US2576529A - Web registration device - Google Patents

Description

F! P 8212 XR 2 Q5769 529 WEB REGISTRATIONVDEYICE Filed Nov. 22, 1946 2 SHEETSSHEET 1 INVENTOR 57 HENRYEMKENNEY BY W/LLlfY H. NEWELL Ar' oR/vZ r w .w 1 V Nov. 27, 1951 McKENNEY ETAL 2,576,529

WEB REGISTRATION DEVICE Fi led Nov. 22, 1946 2 SHEETS-SI-1EET 2 I5 l r12 INVENTOR. HENRY F. MKENNE Y BY WILLIAM H. NEWEL L ATTORNE Y Patented Nov. 27, 1951 WEB REGISTRATION DEVICE Henry F. McKenney, Flushing, and William H. Newell, New York, N. Y., assignors to The Sperry Corporation, a corporation of Delaware Application November 22, 1946, Serial No. 711.616 1 Claim. 2712.6)

1 This invention relates to a registering device for controlling the feed of a moving web such as a web of paper or metal foil to be cut into blanks for making folded boxes or packages, or a web 2 drive which is determined by the error signals received from the photoelectric cell; The motor control circuit includes an amplifier system which is connected to control the operato be printed in a plurality of steps which must 5 tion of a pair of saturable core transformers, the be maintained in registration as in color printing. outputs of which are connected in opposition to In a specific embodiment the invention may be the control winding of an induction motor. A applied to a web of aluminum foil or the like feed-back generator capable of producing a carrying a recurring printed pattern which is fed voltage which is a function of its speed is driven continuously past a cutting knife for cutting into by the induction motor. The amplifier system inindividual blanks. In this embodiment the includes an inverter stage comprising a pair of tubes vention provides means for accurately maintainwith their cathodes coupled by a biasing resistor ing the cutting knife in register with the printed in such a manner that their plate currents vary pattern on the foil so that the pattern appears in opposite sense. The signal from the photoin the properlocation on each cut blank. 5 electric cell, suitably amplified, is applied to the An object of the invention is to provide a novel grid of one of the inverter tubes and the signal and improved registering system of the above derived from the generator is supplied to the type which is suited for maintaining accurate grid of the other inverter tube in such a manner registration during commercial operations. that the combined effect of the signals causes v Another object is to provide a registering systhe induction motor to operate in a direction and tem of the above type which is adapted to operate at a rate which is a function of the input signal. on a continuously moving web and is designed to For causing the correction motor to operate advance or retard the feed of the web to the continuously over a complete cycle of the cutting cutting knife as required for maintaining acknife, a so-called memory circuit is introduced curate registration. into the input of the inverter stage. This circuit Another object is to provide a system of "the includes a condenser which is charged by the above type in which the correction is introduced input signal from the photoelectric cell and maincontinuously during a cycle in response to an tains its charge through a complete cycle of opererror which is determined at a given point in each ation. The condenser is connected to the input cycle. circuit of the inverter stage in such a way that Another object is to provide a system of'the the amplified voltage is maintained constant type above described in which the correction-rate throughout a full cycle of operation of the cutting is a function of the direction and magnitude of knife and constitutes a basis for comparison with the observed error. the signal in the feed-back circuit during such Various other objects and advantages will be cycle. apparent asthe nature of the invention is more Although the novel features which are believed fully dis los d. to be characteristic of this invention are pointed In accordance with one embodiment of the inout more particularly in the claim appended vention as applied to a moving web of aluminum hereto, the nature of the invention will'be better foil or the like carrying a printed pattern and 40 understood by referring to the following descripadapted to be cut into blanks, a light modulating tion taken in connection with the accompanyv index is printed on the web in predetermined relai g drawings in which a specific embodiment jtionship to each blank area. A beam of light is thereof has been set forth for purposes of illusfo'cused'on the path of the index area and is ra ion. reflected therefrom onto a photoelectric cell in In the drawings: amanner such that the reflected light is altered Fig. 1 is a diagramma ic r pr sentation of a during the passage of the index area. The signal registering system embodying the present invenproduced by the photoelectric cell in timed relation as applied to a travelling web to be cut tionship to the actuation of the knife is applied into box blanks or the like; and to an amplifier circuit of a type which is adapted Fig. 2 is a schematic diagram of the amplifier to drive a correction motor in a direction and at system for controlling the operation of the cora rate which are functions of the indicated error. 'rection motor. The correction motor is connected through a dif- Referring to the drawings more in detail, the ierential to the driving means for the feed roller invention is shown as applied to. a travelling web and introduces a lead'or lag in the feed roller l0 which may comprise a strip of metal foil'to be cut into lengths for forming box blanks. The foil may carry a suitable printed pattern not shown to appear on the various sides of the folded box. The marginal edge of the web I is assumed to have a light reflecting surface on which are printed suitable index areas I I in predetermined relationship to the patterns for the various blanks to be cut. The index areas I I are of a material having a different light reflecting characteristic from that of the foil surface and are adapted to modulate the reflected light as they intercept the light rays.

In the embodiment shown the web I0 is fed by a pair of feed rollers I2 which are driven by a shaft I3 which is connected by bevelled gears I4 and a shaft I5 to one side I6 of a differential I1. The other side I8 of the differential I1 is driven from a drive shaft through bevelled gears 2| and a shaft 22. The web I0 is cut into blank lengths by a rotating knife carried on a roller 26 which is mounted on a shaft 21 driven through bevelled gears 28, shaft 29 and bevelled gears 30 from the drive shaft 20. A stationary anvil 3| cooperates with the rotating knife 25 for severing the web I0 when the knife 25 is brought into registration therewith.

It will be evident that in the absence of a correction device any error in the position of the rotating knife 25 with respect to the travelling web I0 will result in an improper positioning of the printed pattern on the folded box formed from the blank. Likewise in the case of a printed web in which various colors, for example, are to be printed in succession, the error in registration would tend to offset the printing of the various colors and would result in an imperfect product.

In accordance with the present invention a light beam is produced from a source 36 which is energized from mains 31. Light from the source 36 is focused by lens 38 through an aperture plate 40 onto the marginal portion of the printed web I0 in the shape of a rectangular light spot 4|. Light from this spot 4| is reflected from the surface of the foil and passes through a focusing lens 42 onto a photoelectric unit 43 which is shown more in detail in Fig. 2 and is adapted to produce a signal, the value of which is dependent upon the position of the light spot 4| with respect to the index area I I at the timed instant. The correction signal thus produced is applied by a line 44 to an insulated microswitch contact 45 which is contacted by a contact on a lever 46 actuated by a cam 41 mounted on the shaft 21. A similar insulated microswitch contact 49 is contacted by a contact on a lever 50 controlled by a cam 5| mounted on the shaft 21. Springs 52 and 53 hold their respective levers 50 and 46 against theircams. The cams 41 and 5| are relatively adjustable about the shaft 21 to vary the duration of the closed period and may be secured by set screws 54. The entire microswitch assembly including the levers 46 and 50 is mounted on a support 55 to which both levers 46 and 50 are electrically connected and which is adapted to be rotatably adjusted about the shaft 21 for varying the timing of the closed period. The support 55 is shown as provided with a manual adjustment shaft 39 for the above purpose.

The microswitch 49 is connected by a lead 58 to a control mechanism 80 which is shown more in detail in Fig. 2 and is provided with an output shaft 6| which is driven in a direction and at a rate which is a function of the error signal. The shaft 6| is connected by bevelled gears 62, shaft 63, bevelled gears 64 and shaft 65 to the cage of 4 the differential I1 and is adapted to produce a relative adjustment between the position of the feed rollers I2 and of the rotating knife 25 suited to correct the error in registration indicated by the error signal.

Referring to Fig. 2, a photoelectric cell 10 is connected to ground by a lead 1| and a resistor 12 and is supplied with a regulated voltage. for example. 90 volts, by a lead 13 which is connected 10 to a suitable source of D. C. potential.

The voltage produced by the photoelectric cell 10 is amplified by an amplifier tube of standard type which is provided with a control grid 8| connected by a lead 82 to the ground lead H of 15 the photoelectric cell and with an anode 83 which is connected by a lead 84 to a source of plate potential such as the 90 volt lead 13. The amplifier tube 80 is provided with a cathode 85 which is connected by a lead 86 to a potentiometer 81, thence by a lead 88 and through a resistor 89 to v a source of constant biasing voltage, for example, 105 v. The elements 10-89 constitute the unit 43 of Fig. 1. 4

The potentiometer 81 is provided with an adjustable tap 90 which is connected by the lead 44 of Fig. 1 to the microswitch 45. The second microswitch 49 is connected by the lead 58 to the grid of an amplifier tube 96. A condenser 200 is connected between the grid 95 and ground. This condenser is of sufficient capacity to receive a charge proportional to the applied error signal and to retain this charge until the microswitches 45 and 49 are again closed. The cathode 91 of the tube 96 is connected to one side of a potentiometer 98 having a variable tap 99 which is connected through a cathode biasing resistor I00 and a lead IOI to a source of biasing potential such as the v. source. The anode I02 of the tube 96 is connected by a lead I03 to an impedance coupling network I04 comprising resistors I05, I06 and I01, thence by a lead I08 to the control grid I09 of an amplifier tube I I0. The resistor I05 is connected by a lead I I I to a return lead |I2 which in turn is connected to the 90 v. 45 lead 13. The resistor I01 is connected by a lead 3 to the resistor I00.

The tube I I0 is shown as provided with a screen grid II5 which is connected by a lead II6 to the lead I I2 thence to the 90 v. lead 13. The tube I I0 is also provided with a cathode I25 connected to ground by a lead I26 and with an anode I I1 which is connected by a lead I I 8 to the saturating winding 9 of a saturable core transformer I20 having a primary |2| and a secondary I22. The other side of the saturating winding 9 is connected by a lead I23 to a source of D. C. potential such as 300 v. source. A protective resistor I24 is shown as connected across the saturating winding II 9.

An'amplifler tube I30 has a cathode I3I connected by a, lead I32 to the potentiometer 98, and has an anode I 35 connected by a lead I38 to an impedance coupling network I31 comprising resistors I38, I39 and I40, thence by a lead 65 MI to the control grid I42 of an amplifier tube I43. The resistor I38 is connected to the lead H2 and thence to the 90 v. lead 13. The resistor I40 is connected by a lead I44 to the resistor I00.

The amplifier tube I43 is provided with a 70 cathode I50 connected by a lead I5| to ground.

The screen grid I54 of the tube I43 is connected by a lead I55 to the lead H2 and thence to the 90 v. lead 13.

The anode I56 of the tube I43 is connected by 75 a lead I 51 to the saturating winding I58 of a second satu-rable core transformer I59 having a primary I66 and. a secondary I6I. The other side .ofthe saturating winding I58 is connected to the lead I23.and thence to the 300 v. source. A protective resistor I62 is connected across the saturating winding I58.

Primaries I2I and I66 are supplied in series from a 110 v. 60 cycle source by mains I65 and I61. The main I65 is connected by a lead I66 to the primary I2I, thence by a lead I68 to the primary I60, thence by a lead I60 to the alternating current supply main I61.

-A two-phase induction motor I16 is shown as provided with a rotor "I, an energizing winding I12 and a control winding I13. The energizing winding I12 is connected across the alternating current supply mains I65, I61. The secondaries I22 and I6I of the saturable core transformers are connected in series opposition to the control winding I13 of the motor by means of leads I15, I 16 and I 11. A phasing condenser I18 is connected across the control winding I13.

. The rotor "I of the motor I is connected to the shaft 6|. This shaft carries a D. C. generator I80 having an armature connected by brushes I8I and I-82 and leads I83 and I84 to a resistor I85, a potentiometer I86 and a resistor ,I81 in series. The lead I84 is grounded at I88. .The potentiometer I 86 is provided with a variable tap I69 which is connected by a lead I90 to the control grid I9I of the tube I36.

In the operation. of-this device the microswitches 45 and 40 are closed bythe cams 41 and 5 I for a short interval during each cycle of operation of the cutting knife 25. The cams 41 and 5 I are individually adjustable so as to control the duration of the closed periods, such a. period may, for example, be of the order of .005 second. The support 55 is rotated with respect to the shaft 21 so that this closed period will occur when the device. is in proper registration at. the instant that the light spot 4| from the light source 36 is equally divided between the index mark I I and the foil surface at the leading edge of the index mark. Under these conditions a given voltage is produced by the photoelectric cell 16 which corresponds to correct registration and the voltage is either increased or decreased asthe case may be, if the position of the web I0 ,at the instant of closing of the microswitches either lags or leads the correct position. In the embodiment illustrated, if the web I6 should lead its proper position, the leading edge of the index area II will have advanced beyond the midpoint of the light spot M and a signal of lesser intensity will be produced by the photo-electric cell 10, whereas if the web I6 should lag its correct position the index area II will intercept a lesser portion of the light rays and a signal of higher intensity will be produced by the photoelectric cell.

Thevoltage from the photoelectric cell 16 is applied to the control grid 8| of the amplifier tube 86 and controls the plate current of that tube. A voltage is thus produced at the tap 96 of the potentiometer 81 which is a function of the plate current and is likewise a function of the applied voltage from the photoelectric cell 16. In operation, suitable adjustment is made of the tap 96 of the potentiometer 81 so that the tap is connected at the zero voltage position under conditions of proper registration. In this way a negative voltage is obtained at the tap 96 when an error appears in one direction and a positive voltage is obtained when an error-appears in the opposite direction. w

The voltage produced at the tap 96 issupplied through the microswitches 45 and. 49, at. the instant that these switches are both closed. to the control grid of the tube 95. This voltage also charges the condenser 260 which is of. a size such that it becomes fully charged to the applied voltage during the instant of closing of the switches 45 and 49 and retains its charge through a complete cycle of operation, that is until the switches are again closed at the next cycle. The condenser 260 thus comprises a memory circuit which retains a voltage corresponding" to the registration error during the entire cycle. I I

The operation of the amplifier tubes IIO and I43 controls the saturating current which passes through the windings I I6 and I58 of the saturable c'oretransformers I20 and I58. If the saturating current supplied to the transformer I20 is in balance with that supplied to the transformer I59 the voltages supplied by the secondaries I22 and I6I are balanced-out and no resultant voltage is applied to the control winding I13 of the motor I-10. If, however, the voltages in the secondaries I22 and I6I are unbalanced a resultant voltage 'is applied to the control winding I13 which causes the motor I 10 to rotate in one direction or the other depending upon the phase of the applied voltage, and at a rate which is dependent upon the magnitude of the applied voltage.

The' amplifier tubes 56 and I30 and associated resistors 88 and I66 and networks I64 and I31 form an inverting and combining stage whose output-is the amplified sum or difierence of the error'and feed-back input signals. The amplifier tubes H0 and I43 form a stage of amplification between the inverter and the saturable core reactors I26 and 156.

The adjustments are made so that with a zero error signal on the grid 95 and a zero feedback signal on the grid IBI the saturable core transformers I26 and I59 are in balanced relationship and zero control voltage is supplied to thecontrol winding I13 of the motor I16. If now a plus or minus error signal is applied to the grid 95 the space current in the tube 96 is altered in either a positive or negative direction with a corresponding change in the space current'in' the tube 1 I6 and the saturating current in the winding H0. The space current intube 05, flowing through the self biasing resistor I60, varies the cathode potential of the tubes. and I36. Since the grid, voltage of the tube I30 remains unaltered, the change in cathode bias due to the resistor I60 varies the space current of the tube I30 in an opposite sense from the variation of thesp'ace current in the'tube 06, whereby produclnga corresponding variation in the saturating current in the winding I58. The inverter stage thus produces an opposite change inthe saturating currents to the two transformers I20 and I59 in response to an error signal on the grid as. The saturation of the two transformers I26, I thus becomes unbalanced and a resultant voltage is supplied to the control winding I13 of the motor I10 which causes the motor to operate.

The motor I10 drives the generator I86 and causes the latter to apply a voltage to the potentiometer I66 which is dependent upon the direction and speed of rotation of the generator. The

7 voltage at the tap 189 is applied to the control grid I91 of the tube 130 of the inverter stage and produces an effect which opposes the effect of the error signal.

Assuming, for example, an error signal of :9 v. range and that the amplifier network is adjusted so that an error signal of :2 v. will cause the motor I10 to operate at full speed, it is evident that the motor I10 will operate at constant speed when the error signal is between :2 v. and i9 v. If the feed-back signal which is produced by the generator I80 is adjusted to a value of 7 v.- at full generator speed, the difference between the error signal and the feed-back signal at full speed would amount to 2 v. which produces maximum torque on the motor I10. At any intermediate value of error signal the motor will drive the generator at a speed to produce maximum torque conditions, i. e. a 2 v. difference between error signal and feed-back signal. Hence the feed-back causes the motor I10 to operate at a variable speed which is a function of the error signal voltage. above are illustrative only.

The operation of the motor I10 will continue under the control of the voltage across the condenser 200 until the microswitches 45 and 49 are again closed in the next cycle, at which time a new error voltage is received and applied to the condenser 200 and the operation of the devic is modified accordingly.

It will be noted that in the above described device a correction is continuously applied until the error signal is returned to zero. The rate of correction is varied in accordance with the amount of the error signal. The device is extremely sensitive and prevents appreciable error from developing by initiating a correction as soon as the first error signal is received.

Index areas should extend along the web several times the width of the light beam to avoid possibility of a sudden large error allowing an index area to jump ahead of the light ray and cause spoilage of a number of blanks due to successive partial corrections, all in the wrong direction, before the next area is reached. It has been found that a light image having a length along the web of /a inch and a width of 4 inch is suitable for the above purpose and may be made to produce an 18 volt fluctuation at the tap 90 between conditions of maximum light reflection and minimum light reflection. This voltage difierential is suflicient for obtaining an accurate and rapid follow up.

By deriving the error signal from the potentiometer 81 in the cathode lead to the amplifier tube a high input impedance is produced which eliminates electrical loading of photoelectric circuit. This prevents distortion of the voltage signal and insures a true indication of the light intensity on the photoelectric tube. The potentiometer 8'! may, for example, have a value of 7500 ohms and the resistor 89 may have a value of 30,000 ohms. This resistance in the cathode circuit produces a low impedance source for the charging voltage to the condenser 200 which is required for the practically instantaneous charging of the condenser during the short closed period of the microswitches. The value of the capacity I18 is such as to produce a 90 The voltages referred to phase relationship between the voltages in the windings I12 and 113. The voltage in the winding 113 may lead or lag the voltage in the winding I12 dependent upon a plus or minus error signal.

The feed-back from the generator I may be adjusted to correspond to the speed at which the machine is operating. If, for example, the machine is cutting lengths of foil a minute the correction rate may be limited to .03 inch per cycle and the mechanism may be adjusted to maintain registration within this limit of error.

The correction system above described compensates for printing errors, slippage of feed rolls, or error in feed roll speed and maintains accurate registry throughout the entire operation.

Although a specific embodiment of the invention has been described, it is to be understood that the invention is capable of various uses and that changes and modifications may be made therein as will be readily apparent to a person skilled in the art. The invention is only to be restricted in accordance with the scope of the following claim.

What is claimed is:

A correction motor control circuit for travelling webs having recurrent index areas with contrasting light modulating characteristics, continuous web feed means and means deriving an error signal from said index areas corresponding to variations from correct web registration, said control circuit comprising a correction motor connected to modify the operation of said feed means, follow-up means comprising a feedback signal generator driven by said motor, balanced combining and amplifying channels responsive to the combined eifect of said error signal and said feed-back signal and connected to control said correction motor in a sense to maintain correct web registration, each channel including a signal amplifier tube having a control grid, means applying said error signal to one of said control grids, and a condenser in cir .cuit with said last control grid connected to be charged by the error signal and adapted to retain its charge during a complete cycle of operation for maintaining the error signal input to said channels.

HENRY F. McKENNEY.

WILLIAM H. NEWEIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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