Abstract: A sewing machine includes a needle plate, a feed dog configured to move a workpiece, a vertical drive mechanism configured to vertically drive the feed dog, a switch mechanism, a cutting mechanism, and an actuator. The switch mechanism is configured to switch from an active state where the feed dog is driven, by the vertical drive mechanism, above and below an upper surface of the needle plate to an inactive state where an upper surface of the feed dog is maintained below the upper surface of the needle plate. The cutting mechanism includes a blade configured to cut a thread at a position below the needle plate. The actuator is configured to commonly drive the switch mechanism and the cutting mechanism.

Abstract: In a sewing machine, a switching mechanism is coupled to a slide arm of a transmission mechanism included in an upper feed mechanism. When the switching mechanism is operated, the slide arm is switched between a transmission state in which the driving force of a driving cam is transmitted to a feed link mechanism and a non-transmission state in which the driving force of the driving cam is not transmitted to the link mechanism 61. This allows the switching mechanism to switch the slide arm 60A to the non-transmission state. This allows the operation of the feed link mechanism to be suspended, and allows the upper-lower movement of an upper feed dog to be suspended. Accordingly, this contributes to a reduction in vibration and noise in the sewing machine.

Abstract: A sewing machine having a device for manually changing a feed dog (10), including the feed dog (10) and a feed-dog holder (30). The feed-dog holder (30) is disposed in an arm bed (103) that is associated with the sewing machine, and the feed dog (10) is receivable in a clearance (31, 81) of the feed-dog holder (30). The feed dog (10) that is located in the clearance (31, 81) has a support face (15) which may be disposed parallel with the surface of a sewn-product support which may contain a needle-hole plate (113) or be configured as a needle-hole plate (113), the sewn-product support and/or the needle-hole plate (113) may at least partially be formed by the surface of the arm bed (103), and the support face (15) may be received in an opening (140) of the needle-hole plate (113).

Abstract: A sewing machine having a device for manually changing a feed dog (10), including the feed dog (10) and a feed-dog holder (30). The feed-dog holder (30) is disposed in an arm bed (103) that is associated with the sewing machine, and the feed dog (10) is receivable in a clearance (31, 81) of the feed-dog holder (30). The feed dog (10) that is located in the clearance (31, 81) has a support face (15) which may be disposed parallel with the surface of a sewn-product support which may contain a needle-hole plate (113) or be configured as a needle-hole plate (113), the sewn-product support and/or the needle-hole plate (113) may at least partially be formed by the surface of the arm bed (103), and the support face (15) may be received in an opening (140) of the needle-hole plate (113).

Abstract: A sewing machine feed mechanism is mounted on a work table of a sewing machine for transporting fabrics to be sewn, and includes a feed belt defining an encircled space; two belt wheels, on which two opposite ends of the feed belt are mounted; a driving source for driving the two belt wheels and the feed belt to rotate synchronously; a plurality of pressing elements located in the encircled space with respective bottom in contact with the feed belt; and an airbag located atop the pressing elements and connected to an external control device to have adjustable internal pressure. With these arrangements, the sewing machine feed mechanism has simplified structure to allow easy mounting/dismounting and reduced manufacturing cost thereof. Further, fabrics placed between the work table and the feed belt can be evenly pressed while being transported into a stitch forming area of the sewing machine for sewing.

Abstract: A sewing machine includes a bed, a sewing machine motor, a drive shaft, a needle bar moved up and down by the rotation of the drive shaft, a first feed mechanism can move the sewing object by making contact from below, a maximum value of the unit feed amount for the first feed mechanism being less than a specified length that is the length of a basting stitch, a second feed mechanism can move the sewing object by making contact from above, a maximum value of the unit feed amount for the second feed mechanism being not less than the specified length, and a control device controls the first feed mechanism such that the first feed mechanism does not move the sewing object and controls the second feed mechanism such that the second feed mechanism moves the sewing object with the specified length being defined as the unit feed amount.

Abstract: An upper feed device is configured to be arranged above a bed of a sewing machine and feed a work cloth. The upper feed device includes a feed portion, a mechanism arrangement portion, and a drive portion. The feed portion includes a first feed mechanism and a second feed mechanism and is configured to feed the work cloth in a feed direction. The first feed mechanism and the second feed mechanism are arranged side by side in a first direction, which is parallel to a top surface of the bed and orthogonal to the feed direction. The mechanism arrangement portion is configured to arrange the first feed mechanism and the second feed mechanism in different positions in a second direction, which is orthogonal to the top surface of the bed. The drive portion is configured to drive the first feed mechanism and the second feed mechanism in synchronization.

Abstract: A feed mechanism that advances fabric comprises at least one dog that mechanically advances the fabric toward a sewing head and at least one actuator that is coupled to and actuates the at least one dog in a servo controlled motion so that the sewing head sews the fabric at a desirable position.

Abstract: An upper feed device includes a mounting portion, a feed mechanism, a drive portion, and a connecting portion. The mounting portion is configured to mount the upper feed device to a presser bar of a sewing machine. The feed mechanism is configured to feed a work cloth. The drive portion is configured to drive the feed mechanism. The connecting portion is configured to electrically connect the drive portion to a control portion of the sewing machine.

Abstract: A guiding structure for a cloth feeding mechanism which is disposed on a base below a needle plate of a sewing machine, a feeding dog driven by the cloth feeding mechanism is mounted on a mounting seat. The guiding structure comprising a first guiding portion formed on the mounting seat and a second guiding portion formed on a guiding device, the first and second guiding portions cooperate with each other to guide the feeding dog to move in the X-axis direction, so that the cloth can be fed precisely along the predetermined path to ensure good sewing quality.

Abstract: A sewing machine includes a feed dog which transfers workpiece cloth, a needle plate having a first hole through which a needle is passed and a second hole through which a feed dog is movable upward and downward, a bed to which the needle plate is detachably attachable, a feeding mechanism which drives the feed dog in a front-back direction and in an up-down direction, an engaged portion formed in the needle plate, an engaging portion formed in the feed dog or the feeding mechanism, and a switching unit which switches the feed dog or the feeding mechanism between a transfer position where the feed dog transfers the workpiece cloth and a needle plate adjusting position which differs from the transfer position and where the engaging and engaged portions are engaged with each other thereby to determine a fixing point of the needle plate on the bed.

Abstract: The purpose of this invention is to change the direction of the feed so that the user/operator can now use the free arm of the sewing machine to the optimum advantage. The conventional domestic free arm sewing machine has, heretofore, been limited to sewing in a lateral direction across the free arm. The use of this invention allows the machine to be used so that tubular shaped garments can travel along and around the free arm of the sewing machine this sewing can be accomplished with any outside seams, something, heretofore, impossible with a conventional free arm sewing machine.

Abstract: An electrically controlled sewing machine includes a needle bar, a needle plate, a feed dog, a feed dog vertical drive mechanism, a feed dog front/rear drive mechanism, an embroidery drive mechanism, and a feed dog retraction mechanism. The feed dog retraction mechanism includes a switching operation lever. The feed dog vertical drive mechanism includes a normal sewing drive cam and a retraction drive cam, which are switched between using the switching operation lever. The retraction drive cam drives the feed dog to rise upward by about 1 mm when the upper thread is being tightened, that is, at about 40.degree. to 90.degree. phase at the end of the thread tightening operation by the upper thread take-up lever. Because the feed dog moves upward only about 1 mm, it remains retracted below the level of the needle plate and will not interfere with movement of a workpiece cloth mounted in an embroidery frame.

Abstract: A blindstitch machine provided with a mechanism for feeding an end of the fabric to a position where a needle of the machine main body passes thereby to form the seam from the start end of the fabric, wherein the rotating amount of a belt is adjusted corresponding to the feeding amount of a feed dog of the machine main body, for instance, adjusted to synchronize the fabric feeding by the machine main body with that by the belt, so that the fabric is sewed without being wrinkled or stretched about the passing position of the needle.

Abstract: A piece of textile goods is selvedged along an edge extending between ends of the piece by gripping a strip of the piece offset from the edge and displacing it parallel to the edge at a constant travel speed such that successive portions of the edge pass through a plurality of folding stations followed by a sewing station. The edge is folded over as it passes through the folding stations and the folded-over edge is stitched together in the sewing station. The portions are gripped in each station upstream of the sewing station as they pass through. To eliminate an out-of-square condition the gripped portion is advanced when it is adjacent one end of the goods at a speed that is greater than the constant travel speed, the gripped portion is advanced when it is adjacent the other end of the goods at a speed which is less than the constant travel speed, and the gripped portion is advanced when it is offset the ends of the goods at a speed which is substantially equal to the constant travel speed.

Abstract: A quilting machine includes a multiple needle quilter with a panel cutter located in-line therewith and downstream thereof and having an accumulator therebetween. A programmable controller operates the quilter to stitch a programmed series of one or more patterns on a web. A feed roller angular encoder measures the quilted web length fed under tension to the accumulator. A detector signals when the accumulator is full, whereupon the controller causes web to be fed from the accumulator to the panel cutter, where it passes without tension thereon toward a photo sensor. The photo sensor signals the controller which activates the cutter to sever a predetermined panel length from the web. The controller then reads information from the encoder and the accumulator detector to determine the amount of stressed quilt required to replenish the cutoff panel length.

Abstract: A method for forming a partial mattress sack which prevents radial bunching includes feeding first and second panels having different edge lengths at different rates through a sewing machine to form the partial mattress sack. An apparatus for sewing the partial mattress sack includes a mechanism for driving upper and lower walking feet at varying rates and a mechanism for driving the upper walking foot at the same speed as a second lower walking foot.

Abstract: A feed device for a sewing machine incorporates an upper feed dog above a throat plate and a lower feed dog below the throat plate and conveys material fabrics to a needle drop point by way of sandwiching the material fabrics between the upper and lower feed dogs. The feed device incorporates an energizing member for energizing the upper feed dog in the direction of the throat plate and controls the sandwiching force between the upper and lower feed dogs by constraining the energizing force generated by the energizing member.

Abstract: The invention comprises improvements to sewing machines for increasing the throat clearance of the machine. The improvements relate to 1) modifications to mechanical components of the machine to increase the throw and upper travel limits of the presser foot, upper feeding foot, needle and spreader, 2) an adjustment for allowing the speed of the upper walking foot to be variable relative to the speed of the lower walking foot, and 3) an improved biasing spring for biasing the presser foot downward.

Abstract: A process for determining coordinate values of touchdown sites of a needle for forming sewing patterns with an electronically controlled sewing machine, which is equipped with a feed dog performing only relatively small amounts of displacement and with a needle pivotable in one direction of displacement of the feed dog. The coordinate values for a straight seam section, the consecutive touchdown points of the needle, are determined when the maximum amount of feed of the feed dog in the X coordinate direction and/or the sum of the maximum amount of the lateral movement of the needle which is possible at a given needle position and the maximum amount of feed of the feed dog in the Y coordinate direction is exceeded. The seam section is subdivided by equidistant intermediate touchdown sites, the distances between which in the direction of movement of the needle are composed of a constant percentage of the lateral movement of the needle and of a constant feed percentage of the feed dog.

Abstract: A processing device for processing a sheet material with a pattern of the present invention is such as a sewing machine with pattern matching operation. The processing device has a detecting unit for detecting a color state of the pattern of the sheet material and producing a color state signal indicative of the color state. The processing device processes the sheet material on the basis of the color state signal produced by said detecting means. According to the present invention, the processing device is provided with an automatic adjusting unit for adjusting the detecting unit to allow the detecting unit to produce a desired color state signal with respect to a reference color state. Therefore, the white balance or the dynamic range is properly adjusted simply and reliably for the processing device.

Abstract: A device for loading a garment for a sewing machine having a first device for moving the garment toward the sewing machine, a second device downstream of the first moving device for moving the garments towards the sewing machine, and a device for changing the speed of the first and second moving devices relative to each other to change the distance between adjacent moving garments according to programmed distance values.

Abstract: A sewing machine has a pattern matching system for matching patterns on two fabric pieces to be sewn to each other, based on detected hues of the patterns. Any mismatch between the patterns is calculated on the basis of color quality information converted from detected intensities of light which is reflected by the fabric pieces. The fabric pieces are fed relatively to each other so that the patterns thereon are matched, based on the calculated mismatch.

Abstract: A device for sewing together two fabric parts includes two pattern sensors and correcting means for determining and correcting misalignment of patterns on the fabric parts. Also, an additional image sensor (18) is provided, which scans the surface of the fabric (16) to be sewn at the site of an intermediate storage location (15) before this fabric is fed into the sewing machine. An image-processing device connected to this additional image sensor generates data on certain basic characteristics of the fabric pattern, such as color, contrast, lightness, register length, and angular orientation of the pattern components. From these characteristic data, a decision logic circuit determines setting data for the operating parameters of the devices used in the sewing machine for detecting and correcting a possible pattern misalignment during sewing.

Abstract: A feeding apparatus includes a spindle and a shaft disposed in a base of a sewing machine. A lever is fixed on the shaft and can be caused to swing by the spindle. Two followers are engaged on the spindle. A pawl is fixed on each follower for feeding cloth. One follower is coupled to one end of the lever and the other follower is coupled to the other end of the lever by a link and a lever arm. The amplitude of swinging of the lever arm can be changed so that one of the pawls can be caused to move back and forth relative to the other pawl.

Abstract: Patterns of two fabric layers are each recognized by a camera and the fabric layers are aligned to make these patterns agree in the transverse and longitudinal directions. According to the invention the influence of speed-related disturbance variables and pattern-related limitations during the generation of the signal is reduced. Two-dimensional images of the two fabric layers are recorded with a matrix camera each during a pause between feeds. The degree of congurence of the fabric layers according to the pattern is determined by two-dimensional cross-correlation analysis of the image points arranged in rows and columns. Aligning correction values are calculated from this degree. The edge distance of the fabric layers is determined with a section of the matrix sensors, which is a separate section in terms of evaluation. Based on the edge distance data, the lower fabric layer is adjusted to the correct distance continuously and the upper fabric layer is adjusted as needed.

Abstract: A feed dog drive having an adjustable feed direction for a sewing machine having, a needle plate, a presser foot, and a feed dog element. The drive has a device for carrying out a feeding and lifting motion of the feed dog element, a holder, and a device for rotatably mounting the feed dog element on the holder such that it can be turned is synchronism with stitch formation of the sewing machine.

Abstract: An improved method and apparatus is provided for use in a sewing machine. The improvements include preloading two pieces of material which are to be sewn together. The preloading is accomplished by positioning pieces of material to be sewn under a gripper spaced from the sewing head on a table while prior pieces of material are being sewn. The gripper engages the material and, when the prior sewing operation is completed, the gripper is moved across the table toward the sewing head to load the preloaded pieces of material. When the two pieces of material are preloaded, most of the material hangs over an edge of the table and the lengths of the pieces of material are determined by movable detectors.

Abstract: A feeding apparatus includes a spindle and a shaft disposed in a base of a sewing machine. A lever is fixed on the shaft and can be caused to swing by the spindle. Two followers are engaged on the spindle. A pawl is fixed on each follower for feeding cloth. One follower is coupled to one end of the lever and the other follower is coupled to the other end of the lever by a link and a lever arm. The amplitude of swinging of the lever arm can be changed so that one of the pawls can be caused to move back and forth relative to the other pawl.

Abstract: A pattern matching sewing machine comprises a sewing means for sewing two superposed sheets of cloth having substantially identical patterns thereon, a feeding means for feeding the two cloth sheets into the sewing means, a detecting means for detecting a mismatch distance between the patterns on the two cloth sheets, and a transport means to transport the two cloth sheets relatively. The pattern displacement amount detected by the pattern mismatch distance amount detecting means may be reduced. A determining means is provided for determining whether pattern matching is possible or not based on the information relating to the mismatch distance obtained by the detecting means.

Abstract: An edge tracing sewing machine includes a reciprocable needle bar having a needle at a lower end, a forward feed driving device for feeding a work fabric in a sewing direction, a lateral feed driving device for feeding the work fabric in a lateral direction perpendicular to the sewing direction, a tracing width setting device for setting a tracing width from the edge of the work fabric to the needle in the lateral direction, a fabric-edge sensor movable in the lateral direction for detecting an edge of the work fabric, a fabric-edge position detector for detecting a position of the fabric-edge sensor, and a control device. The control device moves the fabric-edge sensor in the lateral direction to make the fabric-edge sensor follow the edge of the work fabric. The control device controls the lateral feed driving device based on the tracing width set by the tracing width setting device and the position of the fabric-edge sensor detected by the fabric-edge position detector.

Abstract: An edge tracing sewing machine includes a reciprocable needle bar having a needle at a lower end, a needle position sensor for detecting needle-down position, a presser bar having a presser foot at a lower end, a presser foot switch for detecting an upper position of the presser foot, a vertical feed driving device, a forward feed driving device for feeding a work fabric in a sewing direction, a lateral feed driving device for feeding the work fabric in a lateral direction perpendicular to the sewing direction, a fabric-edge position detector, a tracing width setting device, and a control device. The control device controls the lateral feed driving device based on signals from the fabric-edge position detector and the tracing width setting device, so as to carry out a tracing sewing with the tracing width set by the tracing width setting device.

Abstract: An upper feed mechanism of a sewing machine, in which a horizontal motion mechanism for moving the upper feed dog back and forth is provided with a double lever mechanism composed of a single arm lever, a bifurcate lever and a slider slidably mounted on both levers, and a crank lever mechanism for oscillating the levers. When a crank of the crank lever mechanism is at a top dead point or a bottom dead point, the radial directions of the levers are matched, and when the slider is moved in this state, the upper feed dog varies in the feed amount while the front position or rear position is constant.

Abstract: A pattern-matching joining machine for joining two sheets (e.g., sewing two cloths) having the same patterns with the patterns matching. The pattern-sensing photo-sensor generates intensity data for three different colors and the color data processed to correctly discriminate elements of a pattern having colors of similar brightnesses, and to accurately pick out pattern elements with faint colors from behind outstanding pattern elements. One way of processing the data includes calculating differences between intensity data for different colors. Another way includes selecting the color that has the largest intensity change.

Abstract: A sewing machine including a laterally extending shaft with a cam contactor thereon being rocked by an eccentric cam assembly secured at a hook drive shaft provides an end face cam at its end such that a sliding shaft with a feed dog assembly thereon and contacting with the end face cam is slid laterally. Thereby, the feed dog is moved laterally, leftwardly or rightwardly, depending on the shifting of the cam contactor. The eccentric cam assembly comprises two eccentric cams configurated opposite in phase and formed such that leftward feed or rightward feed is selectively enabled, and a circular cam which causes no lateral feed. Shifting of the contactor to the selected cam is performed by a solenoid via a linkage system.

Abstract: A device for performing an initial setting of a photosensor of a sewing machine including a light-emitting element and a light-receiving element. The device adjusts the strength of light emitted by the light-emitting element so that the output of the light-receiving element responding to the emitted light falls within a preset normal range. Thus the output from the light-receiving element is normalized and the photo-sensor can correctly discriminate various levels of reflectance, i.e., between a pattern signal and a cloth-edge signal, or among pattern signals of various brightnesses.

Abstract: A pattern-matching sewing machine having a feed-correcting means for accurately adjusting feed amount using a correction factor with three values which are set according to various sewing conditions such as species of cloths and a speed of a main motor. When the feed amount for pattern matching is calculated based on only a mismatch distance detected by a photo-sensor, the accurate pattern matching is not achieved due to the various sewing conditions. Therefore, the feed-correcting means selects the optimum one of the three values to accurately correct the feed amount for a good pattern matching.

Abstract: A pattern-matching sewing machine for sewing two sheets, (e.g. two cloths) having the same patterns with their patterns matching. The sewing machine has a plurality of mismatch calculation modes. The operator selects one of the calculation modes appropriate to the type or characteristics of the pattern to be sewn and the mismatch distance is calculated according to the selected mode.

Abstract: A pattern-matching sewing machine that constantly samples photo-intensity data during calculation of a mismatch distance and during adjustment of the feeding mechanism based on the calculated mismatch distance. When the adjustment is finished, a new mismatch-distance calculation is quickly started, not by waiting for sampling new photo-intensity data of a predetermined number, but by using photo-intensity data of the predetermined number including the data thus sampled during the previous calculation and adjustment, and the previously stored data which have been used in the previous calculation.

Abstract: A hemmer seamer assembly comprising an apparatus for positioning a chain of stitches for stitching onto fabric having a needle and a throat plate, including a device for positioning the chain of stitches forwardly of the needle, and a device for moving the fabric to the throat plate for sewing the chain onto the fabric.

Abstract: A sewing machine for sewing two overlapped cloth pieces including sensor means for detecting the intensity of light transmitted through each respective cloth piece, intensity curve generating means for generating respective intensity curves over a predetermined distance, differentiation means for differentiating between the intensity curves of each cloth piece and for generating differential curves for each cloth piece, difference determining means for determining a displacement between the two differential curves and feed pitch control means for adjusting a feed pitch based on the displacement. The sewing machine of the invention matches and sews the two cloth pieces having the same lateral and vertical patterns by ignoring the detected vertical pattern data having unclear and vague broad peaks and using the detected lateral pattern data having clear sharp peaks to have the two cloth pieces' patterns matched in alignment.

Abstract: In order to correct the asynchronous state of a feed pulse motor of a sewing machine used to reciprocate a feed for feeding a fabric to a sewing needle, a feed control apparatus is provided which switches the pulse motor to a predetermined excited state when the feed dog abuts a stopper on the downstream side of feed motion at the start up of sewing operation so as to locate the feed dog at a known reference position. Additionally, the feed control apparatus switches the pulse motor to another predetermined excited state when the feed dog abuts a stopper on the upstream side of the feed motion so as to locate the feed dog at a known position during consecutive sewing operation.

Abstract: Before sewing, a cloth pattern sensing means generates waveform signal corresponding to the overall width of two overlapping patterns corresponding to each other in two cloth pieces. The position difference between the patterns is calculated on the basis of the waveform signal. At least one of the feed pitches of the two cloth pieces is changed on the basis of data on the calculated amount of difference and data on the sensed cloth feed pitch. Data on the position difference amount between any patterns and the position difference amount between the next patterns are compared to calculate the direction in which the position difference amount increases or decreases, namely, the direction of the difference. Adjustment is made in the direction in which the amount of difference decreases on the basis of the result of calculation of the direction.

Abstract: A pattern sensor installed in a sewing machine for sensing patterns on two opposing sheets of cloth so that the patterns on the separate cloths are correctly aligned while sewing. The sensor is composed of a sensor head disposed between the two sheets of cloth, a light source, a light receiver, two light conduits including bundles of thin optical fibers, and a reflector which is composed of two prisms provided in the sensor head. The light emitted from the light source is transmitted via separate conduits and respectively enters the prisms. One beam is reflected upward toward the upper cloth, and the other is reflected downward toward the lower cloth for sensing the patterns. The light reflected on each cloth returns to the light receiver via the reverse route to be processed as a pattern signal.

Abstract: A lifting rocker which is pivotally supported by a link is engaged with an eccentric ring which is fixed to a main shaft of a sewing machine. By the rotation of the eccentric ring, the lifting rocker rocks up and down about a fulcrum defined by the link while causing the link to rock. A feed bar having thereon a feed dog is slidably supported by the lifting rocker, and moves in back and forth directions through the rocking of the arm to constantly maintain a definite amount of feed without respect to variation of the rotational speed of the main shaft of the sewing machine.

Abstract: There is provided an automatic sewing machine which comprises, a main shaft, a bed, a needle bar having a needle secured to the lower end thereof, a thread straining control device, an operation device and an alarm device.

Abstract: Method and apparatus for determining and regulating the amount of advance of a plurality of workpiece plies at a sewing machine which is affected by scanning the individual plies while recording the stitches being formed between two separate feed points and actuating top and bottom feed devices to achieve a desirable feed of each ply. Signs present or to be applied at any desired point of the workpiece plies are scanned at two successive points, and pulses generated by a pulse generator connected with the main shaft of the machine are summed during this period of time. The pulse sum is compared with a number of pulses which depends on the mutual spacing of the scanning points and on the adjusted stitch length. For two work plies the pulse sums formed between the recognition of the signs are compared directly. As signs to be scanned are used either imprinted marks, the jags of a pinked workpiece edge, or the bright, dark structure of a surface section of the workpiece.

Abstract: A feed device on a sewing machine having a feeder which is firmly connected with a horizontal shaft which is displaceably mounted in a feed rocker mounted fixed in a housing, and having a drive for the longitudinal axial movement of the shaft. For the reduction and simplification of the drive for the longitudinal movement of the shaft, this drive is arranged directly on the feed rocker. In addition, the horizontal shaft has a gear system with which a gear segment cooperates which together with its drive elements is mounted on a flange firmly connected with the feed rocker. The drive occurs via a step motor which is secured on a flange plate of the feed rocker lever.

Abstract: A thread tightening control apparatus according to the present invention is capable of tightening upper and under threads accurately and in good order, irrespective of fabric thickness, by the relative movement between a needle and a fabric holding body.The apparatus is provided with setting means capable of generating a plurality of setting signals of different timings at which the drive pulses are to be supplied to the drive means in dependence upon fabric thickness. Shifting means is operable in association with a selected setting signal for moving a period during which drive means is supplied with drive pulses by the actuating means forward or backward with respect to a predetermined rotational angle of a spindle. As a result, the distance between the tip of the needle and the surface of the fabric at the completion of fabric feed is set to a predetermined minimum length irrespective of fabric thickness.

Abstract: A method and apparatus for the pattern-correct sewing together of two pieces of cloth having the same pattern by a sewing machine with one cloth feed mechanism arranged over and one arranged under the cloth pieces, the feed quantity of which is variably by at least one positioning system relative to each other, uses a sensor arranged upstream of a stitch forming point for each cloth piece and a signal processing unit which processes signals from the sensors corresponding to the relative position of the cloth pieces and which influences the positioning system for the feed mechanism in accordance with the established relative position of the cloth pieces. For the pattern-correct sewing together of the two cloth pieces, the pattern structure of each cloth piece is continuously determined by the sensors by measuring values of a structure-or pattern-typical criterion.