US2896636A - Detector device suitable for use with cigarette-making machines - Google Patents

Description

July 28, 1959 I GQ'F. w. POWELL ETAL DETECTOR nsvzcz SUITABLE FOR uss WITH CIGARETTE-MAKING MACHINES Filed Jan. 20, 1958 5 Sheets-Sheet 3 L QWW A TTORNE Y5 United States Patent DETECTOR DEVICE SUlTABLE FOR USE WITH CIGARETTE-MAKING MACHINES Gordon Francis Wellington Powell and Richard Graham Crosland, both of Deptford, London, England, assignors to Molins Machine Company, Limited, London, England, a British company Application January 20, 1958, Serial No. 710,000

Claims priority, application Great Britain January 25, 1957 5 Claims. (Cl. 131-21) This invention concerns a detector device suitable for use with cigarette-making machines, said machines being of the kind in which stubs and pieces of cigarette rod are assembled for joining to form a composite rod by feeding them axially in alignment as a step in the manufacture of mouthpiece cigarettes.

In some cigarette-making machines of the kind referred to the pieces of cigarette rod are cut from a continuous rod, while in other machines the pieces are fed from a hopper.

In the first type of machine failure of the mechanism may occur from breakout of the cigarette rod, that is, the continuous rod is imperfectly sealed; failure of the stub supply; ortransfer blockage, that is, the mechanism to which the assembled pieces are transferred for further treatment becomes jammed for some reason.

In the second type of machine failure may occur due to failure of the supply of pieces of cigarette rod; failure of the stub supply; or transfer blockage.

It will be readily understood by those skilled in the art that (depending on the type of machine) if one of the components fails to arrive at the position where they are grouped ready for joining, the resulting rod will be defective or it may be that a rod cannot be formed because a component is missing or a piece of cigarette rod is defective. Loose pieces of material can easily upset the operation of mechanism to which the group is passed and defective cigarettes must not pass unnoticed to the delivery end of the machine so it is imperative that the machine shall stop to enable the operator to clear the fault and determine the cause of the fault, if it is not immediately obvious.

The present invention provides a photo-electric detector suitable for this purpose.

The devices herein specifically described are adapted for use in a machine of the first type and, moreover, one in which two pieces of rod with a double length stub between are joined to produce a short composite rod which is thereafter bisected to produce two mouthpiece cigarettes but as will be seen the invention is generally applicable to detection of faults occurring in any succession of workpieces moving in spaced relationship, that is, if the pieces do not continue to move at the proper rate and are not properly spaced the detector device will operate to stop the machine.

According to the invention there is provided a device for detecting spacing and motion faults in a succession of workpieces moving in spaced relationship, comprising a photo-electric detector, the cell whereof is illuminated as the trailing end of a workpiece passes out of the light beam directed on to said cell and a further photo-electric detector the cell whereof is obscured as the leading end of the succeeding workpiece passes into the light beam directed on to the cell of said further detector, the first said detector being adapted, as its cell becomes illuminated, to cause the energisation of a 2,890,636 Patented July 28, 1959 relay and the second said detector being adapted to prevent energisation of the relay by the first said detector unless the cell of the second said detector is obscured. Thus if the spacing between two succeeding workpieces is not correct or one workpiece is not moving in correct timed relationship with the other, for example, one has ceased to move, the relay condition is affected and this abnormal condition may be used to give a signal or stop the movement of the machine in which said workpieces move.

Further according to the invention there is provided a device for use on a cigarette-making machine of the kind wherein short composite rods comprising two pieces of cigarette rod with an intervening double-length stub are assembled for the purpose of manufacturing mouthpiece cigarettes, said device comprising a photo-electric detector the cell whereof is illuminated as the trailing end of a composite rod group passes out of the light beam directed on to said cell and a further photo-electric detector, the cell whereof is obscured as the leading end of the succeeding composite rod group passes into the light beam directed on to the cell of said further detector, the first said detector being adapted as its cell become illuminated to cause energisation of a relay and the second said detector being adapted to prevent energisation of the relay by the first said detector unless the cell of the second said detector is obscured, the relay having contacts which close when the relay is energised and which are in a control circuit for a motor driving said machine and open to stop the motor unless the relay is energised by the first said detector. Means may be provided for rendering the device inoperative while the machine is starting to run and for preventing the motor from being re-started after it has been stopped by the detector until certain requirements have been fulfilled and the machine is in proper order. For amplification of the detector impulses and as a control device for the relay, transistors are used.

The invention further comprises a device as set forth in the preceding paragraph comprising apparatus whereby a signal pulse originating by illumination of the cell of the first detector is fed to an amplifier through a diode biased to control conduction and the amplified signal is fed to the relay, and a coupling between the cell of the first detector and the cell of the second detector whereby the output from the first cell is fed to the second cell which has a load resistance in series therewith, the lead to said diode being connected to the joint between cell and. resistance whereby when the second said cell is illuminated and its impedance falls the voltage applied to the diode is insufiicient to overcome its standing bias and the signal pulse cannot pass the diode, while if the second said cell is not illuminated its impedance remains high and the voltage applied to the diode overcomes the standing bias and the pulse passes to the amplifier to cause energisation of the relay and the closure of its contacts. The apparatus may further include a condenser Which maintains the supply to the relay during the interval between the pulses (i.e. the time taken for a group to pass completely through the device) said condenser discharging shortly after the expiration of said interval unless a further pulse occurs.

The invention will be more fully described with reference to the accompanying drawings in which:

Figure 1 is a front elevation of part of a cigarettemaking machine in which two pieces of rod with a double length stub between are joined to produce a short composite rod, and showing the detecting apparatus in position. I

Figure 2 is a side elevation of Figure 1.

Figures 3A, 3B and 30 show, in combination, the circuits" and other electrical details of the apparatus, but the figures are drawn separately for the purpose of easier understanding.

Figures 4A, 4B and 4C are diagrams to illustrate the functioning" of the apparatus under three different condition's.

In the apparatus about to be described, the function ofthe apparatus is to' detect any of'the following faults:

(a) Failure of cigarette supply which is normally due to breakout of cigarette rod;

(b) Failure of stub supply.

(a) Transfer blockage.

On the occurrence of any of these faults, the main driving motor of the machine is stopped.

Referring first to Figure 1, the detection apparatus consists of'two photo-detecting heads, 1 and 2, each of which has a photo-cell which'is illuminated by a beam of light projected from" a lamp 3" and reflected by prisms 4 across the path'of'the cigarette components which consist'sof' pieces of cigarette rod 5 and stubs 6. The photo cell of the head 2 can be seen in-' Figure 2 where it is marked 16'.

The cigarette components have already been'fed to a travellingtape 7 on which they have been aligned and abutt'ed. In the present example the cigarettes have been cut-from a continuous cigarette rod formed in the usual way on apparatuswellto'the right of Figure 1 andafter rod-cutting the'stubs have been'fed into the intervening spaces rromea stub hopper with suitable devices for feeding stubs ontothetape and other devices for causing the components to abutas shown.

It will however be understood that the components can be supplied to the tape in any other known way. Alignment' is preserved on the tape by an overhead travelling endless band device consisting of a pair of helical springs s, Figure 2. V

The head-1 is the detector head; and produces a signal pulse each time the trailing end of the piece of cigarette rod (hereafter briefiytermed a cigarette) at the end ofa grouppasses by it, thereby exposing the photocell of said head to the light beam. The other head 2 (referred to henceforth as the gate head) only allows the pulse fromthe'detector head to be'used under normal running conditions.

Referring now to Figures 3A, 3B and 3C, each detec tor pulse causes a relay 10, Figure 3C, to'be energised and its contacts 11 to remain closed (as explained in more detail later) and as long as thiscondition exists the contacts 11 maintain the circuit to the starter of the motor which drivesthemachine but as will now be seen detector pulses are only permitted to'energise the relay as long as the performance of the machine is correct.

On the occurrence of either of the faults a or b referred to above the gate head prevents the detector pulse from operating the relay, whose contacts 11 thus become disengaged; breaking the supply to the machine driving motor, and thereby stopping the machine.

When transfer blockage occurs there is no detector pulse available and sothe relay IObeoomes disengaged and its contacts 11 open and the driving motor circuit is broken.

The description and operation of the apparatus shown in Figures 3A, 3B and 30 can be roughly divided into four sections, viz:

(i) pulse generationcircuit and gating.

(ii) pulse sharper and amplifier.

(iii) output.

(iv) power supply. I

The essential circuit of item (i) is shown in Figure 3A. The photo-electric cell 12 of the detector head 1 is of the cadmium selenide photo-conductive cell type. When the cell'is darkened; it has a high impedance (several megohm's) andlittleciirrent fiows' throughit. On exposure to light, the cell impedance falls to a few hundred ohms; the resultant current surgeihthepriinary 13 of a transformer 14 produces a pulse to the gating network comprising a resistor 15, photo-electric cell 16 of the gate head and blocking diode (a germanium type diode) 17, suitably biased as explained later.

If the gate cell 16 is illuminated, this pulse (negative) is largely attenuated, by the relative impedances of resistor 15 which is fairly high and of the gate cell which is quite low. The bias applied to the blocking diode 17 is sufficient to prevent the pulse overcoming the high impedance of the diode, and it is blocked from the amplifier which is shown in Figure 3B.

If, however, the gate cell 16 is darkened, its impedance is much higher, (due to the inherent time constant of the type of cell it does not reach its final value of up to 5 megohms, in the time available; however, its impedance is at least several thousand ohms) and there is thus a sufiiciently large pulse developed across the gate cell to raise the potential of the diode cathode negative, in respect to the diode anode; that is, to overcome the blocking bias on the diode; and tak'eit into the conducting region. Current can thus flow through the diode 17 and along line'O to the amplifier.

Figure 3B shows the essential components of the pulse shaper and amplifier. This amplifying circuit is, in effect, a mono-stable switch, producing a (nominally) square pulse output of constant amplitude and durati'o'n,- on the application of the requisite triggering pulse. The circuit employs two transistors, 18 and 19. A resistor 9' connects the emitters of these transistors to thepositive line. The current in this resistor develops a'voltage' at the transistor emitters which" fixes the base to emitter bias.

Normally,-the high negative bias applied to the base of the transistor 18 (p; n. p; junction'transistor) by a resistor 20, is sufficient to cause base current to flow, of sufficient magnitude to saturate the collector; that is, to bring the collector volts down to the bottomed condition'by the voltage drop across a resistor 21 caused by the large collector current. The voltage drop across resistors 22 and 23' results in the base of transistor 19 being held positive to the emitter, because of the current flowing-in transistor 18 and in the common emitter resistor thereby cutting off the transistor 19.

Thispotential' is also used to provide the negative block'- ing bias for the diode 17.

On application of the triggering pulse, a positive pulse appears on the collector of transistor 19 as'it starts conducting, which pulse is'applied to the base of transistor 18 through a capacitor 24 thereby taking the transistor 18 into the cut-off region. The collector current falls, resulting in an increase in voltsac'ross resistors 22 and 23, and eventually the unstable condition is reached whereby the base current of transistor 19" through'res'istor 22 is suflicient to saturate said' transistor 19. Transistor 18 is held cut oif'by the charge in the capacitor 24. This charge is, however, leaking away exponentially through the resistor 20 and another marked 25'and after a time (depending upon the magnitude of the charge, and of the relative'potentials of the emitter, and the supply volts, together withthe values of resistor 20, capacitor 24, and resistor 25) the'base of transistor 18' falls negative to its emitter, and the transistor starts conducting, the potential across resistors 22 and 23 fal-ls' making the base of transistor 19 positive to its emitter, thereby cutting off said transistor and the collector volts rise negative and apply a'saturating negative pulse to the base of transistor 18 through capacitor 24.

The unit then remains in that condition until the arrival of a further pulse from the detector head; The output from the amplifier is taken from the collector of transistor 18 by the line marked 0'.

The output stage is shown-at the left of Figure 3C. In

order to provide a degree; of integration of the output pulses," the output is fed from Figure 3B along the line 0 through a diode 2 6 (a-germanium'diode) to a reservoir condenser 27. Thiscondenser charges rapidly through resistor 21 when the transistor 18 is cut off, but retains its charge when transistor 18 switches on except insofar as it discharges through resistors 29 and 30 and the base of a transistor 31. Thus although as previously Further, it is common in cigarette-making machines to use a lever operated clutch in the main drive so that ordinarily the driving motor can be started and then the clutch is engaged to drive the machine. This arrangestated the relay coil is energised at each detector pulse 5 ment is employed in the machine in question and thereand in other circumstances this would mean that the fore a further micro-switch (not shown) is fitted to the relay contacts would open at the end of a pulse they in main starting lever mechanism and is arranged for confact remain closed because the stored charge in the connecting into the driving motor circuit so that after the denser 27 causes the transistor 31 to feed the relay coil photo-electric detector has stopped the driving motor, this in the interval between the pulses. If a pulse does not 10 motor cannot be restarted until the clutch has been disoccur then the condenser discharges and the motor control engaged. circuit is broken. In order to assist in the full understanding of the in- In the conducting region the input impedance of tranvention as at present applied, Figures 4A, 4B and 4C sistor 31 is a few hundred ohms, so that resistor 30 are provided and together with the table given below supplies negligible damping and only serves to provide a show what happens under various conditions likely to low impedance base-emitter circuit when capacitor 27 occur in practice. is discharged. Referring first to Figure 4A which shows normal The base current flowing when capacitor 27 is charged running conditions, the fundamental principle is that the is sufiicient to saturate the transistor 31 thus applying the gate is closed when the light beam is falling on the full D.C. volts across the relay 10. In the event of the cell, and open when the light beam is obscured by the non-arrival of a pulse at transistor 19 the charge on cigarette rod. The signal pulse is produced by the excapacitor 27 rapidly decreases, reducing the collector posure of the detector cell rod to the light beam as a current of transistor 31 and the relay 10 disengages therecigarette passes from in front of it. Under normal condiby switching off the driving motor of the machine. tions the next cigarette has, by this time, obscured the The power supply apparatus is shown at the right of gate Cell, thereby opening the gate, and allowing the Figure 3C. A transformer 32 has two secondary windpulse to be fed to the amplifier, to keep the relay energised. ings, one, 33 to feed the lamps 3 and the other, 34 in In Figure 413 it is supposed that the stub supply has series therewith to provide a voltage which after bridge failed in respect of the right-hand group. Thus, the rectification by a normal selenium metal rectifier 35 space between the trailing end of the last cigarette of smoothed by capacitors 36 gives approximately 18 volts the first group and the leading end of the first cigarette D.C. supply, though this value is merely by way of of the succeeding group is increased, and gate cell is not example. yet obscured, thereby closing the gate and preventing the A supply for the detector cell is obtained from the 18v pulse from being fed to the amplifier: the relay thus supply by a potential divider consisting of resistors 37 becomes disengaged. and 38 with a smoothing capacitor 39, see Figure 3A. In Figure 4C the supply of cigarettes has ceased, for

Referring again to Figure 1 it will be seen that the example, there has been a break-out in the rod. Again detectors are jointly adjustable along a bar 40 while they the spacing has increased so the consequences are the are separately adjustable on round rods 41. same as for Figure 4B.

The spacing between the trailing ends of two groups These results, with others due to faults likely to occur, ie the distance X on Figure 1 is fixed at 209 mm. irre- 40 are now shown in tabular form.

Action on detectors and relay Conditions Detector Gate Relay (1) Normal operation Produces pulse Open Energised.

(2) Stub failure dn Closed Desengages provided that 2 or more successive cigarettes are without plugs.

(3) Cigarette failure Thestubsproducepulse do Disengages.

(4) Transfer bloekage Botht gells continuously illumi- No pu do Do.

Bfih cells continuously in dark- .d0 Open Do.

(5) other la l o c kage conditionsBoth cells do Open (but no pulse from Do.

obscured. detector).

spective of the length of the cigarettes and stubs. Then It is to be noted that the detector only produces a if Y is the distance between the inside faces of the prisms pulse correctly when the trailing end of the end cigarette of the two detectors as indicated in Figures 4A, 4B and of a group is moving across it. 4C:-Y=209 mm. minus (group length plus 5 mm.). The gate is open when not illuminated and is closed In the machine specifically described the three assemwhen illuminated.

bled components to make the short composite rod are For certain purposes the gate and the gating network passed to mechanism where a cork tip is rolled around may be dispensed with in which case the detector pulse them to join the stub piece to the neighbouring ends of goes to the amplifier without hindrance each time it is the cigarettes. Also as previously remarked the stubs produced. For example, if it is only a question of detect are fed from a hopper and the cigarettes are cut from a ing a continuous succession of spaced cigarettes it is continuous rod. In starting such a machine it is first possible to operate in this manner, the apparatus shown necessary to get a satisfactory continuous rod made and in Figures 3A, 3B and 3C being very suitable for detect then start the stub feeding devices, and the cork-tip ing purposes even without the gating device. mechanism. Thus during the time before the stub feed is What we claim as our invention and desire to secure applied on starting up the machine, there would apparentby Letters Patent is: 1y be a fault (equal to failure in stub supply or the break- 1. Apparatus for detecting spacing and motion faults out condition) and the machine would be switched off. in a succession of workpieces moving in spaced relation To counteract this, a micro-switch 42 is fitted which holds ship, comprising a first photoelectric detector having a the relay 10 permanently energised, until such time as the photoelectric cell and means for directing a beam of light cork feed mechanism is engaged, and the normal condithereon, said cell becoming illuminated as the trailing tions of running exist. end of a workpiece passes out of the light beam directed 011 to said cell, a second photoelectric detector having a photoelectriccell and means for directing a' beam of lightthereon, said last named cell being obscured as'the leading end of thesucceeding workpiece passes into the lightbeam directed on to the cell of saidsecond detector, a relay, and a circuit connecting said cells and said relay for; energizing said relay on illumination of the cell of said first detector unless the cell of said second detector is concurrently obscured. p

2. Apparatus for use on a cigarette-making machine having an electric driving motor and a control circuit therefor, said machine being of the kind wherein short composite rods are assembled from composite rod groups comprising'two pieces of cigarette rod with an intervening double length stub, for the purpose of manufacturing mouthpiece cigarettes, said apparatus comprising a first photoelectric detector having a photoelectric cell and means for directing abeam of light thereon, said cell becoming illuminated as the trailing end of a composite rod group passes out of the light beam directed on to said cell,- a second photoelectricdetector having a photoelectric cell and means for directing a beam of light thereon, said last named cell being obscured as the-leading end of the succeeding composite rod group passes into the-light beam directed on to the cell of said second detector, a relay, and connections between said cells and said relay for energizing said relay on illumination of the cell of said first detector unless the cell of said second detector isconcurrently obscured, said-relay havingcon tacts which close when the relay is energized, which are 8 in said control circuit for the motor, and which are open tostop the motor unless the relay is energized by the said first detector.

3. Apparatus as claimed in claim 2 comprising a power supply adapted to energize the relays, and a switch which when closed connects the relay directly to said power supply to render the detecting device inoperative while the machine is starting to run. 7 s

4. Apparatus as claimed in claim 1 in which the circuit connecting said cells and said relay includes a blocking diode normally biased beyond cut ofi, means operative on illumination of the cell of said first detector to deliver a pulse to said diode to render the latter conducting-the cell of said second detector being arranged in shuntwith said diode so as to bypass said pulse when said last mentionedcell is illuminatedto reduce its impedance, and means including an amplifier deliver ing pulses fromsaid diode to said relay.

5. Apparatus as claimed in claim 4 comprising a con denser which discharges to the relay to maintain it in the energizedjstat'e during the interval between the pulses and; a resistance connected to said condenser and through which it discharges shortly after the expiration of said intervalunless a further pulse occurs.

References Cited in the file of this patent UNITED STATES PATENTS Gilson Oct. 20, 1931 Schick Dec. 24, 1946

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