US3604430A

US3604430A - Cigarette dense end measuring and controlling apparatus

Info

Publication number: US3604430A
Application number: US871549A
Authority: US
Inventors: Alan Norwich; John E De Witt
Original assignee: Industrial Nucleonics Corp
Current assignee: Industrial Nucleonics Corp; ABB Automation Inc
Priority date: 1969-11-07
Filing date: 1969-11-07
Publication date: 1971-09-14
Anticipated expiration: 1988-09-14

Abstract

A dense end controller is provided for a cigarette machine having means for making a continuous cigarette rod having dense tobacco regions spaced along the length thereof and a cutter. A density gauge provides a first signal proportional to the density of the tobacco rod. A phase comparator, such as a synchronous detector, continuously compares the phase of the periodic variations in the first signal relative to the phase of pulses in a second signal from the cutter to provide a control signal directly proportional to any deviation of said dense tobacco regions from the ends of cut cigarettes.

Description

United States- Patent [72] Inventors Man Norwich; 7 1942 Stein 131/61 B John E. De Witt, both of Columbus, 01110 2,316,213 4/ 1943 131/61 UX [211 App]. No. 7 549 2,338,070 12/1943 131/21UX [22] Filed No 7, 1969 2,543,277 2/1951 131/63 X [45] patented Sept. 14 1971 2,832,352 4/1958 Powell 131/21 B 7 Assignee Industrial Nucleonics Corporafion 2,954,81 1 10/1960 H ensgen 146/95 Continuafion of application Ser. No. 3,067,754 12/1962 Pmkham et al. l31/2l 543 9 AP 20 1966, now abandoned- 3,174,373 3/1965 Gensman 146/104 X 3,259,746 7/1966 Blunt 131/21 X 3,306,305 2/1967 Molins 131/84 (B) X FOREIGN PATENTS 881,024 11/1961 Great Britain 13l/84C [54] CIGARETTE DENSE END MEASURING AND CONTROLLING APPARATUS Primary Examiner-Joseph S. Reich 1 Claims 1 1 Drawing Figs AtrorneyC. Henry Peterson [52] US. Cl 131/21 B,

1 1/ ABSTRACT: A dense end controller is provided for a [51] Int. Cl A24c 5/32 cigarette machine having means for making a continuous of Search cigarette rod having dense tobacco regions spaced along the 3184,21 length thereof and a cutter. A density gauge provides a first signal proportional to the density of the tobacco rod. A phase [56] References cued comparator, such as a synchronous detector, continuously UNITED STATES PATENTS compares the phase of the periodic variations in the first signal 1,567,533 12/1925 Marsh 131/65 relative to the phase of pu ses n a second signa from the 1,851,334 3/1932 Stein et al 131/65 cutter to provide a control signal directly proportional to any 1,920,708 8/1933 M ]in 131/65 deviation of said dense tobacco regions from the ends of cut 1,968,018 7/1934 Arelt 131/63 cigarettes.

CUTTER DEMVT rag/mm a 6/7065 255%; m

4 I J: 1/ Q 341V 1.

. REFERENCE 1 PUZJE 1 GENE/WI 70/? 360 3a o PATENTEU sin 419m SHEET 1 0F 3 Q \NL AGENT CIGARETTE DENSE END MEASURING AND CONTROLLING APPARATUS This is a continuation of my copending Pat. application Ser. No. 543,916, filed Apr. 20, 1966, now abandoned.

The present invention relates generally to cigarette makers and, more particularly, to improved apparatus for facilitating the manufacture of cigarettes having dense ends.

BACKGROUND Many cigarettes are being manufactured by providing extra tobacco in the tobacco rod at the regions which will form the adjacent ends of cut cigarettes. The purpose of this dense ending is to give the cigarette ends added firmness, good appearance and to prevent small particles of tobacco from falling out of loosely packed ends.

Dense ending apparatuses are built into many modern cigarette machines and they may take on various forms. For example, suction techniques may be employed to drop increased amounts of tobacco onto the tobacco stream, compacting wheels may be used to compress the stream at various points or a rotating trimmer disc having peripheral indentations may be used to trim off more tobacco in some regions of the stream than in others. US. Pat. No. 3,032,041 issued to R. Lanore and British Pat. Nos. 813,576, 940,153, 941,852, and 948,736 are representative of the state of the art in this area.

One problem that arises frequently with these systems is that the extra tobacco in the cigarette rod may occur at the wrong location. The cutter is normally synchronized with the dense ending device so that the cutter cuts through the rod substantially in the center of the dense regions. While the system may be located several feet downstream from the dense ending device and the intervening rod forming mechanisms induce an unpredictable stretching of the tobacco stream and cigarette rod causing misregistration of the cutter with the dense regions. Instead of occurring in the twobutted adjustment cigarette ends where the rod is cut, the dense regions may appear in the center of the cigarette.

Another problem concerns the amount of increased density added to the dense regions. Machines are commonly designed to put typically a percent, a percent, or a percent increase in density into the ends of the cigarettes. Machine faults or maladjustments may cause the magnitude of the dense regions of the tobacco rod to be less than desired.

PRIOR SYSTEMS It has been necessary to sample the density of a large number of cigarettes manually to determine whether or not the dense regions were of the desired magnitude and occurring at the ends of adjacent cigarettes. When the production of faulty cigarettes was discovered, it was necessary to stop the machine and adjust the dense ending device. This method was not only time consuming but also wasteful, as a large number of objectionable cigarettes were produced as a result of the high production rate, e. g. 1,800 cigarettes per minute or more by one machine, before the fault was discovered. Moreover, it was virtually impossible to discriminate between a loss of cutter synchronization and a decrease in density of the dense regions.

BRIEF DESCRIPTION OF THE PRESENT INVENTION We provide. means for determining when a machine is producing cigarettes having acceptable dense ends. Generally, we provide a system for determining the phase relationship existing between the cutter and the dense end regions. A gauge is used to determine when one of the dense regions of the cigarette rod occurs at the location of the cutter. We also generate a reference pulse whenever the cutter cuts through the cigarette rod. By comparing the times of occurrence of the dense end regions relative to the occurrence of the reference pulse, we provide a signal proportional to the amount and direction of any deviation of said dense regions from the ends of the cut cigarettes. Automatic control apparatus responsive to the deviation signal is provided to maintain continuous production of cigarettes having the desired dense ends.

In a specific embodiment, the deviation in phase of the dense end signal components relative to the reference pulse is measured by a synchronous demodulator which provides an output signal directly proportional to any deviation in the synchronization of the cutter with the dense end regions. We also provide means for changing the reference phase of the demodulator to check for insufficiently dense ends.

BRIEF DESCRIPTION OF THE OBJECTS Accordingly it is a primary object of the present invention to provide an improved dense end monitor for a cigarette machine.

It is another object of the present invention to provide a dense end monitor that provides a signal continuously indicative of the dense end condition of the cut cigarettes.

It is also an object of the present invention to provide a signal proportional to the amount and direction 'of any deviation in the synchronization of the cutter and the dense end regions.

It is still another object of the present invention to provide an improved dense end control system.

It is yet another object of the present invention to provide a dense end monitor not requiring skilled operating personnel.

DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 is a block diagram, partly schematic, illustrating our dense end monitoring system for a cigarette dense ending machine together with three associated graphs of typical signal waveforms appearing in portions of the apparatus;

FIG. 2 is a graph of cigarette rod density vs. time for two cigarette samples;

FIG. 3 is a graph showing the output signal of the phase comparator employed in the monitoring system shown in FIG.

FIG. 4 is a partial sectional view, partly schematic, showing a preferred synchronous detector for use in the system shown in FIG. 1;

FIGS. 5a and 5b are graphs showing the waveforms of the input signal and the output signal of the synchronous detector of FIG. 4 in one mode of operation;

FIG. 6 is a sectional view of apparatus for adjusting the time reference of the cutter pulse generator; and,

FIG. 7a-7d are graphs of various waveforms occurring in the synchronous detector of FIG. 4 operating in an alternative mode.

CIGARETTE DENSE END PROCESS With reference now to the drawings and particularly to FIG. 1, a cigarette-making process includes a tobacco stream former l0 delivering a stream 12 of tobacco to a rod former 14. Rod former 14 wraps a paper strip 16 around the tobacco stream 12 and glues the seam to form a cigarette rod 18. The cigarette rod 12 is conveyed to a cutter 20 which periodically cuts a cigarette 22 of length L from the continuous rod 18. In the past, this type of industrial process has been measured and controlled to provide cigarettes having a desired weight per unit length. For a more detailed description of the cigarette making machine, reference may be had to U.S. Pat. No. Re. 25,476 issued Nov. 12, 1963 to S. A. Radley et a1. and assigned to the same assignee as the present invention.

Some machines are equipped with a dense ending device 24 which may comprise a rotating trimmer disc having raised portions spaced around the periphery thereof. Other devices may be employed to provide the same function; some of these are described in the patents cited, supra. The disc trims ofi some tobacco 12a which is returned upstream leaving an excess amount of tobacco in dense regions R spaced one cigarette length L apart from one another. The density of the tobacco in the dense regions R of the cigarette rod 18 may be up to 20 percent greater than the density in the remainder of the rod 18. In a typical example, the length AL of the dense region may be to mm. while the entire cigarette may be some 70 mm. in length.

A main drive motor 26 provides motive power for simultaneously conveying the cigarette rod [8 toward the cutter 20 and actuating the cutter 20 to cut cigarettes of substantially equal length from the rod 18. The dense end device 24 is also coupled to the main drive motor 26 as indicated by the dotted line 28. The object is to time the cutter operation with the dense end device 24 so that the cutter 20 cuts the tobacco rod 18 substantially in the center of each dense region R. If, due to longitudinal dimensional changes of the rod 18 or slippage of the drive to either the cutter 20 or the dense end trimmer, the cutter and dense regions R are not in synchronism, the cigarettes 22 will either have an insufficient amount of tobacco at one end or the other or no dense ends at all.

This effect is graphically shown in FIG. 2 wherein a density profile 27 is plotted on the same time scale as pulses 29 occurring when the cutter 20 cuts through the tobacco rod. A superposed cigarette 22 is shown in section to illustrate an acceptable dense end condition (case I) and an objectionable dense end condition (case II). In both cases the ends of the cigarette 22 are in time coincidence with the cutter pulses 29. In case l, however, the dense regions R arrive at the cutter 20 when a cigarette is being cut. Cigarettes are provided with dense end portions. Case ll illustrates a situation where the dense regions R arrive at the cutter 20 several milliseconds late so that the cut cigarettes contain a centrally located dense portion.

It is desirable to cut the rod 18 continually in each dense region R. By cutting substantially in the center of this region, one end of the cigarette 22 contains approximately the same amount of extra tobacco as the other end. To accomplish this result, one must know when each dense region R occurs at the cutter 20. By comparing the arrival time of each dense region with the time each cigarette is cut from the rod 18, one may determine whether or not the cutter is properly synchronized and, if it is not synchronized, the amount and direction in which it is out of synchronization.

With reference now to FIG. 1, we measure the relative degree of cutter synchronization by comparing the phase of cutter pulses 31 in a reference signal S, on line 36a relative to the increased density pulses in a signal S provided on line 30a by a density gauge 30. Pulses 31 are provided by a reference pulse generator 32 mechanically coupled to the cutter 20 as indicated by the dotted line 34. In the specific embodiment shown, the pulses 31 generated by pulse generator 32 are delayed for a suitable length of time by a delay unit 36, to be further described hereinafter, which provides the delayed pulses on its output line 36a. In its simplest form, generator 32 may be a switch contact which closes every time a cigarette 22 is cut from the rod 18.

Density gauge 30 is preferably located upstream from the cutter 20 to measure the density of the rod 18 and may be of the capacitance type, for example. A preferred form of transducer is described hereinafter. The density gauge 30 is positioned as close as physically possible to the cutter 20. By spacing the gauge 30 an integral number of cigarettes lengths, nL, away from the cutter 20, one knows that a dense region R is occurring simultaneously at both the gauge 30 and the cutter 30. If, due to the lack of space on the cigarette-making machine, for example, it is physically impossible to mount the gauge 30 in a location so as to provide this preferred spacing, either the gauge signal 5 or the cutter signal S may be delayed by a unit 36. The amount of delay provided by unit 36 should take into account any inherent lags in the measurement of rod density by the gauge 30.

A phase comparator 38 compares the phase of the density signal S, with that of the reference signal S, Phase comparator 38 provides an output signal which is directly proportional to a small deviation from cutter dense end synchronization, i.e. its magnitude passes through zero and its polarity always changes in the same direction as the cutter operation is brought from a lagging to a leading relationship with the dense end regions in the manner and for the reasons explained hereinafter. As one suitable output device, a meter 40 may be used to indicate the output signals provided by the phase comparator.

A related dense end monitoring system is the subject of a copending application Ser. No. 544,000 filed Apr. 20, 1966 by John E. Dewitt, now abandoned and refiled Oct. 3, 1969 as Ser. No. 864,292, and assigned to the same assignee as the present application.

In the embodiment shown, the density signal S- on line 300 at the output of density gauge 30 contains portions representative of the increased density in the dense regions R. These portions appear as density pulses 42 extending above the average density signal level. A typical pulse may start at a time t and be centered about a time t as shown. If the cutter pulses 31 on line 36a at the output of the delay unit 36 arrive at time t the cigarette rod 18 is being cut substantially in the center of the dense regions R and the output signal 8;, of the phase comparator 38 is zero as shown by the meter 40. If the cutter pulses arrive either sooner or later than time t the dense regions R either lead or lag relative to the cutter 20. The cutter 20 is no longer synchronized with the dense end device 24. Cigarettes 22 are produced either with an unequal amount of tobacco in each end or with no dense ends at all.

The variation of the output signal S of the phase comparator 38 with the cutter-dense end timing or phase angle difference is illustrated in FIG. 3. As shown by the characteristic curve 44, for small deviations from proper cutter synchronization the signal S is directly proportional to deviations from the desired phase angle difference, i.e. it indicates by its magnitude and polarity respectively both the amount and the direction of any deviation from synchronization. The signal characteristic 44 reverses polarity at 0 where the cutter 20 and dense end device 24 are correctly synchronized. There fore, it is possible to determine not only when the cutter 20 is out of synchronization but also in which direction it is out. Meter 40 may be provided with a center zero dial so operating personnel can immediately observe any deviation in cutterdense end synchronization.

This direction-sensitive capability of our phase comparator makes it especially useful in controlling the process to maintain the desired synchronization. For example, the meter scale may be calibrated in degrees. Operating personnel can read the amount and direction of cutter-dense end phase shift and make appropriate adjustments to the machine to correct the faulty dense end condition. This may be done manually by stopping the machine and rotating the dense end trimmer a given amount in one direction or the other. Alternatively, automatic control can be exerted by another suitable output device comprising a controller 46 operating directly from the comparator output signal S A difierential gearing unit 48 may serve to couple the main drive motor 26 simultaneously to the cutter 20 and the dense end device 24. Differential 48 is provided with a pair of

output shafts

50 and 52, the relative speeds of which can be adjusted as indicated by the arrow. For example, a control shaft is often employed to vary the ratio of the speed of one shaft to the speed of the other. Controller 46 is coupled to this adjuster by the heavy dotted line 54. Other mechanisms for effecting automatic control of cutter synchronization will be apparent to those skilled in the art.

PREFERRED DEMODULATOR EMBODIMENT We have found it particularly useful to employ a synchronous detector circuit 60 as shown in FIG. 4 to demodulate the density signal provided by the gauge 30 because of the random nature of all of the density components in the signal except the dense region pulses. The phase of the density signal applied at terminal A is compared with the phase of the reference pulses applied at terminal 3" to obtain an output signal directly proportional to shifts in cutter-dense end synchronization.

In a preferred form, density gauge 30 comprises a radiation source 62 and a radiation detector 64 positioned on opposite sides of the cigarette rod 18 to provide a signal proportional to the density or weight per unit length of the cigarette rod 18. Amplifier 66 amplifies the output signal of the radiation gauge. Capacitor 68 serves to couple the amplified density signal to the input terminal A of the synchronous detector 60 and effectively block any DC level the density signal may have.

The detector 60 comprises a center-tapped input transformer 70, having the winding polarities arranged so that the input and output connections indicated by the dots will have their respective voltages in phase. Detector 60 further comprises an upper loop including transistor Q diode 72 and resistor 74, and a lower loop including transistor diode 76 and resistor 78 connected to opposite ends of the transformer secondary winding 70a. The free ends of

resistors

74 and 78 are connected together and a capacitor 80 connects their junction to the reference pulse input terminal B. Output meter 82 is connected in series with a resistor 84 between the center tap 86 of the secondary winding 70a of transformer 70 and ground G. Capacitor 88 is connected across the meter 82 to average the current flowing between the transformer center tap 86 and ground Reference pulses may be obtained by bouncing light off of rotating shaft 90 that forms part of the cutting mechanism of cutter 20. The shaft 90 rotates continuously as the knife 92 cuts through cigarette rod 18. Segments of reflecting paint or a tape strip 94 may be spaced around he periphery of the shaft 90. A light source 96 directs light toward the axle 90. A phototransistor 98 may be used to sense light reflected from the strip 94 as the shaft 90 turns. Phototransistor 98 thus generates a pulse train which can be amplified and shaped by a unit 100. The output pulses from unit 100 are coupled to the reference pulse input terminal B of the synchronous detector 60. The length of the strips 94 is made long enough to provide a reference pulse width substantially equal to the width of the dense region pulses 42 in the density signal to be detected.

OPERATION OF THE PREFERRED DEMODULATOR EMBODIMENT The operation of the synchronous detector dense end monitor may be best explained by reference to the waveforms shown in FIGS. a and 5b.

The transistors Q and Q of the synchronous detector 60 act like a pair of ganged single-pole switches, connecting one loop and then the other into the output circuit in synchronism with the reference pulses applied at terminal B. The effect is to invert that part of the density waveform that occurs during the time of the reference pulses 102 shown in dotted line in FIG. St: for simplicity. The output signal, whose waveform is shown in FIG. 5b and which could be the current through meter 82, is inverted from its sense shown in FIG. 5a except during the time At of the reference pulse 102. When the cutter is properly synchronized with the dense regions, the reference pulse 102 from pulse amplifier 100 starts substantially in the center of the dense region at time t,. Since the detector output signal as shown in FIG. 5!; has a zero DC level because of capacitor 68 and transformer 70, and since for all practical purposes the variations in density 104 of the rest of the cigarette rod 18 are random, and since the dense region pulse is relatively symmetrical about the time t,, and inverted after time t, for a time period At, the average value of the output signal of the synchronous detector60 is substantially zero.

The average value of the output will be different from zero whenever the leading edge of the reference pulse 102 does not appear at the time t,. A shift in time one way will produce an output signal having one polarity and a shift in the other direction will cause the synchronous detector to provide a signal of the opposite polarity. The output signal characteristic of the synchronous detector 60 will be similar to that shown in FIG. 3.

INITIAL SETUP It is necessary to set the system up initially by angularly orienting the cutter shaft to provide zero signal on the meter 82 when cigarettes are produced having equal dense ends. Thereafter, any deflection of the meter indication from zero indicates the direction and magnitude of cutter-dense end phase shift. To establish the desired initial mechanicaltime reference, the apparatus shown in FIG. 6 may be used. The lamp 96 and phototransistor 98 are mounted in a housing positioned adjacent to and rotatable with respect to the cutter shaft 90. While the housing 110 is shown concentrically mounted, it need not surround the shaft 90. The housing 110 is provided with a sector gear segment 112 that is engaged by a worm gear 114. Housing 110 may be rotated relative to the cutter shaft 90 turning the worm gear 114. The end of the worm gear 114 may be slotted to enable fine screwdriver adjustments to be made by operating personnel.

Light periodically reflects off of the tape segments 94 toward the phototransistor 98 as the cutter shaft 90 rotates. The length of the pulse generated by the phototransistor 98 will be proportional to the arcuate length of each strip 94.

To set up our system, the cutter 20 and the dense end device 24 are adjusted with respect to one another so that the cutter 20 is cutting the rod 18 substantially in the center of the dense regions R. The worm gear 114 is turned to rotate the housing 110 until the output of the synchronous detector 60 goes to zero. If the cutter motion is stopped as the cutter is cutting through the rod 18, the housing 110 willbe positioned as shown in FIG. 6. At this instant, when the cutter pulse reference is correctly adjusted, light is starting to reflect from the leading edge of the strip 94. This instant is the time t shown in FIG. 5a, Continued motion of the shaft 90 causes light to be reflected until time Several strips of reflecting tape may be placed on the shaft 90. For example, if the cutter 20 cuts three cigarettes for every revolution of the shaft 90, three strips 94 of equal length may be spaced apart on the periphery of shaft 90. Other mechanical or electronic devices may be employed with substantially equal utility to provide the required cutter pulse time reference.

ALTERNATIVE EMBODIMENTS A different, useful result is obtained when the window provided by the reference pulse 102 is established in time coincidence with the dense region pulse as shown in FIG. 7a. When the reference pulse 102 starts at time t an average value different from zero is computed by the signal inverting or differencing action of demodulator 60 and the averaging action of resistor 84 and capacitor 88. This is shown graphically in FIG. 7b. It may be observed that the average value computed is primarily a function of the amplitude of the dense region pulses l 16, since the average of the random densities in the remainder of the signal is substantially zero. The reference pulse 102 is deliberately shifted in time to include the dense region pulse 116 by displacing the housing 110 (FIG. 6) counterclockwise through a mechanical angle 0 which corresponds to the difference between the times t and If a 10 mm. dense end is placed on 70 mm. cigarettes the angle 6 may be computed, for the apparatus shown in FIG. 6, as follows:

5 mm. 0 N O 0 120 X 8-5 n An operators control knob 118 may be coupled to the worm gear 114 to rotate the housing 110 through the angle 0. Knob 1 18 may be provided with a dial for selecting either one of two modes of operation of the synchronous detector 60, denoted Check 1 and Check 2. Alternatively, a servomechanism may make the necessary displacement automatically on demand.

When placed in Check 1 position, the system responds primarily to the deviation of the cutter 20 and dense regions R for synchronization. When the proper extra density is being placed in each dense region R, the output signal of detector 60 is directly proportional to the deviation of the cutter and dense regions from synchronization. Since the detector 60 is somewhat amplitude sensitive, a change in the magnitude of the density of the dense regions R may be reflected in the output signal. The detector 60 may be rendered insensitive to changes in dense region density by inserting a signal-limiting circuit such as a clipper 120 (FIG. 4) in the path of the density signal, for example. Alternatively, clipping may be provided in the output circuit of the detector 60. The meter 82 always reads zero when the correct synchronization is provided irrespective of what changes occur in the magnitude of the density of the dense end regions R. It also displays in which direction the cutter and dense regions have fallen out of synchronization.

In the Check 2 position, our instrument responds not only to deviation but also to an undesired density of the dense regions R. The average value readout on meter 82 will be maximum if acceptable dense end cigarettes are being manufactured. If, for some reason or another, a deficient amount of tobacco is placed in the dense regions R, the indicated average value will decrease even though the machine may still be properly synchronized. If an out of sync condition prevails, the pulse 1 16 (FIG. 7a) is displaced relative to the pulse 102 causing the output signal to decrease in average value.

Referring to FIGS. 7c and 7d, when operated in Check 2 or peak reading mode, our detector 60 provides a signal for the dense end at the emitter of transistor Q, and a signal indicative of the density variation in the remainder of the cigarettes 22 appears at the emitter of transistor These signals are alternately clamped to ground (zero potential) at different times when one or the other of the transistors Q O is rendered conductive by the cutter reference pulse 102. These signals may be separately processed and evaluated for purposes of overall cigarette inventory or control by means not shown. It may be necessary to disable the clipper 120 by means of a switch 122 operated by the operators control knob 118 (FIG. 6) when the instrument is used in the peak reading mode.

What is claimed is: 1. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving along a path which includes the location of said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means for measuring the density of said tobacco rod as it passes a point along said path to produce a density signal having periodically varying portions indicative of the passage of each of said dense regions in said moving rod,

means for measuring the phase relationship between the operation of said cutter to cut said rod and the occurrence of said periodically varying portions in said density signal and for generating and coupling to said output device a signal directly proportional to the amount and direction of a deviation from the center of said dense regions of the ends of said cut cigarettes.

2. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means responsive to the density of said tobacco rod for generating a first signal having a periodically changing portion indicative of each of said dense regions in said moving rod,

means for generating a second signal whenever said cutter cuts a cigarette from said rod, and

means for continuously comparing the phase of said periodically changing portions of said first signal relative to said second signal and for producing and coupling to said output device a third signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said dense regions.

3. Apparatus for monitoring the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter along a path which includes the location of said cutter, said rod having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means responsive to the density of said rod as it passes a point along said path for generating a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod,

means synchronized with said cutter for producing a second signal corresponding to one portion of said first signal, and having a waveform that is inverted with respect to the waveform of said first signal, and

means responsive to said second signal and to another portion of said first signal to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes.

4. Apparatus for monitoring the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means for measuring said cigarette rod to provide a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod,

means synchronized with said cutter for periodically producing a second signal corresponding to one portion of said first signal and having a waveform that is inverted with respect to the waveform of said first signal for a predetermined period of time,

means for combining said second signal and said remaining portions of said first signal, and

means for averaging said combined signal portions to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes.

5. Apparatus for monitoring the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense-end forming device, said apparatus comprising: 1

means for generating a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod,

adjustable means coupled to said cutter for generating a reference signal having a pulse whose width is substantially equal to said periodic pulses,

means responsive to said reference pulse for periodically producing a second signal corresponding too one portion of said first signal, and having a waveform that is inverted with respect to the waveform of said first signal,

means for combining said second signal with the remaining portions of said first signal,

means for averaging said combined signal portions to obtain an output signal, and

means for adjusting said reference pulse generating means to initiate said reference pulse substantially in the center of each of said dense region pulses when said cutter and said dense end device are synchronized to provide an output signal directly proportional to any deviation of said dense regions from the ends of said cut cigarettes.

6. Apparatus as set forth in claim 5 further including:

means for adjusting said reference pulse generating means to change its time of operation relative to the operation of said cutter, thereby to initiate said reference pulse in time coincidence with the beginning of each of said dense region pulses to maximize said output signal when said dense regions are simultaneously of the desired magnitude and occurring in portions of said rod which are cut through by said cutter to separate adjacent cigarettes.

regions.

8. Apparatus for controlling the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense end device, said apparatus comprising:

means for continuously measuring the density of said cigarette rod to provide a signal having periodic increased portions responsive to the passage of said dense regions of said moving rod,

means coupled to said cutter to provide a reference pulse whenever a cigarette is cut from said cigarette rod,

synchronous detector means for producing a signal which is directly proportional to the phase difference of said measured increased density portions from said reference pulses, and control means responsive to said measured phase difference signal for continuously maintaining said cutter and said dense end device in synchronization to cut said cigarette rod substantially in the center of each of said dense regions.

9. Apparatus for monitoring the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco movable relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense end forming device, said apparatus comprising:

means for measuring the density of said cigarette rod to provide a first electrical signal having periodic pulses responsive to the passage of said dense regions of said moving rod, and

a phase detector for producing a signal indicative of a deviation from synchronization of the operation of said cutter and said dense end forming device wherein said cutter cuts said rod substantially in the center of each of said dense regions, said phase detector including a pair of electrical circuit loops each having a diode element for conducting current in one direction,

switch mans in series with said diode element and means for coupling said first signal to said phase detector,

a common load circuit shared by each of said loops and means for connecting said loops to said signal-coupling means to provide a current flow in each direction through said common load circuit and adjustable means coupling said switch means to said cutter for providing for a current flow of one loop or the other of said phase detector for predetermined periods synchronized with the operation of said cutter.

10. Apparatus as set forth in claim 9 further including: controller means responsive to said average current value for continuously maintaining said cutter and said dense end device in synchronization to cut said cigarette rod substantially in the center of each of said dense regions.

11. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means for measuring the density of said tobacco rod to produce a density signal having a waveform including a distinctive portion responsive to the occurrence of each of said dense regions in the vicinity of said cutter,

means for measuring the phase relationship between the operation of said cutter and the occurrence of said distinctive portions and for producing and coupling to said output device an output signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said dense regions.

12. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means for generating a first signal whenever one of said dense regions occurs at said cutter,

means for comparing the phase of said first signal relative to said second signal for producing and coupling to said output device an output signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said denser regions.

13. Apparatus for controlling the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising:

means for generating a first signal responsive to the passage of each of said dense regions in said moving rod,

means for generating a second signal each time said cutter cuts a cigarette from said rod,

means for comparing the phase of said first signal relative to said second signal for providing an output signal directly proportional to the amount and direction of any deviation of said cutter and said dense regions occurring thereat, and

control means responsive to said output signal for controlling the movement of said cutter relative to said tobacco rod.

14. Apparatus for controlling the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving along a path which includes the location of said cutter, said rod having locally dense regions spaced therealong, said apparatus comprising:

means synchronized with said cutter for producing a second signal corresponding to one portion of said first signal,

and having a waveform that is inverted with respect to the waveform of said first signal,

means responsive to said second signal and to another portion of said first signal to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes, and

15. Apparatus for controlling the operation of a cigarettemaking machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco having locally dense regions spaced along said tobacco rod and moving along a path which includes the location of said cutter, said apparatus comprising:

means responsive to the density of said rod as it passes a point along said path to provide a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod,

means for indicating the average value of said current flowing through said load circuit, and

means for adjusting said coupling between said cutter and said switch means to provide an average current flow that is substantially zero when said cutter is synchronized with said dense regions of said rod and directly proportional to any deviationfrom the center of said dense regions of the ends of said out cigarettes.

Claims

1. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving along a path which includes the location of said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising: means for measuring the density of said tobacco rod as it passes a point along said path to produce a density signal having periodically varying portions indicative of the passage of each of said dense regions in said moving rod, means for measuring the phase relationship between the operation of said cutter to cut said rod and the occurrence of said periodically varying portions in said density signal and for generating and coupling to said output device a signal directly proportional to the amount and direction of a deviation from the center of said dense regions of the ends of said cut cigarettes.

2. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising: means responsive to the density of said tobacco rod for generating a first signal having a periodically changing portion indicative of each of said dense regions in said moving rod, means for generating a second signal whenever said cutter cuts a cigarette from said rod, and means for continuously comparing the phase of said periodically changing portions of said first signal relative to said second signal and for producing and coupling to said output device a third signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said dense regions.

3. Apparatus for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter along a path which includes the location of said cutter, said rod having locally dense regions spaced along said tobacco rod, said apparatus comprising: means responsive to the density of said rod as it passes a point along said path for generating a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod, means synchronized with said cutter for producing a second signal corresponding to one portion of said first signal, and having a waveform that is inverted with respect to the waveform of said first signal, and means responsive to said second signal and to another portion of said first signal to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes.

4. Apparatus for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus compRising: means for measuring said cigarette rod to provide a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod, means synchronized with said cutter for periodically producing a second signal corresponding to one portion of said first signal and having a waveform that is inverted with respect to the waveform of said first signal for a predetermined period of time, means for combining said second signal and said remaining portions of said first signal, and means for averaging said combined signal portions to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes.

5. Apparatus for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense-end forming device, said apparatus comprising: means for generating a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod, adjustable means coupled to said cutter for generating a reference signal having a pulse whose width is substantially equal to said periodic pulses, means responsive to said reference pulse for periodically producing a second signal corresponding too one portion of said first signal, and having a waveform that is inverted with respect to the waveform of said first signal, means for combining said second signal with the remaining portions of said first signal, means for averaging said combined signal portions to obtain an output signal, and means for adjusting said reference pulse generating means to initiate said reference pulse substantially in the center of each of said dense region pulses when said cutter and said dense end device are synchronized to provide an output signal directly proportional to any deviation of said dense regions from the ends of said cut cigarettes.

6. Apparatus as set forth in claim 5 further including: means for adjusting said reference pulse generating means to change its time of operation relative to the operation of said cutter, thereby to initiate said reference pulse in time coincidence with the beginning of each of said dense region pulses to maximize said output signal when said dense regions are simultaneously of the desired magnitude and occurring in portions of said rod which are cut through by said cutter to separate adjacent cigarettes.

7. Apparatus as set forth in claim 5 further including: means responsive to said output signal for adjusting the relative position of said cutter and said dense end device to cut said cigarette rod substantially in the center of each of said dense regions.

8. Apparatus for controlling the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense end device, said apparatus comprising: means for continuously measuring the density of said cigarette rod to provide a signal having periodic increased portions responsive to the passage of said dense regions of said moving rod, means coupled to said cutter to provide a reference pulse whenever a cigarette is cut from said cigarette rod, synchronous detector means for producing a signal which is directly proportional to the phase difference of said measured increased density portions from said reference pulses, and control means responsive to said measured phase difference signal for continuously maintaining said cutter and said dense end device in synchronization to cut said cigarette rod substantially in the center of each of said dense regions.

9. Apparatus for monitoring the operation of a cigarette-making machine having a cutter provIding a plurality of cigarettes cut from a continuous rod of tobacco movable relative to said cutter and having locally dense regions spaced along said tobacco rod by a dense end forming device, said apparatus comprising: means for measuring the density of said cigarette rod to provide a first electrical signal having periodic pulses responsive to the passage of said dense regions of said moving rod, and a phase detector for producing a signal indicative of a deviation from synchronization of the operation of said cutter and said dense end forming device wherein said cutter cuts said rod substantially in the center of each of said dense regions, said phase detector including a pair of electrical circuit loops each having a diode element for conducting current in one direction, switch mans in series with said diode element and means for coupling said first signal to said phase detector, a common load circuit shared by each of said loops and means for connecting said loops to said signal-coupling means to provide a current flow in each direction through said common load circuit and adjustable means coupling said switch means to said cutter for providing for a current flow of one loop or the other of said phase detector for predetermined periods synchronized with the operation of said cutter.

11. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising: means for measuring the density of said tobacco rod to produce a density signal having a waveform including a distinctive portion responsive to the occurrence of each of said dense regions in the vicinity of said cutter, means for measuring the phase relationship between the operation of said cutter and the occurrence of said distinctive portions and for producing and coupling to said output device an output signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said dense regions.

12. Apparatus including an output device for monitoring the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising: means for generating a first signal whenever one of said dense regions occurs at said cutter, means for generating a second signal whenever said cutter cuts a cigarette from said rod, and means for comparing the phase of said first signal relative to said second signal for producing and coupling to said output device an output signal directly proportional to the amount and direction of any deviation from the ends of the cigarettes cut by said cutter of the center of said denser regions.

13. Apparatus for controlling the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving relative to said cutter and having locally dense regions spaced along said tobacco rod, said apparatus comprising: means for generating a first signal responsive to the passage of each of said dense regions in said moving rod, means for generating a second signal each time said cutter cuts a cigarette from said rod, means for comparing the phase of said first signal relative to said second signal for providing an output signal directly proportional to the amount and direction of any deviation of said cutter and said dense regions occurring thereat, and control means responsive to said output signal for controlling the movement of said cutter relative to said tobacco rod.

14. Apparatus for controlling the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco moving along a path which includes the location of said cutter, said rod having locally dense regions spaced therealong, said apparatus comprising: means responsive to the density of said rod as it passes a point along said path for generating a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod, means synchronized with said cutter for producing a second signal corresponding to one portion of said first signal, and having a waveform that is inverted with respect to the waveform of said first signal, means responsive to said second signal and to another portion of said first signal to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes, and control means responsive to said output signal for controlling the movement of said cutter relative to said tobacco rod.

15. Apparatus for controlling the operation of a cigarette-making machine having a cutter providing a plurality of cigarettes cut from a continuous rod of tobacco having locally dense regions spaced along said tobacco rod and moving along a path which includes the location of said cutter, said apparatus comprising: means responsive to the density of said rod as it passes a point along said path to provide a first signal having a waveform including periodic pulses indicative of the passage of said dense regions of said moving rod, means synchronized with said cutter for periodically producing a second signal corresponding to one portion of said first signal and having a waveform that is inverted with respect to the waveform of said first signal for a predetermined period of time, means for combining said second signal with the remaining portions of said first signal, means for averaging said combined signal portions to provide an output signal directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes, and control means responsive to said output signal for controlling the movement of said cutter relative to said tobacco rod.

16. Apparatus as in claim 9 in which said adjustable means comprises: means for indicating the average value of said current flowing through said load circuit, and means for adjusting said coupling between said cutter and said switch means to provide an average current flow that is substantially zero when said cutter is synchronized with said dense regions of said rod and directly proportional to any deviation from the center of said dense regions of the ends of said cut cigarettes.