Abstract: An apparatus is disclosed which detects the residual quantity of bobbin thread on a sewing machine bobbin when the shuttle containing the bobbin is located at a specific phase position. The apparatus includes a detection rod driven by a solenoid so that one end contacts the outer periphery of the residual bobbin thread. A sensor signals when the amount of residual thread is less than a predetermined quantity.

Abstract: A residual thread removing device detects an amount of thread left in a bobbin of a sewing machine. The bobbin exchange time setting means sets a time to exchange a bobbin set in the sewing machine with a new one to a bobbin exchange time at which an amount of thread providing a minimum of unusable thread is left in the bobbin, on the basis of the detected thread amount. With such an arrangement, a bobbin exchange time can be set to an optimal time at which a waste of the thread in a bobbin is minimized, irrespective of a kind of thread and/or thread count.

Abstract: Stitch quality monitoring system for use in combination with a sewing machine having one or more stitch threads and comprising sensor means for at least one of said one or more stitch threads for detecting thread motion during each sewing stitch cycle. Encoder means is operatively associated with the sewing machine for creating a predetermined constant number of sensor means sampling signals for each stitch cycle of the sewing machine, and circuit means is electrically connected to the sensor means and encoder means for detecting stitch defects during the formation of potentially defective stitches.

Abstract: A sewn seam monitoring system for evaluating selected characteristics of seam formed from a plurality of fabric plies is disclosed comprising a vertically displaceable wheel for compressing and monitoring the thickness of a seam being sewn as the seam passes therebeneath and a transducer operatively connected to the wheel to measure vertical movement and generate a signal corresponding to the vertical displacement of the wheel. Computer means is electrically connected to the transducer for analyzing the seam being sewn to detect any defects therein sensed by the wheel when in compressing contact with the seam passing therebeneath.

Abstract: A controlled needle tufting machine has a cyclically reciprocating latch bar to which the needles may be selectively latched in accordance with a pattern to reciprocate and insert loops of yarn into a backing material or to not be latched and remain stationary above the backing material includes yarn detection apparatus for determining whether the feeding of yarn for the needle is correct. The detection apparatus includes a yarn fault detector for detecting whether yarn is moving between a source and a respective needle and for providing a signal in response to such movement. The yarn movement signal is compared with a signal from the pattern control and if the needle is latched and yarn is supposed to be moving, a fault signal is provided if the yarn is not moving. If the needle is supposed to be stationary but the detector indicates that yarn is moving, a fault signal may also be provided. In either case the fault signal is displayed and the machine may be stopped.

Abstract: In a process and device for monitoring a residual amount of hook thread in a double thread lockstitch sewing machine, a bobbin is used, which is divided into a large clamber and a small chamber due to the arrangement of a middle flange, wherein the small chamber accommodates the residual amount of thread. An abrupt reduction in the speed of rotation of the bobbin, n.sub.S, takes place dating sewing at the time of the transition from the principal to the residual amount of thread as a consequence of the abrupt change in the thread pull-off site in the bobbin.

Abstract: A catch thread device is provided for a sewing machine with a scanning element controlled by the upper thread in the rhythm of sewing. The scanning element triggers a signal for the operator and/or for switching off the drive of the sewing machine via an electronic control circuit in the case of a thread break. The catch thread device includes a support fastened to the housing in the sewing machine as well as a pivotable switching lever. The pivotable switching lever is pretensioned and mounted in the support and is connected to the scanning element extending into the course of the upper thread between an eye of the needle and a thread guide of a thread lever of the sewing machine. The scanning element is connected to a magnet which is arranged adjacent to a Hall IC (integrated circuit) fastened to the support wherein the Hall IC is connected via lines to the control circuit for evaluating the signals triggered by the magnet in the Hall IC during the movement of the switching element.

Abstract: A device, preferably of disc configuration, capable of being fastened to a bobbin-less coil of thread for indicating the non-rotation of the coil during a sewing operation. One side of the device includes indicating means enabling the optical detection of the rotation of the device. The opposite side of the device includes fastening means, such as pins or adhesive, for fastening the device to a coil of thread, the fastening means being capable of disengaging from the coil when a predetermined length of thread remains therein.

Abstract: An automatic hemming machine, including a multi-belt conveyor, for folding the top edge of a pocket to be subsequently sewn on a shirt and hemming it with a back binding tape, severing the binding tape sewn on the pockets with a fast acting scissors type trimming assembly, and thereafter stacking a predetermined number of pockets after being fed off of the conveyor and returning one or more stacks in a bundle to an operator who does not have to leave the work station to unload the bundle from the machine.

Abstract: This invention relates to a method and apparatus for instantaneously monitoring the presence of properly and improperly formed needle thread stitches for all sewing machines with one or more needles at all operating speeds. An electronic control circuit connected to a high-speed synchronizer sensor and a high-speed thread sensor is provided which yields an instantaneous output of a desired duration when improper stitch formation occurs. The output from the electronic control circuit may be used to alert sewing machine operators in various ways of defective needle thread stitches.

Abstract: A sewing system including (A) a sewing device which includes (a) a sewing needle, (b) a first driver to reciprocate the needle, (c) a second driver to move the needle and a work sheet relative to each other in a direction crossing an axis line of the needle, and (d) a synchronizer to synchronize the reciprocation of the needle and the relative movement of the needle and work sheet, with each other, so as to form a series of stitches on the work sheet, (B) a detector associated with the sewing device to detect an abnormality of the sewing device, (C) a memory associated with the sewing device and the detector to store operation-state data indicative of an operation state of the sewing device upon detection of the abnormality, and (D) a utilizing device which utilizes the stored operation-state data for a control of the sewing system.

Abstract: Fastened to the bobbin for reception of the supply of looper thread which is inserted in the looper of a sewing machine, there is a data carrier (22) in which there is stored data which describe the supply of looper thread present on the bobbin with respect to the amount thereon and possibly also the nature of the sewing thread wound thereon. The data carrier is scanned by a sensor which preferably includes a first read/write head (27) and a second read/write head. After the winding of an empty bobbin, the data defining the supply of looper thread is recorded by said second read/write head in the data carrier of the said bobbin. After the sewing has been effected, the data defining the existing supply of looper thread is entered/read with the first read/write head in/from the data carrier of the corresponding bobbin. Thus, the bobbin provides information at any time as to the supply of looper thread present on it.

Abstract: An apparatus for measuring a remaining amount of a bobbin thread wound on a bobbin accommodated in a shuttle of a sewing machine, including a measurement bar displaceable along a displacement path from outside the shuttle toward an axis line of the bobbin inside the shuttle, a driver which displaces the measurement bar along the displacement path so that a free end of the bar contacts the outer surface of a roll of bobbin thread wound on the bobbin, a sensor which detects the displacement of the measurement bar and generates a displacement signal representative of continuous change in displacement amount of the bar, a signal-characteristic determining and storing device which determines a characteristic of the displacement signal based on respective values of the displacement signal when the measurement bar is located at a plurality of reference positions on the displacement path, and stores data indicative of the determined signal characteristic, and a remaining-amount determining device which determines the

Abstract: A sewing machine is disclosed in which an expenditure of lower thread is calculated from an expenditure of an upper thread. The expenditure of the upper thread is determined from the amount of rotation of a rotary tension disc. A pair of Hall elements deliver two phase signals, a phase difference therebetween is utilized to determine the direction of rotation, thus removing the likelihood of an error being caused by a rotation in the reverse direction. When the amount of leftover lower thread reduces below a given value, an alarm is issued. Where a plurality of needles are used, an expenditure of an upper thread is obtained for each tension disc, and the total expenditure is obtained.

Abstract: An apparatus for measuring a remaining amount of a bobbin thread which is wound around a bobbin accommodated in a shuttle of a sewing machine, including a measurement bar which is displaceable along a displacement path from outside the shuttle toward an axis line of the bobbin inside the shuttle, a measurement-bar driver which displaces the measurement bar along the displacement path so that a free end of the measurement bar contacts an outer surface of a roll of the bobbin thread remaining on the bobbin, a displacement-speed control device which controls the measurement-bar driver to displace the measurement bar such that the free end of the measurement bar contacts the outer surface of the roll of the bobbin thread at a speed lower than a highest speed of the displacement of the bar along the displacement path, and a remaining-amount determining device which determines the remaining amount of the bobbin thread on the bobbin, based on an amount of the displacement of the measurement bar along the displacemen

Abstract: A process and device for monitoring the bobbin thread on stitch-forming machines, on the bobbin of which a residual amount of thread is wound in a winding direction opposite the direction of winding of the principal amount of thread, is to ensure that a first control function will be generated at the beginning of consumption of the residual amount of thread, and a second control function is generated nearly without delay in the case of thread end or thread break. To achieve this, two signal patterns are received with a phase shift from a bobbin acting as a signal generator, and the first signal function is generated in the case of a deviation of the actual phase shift from the desired phase shift. If only one signal pattern is received, this first control function is also generated if its signal sequence deviates from a reference signal sequence. The second control function is generated if a stoppage of the bobbin lasts longer than a predeterminable number of stitches.

Abstract: A stitch forming machine is provided including a transducer for determining the tension present in a thread, wherein the thread tension assumes a higher value during stitch formation and the transducer provides a signal representing the tension level. The control is provided for evaluating the signal corresponding to the tension level. The control includes a comparator device for comparing a peak of the signal representing the tension level, which peak can be used to detect a malfunction, with a limit signal, corresponding to a limit tension. The comparator sends a signal to a switching device when a signal peak drops below the limit signal. The switching device may be connected to a shut-off device of the drive motor of the machine as well as one or more display elements. In this way, the machine may be stopped and the display element associated with a limit tension, below which the tension dropped by a switching device.

Abstract: Apparatus and method for detecting skipped stitches for chainstitch sewing machines having a looper assembly using a needle thread movement sensor and/or a looper thread movement sensor in combination with a shaft rotation sensor. Needle thread movement is correlated with needle shaft rotation per stitch cycle to detect instances when there is no needle thread movement during a stitch cycle. Similarly, looper thread movement may be correlated with needle shaft rotation per stitch cycle to detect instances when there is no looper thread movement during a stitch cycle. The invention includes methods for detecting needle loop and triangle skips by detecting instances of substantially no needle thread or looper thread movement during certain respective portions of the stitch cycle.

Abstract: A bobbin thread remainder detecting device for detecting an amount of remainder of a bobbin thread wound up around a bobbin for a sewing machine, in which a winding leading end portion of the bobbin in a winding direction reverse to a winding direction of another portion of the bobbin thread, comprises a bobbin rotating direction detecting unit, including light emitting and receiving elements, disposed in a vicinity of a bobbin case for detecting a rotating direction of the bobbin and a bobbin thread remainder detecting unit, including an electronic control circuit element, disposed in association with the rotating direction detecting unit for detecting the amount of the remainder of the bobbin thread in response to rotation of the bobbin in a particular direction as detected by the rotating detecting unit. The bobbin thread remainder detecting unit detects reducing the bobbin thread remainder wound up around the bobbin at a time when the rotating direction of the bobbin changes.

Abstract: A residual bobbin thread amount detection apparatus for a sewing machine which includes a hook rotating in association with a main shaft of the sewing machine and a bobbin rotatably mounted on the hook. A first detector detects the rotation speed of the main shaft and a second detector detects the rotation speed of the bobbin. A comparator responsive to the second detector generates a signal when the rotation speed of the bobbin exceeds a predetermined value, whereby a controller operates an alarm.

Abstract: A sewing machine is provided with a device for stopping the drive in the case of a thread disturbance. The device has a light source, a first light guide device for transmitting the light beams to the monitoring point, a second light guide device, via which a signal can be sent to a receiver in the absence of thread at the monitoring point, and a control unit for signal evaluation and to report a thread disturbance, even in the case of maximum deflection of the thread at right angles to the pull-off direction, only when a thread disturbance does really exist. To achieve this, the first light guide device is designed, on its side facing the thread, in a plane perpendicular to the thread pull-off direction, with a radiation outlet which extends preferably in the horizontal direction. The first light guide device causes light beams to be sent over the maximum range of movement of the thread at equal radiation intensity over an entire radiation cross section.

Abstract: Sewing apparatus comprises a sewing needle, a bobbin for feeding thread to the sewing needle, a rotary housing containing the bobbin and its case a sensor for sensing the non-feeding of thread to the sewing needle; an extraction-reloading device automatically effective, upon sensing the non-feeding of the thread to the sewing needle, for first extracting the bobbin and its case from the rotary housing, then extracting the bobbin from its case, then reloading the case with another bobbin having a supply of thread thereon and then returning the case with its reloaded bobbin into the rotary housing.

Abstract: Apparatus for detecting skipped stitches for sewing machines having a bobbin-type assembly using a thread movement sensor for continuous monitoring of the presence of a needle thread in a beam path. Needle thread movement is correlated with needle shaft rotation per stitch cycle to detect instances when there is no thread movement during a stitch cycle. The apparatus may also include a bobbin thread monitor system to detect residual bobbin thread.

Abstract: To recognize missed stitches during the operation of a sewing machine, a function, which represents the tensile force of a thread fed into a stitch-forming device depending on the angle of rotation of the main shaft, is scanned in its entirety during each revolution period of the main shaft for selected characteristics without regard to the location of this characteristic within the revolution period. The characteristics found are measured in order to obtain for each characteristic an analytical value that is compared with the corresponding analytical value from at least the last preceding revolution period to form the difference of the two analytical values. If this difference exceeds a predeterminable value, a decision corresponding to a missed stitch is made.

Abstract: According to a sewing machine with a bobbin thread monitor, the light emitted from a luminescence element is reflected by a bobbin thread or a rotating hook bobbin and received by a light receiving element. The light receiving element outputs the detection signal according to an amount of thread remaining on the bobbin based on the reflection light. A color sensor detects the wave length of the color of the bobbin thread and outputs the signal according to the result of the detection. A CPU corrects the detection signal output from the light receiving element based on the signal output from the color sensor so that the amount of thread remaining on the bobbin is detected.

Abstract: A sewing machine comprising a sewing machine lamp for illuminating an area around an end of a sewing needle, and a plurality of color filters provided on a rotary disk which is rotated by a stepping motor so that the area around the end of the sewing needle is illuminated by light of a selected one of a plurality of different colors. When an abnormal condition detector for detecting an erroneous operation or an abnormal condition such as an accident of the sewing machine detects an abnormal condition, an abnormal condition warning device changes the color of the illuminating light to a color corresponding to a type of the abnormal condition.

Abstract: The invention is a method and apparatus for detecting a skipped stitch for a Class 301 lockstitch sewing machine. A monitor assembly determines the passage of the needle thread about the bobbin assembly during formation of lockstitches. A second monitor assembly determines the reciprocal movement of the needle by detecting rotation of a shaft which drives the needle. A processor identifies times when the rotational movement of the shaft does not correlate with passage of the needle thread about the bobbin assembly.

Abstract: A tight end detector for tufting machines is disclosed which includes a modular switch bar assembly, a switch contact forming PC board thereon having a conductive stripe, insulating strip, a leaf-metal electrical contact member having parallel contact finger formations overlying the conductive stripe of the PC board and a thin cover layer overlying the bar, PC board, insulating strip, and electrical contact member to provide a wear surface against which yarn ends of the tufting machine may bear.

Abstract: An amount of a lower thread to be supplied from a bobbin in each stitch forming operation is first determined on a theoretical basis in accordance with the stitch control data stored in a pattern memory. The sewing machine is provided with a bobbin rotation detector which detects every rotation of the bobbin to estimate a lower thread amount which has actually been supplied from the bobbin. A control unit compares the theoretical amount and the practical amount to lead out a correction coefficient which will be applied to the theoretical amount for the next stitch forming operation.

Abstract: A device on a sewing machine for controlling the tensile stress (F) applied to a thread as it is being fed in the sewing process, including a device for producing a frictional force acting on the thread, a setting member, a force-measuring device, and a control unit for controlling the tensile stress (F) in the thread. The setting member functions commonly as the force measurement sensor and the force-applying device.

Abstract: Thread monitor for monitoring double lock stitch shuttles or hooks and chain stitch machine shuttles or loopers. During normal operation of the sewing machine, the shuttle thread is used as a reflection surface. The scattered light beams reflected by the thread enter photodetector 10 of the thread monitor 8. If the support surface 7, 28 is covered by thread, light beams will reach said photodetector 10, as a result of which a control circuit 12 connected to it issues a warning signal.

Abstract: In an apparatus for detecting and displaying a residual quantity of lower or under thread (12) of a sewing machine, an under-thread bobbin (10) is provided with transparent flange portions (10a) permitting the light rays emitted from a light emitting device of a photosensor (19) to pass through the flange portions (10a ) of the bobbin (10). The light rays having passed through the bobbin (10) are then reflected by a reflecting means or mirror (21) affixed to a back surface of a bed of the sewing machine to impinge on a light receiving device of the photosensor (19) so that the photosensor (19) detects the residual quantity of the lower thread (12) of the sewing machine. In the photosensor (19), the light emitting device is integrally formed with the light receiving device to save space.

Abstract: A needle thread feeding assembly in which the thread is positively fed at a desired stitch pitch while being clamped in between a presser roller and a drive roller, whose rotation is frictionally transmitted from a drive source. An encoder detects a predetermined amount of rotation and signals to restrict the drive roller, while allowing the drive shaft to continue rotating. A main-shaft-angle-detector detects predetermined angles adapted to operate the required stitch pitch and to start counting of pulses at the encoder. When a required number of pulses corresponding to the stitch-pitch is counted, the encoder signals to restrict the drive roller. Thus, the needle thread is positively and intermittently fed according to the stitch pitch.

Abstract: A method of supplying a thread to a sewing machine from a reel wherein the thread is supplied by carrying on a hanger a loop produced between the reel and the sewing machine by twisting the thread two to three times. The hanger used in supplying the thread comprises a case body, a cylindrical dial partly exposed on the surface of the case body, and a hook projecting from the case body to catch the thread. The hook is coupled through gearing to the dial and is rotatable in response to rotation of the dial.

Abstract: A method and apparatus for detecting an improper stitch for a Class 400 chainstitch sewing machine. A monitor assembly determines the consumption per stitch of the looper thread during the formation of the chainstitches. A processor identifies times when the monitored consumption is indicative of looper thread consumption per stitch below a predetermined threshold value. Since the consumption per stitch for looper thread is nominally a predetermined multiple of the stitch length, those identified times correspond to times when improper stitches have occurred.

Abstract: A tufting machine having a broken yarn detector including a multiplicity of yarn engaging fingers mounted in a support block secured to the frame of the tufting machine. Each finger has an eyelet at one end for receiving a strand of yarn and is pivotably mounted on a rod externally of the mounting block so that the fingers may be supported by the yarn in a raised position during normal operation, but pivotably drops when the yarn is broken. The rod is secured in position by a number of clamping blocks attached to the mounting block, the clamping blocks also having slots aligned with the slots in the mounting block at the location where the clamping blocks are secured for receiving the external ends of the fingers so as not to impede the pivotable movement. A light generator and a photoconductive receiver are mounted for detecting when a finger drops, the finger interrupting the transmission of the light beam to provide a signal which may be used to stop the tufting machine.

Abstract: A detecting electrode is mounted on the path of a thread in a sewing machine. When a cloth is sewn in the sewing machine, a bobbin thread or a needle thread moves spatially against the detecting electrode. An electric signal is obtained on the detecting electrode in response to such movement of the thread. On the other hand, a timing signal generator generates a timing signal synchronous with the vertical movement of the needle in the sewing machine. A discriminator receives the electrical signal from the detecting electrode and the timing signal from the timing signal generator. The discriminator compares the electric signal with a reference signal when it receives the timing signal and outputs a discrimination signal in accordance with the result of the comparison.

Abstract: Disclosed in a feeding control device for a plurality of threads in a sewing machine of the type wherein a set of a feed roller and a pressure roller are rotated forcibly at the same peripheral speed independently of the number of revolutions of a main drive shaft of the sewing machine so that a plurality of threads can be fed while the travel of each thread is controlled by each thread holding device. The present invention eliminates the necessity of securing high parallelism between both rollers to prevent their joint rotation, makes it possible to use a wear-resistant material for the pressure roller and can reduce breakage and damage of the thread due to friction with the rollers that are always rotating, at the time of stop of the thread.

Abstract: A sewing machine thread break detector using a photo amplifier in which thread to be monitored is guided relatively to a light beam so that thread movement will vary transmitted light. An electronic circuit signals thread breakage when uniformity of the transmitted light beam indicates thread motion has ceased during sewing machine operation.

Abstract: An optical low bobbin thread detector is disclosed utilizing particularly cost effective matrixed light emitting diodes for bobbin thread detection and alarm, and virtually eliminating false alarms by employing a system requiring detection of a predetermined number of successive valid low bobbin thread detections to justify actuation of the alarm.

Abstract: A sewing machine having a thread monitor associated with a bobbin mounted for rotation. The bobbin includes first and second reflecting surfaces associated with an inner side of a second bobbin flange, and first and second light outlet openings associated with a second bobbin flange. A light source is provided for directing light toward the reflecting surfaces. A light receiver is positioned so as to receive light emerging from the first and second outlet opening. The light receiver produces signals representing the light intensity received by the light receiver. A Schmitt trigger provides a pulse to a microprocessor coinciding with a revolution of the bobbin. For each revolution of the bobbin, an A/D converter converts signals received from the light receiver into digital signals which are compared. The digital signal having the maximum value for the revolution is stored in a memory and then compared with a subsequent maximum value.

Abstract: A fiberoptic bundle has one end disposed in the bed of a sewing machine in opposition to the stitch formation region below the throatplate. A strobe light for periodically illuminating the region and a camera for recording visual images of the region are coupled to the opposite end of the fiberoptic bundle. The end of the fiberoptic bundle within the sewing machine bed may be provided in guidepaths for viewing the stitch formation region from different viewing directions, preferably 90.degree. apart. A load cell is disposed on the side of the sewing machine for recording tension transients in the thread en route to the needle.

Abstract: An automatic thread tensioning device for positioning the crossing points of upper and lower threads in the center of thickness of a fabric undergoing stitching. The positioning is effected by making calculations based on measured results of thread tension, without needing to detect the various kinds of characteristics of fabrics, threads, or lower thread tension responding to an existing type of stitching condition. The proper upper thread tension may be determined for the stitching conditions of fabrics which have different characteristics and for stitching conditions of fabrics which have conventionally been difficult to deal with, simply by pressing buttons and making test stitchings. If an upper thread tensioning device has a motor, a stitching operation may be made more easily.

Abstract: Herein disclosed is a material feeder of a sewing machine, which comprises a first mechanism which draws a predetermined length of a narrow and long material from a bobbin when actuated, and a second mechanism which actuates the first mechanism when the length of the material drawn from the bobbin is reduced to a predetermined degree.

Abstract: An apparatus for feeding thread for a sewing machine comprising a thread feeding system for guiding the thread (14) from a spool (13) to a take-up lever (2) of the sewing machine (A). The thread feeding device is comprised of a pressure roller (10) and a feed roller (8) driven by a motor, an encoding device (17) installed on the main drive shaft of the sewing machine, an encoder (8a) for measuring the length of the thread fed, and a thread holding device (11), whereby when the encoding device (17) gives the signal to the thread holding device to release the thread, the thread feeding device feeds the thread for completing one full stitch, and the encoder (8a) actuates the thread holding device (11) to hold the thread during the stitching.

Abstract: An apparatus for monitoring one or more threads in a sewing machine with a number of sewing heads, the signal emitter including a spring arm (2) which is fixedly anchored at its one end (3) and, at its opposite end, carries a magnet (9), this opposite end being moreover located in the path of movement of the lower thread (12) in order to be influenced by same and thereby change the position of the magnet (9) in relation to an element (10) sensitive to the position of the magnet (9) and generating an electric signal in dependence upon the position of the magnet (9), the signal change being sensed and evaluated.

Abstract: A solar cell powered detecting and indicating system applicable to mechanically controlled sewing machines without D.C. power supplies connected to regular A.C. house mains, and detecting and indicating circuits minimizing power consumption for compatability with solar generated power supply.

Abstract: A thread break detector for a thread in a sewing machine comprising, a sensor device having a signal path cross section for scanning, a first thread guide disposed on one side of the sensor device, and a second thread guide disposed on the other side of the sensor device and being movable in synchronism with the stitch formation of the sewing machine, such that the second thread guide deflects the thread in the region of the sensor device a greater amount than the cross section of the sensor device signal path.

Abstract: A sewing machine with a lockstitch rotary hook containing a bobbin, has a thread monitor with which light signals of a radiation source are conducted to a light receiver via inlet and outlet openings in parts of the rotary hook and in at least one of the flanges of the bobbin. For determination of a predeterminable thread and length, the hub which connects the flanges of the bobbin comprises a truncated cone-shaped region, in the surface of which the outlet opening extending substantially parallel to the axis of the hub ends.

Abstract: A bag closing container device applies a strip of closure tape to a container, and sews stitches through the tape and container walls, as the container is moved past a closure station. A first sensor, located near an encoder disc driven by the container transport motor, generates a signal proportional to the container transport speed. An idler roller frictionally engaged with the closure tape carries an indicator wheel, which generates in a second sensor a signal proportional to the tape speed. The thread used in stitching the containers is wrapped around a detector wheel on its way to the closure station, and is frictionally engaged with the wheel. Wheel rotation generates in a third sensor a signal proportional to thread speed. The device includes a microprocessor which receives the signals as inputs, continually compares container transport speed and thread speed, and generates a thread fault indication if the thread and container speeds deviate from a preselected ratio.