A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

A sewing control device includes in a sewing machine having upper feed function a control device which controls feed of an object to be sewn. A lower feed amount setting motor sets a feed amount of a lower feed dog and an upper feed amount change motor changes a feed amount of an upper feed dog. A feed execution range, in which the feed of the object to be sewn is executed by an appropriate feed amount while the object to be sewn is sandwiched between the lower feed dog and the upper feed dog, and a feed non-execution range, in which the feed of the object to be sewn is not executed in a state in which the feed dogs do not act on the object to be sewn, are present. The feed amount of the upper feed dog can be changed only in the feed non-execution range during sewing.

A position indicating circuit includes: first and second input terminals for respectively receiving first and second voltages; an output terminal; a first resistor; and a second resistor having a first terminal coupled to the first input terminal through the first resistor, a second terminal coupled to the second input terminal, and a third terminal coupled to the output terminal. The second resistor is used to be actuated by a pedal of a foot controller of a sewing machine such that a voltage at the output terminal has a magnitude related to a position of the pedal. A detecting system that uses the position indicating circuit and that can determine whether the foot controller is coupled to a main body of the sewing machine is also provided.

A position indicating circuit includes: first and second input terminals for respectively receiving first and second voltages; an output terminal; a first resistor; and a second resistor having a first terminal coupled to the first input terminal through the first resistor, a second terminal coupled to the second input terminal, and a third terminal coupled to the output terminal. The second resistor is used to be actuated by a pedal of a foot controller of a sewing machine such that a voltage at the output terminal has a magnitude related to a position of the pedal. A detecting system that uses the position indicating circuit and that can determine whether the foot controller is coupled to a main body of the sewing machine is also provided.

A foot-operated controller of a sewing machine including a first pedal that input a number of revolution of a sewing machine motor by stepping of a user, a second pedal pressed by the user, a main body that supports the first pedal, and a support unit that supports the second pedal, in which the support unit is selectively attachable in disposition where the second pedal is on the left side of the first pedal and disposition where the second pedal is on the right side of the first pedal. In both cases where the second pedal is on the left side of the first pedal and the right side of the first pedal, across an interval between the main body and the support unit, it is possible to detect the pressing to the second pedal with respect to the second element.

A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

A foot controller includes: a pedal portion that is to be depressed by a foot thereon; a pedal stand on which one end of the pedal portion is supported so that the pedal portion freely pivots about a pivot portion; a speed control member that controls an operation speed of a sewing machine; and a depression suppression member that regulates and controls a depressing operation of the pedal portion in accordance with the depression speed of the pedal portion. In response to a depressing operation which does not involve an abrupt speed change of the pedal portion, the depression suppression member is not operated and the operation speed of the sewing machine is controlled according to an amount of depression of the pedal portion. In response to a depressing operation which involves an abrupt speed change of the pedal portion, the depression suppression member is operated.

A sewing control device includes in a sewing machine having upper feed function a control device which controls feed of an object to be sewn. A lower feed amount setting motor sets a feed amount of a lower feed dog and an upper feed amount change motor changes a feed amount of an upper feed dog. A feed execution range, in which the feed of the object to be sewn is executed by an appropriate feed amount while the object to be sewn is sandwiched between the lower feed dog and the upper feed dog, and a feed non-execution range, in which the feed of the object to be sewn is not executed in a state in which the feed dogs do not act on the object to be sewn, are present. The feed amount of the upper feed dog can be changed only in the feed non-execution range during sewing.

A foot-operated controller of a sewing machine including a first pedal that input a number of revolution of a sewing machine motor by stepping of a user, a second pedal pressed by the user, a main body that supports the first pedal, and a support unit that supports the second pedal, in which the support unit is selectively attachable in disposition where the second pedal is on the left side of the first pedal and disposition where the second pedal is on the right side of the first pedal. In both cases where the second pedal is on the left side of the first pedal and the right side of the first pedal, across an interval between the main body and the support unit, it is possible to detect the pressing to the second pedal with respect to the second element.

A sewing machine includes a rotational speed determination unit configured to determine a rotational speed instruction value on the basis of information from a movement detection sensor that detects movement of a workpiece and a predetermined sewing pitch amount, an upper limit rotational speed setting unit configured to set an upper limit rotational speed value, a rotational speed control unit configured to control a rotational speed to the rotational speed instruction value and control the rotational speed to the upper limit rotational speed value when the rotational speed instruction value reaches the upper limit rotational speed value, and a sewing machine motor driven at the controlled rotational speed to operate a needle. Rotational speed control of the sewing machine motor according to a movement amount of the workpiece is executed, but the rotational speed is controlled so as not to exceed the upper limit rotational speed.