostriction transducers.

5. Sheet feeding apparatus according to claim 1 wherein said control means is connected to means to alter the feed of sheets when the receiver senses two overlapping sheets.

6. A method of detecting the feeding of two or more overlapping sheets of paper or the like comprising the adjustment of detection means consisting essentially of a transmitter and receiver of longitudinal air pressure vibrations located one on each side of the path of feed of a sequence of sheets issuing from feed means adapted to normally feed said sheets one at a time along said path so that the receiver senses the difference between the presence of a single sheet and two or more overlapping sheets traversing the beam of longitudinal air pressure vibrations between said transmitter and receiver, and utilizing the response of the receiver to the feed of two or more overlapping sheets to initiate action in apparatus handling said sequence of sheets.

7. A method according to claim 6 wherein said air vibrations have a frequency above 20 kc./sec.

8. A method according to claim 6 wherein said air vibrations have a frequency between 20 kc./sec. and kc./sec.

References lCited by the Examiner UNITED STATES PATENTS 2,063,479 12/1936 Belluche 271-56 X 2,277,037 4/1942 Clark et al. 209-111.9 X 2,994,528 8/1961 Hull et al. 271-56 2,999,589 9/1961 Norwich 209-111.9 X 3,131,816 5/1964 Mizell et al. 209-111.9

M. HENSON WOOD, JR., Primary Examiner.

SAMUEL F. COLEMAN, Examiner.

W. F. MCCARTHY, lA. N. KNOWLES,

Assistant Examiners.

Claims

1. A SHEET FEEDING APPARATUS INCORPORATING MEANS FOR DETECTING THE PRESENCE OF TWO OR MORE OVERLAPPING SHEETS OF PAPER OR THE LIKE MOVING ALONG A FEED PATH FROM A FEEDING MEANS ADAPTED TO NORMALLY FEED SAID SHEETS ONE AT A TIME ALONG SAID PATH COMPRISING A TRANSMITTER AND A RECEIVER OF LONGITUDINALY AIR PRESSURE VIBRATIONS LOCATED ON OPPOSITE SIDES OF THE PATH OF FEED OF A SEQUENCE OF SAID SHEETS, AND CONTROL MEANS FOR ADJUSTING SAID DETECTOR MEANS TO CONDITION IT FOR DISTINGUISHING BETWEEN THE PRESENCE OF ONE AND TWO OR MORE OVERLAPPING SHEETS TRAVERSING THE BEAM OF LONGITUDINAL AIR PRESSURE VIBRATIONS BETWEEN SAID TRANSMITTER AND RECEIVER.