sewing machine

Abstract

Sewing machine (100), including: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor (16) which drives the needle vertical movement mechanism as a drive source; a transporter holder (32) which holds a transporter (31) which transports a workpiece on a needle plate (11); a horizontal transport mechanism (40) which receives a driving force from the sewing machine motor (16) and transmits a horizontal back-and-forth movement to the feed dog support (32); a vertical transport mechanism (60B) which imparts a vertical back-and-forth movement to the transporter holder (32); a press foot (71) which presses the workpiece from above; and a press height detection unit (76) which detects a height of the press foot (71), wherein the horizontal transport mechanism (40) includes a transport adjustment motor (57) which changes and adjusts the division of the horizontal reciprocating movement by the sewing machine motor (16) with respect to the feed dog support (32), the vertical transport mechanism (60B) comprises a vertical transport motor (66) which provides the vertical reciprocating movement with respect to the feed dog support (32) as a drive source, and wherein the sewing machine (100) comprises a control device (90) which controls the vertical transport motor (66) to increase the height of the feed dog (31) in a transport section when the presser height detection unit (76) detects that the presser foot (71) is running over a stepped part of a thicker area of ​​the workpiece.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a sewing machine which performs a transport adjustment. Related state of the art

[0002] A sewing machine which transports a fabric clamped between a presser foot and a feed dog typically uses a transport mechanism which employs a feed dog that is mechanically linked to a main shaft (see JP 2013- 146 326 A).

[0003] Furthermore, the sewing machine is equipped with a presser foot lifting mechanism, comprising a presser rod which holds a presser foot, a presser spring which exerts a downward pressing pressure on the presser foot through the presser rod, a lever which applies a lifting operation to the presser rod against the action of the presser spring, and a solenoid which applies a lifting operation to the lever via a plurality of connecting link bodies.

[0004] Then the press foot is lowered by spring pressure from the press spring with no drive of the solenoid or minimal pressure, while the press foot is raised by drive of the solenoid (see, for example, JP 2011-092523A).

[0005] A fabric feed device for a sewing machine is known from JPH04-156 883 A. A sewing machine is described in JP 2015-150 361 A. A feed device for a sewing machine is disclosed in JP 2006-141 547 A. Summary

[0006] However, in state-of-the-art sewing machines, which transport the fabric by clamping it between a presser foot and a feed dog, the problem arises that at a stepped section where the fabric becomes thicker, the presser foot is raised and the pressing pressure is reduced.

[0007] In this case, increasing the height of the conveyor reduces the gap between the conveyor and the press foot, thus compensating for a reduction in pressing pressure. However, with the conveyor mechanism featuring a conveyor mechanically linked to a main shaft, as disclosed in JP 2013-146 326 A, it is difficult to change the conveyor height while the main shaft is rotating.

[0008] In the presser lifting mechanism disclosed in JP 2011-092 523 A, it is difficult to make any adjustment of the presser foot pressure by control because the solenoid is used as a drive source for lifting the presser foot.

[0009] Furthermore, a problem arises in that a thread becomes loosened when the presser foot runs over the stepped part.

[0010] One object of the invention is to enable a change of a parameter, for example a vertical transport amount, a pressing pressure or a thread tension, after detection of the stepped part where the workpiece becomes thicker. (1) To solve the above-mentioned problem, a sewing machine according to the present invention comprises: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor which drives the needle vertical movement mechanism as a drive source; a feed dog support which holds a feed dog which transports a workpiece on a needle plate; a horizontal feed mechanism which receives a drive force from the sewing machine motor and transmits a horizontal reciprocating motion to the feed dog support; a vertical feed mechanism which imparts a vertical reciprocating motion to the feed dog support; a presser foot which presses the workpiece from above; and a presser height detection unit which detects the height of the presser foot.The horizontal feed mechanism includes a feed adjustment motor, which modifies and adjusts the horizontal reciprocating motion of the sewing machine motor relative to the feed dog support. The vertical feed mechanism includes a vertical feed motor, which provides the vertical reciprocating motion relative to the feed dog support as a drive source. The sewing machine includes a control unit that controls the vertical feed motor to increase the feed dog height in a feed section when the presser height detection unit detects that the presser foot is moving over a stepped portion of a thicker area of ​​the workpiece. (2) The sewing machine according to (1) further comprises: a presser bar which holds the presser foot at a lower end of the presser bar; a presser spring which exerts a pressing force on the presser foot through the presser bar with respect to the workpiece; and a feed motor which performs a raising and lowering operation of the presser foot and which adjusts the pressing force on the workpiece by the presser foot by setting an expansion amount of the presser spring. The control device controls the feed motor to exert a greater pressing force of the presser foot on the workpiece when the presser height detection unit detects that the presser foot is passing over the stepped part. (3) In the sewing machine according to (1) or (2), the presser height detection unit comprises: a detection object which moves up and down together with the presser foot; and a line sensor which optically detects a height of the detection object. (4) The sewing machine according to any one of points (1) to (3) further comprises: a thread tensioner which applies tension to a thread to be sewn onto the workpiece and changes this tension by controlling the current value of a solenoid. The control device controls the thread tensioner to apply greater tension to the thread by controlling the current value of the solenoid when the presser height detection unit detects that the presser foot is passing over the stepped part.

[0011] According to the invention, it is possible to change the parameter, for example the vertical transport amount, the pressing pressure or the thread tension, after detection of the stepped part of the thicker area of ​​the workpiece.

[0012] Accordingly, even when the presser foot runs over the stepped part, the workpiece can be satisfactorily sewn while it is held between the presser foot and the feed dog. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view showing a configuration of main components in a bed area of ​​a sewing machine; Fig. Figure 2 is a perspective view of a transport adjustment mechanism; Fig. Figure 3 is a perspective view of a vertical transport mechanism; Fig. Figure 4 is an explanatory operational view of the vertical transport mechanism when the shaft angle of a vertical transport motor is 0°; Fig. Figure 5 is an explanatory operational view of the vertical transport mechanism when the shaft angle of the vertical transport motor is -5°; Fig. Figure 6 is an explanatory operational view of the vertical transport mechanism when the shaft angle of the vertical transport motor is +5°; Fig. 7 is a side view of a press foot mechanism; Fig. 8 is a front view of the press foot mechanism; Fig. 9 is a perspective view of the press foot mechanism; Fig. 10 is an explanatory operational view showing a state in which the presser foot of the presser foot mechanism is in an up-retract position; Fig. Figure 11 is an explanatory operational view showing a state in which the presser foot of the presser foot mechanism is lowered to a stitch plate; Fig. Figure 12 is an explanatory operational view showing a state in which the presser foot of the presser foot mechanism applies a pressing pressure to the needle plate; Fig. Figure 13 is a block diagram showing a control system of the sewing machine; Fig. 14 is a diagram showing the path of a transporter at the time of transport; Fig. 15 is a diagram showing a relationship between a harmonic angle and the shaft angle of the vertical transport motor in path pattern data from Fig. Figure 14 shows which are obtained by a clockwise rotation and a counterclockwise rotation; and Fig. Figure 16 is a flowchart of a press spring identification process, which is carried out by a control device. DETAILED DESCRIPTION [Overall configuration of the embodiment]

[0013] The following describes in detail a sewing machine according to one embodiment of the invention.

[0014] Fig. Figure 1 is a perspective view showing main configurations in a bed area of ​​a sewing machine 100.

[0015] As in Fig. As shown in Figure 1, the sewing machine 100 comprises a needle vertical movement mechanism (not shown) for moving a sewing needle up and down, a sewing machine motor 16 (see Figure 1). Fig. 13), which serves as a drive source, an upper shaft (not shown) which is set in rotation by the sewing machine motor 16, a shuttle 12 for joining an upper thread to a lower thread, a feed mechanism 30 for transporting a fabric, i.e. a workpiece, on a needle plate 11 according to the vertical movement of the sewing needle, a belt mechanism 20 for transmitting a rotational force from the upper shaft to a lower shaft 33 of the feed mechanism 30, a thread cutting device 14 (see Fig. 13) for cutting the upper thread and the lower thread, a presser foot mechanism 70 for performing a raising and lowering operation of the presser foot 71, a sewing machine frame 110 (see Fig. 7) for holding the components described above and a control device 90 (see Fig. 13) to control each of the components.

[0016] The sewing machine 100 is a so-called lockstitch sewing machine. Therefore, the sewing machine 100 includes a thread take-up mechanism, a thread tensioner, a presser foot, and other components typical of a lockstitch sewing machine. Since these components are well-known, their description is omitted.

[0017] The sewing machine frame 110 comprises a sewing machine bed area 101, which is arranged in a lower area of ​​the overall structure of the sewing machine, a vertical stand area 102, which stands at one end of the sewing machine bed area 101 in a longitudinal direction thereof, and a sewing machine arm area 103, which extends from an upper end of the vertical stand area 102 in the same direction as the sewing machine bed area 101 (see Fig. 7).

[0018] A front end (end on one side of a surface area) of the sewing machine bed area 101 indicates a stitch position, and the stitch plate 11 is located on an upper surface of the bed area 101.

[0019] In the following description, a horizontal direction parallel to the longitudinal direction of the sewing machine bed area 101 is referred to as a Y-axis direction, and a horizontal direction orthogonal to the Y-axis direction is referred to as an X-axis direction. A direction orthogonal to both the X-axis and Y-axis directions is referred to as a Z-axis direction. [Configuration of the needle vertical movement mechanism and the belt mechanism]

[0020] The needle vertical movement mechanism comprises: a shaft which is arranged in the sewing machine arm area 103, is set in rotation by the sewing machine motor 16 and is directed in the Y-axis direction; a needle bar which holds the sewing needle at its lower end; and a crank mechanism (not shown) which converts the rotational force of the shaft into a reciprocating driving force for a vertical reciprocating movement and transmits the reciprocating driving force to the needle bar.

[0021] A belt mechanism 20 comprises a main drive pulley, which is fixedly mounted on the upper shaft, a driven pulley 21, which is fixedly mounted on the lower shaft 33 of the transport device 30, and a timing belt 22, which is tensioned between the drive pulley and the driven pulley 21. The belt mechanism 20 causes the lower shaft 33 to rotate at the same speed as the upper shaft.

[0022] Alternatively, the transmission of the rotational force from the upper shaft to the lower shaft 33 can be carried out via a gear transmission mechanism with a vertical shaft and a bevel gear instead of via the belt mechanism. [Transport equipment]

[0023] As in Fig. As shown in Figure 1, the transport device 30 comprises a feed dog 31, which partially emerges from an opening in a stitch plate 11 to transport a fabric in a predetermined direction, a feed dog holder 32 which holds the feed dog 31, a horizontal transport mechanism 40 which receives power from the sewing machine motor 16 and transmits a back-and-forth movement in the X-axis direction (the horizontal direction) to the feed dog holder 32, and a vertical transport mechanism 60B which imparts a vertical back-and-forth movement to the feed dog holder 32. [Horizontal transport mechanism]

[0024] The horizontal transport mechanism 40 comprises a transport adjustment mechanism 50 for adjusting the stroke of a reciprocating movement in the X-axis direction with respect to the conveyor bracket 32, a connecting rod 41 for transferring the reciprocating movement in the X-axis direction from the lower shaft 33, a horizontal transport shaft 42, to which a reciprocating rotation is imparted by the connecting rod 41 via the transport adjustment mechanism 50, and a horizontal transport arm 43 for converting the reciprocating rotational driving force of the horizontal transport shaft 42 into a reciprocating driving force, which is exerted in a transport direction, and for transmitting the reciprocating driving force to the conveyor bracket 32.

[0025] The connecting rod 41 has a first end that rotatably holds an eccentric cam body (not shown) fixedly mounted on the lower shaft 33, and a second end that is connected to the transport adjustment mechanism 50. The connecting rod 41 is arranged such that its longitudinal direction essentially coincides with the X-axis direction. Thus, when the lower shaft 33 completes a full revolution, the second end of the connecting rod 41 performs a reciprocating motion in its longitudinal direction with a stroke that is twice the eccentricity of the eccentric cam body. This reciprocating motion of the connecting rod 41 is transmitted as a reciprocating rotational force via the transport adjustment mechanism 50 to the horizontal transport shaft 42.

[0026] As in Fig. As shown in Figure 2, the transport adjustment mechanism 50 comprises: a swing arm 51, which is fixedly mounted on the horizontal shaft 42 and extends outwards in a radial direction of the horizontal transport shaft 42; a pair of first connecting link bodies for connecting the second end of the connecting rod 41 and the swing arm 51; a pair of second connecting link bodies 54 for guiding the direction of the reciprocating movement of the second end of the connecting rod 41 in a specific direction; a transport adjustment body 55 for determining the direction of the reciprocating movement, which is guided by the second connecting link bodies 54; a support shaft 52, which rotates together with the rotation of the transport adjustment body 55; an input arm 56, which is fixedly mounted on the support shaft 52 and extends outwards in a radial direction of the support shaft 52;a transport adjustment motor 57, which rotates the transport adjustment body 55 to adjust the amount of a back-and-forth movement in the X-axis direction (the horizontal direction), which is transmitted from the lower shaft 33 to the conveyor bracket 32; and two transmission connecting elements 58 and 59, which transmit a rotational force from an output shaft of the transport adjustment motor 57 to the input arm 56.

[0027] A first end of the first connecting link body 53 is connected to the second end of the connecting rod 41, and a second end of the first connecting link body 53 is connected to a swing end of the swing arm 51. Both the first and second ends of the first connecting link body 53 are connected so as to be rotatable about the Y-axis direction.

[0028] A first end of the second connecting link body 54 and the first end of the first connecting link body 53 are connected to the second end of the crank rod 41, and a second end of the second connecting link body 54 is connected to a rotatable end of the transport adjusting body 55. The first and second ends of the second connecting link body 54 are connected so as to rotate about the Y-axis direction.

[0029] The support shaft 52 extending in the Y-axis direction is fixed to a base area of ​​the transport adjustment body 55, and the support shaft 52 is mounted within the sewing machine frame so as to be rotatable around the Y-axis.

[0030] The rotatable end of the transport adjustment body 55 is rotatably connected to the second end of the second connecting element body 54 about the Y-axis.

[0031] Regarding the transport adjustment mechanism 50, when the transport adjustment body 55 is rotated such that the longitudinal direction of the first connecting link body 53 coincides with the longitudinal direction of the second connecting link body 54, i.e., when the connecting link bodies 53 and 54 are superimposed, it is not possible to transmit the driving force of the crank rod 41 to the swing arm 51. At this point, due to the fact that the reciprocating rotational movement is not transmitted to the horizontal transport shaft 42, the stroke of the reciprocating movement of the transporter bracket 32 ​​in the X-axis direction is equal to 0, i.e., the sewing pitch is equal to 0. Thus, the rotation angle of the transport adjustment body 55, at which the connecting link bodies 53 and 54 are superimposed, is defined as the "neutral angle of the transport adjustment body 55".

[0032] When this transport adjusting body 55 is rotated in one direction starting from the neutral angle, the swing arm 51 can be given a back-and-forth oscillating movement according to a rotation angle amount, thereby increasing the sewing pitch in a forward transport direction.

[0033] Conversely, if the transport adjusting body 55 is rotated backwards from the neutral angle, the swing arm 51 can also be given a back-and-forth oscillating motion corresponding to the rotation angle. In this case, however, the phase of the oscillating motion is reversed, and the reversed phase of the oscillating motion is transmitted to the swing arm 51, thereby increasing the stitch pitch in a reverse transport direction.

[0034] The feed adjustment motor 57 is arranged in an end region of the sewing machine bed area 101 in the Y-axis direction, with its output shaft oriented in the Y-axis direction. A first end of the transmission link 58 is fixedly mounted to the output shaft of the feed adjustment motor 57, with the longitudinal direction of the transmission link 58 being oriented essentially in the X-axis direction. Thus, when the feed adjustment motor 57 is driven for operation, a second end of the transmission link 58 is rotated up and down.

[0035] The lower end of the transmission link 59 is connected to the second end of the transmission link 58 so that it can be rotated about the Y-axis in a state where its longitudinal direction is essentially oriented in the Z-axis direction. Thus, when the transport adjustment motor 57 is driven into operation, the transmission link 59 as a whole performs a vertical movement.

[0036] The input arm 56 is fixedly mounted on the support shaft 52 and extends from the support shaft 52 essentially in the X-axis direction. A distal end of the extension of the input arm 56 is rotatably connected to an upper end of the transmission connecting element 59 to allow rotation about the Y-axis.

[0037] Consequently, when the transport adjustment motor 57 is driven, the transport adjustment body 55 can be rotated via the transmission connecting elements 58 and 59 and the input arm 56.

[0038] The horizontal transport shaft 42 is rotatably mounted in the sewing machine bed area 101 and oriented in the Y-axis direction. Furthermore, the horizontal transport shaft 42 extends downstream (left side in Fig. 1) the lower shaft 33 is arranged in a sewing material transport direction. From the lower shaft 33, a reciprocating rotational force is applied to a first end of the horizontal transport shaft 42, which is an end close to the vertical stand area 102, via the transport adjustment mechanism 50 described above, and the reciprocating movement in the X-axis direction is transmitted from the second end of the horizontal transport shaft 42 via the horizontal transport arm 43 to the feed dog holder 32.

[0039] A base area of ​​the horizontal transport arm 43 is rigidly connected to an end of the horizontal transport shaft 42, which is an end near the needle plate 11, and a vibrating end of the horizontal transport arm 43 is connected to the feed dog holder 32 in a state in which the vibrating end is an upper end of the horizontal transport arm 43.

[0040] Thus, the horizontal feed arm 43 of the feed dog bracket 32 ​​can be driven back and forth in the X-axis direction when the sewing machine motor 16 is powered for operation. Furthermore, the stroke of the back-and-forth movement of the feed dog bracket 32 ​​in the X-axis direction can be freely adjusted by controlling the feed adjustment motor 57 of the feed adjustment mechanism 50.

[0041] The feed dog support 32 is located below the needle plate 11. One end of the feed dog support 32, which is in the direction of fabric transport (X-axis direction), is connected to the vertical feed mechanism 60B, and a second end of the feed dog support 32 is connected to the horizontal feed arm 43. Furthermore, the feed dog 31 is installed above the feed dog support 32 and fixed at a position located in the middle of the longitudinal direction of the feed dog support 32.

[0042] Thus, the first end of the feed dog support 32 is subjected to a reciprocating driving force acting in the vertical direction, and the second end of the feed dog support 32 is subjected to a reciprocating driving force acting in the transport direction in the same cycle. Since these reciprocating driving forces add up, the feed dog support 32 performs an elliptical movement in an XZ plane. The feed dog 31 also performs an elliptical movement along with the feed dog support 32. At this point, as the feed dog support 32 moves along an upper part of the path of the elliptical movement, the tip of the feed dog 31 partially protrudes upwards through the opening of the needle plate 11, thereby transporting the fabric. [Vertical transport mechanism]

[0043] Fig. Figure 3 is a perspective view of the vertical transport mechanism 60B and Fig. Figures 4 to 6 show explanatory operational views of the Vertical Transport Mechanism 60B.

[0044] The vertical transport mechanism 60B comprises a vertical transport motor 66, which serves as a drive source for the reciprocating movement in the vertical direction (the Z-axis direction) imparted to the feed dog support 32; a first connecting link 61B, which is connected to an output shaft of the vertical transport motor 66 to perform a rotational movement; a second connecting link 62B with a first end connected to a rotatable end of the first connecting link 61B; a third connecting link 63B with a first end connected to a second end of the second connecting link 62B; a rotational shaft 67, which is connected to a second end of the third connecting link 63B and is fixed in position within the sewing machine frame; and a fourth connecting link 64, which is connected to the third connecting link 63B via the rotational shaft 67.and a fifth connecting link 65 with a first end which is connected to a rotatable end of the fourth connecting link 64, and with a second end which is connected to the first end of the conveyor bracket 32.

[0045] Instead of the vertical transport mechanism 60B described above, the use of a structure with a motor, an eccentric cam body and a connecting link or a structure with a motor and a rack and pinion drive is also easily conceivable.

[0046] The vertical feed motor 66 is located at an end of the sewing machine bed 101, near the needle plate 11, in the Y-axis direction. This means that the vertical feed motor 66 is spaced apart from the feed adjustment motor 57 of the feed adjustment mechanism 50, as described above. Both motors 57 and 66 require considerable installation space. However, since the motors 57 and 66 are spaced apart longitudinally within the sewing machine bed 101, the space between them can be used for a solenoid, which serves as a drive source for a thread cutter 14 and, like the motors, also requires considerable installation space.

[0047] Furthermore, the vertical transport motor 66 is arranged such that its output shaft is oriented in the Y-axis direction.

[0048] Furthermore, the vertical transport motor 66 has the same specifications and performance as the transport adjustment motor 57. The vertical transport motor 66 can be identical to the transport adjustment motor 57 in terms of model and type.

[0049] In this configuration, the motors and their peripherals can be shared, making it possible to reduce costs and increase maintenance efficiency.

[0050] The base area of ​​the first connecting element 61B, which serves as a center of rotation, is firmly held by the output shaft of the vertical transport motor 66.

[0051] On the other hand, the third connecting element 63B is held firmly by the rotating shaft 67, the second end of which is rotatably held by a frame of the sewing machine bed area 101.

[0052] The rotatable end of the first connecting element 61B and the rotatable end of the third connecting element 63B are rotatably connected to the first end and the second end of the second connecting element 62B about the Y-axis.

[0053] As in Fig. As shown in Figure 4, the lengths of the connecting elements one to three, 61B to 63B, are set such that the second connecting element 62B is substantially parallel to the X-axis direction in a state in which the first connecting element 61B is substantially parallel to the Z-axis direction, wherein its rotatable end is an upper end, and in a state in which the third connecting element 63B is substantially parallel to the Z-axis direction, wherein its rotatable end is an upper end.

[0054] Accordingly, the first connecting element 61B and the second connecting element 62B form an angle of 90° (a right angle) when the angle of the output shaft of the vertical transport motor 66 is set to a shaft angle of 0°, as shown in Fig. 4 is shown. This state is referred to as the "origin point" of a strand of connecting links, which consists of connecting links one to three, 61B to 63B.

[0055] At the wave angle designated as "origin point", the height of the transporter 31 is identical to the height of the upper surface of the needle plate 11.

[0056] On the other hand, as in Fig. As shown in Figure 5, the transporter 31 is raised to be higher than the upper surface of the needle plate 11 when the vertical transport motor 66 is driven to rotate in the reverse direction (counterclockwise) from the shaft angle, i.e., the origin point. Conversely, as shown in Fig. As shown in Figure 6, the transporter 31 is lowered to lie below a lower surface of the needle plate 11 when the vertical transport motor 66 is driven to rotate in a forward direction (clockwise).

[0057] In the sewing machine 100, the control device 90 performs an operational control such that, for each transport operation of the feed dog 31, the vertical transport motor 66 performs a single forward and backward rotation within an angular range (for example, origin ±10°) which does not reach an output wave angle at which the first connecting element 61B and the second connecting element 62B are aligned in a straight line to extend to their maximum extent.

[0058] Since the string of connecting links, consisting of the first to third connecting links 61B to 63B, maintains the rotary motion of the vertical feed motor 66 and the impingement of the feed dog support 32 with the vertical movement at an identical frequency, the stroke of the reciprocating motion is relatively small compared to a case in which the reciprocating motion for the horizontal feed is imparted by a separate motor independent of the sewing machine motor 16. Therefore, excellent tracking performance is achieved at high-speed sewing.Since the vertical transport motor 66 is driven to a rotational movement within a range which includes an axial angle in which the angle between the first connecting element 61B and the second connecting element 62B is a right angle, it is particularly possible to reduce the stroke of the reciprocating movement and thereby further improve the tracking performance of keeping pace with the high-speed sewing operation.

[0059] Furthermore: since the base area of ​​the fourth connecting element 64 is not fixed to the rotating shaft 67 in a state in which the fourth connecting element 64 is essentially oriented in the X-axis direction, the fourth connecting element 64 rotates together with the third connecting element 63B.

[0060] With the fifth connecting link 65 oriented essentially in the Z-axis direction, the first end of the fifth connecting link 65 is connected to the rotatable end of the fourth connecting link 64, and the second end of the fifth connecting link 65 is connected to the first end of the conveyor bracket 32. Therefore, the vertical movement via the fifth connecting link 65 can be transmitted to the conveyor bracket 32 ​​by the rotation of the fourth connecting link 64. [Thread cutting device]

[0061] The thread cutting device 14 comprises a fixed knife and a movable knife, which are arranged between the feed dog 31 and the shuttle 12, a cam body provided on the lower shaft 33, a cam body roller which engages with the cam body to cause the movable knife to perform a cutting operation, and a solenoid for engaging the cam body roller with the cam body. The solenoid operates under the control of the control device 90, and in response to the operation of the solenoid, the cam body roller engages with the cam body and thereby transmits a reciprocating motion to the movable knife, causing the movable knife to perform a cutting operation. In this way, the movable knife, in conjunction with the fixed knife, cuts an upper thread and a lower thread. [Press foot mechanism]

[0062] Fig. Figure 7 shows a side view of part of the sewing machine frame 110 (represented by a two-dot dashed line), illustrating an internal arrangement of the presser foot mechanism 70. Furthermore, Fig. 8 a front view of the presser foot mechanism 70, seen from a surface side, and Fig. Figure 9 is a perspective view showing a configuration of the presser foot mechanism 70 on the surface side.

[0063] As shown in these drawings, the press foot mechanism 70 comprises a press foot 71 which presses the workpiece from above, a press rod 72 which holds the press foot 71 at a lower end, a transport motor 73 which is a lifting and lowering drive source of the press foot 71, a transfer mechanism 74 which transmits a lifting and lowering operation from the transport motor 73 to the press rod 72 and the press foot 71, a press spring 75 which exerts a pressing pressure with respect to the workpiece on the press foot 71 through the press rod 72, and a press height detection unit 76 which detects a height of the press foot 71.

[0064] The presser foot 71 is a so-called boat-shaped presser, in which a lower surface is flat and an upflow side (front side) is curved upwards in a sewing material transport direction.

[0065] The presser rod 72 is held in order to be movable up and down by metal bearings 721 and 721, which are arranged at two points above and below inside the sewing machine arm 103 in a state extending along a Z-axis direction near the needle bar.

[0066] Between the metal bearing 721 on the upper side of the press rod 72 and the metal bearing 721 on the lower side of the same, both an upper rod connecting pin 722 and a lower rod connecting pin 723 are firmly arranged at the top and bottom by clamping.

[0067] A sleeve 725 is arranged on the lower side of the upper rod connecting pin 722, which is slidably movable up and down relative to the press rod 72. The coiled press spring 75 is arranged between the sleeve 725 and the lower rod connecting pin 723 in a state in which the press rod 72 is inserted.

[0068] The connecting rod pins 722 and 723 and the presser foot 71 are each fixed to the presser rod 72 by tightening set screws. When the set screws are loosened and all the components described above are removed, the presser rod 72 can be pulled upwards out of the sewing machine frame 110. In this way, the presser spring 75 can be replaced.

[0069] On the other hand, a number of types of press springs 75 with essentially the same inner diameters and different spring constants are prepared and can be appropriately selected and exchanged, depending on the pressing pressure required for different types of workpieces.

[0070] A vertical distance between the upper rod connecting pin 722 and the lower rod connecting pin 723 is set to be slightly wider than the combined length of the press spring 75 and the sleeve 725. The press spring 75 and the sleeve 725 are arranged with a small gap between the upper rod connecting pin 722 and the lower rod connecting pin 723.

[0071] The sleeve 725 is a cylindrical body into which the press rod 72 can be inserted. The lifting and lowering operation is applied to the sleeve 725 by the transport motor 73 via the transfer mechanism 74, and the sleeve 725 is positioned at any desired height.

[0072] When the sleeve 725 is lowered by the transport motor 73, for example, the lower press spring 75 is compressed, and the elastic force of the compressed press spring 75 is applied to the press foot 71 via the lower rod connecting pin 723. At this time, regardless of the sleeve 725's height, the press spring 75 can be compressed to any desired amount and can be adjusted to exert any desired pressing force.

[0073] Furthermore: when the sleeve 725 is lifted by the transport motor 73, the sleeve 725 comes into contact with the upper rod connecting pin 722 and the press rod 72 is lifted by the upper rod connecting pin 722, whereby the press foot 71 can be retracted into a release position of the workpiece, in which it is spaced upwards from the needle plate 11.

[0074] Furthermore, even when the presser foot 71 is lowered onto the upper surface of the needle plate 11, the presser rod 72 must be long enough that its upper end protrudes from the upper area of ​​the sewing machine arm section 103. The upper end of the presser rod 72 is equipped with a knob 724 for holding and manually raising the presser foot 71.

[0075] Since the raising and lowering operation of the presser foot 71 can be carried out by the transport motor 73, the presser foot mechanism 70 is not provided with a presser foot lifting lever, which is arranged in the existing sewing machine to carry out the raising and lowering operation of the presser foot 71 by manual actuation of a connecting link mechanism.

[0076] However, if the sewing machine's power supply is interrupted due to a power outage or similar event, the presser foot 71 remains in the lowered position. For this reason, the upper end of the presser rod 72 is equipped with the knob 724, making it possible to easily pull the presser foot 71 back up.

[0077] The transport motor 73 is held by a plate-like bracket 731 in the inner upper area of ​​the vertical stator area 102 in a state in which an output shaft of the same is aligned in the X-axis direction.

[0078] The transport motor 73 is a stepper motor and can be positioned at any shaft angle with a predetermined minute angle unit.

[0079] Although in the Fig. Figures 7 to 9 do not show the output shaft of the transport motor 73 connected to an encoder 732 (see Fig. 13), the wave angle of the output wave is detected and the wave angle is entered into the control unit 90.

[0080] The transfer mechanism 74 comprises a driving main gear 741, which is fixedly mounted on the output shaft of the transport motor 73, a driven gear 742, which is essentially fan-shaped, a connecting link 745, which is provided with fork-shaped pivot arms 746 and 747 and has a bell crank shape 745, and a connecting rod 749, which connects the driven gear 742 and the connecting link 745.

[0081] The driving main gear 741 is a spur gear and meshes with the driven gear 742.

[0082] The driven gear 742 is a fan-shaped gear, rotatably mounted about the X-axis in the sewing machine frame 110. The teeth meshing with the driving main gear 741 are formed only in a circular arc region of the latter. The teeth of the driven gear 742 have a larger effective diameter than those of the driving main gear 741, and the rotational input is transmitted from the driving main gear 741 to the teeth of the driven gear 742 in a state where it is largely reduced. Consequently, it is possible to increase the resolution of the compression adjustment of the presser spring 75 by the transport motor 73.

[0083] Furthermore, the driven gear 742 comprises an arm section 743, which extends in a radial direction of rotation, and the arm section 743 is rotatably connected to one end of the connecting rod 749 about the X-axis. When the driven gear 742 rotates by receiving a torque from the driving main gear 741, the driven gear 742 imparts a movement to one end of the connecting rod 749, which is directed essentially along the Y-axis.

[0084] The connecting rod 749 is essentially arranged along the Y-axis direction in the sewing machine arm area 103 and its other end is rotatably connected to a rotary arm 746 of the connecting link 745 about the X-axis.

[0085] The connecting element 745 is rotatably mounted about the X-axis in the sewing machine frame 110, such that one rotating arm 746 is oriented essentially in the Z-axis direction and the other rotating arm 747 is oriented essentially in the Y-axis direction. The other rotating arm 747 is connected to the sleeve 725 by a rectangular piece 748. The rectangular piece 748 is connected to the rotating arm 747 to be rotatable about the X-axis and is shaped into a rectangular, cuboid form. The sleeve 725 holds the rectangular piece 748 in a sandwich-like manner from the top and bottom sides, allowing movement of the rectangular piece 748 along the Y-axis direction.

[0086] Therefore, when the connecting link 745 rotates, the rotary arm 747 rotates in the vertical direction and transmits the vertical movement through the rectangular piece 748 to the sleeve 725. Since the rectangular piece 748 moves along a circular path, the rotation of the rotary arm 747 also results in a displacement in the Y-axis direction. However, because the rectangular piece 748 can only move in the Y-axis direction relative to the sleeve 725, only the movement in the Z-axis direction is transmitted to the sleeve 725.

[0087] The press height detection unit 76 mainly comprises a detection object 761, which is held by the lower rod connection pin 723, and a line sensor 762, which optically detects the height of the detection object 761.

[0088] Since the detection object 761 is held by the lower rod connecting pin 723, it moves up and down together with the press foot 71 and the press rod 72.

[0089] The line sensor 762 is designed with light-receiving elements arranged along the Z-axis. The line sensor 762 can detect the position (height) in the Z-axis direction of the upper end of the detection object 761 by being obscured by the detection object 761. [Sewing machine control system]

[0090] A control system of the sewing machine 100 is shown in the block diagram of Fig. 13 shown. As in Fig. As shown in Figure 13, the sewing machine 100 comprises the control unit 90, which performs operational control for each component of the sewing machine. The control unit 90 is connected to the sewing machine motor 16, the feed adjustment motor 57, the vertical feed motor 66, and the feed motor 73 by means of respective motor drive circuits 16a, 57a, 66a, and 73a.

[0091] The sewing machine motor 16 and the feed motor 73 are equipped with encoders 161 and 732, respectively, which detect a rotational speed. The encoders 161 and 732 are also connected to the control unit 90 via the motor drive circuits 16a and 73a, respectively.

[0092] The thread cutting device 14 is connected to the control device 90 and thus the solenoid, which is driven at the time of thread cutting, is controlled by the control device 90.

[0093] The control unit 90 comprises a CPU 91, a ROM 92, a RAM 93 and an EEPROM 94 (EEPROM is a registered trademark) and performs various types of operational controls, which will be described below.

[0094] ROM 92 contains various control programs, which will be described below.

[0095] The EEPROM 94 stores tabular data that individually corresponds to each of the multiple types of press springs 75 with different spring constants and indicates the relationship between the operating quantity of the transport motor 73 and the pressing pressure generated in the press foot 71. That is, the EEPROM 94 functions as a "tabular storage unit".

[0096] Furthermore, an operating input unit 96 is connected to the control unit 90 via an interface 96a to input selections and executions of various types of operational controls concerning the transport device 30, as described below, or to input set values ​​of the pressing pressure or the like for the press foot 71 via the press foot mechanism 70. As a consequence, the operating input unit 96 functions as a "pressing pressure setting unit" for setting the input of the pressing pressure.

[0097] Furthermore, a pedal 95 is connected to the control unit 90 via an interface 95a in order to input the sewing start command based on a pedal operation and a sewing speed according to the extent of the pedal pressing.

[0098] The operating input unit 96 includes a display unit 961 and shows information necessary for entering various set values. For example, when the pressing pressure of the press foot 71 is set by the press foot mechanism 70, the operating input unit 96 displays an upper and a lower limit of a set value for the pressing pressure and a settable numerical value range (resolution) of the pressing pressure.

[0099] Furthermore, a line sensor 762 is connected to the control unit 90 via an interface 762a in order to detect the height of the press foot 71.

[0100] Furthermore, a thread tensioner 101 is connected to the control unit 90 via an interface 101a, whereby a thread tension is set by controlling a current value of the solenoid. [Operational control of the transport system]

[0101] In the sewing machine 100, the path of the circular movement of the feed dog 31 can be freely changed by controlling the vertical transport motor 66, since the vertical feed motor 66 causes a vertical back-and-forth movement of the feed dog 31 independently of the sewing machine motor 16.

[0102] Fig. Figure 14 shows a path of a reference shape during normal transport. Fig. Figure 14 indicates the horizontal axis as the position of the feed dog 31 in the X-axis direction, and the vertical axis as the position of the feed dog 31 in the Z-axis direction. The left side of the horizontal axis is the downstream side in the transport direction, and position zero on the horizontal axis designates a stitch position. Furthermore, position zero on the vertical axis is the height of the upper surface of the stitch plate 11.

[0103] This path is an elliptical path that is essentially symmetrical with respect to the upper surface of the needle plate 11 on both the top and bottom sides. The area of ​​the angle of the upper shaft in which the tooth tip (the upper end) of the feed dog 31 is positioned to be higher than the upper surface of the needle plate 11 is defined as the 'feed section'.

[0104] The control unit 90 stores path pattern data in the EEPROM 94, in which the wave angle of the vertical transport motor 66 for positioning the conveyor 31 at each position of points arranged on the elliptical path is recorded in conjunction with the angle of the harmonic.

[0105] Since the wave angle of the feed adjustment motor 57 determines the horizontal width (sewing pitch) of the elliptical path, when setting the sewing pitch via the operating input unit 96, the wave angle of the feed adjustment motor 57, at which the sewing pitch becomes a set value, is maintained while the feed dog performs a circular movement.

[0106] During the sewing process, the control unit 90 reads the path pattern data and loads it into RAM 93, monitors the output of the encoder 161, and initiates a circular movement of the transporter 31 along the path of the vertical transport motor 66. Fig. 14 to be carried out by positioning the vertical transport motor 66 at the shaft angle determined in the path pattern data, each time the angle of the harmonic reaches a predetermined angle.

[0107] Fig. Figure 15 shows a relationship between the angle of the shaft (vertical axis) of the vertical transport motor 66 and the angle of the overshaft (horizontal axis), which corresponds to the in Fig. The path shown in section 14 will be obtained.

[0108] As in Fig. Figure 15 shows the change in the shaft angle of the vertical transport motor 66 in the Fig. The path pattern shown in 14 is a sine curve of approximately 2π.

[0109] Since the conveyor performs a single back-and-forth movement in a vertical direction when the vertical transport motor 66 performs a single back-and-forth rotation in the forward and reverse directions, there is no need to prepare two types of data: path pattern data obtained by clockwise rotation and path pattern data obtained by counterclockwise rotation. That is, only one type of path pattern data is managed. [Process concerning the press foot mechanism]

[0110] As described above, the presser foot mechanism 70 of the sewing machine 100 can selectively replace the presser spring 75, which determines the presser pressure, from among a plurality of types of presser springs 75 with different spring constants. Therefore, when the main power supply to the sewing machine 100 is switched on, the control unit 90 performs an identification process according to the program stored in the ROM 92 to determine whether the installed presser spring 75 is any of the plurality of types of presser springs 75.

[0111] The process of identifying the press spring is described below with reference to the information in the Fig. Figures 10 to 12 illustrate the explanatory operational view of the presser foot mechanism and the flowchart of Fig. 16 described.

[0112] When the main power supply of the sewing machine 100 is switched on, the control unit 90 first drives the transport motor 73 to lower the presser foot 71, which is located above the stitch plate 11 in a retracted position (step S1: Fig. 10).

[0113] The control unit 90 monitors the height of the press foot 71, which is detected by the line sensor 762, while the press foot 71 is being lowered. The control unit 90 then determines, based on the detected height of the press foot 71 as indicated by the line sensor 762, whether the press foot 71 has been lowered to the upper surface of the needle plate 11 (step S3: Fig. 11) When the presser foot 71 reaches the upper surface of the needle plate 11 due to the lowering movement, the height of the presser foot 71 detected by the line sensor 762 is in a stop state with respect to the lowering state. This makes it possible to determine whether the presser foot 71 has been lowered to the upper surface of the needle plate 11.

[0114] If it is determined that the press foot 71 does not reach the upper surface of the die plate 11 (step S3: NO), the control unit 90 continuously lowers the press foot 71 (step S1). If it is determined that the press foot 71 reaches the upper surface of the die plate 11 (step S3: YES), the control unit 90 stores a motor position, which is specified by the encoder 732 at the time of arrival, as an origin position and drives the transport motor 73 in the lowering direction by a predetermined amount from the origin position (step S5: Fig. 12).

[0115] The control unit 90 detects a drive current of the transport motor 73 using the motor drive circuit 73a and detects the increment of the drive current from the initial position (step S7). When the transport motor is lowered by the predetermined amount from the initial position, the press spring 75 is compressed by a specific length, and thus the spring constant of the press spring 75 can be specified by obtaining an increase in the torque of the transport motor 73 from the increment of the drive current. Accordingly, the control unit 90 can identify from the increment of the drive current whether the press spring 75 attached to the press rod 72 is one of the multiple types of press springs 75 with different spring constants (step S9 [function of identifying the spring type]).

[0116] Furthermore, the control unit 90 selects table data corresponding to the present press spring 75 from a plurality of types of table data, which specifies a relationship between the operation amount of the transport motor 73 recorded in the EEPROM 94 and the pressing pressure generated in the press foot 71 (step S11).

[0117] Furthermore, the control unit 90 sets an upper limit and a lower limit of the pressing pressure, which is to be displayed at the operating input unit 96 at the time the pressing pressure is set, and sets a settable numerical value range (resolution) of the pressing pressure to values ​​which correspond to the present press spring 75 (step S13).

[0118] The control device 90 then completes the process of determining the press spring 75.

[0119] Following the process described above, once the press pressure has been set at the operator input unit 96, the display unit 961 shows the upper and lower limits of the press pressure set in step S13 and the settable numerical value range (resolution) of the press pressure. At this time, the press pressure input is limited to a range from the lower limit to the upper limit to be displayed, and the numerical value input is accepted in units of the settable numerical value range of the press pressure.

[0120] Furthermore: when the pressing pressure of the press foot 71 is set, the control unit 90 refers to the table data selected in step S11, drives the transport motor 73 at the shaft angle at which the set pressing pressure is obtained, and controls the transport motor to maintain the shaft angles. [Change of parameters depending on a run over stepped sewing material]

[0121] In the above description, when the presser height detection unit 76 detects that the presser foot 71 runs over a stepped part where the material being sewn becomes thicker (a thicker area), the control unit 90 then takes steps to change parameters relating to sewing, as described below.

[0122] During sewing, the control unit 90 monitors, by means of the line sensor 762 in the presser foot mechanism 70, whether the presser foot 71 is in a position below the prescribed height relative to the stitch plate 11. If it is detected that the presser foot 71 is in a position equal to or higher than the prescribed height, the control unit determines that a stepped section is present. [1. Change in printing pressure]

[0123] When the press height detection unit 76 detects that the press foot 71 is running over the stepped part, the control device 90 first controls the transport motor 73 in such a way that the pressing pressure of the press foot 71 is corrected to be stronger.

[0124] In this way, when the detection that the presser foot 71 is running over the stepped part increases the pressing pressure of the presser foot 71, the strong pressing pressure is applied to the presser foot 71 running over the stepped part, so that the material to be sewn can be sewn satisfactorily while it is held between the presser foot 71 and the feed dog 31. [2nd change in carrier height]

[0125] Next: when the press height detection unit 76 detects that the press foot 71 is running over the stepped part, the control device 90 controls the vertical transport motor 66 in such a way that the height of the conveyor 31 is corrected to be higher in a transport section.

[0126] In this way, if the height of a tooth tip of the feed dog 31 is raised in the transport section by the detection that the presser foot 71 is running over the stepped part, the feed dog 31 is raised in accordance with the running of the presser foot 71 over the stepped part, so that the material to be sewn can be sewn satisfactorily while being held in a state in which the distance between the presser foot 71 and the feed dog 31 is maintained uniformly. [3. Change in thread tension]

[0127] Next: when the presser height detection unit 76 detects that the presser foot 71 is running over the stepped part, the control device 90 controls the current value of the solenoid in such a way that the thread tension of the thread tensioner 101 is corrected to be stronger.

[0128] In this way, when the thread tension of the thread tensioner 101 increases due to the detection that the presser foot 71 is running over the stepped part, loosening of the thread is prevented, so that sewing can be carried out satisfactorily. [Effect of the embodiment]

[0129] As described above, in the sewing machine 100 according to the embodiment, the horizontal feed mechanism 40 comprises the feed adjustment motor 57, which changes and adjusts the amount of operation (the division) of the horizontal back-and-forth movement imparted to the feed dog support 32 by the sewing machine motor 16; the vertical feed mechanism 60B comprises the vertical feed motor 66, which serves as a drive source for the vertical back-and-forth movement imparted to the feed dog support 32; and the control device 90 is included to control the feed adjustment motor 57 and the vertical feed motor 66, thereby causing the feed dog 31 to carry out the transport of a workpiece.

[0130] For this reason, because the vertical back-and-forth movement of the feed dog 31 can be adjusted arbitrarily without restriction by the sewing machine motor 16, it is possible to cause the feed dog 31 to move in a circular motion along a variety of different path patterns, as described above.

[0131] Regarding the horizontal reciprocating movement of the feed dog 31, it is also possible to obtain some of the various path patterns of the feed dog 31 described above when using an additional motor independent of the sewing machine motor 16 as the drive source. However, since the reciprocating stroke in the horizontal direction is much greater than the reciprocating stroke in the vertical direction, a motor with lower inertia and higher output power is required. Since the inertia of a motor tends to increase with increasing output power, such a motor with lower inertia and higher output power is practically difficult to obtain. It is therefore essential to reduce the sewing speed and perform the feed operation at a reduced sewing speed.

[0132] On the other hand, because the sewing machine 100, according to the embodiment, uses the sewing machine motor 16 as a drive source for the horizontal reciprocating movement of the feed dog 31 and the vertical feed motor 66 as a drive source for the vertical reciprocating movement of the feed dog 31, it is possible to impart a reciprocating movement in the vertical direction to the feed dog 31 within a narrow reciprocating stroke range. Furthermore, a compact motor, which is readily available and has a low output power, can be used as the vertical feed motor 66. It is also possible to perform the feed with a wider variety of path patterns for the feed dog 31.

[0133] Furthermore, the sewing division can be set with high reliability, stability and accuracy using a combination of the feed adjustment body 55 and the feed adjustment motor 57, which have been used previously.

[0134] The control unit 90 of the sewing machine 100 then controls the feed motor 73 such that the presser foot 71 is lowered from a position in which it is spaced upwards from the needle plate 11. Furthermore, the control unit 90 has a spring type identification function for determining – based on a reaction force received by the presser spring 75 during the lowering operation of the presser foot 71 – whether the presser spring 75 is any of the multiple types of presser springs 75 with different spring constants, and thus the control unit 90 can specify a type of interchangeable presser spring 75.

[0135] As a result, it is possible to identify and use the types of multiple presser springs 75 with different spring constants, to set the press pressure arbitrarily with a wide spring pressure range, and to perform sewing on many types of workpieces.

[0136] Furthermore, the EEPROM 94 of the control unit 90 stores the table data, which individually correspond to each of the multiple types of press springs 75 with different spring constants and specify the relationship between the operation amount of the transport motor 73 and the pressing pressure generated in the press foot 71, and the CPU 91 performs a setting control of the pressing pressure based on the table data, which corresponds to the press spring 75 specified using the spring type identification function, whereby the appropriate pressing pressure can be set automatically without the setting input of the type of press spring 75.

[0137] Furthermore, the control unit 90 controls the display unit 961 of the operating input unit 96 in such a way that the settable upper limit of the spring pressure and the settable numerical value range (resolution) of the spring pressure can be variably entered according to the press spring 75 specified by the spring type identification function, whereby the appropriate press pressure can be set without having to enter the type of the press spring 75.

[0138] In particular, when the presser height detection unit 76 detects that the presser foot 71 is running over a stepped section where the material being sewn becomes thicker (over a thicker area), the control unit 90 changes the parameters relating to the sewing. Thus, even when the presser foot 71 is running over the stepped section, the material can be sewn satisfactorily while it is held between the presser foot 71 and the feed dog 31.

[0139] This means that if the pressing pressure of the presser foot 71 increases due to the detection that the presser foot 71 is running over the stepped part, the strong pressing pressure is exerted on the presser foot 71 running over the stepped part, so that the material to be sewn can be sewn satisfactorily while it is held between the presser foot 71 and the feed dog 31.

[0140] Furthermore: if the height of the feeder 31 is raised in the transport section due to the detection that the presser foot 71 runs over the stepped part, the feeder 31 is raised in accordance with the movement of the presser foot 71 over the stepped part, so that the material to be sewn can be sewn satisfactorily while being held in a state in which the distance between the presser foot 71 and the feeder 31 is maintained uniformly.

[0141] Furthermore: if, due to the detection that the presser foot 71 runs over the stepped part, the thread tension of the thread tensioner 101 increases, loosening of the thread is prevented, so that sewing can be carried out more satisfactorily. [Miscellaneous]

[0142] In the embodiment of the invention described above, upon detection that the press foot 71 is running over the stepped section, the pressing force of the press foot 71 is increased. However, the transport motor 73 can be controlled to reduce the pressing force of the press foot immediately after the press foot 71 begins its movement over the stepped section, and to increase the pressing force of the press foot 71 after a predetermined time has elapsed.

[0143] Furthermore, upon detection that the presser foot 71 is running over the stepped part, the sewing machine motor 16 can be controlled to slow down the rotational speed of the main shaft in addition to the parameter change described above.

[0144] In the embodiment of the invention described above, the lockstitch sewing machine is described by way of example; however, the transport device 30 can be applied to any type of sewing machine which transports the workpiece with the feed dog.

[0145] In the described embodiment of the invention, the case is described by way of example in which the first connecting element 61B is directly attached to and connected with the output shaft of the vertical transport motor 66. However, the output shaft of the vertical transport motor 66 and the first connecting element 61B can also be indirectly connected to each other via a transfer element or a transmission mechanism.

[0146] Furthermore, it is understood that modifications and changes to other specific detailed structures are possible.

Claims

[1] Sewing machine (100), comprising: a needle vertical movement mechanism which moves a needle bar up and down; a sewing machine motor (16) which drives the needle vertical movement mechanism as a drive source; a transporter holder (32) which holds a transporter (31) which transports a workpiece on a needle plate (11); a horizontal transport mechanism (40) which receives a driving force from the sewing machine motor (16) and transmits a horizontal back-and-forth movement to the feed dog support (32); a vertical transport mechanism (60B) which imparts a vertical back-and-forth movement to the transporter holder (32); a press foot (71) which presses the workpiece from above; and a press height detection unit (76) which detects a height of the press foot (71), wherein the horizontal transport mechanism (40) includes a transport adjustment motor (57) which changes and adjusts the division of the horizontal reciprocating movement by the sewing machine motor (16) with respect to the feed dog support (32), the vertical transport mechanism (60B) comprises a vertical transport motor (66) which provides the vertical reciprocating movement with respect to the feed dog support (32) as a drive source, and wherein the sewing machine (100) comprises a control device (90) which controls the vertical transport motor (66) to increase the height of the feed dog (31) in a transport section when the presser height detection unit (76) detects that the presser foot (71) is running over a stepped part of a thicker area of ​​the workpiece. [2] Sewing machine according to claim 1, further comprising: a press rod (72) which holds the press foot (71) at a lower end of the press rod (72); a press spring (75) which exerts a pressing force on the workpiece through the press rod (72) onto the press foot (71); and a transport motor (73) which performs a lifting and lowering operation of the press foot (71) and which adjusts the pressing pressure with respect to the workpiece through the press foot (71) by adjusting an expansion amount of the press spring (75), wherein the control unit (90) controls the transport motor (73) to exert a stronger pressing pressure of the press foot (71) with respect to the workpiece when the press height detection unit (76) detects that the press foot (71) is running over the stepped part of the thicker area of ​​the workpiece. [3] Sewing machine according to claim 1 or 2, wherein the presser height detection unit (76) comprises: a detection object (761) which moves up and down together with the presser foot (71); and a line sensor (762) which optically detects a height of the detection object (761). [4] Sewing machine according to any one of claims 1 to 3, further comprising: a thread tensioner (101) which applies tension to a thread to be sewn onto the workpiece and changes this tension by controlling a current value of a solenoid, wherein the control unit (90) controls the thread tensioner (101) to impart a stronger voltage to the thread by controlling the current value of the solenoid when the presser height detection unit (76) detects that the presser foot (71) is running over the stepped part.

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