Abstract: A sewing device includes a material wrapped around a spool (the spool rotating around an axis), and a needle with a hole through which the material passes. A material feeding mechanism moves the needle and feeds the material in a feeding direction, thereby unraveling the material from the spool and stitching the material into a workpiece. A controller controls the material feeding mechanism to move the needle to a first rest position above a top surface of the workpiece. The first rest position is determined by the following formula: PR1=PW1+AT; wherein PR1 is the first rest position; PW1 is a first position of the top surface of the workpiece; and AT is an amount of material to be used in forming a second stitch in the workpiece after forming a first stitch in the workpiece.

Abstract: A device and method for continuously regulating the amount of thread stripped from a supply spool and fed to a sewing needle during embroidery is provided. In commercial embroidering, the lengths of consecutive stitches can vary widely. The invention allows the machine to apply optimal tension to all embroidery stitches, regardless of their differing lengths. Pulling all stitches under optimal tension improves the appearance of the finished stitches and reduces the breakage and fraying of the thread. In the preferred embodiment of the invention, a digital computer controls a programmable servomotor, which in turn regulates the action of the embroidery machine's take-up and driver lever. The take-up in turn regulates the length of thread stripped from the supply bobbin and fed to the current stitch. In an alternative embodiment, the take-up and driver lever are replaced by a wheel, which is connected to the servomotor.

Abstract: A sewing machine for automatic thread taking-up and threading comprising a guide groove for guiding a needle thread to a threading preparatory position in the vicinity of a needle bar via a thread taking-up preparatory position intersecting a thread take-up moving area, a sewing machine motor driver for extracting the needle thread along the thread take-up moving area and for instructing a thread take-up to catch the needle thread, a pulse motor driver for threading the needle thread to an eye of a needle, a threading switch for generating signals, and an electronic control circuit for controlling the pulse motor driver and the sewing machine driver at prescribed timings in response to the signals from the threading switch. In the sewing machine, an operator has only to prepare a needle thread along the guide groove and push the threading switch.

Abstract: A sewing machine for automatic thread take-up and threading, which comprises a guide groove for guiding a needle thread from a bobbin to a threading preparatory position via a thread take-up preparatory position, a sewing machine motor driver and a sewing machine motor for extracting the needle thread at the thread take-up preparatory position along the thread take-up moving area and for taking up the needle thread using a thread receiver and/or a thread take-up, and a thread positioning member for keeping the end of the needle thread guided to the threading preparatory position and for positioning the needle thread in front of or at the rear of the eye of a needle, a threading member for performing the threading operation of the needle thread, and a prohibiting member for prohibiting the threading operation until the thread take-up operation is over. In the sewing machine, the thread take-up operation and the heading operation are automatically and successively performed.

Abstract: A method of automatically controlling thread tension in a sewing machine according to which a first thread tension device is provided between an upper thread source and a thread take-up lever, and a second thread tension device is provided between the first tension device and the thread take-up lever. The first thread tension device is operated to apply a constant pressure to the upper thread such that the thread take-up lever is able to draw out the upper thread upon moving upward. The second thread tension device is operated to fixedly hold the upper thread until the thread take-up lever moves upward to an upper dead point thereof through a lower dead point thereof, at which the take-up lever moves downward to supply the upper thread to the needle. The second thread tension device is further operated to effect release of the upper thread when the thread take-up lever reaches the upper dead point thereof and until the thread take-up lever moves downward to a thread supply starting position thereof.

Abstract: A sewing machine having a vertically reciprocating needle carrying an upper thread, a needle plate secured to a sewing machine housing and provided with a needle penetrating hole, a loop-taker arranged below the needle plate and operated in synchronism with reciprocation of the needle for interlocking a lower thread carried thereby with the upper thread, and a feed dog for feeding a fabric placed on the needle plate in a predetermined direction on which a stitch composed of the interlocked upper and lower threads has been formed. A swingable arm is operated to interfere with the normal travelling path of the lower thread between the loop-taker and the needle hole to draw a predetermined amount of the lower thread out of the loop-taker, while the fabric is not being fed.

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: A lower thread drawing-out device for a computerized sewing machine, the device having a cup-shaped loop taker with a surrounding wall. The loop taker is rotatable in a timed relation with a vertical reciprocation of the needle to catch the upper thread to concatenate with the lower thread and thereby form lock stitches. A bobbin is arranged in the loop taker so as to form a space between the bobbin and the loop taker surrounding wall. A lower thread drawing out element having a free end in the space is arranged so that when a lower thread is wrapped around the bobbin and extends to a needle, the free end contacts the lower thread at a location. The lower thread drawing out element is rotatable relative to the loop taker. The lower thread is movable transversely at the contact location relative to the lower thread when extended and in response to a rotation of the element relative to the loop taker, thereby compensating for biasing of the lower thread.

Abstract: A lockstitch sewing machine has, in addition to stitch forming instrumentalities (22, 24), a needle thread control arrangement (32) by which the tension in the needle thread (T2) is controlled during stitch formation. In addition, said arrangement (32) ensures that each formed stitch is drawn into the body of the workpiece, by pulling on the thread while it remains clamped by thread clamping means (200, 202). This pulling takes place in the early stages of the formation of the next stitch so that, at the end of the machine stitching cycle, the final stitch is not set by this arrangement (32). Instead, electrically actuated stitch setting means (220 to 226) is provided operable in response to an "end of cycle" signal supplied by control means by which further "end of cycle" functions (e.g. release of a presser foot (36) and of the thread clamping means (200, 202) are also controlled.

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 lock stitch sewing machine is provided with mechanism operable by a feed dog for pulling thread for stitches from a bobbin spool in amounts predetermined by the setting of a stitch length regulator.