Abstract: An arrangement for monitoring the shuttle thread reserve in a sewing machine with a lockstitch revolving shuttle and with a light-emitting diode, which sends a beam of light through openings in the bobbin housing and in the bobbin to a photodetector which triggers a switching pulse for an actuating device. To obtain maximum utilization of the residual thread, the photodetector is used at the same time as a pulse generator for a counter which controls the actuating device. The counter can be connected to a switch-off device of a drive motor for the sewing machine.

Abstract: A device for detecting the residual amount of bobbin thread in a lock stitch sewing machine is arranged such that a detector detect the number of rotations of an arm shaft or oscillating shaft, or the number of cycles of vertically reciprocating movement of a needle bar of a lock stitch sewing machine including the arm shaft, and oscillating shaft, and needle bar. The detector provides an output for the detected of rotations. The residual amount of bobbin thread wound on a bobbin in a bobbin case is then detected based on the detected number of rotation output. The detected residual amount of bobbin thread is then compared with a predetermined value which is predetermined in dependence on conditions such as the thread and needle to be employed, and the workpiece.

Abstract: A bobbin run-out detector for a lockstitch sewing machine is responsive to thread tension for sensing when the bobbin is empty of thread. The thread tension is sensed by a hook member (168; 332) engageable with the thread extending from the bobbin, the hook member (168; 332) being moved by a resilient bias as a result of loss of thread tension consequent on emptying of the bobbin. The hook member (168; 332) is linked to a shutter (174; 334) which moves with the hook member (168; 332) in order to influence a light beam, light receiving means (202) being responsive to such influence to produce a signal indicative of bobbin run-out. The signal may stop the machine and/or actuate an alarm. Alternatively, the signal may actuate a bobbin change device (2, 4, 14, 16) for removing the empty bobbin and for inserting a previously wound bobbin, to permit sewing to resume.

Abstract: The invention relates to an apparatus for feeding thread in a sewing machine. The apparatus includes a thread feeding pass, a base tension disc, a thread holding device, an encoder, and a thread feeding device. The thread feeding device includes a presser roller and a feeding roller driven synchronously with a sewing needle. When a predetermined length of thread is fed to a thread take-up lever, the thread holding device is actuated to hold and stop the thread without stopping rotation of the thread feeding rollers such that the thread slips on the feeding rollers.

Abstract: An optical thread breakage monitoring apparatus for tufting machines contains a laser (36), a mirror wheel (17) which is illuminated by the laser and also a plurality of spaced apart strip-like deflecting mirrors (23, 11, 12) which direct the laser light which is cyclically deflected by the mirror wheel (17) onto a horizontally disposed concave mirror (13) which is arranged above the mirror wheel (17) and the deflecting mirrors (11, 12) and which forms the scanning beam (20'") which is directed towards the row of needles (14) of the tufting machine. A retroreflecting strip (15) is arranged behind the row of needles (14). The receipt of the light reflected from the retroreflecting strip (15) takes place in autocollimation (FIG. 1).

Abstract: A drive control mechanism and a safety device in a sewing machine in which thread in a predetermined amount necessary for the formation of one seam each time a seam is to be formed. The drive control mechanism comprises a control circuit for allowing current to flow to a machine motor when no thread amount signal is produced though a position signal is produced at the start of the machine. The safety device comprises a thread paying-out detection circuit operable when a position signal is produced, but no thread amount signal is produced, an alarm for producing a sound or light warning in response to the operation of the thread paying-out detection circuit and a motor stop circuit for interrupting flow of current to a machine motor.

Abstract: A thread monitor device for a textile machine to monitor thread feed through a region of a machine, the device including a source of light, means to convey the light to a thread feed region, and to direct light into said region, means to receive light directed into said region from said source and produce a monitor signal representative of said received light, means responsive to said monitor signal and to changes therein to indicate the occurrence of a change in said signal representative of a change in thread feed in the region.

Abstract: A thread feed device in a sewing machine is disclosed herein. The device comprises a thread paying-out member positioned in the thread path between the bobbin and needle, a pair of holding means positioned upstream and downstream of the paying-out member in the thread path and a control circuit for controlling of the operation of the holding means.

Abstract: The needle thread-break monitor for embroidery machines comprises a double-armed rocking lever acting as a switch in an electrical circuit of an alarm system. The rocking lever is mounted on a bearing shaft forming one pole or terminal of the switch. The other pole or terminal of the switch is formed by a limit or abutment shaft arranged substantially vertically above and extending substantially parallel to the bearing shaft. The arm of the rocking lever not having a thread guide cooperates with the limit shaft, which carries a sleeve of electrically insulating material forming a stop limiting the open position of the switch. The arm of the rocking lever having a thread guide cooperates with the sleeve. The sleeve is rotatable between a terminal or limit position on the terminal or limit shaft enabling electrical contact and another limit position inhibiting electrical contact. The sleeve serves as a support for a needle thread in the relaxed or non-tensioned state.

Abstract: A signal arrangement for supplying a signal as a prewarning to the operator of a sewing machine, when the bobbin thread is about to run out. The bobbin has a reflective center, and a radiation source and detectors are mounted in the loop-taker. A friction clutch may be provided between the bobbin and the loop-taker, so that the bobbin rotates in one direction when thread is wound thereon, and the other direction when all of the thread has unwound therefrom.

Abstract: A thread feed mechanism in a sewing machine for paying-out thread in a predetermined amount necessary for forming one seam. The thread feed mechanism comprises a first signal generation device for producing feed amount and needle bar amplitude signals, a second signal generation device for producing a workpiece thickness signal, first means for adding square values of feed amount and amplitude signals, second means for multiplying a square root of the first means by a coefficient, third means for producing a signal varying depending upon the operation mode thereof, fourth means for multiplying a workpiece thickness signal by the output of the third means, and fifth means for adding the outputs of the second, third and fourth means.

Abstract: A laser beam scanning device (17) is provided for monitoring for thread breakage in tufting machines (31) in which a carrier web (16) is passed from below to a spiked roller (11) and is deflected by the spiked roller into a substantially horizontal direction so that it can be passed beneath a row of needles (12). The row of needles (12) periodically introduce threads into the carrier web (16) by up and down movement in order to form tufted material. A narrow retro-reflecting strip (14) is arranged directly below and behind the tips of the needles and directly above the tufted material (15) parallel to the row of needles (12) and substantially at right angles to the surface of the tufted material.

Abstract: A tufting machine has a broken yarn detector mounted intermediate the yarn feed mechanism and the needles, the detector having a multiplicity of yarn engaging fingers pivotably mounted in a support housing secured to a frame carried by the tufting machine. Each finger has an eyelet for receiving a strand of yarn which during normal operation of the tufting machine supports the finger in a raised position, but which drops when the yarn is broken. A signal generator and a signal receiver in the form of a light source and a photo-conductive receiver respectively are carried by the frame of the broken yarn detector at a disposition such that when a finger drops it interrupts the transmission of the light beam from the transmitter to the receiver to provide a signal which may be used to stop the tufting machine.

Abstract: A diagnostic table which stores possible causes of certain abnormal conditions is accessed by corresponding push buttons for sequential vocalization by a sewing machine system, thereby helping the operator check the machine.

Abstract: A monitoring device for monitoring a low thread supply in a sewing machine comprises a light emitter and light receiver positioned on opposite ends of a rotary hook in the sewing machine. The sewing machine is equipped with the rotary hook, a bobbin case, a bobbin in the bobbin case for carrying the thread and a drive shaft for rotating the rotary hook or which rotates as a function of rotation of the rotary hook. A pulse transmitter is connected to the drive shaft which supplies pulses to a control circuit connected to the light emitter. The control circuit, responsive to the pulses, activates the light emitter only during intervals at which apertures in the rotary hook, the case and the bobbin are aligned. Light passing through the aligned apertures indicates whether there is a low supply of thread on the bobbin.

Abstract: Yarn break in a short seam sewing machine is determined by detection of yarn swinging and wherein the sewing machine is stopped in response to the detection.

Abstract: An optical switching arrangement for a sewing machine when used as a low bobbin thread detection and indicating system utilizes an infra-red light emitting diode and a phototransistor arranged on opposite sides of the bobbin so that an amount of bobbin thread greater than a predetermined threshold interrupts the light path from the light emitting diode to the phototransistor. A single integrated circuit chip is utilized to modulate the emission from the light emitting diode and to demodulate the output of the phototransistor to differentiate the detected emission from ambient radiation. The same basic configuration is also applied to an optical buttonhole switching arrangement.

Abstract: An automatic thread regulating system having an adjustment mechanism for controlling the thread feed and takeup during the formation of a sewing machine stitch. A central processing unit calculates the length of thread required for a specific stitch formation based on work piece thickness and stitch length. This information is directed to the adjustment mechanism which thereby regulates the appropriate thread amount by feed rolls and a suction apparatus.

Abstract: A bobbin thread level detection and display arrangement for a sewing machine includes an array of light emitting diodes which are activated to convey to the sewing machine operator an indication of the quantity of thread left of the bobbin. To control the light emitting diodes, an arrangement utilizing a light source and a phototransistor is arranged proximate the bobbin. The circuitry for controlling the activation of the light emitting diodes also provides for a "fading in" of the individual light emitting diodes to provide a display in the nature of a bar graph.

Abstract: A device for automatically adjusting the tension of a lower thread, which comprises a lower thread bobbin arranged on a bottom plate of a bobbin carrier turnably carrying the bobbin, a loop taker mounted on a magnetic shaft, and an energizing coil arranged around the magnetic shaft and providing together with said bottom plate and magnetic shaft a path of magnetic flux. The device is further provided with a detector detecting the consumed amount of the bobbin thread and a control circuit for energizing the coil when the lower thread is wound to the maximum capacity of the bobbin, interrupting the light of the detector. The detector operates the control circuit to decrease the amount of electric current applied to the energizing coil so as to set the lower thread tension back to its initial predetermined value.

Abstract: The invention is to provide an electrical indication of improper thread tension to enable the sewing operation to be exactly accomplished.

Abstract: A yarn tension detector having a cage-like form pivotably moveable between predetermined limits about the pivot point and under the control of the tension of a moving yarn. The detector includes a pair of spaced abutment members in an electrical circuit with a lamp. The cage-like member makes a circuit whenever it engages one or the other of the abutments to thereby cause the bulb to light. The member also includes oppositely directed guide formations about which a yarn is trained and as the yarn is fed from a creel to, for example, a tufting machine the tension in the yarn as it moves through the guide formations pivots the member. One of the guide formations progressively opens when the yarn tension is in excess of a predetermined high tension to release the yarn from the detector after it has indicated the yarn tension fault.

Abstract: A sewing machine having a rotary hook shaft, a bobbin case with a hollow cylindrical shaft journalled through the rotary hook shaft, and a bobbin rotatably mounted on the shaft of the bobbin case. An axially spring-biased cylindrical member is provided for unitary rotation with the bobbin and axially movable between a first position in which it is held against the lateral edges of the thread layers when the latter is present through the length of the cylinder of the bobbin and a second position in which the thread layers have reduced to a predetermined radial extent. A detector is provided to sense the axial movement of the spring-biased cylinder member from the first to second positions.

Abstract: A thread monitoring device for monitoring the thread supply in a sewing machine, having a rotary hook, comprises, a hook body with a thread bobbin having thread thereon which is connected to a rotatable shaft for rotation thereby. The hook includes a stationary bobbin case which is enclosed by a hook body which has a hub portion connected to the shaft. A light source is disposed on one side of the hook and a light receiver is disposed on the opposite side. Light is transmitted by the light source through a path intercepting the thread on the bobbin so that, when the thread on the bobbin is paid out during the stitching operation, beyond a predetermined amount, the light will be transmitted to a reflective wall portion of the hook body and deflected by the wall portion to the light receiver. The light receiver is connected in a control circuit to operate a control for operating the sewing machine or for actuating an indicator to show that the thread has been used up to the predetermined amount.

Abstract: A sewing machine is provided with an actuator controlled thread take-up lever. A microprocessor is programmed to provide signals for controlling the actuator to provide a system wherein the interaction of the needle, the needle thread take-up and needle thread tension are optimally controlled. A thread metering mechanism, also under microprocessor control, is included in the system.

Abstract: A holder containing the light detector of the low bobbin thread detection system of a sewing machine and including a light admitting aperture through which light may pass to a photodetector is provided with a plastic tubular collar which extends over the aperture and serves both as a shield to keep lint out of the aperture and as a lens to focus light on a light sensitive surface in the photodetector.

Abstract: A bobbin alarm for a sewing machine which utilizes a light source and a pair of light sensors to provide a warning of low bobbin thread remaining or of a full bobbin condition. The light sensors are arranged with respect to the light source so that one sensor lies substantially on a line from the light source tangent to the hub of the bobbin and the other sensor lies substantially on a line from the light source tangent to the periphery of an imaginary cylinder having the bobbin flanges as the ends thereof. A circuit is provided which is responsive to light stimulation of both sensors (empty bobbin condition) or no stimulation of both sensors (full bobbin condition) to provide a signal to an operator in the form of an illuminated LED.

Abstract: A drive control system for stopping a sewing machine when a thread of the sewing machine is broken or tangled. The system comprises rotational speed meter circuits, each one of which is coupled with respective thread tension disk means which rotate in synchronism due to movement of threads on them. A deceleration of the rotation of one of the thread tension disk means is detected by a rotational speed meter circuit coupled with it. An electric logic circuit in the system, which is energized to drive the sewing machine in response to a closure of a start switch and deenergized to stop the sewing machine in response to a closure of a stop switch, is deenergized to stop the sewing machine in response to the detection of the deceleration of the rotation of one of the rotary disks.

Abstract: A programmable bobbin thread detector which generates a signal when the amount of thread remaining on a bobbin is sufficient to complete only one more seam. At the beginning of each operation, the operator sews a complete seam with a full bobbin and the number of bobbin revolutions are stored in a first counter. The operator then fills a new bobbin. Each turn of the bobbin during the winding operation is detected and increments a second counter until its contents correspond to the total number of thread revolutions on the new bobbin minus the number of revolutions necessary to complete one seam. The complement of this number is loaded into a third counter. During subsequent sewing operations using a new bobbin, a third counter is incremented with each revolution of the bobbin, and an alarm is generated when the third counter reaches a predetermined state.

Abstract: A light detector is supported in a mask box which extends into the cavity accommodating the looptaker with an edge of the surface adjacent the looptaker and upstream to the air currents generated by the looptaker closer to the looptaker than an edge downstream in order to discourage lint build up on the adjacent surface. A light source is fashioned with a lens projecting into the cavity accommodating the looptaker similarly to discourage lint build up.

Abstract: A low bobbin thread detection system for sewing machines. A light source transmits a beam of light through a pair of passageways contained in the bobbin case and toward a photodetector enclosed in a shield to shelter it from stray light. The light shield contains a pair of spaced apertures whose axes are in optical alignment with the light source and the bobbin case passageways. The thread carrying bobbin lies intermediate the passageways and does not permit the transmission of light from the first to the second passageway while thread remains thereon. When sufficient thread has been consumed from the bobbin, light may pass from the light source to the photodetector. Light which is directed at the shield surrounding the photodetector from any angle other than that coincident with the optical axis formed by the two apertures is blocked from impinging on the photodetector and will not falsely trigger a low bobbin thread alarm.

Abstract: A bobbin thread run-out detector having a light source and means for directing a beam of light toward a set of retro-reflecting reflectors on the bobbin and toward a reference reflecting spot on the loop taker. Bobbin thread wound around the bobbin is interposed between the light source and the retro-reflecting reflectors. When a sufficient quantity of thread has been consumed to expose the indentations to the source of light, the light is reflected to a photodetector. Light from the source is also intermittently reflected onto the photodetector by the reflecting spot on the loop taker during each revolution of the loop taker. An electronic circuit compares the light received by the photodetector from the bobbin with the light received from the reflecting spot on the loop taker. When the quantity of light reflected from the bobbin changes relative to the quantity of light reflected from the loop taker a low bobbin thread alarm is activated to warn the operator of the impending exhaustion of bobbin thread.

Abstract: A low bobbin thread supply alarm in which a bobbin case is fitted with lever pivoted thereon and carrying a permanent magnet for travel to the hub of the bobbin. An arm overhanging the bobbin case and bobbin carries a Hall generator in a portion thereof overlying the hub of the bobbin. The lever and permanent magnet carried thereby is urged by an electromagnet supported externally of the looptaker toward and away from the hub of the bobbin at suitable intervals. When the lever pivots greater than a given amount due to depletion of thread on the hub of the bobbin the permanent magnet on the lever will trigger a voltage change on the Hall generator which may cause an appropriate alarm to provide a warning of a low thread condition.

Abstract: A lock stitch sewing machine having a bobbin thread run-out indicator which is adjustable to permit initiation of the indication with a selected length of bobbin thread remaining on the bobbin. A bobbin case is supported in a rotating loop taker against rotation therewith and partially extending therefrom. The bobbin is fashioned with two flanges joined by a hub and is carried in a cavity in the bobbin case, the cavity being arranged so that one flange of the bobbin also extends partially from the rotating loop taker. A fibre optic is arranged in the sewing machine frame to extend a light ray through an opening in the bobbin case above the rotating loop taker but in between the flanges of the bobbin, adjacent the hub thereof, and through an opening in the opposite side of the bobbin case to a light sensor. The light sensor is carried so as to be shiftable normal to the direction of the light ray.

Abstract: A skipped stitch detection system for a sewing machine is provided with a strain gage mounted on the slack thread regulator. The strain gage is connected in a Wheatstone bridge configuration. An amplified output from the Wheatstone bridge and timing signals from the sewing machine are provided to a microprocessor which analyzes the thread tension profile to detect the occurrence of a skipped stitch.

Abstract: A sewing machine is disclosed which includes at least one regulatable operating instrumentality, such as, for example, an adjustable needle thread tensioner. Means are provided for generating signals indicative of different parameters which affect the ultimate overall stitch, such as, for example, fabric thickness at the seam, thread type, and pattern type. A central processor is provided with an algorithm for controlling the thread tension so as to maintain uniform stitch quality as a function of the different parameters.

Abstract: A sewing machine for sewing buttonholes in a workpiece comprises a stationary lower part and an arm having one end pivotally mounted on the lower part and having an opposite end which carries a rotary hook which cooperates with a reciprocating needle carried in the lower part. The arm is pivotal relative to the base part to move the arm from a fixable sewing position with said hook spaced by a predetermined distance from the needle at a stitch-forming area to a rest position in which it is spaced away from the stitch-forming area. A thread-monitoring device is located adjacent the needle for monitoring the thread and detecting any breakage thereof. The machine includes a buttonhole cutting mechanism which is connected to the drive means so as to periodically cut the workpiece. A clamp is carried by the upper arm and it has a lower portion which rests on a resilient support which is biased upwardly by a spring.

Abstract: A tension detector which senses excessive tension deviation in the yarn fed to a tufting machine to operate a loaded plunger. There is a separate plunger for each yarn end with each plunger operating to complete an electric circuit when the plunger is acted upon by a high tension deviation yarn. The electrical circuit consists of a bank of identical resistors connected in series with a known voltage across them to create a linear voltage divider, a switch corresponding to each resistor, each switch being mounted after its resistor in parallel with the remaining resistors and closed by the actuation of a respective one of the plungers. The voltage indicator can be calibrated to display the particular yarn or needle number directly thereon so that the operator may identify the particular troublesome yarn.