Abstract: A stitching system is configured to stitch through decorative skins with a molded seam recess representing a seam and includes a sewing machine, an image acquisition mechanism, a controller, and a rotation mechanism. The sewing machine is rotatable with respect to a support table, and includes a sewing head to receive a sewing needle and a sewing foot to selectively engage the skin. The image acquisition mechanism produces an image of the seam recess with respect to the sewing head/needle(s). The controller determines the difference between the actual recess location and a predetermined desired recess location. Based on this difference, the controller determines a sewing machine rotation angle and orientation to reduce the difference to zero, and then produces a corresponding adjustment signal that drives the rotation mechanism. A robot can move either the sewing machine or the workpiece, and still use the herein-described real time steering control.

Abstract: A sewing machine includes a sewing controller that controls sewing machine components, an imaging element capable of capturing facial images of a sewing machine user; a settings storage that stores settings for preset modes, the settings comprising items pertaining to sewing machine functions; a user information storage that stores facial image data of the user captured by the imaging element with mapping to the settings of the mode registered with the user; a verifier that verifies whether or not image data that matches the facial image data captured by the imaging element at sewing operation start exists in the user information storage; and an instruction controller that reads the settings from the user information storage when receiving a positive verification result from the verifier, and that instructs the sewing controller to control the sewing machine components based on the settings read.

Abstract: A sewing machine including an image capturing unit disposed at a position capable of capturing images of the stitches formed on the workpiece cloth and capturing images of the stitches at least from either upper and undersides of the workpiece cloth; an extracting section that extracts, from the image data of the stitches captured by the image capturing unit, a region occupied by an opposite side thread appearing at an interlace of the needle thread and the bobbin thread; a calculating section calculating an area of the extracted region; an evaluating section that evaluates a tension balance between the needle thread and the bobbin thread based on the area calculated by the calculating section; and a controller controlling the thread tension adjustment mechanism to modify the tension balance of the stitches based on a result of evaluation by the evaluating section.

Abstract: A sewing machine and a sewing machine operating program stored on a computer-readable medium for changing display items displayed on a liquid crystal display of a sewing machine on a page by page basis, when an output signal of an operation of rolling forward or backward a mouse wheel is detected. The sewing machine may include a display device that displays a variety of information related to sewing and a display item storage device that stores display items to be displayed on the display device. The sewing machine may also include an operation device that includes an operating member for performing plural types of operations and a display control device that changes the display item displayed on the display device in response to at least one of the operation type or the operation quantity outputted by the operation device.

Abstract: A sewing machine includes a display device, a display data storage device storing pattern display data for displaying each sewing pattern on the display device and pattern group display data for displaying on the display device a pattern group indication mark indicative of each of a plurality of pattern groups obtained by classifying the sewing patterns, a selecting operation device selecting one of the sewing groups and further either or any one of the sewing patterns contained in the selected pattern group, and a display control device which, when one of the pattern groups has been selected, causes the display device to display the pattern group indication mark indicative of the selected sewing pattern group on the display device firstly in an enlarged size and subsequently in a reduced normal size, based on the pattern group display data of the selected pattern group.

Abstract: A sewing apparatus such as a sewing machine includes a cassette mount to which a thread cassette having a thread accommodating section for accommodating a thread supply is detachably attached, at least one detector detecting an operating state of at least one mechanism related with the thread cassette, a determining unit determining whether the thread cassette can be attached to the cassette mount, based on a result of detection by the detector, and an informing unit informing a result of determination by the determining unit.

Abstract: A sewing apparatus such as a sewing machine includes a sewing mechanism in which a thread is used, a cassette mount to which a thread cassette holding the thread used in the sewing mechanism is detachably attached, a determining unit determining a type of the thread cassette attached to the cassette mount, and a control device controlling the sewing mechanism according to the type of the thread cassette determined by the determining unit.

Abstract: In connection with an electric motor (12) used for operating a sewing machine, which has a fan wheel (17) and a speed sensor (25), the fan wheel (17) and the screen disk (18) of the speed sensor (25), as well as a belt pulley (19) of the belt drive (10), are combined into a multi-function wheel (15).

Abstract: A festooning machine has at least one transport element for a forward transportation and transverse transportation of a sewing product, two vertically movable needles arranged at a distance near the transport element and parallel to a direction of the transverse movement with an adjustable distance therebetween, a needle drive for vertically moving the needles, and a independent drive unit which supports the transport element and provides movements of the transport element.

Abstract: The present invention stores the image data of an original image pattern read by an image reader in processed data storage means, and stores the calculation formulas for producing designs such as checkers and strip patterns in calculation formula storage means. And, the needle location data of a selected design is generated by substituting the line and column numbers of the image data in the calculation formulas stored in the calculation formula storage means. By this construction, within the image data, embroidering data of the design which is not affected by the visible outline thereof can be formed. In addition, by carrying out the logical AND between the data of the needle locations corresponding to a design and the image data of an original data, embroidering data of the design which is not affected by the visible outline of the image data is formed within the image data.

Abstract: A thread trimmer for a pattern sewing machine is disclosed. When the pattern sewing machine forms patterns, a pattern is connected to a next pattern by a crossover thread. The thread trimmer automatically cuts a specified portion of the crossover thread. Therefore, the operator can avoid the troublesome and time-consuming cutting of the crossover thread manually with scissors. Furthermore, the sewing efficiency of the pattern sewing machine is enhanced.

Abstract: A sewing machine incorporates a needle bar disconnecting mechanism (3) and a thread cutting mechanism (9). The needle bar disconnecting mechanism (3) is interposed between an arm spindle (2) and a needle bar (4), which normally transmits rotations of the arm spindle (2) to the needle bar (4) to vertically move the latter up and down but disconnects the needle bar (4) from the arm spindle (2) to stop the vertical movement of the needle bar (4) when actuated. The thread cutting mechanism (9) cuts threads at the termination of stitching. A rotational phase detecting mechanism (11) is provided for detecting a rotational phase of the arm spindle (2). An electronic control circuit (12) actuates the needle bar disconnecting mechanism (3) when the rotational phase detecting mechanism (11) detects that the arm spindle (2) has reached a predetermined rotational phase after the thread cutting mechanism (9) is actuated.

Abstract: A pattern sewing machine provided with a thread trimmer and a thread delivery unit. After a series of patterns is completed and the thread trimmer trims thread, the thread delivery unit is prohibited from delivering thread until the next sewing operation starts to form another pattern. When the patterns are distant from each other, a needle bar is disconnected and fabric is fed a distance in a non sewing operation. No excess thread is delivered corresponding to the feeding distance of the fabric, thus preventing thread from being wasted. Furthermore, an operator can avoid the cutting of excess thread with scissors. The sewing efficiency is thus enhanced. In the pattern sewing machine the crossover thread connecting the patterns is automatically cut regardless of the distance between the patterns.

Abstract: A zigzag sewing machine comprising a needle bar lateral drive device, a needle bar lateral drive steppping motor for controlling the needle bar drive device, a feed device for driving a feed dog back and forth, a crossfeed device for driving the feed dog from side to side, and a crossfeed stepping motor for controlling the feed drive device. The sewing machine can sew beautiful pattern stitches and neat stitches by setting up amplitude according to the minimum feeding pitch of the feed dog which is smaller than the minimum moving pitch of the needle bar. Since the needle location is determined by cooperation between the needle bar and the feed dog, the maximum lateral moving width of the needle is shorter than amplitude and the needle can be securely and accurately driven even at a high sewing speed.

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 sewing machine capable of performing a profile sewing in which a stitch is provided at a position spaced away from an edgeline of a workpiece by a predetermined constant distance to provide a predetermined margin. The sewing machine is provided with memory means which stores therein the needle position data. This data is transmitted to a sewing needle swinging mechanism so as to move the sewing needle to a position inwardly spaced away from the edgeline to provide the margin. The sewing machine is also provided with image forming means connected to the memory means for providing a visualized image of a stitching reference line on one of a surface of the bed and the workpiece fabric on the bed in accordance with the needle position data. The stitching reference serves as a guide line along which the edgeline is placed.

Abstract: A device for switching between normal and embroidering stitching comprises X-directional and Y-directional drive control devices for controlling movement of the embroidering stitching device in X- and Y-directions, respectively, and two stepping motors for driving a needle bar control device or the X-directional drive control device, and a feed control device or the Y-directional drive control device, respectively. Two switching elements alternatively connect the first stepping motor with either of the needle bar control device or the X-directional drive control device, and the second stepping motor with either of the feed control device or the Y-directional drive control device, respectively, to provide for normal and embroidering stitchings, respectively.

Abstract: According to the present invention, there is disclosed a microprocessor for a sewing machine which can be changed over from a normal service mode for controlling sewing operations to a diagnostic mode for controlling diagnostic programs. The drive of the diagnostic programs takes place by actuation of already present selector switches of the sewing machine and the display of the diagnostic results takes place through already present displays of the sewing machine. In order to facilitate the diagnostic, a mask is provided which can be placed on the control and displaying panel of the sewing machine and which contains indications relating to the drive of determined programs and the reading of the results. At least in one case, means are provided in order to enter and store correcting information according to the results of the diagnostic. This provides a simple and multilateral diagnostic capability and the possibility of intervention in the electronics of the sewing machine.

Abstract: An upper thread carried by a vertically reciprocating needle is drawn from a bobbin through a tensioning device, a supply device and a take-up lever. A predetermined amount of the upper thread is first supplied by actuating the supply device, while applying no tension thereto. An additional amount of the upper thread is then supplied by operation of the take-up lever with a predetermined tension being given thereto. The additional amount is detected by a sensor. The supply device includes a one-way clutch for allowing the upper thread to travel in a predetermined direction which, however, may not be conveyed from the needle side when the supply device is made operative. A CPU controls the amount of thread first supplied by the supply device which will always be smaller than an amount actually required for producing a stitch, resulting in an additional amount to be supplied supplemental in cooperation with the tensioning device.

Abstract: A device for guiding a lower thread in a zigzag stitching sewing machine is provided with a lower thread guiding unit that determines two lower thread drawing positions in accordance with a selected pattern. The lower thread guiding unit includes a lower thread guiding part which, at one of the two positions, acts on the lower thread to guide a lower thread drawing position to a center of a needle amplitude. A lower thread releasing element, at the other of the two positions, cooperates with the lower thread guiding unit to release the lower thread engaged with the lower thread guiding part.

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 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 electronically controlled sewing machine, comprises a current detecting device for detecting a value of current flowing through a stepping motor that drives a machine part and current setting means for setting a value of current to be applied to the stepping motor. The sewing machine further includes a control device (CPU) for storing a plurality of different values of currents to be applied to the stepping motor and driving the stepping motor until the stepping motor passes through an initial position thereof. The control device stops the stepping motor at a predetermined angular position thereof spaced from the initial position. The control device supplies the different values of currents to the stepping motor in a predetermined sequence from a smallest value to a larger value of current under a predetermined program to drive the stepping motor until the stepping motor reaches the initial position thereof.

Abstract: An automatic thread tension control sewing machine comprising thread tension controller for clamping an upper thread with a predetermined pressure to control an amount of the upper thread supplied to a needle and a loop taker, thread tension setting means that determines a pressure with which the thread tension controller clamps the upper thread, upper thread supplying mechanism, a releasing mechanism controlling operation of the upper thread supplying mechanism, and a central processing unit for actuating the releasing mechanism in accordance with a selected stitch pattern.

Abstract: A sewing machine comprises a thread deflecting device arranged between a thread take-up lever and a needle and which in response to a swinging movement of a needle bar effected in response to selection of a zigzag stitch, deflects the upper thread laterally of a fabric feeding direction. A thread blocking device is provided on one side of the thread deflecting device. The sewing machine further comprises an actuator operated in response to actuation of a zigzag stitch pattern selecting key to move the thread blocking device to an operative position thereof. The thread blocking device in the operative position blocks the upper thread as it is deflected in one direction by the thread deflecting device to give a predetermined degree of tension to the upper thread, so that the stitch is tightened on one side of the zigzag stitch in addition to the tightening of the stitch by a thread take-up lever.

Abstract: A zigzag sewing machine includes a needle hole member having a round needle hole of a diameter slightly larger than that of a stitching needle. The needle hole member engages a laterally elongated hole in a needle plate and is swingable along the latter. A base member is mounted coaxially with a loop taker and is rotatable relative to the loop taker. The needle hole member is pivoted to the base member for relative vertically swinging movement. A lever swingably mounted on the machine housing engages with the needle hole member, and a cam rotated in synchronism with the vertical reciprocation of the needle is in engagement with the swinging lever. A stepping motor is operatively connected to the needle to reciprocate the needle laterally in the elongated needle plate hole, and the motor is also operatively connected to the base member to reciprocate the base member.

Abstract: This invention relates to an electronic sewing machine in which sewing data consisting of the needle sewing positions encoded for each stitch of a predetermined stitch pattern is stored. It comprises at least a memory for storing sewing data consisting of the encoded stitch data in group in regard to the stitches the needle sewing positions of which change regularly and the read out time data which instructs the reading out of the encoded stitch data by the number of times equal to the number of stitches encoded in group. This composition is effective not only in reducing the capacity required for storing stitch data but also shortening the time required to process the stitch data.

Abstract: A selected pattern display device of a sewing machine is disclosed wherein pattern selecting means is selectively operated to select stitch data for a pattern from a plurality of patterns including a straight stitch pattern stored in pattern storage means, amplitude selecting means is selectively operated to select a numeral value for determining the amplitude of the selected pattern, and display means is provided to display the selected pattern and the numeral value of the selected pattern, discriminating means is responsive to operation of the pattern selecting means to discriminate if the selected pattern is the straight stitch pattern, the discriminating means producing a signal, if the selected pattern is the straight stitch pattern, straight display data storage means is responsive to the signal from the straight stitch pattern discriminating means and a numeral value selected by operation of the amplitude selecting means to produce graphic data representing the straight stitch pattern of a determined n

Abstract: A sewing machine for forming successive stitches along an edge of a workpiece, including an endwise reciprocable sewing needle, a feeding device for feeding the workpiece in a feed direction, in synchronization with reciprocations of the needle, a control motor for changing a relative position between the needle and the workpiece in a lateral direction perpendicular to the feed direction, an edge sensor generating an output signal corresponding to a position relative to the workpiece edge in the lateral direction, and a position control device for receiving the output signal from the sensor in synchronization with the needle reciprocations and applying to the control motor a drive signal to control the relative position between the needle and the workpiece edge. The drive signal is determined based on the output signal of the sensor.

Abstract: Predetermined pattern selecting and function selecting keys of an electronic sewing machine are employed for controlling the selection between normal operation of a stitch forming device and a built-in diagnosing device. The diagnosing device is enabled only when the power switch of the machine is on while the predetermined function selecting key is kept depressed, and the predetermined pattern selecting key is kept depressed for a predetermined time interval. The stitch forming device is enabled when the two predetermined keys are not depressed for the predetermined time interval.

Abstract: A sewing machine capable of forming a line of stitches along the edge of a workpiece, while the needle is reciprocated by a needle bar relative to the workpiece in a feeding movement. The needle bar is supported by an oscillator which is joggable in a lateral direction substantially perpendicular to the feeding direction. A sensor is provided to detect the fabric edge, by emitting a radiation toward a reflecting surface provided on the work bed of the machine. The sensor determines the position of the fabric edge by detecting an amount of the reflected radiation received. The reflecting surface has a concave shape in cross section taken in a vertical plane parallel to the feeding direction. The lateral jogging movement of the oscillator is controlled according to the amount of the reflected radiation received by the sensor, so that the line of stitches is spaced apart from the edge of the workpiece by a predetermined distance.

Abstract: In a sewing machine which stores stitch control signals in an electronic memory composed with a microcomputer, incorporated therein are a stitch selecting device, a blindstitching depth setting device and a blindstitching width setting device which are both independently set by operation of said stitch selecting device. When a blindstitching pattern is selected, said depth setting device and width setting device are made operative, and needle dropping left positions are set by said depth setting device, and right dropping positions or whole amplitudes are set by said width setting device, and they are input to the memory for forming the blindstitching patterns by the stitching control signal of the blindstitching pattern.

Abstract: A zigzag sewing machine capable of forming a plurality of back stitches before or after forming a pattern. When a specific pattern for over-casting is selected and the needle is jogged to a position corresponding to the right end position of the selected pattern, back stitches are formed after the needle has been jogged to the left in response to the operation of a back stitch control member.

Abstract: In the present invention, two stitch control signals are memorized in each address, one of these stitch control signals is used as an address signal, the other signal is used as a stitch control signal in its address, and this address signal is the next stitch control signal. Therefore, when the next stitch control signal is an address signal of the stitch control signal to be executed then, the discrimination in a data selector becomes fast and the motion for sending the stitch control signals is quickly executed.

Abstract: This invention makes a proper calculation to an amount of supplying a lower thread to be required to forming of a stitch with stitching information in relation with changing of a needle dropping position from a preceding stitch to a present stitching, so that the lower thread is forcibly drawn out in accordance with said calculation, and makes a proper calculation to tension of an upper thread optimum to forming of a stitch with stitching information so as to determine the optimum upper thread tension in accordance with said calculation, or makes a calculation to the amount of supplying the upper thread optimum to forming of a stitch with stitching information so as to draw out the upper thread in accordance with said calculation.

Abstract: A movement control apparatus for a sewing machine to automatically control movement initiating timing corresponding to various sewing machine speeds.

Abstract: A stepping motor is initially set while it passes through a full moving range at comparatively low pulse frequency, and it is discriminated whether the motor moves accurately in response to driving pulses between detecting points until the motor passes one detecting point and again reaches this detecting point.

Abstract: A sewing machine with a needle bar mounted in a rocker, has a step motor drive for the oscillation of the rocker. A memory is used in which are contained selected digital data for influencing the step motor and a control unit is inserted between the memory and the step motor for selection and conversion of the digital data into stepping pulses for the step motor. A pulse generator operating synchronously with a main shaft of the sewing machine is used for triggering the transmission of stepping pulses to the step motor. To improve the drive transmission and to avoid reactions on the step motor, the step motor is connected to a lever arm of the rocker via an eccentric transmission.

Abstract: In the invention, the sewing machine carries out winding of the thread by operating separately a thread winding mechanism and a clutch mechanism. A speed detector is provided to measure actual rotary speed of a mechanism which is related with rotation of an upper shaft. If the thread winding were carried out, while said mechanism is left as engaged with a power source of the sewing machine, the speed detector would detect the rotation of said mechanism to stop a machine motor instantaneously, so that the thread winding cannot be performed when said relative mechansim is not released from the power source, and the needle bar is not actuated at winding the thread for safety in operation.

Abstract: A zig zag sewing machine having a feed device for feeding a workpiece in a feed direction on a work bed, an endwise reciprocable needle bar for carrying a needle, and a support member joggable laterally with respect to the feed direction and supporting the needle bar, including a detector having a light emitting portion and a light receiving portion and disposed on the support member for detecting the edge of the workpiece extending in the feed direction. The detector is movable laterally with respect to the feed direction in a predetermined positional relation with the support member at least when the support member is laterally moved. The lateral positions of the support member and the detector are changed by a driving device which is controlled so that an amount of light received by the light receiving portion coincides with a predetermined amount, whereby successive stitches to be formed by the needle are placed on a line which is away from the workpiece edge by a predetermined constant distance.

Abstract: In the present invention, a timing pulley is moved to a start point position in which a start point switch is switched on or off by a pulse motor, the start point position is memorized in a memory of a control circuit, key codes of selected pattern selection switches are calculated, a driving step number of the pulse motor is calculated by cam position data of a selected pattern obtained by the key codes, the cam position data being previously memorized in a memory, and position data of pattern cam selected in the present time, the position data being memorized in a random access memory and a cam-follower is moved to the position of the selected pattern cam by driving the pulse motor.

Abstract: An optical sensor system senses encodings on workpiece holders being processed within an automatic sewing machine. The optical sensor system can reliably sense the encodings on the workpiece holders over a wide range of spaced distances dictated by workpiece holder configurations encountered within automatic sewing machine systems.

Abstract: A specific pattern for adjusting a fabric feeding amount in an electronic sewing machine with a storage for storing stitch control data for a plurality of different patterns. The specific pattern includes a 1st stitching group stored in the sewing machine and used for stitching the whole pattern in a reverse feed, a 2nd stitching group which coincide with the first one when a feed reference point is adjusted properly, and at least a 3rd stitching group which is stitched by a plurality of forward feeds and rearward feeds and is positioned in opposition to the 1st stitching group relative to a middle basic line, and gives to the 2nd stitching group accumulative errors of the forward feed and the rearward feed, so that a balance between the feeding amounts in a forward and a rearward directions of stitching is conformed.

Abstract: In backward progress of straight stitching, stitches are conformed to either a perfect stitch or a hitch stitch without causing mixture of them, and while a needle is turned at a determined one of a right line or a left one from a basic line just before the needle drops on the basic line of a straight stitching, a condition of the thread to penetration of the needle is regulated before the needle dropping, whereby the stitch forming conditions are made uniform, so that satisfactory stitches are formed without requiring any special processes to the stitch forming mechanism members.

Abstract: A position detecting device of a contacting system is incorporated in a computerized sewing machine, which actuates in relation with an output shaft of a pulse motor at an initial setting during sewing operation of a feed control pulse motor or an amplitude control pulse motor, outside of the control region of each of said pulse motors, and the pulse motors are initially set within said control regions by signals from the position detecting device. Therefore a device for initially setting the computerized sewing machine may be provided which is excellent in durability and could promise a stable initial setting for a long period of time.

Abstract: In an electronic sewing machine, a pattern data memory has memory locations which are accessed in such a manner that address signals are prepared at random. These random address signals are used as stitch data to produce a specific version of a selected pattern.

Abstract: An electronic sewing machine with a dot matrix display for representing the image of a selected pattern to be stitched, having a first memory which stores stitch control data which may be sequentially read out in dependence upon a selected pattern per rotation of the sewing machine and transmitted to a driving part of a stitch forming mechanism; prior to initiation of the driving part, a calculator receives the read out stitch control data to make calculations for linearly interpolating between the adjacent stitches, thus to repeatedly renew the stitch control data into display data; a second memory stores the display condition data for controlling the cycle of pattern unit to be displayed; a counter counts up the cycles of the selected pattern in reference to the renewed stitch control data.

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 feed drive for a stitch group sewing machine includes a cam plate serving to drive a cloth clamp and it is connected with a separate motor. In order to keep the stitch length constant at varying length of the stitch group, the motor speed is controllable by a control device as a function of the rotational speed of the sewing machine, of the transmission ratio of a gearing between cam plate and cloth clamp which determines the length of the stitch group, and of the adjusted stitch length. The stitch group to be sewn can be divided into two sections with a stitch length variable independently of each other, in that a path-dependent switch operable after a partial revolution of the cam plate corresponding to the length of the first section alternately connects one of two potentiometers which determine the stitch length, with the motor control circuit.